US3926496A

US3926496A - Connector receptacle

Info

Publication number: US3926496A
Application number: US435416A
Authority: US
Inventors: Carl Occhipinti
Original assignee: Bunker Ramo Corp
Current assignee: Amphenol Corp
Priority date: 1972-05-05
Filing date: 1974-01-22
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16
Also published as: GB1432606A; CH558629A; FR2183829A1; FR2183829B1; AU5475673A; NL7306198A; CA1014631A; JPS4967189A; DE2322596A1

Abstract

A receptacle for flat circuit bearing elements such as printed circuit boards, which receptacle has an elongated one-piece body of insulating material with a long, narrow slot for insertion of the circuit bearing element, a plurality of adjacently spaced, electrical contacts mounted adjacent at least one longitudinal side of the slot partially under a protective cover and adapted for connection with complementary contacts on the circuit bearing element, the adjacent contacts in the body having terminal portions extending from the bottom of the body which are both longitudinally and laterally spaced apart, and a pair of oppositely disposed vertical uprights integral with the body and positioned adjacent to the opposite ends of the slot, one of the uprights having a reference surface for locating the circuit bearing element in a predetermined position in respect to the contacts in the body, and the other upright having a spring means for forcibly positioning the circuit bearing element against the reference surface for establishing said predetermined alignment.

Description

United States Patent [1 1 Occhipinti Dec. 16, 1975 [73] Assignee: Bunker Ramo Corporaation, Oak

Brook, Ill.

[22] Filed: Jan. 22, 1974 [21] Appl. No.: 435,416

Related U.S. Application Data [63] Continuation of Ser. No. 250,710, May 5, 1972,

Guides, 6-1963, pp. 96 & 97.

Primary Examiner-Joseph l-l. McGlynn Attorney, Agent, or FirmFred Fisher; F. M. Arbuckle [5 7] ABSTRACT A receptacle for flat circuit bearing elements such as printed circuit boards, which receptacle has an elongated one-piece body of insulating material with a long, narrow slot for insertion of the circuit bearing element, a plurality of adjacently spaced, electrical contacts mounted adjacent at least one longitudinal side of the slot partially under a protective cover and adapted for connection with complementary contacts on the circuit bearing element, the adjacent contacts in the body having terminal portions extending from the bottom of the body which are both longitudinally and laterally spaced apart, and a pair of oppositely disposed vertical uprights integral with the body and positioned adjacent to the opposite ends of the slot, one of the uprights having a reference surface for locating the circuit bearing element in a predetermined position in respect to the contacts in the body, and the other upright having a spring means for forcibly positioning the circuit bearing element against the reference surface for establishing said predetermined alignment.

5 Claims, 9 Drawing Figures US. Patent Dec. 16, 1975 Sheet 1 of2 3,926,496

H" W if i W {mpg Sheet 2 of 2 US. Patent Dec. 16, 1975 CONNECTOR RECEPTACLE This is a continuation, of application Ser. No. 250,710, filed May 5, 1972, now abandoned.

BACKGROUND OF THE INVENTION With the miniaturization of electronic circuits, many circuits are now either printed, deposited or otherwise formed on either or both surfaces of a board or similar substrate. In use, these circuits bearing elements or boards are fitted into suitable receptacles and interconnected to other circuit elements to form complex electronic devices. In order to permit electrical contacts of the printed circuit board with the receptacle, a plurality of contact pads are provided adjacent at least one edge of the printed circuit board. The contact pads generally are in the form of strips of conductive material to which circuitry on the board can be connected.

With increased miniaturization, the receptacles in order to accept the multitude of contact pads on the circuit board have contained a number of small, closely grouped contacts. Each of the contacts is rigidly mounted in the receptacle, insulatively separated from adjacent contacts, and includes an engagement portion with some form of nose section adapted to electrically mate with one of the contact pads. A terminal portion is also provided on each contact for electrical connection to an external conductor.

In many instances, the receptacles have also included a cover plate of insulating material which extends over most of each contact except for the nose section and provides increased protection of the small, fragile contacts against damage or accidental electrical short circuiting. These connectors in the past have been commonly formed by fastening two or more individual parts together to form an insulative housing with the cover for the contacts.

