Note: Descriptions are shown in the official language in which they were submitted.
- ~3~ 2~
- -- B~ackqround of the Invention
This invention relates to electrical circuit
interconnections, and more particularly to connector
arrangements of the type useful with electronic circuit
components of the semiconductor type.
Integrated circuitry developments require
circuit interconnection configurations of greater
density, as well as circuit path configurations that
control impedance and resistive effQcts which may alter
circuit performance. Conventionally employed methods of
interconnecting electrical or electronic circuit
components have included the "pin-and~socket" type and
the so-called "zero force insertion" type in which a
circuit card may be inserted when cooperating contacts
are in an open position, and the contacts are then
cammed to a closed position. These and other techniques
have reguired substantial space or generally have a
tendency to utilize complex arrangements and complicated
manufacturing procedures. Additionally, certain types
of commercially employed connectors cannot be easily
matched in impedance to the circuit cards being
connected, thus causing reflections which degrade signal
quality. Such problems are particularly acute when
connectors are used with newer generation semiconductors
which have high switching speeds (100 - 500 picosecond~
rise time), low switching enQrgy and signal swings in
the microvolts range, the resulting disadvantages
including poor signal ~uality caused by high crosstalk,
rise time degradation, and refiections due to impedance
mismatch.
:~3(36~
Sumn~ary of the nvention
In accordance with one aspect of the invention,
there is provided a high fre~lency electrical connector
system for electrically interconnecting a first circuit
element with a second circuit element. The system
includes a first planar array of pad-type contact
terminals that are disposed OIl a nonconductive substrate
and connected to a first circuit on the substra~e,
together with first guide structure adjacent the first
contact terminal array. A cooperating second array of
pad-type contact terminals is mounted on a rigid
nonconductive contact support structura that includes
camming structure, a resilient contact array mounting,
and second guide structure for cooperation with the
first guide structure. The contact support structure is
resiliently coupled to a carrier structure that includes
cooperating camming structure opposed to the camming
structure of the contact support structure. Flexible
multi-conductor interconnection structure has one end of
2Q the conductors electrically connected to a cooperating
electrical circuit secured to the carrier structure and
the other end of the cond~lctors connected to
corresponding pad-type contact terminals of the second
array. Fastener structure is adapted to secure the
carrier structura and the substrate together with the
first and second guide structures in engagement. With
the arrays of planar pad-type contact terminals in
face-to-facQ engagement, as the fastener structure moves
the carrier structure towards the substrate, the camming
structures interact and move the contact support
structure laterally (parallel to the plane of the
contact arrays) in transverse wiping action as
directional].y quided by the engaged first and second
guide struct:ures to remove debris or other foreign
~L3~6~2~
-- 3 --
matter (such as corrosive ilms) which may adversely
affect electrical circuit performance.
In preferred embodiments, the flexible
interconnection structure includes a plurality of
conductor traces and a ground plane, and each conductor
trace has the same characteristic impedence as other
conductor traces, the clamping and wiping interactions
providing circuit interconnections of minimal resistance
and impedance reflectio~. In ,a particular embodiment,
the pad-type contacts at one end of the flexible
interconnection structure have spacing different from
tha spacing on center of the terminals at the other
end.
Also in preferred embodiments, the second array
of pad-type contacts lies in a plane and the camming
structures of the carrier and contact support structures
are planar surfaces that are disposed at an acute angle
to the plane of the array of pad-type contacts; and the
first guide structure includes an upstanding post member
that is received in a guide slot between ~wo spaced
projecting members of the contact support when the
pad-type contact arrays are in face-to-face engagement.
In a particular module-to-board connector
embodiment, the carrier structure supports a module with
a plurality of chip carriers and includes four planar
ramp surfaces disposed in rectangular arrangement, and a
corresponding contact support structure is mountad on
each ramp surface. Each ramp surface has an elongated
slot therein and thQ resilient coupling between the
support structure and the carrier structure includes a
post structure that extends through the ramp slot and is
engaged by a spring member that biases the camming
structures of the support and carrier structures into
engagement wi.th one another. The resilient contact
~3~ Z~
.~
array mountinq includes a foam elastomer strip that
?referably has low stress relaxation when compressed
five to fifty percent of its thickness and provides
conormability and controlled contact force.
In accordance with another aspect of the
invention, there is provided an electrical connectox
arrangement of the solderless type in which first and
second planar ~rrays of pad-ty~e contact terminals are
adapted for face to face enqagement. Means are provided
for ~.oving one of the arrays of contact terminals
rslative to the other contact terminal array in contact
wiping action for cemoving surface contamination.
