Abstract:
A connector insert comprising a plurality of layers of conductive elastomer, and a concomitant method of employing a connector insert, the method comprising the steps of fabricating a plurality of layers of conductive elastomer as an insert and placing the insert into a connector.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of the filing of U.S. Provisional Patent Application Ser. No. 61/898,927, entitled “Very Low Inductance Design for Electrical Connector Insert”, filed on Nov. 1, 2013, and the specification and claims thereof are incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
     Not Applicable. 
     COPYRIGHTED MATERIAL 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention (Technical Field) 
     The present invention relates to inserts installed into an existing or new electrical connector to reliably add electrical circuitry to the system and concomitant methods of use and construction. 
     2. Description of Related Art 
     The present invention primarily relates to an insert installed into an existing or new electrical connector to reliably add electrical circuitry to the system. Current technology in this field uses either standard circuit board technology or EESeal® silicone inserts. The circuit board technology corrupts the existing environmental seal of the connector, and so is unsuitable for high-reliability connectors. The EESeal technology is made primarily from silicone elastomer, and so does not corrupt the existing seal. However, the filament wire interconnects within the insert introduce unwanted stray inductance and are labor intensive to construct. The additional stray inductance limits EESeal effectiveness at frequencies above 100 MHz. Both technologies incorporate discrete surface mount devices, primarily capacitors, whose stray inductance is typically a minimum of 0.5 nH. The stray inductance of the surface mount devices also limits high frequency performance. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is of a connector insert comprising one or more layers of conductive elastomer. Preferably, the layers have a volume resistivity less than about 0.010 ohms/cm. The insert can be placeable into an existing connector. The layers have holes for pins of the connector, and provide at least a connector shell contact, a ground plane, and a pin contact. The connector insert can additionally comprise a capacitor, preferably comprising a plurality of layers of conductive elastomer, with separation provided by at least one layer of non-conductive material, and most preferably wherein the at least one layer of non-conductive material comprises non-conductive elastomer. The insert may additionally comprise one or more other electrical components such as resistors, MOVs, diodes, fuses, antifuses, shorting blocks, inductors, active electrical components, and any combination thereof, and one or more electrical components may comprise elastomer. 
     The invention is additionally of a concomitant method of employing a connector insert, the method comprising the steps of: fabricating one or more layers of conductive elastomer as an insert; and placing the insert into a connector. The layers preferably have a volume resistivity less than about 0.010 ohms/cm. The connector may be an existing connector. Holes are formed in the insert for the pins of the connector, and the insert provides at least a connector shell contact, a ground plane, and a pin contact for the connector. A capacitor may be formed in the insert, preferably wherein the capacitor comprises a plurality of layers of conductive elastomer, with separation provided by at least one layer of non-conductive material, and most preferably wherein the at least one layer of non-conductive material comprises non-conductive elastomer. One or more electrical components may be formed in the insert, and one or more of the electrical components may comprise elastomer. 
     The invention is further of a capacitor for a connector insert, the capacitor comprising a plurality of layers of elastomer, with separation provided by at least one layer of non-conductive material. 
