WO1996022621A1

WO1996022621A1 - Electrical interconnect assemblies

Info

Publication number: WO1996022621A1
Application number: PCT/US1995/004684
Authority: WO
Inventors: Mark Spencer
Original assignee: W. L. Gore & Associates, Inc.
Priority date: 1995-01-19
Filing date: 1995-04-17
Publication date: 1996-07-25
Also published as: AU2292795A

Abstract

The present invention is an improved electrical interconnect. The material of the present invention comprises a sheet of a porous polymer such as expanded polytetrafluoroethylene where the pores are filled with a silicone to produce a flexible and durable composite; and a sheet of dielectric containing conductive traces. The sheets are alternated to provide the interconnect.

Description

TITLE OF THE INVENTION

ELECTRICAL INTERCONNECT ASSEMBLIES

FIELD OF THE INVENTION

This invention relates to flexible resilient electrical interconnects for connecting adjacent electronic components and more particularly to interconnects that have electrical conductivity in one plane while being non- conductive in the other two planes.

It has long been a goal in the electronics industry to replace soldering and welding as a means of providing an electrical connection between two opposing rows or conductive elements. Electrical connection is needed to connect the traces of one flexible circuit to the traces of another flexible circuit; connect a ribbonized flat cable to a printed circuit board; connect a packaged integrated circuit to a printed circuit board; or the like. Moreover, there is a trend to make more efficient use of board space by closely spacing leads or traces, and by generally diminishing component size and circuitry. Usual connectors, e.g. spring, finger or pin contact are not amenable to the diminished size components that are common today.

Electrical interconnects are well known devices to link two such separate electronic components. The interconnect is placed between two such components. It ordinarily has a multiplicity of conductive traces or elements runing in parallel from one side to the other. Traces on the two components make contact with conductive traces of the interconnect thus providing a path of conductivity from one such element to the other through the interconnect assembly. The interconnect assemblies should be elastomeric in order to provide the requisite resiliency needed to ensure good contact between the two components. Some interconnects are made of layers of elastomeric silicone sheets having a multitude of metallic conductive traces between them. These are deficient in that their elasticity could be improved, and the conductive traces themselves do not consistently return to their original height.

In other interconnects, conductive particles are used. These interconnects employ conductive bands of metal particle filled elastomeric material disposed between bands of non-conductive elastomeric material. The bands of conductive elastomer make an electrical connection between conductive elements on two other parts desired to be connected. The width of each conductive elastomer band is less than the spacing between the individual conductive elements on each part, so the conductive bands make an electrical connection between the opposing elements but not between the individual conductive elements on each part. For example, a row of copper lines on one printed circuit board can be electrically connected to a row of copper lines on another printed circuit board without causing an electrical short within the row of copper lines on the printed circuit boards themselves.

If the electrical connection between two opposing parts needs to be more permanent, or a constant normal force cannot be exerted to hold the interconnect in place, then a Z-axis adhesive can be utilized. Z-axis adhesives are non-conductive resins filled with conductive particles. They come as either liquids, pastes, or cast films. The Z-axis adhesive is used to mechanically bond and electrically connect the conductive elements on one part and the opposing conductive elements on the other part. The conductive particles are suspended and isolated in the non-conductive resin. The diameter of each conductive particle is substantially less than the spacing of the conductive elements, therefore, there is no shorting between the individual elements. Conversely, the conductive particles have a sufficiently large diameter that they can electrically bridge between the opposing rows of conductive elements to be connected. These methods of connection have their limitations. The density of the connection that can be attained by the elastomeric connectors is limited by the spacing of the conductive and non-conductive elements in the elastomeric strip as well as the normal force that must be exerted. The Z-axis adhesive has several limitations based on its ability to keep the conductive particles suspended and isolated in the adhesive. If the particles are not evenly dispersed, they can cause shorting between the conductive elements. If they are not large enough or are not in sufficient concentration, there will not be sufficient conductivity between the conductive elements to be connected. Also, if the adhesive flows or is smeared during processing, the conductive adhesive may cause shorting of other components. Another problem with the

Z-axis adhesive is achieving the right balance of adhesion, conductivity, reparability, and compliance. A high particle content is usually needed, which can result in a brittle or weak reaction.

