US 3683317 A
An electrical connector of the type receiving a male component lead is characterized by imposition of extremely small or no insertion forces on the male lead in order to make electrical connection. An elastically deformable contact strip forms at least one side of a cavity, and means are provided for deforming the contact strip in a lengthwise direction. When the contact strip is in its relaxed state, the male lead can be inserted freely in the cavity alongside the strip without significant insertion force. The contact strip has a curved portion with a contact area facing the inserted male lead, and a compressible portion connected at one end to the curved contact portion and being substantially fixed with respect to the cavity at the other end. As the contact strip is deformed lengthwise, the contact area tends to expand across the cavity to exert a contact force against the male lead, and the compressible portion shrinks in its lengthwise dimension, thereby wiping the contact area along the male lead for reliable film-removing electrical contact. The contact strip, in some examples, is formed with a portion having a second contact area which resiliently touches the opposite side of the male lead from that contacted by the first contact area.
Description (OCR text may contain errors)
United States Patent [451 Aug. 8, 1972 Walkup  MINIMAL INSERTION FORCE CONNECTOR  Inventor: William B. Walkup, Southboro,
 Assignee: Cambridge Thermionic Corporation 221 Filed: July 20,1970
21 App1.No.: 56,298
 US. Cl. ..339/75 MP, 339/17 C, 339/174, 339/176 MP  Int; Cl ..H05k H07, H01! 13/54  Field of Search ..339/17 C, 17 CF,17 F, 17 L, 339/17 LC, 17 LM, 17 M, 74, 75 M, 75 MP,
75 T,174, 176 M, 176 MP, 176 MP, 191 M,
 References Cited UNITED STATES PATENTS 3,329,926 7/1967 Aksu et al. ..339/176 MP FOREIGN PATENTS OR APPLICATIONS 869,497 5/1961 Great Britain ..339/1 7 L Primary ExaminerMarvin A. Champion Assistant Examiner-Lawrence J. Staab Attorney-Roberts, Cushman & Grover  ABSTRACT tact strip in a lengthwise direction. When the contact strip is in its relaxed state, the male lead can be inserted freely in the cavity alongside the strip without significant insertion force. The contact strip has a curved portion with a contact area facing the inserted male lead, and a compressible portion connected at one end to the curved contact portion and being substantially fixed with respect to the cavity at the other end. As the contact strip is deformed lengthwise, the contact area tends to expand across the cavity to exert a contact force against the male lead, and the compressible portion shrinks in its lengthwise dimension, thereby wiping the contact area along the male lead for reliable film-removing electrical contact. The contact strip, in some examples, is formed with a portion having a second contact area which resiliently touches the opposite side of the male lead from that contacted by the first contact area.
Use of the foregoing connector involves first, inserting the male lead while the contact strip is in its relaxed state, permitting free insertion, second, deforming the contact strip in a lengthwise direction to being about a film wiping contact between the male lead and contact area, and third, holding the contact strip in its deformed configuration for as long as electrical contact is desired to be maintained.
Sockets, for example to receive integrated circuit modules with linear arrays of male leads, employ connectors of the type described in multiple configuration, with cavity means positioned for receiving the male leads, a plurality of contact strips deformable lengthwise to yield the firm wiping contact described above, movable means for simultaneously deforming a plurality of the contact strips, and fastener means, such as screws, for holding the contact strips in deformed configuration.
' 15 Claims, 15 Drawing Figures PATENTl-imus 8 I972 3,683,317
sum 2 or 3 1 MINIMAL INSERTION FORCE CONNECTOR BACKGROUND OF THE INVENTION The field of the present invention relates to electrical connectors of the type receiving a male component lead, such as is found on an integrated circuit module or similar device, where high insertion forces are undesirable.
