Note: Descriptions are shown in the official language in which they were submitted.
PF71188 CA 02806936 2013-01-29
1
As originally filed
Carrier fluids for abrasives
Description
The invention relates to the use of modified polyglycols for producing carrier
fluids for
abrasives, novel carrier fluids for abrasives, in particular cutting fluids,
the use of the
carrier fluid in the removal of material, in particular in the cutting of
wafers and also
wafers produced with the aid of the cutting fluid.
Abrasives, also known as grinding agents or abrasive materials, are materials,
preferably grains of hard material, which are utilized for removing a
material. The use
of abrasives as a dispersion in fluids, for example grinding fluids or cutting
fluids, is
known. Abrasives can in this way be used for polishing wafers, for example
silicon
wafers, and also for polishing plastics, for example for lenses. Furthermore,
the use of
abrasives in cutting fluids for cutting wafers is also known. Wafers are thin
slices of
semiconductors which are used, for example, in photovoltaics. Electronic
components,
especially integrated circuits, can be produced from wafers. The wafers
generally
comprise a brittle material, for example silicon, but may also be made of
gallium
arsenide or cadmium telluride, etc. Wafers are generally produced from
cylindrical or
cubic monocrystals or polycrystals which are sawn into the individual slices,
viz, the
wafers. The sawing (also referred as cutting or lapping) is an industrial
practice carried
out by wire sawing. This is a parting process using a thin wire as cutter and
using
unbounded cutting grains in a carrier fluid. The wire generally has a diameter
of from
80 to 180 pm. It dips into a slurry of carrier fluid and cutting grain and
draws the cutting
grains adhering to the wire surface into the saw cut. The object/silicon
block, known as
ingot, to be sawn/lapped is cut by means of the cutting grains into wafers,
with particles
being removed from the solid to be cut. The carrier fluid for the cutting
grains is applied
together with the cutting grains as slurry via an immersion bath through which
the wire
runs or, in general, via nozzles. The carrier fluid has, inter alia, the task
of effecting
adhesion of the cutting grains to the wire and carrying particles of removed
material
from the solid to be parted. Furthermore, the carrier fluid has the task of
providing
cooling and transport of the abraded material through the saw cut.
A process for parting a workpiece, for example a wafer, by means of wire
sawing is
known from EP 1 757 419 Al; here, a slurry applied to the wire is used and the
water
content of at least part of the gaseous medium surrounding the slurry is
regulated or
controlled. Furthermore, the use of glycols as carrier substance is known from
EP 1 757 419 Al.
PF 71188 CA 02806936 2013-01-29
= 2
A cutting oil comprising a) a polyether compound and b) silica particles and
the use of
this cutting oil composition for cutting an ingot using a wire saw, in
particular for cutting
silicon ingots, is known from DE 199 83 092 B4 and US 6,383,991 B1.
Water-based lubricants based on polyethers are known from EP 0 131 657 Al and
US-A-4,828,735. Cutting fluids are likewise known from the Chinese patent
application
CN 101205498 A; a reduction in the water uptake is not indicated here. The
compounds specifically mentioned are polyalkyleneoxy compounds which are
etherified with alcohols having from 1 to 4 carbon atoms.
EP 686 684 Al discloses a sawing suspension comprising an abrasive material in
an
aqueous phase comprising one or more water-soluble polymers as thickeners.
US 2007/0010406 Al discloses hydroxy polyethers as additives for aqueous
cutting
fluids which can be used, inter alia, for producing silicon wafers.
The known cutting fluids are generally based on an aqueous or water-soluble
base.
However, the presence of water is disadvantageous because it can cause
corrosion
and it is also possible, for example, for hydrogen to be evolved when cutting
silicon
wafers as a result of reaction of water and silicon. An additional problem
here is that
silicate or polysilicate formation occurs on the wafer and in the slurry.
The known water-soluble systems, too, can comprise water and, owing to their
microscopic properties, attract water so that the same disadvantages as in
aqueous
systems can occur.
It was an object of the invention to provide improved carrier fluids for
abrasives, in
particular cutting fluids, which, in particular, lead to a reduction in the
water uptake and
a reduction in the energy required for sawing.
The invention provides for the use of compounds of the formula I
R1 [0 (E0)õ (AO) y H],
where
R1 is a z-valent alkyl radical having from 1 to 20 carbon atoms
(E0) is an ethyleneoxy radical
(AO) is an alkyleneoxy radical having from 3 to 10 carbon atoms
is an integer from 3 to 12, in particular from 5 to 10
y is an integer from 0 to 10, in particular from 4 to 8
= PF 71188 CA 02806936 2013-01-29
, , 1 3
z is an integer from 1 to 6, in particular from 1 to 3,
for producing carrier fluids for abrasives, in particular cutting fluids,
having a reduced
water uptake for removal of material, in particular for sawing wafers by means
of a wire
saw.
The invention further provides carrier fluids for abrasives, in particular
cutting fluids,
comprising at least one compound of the formula 1
Fe [0 (E0), (AO)y H],
where
R1 is a z-valent alkyl radical having from 5 to 10 carbon atoms
(E0) is an ethyleneoxy radical
(AO) is an alkyleneoxy radical having from 3 to 10 carbon atoms
x is an integer from 3 to 12, in particular from 5 to 10
y is an integer from 0.5 to 10, in particular from 4 to 8
z is an integer from 1 to 6, in particular from 1 to 3.
The invention further provides novel compounds 11 of the formula
R1 0 (E0)x (AO)y H
where
R1 is 2-methylbutyl or 3-methylbutyl
(E0) is an ethyleneoxy radical
(AO) is an alkyleneoxy radical having from 3 to 10 carbon atoms
x is an integer from 3 to 12, in particular from 5 to 10
y is an integer from 0 to 10, in particular from 4 to 8
z is an integer from 1 to 6, in particular from 1 to 3
In preferred compounds of the formula II, at least as many E0 units as PO
units are
present. Very particularly preferred compounds of the formula II are shown in
the
following table:
Compound R1 x Y
11.1 2-methylbutyl 5.5 5.5
11.2 2-methylbutyl 5.0 6.0
PF 71188 CA 02806936 2013-01-29
4
In a preferred embodiment, the ratio of x to y in the compound of the formulae
I and II
is equal to or less than 1.
For the purposes of the present invention, compounds of the formula II are
particularly
preferred embodiments of compounds of the formula I.
