Adhesive composition, adhesive film for circuit connection, connection structure, and method for manufacturing same

Abstract

An adhesive composition according to the present invention includes a thermoplastic resin and a filler, wherein the thermoplastic resin is a polyester urethane resin, and the mass ratio of the polyester urethane resin to the filler is 1.5-5. The adhesive composition including the thermoplastic resin and a filler is such that the thermoplastic resin has a glass transition temperature of 50°C or higher, and a cured product of the adhesive composition has a storage modulus at 100°C of 6.0×107 Pa or higher.

Description

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

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

[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), and this has led to changes in the materials used to make panels.

[0003] Conventional liquid crystal displays use glass substrates as substrates, and as circuit materials formed on the glass substrates, metals such as aluminum are used for the underlying circuit layers, and ITO (Indium Tin Oxide) or the like is used for the surface electrodes. On the other hand, organic LEDs mainly use flexible plastic substrates such as polyimide substrates as substrates, and Ti is used as the circuit material formed on the plastic substrates. Patent Document 1 discusses a circuit connecting material that can provide sufficient adhesive strength when connecting circuit members having substrates made of polyimide resin or the like.

[0004] Japanese Patent Application Laid-Open No. 2006-318990

[0005] In recent years, the market has been demanding increasing levels of reliability in the quality of panels of liquid crystal display devices and the like. Circuit connecting materials are required to have properties that enable them to maintain the connection reliability of connectors even under harsh conditions of high temperature and high humidity. The inventors conducted detailed observations of connectors after high temperature and high humidity tests and found that peeling sometimes occurred between the circuit components and the cured adhesive. There is concern that the progression of peeling may lead to poor connection of the connectors.

[0006] Therefore, an object of the present disclosure is to provide an adhesive composition that can improve connection appearance and reduce connection resistance under high-temperature, high-humidity conditions (e.g., 85°C, 85% RH), and to provide an adhesive film for circuit connection that uses the adhesive composition, as well as a connection structure and a method for producing the same.

[0007] The present disclosure includes, for example, the following [1] to

[13] . [1] An adhesive composition comprising a thermoplastic resin and a filler, wherein the thermoplastic resin is a polyester urethane resin, and the mass ratio of the polyester urethane resin to the filler is 1.5 to 5. [2] The adhesive composition according to [1], wherein the polyester urethane resin has a glass transition temperature of 50°C or higher. [3] A cured product of the adhesive composition has a storage modulus at 100°C of 6.0 x 10 ７ [4] An adhesive composition according to [1] or [2], comprising a thermoplastic resin and a filler, wherein the thermoplastic resin has a glass transition temperature of 50°C or higher, and the cured product of the adhesive composition has a storage modulus of 6.0 x 10 Pa or higher at 100°C. ７an adhesive composition having a viscosity of 100 Pa or more. [5] The adhesive composition according to [4], wherein the thermoplastic resin is a polyester urethane resin. [6] The adhesive composition according to [4] or [5], wherein the mass ratio of the thermoplastic resin to the filler is [4] or [5]. [7] The adhesive composition according to any one of [1] to [6], further comprising a radically polymerizable compound. [8] The adhesive composition according to any one of [1] to [7], further comprising a coupling agent. [9] The adhesive composition according to any one of [1] to [8], further comprising conductive particles.

[10] An adhesive film for circuit connection, comprising an adhesive layer formed from the adhesive composition according to any one of [1] to [9].

[11] An adhesive film for circuit connection, comprising a first adhesive layer and a second adhesive layer laminated on the first adhesive layer, 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 [9].

[12] A connection structure comprising: 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 film for circuit connection described in

[11] .

[13] A method for producing a connection structure, comprising the steps of: interposing the adhesive film for circuit connection described in

[11] 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.

[0008] According to the present disclosure, it is possible to provide an adhesive composition that can improve connection appearance and reduce connection resistance under high-temperature, high-humidity conditions (e.g., 85°C, 85% RH). Furthermore, according to the present disclosure, it is possible to provide an adhesive film for circuit connection that uses the adhesive composition, as well as a connection structure and a method for producing the same.

[0009] 1A and 1B are schematic cross-sectional views showing an adhesive film according to one embodiment, an adhesive film according to another embodiment, and a connection structure according to one embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail, with reference to the drawings as needed. However, the present disclosure is not limited to the following embodiments.

