Adhesive composition, adhesive film, connection structure, and method for producing the same

Abstract

To provide an adhesive composition capable of easily manufacturing a connection structure in which connection resistance hardly increases even when external stress is applied to the connection structure. To provide an adhesive film using the adhesive composition, and to provide a connection structure and a method for producing the same.SOLUTION: The adhesive composition has an elongation at break of 100 to 280% after being cured and a strength at break of 16 to 26MPa after being cured. The adhesive film for circuit connection includes an adhesive layer formed of the adhesive composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an adhesive film, a connection structure, and a method for producing the same. [Background technology]

[0002] In recent years, the display industry has seen a paradigm shift in display module technology from liquid crystal displays to organic light-emitting diodes (LEDs), which has led to changes in the materials that make up panels.

[0003] Conventional liquid crystal displays use glass substrates as their substrates, with metals such as aluminum used for the underlying circuit and ITO (indium tin oxide) used for the surface electrodes as circuit materials formed on the glass substrate. On the other hand, organic LEDs use flexible plastic substrates such as polyimide substrates as their substrates, with Ti being the mainstream material for the circuits formed on the plastic substrates. Furthermore, a pressure-sensitive adhesive layer and a flexible member such as a polyethylene terephthalate (PET) substrate are typically disposed on the underside of the polyimide substrate to provide flexibility (see, for example, Patent Document 1).

[0004] In liquid crystal displays, from the viewpoints of fine pitch, light weight and thinness, so-called COG (chip on glass) mounting is adopted, in which various electronic components such as driver ICs are mounted directly on the glass substrate of the display panel. Also, as a COG mounting method, for example, a method is used in which a circuit connection structure is obtained by thermocompression bonding a liquid crystal driver IC onto a glass substrate via a circuit connection adhesive film having anisotropic conductivity in which conductive particles are dispersed in the adhesive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2016-054288 Summary of the Invention [Problem to be solved by the invention]

[0006] When the connection structure is incorporated into a module, the connection structure may be subjected to external stress. When an external load is applied to the connection structure, the connection state of the connection structure becomes unstable, which may result in an increase in connection resistance and a decrease in the functionality of the module.

[0007] Therefore, an object of the present invention is to provide an adhesive composition that can be used to produce a connection structure in which connection resistance is unlikely to increase even when external stress is applied to the connection structure. Another object of the present invention is to provide an adhesive film that uses the adhesive composition, as well as a connection structure and a method for producing the same. [Means for solving the problem]

[0008] The present invention includes, for example, the following [1] to

[11] . [1] A thermoplastic resin and a filler are contained, The breaking elongation after hardening is 100 to 280%. An adhesive composition having a breaking strength after curing of 16 to 26 MPa. [2] The adhesive composition according to [1], wherein the thermoplastic resin comprises a polyester urethane resin. [3] The adhesive composition according to [1] or [2], wherein the content of the filler is 5 parts by mass or more and 50 parts by mass or less, based on 100 parts by mass of the thermoplastic resin. [4] The adhesive composition according to any one of [1] to [3], further comprising a radically polymerizable compound. [5] The adhesive composition according to [4], wherein the radical polymerizable compound contains a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound. [6] The adhesive composition according to any one of [1] to [5], further comprising a coupling agent. [7] The adhesive composition according to any one of [1] to [6], further comprising conductive particles. [8] An adhesive film for circuit connection, comprising an adhesive layer formed from the adhesive composition according to any one of [1] to [7]. [9] A first adhesive layer and a second adhesive layer laminated on the first adhesive layer, An adhesive film for circuit connection, wherein at least one of the first adhesive layer and the second adhesive layer is a layer formed from the adhesive composition according to any one of [1] to [7].

[10] a first circuit member having a first electrode; a second circuit member having a second electrode; a connection portion disposed between the first circuit member and the second circuit member, electrically connecting the first electrode and the second electrode to each other; Equipped with A connection structure, wherein the connection portion comprises a cured product of the adhesive film for circuit connection according to [9].

[11] A method for manufacturing a connection structure, comprising the steps of: interposing an adhesive film for circuit connection described in [9] between a first circuit member having a first electrode and a second circuit member having a second electrode; and thermocompression bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an adhesive composition that can be used to produce a connection structure in which connection resistance is less likely to increase even when external stress is applied to the connection structure. The present invention also provides an adhesive film that uses the adhesive composition, as well as a connection structure and a method for producing the same. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an adhesive film according to one embodiment. [Figure 2] FIG. 4 is a schematic cross-sectional view showing an adhesive film according to another embodiment. [Figure 3]1 is a schematic cross-sectional view showing one embodiment of a connection structure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings where necessary, but the present invention is not limited to the following embodiments.

[0012] In this specification, a numerical range indicated with "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the Examples. Furthermore, the upper and lower limits individually described can be arbitrarily combined. Furthermore, in this specification, "(meth)acrylate" means at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl." Furthermore, "(poly)" refers to both the presence and absence of the "poly" prefix. Furthermore, "A or B" may include either A or B, or may include both. Furthermore, the materials exemplified below may be used alone or in combination of two or more, unless otherwise specified. When a composition contains multiple substances corresponding to each component, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0013] <Adhesive composition> The adhesive composition of the present embodiment contains a thermoplastic resin and a filler.

[0014] [Thermoplastic resin] The adhesive composition contains a thermoplastic resin. When the adhesive composition contains a thermoplastic resin, handling of the adhesive composition can be facilitated when the adhesive composition is formed into a film.

[0015] Examples of thermoplastic resins that can be used include polyvinyl butyral resin, polyvinyl formal resin, polyamide resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, polystyrene resin, xylene resin, polyurethane resin, and polyester urethane resin. These may be used alone or in combination of two or more. The thermoplastic resin may be polyester urethane resin, which facilitates the production of a connection structure in which the connection resistance is unlikely to increase even when external stress is applied to the connection structure.

[0016] Polyester urethane resins can be obtained by reacting a dicarboxylic acid with a diol to obtain a polyester polyol, and then reacting the polyester polyol with an isocyanate. Examples of dicarboxylic acids include isophthalic acid, terephthalic acid, and adipic acid. Examples of diols include ethylene glycol, neopentyl glycol, 1,6-hexanediol, and propylene glycol. Examples of isocyanates include 4,4'-diphenylmethane diisocyanate.