In current electronic fabrication, it is typical to mount integrated circuit wafers or chips on standardized interconnection packages, which have protruding therefrom a number of interconnecting pins or leads in a standardized pattern for connection into larger circuit assemblies. As integrated circuits become more complex and comprehensive, the number of interconnections with other circuit elements increases, with a concomitant increase in the number of connector pins or leads extending from the standardized package. If the advantages of miniaturized circuitry are to be retained, the mounting packages must not increase in size very much. This situation yields integrated circuit packages which have a large number of small, mechanically weak, leads which are to be connected to other circuit assemblies. Connection of the integrated circuit packages with other electronic assemblies has typically been by direct soldering or by means of sockets with pin receptacles in a pattern corresponding to the pin pattern on the package. The sockets can be wired into the assembly with no chance of thermal damage to the integrated circuits, and offer the further advantage of easy replaceability of integrated circuits should they become defective. However, the interconnection of an IC package and its socket raises problems as the number of interconnections increases. First, each pin-socket connection requires a given amount of insertion force for reliable contact, since it is typically necessary to provide a forceful wiping contact to remove high resistance films which form on pin or socket elements. The total force needed can become high if there are a large number of connections to be made, which makes accurate inser tion into the socket difficult. Second, as the number of connectors increases, their mechanical strength tends to decrease in order to retain space advantages. Third, as the number of connectors increases, it is typical that the value of the integrated circuit increases in a geometric relationship. Thus any destruction of a lead, which would result in the rejection of the entire package, would have great economic consequences. Thus, it can be seen that a number of factors working together call for some improved manner of connecting integrated circuit packages into electronic assemblies so as to minimize the possibility of package destruction or damage during the interconnection, and preferably without losing the advantages of easy replaceability and thermal safety offered by socket connectors. Many of the same problems are found not only in connection of integrated circuit packages, but are found also in other connection contexts where for some reason one of the connectors is fragile, or the net insertion force is excessive, or the cost of damaged components is high.
SUMMARY OF THE INVENTION Objects of the present invention are to provide a device for making electrical contact with a male connector or pin or lead which permits electrical connection to be made easily and reliably with minimal likelihood of harm to the male connector, and which can be easily and inexpensively manufactured in sizes corresponding to those presently utilized for integrated circuit packages, and which further permits the male connector to be removed or replaced.
According to the invention, the device for making electrical contact with a male connector is characterized by imposition of low insertion forces on the male connector and comprises an elastically deformable contact strip of conductive material, means including said contact strip for forming a cavity into which the male connector is freely insertable when said contact strip is relaxed, and means to deform said contact strip in a lengthwise direction. The contact strip has a curved portion with its convex surface forming a contact area facing the inserted male connector, a said curved portion tending to expand its contact area across the cavity to exert a force against the male connector as said contact strip is deformed in a lengthwise direction. The contact strip preferably further has a second portion adjacent the curved portion, which compresses as the strip is deformed in a lengthwise direction, thereby wiping said contact area along the male connector for removal of non-conductive films and reliable contact. Means are also preferably provided for holding the contact strip in its deformed position of contact with the male connector. The device of the present invention is used by first, placing the contact strip in its undeformed position, second, freely inserting the male connector in the cavity alongside the undeforrned contact strip, third, deforming the contact strip in a lengthwise direction to bring the contact strip into reliable electrical contact with the male connector, and fourth, retaining the contact strip in its deformed configuration to maintain the contact.
Preferably, the contact strip has not only the first and second portions described above, but also a third portion connected to the second portion and facing the contact portion for contact with the male connector, the third portion preferably resiliently supporting the male connector.
In another aspect, the invention is a socket employing a plurality of connector devices as described above, and designed for use with a package having a plurality of male connectors. The socket comprises cavity means receiving the male connectors, a plurality of contact strips deformable lengthwise so as to provide the wiping contact described above, means movable to simultaneously deform a plurality of said contact strips, and means for holding the movable means with the contact strips in deformed position. Preferably the cavity means is formed with a molded plastic base receiving the contact strips and the movable deforming means is a mount for said contact strips which is attached to one of the base members and which causes the strip to be deformed as the member is moved.
