Adhesive composition, adhesive film, connecting structure, and method for manufacturing the same

Abstract

An adhesive composition containing a compound which includes an aromatic heterocycle and a side-chain group bonded to the aromatic heterocycle and including at least one chain selected from the group consisting of alkyl chains having three or more carbon atoms and alkylene chains having three or more carbon atoms.

Description

Technical Field

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

Background Art

[0002] In recent years, miniaturization, thinning, and high performance of electronic components have been progressing, and the development of economic high-density mounting technologies has been actively carried out. It is difficult to connect an electronic component having fine circuit electrodes to a circuit member using conventional solder and rubber connectors. Therefore, a connection method using an anisotropic conductive adhesive composition and its film (adhesive film) having excellent resolution, as disclosed in Patent Documents 1 to 6, is frequently used. For example, when connecting glass of a liquid crystal display (Liquid Cristal Display) to a circuit member such as a TAB (Tape Automated Bonding) or FPC (Flexible Print Circuit), a method of sandwiching an anisotropic conductive adhesive film containing conductive particles between opposing electrodes and heating and pressing is known. In this method, it is possible to electrically connect the electrodes of both substrates while maintaining the insulation between adjacent electrodes on the same substrate. In this method, an electronic component having fine circuit electrodes and a circuit member are fixed by an anisotropic conductive adhesive film.

[0003] Since the above connection method is advantageous for weight reduction, thinning, and high sensitivity of modules, it is applied to display modules such as liquid crystal display devices and electronic papers, sensor substrates such as touch panels, and the like. For the circuit electrodes formed on these substrates, metal materials containing Ag (silver), Cu (copper), Au (gold), Al (aluminum), etc. (for example, these metal single substances or alloys, etc.) are used for the purpose of reducing wiring resistance. In recent years, metal materials containing Cu and Ag have come to be used for forming circuit electrodes from the viewpoints of price, low surface resistance, simplicity of processing, etc.

[0004] When an anisotropically conductive adhesive composition is used to connect electrodes made of metallic materials containing Cu and Ag, the vicinity of the electrode connection is exposed to the atmosphere, making the electrodes susceptible to oxidation and moisture absorption. In particular, when solid copper is used for the electrodes, surface oxidation may cause a decrease in adhesive strength and an increase in circuit resistance, and moisture absorption may cause the electrodes to corrode. Compounds containing aromatic heterocycles, such as benzotriazole, are known as effective rust inhibitors for such metallic materials containing Cu and Ag (for example, Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 08-148213 [Patent Document 2] Japanese Patent Application Publication No. 08-124613 [Patent Document 3] Japanese Patent Application Publication No. 11-50032 [Patent Document 4] Japanese Patent Publication No. 2011-91044 [Patent Document 5] Japanese Patent Publication No. 2011-100605 [Patent Document 6] Japanese Patent Publication No. 2013-55058 [Non-patent literature]

[0006] [Non-Patent Document 1] Tetsu Nakagawa, Genzo Hashizume, "Effects of water-soluble organic sulfides on the rust-preventive action of benzotriazole," Journal of Corrosion Protection Technology, Vol. 16, No. 1 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, with the increasing resolution and narrowing of bezels of modules, the connection area of ​​connecting structures has been decreasing. However, stable connectivity is required regardless of the connection area. Therefore, adhesive compositions require excellent adhesive properties. However, when an adhesive composition contains compounds including the above-mentioned aromatic heterocycles, the adhesive strength of the adhesive composition may decrease.

[0008] Therefore, one of the objectives of this disclosure is to provide an adhesive composition that contains compounds including aromatic heterocycles while exhibiting excellent adhesive strength. [Means for solving the problem]

[0009] One aspect of this disclosure relates to the adhesive compositions described below.

[0010] [1] An adhesive composition comprising a compound comprising an aromatic heterocycle and a side chain group bonded to the aromatic heterocycle and comprising at least one selected from the group consisting of an alkyl chain having 3 or more carbon atoms and an alkylene chain having 3 or more carbon atoms.

