Electrical Connectors

Abstract

An electrical connector capable of interconnecting individual electrical contacts of a first row of contacts with corresponding electrical contacts in a second row of contacts spaced apart from and substantially parallel to the first row, the connector including a support member of a resilient electrically insulating material, and a plurality of substantially C-shaped electrically conductive members formed around and secured to the support member. The C-shaped members are spaced apart along the length of the support member at a pitch which is equal to the pitch of the electrical contacts of the said rows. In an electrical interconnection system, the electrical connector is interposed between superposed electrically insulating boards on which the first and second rows of contacts are carried, the insulating boards and the electrical connector being clamped together by at least one spring clip.

Description

The invention relates to electrical connectors, to methods of producing the electrical connectors, and to electrical interconnecting arrangements which utilise the electrical connectors for the electrical interconnection of opposed sets of electrical contacts that are carried by superposed electrically insulating boards.

In known electrical interconnecting arrangements it is normal to provide a plurality of superposed electrically insulating boards which carry on each side a set of electrical contacts which are associated with the elements, or devices carried by the boards and which facilitate the making of electrical connections thereto. The electrical interconnections between opposed sets of electrical contacts associated with adjacent insulating boards can be effected in a number of ways, for example in a manner as outlined in our co-pending U.S. Pat. application No. 1345/70 wherein a set of electrical printed circuit conductors carried by a flexible substrate is soldered at one end to printed circuit contacts carried by an electrically insulating board, and wherein the sets of electrical printed circuit contacts of the flexible substrates associated with adjacent electrically insulating boards are clamped together in electrical contact with each other by means of one or more spring clips. In general, the known electrical interconnecting arrangements are, due in the main to component tolerance difficulties, not suitable for the interconnecting of electrical contacts with a spacing therebetween of less than 0.030 inches.

The invention provides an electrical connector capable of interconnecting individual electrical contacts of a first row of contacts with corresponding electrical contacts in a second row of contacts spaced apart from and substantially parallel to the first row, the connector including a support member of a resilient electrically insulating material; and a plurality of substantially C-shaped electrically conductive members formed around, and secured to the support member, the C-shaped members being spaced apart along the length of the support member at a pitch which is equal to the pitch of the electrical contacts of the said rows. This connector is suitable for the interconnecting of electrical contacts with a spacing therebetween of smaller than 0.001 inches.

The invention also provides a method of producing an electrical connector capable of interconnecting individual electrical contacts of a first row of contacts with corresponding electrical contacts in a second row of contacts spaced apart from and substantially parallel to the first row, the method including the steps of providing a support member of a resilient electrically insulating material; forming a spiral of an electrically conductive material around, and along the length of the support member such that it is securely attached thereto, the pitch of the spiral being equal to the pitch of the electrical contacts of the said rows; and completely severing each turn of the spiral to provide a plurality of substantially C-shaped electrically conductive members which are spaced apart along the length of the support member.

The invention further provides an electrical interconnecting arrangement for interconnecting individual electrical contacts of a first row of contacts with corresponding electrical contacts in a second row of contacts spaced apart from and substantially parallel to the first row, the first and second rows of contacts being carried by superposed electrically insulating boards, the arrangement including an electrical connector as outlined in a preceding paragraph interposed between the first and second rows of contacts such that the C-shaped members thereof are in register with the rows of contacts; and at least one spring clip for clamping together the insulating boards and the electrical connector.

The foregoing and other features according to the invention will be better understood from the following description with reference to the accompanying drawings, in which:

FIGS. 1 to 5 diagrammatically illustrate the various stages of the methods of producing an electrical connector according to the invention,

FIG. 6 diagrammatically illustrates in a cross-sectional side elevation a partly completed electrical connector according to the invention,

FIGS. 7(A) and 7(B) diagrammatically illustrate respectively in a cross-sectional front elevation and side elevation part of an electrical interconnecting arrangement according to the invention.

FIG. 8 diagrammatically illustrates in a pictorial view another part of an electrical interconnecting arrangement according to the invention, and

FIG. 9 diagrammatically illustrates in a side elevation an electrical interconnecting arrangement according to the invention.