In a preferred embodiment,
in formula I: R1 is a pentyl radical, preferably
H3C-CHCH3-CH2-CH2- (3-methylbutyl) and
H3C-CH2-CHCH3-CH2- (2-methylbutyl), in particular at least
10% of 3-methylbutyl
In formulae I and II: AO is propyleneoxy, butyleneoxy and pentyleneoxy or a
mixture
thereof.
In the case of the compounds of the formulae I and II, the recurring units
(EO) and
(AO) can be present as a block or randomly distributed. In a preferred
embodiment,
they are randomly distributed. It has surprisingly been found that the
viscosity of the
compounds is largely independent of temperature when the recurring units (AO)
and
(EO) are randomly distributed. In particular, when the recurring units (EO)
and (AO) are
randomly distributed, the compounds of the formula I to be used according to
the
invention have a viscosity index in a slurry comprising 40% by weight of
silicon carbide
of the type Carborex F 800 PV from Washington Mills AS, NO-7300 Orkanger,
Norway,
of not more than 45%, preferably less than 30%, in particular less than 20%,
with the
viscosity index being defined as follows: the viscosity index is, for the
purposes of the
present invention, the percentage decrease in the viscosity of the compounds
of the
formula I at 50 C compared to the viscosity at 30 C. The viscosity here is the
dynamic
viscosity (Brookfield, spindle V-73) determined in accordance with DIN EN
12092.
The carrier fluids of the invention can not only comprise one compound of the
formula I
but also mixtures of compounds of the formula I.
The preparation of compounds of the formula I is known per se, see, for
example,
Nonionic Surfactants, edited by Martin J. Schick, Volume 2, Chapter 4 (Marcel
Dekker,
Inc., New York 1967). The preparation of the novel compounds of the formula II
can be
carried out in an analogous way.
In a preferred embodiment, the carrier fluids for abrasives, in particular
cutting fluids,
consist of the compound of the formula I. The molecular weight of the compound
of the
, PF 71188 CA 02806936 2013-01-29
. , t 5
formula I is preferably from 200 to 1200 g/mol. In a further preferred
embodiment,
alkylene alcohols based on ethylene oxides, propylene oxides or copolymers of
ethylene oxides and propylene oxides, preferably having a molecular weight of
from
200 to 800 g/mol are comprised in addition to the compounds of the formula I.
In use
for sawing, the cutting fluid comprises abrasives, in particular cutting
grains, in addition
to the compound of the formula I.
In a further preferred embodiment, the carrier fluids for abrasives, in
particular cutting
fluids, are combined with at least one further additive, in particular with at
least one
monoalkylene, oligoalkylene or polyalkylene glycol,
wetting agent,
thickener,
dispersant,
corrosion inhibitor,
complexing agent and/or
other additives such as scale inhibitors
to form a carrier fluid.
Preference is given to at least one of the following additives being added in
the
following parts by weight per 100 parts by weight of the compound I:
alkylene glycols: from 10 to 90, in particular from 20 to 60, parts by weight
wetting agent: from 1 to 100, in particular from 10 to 40, parts by weight
thickener: from 0.5 to 20, in particular from 1 to 10, parts by weight
dispersant: from 0.1 to 20, in particular from 0.5 to 10, parts by weight
corrosion inhibitor: from 0.1 to 10, in particular from 0.1 to 3, parts by
weight
complexing agent: from 0.1 to 10, in particular from Ito 5, parts by weight
other additives: from 0.05 to 10, in particular from 0.1 to 5, parts by weight
The water content of the composition according to the invention is, based on
the total
composition, not more than 10% by weight, preferably not more than 5% by
weight, in
particular less than 1% by weight.
' PF 71188 CA 02806936 2013-01-29
. , 1
6
Particularly preferred additives are indicated below:
Wetting agents
In addition to the compounds of the formula Ito be used according to the
invention, it is
possible to use further wetting agents, in particular
(1) Poly(oxyalkylene) derivatives of
a) sorbitan esters, e. g. poly(oxyethylene)sorbitan monolaurate,
poly(oxyethylene)sorbitan monooleate, poly(oxyethylene)sorbitan trioleate
b) fatty amines, e.g. tallow amino ethoxylates, soy amino ethoxylates,
c) castor oil, e.g. castor oil ethoxylates,
d) alkanolamides, e.g. coconut oil alkanolamide ethoxylates,
e) fatty acids, e.g. oleic acid ethoxylates, lauric acid ethoxylates,
palmitic acid
ethoxylates,
f) fatty alcohols,
9) linear alcohol ethoxylates, nonylphenol ethoxylates, octylphenol
ethoxylates
(2) Hydrophilic polydimethylsiloxanes
a) poly(dimethyl)siloxane substituted by at least one carbonyl end group,
poly(dimethyl)siloxane copolymers,
c) poly(dimethylsiloxane)-b-poly(propylene oxide)-b-poly(ethylene oxide)
copolymers,
d) polyquarternary (dimethylsiloxane) copolymers
(3) Fatty imidazolines
(4) Fatty acid esters of
a) phosphates,
b) sorbitans,
c) glycerol compounds, e.g.
glyceryl monooleate, glyceryl dioleate, glyceryl trioleate, dilaurate,
e) sulfosuccinic acid,
(5) Quaternary compounds e.g.
quaternary ammonium methosulfate.
Further suitable nonionic, cationic, anionic or amphoteric wetting agents are,
in
particular
' PF 71188 CA 02806936 2013-01-29
t 7
- alkoxylated C4-C22-alcohols such as fatty alcohol alkoxylates or oxo
alcohol
alkoxylates. These can be alkoxylated by ethylene oxide, propylene oxide
and/or
butylene oxide. All alkoxylated alcohols which have at least two molecules of
one
of the abovementioned alkylene oxides added on can be used as wetting agents.
Possible compounds of this type are block polymers of ethylene oxide,
propylene
oxide and/or butylene oxide or addition products which comprise the
abovementioned alkylene oxides distributed randomly or in blocks. The nonionic
wetting agents generally comprise from 2 to 50 mol, preferably from 3 to 20
nnol, of
at least one alkylene oxide per mole of alcohol. The alcohols preferably have
from
10 to 18 carbon atoms. Depending on the type of alkoxylation catalyst used in
the
preparation, the method of preparation and the work-up, the alkoxylates have a
broad or narrow alkylene oxide homologue distribution;
- alkylphenol alkoxylates such as alkylphenol ethoxylates having C6-C14-alkyl
chains
and from 5 to 30 alkylene oxide units;
- alkyl polyglucosides having from 8 to 22, preferably from 10 to 18, carbon
atoms in
the alkyl chain and generally from 1 to 20, preferably from 1.1 to 5,
glucoside units,
sorbitan alkanoates, also alkoxylated;
- N-alkylglucamides, fatty acid alkoxylates, fatty acid amine alkoxylates,
fatty acid
amide alkoxylates, fatty acid alkanolamide alkoxylates, alkoxylated, block
copolymers of ethylene oxide, propylene oxide and/or butylene oxide,
polyisobutene ethoxylates, polyisobutene-maleic anhydride derivatives,
optionally
alkoxylated monoglycerides, glyceryl monostearates, sorbitan esters and
bisglycerides.
