GB2048582A - Multiple-lead electrical connector - Google Patents

Abstract

A series of contact pads 13 on the edge of a printed circuit board 11 is interconnected with respective terminals 15 by a flexible connector 17 comprising a preferably woven sheet 18 which carries conductive strips 20 composed preferably of metal particles in a rubber binder. Strips 20 incorporate a conductive adhesive or are covered by a conductive adhesive 21, the strips being separated by an insulating adhesive 19 which serves to attach the connector sheet 18 to the board 11 while the adhesive 19 connects the strips 20 to the pads 13. <IMAGE>

Description

SPECIFICATION Multiple-lead electrical connector The present invention relates generally to an electrical connector, and, more particularly, to an electrical connector for making connection to flatsurfaced contact areas such as are found on printed circuit boards, liquid crystal displays and the like.

A long-standing and difficult problem in the electronic fabrication art has been that of effecting interconnections to a printed circuit board or a liquid crystal display, where the interconnections are abie to withstand the shocks and vibrations encountered during manufacture and use. A printed circuit board typically includes an insulative base or substrate on which are mounted various electronic components, all interconnected by wire and/or deposited leads on the substrate. Terminals for interconnecting the printed circuit board with other apparatus conventionally consist of a plurality of flat-surfaced, deposited pads or lands formed along one or more edges of the board.

Prior connectors for making interconnection with the terminals of such boards have consisted of metallic springlike members clamped onto the circuit board edge margin effecting contact with the terminal pads through spring action. These spring metal connectors have not been completely satisfactory from several standpoints, the first of which being that they tend to develop loose connections with the terminal pads. This is primarily the result of the relatively low amount of spring pressure that has to be used per contact since such connectors usually include means for providing a large number of individual connections (e.g., as many as 40 is not uncommon). That is, to keep the total magnitude of the connector insertion force within a manageable range, the spring pressure of each contact must be kept low.Not infrequently, one or more of the connector spring contacts becomes bent during fabrication or assembly resulting in either failure to connect or the creation of a "high -resistance" connection, both of which are undesirable.

In an effort to insure the achievement of good and reliable connection using a spring connector, these connectors are sometimes secured in place through the use of an epoxy or other suitable adhesive material. However, when this is done, the connectors cannot be removed without substantial risk of destroying the connector, the board, or both.

Summary of the invention The connector of this invention includes a resilient, flexible, insulative base or substrate having an insulative adhesive on a major surface thereof. A plurality of conductors are arranged in mutually spaced relationship on the adhesive surface of the resilient substrate. The conductors are of predetermined arrangement to permit individually contacting a corresponding number of terminal pads on, say, a printed circuit board to which interconnection is desired to be made. The material forming the conductors preferably includes an electrically conductive adhesive incorporated therein for providing conductive securement between the conductors and terminal pads. Optionally, the conductive adhesive may be applied as a separate coating or film onto the conductors.

In use, part of the connector is pressed onto the edge of the printed circuit board so that the conductors thereof are adhesively interconnected one-forone to the terminal pads on the board. The remainder of the connector is then pressed onto another set of terminal pads of, say, another board, other electrical circuits of equipment, or other components.

Description ofthe drawing Figure 1 is a perspective view of a connector of this invention shown interconnecting a circuit board to other apparatus.

Figure 2 is an enlarged plan view of a connector made in accordance with this invention.

Figure 3 is a sectional, elevational view taken along the line 3-3 of Figure 1.

Figure 4 is a perspective view of the connector formed into a roll.

Figure 5shows a connector strip removed from the roll of Figure 4.

Figure 6 is a sectional, elevational view taken along the line 6-6 of Figure 5.

