Note: Descriptions are shown in the official language in which they were submitted.
CA 02346111 2001-04-02
WO 00/Z1900 PCT/US99/21443
-1-
GLASS FIBER-REINFORCED PREPREGS, LAMINATES, ELECTRONIC
CIRCUIT BOARDS AND METHODS FOR ASSEMBLING A FABRIC
Cross Reference to Related Applications
This patent application is a continuation-in-part of U.S. Patent
Application Serial No. 09/170,578 of B. Novich et al. entitled "Glass Fiber-
Reinforced Laminates, Electronic Circuit Boards and Methods for Assembling
a Fabric", filed October 13, 1998, viihich is a continuation-in-part of U.S.
Patent Application Serial No. 09/130,270 of B. Novich et al. entitled "Glass
Fiber-Reinforced Laminates, Electronic Circuit Boards and Methods for
Assembling a Fabric", filed August 6, 1998, now abandoned, which is a
continuation-in-part application of U.S. Serial No. 09/034,525 of B. Novich et
al. entitled "Inorganic Lubricant-Coated Glass Fiber Strands and Products
Including the Same" filed March 3, 1998, now abandoned. This application is
also a continuation-in-part of U.S. Patent Application Serial No. 09/170,780
of
B. Novich et al. entitled "Inorganic Lubricant-Coated Glass Fiber Strands and
Products Including the Same" filed October 13, 1998, which is a continuation-
in-part application of U.S. Patent Application Serial No. 09/034,525 of B.
Novich et al. entitled "Inorganic Lubricant-Coated Glass Fiber Strands and
Products Including the Same" filed March 3, 1998, now abandoned. This
application is also a continuation-in-part of U.S. Patent Application Serial
No.
09/170,781 of B. Novich et al. entitled "Glass Fiber Strands Coated With
Thermally Conductive Inorganic Solid Particles and Products Including the
Same" filed October 13, 1998, which is a continuation-in-part application of
U.S. Application Serial No. 09/034,663 filed March 3, 1998, now abandoned.
This patent application is related to U.S. Patent Application Serial No.
09/170,579 of B. Novich et al. entitled "Methods for Inhibiting Abrasive Wear
of Glass Fiber Strands" filed October 13, 1998, which is a continuation-in-
part
application of U.S. Patent Application Serial No. 09/034,078 filed March 3,
1998, now abandoned; U.S. Patent Application Serial No. 09/170,566 of B.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99r11443
_2_
Novich et al. entitled "Impregnated Glass Fiber Strands and Products
Including the Same" filed October 13, 1998, which is a continuation-in-part
application of U.S. Patent Application Serial No. 09/034,077 filed March 3,
1998, now abandoned; and U.S. Patent Application Serial No. 09/170,565 of
B. Novich et al. entitled "Inorganic Particle-Coated Glass Fiber Strands and
Products Including the Same" filed October 13, 1998, which is a continuation-
in-part application of U.S. Patent Application Serial No. 09/034,056 filed
March 3, 1998, now abandoned.
This application claims the benefit of U.S. Provisional Application Nos.
60/133,075, filed May 7, 1999; 60/133,076, filed May 7, 1999, and
60/146,337, fled July 30, 1999.
Field of the invention
This invention relates generally to reinforced laminates for electronic
circuit boards and, more particularly, to laminates containing woven fabrics
of
glass fibers having a coating which is compatible with laminate matrix resins
and provides improved drilling properties in the laminate.
Background of the Invention
Electronic circuit boards are typically formed from laminated layers of
resin impregnated fabric composed of reinforcing fibers, such as glass fibers,
which provide dimensional stability to the board to maintain the integrity of
the
electronic circuits mounted thereon. Holes are formed in the laminate by
drilling through the layers of the laminate or support to interconnect
circuits
positioned along different planes of the laminate. It has been observed that
the hardness of the glass fibers in the laminate and the heat generated during
the drilling operation can accelerate the wear of the drill bit. As a result,
the
drill bit will drill fewer holes before drill replacement and/or resharpening
of the
drill tip, and will have a shorter overall useful tool life. In addition, it
has been
observed that the accelerated drill tip wear also effects the locational
CA 02346111 2001-04-02
WO 00/21900 PCT/US99121443
-3-
accuracy of the holes, and in particular the exit end of the hole drilled
through
a laminate.
Typically, the surtaces of glass fibers forming these reinforcing fabrics
of the laminates are coated with a sizing composition in the fiber forming
process to protect the fibers from abrasion during subsequent processing.
For example, starch and oil-based sizing compositions are used to protect
fibers from interfilament and equipment abrasion during fabric weaving which
can contribute to fiber breakage. Organic lubricants, such as alkyl
imidazoline derivatives and amide substituted polyethylene imines, have been
added to sizing compositions to reduce abrasion. However, such organic
lubricants can deteriorate during subsequent processing or cause undesirable
side reactions with other sizing and matrix material components. In addition,
many commonly used sizing components can adversely affect adhesion
between the glass fibers and the laminate matrix material, e.g., starches,
which are commonly used as film formers in textile sizings, are generally not
compatible with the laminate resin matrix material. To avoid incompatibility
between the glass fibers and matrix materials, the coating or sizing
composition is typically removed from the woven cloth prior to lamination by
thermally decomposing the components of the sizing (heat treatment or de-
oiling) or by washing with water or other solution. A conventional heat
cleaning process involves heating the cloth at 380°C for 60-80 hours.
The
cleaned cloth is then re-coated with a silane coupling agent to improve
adhesion between the glass fiber and the matrix resin.
The strength of the glass fibers, and more particularly the flexural
strength of the laminate, can be greatly reduced by these heat cleaning
processes. Heat cleaning of high silica content glass fibers, such as D-glass,
S-glass and Q-glass, is particularly undesirable because of strength loss and
discoloration.
Many coating compositions for glass fibers which require heat or water
cleaning prior to use as a reinforcement in a composite or laminate are
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-4-
disclosed in the art. Japanese Patent Application No. 9-208,268 discloses a
cloth having yarn formed from glass fibers coated immediately after spinning
with starch or a synthetic resin and 0.001 - 20.0 weight percent of inorganic
particles such as colloidal silica, calcium carbonate, kaolin and talc. Heat
or
water de-oiling is required prior to formation of a laminate.
U.S. Patent No. 5,286,562 discloses a textile strand for screen
products which is weaveabie on air jet looms having a coating of at least 45
weight percent wax, lubricants, polyvinyl pyrrolidone and organo silane
coupling agents. U.S. Patent No. 5,038,555 discloses twisted bundles of
glass fibers for screen products which are coated with an aqueous chemical
treating composition having an epoxy film former, emulsifier, lubricant,
organo
functional metallic coupling agent, polyvinyl pyrrolidone, polyethylene and
water.
To avoid heat cleaning glass fiber cloth, Japanese Patent Application
No. 8-119,682 discloses a primary sizing agent for glass fibers containing a
water-soluble epoxy resin and having a pH of 5.5 to 7.5, which facilitates
removal of the sizing with water. Similarly, U.S. Patent No. 5,236,777
discloses methods for producing glass cloth for reinforcing a resin by coating
the glass yarns with a primary sizing having at least one water-soluble film
forming agent selected from the group consisting of an amine-modified epoxy
resin, an ethylene oxide-added epoxy resin and ethylene oxide-added
bisphenol A, silane coupling agent and lubricant, water washing the yarns to
reduce the amount of primary sizing to less than 0.25 weight percent LOI and
treating with a secondary sizing agent. Japanese Patent Application No. 9-
268,034 discloses binders for twist-free glass fiber yarn including a water-
soluble urethane compound and/or a water-soluble epoxy product modified by
addition reaction with a polyhydric alcohol.
U.S. Patent No. 4,933,381 discloses a resin-compatible size
composition for glass fibers containing an epoxy film-former, non-ionic
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-5-
lubricant, cationic lubricant, silane coupling agent and an acid such as
acetic
or citric acid.
Japanese Patent Application No. 8-325,950 discloses a glass fiber
sizing agent including as essential components polyvinyl pyrrolidone, a water-
soluble epoxy resin amine addition product and a silane coupling agent which
do not require heat removal from finished glass cloth.
Japanese Patent Application No. 7-102,483 discloses a warp
secondary sizing agent for glass fiber for weaving glass cloth that does not
require heat oil removal. The warp secondary sizing agent is composed
mainly of polyvinyl pyrrolidone and contains an additive such as high
molecular weight polyethylene oxide. A water-soluble epoxy resin can be
included as a binding component.
An inert lubricant for inhibiting abrasion of glass fibers which does not
appreciabty deteriorate during processing, improves the drilling properties of
a
laminate incorporating the glass fiber, and which is compatible with polymeric
matrix materials is desirable. However, use of inorganic materials has mainly
focused on fillers for modifying general physical characteristics of
composites
rather than improving abrasion-resistance characteristics of reinforcement
fibers.
U.S. Patent No. 4,869,954 discloses a sheet-like, thermally conductive
material formed of a urethane binder, curing agent and thermally conductive
fillers such as aluminum oxide, aluminum nitride, boron nitride, magnesium
oxide and zinc oxide and various metals (see col. 2, lines 62-65 and col. 4,
lines 3-10). One or more layers of a support material, such as glass fiber
cloth, can be included in the thermally conductive material.
U.S. Patent No. 3,312,569 discloses adhering particles of alumina to
the surfaces of the glass fibers and Japanese Patent Application No. 9-
208,268, as discussed earlier, discloses a cloth having yarn formed from
glass fibers coated immediately after spinning with starch or a synthetic
resin
and inorganic particles such as colloidal silica, calcium carbonate, kaolin
and
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-6-
talc to improve penetration of resin between glass reinforcement fibers during
formation of a composite. However the Mohs' hardness values of alumina
and silica are greater than about 9 and about 7', respectively, which can
cause abrasion of softer glass fibers.
U.S. Patent No. 5,541,238 discloses a fiber for reinforcing
thermoplastic or thermoset composites which is coated by vapor deposition or
plasma process with a single layer of an ultrafine material such as inorganic
oxides, nitrides, carbides, borides, metals and combinations thereof having an
average particle diameter of 0.005-1 micrometer. Limited space and
environmental considerations make the use of vapor deposition or plasma
processes under a glass fiber production bushing impractical.
Soviet Union No. 859400 discloses an impregnating composition for
manufacturing laminates of glass fiber cloth, the composition containing an
alcoholic solution of phenol-formaldehyde resin, graphite, molybdenum
disulfide, polyvinyl butyral and surfactant. Volatile alcoholic solvents are
not
desirable for glass fiber production applications.
U.S. Patent No. 5,217,778 discloses a dry clutch facing including a
composite yarn of glass fibers, metallic wire and polyacrylonitrile fibers
which
are impregnated and coated with a heat curable cement or binder system.
The binder can include friction particles such as carbon black, graphite,
metal
oxides, barium sulfate, aluminum silicate, ground rubber particles, ground
organic resins, polymerized cashew nut oil, clay, silica or cryolite (see col.
2,
lines 55-66) to modify frictional characteristics of a composite.
There is a need for lubricant coatings for glass fibers which are
compatible with a variety of polymeric matrix materials, that reduce drill tip
wear and improve the locational accuracy of drilled holes. In addition, it
' See R. Weast (Ed.), Handbook of Chemistnr and Physics, CRC Press (1975) at
page F-22
and H. Katz et al. (Ed.), Handbook of Fillers and Plastics, (1987) at page 28,
which are hereby
incorporated by reference.
CA 02346111 2001-04-02
WO 00/21900 PCT/ITS99I21443
_7_
would be particularly advantageous if the coating was also compatible with
modern air jet weaving equipment to increase productivity.
Summary of the Invention
One aspect of the present invention is a prepreg for an electronic
support, the prepreg comprising: (a) a polymeric matrix material; and (b) a
fabric comprising a strand comprising glass fibers, at least a portion of the
fabric having a coating which is compatible with the polymeric matrix
material,
the prepreg having a drill tip percent wear of no greater than about 32
percent, as determined after drilling 2000 holes through a stack of 3
laminates, each laminate including eight of the prepregs, at a hole density of
62 holes per square centimeter (400 holes per square inch) and a chip load of
0.001 with a 0.46 mm (0.018 inch) diameter tungsten carbide drill. The
present invention also provides a laminate incorporating the prepreg.
Another aspect of the present invention is a prepreg for an electronic
support, the prepreg comprising: (a) a polymeric matrix material; and (b) a
woven reinforcement fabric comprising a glass fibers, at least a portion of
the
fabric having a coating which is compatible with the polymeric matrix
material,
the prepreg having a deviation distance of no greater than about 36
micrometers, as determined after drilling 2000 holes through a stack of 3
laminates at a hole density of 62 holes per square centimeter (400 holes per
square inch) and a chip load of 0.001 with a 0.46 mm {0.018 inch) diameter
tungsten carbide drill. The present invention also provides a laminate
incorporating the prepreg.
Brief Description of the Drawings
The foregoing summary, as well as the following detailed description of
the preferred embodiments, will be better understood when read in
conjunction with the appended drawings. In the drawings:
CA 02346111 2001-04-02
WO 00/21900 PCT/US99r11443
_g_
Figure 1 is a cross-sectional view of a reinforced laminate according to
the present invention;
Figure 2 is a top plan view of one embodiment of a fabric incorporating
features of the present invention;
Figure 3 is a perspective view of a coated fiber strand according to the
present invention;
Figure 4 is a cross-sectional view of an alternative embodiment of a
reinforced laminate according to the present invention;
Figure 5 is a cross-sectional view of an electronic support according to
the present invention;
Fig. 6 is a schematic diagram of a method for forming an aperture in a
layer of fabric of an electronic support;
Figure 7 is an end view of a drill illustrating the primary cutting edge.
Figure 8 is a schematic of a drill hole pattern.
Detailed Description of the Invention
The laminates of the present invention are reinforced with fabric
comprising coated fiber strands, and preferably woven fabric comprising
coated glass fiber strands, which can provide the laminate with low
coefficient
of thermal expansion, good flexural strength, thermal stability, hydrolytic
stability, low corrosion and reactivity in the presence of high humidity,
reactive
acids and alkalies. The coated glass fiber strands are compatible with a
variety of polymeric matrix materials, which can eliminate the need for heat
or
water cleaning of the glass fiber fabric prior to lamination.
Another significant advantage of the laminates of the present invention
is that they exhibit improved drillability, i.e. reduced drill tip wear and/or
improved drilled hole location accuracy, especially when the laminate is being
used as an electronic support. As used herein, "electronic support" means a
structure that mechanically supports and/or electrically interconnects
elements including but not limited to active electronic components, passive
CA 02346111 2001-04-02
WO 00/21900 PCT/US99I21443
-9-
electronic components, printed circuits, integrated circuits, semiconductor
devices and other hardware associated with such elements, such as but not
limited to connectors, sockets, retaining clips and heat sinks.
Another advantage of the laminates of the present invention is that
they can be fabricated from fiber strands that are suitable for use in an air
jet
weaving process. As used herein, "air jet weaving" means a type of fabric
weaving in which the fill yarn (weft) is inserted into the warp shed by a
blast of
compressed air from one or more air jet nozzles.
Referring now to the Figures, wherein like numerals indicate like
elements throughout, Fig. 1 shows a laminate 10 according to the present
invention. The laminate 10 comprises a polymeric matrix material 12
(discussed in detail below) which is reinforced by a reinforcement fabric 14.
Fabric 14 can be a woven or nonwoven fabric, such as but not limited to a knit
fabric or mat, formed by any suitable knitting, weaving or mat producing
process. Preferably the fabric 14 is a woven fabric formed by an air jet
weaving process, which is well know to those skilled in the art. The laminate
10 can also be a unidirectional laminate wherein most of the fibers, yarns or
strands in each layer of fabric are oriented in the same direction.
Typically, a laminate includes multiple prepregs with each prepreg
incorporating fabric 14 and a partially cured polymeric matrix 12, as will be
discussed later in more detail. The number of prepregs in a laminate can
range from one to about 40. For clarity in the figures, only a single prepreg
is
shown in the laminate 10.