These and other objects and novel aspects of the invention will be apparent from the following description of preferred embodiments.
DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of a connection device according to the invention;
FIGS. 2, 3, and 4 are side views of the connector of FIG. 1 illustrating successive positions of the contact strip as it is deformed in a lengthwise direction to establish electrical contact;
FIG. 5 is a plan view, partially broken away, of a socket according to the invention;
FIG. 6 is a right end view of the socket of FIG. 5;
FIG. 7 is a section on line 7-7 of FIG. 5;
FIG. 8 is a bottom view of the socket of FIG. 5;
FIG. 9 is a section on line 99 of FIG. 7;
FIG. 10 is an isometric view of another embodiment of the invention;
FIG. 11 is a plan view of still another embodiment of the invention, adapted to receive a printed circuit card;
FIG. 12 is a section on line 1212 of FIG. 11 showing the device in position for insertion of a printed circuit card;
FIG. 13 is a section similar to FIG. 12, showing the device positioned to establish electrical contact;
FIG. 14 is a section on line 14-14 of FIG. 11; and
FIG. 15 is a partial section, similar to FIG. 14, showing 1-modification.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 14 illustrate the basic construction and operation of an electrical connecting device 10 of the present invention, designed to accept and make electrical contact with a male connector 12 associated with an arbitrary electrical device 14, a portion of which is shown in the drawing. The connecting device 10 as illustrated, comprises an elastically deformable contact strip 16 of conductive material, e.g., beryllium copper initially shaped on a slide press and subsequently hardened to provide appropriate springness or elasticity. The deformable contact strip 16 lies in a recess 18 formed between a fixed base member 20 and a movable base member 22, both of which can be molded from a non-conductive plastic material. In brief summary, the deformable contact strip, when in relaxed position (FIGS. 1 and 2) forms an open pocket or cavity 24 in which the male connector 12 may be freely inserted, with little or no insertion force. Thereafter, the base member 22 is moved relatively to the base member 20 (downwardly in FIGS. 3 and 4) to deform the contact strip 16 in a manner which causes a contact area 26 of the strip 16 to first contact the connector 12 (FIG. 3) and to then rub therealong under firm pressure for efficient film removal and effective electrical contact therebetween (FIG.4).
In greater detail, the construction of deformable strip 16 and base members 20 and 22 to provide the operation described above is as follows. The deformable contact strip 16 can be subdivided functionally into four portions. A first portion 16.1 extends through a hole 28 in fixed base member 20 for connection to other electrical circuit components as by soldering, wire wrapping, or the like. As illustrated, the portion 16.1 may be situated substantially collinear with the connector 12 so that the device 10 establishes the same pattern for connections as the electrical device 14, thereby making the device 10 compatible with standard circuit board patterns and procedures. A second portion 16.2 of the strip 16 provides a resilient wall at one side of the cavity 24 in which the connector 12 is inserted. This resilient portion 16.2 is comprised of an offset portion 16.21 extending from connector portion 16.1 over a ledge 30 provided in base member 20, a relatively flat portion 16.22 resting against interior surface 32 of base member 20, and another relatively flat portion 16.23 folded over from the portion 16.22 to provide one side of pocket 24. So formed, the side 16.23 is not rigid, but provides resilient support for connector 12, and an additional contact surface 16.24 touching connector 12 opposite contact surface 26. As shown in FIG. 3, the lower end of portion 16.23 swings over to bear against the upper end of portion 16.1 as the connector is closed, and then remains secured in this position as the connector is closed further to provide the wiping contact described above.
