conductive adhesive film

Abstract

This conductive adhesive film includes a support body and a conductive layer; the conductive layer contains a thermosetting resin composition, and the thermosetting resin composition contains (a) an epoxy resin, (b) a polymer resin that has a glass transition temperature of 25°C or less or that is liquid at 25°C, (c) a curing agent, and (d) a conductive filler; and component (d) is at least one item selected from metal particles selected from silver, copper and nickel, and metal coated particles coated with a metal selected from silver, copper and nickel.

Description

Technical Field

[0001] The present invention relates to a conductive adhesive film. Further, it relates to an electromagnetic shield, an electronic device, and a wiring board using the conductive adhesive film.

Background Art

[0002] With the recent miniaturization of electronic devices, flexible printed wiring boards (FPCs) are frequently used, and conductive adhesive films may be used for the high functionality of electronic devices equipped with FPCs (Patent Document 1). For example, a conductive adhesive film may be used for the purpose of, among other things, adhering a reinforcing member of a flexible printed wiring board involving component mounting such as a camera module of a mobile phone, and simultaneously imparting an electromagnetic shielding function to the mounting portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conductive adhesive film, in order to exhibit sufficient conductivity, it is required to fill a conductive filler with a certain amount or more. However, when the blending amount of the conductive filler is increased, there is a problem that the adhesiveness deteriorates. <​​​​​​​​​As a result of diligent research to achieve the above objective, the inventors of the present invention have discovered that by including a specific polymer resin in the thermosetting resin composition constituting conductivity, it is possible to provide a conductive adhesive film that exhibits excellent conductivity and good adhesive performance, thereby completing the present invention.

[0007] In other words, the present invention includes the following: [1] A conductive adhesive film comprising a support and a conductive layer, The conductive layer comprises a thermosetting resin composition. The thermosetting resin composition contains (a) an epoxy resin, (b) a polymer resin having a glass transition temperature of 25°C or lower or being liquid at 25°C, (c) a curing agent, and (d) a conductive filler. (d) A conductive adhesive film in which component is at least one selected from metal particles selected from silver, copper, and nickel, and metal-coated particles coated with a metal selected from silver, copper, and nickel. [2] The conductive adhesive film according to [1], wherein component (a) is an epoxy resin having an aromatic structure. [3] The conductive adhesive film according to [1] or [2], wherein component (b) has one or more structures selected from the group consisting of a polyalkylene structure, a polyalkylene oxy structure, a polybutadiene structure, a polyisoprene structure, a polyisobutylene structure, a polycarbonate structure, a poly(meth)acrylate structure, and a polysiloxane structure. [4] The conductive adhesive film according to any one of [1] to [3], wherein the content of component (b) is 2% by mass or more and 13% by mass or less, when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. [5] A conductive adhesive film according to any one of [1] to [4], wherein component (d) is a metal particle selected from silver, copper, and nickel. [6] The conductive adhesive film according to any one of [1] to [5], wherein the content of component (d) is 40% by mass or more when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. [7] A conductive adhesive film according to any one of [1] to [6], wherein the mixing ratio (mass ratio) of component (d) and component (b) is ((d) component / (b) component), which is 5 or more and 45 or less. [8] An electromagnetic shield comprising a cured product of a thermosetting resin composition of a conductive adhesive film as described in any of [1] to [7]. [9] An electronic device comprising a cured product of a thermosetting resin composition of a conductive adhesive film as described in any of [1] to [7].

[10] A wiring board comprising a cured product of a thermosetting resin composition layer of a conductive adhesive film as described in any of [1] to [7].

[11] A flexible circuit board, as described in

[10] . [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a conductive adhesive film that has excellent conductivity and good adhesive performance, as well as an electromagnetic shield, an electronic device, and a wiring board using the conductive adhesive film. [Modes for carrying out the invention]

[0009] The conductive adhesive film of the present invention, electromagnetic shielding, electronic devices, and wiring boards using the conductive adhesive film will be described in detail below.

[0010] [Conductive adhesive film] The conductive adhesive film of the present invention comprises a support and a conductive layer. In one embodiment, the conductive adhesive film comprises a support and a conductive layer bonded to the support. The conductive layer comprises a thermosetting resin composition, and usually comprises only the thermosetting resin composition. The thermosetting resin composition contains (a) an epoxy resin, (b) a polymer resin having a glass transition temperature of 25°C or less or being liquid at 25°C, (c) a curing agent, and (d) a conductive filler. Each layer constituting the conductive adhesive film will be described in detail below.

[0011] <Support> The conductive adhesive film of the present invention includes a support. Examples of the support include a film made of a plastic material, a metal foil, and a release paper, with a film made of a plastic material and a metal foil being preferred.

[0012] When using a film made of plastic material as a support, examples of plastic materials include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketones, and polyimides. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0013] When using metal foil as a support, examples of metal foil include copper foil and aluminum foil, with copper foil being preferred. As for copper foil, foil made of single-metal copper may be used, or foil made of an alloy of copper with another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used. Furthermore, a metal foil made by laminating multiple metal foils may also be used.

[0014] The support may have a matte finish or corona treatment applied to the surface that is bonded to the conductive layer.

[0015] Further, as the support, a support with a release layer having a release layer on the surface that joins with the conductive layer may be used. Examples of the release agent used for the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. The support with a release layer may be a commercially available product. For example, "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation, "Lumirror T6AM" manufactured by Toray Industries, etc., which are PET films having a release layer mainly composed of an alkyd resin-based release agent, can be mentioned.

[0016] The thickness of the support is not particularly limited, but a range of 5 μm to 75 μm is preferable, and a range of 10 μm to 60 μm is more preferable. When using a support with a release layer, it is preferable that the total thickness of the support with a release layer is within the above range.

[0017] <Conductive layer> The conductive adhesive film of the present invention includes a conductive layer, and the conductive layer is composed of a thermosetting resin composition. The thermosetting resin composition contains (a) an epoxy resin, (b) a polymer resin having a glass transition temperature of 25°C or lower or being liquid at 25°C, (c) a curing agent, and (d) a conductive filler. The thermosetting resin composition may further contain (e) a curing accelerator and (f) other additives as necessary.

[0018] -(a) Epoxy resin- The thermosetting resin composition contains, as component (a), (a) an epoxy resin. From the viewpoint of remarkably obtaining the effects of the present invention, it is preferable that the component (a) contained in the thermosetting resin composition includes an epoxy resin having an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and includes polycyclic aromatics and aromatic heterocycles. Examples of the (a) epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, biscyclohenol type epoxy resin, glycidylamine type epoxy resin having an aromatic structure, glycidyl ester type epoxy resin having an aromatic structure, cresol novolak type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin having an aromatic structure, epoxy resin having a butadiene structure having an aromatic structure, alicyclic epoxy resin having an aromatic structure, heterocyclic epoxy resin, spiro ring-containing epoxy resin having an aromatic structure, cyclohexanedimethanol type epoxy resin having an aromatic structure, naphthylene ether type epoxy resin, trimethylol type epoxy resin having an aromatic structure, tetraphenyl ethane type epoxy resin having an aromatic structure, and the like. The (a) epoxy resin may be used alone or in combination of two or more. Among them, it is preferable that the component (a) is at least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl type epoxy resin.

