JPH0421966B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION This invention relates to sheet materials useful for forming adhesive electrical connections to electronic components. In the electrical equipment industry, small side-
There is a need for a means to make a convenient yet reliable electrical connection between each component within a set of terminal pads (by-side). A promising technique for forming such connections is
GB 2048582A teaches an adhesive comprising a flexible insulating sheet, a number of parallel separate conductive stripes carried on the sheet, and a conductive adhesive covering the conductive stripes. A flexible connector tape is taught. Electrical connections can be made by adhering the ends of the tape to a set of terminal pads in line with the individual pads, with the individual stripes on the tape. In order to satisfactorily use the sheet material described above, the conductive adhesive of the sheet material must have a low electrical resistance and adequate adhesion that is stable over the length of time and under the operating conditions expected of the sheet material. Must have. Conventional conductive adhesives do not have the necessary degree of stability and low electrical resistance. Also, conventional conductive adhesives either have too high an initial resistance or increase in resistance during use and lead to contact defects to ensure proper electrical contact and therefore a reduction in electrical resistance. Additional mechanical tightening required. Also, a drawback of the connector tapes described above is that the conductive adhesive covering the stripes can unintentionally come into contact with other parts of the electronic device in the middle part of the tape, causing short circuits. Such contact connects the middle portion of the tape, as was done in some small flat cables of the prior art (see U.S. Pat. No. 4,113,981, which describes a cable including a flat sheet with conductive stripes). This could be avoided by coating with an electrically insulating layer. However, intermediate covering of cables with such electrically insulating layers is inconvenient and uneconomical. This is because only this intermediate coating needs to be coated with a specific length of electrically insulating material to suit the specific application. The intermediate application of a specific length of insulation material is a more difficult operation, and the application of this insulation material requires a stock of cables with different lengths of electrical insulation for different products. It needs to be saved. Alternatively, electrical insulation must be removed from the ends of the cable, which is difficult and unsuitable for rapid automated operation. The present invention is insulated over its entire adhesive surface;
Furthermore, the present invention provides a new conductive adhesive sheet that can be directly bonded to electronic components and electrically connected in one operation. This new product has a conductive stripe, such as a metal layer, deposited on an insulating web support, giving the surface of the sheet material electrical conductivity. The sheet materials of the present invention are electrically conductive, generally comprising a single layer of electrically conductive elements, such as discrete metal particles, dispersed within the adhesive layer, the thickness being substantially the same as or greater than the thickness of the adhesive layer. Contains adhesive layer.
As used herein, the term "discrete" means that the conductive elements are independent and separated from each other. A thin electrically insulating layer is disposed on the single layer of the conductive element, and the electrically insulating layer is tack-free or poorly tack-free at room temperature (i.e., 20° C.) and when tested according to the test method described herein. the electrical resistance through the layer to the electrically conductive element is at least 1 megohm, softens to an adhesive and flowable state when heated to high temperatures, but becomes rigid and substantially non-flowable when cooled to room temperature; Made of electrically insulating material. The sheet material is easy to handle at room temperature and exhibits no conductive adhesive properties at room temperature; however, by pressing it against a substrate and heating it, the sheet material integrates with the substrate and the conductive elements penetrates the electrically insulating layer to form an electrical connection with the substrate side. A conductive adhesive layer with conductive elements dispersed in the adhesive layer is generally supported on a flexible insulating web or film support via conductive stripes. The adhesive softens to an adhesive state when heated to high temperatures, but hardens to a strong, substantially non-flowing state at room temperature. and the conductive elements dispersed in the adhesive layer have a uniform thickness that is approximately the same as or greater than the average thickness of the adhesive layer;