[0011] [2] The adhesive composition according to [1], wherein the aromatic heterocycle comprises a nitrogen atom as a heteroatom.

[0012] [3] The adhesive composition according to [1] or [2], wherein the side chain group comprises two or more alkyl chains having 3 or more carbon atoms.

[0013] [4] The adhesive composition according to any one of [1] to [3], further containing conductive particles.

[0014] [5] The adhesive composition according to any one of [1] to [4], wherein when the total amount of nonvolatile components other than conductive particles in the adhesive composition is 100 parts by mass, the content of the compound is 0.01 to 10 parts by mass.

[0015] [6] An adhesive composition according to any one of [1] to [5], used for connecting circuit components together.

[0016] Another aspect of the present disclosure relates to an adhesive film comprising a layer made of the adhesive composition according to any one of [1] to [6].

[0017] In one aspect, the adhesive film may have a multilayer structure of two or more layers. In this case, at least one outermost layer of the layers constituting the multilayer structure may be a layer made of the adhesive composition. At least one of the layers constituting the multilayer structure may be a layer containing conductive particles.

[0018] Another aspect of the present disclosure relates to a connection structure comprising a first circuit member having a first electrode, a second circuit member having a second electrode, and a circuit connection member 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 circuit connection member contains a cured product of the adhesive composition according to any one of [1] to [6].

[0019] In one aspect, one or both of the first electrode and the second electrode may be formed of a metal material containing at least one selected from the group consisting of Cu and Ag.

[0020] Another aspect of the present disclosure relates to a method for manufacturing a connection structure, comprising the steps of preparing a first circuit member having a first electrode and a second circuit member having a second electrode, disposing the adhesive composition according to any one of [1] to [6] between the first circuit member and the second circuit member, and pressing the first circuit member and the second circuit member through the adhesive composition to electrically connect the first electrode and the second electrode to each other. [Advantages of the Invention]

[0021] According to the present disclosure, it is possible to provide an adhesive composition having excellent adhesive strength while not containing a compound containing an aromatic heterocyclic ring. [Brief Description of the Drawings]

[0022] [Figure 1]Figure 1 is a schematic cross-sectional view showing an adhesive film (single-layer structure) according to one embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing an adhesive film (two-layer structure) according to one embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing an adhesive film (three-layer structure) according to one embodiment. [Figure 4] Figures 4(a) and 4(b) are schematic cross-sectional views showing a method for manufacturing a connecting structure according to one embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing a copper electrode film attached to a body made using the adhesive film (single-layer structure) of the example. [Figure 6] Figure 6 is a schematic cross-sectional view showing a copper electrode film attached to a body fabricated using the adhesive film (two-layer structure) of the example. [Figure 7] Figure 7 is a schematic cross-sectional view showing a copper electrode film attached to a body made using the adhesive film (three-layer structure) of the example. [Figure 8] Figure 8 is a schematic cross-sectional view showing a copper electrode film attached to a body prepared using the adhesive film of the comparative example. [Modes for carrying out the invention]

[0023] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings, where applicable. However, the present disclosure is not limited in any way to the embodiments described below. In this specification, numerical ranges indicated using "~" indicate a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. Furthermore, the upper and lower limits described individually can be combined in any way.

[0024] <Adhesive composition> An adhesive composition according to one embodiment contains an adhesive component and conductive particles dispersed in the adhesive component.

[0025] (Conductive particles) The conductive particles are not particularly limited as long as they are conductive particles, and may include metal particles composed of metals such as Au, Ag, Ni, Cu, Pd, and solder, or conductive carbon particles composed of conductive carbon.

[0026] The conductive particles may be coated conductive particles comprising a core containing non-conductive glass, ceramic, or plastic (such as polystyrene), and a coating layer containing the above-mentioned metal or conductive carbon that covers the core. The conductive particles may also be metal particles formed from a heat-meltable metal, or coated conductive particles comprising a core containing plastic and a coating layer containing metal or conductive carbon that covers the core.