[0019] (a) The epoxy resin preferably contains an epoxy resin having two or more epoxy groups per molecule. When the non-volatile components of the epoxy resin are considered to be 100% by mass, it is preferable that at least 50% by mass or more is an epoxy resin having two or more epoxy groups per molecule. From the viewpoint of film formation, the epoxy resin preferably contains an epoxy resin that is solid at 20°C. In particular, it is preferable to contain an epoxy resin that has two or more epoxy groups per molecule and is liquid at 20°C (hereinafter referred to as "liquid epoxy resin") and an epoxy resin that has three or more epoxy groups per molecule and is solid at 20°C (hereinafter referred to as "solid epoxy resin"). By using both liquid epoxy resin and solid epoxy resin as the epoxy resin, a thermosetting resin composition with excellent flexibility can be obtained. In addition, the tensile strength of the cured product of the thermosetting resin composition is also improved.

[0020] Preferred liquid epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin having an aromatic structure, glycidylamine type epoxy resin having an aromatic structure, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton having an aromatic structure, cyclohexanedimethanol type epoxy resin having an aromatic structure, and epoxy resin having a butadiene structure having an aromatic structure. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, and naphthalene type epoxy resin are more preferred, and bisphenol A type epoxy resin and bisphenol F type epoxy resin are even more preferred. Specific examples of liquid epoxy resins include "HP4032," "HP4032D," and "HP4032SS" (naphthalene-type epoxy resins) from DIC Corporation, "828US," "jER828EL" (bisphenol A-type epoxy resin), "jER807" (bisphenol F-type epoxy resin), "jER152" (phenol novolac-type epoxy resin), "630," and "630LSD" (glycidylamine-type epoxy resins) from Mitsubishi Chemical Corporation, "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) from Nippon Steel Chemical & Material Corporation, "EX-721" (glycidyl ester-type epoxy resin) from Nagase ChemteX Corporation, "Celoxide 2021P" (alicyclic epoxy resin with an ester skeleton) from Daicel Corporation, and "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane) from Nippon Steel Chemical & Material Corporation. These may be used individually or in combination of two or more types.

[0021] As solid epoxy resins, naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins having an aromatic structure, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, and tetraphenylethane-type epoxy resins are preferred, naphthalene-type tetrafunctional epoxy resins, naphthol-type epoxy resins, and biphenyl-type epoxy resins and naphthylene ether-type epoxy resins are more preferred, and naphthalene-type tetrafunctional epoxy resins and naphthylene ether-type epoxy resins are even more preferred.Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene-type epoxy resin), "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin), "N-690" (cresol novolac-type epoxy resin), "N-695" (cresol novolac-type epoxy resin), "HP-7200" (dicyclopentadiene-type epoxy resin), "HP-7200HH", "HP-7200H", "EXA7311", "EXA7311-G3", "EXA7311-G4", "EXA7311-G4S", "HP6000" (naphthylene ether-type epoxy resin), and Nippon Kayaku's "EPPN-502H" (trisphenol-type epoxy resin), "NC7000L" (naphthol novolac-type epoxy resin), "NC3000H", "NC3000", Examples include "NC3000L" and "NC3100" (biphenyl-type epoxy resins), "ESN475V" (naphthol-type epoxy resin) and "ESN485" (naphthol novolac-type epoxy resin) from Nippon Steel Chemical & Material, "YX4000H" and "YL6121" (biphenyl-type epoxy resins), "YX4000HK" (bixylenol-type epoxy resin) and "YX8800" (anthracene-type epoxy resin) from Mitsubishi Chemical, "PG-100" and "CG-500" from Osaka Gas Chemical, "YL7800" (fluorene-type epoxy resin) from Mitsubishi Chemical, "jER1010" (solid bisphenol A-type epoxy resin), "jER1031S" (tetraphenylethane-type epoxy resin) and "YL7760" (bisphenol AF-type epoxy resin) from Mitsubishi Chemical.

[0022] When using both liquid epoxy resin and solid epoxy resin, the ratio of liquid epoxy resin to solid epoxy resin (by mass) is preferably in the range of 1:0.1 to 1:20. By setting the ratio of liquid epoxy resin to solid epoxy resin within this range, the following effects can be obtained: i) appropriate tackiness is provided when used in the form of a conductive adhesive film, ii) sufficient flexibility is obtained when used in the form of a conductive adhesive film, improving handling, and iii) a cured product with sufficient breaking strength can be obtained. From the viewpoint of the above effects i) to iii), the ratio of liquid epoxy resin to solid epoxy resin (by mass) is more preferably in the range of 1:0.3 to 1:10, and even more preferably in the range of 1:0.6 to 1:9.

[0023] The content of (a) epoxy resin in the thermosetting resin composition is preferably 4% by mass or more, more preferably 5% by mass or more, and even more preferably 6% by mass or more, from the viewpoint of obtaining a conductive layer that exhibits good mechanical strength. The upper limit of the epoxy resin content is not particularly limited as long as the effects of the present invention are achieved, but is preferably 50% by mass or less, and more preferably 40% by mass or less.

[0024] In this invention, unless otherwise specified, the content of each component in the thermosetting resin composition is the value when the non-volatile component in the thermosetting resin composition is taken as 100% by mass.

[0025] (a) The epoxy equivalent of the epoxy resin is preferably 50 to 5000, more preferably 50 to 3000, even more preferably 80 to 2000, and even more preferably 110 to 1000. The epoxy equivalent can be measured according to JIS K7236 and is the mass of the resin containing one equivalent of epoxy groups.

[0026] (a) The weight-average molecular weight of the epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. Here, the weight-average molecular weight of the epoxy resin is the weight-average molecular weight on a polystyrene basis measured by gel permeation chromatography (GPC).

[0027] -(b) Polymer resins with a glass transition temperature of 25°C or lower, or that are liquid at 25°C- The thermosetting resin composition includes, as component (b), a polymer resin having a glass transition temperature of 25°C or less or being liquid at 25°C. Component (b) may consist solely of a polymer resin having a glass transition temperature of 25°C or less, solely of a polymer resin being liquid at 25°C, or a combination of a polymer resin having a glass transition temperature of 25°C or less and a polymer resin being liquid at 25°C. By including a polymer resin such as component (b), good adhesion of the conductive layer can be achieved even when a conductive filler is included to an extent sufficient to exhibit sufficient conductivity.

[0028] (b) The glass transition temperature (Tg) of the polymer resin having a glass transition temperature of 25°C or less is preferably 20°C or less, more preferably 15°C or less. The lower limit of the glass transition temperature of component (b) is not particularly limited, but can usually be -15°C or higher.

[0029] Component (b) preferably has a functional group that can react with component (a). That is, component (b) is preferably a resin having a functional group and having a glass transition temperature of 25°C or lower, and preferably one or more resins selected from resins having a functional group that are liquid at 25°C. In one preferred embodiment, the functional group of component (b) is one or more functional groups selected from the group consisting of a hydroxyl group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group. Among these, the functional group is preferably a hydroxyl group, an acid anhydride group, an epoxy group, or a phenolic hydroxyl group, and more preferably a hydroxyl group, an acid anhydride group, or an epoxy group. However, if the functional group includes an epoxy group, it is preferable that component (b) does not have an aromatic structure.