In some embodiments, a single conductive particle is used to provide the electrical path between two opposing conductive elements. In this type of connector, uniformity of particle size is critical to ensure adequate contact, since the degree to which two opposing conductive elements can be pressed together will depend on the diameter of the larger size particle in the elastomeric connector. It would be beneficial to have a connector that did not depend on the criticality of particle size for operation.

SUMMARY OF THE INVENTION

This invention overcomes deficiencies in art interconnects by providing a flexible elastomeric interconnect assembly comprising alternating sheets of:

(a) a dielectric material having a multiplicity of parallel conductive traces on one side, and (b) a flexible microporous material in which the pores are filled with an elastomeric silicone.

The silicone is preferably cured. The microporous material is an organic polymer, preferably a fluorocarbon polymer. Stretched porous polytetrafluoroethylene is especially preferred. The dielectric material can be any insulative sheet material such as polyester, polyimide, or the like.

The silicone in the pores of the microporous material makes the material highly resilient.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1a depicts dielectric material 10 with parallel conductive strips 11 on it.

Figure 1b depicts dielectric material 10 with parallel conductive strips 11 embedded in the surface of material 10 to form an even face along the surface.

Figure 2 depicts a side view of microporous material 12 with its pores filled with a silicone 13.

Figure 3a depicts alternating layers of dielectric material 10 and microporous material 12 in exploded view. Figure 3b depicts the layers of Figure 3a in an unexploded view.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures 1a and 1b, dielectric sheet 10 contains parallel conductive strips 11. In Figure 11a the strips 11 are located on one surface of dielectric 10. In Figure 1b, the strips 11 are embedded in the surface of sheet 10 so they are flush with the surface. The dielectric sheet can be any convenient material, preferable flexible, that is capable of retaining the strips 11. Suitable materials are thermosetting and thermoplastic resins, such as polyester or polyimide. A preferred dielectric material is polyimide. The dielectric sheet with the conductive strips will preferably be 3-12 mils thick. The conductive strips can be of any conductive material, such as conductive metal or plastic rendered conductive by the presence of a conductive filler. Representative strips include copper strips.

These dielectric sheets with conductive traces on one surface are layered alternately with a silicone filled 13 microporous material 12, as shown in Figure 2. The silicone filled microporous material is flexible and resilient and provides resiliency to the interconnect assembly.

Referring to Figures 3a and 3b the construction of alternating layers ensures that the conductive strips 11 are held in a desired alignment and are unable to move or contact one another. This avoids shorting out the material. Thus in the interconnect of the invention each conductive strip is isolated from the others. Because each conductor is isolated, the interconnect is especially useful to mate coaxial conductors. Only those conductor strips that contact the center conductor of the coax form the center conductive path and only the conductor strips contacting the outer conductor of the coax form the outer conductive path. All conductor strips between will contact only the dielectric material of the coax and will not provide any conductive path.

In the assemblies of this invention, the conductor strips can be as small as 0.0005 inch thick by 0.001 inch wide, and can be spaced 0.002 inch apart. The strips can be formed on the dielectric material by any convenient means, such as photoetching or adhesion. The microporous material employed can be any microporous organic polymer such as polyolefin, fluoropolymer, polyamide, or the like. Of preferred value because of its strength, lightweight, flexibility, is stretched porous polytetrafiuoroethylene. The silicone used is an elastomeric one to provide resiliency to the interconnect. The volume of the microporous material constitutes 50-85% or so of the material. The silicone can be imbibed into the pores by first dissolving the silicone in a suitable solvent.

To prepare interconnects using microporous expanded PTFE, first, an expanded porous PTFE material is produced, such as through the methods described in United States Patents 3,956,566 to Gore and 4,187,390 to Gore, each incorporated by reference. For instance, an expanded PTFE material may be formed from a mixture of PTFE resin (having a crystallinity of about 95% or above) and a liquid lubricant (e.g., a solvent of naphtha, white oil, mineral spirits, or the like). The mixture is thoroughly blended and then dried and formed into a pellet. The pellet is extruded into a film shape through a ram-type extruder. Subsequently, the lubricant may then be removed through evaporation in an oven. The resulting film material may then be subjected to uniaxial or biaxial stretching at a temperature of less than 327°C to impart the desired amount of porosity and other properties to the tube. Stretching may be performed through one or more steps, at amounts varying from 1:1 or less up to 45:1. The resulting material may then be subjected to a sintering temperature above 345°C (i.e., the melting temperature of PTFE) to amorphously lock the material in its expanded orientation. The stretched PTFE film comprises polymeric nodes interconnected by fibrils. Typical properties of such a structure comprise an average fibril length between nodes of 0.05 to 30 μm (preferably 0.2 to 10 μm), and a void volume of 50 to 85%. The stretched PTFE film will preferably have a thickness of 5-12 mils.

