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

Abstract

To provide an adhesive composition capable of improving connection appearance and reducing connection resistance in a salt water sprayed state.SOLUTION: An adhesive composition comprising: a thermoplastic resin; a filler; and a silane coupling agent having a butadiene skeleton. The adhesive film for circuit connection includes an adhesive layer formed of the adhesive composition. The connection structure includes a first circuit member having a first electrode, a second circuit member having a second electrode, and a connection part arranged 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 part contains a cured product of the adhesive film for circuit connection.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an adhesive film for circuit connection, 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, 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) is used for the surface electrodes. On the other hand, organic LEDs mainly use flexible plastic substrates such as polyimide substrates as their substrates, and Ti is used as the circuit material formed on the plastic substrates. Patent Document 1 investigates a circuit connection material that can provide sufficient adhesive strength when connecting circuit components having substrates made of polyimide resin or the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-318990 Summary of the Invention [Problem to be solved by the invention]

[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] Furthermore, in recent years, there has been an increase in wearable devices (devices worn on the body) and display devices (smartphones, tablets, smartwatches, etc.) with high durability as an added value. Circuit connection materials for components of these devices are required to have excellent connection reliability even when structures obtained using the circuit connection materials are exposed to saltwater, assuming sweat and saltwater such as seawater. In other words, such circuit connection materials are required to have excellent saltwater resistance (resistance to saltwater).

[0007] Methods for evaluating saltwater resistance (resistance to saltwater) include JIS Z 2371 (2000 Salt Spray Test Method); ISO 9227 (2006 Corrosion tests in artificial atmospheres - Salt spray tests); a method of immersing in 5% saltwater; and a method of immersing in saltwater and then placing in a constant temperature and humidity chamber. As a result of verification by the present inventors, it was found that when the above-mentioned saltwater resistance tests were conducted on connection structures obtained by connection with an adhesive composition, peeling was likely to occur at the connection.

[0008] Therefore, an object of the present invention is to provide an adhesive composition that can improve connection appearance and reduce connection resistance under salt spray conditions. Another object of the present invention is 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. [Means for solving the problem]

[0009] The present invention includes, for example, the following [1] to

[10] . [1] An adhesive composition comprising a thermoplastic resin, a filler, and a silane coupling agent having a butadiene skeleton. [2] The adhesive composition according to [1], wherein the thermoplastic resin is a polyester urethane resin. [3] The adhesive composition according to [1] or [2], wherein the mass ratio of the thermoplastic resin to the filler is 1.5 or more. [4] The adhesive composition according to any one of [1] to [3], wherein the silane coupling agent has an acid anhydride group. [5] The adhesive composition according to any one of [1] to [4], further comprising a radically polymerizable compound. [6] The adhesive composition according to any one of [1] to [5], further comprising conductive particles. [7] An adhesive film for circuit connection, comprising an adhesive layer formed from the adhesive composition according to any one of [1] to [6]. [8] 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 [6]. [9] 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 [8].

[10] A method for manufacturing a connection structure, comprising the steps of: interposing an adhesive film for circuit connection described in [8] 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]

[0010] The present invention can provide an adhesive composition that can improve connection appearance and reduce connection resistance under salt spray conditions. The present invention also can 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. [Brief explanation of the drawings]

[0011] [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

[0012] 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.

[0013] 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.

[0014] <Adhesive composition> The adhesive composition of this embodiment contains a thermoplastic resin, a filler, and a silane coupling agent having a butadiene skeleton. By containing a thermoplastic resin, a filler, and a silane coupling agent having a butadiene skeleton, the adhesive composition can improve the connection appearance and reduce the connection resistance under salt spray conditions. The inventors speculate that the reason for this is as follows.

[0015] That is, the inventors have found through their investigations that the inclusion of a silane coupling agent having a butadiene skeleton in the adhesive composition improves the water resistance and saltwater resistance at the adhesive interface between the adhesive composition and the adherend, thereby making it possible to suppress peeling that occurs at the interface between the adhesive composition and the adherend under high temperature and high humidity conditions and salt water spray conditions, and making it easier to maintain low connection resistance.

[0016] [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.

[0017] 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 salt spray conditions and further reducing the connection resistance under high temperature and high humidity conditions and salt spray conditions.

[0018] The polyester urethane resin is composed of monomer components of a dicarboxylic acid monomer, a diol monomer, and an isocyanate monomer, from the viewpoint of further improving the connection appearance under high temperature, high humidity conditions and salt spray conditions, and further reducing the connection resistance under high temperature, high humidity conditions and salt spray conditions.

[0019] 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 salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions.

[0020] 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 salt spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions; and from the same viewpoint, it may be 60 mol% or less, 50 mol% or less, or 40 mol% or less.

[0021] 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, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions.