[0017] The content of dicarboxylic acid monomer in the polyester urethane resin may be 15 mol% or more, 25 mol% or more, or 35 mol% or more, based on the total amount of all monomer components constituting the polyester urethane resin, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is less likely to increase even when external stress is applied to the connection structure, and from the same viewpoint, it may be 60 mol% or less, 50 mol% or less, or 45 mol% or less.

[0018] The content of the diol monomer in the polyester urethane resin may be 30 mol% or more, 40 mol% or more, or 45 mol% or more, based on the total amount of all monomer components constituting the polyester urethane resin, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is less likely to increase even when external stress is applied to the connection structure, and from the same viewpoint, it may be 75 mol% or less, 65 mol% or less, or 55 mol% or less.

[0019] The content of isocyanate monomer in the polyester urethane resin may be 1 mol% or more, 5 mol% or more, or 8 mol% or more, based on the total amount of all monomer components constituting the polyester urethane resin, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when external stress is applied to the connection structure, and from the same viewpoint, it may be 20 mol% or less, 15 mol% or less, or 12 mol% or less.

[0020] The weight average molecular weight of the thermoplastic resin is 1.0×10 in order to provide excellent film-forming properties to the adhesive composition. 4 or more, and from the viewpoint of mixability, 1.0 × 10 4 Over 1.0 x 10 6 The weight average molecular weight here is measured by gel permeation chromatography under the conditions described in the Examples using a calibration curve based on standard polystyrene.

[0021] The thermoplastic resin has a glass transition temperature (Tg) of 40°C or higher and a weight average molecular weight of 1.0 x 10 4 The above-mentioned hydroxyl group-containing resin (for example, phenoxy resin) can be used. The hydroxyl group-containing resin may be modified with an epoxy group-containing elastomer.

[0022] Phenoxy resins can be obtained by reacting a difunctional phenol with an epihalohydrin to a high molecular weight, or by subjecting a difunctional epoxy resin with a difunctional phenol to a polyaddition reaction.

[0023] The thermoplastic resin may contain polyester urethane resin, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when an external stress is applied to the connection structure.

[0024] In this specification, the thermoplastic resin having a radically polymerizable functional group is blended as a radically polymerizable compound, which will be described later.

[0025] The content of the thermoplastic resin may be 5% by mass or more, 15% by mass or more, or 25% by mass or more, based on the total mass of the resin components of the adhesive composition, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is less likely to increase even when external stress is applied to the connection structure, and from the same viewpoint, may be 80% by mass or less, 50% by mass or less, or 30% by mass or less.

[0026] [Filling material] The adhesive composition contains a filler. Examples of the filler include non-conductive fillers (e.g., non-conductive particles). The filler may be either an inorganic filler or an organic filler.

[0027] Examples of inorganic fillers include metal oxide particles such as silica particles, alumina particles, silica-alumina particles, titania particles, and zirconia particles; metal nitride particles, etc. These may be used alone or in combination of two or more.

[0028] Examples of organic fillers include silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, polyimide particles, etc. These may be used alone or in combination of two or more.

[0029] The filler may be an inorganic filler or silica particles, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when an external stress is applied to the connection structure. The silica particles may be crystalline silica particles or amorphous silica particles, and these silica particles may be synthetic products. The silica synthesis method may be a dry method or a wet method. The silica particles may include at least one type selected from the group consisting of fumed silica particles and sol-gel silica particles.

[0030] The silica particles may be surface-treated silica particles from the viewpoint of excellent dispersibility in the adhesive component. The surface-treated silica particles are, for example, silica particles whose surface hydroxyl groups have been hydrophobized with a silane compound or a silane coupling agent. The surface-treated silica particles may be, for example, silica particles surface-treated with a silane compound such as an alkoxysilane compound, a disilazane compound, or a siloxane compound, or may be silica particles surface-treated with a silane coupling agent.

[0031] Examples of alkoxysilane compounds include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, and 3,3,3-trifluoropropyltrimethoxysilane.

[0032] Examples of the disilazane compound include 1,1,1,3,3,3-hexamethyldisilazane, 1,3-diphenyltetramethyldisilazane, 1,3-bis(3,3,3-trifluoropropyl)-1,1,3,3-tetramethyldisilazane, and 1,3-divinyl-1,1,3,3-tetramethyldisilazane.

[0033] Examples of siloxane compounds include tetradecamethylcycloheptasiloxane, decamethylcyclopentasiloxane, hexaphenylcyclosiloxane, octadecamethylcyclononasiloxane, hexadecamethylcyclooctasiloxane, dodecamethylcyclohexasiloxane, octaphenylcyclotetrasiloxane, hexamethylcyclotrisiloxane, heptaphenyldisiloxane, tetradecamethylhexasiloxane, dodecamethylpentasiloxane, hexamethyicyclohex ... Tyldisiloxane, decamethyltetrasiloxane, hexamethoxydisiloxane, octamethyltrisiloxane, octamethylcyclotetrasiloxane, 1,3-vinyltetramethyldisiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, 1,3-dimethoxy-1,1,3,3-tetraphenyldisiloxane, 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane, 1,3-dimethyl-1,3-diphenyl-1,3-di Vinyldisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, 1,1,1,3,5,5,5-heptamethyl-3-(3-glycidyloxypropyl)trisiloxane, 1,3,5-tris(3,3,3-trifluoropropyl)-1,3,5-trimethylcyclotrisiloxane, 1,1,1,3,5,5,5-heptamethyl-3-[(trimethylsilyl)oxy]trisiloxane, 1,3-bis[2-(7-hydroxypropyl)methyl]phenyl]-2,3-dimethyl-2,4,6,8-tetramethylcyclotetrasiloxane,

[0033] 1,1,3,3-tetramethyldisiloxane, 1,1,1,5,5,5-hexamethyl-3-[(trimethylsilyl)oxy]-3-vinyltrisiloxane, 3-[[dimethyl(vinyl)silyl]oxy]-1,1,5,5-tetramethyl-3-phenyl-1,5-vinyltrisiloxane, octavinyloctasilsesquioxane, and octaphenyloctasilasilsesquioxane.

[0034] Silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(amino N-(ethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-trimethoxysilylpropylsuccinic anhydride.

[0035] Silica particles that have been surface-treated with a silane compound or a silane coupling agent may be further surface-treated with a silane compound such as 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, or trimethoxyphenylsilane to further hydrophobize the hydroxyl group residues on the surface of the silica particles.