The fibril length of expanded PTFE that has been expanded in single direction is defined herein as the average of ten measurements between nodes connected by fibrils in the direction of expansion. The ten measurements are made on a representative micrograph of an expanded PTFE sample. The magnification of the micrograph should be sufficient to show at least five sequential fibrils within the length of the micrograph. Two parallel lines are drawn across the length of the micrograph so as to divide the image into three equal areas, with the lines being drawn in the direction of expansion and parallel to the direction of orientation of the fibrils. Measuring from left to right, five measurements of fibril length are made along the top line in the micrograph beginning with the first nodes to intersect the line near the left edge of the micrograph, and continuing with consecutive nodes intersecting the line. Five more measurements are made along the other line from right to left, beginning with the first node to intersect the line on the right side of the micrograph. The ten measurements obtained by this method are averaged to obtain the average fibril length of the material. Expanded porous PTFE is also commercially available in a wide variety of forms from a number of sources, including under the trademark GORE- TEX® from W. L. Gore & Associates, Inc., Newark, DE.

The porous, expanded PTFE material obtained is then filled with the silicone. A solution is formed by dissolving a silicone in an organic solvent. The ratio of silicone to solvent should be in the range of 4:1 to 1 : 10 parts by volume, and preferably is in the range of 3:1 to 1:3 parts by volume. The solution is formed through any conventional means, such as by blending in a mechanical mixer under ambient conditions. Where high loading of silicone is desired, elevation temperatures may be employed below the boiling temperatures of the solvent.

The preferred solutions comprise a silicone material comprising a material soluble in one or more solvents capable of permeating and wetting out an expanded PTFE structure. The material used preferably has a solids content of 95-100%, a specific gravity of between 0.95 to 1.5, and a viscosity between 300 and 150,000 centipoise. The silicone material can be ones that employ either a one or two part cure system. Ideally, curing is carried out at an elevated temperature, to cure the silicone into a rubber-like mass. It is particularly useful to use a silicone with a platinum-type cure system that is activated at elevated temperatures to cross-link into a rubber-like substance. The silicone material can be selected from a wide variety of silicones. For example, organic siloxanes or organic polysiloxanes having reactive groups, and copoiymeric siloxanes having reactive groups are representative. Fluorinated silicones are useful also. Representative curable silicone rubber material compositions include normal temperature curing types, low temperature curing types, and high temperature curing types. Suitable silicones for use in the present invention include methylhydrogen siloxane, dimethylhydrogen siloxane, dimethyl siloxane, dimethylvinyl-terminated siloxane, dimethylmethylphenylmethoxy silicone polymer, and the like.

Additionally, the silicone can contain dimethylvinylated silica, trimethylated silica, methyltrimethoxysilane, and the like. Commercially available silicone useful with the present invention include Q 3-6611, X1-4105, and Q1-4010, all available from Dow Corning, Inc., Midland, Michigan. Room temperature curing and high temperature curing compositions of silicone include two-pack type materials. Two-pack type materials provide a silicone rubber having cross-linked structure by means of a reaction between siloxanes having reactive groups (e.g., SiOH, SiO-R (where R is an alkyl group), SiH, SiCH=CH2 or the like) in the presence of a catalyst. The two- pack compositions are divided into condensation reaction types and addition reaction types. The condensation reaction types include those employing: dehydration-condensation reactions between silanol and alkoxy siloxane; a de-alcoholation condensation reaction between silonal and alkoxy siloxane; and a dehydrogenation condensation reaction between SiH and Silanol. The addition reaction types include those employing addition reaction between vinyl groups, alkyl groups, or other unsaturated groups and SiH.

A suitable curing catalyst is selected depending on the type of curing reaction desired. For example, metal, organic-metal salts, organic amines, -7- quatemary ammonium salts, and the like are employed in reactions of condensation reactions types. Palladium or platinum black, platinum asbestos, chlorplatinic acid or other form of platinum are employed in reactions of addition reaction types. The above-mentioned compositions may also contain other materials, such as silicone oil, Siθ2. or fumed silica as property altering agents.

