US3434094A - Buss strip - Google Patents

Description

G. WALTER BUSS STRIP March 18, 1969 Filed July 20, 196'? a 2% M 14 l Z m 7 m/ i f M z W United States Patent 7 Claims ABSTRACT OF THE DISCLOSURE An electrical connector which has a spring arm integral with and extending along an edge of a buss strip. A spring finger which has an arcuate contact surface extends from an end of the spring arm for contact with circuitry on a printed circuit board.

This invention relates in general to electrical circuitry. It deals more particularly with a buss arrangement for electrical terminals.

It is well known in the art, of course, to buss together electrical terminals mounted in a connector complex. This is aptly demonstrated in the Vanderpool Patent No. 2,857,577, which illustrates a direct entry connector assembly for a printed circuit board. The buss strip and contact arrangement in the Vanderpool construction is complicated, relatively expensive and inefficient, however, with the contacts formed separately and riveted or stapled to the buss strip. Furthermore, the Vanderpool contact effects relatively inconsistent and occasionally inadequate resilient engagement with a directly entering printed circuit board.

Accordingly, it is an object of the present invention to provide a new and improved bussing arrangement for a connector assembly adapted to receive a printed circuit board in direct entry relationship.

It is another object to provide a bussing arrangement including unitarily formed contacts which afford heretofore unattained flexibility.

It is still another object to provide a new and improve-dcontact construction for a direct entry printed circuit board connector assembly.

It is a further object to provide a contact construction which affords highly eflfective wiping of contact and circuit surfaces, as well as maintaining a consistently superior resilient retaining force on the direct entry printed circuit board.

The foregoing and other objects of the present invention are alforded by providing a unitary arrangement of contacts and a buss strip in a matrix of dielectric material seated on a terminal plate and adapted to receive a printed circuit board in direct entry relationship. The contacts are formed unitarily with the upper edge ofthe buss strip and develop highly effective resilient engagement with the circuitry on the printed circuit board. Each contact includes a spring arm extending generally parallel to a corresponding edge of the buss strip and joined to the edge at one end. A spring finger is joined to the opposite end of the spring arm and extends generally perpendicular to the arm. A contact surface for engaging circuitry on the printed circuit board is formed on the free end of the spring finger. Superior overall resiliency is afforded by resilient deflection of the spring finger in a plane generally parallel to the spring arm and, in addition, resilient deflection of the spring arm in a plane generally parallel to the spring finger.

The invention, together with its organization and method of operation, taken with other objects and advantages thereof, is illustrated generally more or less diagrammatically in the drawings in which:

FIGURE 1 is a plan view of a portion of a terminal connector assembly incorporating a buss strip and contact arrangement embodying features of the present invention, with parts broken away;

FIGURE 2 is an enlarged plan view of a portion of the connector assembly illustrated in FIGURE 1;

FIGURE 3 is a sectional View taken along line 33 of FIGURE 2;

FIGURE 4 is an enlarged top plan view of a portion of a buss strip and contact arrangement embodying features of the present invention, and

FIGURE 5 is a sectional view taken along line 55 of FIGURE 4.

Referring now to the drawings, and particularly to FIG- URE l, a portion of a connector assembly for a computer module or the like is shown generally at 10. The connector assembly 10 includes a conventional terminal plate 11 upon which is mounted a connector complex 12 (only partially shown). The connector complex 12 normally extends over the entire plate 11 and is adapted to complete connections to a series of printed circuit boards 13 (only one shown) received in direct entry relationship. Surrounding the connector complex 12 and extending along the sides and ends of the plate 11 are phenolic plate stiffening members 14 secured to the plate in a conventional manner by fasteners 15.

Referring now to FIGURES 1 and 2, the connector complex 12 includes a matrix 20 of dielectric material such as phenolic or the like seated on the plate 11. The phenolic matrix 20 actually comprises a series of elongated printed circuit board receiving blocks 20a, 20b, et seq. (only two shown), arranged in immediately adjacent, side-by-side relationship on the terminal plate 11. Each elongated block 20a, 2012, et seq., is adapted to receive one printed circuit board 13 in the manner illustrated in .FIGURE 1.

Referring specifically to FIGURE 2, a portion of the matrix block 20a is shown in greater detail. The block 20a includes a pair of oppositely disposed end block segments 21 (only one shown) separated by a plurality of intermediate block segments 22 (only one shown). Each of the block segments 21 and 22 houses a plurality of electrical contacts 30 adapted to engage circuitry on a printed circuit board 13.