[0036] The surface-treated silica particles may comprise at least one selected from the group consisting of a reaction product (hydrolysis product) of silica and trimethoxyoctylsilane, a reaction product of silica and dimethylsiloxane, a reaction product of silicon dioxide or silica and dichloro(dimethyl)silane, a reaction product (hydrolysis product) of silica and bis(trimethylsilyl)amine, and a reaction product of silica and hexamethyldisilazane, or may comprise at least one selected from the group consisting of a reaction product of silica and trimethoxyoctylsilane, and a reaction product of silica and bis(trimethylsilyl)amine, from the viewpoint of making it easier to control the fluidity when the adhesive film for circuit connection is pressed when the adhesive composition is used as an adhesive film for circuit connection, and from the viewpoint of improving the mechanical properties and water resistance of the connection structure after pressing.

[0037] The content of the filler may be 1 mass % or more, 3 mass % or more, or 5 mass % or more, based on the total mass of the adhesive composition, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when external stress is applied to the connection structure, and from the same viewpoint, may be 30 mass % or less, 20 mass % or less, or 15 mass % or less.

[0038] The content of the filler may be 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more, based on 100 parts by mass of thermoplastic resin, from the viewpoint of making it easier to manufacture a connection structure in which the connection resistance is less likely to increase even when external stress is applied to the connection structure, and from the same viewpoint, it may be 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, or 25 parts by mass or less.

[0039] [Radical polymerizable compounds] The adhesive composition may further contain a radically polymerizable compound from the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when an external stress is applied to the connection structure. The radically polymerizable compound is a compound having a functional group capable of radical polymerization. Examples of such compounds include vinyl compounds having a vinyl group and (meth)acrylate compounds having a (meth)acryloyl group. The radically polymerizable compound may be used in the form of a monomer or an oligomer, or a monomer and an oligomer may be used in combination. The radically polymerizable compound may be used alone or in combination of two or more.

[0040] The radical polymerizable compound is preferably a (meth)acrylate compound, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when an external stress is applied to the connection structure. Examples of the (meth)acrylate compound include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, 2-hydroxy-1,3-di(meth)acryloxypropane, 2,2-bis[4-((meth)acryloxymethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, dicyclopentenyl (meth)acrylate, tricyclodecanyl (meth)acrylate, tris((meth)acryloyloxyethyl)isocyanurate, (poly)urethane (meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, isocyanuric acid EO (ethylene oxide)-modified diacrylate, and 2-methacryloyloxyethyl acid phosphate.

[0041] The (meth)acrylate compound may be a (poly)urethane(meth)acrylate from the viewpoint of balancing crosslink density and cure shrinkage, further reducing connection resistance, and improving high-temperature, high-humidity resistant connection reliability. The content of the (poly)urethane(meth)acrylate may be 20% by mass or more, 40% by mass or more, or 60% by mass or more, and 90% by mass or less, or 80% by mass or less, based on the total mass of the radical polymerizable compounds. The adhesive composition may contain only a (poly)urethane(meth)acrylate as the radical polymerizable compound.

[0042] (Poly)urethane (meth)acrylate has a weight average molecular weight of 1.0 × 10 4 or more, and from the viewpoint of mixing, 1.0 × 10 4 Over 1.0 x 10 6 The weight average molecular weight here is measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene under the conditions described in the Examples.

[0043] The (meth)acrylate compound may also have at least one partial structure selected from the group consisting of a dicyclopentane skeleton, a tricyclodecane skeleton, and a triazine ring. By using a (meth)acrylate compound having such a partial structure as a radically polymerizable compound, the cured product of the adhesive composition will have excellent heat resistance. From the viewpoint of balancing the crosslink density and cure shrinkage and further reducing the connection resistance, the (meth)acrylate compound may be a (meth)acrylate compound having a tricyclodecane skeleton. From the viewpoint of balancing the crosslink density and cure shrinkage, the content of the (meth)acrylate compound having a tricyclodecane skeleton may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, and may be 90% by mass or less, 60% by mass or less, or 30% by mass or less, based on the total mass of the radically polymerizable compounds.

[0044] The (meth)acrylate compound may be a compound represented by the following formula (1) (a (meth)acrylate compound having a phosphate ester structure). In this case, the adhesive strength to the surface of an inorganic material (such as a metal) is improved, resulting in better adhesion between electrodes (for example, between circuit electrodes). [ka] In formula (1), n ​​represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.

[0045] The (meth)acrylate compound represented by formula (1) can be obtained, for example, by reacting phosphoric anhydride with 2-hydroxyethyl (meth)acrylate. Specific examples of the (meth)acrylate compound represented by formula (1) include mono(2-(meth)acryloyloxyethyl) acid phosphate and di(2-(meth)acryloyloxyethyl) acid phosphate.

[0046] From the viewpoint of reducing connection resistance and making it easier to obtain a crosslinking density required to improve connection reliability, the content of the (meth)acrylate compound represented by formula (1) may be 1 mass % or more, or 2 mass % or more, and may be 20 mass % or less, 10 mass % or less, or 5 mass % or less, based on the total mass of the radical polymerizable compounds.

[0047] As the radical polymerizable compound other than the (meth)acrylate compound, for example, the compounds described in Patent Document 5 (WO 2009 / 063827) can be used.

[0048] The radically polymerizable compound may be a polymer such as polyurethane, polystyrene, polyethylene, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyester, polyvinyl chloride, polyphenylene oxide, urea resin, melamine resin, phenol resin, xylene resin, epoxy resin, polyisocyanate resin, phenoxy resin, etc. These polymers have at least one radically polymerizable functional group in the molecule.

[0049] When a polymer is used as the radically polymerizable compound, the adhesive composition is easy to handle and exhibits excellent stress relaxation during curing. Furthermore, when the polymer has a functional group such as a hydroxyl group, the adhesive composition exhibits excellent adhesive properties. From this perspective, it is more preferable to use a polymer modified with a radically polymerizable functional group.

[0050] The weight-average molecular weight of the polymer is 1.0 × 10 4 or more, and from the viewpoint of mixing, 1.0 × 10 4 Over 1.0 x 10 6 The weight average molecular weight here is measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene under the conditions described in the Examples.

[0051] From the viewpoint of facilitating the production of a connection structure in which the connection resistance is unlikely to increase even when external stress is applied to the connection structure, the adhesive composition may contain a monofunctional radically polymerizable compound and a polyfunctional radically polymerizable compound as the radically polymerizable compound, or may contain a radically polymerizable compound that is a monofunctional monomer and a radically polymerizable compound that is a polyfunctional monomer.