[0011] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the 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 the 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)" means both with and without 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.

[0012] <Adhesive Composition> The adhesive composition of the present embodiment contains a thermoplastic resin and a filler.

[0013] [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.

[0014] 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, polyester urethane resin, etc. The thermoplastic resin may be polyester urethane resin, from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions.

[0015] The polyester urethane resin is composed of monomer components such as a dicarboxylic acid monomer, a diol monomer, and an isocyanate monomer, from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions.

[0016] Examples of the dicarboxylic acid monomer include isophthalic acid, terephthalic acid, and adipic acid. The dicarboxylic acid monomer may be terephthalic acid, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions.

[0017] The content of the 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 further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions; and from the same viewpoint, it may be 60 mol% or less, 50 mol% or less, or 40 mol% or less.

[0018] Examples of the diol monomer include ethylene glycol, propylene glycol, neopentyl glycol, and 1,6-hexanediol. The diol monomer may be propylene glycol, from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions.

[0019] From the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions, the content of the diol monomer in the polyester urethane resin may be 30 mol% or more, 40 mol% or more, or 50 mol% or more, based on the total amount of all monomer components constituting the polyester urethane resin; from the same viewpoint, it may be 75 mol% or less, 65 mol% or less, or 55 mol% or less.

[0020] Examples of the isocyanate monomer include 4,4'-diphenylmethane diisocyanate. The isocyanate monomer may be 4,4'-diphenylmethane diisocyanate from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions.

[0021] The content of the 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 further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions; and from the same viewpoint, it may be 20 mol% or less, 15 mol% or less, or 10 mol% or less.

[0022] The weight average molecular weight of the thermoplastic resin is 1.0 × 10 to provide an adhesive composition with excellent film-forming properties. ４ or more, and from the viewpoint of mixability, 1.0 × 10 ４ Above 1.0 x 10 ６ The weight average molecular weight here is measured by gel permeation chromatography (GPC) under the conditions described in the Examples, using a calibration curve based on standard polystyrene.

[0023] The glass transition temperature (Tg) of the thermoplastic resin may be 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, or 105°C or higher, from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions. The glass transition temperature of the thermoplastic resin may be 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, or 105°C or lower, from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions. The glass transition temperature is measured by the method described in the examples below.

[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 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the resin components of the adhesive composition, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions; and from the same viewpoint, may be 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0026] From the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions, the content of the polyester urethane resin may be 50 mass % or more, 70 mass % or more, 80 mass % or more, 90 mass % or more, or 100 mass % (an embodiment in which the thermoplastic resin contained in the adhesive composition essentially consists of the polyester urethane resin) based on the total mass of the thermoplastic resin contained in the adhesive composition.

[0027] The content of the polyester urethane resin may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the resin components of the adhesive composition, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions; and from the same viewpoint, it may be 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0028] From the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions, the content of the thermoplastic resin having a glass transition temperature of 50°C or higher may be 50% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass (an embodiment in which the thermoplastic resin contained in the adhesive composition is substantially composed of a thermoplastic resin having a glass transition temperature of 50°C or higher) based on the total mass of the thermoplastic resin contained in the adhesive composition.

[0029] The content of the thermoplastic resin having a glass transition temperature of 50°C or higher may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the resin components of the adhesive composition, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions; and from the same viewpoint, may be 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0030] The mass ratio of the thermoplastic resin to the filler (mass-based content of thermoplastic resin / mass-based content of filler) may be 1.5 or more, 1.7 or more, 1.9 or more, or 2.0 or more, from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions. From the same viewpoint, it may be 5 or less, 4 or less, 3 or less, 2.5 or less, or 2.4 or less. The mass ratio of the polyester urethane resin to the filler (mass-based content of polyester urethane resin / mass-based content of filler) may be in the same range as above, from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions. The mass ratio of the thermoplastic resin having a glass transition temperature of 50 ° C. or more to the filler (mass-based content of thermoplastic resin having a glass transition temperature of 50 ° C. or more / mass-based content of filler) may be in the same range as above, from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions.

[0031] [Filler] 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, and may be an inorganic filler from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions.

[0032] Examples of the inorganic filler include metal oxide particles such as silica particles, alumina particles, silica-alumina particles, titania particles, and zirconia particles; metal nitride particles, etc. The inorganic filler may be silica particles, from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions.