[0022] 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 viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions, or from the same viewpoint, may be 75 mol% or less, 65 mol% or less, or 55 mol% or less.

[0023] 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, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions.

[0024] 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 salt spray conditions, and further reducing the connection resistance under high temperature, high humidity conditions and salt spray conditions, and from the same viewpoint, may be 20 mol% or less, 15 mol% or less, or 10 mol% or less.

[0025] 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 6The 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.

[0026] 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, or 100°C or higher, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray 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, or 110°C or lower, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions.

[0027] In this specification, the thermoplastic resin having a radically polymerizable functional group is blended as a radically polymerizable compound, which will be described later.

[0028] 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 salt spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray 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.

[0029] From the viewpoint of further improving the connection appearance under high temperature, high humidity conditions and salt spray conditions and further reducing the connection resistance under high temperature, high humidity conditions and salt spray 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 polyester urethane resin) based on the total mass of the thermoplastic resin contained in the adhesive composition.

[0030] 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 salt spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray 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.

[0031] 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 essentially 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, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions.

[0032] 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 salt-spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt-spray conditions; and from the same viewpoint, may be 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0033] 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, or 1.9 or more, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt water spray conditions, and from the similar viewpoint, it may be 5 or less, 4 or less, 3 or less, or 2.5 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, high-humidity conditions and salt water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt water spray conditions. The mass ratio of the thermoplastic resin having a glass transition temperature of 50°C or higher to the filler (mass-based content of thermoplastic resin having a glass transition temperature of 50°C or higher / 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, high-humidity conditions and salt-water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt-water spray conditions.

[0034] [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, and may be an inorganic filler from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt-water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt-water spray conditions.

[0035] Examples of inorganic fillers include metal oxide particles such as silica particles, alumina particles, silica-alumina particles, titania particles, and s-alconia particles; metal nitride particles, etc. The inorganic filler may be silica particles, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions.

[0036] Examples of organic fillers include silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, and polyimide particles.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The average particle size of the filler may be 1 nm or more, 5 nm or more, or 10 nm or more, or may be 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 salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions. The average particle size of the filler is the volume-based average particle size, and can be calculated by observing 100 target fillers with a scanning electron microscope (SEM) and measuring the particle sizes, and can be measured using a particle size analyzer (for example, a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd.).

[0046] 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, high-humidity conditions and salt spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray 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.

[0047] [Silane coupling agents with butadiene skeleton] The adhesive composition contains a silane coupling agent having a butadiene skeleton (hereinafter, this silane coupling agent will also be referred to as "silane coupling agent A"). By containing silane coupling agent A, the adhesive composition can improve the connection appearance under high-temperature, high-humidity conditions and salt water spray conditions, and can reduce the connection resistance under high-temperature, high-humidity conditions and salt water spray conditions.

[0048] Silane coupling agent A has a butadiene skeleton and therefore has a structure represented by the following formula (1A). [ka]

[0049] The silane coupling agent A may have a structure represented by the following formula (2A), from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt-water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt-water spray conditions. [ka] [In formula (2A), R represents a methyl group or an ethyl group.]

[0050] Silane coupling agent A may have an acid anhydride group from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions. When silane coupling agent A has an acid anhydride group, adhesion is improved, so that the connection appearance is excellent and low connection resistance can be easily maintained.

[0051] When the silane coupling agent A has an acid anhydride group, the silane coupling agent A may have a structure represented by the following formula (3A), from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt-water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt-water spray conditions. [ka]

[0052] The content of silane coupling agent A 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 adhesive composition, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions; from the same viewpoint, it may be 20% by mass or less, 15% by mass or less, or 10% by mass or less. The content of silane coupling agent A may be 2% by mass or more, 3% by mass or more, or 3.5% by mass or more, from the viewpoint of further improving the connection appearance under salt spray conditions and further reducing the connection resistance under salt spray conditions; from the same viewpoint, it may be 8% by mass or less, 6% by mass or less, or 4% by mass or less.

[0053] The mass ratio of silane coupling agent A to thermoplastic resin (mass content of silane coupling agent A / mass content of thermoplastic resin) may be 0.005 or more, 0.01 or more, or 0.05 or more from the viewpoint of further improving the connection appearance under high temperature, high humidity conditions and salt spray conditions and further reducing the connection resistance under high temperature, high humidity conditions and salt spray conditions, and from the same viewpoint, it may be 0.5 or less, 0.3 or less, or 0.2 or less. The mass ratio of silane coupling agent A to thermoplastic resin may be 0.08 or more, 0.1 or more, or 0.12 or more from the viewpoint of further improving the connection appearance under salt spray conditions and further reducing the connection resistance under salt spray conditions, and from the same viewpoint, it may be 0.18 or less, 0.15 or less, or 0.13 or less.