[0052] The mass ratio of the content of the polyfunctional radical polymerizable compound to the content of the monofunctional radical polymerizable compound (polyfunctional radical polymerizable compound / monofunctional radical polymerizable compound) may be 1 or more, 5 or more, or 10 or more, from the viewpoint of facilitating the production of a connection structure in which the connection resistance is less likely to increase even when external stress is applied to the connection structure, and from the same viewpoint, may be 1 or less, 0.5 or less, or 0.1 or less.

[0053] From the viewpoint of reducing connection resistance and making it easier to obtain the crosslink density necessary to improve high-temperature and high-humidity resistant connection reliability, the content of the radical polymerizable compound may be 15% by mass or more, 20% by mass or more, or 40% by mass or more, based on the total mass of the resin components of the adhesive composition (components other than the conductive particles and filler (details described later); the same applies hereinafter), and may be 90% by mass or less, 75% by mass or less, or 60% by mass or less.

[0054] The content of the radical polymerizable compound may be 100 parts by mass or more, 120 parts by mass or more, 140 parts by mass or more, or 160 parts by mass or more, based on 100 parts by mass of the thermoplastic resin, from the viewpoint of making it easy to produce a connection structure in which the connection resistance is unlikely to increase even when external stress is applied to the connection structure, and from the same viewpoint, it may be 300 parts by mass or less, 250 parts by mass or less, or 200 parts by mass or less.

[0055] [Radical polymerization initiator] The adhesive composition may further contain a radical polymerization initiator. The radical polymerization initiator is a compound that generates free radicals, such as a peroxide compound or an azo compound, which decomposes upon heating to generate free radicals. The radical polymerization initiator is appropriately selected depending on the intended connection temperature, connection time, etc. The radical polymerization initiator may be used alone or in combination of two or more.

[0056] Examples of the radical polymerization initiator include diacyl peroxides, peroxydicarbonates, peroxyesters, peroxyketals, dialkyl peroxides, and hydroperoxides.

[0057] Examples of diacyl peroxides include 2,4-dichlorobenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic peroxide, benzoylperoxytoluene, and benzoyl peroxide.

[0058] Examples of peroxydicarbonates include di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, di-2-ethoxymethoxyperoxydicarbonate, di(2-ethylhexylperoxy)dicarbonate, dimethoxybutyl peroxydicarbonate, and di(3-methyl-3-methoxybutylperoxy)dicarbonate.

[0059] Peroxyesters include 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, and t-butylperoxy. Examples of peroxyalkylene compounds include 2-ethylhexanoate, t-butylperoxyisobutyrate, 1,1-bis(t-butylperoxy)cyclohexane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(m-toluoylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, and t-butylperoxyacetate.

[0060] Examples of peroxyketals include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-(t-butylperoxy)cyclododecane, and 2,2-bis(t-butylperoxy)decane.

[0061] Examples of dialkyl peroxides include α,α'-bis(t-butylperoxy)diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and t-butylcumyl peroxide.

[0062] Examples of hydroperoxides include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

[0063] These radical polymerization initiators may be used in combination with decomposition accelerators, inhibitors, etc. Furthermore, it is preferable to coat these radical polymerization initiators with a polyurethane-based or polyester-based polymeric substance and microencapsulate them, as this extends the shelf life.

[0064] From the viewpoint of pot life, the content of the radical polymerization initiator may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 20% by mass or less, 15% by mass or less, or 10% by mass or less, based on the total mass of the resin components of the adhesive composition.

[0065] [Conductive particles] The adhesive composition may further contain conductive particles. The conductive particles may be metal particles such as Au, Ag, Ni, Cu, or solder, or conductive carbon particles composed of conductive carbon. The conductive particles may be transition metal particles such as Ni coated with a noble metal such as Au. To ensure a sufficient pot life, the surface layer may be Au, Ag, or a noble metal of the platinum group, or may be Au. The conductive particles may be coated conductive particles formed by coating the surface of non-conductive particles such as glass, ceramic, or plastic with the above-mentioned conductive material to form a conductive layer on the surface of the non-conductive particles, and further forming an outermost layer of a noble metal. When such particles or heat-fusible metal particles are used, they are deformable by heating and pressurization, increasing the contact area with the electrode during connection and improving reliability.

[0066] The conductive particles may be insulating coated conductive particles comprising the above-mentioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer containing an insulating material such as a resin and coating the surfaces of the particles. When the conductive particles are insulating coated conductive particles, even if the content of the conductive particles is high, the surfaces of the particles are coated with resin, so that the occurrence of short circuits due to contact between the conductive particles can be suppressed and the insulation between adjacent electrode circuits can also be improved.

[0067] The conductive particles may be any of the above-mentioned various conductive particles, used singly or in combination of two or more.

[0068] The maximum particle size of the conductive particles must be smaller than the minimum spacing between the electrodes (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of the conductive particles may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of the conductive particles may be 50 μm or less, 30 μm or less, or 20 μm or less. In this specification, the particle size of 300 random conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is defined as the maximum particle size of the conductive particles. Note that if the conductive particles are not spherical, e.g., have protrusions, the particle size of the conductive particles is defined as the diameter of a circle circumscribing the conductive particles in the SEM image.

[0069] The average particle size of the conductive particles may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more, from the viewpoint of excellent dispersibility and conductivity. The average particle size of the conductive particles may be 50 μm or less, 30 μm or less, or 20 μm or less, from the viewpoint of excellent dispersibility and conductivity. In this specification, the particle size of 300 random conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the particle sizes obtained is defined as the average particle size.

[0070] The content of the conductive particles may be in the range of 0.1 to 30 parts by volume relative to 100 parts by volume of the resin component of the adhesive composition, since this makes it easier to obtain stable connection resistance. The content of the conductive particles may be in the range of 0.1 to 10 parts by volume, from the viewpoint of preventing short circuits between adjacent circuits due to excess conductive particles.

[0071] The content of the conductive particles may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, based on the total mass of the resin components of the adhesive composition, from the viewpoint of easily obtaining a stable connection resistance, and may be 30% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total mass of the resin components of the adhesive composition.

[0072] [Other ingredients] The adhesive composition may further contain other components in addition to the components described above. Examples of other components include thiol compounds, coupling agents, softeners, accelerators, antioxidants, colorants, flame retardants, thixotropic agents, and polymerization inhibitors. These components may be used alone or in combination of two or more.

