JPWO2017043455A1 - Conductive adhesive composition, conductive adhesive sheet and wiring device using the same - Google Patents

Abstract

For example, in the case of producing a flexible wiring device, when the main curing adhesion time is shortened in the main curing adhesion of the conductive reinforcing plate and the flexible wiring board via the conductive adhesive composition layer, In the reflow soldering process, there are cases where problems relating to adhesiveness such as peeling off occur in the laminate. SOLUTION: NBR having a carboxyl group, an epoxy resin, a curing agent, and a conductive material, and the weight average molecular weight of the NBR having a carboxyl group is 5,000 to 1,000,000, and contains a nitrile monomer unit. By setting the amount to 5 to 45% by mass, it is possible to provide a conductive adhesive composition that does not cause problems such as peeling to the laminate even if the main curing time is shortened. [Selection figure] None

Description

  The present invention is formed of a conductive adhesive composition, a conductive adhesive sheet, and a cured product of a conductive adhesive composition for bonding an electronic circuit board and a conductive reinforcing plate in a process of mounting an electronic component. The present invention relates to a wiring device formed by bonding with an adhesive layer.

  Electronic devices such as OA devices, communication devices, and mobile phones have been further improved in performance and size. A flexible printed wiring board (hereinafter, also referred to as FPWB), which is one of the wiring devices mounted on these, is an internal part that is arranged in a narrow and complex space of an electronic device by utilizing its bendable characteristics. Widely used as a substrate.

  On the other hand, due to high-density mounting due to an increase in the amount of information supplied to electronic circuits and higher operating signal frequency, there has been a concern about malfunction of internal circuits due to electromagnetic noise, and there is a growing demand for countermeasures against electromagnetic waves for FPWB. ing.

  From the above demand, a wiring device in which a conductive reinforcing plate and an electronic circuit board are bonded via a conductive adhesive layer has been proposed (for example, Patent Document 1). This is because a conductive reinforcing plate using a metal such as stainless steel is attached to the FPWB via a conductive adhesive layer, thereby electrically connecting the conductive reinforcing plate to the ground circuit, thereby preventing electromagnetic wave shielding. The circuit signal can be stably transmitted.

  The process of producing a wiring device having such electromagnetic wave shielding characteristics includes the steps of forming a conductive adhesive composition layer surface and a conductive reinforcing plate of a conductive adhesive sheet in which a conductive adhesive composition layer is laminated on a peelable substrate. Temporary pressure bonding, and then the peelable substrate is peeled off from the conductive adhesive sheet, and FPWB is superimposed on the surface of the conductive adhesive composition layer of the laminate of the conductive reinforcing plate and the conductive adhesive composition layer, and then the temporary pressure bonding is performed. In addition, a method is known in which the conductive adhesive composition is fully cured in a heated and pressurized atmosphere.

  In addition, reflow soldering is generally used as a method for surface mounting electronic components such as chip components on the wiring device having the electromagnetic wave shielding characteristics manufactured as described above. The wiring device is heated in a reflow furnace during reflow soldering, and the conductive adhesive composition layer laminated between the conductive reinforcing plate and the FPWB is also exposed to the heat of the reflow furnace. In this case, problems that occur in the conductive adhesive composition layer include local defects such as pulverization, cracks, cracks, foaming, etc., when the adhesion to the conductive reinforcing plate or FPWB cannot be maintained (peeling), etc. It is known that there is.

  In order to improve the problems that occur in the conductive adhesive composition during reflow soldering, it is necessary to use a specific epoxy resin, curing agent, and conductive filler for the purpose of preventing peeling of the IC and the substrate. An adhesive has been proposed (for example, Patent Document 2).

  In addition, when the wiring device is stored under wet heat conditions, it is known that foaming is likely to occur in the conductive adhesive composition layer during reflow soldering, and these items are also IPC standards. In order to improve such heat and heat resistance reliability, a polyester resin in which a cyclic structure such as an aromatic ring or an aliphatic ring is directly incorporated next to an ester bond in the main chain, an epoxy curing agent, and a conductive filler Etc. have been proposed (for example, Patent Document 3).

JP2007-189091 Japanese Patent Laid-Open No. 5-1265 JP2012-211256

  In the step of thermocompression bonding the conductive reinforcing plate and the FPWB through the conductive adhesive composition layer, a main curing step that takes about 1 hour including the temperature rising and cooling time is passed, and then after-curing. It has become common. This is because, in a subsequent reflow soldering process, when a wiring device in which the conductive reinforcing plate and the FPWB are cured and bonded via the conductive adhesive composition layer is exposed to a high temperature, the conductive adhesive composition layer is Although it is a measure to form a sufficiently hardened and adhered state so that adhesion to the reinforcing plate and FPWB can be maintained, it is difficult to say that it is an efficient process in the process of producing electronic circuit boards. It was.

  Therefore, the present invention shortens the main curing bonding time when the conductive reinforcing plate and the FPWB are bonded by thermocompression bonding via the conductive adhesive composition layer (hereinafter also referred to as a quick press). Even if it does, in a reflow soldering process, the conductive adhesive composition which does not produce the problem regarding adhesiveness, such as peeling to a conductive reinforcement board or FPWB, a conductive adhesive sheet, and a wiring device using the same With the goal.

  As a result of intensive studies to solve the above problems, the present inventors have found that NBR (A) having a carboxyl group, epoxy resin (B), curing agent (D), and conductive material (E) The NBR (A) having a carboxyl group has a weight average molecular weight (Mw) of 5,000 to 1,000,000, and the nitrile monomer unit content based on the total mass of the NBR (A) having the carboxyl group 5 to 45 mass%, it is possible to perform reflow soldering even when a quick press is performed when the conductive reinforcing plate and the FPWB are heat-pressed and bonded through the conductive adhesive composition layer and finally cured and bonded. The present inventors have found that a conductive adhesive composition and a conductive adhesive sheet that do not cause problems in adhesiveness in the process can be formed, and have completed the present invention.

  That is, this invention (1) has NBR (A) which has a carboxyl group, an epoxy resin (B), a hardening | curing agent (D), and an electroconductive material (E), and NBR which has this carboxyl group The weight average molecular weight (Mw) of (A) is 5,000 to 1,000,000, and the nitrile monomer unit content is 5 to 45% by mass based on the total mass of NBR (A) having the carboxyl group. The conductive adhesive composition is characterized.

