[0001] This application relates to an electrical connector and a terminal for use in the
electrical connector of the type suitable for use in establishing an interconnector
to traces on a circuit panel, especially to an electrical connector socket for use
in establishing electrical interconnections to a single in-line memory module.
[0002] Single in-line memory modules represent a high density, low profile single in-line
package for electronic components such as dynamic random access memory integrated
circuit components. A plurality of these components can be mounted in line on a circuit
panel whose height is little more than the length of the components themselves. The
circuit panels can in turn be mounted on a printed circuit board daughtercard which
can then be mounted on a printed circuit board mothercard. The spacing between adjacent
daughtercards would then need to be only slightly greater than the height of the individual
circuit panels or single in-line memory modules.
[0003] One approach for mounting single in-line memory modules on a daughterboard would
be to employ plug in leads adjacent one edge of the circuit panel. These plug in leads
can then be connected to conventional printed circuit board contacts such as miniature
spring contacts.
[0004] An alternate approach has been to use single in-line memory module sockets to establish
a disconnectable interconnection to traces along the edge of the circuit panel used
in the single in-line memory module. Terminals for use in such sockets are disclosed
in U.S. Patent 4,557,548 and U.S. Patent 4,558,912. Additional details of an insulative
housing which is suitable for use with those terminals is disclosed in U.S. Patent
4,781,612. The socket disclosed in these patents is intended for use with in-line
memory modules having a center line spacing for pads or traces at the edge of the
circuit panel of 0.100 inch(about 2,5mm). Since the terminals employed in that socket
are stamped and formed, the width of the terminals generally precludes establishing
an interconnection on closer center line spacings. Instead of using stamped and formed
terminals, other single in-line memory module sockets employ edge stamped terminals.
For example, U.S. Patent 4,737,120 discloses an electrical connector of the type suitable
for use in a single in-line memory module in which a zero insertion force interconnection
is established between the terminals and the pads on the circuit panel. The circuit
panel is inserted at a angle and then cammed into position. The insulative housing
on the connector provides a stop to hold the circuit panel in position. Another zero
insertion force connector is disclosed in U.S. Patent 4,575,172. The contact terminals
in each of these patents is edge stamped sockets using terminals of this type are
suitable for use on center line spacings on the order of 0.050 inches (about 1,3 mm).
[0005] Each of these zero insertion force configurations provides limited wipe between the
contacts and the pads on the printed circuit board. It is understood that full force
wipe is desirable in order to remove contaminates which may build up either on the
terminals or on the printed circuit board pads or traces. U.S. Patent 4,725,250 discloses
a socket connector employing a terminal in which a full force wiping action is established
between the terminals and the surface pad portions of traces on the circuit panel.
This connector also includes edged stamped terminals. The connector shown in U.S.
Patent 4,725,250 is suitable for use with standard single in-line memory modules.
However, not all commercially available single in-line memory modules are manufactured
in compliance with generally accepted standards for such modules, such as appropriate
JEDEC standards. Nonstandard single in-line memory module circuit panels are manufactured
with the pad portions of the traces adjacent the edge of the circuit panel being shorter
than required by industry acknowledged standards. The connector disclosed in U.S.
Patent 4,725,250 is unsuitable for use with circuit panels having short pad portions
where contact must be established immediately adjacent the edge of the circuit panel
because of the height of the beams used to establish the full force wipe contact in
that connector.
[0006] Deviations in JEDEC standards have also occurred because some module manufacturers
have been unable to maintain a tolerance of ± 0.003 inches (about 0,08mm) on the module
thickness as required by JEDEC. Tolerances of ± 0.008 inches (about 0,2mm) are more
realistic; but such tolerances complicate the design of the terminal because a larger
deflection range is necessary. Lengthening the terminals is not suitable because the
improved density offered by SIMM's is compromised and contact cannot be established
adjacent the edge of the module.
[0007] Not only have non-conforming single in-line memory modules begun to appear, but the
basic single in-line memory module socket is being adapted to applications in which
additional integrated circuit components are positioned on the circuit panel. Indeed
the height of the circuit panel has been increasing as more and more integrated circuit
packages are added to the modules. Modules referred to as SAM's (special application
modules) using the basic SIMM approach. For instance, boards using the SIMM approach
now have a height of 2.0 to 3.5 inches (about 5 cm to about 9 cm). The additional
height of these circuit panels, makes it difficult for standard sockets to stabilize
these components since conventional panel guides used in such sockets do not have
a height sufficient to engage these circuit panels adjacent there upper end. The instant
invention provides not only a means for stabilizing circuit panels having a greater
height, but also employs a terminal suitable for establishing electrical contact adjacent
the edge of the circuit panels so that this full force wipe connector can be employed
with non-standard single in-line memory module circuit panels.