Particularly useful nonionic wetting agents are alkyl alkoxylates or mixtures
of alkyl
alkoxylates, as are described, for example, in DE-A 102 43 363, DE-A 102 43
361,
DE-A 102 43 360, DE-A 102 43 365, DE-A 102 43 366, DE-A 102 43 362 or
DE-A 43 25 237. These are alkoxylation products obtained by reaction of
alkanols with
alkylene oxides in the presence of alkoxylation catalysts or mixtures of
alkoxylation
products. Particularly suitable starter alcohols are the Guerbet alcohols, in
particular
ethylhexanol, propylheptanol and butyloctanol. Particular preference is given
to
propylheptanol. Preferred alkylene oxides are propylene oxide and ethylene
oxide, with
alkyl alkoxylates having a direct bond between a preferably short
polypropylene oxide
block and the starter alcohol, as are described, for example, in DE-A 102 43
365, being
particularly preferred because of their low residual alcohol content and their
good
biodegradability.
A preferred class of suitable nonionic wetting agents are the alcohol
alkoxylates of the
general formula (NI)
PF 71188 CA 02806936 2013-01-29
, , 8
R1-0-(CH2-CHR5-0-)1(CH2-CH2-0-)n(CH2-CHR6-0-)5(CH2-CHR2-0-),,H (NI)
where
R1 is an at least singly branched C4_22-alkyl or -alkylphenol,
R2 is C3_4-alkyl,
R6 is C1.4-alkyl,
R6 is methyl or ethyl,
n is an average value of from 1 to 50,
m is an average value of from 0 to 20, preferably from 0.5 to 20,
r is an average value of from 0 to 50,
s is an average value of from 0 to 50,
where n is at least 0.5 when R6 is methyl or ethyl or r is 0.
A mixture of from 20 to 95% by weight, preferably from 30 to 95% by weight, of
at least
one abovementioned alkyl alkoxylate and from 5 to 80% by weight, preferably
from 5 to
70% by weight, of a corresponding alcohol alkoxylate in which R1 is, however,
an
unbranched alkyl radical having the same number of carbon atoms is also
possible.
Furthermore, alcohol alkoxylates of the general formula (NII)
R3-0-(CH2-CH2-0)p (CH2-CHR4-0-)qH (Nil)
where
R3 is branched or unbranched C.4_22-alkyl or -alkylphenol,
R4 is C3_4-alkyl,
p is an average value of from 1 to 50, preferably from 4 to 15,
a is an average value of from 0.5 to 20, preferably from 0.5 to 4, more
preferably
from 0.5 to 2,
are also suitable.
A mixture of from 5 to 95% by weight of at least one branched alcohol
alkoxylate (N II)
as described directly above and from 5 to 95% by weight of a corresponding
alcohol
alkoxylate in which, however, an unbranched alkyl radical is present in place
of a
branched alkyl radical is also possible.
In the alcohol alkoxylates of the general formula (NI), R2 is preferably
propyl, in
particular n-propyl.
4 PF 71188 CA
02806936 2013-01-299
In the alcohol alkoxylates of the general formula (Nil), n preferably has an
average
value of from 4 to 15, particularly preferably from 6 to 12, in particular
from 7 to 10.
m preferably has an average value from 0.5 to 4, particularly preferably from
0.5 to 2, in
particular from 1 to 2.
The radical R1 is preferably a C8_15-, particularly preferably C8_13-, in
particular C8_12-alkyl
radical which is at least singly branched. It is also possible for a plurality
of branches to
be present.
R6 is preferably methyl or ethyl, in particular methyl.
R6 is preferably ethyl.
In the mixtures, compounds having unbranched and branched alcohol radicals R1
are
present. This is the case, for example, for oxo alcohols which have a
proportion of
linear alcohol chains and a proportion of branched alcohol chains. For
example, a C13115
oxo alcohol frequently has about 60% by weight of completely linear alcohol
chains
together with about 40% by weight of a-methyl-branched and C>2-branched
alcohol
chains.
In the alcohol alkoxylates of the general formula (NII), R3 is preferably a
branched or
unbranched C8_15-alkyl radical, particularly preferably a branched or
unbranched
C8_13-alkyl radical and in particular a branched or unbranched C8.12-alkyl
radical. R4 is
preferably propyl, in particular n-propyl. p preferably has an average value
of from 4 to
15, particularly preferably an average value of from 6 to 12 and in particular
an average
value of from 7 to 10. q preferably has an average value of from 0.5 to 4,
particularly
preferably from 0.5 to 2, in particular from 1 to 2.
In a manner analogous to the alcohol alkoxylates of the general formula (NI),
the
alcohol alkoxylates of the general formula (N II) can also be present as
mixtures having
unbranched and branched alcohol radicals.
Possible alcohol components on which the alcohol alkoxylates are based include
not
only pure alkanols but also homologous mixtures having a range of carbon
atoms.
Examples are C8,10-alkanols, C10112-alkanols, C13,15-alkanols, C12,15-
alkanols. Mixtures of
a plurality of alkanols are also possible.
The above alkanol alkoxylates or mixtures according to the invention are
preferably
prepared by reacting alcohols of the general formula R1-OH or R3-OH or
mixtures of
PF 71188 CA 02806936 2013-01-29
10
corresponding branched and unbranched alcohols optionally firstly with C3_6-
alkylene
oxide, then with ethylene oxide and subsequently optionally with C3_4-alkylene
oxide
and then with an appropriate C5_6-alkylene oxide. The alkoxylations are
preferably
carried out in the presence of alkoxylation catalysts. In particular, basic
catalysts such
as potassium hydroxide are used here. The random distribution of the amounts
of the
alkylene oxides incorporated can be greatly restricted by means of specific
alkoxylation
catalysts such as modified bentonites or hydrotalcites as are described, for
example, in
WO 95/04024, so that "narrow-range" alkoxylates are obtained.