Preferably, the upper edge of substantially each conductive element is higher than at least a portion of the outer surface of the adhesive layer surrounding the element. In bonding the preferred sheet material to a substrate, the adhesive surrounding the conductive elements is forced into contact with and adheres to the substrate. The insulating web or insulating film support carrying the adhesive layer also avoids areas of the conductive element that are thicker than the adhesive, as the electrically insulating layer will flow due to the heat and pressure when pressed against the substrate and heated. to equalize. It is contemplated that an insulating web (or insulating film) support is held under tension around the conductive element and places the conductive element under compression against the substrate. The adhesive layer and the conductive element, which are strong but substantially non-flowing at room temperature, form a connection to the substrate that has a low electrical resistance and maintains this low electrical resistance over a long useful life. be done. The sheet material of the present invention has advantages over prior art techniques using commercially available pressure sensitive adhesive connector tape products of the type described in U.S. Pat. No. 3,475,213. These conventional connector tapes consist of a pressure-sensitive adhesive layer applied onto a conductive support, typically a metal foil, by a single layer of relatively large conductive particles dispersed within the adhesive layer. are using. The particles in these tapes were substantially the same thickness as the adhesive layer, and sometimes even thicker than the adhesive layer. However, these conventional connector tapes must be tightened to hold the connector tape to the board or a low electrical resistance electrical connection may not be achieved. Apparently, after the conventional connector tape is adhered to the desired location, the force holding the conductive particles to the substrate gradually decreases as the adhesive flows away. In contrast to the prior art, the preferred sheet materials of the present invention provide a thin layer of electrically insulating material of sufficient thickness to provide electrical insulation and physical protection, thereby providing reliable and reliable electrical Connections can be made through the electrically insulating layer using heat and pressure. This heat and pressure causes the electrically insulating material to move from above the conductive element to a lower area, such as a recess in the sheet material, exposing the conductive element and forming an electrical connection by making intimate contact with the conductive portion of the substrate. is ensured and the electrically insulating material of the electrically insulating layer is maintained in a strong state at the moved position by cooling the electrically insulating material. The low resistance electrical connection thus formed is maintained over a long useful life. Typically, the sheet materials of the present invention, once formed into elongated strips, can be wound into rolls for convenience in use. Furthermore, a plurality of conductive layers are included as narrow parallel conductive stripes, which conductive stripes are formed into a stretched insulating web (insulating film).
They are supported at intervals on a support and insulated from each other, the conductive stripes having a length equal to the length of the insulating web (insulating film) support. That is, the presence of the conductive stripes allows electrical connections to be properly made to a terminal substrate having a plurality of separate parallel terminal pads. Specific tape 10 shown in FIGS. 1 and 2
consists of a flat electrically insulating sheet (support) 11, a conductive strip 12, a non-conductive adhesive material 13 covering the conductive strip, conductive particles (conductive elements) 14 dispersed in the adhesive material, and covering the entire top surface of the tape. Thin layer of electrically insulating material (electrical insulating layer) 1
Contains 5. The flat electrically insulating sheet (support) 11 typically comprises a film, such as a polyethylene terephthalate or polyimide film, or a resin-impregnated fibrous web. In a preferred construction, the sheet is flexible so that it conforms to the surroundings of the conductive element during the gluing operation, yet allows the adhesive carried on the support to be in intimate contact with the substrate to be bonded. There must be. Preferred films have flexibility on the order of 25 micrometer or 50 micrometer thick films of polyethylene terephthalate. With regard to controlling the conformity of sheet materials to substrates in general, films with greater flexibility allow for better conformity when electrical contact is made under heated conditions;
Conversely, less flexible films require thicker adhesive layers to achieve the same desired results. Conductive stripes 12 typically consist of a layer of metal, such as silver, gold, aluminum, or copper, deposited on a flat insulating sheet support. other conductive stripes, such as metal foil (which may be adhered to a flat insulating sheet support with adhesive);
A conductive strip of metal sputtered onto a flat sheet support, or a layer formed from a conductive paint composition or ink that typically includes a paint vehicle and a conductor, such as metal or carbon particles, into a conductive strip. Can be used. The adhesive material 13 is a heat-activated material that forms an adhesive layer during the heating operation. During the heating operation, the adhesive material wets the substrate to be bonded. The adhesive then cures, either by cooling or by reaction of the components, and the sheet material and conductive particles (conductive elements) of the invention are held in place with respect to the adherend. At this point, the adhesive material is either tack-free or poorly tack-free. A preferred adhesive material known as a "thermal tack adhesive" is a U.S. patent application no.