Referring now to Figs. 2 and 3, the fabric 14 comprises one or more
coated fiber strands 16. As used herein, the term "strand" means a plurality
of individual fibers. The term "fiber" means an individual filament.
The glass fibers 18 can be formed from any type of fiberizable glass
composition known to those skilled in the art, including those prepared from
fiberizable glass compositions such as "E-glass", "A-glass", "C-glass", "D-
glass", "Q-glass", "R-glass", "S-glass" and E-glass derivatives. As used
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
- 10-
herein, the term ufiberizable" means a material capable of being formed into a
generally continuous filament, fiber, strand or yam. As used herein, "E-glass
derivatives" means glass compositions that include minor amounts of fluorine
and/or boron and preferably are fluorine-free and/or boron-free. Furthermore,
as used herein, minor means less than about 1 weight percent fluorine and
less than about 5 weight percent boron. Basalt and mineral wool materials
are examples of other fiberizable glass materials useful in the present
invention. Preferred glass fibers are formed from E-glass or E-glass
derivatives. Such compositions are well known to those skilled in the art and
further discussion thereof is not believed to be necessary in view of the
present disclosure. The glass fibers of the present invention can be formed
in any suitable method known in the art, for forming glass fibers. For
example, glass fibers can be formed in a direct-melt fiber forming operation
or
in an indirect, or marble-melt, fiber forming operation. In a direct-melt
fiber
forming operation, raw materials are combined, melted and homogenized in a
glass melting furnace. The molten glass moves from the furnace to a
forehearth and into fiber forming apparatus where the molten glass is
attenuated into continuous glass fibers. In a marble-melt glass forming
operation, pieces or marbles of glass having the final desired glass
composition are preformed and fed into a bushing where they are melted and
attenuated into continuous glass fibers. If a premelter is used, the marbles
are fed first into the premelter, melted, and then the melted glass is fed
into a
fiber forming apparatus where the glass is attenuated to form continuous
fibers. In the present invention, the glass fibers are preferably formed by
the
direct-melt fiber forming operation. For additional information relating to
glass
compositions and methods of forming the glass fibers, see K. Loewenstein,
The Manufacturing Technology of Glass Fibres, (3d Ed. 1993) at pages 30-
44, 47-60, 115-122 and 126-135, U.S. Patents 4,542,106 and 5,789,329, and
IPC-EG-140 "Specification for Finished Fabric Woven from 'E' Glass for
Printed Boards" at page 1, a publication of The Institute for Interconnecting
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-11 -
and Packaging Electronic Circuits (June 1997), which are hereby
incorporated by reference.
The glass fibers can have a nominal filament diameter ranging from
about 3.0 to about 35.0 micrometers (corresponding to a filament designation
of B through U and above), and preferably have a nominal filament diameter
ranging from about 5.0 to about 30.0 micrometers. For fine yarn applications,
the average nominal filament diameter preferably in the range of about 5 to
about 7 micrometers. The number of fibers per strand can range from about
2 to about 15,000, and is preferably about 100 to about 7000. For further
information regarding nominal filament diameters, and designations of glass
fibers, see Loewenstein at pages 25 and 27, which are hereby incorporated
by reference.
In addition to glass fibers, the coated fiber strand 1fi can further
comprise fibers 20 formed from other fiberizable inorganic materials,
fiberizable organic materials, and mixtures and combinations thereof. The
inorganic and organic materials can be either man-made or naturally
occurring materials. It will be appreciated by one skilled in the art that the
fiberizable inorganic and organic materials can also be polymeric materials.
As used herein the term "polymeric material" means a material formed from
macromolecules composed of long chains of atoms that are linked together
and that can become entangled in solution or in the solid state2.
Non-limiting examples of suitable non-glass fiberizable inorganic
materials include ceramic materials such as silicon carbide, carbon, graphite,
muliite, aluminum oxide and piezoelectric ceramic materials. Non-limiting
examples of suitable fiberizable organic materials include cotton, cellulose,
natural rubber, flax, ramie, hemp, sisal and wool. Non-limiting examples of
suitable fiberizable organic polymeric materials include those formed from
polyamides (such as nylon and aramids), thermoplastic polyesters (such as
' James Mark et al. Inor4anic Polymers, Prentice Hall Polymer Science and
Engineering
Series, (1992) at page 1 which is hereby incorporated by reference.
CA 02346111 2001-04-02
wo ooni9oo Pcrn.rs9vni4a3
- 12-
polyethylene terephthalate and polybutylene terephthalate), acrylics (such as
polyacrylonitriles), polyolefins, polyurethanes and vinyl polymers (such as
polyvinyl alcohol). Non-glass fiberizable materials useful in the present
invention and methods for preparing and processing such fibers are
discussed at length in the Encyclopedia of Polymer Science and Technology,
Vol. 6 (1967) at pages 505-712, which is hereby incorporated by reference. It
is understood that blends or copolymers of any of the above materials and
combinations of fibers formed from any of the above materials can be used in
the present invention, if desired.
The present invention will now be discussed generally in the context of
glass fiber strands, although one skilled in the art would understand that the
strand 16 can additionally include one or more of the non-glass fibers
discussed above.
Although not limiting in the present invention, in the embodiment of the
fabric 14 shown in Fig. 2, at least one and preferably all the fibers 18 of
the
strand 16 are coated with a layer 22 of a coating composition applied to at
least a portion of a surface of the fibers 18 to protect the fiber surface
from
abrasion during processing and inhibit fiber breakage. Preferably the coating
composition is applied to the entire outer surface or periphery of the each of
the fibers 18 of the strand 16 as shown in Fig. 3.
The coating composition useful in the present invention are present
upon the fibers as a sizing (preferred), a secondary coating applied over a
sizing and/or a tertiary or outer coating, as desired. As used herein, the
terms
"size", "sized" or "sizing" refer to the coating composition applied to the
fibers
immediately after formation of the fibers. In an alternative embodiment, the
terms "size", "sized" or "sizing" additionally refer to the coating
composition
(also known as a "finishing size") applied to the fibers after at least a
portion,
and typically all of a conventional primary coating composition has been
removed by heat, water or chemical treatment, i.e., a finishing size which is
applied to bare glass fibers incorporated into a fabric form. The term
CA 02346111 2001-04-02
WO 00/21900 PCTNS99/21443
-13-
"secondary coating" refers to a coating composition applied secondarily to
one or a plurality of strands after a sizing composition is applied, and
preferably at least partially dried. This coating can be applied to the fiber
before the fiber is incorporated into a fabric or it can be applied to the
fiber
after the fiber is incorporated into a fabric , e.g. by coating the fabric.
The coating compositions useful in the present invention are preferably
aqueous coating compositions. Although not preferred for safety reasons,
the coating compositions can contain volatile organic solvents such as
alcohol or acetone as needed, but preferably are free of such solvents.
The coating composition useful in the present invention comprises one
or more polymeric materials, such as thermosetting materials or thermoplastic
materials, which are compatible with the polymeric matrix material 12 of the
laminate 10, i.e., the components of the coating composition facilitate wet-
out
and wet-through of the matrix material upon the fiber strands and provide
adequate physical properties in the composite. Preferably the polymeric
materials form a generally continuous film when applied to the surface of the
fibers 18. The polymeric materials can be water soluble, emulsifiable,
dispersible and/or curable. As used herein, the phrase "compatible with the
polymeric matrix material" means that the components of the coating
composition applied to the glass fibers facilitate wet-through and wet-out of
the matrix material upon the fiber strands, provide adequate physical
properties in the composite, are chemically compatible with the polymeric
matrix material, provide good hydrolytic stability, i.e. resistance to water
migration along the fiber surface/matrix material interface, and the coating
components (or selected coating components) do not require removal prior to
incorporation of the coated fiber into the polymeric matrix material. The
measure of the penetration of the polymeric matrix material through a mat or
fabric is referred to as "wet-through". The measure of the flowability of the
polymeric matrix material through the glass fiber strands to obtain
essentially
CA 02346111 2001-04-02
WO 00/21900 PGT/US99/21443
- 14-
complete encapsulation of the entire surface of each glass fiber by the
polymeric matrix material is referred to as "wet-out".
In one embodiment of the invention, the coating composition applied to
fibers 18 that are incorporated into laminate 10 comprises one or more
polymeric film forming materials which are compatible with a thermosetting
matrix material such as are used to form laminates for printed circuit boards
or printed wiring boards {hereinafter individually and collectively referred
to as
"electronic circuit boards"), for example FR-4 epoxy resins, which are
polyfunctional epoxy resins, and in one particular embodiment of the
invention, is a difunctional brominated epoxy resins, and polyimides. See 1
Electronic Materials Handbook, ASM International (1989) at pages 534-537,
which are hereby incorporated by reference.
Nonlimiting examples of useful polymeric film forming materials include
thermoplastic polymeric materials such as thermoplastic polyesters, vinyl
polymers, polyolefins, polyamides (e.g. aliphatic polyamides or aromatic
polyamides such as aramid), thermoplastic polyurethanes, acrylic polymers
and mixtures thereof which are compatible with a thermosetting matrix
material. Nonlimiting examples of thermoplastic polyesters include
DESMOPHEN 2000 and DESMOPHEN 2001 KS, both of which are
commercially available from Bayer of Pittsburgh, Pennsylvania, RD-847A
polyester resin which is commercially available from Borden Chemicals of
Columbus, Ohio, and DYNAKOLL SI 100 resin which is commercially
available from Eka Chemicals AB, Sweden. Useful polyamides include the
VERSAMID products that are commercially available from General Mills
Chemicals, inc. Useful thermoplastic polyurethanes include WITCOBOND~
W-290H that is commercially available from Witco Chemical Corp. of
Chicago, Illinois and RUCOTHANE~ 2011 L polyurethane latex that is
commercially available from Ruco Polymer Corp. of Hicksville, New York.
Nonlimiting examples of useful thermosetting polymeric materials
include thermosetting polyesters, epoxy materials, vinyl esters, phenolics,
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-15-
aminoplasts, thermosetting polyurethanes and mixtures thereof which are
compatible with a thermosetting matrix material. Suitable thermosetting
polyesters can include STYPOL polyesters that are commercially available
from Cook Composites and Polymers of Port Washington, Wisconsin and
NEOXIL polyesters that are commercially available from DSM B.V. of Como,
Italy.
Useful epoxy materials contain at least one epoxy or oxirane group in
the molecule, such as polyglycidyl ethers of polyhydric alcohols or thiols.
Examples of suitable epoxy polymers include EPON~ 826 and EPON~ 880
epoxy resins, which are epoxy functional polyglycidyl ethers of bisphenol A
commercially available from Shell Chemical Company of Houston, Texas. In
one embodiment of a coating composition, the coating composition is
essentially free of epoxy materials, i.e., comprises less than about 5 weight
percent epoxy materials and more preferably less than about 2 weight
percent.
In one nonlimiting embodiment of the coating composition, the coating
composition comprise one or more polyesters (e.g. DESMOPHEN 2000 and
RD-847A) and one or more additional film-forming polymers selected from the
group consisting of vinyl pyrrolidone polymers (preferred), vinyl alcohol
polymers and/or starches. Vinyl pyrrolidone polymers useful in the present
invention include polyvinyl pyrrolidones such as PVP K-15, PVP K-30, PVP K-
60 and PVP K-90, each of which are commercially available from ISP
Chemicals of Wayne, New Jersey. Other suitable vinyl polymers include
Resyn 2828 and Resyn 1037 vinyl acetate copolymer emulsions, which are
commercially available from National Starch and Chemical of Bridgewater,
New Jersey. Useful starches include those prepared from potatoes, corn,
wheat, waxy maize, sago, rice, milo and mixtures thereof, such as
KOLLOTEX 1250 (a low viscosity, low amylose potato-based starch etherified
with ethylene oxide) which is commercially available from AVEBE of the
Netherlands. The amount of additional polymer is preferably less than about
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
- 1fi -
20 weight percent, and more preferably ranges from about 0.1 to about 5
weight percent. Preferably, the coating composition is essentially free of
starch, i.e., contains less than about 5 weight percent starch and more
preferably is free of starch, which is often incompatible with the matrix
material.
The coating composition can comprise a mixture of one or more
thermosetting polymeric materials with one or more thermoplastic polymeric
materials. In one embodiment for laminates for electronic circuit boards, the
polymeric materials of the coating composition comprise a mixture of RD-
847A polyester resin or DYNAKOLL SI 100 resin, PVP K-30 polyvinyl
pyrrolidone, DESMOPHEN 2000 polyester and VERSAMID polyamide. In an
alternative embodiment suitable for laminates for printed circuit boards, the
polymeric materials of the aqueous sizing composition comprise PVP K-30
polyvinyl pyrrolidone, optionally combined EPON 826 epoxy resin.
Generally, the amount of polymeric material can range from about 1 to
about 90 weight percent of the coating composition on a total solids basis,
preferably about 1 to about 80 weight percent.
In addition to or in lieu of the polymeric materials discussed above, the
coating composition preferably comprises one or more coupling agents such
as organo silane coupling agents, transition metal coupling agents,
phosphonate coupling agents, aluminum coupling agents, amino-containing
Werner coupling agents and mixtures thereof. These coupling agents
typically have dual functionality. Each metal or silicon atom has attached to
it
one or more groups which can either react with or compatibilize the fiber
surface and/or the components of the polymeric matrix. As used herein, the
term "compatibilize" means that the groups are chemically attracted to the
fiber surface and/or the components of the coating composition, for example
by polar, wetting or solvation forces. In one nonlimiting embodiment, each
metal or silicon atom has attached to it one or more hydrolyzable groups that
allow the coupling agent to react with the glass fiber surface, and one or
more
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-17-
functional groups that allow the coupling agent to react with components of
the polymeric matrix. Examples of hydrolyzable groups include:
O H O R3
II I II I
-OR', -O-C-R2, -N-C-R2, -O-N=C-R4, -O-N=CRS, and
the monohydroxy and/or cyclic C2 C3 residue of a 1,2- or 1,3 glycol, wherein
R' is C,-C3 alkyl; RZ is H or C,-C, alkyl; R3 and R4 are independently
selected
from H, C,-C4 alkyl or Ce-CB aryl; and R5 is C4 C, alkylene. Examples of
suitable compatibilizing or functional groups include epoxy, glycidoxy,
mercapto, cyano, allyl, alkyl, urethano, halo, isocyanato, ureido,
imidazolinyl,
vinyl, acrylato, methacrylato, amino or polyamino groups.
Functional organo-silane coupling agents are preferred for use in the
present invention. Examples of useful functional organo-silane coupling
agents include gamma-aminopropyltrialkoxysiianes, gamma-
isocyanatopropyltriethoxysilane, vinyl-trialkoxysilanes,
glycidoxypropyltrialkoxysilanes and ureidopropyltrialkoxysilanes. Preferred
functional organo silane coupling agents include A-187 gamma-
glycidoxypropyltrimethoxysilane, A-174 gamma-
methacryloxypropyltrimethoxysilane, A-1100 gamma-
aminopropyltriethoxysilane silane coupling agents, A-1108 amino silane
coupling agent and A-1160 gamma-ureidopropyltriethoxysilane {each of
which are commercially available from OSi Specialties, Inc. of Tarrytown, New
York). The organo-silane coupling agent can be at least partially hydrolyzed
with water prior to application to the fibers, preferably at about a 1:1
stoichiometric ratio or, if desired, applied in unhydrolyzed form. If desired,
the
pH of the water can be modified by the addition of an acid or base to initiate
or speed the hydrolysis of the coupling agent as is well known in the art.
Suitable transition metal coupling agents include titanium, zirconium,
yttrium and chromium coupling agents. Suitable titanate coupling agents and
zirconate coupling agents are commercially available from Kenrich
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-18-
Petrochemical Company. Suitable chromium complexes are commercially
available from E.I. duPont de Nemours of Wilmington, Delaware. The amino-
containing Werner-type coupling agents are complex compounds in which a
trivalent nuclear atom such as chromium is coordinated with an organic acid
having amino functionality. Other metal chelate and coordinate type coupling
agents known to those skilled in the art also can be used herein.
The amount of coupling agent can range from about 1 to about 30
weight percent of the coating composition on a total solids basis, and
preferably about 1 to about 10 weight percent.