In a particular embodiment of the present invention, the alkoxylates are
alkoxylate
mixtures comprising alkoxylates of the general formula (NIII)
C5H1 1CH(C3H7)CH20(B)p(A)n(B)m(A)qH (NIII)
where
A is ethyleneoxy,
the radicals B are each, independently of one another, C3_10-alkyleneoxy,
preferably
propyleneoxy, butyleneoxy, pentyleneoxy or mixtures thereof,
where groups A and B are present in the form of blocks in the order indicated,
is from 0 to 10,
is from > 0 to 20,
is from > 0 to 20,
q is from > 0 to 10,
p+n+m+q is at least 1,
where
from 70 to 99% by weight of alkoxylates Al in which C5Fi11 is n-051-111 and
from 1 to 30% by weight of alkoxylates A2 in which C5H11 is C2H5CH(CH3)CH2
and/or
CH3CH(CH3)CH2CH2,
PF 71188 CA 02806936 2013-01-29
11
are present in the mixture.
In the general formula (N111), p is from 0 to 10, preferably from 0 to 5, in
particular from
0 to 3. If blocks (B)p are present, p is preferably from 0.1 to 10,
particularly preferably
from 0.5 to 5, in particular from 1 to 3.
In the general formula (N111), n is preferably in the range from 0.25 to 10,
in particular
from 0.5 to 7, and m is preferably in the range from 2 to 10, in particular
from 3 to 6. B
is preferably propyleneoxy and/or butyleneoxy, especially propyleneoxy in both
positions.
q is preferably in the range from 1 to 5, particularly preferably in the range
from 2 to 3.
The sum p+n+m+q is at least 1, preferably from 3 to 25, particularly
preferably from
5 to 15, in particular from 7 to 13.
Preference is given to 3 or 4 alkylene oxide blocks being present in the
alkoxylates. In
one embodiment, firstly ethyleneoxy units, then propylene oxide units and then
ethyleneoxy units are adjoined to the alcohol radical. In a further
embodiment, firstly
propyleneoxy units, then ethyleneoxy units, then propyleneoxy units and
finally
ethyleneoxy units are adjoined to the alcohol radical. It is also possible for
the other
alkyleneoxy units indicated to be present in place of the propyleneoxy units.
p, n, m and q are each a value averaged over the alkoxylates. For this reason,
p, n, m,
q can also have nonintegral values. The alkoxylation of alkanols generally
gives a
distribution of the degree of alkoxylation which can to a certain extent be
set by use of
different alkoxylation catalysts. The choice of appropriate amounts of the
groups A and
B enables the property spectrum of the alkoxylate mixtures according to the
invention
to be matched to practical requirements.
The alkoxylate mixtures are obtained by alkoxylation of the parent alcohols
C51111CH(C3H7)CH2OH. The starting alcohols can be mixed from the individual
components so to as give the ratio according to the invention. They can be
prepared by
aldol condensation of valeraldehyde and subsequent hydrogenation. The
preparation
of valeraldehyde and the corresponding isomers is carried out by
hydroformylation of
butene, as described, for example, in US 4,287,370; Beilstein E IV 1, 32 68,
Ullmanns
Encyclopedia of Industrial Chemistry, 5th Edition, Volume Al, pages 323 and
328 if.
The subsequent aldol condensation is described, for example, in US 5,434,313
and
Rompp, Chemie Lexikon, 9th Edition, keyword "Aldol-Addition", page 91. The
PF 71188 CA 02806936 2013-01-29
12
hydrogenation of the aldol condensation product follows general hydrogenation
conditions.
Furthermore, 2-propylheptanol can be prepared by condensation of 1-pentanol
(as
mixture of the corresponding 1-rnethylbutanols) in the presence of KOH at
elevated
temperatures, see, for example, Marcel Guerbet, C.R. Acad Sci Paris 128, 511,
1002
(1899). Reference may also be made to ROmpp, Chemie Lexikon, 9th Edition,
Georg
Thieme Verlag Stuttgart, and the references cited therein and also
Tetrahedron, Vol.
23, pages 1723 to 1733.
In the general formula (NIII), the radical C5H11 can be n-05H11,
C2H5CH(CH3)CH2 or
CH3CH(CH3)CH2CH2. The alkoxylates are mixtures in which
- from 70 to 99% by weight, preferably from 85 to 96% by weight, of
alkoxylates Al
in which C5H11 is n-05H11 are present and
- from 1 to 30% by weight, preferably from 4 to 15% by weight, of alkoxylates
A2 in
which C51-111 is C2H5CH(CH3)CH2 and/or CH3CH(CH3)CH2CH2 are present.
The radical C3H7 is preferably n-C3H7.
The alkoxylates can also be block isotridecanol alkoxylates of the general
formula (NV)
where R-0-(CmH2m0)x-(Cnhl2n0)y-H (NV)
is an isotridecyl radical,
is 2 and at the same time n is 3 or 4 or
is 3 or 4 and at the same time n is 2 and
x and y are, independently of one another, from 1 to 20,
where in the case of m = 2/n = 3 or 4, the variable x is greater than or equal
to y.
These block isotridecanol alkoxylates are described, for example, in DE 196 21
843
Al.
Another suitable class of nonionic surfactants are end-capped alcohol
alkoxylates, in
particular of alcohol alkoxylates mentioned above. In a particular embodiment,
the end-
capped alcohol alkoxylates are the end-capped alcohol alkoxylates
corresponding to
the alcohol alkoxylates of the general formulae (NI), (NII), (NIII) and (NV).
The end cap
can be produced, for example, by means of dialkyl sulfate, C1.10-alkyl
halides,
C1_10-phenyl halides, preferably chlorides, bromides, particularly preferably
cyclohexyl
chloride, cyclohexyl bromide, phenyl chloride or phenyl bromide.
e- , , PF 71188
CA 02806936 2013-01-2913
Examples of end-capped alkoxylates are also described in DE-A 37 26 121, the
entire
relevant disclosure of which is incorporated by reference into the present
invention. In a
preferred embodiment, these alcohol alkoxylates have the general structure
(NVI),
RI-0-(CH2-CHR11-0)rn,(CH2-CHRIII0),RIv (NVI)
where
R' is hydrogen or C1-C20-alkyl,
RI' and RIII are identical or different and are each,
independently of one another,
hydrogen, methyl or ethyl,
RIv is C1-C10-alkyl, preferably C1-C4-alkyl, or
cyclohexyl or phenyl,
m' and n' are identical or different and are each greater
than or equal to 0,
with the proviso that the sum of m' and n' is from 3 to 300.
