Contact arrangement

[0002] 1. Field of the Invention

[0003] The invention relates to a contact arrangement for electrical connection of a large number of first electrical contact points, which are arranged on an essentially planar surface of a first substrate, having a corresponding number of second electrical contact points which are arranged on an essentially planar surface of a second substrate, including a flat insulating body in which holes are formed in the grid size of the first and second contact points, through each of which holes, which is in the form of a plated-through hole, an electrical conductor passes, and contact elements which are electrically connected to the respective plated-through hole are attached to the hole ends on both sides of the insulating body.

[0004] 2. Description of the Prior Art

[0005] Highly complex electrical components such as processors in some cases have hundreds of contact points which have to be electrically connected to corresponding mating contacts, for example on a printed circuit board. It is known for these contact points to be provided in the form of a so-called Land Grid Array (“LGA”). In this case, contact points are arranged in a regular grid size on an essentially planar contact surface. They are connected to the corresponding mating contact elements on a printed circuit board or on another component by means of a contact arrangement as mentioned initially, rather than by soldering. In a contact arrangement of the type mentioned initially which is marketed by the company CINCH and is known of the Company Document “CIN::APSE” of the company LABINAL COMPONENTS & SYSTEMS Inc. CINCH CONNECTOR DIVISION, U.S.A., button contacts are arranged in the holes in the insulating body, which button contacts include a tangle of thin conductive wire and project by a small amount beyond the insulating body at the hole ends. This contact arrangement is inserted between the mutually opposite contact points. The two substrates for the contact points are then mechanically pressed against one another. The elasticity of the wire tangle of the individual button contacts produces a reliable electrical connection between the mutually opposite contact points on the two substrates. A comparable contact arrangement is likewise described in U.S. Pat. No. 5,196,320.

[0006] A contact arrangement of the known type is extraordinarily complex to manufacture. The button contacts have a diameter of about 0.5 to about 1 mm. Their production and the insertion of the button contacts into the holes in the insulating body are thus tedious.

[0007] The invention is based on the object of specifying a contact arrangement of the type mentioned initially which, on the one hand, allows reliable contact between the mutually opposite contact points and, on the other hand, can be produced cheaply and easily.

[0008] This object is achieved according to the invention in that the contact elements are formed by a sheet of conductive material, and in that the hole ends are surrounded at a distance by depressions on both sides of the insulating body, in which depressions projections of the contact elements engage.

[0009] The plated-through holes can be produced electrochemically in one process step. The contact elements can likewise be attached to the two sides of the insulating body in one process step. This avoids the tedious insertion of the millimeter-size button contacts composed of a wire tangle or wire mesh into the holes in the insulating body.

[0010] The contact elements preferably include sections of a contact element mat which are separated from one another. The contact elements can thus be produced together in a simple manner, for example from a sheet of spring bronze, and can be aligned on the insulating body and attached to it, as will be explained in more detail further below.

[0011] The attachment process is carried out mechanically by the hole ends being surrounded at a distance by depressions on both sides of the insulating body, in which depressions projections of the contact elements engage.

[0012] In the region of the holes, the contact elements preferably have contact tongues, which are bent out of the plane in the region of the holes, so that the spring effect of these contact tongues ensures a reliable electrical connection between the mutually opposite contact points.

[0013] A contact arrangement of the type mentioned above can be produced in a simple manner, so that holes are first of all produced in a flat insulating body in the grid size of the contact points and each are provided with through-plating, so that a contact element mat is placed on each of the two sides of the insulating body so that the contact elements each cover one hole, and so that the contact elements are separated from one another and are connected to the insulating body in one process step. In this case, the projections on the contact elements mentioned above are pressed into the depressions which surround the holes, such that the projections mechanically grip against the walls of the depressions.

[0014] The contact element mats may be produced by stamping or etching.

[0015] FIG. 1 shows a schematic side sectional through two substrates of contact points and a contact arrangement according to the invention arranged between them, which contact arrangement is intended to produce the electrical connection between the contact points.

[0016] FIG. 2 shows a top view of a corner region of an insulating body of the contact arrangement.

[0017] FIG. 3 shows a section through the insulating body shown in FIG. 2, along the line III—III in FIG. 2.

[0018] FIGS. 4 and 5 show illustrations of the insulating body corresponding to FIGS. 2 and 3, respectively, once the plated-through holes have been produced.