In accordance with anothec aspect of the
invention, there is provided an electrical connector
assembly for connecting a first array of electrical
contacc terminals supported on a rigid member having a
generally planar face witn a corresponding second array
of electrical contact terminals carried by a flexible
circuit. The connector assembly includes a support
structure having a face opposed to the planar face of
the rigid member and mounted to press the flexible
circuit mounted array of contact terminals toward the
rigid member and move that array laterally, parallel to
the face o the rigid member to pro~ide wiping between
the engaged arrays of contact terminals. The connector
assembly further includes ca~ming means supported for
actuating movement in the direction perpendicular to the
face of the rigid member, and movable to produce lateral
mo~ion of the support structure in response to
perpendicular actuating motion of the camming means.
In particular embodiments, the support
structure is of a form generally correspondinq to the
outline of the first array, and the camming means is of
~3~
generally corresponding form and lies predominantly
within lines projected perpendicular to the face of the
rigid member board from the outline of the contact
terminal array on that face, whereby wiping engagement
of a series of close-together contacts can be achieved
by means which covers little excess area of the array of
contacts on the'rigid circuit board. In a particular
embodiment, the connector assembly includes four contact
array sets, and the support structure and camming means
are assembled upon a single rigid member in a hollow
square pattern, and a chip carrier module is disposed on
the single rigid member within the sguare pattern. The
flexible cirsuits comprise controlled characteristic
impedance strip means. The contacts in the arrays are
lS spaced apart and provide connections with high contac~
density and controlled impedance.
In accordance with another aspect of the
invention, there is provided electrical connector
structure of the solderless type for providing
electrical connections to a first array of pad-type
contact terminals on a substrate or the like. The
connector structure includes contact support structure
that carries a corresponding array of resiliently
mounted pad-type contact terminals and has a camming
surface. The contact support structure is resiliently
coupled to a carrier structure that includes camming
structure that engages the contact support structure
camming surface. Extending from the fixed array of
pad-type contact terminals of the array carried by the
contact support structure is flexible multi-conductor
interconnection structure that has electrical terminals
at its other end connected to circuits on the carrier
structure. With the pad-type contact terminal array in
face-to-face engagement, movement of the carrier
~L3~6~2~
structure toward the first planar array causes the
camming surface structure to produce lateral movemen~ of
the contact support structure and wiping action of the
enga~ed pad-type contact terminal arrays, providing low
resistance circuit interconnections.
In a particular embodiment, one or more chip
carriers are on a module that :is mounted on the carrier
structure and terminals of the module are fixed to
conductor traces of a flexible shee~-form
interconnection structure that includes a ground plane
impedance control trace and a low loss, low dielectric
constant member, each conductor trace having a
characteristic impedence matched to the impedance of the
integrated circuit. A pad-type contact terminal is at
the other end of each conductor trace, those pad-type
contact terminalc being spaced and disposed in a planar
array that is secured to a carrier bar.
The connector assembly provides a controlled
impedance connection with low crosstalk and high
propagation velocity in an environmentally reliable,
high density interconnection which is electrically
invisible even at very high frequencies.
Other features and advantages of the invention
will be seen as the following description of a
particular embodiment progresses, in conjunction with
the drawings.
Preferred Embodiments
We first briefly describe the drawings.
Fig. 1 is a plan view of a printed circuit
board with a rectangular array of terminals;
Fig. 2 is a perspective view of a
module-to-board connector assembly in accordance with
~3~
the invention for cooperation with the printed circuit
board of Fig. 1, showing a chip carrier module and
contact array;
Fig. 3 is an exploded perspective view of
components of the chip carrier module and contact array
of Fig. 2, showing a terminal support assembly;
Fig. 4 is a plan view of the carrier frame
member of Fig. 3;
Fig. 5 is a side view of the frame member of
Fig. 4;
Fig. 6 is a sectional view taken along the line
6-6 of Fig. 4;
Fig. 7 is a plan view of a contact support bar
of the terminal support assembly of Fig. 3;
Fig. 8 is a front view of the support bar of
Fig. 7;
Fig. 9 is a sectional view taken along the line
9-9 of Fig, 7;
Figs. lOA and lOB are plan views of flexible
signal conductor arrays employed in a particular
embodiment of the invention;
Fig. lOC is an enlarged diagrammatic view of
the superimposed contact arrays;
Fig. lOD is a p}an view of the contact arrays
shown in Fig. lOC; and
Figs. ll and 12 are sectional diagrammatic
views illustrating the wiping and electrical connection
actions of the connector assembly of Fig. 2.