The remaining two portions 16.3 and 16.4 of the contact strip 16 provide the desired wiping contact. Portion 16.4 is a curved or bent portion whose outer convex surface faces the male connector 12 and forms the contact area 26 which rubs thereagainst. The portion 16.3 is an initially flat portion which lies against inner surface 34 of movable base member 22 when the contact strip is relaxed (FIG.2), and which swings away therefrom as the upper end of portion 16.4 is pushed downwardly by overhanging lip 36 provided on movable base member 22 (FIG. 3). When the lower end of portion 16.23 meets the stop provided by the upper end of portion 16.1, as shown in FIG. 3, the lower end of the compressible portion 16.3 is firmly fixed. Further downward motion of movable base 22 results in the lengthwise deformation of portions 16.3 and 16.4, which results in the bending of portion 16.3 to reduce its lengthwise dimension, and in the downward travel of contact area 26 along male connector 12. At the same time that the contact area 26 is wiped along the connector 12, the curved portion 16.4 is pushed with increasing sidewise force against connector 12, this force being resisted by the resilience provided by portion 16.2 and contact area 16.24 with the result that the connector 12 is reliably secured in a pinching fashion between the two contact areas. As shown by FIGS. 3 and 4, the portions 163 and 16.4 substantially form an S-shape whose ends are moved closer to one another as the connector is closed, with the result that the S-shape becomes shorter and wider, this action urging the contact surface 26 both outwardly against and downwardly along the member 12 against which it rests.
It can be appreciated that the provision of resilient backing portion 16.2 not only provides an additional contact area 16.24 for lower contact resistance, but also permits pocket 24 to be made wider, and to handle a larger range of thicknesses of connectors 12, for any given set of positional and flexural tolerances imposed on the contact strip 16 and on the base members 20 and 22. Thus, the pinching forces on connector 12 can be made more uniform, and less dependent on positioning of contact strip portions 16.3 and 16.4 and on thicknesses of connectors 12.
Once portions 16.3 and 16.4 of contact strip 16 have been deformed in a lengthwise direction to produce electrical contact with connector 12, the contact strip 16 is maintained in its deformed configuration, as symbolized by pin 38 engaging base members 20 and 22 and preventing their relative movement (FIG. 4).
From the above description of the construction and operation of the connector device 10, it can be seen that base members 20 and 22 engaging contact strip 16 exist to provide fixed support for the portions 16.1 and 16.2 of the contact strip and movable support for the end of portion 16.4 permitting lengthwise deformation of portions 16.3 and 16.4. Thus, a number of constructional variations are possible, e. g., instead of making lip 36 integral with a movable base member 22, an altemative construction attaching a movable lip to a fixed base member could be used. Other such variations will be apparent.
It is similarly apparent that variations in construction of contact strip 16 can also be made, for example, by omitting or modifying one or more of the fourportions which compose it. Resilient portion 16.2 might be omitted if its added contact area and resilient support were not needed; external connection portion 16.1 might be omitted if other connection provisions were made; compressible portion 16.3 might be shortened or eliminated if curved portion 16.4 were sized to provide an adequate rotation or bending to wipe contact area 26 along the male connector 12; similarly, curved portion 16.4 might take different shape and still provide a contact area 26 to be brought into wiping contact with male connector 12. Some of these variations are illustrated in the following embodiments in which parts similar or analogous to those described with reference to FIGS. 1-4 are designated by the same numerals, prefixed with the added numeral 1, 2 or 3. Thus, the numerals 12, 112, 212 and 312 designate similar parts.
FIGS. 5-9 illustrate a socket 100 utilizing a plurality of connector devices 110 each similar to the device described above, and adapted to receive electrical connectors 112 extending from an electrical device 114. The particular device 114 illustrated comprises a flat oblong slab 114.1 upon which an integrated circuit chip 114.2 is placed, and two rows of connectors 112 extending downwardly from opposite sides of the slab. The connectors 110 of the present invention are particularly advantageous when used with this type of device, which is fragile, susceptible to thermal destruction, and expensive to replace.