[0019] FIG. 6 shows a top view of a corner region of a contact element mat.

[0020] FIG. 7 shows a side sectional view through an individual contact element along the line VII—VII in FIG. 6.

[0021] FIG. 8 shows a top view, corresponding to FIGS. 2 and 4, of an insulating body having two contact elements mounted on it.

[0022] In FIG. 1, two substrates are denoted by 10 and 12, and each have a large number of contact surfaces 18 and 20, respectively, on their mutually facing planar surfaces 14 and 16, respectively. The diameter and the distance between the contact surfaces 18 and 20, respectively, is approximately about 1 mm, so that the contact surfaces 18 and 20 are referred to in the following text as contact points, due to their small extent. Several hundred of these contact points 18 and 20, respectively, are arranged in a regular grid size on each of the surfaces 14 and 16. The first substrate 10 may be an electronic component, for example a processor, while the second substrate 12 may be a printed circuit board to which the component 10 is intended to be fitted.

[0023] The electrical connection between the contact points 18 on the substrate 10 and the contact points 20 on the substrate 12 is produced by a contact arrangement which is denoted in general by 22 and which will be described in more detail in the following text.

[0024] The contact arrangement 22 includes an insulating body 24 in the form of a thin plate (FIGS. 2 and 3) in which bores or holes 26 are formed which pass all the way through in an arrangement corresponding to the grid arrangement of the contact points 18 and 20. The holes 26 are each located in an area of a grid which is formed by grooves 28 (which cross one another at right angles) in the two surfaces of the insulating body 24. Each hole 26 is surrounded by an annular cutout 30, which projects outward in four short channels 32. In other words, there are four projections 34 in the four corners of each area, which surround the hole 26 at a distance from it and are separated from one another by the channels 32. The insulating body 24 described so far may be produced as a plastic injection-molded part.

[0025] In a first method step, the holes 26 are provided with through-plating 36 (FIGS. 1 and 5). This forms a conductive layer 38 which covers the hole wall and continues on both sides of the insulating body 24 in a ring 40 surrounding the hole 26. A contact element mat or sheet 42, which is shown in FIG. 6, is now placed onto both sides of the insulating body 24 prepared in this way.

[0026] This contact element mat or sheet 42 is composed of a conductive material, for example of a springy bronze material, and includes a supporting frame 44 within which contact elements 46 are formed in an arrangement and quantity corresponding to the hole pattern of the insulating body 24, and these contact elements 46 are connected to one another and to the supporting frame 44 via material links 48. Such a contact element mat can be produced, for example, by stamping or etching.

[0027] Each material link 48 is located on a radial projection 50 which, for its part, has two pointed claws 52 pointing toward opposite sides. The center part of each individual contact element 46 has a circular cutout 54 into which two mutually parallel spring tongues 56 project in opposite directions and which, once the contact element mat 42 has been produced, project out of its plane, as is shown in FIG. 7.

[0028] Once the contact element mat 42 has been placed on the insulating body 24 that is provided with the plated-through holes 36, so that the contact elements 46 are located exactly above the grid areas of the insulating body 24 which contain the holes 26, the material links 48 are cut and the projections 50 of the individual contact elements 46 are pressed, in a single process, into the channels 32 between the projections 34, using a stamping and pressing tool (which is not illustrated), so that the projections 50 are hooked onto the pointed claws 52 on the walls which bound the channels 32. The contact elements 46 are in this way firmly attached to the insulating body 24 and rest on the rings 40 of the respective plated-through hole 36. If the substrates 10 and 12 are now pressed against one another with the contact arrangement 22 located between them, then, in conjunction with the respective plated-through hole 36, the contact elements 46 produce a conductive connection between the respective mutually opposite contact points 18 and 20. The spring tongues 56, which are bent outward, in this case ensure that reliable contact is made at the same time with all contact points.

[0029] In the contact arrangement according to the invention, the conductor length between two mutually associated contact elements is very short. The electrical connection has low induction and capacitance levels. The contact arrangement is extremely flexible in use, with different distances between the contact points which are to make contact with one another, that is to say it is virtually irrelevant for the production of the electrical connections whether the insulating body is somewhat thicker or thinner. Furthermore, the contact arrangement according to the invention can be produced several orders of magnitude more cheaply than the known solution described initially, in which a specific contact button must be inserted into each hole and it is necessary to ensure that this contact button projects out of the hole by a certain amount on both sides.

[0030] Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.