US3551750A - Circuit board connector - Google Patents

Description

United States Patent Inventor Maurice S. Sterling Willow Grove, Pa.

Appl. No. 817,769

Filed Apr. 21,1969

Patented Dec. 29, 1970 Assignee Hugh ll. Eby, Co.

Philadelphia, Pa.

a corporation of Pennsylvania CIRCUIT BOARD CONNECTOR 10 Claims, 10 Drawing Figs.

US. Cl. 317/101, 339/17, 339/176 Int. Cl. 1102b l/02 FieldofSearch 3l7/l01DA, IOICM,101:339/17,17LM,17Lc, 176(MP) [56] References Cited UNITED STATES PATENTS 3,173,732 3/1965 James ..339/176MP(UX) 3,215,968 11/1965 Herrmann ...339/l 76MP(UX) 3,270,311 8/1966 Deer et a1. ..339/l 76MP(UX) Primary Examiner- Robert K. Schaefer Assistant Examiner-D. Smith, Jr. Attorney-Stanley Bilker ABSTRACT: A circuit board connector having spring contact elements received in transverse channels is provided with retaining means for exerting a clamping bias at the intermediate portions of the spring contact elements.

PATENTEDUECZQISYB 3.651.750

' SHEET l flF 2- 42m. v m M /Y/// ///A 40 36 2O INVENTOR. Maurice 8. Sterling ATTORNEY. v

' PATfiNTEnmzslsm $551,750

SHEET 2 BF 2 INVENTOR. Maurice 8. Sterling ATTORNEY.

CIRCUIT BOARD CONNECTOR This invention relates to connectors used for interconnecting circuit boards. Such connectors provide a detachable electrical connection between adjacent circuit boards, for example, between the upper and lower peripheral edges of spaced circuit boards stacked one above the other.

Connectors of the type described use spring contact elements to bridge the conductors of adjoining circuit boards. The spring contact elements are carried in channels on in insulator block capable of being secured' in the assembly and of being readily removed therefrom.

One of. the disadvantages of prior art circuit board connectors is the inability of each leg of a generally U-shaped spring contact element to resist deflection independently of the other leg connected integrally therewith. The spring contact elements of most prior art connectors are free to move transverse to the longitudinal axis of the connector when engaged by only one circuit board. In other words, a force tending to deflect only one leg of a contact into its channel will not be yieldingly resisted unless an opposing force is applied to the other leg of.

the same contact. It is thus not possible with such prior art connectors to establish a properly biased electrical contact with the terminals or conductors of one circuit board until the second circuit board is secured in its proper position.

It is proposed, according to the present invention, to provide an improved circuit board connector having novel means for retaining the spring contact elements. Such retaining means preferably comprises a longitudinal retaining strip on the insulator block which engages intermediate portions of the spring contact elements and exerts a clamping bias thereon. This construction permits each leg of a spring contact element to resist deflection independently of its integral counterpart, thus overcoming one of the disadvantages of the prior art constructions.

In one form of the invention, the generally U-shaped contact elements are serially assembled on the insulator block with their open ends all extending in the same direction. In modified form, alternate contact elements are inverted so as to have their open ends extending in opposite direction. The latter arrangement ensures that balanced biasing forces will be applied between the connector and the circuit board.

As another modification of the invention the legs of the U- shaped contact elements are in converging relationship, and the connector is adapted to be assembled with circuit boards that are right angles to one another.

In still another modification of the present invention the intermediate portion of each contact element is bent to an angular form which interlocks with the channel of the insulator block and secures it thereto without a separate retaining strip.

Various other objects, features, and advantages of the invention will appear more fully from the following detailed description and the accompanying drawings.

In the drawings:

FIG. 1 is a top view of a connector constructed according to the invention;

- FIGS. 2, 3 and 4 are side, bottom, and end views, respectively, of the same;

' FIG. 5 is a transverse sectional view ofthe connector, taken along line 5-5 of FIG. 1, shown on a larger scale in engagement with two circuit boards;

FIG. 6 is a view similar to FIG. 5, but with the connector engaging only one circuit board;

FIG. 7 is a fragmentary view corresponding to FIG. 3, but showing a bottom view of the connector in modified form;

FIG. 8 is an enlarged, transverse sectional view of the modified connector shown in FIG. 7, taken along line 8-8 thereof;

FIG. 9 is a view corresponding to FIGS. 5 and 6, but without circuit boards and showing another modification of the invention; and

FIG. 10 also corresponds to FIGS. 5 and 6, and it illustrates still another modification of the present invention with its contact legs disengaged.

It is to be understood that only several forms of the invention will be described in detail, and that the scope of the invention is to be determined with reference to the claims at the end hereof.

Theconnector 10 shown in FIGS. 1 to 6 of the drawings has a series ofspring contact elements 12 mounted on a body orinsulator block 14. The latter is formed, preferably by molding, of a thermoplastic material having electrical insulation properties, such as Noryl. However, a large variety of moldable insulating materials are commercially available and can be used in practicing this invention.

