CA1133600A - Contact assembly for printed circuit board - Google Patents

Abstract

ABSTRACT

A new and improved contact assembly for use with printed circuit boards has first and second contact members which respectively define first and second insulation dis-placing slots which are aligned in spaced relation along a first axis. A third contact member defines a third insul-ation displacing slot and biasingly disposes the third slot along a second axis which is offset from the first axis. The third contact member is movable to dispose the third slot along the first axis in the course of insertion of an electrical con-ductor in the assembly. The contact assembly improves the electrical connection between conductor and contact by forcing the conductor to follow a tortuous path during insertion.

Description

~33600 -~'lELD OF TH~: INVENTION
___ The present invention relates to electrical connector ~nd contact assemblies, and, more particularly, to such assemblies which are especially adapted for use with printed circuit boards BACKGROtlND OF THE INVENTION
One of the earliest devices for c~nnecting an electri-cal cable to a surface conductor of a printed circuit board em~
ployed 2 socket connector adapted for attachment to a pin or header ';
soldered into the printed circuit board. These early devices were both expensive ana time-consuming to install.
More recently, connector assemblies have been developed which overcome the problems and disadvantages of the early devices discussed above. For instance, Teagno et al. ~.S. Patent No.
3,744,009 describes ana illustrates a more recent type of printed circuit board connector assembly which utilizes rigid leg members i attached to a stationaxy housing, each of the leg members regis-tering with a corresponding aperture in a pxinted circuit board for mounting the connector assembly thereon. Due to the rigidity of the leg members, the housing must be slid along the printed ., .
circuit board to properly latch the housing in position. Sliding the housing along the printed circuit board is undesirable, because a contact carried by the housing rubs against a surface conductor on the printed circuit board, thereby causing undue wear of the surface conductor and a resulting rapid deterioration of the elec-trical juncture between the contact and the surface conductor.
In order to reduce such wear, the connector assemblies disclosed in Narozny U.S. Patent No. 4,009,921 were developed by the assignee of this application. The connector assemblies of the Narozn~ patent include two pairs of resilient leg members ,`, .

i~33600 which are attached to a body port;on of the connector assemblies, each of the leg members terminating in a ~oot adapted for inser-tion through a corresponding aperture in a printed circuit board.
The feet o~ at least one pair of the legs can be deflected to permit them to pass through their corresponding apertures. The resilient leg members and the deflectable feet permit the con-nector assem~lies to be pivoted or pushed into position. By pivoting or pushing the connector assemblies into position, i~is possible to avoid the wear generally resulting from the use of the connector assemblies, like the one disclosed in the Teagno et al. patent, which are mounted on a printed ci~cuit board by sliding them into position. Despite the substantial advantages of the connector assemblies described and illustrated in the ~arozny patent, their mounting and removal are complicated by the need to manually engage at least one pair of the leg members or feet to defl~ct the individual leg members or feet into proper positions with respect to the corresponding apertures in the prin-ted circuit board.
In the past, electrical contacts for printed circuit boards have employed a number of aligned insulation-displacing slots designed to displace the insulation of an insulated conduc-tor. Bowever, when such conductors are made from a bundle of in-dividual strands of conducting material, the outer strands tend to become somewhat realigned and compressed toward the medial longitudinal axes of the slots, thereby disadvantageously re-ducing the quality of the electrical connection between the con-tacts and the conductor. A contact having aligned insulation-piercing slots, which are similar to the insulation-displacing slots discussed above, is disclosed in the Narozny patent.

