Detachable Electrical Contact Arrangement

Abstract

A detachable electrical contact arrangement for positioning between contact surfaces on units to form electrical connections therebetween characterized by a thin insulating sheet having contact elements disposed thereon in a predetermined pattern and the contact elements having a current path through the sheet which is not more than one millimeter in length. In one embodiment the contact elements are either elastic hollow metal spheres or elastic wire balls mounted in openings in an insulating sheet. In another embodiment the insulating sheet has a net configuration form of strips and the contact elements are metal deposits surrounding the strip or points of intersection of the strip. A third embodiment is a thin flexible metal sheet sandwiched between a pair of insulating film or sheets which metal sheet has had portions removed to provide a plurality of contact elements interconnected by connecting strips. The insulating film is provided with openings to expose the surface of the contact element and a portion of the film and connecting strips are subsequently removed to electrically isolate selected contact elements from adjacent contact elements.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a detachable electrical contact arrangement and a method for making the arrangement for providing electrical connections between contact surfaces on electrical units such as micro assemblies and wiring plates or boards.

2. Prior Art

At the present time, detachable electrical contacts comprising contact elements positioned between contact surfaces are frequently employed in high-frequency technology such as spring bands for high frequency and tight sealing screen housings or hollow waveguide flange connection and for electrically contacting timing plungers for microwave lines. These types of contacts are only suitable for connections which have large surfaces.

Another type of detachable or removable contact arrangements for connecting parallel printed circuit boards via at least one joint plate with the contacting elements or components preferably opening in the direction of the plane of the joint plate are disclosed in the German Pat. No. 1,075,691. For interconnecting contact surfaces on electrical units such as printed circuit boards, an arrangement which comprises a board sandwiched between the printed circuit boards and containing structural elements for forming the electrical connection therebetween is disclosed in the German utility or petty Pat. No. 1,891,042 patented on Apr. 16, 1964.

Another typical type of contact arrangement has a rigid plate having S-shaped contact elements which establish connections between contact surfaces of two printed circuit boards. An example of this type of arrangement is displayed in the printed German Pat. No. 1,275,170 published Aug. 14, 1968.

Each of the above arrangements for connecting assemblies and wiring plates or circuit boards has drawbacks especially when used in high-frequency applications during which the contact elements have inductivities of a certain magnitude which create disturbing effects for many applications at maximum frequencies.

SUMMARY OF THE INVENTION

The present invention is directed to a detachable electrical contact arrangement which requires minimum space and which has a lower inductivity which is desirable in high-frequency applications and the method of making the arrangement. The arrangement provides contact elements having a current path of a length not greater than 1 mm. carried on a flexible sheet of insulating elastomer material which maintains the spacing between the element while enabling flexing of the arrangement in a direction perpendicular to its plane. Embodiments of the present invention include an arrangement having elastic contact elements which are either wire balls or hollow spheres mounted in an aperture of a flexible sheet of insulation material. Another embodiment of the arrangement utilizes a netlike sheet of insulating material having openings with contact elements formed by the depositing of metal thereon. A third embodiment of the invention utilizes sheetlike contact elements laminated to a sheet of insulation material with selected contact elements electrically insulated from adjacent contact elements which are electrically connected.

Accordingly, it is an object of the present invention to provide a detachable electrical contact arrangement and method of making the arrangement in which the contact elements have a path of travel for the current of less than 1 mm.

Another object of the present invention is to provide electrical contact arrangements and method making the arrangement which has a sheet of insulating material that is flexible to allow movement of the contact elements in a direction perpendicular to the plane of the sheet while being relatively unmovable in the direction parallel to the plane of the sheet.

A still further object of the present invention is to provide an electrical contact arrangement and method of making the arrangement which has a plurality of contact elements which are electrically interconnected and selected contact elements that are electrically isolated therefrom for forming coaxial connections between units.