Although not limiting in the present invention, in the embodiment of the
coating composition shown in Figure 3, the coating composition of the present
invention comprises one or more particles 24 that when applied to at least
one fiber 18 of strand 16 adheres to the outer surface of the fiber 18 and
provides one or more interstitial spaces 30 between adjacent glass fibers 26,
28 of the strand 16. These interstitial spaces 30 correspond generally to the
average size 32 of the particles 24 positioned between the adjacent fibers.
The particles 24 of the coating composition are preferably discrete
particles. As used herein the term "discrete" means that the particles do not
tend to coalesce or combine to form films under processing conditions, but
instead generally retain their individual shape or form. In addition, the
particles are preferably dimensionally stable. As used herein the term
"dimensionally stable particles" means that the particles will generally
maintain their average particle size and shape under processing conditions,
such as the forces generated between adjacent fibers during weaving, roving
and other processing operations, so as to maintain the desired interstitial
spaces between adjacent fibers 26, 28. In other words, the particles
preferably will not crumble, dissolve or substantially deform in the coating
composition to form a particle having a maximum dimension less than its
selected average particle size under typical glass fiber processing
conditions,
such as exposure to temperatures of up to about 25°C and preferably up
to
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
_ 19_
about 100°C, and more preferably up to about 140°C.
Additionally, the
particles 24 should not substantially enlarge or expand in size under glass
fiber processing conditions and, more particularly, under composite
processing conditions where the processing temperatures can exceed
150°C.
As used herein, the phrase "should not substantially enlarge in size" in
reference to the particles means that the particles should not expand or
increase in size to more than approximately 3 times their initial size during
processing. Preferably, the coating compositions of the present invention are
essentially free of heat expandable hollow particles. As used herein, the term
"heat expandable hollow particles" means hollow particles filled with or
containing a blowing agent, which when exposed to temperatures sufficient to
volatilize the blowing agent expand or substantially enlarge in size. As used
herein the term "essentially free of" means the sizing composition comprises
less than about 20 weight percent of heat expandable hollow particles on a
total solids basis, more preferably less than about 5 weight percent, and most
preferably less than 0.001 weight percent. Furthermore, as used herein, the
term "dimensionally stable" includes both crystalline and non-crystalline
materials.
In addition, although not required, it is preferred that the particles 24
are non-waxy. The term "non-waxy" means the materials from which the
particles are formed are not wax-like. As used herein, the term "wax-like"
means materials composed primarily of unentangled hydrocarbons chains
having an average carbon chain length ranging from about 25 to about 100
carbon atoms3~".
Preferably, the particles 24 in the coating composition are discrete,
dimensionally stable, non-waxy particles. In a specific, nonlimiting
3 L. H. Sperling Introduction of Physical Polymer Science, John Wiley and
Sons, Inc. (1986) at
pages 2-5, which are hereby incorporated by reference.
' W. Pushaw, et al. "Use of Micronised Waxes and Wax Dispersions in Waterborne
Systems"
Polymers. Paint. Colours Journal, V.189, No. 4412 January 1999 at pages 18-21
which are
hereby incorporated by reference.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-20-
embodiment of the present invention, the average particle size 32 of the
particles 24 is at least about 0.1 micrometers, preferably at least about 0.5
micrometers, and ranges from about 0.1 micrometers to about 5 micrometers
and preferably from about 0.5 micrometers to about 3.0 micrometers. In one
embodiment, the particles 24 are at least about 1 micrometer and preferably
in the range of about 1 to about 3 micrometers. In this nonlimiting
embodiment, the particles 24 have an average particle sizes 32 that is
generally smaller than the average diameter of the fibers 18 to which the
coating composition is applied. It has been observed that twisted yarns made
from fiber strands 16 having a layer 22 of a residue of a primary sizing
composition comprising particles 24 having average particles sizes 32
discussed above can provide sufficient spacing between adjacent fibers 26,
28 to permit air jet weavability (i.e. air jet transport across the loom)
while
maintaining the integrity of the fiber strand 16 and providing acceptable "wet-
through" and "wet-out" characteristics when impregnated with a polymeric
matrix material.
In another specific, non-limiting embodiment of the present invention
the average particles size 32 of particles 24 is at least 3 micrometers,
preferably at least about 5 micrometers, and ranges from 3 to about 1000
micrometers, preferably about 5 to about 1000 micrometers, and more
preferably about 10 to about 25 micrometers. Preferably, each of the
particles 24 has a minimum particle size of at least 3 micrometers, and
preferably of at least about 5 micrometers. It is also preferred in this
embodiment that the average particle size 32 of the particles 24 corresponds
generally to the average nominal diameter of the glass fibers. It has been
observed that fabrics made with strands coated with the particles of the sizes
as discussed above exhibit good "wet-through" and "wet-out" characteristics
when impregnated with a polymeric matrix material.
It will be recognized by one skilled in the art that mixtures of one or
more particles 24 having different average particle sizes 32 can be
CA 02346111 2001-04-02
WO 00/Z1900 PCT/tTS99/21443
-21 -
incorporated into the sizing composition in accordance with the present
invention to impart the desired properties and processing characteristics to
the fiber strands 16 and to the products subsequently made therefrom. More
specifically, different sized particles can be combined in required amounts so
as to provide fibers having good air jet transport properties as well a fabric
exhibiting good wet-out and wet-through characteristics.
Although not limiting in the present invention, the configuration or
shape of the particles 24 can be generally spherical (such as beads,
microbeads or solid hollow spheres), cubic, platy or acicular (elongated or
fibrous), as desired. In addition, the particles 24 can have a structure that
is
hollow, porous, or void free, or a combination thereof. In addition, the
particles 24 can have a combination of these structures, e.g. a hollow center
with porous or solid walls. For more information on suitable particle
characteristics, see H. Katz et al. (Ed.), Handbook of Fillers and Plastics
(1987) at pages 9-10, which are hereby incorporated by reference.
Glass fibers are subject to abrasive wear by contact with asperities of
adjacent glass fibers and/or other solid objects or materials which the glass
fibers contact during forming and subsequent processing, such as weaving or
roving. "Abrasive wear", as used herein, means scraping or cutting off of bits
of the glass fiber surface or breakage of glass fibers by frictional contact
with
particles, edges or entities of materials which are hard enough to produce
damage to the glass fibers. See K. Ludema, Friction. Wear, Lubrication,
(1996) at page 129, which is hereby incorporated by reference. Abrasive
wear of glass fiber strands causes strand breakage during processing and
surface defects in products such as woven cloth and composites, which
increases waste and manufacturing cost.
To minimize abrasive wear, the particles 24 have a hardness value
which does not exceed, i.e., is less than or equal to, a hardness value of the
glass fiber(s). The hardness values of the particles and glass fibers can be
determined by any conventional hardness measurement method, such as
CA 02346111 2001-04-02
WO 00/21900 PGTNS99/21443
-22-
Vickers or Brinell hardness, but is preferably determined according to the
original Mohs' hardness scale which indicates the relative scratch resistance
of the surface of a material. The Mohs' hardness value of glass fibers
generally ranges from about 4.5 to about 6.5, and is preferably about 6. See
R. Weast (Ed.), Handbook of Chemistr)r and Physics, CRC Press (1975) at
page F-22, which is hereby incorporated by reference. The Mohs' hardness
value of the particles suitable for use in the coating composition discussed
above preferably ranges from about 0.5 to about 6. The Mohs' hardness
values of several non-limiting examples of particles suitable for use in the
present invention are given in Table A below.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-23-
Table A
Particle material Mohs' hardness on final
scale)
boron nitride about 25
ra hite _
about 0.5-1B
mol bdenum disulfide about 1
talc about 1-1.5
mica about 2.8-3.2
kaolinite about 2.0-2.5'
sum about 1.6-2"
calcite (calcium carbonate)about 3 2
calcium fluoride about 4'3
zinc oxide about 4.5'"
aluminum about 2.5'
copper about 2.5-3'6
iron about 4-5"
gold about 2.5-3'8
nickel about 5'g
alladium about 4.82
latinum about 4.32'
silver about 2.5-42z
As mentioned above, the Mohs' hardness scale relates to the
resistance of a material to scratching. The instant invention therefore
further
contemplates particles that have a hardness at their surface that is different
from the hardness of the internal portions of the particle beneath its
surface.
More specifically, the surface of the particle can be modified in any manner
5 K. Ludema, Friction. Wear, Lubrication, (1996) at page 27, which is hereby
incorporated by reference.
6 R. Weast (Ed.), Handbook of Chemistry and Physics, CRC Press (1975) at page
F-22.
7 R. Lewis, Sr., Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at
page 793, which is
hereby incorporated by reference.
8 Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at page 1113, which
is hereby
incorporated by reference.
9 Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at page 784, which
is hereby incorporated
by reference.
1 Handbook of Chemistry and Physics at page F-22.
11 Handbook of Chemistry and Physics at page F-22.
12 Friction, Wear, Lubrication at page 27.
13 Fd~ion. Wear. Lubrication at page 27.
14 Friction. Wear. Lubrication at page 27.
Friction. Wear. Lubrication at page 27.
16 Handbook of Chemistry and Physics at page F-22.
1 ~ Handbook of Chemistry and Physics at page F-22.
18 HHandbook of Chemistry and Physics at page F-22.
19 Handbook of Chemistry and Physics at page F-22.
2~ Handbook of Chemistry and Physics at page F-22.
21 Handbook of Chemistry and Physics at page F-22.
22 Handbook of Chemistr~nd Physics at page F-22.
CA 02346111 2001-04-02
WO 00/21900 PCTNS99lZ1443
-24-
well known in the art, including but not limited to chemically changing its
surface characteristics using techniques known in the art, such that the
surface hardness of the particle is not greater than the hardness of the glass
fibers while the hardness of the particle beneath the surface is greater than
the hardness of the glass fibers. As another alternative, a particle can be
coated, clad or encapsulated to form a composite particle (as discussed later)
that has a softer surface.
Generally, particles 24 useful in the present invention can be formed
from materials selected from the group consisting of polymeric and non-
polymeric inorganic materials, polymeric and non-polymeric organic materials,
composite materials and mixtures thereof. As used herein the term
"polymeric inorganic material" means a polymeric material having a backbone
repeat unit based on an element or elements other than carbon. For more
information see J. E. Mark et al. at page 5 which is hereby incorporated by
reference. Polymeric organic materials include synthetic polymeric materials,
semisynthetic polymeric materials and natural polymeric materials. An
"organic material", as used herein, means all compounds of carbon except
such binary compounds as the carbon oxides, the carbides, carbon disulfide,
etc.; such ternary compounds as the metallic cyanides, metallic carbonyls,
phosgene, carbonyl sulfide, etc.; and metallic carbonates, such as calcium
carbonate and sodium carbonate. See R. Lewis, Sr., Hawlev's Condensed
Chemical Dictionary, (12th Ed. 1993) at pages 761-762 which are hereby
incorporated by reference. More generally, organic materials include carbon
containing compounds wherein the carbon is typically bonded to itself and to
hydrogen, and often to other elements as well and excludes carbon-
containing ionic compounds. See M. Silberberg, Chemistry The Molecular
Nature of Matter and Chance, (1996) at page 586, which is hereby
incorporated by reference. The term " inorganic material" generally means all
materials that are not compounds of carbon with the exception of carbon
oxides and carbon disulfide. See R. Lewis, Sr., Hawley's Condensed
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-25-
Chemical Dictionary, (12th Ed. 1993) at page 636 which are hereby
incorporated by reference. As used herein the term "inorganic materials"
means any material that is not an organic material. As used here in the term
"composite material" means a combination of two or more different materials.
For more information on particles useful in the present invention, see G.
Wypych, Handbook of Fillers, 2nd Ed. (1999) at pages 15-202, which are
hereby incorporated by reference.
Non-polymeric inorganic materials useful in forming the particles 24
include ceramic materials and metallic materials. Suitable ceramic materials
include metal nitrides, metal oxides, metal carbides, metal sulfides, metal
borides, metal silicates, metal carbonates and mixtures thereof.
A non-limiting example of a suitable metal nitride is boron nitride, which
is the preferred inorganic material from which particles useful in the present
invention are formed. A non-limiting example of a useful metal oxide is zinc
oxide. Suitable metal sulfides include molybdenum disulfide, tantalum
disulfide, tungsten disulfide and zinc sulfide. Useful metal silicates include
aluminum silicates and magnesium silicates, such as vermiculite. Suitable
metallic materials include graphite, molybdenum, platinum, palladium, nickel,
aluminum, copper, gold, iron, silver and mixtures thereof.
Although not required, preferably the particles 24 are also solid
lubricants. As used herein, "solid lubricant" means any solid used between
two surfaces to provide protection from damage during relative movement
and/or to reduce friction and wear. More preferably, the particles 24 are an
inorganic solid lubricant. As used herein, "inorganic solid lubricant" means
that the inorganic particles 24 have a characteristic crystalline habit which
causes them to shear into thin, flat plates which readily slide over one
another
and thus produce an antifriction lubricating effect between the glass fiber
surtace and an adjacent solid surtace, at least one of which is in motion.
(See R. Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed.
1993) at page 712, which is hereby incorporated by reference.) Friction is the
CA 02346111 2001-04-02
WO 00/21900 PCTNS99/21443
-26-
resistance to sliding one solid over another. See F. Clauss, Solid Lubricants
and Self Lubricating Solids, (1972) at page 1, which is hereby incorporated by
reference.
In one particular embodiment useful in the present invention, the solid
lubricant particles have a lamellar structure which is believed to contribute
to
reduced tool wear when drilling holes through the laminae, as will discussed
later in more detail. Particles having a lamellar structure are composed of
sheets or plates of atoms in hexagonal array, with strong bonding within the
sheet and weak van der Waals bonding between sheets, providing low shear
strength between sheets. A non-limiting example of a lamellar structure is a
hexagonal crystal structure. See Friction. Wear. Lubrication at page 125,
Solid Lubricants and Self Lubricating Solids at pages 19-22, 42-54, 75-77, 80-
81, 82, 90-102, 113-120 and 128, and W. Campbell "Solid Lubricants",
Boundary Lubrication: An Appraisal of World Literature, ASME Research
Committee on Lubrication (1969) at pages 202-203, which are hereby
incorporated by reference. Inorganic particles having a lamellar fulferene
(buckyball) structure are also useful in the present invention.
Non-limiting examples of suitable inorganic solid lubricant particles
having a larnellar structure include boron nitride, graphite, metal
dichalcogenides, mica, talc, gypsum, kaolinite, calcite, cadmium iodide,
silver
sulfide and mixtures thereof. Preferred inorganic solid lubricant particles
include boron nitride, graphite, metal dichalcogenides and mixtures thereof.
Suitable metal dichalcogenides include molybdenum disulfide, molybdenum
diselenide, tantalum disulfide, tantalum diselenide, tungsten disulfide,
tungsten diselenide and mixtures thereof.
A non-limiting example of an inorganic solid lubricant material for use
in the coating composition of the present invention having a hexagonal crystal
structure is boron nitride. Particles formed from boron nitride, zinc sulfide
and
montmorillonite also provide good whiteness in composites with polymeric
matrix materials such as nylon 6,6.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-27-
Non-limiting examples of boron nitride particles suitable for use in the
present invention are PolarTherm~ 100 Series (PT 120, PT 140, PT 160 and
PT 180), 300 Series (PT 350) and 600 Series (PT 620, PT 630, PT 640 and
PT 670) boron nitride powder particles which are commercially available from
Advanced Ceramics Corporation of Lakewood, Ohio. "PolarTherm~
Thermally Conductive Fillers for Polymeric Materialsn, a technical bulletin of
Advanced Ceramics Corporation of Lakewood, Ohio (1996), is hereby
incorporated by reference. These particles have a thermal conductivity of
about 250-300 Watts per meter °K at 25°C, a dielectric constant
of about 3.9
and a volume resistivity of about 10'5 ohm-centimeters. The 100 Series
powder particles have an average particle size ranging from about 5 to about
14 micrometers, the 300 Series particles have an average particle size
ranging from about 100 to about 150 micrometers and the 600 Series
particles have an average particle size ranging from about 16 to greater than
about 200 micrometers.