Another class of nonionic wetting agents are alkyl polyglucosides which
preferably
have from 6 to 22, particularly preferably from 10 to 18, carbon atoms in the
alkyl chain.
These compounds generally comprise from 1 to 20, preferably from 1.1 to 5,
glucoside
units.
Further possible nonionic wetting agents are the end-capped fatty acid amide
alkoxylates of the general formula
RI-CO-NH- (CH2)y-0- (A10)-R2
known from WO-A 95/11225, where
RI is a C5-C21-alkyl or alkenyl radical,
R2 is a CI-C4-alkyl group,
A' is C2-C4-alkylene,
y is 2 or 3 and
x is from 1 to 6.
Examples of such compounds are the reaction products of n-butyl triglycolamine
of the
formula H2N-(CH2-CH2-0)3-C4H9 with methyl dodecanoate or the reaction products
of
ethyl tetraglycolamine of the formula H2N-(CH2-CH2-0)4-C2H5 with a commercial
mixture of saturated C8-C18 methyl fatty acid esters.
w.= PF 71188 CA 02806936 2013-01-29
14
Further suitable nonionic wetting agents are polyhydroxy or polyalkoxy fatty
acid
derivatives such as polyhydroxy fatty acid amides, N-alkoxy or N-aryloxy
polyhydroxy
fatty acid amides, fatty acid amide ethoxylates, in particular end-capped
fatty acid
amide ethoxylates, and also fatty acid alkanolamide alkoxylates.
Further suitable nonionic wetting agents are block copolymers of ethylene
oxide,
propylene oxide and/or butylene oxide (Pluronic and Tetronic grades from
BASF SE
and BASF Corp.). In a preferred embodiment, these copolymers are triblock
copolymers having polyethylene/polypropylene/polyethylene blocks and a
molecular
weight of from 4000 to 16 000, with the proportion by weight of the
polyethylene blocks
being from 55 to 90%, based on the triblock copolymer. Particular preference
is given
to triblock copolymers having a molecular weight of more than 8000 and a
polyethylene
content of from 60 to 85% by weight, based on the triblock copolymer. These
preferred
triblock copolymers are, in particular, commercially available under the trade
names
Pluronic F127, Pluronic F108 and Pluronic F98, in each case from BASF Corp.,
and
are described in WO 01/47472 A2, the entire relevant disclosure of which is
incorporated by reference into the present invention.
In addition, preference is also given to using block copolymers of ethylene
oxide,
propylene oxide and/or butylene oxide capped at one or both ends. Capping at
one end
is achieved, for example, by using an alcohol, in particular a C1_22-alkyl
alcohol, for
example methanol, as starting compound for the reaction with an alkylene
oxide. In
addition, two-ended end capping, for example, can be produced by reacting the
free
block copolymer with dialkyl sulfate, C1_10-alkyl halides, C1_10-phenyl
halides, preferably
chlorides, bromides, particularly preferably cyclohexyl chloride, cyclohexyl
bromide,
phenyl chloride or phenyl bromide.
Individual nonionic wetting agents or a combination of different nonionic
surfactants
can also be used. It is possible to use nonionic wetting agents from only one
class, in
particular only alkoxylated C4-C22-alcohols. However, as an alternative,
wetting agent
mixtures from various classes can also be used.
The concentration of nonionic wetting agent in the composition according to
the
invention can vary as a function of the leaching conditions, in particular as
a function of
the material to be leached.
Suitable anionic wetting agents are alkanesulfonates such as C5-C24-,
preferably C10-
C18-alkanesulfonates, and also soaps such as the Na and K salts of saturated
and/or
unsaturated C8_C24-carboxylic acids.
PF 71188 CA 02806936 2013-01-29
4. . 15
Further suitable anionic wetting agents are linear C8-C20-
alkylbenzenesulfonates
("LAS"), preferably linear C9-C13-alkylbenzenesulfonates and -
alkyltoluenesulfonates.
Thickeners
Thickeners are compounds which increase the viscosity of the chemical
composition.
Nonlimiting examples are given, for example, in WO 2009/090169 Al:
polyacrylates
and hydrophobically modified polyacrylates. The advantage of the use of
thickeners is
that liquids having a relatively high viscosity have a higher residence time
on inclined or
vertical surfaces than liquid having a lower viscosity. This increases the
interaction time
between composition and surface.
Further particularly preferred thickeners are, for example, bentonite, xanthan
and
cellulose and also cellulose derivatives, in particular cellulose ethers and
cellulose
esters, in particular methylcellulose, hydroxyethylcellulose and
carboxymethylcellulose.
Further examples of thickeners are polyacrylamides, polyethers or associative
polyurethane thickeners, polyvinyl alcohols and polyvinylpyrrolidones.
Dispersants/scale inhibitors
Furthermore, it is possible, according to the invention, to make additional
use of at least
one dispersant, for example selected from the group consisting of salts of
naphthalenesulfonic acids, condensation products of naphthalenesulfonic acids
and
formaldehyde and also polycarboxylates. Dispersants of this type are
commercially
available, for example, under the trade names Tamol , Sokalan and Nekal from
BASF SE and under the trade name Solsperse from Lubrizol. These dispersants
may
also act as scale inhibitors (deposit preventers) since they disperse the
calcium
carbonate CaCO3 formed in alkaline medium and thus prevent, for example,
blockage
of nozzles or formation of deposits in pipes. Independently of this, the
composition
according to the invention can additionally comprise at least one further
scale inhibitor.
Suitable scale inhibitors are described, for example, in WO 04/099092, which
describes
(meth)acrylic acid copolymers which comprise
(a) from 50 to 80% by weight, preferably from 50 to 75% by weight,
particularly
preferably from 55 to 70% by weight, of a poly(meth)acrylic acid skeleton,
(b) from 1 to 40% by weight, preferably from 5 to 20% by weight, particularly
preferably from 7 to 15% by weight, of at least one unit which is selected
from the
group consisting of isobutene units, terelactone units and isopropanol units
and is
bound to the skeleton and/or incorporated into the skeleton and
* PF 71188 CA 02806936 2013-01-29
16
(c) from 5 to 50% by weight, preferably from 5 to 40% by weight, particularly
preferably from 10 to 30% by weight, of amide units based on
aminoalkylsulfonic
acids,
where the total weight of the units in the (meth)acrylic acid copolymer is
100% by
weight and all percentages by weight are based on the (meth)acrylic acid
copolymer.