The preferred solvent for the silicone comprises a solvent that both actively dissolves the silicone and is readily flows into structure of the intended polymeric substrate. For use with a PTFE substrate structure, a halogenated solvent, such as methylene chloride, acetone, or toluene, is particularly useful, as are commercially available solvents NORPAR-12 and ISOPAR-C. While methylene chloride has produced the best results to date, the carcinogenic nature of this solvent is objectionable for some applications. Accordingly, other preferred solvents continue to be sought. The presently preferred composition comprises a mixture of 10-75% by weight of Q1-4010 silicone elastomer and 25-90% methylene chloride, acetone, or toluene solvent. This mixture is formed by stirring the solvent while adding the silicone elastomer at room temperature (about 22°C) until the mixture has achieved a homogenous color. With an acetone mixture, the mixture should be re-stirred prior to each use due to precipitation of materials. Once the silicone/solvent composition is formed, it can then be applied to a suitable microporous material. The preferred material for use with the present invention comprises the microporous expanded PTFE material described above. Another material which may be suitable for use with the present invention is expanded ultra-high molecular weight polyethylene and perhaps others that can form an open, porous network of continuous pores from one side to another.

The solution is applied to the microporous material by spreading it over the material and then allowing the solution to become absorbed therein. Preferably, the material is immersed within the solution until it becomes saturated, such as by submerging the material in a bath of solution over a period of 1 to 5 minutes.

Once filled, the membrane and absorbed solution is exposed to an energy source, such as a heated oven set at 70 to 75°C or above, for a period of 2 to 5 minutes or more to evaporate away any solvent. Ideally, evaporation comprises employing an oven heated to 85°C or above and exposing the composition for at least 5 minutes. The evaporation of solvent can also be performed in one of the following manners: air drying for about a 5 hour period; or about 1 hour at about 50°C in an explosion-proof oven.

When applied in this manner, it has been found that the microporous material becomes thoroughly impregnated with the silicone between its top and bottom surfaces. When applied to a flat microporous material, e.g. a sheet, by spreading on one side, the bottom surface of the membrane (i.e., the surface opposite the side where the composition is applied) tends to have a tacky feel to it that may be desirable if the membrane is to be used as an adhesive layer.

By contrast, with some applications the top surface of the microporous material has been found to have a powder-like material on it. This is believed to be a coating of silicon dioxide found as a filler in some commercial silicone materials. This material may be left in place for ease in handling or may be removed through any suitable means, such as through use of a solvent and/or mechanical scraping. Additionally, it may be possible to adjust the pore size of the material to allow the infiltration of filler or extraneous material into the material along with the silicone. Different silicone mixtures, both with and without silicone dioxide filler, are described in the examples set forth herein.

After impregnation, the material may then be subjected to appropriate conditions to cure the silicone material. For Q4010-10 type silicone of Dow Corning Company, a filled microporous PTFE material can be cured by placing the uncured material in an oven at about 110°C for about 30 minutes.

The foregoing procedure provides an overlay of silicone over the polymeric nodes and fibrils of the membrane. The entire fibrillated interior of the membrane, including most or all of the porous structure therein, can be filled with the silicone.

The resulting impregnated material has substantial elastomeric properties. In this respect, the degree of elasticity of the present invention can be measured in the following manner: a piece of treated and cured microporous material is measured in length, stretched 2 times its length, released, and its new length re-measured. Resiliency is measured by compressing a given thickness of treated membrane to 50% its original height for 1 minute, releasing, and re-measuring its thickness.

To further aid in the impregnation process, the process of the present invention may be combined with other processes to achieve specific properties. For example, for some applications, such as use with very fine microporous materials, it may be desirable to impregnate the membrane with the silicone/solvent composition with the aid of a mechanical vacuum process. Other possible methods include use of mechanical pressure through either a pressure or vacuum process.

The silicone impregnated sheet of microporous material is then laminated to the dielectric material containing the conductive strips by any convenient means.

By alternating sheets, a layered up composite is obtained. The composite is then cut into section crosswise to the direction of the conductive strips to obtain the interconnects of the invention.

The silicone filled microporous material provides the desired elasticity, while the dielectric conductive material provides the electrical contacts that make the interconnect electrically.