The particles 24 can be formed from non-polymeric, organic materials.
Examples of non-polymeric, organic materials useful in the present invention
include but are not limited to stearates (such as zinc stearate and aluminum
stearate), carbon black and stearamide.
The particles 24 can be formed from inorganic polymeric materials.
Non-limiting examples of useful inorganic polymeric materials include
polyphosphazenes, polysilanes, polysiloxane, polygeremanes, polymeric
sulfur, polymeric selenium, silicones and mixtures thereof. A specific, non-
limiting example of a particle formed from an inorganic polymeric material
suitable for use in the present invention is Tospearl23, which is a particle
formed from cross-linked siloxanes and is commercially available from
Toshiba Silicones Company, Ltd. of Japan.
z3 See R. J. Perry "Applications for Cross-Linked Siloxane Particles"
Chemtech. February
1999 at pages 39-44.
CA 02346111 2001-04-02
WO 00/21900 PCTNS99/21443
-28-
Suitable synthetic, organic polymeric materials from which the particles
can be formed include, but are not limited to, thermosetting materials and
thermoplastic materials. Suitable thermosetting materials include
thermosetting polyesters, vinyl esters, epoxy materials, phenolics,
aminoplasts, thermosetting polyurethanes and mixtures thereof. A specific,
non-limiting example of a preferred synthetic polymeric particle formed from
an epoxy material is an epoxy microgel particle.
Suitable thermoplastic materials include thermoplastic polyesters,
polycarbonates, polyolefins, acrylic polymers, polyamides, thermoplastic
polyurethanes, vinyl polymers and mixtures thereof. Preferred thermoplastic
polyesters include but are not limited to polyethylene terephthalate,
polybutylene terephthalate and polyethylene naphthalate. Preferred
polyolefins include but are not limited to polyethylene, polypropylene and
polyisobutene. Preferred acrylic polymers include copolymers of styrene and
acrylic and polymers containing methacrylate. Non-limiting examples of
synthetic polymeric particles formed from an acrylic copolymer are
ROPAQUE~ HP-105524, which is an opaque, non-film-forming, styrene acrylic
polymeric synthetic pigment having a 1.0 micrometer particle size, a solids
content of 26.5 percent by weight and a 55 percent void volume, ROPAQUE~
OP-9625, which is an opaque, non-film-forming, styrene acrylic polymeric
synthetic pigment dispersion having a particle size of 0.55 micrometers and a
solids content of 30.5 percent by weight, and ROPAQUE~ OP-62 L02B which
is also an opaque, non-film-forming, styrene acrylic polymeric synthetic
pigment dispersion having a particles size of 0.40 micrometers and a solids
24 See product property sheet entitled: "ROPAQUE~ HP-1055, Hollow Sphere
Pigment for
Paper and Paperboard Coatings" October 1994, available from Rohm and Haas
Company,
Philadelphia, PA at page 1 which is hereby incorporated by reference.
2s See product technical bulletin entitled: "Architectural Coatings- ROPAQUE~
OP-96, The
All Purpose Pigment", April 1997 available from Rohm and Haas Company,
Philadelphia, PA
at page 1 which is hereby incorporated by reference.
26 Ibid.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99121443
-29-
content of about 36.5 percent by weight, each of which are commercially
available from Rohm and Haas Company of Philadelphia, Pennsylvania.
Suitable semisynthetic, organic polymeric materials from which the
particles 24 can be formed include but are not limited to cellulosics, such as
methylcellulose and cellulose acetate; and modified starches, such as starch
acetate and starch hydroxyethyl ethers.
Suitable natural polymeric materials from which the particles 24 can be
formed include but are not limited to polysaccharides, such as starch;
polypeptides, such as casein; and natural hydrocarbons, such as natural
rubber and gutta percha.
In one embodiment of the present invention, the polymeric particles 18
are formed from hydrophobic polymeric materials to reduce or limit moisture
absorption by the coated strand. Non-limiting examples of hydrophobic
polymeric materials believed to be useful in the present invention include but
are not limited to polyethylene, polypropylene, polystyrene and
polyrnethylmethacrylate. Non-limiting examples of polystyrene copolymers
include ROPAQUE~ HP-1055, ROPAQUE~ OP-96, and ROPAQUEc~ OP-62
LO pigments (each discussed above).
In another embodiment of the present invention, polymeric particles 18
are formed from polymeric materials having a glass transition temperature
(T9) and/or melting point greater than about 25°C and preferably
greater than
about 50°C.
Composite particles 24 useful in the present invention include particles
formed by cladding, encapsulating or coating particles formed from a primary
material with one or more secondary materials. For example, an inorganic
particle formed from an inorganic material such as silicon carbide or
aluminum nitride can be provided with a silica, carbonate or nanoclay coating
to form a useful composite particle. In another example, a silane coupling
agent with alkyl side chains can be reacted with the surface of an inorganic
particle formed from an inorganic oxide to provide a useful composite particle
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
- 30 -
having a "softer" surface. Other examples include cladding, encapsulating or
coating particles formed from organic or polymeric materials with inorganic
materials or different organic or polymeric materials. A specific non-limiting
example of such composite particles is DUALITE, which are synthetic
polymeric particles coated with calcium carbonate that is commercially
available from Pierce and Sevens Corporation of Buffalo, New York.
In still another embodiment of the present invention, the particles 24
can be hollow particles formed from materials selected from the group
consisting of inorganic materials, organic materials, polymeric materials,
composite materials and mixtures thereof. Non-limiting examples of suitable
materials from which the hollow particles can be formed are described above.
Non-limiting examples of a hollow polymeric particle useful in present
invention are ROPAQUE~ HP-1055, ROPAQUE~ OP-96 and ROPAQUE~
OP-62 LO pigments (each discussed above). For other non-limiting
examples of hollow particles that can be useful in the present invention see
H.
Katz et al. (Ed.) (1987) at pages 437-452 which are hereby incorporated by
reference.
The solid lubricant particles 24 can be present in a dispersion,
suspension or emulsion in water. Other solvents, such as mineral oil or
alcohol (preferably less than about 5 weight percent), can be included in the
sizing composition, if desired. A non-limiting example of a preferred
dispersion of about 25 weight percent boron nitride particles in water is
ORPAC BORON NITRIDE RELEASECOAT-CONC which is commercially
available from ZYP Coatings, Inc. of Oak Ridge, Tennessee. "ORPAC
BORON NITRIDE RELEASECOAT-CONC", a technical bulletin of ZYP
Coatings, inc., is hereby incorporated by reference. The boron nitride
particles in this product have an average particle size of less than about 3
micrometers and include about 1 percent of magnesium-aluminum silicate to
bind the boron nitride particles to the substrate to which the dispersion is
applied. Other useful products which are commercially available from ZYP
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/Z1443
-31 -
Coatings include BORON NITRIDE LUBRICOAT~ paint, BRAZE STOP and
WELD RELEASE products. Specific, non-limiting examples of emulsions and
dispersions of synthetic polymeric particles formed from acrylic polymers and
copolymers include: Rhoplex~ GL-6232' which is an all acrylic firm polymer
emulsion having a solids content of 45 percent by weight and a glass
transition temperature of about 98°C; EMULSION E-232128 which is a
hard,
methacrylate polymer emulsion having a solids content of 45 percent by
weight and a glass transition temperature of about 105°C; ROPAQUE~ OP-
96 (discussed above), which is supplied as a dispersion having a particle size
of 0.55 micrometers and a solids content of 30.5 percent by weight;
ROPAQUE~ OP-62 LO (discussed above), which is also a opaque, non-film-
forming synthetic pigment dispersion having a particles size of 0.40
micrometers and a solids content of about 36.5 percent by weight; and
ROPAQUE~ HP-1055 (discussed above), which is supplied as a dispersion
having a solids content of about 26.5 percent by weight; all of which are
commercially available from Rohm and Haas Company of Philadelphia,
Pennsylvania.
Although not required, it is preferred that the particles 24 be non-
hydratable, inorganic solid lubricant particles. As used herein, "non-
hydratable" means that the solid inorganic lubricant particles do not react
with
molecules of water to form hydrates and do not contain water of hydration or
water of crystallization. A "hydrate" is produced by the reaction of molecules
of water with a substance in which the H-OH bond is not split. See R. Lewis,
Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at pages 609-
610 and T. Perros, Chemistry, (1967) at pages 186-187, which are hereby
incarporated by reference. Structurally, hydratable inorganic materials
2' See product property sheet entitled: "Rhoplex~ GL-623, Self-Crosslinking
Acrylic Binder of
Industrial Nonwovens", March 1997 available from Rohm and Haas Company,
Philadelphia,
PA which is hereby incorporated by reference.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-32-
include at least one hydroxyl group within a layer of a crystal lattice (but
not
including hydroxyl groups in the surface planes of a unit structure or
materials
which absorb water on their surface planes or by capillary action), for
example as shown in the structure of kaolinite given in Fig. 3.8 at page 34 of
J. Mitchell, Fundamentals of Soil Behavior (1976) and as shown in the
structure of 1:1 and 2:1 layer minerals shown in Figs. 18 and 19,
respectively,
of H. van Olphen, Clay Colloid Chemistry, (2d Ed. 1977) at page 62, which
are hereby incorporated by reference. A "layer" of a crystal lattice is a
combination of sheets, which is a combination of planes of atoms. See
Minerals in Soil Environments, Soil Science Society of America {1977) at
page 196-199, which is hereby incorporated by reference. The assemblage
of a layer and interlayer material (such as cations) is referred to as a unit
structure.
Hydrates contain coordinated water, which coordinates the cations in
the hydrated material and cannot be removed without the breakdown of the
structure, and/or structural water, which occupies interstices in the
structure
to add to the electrostatic energy without upsetting the balance of charge.
See R. Evans, An Introduction to Crystal Chemistry, (1948) at page 276,
which is hereby incorporated by reference.
While not preferred, the aqueous sizing composition can contain
hydratable or hydrated inorganic solid lubricant materials in addition to the
non-hydratable inorganic solid lubricant materials discussed above. Non-
limiting examples of such hydratable inorganic solid lubricant materials are
clay mineral phyllosilicates, including micas (such as muscovite), talc,
montmorillonite, kaolinite and gypsum.
Preferably, the coating composition is essentially free of hydratable
inorganic solid lubricant particles or abrasive silica particles or calcium
28 See product property sheet entitled: "Building Products Industrial Coatings-
Emulsion E-
2321 ", 1990, available from Rohm and Haas Company, Philadelphia, PA which is
hereby
incorporated by reference.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-33-
carbonate, i.e., comprises less than about 20 weight percent of hydratable
inorganic lubricant particles, abrasive silica particles or calcium carbonate
on
a total solids basis, more preferably less than about 5 weight percent, and
most preferably less than 0.001 weight percent.
In an alternative embodiment useful in the present invention, the
particles 24 are formed from organic polymeric materials selected from the
group consisting of thermosetting materials, thermoplastic materials, starches
and mixtures thereof. Suitable thermosetting materials include thermosetting
polyesters, vinyl esters, epoxy materials, phenolics, aminoplasts,
thermosetting polyurethanes and mixtures thereof, such as are discussed
below. Suitable thermoplastic materials include vinyl polymers, thermoplastic
polyesters, polyolefrns, polyamides, thermoplastic polyurethanes, acrylic
polymers and mixtures thereof. Preferred organic particles are in the form of
microbeads or hollow spheres.
Although not required, in one embodiment useful in the present
invention, the particles 24 are thermally conductive, i.e., have a thermal
conductivity greater than about 30 Watts per meter K, and preferably is
greater than about 100 Watts per meter K, and more preferably ranges from
about 100 to about 2000 Watts per meter K. As used herein, "thermal
conductivity" means the property of the particle 24 that describes its ability
to
transfer heat through itself. See R. Lewis, Sr., Hawle~s Condensed
Chemical Dictionary, (12th Ed. 1993) at page 305, which is hereby
incorporated by reference.
The thermal conductivity of a solid material can be determined by any
method known to one skilled in the art. For example, if the thermal
conductivity of the material to be tested ranges from about 0.001 Watts per
meter K to about 100 Watts per meter K, the thermal conductivity of the
material can be determined using the preferred guarded hot plate method
according to ASTM C-177-85 (which is hereby incorporated by reference) at a
temperature of about 300K. If the thermal conductivity of the material to be
CA 02346111 2001-04-02
WO 00/21900 PC'1'/US99121443
- 34 -
tested ranges from about 20 Watts per meter K to about 1200 Watts per
meter K, the thermal conductivity of the material can be determined using the
guarded hot flux sensor method according to ASTM C-518-91 (which is
hereby incorporated by reference). It is believed that the materials with
higher thermal conductivity will more quickly dissipate the heat generated
during a drilling operation from the hole area, resulting in prolonged drill
tip
life. The thermal conductivity of selected material in Table A is included in
Table B.
Although not required, in another embodiment useful in the present
invention, the particles 24 are electrically insulative or have high
electrical
resistivity, i.e., have an electrical resistivity greater than about 1000
microohm-cm. Use of particles having high electrical resistivity is preferred
for conventional electronic circuit board applications to inhibit loss of
electrical
signals due to conduction of electrons through the reinforcement. For
specialty applications, such as circuit boards for microwave, radio frequency
interference and electromagnetic interference applications, particles having
high electrical resistivity are not required. The electrical resistance of
selected materials in Table A is included in Table B.
It will be appreciated by one skilled in the art that particles 24 of the
coating composition can include any combination or mixture of particles 24
discussed above. More specifically, the particles 24 can include additional
particles made from any of the materials described above for forming the
particles 24.
The solid lubricant particles, if present, can comprise about 1 to about
1 weight percent of the coating composition on a total solids basis,
preferably
about 1 to about 60 weight percent. In one embodiment, the coating
composition can contain about 2 to about 10 weight percent boron nitride on
total solids basis. In another embodiment of the invention wherein a
combination of different particles are used, the coating composition contains
about 20 to about 60 weight percent of particles 24 on total solids basis, and
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-35-
preferably about 35 to about 55 weight percent, and more preferably about
30 to about 50 weight percent.
The coating composition can further comprise one or more softening
agents, or surfactants, that impart a uniform charge to the surface of the
fibers, causing the fibers to repel from each other and reducing the friction
between the fibers, so as to function as a lubricant. Although not required,
it
is preferred that the softening agents are chemically different from the
polymeric materials discussed above. While the coating composition can
comprise up to about 60 weight percent softening agent, preferably the
coating composition is essentially free of softening agents, i.e., contains
less
than about 10 weight percent softening agent, and more preferably contains
less than about 5 weight percent softening agent. Examples of such
softening agents include cationic, non-ionic or anionic softening agents and
mixtures thereof, such as amine salts of fatty acids, alkyl imidazoline
derivatives such as CATION X, which is commercially available from Rhone
Poulenc of Princeton, New Jersey, acid solubilized fatty acid amides,
condensates of a fatty acid and polyethylene imine arad amide substituted
polyethylene imines, such as EMERY~ 6717, a partially amidated
polyethylene imine commercially available from Henkel Corporation of
Kankakee, Illinois. For more information on softening agents, see A. J. Hall,
Textile Finishing, 2"d Ed. (1957) at pages 108-115, which are hereby
incorporated by reference.
The coating composition can include one or more emulsifying agents
for emulsifying or dispersing components of the coating composition, such as
the organic and inorganic particles. Non-limiting examples of suitable
emulsifying agents or surfactants include polyoxyalkylene block copolymers
(such as PLURONICT"" F-108 polyoxypropylene-polyoxyethylene copolymer
which is commercially available from BASF Corporation of Parsippany, New
Jersey), ethoxylated alkyl phenols (such as IGEPAL CA-630 ethoxylated
octylphenoxyethanol which is commercially available from GAF Corporation of
CA 02346111 2001-04-02
WO 00/Z1900 PCT/US99/21443
-36-
Wayne, New Jersey), polyoxyethylene octylphenyl glycol ethers, ethylene
oxide derivatives of sorbitol esters, polyoxyethylated vegetable oils (such as
ALKAMULS EL-719, which is commercially available from Rhone-Poulenc)
and nonylphenol surfactants (such as MACOL NP-6 which is commercially
available from BASF of Parsippany, New Jersey). Generally, the amount of
emulsifying agent can range from about 1 to about 30 weight percent of the
coating composition on a total solids basis.