, 133~ 0 SUMMARY CF THE INVENTION
This is a division of parent Canadian Application Serial ~o.
338,542 filed October 26, 1979.
Many of the disadvantages and shor-tcomings of the connector assemblies and contacts discussed above æ e overcome by the present in-vention which includes a new and improved connector and contact housing adapted for use with printed circuit boards. The connector housing according to the parent application includes a base mounted on the top side of a printed circuit bo æd and having a depending portion extending fron the top side of the printed circuit board to the underside thereof.
A cover movably mounted with respect to the base has a depending portion which can be moved through an opening in the printed circuit board in response to the movement of the cover for releasably engaging the under-side of the printed circuit board. The depending portion of the base engages the underside of the printed circuit board and cooperates with the depending portion of the cover to releasably mount the connector in a fixed position on the top side of the printed circuit board. Inasmuch as the connector can be locked in position and unlocked simply by moving the cover, which is more readily accessible than any members depending from the base, mounting and removal of the connector are greatly facilitated.
In one especially advantageous embcdiment, the cover is pivotally mounted to the base for pivotal movement between an open position and a closed position. The cover can be releasably maintained in the closed position by a catch which is positioned on the base so as to releasably engage the cover when it is closed.
The depending portion of the cover may consist of a pair of arcuate hcoks, each of which is movable through a corresponding opening in the printed circuit board. To provide a mid-board connector, the depending portion of the base may consist of another pair of arcuate hooks, each of the hooks extending through a Pg/~\ - 3 ~

corresponding ope~ing in the printed circuit board. Alter-natively, in an edge board connector version of the present invention, the depending portion of the base i~ a single ~-shaped hook adapted for attachment to an exterior edge of the printed circuit board.
In summary of the above, therefore, the invention according to the parent application may be broadly defined as providing a housing mountable on one side of a printed circuit board comprising: a base defining a first bearing surface and having dependent leg means extending from one side of the print-ed circuit board through an opening in the board toward the opposite side thereof for engaging an edge of the opening; and a cover defining a second bearing surface direçtly engaged with the first bearing surface for supporting relative movement of the cover with respect to the base, the cover having integrally dependent leg means movable on cover movement relativé to the base, such cover leg means thereby being movable through the opening in the printed circuit board into engaging relation with another edge of the printed circuit board opening, such base leg means and the cover leg means thereby cooperatively mounting the housing.
The connector housing may receive the new and improved contact of the present invention which includes a plurality of insulation-displacing slots arranged successively therealong.
Each of the slots is offset with respect to at least one adja-cent slot, so that an insulated electrical conductor inserted into the slots will be bent a number of times to follow a tor-tuous path defined by the slots. The contact may be designed to tension the conductor, so that, if the conductor is made from a bundle of individual strands of electric-conducting mater-ial wrapped by a layer of electric-insulating material, dispiace-ment of the individual strands will be inhibited to provide a Pg/

~33600 good electrical connection between the conductor and contact.
In one novel embodiment, the contact includes a flat elongated body having an upstanding bridge extending outward-ly from the upper surface thereof. The upper surface of the bridge contains four insulation-displacing slots arranged in such a manner that the two end slots lie along a common center-line and the two other slots lie along another common center-line. A deflectable locking tang may be arranged on the body so as to cooperate with a stationary abutment in the connector housing for inhibitlng inadvertent removai of the contact from the connector housing.
Thus the present invention may be broadly defined as an electrical contact assembly comprising first and second con-tact members defining respective first and second insulation displacing slots aligned in spaced relation along a first axis and a third contact member defining a third insulation displac-ing slot, the third contact member biasingly disposing the third slot along a second axis offset from the first axis and being movable to dispose the third slot along the first axis in the course of insertion of an electrical conductor in the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the invention, reference may be had to the following description of the exemplary Pg/~ - 4A -`A`

il33600 .
embo~iments taken in conj~mction with the accompanying figures of the drawings, in which:
~ ig. 1 is an exploded perspective view of a connector and eontact assembly constructed in accordance with one embodi-ment of the present invention;
~ ig. 2 is a partial back elevational view of the eon-nectox and contact assembly shown in Fig. l;
Fig. 3 is a longitudinal cross-sectional-view of the eonneetor and contact assem~ly of Figs. 1 and 2;
Fig~ 4 is a plan view of the contact illustrated in Figs. 1-3;
Fis. 5 is a back elevational view of the contaet shown in Fig. 4; and Fig. 6 is a longitudinal eross-sectional view of an alternate e~bodiment of the connector and contact assem~ly of the preæent invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
The connector and contact assembly 10 illustrated in Figs~1-3 includes a eonnector 12 made from a plastie material and a plurality o contacts 14 made from a good electric-conducting material, such as a eopper alloy. The eonneetor 12 incl~des a base 16 and a cover 18 pivotally mounted thereto, The base 16 has a pair of vertical sidewalls 20 and a front wall 22. A plur-ality of vertical partitions 24 are spaced equidistantl~ aeross the base 16 to form a number of ehannels 26. Each of the ehan-nels 26 ineludes a horizontal dividing wall 28 which divides the channel 26 into an upper channel 30 and a lower ehannel 32. A
slot 34 in the rear end of the dividing wall 28 permits eaeh of the ehambers 26 to receive a corresponding one of the contacts 14, which will be described in greater detail hereinbelow.

