US3757284A

US3757284A - Socket type contact terminal

Info

Publication number: US3757284A
Application number: US00240532A
Authority: US
Inventors: W Klehm
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1972-04-03
Filing date: 1972-04-03
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04
Also published as: GB1397376A; NL7214000A

Abstract

A contact terminal of the socket type preferably formed from sheet metal stock in which the socket portion thereof is folded into channel formation to provide two side walls each similarly longitudinally bowed toward one another to bring their respective midsections into juxtaposition. Each side wall is dimpled in its midsection to form an inwardly directed protrusion which is in offset relation to the protrusion of the other side wall, the two protrusions extending across the space between the midsections and cooperating therewith to provide a constricted passage for receiving a contact member introduced therebetween. With this construction the gripping forces applied by the midsections of the two side walls are substantially greater than the forces opposing the introduction of a contact member therebetween, the gripping forces in the region of the midsections acting perpendicularly to the axial dimension of the socket and applying a squeezing pressure considerably greater than the force required to insert and withdraw the contact member, thereby preventing the latter from buckling when introduced thereinto.

Description

United States Patent [1 1 Klehm, Jr.

[451 Sept. 4, 1973 SOCKET TYPE CONTACT TERMINAL [75] Inventor: William G. Klehm,Jr.,Farmington,

Mich.

[73] Assignee: Burroughs Corporation, Detroit,

' Mich.

221 Filed: Apr. 3, 1972 211 Appl. No; 240,532

[56] References Cited UNITED STATES PATENTS 3,309,761 3/1967 Deakin 339/217 S X 3,226,669 12/1965 Lutz 339/258 P X 1,553,952 9/1925 Nero 339/191 R 3,192,498 6/1965 Rueh1emann.... 339/217 S X 3,227,927 1/1966 Parstorfer 339/17 CF X 3,192,445 6/1965 Evans 339/17 CF X Primary Examiner-Marvin A. Champion Assistant Examiner--William F. Pate, III

A tt0rney- Paul W. Fish, Ralzemond B. Parker et a1.

57 ABSTRACT A contact terminal of the socket type preferably formed from sheet metal stock in which the socket portion thereof is folded into channel formation to provide two side walls each similarly longitudinally bowed toward one another to bring their respective midsections into juxtaposition. Each sidewall is dimpled in its midsection to form an inwardly directed protrusion which is in offset relation to the protrusion of the other side wall, the two protrusions extending across the space between the midsections and cooperating therewith to provide a constricted passage for receiving a contact member introduced therebetween. With this construction the gripping forces applied by the midsections of the two side walls are substantially greater than the forces opposing the introduction of a contact member therebetween, the gripping forces in the region of the midsections acting perpendicularly to the axial dimension of the socket and applying a squeezing pressure considerably. greater than the force required to insert and withdraw the contact member, thereby preventing the latter from buckling when introduced thereinto.

6 Claims, 15 Drawing Figures Pmmww' saztnnr FIG. 2.

PAIENTEDSEP 4W 3.757. 284

SHEEI 2 0F 3 comm m CAVITY 58 ml a 94-- Pmiminw' 3.757. 284

sum 3 or 5 FIG. II.

SOCKET TYPE CONTACT TERMINAL CROSS REFERENCE TO A RELATED APPLICATION FOR PATENT Reference is made to applicants copending application for patent identified as Ser. No. 194,396, now U.S. Pat. No. 3,693,131 filed Nov. 1, 1971, and entitled a PROGRAMMABLE DUAL-IN-LINE PIN CONNEC- TOR FOR INTEGRATED CIRCUIT UNITS where the pin and socket connector illustrated in FIG. 1 herein is shown but not claimed in the aforesaid copending application.

FIELD OF THE INVENTION The invention relates generally to integrated circuit components and more particularly to a socket type connector for use in such art.