The coating composition can further include one or more lubricious
materials that are chemically different from the polymeric materials and
softening agents discussed above to impart desirable processing
characteristics to the fiber strands during weaving. Suitable lubricious
materials can be selected from the group consisting of oils, waxes, greases
and mixtures thereof. Non-limiting examples of wax materials useful in the
present invention include aqueous soluble, emulsifiable or dispersible wax
materials such as vegetable, animal, mineral, synthetic or petroleum waxes,
e.g. paraffin. Oils useful in the present invention include both natural oils,
semisynthetic oils and synthetic oils. Generally, the amount of wax or other
lubricious material can range from 0 to about 80 weight percent of the sizing
composition on a total solids basis, preferably from about 1 to about 50
weight percent, more preferably from about 20 to about 40 weight percent,
and most preferably from about 25 to about 35 weight percent.
Preferred lubricious materials include waxes and oils having polar
characteristics, and more preferably include highly crystalline waxes having
polar characteristics and melting points above about 35°C and more
preferably above about 45°C. Such materials are believed to improve the
wet-out and wet-through of polar resins on fiber strands coated with sizing
compositions containing such polar materials as compared to fiber strands
coated with sizing compositions containing waxes and oils that do not have
polar characteristics. Preferred lubricious materials having polar
characteristics include esters formed from reacting (1 ) a monocarboxylic acid
CA 02346111 2001-04-02
WO 00/21900 PCT/US99121443
-37-
and (2) a monohydric alcohol. Non-limiting examples of such fatty acid esters
useful in the present invention include cetyl palmitate, which is preferred
(such as is available from Stepan Company of Maywood, New Jersey as
KESSCO 653 or STEPANTEX 653), cetyl myristate (also available from
Stepan Company as STEPANLUBE 654), cetyl laurate, octadecyl laurate,
octadecyl myristate, octadecyl palmitate and octadecyl stearate. Other fatty
acid ester, lubricious materials useful in the present invention include
trimethylolpropane tripelargonate, natural spermaceti and triglyceride oils,
such as but not limited to soybean oil, linseed oil, epoxidized soybean oil,
and
epoxidized linseed oil.
While not preferred, the coating composition can include one or more
other lubricious materials, such as non-polar petroleum waxes, in lieu of or
in
addition to of those lubricious materials discussed above. Non-limiting
examples of non-polar petroleum waxes include MICHEM~ LUBE 296
microcrystalline wax, POLYMEKON~ SPP-W microcrystalline wax and
PETROLITE 75 microcrystalline wax which are commercially available from
Michelman Inc. of Cincinnati, Ohio and the Petrolite Corporation of Tulsa,
Oklahoma, respectively.
Although not required, if desired the coating composition can also
include a resin reactive diluent to further improve lubrication of the coated
fiber strands of the present invention and provide good processibility in
weaving and knitting by reducing the potential for fuzz, halos and broken
filaments during such manufacturing operations, while maintaining resin
compatibility. As used herein, "resin reactive diluent" means that the
diluent includes functional groups that are capable of chemically reacting
with the same resin with which the coating composition is compatible
The diluent can be any lubricant with one or more functional groups that
react with a resin system, preferably functional groups that react with an
epoxy resin system, and more preferably functional groups that react with
an FR-4 epoxy resin system. Non-limiting examples of suitable lubricants
CA 02346111 2001-04-02
WO 00/21900 PCT/US99121443
-38-
include lubricants with amine groups, alcohol groups, anhydride groups,
acid groups or epoxy groups. A non-limiting example of a lubricant with
an amine group is a modified polyethylene amine, e.g. EMERY 6717,
which is a partially amidated polyethylene imine commercially available
from Henkel Corporation of Kankakee, Illinois. A non-limiting example of a
lubricant with an alcohol group is polyethylene glycol, e.g. CARBOWAX
300, which is a polyethylene glycol that is commercially available from
Union Carbide of Danbury, Connecticut. A non-limiting example of a
lubricant with an acid graup is fatty acids, e.g. stearic acid and salts of
stearic acids. Non-limiting examples of lubricants with an epoxy group
include epoxidized soybean oil and epoxidized linseed oil, e.g. FLEXOL
LOE, which is an epoxidized linseed oil, and FLEXOL EPO, which is an
epoxidized soybean oil, both commercially available from Union Carbide of
Danbury, Connecticut, and LE-9300 epoxidized silicone emulsion, which is
commercially available from Witco Corporation OSi Specialties, Inc. of
Danbury, Connecticut. Although not limiting in the present invention, the
sizing composition can include a resin reactive diluent as discussed above
in an amount up to about 15 weight percent of the sizing composition on
a total solids basis.
Crosslinking materials, such as melamine formaldehyde, and
plasticizers, such as phthalates, trimellitates and adipates, can also be
included in the coating composition. The amount of crosslinker or plasticizer
can range from about 1 to about 5 weight percent of the coating composition
on a total solids basis.
Other additives can be included in the coating composition, such as
silicones, fungicides, bactericides and anti-foaming materials, generally in
an
amount of less than about 5 weight percent. Organic and/or inorganic acids
or bases in an amount sufficient to provide the coating composition with a pH
of about 2 to about 10 can also be included. A non-limiting example of a
suitable silicone emulsion is LE-9300 epoxidized silicone emulsion that is
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-39-
commercially available from OSi Specialties, Inc. of Danbury, Connecticut.
An example of a suitable bactericide is BIOMET 66 antimicrobial compound,
which is commercially available from M 8~ T Chemicals of Rahway, New
Jersey. Suitable anti-foaming materials are the SAG materials, which are
commercially available from OSi Specialties, Inc. of Danbury, Connecticut
and MAZU DF-136, which is available from BASF Company of Parsippany,
New Jersey. Ammonium hydroxide can be added to the coating composition
for stabilization, if desired. Water (preferably deionized) is preferably
included in the coating composition in an amount sufficient to facilitate
application of a generally uniform coating upon the strand, generally in an
amount of about 25 to about 99 weight percent. The weight percentage of
solids of an aqueous coating composition generally ranges from about 1 to
about 75 weight percent.
The coating composition is preferably essentially free of glass
materials. As used herein, "essentially free of glass materials" means that
the
coating composition comprises less than 20 volume percent of glass matrix
materials for forming glass composites, preferably less than about 5 volume
percent, and more preferably is free of glass materials. Examples of such
glass matrix materials include black glass ceramic matrix materials or
aluminositicate matrix materials such as are well known to those skilled in
the
art.
In one nonlimiting embodiment of a fabric for electronic circuit boards
of the present invention, the glass fibers of the coated fiber strands have
applied thereto a primary layer of a dried residue of an aqueous sizing
composition comprising PolarTherm~ 160 boron nitride powder and/or
ORPAC BORON NITRIDE RELEASECOAT-CONC dispersion, PVP K-30
polyvinyl pyrrolidone, A-174 acrylic-functional organo silane coupling agent,
A-187 epoxy-functional organo silane coupling agent, ALKAMULS EL-719
polyoxyethylated vegetable oil, EMERY~ 6717 partially amidated
polyethylene imine, RD-847A polyester, DESMOPHEN 2000 polyester,
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-40-
PLURONICS F-108 polyoxypropylene-polyoxyethylene copolymer, ICONOL
NP-6 alkoxylated nonyl phenol and SAG 10 antifoaming material.
In another embodiment of fabric for electronic circuit boards of the
present invention, glass fibers of the coated fiber strands of the present
invention have applied thereto a primary layer of a dried residue of an
aqueous sizing composition comprising PolarTherm~ 160 boron nitride
powder and/or ORPAC BORON NITRIDE RELEASECOAT-CONC dispersion,
RD-847A polyester, PVP K-30 polyvinyl pyrrolidone, DESMOPHEN 2000
polyester, A-174 acrylic-functional organo silane coupling agent, A-187
epoxy-functional organo silane coupling agent, PLURONICS F-108
polyoxypropylene-polyoxyethylene copolymer, VERSAMID 140 polyamide,
and MACOL NP-6 nonyl phenol.
In still another embodiment for weaving fabric for laminated printed
circuit boards, glass fibers of the coated fiber strand of the present
invention
have a primary layer of a dried residue of an aqueous primary sizing
composition comprising ROPAQUE~ HP-1055 and/or ROPAQUE~ OC-96
styrene-acrylic copolymer hollow spheres, PVP K-30 polyvinyl pyrrolidone,
A-174 acrylic-functional organo silane coupling agents and A-187 epoxy-
functional organo silane coupling agents, EMERY~ 6717 partially amidated
polyethylene imine, STEPANTEX 653 cetyl palmitate, TMAZ 81 ethylene
oxide derivatives of sorbitol esters, MACOL OP-10 ethoxylated alkylphenol
and MAZU DF-136 antifoaming material. In addition, this embodiment can
optionally further include PolarTherm~ 160 boron nitride powder and/or
ORPAC BORON NITRIDE RELEASECOAT-CONC dispersion.
The coating compositions useful in the present invention can be
prepared by any suitable method such as conventional mixing well known to
those skilled in the art. Preferably, the components discussed above are
diluted with water to have the desired weight percent solids and mixed
together. Powdered particles can be premixed with water or added to the
polymeric material prior to mixing with the other components of the coating.
CA 02346111 2001-04-02
WO 00/Z1900 PCT/US99/21443
-41 -
The layer of coating is applied to the fibers in many ways, for example
by contacting the filaments with a roller or belt applicator, spraying or
other
means. The coated fibers are preferably dried at room temperature or at
elevated temperatures. The dryer removes excess moisture from the fibers
and, if present, cures any curable coating composition components. The
temperature and time for drying the glass fibers will depend upon such
variables as the percentage of solids in the coating composition, components
of the coating composition and type of glass fiber. The coating composition is
typically present as a dried sizing residue on the fibers in an amount between
about 0.1 percent and about 25 percent by weight after drying. The loss on
ignition of the fibers is generally less than about 1.0 weight percent,
preferably less than about 0.5 weight percent, and more preferably ranges
from about 0.01 to about 0.45 weight percent. As used herein the term "loss
on ignition" means the weight percent of dried coating composition present on
the surface of the fiber strand as determined by the following equation:
LOi= 100 X [(Wdry W,~~)/Wdry]
wherein Wd,~ is the weight of the fiber strand plus the residue of the coating
composition after drying in an oven at about 220°F (about 104°C)
for about
60 minutes and Wbe~ is the weight of the bare fiber strand after removal of
residue of the coating composition by heating the fiber strand in an oven at
about 1150°F (about 621 °C) for about 20 minutes.
A layer of a secondary coating composition can be applied over the
layer of coating composition discussed above in an amount effective to coat
or impregnate the portion of the coated strands, for example by dipping the
coated strand in a bath containing the secondary coating composition,
spraying the secondary coating composition upon the coated strand or by
contacting the coated strand with an applicator as discussed above. The
coated strand can be passed through a die to remove excess coating
composition from the strand and/or dried as discussed above for a time
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/Z1443
-42-
sufficient to at least partially dry or cure the secondary coating
composition.
The method and apparatus for applying the secondary coating composition to
the strand is determined in part by the configuration of the strand material.
The strand is preferably dried after application of the secondary coating
composition in a manner well known in the art.
Suitable secondary coating compositions can include one or more film-
forming materials, lubricants and other additives such as are discussed
above. The secondary coating is preferably different from the sizing
composition, i.e., it (1 ) contains at least one component which is chemically
different from the components of the sizing composition; or (2) contains at
least one component in an amount which is different from the amount of the
same component contained in the sizing composition. Non-limiting examples
of suitable secondary coating compositions including polyurethane are
disclosed in U.S. Patent Nos. 4,762,750 and 4,762,751, which are hereby
incorporated by reference.
In an alternative embodiment of the present invention, the glass fibers
of the fiber strand can having applied thereto a primary coating of a dried
residue of a conventional sizing composition or a sizing composition which
can include any of the sizing components in the amounts discussed above.
Examples of suitable sizing compositions are set forth in Loewenstein at
pages 237-291 (3d Ed. 1993) and U.S. Patent Nos. 4,390,647 and 4,795,678,
each of which is hereby incorporated by reference. A layer of a secondary
coating composition useful in the present invention and disclosed herein is
applied to at least a portion, and preferably over the entire outer surface,
of
the primary coating. The secondary coating composition can comprise one or
more types of particles discussed above and/or those that are set forth in
Tables B below. It is noted that several of these particles have a Mohs
hardness greater than that expected for the glass fiber, i.e. about 4.5 to
about
6. However, since these particles are part of the secondary coating
composition that does not directly contact the surface of the glass fibers,
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-43-
these higher hardnesses will not adversely affect the glass fibers and are
acceptable.
Table B
Inorganic Solid Thermal conductivityElectrical ResistanceMohs' hardness
Material (W/m K at 300K) (micro ohm-centimeters)(ori final
scale)
boron nitride about 20029 1.7 x 10'9 ao about 23'
boron phosphide about 350 - about 9.5
3
Aluminum phosphideabout 130" . - -
aluminum nitrideabout 200'5 reater than 10'9 about 93
~
allium nitride about 170 - -
alliurn phos about 100' - -
hide
silicon carbide about 270 4 x 105 to 1 x reater than
10 ' 94
silicon nitride about 30' 10'9to 102' about g5
be Ilium oxide about 240'6 - about 9"
zinc oxide about 26 - about 4.54a
zinc sulfide about 25" 2.7 x 105 to 1.2 about 3.5-4
x 10'2 ~ '
29 G. Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phvs.
Chem. Solids (1973) Vol.
34, p. 322, which is hereby incorporated by reference.
30 A. Weimer (Ed.), Carbide, Nitride and Boride Materials Synthesis and
Processing, (1997) at page
654.
31 Friction. Wear. Lubrication at page 27.
32 G. Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phvs.
Chem. Solids {1973) Vol.
34, p. 325, which is hereby incorporated by reference.
33 R, Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at
page 164, which is
hereby incorporated by reference.
34 G, Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phvs.
Chem. Solids (1973) Vol.
34, p. 333, which is hereby incorporated by reference
35 G, Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phvs.
Chem. Solids (1973) Vol.
34, p. 329, which is hereby incorporated by reference.
36 A. Weimer (Ed.), Carbide, Nitride and Boride Materials Synthesis and
Processing, (1997) at page
654.
37 Friction. Wear. Lubrication at page 27.
38 G. Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phvs.
Chem. Solids (1973) Vol.
34, p. 333
39 G, Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phys.
Chem. Solids (1973) Vol.
34, p. 321, which is hereby incorporated by reference.
40 Microelectronics Packacin4 Handbook at page 36, which is hereby
incorporated by reference.
41 A. Weimer (Ed.), Carbide, Nitride and Boride Materials Synthesis and
Processing, (1997) at page
653, which is hereby incorporated by reference.
42 Friction, Wear. Lubrication at page 27.
43 Microelectronics Packacino Handbook at page 36, which is hereby
incorporated by reference.
~ A. Weimer (Ed.), Carbide, Nitride and Boride Materials Synthesis and
Processing, (1997) at page
654.
45 Friction. Wear. Lubrication at page 27.
46 Microelectronics Padcaninu Handbook at page 905, which is hereby
incorporated by reference.
47 Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at page 141, which
is hereby
incorporated by reference.
48 Friction. Wear. Lubrication at page 27.
49 Handbook of Chemistn~ and Physics, CRC Press (1975) at page 12-54.
50 Handbook of Chemistry and Physics, CRC Press (71 st Ed. 1990) at page 12-
63, which is hereby
incorporated by reference.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-44-
Table B i(cont'd)
Inorganic Solid Thermal conductivityElectrical ResistanceMohs' hardness
Material (W/m K at 300K) (micro ohm (ori final
-centimeters) scale)
diamond about 230052 _ 10~
2.7 x 10~
silicon about 84 5 about 10.0 about 75'
ra hite up to 2000 10059 about 0.5-160
mol bdenum about 1386' about 5.282 about 5.5~
platinum about 69~' about 10.6 about 4.3~
alladium about 70 about 10.888 about 4.8
tun sten about 200' about 5.5 ' about 7.5'2
nickel about 92'3 about 6.8'" about 5'S
aluminum about 205 6 about 4.3" about 2.5 8
chromium about 66'9 about 20~ about 9.08'
copper about 39882 about 1.78 about 2.5-3~~
51 Handbook of Chemistry and Physics, CRC Press (71st Ed. 1990) at page 4-158,
which is hereby
incorporated by reference.