  The present invention (2) is the conductive adhesive composition according to the invention (1), wherein the acid value of the NBR (A) having a carboxyl group is 3 to 60 mgKOH / g.

  The present invention (3) is characterized in that a mass part ratio (A) / (B) between the NBR having a carboxyl group (A) and the epoxy resin (B) is 0.35 to 2.5. The conductive adhesive composition according to the invention (1) or (2).

  The present invention (4) is characterized in that a mass part ratio (B) / (D) of the epoxy resin (B) and the curing agent (D) is 1-1000, The conductive adhesive composition according to (2) or (3).

  The present invention (5) includes a peelable substrate and the conductive adhesive composition according to the invention (1), (2), (3) or (4) on one surface side of the peelable substrate. A conductive adhesive sheet comprising a conductive adhesive composition layer comprising:

  In the present invention (6), the conductive material (E) is at least one selected from conductive metal powder, conductive metal composite powder, and carbon powder, and the volume ratio in the conductive adhesive composition is The conductive adhesive composition according to the invention (1), (2), (3) or (4), which is 10 to 35% by volume based on the total volume (dry volume) of the conductive adhesive composition The surface-resistance value of the hardened | cured material of the said conductive adhesive composition layer is 5 ohms / square or less, It is a conductive adhesive sheet as described in the said invention (5) characterized by the above-mentioned.

  According to the present invention (7), the wiring board provided with the signal wiring and the conductive reinforcing plate provided on one surface side of the wiring board are the invention (1), (2), (3) or (4). It is adhere | attached through the hardened | cured material of the conductive adhesive composition layer formed from the conductive adhesive composition of description.

  According to this invention comprised as mentioned above, it has NBR (A) which has a carboxyl group, an epoxy resin (B), a hardening | curing agent (D), and an electroconductive material (E), and this carboxyl group The NBR (A) having a weight average molecular weight (Mw) of 5,000 to 1,000,000 and the nitrile monomer unit content of 5 to 45% by mass makes the conductive reinforcing plate and FPWB conductive adhesive. A conductive adhesive composition, a conductive adhesive sheet, and a conductive adhesive composition that do not cause a problem in adhesiveness in a reflow soldering process even when quick pressing is performed by thermocompression bonding and main-curing adhesion through the composition layer A wiring device using can be provided.

  That is, to the conductive adhesive composition after main curing obtained by the high heat resistance and adhesion of NBR (A) having a carboxyl group, the crosslinking reaction of epoxy resin (B) and NBR (A) having a carboxyl group, and the like. By providing the toughness, it is possible to obtain a conductive adhesive composition capable of sufficiently securing the adhesiveness in the reflow soldering process even if quick pressing is performed.

It is a figure for demonstrating the connection resistance value measuring point. It is a figure for demonstrating the connection resistance value measuring point. It is a figure for demonstrating the resin flow characteristic evaluation method.

Hereinafter, the form for implementing this invention is demonstrated concretely. However, the present invention is not limited to this form. Hereinafter, description will be given in the following order.
1. 1. Conductive adhesive composition 1-1. Component 1-2. Formulation 2. 2. Production method of conductive adhesive composition 3. Conductive adhesive sheet 4. Manufacturing method of conductive adhesive sheet 5. Use of conductive adhesive sheet Application example (wiring device)

<< 1. Conductive adhesive composition >>
The conductive adhesive composition according to the present invention includes an NBR (A) having a carboxyl group, an epoxy resin (B), a curing agent (D), and a conductive material (E). Other known additives may be blended. Hereinafter, each component will be described in detail.

<1-1. Ingredients>
{1-1-1. NBR having carboxyl group (A)}
The NBR (A) having a carboxyl group according to the present invention is a polymer (for example, acrylonitrile butadiene rubber) containing an α, β-ethylenically unsaturated nitrile monomer and butadiene as monomer units, and the carboxyl group. It is a polymer having Here, the α, β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group. For example, acrylonitrile, α-chloroacrylonitrile, α- Examples include α-halogenonitrile such as bromoacrylonitrile and α-alkylacrylonitrile such as methacrylonitrile. The α, β-ethylenically unsaturated nitrile monomer may be used alone or in combination of two or more. The butadiene is preferably 1,3-butadiene.

  Here, as NBR (A) having a carboxyl group, for example, a copolymer obtained by copolymerizing an α, β-ethylenically unsaturated nitrile monomer (for example, acrylonitrile) and butadiene (rubber by the first production method). Rubbers with carboxylated molecular chain ends, rubbers produced by the second production method, α, β-ethylenically unsaturated nitrile monomers (for example, acrylonitrile), butadiene and carboxylic acids having polymerizable unsaturated double bonds Examples thereof include terpolymer rubbers with monomers. In any method, if necessary, another monomer capable of copolymerization may be copolymerized. Here, as the carboxylic acid monomer (carboxyl group-containing monomer) in the second production method, for example, it can be copolymerized with an α, β-ethylenically unsaturated nitrile monomer and is not esterified. A monomer having one or more unsubstituted carboxyl groups. For example, examples of the carboxyl group-containing monomer used in the present invention include α, β-ethylenically unsaturated monocarboxylic acid monomers, α, β-ethylenically unsaturated dicarboxylic acid monoester monomers, and the like. It is done. More specific examples include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and the like. In addition, what was illustrated as these carboxylic acid monomers can also be used for the said carboxylation in a 1st manufacturing method. NBR (A) having a carboxyl group is a terpolymer of an α, β-ethylenically unsaturated nitrile monomer (for example, acrylonitrile), butadiene and a carboxylic acid monomer having a polymerizable unsaturated double bond. It may be a crosslinked rubber that is partially crosslinked by adding a crosslinkable monomer in the stage, or, if necessary, a crosslinked rubber that is made into particles after crosslinking.

  Although the manufacturing method of NBR (A) which has a carboxyl group of this invention is not specifically limited, It is preferable to copolymerize and manufacture the above-mentioned monomer by emulsion polymerization using an emulsifier. For emulsion polymerization, commonly used polymerization auxiliary materials such as known emulsifiers, polymerization initiators, molecular weight regulators and the like can be used.