The socket 100 comprises a fixed base member 120, adapted to rest on a circuit board, for example, and a movable base member 122 interfitting therewith so as to permit sliding vertical movement. Both fixed and movable base members can be molded with plastic materials. A plurality of screws 138 interconnect fixed base member 120 and movable base member 122, and as will be explained hereafter, serve as the means for closing the connectors 110 and holding them in closed contact position.
Fixed base member 120 is generally rectangular, but is provided with end cut-outs or slots 140 and side cutouts or slots 142 respectively receiving end flanges 160 and side flanges 162 extending down from movable base member 122. At the comers of fixed base member 120, there remain platforms 144 which threadably engage screws 138 with threads provided therein or in a threaded insert. Movable base member 122 is provided with a central opening 164 to receive the electrical device 114 and has a chamfer 166 at each end to facilitate finger gripping of the electrical device 114.
To accommodate the contact strips 116, similar to contact strip 16 described above, the fixed base member is provided with a plurality of recesses 118 in the edges thereof which face the side flanges 162 FIG. 9). The recesses 118 are spaced to match the spacing of male connectors 112, and are separated by integral spacers 146 which electrically insulate the contact strips 116 from one another. In each recess 118, the fixed base member 120 has a ledge and an aperture 128 corresponding to ledge 30 and aperture 28 described above. The other end of contact strip 1 16 is accommodated in movable base member 122 by means of recesses 168 therein which are aligned with recesses 118 and bounded by overhanging flange 136 and lateral spacers aligned with spacers 146 to ensure electrical separation of the contact strips 116.
The socket 100 illustrated in FIGS. 5-9 is typically mounted on a circuit board or the like with connections made to the portions 116.1 of the respective contact strips. To insert an electrical device 114 in the socket, the screws 138 are positioned so that the movable base member 120 is spaced away from the fixed base member 120 to put contact strips: 116 in relaxed position with the cavities 124 thereof opened to receive connector pins 112. The connector pins 112 are inserted with minimal force into the opened cavities 124. Screws 138 are then rotated to bring fixed and movable base members 120 and 122 closer togetherto thereby simultaneously deform the contact strips 1 16 with consequent electrical contact and film wiping action. When contact is completed, the screws 138 serve as means to hold the contact strips 116 in deformed position for as long as it is desired that contact be made. Removal of the electrical device 114 is accomplished by rotating screws 138 to separate base members 120 and 122. The contact strips 116 return to their relaxed position and the connector pins 112 can be freely removed therefrom.
FIG. 10 illustrates yet another embodiment of the invention, a connector device 200 which comprises a fixed base member 220 forming a recess 218 which accommodates a deformable contact strip 216. As illustrated, base member 220 is substantially U-shaped, with opposed walls 232 and 234 confining the contact strip 216. The contact strip 216 differs from contact strips 16 and 116 in that it has its connector portion 216.1 in line with the portion 216.22 which rests against wall 232, omitting an offset portion such as portion 16.21 of FIGS. 1-4.
The free end 216.41 of the contact strip 216 is confined under an overhanging flange 236 of a member 222. The member 222 is provided with a snap-tang fastener 238 which is receivable in an undercut slot 239 provided in base member 220, the interfitting fastener 238 and slot 239 being positioned to lock together when the contact strip 216 has been deformed to make electrical contact with connector pin 212 of electrical device 214. It should be apparent that the modifications illustrated in FIG. 10 respecting base member construction, contact strip construction, and construction of the means to hold the contact strip in deformed position, could be substituted for their respective counterparts in the device 10 and socket 100 illustrated in FIGS. 1-9.