Although these receptacles have been generally satisfactory, there have been some problems with their manufacture and performance. The manufacture of each of the individual parts required for the housing of insulating material has required a number of time-consuming operations. In some instances, the performance of the completed receptacles has been limited by variations in alignment of the individual parts in the housing. The alignment problem is particularly important in respect to receptacles having a multitude of small, closely grouped contacts since even a slight variation in their positions can result in connection problems with contact pads on the printed circuit board.

Another problem frequently associated with these receptacles is the limited accessibility of the terminal portion of each contact for connection to an external conductor. As the contacts within a limited space are increased in number, the engagement portions of adjacent contacts are often separated by only a few hundreds of an inch. Since each terminal portion is integral with the engagement portion, the space available between adjacent terminal portions also often becomes so limited that it is often difficult to connect an external conductor to each terminal portion. This problem is particularly significant when the individual terminal portions are wire wrapped with several turns of the external conductor wire, thus increasing the metallic perimeter of each terminal portion. When automatic equipment is utilized for wire wrapping, it also is necessary to include space between terminal portions for the insertions of a special wire wrapping tool. In some instances, this causes a reduction in wire size, terminal portions of the contact, or both.

It is therefore desirable to provide new protected entry receptacles in accordance with the description below.

SUMMARY OF THE INVENTION This invention is directed to a protected entry connector for flat circuit bearing elements such as printed circuit boards and more particularly to a receptacle constructed of a one-piece solid body of insulating material and having a plurality of electrical contacts positioned within the body with portions slightly exposed in the slot for engagement with complementary contact pads on the printed circuit board.

The receptacle is made of a one-piece body of nylon, hi-impact polystyrene or other suitable insulating material and is conveniently formed in a molding operation. Slot means are provided to expose at least a portion of the engagement portions of the electrical contacts and to receive a printed circuit board with contact pads, positioned for electrical connection with the contacts in the receptacle. Reference means are also provided to locate the printed circuit board in an exact predetermined position relative to the plurality of contacts in the receptacle. In addition, means are provided for mounting the individual contacts in the receptacle body such that their terminal portions extending from the bottom of the connector body are not all in a single plane.

More specifically, the receptacle has an elongated onepiece body of insulating material with a long, narrow slot extending vertically through the body and exposing a plurality of contact-receiving pockets spaced along at least one of the longitudinal sides of the slot. Adjacent pockets are separated by a barrier member with a lower portion having contact mounting surfaces for rigidly securing each contact in the body. The adjacent contacts are positioned in their respective pockets such that their terminal portions are also separated in a lateral direction with respect to the longitudinal side of the slot. Each contact is postioned so as to be adapted to make physical and electrical contact with a contact pad of the printed circuit element when the element is in the slot.

The body of dielectric material also includes a pair of oppositely disposed vertical uprights at the ends of the slot. One of the uprights has an upwardly projecting reference means with a surface adapted to receive the printed circuit board and to locate it in an exact predetermined position with reference to the contacts in the receptacle body. The other upright has a resilient means adapted to force the printed circuit board element against the reference surface of the opposite upright.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a top view of a protected entry receptacle utilizing the invention.

FIG. 2 is a side view of the receptacle illustrating the pair of opposed vertical uprights and terminal portions of the contacts.

FIG. 3 is a fragmental view of the bottom of the receptacle illustrating a portion of the slot and contact pockets exposed by the slot.

FIG. 4 is a cross-sectional view of the receptacle along line 44 of FIG. 2 and illustrates the positioning 3 of an electrical contact in a contact-receiving pocket.

FIG. 5 is a cross-sectional view of an adjacent pocket and contact member to that illustrated in FIG. 3, taken along line 5-5 of FIG. 2, and illustrates the positioning of the electrical contact to provide the desired separation of the terminal positions of the adjacent contacts.

FIG. 6 is an enlarged view of pockets illustrated in FIG. 3 prior to insertion of the metallic contacts.

FIG. 7 is a perspective view in cross section of receptacle illustrating the mounting of a contact in the receptacle.

FIG. 8 is a cross-sectional view of one vertical upright taken along line 88 of FIG. 1 illustrating the reference surface adapted to receive and position the printed circuit board element which serves as a reference means to locate the printed circuit board element.

FIG. 9 is a cross-sectional view of the opposite upright taken along line 99 of FIG. 1 illustrating the positioning of a spring which serves as a resilient means to locate the printed circuit board element.