[0073] The thiol compound may be a thiol compound having one thiol group (monofunctional thiol compound), or may be a thiol compound having a plurality of thiol groups (polyfunctional thiol compound).

[0074] The thiol group contained in the thiol compound may be a primary thiol group, a secondary thiol group, or a tertiary thiol group.

[0075] Examples of monofunctional thiol compounds include 2-mercaptobenzothiazole, 2-methyl-4,5-dihydrofuran-3-thiol, 3-mercapto-1-hexanol, mercaptomethylbutanol, 3-mercapto-2-methylpentanol, 3-mercapto-3-methylbutanol, 4-ethoxy-2-methyl-2-butanethiol, hexanethiol, isobutylthiol, 1,1-dimethylheptanethiol, 2-ethylhexyl-3-mercaptopropionate, n-octyl-3-mercaptopropionate, methoxybutyl-3-mercaptopropionate, and stearyl-3-mercaptopropionate.

[0076] Examples of polyfunctional thiol compounds include pentaerythritol tetrakis(3-mercaptobutyrate), ethanedithiol, 1,3-propanethiol, 1,4-butanethiol, trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, and tetraethylene glycol bis(3-mercaptopropionate).

[0077] The content of the thiol compound may be 0.5% by mass or more, 1% by mass or more, or 1.5% by mass or more, based on the total mass of the resin components of the adhesive composition, from the viewpoint of suppressing peeling at the interface between the adhesive composition and the circuit member after curing and suppressing an increase in the connection resistance of the circuit connection structure; and may be 5% by mass or less, 3% by mass or less, or 2% by mass or less, from the viewpoint of suppressing peeling at the interface between the adhesive composition and the circuit member after curing and suppressing an increase in the connection resistance of the circuit connection structure.

[0078] As the coupling agent, a compound having at least one of a vinyl group, an acryloyl group, an amino group, an epoxy group, and an isocyanate group can be used in order to improve adhesiveness.

[0079] The adhesive composition according to one embodiment of the present invention has a post-cure breaking elongation of 100 to 280% and a post-cure breaking strength of 16 to 26 MPa. The post-cure breaking elongation and breaking strength are measured using a thermostatic tester (e.g., SSR-111 manufactured by Isuzu Motors Co., Ltd.) by curing the adhesive composition at a set temperature of 180°C for 1 hour, and then cutting the cured adhesive composition into a measurement sample with a width of 5 mm and a length of 10 mm. The breaking elongation and breaking strength of the measurement sample can then be measured using a dynamic viscoelasticity measuring device (e.g., RSA-G2 manufactured by TA Instruments Japan Co., Ltd.) at a measurement speed of 50 mm / min and a load of 5 g.

[0080] The present inventors speculate as follows about the reason why the adhesive composition according to one embodiment of the present invention has a post-cure breaking elongation of 100 to 280% and a post-cure breaking strength of 16 to 26 MPa, and therefore can produce a connection structure in which the connection resistance is less likely to increase even when an external stress is applied to the connection structure. That is, the inventors have found that conventional adhesive compositions have a high breaking strength after curing in order to sufficiently increase the connection strength of the adhesive composition. However, conventional adhesive compositions have a low breaking elongation after curing, and when external stress is applied, the adhesive composition is unable to deform in response to the stress, making it impossible to maintain the connection. Furthermore, if the breaking elongation of the adhesive composition after curing is too high, the resin becomes too fluid, making it impossible to maintain the connection. Furthermore, from the perspective of capturing particles (filler, conductive particles) contained in the adhesive composition, increasing the breaking elongation of the adhesive composition after curing has not been considered. Furthermore, even if the breaking elongation of the adhesive composition after curing is increased, if the breaking strength of the adhesive composition after curing is insufficient, the adhesive composition will be unable to withstand the external stress when it is applied, making it impossible to maintain the connection. Based on these findings, with the adhesive composition according to one embodiment of the present invention, the breaking elongation after curing and the breaking strength after curing are each within a specific range, and therefore it is possible to produce a connection structure in which the connection resistance is less likely to increase even when external stress is applied to the connection structure.

[0081] The breaking elongation after curing may be 260% or less, 240% or less, 220% or less, 200% or less, 190% or less, 180% or less, or 170% or less, from the viewpoint of facilitating the production of a connection structure in which connection resistance is unlikely to increase even when external stress is applied to the connection structure, or may be 160% or less, 150% or less, 140% or less, 130% or less, 120% or less, or 110% or less, from the viewpoint of facilitating the production of a connection structure in which connection resistance is unlikely to increase even when external stress is applied to the connection structure. The breaking elongation after curing may be 110% or more, 120% or more, 130% or more, 140% or more, 150% or more, 160% or more, or 170% or more.

[0082] The breaking strength after curing may be 17 MPa or more, 18 MPa or more, 19 MPa or more, 20 MPa or more, 21 MPa or more, 22 MPa or more, or 23 MPa or more, from the viewpoint of facilitating the production of a connection structure in which connection resistance is unlikely to increase even when external stress is applied to the connection structure. The breaking strength after curing may be 25 MPa or less, or 24 MPa or less, from the viewpoint of facilitating the production of a connection structure in which connection resistance is unlikely to increase even when external stress is applied to the connection structure. The breaking strength after curing may be 23 MPa or less, 22 MPa or less, 21 MPa or less, or 20 MPa or less.

[0083] The breaking elongation and breaking strength after curing of the adhesive composition can be adjusted, for example, by adjusting the type and / or content of each component of the adhesive composition. More specifically, these can be adjusted by the content of the filler, the ratio of the content of the thermoplastic resin to the content of the filler, and the content and ratio of the monofunctional radically polymerizable compound to the polyfunctional radically polymerizable compound in the radically polymerizable compound. For example, the breaking elongation of the adhesive composition after curing tends to be large when it contains a component with a high elongation percentage.

[0084] The adhesive composition described above is suitably used as a circuit connection adhesive composition for connecting circuit components having electrodes with the electrodes arranged opposite each other, and is particularly suitably used as an anisotropically conductive adhesive composition for connecting circuit components with each other.

[0085] <Adhesive film> The above-described adhesive composition may be formed into a film and used as an adhesive film from the viewpoint of ease of handling. FIG. 1 is a schematic cross-sectional view showing an adhesive film according to one embodiment. The adhesive film 1A shown in FIG. 1 includes an adhesive layer 2 containing the above-described adhesive composition. The adhesive layer 2 contains an adhesive component 3 (components in the adhesive composition other than the conductive particles) and conductive particles 4 dispersed in the adhesive component 3. The thickness of the adhesive film 1A may be 10 μm or more and 50 μm or less.