FIGS. 11 through 14 illustrate a printed circuit card connector 300 using minimal insertion force connectors according to the invention. The device is adapted to make electrical connection with a printed circuit card 314 which has provided-therein a plurality of surface contacts 312 on both sides of the card 314 along one edge thereof. The surface contacts 312 are connected to various circuit items on card 314 and are usually provided by printed circuit techniques. The connector device 300, typically mounted on a circuit board B, comprises a fixed base member 320 and a movable base member 322 fastened thereto by means of jack screws 338 for travel toward and away from the fixed base member 320. The movable base member 322 is provided with a central opening 364 to receive the card 314 and has an overhanging flange 336 at opening 364. A plurality of contact strips 316, one for each surface contact 312, are mounted between flange 336 and fixed base member 320, the contact strips 316 being separated from one another by spacers 346 integrally formed with fixed base member 320. The spacers 346 extend into central opening 364 and have rounded upper ends 347 to help guide the printed circuit card 314 therein. Each contact strip 316 has a connector portion 316.1 extending through a hole provided in fixed base 320, an offset portion 316.21 to secure the contact strip against fixed base member 320, a compressible portion 316.3, and a curved contact portion 316.4 whose end fits underneath flange 336. Portions 316.3 and 316.4 of contact strip 316 function in a manner similar to portions 16.3 and 16.4 of the contact strip 16 described above, these portions changing shape when deformed lengthwise so as to develop a wiping electrical contact between contact area 326 thereof and the surface contacts 312 of card 314. Use of card connector 300 is similar to use of the socket 200 described above: To insert a card 314, screws 338 are positioned as in FIG. 12 so that fixed and movable base members 320 and 322 are separated and the contact strips 316 are relaxed to freely admit the card 314 therebetween. With the card in place, screws 338 are tightened to lengthwise deform the contact strips 316 and bring about the desired electrical contact with the surface contacts 312 of the card, as in FIG. 13. Removal of a card 314 is accomplished by reversal of the above steps.
Instead of using screws 338 as shown in FIGS. 11 through 14, a camming means may be used instead. FIG. 15 illustrates a portion of a card connector similar to that of FIGS. 1 1 through 14 modified to substitute a camming means 350 for the screws 338. The camming means 350 comprises a pin 352 secured to fixed base member 320 and extending through a hole provided in movable base member 322. Rotatably mounted on crossbar 354 at the top of pin 352 is a camming lever 356 with a camming surface 358 bearing against the surface of movable base 322 to urge it toward fixed base 320 as lever 356 is rotated, the surface 358 having a flat 359 to lock cam lever 356 in a position corresponding to deformation of the contact strips 316.
What is claimed is:
1. A connector device for making electrical contact with a male connector element, characterized by low insertion forces imposed on said male element, comprising means forming a cavity into which said male connector element can be inserted freely; said cavity forming means including an elastically deformable contact strip of conductive material positioned along one side of said cavity, said contact strip having a first curved portion forming a first contact area facing an inserted male element, said curved portion tending to expand across the cavity toward said male element to exert a force against said male connector element as said contact strip is deformed in a lengthwise direction, said strip further having a compressible portion adjacent said curved portion which contracts as said strip is deformed in a lengthwise direction, thereby wiping said first contact area along said inserted male connector element, said strip further having a second curved portion forming a second contact area positioned to contact substantially the entire inserted portion of said male connector element on the side opposite said first contact area; and
means movable to deform only said first curved portion and said compressible portion of said contact strip in a lengthwise direction without deforming said second curved portion thereof in a lengthwise direction, thereby to expand said first contact area across the cavity to exert a contact force against said male connector element and to wipe said first contact area therealong, thereby to make electrical contacts with said connector element at said first and said second contact areas.
2. A connector device according to claim 1 further comprising means to hold said movable means with said contact strip in deformed position, thereby to maintain electrical contacts with said male connector element.
3. A connector device according to claim 1 wherein said cavity forming means further includes a fixed base member receiving said contact strip, and
wherein said means movable to deform the contact strip includes a movable base member having a portion securing an end of said contact strip; and means for holding said fixed and movable base members with said contact strip in deformed position thereby to maintain said electrical contacts.
4. A connector device according to claim 3 wherein said fixed base member and said movable base member have parallel walls between which said male connector element and said contact strip are received; and
said portion of said movable base member which secures said contact strip comprises a lip extending from the parallel wall formed by said movable base member, said lip being secured to said first curved portion of the contact strip.