GENERAL DESCRIPTION The receptacle is utilized with a flat circuit bearing element having contact pads adjacent at least one of its edges and comprises an elongated one-piece body of insulating material having a slot adapted to receive the edge of the element having the contact pads. The slot is open at the top of the body, extends vertically a dis tance into the body, and exposes at least one contactreceiving pocket containing an electrical contact. The body has an upper, inner surface adjacent to at least one of the longitudinal sides of the slot. The surface extends in a lateral and general horizontal direction away from the slot and serves as a protective cover for the contacts.

One or more contacts are mounted in the body below and are partially hidden by the cover. Each contact is disposed under the upper, inner surface of the pocket and has a section which extends a short distance into the slot for engagement with a complimentary contact pad on the circuit bearing element. When a plurality of contacts are disposed in a plurality of pockets along at least one side of the slot, the adjacent contacts are mounted in their respective pockets such that the terminal portions which extend below the body of insulating material are separated a greater distance than the separation of the engagement portions of the contacts.

The body also includes a pair of vertical uprights positioned adjacent the opposite ends of the slot. One of the uprights has a reference means adapted to receive and position the circuit bearing element in a predetermined location in the slot. The other upright has a resilient means adapted to receive the circuit bearing element and forcibly position it against the reference means. The connector receptacle. generally indicated at 10 in FIGS. 1 and 2, includes an elongated body portion 12 extending between a pair of oppositely disposed

vertical uprights

14 and 15 with opposed inner verti- Cally flat faces 16 and 17. Mounting

flanges

18 and 20 are ordinarily provided and these are illustrated as including screw holes 22 and 24, as is common practice in the connector art.

The connector body 10 includes a relatively long, narrow, deep slot 26 disposed between uprights l4 and 15 and arranged to receive the leading edge of a mating circuit board. As illustrated, slot 26 extends vertically through body 10 and includes longitudinal side 28 which is usually in the form of a flat, vertical wall.

Along the opposite longitudinal side 30 of slot 26 are arranged a plurality of contacts illustrated by individual contact 32 which has a yieldable ribbon-like blade portion 33 exposed by slot 26 (as more completely illustrated in FIG. 4). It is understood that a similar arrangement of contacts can also be positioned along side 28 of slot 26.

FIG. 3 is a fragmental view of bottom side 34 of body 12 and illustrates

contacts

32 and 36 disposed in

pockets

38 and 40 which are exposed by side 30 of slot 26. The individual pockets are disposed in a row along side 30 and are open at bottom side 34 to facilitate molding of body 12 and the insertion of the individual contacts into the pockets. As illustrated, pockets 38 and 40 are separated by barrier wall 41 which extends laterally between side 30 of slot 26 and outer body section 42.

Each of the metallic contacts consists of a single integral stamping of relatively thin sheet metal. In the preferred embodiment, they are formed of a nickel alloy, (nickel-copper-zinc) ribbon stock of about 0.0080.009 inches in thickness which has been goldplated to improve electrical conductivity.

As illustrated in FIGS. 4, 5, and 7 each contact is formed as a flat blade and includes a shank or mounting portion 46 to rigidly secure the contact in the body of insulating material, a terminal portion 48 for connection to a lead-in wire or other conductor by wire wrapping, soldering or the like, and a yieldable engagement portion 50 with a rounded bow 51 as a nose section for engagement with a contact pad on the circuit board element. Engagement portion 50 also includes upper arm 52 positioned against surface 54 of projection 56 which serves as a stop member to limit the distance that the engagement portion projects into slot 26. Lower arm 53 extends rearwardly away from slot 26 and is integrally interconnected with mounting portion 46. When a circuit board element is in the receptacle, engagement portion 50 is forced away from its normal biased position and therefore exerts a substantial force against the contact pad on the circuit board, thus causing good physical and electrical connection to be made between the contact and contact pad.

Frequently, a multiplicity of contacts are arranged in one row along slot 26. In the preferred embodiment, the slot is about 2 inches long and provides access to 40 contacts in a single row, each contact being about 0.02 inches wide at its blade and terminal portions. Under these conditions, the contacts are separated by about 0.03 inches. Since this distance would limit accessibility of the terminal portion of each contact for electrical connections, the mounting portions of adjacent contacts are also spaced laterally apart in respect to the longitudinal side 30 (FIG. 1) of the slot to substantially increase separation of the terminal portions.

