Note: Descriptions are shown in the official language in which they were submitted.
1~75515
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LQW OR ZERO INSERTION FORCE CONNECTOR
FOR MULTI-PIN ARRAYS
l FIELD OF THE INVENTION-
This invention relates generally to electrical
connectors and pertains more particularly to connectors
of so-called zero or low insertion force type for use
with multi-pin arrays.
BACKGROUND OF THE INVENTION
The primary advantage in the use of zero in-
sertion force connectors, namely, minimizing loading of
interfitting contacts during connection, takes on par-
ticularly great significance as the number of contactssimultaneously made increases to levels today seen with
circuit components produced by very large scale integra-
tion (VLSI) techniques. In this sector, a VLSI device
may present a twenty-by-twenty pin array, i.e., a total
of four hundred pins, for simultaneous individual mating
with collectively supported sockets. The loading forces
attending such connection are, of course, cumulative of
the force per mating contact pair and can readily amount
to a level which may be unattainable for an assembler or
not sustainable by support housings of the respective
pins and sockets.
A further problem presented to the connector
designer by VLSI is that of readily facilitating connec-
tion and disconnection and while minimizing space in
which such insertion connection and disconnection are to
be effected. Customary practices in the art in larger
environs are not applicable. In the above example of
VLSI connection, the twenty-by-twenty pin array may be
necessary within a square of about two inches per side,
i.~., about one-tenth inch pin spacings in both column
and row directions. Further connections may envision
forty-by-forty pin arrays or more.
There are generally two types of zero insertion
force connectors, one in which the contacts are normally
1175S15
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1 closed and the other in which the contacts are normally
open. The present invention relates to a zero or low
insertion force connector having normally closed con-
tacts. There are a number of known zero insertion force
connectors of the closed-contact type which are used to
make connection to conductors on printed circuit boards
as well as to the leads of electronic packages or compo-
nents and which employ camming devices for opening such
contacts. Such connectors for printed circuit board
connections are shown, for example, in U.S. Patents
4,196,955; 4,159,861; 4,159,154; 3,553,630; 3,426,313
and 3,395,377 and in German Patent 1,118,852. Refer-
ences showing connections to a multi-pin device in a
closed contact connector include U.S. Patents 4,080,032
and 4,050,758, the latter reference also being useful
in connections to printed circuit boards.
SUMMARY OF THE INVENTION:
The primary object of the present invention is
an improved connector for the interconnection of multi-
pin arrays to corresponding contacts.
A more particular object of the present in-
vention is to provide such interconnection of the multi-
pin/contact arrays with zero or low insertion force.
In accordance with the invention, an electrical
connector has a plurality of contacts having socket ter-
minals disposed in an array corresponding to the multi-
pin array and opposite terminals for connection to com-
panion apparatus. The socket terminals are each formed
with facing elements thereof closingly biased toward one
another to electrically engage a pin to be received
therein. Each facing element is defined to provide a
partial boundary surface for the pin upon receipt there-
of. A cam is supported for movement in the connector,
such cam being adapted for receiving the terminal pins
therein, the cam defining a further partial boundary
surface for each terminal pin upon receipt thereof. The
11'75515
1 cam is movable from one position opposing such closing
bias of the contact elements and displacing same to
facilitate low-insertion force entry of pins therein to
a second position wherein the cam surfaces are inactive
in such function and permit self-biased tight engagement
of the contact elements with the pins.
In a particular form of the invention, a cam
actuator is provided for moving the cam between its first
and second positions, the cam actuator being movable in
a direction transverse to the movement of the cam. The
cam defines a plurality of openings, one connector con-
tact being situate in each, the openings adapted to re-
ceive the terminal pins therein. Each cam opening has
a cam surface therein that is movable with the cam to
engage the facing contact elements upon movement of the
cam to the first position.
In its particularly preferred embodiment, the
cam and cam actuator are plates, the cam plate being
movable in an upward direction in response to lateral
movement of the cam actuator plate. Both the cam and cam
actuator plates comprise cooperating camming surfaces,
each including a plurality of successively spaced, in-
clined cam ramps and slots for effecting movement of the
cam between the first and second positions.
