Patent Publication Number: US-11394154-B1

Title: Pliant electrical interface connector and its associated method of manufacture

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     In general, the present invention relates to electrical connectors that are used to electrically interconnect components that are pressed against opposite sides of the electrical connector. More particularly, the present invention relates to electrical connectors that are made, in part, from elastomeric or flexible materials so that the electrical connector is pliant. 
     2. Prior Art Description 
     As electronic circuitry becomes smaller and more densely populated with components, it is often difficult to interconnect separate electronic circuits using traditional soldering techniques. In many electronic assemblies, separate electronic components are placed in different areas of the assembly. Although the various electronic components will be near each other when fully assembled, these same parts are kept apart prior to assembly. In order to electrically interconnect the various electronic components prior to the final assembly, a manufacturer often uses long connection ribbons to interconnect the various separated electronic components. The long connection ribbons are then folded up into the device as the separated electronic components are assembled. 
     The use of such long ribbons is expensive, labor intensive, and requires space in the final assembly to hold the folded long ribbons. Furthermore, the long ribbons often become pinched as they are folded up into the final assembly, thus causing defective assemblies. 
     Another solution to this problem has been the use of elastomeric contact connectors. Elastomeric contact connectors are a class of connectors that contain conductive elements supported by an elastomeric body. 
     By placing an elastomeric connector between two electronic components, the two components can be electrically interconnected as the final product is assembled and the two electronic components are biased against the same elastomeric contact connector. Such prior art connectors are exemplified by U.S. Pat. No. 6,350,132 to Glatts. Elastomeric connectors are commercially produced by a variety of manufacturers, including Fujipoly® of Carteret, N.J. 
     One problem associated with elastomeric contact connectors is that of compression displacement. When the elastomeric substrate of the connector is compressed, it shortens and widens. This causes lateral forces in the body of the substrate. The lateral forces act upon the conductive material extending through the substrate. As a result, the conductive elements may move laterally as the connector is compressed. The lateral movement can cause the conductive elements to move away from established contact points, therein causing a failure in electrical conductivity between components. 
     In an attempt to reduce the lateral forces applied to conductors during compression, different techniques have been used with only limited success. In U.S. Pat. No. 6,106,305 to Kuzel, a technique is shown where the conductive element is designed to deform upon compression. In this manner, lateral forces will merely bend the conductor rather than move the conductor laterally. This technique works only to a limited degree because the conductor is designed to deform in a specific direction. If the lateral forces act upon the conductor from another direction, the conductor cannot bend and the conductor may be moved by the lateral forces. 
     Another technique used in the industry is to isolate the conductor from the elastomeric substrate. This is typically accomplished by placing the conductor into voids within the substrate. Such prior art is exemplified by U.S. Pat. No. 7,816,932 to Cartier and U.S. Pat. No. 6,079,987 to Matsunaga. The problems with such a technique are twofold. First, since the conductors pass through voids, the side of the conductors are not protected by the substrate. The exposed sides of the conductors can therefore oxidize. The oxidization changes the conductivity and impedance of the conductors, which can create operating errors in many electronic components. The second problem is that when the conductors are separated from the substrate, they lose the mechanical support of the substrate. The conductors are, therefore, much more likely to permanently deform over time. The deformation can cause loss of contact and failure of the electrical connection. 
     A need therefore exists for an improved pliant contact connector that keeps the conductors protected within an elastomeric substrate, yet prevents the elastomeric substrate from applying lateral displacement forces to the conductors. This need is met by the present invention as described and claimed below. 
     SUMMARY OF THE INVENTION 
     The present invention is a connection device for interconnecting electrical components. The connection device uses a plurality of contact layers that are interconnected in a unique manner. Each of the contact layers includes a substrate of dielectric material with a top edge, a bottom edge and side surfaces. A plurality of conductive elements extend in parallel through the dielectric material from the top edge to the bottom edge. Each of the conductive elements has one end exposed along the top edge and a second end exposed along the bottom edge. 
     The various contact layers are stacked. The side surfaces of the contact layers interconnect through a matrix of connective pillars. The connective pillars provide a network of open spaces between each of the contact layers. 