  The NBR (A) having a carboxyl group according to the present invention has a weight average molecular weight (Mw) of 5,000 to 1,000,000, preferably 7,000 to 700,000, and more preferably 100,000 to 500,000. If the weight average molecular weight is less than 5,000, the heat resistance of the conductive adhesive composition after curing may decrease. If the weight average molecular weight exceeds 1,000,000, the viscosity of the conductive adhesive composition increases. There is a risk of problems in forming the sheet. The weight average molecular weight (Mw) of NBR (A) having a carboxyl group refers to a value in terms of polystyrene determined by gel permeation chromatography (GPC) measurement.

  The NBR (A) having a carboxyl group according to the present invention has a nitrile monomer unit content of 5 to 45% by mass based on the total mass of the NBR (A) having the carboxyl group, and preferably It is 10-35 mass%, More preferably, it is 20-35 mass%. If the nitrile monomer unit content is less than 5% by mass, the heat resistance of the conductive adhesive composition after curing may be reduced. If the nitrile monomer unit content exceeds 45% by mass, Since the viscosity of the conductive adhesive composition is increased, there is a possibility of causing a problem in the formation of the conductive adhesive sheet. The nitrile monomer unit content of NBR (A) having a carboxyl group according to the present invention is a value measured by Kjeldahl method according to JIS K 6384.

  Moreover, since NBR has a carboxyl group, it has an effect of making it easy to ensure adhesion with a conductive reinforcing plate or the like. Furthermore, from the viewpoint of improving the crosslink density with other substances constituting the conductive adhesive composition, it is more preferable that the carboxyl group has a carboxyl group in the side chain rather than at the end of the molecular skeleton. As a result, the cross-linking structure with the material constituting the conductive adhesive composition is easily three-dimensional, and it is presumed that it contributes to a decrease in the resin flow amount and an improvement in adhesion to the conductive reinforcing plate, FPWB, and the like. The The resin flow is a phenomenon in which the conductive adhesive composition flows out to an unintended area during the main curing, and in the current situation where the density of signal wiring has increased in recent years, the resin flow amount Is required to be less.

  The acid value of NBR (A) having a carboxyl group is preferably 3 to 60 mgKOH / g, more preferably 6 to 55 mgKOH / g, and still more preferably 20 to 50 mgKOH / g. The NBR (A) having a carboxyl group has an appropriate acid value, so that the crosslinking efficiency with the epoxy resin (B) is increased, and the conductive adhesive composition becomes conductive in the reflow soldering process even if quick pressing is performed. The effect that it becomes easy to maintain adhesiveness with a property reinforcement board and FPWB. When the acid value is lower than 3 mgKOH / g, the heat resistance of the conductive adhesive composition may be reduced. When the acid value is higher than 60 mgKOH / g, the flexibility of the conductive adhesive sheet may be reduced, or May not react completely with the epoxy group or the like, and there is a risk that the durability will be adversely affected. The acid value of NBR (A) having a carboxyl group is a value measured according to JIS K 0070: 1992. The acid value can be adjusted by controlling the blending ratio, reaction rate, reaction time, etc. of the polymer having carboxylic acid when the polymer is synthesized.

{1-1-2. Epoxy resin (B)}
The epoxy resin (B) according to the present invention is a compound having two or more epoxy groups in one molecule. The property of the epoxy resin (B) may be liquid or solid. As the epoxy resin (B), for example, glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, cycloaliphatic (alicyclic type) epoxy resin and the like are preferable. Examples of the glycidyl ether type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, cresol novolac type epoxy resin, phenol novolak type epoxy resin, α-naphthol. Novolac type epoxy resin, bisphenol A type novolac type epoxy resin, dicyclopentadiene type epoxy resin, tetrabromobisphenol A type epoxy resin, brominated phenol novolac type epoxy resin, tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) Ethane and the like can be mentioned. Examples of the glycidylamine-type epoxy resin include tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, triglycidylmetaaminophenol, tetraglycidylmetaxylylenediamine, and the like. Examples of the glycidyl ester type epoxy resin include diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, and the like. Examples of the cycloaliphatic (alicyclic) epoxy resin include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis (epoxycyclohexyl) adipate, and the like. Among these, it is preferable to consist of at least one selected from bisphenol A type epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, tris (glycidyloxyphenyl) methane, and tetrakis (glycidyloxyphenyl) ethane. . By using these epoxy resins, the adhesive strength of the conductive adhesive and the heat resistance after curing are further improved. Examples of commercially available bisphenol A type epoxy resins include YD-8125, YD-012 (manufactured by Tohto Kasei Co., Ltd.), jER1001, jER825, JER828, jER834 (manufactured by Mitsubishi Chemical Corporation), and the like.

{1-1-3. Curing agent (D)}
The curing agent (D) according to the present invention is preferably composed of at least one selected from an isocyanate curing agent, an amine curing agent, an aziridine curing agent, an imidazole curing agent, an acid anhydride, and a novolak phenol resin. By using these hardening | curing agents, it has the effect which the adhesive strength of a conductive adhesive composition and the heat resistance after hardening improve more. Examples of isocyanate-based curing agents include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, 1,5-one naphthalene diisocyanate, tetramethylxylylene diisocyanate, trimethylhexamethylene diisocyanate, and the like. Can be mentioned. Examples of the amine curing agent include diethylenetriamine, triethylenetetramine, methylene bis (2 chloroaniline), methylene bis (2 methyl-6 1 methylaniline), 1,5 1 naphthalene diisocyanate, and n 1 butylbenzyl phthalic acid. It is done. Examples of the aziridine-based curing agent include trimethylol propane-tree β-aziridinyl propionate, tetramethylol methane-tree β-aziridinyl propionate, N, N′-diphenylmethane-4,4′-one bis. (11 aziridine carboxamide), N, N ′ 1 hexamethylene-1,6 1 bis (1 aziridine carboxamide) and the like. Examples of the imidazole-based curing agent include 21-methylimidazole, 21-heptadecylimidazole, 21-phenyl-4-1-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, and the like. Examples of the acid anhydride include hexahydrophthalic anhydride and trimellitic anhydride. The novolak phenol resin is obtained by subjecting phenols and aldehydes to a condensation reaction in the presence of an acid catalyst. For example, as phenols, alkylphenol, paraphenylphenol, bisphenol A, resorcinol and the like can be mentioned. Examples of aldehydes include formaldehyde, paraformaldehyde, hexamethylenetetramine, and furfural. For example, heat resistance and mechanical strength at high temperatures can be imparted by using a novolak phenol resin. In addition, when a wiring device is subjected to stress by introducing a novolak phenol resin having a relatively large molecule in addition to NBR (A) and epoxy resin (B) having a carboxyl group into the conductive adhesive composition. It is presumed that the stress relaxation property of the conductive adhesive composition layer can be increased, and the adhesiveness between the conductive adhesive composition layer and the layer in contact with the conductive adhesive composition layer can be easily maintained.