[0086] In other embodiments, the adhesive film may have multiple adhesive layers. When an adhesive film having multiple adhesive layers is used to connect circuit components, stable connection resistance is more likely to be obtained. FIG. 2 is a schematic cross-sectional view of an adhesive film according to another embodiment. The adhesive film 1B shown in FIG. 2 has a first adhesive layer 5 and a second adhesive layer 6 laminated on the first adhesive layer 5.

[0087] The first adhesive layer 5 contains the adhesive composition described above. That is, the first adhesive layer 5 contains the adhesive component 3 and the conductive particles 4 dispersed in the adhesive component 3.

[0088] The second adhesive layer 6 contains, for example, a radical polymerizable compound and a radical polymerization initiator. The radical polymerization initiator and radical polymerization initiator may be those used in the adhesive composition described above. The second adhesive layer 6 may further contain the thermoplastic resin described above and the components exemplified as other components in the adhesive composition. The second adhesive layer 6 may not contain conductive particles.

[0089] The thicknesses of the first adhesive layer 5 and the second adhesive layer 6 may be appropriately set depending on the height of the electrodes of the circuit components to be adhered, etc. The thickness of the first adhesive layer 5 may be, for example, 0.5 μm or more and 20 μm or less. The thickness of the second adhesive layer 6 may be, for example, 5 μm or more and 200 μm or less. The thickness of the adhesive film 1B (the total thickness of the first adhesive layer 5 and the second adhesive layer 6) may be, for example, 5 μm or more and 200 μm or less.

[0090] The adhesive film is not limited to the above embodiment, and may be, for example, an adhesive film including one adhesive layer that does not contain conductive particles. The adhesive film may also be a three-layer film including an adhesive layer that contains conductive particles and an adhesive layer that does not contain conductive particles provided on both sides of the adhesive layer.

[0091] The adhesive film described above can be suitably used as an adhesive film for circuit connection for connecting circuit members having electrodes with each other in a state where the electrodes are arranged opposite each other.

[0092] The adhesive film of this embodiment can be produced by the following method. Specifically, first, the components to be contained in the adhesive layer (e.g., adhesive components and conductive particles) are added to a solvent such as an organic solvent, and dissolved or dispersed by stirring, mixing, kneading, or the like to prepare a varnish composition (varnish-like adhesive composition). The varnish composition is then applied to a release-treated substrate using a knife coater, roll coater, applicator, comma coater, die coater, or the like, and the solvent is then volatilized by heating to form an adhesive film on the substrate.

[0093] The solvent used in preparing the varnish composition may be a solvent capable of uniformly dissolving or dispersing each component. Examples of such solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These solvents may be used alone or in combination of two or more. The stirring, mixing, and kneading in preparing the varnish composition may be carried out using, for example, a mixer, a grinder, a three-roll mill, a ball mill, a bead mill, or a homodisper.

[0094] The substrate is not particularly limited as long as it has heat resistance that can withstand the heating conditions used to volatilize the solvent. For example, films formed from oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. can be used.

[0095] The heating conditions for volatilizing the solvent from the varnish composition applied to the substrate may be such that the solvent is sufficiently volatilized, for example, at 40°C or higher and 120°C or lower for 0.1 to 10 minutes.

[0096] In the adhesive film of this embodiment, some of the solvent may remain unremoved. The content of the solvent in the adhesive film for circuit connection of this embodiment may be, for example, 10 mass % or less, or 5 mass % or less, based on the total mass of the adhesive film.

[0097] <Circuit connection structure and method for manufacturing the same> Next, the circuit connection structure and the method for manufacturing the same will be described.

[0098] The connection structure of this embodiment comprises a first circuit member having a first electrode, a second circuit member having a second electrode, and a connection portion disposed between the first circuit member and the second circuit member and electrically connecting the first electrode and the second electrode to each other, wherein the connection portion comprises a cured product of the adhesive composition of this embodiment.

[0099] Fig. 3 is a schematic cross-sectional view showing one embodiment of a connection structure. The connection structure 10 shown in Fig. 3 includes a first circuit member 13 having a first substrate 11 and a first electrode (first connection terminal) 12 formed on a main surface 11a thereof, a second circuit member 16 having a second substrate 14 and a second electrode (second connection terminal) 15 formed on a main surface 14a thereof, and a connecting portion 17 interposed between the first circuit member 13 and the second circuit member 16 to bond them together. The second circuit member 16 is disposed opposite the first circuit member 13 so that the second electrode 15 faces the first electrode 12.

[0100] The connection portion 17 includes a cured product of the adhesive composition, and is composed of a cured product 18 of the adhesive component and conductive particles 4 dispersed in this cured product 18. The opposing first electrode 12 and second electrode 15 are electrically connected via the conductive particles 4. Meanwhile, the first electrodes 12 and second electrodes 15 formed on the same substrate are insulated from each other.

[0101] Examples of the first substrate 11 and the second substrate 14 include chip components such as semiconductor chips, resistor chips, and capacitor chips, and substrates such as printed circuit boards. While circuit components typically have multiple connection terminals, a single connection terminal may be sufficient in some cases. More specifically, substrates made of semiconductors, inorganic materials such as glass and ceramic, plastic substrates, or glass / epoxy substrates are used. Examples of plastic substrates include polyimide films, polycarbonate films, and polyester films.

[0102] The first electrode 12 and the second electrode 15 are made of a metal such as copper. To obtain better electrical connection, it is preferable to form a surface layer containing a metal selected from gold, silver, tin, and platinum group metals on at least one of the first electrode 12 and the second electrode 15. The surface layer is selected from gold, silver, platinum group metals, or tin, and these may be used in combination. Alternatively, a multilayer structure may be formed by combining multiple metals, such as copper / nickel / gold.

[0103] One of the first circuit member 13 and the second circuit member 16 may be a liquid crystal display panel having a glass substrate or a plastic substrate as a circuit board and having connection terminals formed from ITO or the like. Alternatively, one of the first circuit member 13 and the second circuit member 16 may be a flexible printed circuit board (FPC), a tape carrier package (TCP), or a chip-on-film (COF) having a polyimide film as a circuit board, or a semiconductor silicon chip having a semiconductor substrate as a circuit board. These various circuit members are appropriately combined as needed to form a connection structure.