Of the contacts 30 mounted in the block segments 21 and 22, the two intermediate contacts 30a in each end block segment 21 are distinctive in that they each comprise a component of a buss strip and contact arrangement embodying features of the present invention. These buss strip and contact arrangements 35 carry current to or from circuitry on respective printed circuit boards through the contacts 30a. The buss strip and contact arrangements 35 are identical and only one is described.

Turning to FIGURES 35, a portion of a buss strip and Contact arrangement 35 is illustrated in substantial detail. In FIGURE 3, the arrangement 35 is shown seated in an end block section 21 and arranged for receipt of and contact with a printed circuit board.

The buss strip and contact arrangement 35 includes an elongated buss strip fabricated of Phosphor bronze or the like. One free end of the buss strip 40 extends from the dielectric matrix 20, through a corresponding stitfening member 14, to a power feed-out stud assembly, as at 40a. The buss strip is welded to the stud assembly. The feed-out stud assembly is connected to a suitable source of power (not shown).

The buss strip 40 passes transversely through adjacent matrix blocks 20a, 20b, et seq., along the length of the terminal plate 11. Formed unitarily with the buss strip 40 and extending from its upper edge 41 at regularly spaced intervals are the contacts 30a embodying features of the invention. Formed unitarily with the buss strip and extending from its lower edge 42 at regularly spaced intervals are conventional wire wrap posts 43.

The buss strip 40 passes through vertical slots extending transversely through each end block segment 21. Each wire wrap post 43, in turn, extends through a passage in a depending sleeve 56 formed unitarily with the end block segment 21. The sleeve 56 is seated in a corresponding aperture 57 extending through the terminal plate 11 and a locking shank 58 on the post expands the sleeve 56 to grip the plate 11 in the manner illustrated in US. Patent No. 2,995,617, assigned to the same assignee as the present invention.

The contact portion 30a of the buss strip and contact arrangement 35 extends upwardly into an individual well formed in the block segment 21. Actually, identical wells 65 receive each contact 30 and 30a, although the contacts 30a are distinctively constructed according to the present invention. Accordingly, only the well 65 in that portion of the block 21 surrounding one contact 30a is illustrated and described in detail.

Each well 65 is defined by oppositely disposed, upstanding side walls 67 and end walls 68. The vertical slots 50 hereinbefore referred to extend through the side walls 67. In addition, vertically extending slots 70 are formed in each of the oppositely disposed end walls. The vertically disposed slots 70 are adapted to receive the lower edge of a printed circuit board 13 -(not shown in FIGURE 3) and support the board in upright relationship for engagement by the contact 30a.

The contact 30a extending upwardly into the well 65 includes a spring arm formed unitarily with the strip 40. The spring arm 75 extends generally parallel to the upper edge 41 of the strip 40 and is joined to the edge 41 at one end of the arm 75 through a right angle attachment section 76.

As seen in FIGURE 4, the spring arm 75 is off-set at so that its elongated free end section 81 lies in a plane displaced to one side of the plane of the buss strip 40 and parallel to its edge 41. In FIGURE 4, the free end section 81 is shown displaced one full strip thickness to one side of the buss strip 40. However, in practice this displacement might be slightly more or slightly less than a full strip thickness.

Joined to the free end 85 of the spring arm end section 81 and formed unitarily with the arm 75 and the buss strip 40 is a spring finger 87. The spring finger 87 extends upwardly in the well 65, generally perpendicular to the spring arm 75 and the edge 41 of the strip 40.

The spring finger 87 is actually a fiat segment of the strip material from which the buss strip 40 and contact 30a are unitarily formed, die cut to extend perpendicular to the strip edge 41 and bent at a right angle from the plane of the free end section 81 of the spring arm 75. The width of the spring finger 87 is such that, when bent at a right angle to the spring arm end section 81 in the manner described, it is disposed directly over the buss strip 40, with the plane of the buss strip bisecting the upwardly extending spring finger.