BACKGROUND OF THE INVENTION Electrical connectors having socket type sections for receiving and gripping a mating electrical contact member are of common knowledge and in widespread use. One of the problems associated with such connectors is the difficulty encountered in inserting the mating contact member and especially if it is of the thin blade type associated with integrated circuit units. Contact blades of this type are quite fragile and are likely to buckle as they are forced into the socket of the connector, and attempts to reduce the resistance to insertion also diminishes the gripping forces applied to complete the electrical connection. In view of these difficulties and problems, it is evident that an improvement is needed which will minimize the resistance to insertion on the one hand and increase the gripping forces providing the electrical connection on the other hand.

SUMMARY OF THE INVENTION It is accordingly an important object of the present invention to provide an improved socket type electrical connector for use with integrated circuit units and the like and so designed as to provide a substantially higher force for gripping an introduced contact member as compared with the force required to introduce such contact member thereinto.

Another important object of the invention is to provide an improved electrical socket type connector which is so constructed as to provide a gradually converging mouth leading to a constricted midsection area where counteracting forces grip an introduced contact member with substantially greater forces than those required for its introduction.

A further important object of the invention is to provide an improved electrical connector of the socket type which can be economically produced from flat metal stock to provide the aforesaid advantages.

In carrying out the objects of this invention, the electrical connector is so designed that when folded from a flat metal blank into a channel formation and the side walls thereof are further deformed toward one another there is produced an outwardly flaring mouth for guiding a contact member thereinto and a middle channel region which exerts a compressive force on a contact member introduced thereinto of a magnitude substantially greater than that required for the insertion of the contact member. To this end, the side walls of the socket are inwardly bowed to bring their respective midsections into juxtaposition and such midsections are provided with inwardly directed protrusions which extend across the space between the midsections and are disposed in offset relation to one another to provide the constricted passage into which the inserted contact member is received and gripped.

These and other objects, advantages and meritorious features of the invention will become more fully apparent from the following specification, appended claims and the accompanying sheets of drawings wherein:

BRIEF DESCRIPTION OF THE DRAWING FIGURES:

FIG. 1 is a perspective view of one embodiment of a pin and socket connector constructed in accordance with the present invention and illustrating its folded condition prior to inclusion in an integrated circuit unit;

FIG. 2 is a cross sectional view through an integrated circuit block of insulating material in the cavities of which connectors of the type illustrated in FIG. 1 are received and showing the reception of a lead from an integrated circuit unit in one of such connectors;

FIG. 3 is an endview of the socket portion of the connector of FIG. 1 taken along line 3-3 of the latter;

FIG. 4 is a sectional view taken along line 44 of FIG. 3;

FIG. 5 is a plan view illustrating the flat metal blank prior to the folding thereof to form the connector shown in FIG. 1;

FIG. 6 is a side view of the connector following the folding of the blank of FIG. 5;

FIG. 7 is a side view of the connector of FIGS. 1 and 6 after the connector is received in a cavity of the insulating block; 7

FIGS. 8, 9 and 10 are cross sectional views of the contact terminal taken along lines 8-8, 9-9, and 10-10 of FIG. 7 and illustrating the positions assumed the parts intersected by such lines when the terminal is installed in a cavity of a connector block;

FIG. 11 is a side elevation of an alternative form of contact terminal embodying the invention showing the same installed in a cavity of a block of insulating material;

FIG. 12 is a side elevation of the contact terminal of FIG. 11 but taken at an angle therefrom;

FIG. 13 is a cross sectional view taken along line 13-13 of FIG. 11;

