US3218603A

US3218603A - Circuit board connector

Info

Publication number: US3218603A
Application number: US151237A
Authority: US
Inventors: Eugene F Sanislo
Original assignee: Burndy Corp
Current assignee: FCI USA LLC
Priority date: 1961-11-09
Filing date: 1961-11-09
Publication date: 1965-11-16
Anticipated expiration: 1982-11-16
Also published as: BE624609A; GB1020344A; DE1440797A1; DE1440797B2

Description

Nov. 16, 1965 E. F. sANlsLo CIRCUIT BOARD CONNECTOR 4 Sheets-Sheet 1 Filed Nov. 9. 1961 Nov. 16, 1965 E. F. sANlsLo 3,218,603

CIRCUIT BOARD CONNECTOR Filed Nov. 9, 1961 4 Sheets-Sheet 2 FIGB INVENToR. lf2/GENE SANzsLo ATTOR Y Nov. 16, 1965 E. F. sANlsLo CIRCUIT BOARD CONNECTOR 4 Sheets-Sheet 3 Filed Nov, 9. 1961 INVENTOR. EIGENE [Sams By/ AT ToRN Y Nov. 16, 1965 E. F. sANlsLo 3,218,603

CIRCUIT BOARD CONNECTOR Filed Nov. 9. 1961 4 Sheets-Sheet 4 INVENToR. fuer/vf FSArws Lo TORNEY United States Patent Otlce Patented Nov. 16, 1965 3,218,603 CIRCUIT BDARD CONNECTOR Eugene F. Sanislo, Norwalk, Conn., assignor to Burndy Corporation, a corporation of New York Filed Nov. 9, 1951, Ser. No. 151,237 2 Claims. (Cl. 339-176) This invention relates to electrical connectors and, more particularly, to electrical connectors for cards or boards having electrical components and circuitry thereon.

Circuit board connectors are Well known in the prior art. The boards have a plurality of spaced apart, parallel contact surfaces which are engaged by a plurality of mating, spaced-apart, parallel resilient contacts. These contacts are usually permanently mounted in the connector insulating body, and conductors are usually permanently connected thereto. Replacement of an individual contact is diicult, if not impossible.

The portion of the connector Contact which electrically engages the board contact surface is customarily formed in a resilient configuration to provide at least a minimum mechanical pressure on the board contact surface by the connector and thus to assure an adequate electrical connection therebetween. Too little pressure may permit an intermittent, noisy, or high voltage drop connection. This is of particular significance when Very low energy circuits or dry circuits operating at micro-volt and microampere levels are to be connected. This mechanical pressure is applied by each connector contact regardless of whether a conductor is connected to the contact or not. The Wear resulting from this pressure on the board contact surface and the connector contact is thus effected each time the board is inserted into or removed from the connector.

As a result of the current trend to miniaturization, it is necessary to provide a maximum of connector contacts in a minimum of both total volume and especially linear measure along the length of the leading edge of the board. Thus the connector contacts must be as small as possible and the spacing between adjacent contacts must be a minimum. Yet each contact must be accurately located so that it will adequately engage but one board contact surface `and no others. The fabrication and assembly of an optimum connector is exceedingly diicult.

It is, therefore, an object of this invention to provide a connector wherein both before and after a board is inserted into the connector each contact is individually insertable and removable from said connector, and wherein a plurality of conductors may be individually connected to and disconnected from an individual contact, thereby permitting the ready replacement or rearrangement of contacts and conductors.

Another object is to provide a connector wherein a connector contact to which no conductor is connected applies but a minimum pressure to the associated board contact surface; while a connector contact to which a conductor is connected applies a higher pressure, thereby reducing the wear caused by nonconnected contacts, yet providing adequate pressure by connected contacts.

A further object is to provide a connector wherein all conductors may be concurrently connected to their contacts after the circuit board has been inserted into the connector, and disconnected before the board is removed, thereby minimizing wear on all the board contact surfaces.

Still another object is to provide a connector of miniature design which can be economically fabricated and assembled.