[0030] (b) Component (b) preferably has one or more structures selected from the group consisting of polyalkylene structures, polyalkylene oxy structures, polybutadiene structures, polyisoprene structures, polyisobutylene structures, polycarbonate structures, poly(meth)acrylate structures, and polysiloxane structures, from the viewpoint of obtaining a conductive layer with excellent adhesive properties, and more preferably has one or more structures selected from the group consisting of polybutadiene structures and poly(meth)acrylate structures. Note that "(meth)acrylate" refers to methacrylate and acrylate.

[0031] The polyalkylene structure is preferably a polyalkylene structure having 2 to 15 carbon atoms, more preferably a polyalkylene structure having 3 to 10 carbon atoms, and more preferably a polyalkylene structure having 5 to 6 carbon atoms.

[0032] The polyalkylene oxy structure is preferably a polyalkylene oxy structure having 2 to 15 carbon atoms, more preferably a polyalkylene oxy structure having 3 to 10 carbon atoms, and more preferably a polyalkylene oxy structure having 5 to 6 carbon atoms.

[0033] (b) A preferred embodiment of component is a butadiene resin. The butadiene resin is preferably a butadiene resin that is liquid at 25°C or has a glass transition temperature of 25°C or lower, more preferably one or more resins selected from the group consisting of hydrogenated polybutadiene skeleton-containing resins (e.g., hydrogenated polybutadiene skeleton-containing epoxy resins), hydroxyl group-containing butadiene resins, phenolic hydroxyl group-containing butadiene resins (resins having a polybutadiene structure and phenolic hydroxyl groups), carboxyl group-containing butadiene resins, acid anhydride group-containing butadiene resins, epoxy group-containing butadiene resins, isocyanate group-containing butadiene resins and urethane group-containing butadiene resins, and even more preferably a phenolic hydroxyl group-containing butadiene resin. Here, "butadiene resin" means a resin containing a polybutadiene structure, and in these resins, the polybutadiene structure may be included in the main chain or in the side chains. The polybutadiene structure may be partially or entirely hydrogenated. Here, "hydrogenated polybutadiene skeleton-containing resin" refers to a resin in which at least a portion of the polybutadiene skeleton is hydrogenated, and it is not necessarily required that the polybutadiene skeleton be completely hydrogenated.

[0034] The number-average molecular weight (Mn) of the butadiene resin is preferably 1,000 to 100,000, more preferably 5,000 to 50,000, more preferably 7,500 to 30,000, and even more preferably 10,000 to 15,000. Here, the number-average molecular weight (Mn) of the resin is the polystyrene-based number-average molecular weight measured using GPC (gel permeation chromatography).

[0035] When the butadiene resin contains functional groups, the functional group equivalent is preferably 100 to 10,000, more preferably 200 to 5,000. The functional group equivalent refers to the number of grams of resin containing 1 gram equivalent of functional groups. For example, the epoxy group equivalent can be measured according to JIS K7236. The hydroxyl group equivalent can be calculated by dividing the molecular weight of KOH by the hydroxyl value measured according to JIS K1557-1.

[0036] Specific examples of butadiene resins include Clay Valley's "Ricon 657" (epoxy group-containing polybutadiene), "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", and "Ricon 184MA6" (acid anhydride group-containing polybutadiene); Nippon Soda's "JP-100" and "JP-200" (epoxidized polybutadiene), "GQ-1000" (hydroxyl group and carboxyl group-introduced polybutadiene), "G-1000", "G-2000", and "G-3000" (hydroxyl group polybutadiene at both ends), "GI-1000", "GI-2000", and "GI-3000" (hydroxyl group hydrogenated polybutadiene at both ends); and Daicel. Examples include the company's "PB3600" and "PB4700" (polybutadiene skeleton epoxy resins), "Epofriend A1005", "Epofriend A1010", and "Epofriend A1020" (epoxidized styrene, butadiene, and styrene block copolymers), and Nagase ChemteX's "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin) and "R-45EPT" (polybutadiene skeleton epoxy resin).

[0037] Another preferred embodiment of component (b) is a resin having an imide structure. Examples of such component (b) include linear polyimides (polyimides described in Japanese Patent Publication No. 2006-37083 and International Publication No. 2008 / 153208) derived from hydroxyl-terminated polybutadiene, diisocyanate compounds, and tetrabasic acid anhydrides. The butadiene structure content of the polyimide resin is preferably 60% to 95% by mass, more preferably 75% to 85% by mass. Details of the polyimide resin can be found in Japanese Patent Publication No. 2006-37083 and International Publication No. 2008 / 153208, which are incorporated herein by reference.

[0038] (b) A more preferred embodiment of component is a polyimide resin having a polybutadiene structure, a urethane structure, and an imide structure within the molecule, wherein the polyimide resin preferably has a phenol structure at the molecular terminals.

[0039] The number-average molecular weight (Mn) of the polyimide resin is preferably 1,000 to 100,000, more preferably 10,000 to 15,000. Here, the number-average molecular weight (Mn) of the resin is the number-average molecular weight on a polystyrene basis, measured using GPC (gel permeation chromatography).

[0040] The acid value of the polyimide resin is preferably 1 KOH / g to 30 KOH / g, more preferably 10 KOH / g to 20 KOH / g.

[0041] The butadiene structure content of the polyimide resin is preferably 60% to 95% by mass, more preferably 75% to 85% by mass.

[0042] (b) Another preferred embodiment of component is an acrylic resin. The acrylic resin is preferably an acrylic resin having a glass transition temperature (Tg) of 25°C or lower, and more preferably one or more resins selected from the group consisting of hydroxyl group-containing acrylic resins, phenolic hydroxyl group-containing acrylic resins, carboxyl group-containing acrylic resins, acid anhydride group-containing acrylic resins, epoxy group-containing acrylic resins, isocyanate group-containing acrylic resins, and urethane group-containing acrylic resins. Here, "acrylic resin" means a resin containing a (meth)acrylate structure, and in these resins, the (meth)acrylate structure may be included in the main chain or in the side chain.

[0043] The number-average molecular weight (Mn) of the acrylic resin is preferably 10,000 to 1,000,000, more preferably 30,000 to 900,000. Here, the number-average molecular weight (Mn) of the resin is the polystyrene-based number-average molecular weight measured using GPC (gel permeation chromatography).

[0044] When the acrylic resin has functional groups, the functional group equivalent is preferably 1,000 to 50,000, more preferably 2,500 to 30,000.

[0045] Specific examples of acrylic resins include Nagase ChemteX's Teisan Resin "SG-70L", "SG-708-6", "WS-023", "SG-700AS", "SG-280TEA" (carboxyl group-containing acrylic ester copolymer resin, acid value 5-34 mgKOH / g, weight-average molecular weight 400,000-900,000, Tg -30-5℃), "SG-80H", "SG-80H-3", "SG-P3" (epoxy group-containing acrylic ester copolymer resin, epoxy equivalent 4761-14285 g / eq, weight-average molecular weight 350,000-85 Examples include "SG-600TEA" and "SG-790" (hydroxyl group-containing acrylic ester copolymer resin, hydroxyl value 20-40 mgKOH / g, weight-average molecular weight 500,000-1,200,000, Tg -37--32℃), "ME-2000" and "W-116.3" (carboxyl group-containing acrylic ester copolymer resin), "W-197C" (hydroxyl group-containing acrylic ester copolymer resin), "KG-25" and "KG-3000" (epoxy group-containing acrylic ester copolymer resin) from Negami Kogyo Co., Ltd.