[0027] In one embodiment, the conductive particles include a core made of polymer particles (plastic particles) such as polystyrene, and a metal layer covering the core. The polymer particles may have substantially their entire surface covered by the metal layer. To the extent that their function as a circuit connection material is maintained, a portion of the surface of the polymer particles may be exposed without being covered by the metal layer. The polymer particles may also include particles containing a polymer, for example, which contains at least one monomer selected from the group consisting of styrene and divinylbenzene as a monomer unit.

[0028] The average particle size of the polymer particles is, for example, 1 to 40 μm, and may be 1 to 30 μm from the viewpoint of high-density mounting. From the viewpoint of maintaining a more stable connection state even when there is variation in the surface uniformity of the electrodes (such as when there are irregularities on the surface of the electrodes), the average particle size of the polymer particles may be 2 to 20 μm. The average particle size of the polymer particles may be 1 μm or more, 2 μm or more, and may be 40 μm or less, 30 μm or less, or 20 μm or less.

[0029] The metal layer may be formed from various metals such as Ni, Ni / Au, Ni / Pd, Cu, NiB, Ag, and Ru. The metal layer may be an alloy layer made of an alloy of Ni and Au, an alloy of Ni and Pd, etc. The metal layer may be a multilayer structure consisting of multiple metal layers. For example, the metal layer may consist of a Ni layer and an Au layer. The thickness of the metal layer may be 10 nm or more, 20 nm or more, 500 nm or less, 300 nm or less, 10 to 500 nm, or 20 to 300 nm. The metal layer may be made by plating, vapor deposition, sputtering, etc. The metal layer may be a thin film (for example, a thin film formed by plating, vapor deposition, sputtering, etc.).

[0030] From the viewpoint of improving insulation properties, conductive particles may have an insulating layer. Specifically, for example, in the conductive particles of the above embodiment, which include a core (e.g., polymer particles) and a coating layer such as a metal layer covering the core, an insulating layer covering the coating layer may be provided on the outside of the coating layer. The insulating layer may be a surface layer located on the outermost surface of the conductive particles. The insulating layer may be a layer formed from an insulating material such as silica or acrylic resin.

[0031] The average particle size of conductive particles may be 1.0 μm or larger, 2.0 μm or larger, or 2.5 μm or larger, from the viewpoint of excellent dispersibility and conductivity. The average particle size of conductive particles may be 50 μm or smaller, 30 μm or smaller, or 20 μm or smaller, from the viewpoint of excellent dispersibility and conductivity. From the above viewpoint, the average particle size of conductive particles may be between 1.0 and 50 μm, between 2.0 and 30 μm, or between 2.5 and 20 μm.

[0032] The maximum particle size of conductive particles is preferably 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 conductive particles may be 1.0 μm or larger, 2.0 μm or larger, or 2.5 μm or larger. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of conductive particles may be 50 μm or smaller, 30 μm or smaller, or 20 μm or smaller. From the above viewpoint, the maximum particle size of conductive particles may be between 1.0 and 50 μm, 2.0 and 30 μm, or 2.5 and 20 μm.

[0033] In this specification, the particle size of any 300 particles (pcs) is measured by observation using a scanning electron microscope (SEM). The average value of the obtained particle sizes is defined as the average particle size, and the largest value obtained is defined as the maximum particle size. If the particle has protrusions or other non-spherical shapes, the particle size is defined as the diameter of the circle circumscribing the particle in the SEM image.

[0034] The content of conductive particles is determined according to the fineness of the electrodes to be connected. For example, the content of conductive particles may be 0.1 to 50 parts by mass per 100 parts by mass of adhesive components (i.e., when the total of nonvolatile components other than conductive particles in the adhesive composition is 100 parts by mass). From the viewpoint of insulation and manufacturing cost, the content of conductive particles may be 0.1 to 30 parts by mass per 100 parts by mass of adhesive components. The content of conductive particles may be 0.1 parts by mass or more, and may be 50 parts by mass or less, or 30 parts by mass or less, per 100 parts by mass of adhesive components.