These and other objects and features of this invention will become more apparent by reference to the following description taken in conjunction withvthe accompanying drawings, in which:

FIG. 1 is a partial front View of a connector embodying this invention;

FIG. 2 is a side view in section taken along line 2 2 of FIG. 1 showing the connector with circuit board and wire terminations installed;

FIG. 3 is a side View in section taken along line A-A of FIG. 1 showing the connector with its contact spring and without either a circuit board or Wire terminations installed;

FIG. 4 is a side view in section taken along line 2-2 of FIG. 1 with a circuit board installed but showing a wire termination being inserted and a wire termination being extracted;

FIG. 5 is a side view in section taken along line A-A of FIG. l showing only the connector body;

FIG. 6 is a side view in section taken along line B-B of FIG. l showing only the connector body; and

FIG. 7 is a side view of a polarizing key for use with the connector of FIG. l.

FIG. 8 is a side view of the polarizing key of FIG. 7 assembled to the connector body.

Referring to the drawings, it Will be seen that the connector 11 comprises a substantially rectangular solid shaped body 13 made of suitable insulating material, such as diallyl phthalate; a plurality of spring contacts 15 which may be bent up from round wire stock of a suitable conductive, yet resilient material, such as heat treated beryllium copper; and a plurality of conductor or Wire terminations 17 Which may be bent into an L-shaped cross-section from stamped ilat stock of a suitable conductive and rigid material, such as cartridge brass.

The connector body has a plurality of closely spaced apart vertical bores 19 therethrough, from its front, circuit board receiving face 21, to its rear, wire termination-receiving face 23. The bores are substantially rectangular in cross-section although several projections are formed onto the side walls thereof to constrict the bore. Into these bores 19 are inserted the contact springs 15. As shown in FIGURES 5 and 6, each bore has a right side wall 25, a left side Wall 27, a top wall 29 and a bottom wall 31.

A horizontal slot 33 is formed into the front face of the connector body and extends partially into all the vertical bores 19. The horizontal slot 33 is adapted to receive the circuit board 35.

Suitable mounting means, not shown, may be provided for the connector body, such as a pair of flanges on its ends which include holes for mounting bolts.

Circuit boards customarily have a plurality of spacedapart parallel, contact strips or surfaces 37, as shown in FIGURE 2, adjacent and perpendicular to the leading edge of the board which is inserted into the connector. These contact surfaces may be on one or both sides of the circuit board. It is desirable that the center-to-center spacing of the board contact surfaces and the connector contacts be identical and coincident.

The connector contact springs 15, best shown in FIG- URE 3, are formed in what is essentially a U shape with a medial rear portion 39. Each leg portion 41 and 43 of the U extends by two

reverse bends

45 and 47, and 49 and 51 into a Z shaped inward-going portion having three be bowed slightly to provide a two-

point contact surface

69 and 71, and 73 and 75 to engage the card contact sur faces 37.

As was previously mentioned, a plurality of bore side wall projections are provided to constrict the bore 19.

Continuous webs

77 and 79 are formed from the left sidewall 27 to the right sidewall 25 above and below the circuit board slot 33 to provide a closed entry which limits the` thickness of the board 35 which may be inserted into the slot 33. The rear surfaces 81 and 83 ofthe webs serve as front stops for the contact spring and prevent overi'nsertion of the contact spring 15 into the bore 19. The top and

bottom walls

29 and 31, respectively, together with the

webs

77 and 79, provide recesses 84 and 86, respectively, in which the

hooks

65 and 67 of the contact spring 15 are free to move vertically. A projection 85 extends horizontally from the vertical center of the right sidewall to constrict more than one half of the width of the bore 19. The front surface 87 of the projection 85 serves as a rear stop for the contact spring 15 by engaging the medial portion 39 of the contact spring. Al

pair of

projections

88 and 89 are also formed von the right side wall 25 above and below the board slot 33, respectively. These projections serve to space the contact spring 15 away from the right sidewall. The rear face 91 of the projection 89 extends somewhat further to the rear of the bore 19, and the projection 89 is closer to the bottom wall 31 than is the rear face 93 of the projection 88, which is further from the top wall 29. A similar, but reversed, pair of projections 95 and 97 are formed on the left sidewall. However, projection 95 differs from projection 97 by having a gradual or sloping rear cam surface 99 rather than an abrupt one. When the contact spring 15 is inserted into the bore 19 from its rear face 23 to the right of the projection 95, the cam surface 99, which is forward of the projection surface 87, serves to shift the spring leftwards to the center of the bore as the spring passes forward of the projection 85. By these projections, the contact spring is snap-locked in the forward portion of the bore 19. As may be best seen in FIGURE 3, the