[0046] Furthermore, a preferred embodiment of component (b) is a carbonate resin. Preferably, the carbonate resin has a glass transition temperature of 25°C or lower, and one or more resins selected from the group consisting of hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, epoxy group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins are preferred. Here, "carbonate resin" refers to a resin containing a carbonate structure, and in these resins, the carbonate structure may be included in the main chain or in the side chains.

[0047] The number-average molecular weight (Mn) and functional group equivalents of the carbonate resin are the same as those of the butadiene resin, and the preferred ranges are also the same.

[0048] Specific examples of carbonate resins include "T6002" and "T6001" (polycarbonate diols) from Asahi Kasei Chemicals, and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) from Kuraray Co., Ltd.

[0049] Linear polyimides (PCT / JP2016 / 053609) made from hydroxyl-terminated polycarbonates, diisocyanate compounds, and tetrabasic acid anhydrides can also be used. The content of the carbonate structure in the polyimide resin is preferably 60% to 95% by mass, more preferably 75% to 85% by mass. Details of the polyimide resin can be found in the description of PCT / JP2016 / 053609, which is incorporated herein by reference.

[0050] Furthermore, a preferred embodiment of component (b) is a polysiloxane resin, an alkylene resin, an alkylene oxy resin, an isoprene resin, or an isobutylene resin.

[0051] Polysiloxane resin is a resin containing a polysiloxane structure. Specific examples of polysiloxane resins include Shin-Etsu Silicone's "SMP-2006," "SMP-2003PGMEA," "SMP-5005PGMEA," amine-terminated polysiloxanes, and linear polyimides made from tetrabasic anhydrides (International Publication No. 2010 / 053185). Alkylene resins are resins that contain a polyalkylene structure. Specific examples of alkylene resins include "PTXG-1000" and "PTXG-1800" from Asahi Kasei Fibers, and "YX-7180" from Mitsubishi Chemical Corporation (a resin containing an alkylene structure with ether bonds). Alkylene oxy resins are resins containing a polyalkylene oxy structure. Specific examples of alkylene oxy resins include "EXA-4850-150," "EXA-4816," and "EXA-4822" from DIC Corporation; "EP-4000," "EP-4003," "EP-4010," and "EP-4011" from ADEKA Corporation; "BEO-60E" and "BPO-20E" from Shin Nippon Rika Co., Ltd.; and "YL7175" and "YL7410" from Mitsubishi Chemical Corporation. Isoprene resin is a resin containing a polyisoprene structure. Specific examples of isoprene resin include "KL-610" and "KL613" manufactured by Kuraray Co., Ltd. Isobutylene resin is a resin containing a polyisobutylene structure. Specific examples of isobutylene resin include Kaneka Corporation's "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer) and "SIBSTAR-042D" (styrene-isobutylene diblock copolymer).

[0052] Further preferred embodiments of component (b) include acrylic rubber particles, polyamide microparticles, and silicone particles. Specific examples of acrylic rubber particles include resin microparticles obtained by chemically crosslinking a rubber-elastic resin such as acrylonitrile butadiene rubber, butadiene rubber, or acrylic rubber, making them insoluble and infusible in organic solvents. Examples include XER-91 (manufactured by Nippon Synthetic Rubber Co., Ltd.), Staphyloid AC3355, AC3816, AC3832, AC4030, AC3364, and IM101 (all manufactured by Gantz Chemical Co., Ltd.), and Paraloid EXL2655 and EXL2602 (both manufactured by Kureha Chemical Industry Co., Ltd.). Specific examples of polyamide microparticles include aliphatic polyamides such as nylon, and any flexible backbone such as polyamide-imides. Examples include VESTOSINT 2070 (manufactured by Daicel-Hürss Corporation) and SP500 (manufactured by Toray Industries, Inc.).

[0053] From the viewpoint of improving the tensile strength of the conductive layer, it is preferable that component (b) has high compatibility with components other than component (b). That is, it is preferable that component (b) is dispersed in the conductive layer. Furthermore, component (b) may be dispersed in the conductive layer by forming domains. The average maximum diameter of the domains is preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less, or not dispersed (average maximum diameter of domains is 0 μm).

[0054] The average maximum diameter of a domain can be measured as follows: A conductive adhesive film is heat-cured at 100°C for 30 minutes, then at 170°C for 30 minutes. A cross-sectional observation is performed on the conductive layer using a FIB-SEM combined system (SMI3050SE, manufactured by SII Nanotechnology). Specifically, a cross-section perpendicular to the surface of the conductive adhesive film is cut using FIB (focused ion beam), and a cross-sectional SEM image (observation width 60 μm, observation magnification 2,000x) is obtained. Cross-sectional SEM images from five randomly selected locations are observed, and the maximum diameter of 20 domains (4 points / each cross-section) is measured. The average value of these measurements is taken as the average maximum diameter. The maximum diameter refers to the largest diameter among the domains.

[0055] (b) The content of component is not particularly limited, but when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass, it is preferably 13% by mass or less, more preferably 12% by mass or less, and even more preferably 11% by mass or less. The lower limit is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more.

[0056] -(c) Hardener- The thermosetting resin composition contains a curing agent as component (c). The curing agent (c) is not particularly limited as long as it has the function of curing epoxy resin, and examples include phenolic curing agents, naphthol curing agents, active ester curing agents, benzoxazine curing agents, cyanate ester curing agents, and carbodiimide curing agents. The curing agent may be used alone or in combination of two or more. Component (c) is preferably one or more selected from phenolic curing agents, naphthol curing agents, active ester curing agents, and cyanate ester curing agents, and is preferably one or more selected from phenolic curing agents, naphthol curing agents, and active ester curing agents.

[0057] From the viewpoint of heat resistance and water resistance, phenolic curing agents having a novolac structure or naphthol curing agents having a novolac structure are preferred as phenolic curing agents and naphthol curing agents having a novolac structure. Furthermore, from the viewpoint of adhesion to the wiring layer, nitrogen-containing phenolic curing agents are preferred, and triazine skeleton-containing phenolic curing agents are more preferred. Among these, triazine skeleton-containing phenol novolac curing agents are preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion to the wiring layer.

[0058] Specific examples of phenol-based and naphthol-based curing agents include, for example, "MEH-7700," "MEH-7810," and "MEH-7851" from Meiwa Kasei Co., Ltd., "NHN," "CBN," and "GPH" from Nippon Kayaku Co., Ltd., "SN170," "SN180," "SN190," "SN475," "SN485," "SN495V," "SN375," and "SN395" from Nippon Steel Chemical & Material Co., Ltd., and "TD-2090," "LA-7052," "LA-7054," "LA-1356," "LA-3018-50P," "EXB-9500," and "HPC-9500" from DIC Corporation.

[0059] (c) As component (c), an active ester-based curing agent is also preferred from the viewpoint of obtaining a conductive layer with excellent adhesion. There are no particular restrictions on the active ester-based curing agent, but generally compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are preferred. The active ester-based curing agent is preferably obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. Particularly from the viewpoint of improving heat resistance, an active ester-based curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester-based curing agent obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolac. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by the condensation of two phenol molecules with one dicyclopentadiene molecule.