[0008] An electrical connector or socket suitable for use in establishing electrical contact
with the edge of traces on at least one side of a circuit panel, such as a single
in-line memory module, is disclosed. The connector includes a plurality of terminals
mounted in an insulative housing. Terminals are edge stamped from a spring metal blank,
so that the connector can achieve close center line spacings. Each terminal has opposed
beams extending upwardly from a base. The beams are deflectable upon insertion of
a circuit panel therebetween. Each beam has an upwardly extending portion with a loop
section intermediate the ends. The downwardly extending portion of the beam, located
on the interior of the upwardly extending portion, includes a contact section adjacent
the end of the downwardly extending portion. The terminals are positioned within an
insulative housing having at least one upwardly open slot into which the circuit panels
are inserted. A plurality of cavities are located along the slot, on either side of
the slot. The terminals are positioned within the housing cavities with the contact
point on each downwardly extending arm of the contacts extending into the circuit
panel receiving slot. In the preferred embodiment, the terminals are inserted into
the housing from the lower surface. Each terminal includes a upwardly extending post
or barb which can be secured within a central spine and secures the terminals in position
within the housing and provides a stop against which the edge of the circuit panel
will abut if the circuit panel is inserted too far into the panel receiving slot.
Figure 1 is a perspective view of the socket comprising the preferred embodiment of
this invention to the edge of a circuit panel of a single in-line memory module shown
exploded above a panel receiving slot.
Figure 2 is a view of a terminal used in this socket, showing the deflection as determined
by finite element analysis of the terminal (in phantom) when a circuit panel is inserted
between the opposed beams.
Figure 3 is a sectional view taken along section lines 3-3 in Figure 1 showing the
position of the terminals within the housing and showing the interface of one panel
support member located at the end of the housing.
Figure 4 is a view similar to Figure 3 showing two circuit panels inserted into engagement
with terminals and showing the deflection of flexible walls in the panel support member
for stabilizing the printed circuit panels.
Figure 5 is a perspective view of a portion of the center of the insulative housing,
which is partially in section to show the internal configuration of the housing between
terminal positions.
Figure 6 is a partial view similar to Figure 5, but showing a section through the
housing cavities with the terminals removed.
Figure 7 is a alternate embodiment of the invention showing the same terminal configuration
but a different panel support configuration.
[0009] Single in-line memory module socket or connector 2 employs a plurality of terminals
10 positioned within an insulative housing 20 to establish contact with traces 6 on
a circuit panel 4 adjacent one edge 4a of the circuit panel. This connector 2 is suitable
for use with a circuit panel 4 having traces in which the center line spacing of that
portion of the trace 6 adjacent the edge 4a of the circuit panel being spaced from
the next adjacent terminal on center line spacings of 0.050 inches (about 1,3 mm).
The terminals 10 are edge stamped from a spring metal blank and are formed of a material
such as beryllium copper or of phosphor bronze. Each terminal 10 is suitable for establishing
an electrical contact with traces on at least one side of the circuit panel adjacent
the edge of the traces.
[0010] Each terminal 10 has opposed beams 12 extending upwardly from a base 14. A post or
barb 16 extends upwardly from the center of the base 14 between the opposed beams.
A contact tail 18, aligned with the post or barb 16 extends from the bottom of the
base and is suitable for establishing an electrical interconnection with a printed
circuit board on which the socket 2 can be mounted.
[0011] The opposed beams 12 are deflectable upon insertion of a circuit panel 4 between
the beams. Each of the beams 12 comprises an upwardly extending portion, extending
from one end of the base 14 which extends between the two opposed beams 12. The upwardly
extending portion 12a is connected to the base 14 and is inclined inwardly. Inwardly
inclined arms 12b extend downwardly from the top 12c of the upwardly extending portion.
These inwardly inclined arms 12b diverge from the inwardly inclined portion of the
upwardly extending portion 12a. An inwardly extending loop section 12d is located
between the top and the bottom of the upwardly extending portion 12a of each of the
opposed beams 12. In the preferred embodiment of the terminal, that portion of the
beams between the base 14 and the loop sections 12d is tapered The elevation of inwardly
extending loop section 12d is such that it is located between the base 14 and the
end of the downwardly extending portion 12b. Indeed, the inwardly extending loop 12d
is located below the downwardly extending portion 12b in the preferred embodiment
of this invention. The inwardly extending loop section 12d is a generally U shaped
member in which the bight of the loop section 12c is located along the inner edge
of the opposed beams 12 with the open portion of the U-shaped loop facing outward.