[0033] Examples of organic fillers include silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, and polyimide particles.

[0034] 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.

[0035] 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.

[0036] Examples of the alkoxysilane compound 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.

[0037] 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.

[0038] 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] Examples of the siloxane include 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.

[0039] Examples of 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.

[0040] The 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.

[0041] 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 easily controlling 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.

[0042] The average particle size of the filler may be 1 nm or more, 5 nm or more, or 10 nm or more, or 1 μm or less, 100 nm or less, 50 nm or less, or 30 nm or less, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions. The average particle size of the filler is a volume-based average particle size, and can be calculated by observing 100 target fillers with a scanning electron microscope (SEM) and measuring their particle sizes, and can be measured using a particle size analyzer (for example, a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd.).

[0043] The content of the filler may be 1 mass % or more, 5 mass % or more, or 10 mass % or more, based on the total mass of the adhesive composition, from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions; and from the same viewpoint, the content of the filler may be 30 mass % or less, 25 mass % or less, or 20 mass % or less.

[0044] [Radical Polymerizable Compound] The adhesive composition may further contain a radical polymerizable compound from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and further reducing the connection resistance under high temperature and high humidity conditions. The radical 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 radical polymerizable compound may be used in the form of a monomer or oligomer, or a combination of a monomer and an oligomer may be used.

[0045] The radical polymerizable compound may be a (meth)acrylate compound from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions. 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.

[0046] The (meth)acrylate compound may be a (poly)urethane (meth)acrylate from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions. 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 based on the total mass of the radical polymerizable compounds from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and further reducing the connection resistance under high-temperature, high-humidity conditions, and from the same viewpoint, may be 90% by mass or less, or 80% by mass or less.

[0047] The (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 Above 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.

[0048] 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). [In formula (1), n ​​represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.]

[0049] 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.

[0050] From the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions, the content of the (meth)acrylate compound represented by formula (1) may be 1% by mass or more, or 2% by mass or more, and may be 20% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total mass of the radical polymerizable compounds.

[0051] 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.

[0052] The radical 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, or phenoxy resin (excluding those corresponding to thermoplastic resins). These polymers have at least one radically polymerizable functional group in the molecule.

[0053] 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.

[0054] 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 Above 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.

[0055] 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.

[0056] The content of the radical polymerizable compound may be 15% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the adhesive composition, from the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions; and from the same viewpoint, may be 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0057] [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 that decomposes upon heating to generate free radicals. The radical polymerization initiator is appropriately selected depending on the intended connection temperature, connection time, etc.

[0058] Examples of the radical polymerization initiator include diacyl peroxides, peroxydicarbonates, peroxyesters, peroxyketals, dialkyl peroxides, and hydroperoxides.

[0059] 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.

[0060] 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.

[0061] Examples of 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-butylperoxypivalate. Examples of the peroxyalkylene oxide 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.

[0062] 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.

[0063] 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.

[0064] Examples of hydroperoxides include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

[0065] 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.

[0066] From the viewpoint of pot life, the content of the radical polymerization initiator may be 0.1 mass % or more, 0.5 mass % or more, or 1 mass % or more, and may be 10 mass % or less, 5 mass % or less, or 3 mass % or less, based on the total mass of the adhesive composition.

[0067] [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 made of conductive carbon. The conductive particles may be transition metal particles such as Ni coated with a noble metal such as Au. From the viewpoint of obtaining 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 in which a conductive layer is formed on the surface of non-conductive particles such as glass, ceramic, or plastic by a method such as coating the surface of the non-conductive particles with the above-mentioned conductive material, and the outermost layer is further composed of a noble metal. When such particles or heat-fusible metal particles are used, they are deformable by heating and pressurization, so that the contact area with the electrode during connection is increased, thereby improving reliability.

[0068] 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.

[0069] The maximum particle size of the conductive particles must be smaller than the minimum electrode spacing (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 an SEM image.

[0070] 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 arbitrary conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle sizes is defined as the average particle size.

[0071] 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, from the viewpoint of easily obtaining a stable connection resistance, and may be in the range of 0.1 to 10 parts by volume from the viewpoint of preventing short-circuiting of adjacent circuits due to excess conductive particles.