[0060] Specifically, active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated phenol novolac, and active ester compounds containing a benzoylated phenol novolac are preferred, with active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure being more preferred. "Dicyclopentadiene-type diphenol structure" refers to a divalent structure consisting of phenylene-dicyclopentylene-phenylene.

[0061] Commercially available active ester curing agents include "EXB9451," "EXB9460," "EXB9460S," "HPC-8000-65T," "HPC-8000H-65TM," and "EXB-8000L-65TM" (manufactured by DIC Corporation) as active ester compounds containing a dicyclopentadiene-type diphenol structure; "EXB9416-70BK," "HPC-8150-60T," "HPC-8150-62T," and "EXB-8150-65T" (manufactured by DIC Corporation) as active ester compounds containing a naphthalene structure; "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing an acetylated phenol novolac; and "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) as active ester curing agents containing a benzoylated phenol novolac.

[0062] Specific examples of benzoxazine-based curing agents include "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "Pd" and "Fa" manufactured by Shikoku Chemicals Co., Ltd.

[0063] Examples of cyanate ester curing agents include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl) thioether, and bis(4-cyanatephenyl) ether; polyfunctional cyanate resins derived from phenol novolacs and cresol novolacs; and prepolymers in which these cyanate resins are partially triazined. Specific examples of cyanate ester-based curing agents include "PT30" and "PT60" (both phenol novolac type polyfunctional cyanate ester resins) manufactured by Lonza Japan, "BA230", and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate is triazined and trimerized).

[0064] Specific examples of carbodiimide-based curing agents include "V-03" and "V-07" manufactured by Nisshinbo Chemical Co., Ltd.

[0065] The ratio of (a) epoxy resin to (c) curing agent is the ratio of [total number of epoxy groups in epoxy resin] to [total number of reactive groups in curing agent], preferably in the range of 1:0.01 to 1:2, more preferably in the range of 1:0.015 to 1:1.5, and even more preferably in the range of 1:0.02 to 1:1. Here, the reactive groups of the curing agent are activated hydroxyl groups, activated ester groups, etc., and vary depending on the type of curing agent. The total number of epoxy groups in the epoxy resin is the sum of the values ​​obtained by dividing the solid content mass of each epoxy resin by the epoxy equivalent for all epoxy resins, and the total number of reactive groups in the curing agent is the sum of the values ​​obtained by dividing the solid content mass of each curing agent by the reactive group equivalent for all curing agents. By setting the ratio of epoxy resin to curing agent within this range, the heat resistance of the cured product of the thermosetting resin composition is further improved.

[0066] In one embodiment of the thermosetting resin composition, it is preferable that the composition contains (a) a mixture of liquid epoxy resin and solid epoxy resin as the epoxy resin (the mass ratio of liquid epoxy resin to solid epoxy resin is preferably 1:0.1 to 1:20, more preferably 1:0.3 to 1:10, and even more preferably 1:0.6 to 1:9), and (c) one or more curing agents selected from the group consisting of phenolic curing agents, naphthol curing agents, active ester curing agents, and cyanate ester curing agents.

[0067] (c) The content of the curing agent is not particularly limited, but when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass, it is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. There is no particular lower limit, but 2% by mass or more is preferred.

[0068] -(d) Conductive filler - The thermosetting resin composition includes a conductive filler as component (d). The conductive filler (d) is at least one selected from metal particles selected from silver, copper, and nickel, and metal-coated particles coated with a metal selected from silver, copper, and nickel. Examples of metal particles include silver particles, copper particles, and nickel particles. Examples of metal-coated particles include metal-coated metal particles in which metal particles are coated with metal, and metal-coated resin particles in which resin particles such as polyamide and polybenzoguanamine are coated with metal. Examples of metal-coated particles include silver-coated particles such as silver-coated metal particles and silver-coated resin particles; copper-coated particles such as copper-coated metal particles and copper-coated resin particles; nickel-coated particles such as nickel-coated metal particles and nickel-coated resin particles; and so on. Among these, from the viewpoint of cost, metal particles selected from copper and nickel, and metal-coated particles selected from copper and nickel are preferred as component (d), and nickel particles or nickel-coated particles are particularly preferred. Furthermore, as component (d), from the viewpoint of resistance, metal particles selected from silver and copper, and metal-coated particles selected from silver and copper are preferred, and silver particles or silver-coated particles are particularly preferred.

[0069] The conductive filler is preferably in the form of flakes (scale-like) or filaments (dendritic). The conductive filler may be used alone or in combination of two or more types.

[0070] The average particle size of the conductive filler is preferably 50 μm or less, more preferably 35 μm or less, even more preferably 20 μm or less, and even more preferably 10 μm or less, from the viewpoint of film-forming properties and conductivity. The lower limit of the average particle size is not particularly limited, but is preferably 0.001 μm or more, more preferably 0.005 μm or more, and even more preferably 0.01 μm or more.

[0071] The average particle size of conductive fillers can be measured by the laser diffraction-scattering method based on Mie scattering theory. Specifically, a volume-based particle size distribution of the conductive filler is created using a laser diffraction-scattering particle size distribution analyzer, and the median diameter is used as the average particle size for measurement. A sample of conductive filler dispersed in water using ultrasound is preferably used for measurement. A laser diffraction-scattering particle size distribution analyzer such as the "LA-500" manufactured by Horiba, Ltd. can be used.

[0072] Commercially available conductive fillers can be used. For example, commercially available conductive fillers include "EA0101" from Metallow, Inc., which uses Ag particles with an average particle size of 6.8 μm and a specific surface area of ​​0.28 m². 2 / g; Silver-coated copper particles, "AACU-3001" manufactured by Metallow Co., Ltd., average particle size 5.8 μm, specific surface area 0.61 m² 2 / g; Nickel particles are "NI-613" manufactured by Shoei Chemical Industry Co., Ltd., with an average particle size of 1.0 μm and a specific surface area of ​​1.0 m². 2 / g; Nickel particles: Nikko Rica Co., Ltd. "Type255", "HCA-1"; Copper-nickel particles: Nippon Atomize Processing Co., Ltd. "SF-CuNi", average particle size 8.5 μm, specific surface area 0.2 m² 2 Examples of copper particles include "Cu-HWQ" manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.

[0073] From the viewpoint of improving moisture resistance and dispersibility, it is preferable that the conductive filler is treated with one or more surface treatment agents such as silane-based surface treatment agents, including aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, alkoxysilane compounds, organosilazane compounds, and titanate-based coupling agents; and polyester-based dispersants.

[0074] Examples of commercially available silane-based surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane), "KBM803" (3-mercaptopropyltrimethoxysilane), "KBE903" (3-aminopropyltriethoxysilane), "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), "SZ-31" (hexamethyldisilazane), "KBM103" (phenyltrimethoxysilane), and "KBM-4803" (long-chain epoxy-type silane coupling agent) from Shin-Etsu Chemical Co., Ltd.

[0075] Examples of commercially available polyester dispersants include Solspers 11200, 12000, 13240, 13940, 17000, 18000, 20000, 24000, 26000, and 28000 from Lubrizol Japan, and Azisper PB817, Azisper PB822, Azisper PB821, Azisper PB880, Azisper PB882, and Azisper PB881 from Ajinomoto Fine Techno Co., Ltd. Alternatively, polyester dispersants synthesized using commercially available materials may also be used.