BRIEF DESCRIPTION OF THE DRAWING:
Fig. l is an exploded perspective view of a
connector in accordance with the invention and showing
both a VLSI device and a companion component to be con-
nected thereby with the VLSI device.
Fig. 2 is a perspective view of a contact for
use in the connector of Fig. l.
Figs. 3-5 are respective front, side and top
plan elevations of the Fig. 2 contact.
Fig. 6 is a plan elevation of a segment of the
cam plate of the connector of Fig. 1 with one contact
seated therein for purposes of explanation.
11755~5
1 Fig. 7 is a partial sectional view of the cam
plate of the connector of Fig. 1 as seen from plane VII-
VII of Fig. 6.
Fig. 8 is a partial sectional view of the cam
plate of the conneetor of Fig. 1 as seen from plane VIII-
VIII of Fig. 6.
Fig. 9 is a seetional view as seen from broken
plane IX-IX of Fig. 6 with the cam actuating pin, con-
tact, VLSI device, device pin and eompanion apparatus
being shown without sectioning for eonvenience and sim-
plification of diseussion.
Fig. 10 is a partial seetional view as seen
from broken plane X-X of Fig. 6, with the eontact, VLSI
device, device pin and eompanion apparatus being shown
without seetioning for like convenience and simplifica-
tion of discussion.
Fig. 11 is a sectional view, as in Fig. 9, but
with the cam plate in operative position, i.e., opposing
socket element self-bias and displacing the socket ele-
ments to facilitate pin entry in the socket.
Fig. 12 is an exploded perspective view of analternative eonstruetion of the eonneetor of the present
invention utilizing a different eamming meehanism for
opening the eleetrical eontacts.
DESCRIPTION OF THE PREFERRED EMBODIMENT:
Fig. 1 depiets VLSI device 10 and companion ap-
paratus 12 for eonneetion thereto, for example, a printed
eircuit board (PCB). A conne~tor for effecting sueh
interconnection in aecordance with the present invention
comprises a housing having a base 14, defining eompart-
ment 16 upstanding from base floor 18 and bounded by side
walls 20 and 22 and end walls 24 and 26. A cam plate 28
is shown above base 14. Cover or cap 30 of the housing
has eompartment 32 upstanding from cover floor 34 and
bounded by side walls 36 and 38, end walls 40 and 42, and
keying wall 44 which extends between side wall 36 and end
11755J~S
1 wall 42. For assembly of connector parts, cover 30 has
through-bores 46, 48, 50 and 52 and base 14 has suitably
threaded registering bores 54, 56, 58 and 60. Fastener
bolts (not shown) are passed through bores 46-52 and
threaded into bores 54-60 for securing cover 30 to base
14, entrapping cam plate 28 within the housing.
VLSI device 10 has x-y dimensions compatible
with like dimensions of compartment 32 of cover 30, with
keying wall lOa orientated compatibly with keying wall
44 or cover 30. Pins 62 depend from undersurface 61
of VLSI device 10 in an x-y square array, of rows and
columns, for example, a twenty-pin by twenty-pin pre-
determined array having a total of four hundred pins.
Contacts 64 are supported in base 14 in the same array
as pins 62 on floor 18. As will be seen in detail in
enlarged views below, cam plate 28 has apertures 66 ex-
tending therethrough and arranged in the same array as
the contacts 64. Cover 30 similarly includes passages
68 in such array, whereby contacts 64 may extend through
cam plate 28 and cover 30 to be accessible from the upper
exterior of the housing to receive pins 62.
Cam plate 28 has end wings 70 and 72 providing
detents 74 and 76 for the retentive seating of inserts 78
and 80. Such inserts each have an interiorly threaded
bore for receipt of exteriorly threaded cam actuating pin
members 82 and 84. Cover 30 is provided with openings
86 and 88 for passage of members 82 and 84 therethrough.