FIG. 5 illustrates the mounting of contact 36 (FIG. 3) in pocket 40 and the separation between terminal portion 48 of contact 32 illustrated in FIG. 4 and terminal portion 59 of contact 36. In the receptacle described above, the terminal portions are separated laterally about 0. l 0 inches and those in the same row are separated by about 0.08 inches which are substantially greater than that (0.03 inches) for the engagement portions of the adjacent contacts.

The mounting portion of each contact is rigidly secured in mounting surfaces in the bottom portion of each of the adjoining barrier walls. FIG. 6 is an enlargement of a portion of FIG. 3 prior to insertion of the contacts and illustrates a lower view of

pockets

38 and 40. The pockets include T-shaped

recesses

58 and 60 with associated

cross members

61 and 62 which are laterally offset with respect to each other and provide surfaces for mounting the contacts. As illustrated, cross member 61 is disposed adjacent to side 30 of slot 26 with stem 63 sized to accept passage of engagement portion 50 during mounting of the contact extending laterally away from slot 26 a distance generally equal to the distance between the curved outer surface of the wide radius bend of bow 51 and the lower extremity of the engagement portion of contact 36 shown in FIG. 5. Recess 60 is positioned so that the cross member 62 is laterally separated from cross member 61 of recess 58 and stem 64 extends between cross member 62 and side 30 of slot 26. The distance of stem 64 is generally equal to the distance between outer curved surface of wide radius bend and the vertical supporting member of the mounting shank of contact 32 shown in FIG. 4. The distance between the cross members of recess 58 and recess 60 is generally equal to the separation between the tenninal portions of adjacent contacts.

During the mounting of the individual contacts in the bottom-loaded receptacle, a dummy circuit board is positioned in the slot and serves to force the engagement portion of each contact in a direction away from the slot so that the upper tip of the contact fits into the recess a distance beyond the abutment shoulder. If the contact were inserted in its unloaded condition without the presence of the dummy circuit board, the upper tip would be positioned too far into the slot and the tip would not fit into the recess. After the contact has been mounted, the dummy circuit board is removed and the upper tip engages the abutment shoulder, causing the engagement portion to be in a biased condition.

In FIG. 7, a contact similar to that shown in FIG. 5 is illustrated. The contact includes an engagement portion 70 with an upper arm 71 of bow 72 and a lower arm 73 extending downward at an incline from how 72. Integral with engagement portion 70 is a horizontal beam member 74 and a relatively rigid vertical support 75 of the contact mounting shank. As illustrated, the contact is a single, integral sheet metal stamping of relatively thin conductive metal. The support includes oppositely disposed coplanar flanges, one illustrated as 76, in the same plane as the web 77 of the support. Outer irregularly shaped surfaces, illustrated by barbed surface 78, are provided to bite into the opposite end surfaces 66 and 68 of cross member 58 (FIG. 6) and rigidly secure the contact in the pocket.

FIGS. 8 and 9 are cross sections of vertical uprights 14 and which act to guide and position the circuit board element into slot 26. Upright 14 includes a reference means illustrated as vertical surface 80 for locating the circuit board element in a predetermined position in respect to the horizontal positions of the contacts in slot 26. Spacing between contacts is only a small fraction of an inch and therefore, the exact positioning of the circuit board element is important to the proper functioning of the receptacle. Since upright 14 is an integral part of one-piece body 12, references surface 80 can be formed in a predetermined location on body 12 during the molding operation.

Upright 15 is provided with spring 82 which serves as resilient means to force the circuit board element against the reference surface 80 of upright 14 in FIG. 8. Upright 15 is further provided with side means illustrated by side wall 95 which laterally directs the circuit board element resiliently against spring 82 during insertion of the element between the

uprights

14 and 15 and when the element is positioned in the slot. As illustrated, spring 82 is shaped in the form of a bow 83 with downward extending

elongated arms

84 and 85. Arm 84 is positioned coextensive with the vertical side wall 86 of upright 15 and includes locking tab 87 in the notch 88 on the lower extremity of vertical side wall 86 of upright 15. Extending on the other side of the bow 83 is an elongated bowed arm in abutment engagement with a vertical shoulder 85 in abutment engagement with a vertical shoulder 89 in the base of the receptacle thereby resiliently restraining arm 85 from movement towards vertical face 16 of upright 14. It will be seen that the spring 82 is received in a recess of upright 14 and that the wall 95 on the upright includes guide means for aligning the board or circuit bearing element with the spring. Conveniently, before spring 82 is inserted, a dummy circuit board (not shown) is first positioned in the receptacle forcing the

elongated arms

84 and 85 closer together. When locking tab 87 of the spring 82 reaches notch 88 in vertical side wall 86, it locks into position. Upon removal of the dummy board, tip 90 of opposite elongated arm 85 forcibly moves against vertical shoulder 89 in the base of the receptacle.