{1-1-4. Conductive material (E)}
The conductive material (E) according to the present invention has a function of imparting conductivity to the conductive adhesive composition. Specifically, as the conductive material (E), for example, conductive metal powder made of a metal such as gold, silver, copper, lead, zinc, iron and nickel or an alloy thereof, and composite powder of the conductive metal And carbon powder. Examples of the composite powder include silver-coated copper powder, silver-coated nickel powder, gold-coated copper powder, and gold-coated nickel powder, but are selected from conductive metal powder, composite powder of conductive metal, and carbon powder. More preferably, it consists of at least one selected from the above. Examples of the shape of the conductive material (E) include spherical powder, flaky powder, disk-shaped powder, dendritic powder, needle-shaped powder, and irregular-shaped powder. The average particle size of the conductive material (E) is preferably 1 to 50 μm, and more preferably 5 to 20 μm. If it exceeds 50 μm, the surface property of the conductive adhesive sheet becomes rough, and if it is less than 1 μm, it tends to be difficult to secure a contact between the conductive materials. In addition, when the conductive material has a spherical shape, the average particle diameter of the conductive material is a value obtained by selecting about 10 to 20 particles from an enlarged image obtained by a scanning electron microscope and averaging the diameters. . In addition, when the length in the longitudinal direction and the length in the short direction are greatly different, the equivalent-circle diameter of the projected area of the conductive material was calculated and used as the average particle diameter.

<1-2. Formulation>
Next, the ratio between components and the amount of components in the conductive adhesive composition according to the present invention will be described.

{1-2-1. (A) / (B) ratio}
First, it is preferable that mass part ratio (A) / (B) of NBR (A) which has the said carboxyl group, and the said epoxy resin (B) is 0.35-2.5, 0.4-2. 3 is more preferable. By setting it as the said range, it has the advantage that the provision of the film formability at the time of making a conductive adhesive composition into a sheet, adjustment of resin flow characteristics, and heat resistance becomes easy. If the mass part ratio (A) / (B) is less than 0.35, the resin flow rate may increase. Moreover, when mass ratio (A) / (B) exceeds 2.5, there exists a possibility that the heat resistance after hardening of a conductive adhesive composition may fall.

{1-2-2. (B) / (D) ratio}
Furthermore, the mass part ratio (B) / (D) of the epoxy resin (B) and the curing agent (D) is preferably 1 to 1000, more preferably 2.8 to 500, 200 is particularly preferable. If the mass part ratio (B) / (D) is less than 1, the adhesion with the conductive reinforcing plate or FPWB to be the adherend may be lowered, and if it exceeds 1000, the conductive adhesive composition Heat resistance after curing may be reduced.

{1-2-3. Addition amount of conductive material (E)}
The amount of the conductive material (E) added in the conductive adhesive composition is preferably 10 to 35% by volume, more preferably, based on the total volume (dry volume) of the composition. 15 to 30% by volume. If the amount added is less than 10% by volume, the conductivity and electromagnetic wave shielding properties may be reduced. If the amount added is 35% by volume or more, the adhesiveness to the peelable substrate may be reduced. There is.

≪2. Method for producing conductive adhesive composition >>
The conductive adhesive composition of the present invention can be produced by stirring and mixing the above raw materials and solvent. In preparing the conductive adhesive composition, it is preferable to add a solvent in order to uniformly disperse the conductive material (E).

  The solvent is preferably methyl ethyl ketone, acetone, methyl isobutyl ketone, 2-ethoxyethanol, toluene, butyl cellosolve, methanol, ethanol, 2-methoxyethanol or the like having a relatively low boiling point. Further, a high-boiling solvent may be added in order to adjust the drying rate at the time of coating described later. As the high boiling point solvent, dimethylacetamide, dimethylformamide, methylpyrrolidone, and cyclohexanone are preferable.

  The stirring and mixing can be performed by, for example, a scandex, a paint conditioner, a sand mill, a raking machine, a triple roll, a bead mill, or a combination thereof. Furthermore, it is preferable to perform vacuum defoaming in order to remove bubbles from the conductive adhesive composition after stirring and mixing.

≪3. Conductive adhesive sheet >>
The conductive adhesive sheet of the present invention is a sheet having a conductive adhesive composition layer formed by applying and drying a conductive adhesive composition on a peelable substrate. The conductive adhesive sheet may be referred to as a conductive film.

  As the peelable substrate, a polyester film, a polyethylene film, a polypropylene film, a polyimide film or the like, a film subjected to a release treatment on them, or the like can be used.

  Although the thickness of a conductive adhesive composition layer can be determined suitably, it is 10-200 micrometers normally from viewpoints, such as an adhesive characteristic and electroconductivity, Preferably it is good to set it as 25-100 micrometers.

  The surface resistance value of the cured product of the conductive adhesive composition layer according to the present invention is preferably 5 Ω / □ or less, and more preferably less than 1 Ω / □. If the surface resistance value exceeds 5Ω / □, the electromagnetic shielding properties may be deteriorated. The surface resistance value according to the present invention can be measured according to JIS K 7194.

<< 4. Manufacturing method of conductive adhesive sheet >>
As described above, the conductive adhesive sheet of the present invention can be produced by applying and drying a conductive adhesive composition on a peelable substrate.

  Here, as a coating method of the conductive adhesive composition, knife coating, die coating, lip coating, roll coating, curtain coating, bar coating, gravure coating, flexo coating, dip coating, spray coating, spin coating, etc. are preferable. .

