Electrical Interconnector

Abstract

Compressible electrical interconnectors have dielectric holder sheets with compressible conductive plastic rods extending through the sheets. When electrical contacts are pressed against opposite ends of the rods, interconnection is completed.

Description

BACKGROUND OF THE INVENTION

Electrical interconnectors for completing circuits between opposed contact areas are well known. Typically, the interconnectors are thin rigid sheets of dielectric material having holes which are filled with electrically conductive elements. Electrical contacts, such as contacts on printed circuit boards, are placed adjacent opposite sides of the interconnector so that the conductive elements in the interconnectors are lined with and positioned between appropriate complementary contact areas. Usually, small pressure is applied to the contact bearing members to insure sufficient electrical connection.

The contacts to be interconnected take any of several forms. In some devices the contacts are carefully insulated islands in the middle of the circuit board with the conductive wires being insulated or buried on or within the board. In other cases, such as in strip line connectors, parallel conductors may be exposed over a substantial surface area of a circuit board. Any area along any conductor serves as a contact area as controlled by the position of a conductive element in the dielectric retainer of the interconnector.

In other embodiments, a strip line connector may have several layers of connectors which are crossed and insulated from each other. Contacts on the surface of the board may be permanently connected with conductors within the board or holes through the insulation may expose contact areas on conductors within the boards. In the latter case, interconnectors have projecting elements which fit within the holes to reach the exposed area of the embedded conductor.

Some forms of interconnectors may be very thin sheets having openings which have resilient elements for projecting through the openings for contacting contacts on one side of the sheet. Several problems remain in the interconnector art. For the most part, interconnectors are formed of a dielectric resin and metallic conductive elements. The dielectric retainer and metal conductive elements being of completely different materials require completely different fabricating steps. Hence, the cost of interconnecting devices is increased by the necessity of using dissimilar equipment and steps in manufacturing the dielectric and conductive portions. Temperatures required for the forming of thermoplastic or thermosetting dielectric materials are often too high to form the plastics about preformed fine metallic conductors. Where metals are flowed into openings in the interconductors, temperatures may cause destruction in the dielectric material or may cause latent damage to the interconnectors which may be found only after the connectors have been used for a period of time in expensive electronic equipment.

During use, metal contact elements may scratch or otherwise damage delicate contact areas on printed circuits. The best interconnectors employ highly conductive metal elements such as, for example, silver, and consequently, the high cost of the conducting element adds to the cost of the interconnectors. These and other problems cause the continued search for improved interconnectors.

SUMMARY OF THE INVENTION

The present invention concerns interconnector elements and their making and using in which elements are short compressible rods having discreet conductors disposed therein and being positioned between contact areas which are intended for electrical connection. The elements are assembled in a dielectric retainer which typically takes the form of a flat thin material having a plurality of holes extending from one surface to an opposite surface, with the elements disposed in the holes and extending from surface to surface. The retaining dielectric is flexible or rigid. In one rigid dielectric embodiment, compressible conductor elements extend beyond surfaces of the retainer. In another embodiment, compressible conductive elements are level with or depressed from relatively less compressible or incompressible surrounding dielectric material, and rigid convex contacts are fixed to junctions on the conductors to be connected. When used with convex contacts, conductive elements and rigid retainers may be flush with or depressed in the surface of rigid retainers. In both cases, the resilient conductive elements are compressed between complementary opposed contacts to complete electrical circuits.

When the retainer is resilient and compressible, the conductive elements are either compressible or rigid or relatively rigid. Although the conductive elements may extend outward from the surfaces of the dielectric retainer, the conductive elements are substantially coterminal with surfaces of the retainer in the preferred embodiments.

The dielectric retainer may be made of any convenient material which has a form sufficiently stable to hold the conductor elements in desired alignment with the contact areas. Any suitable thermosetting or thermoplastic resin may be employed. In high heat applications, thermosetting resins are preferred. The resin used in the dielectric retainer may be identical with the resin of the conducting element.

In preferred embodiments, the conductive elements are resilient and compressible. When the dielectric retainer is resilient and compressible, the conductive elements may be made of materials having similar properties, or the elements may be made of relatively rigid materials.