[0076] From the viewpoint of obtaining a conductive layer with low resistance, the content of the conductive filler is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, when the non-volatile components in the thermosetting resin composition are considered to be 100% by mass. From the viewpoint of adhesion of the conductive layer, the upper limit of the content of the conductive filler in the thermosetting resin composition is preferably 98% by mass or less, and more preferably 95% by mass or less.

[0077] The mixing ratio (mass ratio) of component (d) and component (b) is preferably 5 or more, more preferably 6 or more, even more preferably 7 or more, preferably 45 or less, more preferably 35 or less, and even more preferably 25 or less, from the viewpoint of simultaneously achieving adhesion and conductivity.

[0078] -(e) Curing accelerator- The thermosetting resin composition may contain (e) a curing accelerator as an optional component. Examples of curing accelerators include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators are preferred, and amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators are more preferred. The curing accelerator may be used alone or in combination of two or more types.

[0079] Examples of phosphorus-based curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate, with triphenylphosphine and tetrabutylphosphonium decanoate being preferred.

[0080] Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred.

[0081] Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-Cyanoethyl-2-methylimidazole, 1-Cyanoethyl-2-undecylimidazole, 1-Cyanoethyl-2-ethyl-4-methylimidazole, 1-Cyanoethyl-2-phenylimidazole, 1-Cyanoethyl-2-undecylimidazolium trimellitate, 1-Cyanoethyl-2-phenylimidazolium trimellitate, 2,4-Diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2, 4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanurate adduct, 2-phenylimidazole isocyanurate adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-F Examples include imidazole compounds such as phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins, with 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole being preferred.

[0082] Commercially available imidazole-based curing accelerators may be used, such as Mitsubishi Chemical's "P200-H50".

[0083] Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]deca-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]deca-5-ene. Examples include ro[4.4.0]deca-5-ene, 1-methyl biguanide, 1-ethyl biguanide, 1-n-butyl biguanide, 1-n-octadecyl biguanide, 1,1-dimethyl biguanide, 1,1-diethyl biguanide, 1-cyclohexyl biguanide, 1-allyl biguanide, 1-phenyl biguanide, 1-(o-tolyl) biguanide, and the like, with dicyandiamide and 1,5,7-triazabicyclo[4.4.0]deca-5-ene being preferred.

[0084] Examples of metal-based hardening accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0085] The content of the curing accelerator in the thermosetting resin composition is not particularly limited, but it is preferably 0.01% to 3% by mass, when the total amount of nonvolatile components of the epoxy resin and curing agent is 100% by mass.

[0086] -(f) Other additives- The thermosetting resin composition may further contain other additives as needed, such as polymer resins other than component (b), thickeners, defoamers, leveling agents, adhesion promoters, and resin additives such as colorants.

[0087] The thermosetting resin composition may contain polymer resins other than component (b) within the range in which the effects of the present invention are achieved. Examples of polymer resins other than component (b) include phenoxy resin, polyvinyl acetal resin, polyimide resin, polyamide-imide resin, polysulfone resin, polyethersulfone resin, and polyphenylene ether resin.

[0088] If the thermosetting resin composition contains polymer resins other than component (b), the content of polymer resins other than component (b) is 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. The lower limit is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.3% by mass or more.

[0089] From the viewpoint of thinning the wiring board, the thickness of the conductive layer is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, and even more preferably 40 μm or less or 20 μm or less. The lower limit of the thickness of the conductive layer is not particularly limited, but is preferably 2 μm or more, and more preferably 5 μm or more.

[0090] <Other layers> The conductive adhesive film may include other layers as needed. For example, a protective film similar to that of the support can be further laminated as the outermost layer on the side of the conductive layer not bonded to the support (i.e., the side opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. Laminating the protective film prevents the adhesion of dust and other debris to the surface of the conductive layer, as well as scratches.

[0091] As a protective film, a film made of plastic material is preferred. Examples of plastic materials include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polyolefins such as polyethylene and polypropylene, polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Among these, polyethylene terephthalate, polyethylene naphthalate, and polypropylene are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0092] Furthermore, as the protective film, a support with a release layer having a release layer on the surface that bonds with the conductive layer may be used. Examples of release agents used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resin, polyolefin resin, urethane resin, and silicone resin. Commercially available products may be used as the support with a release layer, for example, Lintec's "SK-1", "AL-5", "AL-7", and Toray's "Lumirror T6AM", which are PET films having a release layer mainly composed of an alkyd resin-based release agent.

[0093] The thickness of the protective film is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When using a support with a release layer, it is preferable that the overall thickness of the support with the release layer be within the above range.

[0094] <Method for manufacturing conductive adhesive film> The method for manufacturing a conductive adhesive film is not particularly limited as long as it includes a support and a conductive layer bonded to the support. For example, a conductive adhesive film can be manufactured by preparing a resin varnish by dissolving a thermosetting resin composition in an organic solvent, applying this resin varnish onto a support using a die coater or the like, and then drying it to form a conductive layer.

[0095] Examples of organic solvents include ketones such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone. Organic solvents may be used individually or in combination of two or more.

[0096] Drying may be carried out by known methods such as heating or blowing hot air. The drying conditions are not particularly limited, but the organic solvent content in the conductive layer should be 10% by mass or less, preferably 5% by mass or less. Depending on the boiling point of the organic solvent in the resin varnish, for example, when using a resin varnish containing 30% to 60% by mass of organic solvent, the conductive layer can be formed by drying at 50°C to 150°C for 3 to 15 minutes.

[0097] Conductive adhesive films can be stored by being rolled up. If the conductive adhesive film has a protective film, it can be used after the protective film is removed.

[0098] In the conductive adhesive film of the present invention, the cured product obtained by thermosetting the thermosetting resin composition (for example, the cured product obtained by curing at 190°C for 90 minutes (thermosetting resin composition after thermosetting)) exhibits a good resistance value (25°C). That is, it provides a conductive layer exhibiting a good resistance value. The resistance value of the thermosetting resin composition after curing at 25°C is 100Ω or less, preferably 50Ω or less, and more preferably 10Ω or less. The resistance value can be measured according to the method described in <Resistance Value Evaluation> below.

[0099] In the conductive adhesive film of the present invention, the cured product obtained by thermosetting the thermosetting resin composition (for example, the cured product obtained by curing at 190°C for 90 minutes (thermosetting resin composition after thermosetting)) exhibits good adhesive strength (25°C). That is, it provides a conductive layer with good adhesive strength. The adhesive strength between the aluminum foil and glass epoxy via the cured thermosetting resin composition at 25°C is 0.05 kgf / cm or more, preferably 0.08 kgf / cm or more, and more preferably 0.1 kgf / cm or more. The aluminum foil / glass epoxy adhesive strength can be measured according to the method described in <Adhesion Strength Measurement> below.

[0100] For example, the thermosetting conditions for a thermosetting resin composition vary depending on the type of thermosetting resin composition, but the curing temperature can be in the range of 120°C to 240°C (preferably in the range of 150°C to 220°C, more preferably in the range of 170°C to 200°C), and the curing time can be in the range of 5 minutes to 120 minutes (preferably in the range of 10 minutes to 100 minutes, more preferably in the range of 15 minutes to 90 minutes).