The first stage of the methods of producing an electrical connector according to the invention involves the provision of a support member of a resilient electrically insulating material of a length at least equal to the length of a surface of a substrate which carries the electrical contacts to which it is desired to make electrical connections. The support member is preferably of circular cross-section although cross-sections which are other than circular, for example square or rectangular, can, as will be subsequently outlined, be utilised. In practice, the diameter of the support member is not critical but for an electrical connector utilised to interconnect contacts with a spacing therebetween of the order of 0.020 inches, the diameter can conveniently be of the order of 0.125 inches.

The next stages in the production method for a support member of circular cross-section are diagrammatically illustrated in FIGS. 1 to 5 of the drawings.

Referring to FIG. 1, a spiral groove 1 is cut in the periphery of the support member 2 along its entire length by any known technique. The pitch of the groove 1 is made equal to the spacing between the centres of the electrical contacts that are to be interconnected. The width of the groove 1 is of the order of one half of the contact centre spacing and the depth of the groove should preferably be equal to or less than one half of its width.

A wire 3 of an electrically conductive material and of a diameter which is comparable with the width of the groove 1, is then anchored by any suitable means to one end of the support member 2 and is wrapped around the support member such that it is located by and lies in the groove 1 to give the structure diagrammatically illustrated in FIG. 2 of the drawings. The free end of the wire 3 is then anchored by any suitable means to the other end of the support member 2.

The wire 3 is then permanently attached to the support member 2, along its entire length in a manner diagrammatically illustrated in either FIG. 3 or FIG. 4 of the drawings.

With the method of attachment according to FIG. 3, longitudinally extending grooves 4 are cut in the periphery of the support member 2 along its entire length by any known technique prior to the wire wrapping operation. A suitable glue 5 is then applied to the grooves 4 at appropriate points along the length of the support member 2 such that on completion of the wire wrapping operation and when the glue 5 sets, the wire 3 is permanently attached at these points to the support member 2.

With the method of attachment according to FIG. 4, the support member 2 and wire 3 are partially embedded in a block 6 of an electrically insulating potting material such as an epoxy base resin, which will be in a liquid state before it sets to form the block 6. The shape of the block 6 is determined by a mould 7. In practice, the mould 7 will be such that the entire length of the wire wrapped section of the support member 2 can be accommodated therein, and such that the support member 2 can be supported in the desired position whilst the embedding material is in an initial liquid state. Whilst the embedding material is in the liquid state it will, due to capillary attraction, partially fill the gaps between successive turns of the wire 3.

This method of attachment can be aided by the utilisation of a hollow support member 2 which is open ended. With this arrangement the embedding material when in its liquid state will flow into the bore of the hollow member 2 from the open ends thereby embedding completely part of the wall of the hollow member and giving a more secure fixing of the hollow member to the block 6.

When the embedding material sets to form the block 6, the mould 7 is removed.

As a further alternative the wire 3 can be permanently attached to the support member 2 by ultrasonic bonding.

In an alternative method of producing the electrical connector, the provision of the groove 1 in the support member 2 can be eliminated by utilising two wires of approximately equal diameter but of different materials, one of the wires being suitable for forming the C-shaped electrically conductive members in a manner to be subsequently outlined. With this method the two wires are anchored at one end of the support member 2 and are then simultaneously wrapped around the periphery, and along the length of the support member 2 such that the turns of the two wires are in an abutting relationship. The free ends of the wires are then secured to the other end of the support member 2. Successive turns of the wire from which the C-shaped members are to be formed are, therefore, always separated by a turn of the other wire; therefore, the sum of the diameters of the two wires should be equal to the spacing required between the contact centres. The other wire is selected such that it can be dissolved away preferentially by a chemical process after the wires have been permanently attached to the periphery of the support member, for example in a manner as illustrated in FIG. 3 of the drawings. The glue that is utilised to effect the attachment and the material of the support member 2 must, therefore, be such that they are not affected by the chemical process.