The (meth)acrylic acid copolymers provided according to WO 04/099092
preferably
have a weight average molecular weight of the polymer comprising sulfone
groups of
from 1000 to 20 000 g/mol and can preferably be prepared by means of the
following
process steps:
(1) free-radical polymerization of (meth)acrylic acid in the presence of
isopropanol and optionally water, resulting in a polymer I, and
(2) amidation of the polymer I from process step (1) by reaction with at least
one aminoalkanesulfonic acid.
Further suitable scale inhibitors are, for example:
- semiamides of polycarboxylic acids, which can be obtained by reaction of
polymers comprising anhydride groups with compounds comprising amino
groups (as described in DE 195 48 318),
- vinyllactic acid and/or isopropenyllactic acid (as described in DE 197 195
16),
- homopolynners of acrylic acid (as described in US-A-3 756 257),
- copolymers of acrylic acid and/or (meth)acrylic acid and vinyllactic acid
and/or
isopropenyllactic acid,
- copolymers of styrene and vinyllactic acid,
- copolymers of maleic acid and acrylic acid,
- water-soluble or water-dispersible graft polymers, which can be obtained by
free-radically initiated graft polymerization of
(I) at least one monoethylenically unsaturated monomer,
(II) polymers having a molar mass of from 200 to 5000 g/mol of
monoethylenically unsaturated dicarboxylic acids or anhydrides thereof,
(Ill) where from 5 to 20 000 parts by weight of (I) are used per 100 parts by
weight of the graft base (II) (DE 195 03 546),
- optionally hydrolyzed polynnaleic anhydrides and salts thereof (as described
in
US-A-3 810 834, GB-A-1 454 657 and EP-A-0 261 589),
- iminodisuccinates (as described in DE 101 02 209),
- formulations comprising complexing agents such as ethylenediaminetetraacetic
acid (EDTA) and/or diethylenetriaminepentaacetic acid (DTPA) (as described in
US 5,366,016),
PF 71188 CA 02806936 2013-01-29
17
- phosphonates,
- polyacrylates,
- polyaspartic acids or polyaspartic acids which have been modified as
described
in DE-A-44 34463,
- polyaspartimides,
- polymers comprising hydroxamic acid, hydroxamic ether and/or hydrazide
groups (as described in DE 44 27 630),
- optionally hydrolyzed polymers of maleimide (as described in DE 43 42 930),
- naphthylamine polycarboxylates (as described in EP 0 538 969),
- oxaalkanepolyphosphonic acids (as described in EP 330 075),
- polyhydroxyalkaneaminobismethylenephosphonic acids (as described in DE 40
16753) and
- oxidized polyglucosanes (as described in DE 43 30 339).
Particularly preferred dispersants are polyacrylic acid, for example the
Sokalan grades
from BASF SE, and polyaspartic acids, in particular 13-polyaspartic acids,
having a
molecular weight of from 2000 to 10 000 g/mol. Preferred polymeric compounds
comprising carboxylic acid groups are the acrylic acid homopolymers indicated
in
EP 2 083 067 Al. These preferably have a number average molecular weight in
the
range from 1000 to 50 000, particularly preferably from 1500 to 20 000.
Homopolymers
of acrylic acid which are particularly suitable as polymeric compounds
comprising
carboxylic acid groups are the Sokalan PA grades from BASF SE.
Further suitable polymeric compounds comprising carboxylic acid groups are
oligomaleic acids as are described, for example, in EP-A 451 508 and EP-A 396
303.
Other compounds which are preferred as polymeric compounds comprising
carboxylic
acid groups are copolymers comprising at least one unsaturated monocarboxylic
or
dicarboxylic acid or a dicarboxylic anhydride or a salt thereof as monomer A)
and at
least one comonomer B) in copolymerized form. The monomer A) is preferably
selected from among C3-C10-monocarboxylic acids, salts of C3-C10-
monocarboxylic
acids, C4-C8-dicarboxylic acids, anhydrides of C4-C8-dicarboxylic acids, salts
of
C4-C8-dicarboxylic acids and mixtures thereof. Monomers A) in salt form are
preferably
used in the form of their water-soluble salts, in particular the alkali metal
salts such as
potassium and especially sodium salts or the ammonium salts. The monomers A)
can
in each case be entirely or partly present in anhydride form. Of course, it is
also
possible to use mixtures of monomers A).
The monomers (A) are preferably selected from among acrylic acid, methacrylic
acid,
crotonic acid, vinylacetic acid, maleic acid, maleic anhydride, fumaric acid,
citraconic
PF 71188 CA 02806936 2013-01-29
18
acid, citraconic anhydride, itaconic acid and mixtures thereof. Particularly
preferred
monomers A) are acrylic acid, methacrylic acid, maleic acid, maleic anhydride
and
mixtures thereof. These copolymers preferably comprise at least one monomer A)
in an
amount of from 5 to 95% by weight, particularly preferably from 20 to 80% by
weight, in
particular from 30 to 70% by weight, based on the total weight of the monomers
used
for the polymerization, in copolymerized form.
Corrosion inhibitors
The agents, e.g. carboxylic acids, indicated in, for example, WO 2008/071582
Al act
as corrosion inhibitors. These can be linear or branched. Mixtures of various
carboxylic
acids can be particularly preferred. Caprylic acid, ethylhexanoic acid,
isononanoic acid
and isodecanoic acid are particularly preferred carboxylic acids. Since
corrosion
protection emulsions are frequently neutral to weakly alkaline, it can be
advantageous
to use the carboxylic acids at least partly in neutralized form, i.e. as salt.
Sodium
hydroxide and/or potassium hydroxide and also alkanolamines are particularly
suitable
for neutralization. Particular preference is given to using monoalkanolamines
and/or
trialkanolamines. The use of dialkanolamines is less preferred because of the
risk of
formation of nitrosamines. Dialkanolamines can be used equally well either
alone or
together with monoalkanolamines and/or trialkanolamines for neutralization.
Suitable corrosion inhibitors are, in particular:
Aliphatic carboxamides having from 14 to 36 carbon atoms, for example
myristamide,
palmitamide and oleamide; alkenylsuccinamides having from 6 to 36 carbon
atoms, for
example octenylsuccinamide, dodecenylsuccinamide; mercatobenzothiazoles.
Particularly preferred corrosion inhibitors are alkylene oxide adducts with
aliphatic
amines, in particular triethanolamines and ethylenediamine adducts with from 2
to
8 mol% of propylene oxide.