FIG. 14 is a cross sectional view taken along line 14-14 of FIG. 11;'and

FIG. 15 is a fragmentary perspective view of the entrance portion of a cavity in the insulating block shaped to receive the contact terminal of the character illustrated in FIGS. 11 and 12.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION An electrical contact terminal constructed in accordance with this invention is illustrated in FIG. 1. Preferably, the terminal 20 is formed out of flat stock composed of electrically conductive material and folded upon itself, thereby to exhibit two main longitudinal sections, a channel-shaped, lead gripping portion generally indicated at 22 and a cylindrical post portion generally indicated at 24. The contact terminal is preferably manufactured by stamping and forming operations and in the process of its formation the base of the channel shaped portion is cut away as at 26 to form a longitudinal opening occupying most of the base of the channel-shaped socket as indicated in FIG. 6 and the post portion 24 is rolled upon itself sufficiently to bring the opposite edges into substantial abutment to form a sleeve 28 having a seam indicated at 30 in FIG. 6. In a typical use, the folded section 22 of the terminal is fitted into a recess or cavity 32 of an electrically insulating body such as the hardened plastic block 34 illustrated in cross section in FIG. 2. The cylindrical post section 24 will project beyond the block 34 for entrance into a complementary contact socket (not shown) which may be formed in a printed circuit board for this purpose.

The upper end of the folded section 22 of the terminal aligns itself with the upper narrower end of the cavity 32 in the block 34 into which it is fitted so that a mating contact member 36 may be slidably introduced thereinto as shown in the left cavity 32 of FIG. 2. As the socket section 22 of the terminal is introduced and fitted into its cavity 32 its shape is further modified by the walls of the cavity. In its initial form illustrated in FIGS. 1 and 6 the channel-shaped socket section 22 of the presently described embodiment of the invention has two slightly diverging

side walls

38 and 40. When the contact terminal is introduced into its selected cavity 32 of the insulated block 34, the walls of the cavity are so designed as to force the side walls of the socket 22 inwardly toward one another to assume in its final disposition in the cavity a substantially parallel relation to one another. When fully installed in the block, as illustrated by the left cavity 32 of FIG. 2, a thin strip lead or blade 36 from an integrated circuit unit 42 maybe introduced into the socket section 22 through the upper opened end thereof and sufficiently far enough to be grippingly engaged by the middle portion of the socket section 22.

A general description of one embodiment of the invention and a particular use thereof has been made. Other details of this embodiment will now be described with respect to FIGS. 6 and 10 inclusive. The initial fold of the socket section 22 produces a channel formation consisting of a base and the two diverging

side walls

38 and 40 as previously mentioned. Moreover,

the initial struck out area 26 of the blank illustrated in FIG. 5 produces a slightly converging but generally rectangular opening 26 in the base of the channel as il- 7 lustrated in FIGS. 1 and 6. The cutaway area 26 extends for the major part of the socket section 22 but terminates short of the upper and lower ends of the socket section to form upper and lower connecting

webs

44 and 46 respectively which form parts of the original base of the channel and are integrally joined to the

side walls

38 and 40 as is evident in FIGS. 1 and 6.

The two

side walls

38 and 40 of the contact terminal are also initially shaped at the time of fabrication so as to bring their respective middle portions into juxtaposition as shown in FIGS. 1 and 6. The result of such a bending of the

side walls

38 and 40 is to impart an inwardly bowed condition to each wall bringing the

midsection

48 and 50 of each

wall

38 and 40 closer together than any other portion of the walls as is evident in FIG. 6. The additional folding of the socket section 22 upon itself when installed in operating condition in a cavity of an insulated body such as 34 will force the

midsections

48 and 50 closer together and to assume a slightly spaced apart parallel relationship as illustrated in the sectional view of FIG. 8.

One important feature of the invention is the provision of inwardly directed bulges or protrusions formed on the inner surfaces of the

side walls

38 and 40 and particularly in the region of their midsections 48 and respectively. One such protrusion on midsection 48 is indicated at 52 and a protrusion on the other midsection 50 is indicated at 54. As illustrated in FIG. 5, these two protrusions are preferably formed on the blank prior to the folding thereof into the shape illustrated in FIG. 6, the two protrusions being indicated in FIG. 5 by the

same reference numbers

52 and 54 as appears in FIG. 6.