     Further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings: 
         FIG. 1  is a schematic diagram of a discrete component connector insert with planar conductive elastomer construction according to the invention; 
         FIG. 2  is a schematic diagram of a conductive elastomer capacitor according to the invention; 
         FIG. 3  is a schematic diagram of a conductive elastomer capacitor integrated into a connector insert according to the invention; 
         FIG. 4  is a schematic diagram of a conductive elastomer “perimeter” capacitor integrated into a connector insert according to the invention; 
         FIG. 5  is a schematic diagram of a discrete component connector insert with planar conductive elastomer construction integrated into a connector assembly according to the invention; 
         FIG. 6  is a schematic diagram of an insert according to the invention placed into a pre-existing connector (retrofit); 
         FIG. 7  is a schematic diagram with cut-through views and a cross sectional view of a discrete component connector insert with planar conductive elastomer construction according to the invention illustrating variations on the use of electrical components; 
         FIG. 8  is a schematic diagram with cut-through views and a cross sectional view of a conductive elastomer capacitor integrated into a connector insert according to the invention illustrating variations on the use of electrical components; and 
         FIG. 9  is a schematic diagram with cut-through views and a cross sectional view of a conductive elastomer “perimeter” capacitor integrated into a connector insert according to the invention illustrating variations on the use of electrical components. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention employs planar conductive layers rather than the wire interconnects within a connector insert, which provides a number of advantages. The conductive layers can be conductive elastomer or other conductive element(s) such as a thin metal sheet, but the preferred construct is conductive silicone elastomer, with a volume resistivity preferably less than about 0.010 ohms/cm. Electrically opposing conductive layers are insulated from each other by the non-conductive elastomer. An electrical component, such as a 0402 SMD sized capacitor, transient voltage suppressor, or resistor, is connected between the two conductive layers. This planar arrangement of the conductors greatly reduces unwanted stray inductance. Further, a small capacitor can be formed by overlapping the opposing conductors and separating them with a thin layer of non-conductive elastomer, or other non-conductive material with high dielectric constant, such as polypropylene. A relative permittivity greater than 2 is preferred for any of these non-conductive layers. The planar construction of this integrated capacitor, and the elimination of a discrete capacitor, yields ultra-low stray inductance, providing effective filtering well into the GHz frequencies. An insert can employ a discrete device and/or an integral capacitor to achieve a parallel configuration, with the discrete device providing filtering at lower frequencies and the integral capacitor taking over at higher frequencies. 
     In addition to being installed at the mating interface of a connector pair in a retrofit manner, this assembly can be built into a single connector half, creating a filtered connector. Two capacitive inserts, separated by an inductive element, can be built into a connector, thereby creating a Pi filter. A “T” or “L” type filter can be similarly configured. 
     This type of electronic circuit construction, utilizing flexible conductive elastomer interconnections between circuit elements and external electrical contacts, has application in fields other than electrical connectors, such as medical and consumer electronics where the circuitry is required to be compressed or flexed. 
     Turning to the figures,  FIG. 1  shows one possible construction of a discrete component connector insert  10  with planar conductive elastomer layers, comprising conductive elastomer shell contact  12 , conductive elastomer ground plane  14 , electrical components  16 , conductive elastomer pin contact  18 , non-conductive elastomer  20 , and pin holes  22 . In this embodiment, electrical components  16  comprise discrete capacitors. This insert would typically be installed over the pins of a high reliability circular connector to provide EMI filtering. In other embodiments, electrical components  16  may comprise resistors, MOVs, diodes, fuses, antifuses, shorting blocks, inductors, active electrical components, and any combination thereof. 
     Contact to at least one pin of the existing connector is made using a layer of conductive elastomer  18  with a hole  22  therein. The diameter of the hole  22  is preferably smaller than the diameter of the pin of the existing connector, so that when the pin is inserted into hole  22 , the conductive elastomer stretches to accommodate the pin. This stretching of the conductive elastomer results in a tight fit around the pin, and electrical contact from the pin to the conductive elastomer is thereby achieved. One end of an electrical component  16 , e.g., a 0402 SMD capacitor, is placed so that it makes contact to the conductive elastomer pin contact  18 . The other end of the electrical component  16  makes contact with the planar conductive elastomer ground plane  14 . The pin contact and the ground plane are separated from each other with a layer of non-conductive elastomer  20  placed between them. Non-conductive elastomer  20  is used to encapsulate the top and bottom of the connector insert  10 . The conductive elastomer shell contact  12  is exposed around the periphery of the insert  10  and along the top surface periphery. Its outside diameter is slightly larger than the inside diameter of the existing connector shell so that it is compressed when installed, achieving electrical contact with the existing connector shell. It can also make contact to the existing mating connector shell along the top surface periphery. The resulting planar construction of the insert  10  results in a very low stray inductance, and much better filtering performance, as compared to existing technology. 