It is described in the specification of No. 334820. As described in this application, the adhesive material is tack-free or poorly tack-free at 20° C., but becomes pressure-sensitive and significantly tacky upon heating. Good adhesion occurs immediately at the tack temperature without the need for crosslinking or other chemical reactions. The adhesive material comprises an acrylic polymer or a mixture of acrylic polymers of at least one alkyl acrylate and/or alkyl methacrylate monomer (referred to herein as "acrylic ester monomer"). and (1) the acrylic ester monomer provides at least 50 mole percent of the one or more acrylic polymers of the adhesive layer; The Tg (glass transition temperature) or weight average Tg is from -10°C to 80°C; (b) has a probe tack value of at least 75gf over a range of at least 50°C, which value is less than 40°C;
(c) shear value (defined below) at 65°C;
for at least 25 minutes, and (4) acrylic acid, methacrylic acid, itaconic acid, maleic acid or maleic anhydride, amides of the foregoing acids, acrylonitrile, methacrylonitrile,
Adhesion of the prior art in that up to 50 mole % of one or more acrylic polymers can be provided by copolymerizable monomers with polar groups such as N-vinyl-2-pyrrolidone and N-vinyl-2-pyrrolidone. Different from the material. The one or more acrylic polymers are acrylic ester monomers that give a Tg in the range of -10°C to 80°C, such as homopolymers of methyl acrylate or acrylic acid having a Tg in the range mentioned above. It may be a copolymer of an ester monomer and a copolymerizable polar monomer. at least -10℃
Useful acrylate monomers that homopolymerize to Tg include methyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, bornyl acrylate,
Bornyl methacrylate, 2-phenoxyethyl acrylate, 2-phenoxymethyl acrylate, mono- and di-methyl and ethyl esters of itaconic acid, and mono- and di-maleic acid.
There are methyl and ethyl esters. Useful acrylate monomers that provide low Tg include ethyl acrylate, butyl acrylate and octyl acrylate and n-amyl methacrylate, hexyl methacrylate and octyl methacrylate. A copolymer of 43 mol% methyl methacrylate, 53 mol% methyl acrylate and 4 mol% acrylamide has a Tg of about 50°C. The Tg of a copolymer of 73 mol% methyl methacrylate, 19 mol% methyl acrylate, 4 mol% ethyl acrylate and 4 mol% acrylamide is about 79°C. The thermoadhesive adhesive material typically for use in the present invention is pressure sensitive and significantly sensitive when heated to a temperature of about 40°C or higher, preferably 75°C or higher. Becomes sticky. Appropriate bond strength can be maintained by exposure to temperatures at or above the bonding temperature. Conductive particles (conductive elements) can be dispersed in an adhesive material to form a conductive adhesive, and the conductive particles and the adherend are held in their bonded position by the strong adhesive material not only at room temperature but also at high temperatures. can be done. Other copolymerizable monomers may also be used in small amounts without reducing the above values of the acrylic copolymer for the purposes taught herein. Among such copolymerizable monomers are styrene, vinyl acetate, and vinyl chloride, each of which may be used in amounts up to about 5 mole percent of total monomers. Other heat-activated adhesive materials that can be used include hot melt adhesives, which are thermoplastic materials, and epoxy-based adhesives, which typically soften to a fluid state at elevated temperatures and then cool to form a bond. It is a reactive composition. Pressure sensitive adhesives that are pressure sensitive at room temperature are also used in the present invention, particularly for bonding to types of substrates that cannot be exposed to high temperatures or pressures during bonding to achieve electrical connections. can. The conductive particles 14 in the sheet material of the present invention shown in FIGS. 1 and 2 are generally flattened and of conventional thickness. For example, a sieved batch of originally spherical particles may be passed through a nip roll such as a paint mill. See US Pat. No. 3,475,213. Flat particles are particularly preferred since they are present along the flat side and a high proportion of the particles can participate in electrical conduction through the adhesive layer. Spherical particles are also useful when sieved into a narrow range of sizes so that the majority of the particles are approximately the same size. The conductive particles must be sufficiently hard and rigid to penetrate the electrically insulating layer during the bonding operation.