In one embodiment of the invention, the retainer is made of a silicone rubber, and the conductive element is made of a silicone rubber having embedded therein chunks of similar silicone rubber and a finely dispersed conductive metal, such as for example, silver flake. The metallic content of the conductive element may be as low as about 1.5 percent by volume.

In one example of the manufacture of the interconnectors, rods are formed by mixing cured particles of room temperature vulcanizable silicone rubber having average particle size of about 3 mils with uncured resin of the same silicone rubber and with silver flake smaller than 325 mesh. A suitable proportion is approximately 3 parts by weight cured particles, 3 parts uncured resin and catalyst in a 9 to 1 ratio and 5 parts silver flake. From 3 to 4 parts of alumina particles may be added. The dielectric retainer may be formed of similar room temperature vulcanizable silicone rubber without the particulate fillers.

The rods are precisely arranged in parallel relationships in a frame, and voids are filled with the flowable resin which will form the retainer. When the resin is cured, the block is sliced into several similar interconnector devices with particularly positioned conductor elements.

The invention has as one object the provision of electrical interconnectors having precisely positioned conductive elements of a dielectric resin containing discreet electrical connectors held in electrical conducting relationship in the elements.

Another object of the invention is the provision of compressible conductive elements precisely positioned in dielectric retainer sheets forming printed circuit interconnectors.

The invention has as a further objective the provision of compressible and resilient discreet conductor-filled resin elements held within compressible and resilient retainers at precise positions for selectively electrically interconnecting contacts on opposite sides of the retainer sheet. Other objects of the invention are methods for making compressible electrical circuit interconnectors and for employing compressible circuit interconnectors.

The foregoing and other objects of the invention are apparent in the disclosure which includes the foregoing and ongoing specification and claims and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electrical interconnector of the present invention.

FIG. 2 is a detail of an interconnector showing a conductive particle-filled compressible connective element in an insulating retainer.

FIG. 3 is an assembled detail of spaced opposed printed circuit boards with an interposed connector of the present invention and outer platens for pressing the circuit boards inward to insure electrical communication.

FIG. 4 is an exploded view of a strip line interconnection employing an interconnector of the present invention.

FIG. 5 is an exploded view of an interconnector employed in an electroluminescent system.

FIG. 6 is a detail of a conductive element recessed in a dielectric material.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, an interconnector is generally referred to by the numeral 10. The dielectric resin retainer 12 has a plurality of holes which are filled with rod-like conductors 14 which are compressible and resilient. Preferably, dielectric material 12 is the same basic composition as conductive elements 14, and both have substantially the same resilience and compressibility. As shown in FIG. 1, elements 14 are flush with opposed surface areas of the dielectric material 12.

In FIG. 2, the detail shows a relatively resilient conductive element 16 extending slightly beyond opposite surfaces of a dielectric material retainer 18. Forces caused by compressing the opposite ends of elements 16 together in the application of the device insure good electrical contact. In this embodiment, retainer 18 may be made of a relatively rigid dielectric material.

In FIG. 3, interconnector 20 which has dielectric material 22 and conductive plastic elements 24, is positioned between circuit boards 26 and 28. Contact areas 30 and 32 are joined by one of the conductive elements while contacts 34 and 36 are joined by the other conductive element. Platens 38 are employed to press boards 26 and 28 inward to insure good contacts between the contact areas and the conductive elements. The dielectric material 22 and the basic material of conductive elements 24 is similar. Inward pressure of the platens 38 tends to compress the conductive elements and dielectric material equally. Alternatively, the dielectric material 22 may have greater or lesser compressibility than the conductive elements 24.

As shown in FIG. 4, an interconnecting device 40 having dielectric material 42 and contact elements 44 is interposed between two strip line circuit boards 46 and 48. The inner hidden surface of board 46 has parallel vertical exposed conductive members 47. Board 48 has parallel horizontal exposed conductive members 49. When the boards are pressed together, conductive plastic elements 44 interconnect specific vertical conductors with specific horizontal conductors.