In many instances the receptacle is polarized to accept the circuit board element in a predetermined orientation. Various portions of the receptacle can be formed to provide the desired polarization. To illustrate,

uprights

14 and 15 can include vertical surfaces of unequal lengths to mate with corresponding surfaces on the circuit board element. Slot 26 can include a stop member on one of its ends for the same purpose.

The foregoing description of the present invention is only illustrative of an exemplary form which the invention may take. Still other modifications and variations will suggest themselves to persons skilled in the art. It is intended, therefore, that the foregoing detailed description be considered as exemplary only and that the scope of the invention be ascertained from the following claims.

I claim:

1. A receptacle for a flat circuit-bearing element having contact pads adjacent at least one edge thereof comprising:

a one-piece body of insulating material having a slot for receiving the edge of the element having said contact pads, the slot having opposite ends and-a pair of vertical uprights integral with the body and positioned adjacent the opposite ends of the slot, one'of the uprights including reference means for receiving and locating the element in a predetermined position in the slot and the other upright including resilient means for receiving the element and forcibly positioning it against the reference means, said other upright including side means for laterally directing said element resiliently against said resilient means when said edge of said element is in said slot, said resilient means including a pair of spaced-apart arms and an upper bow joining said arms, one of said arms facing and resiliently restrained from movement towards said reference means, said resilient means including spring means having a lateral ear portion and said other vertical upright including a restraining abutment in juxtaposition with the ear portion for retaining the spring means in the upright.

2. A receptacle for a flat circuit-bearing element having a plurality of contact pads located between spaced edges of said element, the improvement comprising:

a one-piece body of insulating material having a slot for receiving the element and said contact pads, and an integrally formed reference means on said body for engaging one edge of said element to locate the element in predetermined position in the slot, a plurality of contacts carried by said body with each contact having a predetermined position along said slot for engaging a respective contact pad,

and resilient spring means carried by said body engaging the other spaced edge of said element and forcibly positioning the element in the slot against the reference meansto align each contact pad with a respective contact of said plurality of contacts, said resilient spring means including a pair of spaced-apart arms and an upper bow joining said arms, one of said arms in facing engagement with said other edge of said element and resiliently restrained from movement past a selected position towards said reference means, the other arm engaged with said body and held against movement from said element.

3. The receptacle of claim 2 wherein said body includes a vertical shoulder providing an abutment engaging said one arm for resiliently restraining said one arm.

4. A receptacle for a flat circuit bearing element having contact pads adjacent on at least one edge thereof comprising an elongated one-piece body of insulating material having a long, narrow slot extending vertically through the body with opposite longitudinal sides terminating at opposite ends of the slot and an upper inner surface extending laterally and generally horizontally from one of said sides as a protective cover and shaped to include a stop means, a pair of vertical uprights positioned integrally with the body at said ends of said slot and including reference means on one of said uprights to receive and locate the element in a predetermined position in the slot and the other said uprights including resilient means to receive the element and forcibly position it against the reference means with said reference and resilient means including opposed inner, vertically flat faces at said opposite ends of said slot, said resilient means includes spring means with a pair of spacedapart arms joined at an upper bow with one of the arms facing and resiliently restrained from movement towards said reference means and a lateral ear portion on said spring means, said vertical upright including a restraining abutment in juxtaposition with the ear portion for retaining the spring means in the upright, at least one of said longitudinal sides of said slot sides laterally exposing a plurality of adjacently spaced contactreceiving pockets disposed along said side below said protective cover and open at the bottom of the body, with alternate pockets having oppositely directed T- shaped cross sections at the bottom thereof, barrier means with contact-mounting surfaces extending laterally from said one longitudinal side and separating said pockets, and contact means including a plurality of flat blade-like contacts of sheet metal mounted in said pockets between the surfaces of the barrier means with terminal portions extending downwardly from and beyond the body with terminal portions of adjacent contacts being separated both longitudinally and vertically, each T-shape having a cross member adapted for mounting said contacts, and each of said contacts including an engagement portion with a rounded bow partially extending inwardly into said slot for engagement with said contact pads, said bow including an upper arm positioned against said stop means in said pocket for limiting movement of said bow inwardly into said slot and a lower arm extending rearwardly away from said slot to an end spaced apart from said cross member of said T-shape, said each contact also including a barbed pair of coplanar flanges retaining the contact in said cross member of said T-shape and integrally connected with said end of said lower arm, said contact means being adapted to make physical and electrical contact with the contact pad of said element when said element is in said slot.