It-should be further noted that the two

protrusions

52 and 54 are not directly opposed to one another but instead are located on their respective midsections of the

side walls

38 and 40 so that they are offset from one another and preferably laterally of the whole contact terminal 20 and on opposite sides of its longitudinal axis. Also, it should be noted that each

such protrusion

52 and 54 is located along an edge portion of the side wall, one on the inner edge of the side wall 38 formed by the cutaway area 26 and the other on the outer edge of the side wall 40. Furthermore, each protrusion is generally conically shaped except that by virtue of its location on the edge of its associated side wall in the presently described embodiment its base does not occupy a full circle. The result is that when the contact terminal is further folded upon itself, as when placed in a cavity of an insulated block designed to receive the same, the two protrusions are located at the opposite ends of a narrow passage 56, as illustrated in FIG. 8, into which the outer end portion of a lead or blade 36 will be received and gripped by the side wall midsections when fully introduced thereinto.

In the presently described embodiment of the invention, the channel formation of the contact terminal 20 is formed by bending the same on two pairs of fold lines. One pair of fold lines is illustrated at the upper end of the blank in FIG. 5 and identified by the reference character 58, and the other pair is shown at the lower end of the opening 26 in the blank by the reference character 60. The fold lines of each pair extend parallel to one another but it is evident from a comparison of the two pairs of such lines in FIG. 5 that the distance separating the fold lines of pair 58 is smaller than that of the pair 60 with the consequence that the connecting

webs

44 and 46 are unequal in lateral extent as is evident in FIGS. 1 and 6. The result is that the overall formation of the socket section 22 of the contact terminal 20 has a slight convergence from the cylindrical post section 24 to its opposite end, thereby assisting in its insertion in a selected throughway or cavity 32-of the insulating block 34. It is also evident in FIG. 2 that each cavity 32 gradually diminishes in cross section upwardly from the base of the insulating block so that when the socket section 22 is introduced thereinto its side walls are progressively bent toward one another, eventually to bring the

midsections

48 and 50 thereof into the slightly spaced apart parallel relation exhibited in FIG. 8. FIGS. 9 and 10 also illustrate the parallel relation of other portions of the side walls of the socket section after the same has been fully received in a cavity 32 of an insulating block dimensioned to receive the same and perform this function.

FIGS. 11 to 15 illustrate a modification of the inven- I tion wherein in lieu of utilizing the interior formation of the cavity in which the contact terminal is received to bring the side walls into parallel relationship, the contact terminal itself is initially formed to provide and maintain this parallel relationship prior to insertion in a cavity. With more specific reference to FIGS. 11 to 15, the contact terminal 62 of this modification is generally similar to that of the first described embodiment of the invention including a socket section 64 joined to a cylindrical post section 65, both of which may be formed and shaped from a blank of flat stock metal as previously described in connection with the first modification of the invention. The socket section 64 is composed of a pair of

side walls

66 and 68 which are generally similarly shaped with respect to one another and are inwardly bowed toward one another as shown in FIG. 11 to bring their respective mid portions into juxtaposition as is evident from FIG. 14. The midsection of each side wall is provided with a bulge or protrusion which projects toward the other side wall for contact therewith, but as in the case of the first described embodiment the two protrusions are offset laterally with respect to one another to provide a narrow passage for receiving a mating contact member 36. The protrusion associated with the side wall 66 is indicated at 70, and similarly the protrusion carried by the side wall 68 is indicated at 72. The cylindrical post section 66, how ever, is formed of two complementary half sections having two substantially abutting seams 74.

It is evident from the several Figures illustrating the second embodiment of the invention that the two

side walls

66 and 68 of the socket section 64 terminate differently at their upper and lower ends from the embodiment previously described. In the presently described form of the invention, the upper ends of the two side walls are reversely bent upon themselves to provide, as in the case of the side wall 66, a downwardly extending portion 76 and likewise in the case of the side wall 68 a downwardly extending portion 78. Integrally joined to these downwardly directed

extensions

76 and 78 are connecting bands or

webs

80 and 82 as shown in FIG. 14 which together with the downwardly turned

extensions

76 and 78 encircle the upper end of the socket section as illustrated in this figure. Moreover, one of the webs, such as 80, has a greater length than its complementary web 82. The terminal portion 84 of the longer web 80 is folded about the downward extension 78 of the side wall 68 as shown in FIGS. 12 and 14.