In FIG. 5, an electrical interconnector 50 has a dielectric material 52 and a plurality of conductive plastic elements 54 which interconnect contacts 56 on circuit board 58 with appropriate contacts on the electroluminescent panel 60. A frame at the edges of the panel aids in the compression of the entire device to press the resilient conductors onto the contact areas insuring completed circuits in FIG. 6, a panel has a conductive element 64 recessed from the surface of dielectric material 62.

As described herein, the interconnector of the present invention provides solution to many of the extant problems of the prior art. Cost economies are realized by the use of very minor portions of conductive metals. Economies are created in manufacturing both the insulating and the conducting elements with similar equipment and steps, since both are made of similar materials. The dielectric material and the conducting element are temperature suited, since both are constructed of similar materials. The metal-filled compressible elements neither abrade nor otherwise damage the delicate contact areas of printed circuits.

The interconnectors of the present invention are lighter in weight than conventional interconnectors, since metallic content is reduced. The present interconnectors conveniently and thoroughly interconnect printed circuit devices which may have surface irregularities due to production faults, thus eliminating errors caused by non-surface conforming interconnectors of the prior art when used with non-planar printed circuit surfaces.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. Electrical interconnecting apparatus comprising a dielectric material having first and second opposite surface areas and having at least one hole extending through the dielectric material from the first surface area to the second surface area, at least one elastomeric compressible resilient electroconductive element disposed in the hole, the at least one element comprising a dielectric resin containing discrete electrical conductors held in electrical conducting relationship in the element.

2. The electrical interconnecting apparatus of claim 1 wherein the dielectric material has a plurality of holes therein and wherein the at least one element comprises a plurality of elements disposed within the holes for electrically connecting a plurality of first contacts adjacent the first surface area of the material with a plurality of second contacts adjacent the second surface area of the material.

3. The electrical interconnecting apparatus of claim 1 wherein the dielectric material comprises a resin.

4. The electrical interconnecting apparatus of claim 1 wherein the dielectric material comprises a flexible, thin resin sheet.

5. The electrical interconnecting apparatus of claim 1 wherein the dielectric material comprises a thin resilient resin sheet.

6. The electrical interconnecting apparatus of claim 1 wherein the dielectric material comprises a flexible resilient and compressible resin sheet having first and second opposite faces and having a plurality of holes extending through the sheet, and wherein the at least one electroconductive elements comprises a plurality of elastomeric rods disposed in the holes, the rods having electroconductors therein whereby a plurality of contacts adjacent the first face are electrically connected with a plurality of contacts adjacent the second face.

7. The electrical interconnecting apparatus of claim 6 wherein each rod has a plurality of relatively small discreet conductors held by the elastomeric rods in electrical conducting relation which is enhanced by compressing the rods between contacts adjacent the sheet faces.

8. The electrical interconnecting apparatus of claim 1 further comprising first contact bearing means adjacent the first surface area and having positioned thereon at least one first contact adjacent the at least one element, and second contact holding means adjacent the second surface area and having a second contact adjacent the at least one element and means pressing the first and second contact means inward thereby tending to compress the at least one element and completing an electrical circuit between the first and second contacts.

9. The apparatus of claim 1 wherein the element extends from one surface of the dielectric material to an opposite surface thereof.

10. The apparatus of claim 1 wherein the element extends beyond opposite surfaces of the dielectric material.

11. The method of joining electrical contacts comprising positioning contacts opposite each other, interposing a dielectric retainer having a conductive elastomeric element extending therethrough between the contacts and pressing the contacts towards each other, thereby compressing the conductive elastomeric element and completing a circuit between the contacts.

12. Electrical interconnecting apparatus comprising a dielectric material having first and second opposite surface areas and having at least one hole extending through the dielectric material from the first surface area to the second surface area, at least one electroconductive element disposed in the hole, the at least one element comprising a dielectric resin containing discrete electrical conductors held in electrical conducting relationship in the element, wherein the dielectric material is relatively less compressible than the element.

13. Electrical interconnecting apparatus comprising a dielectric material having first and second opposite surface areas and having at least one hole extending through the dielectric material from the first surface area to the second surface area, at least one electroconductive element disposed in the hole, the at least one element comprising a dielectric resin containing discrete electrical conductors held in electrical conducting relationship in the element, wherein the element terminates short of opposite surfaces of the dielectric material.