5. The receptacle of claim 4 wherein said body includes a vertical shoulder providing an abutment for resiliently restraining said one arm.

Claims

1. A receptacle for a flat circuit-bearing element having contact pads adjacent at least one edge thereof comprising: a one-piece body of insulating material having a slot for receiving the edge of the element having said contact pads, the slot having opposite ends and a pair of vertical uprights integral with the body and positioned adjacent the opposite ends of the slot, one of the uprights including reference means for receiving and locating the element in a predetermined position in the slot and the other upright including resilient means for receiving the element and forcibly positioning it against the reference means, said other upright including side means for laterally directing said element resiliently against said resilient means when said edge of said element is in said slot, said resilient means including a pair of spaced-apart arms and an upper bow joining said arms, one of said arms facing and resiliently restrained from movement towards said reference means, said resilient means including spring means having a lateral ear portion and said other vertical upright including a restraining abutment in juxtaposition with the ear portion for retaining the spring means in the upright.

2. A receptacle for a flat circuit-bearing element having a plurality of contact pads located between spaced edges of said element, the improvement comprising: a one-piece body of insulating material having a slot for receiving the element and said contact pads, and an integrally formed reference means on said body for engaging one edge of said element to locate the element in predetermined position in the slot, a plurality of contacts carried by said body with each contact having a predetermined position along said slot for engaging a respective contact pad, and resilient spring means carried by said body engaging the other spaced edge of said element and forcibly positioning the element in the slot against the reference means to align each contact pad with a respective contact of said plurality of contacts, said resilient spring means including a pair of spaced-apart arms and an upper bow joining said arms, one of said arms in facing engagement with said other edge of said element and resiliently restrained from movement past a selected position towards said reference means, the other arm engaged with said body and held against movement from said element.

4. A recepTacle for a flat circuit bearing element having contact pads adjacent on at least one edge thereof comprising an elongated one-piece body of insulating material having a long, narrow slot extending vertically through the body with opposite longitudinal sides terminating at opposite ends of the slot and an upper inner surface extending laterally and generally horizontally from one of said sides as a protective cover and shaped to include a stop means, a pair of vertical uprights positioned integrally with the body at said ends of said slot and including reference means on one of said uprights to receive and locate the element in a predetermined position in the slot and the other said uprights including resilient means to receive the element and forcibly position it against the reference means with said reference and resilient means including opposed inner, vertically flat faces at said opposite ends of said slot, said resilient means includes spring means with a pair of spaced-apart arms joined at an upper bow with one of the arms facing and resiliently restrained from movement towards said reference means and a lateral ear portion on said spring means, said vertical upright including a restraining abutment in juxtaposition with the ear portion for retaining the spring means in the upright, at least one of said longitudinal sides of said slot sides laterally exposing a plurality of adjacently spaced contact-receiving pockets disposed along said side below said protective cover and open at the bottom of the body, with alternate pockets having oppositely directed T-shaped cross sections at the bottom thereof, barrier means with contact-mounting surfaces extending laterally from said one longitudinal side and separating said pockets, and contact means including a plurality of flat blade-like contacts of sheet metal mounted in said pockets between the surfaces of the barrier means with terminal portions extending downwardly from and beyond the body with terminal portions of adjacent contacts being separated both longitudinally and vertically, each T-shape having a cross member adapted for mounting said contacts, and each of said contacts including an engagement portion with a rounded bow partially extending inwardly into said slot for engagement with said contact pads, said bow including an upper arm positioned against said stop means in said pocket for limiting movement of said bow inwardly into said slot and a lower arm extending rearwardly away from said slot to an end spaced apart from said cross member of said T-shape, said each contact also including a barbed pair of coplanar flanges retaining the contact in said cross member of said T-shape and integrally connected with said end of said lower arm, said contact means being adapted to make physical and electrical contact with the contact pad of said element when said element is in said slot.