Without intending to limit the scope of the present invention, the following examples illustrate how the present invention may be made and used:

EXAMPLE 1

A silicone filled microporous membrane suitable for use in the invention was produced in the following manner. A silicone adhesive material was acquired from Dow Corning Inc., of Midland, Michigan, under the designation Q3-6611. This material is a gray colored thick flowable liquid having a viscosity of 95,000 centipoise. The cured Q3-6611 has a durometer measurement of Shore A 60, tensile strength of 700 psi, and an elongation of 125%. The Q3-6611 contains dimethyl, methylhydrogen siloxane copolymer, dimethylvinylated and trimethyled silica and quartz. The silicone material was mixed in a halogenated solvent of methylene chloride (an aqueous solution of 50% by weight). Mixing was performed by stirring the solution at room temperature until a homogenous color formed.

The silicone solution was applied to sample membranes of expanded PTFE made in accordance with United States Patent 3,953,566 to Gore, incorporated by reference.

Coating was performed by using a wheel transfer procedure whereby a 25 foot long by 6 inch wide by 0.008 inch thick piece of unsintered expanded PTFE material was transported via a pay-off and take up real system over a rotating drum partially submersed in the silicone solvent mixture. The drum was rotated in a direction opposite the direction of material travel. A blade was positioned after the drum such that as the impregnated material travels across it, excess silicone material was scraped off.

The extent of silicone penetration was unexpected and caused the uncoated side of the membrane to become sticky. This stickiness caused the membrane to drag and stick to the plenum that the membrane travels across for drying of the solvent before being reeled up. Twenty (20) feet of impregnated membrane was produced using this procedure. Inspection of this membrane revealed that the side to which the silicone had been applied had a thin layer of powder-like material on it. This is believed to be a silicon dioxide deposit. The other side of the membrane had a sticky or tacky feeling indicating that the silicone completely penetrated the membrane. The essentially opaque white membrane also became translucent through this penetration.

Once coated in this manner, the membrane was cured for ten (10) minutes in an oven at 150°C. The pieces of membrane had very good elastic properties and did not show the usual cold flow characteristics of silicone. In order to establish adhesive qualities on both sides of the uncured membrane, the powder layer was removed from some of the samples by scraping the uncured membrane using a blade. The sheets produced were placed in alternating layers with flexible printed circuit board material. This layered composite was then placed in a heated press at 500 lbs at 150°C for ten minutes. The resulting flexible composite had excellent adhesion between the layers and had some elastic properties.

EXAMPLE 2

The silicone used was a Dow Coming 4010 Silicone Conformal Coating which contains dimethyl, methylhydrogen siloxane copolymer, dimethyl siloxane, dimethylvinyl-terminated silica and trimethylated silica.. The silicone was thinned using a solvent of methylene chloride. Mixing was again accomplished by stirring at room temperature until a homogenous color is produced.

Instead of a wheel coater machine, application to a membrane material identical to that employed in Example 1 was performed by placing the membrane material on a layer of silicone release paper. A 50:50 by weight mixture of silicone and methylene chloride was poured onto the membrane and wiped across the entire surface until a uniform translucence was achieved.

EXAMPLE 3

A silicone filled membrane was produced in the following manner. A dispersion was produced using a mixture of 145cc of ISOPAR-K per pound of duPont T-3512 polytetrafluoroethylene resin. The mixture was extruded using a double cavity die in a ram-type extruder. The extruded material was then calendered from 0.026" thick to 0.006" thick. This material was then calendered again to 0.0042" thick. The resulting material was then dried. The dried, calendered material was then expanded at a rate of 3.55:1 nominal expansion rate at a line speed of 130 feet/min. Finally, the expanded material was sintered at a temperature of about 369°C. The resulting material had the following properties: 0.75 gm/cc density; 70% porosity; 12 psi bubble point; 10,610 psi matrix tensile strength in the longitudinal axis of the membrane; 3.55:1 nominal expansion ratio; 2,735 psi matrix tensile strength in the transverse axis of the membrane; and an inverted cup moisture vapor transmission rate (MVTR) of 8300.

These membrane properties were determined in the following manner: Density was determined by measuring the dimensions of the material and calculating its weight per unit area.