≪5. Use of conductive adhesive sheet >>
Next, the use of the conductive adhesive sheet according to the present invention will be described. The conductive adhesive sheet of the present invention is preferably used as an adhesive sheet for attaching an electronic circuit board to be electrically connected and a conductive reinforcing plate. As a method of use, the two can be strongly bonded by pressing them together and heating them.

  The conductive reinforcing plate is made of, for example, a plate or sheet of metal such as stainless steel, aluminum, or copper, and specifically includes a reinforcing plate used for a flexible printed circuit board. Can be mentioned.

  The conductive adhesive composition and the conductive adhesive sheet of the present invention are widely used not only for bonding the electronic circuit board and the conductive reinforcing plate but also for bonding conductive members such as building materials, vehicles, aircraft, ships, etc. can do.

≪6. Application example (wiring device) >>
Moreover, the conductive adhesive sheet of this invention can manufacture the wiring device of this invention using the conductive adhesive composition layer. This wiring device is composed of a wiring board provided with signal wiring, a conductive reinforcing plate provided on one side of the wiring board, and a cured product of a conductive adhesive composition layer, which is electrically conductive with the wiring board. Exhibits the function of bonding to the reinforcing plate. In such a wiring device, for example, a wiring board and a conductive reinforcing plate are temporarily attached via a semi-cured conductive adhesive composition layer to form a laminated body, and then the laminated body is heated at a high temperature. By doing this, the wiring board and a conductive reinforcement board can be adhere | attached by carrying out this hardening of the conductive adhesive composition layer. A cured product of the conductive adhesive composition layer having excellent adhesive strength and heat resistance can be obtained by this curing. The main curing conditions can be carried out under the normal main curing conditions of heating temperature: 140 to 210 ° C., pressurizing pressure: 1 to 12 MPa, and press time: 1 hour, but the conductive adhesive composition of the present invention is used. For example, the heating temperature is 140 to 190 ° C., the pressure is 1 to 5 MPa, and the pressing time is less than 10 minutes. This can contribute to shortening the manufacturing process time for manufacturing the wiring device. In addition, the quick press in this invention refers to the conditions of temperature: 140-190 degreeC, pressure: 1-5MPa, and press time: less than 10 minutes.

  The wiring board includes an insulating substrate, a signal wiring provided on the insulating substrate, and an insulating layer provided on the insulating substrate so as to cover the signal wiring. Usually, in the wiring device, the insulating layer of the wiring board and the conductive reinforcing plate are bonded. Moreover, it is preferable that the wiring board further includes a ground wiring in addition to the signal wiring. By making an electrical connection with the ground wiring by using the conductive reinforcing plate, the conductive reinforcing plate can function as an electromagnetic wave shielding layer. As a constituent material of the conductive reinforcing plate, a conductive metal and its alloy are preferable. Specific examples of the constituent material of the conductive reinforcing plate include stainless steel and aluminum. As a method for obtaining the electrical connection, a through-hole is formed in the insulating layer and a conductive adhesive composition is filled in the through-hole, or a conductive adhesive composition is formed by thermocompression bonding during main curing. For example, a method of flowing the material layer to fill the through holes may be used.

  The wiring board is preferably a flexible printed wiring board (FPWB). When the wiring board is FPWB, the constituent material of the insulating substrate and the insulating layer is preferably a heat-resistant resin material such as polyimide or liquid crystal polymer. On the other hand, when the wiring board is a rigid wiring board, glass epoxy is preferable as a constituent material of the insulating substrate and the insulating layer (insulating base material). By forming the insulating substrate and the insulating layer with such a material, the insulating substrate and the insulating layer exhibit high heat resistance.

  The wiring device of the present invention described above can be used for a touch panel type liquid crystal display or the like, or a mobile phone, a smartphone, a tablet terminal or the like incorporating them. Moreover, the conductive adhesive composition and the conductive adhesive sheet of the present invention can be used for production of a wiring device and can be used for various applications requiring conductivity. Note that the signal wiring and the ground wiring included in the wiring board may form a circuit having a desired function.

  EXAMPLES Next, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to these specific examples at all.

Example 1
<Method for synthesizing NBR having carboxyl group>
In a reaction vessel, 180 parts of ion-exchanged water, 25 parts of a 10% strength by weight aqueous sodium dodecylbenzenesulfonate solution, 28.0 parts of acrylonitrile, 3 parts of mono-n-butyl maleate, and t-dodecyl mercaptan (molecular weight modifier) 0 After adding 5 parts in order and replacing the inside with nitrogen, 43 parts of 1,3-butadiene were charged. While maintaining the reactor at 5 ° C., 0.1 part of cumene hydroperoxide (polymerization initiator) was added and stirred. After 18 hours of polymerization reaction, 0.1 part of 10% strength aqueous hydroquinone solution (polymerization terminator) was added to terminate the polymerization reaction, and then the residual monomer was removed using a rotary evaporator at a water temperature of 60 ° C. NBR with Next, after adding 2 volumes of methanol to the obtained NBR having a carboxyl group and coagulating it, the solid matter was taken out by filtration, and this was vacuum-dried at 60 ° C. for 12 hours to obtain an NBR solid matter having a carboxyl group. Got. The obtained NBR having a carboxyl group had an acrylonitrile monomer unit content of 27% by mass, a weight average molecular weight of 300,000, and an acid value of 34 mgKOH / g.

<Method for Preparing Conductive Adhesive Composition>
Epoxy is used for 100 parts by mass of non-volatile content of NBR (component A) having a carboxyl group having a weight average molecular weight of 300,000, a nitrile monomer unit content of 27% by mass, and an acid value of 34 mgKOH / g obtained by the above synthesis method. Resin (component B) (Mitsubishi Chemical Co., Ltd., product name: jER1001) 100 parts by mass, (Component D) 10 parts by mass of 2-phenyl-4,5-dihydroxymethylimidazole added to 186 parts by mass of methyl ethyl ketone, further conductive Disperser (E component) (product name: ACAX-2, manufactured by Mitsui Mining & Smelting Co., Ltd.) was added to a dry volume of 17.5% by volume based on the total volume of the conductive adhesive composition. The mixture was stirred and mixed to obtain the conductive adhesive composition of Example 1.