The particles are usually metal, preferably silver but also copper or aluminum (US Pat. No. 3,475,213
Additives such as those described in the above specification may be desirable to achieve compatibility with these metals) or various other metals, metal coated glass beads, metal coated carbon. It may also be a metal coated particle such as a particle. The conductive particles can range in thickness from at least 10 micrometers up to 500 micrometers, although the currently preferred range for intended products is about 20 micrometers to 100 micrometers, and the adhesive layer The thickness may range from at least 6 micrometers to 450 micrometers. (The average thickness of the adhesive layer is
It is determined by measuring the approximate volume of adhesive material in the layer and then dividing this volume by the area of the sheet material. ) It is generally difficult to obtain good adhesion to the substrate when the average thickness of the adhesive layer is less than about 60% of the average thickness of the conductive elements. However, by making the adhesive layer thinner than the conductive element, typically with an average thickness of about 90% or less of the average thickness of the conductive element, a permanently low electrical resistance can be obtained in the preferred construction. Electrical connection is obtained. Best results are obtained when the average thickness of the adhesive layer is about 70% to 80% of the average thickness of the conductive elements. As is clear from the above description, the upper edge of substantially all of the conductive elements is preferably higher than at least a portion of the adhesive layer surrounding the conductive elements in order to permanently obtain a good electrical connection with low electrical resistance. . That is, substantially each conductive particle (conductive element) in FIG.
14 is larger than on the outer surface of the adhesive surrounding the conductive particles. Preferably, substantially all of each conductive element is higher than the upper edge of the surrounding adhesive layer. Also,
Preferably, the conductive elements are separated from each other by an average distance that is at least as large as the average diameter of the conductive elements themselves. Typically, it is preferred that the separation distance be at least four times the average diameter to allow the flexible support to fit around the conductive element during the bonding operation. On the other hand, the conductive elements make up at least 2% of the sheet material.
Preferably, it accounts for at least 4%, and more preferably at least 4%. A layer 15 of electrically insulating material has a thickness of 10 on conductive particles (conductive elements) 14 of the structure shown in FIGS.
It provides effective electrical insulation even when it is as thin as a micrometer. A resistance value of at least 1 megohm through layer 15 to the conductive particles must be achieved. Resistance is measured by placing the test sample on a 1 cm square copper substrate with the outer surface of the insulating layer of the sample facing the substrate and then placing a 500 g weight on the test sample at room temperature. An electrical connection is previously made between the metal conductor and a conductive layer, such as the conductive stripes 12 of sheet material shown in FIGS. Ground the copper board and connect it to the metal conductor 5
Apply a voltage in volts and then measure the resistance of the circuit. The electrically insulating layer 15 includes conductive particles (conductive elements) 14
Preferably, it is of the same or similar material to the adhesive material 13 of the conductive adhesive layer in which is dispersed. The thermal tack adhesives taught in the above co-pending application are preferred materials. One advantage is that it can be bonded over a wide temperature range so that the adhesive connection is maintained even if the bonding surfaces are not cooled to room temperature. In some cases, the electrically insulating layer is comprised of various heat-adhesive adhesives having a lower glass transition temperature (Tg) than the adhesive material of the electrically conductive adhesive layer, in which electrically conductive particles (conductive elements) are dispersed. You can leave it there. higher