Porosity was determined by calculating the sample's intrinsic density using a Micromeritics Model 1310 autotychometer. The procedure followed was: to evacuate the sample of air by using helium by exposing the sample to a helium-filled environment for 5 minutes; to determine the bulk density of the sample through an Archimedes method of water displacement of a 1" x 1" sample; and to calculate the porosity in accordance with the following calculation:

Porosity = 1 - ((bulk density)/(intrinsic density)) x 100%. The Bubble Point of porous PTFE was measured using isopropyl alcohol following ASTM Standard F316-86. The Bubble Point is the pressure of air required to blow the first continuous bubbles detectable by the their rise through a layer of isopropyl alcohol covering a 1 inch circular sample. This measurement provides an estimation of maximum pore size. The tensile strength was determined in accordance with ASTM D-882

(Tensile Properties of Thin Plastic Sheeting) using an Instron Tensile Tester, Series IX. The cross-head speed of the tensile tester was set at about 20 inches/min and the gage length was set at 2 inches.

The Moisture Vapor Transmission Rate (MVTR) was determined by mixing approximately 70 ml of a solution consisting of 35 parts by weight of potassium acetate and 15 parts by weight of distilled water and placing it into a 133 ml polypropylene cup, having an inside diameter of 6.5 cm at its mouth. An expanded polytetrafluoroethylene (PTFE) membrane having a minimum MVTR of approximately 85,000 g/m²/24 hrs. as tested by the method described in U.S. Patent 4,862,730 to Crosby and available from W. L. Gore & Associates, Inc. of Newark, Delaware, was heat sealed to the lip of the cup to create a taut, leak proof, microporous barrier containing the solution. A similar expanded PTFE membrane was mounted to the surface of a water bath. The water bath assembly was controlled at 23^'C plus 0.2^' C, utilizing a temperature controlled room and a water circulating bath.

The sample to be tested was allowed to condition at a temperature of 23^'C and a relative humidity of 50% prior to performing the test procedure. Samples were placed so the microporous polymeric membrane was in contact with the expanded polytetrafluoroethylene membrane mounted to the surface of the water bath and allowed to equilibrate for at least 15 minutes prior to the introduction of the cup assembly.

The cup assembly was weighed to the nearest 1/1000 g and was placed in an inverted manner onto the center of the test sample. Water transport was provided by the driving force between the water in the water bath and the saturated salt solution providing water flux by diffusion in that direction. The sample was tested for 5 minutes and the cup assembly was then removed, weighed again within 1/1000g. The MVTR of the sample was calculated from the weight gain of the cup assembly and was expressed in grams of water per square meter of sample surface area per 24 hours.

The expanded PTFE sheet made as described above was then submersed in a mixture of 3:1 by volume of Dow Coming Q 1-4010 silicone and ISOPAR-C solvent in the manner described above using a wiper ("doctor") blade to remove excess silicone from the surface of the membrane.

EXAMPLE 4

A polyimide sheet with parallel uniformly spaced copper traces across it in one direction was prepared by adhering a 16 inch by 16 inch x 4 mil sheet of Ubelex polyimide to a copper sheet 0.5 mil thick using a cyanate ester adhesive and applying heat and pressure. Then the copper was etched by photoresist to obtain copper traces 5 mil wide and 10 mil from center to center. Etching was done by conventional photoresist technology. These sheets were then cut in 1.5 x 4 inch retangular shapes. Sheets of silicone filled stretched porous PTFE prepared as in Example

1 were cut to the same size. Then sheets of the filled PTFE and sheets of the copper/polyimide were alternately stacked until 13 layers were obtained in a fashion so that the traces were all in the same direction. These sheets were adhered to one another by first rolling with a seam roller to press out air. Then the composition was baked at 150°C for about 30 minutes after placing between two aluminum plates under pressure.

The adhered composite was then sectioned perpendicular to the plane of the traces at 60 mil intervals.

The resulting laminate provided an electrical conductance when placed between two opposing printed circuit boards.

While particular embodiments of the present invention have been illustrated and described herein, the present invention should not be limited to such illustrations and descriptions. It should be apparent that changes and modifications may be incorporated and embodied as part of the present invention within the scope of the following claims.

Claims

C LAI MS:

1. A flexible electrical interconnect assembly comprising altemating layers (sheets or strips) of: (a) a dielectric material having a multiplicity of parallel electrically conductive traces on one side; and (b) a flexible microporous material in which the pores are fully filled with an elastomeric silicone.

2. The assembly of Claim 1 wherein the microporous membrane layer is between 5 and 12 mil thick and the dielectric material between 3 and 12 mil thick.

3. The assembly of Claim 1 wherein the microporous material is expanded PTFE.

4. The assembly of Claim 1 wherein the dielectric material is polyimide.

5. An electrical system comprising two electrical components are interconnected by the interconnect assembly of Claim 1.