[0035] (Adhesive component) Adhesive components are defined as non-volatile components in the adhesive composition other than conductive particles. Non-volatile components are components whose amount of volatilization when heated at 70°C for 10 minutes is 20% by mass or less of the total. For example, if the adhesive composition contains an organic solvent as described later, the components other than the organic solvent among the components other than conductive particles in the adhesive composition are called non-volatile components. Adhesive components are, for example, made of insulating materials and have insulating properties as a whole. Adhesive components include at least a compound (hereinafter also referred to as "aromatic heterocyclic compound A") comprising an aromatic heterocycle and a side chain group bonded to the aromatic heterocycle and containing at least one selected from the group consisting of alkyl chains having 3 or more carbon atoms (hereinafter also referred to as "long-chain alkyl") and alkylene chains having 3 or more carbon atoms (hereinafter also referred to as "long-chain alkylene"). In this specification, alkyl chain means a monovalent aliphatic saturated hydrocarbon chain, and alkylene chain means a divalent aliphatic saturated hydrocarbon chain.

[0036] In one embodiment, the adhesive component contains a curable component that hardens by heat or light, and an aromatic heterocyclic compound A. The curable component includes, for example, a radical polymerizable compound and a free radical generator. The curable component generates a polymeric organic component by hardening with heat or light. An adhesive composition containing such an adhesive component is heat-curable or photocurable.

[0037] Radical polymerizable compounds are compounds containing functional groups that polymerize by radicals, and examples include acrylate compounds, methacrylate compounds, and maleimide compounds. The content of radical polymerizable compounds may be, for example, 30% by mass or more, 80% by mass or less, or 30-80% by mass, based on the total amount of adhesive components.

[0038] Examples of acrylate and methacrylate compounds include urethane acrylate, urethane methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dimethylol tricyclodecane diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxypolyethoxy)phenyl]propane, dicyclopentenyl acrylate, tricyclodecanyl acrylate, bis(acryloxyethyl) isocyanurate, ε-caprolactone-modified tris(acryloxyethyl) isocyanurate, and tris(acryloxyethyl) isocyanurate. Radical polymerizable compounds can be used individually or in combination of two or more of these. From the viewpoint of adhesion, the radical polymerizable compound may be urethane acrylate or urethane methacrylate.

[0039] As a radical polymerizable compound, from the viewpoint of improving heat resistance, a urethane acrylate or urethane methacrylate may be used in combination with a radical polymerizable compound that exhibits a Tg of 100°C or higher on its own when crosslinked with an organic peroxide compound. Examples of radical polymerizable compounds that exhibit a Tg of 100°C or higher on their own when crosslinked with an organic peroxide compound include compounds containing a dicyclopentenyl group and / or a tricyclodecanyl group. From the viewpoint of obtaining a significant improvement in heat resistance, the radical polymerizable compound may be a compound containing a tricyclodecanyl group.

[0040] The viscosity of a radical polymerizable compound at 25°C is, for example, 100,000 to 1,000,000 mPa·s, and may also be between 100,000 and 500,000 mPa·s. The viscosity of a radical polymerizable compound at 25°C may be 100,000 mPa·s or higher, and may be 1,000,000 mPa·s or lower, or 500,000 mPa·s or lower. The viscosity of a radical polymerizable compound at 25°C can be measured using a commercially available E-type viscometer.

[0041] The free radical generator is a compound that decomposes upon heat or light to generate free radicals, such as a peroxide compound or an azo compound. The free radical generator is appropriately selected depending on the desired connection temperature, connection time, pot life, etc. The free radical generator may be one or more compounds selected from the group consisting of benzoyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, and hydroperoxide. From the viewpoint of high reactivity and pot life, the free radical generator may be an organic peroxide compound with a half-life of 10 hours at a temperature of 40°C or higher and a half-life of 1 minute at a temperature of 180°C or lower.

[0042] The content of the free radical generator may be 0.05% by mass or more, 15% by mass or less, or 0.05 to 15% by mass, based on the total amount of adhesive components. When the adhesive components contain a free radical generator, the free radical generator may be used in combination with decomposition accelerators, inhibitors, etc.