5. A connector device according to claim 1 wherein said first curved portion and said compressible portion of the contact strip together have a substantially S- shaped configuration, the lower end being secured by said cavity forming means, the upper end thereof being secured by said movable means and being moved towards the lower end thereof during lengthwise deformation.
6. A connector device according to claim 1 wherein said cavity forming means comprises a fixed base portion and wherein said second curved portion with said second contact area is secured in said fixed base member so that said second contact area is resiliently movable in a lateral direction when said movable means deforms said contact strip.
7. A connector device according to claim 1 wherein said contact strip further comprises a portion extending substantially in the direction of said male connector element for attachment to other electrical devices.
8. A low insertion force socket for use with a device having a plurality of male connector elements comprismg:
means forming a plurality of cavities positioned to freely receive said male connector elements;
said cavity forming means including a plurality of elastically deformable contact strips each positioned along one side of a male connector element in a cavity;
each of said contact strips having a first curved portion with a convex first contact area facing an inserted male connector element, said curved portion tending to expand across the cavity toward said male connector element to exert a force against said male connector element as said strip is deformed in a lengthwise direction, said strip further having a compressible portion adjacent said curved portion which compresses as said strip is deformed in a lengthwise direction, thereby wiping said contact area along said male connector element, and each of said strips further having a second curved portion forming a second contact area positioned to contact substantially the entire inserted portion of said male connector element on the side opposite said first contact area;
means movable to simultaneously deform only said first curved portion and said compressible portions of each of said plurality of contact strips in a lengthwise direction without deforming said second curved portion thereof in a lengthwise direction, thereby to establish electrical contacts with said male connector elements; and
means for holding said movable means with said contact strips in deformed position, thereby to main tain electrical contacts established with said male connector elements.
9. A socket according to claim 8 wherein said cavity forming means comprises a fixed base member with a plurality of recesses therein to receive said contact strips, said fixed base member having spacer means separating recesses and electrically separating said contact strips, said movable means comprising a movable base member interfitting with said fixed base member and having a flange formed therein for holding said contact strip means for lengthwise deformation.
10. A socket according to claim 9 wherein said means for holding said movable means comprises means interengaging said fixed and movable base members.
11. A socket according to claim 8 wherein said plurality of male connector elements are aligned in a row, and wherein said cavity forming means comprises a fixed base member having a plurality of recesses to receive said contact strips, and wherein said movable means comprises a movable base member adjacent said fixed base member and having a lip overhanging said said contact strips have their first curved portions and their compressible portions substantially in an S-shaped configuration; and
said second curved portions are secured in said fixed base member so that said second contact areas are resiliently movable in a laterialdirection when said movable means deforms said contact strips. 13. A socket according to claim 11 wherein said contact strips further comprise a portion for connection with other electrical devices, said portions extending from said fixed base member substantially in the pattern of said plurality of male connector elements.
14. A method of establishing electrical contact with a male connector element, characterized by low insertion forces, comprising:
providing means forming a cavity into which said male connector element can be freely inserted;
providing alongside said male connector'element as part of said cavity fonning means an elastically deformable contact strip having a first curved portion with a first contact area facing one side of said male connector element, a compressible portion adjacent to said first curved portion which contracts when said contact strip is deformed in a lengthwise direction and a second contact portion having a second contact area facing the opposite side of said male connector element to contact substantially the entire inserted portion thereof;
inserting said male connector element in said cavity while said contact strip is relaxed; and
deforming only said first curved portion and said compressible portion of said contact strip in a lengthwise direction without deforming said second contact portion in a lengthwise direction, thereby to urge said first curved contact portion against said male connector element and to wipe it therealong and to urge said second contact portion against said male connector element to establish electrical contacts.
15. A method according to claim 14 further comprising holding said contact strip in deformed position to maintain said electrical contact.