[0072] From the viewpoint of easily obtaining a stable connection resistance, 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, 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.

[0073] [Other Components] The adhesive composition may further contain other components in addition to the components described above, such as coupling agents, softeners, accelerators, antioxidants, colorants, flame retardants, thixotropic agents, and polymerization inhibitors.

[0074] Examples of coupling agents include silane coupling agents having an organic functional group such as a (meth)acryloyl group, a mercapto group, an amino group, an imidazole group, or an epoxy group; silane coupling agents having a butadiene skeleton; silane compounds such as tetraalkoxysilane; tetraalkoxytitanate derivatives; and polydialkyltitanate derivatives. When the adhesive composition contains a coupling agent, adhesion can be further improved. The content of the coupling agent may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total mass of the resin components of the adhesive composition, and may be 20% by mass or less, 15% by mass or less, or 10% by mass or less. Note that, in this specification, silane coupling agents having a polymerizable group such as a (meth)acryloyl group are not included in the polymerizable compound.

[0075] From the viewpoint of further improving the connection appearance under high-temperature and high-humidity conditions and further reducing the connection resistance under high-temperature and high-humidity conditions, the storage modulus at 100°C of the cured product of the adhesive composition is 6.0 × 10 ７ Pa or more, 7.0×10 ７ Pa or more, 8.0×10 ７ Pa or more, 9.0×10 ７ Pa or more, or 1.0 x 10 ８ From the same viewpoint, the pressure may be 3.0×10 Pa or more. ８ Pa or less, 2.0×10 ８ Pa or less, 1.5×10 ８ Pa or less, or 1.0 x 10８ Pa or less.

[0076] The storage modulus at 100°C of the cured product of the adhesive composition can be measured by preparing multiple adhesive films from the adhesive composition, laminating the adhesive films so that the adhesive layer has a thickness of 200 μm, and heating in an oven at 180°C for 1 hour to prepare a cured film for evaluation.The cured film is then subjected to DMA measurement from 50°C to 300°C using a dynamic viscoelasticity device (for example, RSA-3 manufactured by TA Instruments Japan Co., Ltd.) at a heating rate of 10°C / min, to measure the storage modulus at 100°C of the cured product of the adhesive composition.

[0077] The storage modulus at 100°C of the cured product 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, the storage modulus can be adjusted by the filler content, the type of filler, the average particle size of the filler, the ratio of the thermoplastic resin content to the filler content, etc.

[0078] An adhesive composition according to a first embodiment of the present disclosure contains a thermoplastic resin and a filler, the thermoplastic resin being a polyester urethane resin, and the mass ratio of the polyester urethane resin to the filler being 1.5 to 5. Because the adhesive composition contains a polyester urethane resin as the thermoplastic resin and the mass ratio of the polyester urethane resin to the filler is within a specific range, it is possible to improve the connection appearance and reduce the connection resistance under high-temperature, high-humidity conditions (e.g., 85°C, 85% RH). The inventors speculate that the reason for this is as follows.

[0079] In other words, because polyester urethane resin has a flexible skeleton, it can alleviate the shrinkage stress caused by thermal expansion that occurs in high-temperature environments, suppress peeling that occurs at the interface between the circuit component and the adhesive, and make it easier to maintain low connection resistance.

[0080] An adhesive composition according to a second embodiment of the present disclosure contains a thermoplastic resin and a filler, the thermoplastic resin having a glass transition temperature of 50°C or higher, and a storage modulus at 100°C of a cured product of the adhesive composition of 6.0 × 10 ７The adhesive composition contains a thermoplastic resin having a glass transition temperature of a specific value or higher, and the cured product of the adhesive composition has a storage modulus at 100°C of a specific value or higher, which makes it possible to improve the connection appearance and reduce the connection resistance under high-temperature, high-humidity conditions (e.g., 85°C, 85% RH). The inventors speculate that the reason for this is as follows.

[0081] That is, by including a thermoplastic resin having a glass transition temperature equal to or higher than a specific value, the adhesive composition can reduce shrinkage stress due to thermal expansion that occurs in high-temperature environments, suppress peeling that occurs at the interface between the adhesive composition and the adherend, and maintain low connection resistance. Also, by having a storage modulus at 100°C of a cured product of the adhesive composition equal to or higher than a specific value, shrinkage stress due to thermal expansion that occurs in high-temperature environments can be further reduced, suppress peeling that occurs at the interface between the adhesive composition and the adherend, and more easily maintain low connection resistance.