Constructed in this fashion, the upper end of this socket is thus enclosed within a ring formed by the

downward extensions

76 and 78 of the side walls and the

web connections

80 and 82 with the consequence that this end portion of the socket is restrained from changing its shape and especially by any outward displacement of the side walls away from one another which would adversely affect the squeezing pressure exerted by their midsections on an introduced contact member 36.

The lower end of the socket section 64 of the contact terminal 62 is generally similarly formed like the upper 'end previously described. Each

side wall

66 and 68 is 86 and 88 and the overlapping portion 90 to hold the base ends of the side walls from any outward displacement that may occur which would adversely effect the squeezing pressure exerted by their midsections upon an introduced contact member represented at 36.

In addition to displaying a side elevation of the contact terminal 62. FIG. 11 shows the mounting thereof in a throughway or cavity 92 of an insulating block 94 which may be formed of hardened plastic material. In such a mounting arrangement, the cavity 92 may be approximately rectangular in shape as illustrated in the sectional view of FIG. 15 and having a slightly wider dimension in one direction at its lower end to accept the lower wider end of the socket. To accommodate the overlapping

portions

84 and 90 associated with the upper and lower ends of the socket section, the cavity is provided with acorner groove 96 running the length thereof and being of such a dimension as to accept the width and depth of the overlapping portions as is evident by the dotted representation of the groove in FIG. 11. The upper end of the cavity 92 is provided with a reduced opening or mouth 98 formed in the plastic body into which the mating contact member 36 is initially introduced before entering the mouth of the socket section 64.

Both embodiments of the invention employ chamfered projections or lances to assist in holding the socket section of the connectors against accidental separation from the cavities of the plastic body into which they are inserted. In the first described embodiment of the invention, such projections are illustrated at 100 and 102 in FIGS. 1 and 3. In the second described embodiment, such lances are illustrated at 104 at the base portion of the socket section 64.

In the operation of the two embodiments of the invention, it is evident that upon introduction of a mating contact member 36, into the socket 64, the thickness of the contact member is greater than the distance separating the middle portions of the inwardly bowed side walls of the socket. The usual practice at the present time is to make the leads of the integrated circuit units of a thickness of 10 mils. Accordingly, to gain the desired results with the use of the present invention, the

minimal separation of the two side walls of either embodiment is a distance of 5 mils, the offset protrusions in either case acting to maintain this minimal distance. The result is that when the contact lead or blade 36 of an integrated circuit unit is projected into the midsection of the socket of either embodiment, it will deflect the midsections of the side walls away from one another by approximately Zi mils. Each side wall may be considered as a simple supported beam held from outward deflection at its opposite ends while the middle portion of its arched configuration is capable of being deflected in an outward direction by the introduced lead 36. Supported in this fashion, each beam furnishes a substantially greater resistance to outward deflection than would a cantilever type supported beam.

Performing in this manner, the two

side walls

38 and 40 of the first embodiment and the

side walls

66 and 68 of the second embodiment may be constructed to exert a pressure at their respective midsections of from 200 to 400 grams in the direction toward one another and perpendicular to the path of travel of an inserted lead 36. This squeezing pressure on the lead is substantially greater than such gripping pressures heretofore employed for such type of connectors, the latter usually being in the range of 30 to 50 grams. Moreover, it is evident that the bowed side walls of either embodiment provide a gradually converging path for guiding the inserted lead 36 to the midsection thereof. In the presently disclosed embodiments of the invention, the entering lead 36 engages the side walls of the socket for a distance of approximately 50 mils before the narrow midsection of the socket is reached during which time the lead gradually wedges each side wall a distance of approximately 2% mils. This mechanical advantage of about to 1 enables the lead introducing forces to be substantially less than the gripping forces applied by the midsections of the side wall on the introduced contact member, thus preventing the leads from being deformed or buckled as they are advanced into the sockets.