<Preparation of conductive adhesive sheet>
The conductive adhesive composition obtained above was applied to a peelable substrate made of polyethylene terephthalate having a thickness of 38 μm and coated with a silicone mold release agent on one side using a comma coater. A conductive adhesive composition layer having a film thickness of 40 μm was formed by heating and drying for minutes, and the conductive adhesive sheet of Example 1 was produced.

Example 2
Using NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 350,000, a nitrile monomer unit content of 27% by mass, and an acid value of 34 mgKOH / g, using the same synthesis method as in Example 1. Except for the above, the conductive adhesive composition and conductive adhesive sheet of Example 2 were obtained in the same manner as Example 1.

Example 3
Using the same synthesis method as in Example 1, except that NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 7000, a nitrile monomer unit content of 27% by mass, and an acid value of 34 mgKOH / g was used. In the same manner as in Example 1, the conductive adhesive composition and the conductive adhesive sheet of Example 3 were obtained.

Example 4
Using the same synthesis method as in Example 1, NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 900,000, a nitrile monomer unit content of 27% by mass, and an acid value of 34 mgKOH / g was used. Except that, the conductive adhesive composition and conductive adhesive sheet of Example 4 were obtained in the same manner as Example 1.

Example 5
Using NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 300,000, a nitrile monomer unit content of 10% by mass, and an acid value of 34 mgKOH / g, using the same synthesis method as in Example 1. Except for the above, the conductive adhesive composition and conductive adhesive sheet of Example 5 were obtained in the same manner as Example 1.

Example 6
Using the same synthesis method as in Example 1, NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 300,000, a nitrile monomer unit content of 40% by mass, and an acid value of 34 mgKOH / g was used. Except for the above, the conductive adhesive composition and conductive adhesive sheet of Example 6 were obtained in the same manner as Example 1.

Example 7
Using the same synthesis method as in Example 1, NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 300,000, a nitrile monomer unit content of 27% by mass, and an acid value of 6 mgKOH / g was used. Except for the above, the conductive adhesive composition and conductive adhesive sheet of Example 7 were obtained in the same manner as Example 1.

Example 8
Using the same synthesis method as in Example 1, NBR (component A) having a carboxyl group adjusted to a weight average molecular weight of 300,000, a nitrile monomer unit content of 27% by mass, and an acid value of 55 mgKOH / g was used. Except for the above, the conductive adhesive composition and conductive adhesive sheet of Example 8 were obtained in the same manner as Example 1.

Example 9
43 parts by mass of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name: jER1001) with respect to 100 parts by mass of the nonvolatile content of NBR having a carboxyl group of Example 1, 2-phenyl-4,5-dihydroxymethylimidazole as a curing agent 7 parts by weight is added to 186 parts by weight of methyl ethyl ketone, and a conductive material (Mitsui Metal Mining Co., Ltd., product name: ACAX-2) is 17.5 in dry volume based on the total volume of the conductive adhesive composition. A conductive adhesive composition and a conductive adhesive sheet of Example 9 were obtained in the same manner as Example 1, except that the volume% was added.

Example 10
233 parts by mass of epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name: jER1001) and 2-phenyl-4,5-dihydroxymethylimidazole as a curing agent with respect to 100 parts by mass of NBR having a carboxyl group in Example 1 17 parts by weight is added to 186 parts by weight of methyl ethyl ketone, and further a conductive material (product name: ACAX-2, manufactured by Mitsui Kinzoku Mining Co., Ltd.) is 17.5 in dry volume based on the total volume of the conductive adhesive composition. A conductive adhesive composition and a conductive adhesive sheet of Example 10 were obtained in the same manner as Example 1 except that the volume% was added.

Example 11
The conductive adhesive composition of Example 11 and conductive properties were the same as Example 1 except that the amount of 2-phenyl-4,5-dihydroxymethylimidazole (D component) added was 7 parts by mass. An adhesive sheet was obtained.

Example 12
The conductive adhesive composition of Example 12 and conductive properties were the same as Example 1 except that the amount of addition of 2-phenyl-4,5-dihydroxymethylimidazole (component D) was 36 parts by mass. An adhesive sheet was obtained.

Example 13
A conductive adhesive composition and a conductive adhesive sheet of Example 13 were obtained in the same manner as in Example 1 except that the epoxy resin (component B) was changed to (Mitsubishi Chemical Corporation, product name: jER806). .

Example 14
A conductive adhesive composition and a conductive adhesive sheet of Example 14 were obtained in the same manner as in Example 1 except that the curing agent (component D) was changed to diaminodiphenylmethane.

Example 15
The conductivity of Example 15 was the same as Example 1 except that the conductive material (E component) was added to a dry volume of 35% by volume based on the total volume of the conductive adhesive composition. An adhesive composition and a conductive adhesive sheet were obtained.

Example 16
The conductivity of Example 16 was the same as Example 1 except that the conductive material (E component) was added so that the dry volume was 10% by volume based on the total volume of the conductive adhesive composition. An adhesive composition and a conductive adhesive sheet were obtained.

Examples az and examples aa-ac
NBR Mw, nitrile monomer unit content, NBR acid value, NBR (A) / epoxy resin (B) ratio, and epoxy resin (B) / curing agent (D) ratio were changed to the values shown in the table. In the same manner as in Example 1, conductive adhesive compositions and conductive adhesive sheets of Examples az and Examples aa-ac were obtained.

Comparative Example 1
Comparative Example as in Example 1 except that NBR having a carboxyl group was changed to NBR having no carboxyl group (weight average molecular weight: 300,000, nitrile monomer unit content: 27% by mass) 1 conductive adhesive composition and a conductive adhesive sheet were obtained.

Comparative Example 2
The conductive adhesive composition of Comparative Example 2, the conductive material was the same as Example 1 except that NBR having carboxyl was changed to an acrylic resin having a carboxyl group having a weight average molecular weight of 500,000 and an acid value of 20 mgKOH / g. An adhesive sheet was obtained.

Comparative Example 3
The conductive adhesive composition of Comparative Example 3 and the conductive material were the same as Example 1 except that the epoxy resin (B component) was not added and the addition amount of the conductive material (E component) was 21 parts by mass. An adhesive sheet was obtained.