[0054] The mass ratio of silane coupling agent A to the filler (mass content of silane coupling agent A / mass content of filler) may be 0.01 or more, 0.05 or more, or 0.1 or more from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions, and from the similar viewpoint, may be 0.8 or less, 0.6 or less, or 0.5 or less. The mass ratio of silane coupling agent A to the filler may be 0.15 or more, 0.2 or more, or 0.25 or more from the viewpoint of further improving the connection appearance under salt spray conditions and further reducing the connection resistance under salt spray conditions, and from the similar viewpoint, may be 0.4 or less, 0.3 or less, or 0.25 or less.

[0055] [Radical polymerizable compounds] The adhesive composition may further contain a radically polymerizable compound from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions. 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 oligomer, or a combination of a monomer and an oligomer may be used.

[0056] 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 salt spray conditions and further reducing the connection resistance under high temperature and high humidity conditions and salt spray 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.

[0057] 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 salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray 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 salt spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt spray conditions, and from the same viewpoint, may be 90% by mass or less, or 80% by mass or less.

[0058] (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 6The 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.

[0059] 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.]

[0060] 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.

[0061] 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, from the viewpoint of further improving the connection appearance under high-temperature, high-humidity conditions and salt-water spray conditions and further reducing the connection resistance under high-temperature, high-humidity conditions and salt-water spray conditions.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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, high-humidity conditions and salt water spray conditions, and further reducing the connection resistance under high-temperature, high-humidity conditions and salt water spray conditions; and from the same viewpoint, it may be 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0068] [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.

[0069] Examples of the radical polymerization initiator include diacyl peroxides, peroxydicarbonates, peroxyesters, peroxyketals, dialkyl peroxides, and hydroperoxides.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] Examples of hydroperoxides include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

[0076] 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.

[0077] From the viewpoint of pot life, the content of the radical polymerization initiator may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, and may be 10% by mass or less, 5% by mass or less, or 3% by mass or less, based on the total mass of the adhesive composition.

[0078] [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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] [Other ingredients] The adhesive composition may further contain other components in addition to the components described above, such as a coupling agent (excluding silane coupling agents having a butadiene skeleton), a softener, an accelerator, an antioxidant, a colorant, a flame retardant, a thixotropic agent, a polymerization inhibitor, etc.

[0085] 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 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.

[0086] The storage modulus at 100°C of the cured product of the adhesive composition is set to 6.0 × 10 from the viewpoint of further improving the connection appearance under high temperature and high humidity conditions and salt spray conditions and further reducing the connection resistance under high temperature and high humidity conditions and salt spray conditions. 7 Pa or higher, 7.0×10 7 Pa or higher, 8.0×10 7 Pa or higher, 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, or 1.5 x 10 8 It may be less than Pa.

[0087] The storage modulus at 100°C of the cured adhesive composition can be measured by preparing multiple adhesive films from the adhesive composition, laminating the adhesive films so that the adhesive layer is 200 μm thick, and heating them in an oven at 180°C for 1 hour to produce a cured film for evaluation.The cured film can then be 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 adhesive composition.

[0088] 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.

[0089] 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.

[0090] <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 invention 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 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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 grinder, a three-roll mill, a ball mill, a bead mill, or a homodisper.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] <Circuit connection structure and method for manufacturing the same> Next, the circuit connection structure and the method for manufacturing the same will be described.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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]

[0116] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0117] <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.

[0118] <Method for preparing 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. <Synthesis of polyester urethane resin A> 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 A was obtained according to the preparation method described above in <Preparation method for polyesterurethane resin>. The weight average molecular weight of polyesterurethane resin A was measured by gel permeation chromatography and found to be 27,000.

[0119] 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 analyzer under conditions of a tensile load of 5 gf and a frequency of 10 Hz. The glass transition temperature of polyesterurethane resin A was determined to be 105°C as the temperature at which 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).

[0120] <Synthesis of polyester urethane resin B> Polyesterurethane Resin B was synthesized according to the above procedure 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 a molar ratio of isophthalic acid / terephthalic acid / adipic acid / ethylene glycol / neopentyl glycol / 1,6-hexanediol / 4,4'-diphenylmethane diisocyanate of 0.21 / 0.21 / 0.58 / 0.19 / 0.55 / 0.46 / 0.30. The weight-average molecular weight of Polyesterurethane Resin B was measured by gel permeation chromatography to be 60,000. The glass transition temperature of Polyesterurethane Resin B was measured in the same manner as for Polyesterurethane Resin A to be -3°C.