[0043] The adhesive component of this embodiment may further contain a polymerization inhibitor. The polymerization inhibitor may be a hydroquinone compound, a methyl ether hydroquinone compound, or the like. The content of the polymerization inhibitor may be 0.05% by mass or more, 5% by mass or less, or 0.05 to 5% by mass, based on the total amount of the adhesive component.

[0044] Aromatic heterocyclic compound A is an organic compound that contains an aromatic heterocyclic ring and a side chain group attached to the aromatic heterocyclic ring.

[0045] An aromatic heterocycle is defined as an aromatic ring containing one or more heteroatoms within the ring, and is composed of carbon atoms and heteroatoms. Examples of heteroatoms include nitrogen atoms, sulfur atoms, and oxygen atoms. In an aromatic heterocycle, the heteroatoms act as Lewis bases on the metal surface constituting the electrode, becoming ligands. When aromatic heterocycle compound A is used, oxidation of the electrode surface is suppressed due to the above coordination action, thereby suppressing the increase in connection resistance and improving connection reliability. From the viewpoint of strong Lewis base properties and further improving connection reliability, the heteroatoms may contain nitrogen atoms, sulfur atoms, or oxygen atoms. Among these, when the heteroatom contains a nitrogen atom, a particularly significant improvement in connection reliability tends to be obtained. In other words, from the viewpoint of significantly improving connection reliability, the aromatic heterocycle may be a nitrogen-containing aromatic heterocycle.

[0046] The number of heteroatoms in an aromatic heterocycle may be one or more, two or more, four or less, one to four, or two to four. An aromatic heterocycle may contain multiple heteroatoms of one type, or multiple heteroatoms of different types. For example, an aromatic heterocycle may contain a nitrogen atom and an oxygen atom, a nitrogen atom and a sulfur atom, or a nitrogen atom, an oxygen atom, and a sulfur atom. If there is one nitrogen atom in the aromatic heterocycle, the aromatic heterocycle may further contain other atoms (such as sulfur atoms and oxygen atoms) in addition to carbon atoms and nitrogen atoms.

[0047] The aromatic heterocycle is, for example, a five-membered ring or a six-membered ring. From the viewpoint of the effects of this disclosure, the aromatic heterocycle may be a five-membered ring. Examples of five-membered rings include pyrazole rings, imidazole rings, triazole rings, tetrazole rings, thiazole rings, thiadiazole rings, oxazole rings, pyrrole rings, furan rings, and thiophene rings. Examples of six-membered rings include pyrimidine rings, pyridine rings, pyridazine rings, pyrazine rings, and triazine rings.

[0048] From the viewpoint of suppressing the increase in connection resistance and further improving connection reliability, the aromatic heterocycle may be a pyrazole ring, imidazole ring, triazole ring, tetraazole ring, thiazole ring, thiadiazole ring, oxazole ring, or pyrimidine ring. Among these, the improvement in connection reliability tends to be particularly pronounced when the aromatic heterocycle is a pyrazole ring, imidazole ring, triazole ring, tetraazole ring, thiazole ring, thiadiazole ring, or oxazole ring. Among these, the improvement in connection reliability tends to be even more pronounced when the aromatic heterocycle is a triazole ring, tetraazole ring, or thiadiazole ring.

[0049] The aromatic heterocyclic compound A may contain one or more aromatic heterocyclic rings. If aromatic heterocyclic compound A contains multiple aromatic heterocyclic rings, the multiple aromatic heterocyclic rings may be identical or different from each other. The aromatic heterocyclic rings may be fused with other rings or not. That is, aromatic heterocyclic compound A may contain a monoring made up of aromatic heterocyclic rings, or it may contain a fused ring containing aromatic heterocyclic rings. The other rings may be aromatic heterocyclic rings or aromatic carbocyclic rings. That is, aromatic heterocyclic compound A may have rings other than aromatic heterocyclic rings, or it may not have rings other than aromatic heterocyclic rings. From the viewpoint of the effects of this disclosure, the other rings may be aromatic carbocyclic rings.