Description of Particular_Embodiment
Figure 1 is a diaqrammatic view of a circuit
board lO having a substrate ll on which is disposed one
or more printed circuits, represented by area 12, with
an associated rectangular "footprint" in the form bf two
rows of pad-type contact terminals in a terminal array
~L306~Z~
14 (signal terminals 14A and ground terminals 148). As
is known, terminals 14 are connected to circuit(s) 12
(which may be located inside o:r outside "footprint" 14
(or both)) via plated-through holes to connector traces
on the reverse side of the substrate. At each corner of
the array of terminals is a fastener-receiving aperture
16 and two upstanding guide posts 18. Substrate 11 may
be of suitable insulating material such as polyimide
glass or epoxy glass, and an appropriate stiffening
plate 2Q may be secured on the rear side of the
substrate 11 in alignment with terminal array 14 and
alignment posts 18.
Cooperatiny with printed circuit substrate 11
and terminal array 1~ (as shown in Fig. 2) is connector
assembly 30 that includes module 32 on which circuit
elements (such as one or more chips or chip carriers,
not shown) are mounted and that has a rectangular array
of corresponding terminals (not shown) to which are
soldered flexible plural conductor (preferably
microstrip or strip line3 fifty ohm characteristic
impedance transmission line circuits 36 that fan out to
the contact density of the circuit board 10. Each
flexible circuit 36 has one or more rows of contact
pad-type terminals in terminal array 40 at its other
ends of the same size and spacinq as terminal array 14.
The four terminal arrays 40 are secured on corresponding
carrier bars 42 that are in turn resiliently secured to
carrier frame 44 by post structures 46 and spring
members 48.
Connector assembly 30 is shown in exploded view
in Fig. 3, and further details of carrier frame 44 may
be seen with reference to Figs. 4-6. Carrier frame 44
includes a transverse plate 52 with corner post
structures 54 on one side on which module 32 is
~3(~6~
secured. Upstanding from the other side o plate 52 is
a camming structure of rectan~ular configuration that
includes a set of four planar ramp surfaces 56, each of
which is disposed at an angle of 50 to the plana of
plate 52. Centrally located in and extending
perpendicularly through each ramp surface 56 is an
elongated slot 58. At each corner of the ramp structure
56 is a fastener aperture 60. A clearance recess 62 is
formed in base plate 52 in general alignment with slot
58, and a spring tip capturing recess 64 is ormed in
plate 52 on either side of each clearance recess 62.
Each carrier bar 42, as may be seen with
reference to Figs. 3 and 7-9, has a planar base surface
70 in which recess 72 is formed and receives resilent,
open-cell polyurethane foam pad 74 (which may be of the
type described in U.S. Patent 4,468,074) such that the
outer surface of pad 74 projects about one millimeter
beyond surface 70 of carrier bar 42. At each end of
recess 72 is a threaded fastener recess 76 that
cooperates with associated fastener portions 116 of
flexible transmission line circuits 36. The end
surfaces 80 of bars 42 are disposed at 45 angles to the
length of the bar so that the surfaces are aligned with
one another in the~assembly as shown in Fig. 2, and a
recess 8~ ~and corresponding recess 120 (Figs. lOA,
lOB)) is formed in each surface for clamp fastener 88.
Extending laterally from surface 70 at either end
thereof are a pair of projections 84 that define a guide
slot 86 that receives and cooperates with a
corresponding guide post 18 on substrate 11. Each
carrier bar 42 also include a ramp surface 90 that is
~3~6~3Z~
-- 10 --
disposed at an angle of 60 to surface 70, and in which
is formed a threaded recess 92 for receiving post
structure 46.
Carrier bars 42 are assembled to carrier frame
44 with coupling post structures 46 and spring members
48 such that their ramp surfac~es 90 sea~ on frame ramp
surfaces 56. Coupling post st:ructures 46 extend through
slots 5~ and are threadedly secured in recesses 92, the
central portion of each stainless steel spring ~8 is
captured on the head of its post 46 and its end portions
are seated in frame recesses 64, as indicated in Fig. 2,
so that springs 48 bias the ramp surfaces 90 of carrier
bars 42 against and along frame ramp surfaces 56 away
from plate 52. The pad-type contact terminal arrays 40
of flexible transmission line circuits 3S are secured to
carrier bars 42 by threaded fasteners 98 in threaded
fastener recesses 76.