[0121] <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 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) Equipment: Tosoh GPC-8020 Detector: Tosoh Corporation RI-8020 Column: Hitachi High-Tech Gelpack GLA160S + GLA150S Sample concentration: 120mg / 3mL Solvent: tetrahydrofuran Injection volume: 60μL Pressure: 2.94 x 10 6 Pa (30 kgf / cm 2 ) Flow rate: 1.00mL / min

[0122] <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 (polyester urethane resin A synthesized above) A2: Polyester urethane resin (polyester urethane resin B synthesized above) A3: Bisphenol A phenoxy resin (product name: PKHC, manufactured by Union Carbide) (B) Radical polymerizable compound B1: Polyurethane acrylate (UA1) B2: Isocyanuric acid EO-modified diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.) B3: Dicyclopentadiene 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 Agent 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 with a butadiene skeleton (product 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) D2: Silica particles (product name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm) (E) Conductive particles E1: Conductive particles prepared as above (F) Radical polymerization initiator F1: Benzoyl peroxide (product name: Niper BMT-K40, manufactured by NOF Corporation)

[0123] 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.

[0124] <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 (atmosphere) at 180°C for 1 minute to obtain a post-heated sample. The DSC calorific value of each of the pre-heated and post-heated samples was measured using a differential scanning calorimetry (DSC) device (product name DSC7, manufactured by Perkin-Elmer) in a nitrogen stream at a temperature range of 30°C to 250°C and a heating rate of 10°C / min. Based on the measured DSC calorific value, the reaction rate after heating at 180°C for 1 minute was calculated using the following formula: Reaction rate = (Cx - Cy) x 100 / Cx [In the formula, Cx represents the DSC calorific value (J / g) of the sample before heating, and Cy represents the DSC calorific value (J / g) of the sample after heating.]

[0125] <Measurement of storage modulus at 100℃> 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 prepare 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 apparatus (manufactured by TA Instruments Japan, product name: RSA-3), and the storage modulus at 100° C. of the cured adhesive composition was measured.

[0126] A 25 μm pitch COF (manufactured by FLEXSEED) as the first circuit member and a glass substrate (manufactured by Geomatec) 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 pressurizing 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 produce a circuit connection structure (connection structure).

[0127] <Evaluation of connection resistance> The connection resistance between the opposing electrodes of the connection structures prepared above was measured using a four-probe measurement method initially (immediately after preparation), after a salt spray test, and after a high-temperature, high-humidity test. Specifically, the connection resistance between the opposing electrodes was measured at 16 locations using a multimeter (product name: MLR21, manufactured by Kusumoto Chemicals Co., Ltd.), and the average value was calculated. The salt spray test was performed in accordance with JIS Z 2371 by spraying salt water onto the connection structure using a salt spray tester (manufactured by Suga Test Instruments Co., Ltd.) and storing the connection structure in a constant-temperature, constant-humidity chamber at a temperature of 35°C and a humidity of 5% RH for 50 hours. 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.

[0128] <Appearance evaluation> The appearance of the connection points of the connection structures prepared above was observed using an optical microscope initially (immediately after preparation), after the salt spray test, 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 salt spray test was conducted in accordance with JIS Z 2371, by spraying salt water onto the connection structure using a salt spray tester (manufactured by Suga Test Instruments Co., Ltd.), and storing it in a constant temperature, constant humidity chamber at a temperature of 35°C and a humidity of 5% RH for 50 hours. The high-temperature, high-humidity test was conducted 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. [After salt spray test] 1: The ratio of the peeled area to the total area of ​​the space is 15% or less. 2: The ratio of the area where peeling has occurred to the total area of ​​the space portion is more than 15% and 30% or less. 3: The ratio of the area where peeling has occurred to the total area of ​​the space portion is more than 30% and 45% or less. 4: The ratio of the area where peeling has occurred to the total area of ​​the space portion is more than 45% and 60% or less. 5: The ratio of the area where peeling has occurred to the total area of ​​the space portion is more than 60% but not more than 75%. 6: The ratio of the area where peeling occurred to the total area of ​​the space portion is more than 75%. [After high temperature and humidity test] A: The ratio of the peeled area to the total area of ​​the space is 25% or less. B: The ratio of the area where peeling occurred to the total area of ​​the space portion is more than 25% and 50% or less. C: The ratio of the area where peeling occurred to the total area of ​​the space portion is more than 50% but not more than 75%. D: The ratio of the area where peeling occurred to the total area of ​​the space portion is more than 75%.

[0129] [Table 1]

[0130] [Table 2] [Explanation of symbols]

[0131] 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, a filler, and a silane coupling agent having a butadiene skeleton.

2. The adhesive composition according to claim 1 , wherein the thermoplastic resin is a polyester urethane resin.

3. The adhesive composition according to claim 1 , wherein a mass ratio of the thermoplastic resin to the filler is 1.5 or more.

4. The adhesive composition according to claim 1 , wherein the silane coupling agent has an acid anhydride group.

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

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

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

8. 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 6.

9. 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 8 .

10. 10. A method for producing a connection structure, comprising the steps of: interposing the adhesive film for circuit connection according to claim 8 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.

Images