Tg adhesive materials provide a stronger bond at room temperature. On the other hand, a low Tg electrically insulating layer flows easily at high temperatures, yet facilitates the formation of the desired adhesive bond. Other adhesive materials such as hot melt adhesives or hot reactive compositions may also be used. In the embodiment of the sheet material shown in FIGS. 1 and 2, the conductive particles (conductive elements) 14 are only partially embedded in the layer of non-conductive adhesive material 13. The electrically insulating layer 15 also exhibits a generally constant thickness and conforms to the contours indicated by the protruding conductive particles 14. The result is that there are small valleys between adjacent particles in which the electrically insulating material can advantageously flow during high temperature and pressure bonding operations. If adhesive material 13 and conductive particles 14 are placed only on conductive stripes 12, movement of electrically insulating material 15 will leave further valleys between adjacent conductive stripes. In another embodiment of the sheet material of the invention,
For example, if the conductive particles are embedded in an adhesive layer that is substantially the same thickness as the particles, the outer surface of the insulating layer will be planar. Such embodiments are preferably used for bonding to uneven terminal substrates having raised areas to be bonded. In this case, when heat and pressure are applied, the insulating material flows into the recessed portion of the mating substrate, and when cooled, it is firmly bonded to the recessed portion. For example, the terminal pads may be slightly elevated. The embodiment of the sheet material shown in FIGS. 1 and 2 illustrates other desirable features of the invention. That is, the adhesive surface of the sheet material is preferably contoured by recessing at least a portion of the surface of the adhesive, such as the portion over the space between the conductive stripes, below the other portion of the adhesive surface. Therefore,
Some of the adhesive material in the upper part of the conductive stripes can migrate into the recessed areas between the conductive stripes during the bonding operation, and the conductive elements are kept in tighter electrical connection with the substrate. Such movement occurs in proportion to the flow rate of the electrically insulating and adhesive materials and the degree of heat and pressure applied to the adhesive materials during the bonding operation. Because the heat-adhesive adhesive material does not flow extensively during the gluing operation, the flexible insulating support can adapt to the thickness that defines the adhesive layer. The insulating layer 15 of the embodiment of FIGS. 1 and 2 is of fairly constant thickness, yet has underlying protruding conductive particles 1.
4 and adhesive material 13. After bonding to a substrate, the contact surface of the sheet material of the present invention generally changes to conform to the shape of the surface of the substrate. A terminal board in which the sheet material of the present invention is used is planar with the terminal pads embedded within the board, and is also coplanar with the rest of the board. In this case, the sheet material of the invention forms a generally planar, all-over contact with the substrate. However, preferably the terminal pads are slightly elevated as described above. in the finished bond, in a proportion sufficient to allow the necessary dielectric breakdown through the adhesive material and in a proportion sufficient to obtain electrical conductivity between the conductive stripe and the substrate to which the sheet material is bonded; The conductive element occupies a portion of the adhesive bond thickness. Preferably, the conductive element occupies a small portion of the area of the adhesive surface to ensure a substantial portion of the adhesive contacting the adherend, and that the conductive element covers a small area relative to the area of the conductive stripes. A conductive adhesive layer consisting of an adhesive material and a conductive element is electrically conductive throughout the layer but not laterally within the layer. In some embodiments of the invention, as shown in FIG. The need for limited coverage of conductive adhesive on the stripes only is eliminated. Since the conductive adhesive layer is not laterally conductive, adjacent stripes 21 are electrically isolated from each other. Conductive particles (conductive elements) 22 in the conductive adhesive layer penetrate the adhesive and the electrical insulation to provide an electrical connection between the conductive stripes 21 and the terminal pads with which the stripes are aligned. FIG. 4 shows an electrically insulating layer 26 and a conductive adhesive 2.