     The conductive elements are completely isolated by the dielectric material. However, there are open spaces in adjacent positions. When the overall connection device is compressed, the dielectric material compresses and widens. The open areas receive the deformation and prevent the deformations from propagating lateral forces that can act to displace the conducive elements from their original positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention, reference is made to the following description of an exemplary embodiment thereof, considered in conjunction with the accompanying drawings, in which: 
         FIG. 1  is an exemplary embodiment of a pliant electrical interface connector in accordance with the present invention; 
         FIG. 2  is a perspective cross-sectional view of the exemplary embodiment of  FIG. 1 , as viewed along section line  2 - 2 ; 
         FIG. 3  is a front cross-sectional view of the exemplary embodiment of  FIG. 1 , as viewed along section line  3 - 3 ; 
         FIG. 4  shows a single contact layer used within the exemplary embodiment; 
         FIG. 5  shows the contact layer of  FIG. 4  in conjunction with a perforated layer and an adhesive layer; 
         FIG. 6  shows the layers of  FIG. 5  repeated to show a stack; and 
         FIG. 7  shows a finishing process applied to the stack of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Although the present invention pliant connector device can be embodied into many shapes and sizes, only one exemplary embodiment is illustrated. The exemplary embodiment is being shown for the purposes of explanation and description. The exemplary embodiment is selected in order to set forth one of the best modes for the invention. The illustrated embodiment, however, is merely exemplary and should not be considered a limitation when interpreting the scope of the appended claims. 
     Referring to  FIG. 1  and  FIG. 2 , a first embodiment of a pliant connector device  10  is shown. The pliant connector device  10  has a first top surface  12  and an opposite second bottom surface  14 . A plurality of conductive elements  16  extend through a dielectric body  18  from the top surface  12  to the bottom surface  14 . Each of the conductive elements  16  is isolated from the others by the dielectric body  18 . However, the conductive elements  16  are exposed along the top surface  12  and the bottom surface  14 . The exposed ends of the conductive elements  16  can therefore be considered as contact pads  20  on the top surface  12  and the bottom surface  14  of the pliant connector device  10 . Since the contact pads  20  are exposed on the top surface  12  and on the bottom surface  14 , electricity can pass through the pliant connector device  10  between the top surface  12  and the bottom surface  14 . 
     Aside from the exposed contact pads  20  on the top surface  12  and the bottom surface  14 , each of the conductive elements  16  is completely insulated by the dielectric body  18  within the pliant connector device  10 . The conductive elements  16  are all parallel as they extend from the top surface  12  to the bottom surface  14 . The conductive elements  16  are arranged in rows  22 . The rows  22 , themselves, are parallel and travel in directions that are perpendicular to the lengths of the conductive elements  16 . As will be explained, the dielectric body  18  is not solid. Rather, the rows  22  are coupled by a matrix of connective pillars  25 . This creates a latticework of open spaces  24  around the connective pillars  25  and between each of the rows  22 . 
     The dielectric body  18  is made of an elastomeric material  26 , such as silicone, thermoplastic rubber (TPR) or another synthetic dielectric rubber. Due to the durometer of the elastomeric material  26 , the elastomeric material  26  is pliant and compresses when squeezed. Referring to  FIG. 3  in conjunction with  FIG. 2 , it will be understood that open spaces  24  exist between the rows  22  of conductive elements  16 . Accordingly, the open spaces  24  are adjacent to the conductive elements  16  within the pliant connector device  10 . The pliant connector device  10  is set between two electrical components  28 ,  29 . The electrical components  28 ,  29  touch the contact pads  20  that are the exposed ends of the conductive elements  16 . When compressed, the elastomeric material  26  within the pliant connector device  10  reduces in thickness and expands in width. The open spaces  24  within the pliant connector device  10  provide room for this compressional widening. In this manner, the elastomeric material  26  can widen without pressing laterally against the conductive elements  16 . Accordingly, compression of the pliant connector device  10  does not create internal lateral forces on the conductive elements  16  that can laterally alter the position of the conductive elements  16 . The conductive elements  16 , therefore, remain in the same position. As a consequence, the contact pads  20  that are the exposed ends of the conductive elements  16  also remain in the same position. This produces a stable electrical contact between the electrical components  28 ,  29  and the contact pads  20 . 
     Referring to  FIG. 4  in conjunction with  FIG. 1  and  FIG. 2 , it will be understood that the pliant connector device  10  is made from stacked layers. The rows  22  of conductive elements  16  are set into a ribbon  32  of the elastomeric material  26  to produce a contact layer  30 . A single contact layer  30  is shown in  FIG. 4 . Each contact layer  30  has a top edge  31 , a bottom edge  33 , and side surfaces  35  that run between the top edge  31  and the bottom edge  33 . The conductive elements  16  run in parallel between the top edge  31  and the bottom edge  33  within the confines of the two side surfaces  35 . 