inner legs

57 and 63 of the Z project into the board slot 33, and as seen in FIGURE 2, resiliently engage the board contact surfaces 37. The contact spring may be extracted by inserting a suitable tool, not shown, to deflect the medial portion 39 of the spring away from the surface 87 and then moving the spring towards the rear of the bore and out of the connector body.

Referring to FIGURES 4 and 1, it will be seen that the wire terminations 17 are formed with an L-shaped cross section, web 103 being the shorter leg of the L and slightly less in width than the width of the bore 19. The thickness ofthe longer web 105 is made equal to or slightly less than the thickness of the projection 88 or 97 to aid in centering the spring 15 within the bore. The rear end of each wire termination 17 is formed with a pair of U-shaped cross sections which are crimped over and into thewire 107; forward U section 109 grasps the bare wire 111 while rearward U section 113 grasps the insulation of the wire. Both sections are crimped into an elliptical cross section to minimize the total width of the wire plus termination. A forward portion 115 of the short web is struck up slightly to provide a detent which will engage a

shoulder

117 or 119 provided in top and bottom walls of the bore, respectively. As may -be seen in FIGURE 4, the wire terminations 17 may be inserted into the rear of the bore 19, short web 103 sliding between the top or

bottom bore wall

29 or 31 and the

outer leg

53 or 59 of the contact spring respectively, until detent 115 snaps into place forward of

shoulder

117 or 119. The long web 105 pasess to the side of the contact spring and assists the several bore projections in centering the contact spring in the bore. The' contact spring resiliently presses against the wire termination, pressing it against the top or bottom wall of the bore, and also maintains electrical connection with the spring. The release of the wire terminations is effected by disengaging the detent from the

bore shoulder

117 or 119, as by a tool 121 slid between the termination and the wall, and pulling the termination out of the bore, as by a projection 123 on the tool engaging a shoulder 125 on the termination 17. The wire termination may be inserted 4or extracted regardless of whether the board is inserted between the legs of the contact spring or not. The insertion of the termination 17 is polarized with respect to the bore 19 tothe vertical plane by the height of the longer web 105 being greater than the width of the bore, and forwardly and rearwardly within the vertical plane by either the rear surface 91 of projection 89, or the medial portion 39 of the Contact spring obstructing further insertion of the narrow web 103, if the narrower web is centrally directed with respect to the bore, rather than correctly outwardly.

It will be noted that the wire termination, when inserted, reduces the vertical distance available to the Z portion of the contact spring, thereby increasing its compression and thus the pressure it' will exert on the board contact surface 37. Thus, to achieve a high contact pressure and corresponding good electrical connection between the contact spring inner leg '57 or 63 and the re spective card contact surface 37, while providing, during; insertion and removal of the card, Va lower contact pressure and corresponding lower wear on the contact spring lleg and the card contact surface, it is merely necessary to insert the wire termination after the board is inserted, and to extract the terminations before the board is extracted. If desired, all of the Wire terminations may be seized by a single tool, `or mounted on a single back strip for concurrent insertion and extraction.

If desired, a polarizing key 127 such as is shown in FIGURE 7 may be utilized to block off individual bores in the connector. The key is substantially of U shape, having a medial reverse bend 129, and a pair of

upset detents

131 and 133 on

legs

135 and 137, respectively. The key may be inserted fromy the front of the connector,

legs

135 and 137 passing through and beyond the bore so that

detents

131 and 133 snap behind the rear surface of the connector body 13. If desired, shoulders, not shown, similar to

shoulders

117 and 119 may be formed in the` top and bottom walls of the bore to receive

detents

131 and 133. The width of the key is equal to or less than the width of the bore. The key is adapted to c0- operate with a mating slot cut into the leading edge of the cards. The legs of the key, projecting slightly to the rear of the connector, serve as an indication that no termination is to be inserted into that specific bore.