Other objects, features and advantages of the invention will be readily apparent from the foregoing description of the preferred embodiments taken in conjunction with the accompanying drawings, although modifications may be effected without departing from the spirit and scope of the novel concepts of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view with portions exploded for purposes of illustration of the present invention utilized for forming a connection between electrical units;

FIG. 2 is an enlarged side view of a portion of FIG. 1 illustrating the electrical connections formed by the present invention;

FIG. 3 is a plan view of the present invention illustrated in FIG. 2;

FIG. 4a is a plan view of an embodiment of the detachable electrical contact arrangement of the present invention;

FIG. 4b is an end view of the arrangement illustrated in FIG. 4a;

FIG. 5 is four views identified as A, B, C and D of a sheet metal contact element of the present invention;

FIG. 6 is four views identified as A, B, C and D of another embodiment of the sheet metal contact element of the present invention; and

FIG. 7 is a third embodiment of the arrangement of the present invention utilizing contacts such as those illustrated in FIGS. 5 and 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although the principles of the present invention are particularly useful in forming electrical connections between various electrical units, they are particularly useful in a detachable electrical contact arrangement 2 for providing electrical connections between a microelement or unit 1 and a wiring plate or circuit board 3. The detachable electrical contact arrangement 2 is disposed between wiring board 3 and the microunit 1 and the necessary pressure needed for forming the connection is provided by suitable fastening means such as the fastening elements 4.

As illustrated in FIG. 2, the microassembly 1 is provided with surface contacts 5 on a surface facing the wiring board 3 which is provided with surface contacts 6. The detachable electrical contact arrangement 2 has contact elements 7 carried on a sheet 8 of insulating material and is disposed between the contact surfaces 5 and 6 to complete an electrical connection therebetween.

The contact elements 7 are arranged on the sheet or film 8 in rows and columns with uniform spacing of the elements in the rows and between the columns to provide the desired rectangular pattern with the desired distance such as 2.54 or 1.27 mm. The film 8 has a thickness of approximately 0.0125 mm. and the contact elements 7 have a current path which is not greater than 1 mm. for connecting the contact surfaces 5 and the contact surfaces 6. The contact elements 7 are hollow metal spheres which are elastically deformable under the contact pressure and are supported or mounted within apertures in the sheet or film 8. Instead of using hollow metal spheres, wire balls can be used on the contact elements 7 and mounted in the openings in the sheet or film 8.

The sheet 8 is flexible to allow adjustment of the contact elements 7 in a direction at right angles or perpendicular to the plane of the sheet to compensate for irregularities in the surface of the unit 1 or board 3 which have the contact surfaces 5 and 6, respectively. However, the sheet 8 maintains the contact elements 7 substantially immovable in a direction parallel to the plane of the sheet 8 and maintains the contact elements in a substantially fixed spacing. Thus the sheet 8 has the characteristics of a diaphragm and enables flexing to compensate for forming a connection between a series of contact surfaces which are disposed on a nonplanar surface.

The embodiment illustrated in FIGS. 4a and b of the contact arrangement 2a utilizes the sheet 9 which has a net configuration having points of intersection between longitudinal and transverse extending strips which strips define mesh openings in the sheet. Contact elements 10 are formed at the intersections of the transverse and longitudinal strips and can be formed at points on each strip intermediate of the points of intersection. Preferably contact elements 10 are formed by depositing metal on the strips of the netlike carrier sheet 9 by a metallizing process such as soldering, welding or electrodepositing. The metal is deposited on both sides of the sheet 9 with the material on both sides being interconnected by the deposited metal of a contact element extending through the mesh openings of the film 9. To interconnect various contact elements 10, surfaces of the strips forming the netlike carrier sheet 9 can be metallized with a deposit or coating of metal extending between adjacent contact elements. As illustrated in FIG. 4, the contact elements 10a are located at points of intersection of the strips to form a frame with the contact element 10b disposed in the center of the frame. To form a contact arrangement for use in a coaxial connection, all of the contact elements 10a can be electrically interconnected by metallizing selected strips of the sheet 9 while the contact elements 10b are electrically isolated therefrom. Such an arrangement can be used in a coaxial connection with the contact element 10b forming a connection for the outer conductor and the contacts 10a, which form a module frame which can frame a rim length less than 2.54 mm. to form the connection for the outer casing or outer conductor.