       FIG. 2  shows an example of an integral capacitor  17  created using conductive elastomer and non-conductive elastomer, comprising dielectric non-conductive elastomer  21 , conductive elastomer first terminal  24 , and conductive elastomer second terminal  26 . A capacitor comprises a plurality of conductive plates separated by an insulating material. The value of the capacitor is determined by the overlapping surface area of the plates, the distance between the plates, and the dielectric constant of the insulating material. 
     By using elastomers for both the conductive and insulating components of a capacitor, the resulting part can change shape through compression, distension, flexure and other external forces while maintaining its electrical performance and mechanical integrity. 
     This type of capacitor can be created as an integral part of the fabrication of a connector insert (integral capacitor  17 ) as shown in  FIG. 3 , comprising conductive elastomer shell contact  12 , non-conductive elastomer  20 , dielectric non-conductive elastomer  21 , pin holes  22 , conductive elastomer pin contact plate  28 , and conductive elastomer ground plate plane  30 . In this example, the conductive elastomer pin contact plate is positioned above-below the conductive elastomer ground plate and separated by a thin layer of dielectric non-conductive elastomer. Non-conductive elastomer  20  is used to isolate the conductive elastomer ground plate  30  from the at least one pin of the existing connector. The overlapping area of the two conductive elastomers, thickness of the dielectric non-conductive elastomer layer, and the dielectric constant of the dielectric non-conductive elastomer determine the value of the resulting capacitor. Non-conductive elastomer  20  is used to encapsulate the top and bottom of the connector insert  10 . The conductive elastomer shell contact  12  is exposed around the periphery of the insert  10  and along the top surface periphery. Its outside diameter is slightly larger than the inside diameter of the existing connector shell so that it is compressed when installed, achieving electrical contact with the existing connector shell. It can also make contact to the existing mating connector shell along the top surface periphery. Since no discrete device is used, the resulting filter is extremely low inductance and provides effective filtering well into the 10&#39;s of GHZ. 
     Instead of using overlapping layers, an integral capacitor  17  can also be created using the perimeter of the conductive elastomer pin contact as one plate, the surface of the conductive elastomer ground plane around the pin contact as the other plate, and the gap between these surfaces filled with a dielectric non-conductive elastomer as the dielectric layer as shown in  FIG. 4 . This embodiment comprises conductive elastomer shell contact  12 , conductive elastomer ground plate  30 , conductive elastomer pin contact plate  28 , dielectric non-conductive elastomer  21 , non-conductive elastomer  20 , and pin holes  22 . The perimeter of the conductive elastomer pin contact plate can be any shape, but the preferred shape is a circle. The surface area of the perimeter of the conductive elastomer pin contact plate, the thickness of the gap filled with the dielectric non-conductive elastomer and the dielectric constant of the dielectric non-conductive elastomer determine the value of the resulting capacitor. Non-conductive elastomer  20  is used to encapsulate the top and bottom of the connector insert  10 . The conductive elastomer shell contact  12  is exposed around the periphery of the insert  10  and along the top surface periphery. Its outside diameter is slightly larger than the inside diameter of the existing connector shell so that it is compressed when installed, achieving electrical contact with the existing connector shell. It can also make contact to the existing mating connector shell along the top surface periphery. Since no discrete device is used, the resulting filter is extremely low inductance and provides effective filtering well into the 10&#39;s of GHZ. 
     With minor dimensional modifications, the embodiments described above can also be made an integral part of a connector as shown in  FIG. 5 , instead of an insert between a connector pair. This embodiment comprises conductive elastomer ground plane  14 , capacitor  16 , conductive elastomer pin contact  18 , non-conductive elastomer  20 , o-ring  32 , interfacial seal  34 , connector shell  36 , pins  38 , and connector insert  40 . One example involves placing the embodiment between the connector insert and the interfacial seal. This permits the necessary contact with the pins and the connector shell while preserving the mating and sealing features of a standard connector pair. With further modifications to a standard connector, the embodiment can be installed elsewhere within the connector as well. 