In this connector embodiment, two superimposed
flexible transmission line circuits 36 (Figs. ll, 12)
are secured to each carrier bar 42, and provide a
transition in terminal density between chip carrier
module 32 and pad-type contact terminal arrays 40.
Details o those flexible transmission line circuits 36
may be seen with reference to Figs. lOA - D. Each
flexible circuit 36A, 36B is of "microstrip"
configuration and includes one ounce copper ground plane
100 that terminates in exposed ground terminal strips
102, 104 at opposite ends of the circuit (the ground
terminal strips 104 corresponding to contact pads 40A of
Fig. lOD), three mil thick glass reinforced fluorocarbon
(Rogers R~-2500~ dielectric 106 that has a low
dielectric constant t2-5) and a low loss factor, a set
of one ounce copper conductive circuit traces 108A, 108B
~L3a~
-- 11 --
that extend between terminals pads 110 and terminals
pads 112 and cover film, the flexible cîrcuits providing
controlled impedence high density transmission line
conductors (traces 108) between terminal strip 102 and
terminal pad 110 that are soldered to chip carrier
module 32 and terminal strip 104 and terminal pads 112
(the signal pads 112 corresponding to contact pads 4oa
of Fig. lOD). At either end of the contact pad terminal
array 40 is a fastener portion 116 that includes an
aperture 118 through which a threaded fastener 98 (Fig.
2) extends into its corresponding threaded fastener hole
76 (the fastener portions 116 being spaced about 2.5
centimeters apart).
The conductive circuit traces 108 are one ounce
(1.4 mil) copper and pads 112 are copper plated to about
two ounces (about 3 mils).
Referring, e.g., to Fig. 11 in conjunction with
Fig. 1, the outlines of the arrays of contacts 14 on the
circuit board 10 (and the corresponding arrays 40 on the
1axible circuits 36) are of elongated orm. The
carrier bars 42 are of corresponding form. The camming
structure that lies directly above each bar 42 is also
of generally corresponding form (see, e.g., Fig. 3),
lying predominantly within projection lines Pl
and P2 (Fig. 11), projected perpendicular to the face
of the circuit board 10 from the outline of the carrier
bar 42. Areas covered by the actuating mechanisms,
i.e., camming ramp surfaces 56, 90, posts 46, etc., are
substantially the same as those covered by the mating
contact arrays, i.e., 14, 40, leaving adjoining areas of
the circuit board available, e.g., for the mounting of
components. For instance, in the square of terminal
array 14 shown, e.g., in Fig. 1, a component, e.g., an
~30~;a~4
- 12 -
active elect.rical component or a cooling device, can be
mounted on the same side of the board as the contacts,
and other electrical components mounted outside of the
square of the terminal array on the same side of the
board as the contacts.
Interaction of the contact assembly 28 (Fig. 2)
with the substrate 11 is indicated diagrammatically in
Figs. 11 and 12. Contact assemoly 28 is disposed on
circuit board 10 as indicated in Fig. 12, with contact
pad array 40 seated on but inwardly offset from
cooperating substrate pad array 14. As fasteners 88 are
tightened to urgQ contact assembly 28 toward substrate
11, (in the direction of arrow 130), the ramp surfaces
56 of frame 44 slide along ramp surfaces 90 of carrier
bars 42 against the biasing forces of springs 48 and
producing a transverse outward (sliding) movement (in
the direction of arrow 132) and wiping action of
terminal pads 112 of contact pad array 40 across
substrate contact pad array 14. That wiping action
removes debris and surface contamination and, together
with resilient actions of springs 48 and pads 74,
produces durable, electrically invisible, low contact
resistance circuit interconnections with clamping forces
of about thirty psi.
The disclosed connector assembly provides
multiple electrical connections in an arrangement
resistant to mechanical and thermal shock which is
relatively inexpensive to manufacture, simple to
utilize, readily replaceable without the use of solder,
30 and provides reliab~le circuit interconnections with
distributed mating forces and wiping actions of pad-type
contacts. While particular embodiments have been shown
and described, various modifications will be apparent to
;
:~3~
- 13 -
those skilled in the art, and therefore it is not
intended that the invention be limited to the disclosed
embodiments or to details thereof, and departures may be
made therefrom within the spirit and scope of the
invention.