In another alternative method of producing the electrical connector, the spiral of an electrically conductive material is formed around, and along the length of the support member 2 by the selective deposition of an electrically conductive material by any known technique onto the periphery of the member 2. The selective deposition being effected by masking the periphery to expose only a spiral strip thereof of the desired width and pitch. Alternatively, the whole surface area of the periphery could be exposed to the deposition process and the spiral formed by a machining operation which would remove the unwanted electrical conductive material.

On completion of the wire attachment or formation stage, each turn of the spiral is completely severed to provide a plurality of substantially C-shaped electrically conductive members. This can be achieved in a number of ways, for example in a manner as illustrated in FIGS. 5(A) and 5(B) wherein a longitudinally extending radial slot 8 is cut into the support member 2 and thereby through each turn of the spiral to provide the substantially C-shaped members 9. The shape of the slot is not critical, it could for example be V-shaped, providing the turns of the spiral are completely severed.

Alternatively, each turn of the spiral can be completely severed by removing, by any suitable machining operation, those parts of the support member 2 and spiral on the left-hand side of the broken line 10 in FIG. 5(A).

With the electrical connector construction of FIGS. 5(A) and 5(B) the application of a force in the directions indicated by the arrows X will cause the C-shaped members 9 and the gap between the free ends of the adjacent members 9 to close slightly and the natural compliance of the underlying resilient support member 2 will enable the members 9 to resume their original shape when the force is removed.

An electrical connector having a support member of square cross-section is diagrammatically illustrated in a cross-sectional side elevation in FIG. 6 of the drawings. With this connector, an interrupted spiral groove is cut around and along the length of the support member 2 i.e., the depth of the groove is arranged such that the groove is contained in only the corner sections of the support member 2. When the wire 3 is wrapped around and along the support member it is located by the groove and is such that a gap 18 is provided between each face of the support member and the wire. By utilising a resilient electrically conductive material such as beryllium copper for the wire 3, the gaps 18 will allow the wire 3 to be compressed when the connector is in use.

The attachment of the wire 3 to the square support member 2 and the severing of the turns of the wire spiral can be effected by any one of the techniques outlined in preceding paragraphs.

An electrical interconnecting arrangement which utilises the electrical connector of FIGS. 5(A) and 5(B) is diagrammatically illustrated in FIGS. 7(A) and 7(B) respectively in a cross-sectional front elevation and a cross-sectional side elevation through Y-Y. In this interconnecting arrangement the electrical connector is sandwiched under pressure between two superposed electrically insulating boards 11 of say a plated-wire memory stack assembly, and is used to interconnect the electrical contacts such as the contacts 4, 5 and 6 which are carried by each of the boards 11 and which are in the case of a memory stack assembly associated with the memory elements and facilitate the making of electrical connections thereto. In practice, the electrical contacts would be printed circuit contacts having, in the case of a memory stack assembly, a spacing between contact centres of less than 0.030 inches but greater than 0.0012 inches. It should, however, be noted that the electrical connector can be used to interconnect contacts with a spacing therebetween of greater than 0.030 inches or smaller than 0.0012 inches.

Three C-shaped electrical conductive members 9a, 9b and 9c are illustrated in FIG. 7(A) which are respectively used to interconnect the pairs of electrical contacts 4, 5 and 6 in the manner indicated. It should be noted that for successful interconnection to be effected it is essential for the electrical contacts of one of the boards 11 to be offset with respect to the electrical contacts on the other one of the boards 11 by an amount equal to one half of the pitch of the wire spiral.

Slight variations which occur in practice in the heights of the electrical contacts can be accommodated by the pliancy of the resilient support member 2 which also enables the connector to conform to the profile of the printed circuit boards 11 even when they are bowed.

Accurate register of the C-shaped members with the electrical contacts being interconnected can only be achieved by the utilisation of locating means associated with the support member 2 and the superposed boards on which the contacts are formed or supported. A tolerance in lateral location between the various parts of the arrangement of .+-. 0.002 inches can be accommodated for contacts spaced at intervals of 0.020 inches or greater, whereas a location tolerance no greater than 0.0003 inches is advisable for contacts spaced at intervals of 0.0012 inches. The locating means which can take many different forms, may typically be provided by the arrangement diagrammatically illustrated in FIG. 8 of the drawings in a pictorial view. This locating means which would be provided at each end of the support member includes a member 12 which is connected to or forms an integral part of the support member, and which has two apertures 13 therein, and two pin members 14 which are each secured at one end to a separate one of the superposed boards 11. The pin members 14 are located in the apertures 13 when the connector is sandwiched between the boards 11 thereby accurately registering the C-shaped members of the electrical connector with the electrical contacts carried by the boards 11.