A third embodiment of the detachable electrical contact arrangement 2b is illustrated in FIG. 7. The contact arrangement 2b comprises a metal film or sheet 14 having portions removed to provide a series of contacts 11 with the contacts 11a interconnected in a quadratic arrangement. Contact elements 11b are connected into the quadratic arrangement of contacts by retaining strip 17 and positioned substantially in the center of the square formed by the frame having the contacts 11a at each corner. The flexible metal sheet or plate has the thickness of approximately 0.03 mm. and is made of a flexible material such as beryllium bronze. A film or sheet of insulating material 15 having a pattern of openings or apertures 16 arranged in a pattern and spacing identical to the contact elements 11a and 11b is superimposed on the sheet 14 and laminated thereto. Preferably a second sheet of insulating material 15a is disposed on the opposite side of metal sheet 14 so that the metal sheet is laminated between a pair of insulating sheets. Subsequent to the laminating, the retaining strips 17 are removed to electrically isolate the contacts 11b from the remaining contacts 11a. The removal can be performed by a punching process, by a burning process using a laser or electron beam, or a melting process using a current pulse. The contact arrangement 2b can be used to make coaxial contact connections with the contact element 11b providing the connections for the inner conductor while the electrically interconnected contact elements 11a provide the connection for the outer conductor.

As best illustrated in FIG. 5 and 6, the contacts 11a and 11b are diagonally slotted or provided with a star-shaped slot to form a plurality of segments 12 or 12a in a frame having a rim length of 1 mm. As illustrated in FIG. 5, the segments 12 are bent in opposite directions so that adjacent segments extend outwardly in opposite direction from the plane of the contact element 11 to ensure the formation of a good electrical connection when the contact arrangement 2b is inserted between the contact surfaces on the wiring board 3 and microunit 1.

Instead of bending the segments 12 out of the plane of the contact 11, it is preferred to provide lumps or projection 13 of metal on the segments 12a. The lumps or projections can be formed by a metallizing process such as electrodepositing, solder or welding. The projections or lumps 13 are positioned so that adjacent lumps are extending in opposite directions from the plane of the contact 11. Gold is the preferred material for forming the lumps or projections and preferably is the material used in forming the contact surfaces such as 5 and 6 on the electrical units.

The amount of set in the bent segment 12 of the contact element illustrated in FIG. 5 and the height of the projection 13 in the element of FIG. 6 should be sufficient so that the segments 12 and 12a are deflected when the arrangement 2b is forming an electrical connection. However, the amount of deflection occurring during the forming of the electrical connection should not plastically deform the segments 12 and 12a to cause a permanent set therein. A contact pressure of ten ponds (Gram force) has been found sufficient to obtain a good electrical connection without plastically deforming the segment 12 and 12b. While forming the connection, the frictional movement of the segment 12 or projection 13 of the contact elements on the contact surfaces provides a self-cleaning of the contact elements and contact surface which is beneficial to the formation of a good electrical connection.

Although various minor modifications may be suggested by those versed in the art, we wish to include within the scope of the invention all such improvements which reasonably come within the contribution to the art.

Claims

We claim as our invention:

1. A detachable electrical contact arrangement for disposing between units such as microassemblies and wiring plates each of which has electrical contacts on a surface facing the other unit for forming electrical connections therebetween particularly a multipole connection, said arrangement comprising a sheet of insulating material having electrical contact elements arranged thereon in a predetermined pattern, said contact elements being formed in a flexible plate secured to said sheet, said plate being provided with two or more slots to form segments with alternate segments projecting in opposite directions from the plane of the plate to provide a current path through said sheet of a length less than one millimeter, and said sheet having characteristics so that the contact elements are movable in a direction at right angles to the plane of the sheet to enable adjusting during formation of a connection and are substantially unmovable in a direction parallel to the plane of the sheet.

2. A detachable electrical contact arrangement according to claim 1, wherein the tip of each of the segments is provided with deposits of contact material extending in the direction of the contact surfaces.

3. A detachable contact arrangement according to claim 2 wherein the deposits of contact material are provided by electroplating, soldering or welding.

4. A detachable electrical contact arrangement for disposing between units such as micro assemblies and wiring plates each of which has electrical contacts on a surface facing the other unit for forming electrical connections therebetween particularly a multipole connection, said arrangement comprising a sheet of insulating material having electrical contact elements arranged thereon in a predetermined pattern, said contact elements providing a current path through said sheet of a length less than one millimeter, one of said contact elements being a connector for an inner conductor of the coaxial connection and the adjacent contact elements surrounding said one element being interconnected electrically to provide a connection for the outer conductor of the coaxial connection, and said sheet having characteristics so that the contact elements are movable in a direction at right angles to the plane of the sheet to enable adjusting during formation of a connection and are substantially unmovable in a direction parallel to the plane of the sheet.