Comparative Example 4
Except not adding a hardening | curing agent (D component), it carried out similarly to Example 1, and obtained the conductive adhesive composition and the conductive adhesive sheet of the comparative example 4.

Comparative Example 5
A comparison was made in the same manner as in Example 1 except that NBR (component A) having a carboxyl group with a weight average molecular weight of 3150 and an acid value adjusted to 32 mgKOH / g was used by the same synthesis method as in Example 1. The conductive adhesive composition and conductive adhesive sheet of Example 5 were obtained.

Comparative Example 6
The conductivity of Comparative Example 6 was the same as Example 1 except that NBR having a carboxyl group (component A) was changed to SBR (styrene butadiene rubber) having a weight average molecular weight of 300,000 having no nitrile monomer. Conductive adhesive composition and conductive adhesive sheet were obtained.

Comparative examples a and b
Except having changed MBR of NBR or nitrile monomer unit content, it carried out similarly to Example 1, and obtained the conductive adhesive composition of Comparative Examples a and b, and the conductive adhesive sheet.

<Evaluation method>
The evaluation methods of the conductive adhesive sheets and the like of the examples and comparative examples prepared above will be described below.

Preliminary pressure bonding Examples, a 25 μm thick copper foil reinforcing plate is laminated on the surface of the conductive adhesive composition layer of the conductive adhesive sheet produced in the comparative example, and conditions of 120 ° C., 0.2 MPa, 0.5 m / min. Then, a temporary press-bonding test sample in which the conductive adhesive sheet and the copper foil reinforcing plate were temporarily press-bonded was produced by passing between the hot rolls. The peelable substrate end of the temporary pressure bonding test sample is set on a Tensilon universal material testing machine (RTG-1210) and peeled at a rate of 100 mm / min in the 90 ° direction to reinforce the conductive adhesive composition layer and the copper foil. The provisional press-bonding property of the plate was evaluated. ○ when the peeling of the peelable substrate can be completed in a state where the adhesion between the conductive adhesive composition layer and the copper foil reinforcing plate is maintained, even if the conductive adhesive composition layer is partially from the copper foil reinforcing plate When it peeled off, it was judged as x. If the adhesion between the copper foil reinforcing plate and the conductive adhesive composition layer is maintained in this evaluation, it can be used for practical use without problems.

Resin flow characteristics Peel off the peelable substrate of the conductive adhesive sheet with a copper foil reinforcing plate prepared under the same temporary pressure bonding conditions as in the temporary pressure bonding test, and a polyimide film having a larger area than the conductive adhesive sheet on the surface Resin flow of Examples and Comparative Examples by stacking 6 and heat-pressing with a vacuum press machine at 160 ° C., 4 MPa for 5 minutes, and then after-curing in an oven at 160 ° C. for 60 minutes. A sample for characteristic evaluation was prepared. As shown in FIG. 3, the resin flow amount was evaluated based on the protruding distance L of the conductive adhesive composition 7 protruding in the normal direction from either side of the copper foil reinforcing plate 1, and the portion with the largest protrusion The average value of the portion with the least protrusion was taken as the resin flow value. The case where the resin flow value was less than 1.0 mm was judged as ◯, and the case where the resin flow value was 1.0 mm or more was judged as ×. If the said value is less than 1.0 mm, it is a level which can be used without a problem practically.

Adhesive strength Each sample for resin flow property evaluation and each sample obtained by changing the polyimide film 6 to a copper foil with a thickness of 25 μm were prepared, and in accordance with JIS K6854-1 using a Tensilon universal material testing machine (RTG-1210). The adhesive strength between the conductive adhesive composition layer and the polyimide film and between the conductive adhesive composition layer and the copper foil was measured. As long as the adhesive strength is 5 N / cm or more, there is no practical problem.

Connection Resistance Value A connection resistance evaluation method will be described with reference to FIGS. A laminated body obtained by temporarily press-bonding a conductive adhesive composition layer composed of the conductive adhesive compositions of Examples and Comparative Examples and a copper foil reinforcing plate having a thickness of 25 μm (FIG. 1, copper foil reinforcing plate 1 and conductive adhesive) The conductive adhesive composition layer 2 surface of the laminate of the agent composition layer 2) is imitated with a polyimide film substrate 3 having a ground hole 5 having an opening diameter of 1 mm and a ground circuit imitating a connection portion with the ground circuit. The laminated body with the copper plate 4 was superposed in the manner shown in FIG. 1, and after the main curing with a vacuum press machine at 160 ° C. and 4 MPa for 5 minutes in a quick press condition, in an oven at 160 ° C. for 60 minutes. After curing, a connection resistance value measurement sample having a cross section as shown in FIG. 2 was prepared. Using this measurement sample, the connection resistance value in the thickness direction between the copper foil reinforcing plate 1 and the copper plate 4 was measured by a surface resistance meter Loresta AX MCP-T370. A case where the connection resistance value was less than 0.3Ω was judged as ◯, and a case where the connection resistance value was 0.3Ω or more was judged as ×. If the connection resistance value is less than 0.3Ω, it can be determined that the connection resistance value is sufficient, and electromagnetic wave shielding properties can be secured.

The surface-resistivity example was laminated on the surface of the conductive adhesive composition layer of the conductive adhesive sheet prepared in the comparative example on the surface where the peelable substrate was not attached, 160 ° C., 4 MPa, After thermocompression bonding with a vacuum press machine under a quick press condition for 5 minutes, after-curing using an oven at 160 ° C. for 60 minutes, and after cooling, a peelable substrate on both sides of the conductive adhesive composition layer Was peeled off to obtain a sample for measuring the surface resistivity of only the electrically cured adhesive composition layer. Using this evaluation sample, the surface resistivity was measured by a four-probe method. Generally, the electromagnetic wave shielding effect required for the conductive adhesive composition layer itself is 40 dB or more (electromagnetic wave shielding rate 99%) when the electric field shielding performance measured by the KEC method (Kansai Electronics Industry Promotion Center method) is 10 to 1000 MPa. If the surface resistivity is less than 1.0Ω / □, this can be satisfied, but if the surface resistivity is 5.0Ω / □ or less, there is no practical problem. Since the electromagnetic wave shielding effect can be obtained in a range, the surface resistivity is less than 1.0 Ω / □, ◎, 1.0 Ω / □ or more, and 5.0 Ω / □ or less, ◯ 5 The case of exceeding 0Ω / □ was judged as x.