Members 82 and 84 are accessible exteriorly of the hous-
ing and are secured to cover 30, as by use of snap rings
(ring 85 also being shown in Fig. 9) applied thereto at
the undersurface of cover 30. Upon such assembly of
members 82 and 84 with cover 30 and subsequent fastening
of cover 30 to base 14, as above discussed, the lower
ends of members 82 and 84 seat freely in base recesses,
one such recess being shown at 90.
11755~s
-- 6 --
1 As is described in detail kelow, members 82 and
84 function as position control means for cam plate 28,
i.e., by turning the members, the plate may be disposed
to confront base floor 18 or to confront the undersurface
of cover 30.
Turning now to Figs. 2-5, contact 64 has a
first terminal 64a which extends through base 12 to be
accessible below the base for engaging a terminal of com-
panion apparatus, e.g., terminal 64a may be wave soldered
to a conductive strip on PCB 12 (Fig. 1). Terminal 64a
may also be formed in straight downward configuration
for insertion into suitable metallized openings provided
in PCB 12 and soldered therein by conventional wave-flow
soldering techniques. A second terminal, serving as a
pin-rece ving socket, is provided opposite such first
terminal and is defined by facing elements 64b and 64c
which are formed in self-biased preselected attitude to
assume generally parallel stance (Fig. 3). Contact 64
is formed of beryllium copper, phosphorous bronze or
like material having sufficient resilience to exhibit
self-bias, whereby facing elements 64b and 64c will
seek to return to such parallel relation, or other pre-
selected self-biased attitude, after release from
mutually outward forces thereon opposing such inward
self-bias.
Lances 64d and 64e are struck from elements
64b and 64c to extend inwardly thereof and preferably
have arcuate facing surfaces at ends 64d-1 and 64e-1. A
central support section 64g and an outwardly flared upper
pin entry section 64f complete the contact, parts 64f-1
and 64f-2 flowing arcuately as shown to define inturned
undersurfaces 64f-3 and 64f-4 inboard of facing elements
64b and 64c.
One such contact 64 is shown in conjunction
with cam plate 28 in Fig. 6, which is a view enlarged
approximately twenty times actual size for the two-inch
1175S15
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.~
1 square, twenty-by-twenty array alluded to above. A con-
tact 64 would, of course, be resident in each of plate
apertures 66, but such other contacts are here omitted
for convenience and to simplify exposition. The segment
of plate 28 shown in Fig. 6 includes apertures 66a
through 66p, each of which has identical outline, as
now discussed for aperture 66b.
Considering Figs. 6-8 jointly with Figs. 2-5,
wall 92 and the left side walls of cam elements 94 and
96 provide a residence channel for contact facing element
64b. Similarly, right wall 98 and the right side walls
of cam elements 94 and 96 provide a residence channel for
contact facing element 64c. Contact lances 64d and 64e
are situated in a non-interference path with plate 28,
being of expanse less than the spacing across the aper-
ture between opposed cam elements 94 and 96. Conversely,
the cam elements extend marginally into the space 64h
between contact facing elements 64b and 64c. Accord-
ingly, if plate 28 were to be moved forwardly outwardly
of the plane of Fig. 6, contact 64 remaining fixed, cam
surfaces 94a and 96a would èngage contact undersurfaces
64f-3 and 64f-4 and oppose the self-bias of facing ele-
ments 64b and 64c to displace same outwardly of each
other.
As cam plate 28 is actually disposed in the
plane of Fig. 6~ the cam surfaces are inactive, being
remote from the cammed contact surfaces 64f-3 and 64f-4,
this condition of the connector being further seen in
Figs. 9 and 10. Here, member 82 is rotated fully coun-
terclockwise in insert 78, placing cam plate 28 in its
lowermost position, adjacent base floor 18. In such
cam inoperative position, contact facing elements exert
the full force of contact self-bias upon pin 62 there-
between.