[0082] The adhesive composition described above is suitably used as an adhesive composition for circuit connection 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.

[0083] <Adhesive Film> From the viewpoint of ease of handling, the above-described adhesive composition may be used as an adhesive film formed into a film shape. That is, another embodiment of the present disclosure is an adhesive film (adhesive film for circuit connection) comprising an adhesive layer formed from the adhesive composition. FIG. 1 is a schematic cross-sectional view showing an adhesive film according to one embodiment. The adhesive film 1A shown in FIG. 1 comprises an adhesive layer 2 containing the above-described adhesive composition. The adhesive layer 2 contains adhesive components 3 (components in the adhesive composition other than 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.

[0084] 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. Figure 2 is a schematic cross-sectional view of an adhesive film according to another embodiment. The adhesive film 1B shown in Figure 2 has a first adhesive layer 5 and a second adhesive layer 6 laminated on the first adhesive layer 5.

[0085] 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.

[0086] 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 does not need to contain conductive particles.

[0087] 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 sum of the thickness of the first adhesive layer 5 and the thickness of the second adhesive layer 6) may be, for example, 5 μm or more and 200 μm or less.

[0088] 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.

[0089] 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.

[0090] The adhesive film of this embodiment can be produced by the following method. Specifically, first, the components 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, etc. to prepare a varnish composition (varnish-like adhesive composition). Thereafter, the varnish composition is applied to a release-treated substrate using a knife coater, roll coater, applicator, comma coater, die coater, etc., and the solvent is volatilized by heating to form an adhesive film on the substrate.

[0091] 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. The stirring, mixing, and kneading in preparing the varnish composition can be carried out using, for example, a mixer, a kneading machine, a three-roll mill, a ball mill, a bead mill, or a homodisper.

[0092] The substrate is not particularly limited as long as it has heat resistance sufficient to withstand the heating conditions when volatilizing the solvent, and 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.

[0093] The heating conditions for volatilizing the solvent from the varnish composition applied to the substrate may be conditions that allow the solvent to volatilize sufficiently, such as a temperature of 40°C or higher and 120°C or lower for 0.1 minutes or longer and 10 minutes or shorter.

[0094] 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.

[0095] <Circuit Connection Structure and Manufacturing Method Thereof> Next, a circuit connection structure and a manufacturing method therefor will be described.

[0096] 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.

[0097] 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 electrode (first connection terminal) 12 formed on a main surface 11a of a first substrate 11, a second circuit member 16 having a second electrode (second connection terminal) 15 formed on a main surface 14a of a second substrate 14, 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.

[0098] 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.

[0099] 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.

[0100] The first electrode 12 and the second electrode 15 are formed from 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. Furthermore, a multilayer structure may be formed by combining multiple metals, such as copper / nickel / gold.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] The adhesive composition disposed 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.

[0106] 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.

[0107] Next, the first circuit member 13 and the second circuit member 16 are pressed in the thickness direction while heating the first circuit member 13, adhesive film 1A, and second circuit member 16, 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.

[0108] 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 can be achieved even with heating at 130 to 180°C, 3 MPa, and 10 seconds.

[0109] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0110] <Preparation of Conductive Particles> A nickel layer was formed on the surface of polystyrene particles to a thickness of 0.2 μm, thereby obtaining 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.

[0111] <Preparation Method of 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 tube. A predetermined amount of isocyanate was then added, and 0.02 parts by weight of dibutyltin laurate per 100 parts by weight of polyester polyol was added as a catalyst. The mixture was 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 added dropwise to pure water, and 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 dried in a vacuum dryer to obtain a polyester urethane resin.

[0112] <Synthesis of Polyester Urethane Resin A> Terephthalic acid as the dicarboxylic acid, propylene glycol as the diol, and 4,4'-diphenylmethane diisocyanate as the isocyanate were used in amounts such that the molar ratio of terephthalic acid / propylene glycol / 4,4'-diphenylmethane diisocyanate was 1.0 / 1.3 / 0.25, and polyester urethane resin A was obtained according to the preparation method described above in <Preparation method of polyester urethane resin>. The weight average molecular weight of polyester urethane resin A was measured by gel permeation chromatography and found to be 27,000.