52 Microelectronics Packagina Handbook at page 36.
53 Handbook of Chemistry and Physics, CRC Press (71 st Ed. 1990) at page 12-
63, which is hereby
incorporated by reference.
~ Handbook of Chemistry and Physics at page F-22.
55 Microelectronics Packaaing Handbook at page 174.
56 Handbook of Chemistry and Physics at page F-166, which is hereby
incorporated by reference.
57 Friction. Wear, Lubrication at page 27.
58 G. Slack, "Nonmetallic Crystals with High Thermal Conductivity, J. Phys.
Chem. Solids (1973) Vol.
34, p. 322, which is hereby incorporated by reference.
59 See W. Calliater, Materials Science and Engineering An Introduction, (2d
ed. 1991) at page 637,
which is hereby incorporated by reference.
60 Handbook of Chemistry and Physics at page F-22.
61 Microelectronics Packaging Handbook at page 174.
62 Microelectronics Packagins~ Handbook at page 37.
63 According to "Web Elements" http://www.shef.ac.ukhchemlweb-elents/nofr-
image-
I/hardness-minerals-Lhtml (February 26, 1998).
64 Microelectronics Packaging Handbook at page 174.
65 Microelectronics Packaging Handbook at page 37.
66 Handbook of Chemistry and Physics at page F-22.
67 Microelectronics Packaging Handbook at page 37.
68 Microelectronics Packaging Handbook at page 37.
69 Handbook of Chemistry and Physics at page F-22.
70 Microelectronics Packaging Handbook at page 37.
71 Microelectronics Packaging Handbook at page 37.
72 AAccording to "Web Elements" http:l/www.shef.ac.ukhchemlweb-elents/nofr-
image-
Ilhardness-minerals-Lhtml (February 26, 1998).
73 Microelectronics Packaging Handbook at page 174.
74 Microelectronics Packaging Handbook at page 37.
75 Handbook of Chemistry and P~sics at page F-22.
76 -Microelectronics Packaging Handbook at page 174.
77 Microelectronics Packaging Handbook at page 37.
78 Friction, Wear, Lubrication at page 27.
79 Microelectronics Packaging Handbook at page 37.
80 Microelectronics Packaging Handbook at page 37.
81 Handbook of Chemistry and Physics at page F-22.
82 Microelectronics Packaging Handbook at page 174.
83 Microelectronics Packaging Handbook at page 37.
84 Handbook of Chemistry and Physics, at page F-22.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21'i43
-45-
Table B i(cont'd~
Inorganic Solid Thermal conductivityElectrical Resistance~ Mohs' hardness
Material
(W/m K at 300K)(micro ohm-centimeters)(ori final
~ scale)
old about 297~ about 2.2 about 2.5-3
iron about 74.5 about 989 about 4-5
silver ~ about 418 ~ about 1.692 ( about 2.5-49'
Molybdenum disulfide and magnesium oxide are other inorganic
particles that are useful for secondary or tertiary coatings useful in the
present
invention. One skilled in the art would understand that mixtures of any of the
above inorganic particles can be used in the present invention.
In an alternative embodiment, the particles of the secondary coating
composition comprise hydrophilic inorganic particles that absorb and retain
water in the interstices of the hydrophilic particles. The hydrophilic
inorganic
particles can absorb water or swell when in contact with water or participate
in
a chemical reaction with the water to form, for example, a viscous gel-like
solution which blocks or inhibits further ingress of water into the
interstices of
a telecommunications cable which the coated glass fiber strand is used to
reinforce. As used herein, "absorb" means that the water penetrates the inner
structure or interstices of the hydrophilic material and is substantially
retained
therein. See Hawley's Condensed Chemical Dictionary at page 3, which is
hereby incorporated by reference. "Swell" means that the hydrophilic
particles expand in size or volume. See Webster's New Collegiate Dictionary
(1977) at page 1178, which is hereby incorporated by reference. Preferably,
the hydrophilic particles swell after contact with water to at least one and
one-
half times their original dry weight, and more preferably about two to about
six
85 Microelectronics Packaaing Handbook at page 174.
86 Microelectronics Packac~ina Handbook at page 37.
8~ Handbook of Chemistry and Physics at page F-22.
88 Microelectronics Packa4ing Handbook at page 174.
89 Handbook of Chemistry and Physics, CRC Press (1975) at page D-171, which is
hereby
incorporated by reference.
9~ Handbook of Chemistry and Physics at page F-22.
91 Microelectronics Packagin4 Handbook at page 174,
92 Microelectronics Packaaing Handbook at page 37.
93 Handbook of Chemistry and Physics at page F-22.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-46-
times their original weight. Non-limiting examples of hydrophilic inorganic
solid lubricant particles that swell include smectites such as vermiculite and
montmorillonite, absorbent zeolites and inorganic absorbent gels. Preferably,
these hydrophilic particles are applied in powder form over tacky sizing or
other tacky secondary coating materials. The amount of hydrophilic inorganic
particles in this embodiment of the secondary coating composition can range
from about 1 to about 99 weight percent on a total solids basis and preferably
about 20 to about 90 weight percent.
The amount of inorganic particles in the secondary coating
composition can range from about 1 to about 99 weight percent on a total
solids basis, and preferably about 20 to about 90 weight percent. The
percentage of solids of an aqueous secondary coating composition generally
ranges from about 5 to about 75 weight percent.
In another alternative embodiment of the present invention, a layer of a
tertiary coating composition is applied over at least a portion of the
surface,
and preferably over the entire surface, of a secondary coating, i.e., such a
fiber strand would have a layer of a primary coating of sizing, a layer of a
secondary coating composition and an outer layer of the tertiary coating. The
tertiary coating is preferably different from the sizing composition and the
secondary coating composition, i.e., the tertiary coating composition (1)
contains at least one component which is chemically different from the
components of the sizing and secondary coating composition; or (2) contains
at least one component in an amount which is different from the amount of
the same component contained in the sizing or secondary coating
composition. The tertiary coating is applied to the glass fibers and strands
prior to or after incorporation into a fabric using techniques, such as but
not
limiting to, spraying and dipping as discussed earlier and as are well know in
the art.
In this embodiment, the secondary coating composition comprises one
or more polymeric materials discussed above, such as polyurethane, and the
CA 02346111 2001-04-02
WO 00/Z1900 PCT/US99121443
-47-
tertiary coating composition comprises powdered thermally conductive
inorganic particles, such as the PolarTherm~ boron nitride particles, or
hollow particles, such as ROPAQUE~ pigment, which are discussed above.
Preferably, the powdered coating is applied by passing the strand having a
liquid secondary coating composition applied thereto through a fluidized bed
or spray device to adhere the powder particles to the tacky secondary coating
composition. Alternatively, the strands can be assembled into a fabric 114
before the layer 140 of tertiary coating is applied, as shown in Fig. 4. The
weight percent of powdered, thermally conductive inorganic particles adhered
to the coated strand can range from about 0.1 to about 75 weight percent of
the total weight of the dried strand. The tertiary coating can also include
one
or more polymeric materials such as are discussed above, such as acrylic
polymers, epoxies, or polyolefins, conventional stabilizers and other
modifiers
known in the art of such coatings, preferably in dry powdered form.
Although the prior discussion is generally directed toward applying the
coating composition of the present invention directly on glass fibers after
fiber
forming and subsequently incorporating the fibers into a fabric, it should be
appreciated by those skilled in the art that the present invention also
includes
an embodiment wherein the coating composition of the present invention is
applied to a fabric after it has been manufactured using various techniques
well known in the art. Depending on the processing of the fabric, the coating
composition of the present invention can be applied either directly to the
glass
fibers in the fabric or to another coating already on the giass fibers and/or
fabric. For example, the glass fibers can be coated with a conventional
starch-oil sizing after forming and woven into a fabric. The fabric can then
be
treated to remove the starch-oil sizing. A coating composition useful in the
present invention and disclosed herein can thereafter be applied directly to
the fabric using well known techniques, such as but not limited to, spraying
or
dipping the fabric into a bath of the sizing composition. The fabric can then
be dried prior to further processing to leave a residue of the composition on
CA 02346111 2001-04-02
WO 00121900 PCT/US99/21443
-48-
the fibers and strands of the fabric.. This sizing removal is accomplished
using techniques well known in the art, such as thermal treatment or washing
of the fabric. In this instance, the coating composition would directly coat
the
surface of the fibers of the fabric. If any portion of the sizing composition
initially applied to the glass fibers after forming is not removed, the
coating
composition of the present invention would then be applied over the
remaining portion of the sizing composition rather than directly to the fiber
surface.
In another embodiment of the present invention, selected
components of the coating composition of the present invention are
applied to the glass fibers immediately after forming and the remaining
components of the coating composition are applied to the fabric after it is
made. In a manner similar to that discussed above, some or all of the
selected components can be removed from the glass fibers prior to
coating the fibers and fabric with the remaining components. As a result,
the remaining components will either directly coat the surface of the fibers
of the fabric or coat those selected components that were not removed
from the fiber surface.
The woven fabric 14 is used as a reinforcement for reinforcing
polymeric matrix materials 12 to form a composite or laminate 10, such as is
shown in Fig. 1, preferably for use in electronic circuit boards. The warp and
weft (i.e. fill) strands of fabric 14 can be non-twisted (also referred to as
untwisted or zero twist) or twisted prior to weaving by any conventional
twisting technique known to those skilled in the art, for example by using
twist
frames to impart twist to the strand at about 0.5 to about 3 turns per inch.
In
addition, the fabric 14 can include various combinations of both twisted and
non-twisted warp and weft strands.
The reinforcing fabric 14 can include about 5 to about 100 warp
strands per centimeter (about 13 to about 254 warp strands per inch) and
preferably has about 6 to about 50 weft strands per centimeter (about 15 to
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/Z1443
-49-
about 127 weft strands per inch). The weave construction can be a regular
plain weave, although any other weaving style well known to those skilled in
the art, such as a twill weave or satin weave, can be used:
The fabric 14 is preferably woven in a style which is suitable for use in
a laminate for printed circuit boards, such as are disclosed in "Fabrics
Around
the World", a technical bulletin of Clark-Schwebel, Inc. of Anderson, South
Carolina (1995), which is hereby incorporated by reference. A non-limiting
example of a fabric style using E225 E-glass fibers is Style 2116, which has
118 warp yarns and 114 weft yarns per 5 centimeters (60 warp yarns and 58
weft yarns per inch); uses 7 22 1x0 (E225 1/0) warp and weft yarn; has a
nominal fabric thickness of 0.094 mm ( 0.037 inches); and a fabric weight of
103.8 g/m2 (3.06 ounces per square yard). A non-limiting example of a
fabric style using G75 E-glass fibers is Style 7628, which has 87 warp yarns
and 61 weft yarns per 5 centimeters (44 warp yarns and 31 weft yarns per
inch); uses 9 68 1x0 (G75 1/0) warp and weft yarn; has a nominal fabric
thickness of 0.173 mm ( 0.0068 inches); and a fabric weight of 203.4 g/m2
(6.00 ounces per square yard). A non-limiting example of a fabric style
using D450 E-glass fibers is Style 1080, which has 118 warp yarns and 93
weft yarns per 5 centimeters (60 warp yarns and 47 weft yarns per inch); uses
5 11 1x0 (D450 1/0) warp and weft yarn; has a nominal fabric thickness of
0.053 mm ( 0.0021 inches); and a fabric weight of 46.8 g/m2 (1.38 ounces per
square yard). A non-limiting example of a fabric style using D900 E-glass
fibers is Style 106, which has 110 warp yarns and 110 weft yams per 5
centimeters (56 warp yarns and 56 weft yarns per inch); uses 5 5.5 1x0 (D900
110) warp and weft yarn; has a nominal fabric thickness of 0.033 mm ( 0.013
inches); and a fabric weight of 24.4 g/m2 (0.72 ounces per square yard).
Another non-limiting example of a fabric style using D900 E-glass fibers is
Style 108, which has 118 warp yarns and 93 weft yarns per 5 centimeters (60
warp yarns and 47 weft yarns per inch); uses 5 5.5 1x2 (D900 1/2) warp and
weft yarn; has a nominal fabric thickness of 0.061 mm ( 0.0024 inches); and a
CA 02346111 2001-04-02
WO 00/21900 PGT/US99/21443
- 50 -
fabric weight of 47.5 g/m2 (1.40 ounces per square yard). A non-limiting
example of a fabric style using both E225 and D450 E-glass fibers is Style
2113, which has 118 warp yarns and 110 weft yarns per 5 centimeters (60
warp yarns and 56 weft yarns per inch); uses 7 22 1x0 (E225 1/0) warp yarn
and 5 11 '! x0 (D450 1I0) weft yarn; has a nominal fabric thickness of 0.079
mm ( 0.0031 inches); and a fabric weight of 78.0 g/m2 (2.30 ounces per
square yard). A non-limiting example of a fabric style using both G50 and
G75 E-glass fiber yarns is Style 7535 which has 87 warp yarns and 57 fill
yarns per 5 centimeters (44 warp yarns and 29 fill yarns per inch); uses 9
68 1 x0 (G75 1 /0) warp yarn and 9 99 1 x0 1650 1 /0) fill yarn; has a
nominal fabric thickness of about 0.201 millimeters (about 0.0079
inches); and a fabric weight of about 232.3 grams per square meter
(about 6.85 ounces per square yard). These and other useful fabric style
specifications are given in IPC-EG-140 "Specification for Finished Fabric
Woven from 'E' Glass for Printed Boards", a publication of The Institute for
Interconnecting and Packaging Electronic Circuits (June 1997), which is
hereby incorporated by reference. Although the aforementioned fabric
styles use twisted yarns, it is contemplated that these or other fabric
styles using zero-twist yarns or rovings in conjunction with or in lieu of
twisted yarns can be made in accordance with the present invention. It is
further contemplated that some or all of the warp yarn in the fabric can
have fibers coated with a first resin compatible sizing composition and
some or all of the fill yarn can have fibers coated with a second resin
compatible coating different from the first composition, i.e. the second
composition (1) contains at least one component which is chemically different
from the components of the first sizing composition; or (2) contains at least
one component in an amount which is different from the amount of the same
component contained in the first sizing composition.
A suitable woven reinforcing fabric 14 useful in the present invention is
formed by using any conventional loom well known to those skilled in the art,
CA 02346111 2001-04-02
WO 00121900 PCT/US99/21443
-51 -
such as a shuttle loom or rapier loom, but preferably is formed using an air
jet
loom. In weaving a fabric using the air jet process, the air jet loom inserts
the
fill yarn into the warp shed and propels the yarn across the width of the
fabric
by a blast of compressed air from one or more air jet. Preferred air jet looms
are commercially available from Tsudakoma of Japan as Model No. 103, 103I
and 1033 and Sulzer Ruti Model No. L-5000, L-5100 L-5200 which are
commercially available from Sulzer Brothers Ltd. of Zurich, Switzerland.
Sulzer Ruti L-5000, L-5100 and L-5200 Product Bulletins of Sulzer Ruti Ltd.,
Switzerland, which are hereby incorporated by reference.
Referring now to Fig. 1, the fabric 14 is used to form a laminate 10 by
coating and/or impregnating one or more layers of the fabric 14 with a
polymeric thermoplastic or thermosetting matrix material 12. The laminate 10
is suitable for use as an electronic support.
Matrix materials useful in the present invention include thermosetting
materials such as thermosetting polyesters, vinyl esters, epoxides (containing
at least one epoxy or oxirane group in the molecule, such as polyglycidyl
ethers of polyhydric alcohols or thiols), phenolics, aminoplasts,
thermosetting
polyurethanes, derivatives and mixtures thereof. Preferred matrix materials
for forming laminates for electronic circuit boards are FR-4 epoxy resins,
polyimides and liquid crystalline polymers, the compositions of that are well
know to those skilled in the art. If further information regarding such
compositions is needed, see 1 Electronic Materials HandbookTM, ASM
International (1989) at pages 534-537.