[0104] It is preferable that the substrates provided with the electrodes are pre-heat treated before connection with the adhesive composition in order to eliminate the influence on connection of volatile components caused by heating during connection.

[0105] A method for manufacturing a connection structure according to this embodiment includes the steps of interposing the adhesive composition according to this embodiment between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermocompression bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

[0106] Specifically, first, a first circuit member 13 having a first electrode (first connection terminal) 12 formed on a main surface 11a of a first substrate 11, and a second circuit member 16 having a second electrode (second connection terminal) 15 formed on a main surface 14a of a second substrate 14 are prepared. Then, the first circuit member 13 and the second circuit member 16 are arranged so that the first electrode 12 and the second electrode 15 face each other, and an adhesive composition is placed between the first circuit member 13 and the second circuit member 16.

[0107] The adhesive composition to be placed between the first circuit member 13 and the second circuit member 16 may be the adhesive film 1A or 1B described above, or a varnish composition (varnish-like adhesive composition) may be applied onto the first circuit member 13 or the second circuit member 16, or onto both.

[0108] When using an adhesive film 1B having two adhesive layers, the adhesive film 1B may be positioned so that the first adhesive layer 5 containing conductive particles faces the first circuit member 13 and the second adhesive layer 6 not containing conductive particles faces the second circuit member 16, or the adhesive film 1B may be positioned so that the first adhesive layer 5 faces the second circuit member 16 and the second adhesive layer 6 faces the first circuit member 13.

[0109] Next, the first circuit member 13 and the second circuit member 16 are pressed in the thickness direction while being heated, thereby thermocompression-bonding the first circuit member 13 and the second circuit member 16. The adhesive component of the adhesive composition is cured by heating, and as a result, the first circuit member 13 and the second circuit member 16 are pressure-bonded together via the cured product of the adhesive composition.

[0110] The pressure to be applied is not particularly limited as long as it does not damage the adherend, but is generally preferably 0.1 to 10 MPa. The heating temperature is not particularly limited, but is preferably 100 to 200°C. The pressure and heating are preferably carried out for 0.5 to 100 seconds, and adhesion is also possible with heating at 130 to 180°C, 3 MPa, and 10 seconds. [Example]

[0111] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0112] <Method for synthesizing polyester urethane resin> After reacting a dicarboxylic acid with a diol to obtain a polyester polyol, the polyester polyol was dissolved in methyl ethyl ketone. The resulting solution was placed in a heated stainless steel autoclave equipped with a stirrer, thermometer, condenser, vacuum generator, and nitrogen gas inlet. A predetermined amount of isocyanate was then added, followed by 0.02 parts by weight of dibutyltin laurate per 100 parts by weight of polyester polyol as a catalyst. The mixture was then reacted at 75°C for 10 hours and then cooled to 40°C. Piperazine was then added and reacted for 30 minutes to extend the chain, followed by neutralization with triethylamine. The reacted solution was then added dropwise to pure water, whereupon the solvent and catalyst dissolved in the water, resulting in the precipitation of a polyester urethane resin as an ester urethane compound. The precipitated polyester urethane resin was then dried in a vacuum dryer to obtain a polyester urethane resin.

[0113] <Synthesis of polyester urethane resin PU1> Polyesterurethane resin PU1 was synthesized according to the procedure described above in "Method for Synthesizing Polyesterurethane Resin," using isophthalic acid, terephthalic acid, and adipic acid as dicarboxylic acids, ethylene glycol, neopentyl glycol, and 1,6-hexanediol as diols, and 4,4'-diphenylmethane diisocyanate as diisocyanate in amounts such that the molar ratio of isophthalic acid / terephthalic acid / adipic acid / ethylene glycol / neopentyl glycol / 1,6-hexanediol / 4,4'-diphenylmethane diisocyanate was 0.21 / 0.21 / 0.58 / 0.19 / 0.55 / 0.46 / 0.30. The weight-average molecular weight of polyesterurethane resin PU1 was measured by gel permeation chromatography to be 60,000.

[0114] In addition, polyesterurethane resin PU1 was dissolved in methyl ethyl ketone to obtain a 20% by mass solution of polyesterurethane resin PU1. This solution was then applied to a PET film (80 μm thick) with a surface treatment on one side using a coating device, and hot air dried at 70°C for 10 minutes to obtain a 35 μm thick film. The temperature dependence of the elastic modulus of this film was measured using a wide-range dynamic viscoelasticity analyzer under conditions of a tensile load of 5 gf and a frequency of 10 Hz. The glass transition temperature of polyesterurethane resin PU1 was determined as the temperature at the point where a line equidistant along the vertical axis from a line extending the baseline before and after the glass transition region intersects with the curve representing the stepwise change in the glass transition region (midpoint glass transition temperature), which was found to be -3°C.

[0115] <Synthesis of polyester urethane resin PU2> Terephthalic acid was used as the dicarboxylic acid, propylene glycol as the diol, and 4,4'-diphenylmethane diisocyanate as the isocyanate in amounts such that the molar ratio of terephthalic acid / propylene glycol / 4,4'-diphenylmethane diisocyanate was 1.0 / 1.3 / 0.25, and polyesterurethane resin PU2 was obtained according to the procedure described above in "Method for synthesizing polyesterurethane resin." The weight-average molecular weight of polyesterurethane resin PU2 was measured by gel permeation chromatography and found to be 27,000. The glass transition temperature of polyesterurethane resin PU2 was measured in the same manner as polyesterurethane resin PU1 and found to be 105°C.

[0116] <Synthesis of polyurethane acrylate (UA1)> Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a calcium chloride drying tube, and a nitrogen gas inlet tube, 2500 parts by mass (2.50 mol) of poly(1,6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight 1000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich) were uniformly added dropwise over 3 hours. Next, after sufficient nitrogen gas was introduced into the reaction vessel, the reaction vessel was heated to 70-75°C and the mixture was allowed to react. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (Sigma-Aldrich) were added to the reaction vessel, followed by 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich). The mixture was allowed to react for 6 hours at 70°C under an air atmosphere. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of the polyurethane acrylate (UA1) was 15,000. The weight-average molecular weight was measured in the same manner as for the polyester urethane resin described above.