Complexing agents
Complexing agents are compounds which bind cations. Typical examples are: EDTA
(N,N,N',N'-ethylenediaminetetraacetic acid), NTA (N,N,N-nitrilotriacetic
acid), MGDA
(2-methylglycine-N,N-diacetic acid), GLDA (glutamic acid diacetate), ASDA
(aspartic
acid diacetate), IDS (iminodisuccinate), HEIDA (hydroxyethylimine diacetate),
EDDS
PF 71188 CA 02806936 2013-01-29
19
(ethylenediamine disuccinate), citric acid, oxodisuccinic acid and
butanetetracarboxylic
acid and completely or partially neutralized alkali metal or ammonium salts
thereof.
Other Additives
Further suitable additives are, for example, bonding agents. Suitable bonding
agents
are, for example, the amphiphilic water-soluble alkoxylated polyalkyleneimines
of the
general formula Al indicated in WO 2006/018856 A2
[E2N Ri [ N¨R][ N z 2 Al
where the variables have the following meanings:
the radicals R are identical or different, linear or branched C2-C6-alkylene
radicals;
B is a branch;
E is an alkyleneoxy unit of the formula
Ri m( R2 0 ) ( R3 0 ) R4
whereR1 is 1,2-propylene, 1,2-butylene and/or 1,2-isobutylene;
R2 is ethylene;
R3 is 1,2-propylene;
R4 are identical or different radicals: hydrogen; C1-C4-alkyl;
x, y, z are each from 2 to 150, where the sum x+y+z is the number of
alkyleneimine units and corresponds to an average molecular weight Mw of the
polyalkyleneimine before the alkoxylation of from 300 to 10 000;
m is a rational number from 0 to 2;
n is a rational number from 6 to 18;
p is a rational number from 3 to 12, where 0.8 n/p 1.0 (x+y+z)1/2.
The invention further provides a slurry composed of the carrier fluid, in
particular cutting
fluid, abrasives, in particular grinding and/or cutting grains, and optionally
additives.
It is possible to use the customary abrasives, in particular grinding and/or
cutting
grains, for example metal, metal or semimetal, carbide, nitride, oxide, boride
or
PF 71188 CA 02806936 2013-01-29
20
diamond grains. Particularly preferred cutting grains are carbide and boride
grains, in
particular silicon carbide (SiC) grains. The cutting grains preferably have a
geometry
matched to the materials and the wafers to be cut. A preferred particle size
is in the
range from 0.5 to 50 pm. The cutting grains can be present in heterodisperse
or
homodisperse form. The cutting grains are preferably comprised in the cutting
fluid
composition in a concentration of from 25 to 60% by weight, in particular from
40 to
50% by weight.
In a particularly preferred embodiment, the carrier fluid, in particular
cutting fluid, has a
contact angle to V2A steel of from 5 to 40 , in particular from 10 to 30 . The
contact
angle is determined here at 25 C on a steel plate made of V2A steel whose
surface
has been rinsed with water and acetone.
In a further preferred embodiment, the carrier fluids, in particular cutting
fluids, of the
invention lead to an average weight decrease over two tests of not more than
20-60 mg
in one minute on a stainless steel cylinder M1M6/05R, Torrington, having a
diameter of
12 mm on a MDD2 balance from Hermann Reichert Maschinenbau, Heidenhof
Backnang, at a loading of 300 N and over a distance of 110 m.
In a further preferred embodiment, the carrier fluids, in particular cutting
fluids, of the
invention take up not more than 30%, preferably not more than 15%, of water
after
storage for 10 hours in a Heraeus BBD 6220 CO2 incubator at 38 C and 78%
relative
atmospheric humidity. For the storage test, 1 g of carrier fluid, in
particular cutting fluid,
in Petri dishes having an internal diameter of 60 mm is used in each case. The
average
of a duplicate determination is determined in each case. In a very
particularly preferred
embodiment, this water uptake does not increase even on further exposure.
A slurry composed of a carrier fluid, in particular cutting fluid, according
to the invention
and 40% by weight of the abrasives indicated below, in particular grinding
and/or
cutting grains, preferably has a viscosity measured at 30 C using a Brookfield
LVDV-Ill
Ultra apparatus (spindle V-73) of from 140 to 200 mPas, in particular from 150
to
190 mPas, when Carborex BWF 800 PV silicon carbide grains from Washington
Mills
are used.
The invention further relates a method of cutting wafers of, in particular,
inorganic
semiconductors such as silicon ingots or silicon blocks by means of a wire saw
using a
slurry based on the cutting fluid of the invention and cutting grains.
The invention further relates to a method of grinding or polishing materials
derived
from, for example, silicon ingots or blocks by, for example, chemomechanical
polishing
PF 71188 CA 02806936 2013-01-29
21
(CMP) or of grinding polymers, in particular for lenses, using abrasives
dispersed in a
carrier fluid to be used according to the invention.
Advantages
The carrier fluid, in particular cutting fluid, of the invention and the
cutting method of the
invention are particularly suitable for sawing ingots, blocks or cylinders of
monocrystalline or polycrystalline silicon single crystals or polycrystals,
GaAs, CdTe
and other semiconductors and ceramics.
The carrier fluid, in particular cutting fluid, of the invention displays
little or no foaming,
does not require any additives, is pH neutral and is nontoxic. In addition, it
does not
contain any volatile organic constituents. Furthermore, the carrier fluid, in
particular
cutting fluid, of the invention is highly suitable for reprocessing by means
of a wet
chemical work-up, for example as described in WO 02/40407 Al and EP 1 390 184
Al.
Examples:
General method of preparing polyethers
1-2 mol of the starter alcohol were in each case placed in a water-free, dry 1
I pressure
reactor, admixed with 0.2% by weight (based on end product) of KOH and flushed
with
nitrogen. The closed reactor was then heated to 130 C over a period of 30
minutes and
a gauge pressure of 1 bar was set by means of nitrogen. The molar amounts of
propylene oxide (hereinafter PO) and ethylene oxide (hereinafter E0) indicated
in table
1 were subsequently metered in in parallel (random process) or in succession
(block
process) while stirring. In the block process, after PO had been added and a
constant
pressure had been reached, the mixture was stirred at 130 C for at least 1/2
hour and
the pressure was set to 1 bar before the addition of E0. The vessel was
thermostated
to 130 C during the reaction. After a constant pressure had been reached, the
mixture
was stirred for a further about % hour. After the reaction was complete, the
mix was
cooled to 80 C, the reactor was depressurized and flushed with nitrogen, the
amount of
glacial acetic acid calculated for neutralization of the KOH was added and the
mixture
was stirred for 1/2 hour.