[0113] In addition, polyesterurethane resin A was dissolved in methyl ethyl ketone to obtain a 20% by mass solution of polyesterurethane resin A. This solution was then applied to a PET film (80 μm thick) with one surface treatment 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 measuring device under conditions of a tensile load of 5 gf and a frequency of 10 Hz. In the obtained elastic modulus-temperature curve, the temperature at the point where a line equidistant in the vertical direction 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) was determined to be 105°C.

[0114] <Synthesis of Polyester Urethane Resin B> Polyester urethane resin B was synthesized according to the above <Preparation Method of Polyester Urethane 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 polyester urethane resin B was measured by gel permeation chromatography to be 60,000. The glass transition temperature of polyester urethane resin B was measured in the same manner as polyester urethane resin A to be -3°C.

[0115] <Synthesis of polyurethane acrylate (UA1)> 2,500 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 1,000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich Co.) were uniformly added dropwise over 3 hours to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a calcium chloride drying tube, and a nitrogen gas inlet tube. Next, nitrogen gas was sufficiently introduced into the reaction vessel, and the reaction vessel was heated to 70 to 75°C to allow the mixture 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 the addition of 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich), and the mixture was allowed to react for 6 hours at 70°C in an air atmosphere. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of polyurethane acrylate (UA1) was 15,000. The weight-average molecular weight was measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene under the following conditions. (Measurement conditions) Apparatus: GPC-8020 manufactured by Tosoh Corporation Detector: RI-8020 manufactured by Tosoh Corporation Column: Gelpack GLA160S+GLA150S manufactured by Hitachi High-Technologies Sample concentration: 120 mg / 3 mL Solvent: tetrahydrofuran Injection volume: 60 μL Pressure: 2.94×10 ６ Pa (30kgf / cm ２ ) Flow rate: 1.00mL / min

[0116] <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 Resins A1: Polyester urethane resin (Polyester urethane resin A synthesized above) A2: Polyester urethane resin (Polyester urethane resin B synthesized above) A3: Bisphenol A-type phenoxy resin (trade name: PKHC, manufactured by Union Carbide Corporation) (B) Radically Polymerizable Compounds B1: Polyurethane acrylate (UA1) B2: Isocyanuric acid EO-modified diacrylate (trade name: M-215, manufactured by Toagosei Co., Ltd.) B3: Dicyclopentadiene-type diacrylate (trade name: DCP-A, manufactured by Toagosei Co., Ltd.) B4: 2-Methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.) (C) Coupling Agents C1: 3-Methacryloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) C2: 3-acryloxypropyltrimethoxysilane (trade name: KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) C3: silane coupling agent having a butadiene skeleton (trade name: X-12-1287A, manufactured by Shin-Etsu Chemical Co., Ltd.) (D) Filler D1: aluminum hydroxide particles (average particle size (primary particle size): 1 μm) C2: silica particles (trade name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm) (E) Conductive particles E1: conductive particles prepared above (F) Radical polymerization initiator F1: benzoyl peroxide (trade name: Nyper BMT-K40, manufactured by NOF Corporation)

[0117] The above varnish composition was applied to a substrate (PET film) having 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 preparing an adhesive film. The thickness of the adhesive layer (thickness after drying) was 25 μm.

[0118] <Measurement of Reaction Rate> Two 5 mg samples of adhesive composition were prepared as pre-heated samples. One pre-heated sample was then heated in an air atmosphere (atmospheric air) at 180°C for 1 minute to obtain a post-heated sample. For each of the pre-heated and post-heated samples, the DSC calorific value was measured using a differential scanning calorimetry (DSC) device (product name DSC7, manufactured by Perkin Elmer) under a nitrogen gas flow at a measurement temperature range of 30°C to 250°C and a heating rate of 10°C / min. Based on the measured DSC calorific values, the reaction rate (%) after heating at 180°C for 1 minute was calculated using the following formula: Reaction rate = (Cx - Cy) × 100 / Cx [where Cx represents the DSC calorific value (J / g) of the pre-heated sample, and Cy represents the DSC calorific value (J / g) of the post-heated sample.]