Non-limiting examples of suitable thermoplastic polymeric matrix
materials include polyolefins, polyamides, thermoplastic polyurethanes and
thermoplastic polyesters, vinyl polymers and mixtures thereof. Further
examples of useful thermoplastic materials include poiyimides, polyether
sulfones, polyphenyl sulfones, polyetherketones, polyphenylene oxides,
polyphenylene sulfides, polyacetals, polyvinyl chlorides and polycarbonates.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
- 52 -
A useful matrix material formulation consists of EPON 1120-A80 epoxy
resin, dicyandiamide, 2-methylirnidazole and DOWANOL PM.
Other components which can be included with the polymeric matrix
material and reinforcing material in the composite include colorants or
pigments, lubricants or processing aids, ultraviolet light (UV) stabilizers,
antioxidants, other fillers and extenders.
The fabric 14 can be coated and impregnated by dipping the fabric 14
in a bath of the polymeric matrix material 12, for example, as discussed in R.
Tummala (Ed.), Microelectronics Packa ing Handbook, (1989) at pages 895-
896, which are hereby incorporated by reference. The polymeric matrix
material 12 and fabric 14 can be formed into a composite or laminate 10 by a
variety of methods which are dependent upon such factors as the type of
polymeric matrix material used. For example, for a thermosetting matrix
material, the laminate can be formed by compression or injection molding,
pultrusion, hand lay-up, or by sheet molding followed by compression or
injection molding. Thermosetting polymeric matrix materials is cured by the
inclusion of crosslinkers in the matrix material and/or by the application of
heat, for example. Suitable crosslinkers useful to crosslink the polymeric
matrix material are discussed above. The temperature and curing time for the
thermosetting polymeric matrix material depends upon such factors as the
type of polymeric matrix material used, other additives in the matrix system
and thickness of the composite, to name a few.
For a thermoplastic matrix material, suitable methods for forming the
composite include direct molding or extrusion compounding followed by
injection molding. Methods and apparatus for forming the composite by the
above methods are discussed in I. Rubin, Handbook of Plastic Materials and
Technoloav (1990) at pages 955-1062, 1179-1215 and 1225-1271, which are
hereby incorporated by reference.
Although not limiting in the present invention, in one embodiment
shown in Fig. 5, composite or laminate 210 includes fabric 214 impregnated
CA 02346111 2001-04-02
wo ooni9oo Pc~rnrs99maa3
- 53 -
with a compatible matrix material 212. The impregnated fabric can then be
squeezed between a set of metering rolls or bars to leave a measured
amount of matrix material, and dried to form an electronic support in the form
of a semicured substrate or prepreg. An electrically conductive layer 250 is
positioned along a portion of a side 252 of the prepreg in a manner to be
discussed below in the specification, and the prepreg is cured to form a
laminate 210 which functions as an electronic support 254 with an electrically
conductive layer. In another embodiment of the invention, and more typically
in the electronic support industry, two or more prepregs are combined with
one or more electrically conductive layers and laminated together and cured
in a manner well known to those skilled in the art, to form an electronic
support. For example, but not limiting the present invention, the prepreg
stack is laminated by pressing the stack, e.g. between polished steel plates,
at elevated temperatures and pressures for a predetermined length of time to
cure the polymeric matrix and form a laminate of a desired thickness. A
portion of one or more of the prepregs can be provided with an electrically
conductive layer either prior to or after lamination and curing such that the
resulting electronic support is a laminate having at least one electrically
conductive layer along a portion of an exposed surface (hereinafter referred
to as a "clad laminate").
Circuits can then be formed from the electrically conductive layers) of
the single layer or multilayered electronic support using techniques well
known in the art to construct an electronic support in the form of an
electronic
circuit board.
If desired, apertures or holes (also referred to as "vias") are formed in
the electronic supports, to allow for electrical interconnection between
circuits
andlor components on opposing surfaces of the electronic support, by any
convenient manner known in the art, including but not limited to mechanical
drilling and laser drilling. More specifically, referring to Fig. 6, an
aperture 360
extends through at least one layer 362 of fabric 312 of an electronic support
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
- 54 -
354 of the present invention. The fabric 312 comprises coated fiber strands
comprising at least one glass fiber having a layer that is compatible with a
variety of polymeric matrix materials as taught herein. In forming the
aperture
360, electronic support 354 is positioned in registry with an aperture forming
apparatus, such as a drill bit 364 or laser tip. The aperture 360 is formed
through a portion 366 of the at least one layer 362 of fabric 312 by drilling
using the drill 364 or laser. After formation of the apertures, a layer of
electrically conductive material is deposited on the walls of the aperture or
the
aperture is filled with an electrically conductive material to facilitate the
required electrical interconnection between one or more electrically
conductive layers (not shown in Fig. 6) on the surface of the electronic
support 354 and/or heat dissipation.
The electrically conductive layer, for example as shown in Figure 5 as
layer 250, can be formed by any method well known to those skilled in the art.
For example but not limiting the present invention, the electrically
conductive
layer is formed by laminating a thin sheet or foil of metallic material onto
at
least a portion of a side of the semi-cured or cured prepreg or laminate. As
an alternative, the electrically conductive layer is formed by depositing a
layer
of metallic material onto at least a portion of a side of the semi-cured or
cured
prepreg or laminate using well known techniques including but not limited to
electrolytic plating, electroiess plating or sputtering. Metallic materials
suitable for use as an electrically conductive layer include but are not
limited
to copper (which is preferred), silver, aluminum, gold, tin, tin-lead alloys,
palladium and combinations thereof.
In another embodiment of the present invention, the electronic support
is in the form of a multilayered electronic circuit board constructed by
laminating together one or more electronic circuit boards (described above)
with one or more clad laminates (described above) and/or one or more
prepregs (described above). If desired, additional electrically conductive
layers can be incorporated into the electronic support, for example along a
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/Z1443
-55-
portion of an exposed side of the multilayered electronic circuit board.
Furthermore, if required, additional circuits can be formed from the
electrically
conductive layers in a manner discussed above. It should be appreciated that
depending on the relative positions of the layers of the multilayered
electronic
circuit board, the board can have both internal and external circuits.
Additional apertures can be formed, as discussed earlier, partially through or
completely through the board to allow electrical interconnection between the
layers at selected locations. It should be appreciated that the resulting
structure can have some apertures that extend completely through the
structure, some apertures that extend only partially through the structure,
and
some apertures that are completely within the structure.
Preferably, the thickness of the laminate forming the electronic support
254 is greater than about 0.051 mm (0.002 inches), and more preferably
ranges from about 0.13 mm (0.005 inches) to about 2.5 mm (about 0.1
inches). For an eight ply laminate of 7628 style fabric, the thickness is
generally about 1.32 mm {0.052 inches). The number of layers of fabric 14 in
the laminate 10 can vary based upon the desired thickness of the laminate.
The resin content of the laminate can range from about 35 to about 80
weight percent, and more preferably about 40 to about 75 weight percent.
The amount of fabric in the laminate can range from about 20 to about 65
weight percent and more preferably ranges from about 25 to about 60 weight
percent.
For a laminate formed from woven E-glass fabric and using an FR-4
epoxy resin matrix material having a minimum glass transition temperature of
about 110°C, the desired minimum flexural strength in the cross machine
or
width direction (generally perpendicular to the longitudinal axis of the
fabric) is
greater than 3 x 10' kg/m2, preferably greater than about 3.52 x 10' kg/m2
(about 50 Kpsi), and more preferably greater than about 4.9 x 10' kg/m2
(about 70 Kpsi) according to IPC-4101 "Specification for Base Materials for
Rigid and Multilayer Printed Boards" at page 29, a publication of The
Institute
CA 02346111 2001-04-02
WO 00/21900 PGT/US99/21443
-56-
for Interconnecting and Packaging Electronic Circuits (December 1997).
IPC-4101 is hereby incorporated by reference in its entirety. In the length
direction, the desired minimum flexural strength in the length direction
{generally parallel to the longitudinal axis of the fabric) is greater than
about 4
x 10' kg/m2, and preferably greater than 4.23 x 10' kglm2. The flexural
strength is measured according to ASTM D-790 and IPC-TM-650 Test
Methods Manual of the Institute for Interconnecting and Packaging
Electronics (December 1994) (which are hereby incorporated by reference)
with metal cladding completely removed by etching according to section
3.8.2.4 of IPC-4101. Advantages of the electronic supports of the present
invention include high flexural strength (tensile and compressive strength)
and high modulus, which can lessen deformation of a circuit board including
the laminate.
Electronic supports of the present invention in the form of copper clad
FR-4 epoxy laminates preferably have a coefficient of thermal expansion from
50°C to 288°C in the z-direction of the laminate ("Z-CTE"),
i.e., across the
thickness of the laminate, of less than about 5.5 percent, and more preferably
ranging from about 0.01 to about 5.0 weight percent, according to IPC Test
Method 2.4.41 (which is hereby incorporated by reference). Each such
laminate preferably contains eight layers of 7628 style fabric, although
styles
106, 108, 1080, 2113, 2116 or 7535 style fabrics can alternatively be used.
In addition, the laminate can incorporate combinations of these fabric styles.
Laminates having low coefficients of thermal expansion are generally less
susceptible to expansion and contraction and can minimize board distortion.
The instant invention further contemplates the fabrication of
multilayered laminates and electronic circuit boards which include at least
one
composite layer made according to the teachings herein and at least one
composite layer made in a manner different from the composite layer taught
herein, e.g. made using conventional glass fiber composite technology. More
specifically and as is well known to those skilled in the art, traditionally
the
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-57-
filaments in continuous glass fiber strands used in weaving fabric are treated
with a starchloil sizing which includes partially or fully dextrinized starch
or
amylose, hydrogenated vegetable oil, a cationic wetting agent, emulsifying
agent and water, including but not limited to those disclosed in Loewenstein
at pages 237-244 (3d Ed. 1993), which is hereby incorporated by reference.
Warp yarns produced from these strands are thereafter treated with a solution
prior to weaving to protect the strands against abrasion during the weaving
process, e.g. poly(vinyl alcohol) as disclosed in U.S. Patent No. 4,530,876 at
column 3, line 67 through column 4, fine 11, which is hereby incorporated by
reference. This operation is commonly referred to as slashing. The polyvinyl
alcohol) as well as the starch/oil size are generally not compatible with the
polymeric matrix material used by composite manufacturers and the fabric
must be cleaned to remove essentially all organic material from the surface of
the glass fibers prior to impregnating the woven fabric. This can be
accomplished in a variety ways, for example by scrubbing the fabric or, more
commonly, by heat treating the fabric in a manner well known in the art. As a
result of the cleaning operation, there is no suitable interface between the
polymeric matrix material used to impregnate the fabric and the cleaned glass
fiber surface, so that a coupling agent must be applied to the glass fiber
surface. This operation is sometime referred to by those skilled in the art as
finishing. The coupling agents most commonly used in finishing operations
are silanes, including but not limited to those disclosed in E. P.
Plueddemann,
Silane Couplina A ents (1982) at pages 146-147, which is hereby
incorporated by reference. Also see Loewenstein at pages 249-256 (3d Ed.
1993). After treatment with the silane, the fabric is impregnated with a
compatible polymeric matrix material, squeezed between a set of metering
rolls and dried to form a semicured prepreg as discussed above. It should be
appreciated that depending on the nature of the sizing, the cleaning operation
and/or the matrix resin used in the composite, the slashing and/or finishing
steps can be eliminated. One or more prepregs incorporating conventional
CA 02346111 2001-04-02
WO 00/21900 PCT/US99121443
-58-
glass fiber composite technology can then be combined with one or more
prepregs incorporating the instant invention to form an electronic support as
discussed above, and in particular a multilayered laminate or electronic
circuit
board. For more information regarding fabrication of electronic circuit
boards,
see 1 Electronic Materials HandbookTM, ASM International (1989) at pages
113-115, R. Tummala (Ed.), Microelectronics Packaging Handbook, (1989) at
pages 858-861 and 895-909, M. W. Jawitz, Printed Circuit Board Handbook
(1997) at pages 9.1-9.42, and C. F. Coombs, Jr. (Ed.), Printed Circuits
Handbook, (3d Ed. 1988), pages 6.1-6.7, which are hereby incorporated by
reference.
The composites and laminates forming the electronic supports of the
instant invention can be used to form packaging used in the electronics
industry, and more particularly first, second and/or third level packaging,
such
as that disclosed in Tummala at pages 25-43, which is hereby incorporated
by reference. In addition, the present invention can also be used for other
packaging levels.
The present invention will now be illustrated by the following specific,
non-limiting examples.
EXAMPLE 1
Electrical grade laminates made from prepregs incorporating fabrics
with yarns having different sizing compositions were tested to evaluate their
drilling properties, and more specifically, (i) the drill tip wear of drills
used to
drill holes through the laminates and (ii) the locational accuracy of the
holes
drilled through the laminates. Control A and Sample B were laminates
incorporating a 7628 style fabric as discussed earlier. The fabric in Control
A
was a heat cleaned and silane finished fabric commercially available from
Clark Schwebel and identified as 7628-718. The fabric in Sample B was
woven from yarn comprising glass fibers coated with a resin compatible sizing
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/Z1443
-59-
as taught herein and shown in Table 1. The glass fibers woven into Sample
B had a loss on ignition of 0.35 percent.
Table 1
5 Weight Percent of Comraonents on Total Solids Basis
for Sizing used in Sample B
COMPONENT Sample
B
thermoplastic polyester film-forming 27.0
polymer94
thermoplastic polyester film-forming 36.2
polymer 95
polyvinyl pyrrolidone96 9.0
epoxy-functional organo silane coupling2.1
agent97
acrylic-functional organo silane coupling4.4
agent98
polyoxyalkylene block copolymer99 9.0
polyamidel 00 4.4
emulsifying agent101 5.4
boron nitride powder particles102 0.9
25 wt% boron nitride aqueous dispersion1031.5
acetic acid <0.1
~ RD-847A polyester resin, which is commercially available from Borden
Chemicals of Columbus,
Ohio.
95 DESMOPHEN 2000 polyethylene adipate diol, which is commercially available
from Bayer of
Pittsburgh, Pennsylvania.
96 pup K_30 polyvinyl pyrrolidone, which is commercially available from ISP
Chemicals of Wayne,
New Jersey.
97 A-187 gamma-glycidoxypropyltrimethoxysilane, which is commercially
available from OSi
Specialties, Inc. of Tarrytown, New York.
9 A-174 gamma-methacryloxypropyltrimethoxysilane, which is commercially
available from OSi
Specialties, Inc. of Tarrytown, New York.
9 PLURONICTM F-108 polyoxypropylene-polyoxyethylene copolymer, which is
commercially
available from BASF Corporation of Parsippany, New Jersey.
100 VERSAMID 140 polyamide, which is commercially available from General Mills
Chemicals,
Inc.
101 MACOL NP-6 nonyl-phenol surtactant, which is commercially available from
BASF of
Parsippany, New Jersey.
102 polarTherm~ PT 160 boron nitride powder particles, which are commercially
available from
Advanced Ceramics Corporation of Lakewood, Ohio.
103 ORPAC BORON NITRIDE RELEASECOAT-CONC, which is commercially available from
ZYP
Coatings, Inc. of Oak Ridge,
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-60-
Prepregs were prepared by a hand lay-up procedure that involved
applying standard FR-4 epoxy resin (EPON 1120-A80 resin available from
Shell Chemical co.) to the fabrics using a paintbrush. The resin saturated
fabric was immediately "dried" and B-stages in a vented hot air oven for about
3 to about 3.25 minutes' at 163°C (325°F) until the desired gel
time of 124
seconds at 171 °C (340°F) was reached. The prepregs were trimmed
to 46
cm by 46 cm (18 inch by 18 inch) sections and weighed to determine resin
content. Only prepregs with resin contents of 44 percent ~ 2 percent were
used in the subsequent laminating procedure.