The converse condition of the connector, i.e.,
cam operative position, is seen in Fig. 11. Here, member
117~i515
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1 82 is rotated fully clockwise in insert 78, placing cam
plate 28 in its uppermost position, adjacent cover 30.
In such cam operative position, contact self-bias is
opposed and contact facing elements are displaced out-
wardly of one another, bending elastically about thelocations of their exit from base apertures 100. Pin 62
is readily inserted into contact 64 under this condition
and is shown in such seated condition.
The extent of deflection of facing elements
64b and 64c in the cam operative position may be readily
established by selection of the width (W in Fig. 7) of
cam elements 94 and 96, once the configuration of con-
tacts 62 is established. Thus, while Fig. 11 shows a
zero insertion force condition, the contact lances being
non-contiguous with pin 62, advantage attends a low,
rather than zero, insertion force. Thus, the invention
prefers selection of cam element and contact dimensions
to provide, in the cam operative position, for the
spacing between opposing lance end surfaces from one
another to be less than the diameter of pin 62. The
lance end surfaces thus frictionally slidably engage pin
62 upon insertion giving rise to measurable insertion
force. The lance end surfaces are preferably arcuate,
as noted above. Upon release of the opposing force
exerted on the facing contact elements 64b and 64c by
the cam plate 28, the lances 64d and 64e, under the
influence of the self-bias force of the contact, provide
a further wiping action as between such arcuate surfaces
and the pins. By virtue of the pin wiping action, sur-
face oxides may be removed and gas-tight electrical con-
nection readily realized.
Various modifications to the foregoing dis-
closed connector will be evident to those skilled in
the art and may be introduced without departing from the
invention. For example, alternative camming mechanisms
1175S~5
1 may be used to reduce the connector profile or to en-
hance its strength by resisting bowing, especially in
connectors with greater numbers of connections, such as
in forty-by-forty pin arrays. Referring to the drawing,
Fig. 12 depicts an electronic component such as a VLSI
device 110 similar to the device 10 of Fig. 1 and having
a plurality of terminal pins 112 projecting from the
undersurrace 114 of the device 110 and companion appa-
ratus 116 for connection thereto, for example, a printed
circuit board (PCB). An alternative approach for ef-
fecting such interconnection in accordance with the
present inventior. includes a connector 118 comprising
a housing including a base 120 having a compartment 122
defined by upstanding side walls 124 and 126, end wall
128 and floor 130. The undersurface 131 of the base
120 may include a plurality of longitudinally extending
ribs 133 that provide stiffness to the base while per-
mitting a minimal thickness.
A cam actuator 132 is configured in the form
of an elongate plate within the base compartment 122
for sliding longitudinal movement relative thereto, as
illustrated by the arrow 134. The undersurface 136 of
the cam actuator 132 includes a plurality of longitudi-
nally extending, laterally spaced teeth 138 that are
adapted to slide within a like plurality of tracks 140
formed in the base floor 130. Movement of the cam actu-
ator 132 is effected by an actuator pin 142 having a
shaft 144 and an eccentric portion 146. The shaft 144
is adapted to be received in an aperture 148 in the
base 120 and the eccentric portion 146 is captively re-
tained in an elongate opening 150 provided through a
solid portion 132a of the cam actuator 132. The open-
ing 150 is formed to closely receive the eccentric por-
tion 146 such that upon rotation of the pin 142, the
eccentric portion 146 will engage the walls of the cam
actuator adjacent the opening 150 and move the cam
1175515
-- 10 --
1 actuator plate longitudinally relative to the base 120.
A slot 143 is provided in the upper surface of the pin
shaft 144 to receive a screwdriver or like instrument
for facilitating rotation of the pin 142.
The cam actuator 132, in its preferred form,
includes a plurality of fingers 152 extendin~ longi-
tudinally from the cam actuator solid portion 132a and
terminating in free ends 152a. Each of the fingers is
laterally spaced by an opening (not shown). The upper
surface of each finger 152 is a camming surface and
includes thereon a plurality of inclined cam ramps 154
and slots 156, successively spaced in the longitudinal
direction and described in more detail hereinbelow.