[0101] Prior to thermal curing the thermosetting resin composition, it may be preheated at a temperature lower than the curing temperature. For example, prior to thermal curing the thermosetting resin composition, it may be preheated at a temperature of 50°C or higher but less than 120°C (preferably 60°C or higher but 110°C or lower, more preferably 70°C or higher but 100°C or lower) for 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0102] The support for the conductive adhesive film may be peeled off after the conductive adhesive film has been laminated onto the substrate and heat-cured, or the support may be peeled off before the conductive adhesive film has been laminated onto the substrate.

[0103] [Electronic devices, circuit boards, electromagnetic shielding] The conductive adhesive film of the present invention has a cured thermosetting resin composition of the conductive adhesive film as a conductive layer and can be applied to various electronic devices. The conductive adhesive film can be suitably used as an adhesive film for electronic devices such as flexible printed circuit boards. In this case, a circuit board such as a flexible printed circuit board equipped with a cured thermosetting resin composition can be obtained. Furthermore, the conductive adhesive film can be suitably used as an electromagnetic wave shielding film for electronic devices such as flexible printed circuit boards. In this case, an electromagnetic wave shield containing a cured thermosetting resin composition can be obtained. Electronic devices manufactured using the conductive adhesive film usually have a cured thermosetting resin composition of the conductive adhesive film, and this cured material can be strongly bonded to components included in the electronic device. [Examples]

[0104] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" and "%" mean "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0105] <Evaluation of adhesive strength> To evaluate the adhesion of the conductive layer, the adhesive strength between the conductive layer and the glass epoxy board was measured as follows.

[0106] The conductive adhesive films (conductive layer thickness: 25 μm) prepared in the examples and comparative examples were cut to a length of 70 mm and a width of 20 mm. The cut conductive adhesive films were then laminated to the aluminum surface of a 150 mm long x 25 mm wide aluminum foil / PET composite film [PET-attached AL1N30] (aluminum foil 30 μm, PET 25 μm: manufactured by Toyo Aluminum Sales Co., Ltd.) using a batch-type vacuum laminator (Nichigo Morton, V-160). The lamination conditions were a temperature of 80°C, a depressurization time of 30 seconds, followed by pressurization at a pressure of 0.3 MPa for 30 seconds. After that, the PET film of the conductive adhesive film was peeled off, and a glass epoxy board (length 76 mm x width 26 mm x thickness 2 mm, FR-4) was further laminated onto the exposed conductive layer under the same conditions as above. The laminate was then cured in a heat-circulating oven at 180°C for 60 minutes to produce a laminate. The resulting laminate was peeled off at a 90-degree angle to the length of the aluminum foil / PET composite film at a tensile speed of 50 mm / min. The adhesive strength (peel strength) to the glass epoxy board surface was measured, and the adhesion was evaluated according to the following criteria. Good ○: Adhesion strength of 0.1 [kgf / cm] or higher. Defective ×: Adhesion strength less than 0.1 [kgf / cm]

[0107] <Resistance Value Evaluation> The resistance of the conductive layer was measured as follows. The conductive adhesive films (conductive layer thickness: 25 μm) prepared in the examples and comparative examples were cut to a length of 20 mm and a width of 20 mm. The cut conductive adhesive films were then laminated to the aluminum side of a 150 mm long x 25 mm wide aluminum foil / PET composite film [PET-attached AL1N30] (aluminum foil 30 μm, PET 25 μm: product manufactured by Toyo Aluminum Sales Co., Ltd.) using a batch-type vacuum laminator (Nichigo Morton, V-160). The lamination conditions were a temperature of 80°C, a depressurization time of 30 seconds, followed by pressurization at a pressure of 0.3 MPa for 30 seconds. After that, the PET film of the conductive adhesive sheet was peeled off, and the aluminum side of the aluminum foil / PET composite film [PET-attached AL1N30] (aluminum foil 30 μm, PET 25 μm: product manufactured by Toyo Aluminum Sales Co., Ltd.) was laminated onto the exposed conductive layer under the same conditions as above. Finally, the laminate was heated and cured in a heat-circulating oven at 180°C for 60 minutes to produce a laminate. For the obtained laminate, the resistance value was measured on the surface of the aluminum foil using a digital multimeter (Advantest R6552), and the resistance value of the conductive layer was measured. The adhesion was then evaluated according to the following criteria. Good (✓): Resistance value is 10 Ω or less. Defective ×: Resistance value of 10 [Ω] or higher

[0108] <Example 1> 71.7 parts of polymer resin A, manufactured as described below, 10.7 parts of bisphenol-type epoxy resin (ZX1059, manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, epoxy equivalent 169), and 2.6 parts of biphenyl-type epoxy resin (NC3000, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 291) were heated and dissolved in 15 parts of methyl ethyl ketone (MEK) and 15 parts of cyclohexanone while stirring. The heated and melted mixture was cooled to room temperature, and 2.6 parts of an active ester compound (DIC Corporation's "HPC-8000-65T," a toluene solution with a weight-average molecular weight of approximately 2700, an active group equivalent of approximately 223, and a non-volatile content of 65% by mass) were mixed with 0.13 parts of a curing accelerator (Shikoku Chemicals, Inc.'s "1B2PZ," 1-benzyl-2-phenylimidazole), 150 parts of nickel powder (average particle size 2.5 μm, Nikko Rica Co., Ltd.'s "Type255"), and 16 parts of methyl ethyl ketone (MEK). The mixture was then uniformly dispersed using a high-speed rotary mixer to produce resin varnish 1. Next, resin varnish 1 was uniformly applied to a polyethylene terephthalate film (Toray Industries' Lumirror "T6AM", 38 μm thick) so that the thickness of the conductive layer after drying would be 80 μm. After drying at 80-120°C (average 100°C) for 6 minutes, a protective film (polypropylene film, Oji F-Tex's "Alfan MA-430", 20 μm thick) was bonded to the conductive layer with its rough surface to produce a conductive adhesive film.

[0109] [Manufacturing of polymer resin A] In a reaction vessel, 50 g of G-3000 (bifunctional hydroxyl-terminated polybutadiene, number average molecular weight = 5047 (GPC method), hydroxyl group equivalent = 1798 g / eq., solids content 100% by mass: manufactured by Nippon Soda Co., Ltd.), 23.5 g of Ipsol 150 (aromatic hydrocarbon mixed solvent: manufactured by Idemitsu Petrochemical Co., Ltd.) and 0.005 g of dibutyltin laurate were mixed and dissolved uniformly. Once homogeneous, the temperature was raised to 50°C, and while stirring, 4.8 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) was added and the reaction was carried out for approximately 3 hours. Next, the reaction mixture was cooled to room temperature, and then 8.96 g of benzophenone tetracarboxylic dianhydride (acid anhydride equivalent = 161.1 g / eq.), 0.07 g of triethylenediamine, and 40.4 g of ethyl diglycol acetate (manufactured by Daicel Corporation) were added. The mixture was heated to 130°C while stirring and the reaction was carried out for approximately 4 hours. FTIR reading: 2250 cm⁻¹ -1 The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered the endpoint of the reaction, and the reactants were cooled to room temperature and filtered through a 100-mesh filter cloth to obtain polymer resin A having imide, urethane, and polybutadiene structures. Viscosity: 7.5Pa·s (25℃, E-type viscometer) Acid value: 16.9 mg KOH / g Solid content: 50% by mass Number average molecular weight: 13723 Glass transition temperature: -10℃ Polybutadiene structural content: 50 / (50+4.8+8.96)×100 = 78.4% by mass

[0110] <Example 2> A resin varnish was manufactured in the same manner as in Example 1, except that 950 parts of copper powder Cu-HWQ (average particle size 2.7 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.) were used instead of nickel powder, and a conductive adhesive film was obtained.