[0119] <Measurement of storage modulus at 100°C> A plurality of the prepared adhesive films were prepared, laminated so that the adhesive layer had a thickness of 200 μm, and heated in an oven at 180°C for 1 hour to produce a cured film for evaluation. Next, the cured film was subjected to DMA measurement from 50°C to 300°C at a heating rate of 10°C / min using a dynamic viscoelasticity device (manufactured by TA Instruments Japan Inc., product name: RSA-3), and the storage modulus (Pa) at 100°C of the cured adhesive composition was measured.

[0120] <Preparation of connection structure> A 25 μm pitch COF (manufactured by FLEXSEED) as the first circuit member and a glass substrate (manufactured by Geomatec Co., Ltd.) with thin film electrodes (height: 1200 Å) made of silicon nitride (SiNx) on a glass substrate as the second circuit member were connected via the prepared adhesive film over a width of 1 mm by heating and pressing at 180° C., 4.5 MPa for 4 seconds using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.), to prepare a circuit connection structure (connection structure).

[0121] <Evaluation of Connection Resistance> The connection resistance of the connection structure prepared above, initially (immediately after preparation) and after a high-temperature, high-humidity test, was measured using a four-terminal measurement method to evaluate the connection resistance between the opposing electrodes. Specifically, using a multimeter (product name: MLR21, manufactured by Kusumoto Chemicals Co., Ltd.), the connection resistance at 16 points between the opposing electrodes was measured and the average value was calculated. The high-temperature, high-humidity test was performed by storing the connection structure in a constant-temperature, constant-humidity chamber at a temperature of 85°C and a humidity of 85% RH for 250 hours.

[0122] <Evaluation of Appearance> The appearance of the connection parts of the connection structures produced above was observed using an optical microscope initially (immediately after production) and after the high-temperature, high-humidity test, and the area where peeling occurred at the substrate-resin interface in the space portion (the portion between the electrode terminals of the FPC (first circuit component)) was measured. The high-temperature, high-humidity test was carried out by storing the connection structures in a constant temperature and humidity chamber at a temperature of 85°C and a humidity of 85% RH for 250 hours. The appearance was evaluated from the peeled area according to the following criteria: A: The ratio of the peeled area to the total area of ​​the space portions is 25% or less. B: The ratio of the peeled area to the total area of ​​the space portions is more than 25% and not more than 50%. C: The ratio of the peeled area to the total area of ​​the space portions is more than 50% and not more than 75%. D: The ratio of the peeled area to the total area of ​​the space portions is more than 75%.

[0123]

[0124]

[0125] 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. An adhesive composition comprising a thermoplastic resin and a filler, wherein the thermoplastic resin is a polyester urethane resin, and the mass ratio of the polyester urethane resin to the filler is 1.5 to 5.

2. The adhesive composition according to claim 1, wherein the glass transition temperature of the polyester urethane resin is 50°C or higher.

3. The storage modulus of the cured product of the adhesive composition at 100°C is 6.0 x 10 ７ The adhesive composition according to claim 1, wherein the viscosity is 100 Pa or more.

4. An adhesive composition containing a thermoplastic resin and a filler, wherein the glass transition temperature of the thermoplastic resin is 50°C or higher, and the storage modulus of a cured product of the adhesive composition at 100°C is 6.0 x 10 ７ The adhesive composition has a viscosity of 100 Pa or more.

5. The adhesive composition according to claim 4, wherein the thermoplastic resin is a polyester urethane resin.

6. The adhesive composition according to claim 4, wherein the mass ratio of said thermoplastic resin to said filler is 1.5 to 5.

7. The adhesive composition according to any one of claims 1 to 6, further comprising a radically polymerizable compound.

8. The adhesive composition according to any one of claims 1 to 6, further comprising a coupling agent.

9. The adhesive composition according to any one of claims 1 to 6, further comprising conductive particles.

10. An adhesive film for circuit connection, comprising an adhesive layer formed from the adhesive composition according to any one of claims 1 to 6.

11. An adhesive film for circuit connection, comprising a first adhesive layer and a second adhesive layer laminated on the first adhesive layer, wherein at least one of the first adhesive layer and the second adhesive layer is a layer formed from the adhesive composition described in any one of claims 1 to 6.

12. A connection structure comprising: 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 film for circuit connection according to claim 11.

13. A method for manufacturing a connection structure, comprising the steps of: interposing an adhesive film for circuit connection according to claim 11 between a first circuit member having a first electrode and a second circuit member having a second electrode; and thermocompressing the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

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