The free ends 152a of the fingers 152 are adapted to
be slidably received in corresponding openings 128a
provided in the end wall 128 of the base 120 upon move-
ment of the actuator 132.
A cam plate 158 overlies cam actuator 132, the
cam plate 158 adapted to fit within the compartment 122
of base 120 and to move vertically relative thereto as
shown by arrow 160. The bottom surface 158a of the cam
plate 158 is a camming surface and comprises a plurality
of laterally spaced, longitudinally extending rows of
inclined cam ramps 162 and slots 164 that are adapted to
cooperate with the cam ramps 154 and slots 156 on the
cam actuator plate 132. Movement of the cam plate 158
is restricted to the vertical direction by the base end
wall 128 and a front wall 166 of a cap 168 that is se-
cured to the base 120 as by screws 170 (only one of
which is shown). Tabs 172 and 174 project from the cam
plate 158 and slide vertica]ly within slots 128b in the
rear wall 128 while tabs 176 and 178 slide vertically
within slots 166a in the front wall 166 in cap 168.
The cap 168 further includes an aperture 169 for re-
ceiving the shaft 144 of the pin 142 for external access
11755~15
-- 11 --
1 thereto. F~r assembly of the cap 168 to the base 120,
the cap 168 has apertures 180 and 182 and base 120 has
suitably threaded registering bores 184 and 186. In
the preferred form, the base 120, cam actuator 132, cam
plate 158 and the cap 168 are made of a suitably rigid
plastic material.
VLSI device 110 has X-Y dimensions compatible
with the base 120, base 120 having internal ledges as at
124a and 126a to support the VLSI device 110 in the con-
nector 118. The pins 112 depend from the undersurface
114 of VLSI device 110 in an X-Y square array of rows
and columns, for example, a twenty-pin by twenty-pin
predetermined array having a total of four hundred pins.
A like number of contacts 188 are supported in the base
in a like array of apertures 190 provided in the base
floor 130. The cam plate 158 has apertures 192 extend-
ing therethrough and arranged in the same array as the
contacts 188. The contacts 188 project upwardly from
the base 120 through the lateral openings (not shown)
between the fingers 152 and into the apertures 192 in
the cam plate 158. The contacts 188 may receive the
terminal pins 112 between their biased facing elements
without the lances as described with reference to Figs.
2-5.
In operation, rotation of the pin 142 provides
longitudinal movement of the cam actuator 132 which, in
turn, with the cam ramps 162 of the cam plate riding on
the cam ramps 154 of the cam actuator provides vertical
upward or downward movement of the cam plate 158 within
the connector 118. Cam surfaces disposed within the aper-
tures 192, similar to those described with reference to
the arrangement in Figs. 6-8 hereinabove, move the con-
tacts to an open position to freely receive the terminal
pins 112 therein. Camming plates having such apertures
constructed to receive both the contact facing elements
and the VLSI terminals while defining partial boundaries
117~i515
- 12 -
f
1 about the VLSI pins contribute to the low profile of the
connector.
It should be noted that the eonneetor arrange-
ment as described herein and shown in Fig. 12 places both
the cam plate 158 and eam aetuator 132 in compression
against the bottom floor 130 of the base 120 under the
influenee of the spring foree of the eontaets 188. Such
construction substantially minimizes the problems of
bowing or bending of the cam plate 158 upon movement up-
ward to spread apart the contact elements. As a result,
a larger array of pins than in the known art having very
close centers in both row and eolumn direetions (e.g.,
0.1 ineh by 0.1 ineh) can be accommodated without prob-
lems of the strength of the material or the stiffness
of the cam plate itself.
Having described the eonstruction and operation
of the eonnectors herein, it should now be appreeiated
that multi-pin eonneetions between the pins of a VLSI
deviee and a eompanion PCB may be readily effeeted with
zero or low insertion foree. The particularly deseribed
arrangements are intended to be illustrative and not
limited thereto. The true seope of the invention is set
forth in the following elaims.