The contact force between the various members can, as is diagrammatically illustrated in FIG. 9 of the drawings, be effected by two locking springs 15 which also effectively prevent the interconnecting arrangement from "rocking" or "see-sawing."

As illustrated in FIG. 9 one of the boards 11 can be a so-called take-off member having terminal pins, such as the pin 16, associated with the electrical contacts 17 carried by the board. In practice, the electrical contacts 17 will each be connected to a printed wire which is formed on the board, and which extends in a direction normal to the plane of the drawing. The terminal pins are set into the back of the board and make contact through the board with the printed lead wires such that one terminal pin is connected to one printed wire and thereby to one electrical contact 17. The position of the terminal pins along the length of the lead wires are staggered from lead wire to lead wire so that the distance between them are large enough to enable conventional connection techniques, for example, wire wrapping, or crimping, or soldering techniques, to be employed in the connecting of wires, such as the wire 19, to the appropriate terminal pins. Alternatively, instead of using terminal pins, the lead wires would be extended into a flexible wiring strip.

It can, therefore, be seen from the foregoing that the electrical interconnecting arrangements outlined in the preceding paragraphs are readily demountable after the original assembly, and are capable of being re-assembled at a later time. The voltage that can be withstood between adjacent electrical contacts and adjacent C-shaped members will be dependent upon the contact separation and the electrically insulating materials that are utilised. It is thought that with known materials and contacts having a spacing of 0.0012 inches between centres that it is possible to apply potential differences of the order of 50 volts between adjacent conductors.

It will of course be appreciated that the contact surfaces of the component parts utilised in the interconnecting arrangements will employ conventional contact materials. For example the C-shaped members can be of gold or a gold plated material.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation in its scope.

Claims

What we claim is:

1. An electrical connector capable of interconnecting individual electrical contacts of a first row of contacts with corresponding electrical contacts in a second row of contacts spaced apart from and substantially parallel to the first row, the connector including a support member of a resilient electrically insulating material; and a plurality of substantially C-shaped electrically conductive members formed around, and secured to the support member, the C-shaped members being spaced apart along the length of the support member at a pitch which is equal to the pitch of the electrical contacts of the said rows, each of the C-shaped members being located in a spiral groove in the periphery of the support member, the spiral groove being of a pitch equal to the pitch of the electrical contacts of the said rows, wherein the support member has a number of longitudinally extending grooves in the periphery thereof, and wherein a glue contained in the longitudinally extending grooves secures each of the C-shaped members to the support member.

2. An electrical connector as claimed in claim 1 wherein the support member and the C-shaped members are partially embedded in a block of an electrically insulating material.

3. An electrical connector as claimed in claim 2 wherein the support member is of hollow section and open-ended, part of the wall of the hollow support member, along the entire length thereof, being embedded in the electrically insulating block.

4. An electrical connector as claimed in claim 1 wherein the support member is of square cross-section, and wherein the C-shaped members are each located in an interrupted spiral groove, the spiral groove being contained in the corner sections only of the support member.

5. An electrical interconnecting arrangement for interconnecting individual electrical contacts of a first row of contacts with corresponding electrical contacts in a second row of contacts spaced apart from and substantially parallel to the first row, the first and second rows of contacts being carried by superposed electrically insulating boards, the arrangement including an electrical connector as claimed in claim 1 interposed between the first and second rows of contacts such that the C-shaped members thereof are in register with the rows of contacts; and at least one spring clip for clamping together the insulating boards and the electrical connector.

6. An electrical interconnecting arrangement as claimed in claim 5 wherein the electrical connector includes locating means at each end thereof for effecting registration of the C-shaped members with the first and second rows of contacts.