7 is applied only on the conductive stripes 28 and the spaces between the conductive stripes are filled with a different adhesive 29. For example, pressure sensitive adhesives can be used to impart room temperature adhesion to the sheet material to the substrate. In this case, after adhesion of the pressure-sensitive adhesive, adhesion to the substrate is ensured by heating and pressing the conductive adhesive on the conductive stripes 28 and the electrically insulating layer thereon. A hot melt or heat-reactive adhesive may also fill the spaces between the conductive stripes. The sheet material of the present invention has a non-adhesive side, especially in the case of an elongated tape that can be wound onto itself in the form of a roll.
or having a low adhesion backing on a release liner disposed on the insulating layer. The sheet material of the present invention is generally prepared by aligning one end of the tape onto the desired substrate on which the connection is to be made;
It is generally applied by pressing the sheet material against the substrate and simultaneously heating the sheet material. The layer 13 of the product shown in FIGS. 1 and 2 may be non-adhesive at room temperature, for example for heat reaction to a durable firm state. The invention is further illustrated by the following examples. Example 1 Continuous 875 micrometer wide conductive stripes of silver spaced 875 micrometers apart are deposited on one side through a grooved mask onto an insulating support consisting of a 25 micrometer thick polyethylene terephthalate film. Formed. This conductive stripe is approximately 400 Å (40 nanometers) thick
It had an electrical resistance value of 4 ohms per 1 cm of length. The conductive adhesive consists of 94.9 parts by volume of an acrylic terpolymer containing 10.4% by weight of methyl methacrylate, 85.6% by weight of methyl acrylate, and 4% by weight of acrylamide dissolved in ethyl acetate with 5.1 parts by volume of silver particles as a conductive element. It was produced by mixing with. The silver particles are sieved through a 140 mesh sieve (US standard, mesh size 105 micrometers), lodged on a 170 mesh sieve (88 micrometers), and then passed through a roller mill until the silver particles are approximately 48 micrometers thick. flattened. A mixture of adhesive and silver particles was applied superimposed on the conductive stripes by applying through an aperture mask to form a conductive adhesive layer. After drying, the adhesive terpolymer occupied a thickness of approximately 20 micrometers. An electrically insulating layer consisting of an acrylic terpolymer containing 40% by weight ethyl acrylate, 56% by weight methyl acrylate, and 4% by weight acrylamide dissolved in ethyl acetate at a solids content of about 25% by weight was then applied by bar coating. Application to the entire surface of the sheet material coated the conductive adhesive applied over the conductive stripes and the film support between the conductive stripes. After drying, a layer of approximately constant thickness of about 10 micrometers was formed as shown in FIG. The ratio of the combined thickness of the adhesive and insulating layers (30 micrometers) to the average thickness of the particles was 62.5%. The resistance value of the layer measured by the above method is approximately
It was 1000 megohms. For comparison, a similar tape without the electrically insulating layer was produced and was found to exhibit a resistance of 10 ohms. 150 pounds per square inch (10.5
The tape was adhered to the conductive terminal pads of a printed circuit test board by pressing the tape with a force of 100 kg/cm2 and then heating the edge of the tape to a temperature of 170° C. for 5 seconds. After cooling, the resistance value at the connection was measured using a four-terminal resistance method and was found to be 10 milliohms. The support was roughened as shown in FIG. In addition, the peel strength of the adhesive against the substrate was measured by ASTM D-1000 and was 2.5.
It was found to be from pounds per inch width to 5 pounds per inch width (from 0.45 kg/cm to 0.9 kg/cm). Example 2 Flattened conductive particles approximately 40 micrometers thick, sufficient conductive adhesive material of a mixture with conductive particles to give an adhesive layer approximately 15 micrometers thick, and two different thicknesses, viz. One way (Example 2A)
is approximately 9 micrometers and the other (Example 2B) is approximately 21
Different tapes of the type described in Example 1 were made using micrometer insulating layers. The combined thickness to average particle ratio of the adhesive and insulating adhesive layers was 60% for Example 2A and 90% for Example 2B. A piece of tape was cut to size and adhered between a conductive pad on a printed circuit board and an indium tin oxide (ITO) deposited surface on a glass test panel using 200 psi pressure for 5 seconds at 150°C. Dual electrical connections made to the ITO test panel of each tape were monitored for individual contact electrical resistance using the 4-wire ohmic method. The test panels were repeatedly exposed to -40°C and 105°C every 4 hours. Table 1 below shows the results of the maximum contact electrical resistance values observed during the reported test period. The data show stable electrical performance even under the above-mentioned abuse conditions for structures with adhesive thickness in the range of 60% of the particle thickness, and that adhesive thickness is in the range of 90% of the conductive particle thickness. exhibits poor electrical performance in some cases. In other tests,
With fewer temperature cycles and shorter times, tapes with a 90% adhesive thickness to conductive particle thickness ratio provided adequate stability.