The configurations of theblock 14 and thecontacts 12, also the spacing of the contacts, are suited to the particular application and the locations of the conductors to be bridged by theconnector 10. Theblock 14 illustrated in the drawing is an elongated member of generally rectangular cross section, and of sufficient length to accommodate a given number of serially arranged, electricallyconductive contacts 12 in the desired locations.

Eachspring contact element 12 is protectively received in atransverse channel 16. Thechannels 16 are defined by transverse ridges orbarrier strips 18 that are an integral part of theblock 14. Preferably, thechannels 16 extend about at least three sides of theblock 14, including two oppositely facingsides 20 and 22, and a third ortop side 24 between them. Although the invention is not so limited, thespring contacts 12 are generally U-shaped and they extend about thesides 20, 22 and 24 of theblock 14, as illustrated.

Of the various conductive and resilient materials from which thespring contacts 12 may be made, beryllium copper plated with gold over nickel flash is preferred. Eachcontact 12 is of unitary construction and comprises anintennediate portion 26 joined endwise to two outwardly biased or spreadcontact legs 28 and 30. Each contact leg has aninturned tip 32 at its free end, adapted to remain within itschannel 16 under all deflection conditions. Before assembly with circuit boards, a substantial portion of thelegs 28 and 30 extend outside thechannels 16 and away from thesides 20 and 22 of theblock 14; but after assembly they are deflected into thechannels 16 entirely.

Thecontacts 12 are secured to theblock 14 by aretainer strip 33 received in a longitudinally extending groove or recess in the top side of the block. Thebottom side 36 of theblock 14 is made similar to thetop side 24 for convenience and symmetry, and therefore therecess 38 which can be seen in FIG. 3 may be regarded as similar to its counterpart. In order to accommodate theretainer strip 33, the recess extends across the entire series ofchannels 16 and to their full depth. In addition, the lateral surfaces of theretainer strip 33 are serrated to in terlock with the edges of the barrier strips 18, and subsequently bonded thereto ultrasonically or by the application of heat and mechanical pressure. For this reason, it is preferred that the retainer strip also be made of thermoplastic insulating material like that of the block '14. Alternatively, adhesives may be employed.

When theconnector 10 is assembled according to the invention thecontacts 12 are secured with theirintermediate portions 26 clamped by theretainer strip 33 against the recessedtop side 24 of theblock 14. With thecontacts 12 thus secured, theirlegs 28 and 30 are eachgcapable of independently resisting deflection without transmitting the deflection force to the other leg, since the contact operate as if rigidly built into theblock 14 at theirintermediate portions 26.

Theconnector 10 is shown in FIG. 5 assembled with a pair of circuit boards, thecontact 12 having itslegs 28 and 30 deflected inwardly while in biased engagement with theconductors 42 of the circuit boards. The assembly is held together by any suitable securing means, as by bolts. In order to accommodate bolts, the ends of theblock 14 are provided withconcave indentations 44 which cooperate with the securing means to hold the connector in position.

The assembly of FIG. 5 illustrates thelegs 28 and 30 of thecontact 12 deflected inwardly of thechannel 16 by the assembledcircuit boards 40. Good electrical contact is made with theconductors 42. The deflection of thecontact legs 28 and .30, is in bending about the adjacent corner of thetop side 24 of theblock 14, tending to deflect theintermediate contact portion 26 outwardly. However, the retainingstrip 33 resists any outwarddeflection of theintermediate portion 26, since the strip33issecurely connected to the top side of theblock 14. The interengagement of the serrated edges of thestrip 33 with the top edges of the barrier strips 18 resists longitudinal dis- 40 of FIG. 6 has itsconductor 42 in good electrical contact "with theother contact leg 30, sinceleg 30 yieldingly resists inward deflection, independently of theleg 28, due to the clamping of the adjacentintermediate contact portion 26 previously described.

From the foregoing it can be seen that connector is of rugged'and dependable construction; that it has improved deflection characteristics; and that it overcomes various disadvantages of prior art connectors without sacrificing economy or simplicity of manufacture.

MODIFICATIONS Several modifications of theconnector 10 shown in FIGS. 1 to 6, will now be described with reference respectively to :FIGS; 7 and 8,9, andlO. However, since the basic construc- "tion of each connector remains the same, like reference numerals will be employedtb designate correspondingly similar parts of the several embodiments of the invention.