The invention has thus been described but it is desired to be understood that it is not confined to the particular forms or usages shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of the invention, and therefore the right' is broadly claimed to employ all equivalent instrumentalities coming within the scope of the appendent claims, and by means of which objects of this invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to obtain these objects and accomplish these results.

I claim:

1. An electrical connector for a circuit board having a plurality of side-by-side spaced-apart conductor surfaces disposed adjacent the leading edge of Vthe board, comprising: a connector body having a plurality of side-by-side spaced-apart channels extending therethrough and a transversely extending slot intersecting each of said channels for receiving the leading edge of said board therein; a plurality of contact springs each adapted to be inserted into one of said channels and each having a contact surface for resiliently engaging and applying a given pressure to a conductor surface on a circuit board inserted into said slot, wherein .a portion of each contact spring is resiliently compressed between a Wall of said channel and a conductor surface upon insertion of said circuit board; a plurality of insertable and removable wire termination members adapted to be inserted into the channels to electrically engage the contact springs therein for completing electrical paths between said circuit board conductor surfaces and external wire conductors, through said springs, each of said termination members being disposed between the wall of said channel and the corresponding contact spring to increase the compression of said spring.

2. The electrical connector of claim 1 wherein said channel wall includes a shoulder, and said Wire termination member includes a detent portion adapted to engage said shoulder to retain said termination member within 6 said channel such that said detent may be disengaged by further compressing said spring portion.

References Cited by the Examiner UNITED STATES PATENTS 2,457,703 12/1948 Merkel 339-150 2,640,970 6/1953 Falge et al. 339-217 X 2,793,354 5/1957 Heimbach 339-198 2,911,612 11/1959 Jackson et al. 339-176 2,983,896 5/1961 Gilbert 339-176 X 3,024,436 3/1962 Kirk 339-176 3,047,831 7/1962 Majewski 339-176 3,047,832 7/1962 Deakin 339-217 3,048,811 8/1962 Lock 339-176 JOSEPH D. SEERS, Primary Examiner.

ALFRED S. TRASK, Examiner.

Claims

1. AN ELECTRICAL CONNECTOR FOR A CIRCUIT BOARD HAVING A PLURALITY OF SIDE-BY-SIDE SPACED-APART CONDUCTOR SURFACES DISPOSED ADJACENT THE LEADING EDGE OF THE BOARD, COMPRISING: A CONNECTOR BODY HAVING A PLURALITY OF SIDE-BY-SIDE SPACED-APART CHANNELS EXTENDING THERETHROUGH AND A TRANSVERSELY EXTENDING SLOT INTERSECTING EACH OF SAID CHANNELS FOR RECEIVING THE LEADING EDGE OF SAID BOARD THEREIN; A PLURALITY OF CONTACT SPRINGS EACH ADAPTED TO BE INSERTED INTO ONE OF SAID CHANNELS AND EACH HAVING A CONTACT SURFACE FOR RESILIENTLY ENGAGING AND APPLYING A GIVEN PRESSURE TO A CONDUCTOR SURFACE ON A CIRCUIT BOARD INSERTED INTO SAID SLOT, WHEREIN A PORTION OF EACH CONTACT SPRING IS RESILIENTLY COMPRESSED BETWEEN A WALL OF SAID CHANNEL AND A CONDUCTOR SURFACE UPON INSERTION OF SAID CIRCUIT BOAR; A PLURALITY OF INSERTABLE AND REMOVABLE WIRE TERMINATION MEMBERS ADAPTED TO BE INSERTED INTO THE CHANNELS TO ELECTRICALLY ENGAGE THE CONTACT SPRINGS THEREIN FOR COMPLETING ELECTRICAL PATHS BETWEEN SAID CIRCUIT BOARD CONDUCTOR SURFACES AND EXTERNAL WIRE CONDUCTORS, THROUGH SAID SPRINGS, EACH OF SAID TERMINATION MEMBERS BEING DISPOSED BETWEEN THE WALL OF SAID CHANNEL AND THE CORRESPONDING CONTACT SPRING TO INCREASE THE COMPRESSION OF SAID SPRING.