       FIG. 6  illustrates placement of an insert  10  according to the invention into a pre-existing connector, thereby providing a retrofit improvement to the connector. Insert  10  is shown comprising outside perimeter P 1  as installed over pins  38  and as oriented with respect to interfacial seal  34 , o-ring  32 , and connector shell  36  with cavity having inside perimeter P 2 . 
     Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited. 
     Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference. 
       FIG. 7  shows another embodiment of a discrete component connector insert  10  with planar conductive elastomer layers, comprising conductive elastomer shell contact  12 , conductive elastomer ground plane  14 , conductive elastomer pin contact  18 , electrical components  16 , non-conductive elastomer  20 , and pin holes  22 . Pin-to-shell discrete component  42  is shown wherein one end of an electrical component  16 , e.g., a 0402 SMD capacitor, is placed so that it makes contact to the conductive elastomer pin contact  18 . The other end of the electrical component  16  makes contact with the conductive elastomer ground plane  14 . The conductive elastomer pin contact and the conductive elastomer ground plane are separated from each other with a layer of non-conductive elastomer  20  placed between them. Shorted pin  44  is shown wherein at least one pin hole  22  is created in the conductive elastomer ground plane  14  to provide an electrical connection between at least one pin of an existing connector and the existing connector shell. Open pin  46  is shown wherein at least one pin hole  22  is created in non-conductive elastomer  20  to provide electrical isolation between at least one pin of an existing connector and the existing connector shell. Pin-to-pin short  48  is shown wherein at least two pins holes  22  are created in a continuous conductive elastomer pin contact  18  to provide an electrical connection between at least two pins of the existing connector. Non-conductive elastomer  20  is used to electrically isolate the conductive elastomer pin contact  18  from the conductive elastomer ground plane  14 . Pin-to-pin discrete component  50  is shown wherein non-conductive elastomer  20  is used to electrically isolate two conductive elastomer pin contacts  18  from each other and from the conductive elastomer ground plane  14 . One end of an electrical component  16  is placed so that it makes contact to one of the conductive elastomer pin contacts  18 . The other end of the electrical component  16  makes contact with the other conductive elastomer pin contact  18 . Non-conductive elastomer  20  is used to encapsulate the top and bottom of the connector insert  10 . The conductive elastomer shell contact  12  is exposed around the periphery of the insert  10  and along the top surface periphery. Its outside diameter is slightly larger than the inside diameter of the existing connector shell so that it is compressed when installed, achieving electrical contact with the existing connector shell. It can also make contact to the existing mating connector shell along the top surface periphery. 