The OH number was determined in accordance with DIN 51562, the residual
alcohol
content was determined by means of gas chromatography and the APHA color
number
was determined in accordance with EN 1557 (at 23 C).
PF 71188 CA 02806936 2013-01-29
22
Table 1: Examples and analytical characterization
Product Chemical composition OH Residual Color
(PO here is propyleneoxy, number alcohol number
EO here is ethyleneoxy)
Pluriol E 200 polyethylene glycol 200 560 DEC max30
3
Cl (3-methylbutan-1-ol) + 1.6 PO + 98.3 0.2 70
8.3 EO
block process
C2 (3-methylbutan-1-ol) + 5.5 PO + 5.5 87.0 <0.1 25
EO
random process
C3 (3-Methylbutan-1-ol) + 6.0 PO + 5.0 85.7 <0.1 20
EO
random process
C4 n-butan-1-ol + 5.5 PO + 5.5 EO 90.4 <0.1 30
random process
C5 methyl diglycol + 8.8 E0/ 106.6/ 0.2/<0.1 60/50
(3-methylbutan-1-ol) + 1.5 PO + 7.0 112.4
EO
in a weight ratio of 6/4
block process
C6 Pluronic0 PE 6200/ 112.4 0.1 30
n-pentanol +1.5 PO + 6 E0
in a weight ratio of 18/82
block process
C7 Plurafac0 LF 401/ 126.2 0.1 25
n-pentanol + 1.5 PO + 6 EO
in a weight ratio of 3/7
block process
C8 n-hexanol + 5.5 PO + 5.5 EO 84.0 <0.1 20
random process
11.1 2-methylbutan-1-ol + 5.5 PO + 5.5 85.2 <0.1 20
EO
random process
11.2 2-methylbutan-1-ol + 6.0 PO + 5.0 86.1 <0.1 15
E0
PF 71188 CA 02806936 2013-01-29
23
Product Chemical composition OH Residual Color
(PO here is propyleneoxy, number alcohol number
EO here is ethyleneoxy)
random process
The wetting agents and alkylene glycols Pluronic0 PE 6200 and Plurafac0 LF 401
added in examples C6 and C7 are commercial products of BASF SE, Ludwigshafen.
The analytical data reported are based on the component pentanol + 1.5 PO + 6
EO
according to the invention, block process.
Properties/determination of the characteristic values
The properties of the cutting fluids according to the invention are summarized
in table
2. The following properties were determined:
= Water uptake
The water uptake of the cutting fluids was determined after storage in a
Heraeus BBD
6220 CO2 incubator at 38 C and 78% relative atmospheric humidity for a time of
10
hours and 24 hours. For storage, 1 g in each case of cutting fluid was used in
Petri
dishes having an internal diameter of 60 mm. The average of a duplicate
determination
was determined in each case. The water uptake is in each case reported in
percent by
weight increase based on the initial weight.
= Slurry viscosity
To determine the slurry viscosity, a mixture of 60 percent by weight of the
sawing fluid
and 40 percent by weight of SiC of the type Carborex BW F 800 PV from
Washington
Mills was produced and the viscosity was determined at 30 C and optionally 50
C
using a model LVDV-III Ultra viscosimeter from Brookfield (Spindle V-73). The
slurry
viscosity is reported in nnPas.
= Contact angle
The contact angle of the cutting fluids was determined at 25 C one second
after
application of a droplet to a steel plate made of V2A steel whose surface had
been
rinsed with water and acetone and subsequently dried in air for 1 hour. A
video-aided
high-speed contact angle measuring instrument from Dataphysics Instruments
GmbH,
Raiffeisenstrafle 34, Filderstadt was used for the determination. The unit of
the contact
angle is .
0 PF 71188 CA 02806936 2013-01-29
24
= Abrasion
The abrasion behavior was determined on a frictional wear balance MDD2 from
Hermann Reichert Maschinenbau, Heidenhof Backnang, at a loading of 300 N and a
test distance of 100 m in 54.5 sec. on a stainless steel cylinder M1M6/05R,
Torrington
having a diameter of 12 mm. A duplicate determination was carried out in each
case
and the average of the weight decrease of the cylinder was determined. The
weight
decrease is reported in mg.
Table 2
Product H20 uptake 10h Viscosity [mPas] Contact angle Abrasion
(24h) [A] 30 C (50 C) [Ol [mg]
Plurio10 E 200 203 (94) 41 70
Cl 17.2 (18.2) 181 (85) 30 25
C2 5.7 ( 5.9) 160 (89) 23 32
C3 5.3 ( 5.3) 185 (161) 21 22
04 6.6 ( 6.6) 155 (93) 23 28
C5 16.3 (24.3) 164 (77) 29 35
C6 5.5 ( 8.3) 175 (84) 28 29
C7 6.3 (8.2) 167 (84) 36 33
C8 5.3 (5.3) 198 (176) 34 38
Plurio10 E 200 is a polyethylene glycol having an average molar mass of 200
from
BASF SE, Ludwigshafen. The example represents the prior art and is not
according to
the invention. The compounds 11.1 and 11.2 gave results comparable to the
compounds
02 and 03.
Practical test
Sawing tests on polycrystalline silicon blocks were carried out on a DS 265
wire saw
from Meyer Burger AG, Allmendstrasse 86, CH 3600 Thun using the sawing fluids
Cl
and 03. The test conditions were:
Dimensions of the wafers: 5" x 5", 150 pm
SiC grade: F 88, ds50 = 6.5 pm
Advance rate: 0.6 mm/s
Wire speed: 14 m/s
Wire diameter: 120 pm
PF 71188 CA 02806936 2013-01-29
25
Wire tension: 20 N
Slurry temperature: 22 C
Composition of the slurry: 60% by weight of sawing fluid, 40% by weight of SiC
Compared to the PEG 200 (Pluriol E 200) which is usually used in industrial
practice,
the following improvements were found for the cutting fluids according to the
invention:
Pluriol E 200 Cl C3
Water uptake, [% by weight] 3 <0.5 <0.5
Force per wire in advance direction, [N] 0.62 0.57 0.58
Force per wire in wire direction, [N] 1.62 1.51 1.55
Power uptake per wire, [W] 29.5 24.0 26.5
(without machine contribution)
TTV, 5¨point support, [%1 12.5 11.8 10.5
(total thickness variation of wafers)
Critical fracture stress, [Nimm2] 158 163 178
Similar improvements were also found when using the other products according
to the
invention shown in table 1.