[0050] An aromatic carbocyclic ring is an aromatic ring composed only of carbon and hydrogen atoms, and does not contain any heteroatoms. An example of an aromatic carbocyclic ring is the benzene ring. Examples of fused rings containing aromatic carbocyclic rings and aromatic heterocyclic rings include the benzimidazole ring, benzotriazole ring, benzothiazole ring, and benzoxazole ring.

[0051] The side chain group may be directly bonded to the aromatic heterocycle. That is, the side chain group may be a substituent that substitutes a hydrogen atom bonded to a carbon atom or heteroatom constituting the aromatic heterocycle. The side chain group may be indirectly bonded to the aromatic heterocycle by directly bonding to a ring other than the aromatic heterocycle (e.g., an aromatic carbocyclic ring) in a fused ring containing the aromatic heterocycle. That is, the side chain group may be a substituent that substitutes a hydrogen atom bonded to a carbon atom constituting the ring other than the aromatic heterocycle. From the viewpoint of the effects of this disclosure, the side chain group may be directly bonded to a heteroatom within the aromatic heterocycle. The number of side chain groups may be one or more. For example, the number of side chain groups may be three or less.

[0052] The side chain group contains long-chain alkyl and / or long-chain alkylene. The side chain group may contain multiple long-chain alkyls, multiple long-chain alkylenes, or one or more long-chain alkyls and one or more long-chain alkylenes. From the viewpoint of superior adhesive strength, the side chain group may contain two or more long-chain alkyls. That is, the side chain group may contain two or more alkyl chains having 3 or more carbon atoms. The number of long-chain alkyls is, for example, three or less or two or less.

[0053] The carbon number of long-chain alkyl and long-chain alkylene is 3 or more, and may be 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more from the viewpoint of superior adhesive strength. The carbon number of long-chain alkyl and long-chain alkylene may be 30 or less, 20 or less, 15 or less, or 10 or less from the viewpoint of suppressing the decrease in coordination ability due to increased steric hindrance. From the above viewpoint, the carbon number of long-chain alkyl and long-chain alkylene is, for example, 3 to 30. Long-chain alkyl and long-chain alkylene may be linear or branched. When the long-chain alkyl is branched, the carbon number of the main chain (the chain with the maximum number of consecutive carbons) of the long-chain alkyl may be within the above range. Similarly, when the long-chain alkylene is branched, the carbon number of the main chain (the chain with the maximum number of consecutive carbons) of the long-chain alkylene may be within the above range.

[0054] Specific examples of long-chain alkyl groups include propyl, butyl, pentyl, hexyl, heptyl, octyl, isobutyl, sec-butyl, isopentyl, neopentyl, tert-pentyl, and isohexyl. Specific examples of long-chain alkylenes include trimethylene, butylene, tetramethylene, 1-methyltrimethylene, 2-methyltrimethylene, 1,1-dimethylethylene, and 1,2-dimethylethylene.

[0055] The side chain group may contain functional groups other than long-chain alkyl and long-chain alkylene. Examples of such functional groups include amino groups, silyl groups (alkoxysilyl groups, alkylsilyl groups, etc.), hydroxyl groups, ester groups, and mercapto groups. The side chain group may contain alkoxysilyl groups from the viewpoint of superior adhesive strength. Examples of alkoxysilyl groups include methoxysilyl groups, dimethoxysilyl groups, trimethoxysilyl groups, ethoxysilyl groups, diethoxysilyl groups, triethoxysilyl groups, propyroxysilyl groups, butoxysilyl groups, and isopropyloxysilyl groups. The above functional groups may be substituents that substitute hydrogen atoms bonded to carbon atoms of long-chain alkyl and long-chain alkylene. The number of above functional groups contained in the side chain group may be one or two or more. The type of above functional group contained in the side chain group may be one or two or more.

[0056] If the side chain group contains an alkoxysilyl group, the radical polymerizable compound may contain a functional group that reacts with and bonds to the alkoxysilyl group. Examples of such functional groups include hydroxyl groups, carboxyl groups, and alkoxysilyl groups. If the radical polymerizable compound contains an alkoxysilyl group, the alkoxysilyl group may be the same as or different from the alkoxysilyl group contained in the side chain group.