       FIG. 8  shows another embodiment of an integral capacitor insert comprising non-conductive elastomer  20 , dielectric layer  21 , conductive elastomer pin contact plate  28 , conductive elastomer ground plate  30 , and various uses of electrical components  16 . Pin-to-shell discrete component  42  is shown wherein, in addition to the integral capacitor  17  described in  FIG. 3 , one end of an electrical component  16 , e.g., a 0402 SMD capacitor, is placed so that it makes contact to the conductive elastomer pin contact plate  28 . Non-conductive elastomer  20  is used to isolate this end of the electrical component from the conductive elastomer ground plate  30 . The other end of the electrical component  16  makes contact with the conductive elastomer ground plate  30 . The conductive elastomer pin contact plate and the conductive elastomer ground plate are separated from each other with a layer of dielectric non-conductive elastomer  21  placed between them. Shorted pin  44  is shown wherein at least one pin hole  22  is created in the conductive elastomer ground plate  30  to provide an electrical connection between at least one pin of an existing connector and the existing connector shell. Open pin  46  is shown wherein at least one pin hole  22  is created in non-conductive elastomer  20  to provide electrical isolation between at least one pin of an existing connector and the existing connector shell. Non-conductive elastomer  20  is used to electrically isolate the conductive elastomer ground plate  30  from the at least one pin of the existing connector. Pin-to-pin short  48  is shown wherein at least two pins holes  22  are created in a continuous conductive elastomer pin contact plate  28  to provide an electrical connection between at least two pins of the existing connector. Non-conductive elastomer  20  is used to electrically isolate the conductive elastomer ground plate  30  from the at least two pins of the existing connector. Pin-to-pin discrete component  50  is shown wherein, in addition to the integral capacitor  17  described in  FIG. 3 , non-conductive elastomer  20  is used to electrically isolate two conductive elastomer pin contact plates  28  from each other. One end of an electrical component  16  is placed so that it makes contact to one of the conductive elastomer pin contact plates  28 . The other end of the electrical component  16  makes contact with other conductive elastomer pin contact plate  28 . Non-conductive elastomer  20  is used to isolate the electrical component from the conductive elastomer ground plate  30 . Non-conductive elastomer  20  is used to encapsulate the top and bottom of the connector insert  10 . The conductive elastomer shell contact  12  is exposed around the periphery of the insert  10  and along the top surface periphery. Its outside diameter is slightly larger than the inside diameter of the existing connector shell so that it is compressed when installed, achieving electrical contact with the existing connector shell. It can also make contact to the existing mating connector shell along the top surface periphery. 
       FIG. 9  shows another embodiment of an integral capacitor insert created using the perimeter of the conductive elastomer pin contact  28  as one plate, the surface of the conductive elastomer ground plane  30  around the pin contact  28  as the other plate, and the gap between these surfaces filled with the dielectric material  21 . Various uses of components  16  are illustrated. Pin-to-shell discrete component  42  is shown wherein, in addition to the integral capacitor  17  described in  FIG. 4 , one end of an electrical component  16 , e.g., a 0402 SMD capacitor, is placed so that it makes contact to the conductive elastomer pin contact plate  28 . The other end of the electrical component  16  makes contact with the conductive elastomer ground plate  30 . The conductive elastomer pin contact plate and the conductive elastomer ground plate are separated from each other with a layer of dielectric non-conductive elastomer  21  placed between them. Shorted pin  44  is shown wherein at least one pin hole  22  is created in the conductive elastomer ground plate  30  to provide an electrical connection between at least one pin of an existing connector and the existing connector shell. Open pin  46  is shown wherein at least one pin hole  22  is created in non-conductive elastomer  20  to provide electrical isolation between at least one pin of an existing connector and the existing connector shell. Pin-to-pin short  48  is shown wherein at least two pins holes  22  are created in a continuous conductive elastomer pin contact plate  28  to provide an electrical connection between at least two pins of the existing connector. Dielectric non-conductive elastomer  21  is used to electrically isolate the conductive elastomer pin contact plate  28  from the conductive elastomer ground plate  30 . Pin-to-pin discrete component  50  is shown wherein dielectric non-conductive elastomer  21  is used to electrically isolate two conductive elastomer pin contact plates  28  from each other and from the conductive elastomer ground plate  30 . One end of an electrical component  16  is placed so that it makes contact to one of the conductive elastomer pin contact plates  28 . The other end of the electrical component  16  makes contact with another conductive elastomer pin contact plate  28 . Non-conductive elastomer  20  is used to encapsulate the top and bottom of the connector insert  10 . The conductive elastomer shell contact  12  is exposed around the periphery of the insert  10  and along the top surface periphery. Its outside diameter is slightly larger than the inside diameter of the existing connector shell so that it is compressed when installed, achieving electrical contact with the existing connector shell. It can also make contact to the existing mating connector shell along the top surface periphery.