1~33600 Nea~ the front of each of the sidewalls ~2 there in provided ~ vertically extending ear 35 having a horizontal slot 36 formed in the front end thereof and terminating in a circular opening 38. Each of the openings 38 receives a corresponding one of a pair of pins 40, each of which extends horizontally and inwardly from a respective one of a pair of sidewalls 42 of the cover 18. Although the diameter of the pins 40 is slightly greater than the width of the slots 36, the resiliency of the ears 35 permits the pins 40 to be slid through the slots ' 36 and into the openings 38, thus providing direct engagement of ba ,e and cover bearing surfaces supportive of rotational movement of the base with respect to the cover.
Each sidewall 20 of the base 16 includes a curved leg 44 extending downwardly and rearwardly from the sidewall 20.
As shown in Figs. 2 and 3, each of the legs 44 projects through a corresponding one of a pair of openings 46 extending through a printed circuit board ~8 between its upper surface 50 and its lower surface 52. A knee portion 54 of each of the legs 44 may be designed and dimensioned so as to positivel~ engage a rear edge 56 of a corresponding opening 46. The upper surface of the free end of the legs 44 has a lug 58 which makes physical contact with the lower surface 52 of the printed circuit board 48.
Each sidewall 42 of the cover 18 includes a curved leg 60 integral therewith. When the cover 18 is in its open position, as shown in Fig. 1, the legs 60 are positioned above the upper surface 50 of the printed circuit board 48. Upon the counterclockwise pivoting of the cover 18 toward its closed position, as shown in Figs. 2 and 3, each of the legs 60 rotates in the same directional angle as cover 18 and passes through a corresponding one of the openings 46 until a lug 62 on the upper surface of the free end of each leg 60 engages the lower surface 52 of the printed c~ 6--.