Description of preferred embodiments With reference now to the drawings, and particularly Figure 1, a printed circuit board to which interconnections are to be effected in accordance with the subject invention is identified generally as at 10 and is seen to include generally rectangular insulative base 11 on which a microcircuit, discrete components or the like represented schematically as at 12, are mounted and interconnected in accordance with the circuit desired. The printed circuit board 10 is conventionally interconnected with other circuit boards or other electrical apparatus via terminals arranged along the board edge margin and consisting of a plurality of deposited, flatsurfaced conductive pads 13. These pads or lands can be formed in a number of known ways such as, for example, silkscreening and vacuum deposition.

The base or substrate 11 can be constructed of glass, ceramic or other good insulative material possessing sufficient rigidity to serve as a circuit base.

Although interconnections may be accomplished between the printed circuit board 10 and other electrical apparatus of great variety, for convenience, the connector of this invention will be described as effecting connections with liquid crystal display 14 on which the board 11 rests, which display has a set of connection pads 15 on one of its edges of respective spacing the same as that of pads 13. It is to be noted that the circuit board pads 13 are on a different level from the liquid crystal display pads 15 with a right angle step or shoulder 16 therebetween.

With reference now additionally to Figure 2, the connector 17 includes a generally rectangular strip 18 of insulative material which is highly flexible and resilient as, for example, a woven textile material.

On a major surface of the strip 18 there is provided an insulative adhesive layer identified as at 19. A plurality of elongated, generally parallel conductors 20 are arranged to extend completely across the narrow width of the strip in mutually spaced relationship. Preferably, the conductors 20 are conductive, adhesive and flexible so that, as will be more particularly shown later, in use the entire connector may be flexed or formed about a sharp corner or be submitted to wide range of deformations without destroying or substantially impairing the conductive characteristics of the conductors. That is, it is preferred that the conductors 20 be constructed of a material that incorporates a conductive adhesive that form the desired adhesive film 21 on the outer surface when the conductor is laid down on the strip 18.

Optionally, conductors 20 may be separately coated with a conductive adhesive to form the adhe sivecoating orfilm 21.

In use, the described connector is laid onto the printed circuit board 11 with a portion of the connector overlying the set of terminal pads 13.

Pressure is then applied onto the connector so that the conductors 20 adheringly contact corresponding pads and the insulative adhesive 19 secures the substrate 18 to the non-conductive board 11 lying between and adjacent to the pads 13. The connector is then shaped to fit into the corner 16 adheringly contacting the edge of the board 11 and immediately adjacent parts of 14. Finally, the remainder of the connector 17 is pressed into contact with the pads 15 on the display 14thereby providing the desired interconnection between respective pairs of pads 13 and 15. When in final operative relation, as shown in Figures 1 and 3, the connector is anchored in position over the pads and adjacent insulative portions of the boards 11 and 14 through combined effect of the insulative adhesive 19 and the condud- tive adhesive 21.If it becomes necessary to remove the connector, it can be simply peeled off with no deleterious effect to either the underlying pads or the boards, and the same connector or a new one may be applied as before.

Although other materials may be found useful, it is considered that a cloth or other woven textile is best for constructing the connector substrate 18 in that repeated and extreme bending or deformation does not destroy it; and it also does not have a memory (as certain plastic materials do) which could provide so-called "creep" tending to break electrical connections completely or form an undesirable highresistance connection. An alternative material which may be found suitable for this purpose is a plastic, such as Mylar (Registered Trade Mark), which is resilient and can be readily coated with adhesives.

An excellent material for making the conductors 20 that has both the qualities of conduction and conductive adhesiveness, is a silver filled polymer manufactured and sold by Emerson & Cuming, Inc.

of Canton, Massachusetts 02021. This conductive adhesive has good qualities of conduction, is both resilient and flexible and maintains a surface tackiness or conductive adhesive property after setting up for purposes already described. Using this material, the conductors may be formed in any number of different ways, such as by silk-screening, brushing, roller coating, spraying, or dipping, all of which are well-known production techniques. It is important to emphasize that conductors formed by this material are highly flexible permitting substantial deformation of the final product carrying conductors made therefrom without destroying the conductors or causing separation of the conductors from the substrate on which they are laid.