The spring finger 87 includes a base section 90 joined to the free end 85 of the spring arm end section 81 immediately below a side cut-out 91 formed in the base section to facilitate forming a satisfactory radius of curvature in the spring arm free end 85 as the finger is formed to place it at right angles to the plane of the section 81. Extending upwardly from the base section 90 of the spring finger 87, and curved roughly into a C-shape, are a pair of finger tines 93(To enhance the resiliency of the finger 87, the tines 93 are formed to a thinner crosssection than the spring arm 75 strip, as seen in FIGURE 3. The curvature of the finger tines 93 is such that an arcuate contact surface 95 on each of the tines extends inwardly of the matrix well 65 to a point where the contact surfaces 95 have penetrated the profile of the printed circuit board receiving slots 70 for a distance equal ap- 4 proximately to the thickness of the strip material, as illustrated in FIGURE 3.

It will now be recognized that as a printed circuit board 13 is inserted in the slots 70 of a matrix block 20a, for example, the spring finger 87 is resiliently biased in a direction parallel to the upper edge 41 of the buss strip 40 and to the spring arm 75. As a spring finger 87 is deformed in this manner, it exerts leverage on the free end 85 of the spring arm 75, causing the spring arm 75 to be resiliently deformed downwardly in a direction perpendicular to the upper edge 41 of the buss strip 40 and generally parallel to the spring finger. The result is a compound resilient deflection of the entire contact 30a about its attachment section 76.

This compound deflection of the contact 30a in the manner described gives the contact great flexibility. Nevertheless, the contact 30a construction embodying features of the invention provides a strong, highly effective resilient retention force acting on the printed circuit board to retain the board in the slots 70 of the matrix block 20a, for example. At the same time, because of the strong resiliency of the compound axis deflection, the contact surfaces 95 press tightly against corresponding circuitry (not shown) on the printed circuit board to wipe the circuitry and the contact surfaces 95 free of oxides or foreign material or the like, whereby an excellent electrical connection is assured.

The compound axis resiliency of the contact 30a provides further advantages. Even after repeated insertion and removal of a printed circuit card, a consistent contact pressure is maintained. Furthermore, this construction permits the contact to adapt to a wide range of tolerance in printed circuit card thicknesses while maintaining consistent contact pressure.

As has been pointed out, the entire contact 30a is formed unitarily with the buss strip 40. In a die-punching operation, the generally L-shaped combination spring arm 75 and spring finger 87 are formed in flat stock. The spring arm 75 is then off-set in the manner illustrated in FIGURE 4 by conventional forming techniques. The separately die-cut tines 93 are then bent in a well-known manner to form the projecting contact surfaces 95. Then the finger is bent at right angles to the free end section 81 of the arm 75. The result is the highly flexible, extremely strong contact 30a fabricated unitarily with the buss strip 40 to form the buss strip and contact arrangement 35 embodying features of the present invention.

While the embodiment described herein is at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of the United States is:

1. In an electrical connector arrangement for printed circuit boards wherein a buss strip is mounted in a matrix of dielectric material, the improvement in contact means formed unitarily with the buss strip, comprising: spring arm means elongated along an edge of the strip and joined at one end to said edge, spring finger means extending generally perpendicular to said edge and connected at one end to the opposite end of said spring arm means, and contact surface means formed on said spring finger means, said spring arm means resiliently deflecting in a direction generally perpendicular to said edge and parallel to said spring finger means while said spring finger means is resiliently deflecting in a direction generally parallel to said edge and to said spring arm means when said contact surface engages a printed circuit board or the like in operational relationship.

2. The improvement in contact means of claim 1 further characterized in that at least a major portion of said spring arm extends generally parallel to the plane of said buss strip.

3. The improvement in contact means of claim 2 further characterized in that said major portion of said spring arm extends substantially parallel to said edge.

4. The improvement in contact means of claim 3 further characterized in that said major portion of said arm means is off-set transversely of said plane of the buss strip so that said portion is disposed at least partially on one side of said plane.

5. The improvement in contact means of claim 4 further characterized in that at least a portion of said spring finger means is off-set transversely of said spring arm means portion so that said spring finger means portion is disposed at least partially on the other side of said plane.

6. The improvement in contact means of claim 1 further characterized in that said spring finger means includes an arcuate tine section adjacent the free end of said finger means, said contact surface means being formed on said arcuate tine section.

References Cited UNITED STATES PATENTS 1/1966 Ruehlemann 339-276 X 5/1967 Spera 339192 RICHARD E. MOORE, Primary Examiner.

R. STROBEL, Assistant Examiner.

US. Cl. X.R. 339221, 258

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