li33600 circuit board 48. ~ knee portion 64 of each leg 60 can be de-si~ned and dimensioned so as to engage a front edge 66 of a corresponding one of the openings 46.
Except for ~he two partitions 24 located adjacent to the sidewalls 20 of the base 16, each of the partitions 24 is provided on the front of its pointed upper edge 67 with a nipple 68. When the covex 18 is in-its closed position, each of the nipples 68 releasably engages a corresponding one of a plurality of holes 70 formed in a back face 72 of the cover 18 to prevent its inadvextent opening.
Referring now to Figs. 1-5, the contacts shown therein include a flat elongated body 74, the rear end of which is bent to form a deflectable shoe 76 adapted for engagement with a sur-face conductor (not shown) on the upper surface 50 of the printed circuit board 48. ~n upstanding bridge 78 extends verticall~ from the body 74 of the contact 14 intermediate the ends thereof. The bridge 78 includes a pair of towers 80, 82 each of which is canti-levered to an edge of the body 74 by a strut 84~ The front tower 80 includes a front wall 86 with a vertical insulation-displacing slot 88 formed in the upper edge thereof and a rear wall 90 having a vertical insulation-displacing slot 92 provided in the u~per edge thereof. Similarly, the rear tower 82 has a front wall 94 with a vertical insulation~displacing slot 96 provided in the upper eage thereof and a rear wall 98 including a vertical insulation-displacing slot 100 formed in the upper edge thereof.
The slots 88 and 92 are offset laterally with respect to each other (see Fig. 4). Similarly, the slot 96 is offset laterally with respect to the slot 100 (see Figs. 4 and 5). However, the slots 88, 100 are laterally aligned with each other, ~s are the slots 92, 96. The walls 90, 9~ are resiliently cantilevered to the ~336~0 walls 86, 98, respectively, so that when an electric cable 102 (see Fig. 4) is inserted into the slots 88, 92, 96, 100 by a suit~ble tool the slots 92, 96 are forced into alignment with the slots 88, 100. However, when the tool is removed, the re-siliency of the walls 90, 94 causes them to revert back to their original position with respect to the walls 86, 98, respectively.
With the walls 90, 94 in their original positions, the slots 92, 96 reassu.~e their offset relationship with respect to the slots 88, 100 respectively, thereby bending the cable 102 so that it follows a tortuous path defined by the slots and symmetrical with respect to a plane arranged perpendicular to the body 74 and con-taining a lateral axis thereof and tensioning the cable 102 to inhibit the undesired elongation of its radial cross section along the longitudinal axes of the slots. The upper end of each of the slots 88, 92, 96, 100 may be flared (as shown) to facilitate the insertion of the cable 102 thereinto.
Between the bridge 78 and the front end of the body 74 there is provided a locking tang 104 which is attached at its front end to the upper surfâce of the body 74 and extends upwardly therefrom at a predetermined angle. The tang 104 is deflectable, -so that upon insertion of the contact 14 into a corresponding one - of the channels 26 in the connector 12 the tang 104 is deflected downward by the dividing wall 28 to permit the complete insertion of the contact 14. When the tang 104 reaches a chamber 106 loca-ted behind the front wall 22 of the base 16, the tang 104 auto-matically reassumes its predetermined angle which is selected to permit the tang 104 to engage a rear wall 108 of the chamber 106 for inhibiting the inadvertent removal of the contact 14.
During the insertion of the contact 14, the strut 84 passes through the slot 34 in the dividing wall 28 with the 1~33600 towers 80, 82 being received in the upper cha~nel 30 and the body 74 being received in the lower channel 32. The inser~ion of the contact 14 also causes the deflection of the shoe 76 (see Fig. 3), thereby forcing the upper surface of the body 74 into engagement with the lower surface of the dividing wall 28 and urging the base 16 away from the upper surface 50 of the printed circuit board 48. The force exerted by the shoe 76 on the upper surface 50 of the printed circuit board 48 enhances the ~uality of the electrical connection between the shoe 76 and the surface conductor (not shown) of the printed circuit board 48. To facilitate insertion of the contact 14, the dis- -tance between the rear wall 108 of the chamber 106 and the front wall 22 o the base 16 is greater than the length of the portion of the contact 14 extending from a point directly below the free end of the tang 104 to the front end of the body 74. If it is desired to remove the contact 14 from the connector 12, a s~ita~le device can be inserted into the chamber 106 through a corxesponding opening 111 formed in the front wall 22 of the base 16 to deflect the tang 104 downward and out of engagement with the rear wall 108 of the chamber 1~6. Prior to the attachment of the connector 12 to the printed circuit board 48, the bridge 78 engages the ~ivid-ing wall 28 to prevent the contact 14 from dropping Ollt o the connector 12.
Each of the contacts 14 can receive a separate insulated electrical cable. The contacts 14 are also adapted for use with a ribbon cable having a plurality of individual spaced-apart electrical cables arranged side-by-side and wrapped in a single layer of electric-insulating material. When a ribbon cable is employed, the pointed upper edges 67 of the partitions 24 cut the webs of electric-insulating material separating adjacent cables to permit insertion of each of the cables into the slots 88, 92, 96, 100 of a corresponding contact 14.
When the cover 18 of the connector 12 is closed, its back face 72 blocks only a portion of the xear end of each of the upper channels 30, so that electrical cables can pass under the bacX face 72 and into the upper channels 30. An opening 113 provided in the front end of the cover 18 permits the passage of the electrical cables into the upper channels 30. Thus, re-g~rdless of the type of cablesused, the contacts 14 can be elec-}0 trically connected to the cables intermediate the ends thereof.
The connector 12 can be mounted to the upper surface50 of the printed circuit board 48 b~ inserting the legs 44 .through the centers of the corresponding openings 46 and then sliding the connector 12 rearwardly until the knee portions 54 of the legs 44 engage the rear edges 56 of the openings 46, thereby causing deflection of the shoes 76 which, in their de-flected position, tend to raise the front end of the base 16 o~
of the upper surface 50 of the printed circuit board 4~. To loc~ the connector 12 in place, the base 16 is pushed downt~ardly until its front end engages the upper surface 50 of the printed - circuit board 48 and then the cover 18 is pivoted in a counter-clockwise direction until it reaches its closed position in whîch the lugs 62 on the legs 60 engage the lower surface 52 of the printed circuit board 48. Due to the resiliency of the legs 44, 60, the connector 12 tends to compensate or board thickness tolerances and board warpage.
The connector 12 can be removed from the printed cir-cuit board 48 by pivoting the cover 18 in a c].ockwise direction until the lugs 62 disengage the lower surace 52 of the printed circuit board 48 and the legs 60 clear the edge 66 of the openin~