In' the embodiment of the invention shown in FIGS. '7 and 8,

, theconnector 10 has itscontacts 12 arranged as if in a basket weave pattern, with every other contact in series being reversed. Thus, conventionaLU-shapedcontacts 12 are alternated withcontacts 12a of inverted U-shaped configuration. Obviously, thecontacts 12a may be structurally identical with thecontacts 12 except that eachcontact 12a is mounted with itslegs 28a and 30a extendingin a direction opposite to that in which thelegs 28 and 30 ofcontact 12 extend. Furthermore, since theblock 14 hasitsbottom side 36 made similar to'itstop side 24, the block l4 of the previously described embodiment is readily adapted to this modification with the alternately reversedcontacts 12 and l2a by the addition of asecond retainer strip 33a at the bottom side'36. Thesecond retainer strip 33a fits therecess 38, in the same manner as itscounterpart 33, in order to clamp theintermediate portions 26a ofcontacts 12a at the bottom of the connector. It is readily apparent that the embodiment of the invention shown in FIGS. 7 and Sensures thatthere will be a balanced biasingforce exertedbetween'the connector 10 and the circuit boards engaged thereby, unlike the unbalanced biasing contact of FIG. 5. A balanced biasing force prevents any rotation of the connector in the assembly or the application of distorting torque thereto which might reduce the effectiveness of contact between engaging surfaces.

Referring now to ,the embodiment of the invention shown in FIG. 9, this form of theconnector 10 is adapted to interconnecting circuit boards that may be at right angles to one another. With this arrangement the cross-sectional configuration of theblock 14 is altered to any suitable shape wherein thelegs 28 and 30 of eachcontact 12 extend in converging directions. In the illustrated embodiment, thelegs 28 and 30 of eachcontact 12 extend transversely alongadjacent sides 22 and 30 of anelongated block 14 of generally square cross section; and theintermediate portion 26 is clamped by theretainer strip 33 against a flattened comer between the other twosides 20 and 24 of theblock. Thestrip 33 is received in a suitable recess formed in the barrier strips 18 and may be securely attached thereto by the means previously described in connection with the other embodiments. 1 V

In FIG. 10 still another modification of the invention is illustrated. In this embodiment, however, thecontacts 12 have been provided with anintermediate portion 26 of novel shape to fit securely in adovetail'slotiog recess 44 at the top or bot tom of theblock 14, without need o'fa retainer strip to clamp it or hold it against rotation. With as inilar recess 44 at the top and bottom of theblock 14 it is agaimpossible to assemble a series ofcontacts 12 in alternately reversed positions, as in the embodiment of FIGS. 7 and 8. I

The connector embodiment of FIG. IO'features ablock 14 having curved sides, a cross section adaptable to any of the previously described embodiments. Furthermore, therecess 44 is inwardly divergent for at least a portion of its length between barrier strips 18, sufficient to accommodate, posi tion, and secure eachcontact 12. The draft on' the sidewalls of the recess is suited to the materials and dimensions of the fitting parts, as well as the forming processes employed, audit is therefore not restricted to any particular range. It will suffree to say in defining this embodiment in the broad sense that the sidewalls of therecess 44 are inwardly divergent, that aresilient projection 46 on theintermediate contact portion 26 is larger than the mouth oftherecess 44, and that theprojection 46 has surface portions interlockingly engaging the sidewalls of therecess 44 so as to resist rotation therein and removal therefrom. As illustrated, theprojection 46 is generally U-shaped in form and fitted snugly to the walls of therecess 44, whereby the resilience and'flexi'bility of the structure permits the structure to flex when snapped into therecess 44 and to spring back into firm contact withthe sidewalls of the recess. The engaging flat, noncircular surfaces of the :pro-

jection 46 and therecess 44 resist relative rotational move.-

ment, while the dovetail configuration of the recess secures theintermediate portion 26 and clamps thecontact 12 to .the

body 14.

Iclaim:

1. A connector for interconnecting a plurality of circuit boards comprising:

an elongated insulator block having two generally oppositely facing sides and at least a third side therebetween; a plurality of channels in said block extending transverse to the longitudinal extent thereof about said sides; 1

a plurality of spring contact elements in respective channels, each having an intermediate portion and two contact legs joined together, said contact legs being outwardly biased so as to have portions thereof extending outside said channels and away from said oppositely fac ing sides when disengaged from said circuit boards; and

retaining means exerting a clamping bias between the intermediate portions of said contact elements and said third side for securing said contactelements to said block.

2. A connector according to 'claim 1 wherein said spring contact elements are generally U-shaped and made of electrically conductive, resilient material.

3. A connector according to claim 1 wherein the block has a fourth side disposed opposite said third side and between the other two sides, and the spring contact elements are serially arranged along the length of said block with theintermediate portions of said elements alternately secured to the respective third and fourth sides of said block.

4. A connector according to claim 1 wherein said re t 'aining 6. A connector according to claim 4 wherein said insulator block and said retaining strip are made of thermoplastic, electrical insulating material and joined together with the intermediate portions of said spring contact elements clamped between the third side of said block and said retaining strip.

7. A connector according to claim 6 wherein said block and said retaining strip are fused together.

8. A connector according to claim 1 assembled with a pair of circuit boards, each having conductors on a side thereof in mutually facing relationship with one of the two oppositely facing sides of said block, the conductors having terminal portions in contact with said spring contact elements.

9. A connector according to claim 1 wherein the contact 0 surface portions for engagement with one another, whereby said retaining means secures said contact element to said block and resists relative rotational movement therebetween.

Images