Solder heat resistance (normal)
The peelable substrate of the conductive adhesive sheet with a copper foil reinforcing plate produced under the same temporary pressure bonding conditions as the temporary pressure bonding property is peeled off, and a 25 μm copper foil is laminated on the surface, and 160 ° C., 4 MPa, 5 minutes. After heat-pressing with a vacuum press under the quick press conditions of No. 1, the film was after-cured in an oven at 160 ° C. for 60 minutes. This was stored in a normal state and then cut into 2.5 cm × 2.5 cm to prepare samples for evaluating solder heat resistance of Examples and Comparative Examples. The temperature of the solder bath was changed from 260 ° C. to 360 ° C. in increments of 10 ° C., and a test in which the evaluation sample was floated in the bath for 180 seconds was performed at each temperature. Foaming caused by the conductive adhesive compositions of Examples and Comparative Examples It was confirmed whether or not floating of the laminated layer occurred. The evaluation was carried out at each N3, and the highest temperature at which foaming or floating of the laminated layer did not occur in any test piece was defined as the solder heat resistance temperature value. The normal state refers to a condition of 23 ± 2 ° C./55±5% RH.

Solder heat resistance (moisture absorption)
An evaluation sample prepared in the same manner as the solder heat resistance characteristics (normal state) was absorbed for 96 hours in an environment of 40 ° C./90% RH, and then the temperature of the solder bath was changed from 240 ° C. to 360 ° C. in 10 ° C. increments. Except that the test was performed, the same test as the solder heat resistance property (normal state) was performed. Solder heat resistance that does not cause problems related to adhesion such as foaming or peeling between the conductive reinforcing plate and FPWB in the reflow soldering process if the solder heat resistance value under severe moisture absorption conditions is 260 ° C or higher as evaluation conditions If it is 280 degreeC or more, it can be evaluated that there exists further favorable solder heat resistance.

  Table 1 (Tables 1A and 1B) shows the amounts and physical properties of the components constituting the conductive adhesive compositions of Examples and Comparative Examples.

  The evaluation results of the conductive adhesive sheet and the like are shown in Table 2 (Table 2A and Table 2B). Note that the criteria for comprehensive evaluation are also shown in Table 2 (Table 2B).

Evaluation results The conductive adhesive composition layer using the conductive adhesive composition of the example has a solder heat resistance of 260 ° C. or higher under strict moisture absorption conditions even when it is fully cured under quick press conditions. It was.
On the other hand, in Comparative Example 1, since a conductive adhesive sheet was produced using NBR having no carboxyl group, good solder heat resistance could not be obtained. In Comparative Example 2, since the conductive adhesive sheet was prepared using an acrylic resin having a carboxyl group, the solder heat resistance was particularly low under moisture absorption conditions, and the possibility of causing problems in the reflow soldering process was high. . In Comparative Example 3, since the conductive adhesive sheet was prepared without adding the epoxy resin (B), the solder heat resistance was inferior in both normal and moisture absorption conditions. There was also a problem with resin flow characteristics. In Comparative Example 4, since the conductive adhesive sheet was prepared without adding the curing agent (D), the solder heat resistance under the moisture absorption condition was insufficient. In Comparative Example 5, a conductive adhesive sheet was prepared using NBR having a carboxyl group having a molecular weight of 5000 or less, and as a result, the resin flow amount increased and the adhesive strength and solder heat resistance were remarkably insufficient. In Comparative Example 6, since the conductive adhesive sheet was prepared using styrene butadiene rubber, the amount of resin flow increased, resulting in significantly insufficient adhesive strength and solder heat resistance. The other comparative examples had similar results.

  As described above, the conductive adhesive composition layer using the conductive adhesive composition of the present invention is formed by, for example, heat-pressing a conductive reinforcing plate and FPWB via a conductive adhesive composition layer to perform main curing adhesion. In this case, even if the quick press is performed, the reflow soldering process has a characteristic that does not cause problems related to adhesiveness such as foaming or peeling between the conductive reinforcing plate and the FPWB.

1 .... Copper foil reinforcing plate 2 .... Conductive adhesive composition layer 3 .... Polyimide film substrate 4 .... Copper plate 5 ....・ ・ ・ ・ ・ ・ Ground hole 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Polyimide film 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Conductive adhesive composition L ・ ・ ・ ・ ・ ・ ・ Projection distance

Claims (7)

NBR (A) having a carboxyl group;
Epoxy resin (B);
A curing agent (D);
A conductive material (E),
The NBR (A) having a carboxyl group has a weight average molecular weight (Mw) of 5,000 to 1,000,000,
A conductive adhesive composition having a nitrile monomer unit content of 5 to 45 mass% based on the total mass of the NBR (A) having a carboxyl group.   The conductive adhesive composition according to claim 1, wherein the acid value of the NBR (A) having a carboxyl group is 3 to 60 mgKOH / g.   The mass part ratio (A) / (B) of the NBR (A) having the carboxyl group and the epoxy resin (B) is 0.35 to 2.5, according to claim 1 or 2. The conductive adhesive composition as described.   The mass ratio (B) / (D) between the epoxy resin (B) and the curing agent (D) is 1 to 1000, according to any one of claims 1 to 3. Adhesive composition. A peelable substrate;
A conductive adhesive composition layer comprising the conductive adhesive composition according to any one of claims 1 to 4 is provided on one surface side of the peelable substrate. Sheet. The conductive material (E) is at least one selected from conductive metal powder, conductive metal composite powder, and carbon powder, and the volume ratio in the conductive adhesive composition is the conductive adhesive composition. 10 to 35% by volume based on the total volume (dry volume) of
The conductive adhesive sheet according to claim 5, wherein a surface resistance value of a cured product of the conductive adhesive composition layer is 5Ω / □ or less. A wiring board with signal wiring;
A conductive reinforcing plate provided on one side of the wiring board,
A wiring device, which is bonded via a cured product of a conductive adhesive composition layer formed from the conductive adhesive composition according to any one of claims 1 to 4.

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