As previously mentioned, the inwardly directed protrusions 52-54 and 70-72 serve to provide and maintain the minimal distance separating the midsections of the side walls of the socket, this distance preferably being about one-half the thickness of the introduced contact member. In addition, these protrusions are laterally spaced apart from one another and function to engage the opposite sides of an introduced lead 36 and guide the same centrally, longitudinally of the side walls. To this end, the rounded bases of the protrusions act to funnel the advancing end of the lead therebetween and thus prevent the lead from straying aside.

While two particular embodiments of the invention have been shown and described, it will be understood, of course, that it is not desired that the invention be limited thereto since modifications may be made, and it is, therefore, contemplated by the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An electrical connector assembly including, in combination:

a socket member in the form of a U-shaped channel of resilient metal to be received in a throughway of a supporting electrically insulating receptacle, the base of the channel being omitted from. the side walls along an intermediate portion of the length of the member, thus leaving a pair of spaced webs along the base of the channel between said side walls, the side walls of the channel being bowed inwardly along said intermediate portion and providing, within the channel shape, converging contact surfaces, at contact terminal member of thin blade-shaped formation insertable lengthwise into the mouth of the socket member formed at one end thereof, similar rounded protrusions bulged out from at least one inner face of said bowed side walls and disverse dimension aproximately half the thickness of such contact member. 2. An electrical socket for receiving a contact member and comprising a sheet metal socket made from a single blank longitudinally folded to provide a channelshaped formation comprised of a base and a pair of side walls, said socket having a struck-out section along the base which terminates short of the upper and lower ends of the socket to form upper and lower connecting webs integrally joined to the side walls,

I said pair of side walls being bowed inwardly toward one another to bring their respective midsections into juxtaposition, the midsection of each of said side walls being dimpled to form an inwardly directed protrusion which is offset in laterally displaced relation to the similar protrusion formed on the other side wall of the socket, one such protrusion being located at the inner edge of its side wall formed by the struck-out section of the socket and such other protrusion being located at the opposite outer edge of its side wall, the two protrusions cooperating with one another in the operating condition of the socket to maintain the midsections of said pair of side walls in slightly spaced apart parallel relation to one another, and

said protrusions being rounded to engage the side edges of an introduced mating contact member and guide the same therebetween.

3. A contact terminal of the socket type having a folded section exhibiting an open-ended channel shaped formation thereby to provide a pair of confronting side walls, the side walls being bowed inwardly toward one another to bring the midsections thereof into juxtaposition, and protrusions carried on the midsection of at least one of said side walls and extending toward the other side wall, said protrusions being laterally spaced apart sufficiently to permitthe passage of a contact member therebetween which is introduced through the open end of the channel formed by the pair of side walls,

said bowed side walls being resiliently arched toward one another but being maintained in spaced-apart relationship by the abutment of each protrusion against the side wall opposite to that upon which it is carried.

4. The contact terminal as recited in claim 3 wherein the protrusions are generally conically shaped and integrally joined at their bases to the side wall upon which they are carried.

5. The contact terminal as recited in claim 4 whrein the protrusions are displaced from one another transversely of the longitudinal dimension of the side walls and cooperate with one another and the side walls to form a narrow gap for receiving a mating contact member introduced into the channel of the contact terminal.

6. An electrical socket-type connector having the socket thereof in the form of a channel of electrically conductive resilient material adapted to be received in a cavity of a supporting receptacle of electrically insulating material, the base of the channel being omitted from the side walls along an intermediate portion of the length of the member thus leaving a pair of spaced webs along the base of the channel between said side walls, the side walls of the socket between said pair of spaced webs being resiliently arched toward one another inwardly along said intermediate portion and promation of each side wall from its initial flat condition,

said protrusions being cooperable with the side walls to form a narrow opening extending crosswise to the longitudinal axis of the socket for receiving a contact terminal member introduced into the mouth of the socket, said protrusions being rounded on the sides thereof facing one another and cooperating with one another to engage the leading end of the contact terminal member introduced into the mouth of the socket to guide the same therebetween.