     The positioning of the conductive elements  16  into the ribbon  32  is accomplished by setting parallel lengths of conductive elements  16  into an adhesive layer of uncured elastomeric material  26 . The elastomeric material  26  is then cured to complete the contact layer  30 . The conductive elements  16  can be segments of wire, such as copper wire, having a given gauge diameter D 1 . However, any conductive material can be used. The ribbon  32  of elastomeric material  26  preferably has a thickness T 1  that is approximately twice the thickness of the gauge diameter D 1  of a conductive element  16 . The conductive elements  16  are also preferably spaced apart at a pitch distance P 1 , from center to center, that is twice the thickness of the gauge diameter D 1 . Accordingly, if the conductive element  16  is a wire with a gauge diameter of 0.002 inches, the ribbon  32  of elastomeric material  26  would have a thickness of 0.004 inches and the center-to-center pitch of the conductive elements  16  would be 0.004 inches. 
     Referring to  FIG. 5  in conjunction with  FIG. 4 , it can be seen that during manufacture, the contact layer  30  is stacked against a perforated layer  34 . The perforated layer  34  is made from a sheet of polyvinyl alcohol  36  or another polymer that is highly soluble. The sheet of polyvinyl alcohol  36  is perforated with a matrix of holes  38 . The holes  38  can be formed in the sheet of polyvinyl alcohol  36  using masked dissolution, laser cutting, stamping or etching. Once the matrix of holes  38  is formed, the sheet of polyvinyl alcohol  36  is cut to size, therein forming the perforated layer  34 . The sheet of polyvinyl alcohol  36  is then adhered to the contact layer  30  using a coating layer of uncured elastomeric material  39 . The coating layer of uncured elastomeric material  39  is sufficient in volume to fill all of the holes  38 . 
     Referring to  FIG. 6  in conjunction with  FIG. 4  and  FIG. 5 , it will be understood that the process is repeated with a second contact layer  30 B being adhered to the perforated layer  34  with more uncured elastomeric material  39 . The process is repeated until a stack  40  is produced where multiple perforated layers  34  are interposed between multiple contact layers  30 . The stack  40  can have any length and width and any thickness. Once a stack  40  of sufficient size is created, a finishing process is applied. 
     Referring to  FIG. 7  in conjunction with  FIG. 6 ,  FIG. 5  and  FIG. 2 , the finishing process is explained. The stack  40  is heated until the adhesive layers of uncured elastomeric material  39  becomes cured. This permanently bonds all contact layers  30  and all perforated layers  34  together into a cured stack  42 . See Block  44 . The cured stack  42  contains the perforated layers  34  of polyvinyl alcohol, which are highly soluble. As is indicated by Block  52 , the processed stack  50  is cut to size, therein producing cut blanks  50 . The cut blanks  50  are then placed in a dissolution tank  46 . In the dissolution tank, the perforated layers  34  within the cut blanks  50  are dissolved away. See Block  48 . If the perforated layers  35  are water soluble, distilled water is used to dissolve the perforated layers  34 . If the perforated layers  35  are made using a material that dissolves in another solvent, then that solvent can be used in place of water, provided the solvent does not affect the remaining elastomeric material. After the perforated layers  34  are dissolved away the contact layers  30  are interconnected by the connective pillars  25 . The connective pillars  25  are created by the elastomeric material  39  that is used as adhesive and extends through the holes  38  in the perforated layers  34 . 
     Returning to  FIG. 1 ,  FIG. 5 , and  FIG. 7 , it will now be understood that the density of the conductive elements  16  on the pliant connector device  10  is determined by the gauge diameter D 1  of the conductive elements  16 , the pitch spacing P 1 , the thickness of each contact layer  30 , and the number of contact layers  30  assembled into a processed stack  50 . The length and thickness of the pliant connector device  10  is determined by how the processed stack  50  is cut. 
     It will be understood that the embodiment of the present invention that is illustrated and described is merely exemplary and that a person skilled in the art can make many variations to that embodiment. For instance, the size and shape of the pliant connector device can be varied. All such embodiments are intended to be included within the scope of the present invention as defined by the claims.