The two parallel sides of the U shaped loop section 12c are generally parallel to
the base 14 and the bight is generally curved. A contact point 12e is located at the
innermost extent of the downwardly extending portion 12b and the contact point 12e
is located adjacent the end of each beam 12. The contact 12e is located above the
loop section 12d. As shown in Figure 2, the opposed beams 12 are configured such that
the majority of the flexure of the opposed beams 12 in the loop section 12d, the base
14 and in that portion of the terminal between the base and the loop. A relatively
large deflection of the contact point 12e can be achieved without increasing the height
of the beams 12.
[0012] Post 16, which comprises a barb, extends upwardly from the base 14 between the two
opposed beams 12. Indeed, post 16 is located between the two contact points 12e on
opposed beams 12. The elevation of the upper surface of post 16 is such that it is
substantially at the same elevation as the loop section 12c.
[0013] The insulative housing 20 can be molded of conventional engineering plastic materials
suitable for use in electrical connectors. Housing 20 has a generally rectangular
central section extending between two panel guide or panel support members 30 located
at either end thereof. In the preferred embodiment of this invention, two panel receiving
slots 20 extend between the panel guides 30 and open upwardly on the upper face 20a
in the insulative housing 20. The two slots 22 are parallel. A plurality of cavities
24 also open upwardly on the upper face 20a of the insulative housing 20 and communicate
with a corresponding panel receiving slot 22 in the dual row connector comprising
the preferred embodiment of the invention. Individual cavities 24 communicate only
with one of the slots 22. Each of the cavities 24 is open on the top and the bottom
of the insulative housing 20 and each cavity 24 extends on opposite sides of the corresponding
upwardly open slot 22. A central spine 26 comprises the portion of the insulative
housing 20 located below each of the panel receiving slots 22. As shown in Figure
5, the central spine 26 comprises a solid portion of the insulative housing 20 at
positions between cavities 24. The cavities 24 are positioned to intersect the slot
22 with housing ribs 28 comprising that portion of the central spine 26 extending
through each cavity. These housing ribs 28 extend downwardly from the lower surface
of slots 22, which comprises the upper surface of the central spine 26, and a hole
26a is located between the housing ribs 28. Each cavity 24 is open both on the upper
face 20a of the insulative housing and on the lower face 20b. Each cavity 24 extends
below the housing ribs 28.
[0014] The panel guide or panel support members 32 are located at the opposite ends of the
insulative housing 20. Each of these panel guides extends upwardly above the upper
face 20a of the insulative housing 20 and has an inner face 30a. Panel grooves 32
having open inner ends are inwardly facing and communicate with each panel receiving
slot 20. Panel grooves 32 also extend upwardly above the panel receiving slots 22.
Panel gripping portions in the form of ridges 34 which comprise constricted portions
of the panel receiving grooves 32 are spaced above the open upper end of the panel
receiving slot 22. Recesses or relief slots 36 are located on opposite sides of the
grooves 32 to define flexible walls 38. These flexible walls are joined as part of
the panel support members 30 in the preferred embodiment of this invention. A central
pocket 40 is located along the lower end of the panel support members 30 in the preferred
embodiment of this invention, and the relief slots 36 in the vicinity of ridges 34
extend upwardly from this pocket 40.
[0015] Terminals 10 are inserted into corresponding cavities 24 from the bottom of the insulative
housing 20. The contact points 12e of the opposed beam 12 are spaced apart by a distance
less than the width of the central spine within the cavities. In other words, the
contact points 12e are spaced apart by a distance less than the spacing of the exterior
surfaces of the two ribs 28 within the cavities 26. When the terminals 10 are inserted
into cavities 12, the opposed beams 12 are deflected outwardly upon engagement with
the ribs 28. Continued movement of the terminal into the cavities 26 from below allows
the inwardly inclined arms to spring back to their original position so that each
inwardly inclined arm 12b projects into the slot from opposite sides. In other words,
the contact point 12e is now positioned within the panel receiving slot 22. The post
or barb 16 extending upwardly from the base 14 on terminal 10 is also aligned with
the panel receiving slot 22. The upper surface of each post 16 extends above the bottom
of the cavity. The post or barb 16 extends into the hole 26a located between the two
housing ribs 12b and the barb secures the corresponding terminal to the central spine
26 by virtue of its engagement with the two ribs 28.