Table 1: (1) To give probe tack values at various test temperatures, the probe and annular weight are heated to the test temperature except that the annular weight is not heated above 220°C. (2) The probe end is a ring with inner and outer diameters of 3.83 mm and 5.10 mm. (3) The annular weight is 19.8g. (4) Perform as described in ASTM D-2979 except for a 10 second pause to determine probe tackiness. 2 Shear values are determined by heating bright annealed stainless steel panels in an oven for 15 minutes at 115° C. above the weight average Tg of the adhesive polymer. With the steel panel horizontal, run one section of 1.27 cm wide tape twice in each direction to meet Federal Standards standards.
Adhere to the steel panel using a 20.4Kg hand roller matching 147. The length of tape that adhered to the panel was trimmed to exactly 1.27 cm long and the assembly was left at the bonding temperature for 15 minutes longer. The plate is transferred to a dryer with a shear stand that provides a 2° backward slope of the panel at its top (the shear weight advances the tape slightly into the panel). After 15 minutes at 65°C, a 1Kg weight is suspended from the free end of the tape. The time after which the weight falls is the shear value of 65°C.

[Brief explanation of drawings]

FIG. 1 is an enlarged perspective view of the distal end portion of an exemplary electrical connector tape of the present invention, and FIG. 2 is a cross-sectional view of the exemplary electrical connector tape of the present invention shown in FIG. 3 and 4 are cross-sectional views of various exemplary electrical connector tapes of the present invention. 10: Tape, 11: Flat electrical insulating sheet support (web or film), 12, 21, 2
8: Conductive stripe, 13: Non-conductive adhesive material, 1
4, 22: Conductive particles (conductive element), 15: Thin layer of electrically insulating material (electrically insulating layer), 20, 27: Conductive adhesive layer (conductive element + non-conductive adhesive), 26: Electrically insulating layer, 29 :glue.

Claims (1)

Claims: 1. In a sheet material suitable for forming a bonded electrical connection to a substrate, in order: (A) a support of an insulating web or film; (B) on said support; (C) a plurality of narrow parallel stripes formed over a limited portion of the support; (C) disposed in contact with the conductive strip;
a conductive adhesive layer comprising a non-conductive heat-activated adhesive material having discrete conductive elements substantially the same thickness or thicker as the adhesive layer dispersed therein in a single layer; (D) a thin electrically insulating layer disposed over the monolayer of the conductive element, the outer surface of which extends along the underlying conductive element and adhesive layer; , a thin electrically insulating layer defining a contour, and the electrically insulating layer (a) has an electrical resistance through the layer to the conductive element of at least 1 megohm; and (b) is nonconductive at room temperature. tacky or poorly tacky;
Unless it is fluidized by heating, it has virtually no adhesive properties; (c) it softens when heated to high temperatures and exhibits adhesive properties and becomes fluid; and (d) it becomes strong and fluid when cooled to room temperature again. the sheet material is substantially non-flowable, thereby facilitating handling at room temperature, and the sheet material is compressed against the substrate;
By heating, the conductive element is integrated with the substrate, and the conductive element penetrates the electrically insulating layer to form an electrical connection with the substrate, and by cooling, a strong bond is formed with the substrate. A sheet material characterized by: 2. A sheet material according to claim 1, wherein the majority of the conductive elements have a thickness greater than the thickness of the adhesive layer.