[0117] [Measurement conditions for weight-average molecular weight] Equipment: Tosoh GPC-8020 Detector: Tosoh Corporation RI-8020 Column: Gelpack GLA160S+GLA150S manufactured by Resonac Co., Ltd. Sample concentration: 120mg / 3mL Solvent: tetrahydrofuran Injection volume: 60μL Pressure: 2.94 x 106 Pa (30 kgf / cm 2 ) Flow rate: 1.00mL / min

[0118] <Preparation of conductive particles> A nickel layer was formed on the surface of the polystyrene particles to a thickness of 0.2 μm, yielding conductive particles with an average particle size of 4 μm, a maximum particle size of 4.5 μm, and a specific gravity of 2.5.

[0119] <Preparation of Thermosetting Adhesive Varnish (Varnish Composition)> The components shown below were mixed in the amounts (unit: parts by mass) shown in Tables 1 and 2 to prepare varnish compositions (varnish-like adhesive compositions). (A) Thermoplastic resin A1: Polyester urethane resin (PU1) synthesized above A2: Polyester urethane resin (PU2) synthesized above (B) Radical polymerizable compound B1: Polyurethane acrylate (UA1) synthesized above B2: Isocyanuric acid EO-modified diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.), multifunctional B3: Dicyclopentadiene diacrylate (trade name: DCP-A, manufactured by Toagosei Co., Ltd.), multifunctional B4: N-acryloylmorpholine (product name: ACMO, manufactured by KJ Chemicals Co., Ltd.), monofunctional (C) Filler C1: Silica fine particles (product name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm) (D) Coupling Agent D1: 3-methacryloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) (F) Conductive particles F1: Conductive particles prepared above (G) Radical polymerization initiator G1: Benzoyl peroxide (product name: Niper BMT-K40, manufactured by NOF Corporation)

[0120] The above varnish composition was applied to a substrate (PET film) with a thickness of 50 μm using a coating device. Then, hot air drying was performed at 70 ° C for 3 minutes to form an adhesive layer on the substrate, thereby producing an adhesive film. The thickness of the adhesive layer (thickness after drying) was 25 μm.

[0121] <Preparation of cured film> The adhesive film was heated for 1 hour at a set temperature of 180°C in a thermostatic tester (Isuzu Motors Ltd., SSR-111) to form a cured film. The calorific value of the film was measured under the following conditions using differential scanning calorimetry (DSC), and the cure rate of the film was calculated according to the following formula (A), and it was confirmed that the cure rate exceeded 80%. [DSC measurement conditions] Measurement atmosphere: Helium atmosphere (flow rate: 50 ml / min) Measurement temperature range: 40 to 200°C Heating rate: 10℃ / min Cure rate (%) = (initial heat generation amount - heat generation amount after curing) / initial heat generation amount × 100 (A)

[0122] <Measurement of breaking elongation> The cured film prepared above was cut into a 5 mm wide and 10 mm long sample to be used as a measurement sample. The breaking elongation of the sample was then measured using a dynamic viscoelasticity measuring device (TA Instruments Japan, RSA-G2) at a measurement speed of 50 mm / min.

[0123] <Measurement of breaking strength> The cured film prepared above was cut into a 5 mm wide and 10 mm long sample to be used as a measurement sample. The breaking strength of the sample was then measured using a dynamic viscoelasticity measuring device (TA Instruments Japan, RSA-G2) at a measurement speed of 50 mm / min and a load of 5 g.

[0124] <Measurement of connection resistance when external stress is applied> The adhesive film thus produced was cut into a piece 2 mm wide and 3 mm long, and used to connect the Au part (ground electrode) of a printed circuit board (PWB board) to the Au wiring of a flexible printed circuit board (FPC) under the following conditions, thereby obtaining a connection structure. PWB substrate: 1.5 mm thick Au wiring (FPC): L / S=50 / 50, FPC wiring 35μm Mounting conditions: 155°C, 1 MPa, 8 seconds (cushion material: silicon 200 μm thick)

[0125] A jig was attached to the mounting part of the connection structure, and the jig was pulled straight up using a Tensilon universal material testing machine (RTI-1225, manufactured by A&D Co., Ltd.) at a measurement environment temperature of 25°C and a movement speed of 5 mm / min, and the relationship between connection resistance and pull strength (the force pulling the mounting part of the connection structure straight up) while pulling was evaluated. The pull strength when the connection resistance increased by 20% from the initial connection resistance is shown in Tables 1 and 2. Note that because the connection state of the connection structure changes when external stress is applied, the greater the pull strength when the connection resistance increased by 20% from the initial connection resistance, the smaller the effect of external stress application, and it can be said that the connection structure is less likely to experience an increase in connection resistance even when external stress is applied to the connection structure.

[0126] [Table 1]

[0127] [Table 2] [Explanation of symbols]

[0128] 1A, 1B...adhesive film, 2...adhesive layer, 3...adhesive component, 4...conductive particles, 5...first adhesive layer, 6...second adhesive layer, 10...connection structure, 11...first substrate, 12...first electrode, 13...first circuit member, 14...second substrate, 15...second electrode, 16...second circuit member, 17...connection portion.

Claims

1. Contains a thermoplastic resin and a filler, The breaking elongation after curing is 100 to 280%, An adhesive composition having a breaking strength after curing of 16 to 26 MPa.

2. The adhesive composition of claim 1 , wherein the thermoplastic resin comprises a polyester urethane resin.

3. The adhesive composition according to claim 1 , wherein the content of the filler is 5 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the thermoplastic resin.

4. The adhesive composition according to claim 1 , further comprising a radically polymerizable compound.

5. The adhesive composition according to claim 4 , wherein the radical polymerizable compound comprises a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound.

6. The adhesive composition of claim 1 further comprising a coupling agent.

7. The adhesive composition of claim 1 further comprising conductive particles.

8. An adhesive film for circuit connection, comprising an adhesive layer formed from the adhesive composition according to any one of claims 1 to 7.

9. a first adhesive layer and a second adhesive layer laminated on the first adhesive layer; An adhesive film for circuit connection, wherein at least one of the first adhesive layer and the second adhesive layer is a layer formed from the adhesive composition according to any one of claims 1 to 7.

10. a first circuit member having a first electrode; a second circuit member having a second electrode; a connection portion disposed between the first circuit member and the second circuit member, electrically connecting the first electrode and the second electrode to each other; Equipped with A connection structure, wherein the connection portion comprises a cured product of the adhesive film for circuit connection according to claim 9 .

11. 10. A method for producing a connection structure, comprising the steps of: interposing the adhesive film for circuit connection according to claim 9 between a first circuit member having a first electrode and a second circuit member having a second electrode; and thermocompression bonding the first circuit member and the second circuit member together to electrically connect the first electrode and the second electrode to each other.

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