[0111] <Example 3> Five parts of bisphenol-type epoxy resin (ZX1059, manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, epoxy equivalent 169), forty parts of biphenyl-type epoxy resin (NC3000, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 291), and twenty parts of polybutadiene skeleton-containing epoxy resin (PB3600, manufactured by Daicel Corporation, number average molecular weight Mn: 5900 g / mol, epoxy equivalent 190) were heated and dissolved with stirring in 15 parts of methyl ethyl ketone (MEK) and 15 parts of cyclohexanone. The heated and melted mixture was cooled to room temperature, and to this, 10 parts of triazine-containing phenol novolac resin (DIC Corporation's "LA-7054", hydroxyl group equivalent 125, nitrogen content approximately 12% by weight, solids content 60% by weight MEK solution), 25 parts of naphthol-based curing agent (DIC Corporation's "HPC-9500", hydroxyl group equivalent 153, solids content 60% by weight MEK solution), 0.06 parts of curing accelerator (Shikoku Chemicals, Inc.'s "1B2PZ", 1-benzyl-2-phenylimidazole), 150 parts of nickel powder (average particle size 2.5 μm, Nikko Rica Co., Ltd.'s "Type255"), and 16 parts of methyl ethyl ketone (MEK) were mixed and uniformly dispersed in a high-speed rotary mixer to prepare a resin varnish, and a conductive adhesive film was obtained in the same manner as in Example 1.

[0112] <Example 4> Five parts of bisphenol-type epoxy resin (ZX1059, manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, epoxy equivalent 169), forty parts of biphenyl-type epoxy resin (NC3000, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 291), and 110 parts of epoxy group-containing acrylic acid ester copolymer (SG-80H, manufactured by Nagase ChemteX Co., Ltd., number average molecular weight Mn: 350,000 g / mol, epoxy value 0.07 eq / kg, MEK solution with 18% solids by mass) were heated and dissolved in 10 parts of methyl ethyl ketone (MEK) and 10 parts of cyclohexanone while stirring. The heated and melted mixture was cooled to room temperature, and 20 parts of a triazine skeleton-containing phenolic curing agent (DIC Corporation's "LA-3018-50P", hydroxyl equivalent of approximately 151, 50% solids 2-methoxypropanol solution), 25 parts of a naphthol-based curing agent (DIC Corporation's "HPC-9500", hydroxyl equivalent of 153, 60% solids MEK solution), 0.06 parts of a hardening accelerator (Shikoku Chemicals, Inc.'s "1B2PZ", 1-benzyl-2-phenylimidazole), 150 parts of nickel powder (average particle size 2.5 μm, Nikko Rica Co., Ltd.'s "Type255"), and 16 parts of methyl ethyl ketone (MEK) were mixed and uniformly dispersed in a high-speed rotary mixer to prepare a resin varnish, and a conductive adhesive film was obtained in the same manner as in Example 1.

[0113] <Comparative Example 1> 47 parts of bisphenol-type epoxy resin (ZX1059, manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, epoxy equivalent 169) and 38 parts of biphenyl-type epoxy resin (NC3000, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 291) were heated and dissolved in 25 parts of methyl ethyl ketone (MEK) while stirring. The heated and melted mixture was cooled to room temperature, and 54 parts of phenoxy resin (Mitsubishi Chemical Corporation's "YX7200B35", a MEK solution with 35% solids by weight), 1 part of a curing accelerator (Shikoku Chemicals, Inc.'s "1B2PZ", 1-benzyl-2-phenylimidazole, a MEK solution with 3% solids by weight), 150 parts of nickel powder (average particle size 2.5 μm, Nikko Rica Co., Ltd.'s "Type255"), and 15 parts of methyl ethyl ketone (MEK) were mixed together. The mixture was then uniformly dispersed using a high-speed rotary mixer to produce a resin varnish, and a conductive adhesive film was prepared in the same manner as in Example 1.

[0114] <Comparative Example 2> A resin varnish was manufactured in the same manner as in Comparative Example 1, except that 950 parts of copper powder Cu-HWQ (average particle size 2.7 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.) were used instead of nickel powder, and a conductive adhesive film was obtained.

[0115] <Comparative Example 3> A resin varnish was manufactured in the same manner as in Example 1, except that 52.7 parts of artificial graphite powder SP5030 (average particle size 5 μm, manufactured by Nippon Graphite Co., Ltd.) were used instead of nickel powder, and a conductive adhesive film was obtained.

[0116] [Table 1]

[0117] Examples 1-4 exhibited low resistance and excellent conductivity, as well as high adhesive strength and superior adhesion.

[0118] On the other hand, Comparative Examples 1 and 2, which used phenoxy resin instead of component (b), exhibited excellent conductivity but poor adhesion. Furthermore, Comparative Example 3, which used artificial graphite powder instead of component (c), exhibited poor conductivity and adhesion. [Industrial applicability]

[0119] The conductive adhesive film of the present invention is useful as an adhesive film for electronic devices such as flexible printed circuit boards and as an electromagnetic wave shielding film.

Claims

1. A conductive adhesive film comprising a support and a conductive layer, The conductive layer comprises a thermosetting resin composition. The thermosetting resin composition contains (a) an epoxy resin, (b) a polymer resin having a glass transition temperature of 25°C or lower or being liquid at 25°C, (c) a curing agent, (d) a conductive filler, and (e) a curing accelerator. (a) The component is an epoxy resin having an aromatic structure, (b) The component has one or more structures selected from the group consisting of polybutadiene structures and poly(meth)acrylate structures, (c) Component contains an active ester-based curing agent, (d) Component is at least one selected from metal particles selected from silver, copper, and nickel, and metal-coated particles coated with a metal selected from silver, copper, and nickel. (a) The content of component is 5% by mass or more and 50% by mass or less, when the nonvolatile component in the thermosetting resin composition is taken as 100% by mass. (b) The content of component is 2% by mass or more and 13% by mass or less, when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. (c) The content of component is 2% by mass or more and 30% by mass or less, when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. (d) The content of component is 40% by mass or more and 98% by mass or less, when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. A conductive adhesive film in which the content of component (e) is 0.01% by mass or more and 3% by mass or less, when the nonvolatile components in the thermosetting resin composition are taken as 100% by mass. However, this excludes cases in which component (a) corresponds to component (b).

2. The conductive adhesive film according to claim 1, wherein component (d) is metal particles selected from silver, copper, and nickel.

3. The conductive adhesive film according to claim 1 or 2, wherein the mixing ratio (mass ratio) of component (d) and component (b) is 5 or more and 45 or less (component (d) / component (b)).

4. An electromagnetic shield comprising a cured product of a thermosetting resin composition for a conductive adhesive film according to any one of claims 1 to 3.

5. An electronic device comprising a cured product of a thermosetting resin composition for a conductive adhesive film according to any one of claims 1 to 3.

6. A wiring board comprising a cured product of a thermosetting resin composition layer of a conductive adhesive film according to any one of claims 1 to 3.

7. The wiring board according to claim 6, which is a flexible wiring board.

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