As an alternate, there is a silver paint sold by Micro-Circuits Company of New Buffalo, Michigan, under the trade designation SC18-0.04 consisting of silver particles suspended in a resilient rubber carrier which can be used to make the conductors 20.

A resilient conductive epoxy made commercially available by Micro-Circuit Company of New Buffalo, Michigan, can be applied directly over these conductors to form the desired conductive layer, coating or film 21.

There is provided in accordance with the practice of the present invention, a connector which establishes interconnection between terminals quickly and easily, and is inexpensive and simple to manufacture. It is also an advantage of the described connector that it easily conforms to surface or object irregularities, or relative arrangements of the circuit apparatus to be interconnected without requiring change in the shape, construction, or manner of operation of the connector. For example, if it should be desired that two circuit boards to be interconnected should be arranged at 90" to one another, the same connector strip could be used, the inherent flexibility and resilience of the strip easily accommodating the 90" flex without suffering any impairment of function or operation.

Although as described above, the connectors 17 can be made individually according to the final size desired, it is also contemplated that the connector strip may be made in the form of a large rectangular sheet 22 with the conductors extending parallel to the long edges, and when it is desired to provide an individual connector, the desired amount of connector may be merely cut off the end of the sheet (Figure 4). The sheet 22 may also be formed into a roll 23 for storage and ease of use, if desired. Preferably, the sheet would include an insulative protective layer 24 provided over the conductors and peeled off when the connector is to be used.

Claims (12)

1. A multiple lead connector for interconnecting corresponding pairs of relatively flat conductive pads, comprising: a flexible resilient extent of an insulative material having a flat surface; an insulative adhesive covering said flat surface; a plurality of flexible and resilient conductors adhered to the flat surface of said insulative material in mutually spaced relation; and a layer of conductive adhesive material covering each of said conductors.

2. A multiple lead connector as in claim 1, in which said insulative material is a woven textile.

3. A multiple lead connector as in either of claims 1 or 2, in which said conductors are constructed of silver metal particles suspended in resilient rubber.

4. A multiple lead connector as in either of claims 1 or 2, in which said conductive adhesive material is a conductive epoxy.

5. A multiple lead connector as in claim 1, in which there is further provided a removable protective layer adhered over the conductors and peelable therefrom prior to use.

6. Means for interconnecting first and second spaced conductive pads with irregularly surfaced insulative material intervening said pads, comprising: a resilient, flexible woven, insulative fabric base having a flat surface; a layer of insulative adhesive on said flat surfaces; a resilient, flexible conductive member adhered to said base flat surface, said member being constructed of metal particles suspended in a flexible resilient carrier; and a conductive adhesive applied to the exposed surface of said conductive member on the base flat surface; said means being adapted for removable emplacement over said first and second conductive pads and intervening insulative material surface with the conductive member being conductively adhered to said pads and said intervening surface.

7. Means as in claim 6, in which said metal particles are silver and said carrier is rubber.

8. An electrical connector, comprising: a flexible insulative strip; an insulative adhesive covering a portion of said insulative strip; and a plurality of flexible conductors adhered to the insulative adhesive on said strip in mutually spaced relation, each of said conductors having an outer surface that is conductively adhesive.

9. An electrical connector as in claim 8, in which said insulative material is a woven textile.

10. An electrical connector as in either of claims 8 or 9, in which said conductors are constructed of a metal filled polymer that is both conductive and has an outer surface that is conductively adhesive.

11. Means for electrically interconnecting first and second spaced terminal pads, comprising: a flexible insulative base; a flexible conductor adhered to a surface of the base, said conductor being constructed of a material providing the conductor with a conductively adhesive coating whereby different portions of the con ductor are secured to the respective first and second terminal pads by the conductively adhesive coating with the insulative base lying thereon in covering relation.

12. A multiple-lead connector comprising a sheet of flexible material carrying spaced parallel strips of flexible conductive material each of which is coated with a conductive adhesive layer, the gaps between the strips being filled by an electrically-insulating, adhesive layer.