I l l

Claims

1. An electrical connector assembly including, in combination: a socket member in the form of a U-shaped channel of resilient metal to be received in a throughway of a supporting electrically insulating receptacle, the base of the channel being omitted from the side walls along an intermediate portion of the length of the member, thus leaving a pair of spaced webs along the base of the channel between said side walls, the side walls of the channel being bowed inwardly along said intermediate portion and providing, within the channel shape, converging contact surfaces, a contact terminal member of thin blade-shaped formation insertable lengthwise into the mouth of the socket member formed at one end thereof, similar rounded protrusions bulged out from at least one inner face of said bowed side walls and disposed in offset relation to one another for guidingly engaging the leading end of the terminal member introduced into the mouth of the socket member, said protrusions being located midway of the length of said bowed side walls and on opposite sides of the longitudinal axis of the socket member of the connector, and said protrusions acting to space the bowed side walls from one another and cooperating therewith to form a narrow opening having a longitudinal dimension approximating the width of the contact terminal member insertable thereinto and a transverse dimension aproximately half the thickness of such contact member.

2. An electrical socket for receiving a contact member and comprising a sheet metal socket made from a single blank longitudinally folded to provide a channel-shaped formation comprised of a base and a pair of side walls, said socket having a struck-out section along the base which terminates short of the upper and lower ends of the socket to form upper and lower connecting webs integrally joined to the side walls, said pair of side walls being bowed inwardly toward one another to bring their respective midsections into juxtaposition, the midsection of each of said side walls being dimpled to form an inwardly directed protrusion which is offset in laterally displaced relation to the similar protrusion formed on the other side wall of the socket, one such protrusion being located at the inner edge of its side wall formed by the struck-out section of the socket and such other protrusion being located at the opposite outer edge of its side wall, the two protrusions cooperating with one another in the operating condition of the socket to maintain the midsections of said pair of side walls in slightly spaced apart parallel relation to one another, and said protrusions being rounded to engage the side edges of an introduced mating contact member and guide the same therebetween.

3. A contact terminal of the socket type having a folded section exhibiting an open-ended channel shaped formation thereby to provide a pair of confronting side walls, the side walls being bowed inwardly toward one another to bring the midsections thereof into juxtaposition, and protrusions carried on the midsection of at least one of said side walls and extending toward the other side wall, said protrusions being laterally spaced apart sufficiently to permit the passage of a contact member therebetween which is introduced through the open end of the channel formed by the pair of side walls, said bowed side walls being resiliently arched toward one another but being maintained in spaced-apart relationship by the abutment of each protrusion against the side wall opposite to that upon which it is carried.

6. An electrical socket-type connector having the socket thereof in the form of a channel of electrically conductive resilient material adapted to be received in a cavity of a supporting receptacle of electrically insulating material, the base of the channel being omitted from the side walls along an intermediate portion of the length of the member thus leaving a pair of spaced webs along the base of the channel between said side walls, the side walls of the socket between said pair of spaced webs being resiliently arched toward one another inwardly along said intermediate portion and providing, within the channel shape, converging contact surfaces for guiding a contact terminal member inserted lengthwise into the mouth of the socket formed at one end thereof, similarly shaped protrusions carried on the inner face of the midsection of at least one of said bowed side walls and disposed in offset relation to one another transverse to and on opposite sides of the longitudinal axis of the channel of the socket, the protrusions each forming an integral part of the side wall on which it is carried and being formed by a deformation of each side wall from its initial flat condition, said protrusions being cooperable with the side walls to form a narrow opening extending crosswise to the longitudinal axis of the socket for receiving a contact terminal member introduced into the mouth of the socket, said protrusions being rounded on the sides thereof facing one another and cooperating with one another to engage the leading end of the contact terminal member introduced into the mouth of the socket to guide the same therebetween.