46. The connector 12 can then be slid forward to disen~age the lugs 58 from the lower surfac~ 52 of the printed circuit boara ~8 and retract the legs 44 through the openings 46.
Referring now to Fig. 6, there is shown a further em-bodiment: of the present invention. The various elements illus-trated in Fig. 6 which correspond to elements described above with respect to Figs. 1-5 have been designated by corresponding reference numerals, increaséd by 100. Unless otherwise statea, the further embodiment operates in the same manner as the em-bodim~nt of Figs. 1-5.
The embodiment of Fig. 6 utilizes a base 116 having an ~-shaped leg 220 which depends r~m the base 116 and extends toward a front wall 122 thereof. The leg 220, which replaces the legs 42 of the embodiment illustrated in Figs. 1-5, is positioned and dimensioned so as to engage an exterior edge ~22 of a printed circuit board 148. A lug 162 is axranged on the upper surface of the free end of each of the legs 160 so as to register with a corresponding depression 224 formed in the lower surface 152 of the printed circuit board 148 for the purpose of positively locking the connector 112 in a fixed position. A contact 114 has a deflectable shoe 176 which is formed at the front end of the contact 114, in ~ eàd of at its rear end. With the shoe 176 losated in the front end of the base 116, the force applied to the rear end of the cover 118 for closing it will be sufficient to automatically lower the front end of the base 116 onto the upper surface 150 of the printed circuit board 148 during the closing operation.
It will be understood that the embodiments described herein are merely exemplar~ and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. For instance, any number of plural slots can be employed. All such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.

Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electrical contact assembly comprising first and second contact members defining respective first and second insulation displacing slots aligned in spaced relation along a first axis and a third contact member defining a third insulation displacing slot, said third contact member bias-ingly disposing said third slot along a second axis offset from said first axis and being movable to dispose said third slot along said first axis in the course of insertion of an electrical conductor in said assembly.

2. The contact assembly claimed in claim 1, wherein said third contact member is formed integrally with at least one of said first and second contact members.

3. The contact assembly claimed in claim 1, wherein said first and said third contact members are portions of a common sheet member.

4. The contact assembly claimed in claim 3, wherein said first contact member portion has connection with support means and wherein said third contact member has connection only with said first contact member portion.

5. The contact assembly claimed in claim 1, wherein said first, said second, and said third contact members are por-tions of a common sheet member.

6. The contact assembly claimed in claim 5, wherein said first contact member portion and said second contact member portion have connection with common support means and wherein said third contact member portion has connection only with said first contact member portion.

7. The contact assembly claimed in claim 1 further includ-ing a fourth contact member defining a fourth insulation dis-placing slot, said fourth contact member biasingly disposing said fourth slot along said second axis and being movable to dispose said fourth slot along said axis.

8. The contact assembly claimed in claim 7, wherein said first and said second contact members comprise conti-guous inner parts of a common sheet member and wherein said third and fourth contact members comprise respective end parts of said common sheet member.

9. The contact assembly claimed in claim 1 further comprising a flat elongated body having an upstanding strut means connected with said first and said second contact mem-bers and providing cantilevered support thereof with respect to said body.

10. The contact assembly claimed in claim 9 further com-prising spring means extending from said body, oppositely to said strut means and comprising a contact in electrical connec-tion to said assembly.

11. The contact assembly claimed in claim 10, wherein said body includes locking means for retention of said assembly in a connector housing.