Prepregs were stacked 8 high and molded in a Wabash Press for 70
minutes at 177°C (350°F) and at 345 newtons/cm2 (500 psi). All
the
laminates were molded without copper foil layers. The laminates showed
various levels of air entrapment. It is believed that the lack of vacuum
assist
and temperature vamping during lamination contributed to this condition.
Tool Wear Analysis
The first series of tests were conducted to evaluate the wear of the drill
tip. The tip wear was expressed in terms of "drill tip percent wear" which was
calculated using the formula:
drill tip percent wear = 100 x (P; Pf)/P
where P; = initial width of the primary cutting edge
P, = width of the primary cutting edge after the allotted
holes were drilled.
Referring to Fig. 7, the width 470 of the primary cutting edge 472 of the
drill
474 was measured at the peripheral edge of the drill tip.
The drilling was conducted using a single head drilling machine. The
drilling was performed on 3-high stacks of laminates (discussed above) with a
0.203 mm (0.008 inch) thick aluminum entry and 1.88 mm (0.074 inch) thick
paper core phenolic coated back-up. Drilling 3 laminates at one time is
generally standard practice in the industry. The drill tip percent wear was
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-61 -
determined for two drill diameters: 0.35 mm (0.0138 inches) and 0.46 mm
(0.018 inches). Both drills were a series 508 tungsten carbide drill available
from Tulon Co., Gardenia, California. The chip load during drilling was held
constant at 0.001 for each tool. As used herein, "chip load" means the ratio
of the drill insertion rate measured in inches per minute to the spindle speed
measured in revolutions per minute (rpm). For the 0.35 mm drill, the spindle
speed was 100,000 rpm and the insertion rate was 100 inches (254 cm) per
minutes. For the 0.46 mm drill, the spindle speed was 80,000 rpms and the
insertion rate~was 80 inches (203 cm) per minute. A retraction rate of 2.54 m
(1000 inches) per minute and a 1.65 mm (0.065 inch) upper drill head limit
was held constant for both tool diameters. As use herein, "drill head limit"
means the distance that the drill tip was withdrawn above the upper surface of
the laminate.
The drill tip percent wear was determined based on a 500 hole drilling
pattern shown in Fig. 8 which included 391 holes drilled in a 0.635 cm by
10.16 cm (0.25 inch by 4 inch) block (section 580), followed by 100 holes in a
10 by 10 hole pattern (section 582), followed by 9 holes in a 3 by 3 hole
pattern (section 584). The holes in each section were drilled at a hole
density
of 62 holes per square centimeter (400 hole per square inch). The pattern
was repeated three additional times for a total of 2000 holes. The drilling
for
Tests 1 and 2 was done using a Uniline 2000 single head drilling machine
and the drilling for Test 3 was done using a CNC-7 single head drilling
machine. Both machines are available from Esterline Technologies,
Bellevue, Washington.
Table 2 shows the drill tip percent wear of the drill for Control A and
Sample B for the 0.35 and 0.46 mm diameter drills after drilling 2000 holes in
the pattern discussed above. Each test was started with a new drill bit.
CA 02346111 2001-04-02
WO 00/Z1900 PCT/US99/21443
-62-
Table 2
Control Sample
A B
Test 1 number of tools 3 3
0.35 mm dia. average drill 28.8 22.2
drill tip
percent wear
Test 2 number of tools 20 20
0.46 mm dia. average drill 34.0 24.4
drill tip
percent wear
Test 3 number of tools 10 10
0.46 mm dia. average drill 30.8 29.3
drill tip
percent wear
As can be seen in Table 2, Sample B in Tests 1 and 2, which
includes glass fiber filaments coated with a sizing as taught herein that is
compatible with laminate matrix resins, exhibited significantly less drill tip
percent wear after 2000 holes than Control A, which includes glass fiber
filaments that had to be heat cleaned prior to being coated with a silane
containing finishing sizing. Test 3 showed only a marginal improvement in
drill tip percent wear but it is believed that this is due to the fact that
the
~ CNC-7 drilling machine used in this test was older and afforded less control
during the drilling test than the Uniline 2000 drilling machine used for Tests
1
and 2.
Locational Accuracy
A common metric used to assess the drilling performance of a
laminate is hole locational accuracy. This test measures the deviation in the
distance of the actual hole location from its intended location. The
measurement was taken on lower surface of the bottom laminate of a 3
laminate stack where the drill exited the laminate stack, since it is expected
that this hole location would have the largest discrepancy from the intended
or "true" hole location. This difference was assessed in terms of the
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-63-
"deviation distance", i.e. the distance from the actual true center of the
drilled
hole on the surface of the laminate to the intended true center of the hole.
The deviation distance was measured after the 500 hole sequence discussed
above was repeated 4 times, i.e. after each tool drilled a total of 2000
holes.
The deviation distance was measured for the last drilled 100 hole pattern,
i.e.
the last drilled section 582. The holes were drilled using a 0.46 mm {0.018
inch) diameter series 508 drill from Tulon Co. of the type discussed above.
As was used in the tool wear test, the spindle speed for the drill was 80,000
rpms and the insertion rate was 80 inches per minute for a chip load of 0.001.
The test was repeated eight times for each Control A and Sample B with each
test starting with a new drill.
Table 3 shows the result of the locational accuracy test for Control A
and Sample B after drilling 2000 holes.
Table 3
Control Sample B
A
number of drills 8 8
average deviation distance 38 28
(micrometer)
As can be seen, Sample B exhibited a lower deviation distance than
Control A, which is of particular significance when the laminate is used as an
electronic support incorporating a large number of holes and circuits. This is
consistent with the drill tip percent wear data shown in Table 2 above. More
specifically, it would be expected that laminates that exhibit less drill tip
percent wear would also exhibit less deviation distance because the drill tips
would be sharper for a longer number of drillings.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-64-
EXAMPLE 2
In Example 2, additional drill tool percent wear tests were conducted.
Electrical grade laminates Control C and Samples D, E and F incorporating a
7628 style fabric as discussed earlier were tested for drill tool percent
wear.
The fabric in Control C was 7628-718 fabric from Clark-Schwebel, Inc. The
fabrics in Samples D, E and F were woven from fill yarn comprising glass
fibers coated with a resin compatible sizing as taught herein and shown in
Table 4, and warp yarn having glass fibers coated with a different polymeric
matrix material compatible coating composition'°4.
'°'' The warp yarn was PPG Industries, Inc.'s commercially available
fiber glass yarn product
designated as G-75 glass fiber yarn coated with PPG Industries, Inc.'s 9383
binder.
CA 02346111 2001-04-02
WO 00/21900 PGT/US99121443
-65-
Table 4
Weigiht Percent of Components on Total Solids Basis
for Sizing used in Samples D. E and F
WEIGHT
PERCENT
OF
COMPONENT
ON TOTAL
SOLIDS
BASIS
Sample
COMPONENT D E F
Pol vinyl P rrolidone13.4 14.7 13.4
Cetyl Palmitate 0 29.9 27.3
Epoxy-functional organo1.9 1.8 1.6
silane couplin a ent107
Acrylic-functional 3.8 3.7 3.3
organo-
silane coupling a
ent108
Softening Agent 1.9 2.4 2.2
Emulsi ing Agent 0 1.6 1.5
Emulsi ing Agent 0 3.3 3.0
Antifoaming Agent 0 0.2 0.2
Antifoaming Agent 0.2 0 0
Styrene/Acrylic Copolymer0 42.4 0
Hollow Particle
Dispersionl 14
Styrene/Acrylic Copolymer0 0 38.6
Hollow Particle
Dispersionl 15
,05 pup K-30 polyvinyl pyrrolidone which is commercially available from ISP
Chemicals of
Wayne, NJ.
'oe STEPANTEX 653 which is commercially available from Stepan Company of
Maywood, NJ
'°' A-187 gamma-glycidoxypropyltrimethoxysilane which is commercially
available from OSi
Specialties, Inc. of Tarrytown, NY.
'°e A-174 gamma-methacryloxypropyltrimethoxysilane which is
commercially available from
OSi Specialties, Inc. of Tarrytown, NY.
'°9 EMERY~ 6717 partially amidated polyethylene imine which is
commercially available from
Henkel Corporation of Kankakee, IL.
"° MACOL OP-10 ethoxylated alkylphenol which is commercially available
from BASF Corp.
of Parsippany, NJ.
"' TMAZ-81 ethylene oxide derivative of a sorbitol ester which is commercially
available from
BASF Corp. of Parsippany, NJ.
"2 MAZU DF-136 antifoaming agent which is commercially available from BASF
Corp. of
Parsippany, NJ.
"3 SAG 10 antiforming material which is commercially available from OSi
Specialties, Inc. of
Danbury, Connecticut.
"4 ROPAQUE~ HP-1055, 1.0 micron particle dispersion which is commercially
available from
Rohm and Haas Company of Philadelphia, PA.
"5 ROPAQUE~ OP-96, 0.55 micron particle dispersion which is commercially
available from
Rohm and Haas Company of Philadelphia, PA.
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/Z1443
-66-
Boron Nitride 3.8 0 6.3
Dispersionl 16
Boron Nitride Powder 5.9 0 2.6
Thermoplastic polyester23.0 0 0
film-forming pol mer118
Thermoplastic polyester31.0 0 0
film-forming polymer119
Polyoxyalkylene block8.4 0 0
copolymer120
Polyoxyethylated vegetable2.5 0 0
oi1121
Alkoxylated nonyl 4.2 0 0
phenol122
LOI 0.35 0.4-0.480.34-0.36
The fabrics were subsequently formed into prepregs with an FR-4
epoxy resin having a Tg of about 140°C (designated 4000-2 resin by
Nelco
International Corporation of Anaheim, CA). The sizing compositions were not
removed from the fabric prior to pre-pregging. Laminates were made by
stacking 8-plies of the prepreg material and four layers of 1 ounce copper (as
shown below) and laminating them together at a temperature of about
355°F
(about 179°C), pressure of about 300 pounds per square inch (about 2.1
megaPascals) for about 150 minutes (total cycle time). The thickness of the
laminates with copper ranged from about 0.052 inches {about 0.132 cm) to
about 0.065 inches (0.165 cm). In forming the laminates, eight prepregs were
"s ORPAC BORON NITRIDE RELEASECOAT-CONC boron nitride dispersion which is
commercially available from ZYP Coatings, lnc, of Oak Ridge, TN.
"' PolarTherm~ PT 160 boron nitride powder which is commercially available
from Advanced
Ceramics Corporation of Lakewood, OH.
"e RD-847A polyester resin which is commercially available from Borden
Chemicals of
Columbus, Ohio.
"9 DESMOPHEN 2000 polyethylene adipate diol which is commercially available
from Bayer
of Pittsburgh, Pennsylvania.
'z° PLURONtCT"~ F-108 polyoxypropylene-polyoxyethylene copolymer which
is commercially
available from BASF Corporation of Parsippany, New Jersey.
'2' ALKAMULS EL-719 polyoxyethylated vegetable oil which is commercially
available from
Rhone-Poulenc.
'22 ICONOL NP-6 alkoxylated nonyl phenol which is commercially available from
BASF
Corporation of Parsippany, New Jersey.
~~..~.".~...~...~...... . ..._ .~. .-,.. _... . .m -..... ~_..
...,~"a.~~,..... . w..
CA 02346111 2001-04-02
WO 00/21900 PCT/US99/21443
-67-
stacked with copper layers in the following arrangement:
one 1 oz/ft2 shiny copper layer
three prepreg layers
one 1 oz/ftz RTF (reverse treated foil) copper layer
two prepreg layers
one 1 oz/ftZ RTF copper layer
three prepreg Payers
one 1 oz/ft2 shiny copper layer
The finished laminates were trimmed to 40.6 cm by 50.8 cm (16 inches by
20 inches).
The drilling was conducted using a Uniline 2000 single head drilling
machine. The drilling was performed on 3-high stacks of laminates
(discussed above) with a 0.010 inch (0.254 mm) thick aluminum entry and
0.1 inch (2.54 mm) thick aluminum clad particle board back-up. The drill tool
percent wear was determined for a 0.34 mm (0.0135 inches) tool diameters,
series 80 tungsten carbide drill available from Tulon Co., Gardenia, CA. The
chip load during drilling was held constant at 0.001, with a spindle speed of
95,000 rpm and insertion rate of 95 inches (241 cm) per minutes. The drill
retraction rate was 90 inches {2.29 m) per minute and the upper drill head
limit was 0.059 inches (1.5 mm) upper drill head limit.
The drill tip percent wear was examined based on a 1500 and 2500
hole drilling pattern. The holes in each section were drilled at a hole
density
of 28 holes per square centimeter (about 178 hole per square inch).
Table 2 shows the drill tip percent wear of the for Control C and
Samples D, E and F after drilling 1500 and 2500 holes. Each set of holes
was started with a new drill bit and each stack of laminates had ten 1500 hole
groupings and ten 2500 hole groupings. Three stacks of laminates of each
fabric type were drilled so that the drill tip percent wear for 30 drills were
measured for each sample.
CA 02346111 2001-04-02
WO 00/21900 PCTNS99/21443
-ss-
Table 5
Drill
Tip Percent
Wear
Control Sample Sample Sample
C D E F
1500 holes24.9 19.8 21.5 19.5
2500 holes28.3 25.3 28.0 24.3
As can be seen in Table 5; Samples D, E and F, which includes glass
fiber filaments coated with a sizing as taught herein that is compatible with
laminate matrix resins, exhibited significantly less percent wear after 1500
holes than Control A, which includes glass fiber filaments that had to be heat
cleaned prior to being coated with a silane containing finishing sizing. After
2500 holes, the amount of drill tool percent wear for Samples D, E and F is
still less than for Control C but less pronounced. This is to be expected
since
the majority of the tool wear will occur during the earlier drilled holes
rather
than the last holes drilled in a grouping.
Based in the above, although not limiting in the present invention, it is
preferred that prepregs made with glass fiber fabric coated with a polymeric
matrix compatible sizing as taught herein have a drilling tip percent wear of
no
greater than about 32 percent, more preferably no greater than about 30
percent, and most preferably no greater than about 25 percent, as
determined after drilling 2000 holes through a stack of 3 laminates, each
laminate including eight prepregs, at a hole density of 400 holes per square
inch and a chip load of 0.001 with a 0.46 mm (0.018 inch) diameter tungsten
carbide drill.
In addition, based in the above, although not limiting in the present
invention, it is preferred that prepregs made with glass fiber fabric coated
with
a polymeric matrix compatible sizing as taught herein have a deviation
distance of no greater than about 36 micrometers, more preferably not
CA 02346111 2001-04-02
wo ooni9oo PcT~s99maa3
-69-
greater than about 33 micrometers, and most preferably not greater than
about 31 micrometers, as determined after drilling 2000 holes through a stack
of 3 laminates, each laminate including eight prepregs, at a hole density of
400 holes per square inch and a chip load of 0.001 with a 0.46 mm (0.018
inch) diameter tungsten carbide drill.
Although not meaning to be bound by any particular theory, it is
believed that the presence of a solid lubricant in the glass fiber coating
composition disclosed herein, and in one particular embodiment, the
presence of the boron nitride, contributes to the improved drilling properties
of
the laminates of the present invention. More particularly, the solid lubricant
contributes to the reduction in drill wear and improvement in locational
accuracy of the drilled holes.
Improved drilling properties in laminate made with glass fibers coated
with a resin compatible sizing as taught herein provides several advantages.
First, longer drill life means that each drill bit can drill more holes before
resharpening or disposal. In addition, because the locational accuracy of the
holes drilled through the laminates of the present invention is greater than
that for conventional laminates, it is expected that more than three laminates
can be stacked for drilling at a single time with the same accuracy as that
achieved in a 3 laminate stack of conventional laminates. Both of these
advantages result is a more cost effective drilling operation. Furthermore,
the
locational accuracy of the holes drilled in the laminates is improved so that
the quality of the electronic support incorporating the laminate in improved.
It will be appreciated by those skilled in the art that changes could be
made to the embodiments described above without departing from the broad
inventive concept thereof. It is understood, therefore, that this invention is
not limited to the particular embodiments disclosed, but it is intended to
cover
modifications that are within the spirit and scope of the invention, as
defined
by the appended claims.