[0016] When a circuit panel 4 is inserted into a panel receiving slot 20, the traces, or
the contact pads located on the ends of the traces adjacent the edge 4a of the circuit
panel, engage the downwardly extending portion 12b of the opposed beams 12 and deflects
these downwardly extending inwardly inclined arms 12b outwardly. Contact points 12e
are brought into contact with these traces adjacent the edge 4a of the circuit panel.
The edge 4a of the circuit panel is also juxtaposed to the post so that contact points
indeed engage these traces adjacent the edge. Full force wiping between the contacts
and trace pads occurs. Such engagement is especially significant when a non-standard
single in-line memory module is employed in this socket.
[0017] The panel support members 30 are also configured to support and stabilize especially
tall single in-line memory modules. As the circuit panel is inserted into the grooves
32, aligned with the panel receiving slots 20, the flexible walls 38 are deflected
when the ridges, forming a constricted portion 34, engage the sides of the circuit
panel 4. These ridges serve to both align and secure the circuit panel within the
socket 2.
[0018] As shown in Figure 7, an alternate panel support guide configuration 130 can be employed
with cantilever beams 138 having a panel gripping protrusion 134 adjacent their upper
ends. Figure 7 therefore illustrates that terminals 10 can be employed in other configurations
and are not dependant upon the use with the panel support guides 30 comprising the
preferred embodiment of this invention. Therefore, it would be clear to one of ordinary
skill in the art that the instant invention can be employed in differing configurations
and the following claims are not limited to the precise embodiment depicted as the
preferred embodiment of this invention or the embodiment comprising the alternate
embodiment of Figure 7.
1. A terminal (10) for use in establishing electrical contact with traces (6) on at
least one side of a circuit panel (4), comprising a member edge stamped from a spring
metal blank, the terminal (10) having opposed spaced apart beams (12) extending upwardly
from a base (14) between the beams, the beams being deflectable upon insertion of
a circuit panel therebetween, each beam having an upwardly extending portion (12a)
connected to the base (14) and a downwardly extending portion (12b) extending from
the top of the upwardly extending portion (12a), the terminal being characterized
in that the upwardly extending portions (12a) each have an inwardly extending U-shaped
loop section (12d) between the base (14) and the downwardly extending portion (12b).
2. The terminal (10) of claim 1 wherein the portion of the upwardly extending portion
(12a) above the loop section (12d) is inclined inwardly.
3. The terminal (10) of claim 1 or 2 wherein the downwardly extending portion (12b)
diverges from the inwardly inclined portion of the upwardly extending portion (12a).
4. The terminal (10) of claim 3 wherein a contact point (12e) comprising the innermost
extent of the downwardly extending portion (12b) is located adjacent the end of each
beam.
5. The termincal (10) of any of claims 1 to 4 wherein the loop section (12d) is located
below the downwardly extending portion.
6. The terminal (10) of any of claims 1 to 5 wherein the terminal (10) has a barb
(16) extending upwardly from the base, between the two opposed beams (12).
7. The terminal (10) of claim 6 wherein the top of the barb (16) has substantially
the same elevation as the loop sections.
8. The terminal (10) of any of claims 1 to 7 wherein a downwardly extending contact
tail (18) extends from the bottom of the base (14).
9. The terminal (10) of claim 8 wherein the contact tail (18) is aligned with the
barb (16).
10. The terminal (10) of any of claims 1 to 9 wherein the loop section (12d) is positioned
so that the majority of the deflection of the terminal occurs in the loop section
(12d), the base (14), and the portion of the terminal between the base (14) and the
loop section (12d).
11. An electrical connector (2) for use in establishing electrical contact adjacent
the edge of traces (6) on at least one side of a circuit panel (4), the connector
(2) comprising:
a plurality of terminals (10), each having opposed beams (12) with inwardly inclined
arms;
an insulative housing (20) having at least one upwardly open slot (22) and a plurality
of upwardly open cavities (24) communicating with the slot (22), the terminals (10)
being positioned in the cavities (24) with the inwardly inclined arms projecting into
the slot (22) from opposite sides, contact points (12e) being located adjacent the
lower end of each inwardly inclined arm; and
panel support members (30) located at opposite ends of the insulative housing (20),
the panel support members (30) each including inwardly facing grooves (32) communicating
with each slot (22) and extending above the slot (22), each groove (32) including
a panel gripping means (34) spaced above the open upper end of the slot; the connector
being characterized in that a relief slot (36) is located adjacent each of the grooves
(32) to define a flexible wall (38) on one side of each groove, the flexible walls
(38) being joined as part of the panel support members (30) at each end of the flexible
walls, the panel gripping means (34) being located on the flexible walls, whereby
the circuit panel (4) can be inserted into the slot (22) so that the contact points
engage the traces adjacent the edge thereof.