[0057] The side chain group may contain a linking group for bonding the long-chain alkyl and / or long-chain alkylene to the aromatic heterocycle. If the side chain group contains a linking group, the linking group is directly bonded to the aromatic heterocycle or a fused ring containing the aromatic heterocycle. The linking group is a divalent or trivalent group (e.g., an organic group) containing a heteroatom such as a nitrogen atom, a sulfur atom, or an oxygen atom. The side chain group may not contain a linking group, and the long-chain alkyl or long-chain alkylene may be directly bonded to the aromatic heterocycle or a fused ring containing the aromatic heterocycle.

[0058] The aromatic heterocycle may be substituted with substituents other than the side chain group described above. Such substituents may be, for example, hydrocarbon groups (excluding those containing long-chain alkyl or long-chain alkylene groups), or the functional groups that can be included in the side chain group. The hydrocarbon group may be an alkyl group, etc.

[0059] The content of aromatic heterocyclic compounds may be 0.01 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more per 100 parts by mass of adhesive components (i.e., when the total of nonvolatile components other than conductive particles in the adhesive composition is 100 parts by mass), from the viewpoint of superior adhesive strength and improved connection reliability by suppressing an increase in connection resistance. The content of aromatic heterocyclic compounds may be 10 parts by mass or less, 8 parts by mass or less, 5 parts by mass or less, 2 parts by mass or less, or 1 part by mass or less, from the viewpoint of superior adhesive strength and improved connection reliability by suppressing an increase in connection resistance. From the above viewpoint, the content of aromatic heterocyclic compounds may be, for example, 0.01 to 10 parts by mass, 0.1 to 8 parts by mass, 0.2 to 5 parts by mass, 0.5 to 2 parts by mass, 0.5 to 1 part by mass, 1 to 10 parts by mass, 2 to 8 parts by mass, 3 to 8 parts by mass, 3 to 5 parts by mass, or 4 to 5 parts by mass per 100 parts by mass of adhesive component.

[0060] In another embodiment, the adhesive component includes a thermosetting resin and the aromatic heterocyclic compound described above.

[0061] Examples of thermosetting resins include epoxy resins, cyanate ester resins, maleimide resins, allylnadiimide resins, phenolic resins, urea resins, alkyd resins, acrylic resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, resorcinol formaldehyde resins, xylene resins, furan resins, polyurethane resins, ketone resins, triallyl cyanurate resins, polyisocyanate resins, resins containing tris(2-hydroxyethyl) isocyanurate, resins containing triallyl trimelitate, thermosetting resins synthesized from cyclopentadiene, and thermosetting resins obtained by trimerization of aromatic dicyanamide. These thermosetting resins may be used individually or in combination of two or more. The content of the thermosetting resin may be, for example, 20% by mass or more, 50% by mass or less, or 20-50% by mass, based on the total amount of adhesive components.

[0062] If the adhesive component contains a thermosetting resin, the adhesive component may further contain a curing agent. The curing agent may be, for example, a catalytic curing agent. The catalytic curing agent may be a hydrazide, a boron trifluoride-amine complex, a sulfonium salt, an amine imide, a diaminomaleonitrile, a polyamine salt, a dicyandiamide, or a modified version thereof. The curing agent may also be a polyaddition type curing agent such as a polyamine, a polymercaptan, a polyphenol, or an acid anhydride. A polyaddition type curing agent and a catalytic curing agent may be used in combination as the curing agent. The curing agents may be used individually or in combination of two or more. The curing agent content may be 0.5% by mass or more, 15% by mass or less, or 0.5 to 15% by mass, based on the total amount of the adhesive component.

[0063] The curing agent may be the curing agent described above, coated with a polymer compound such as polyurethane or polyester, or a thin metal film such as Ni or Cu, or an inorganic compound such as calcium silicate, and then microencapsulated. Such a curing agent allows for an extended pot life.

[0064] In another embodiment, the adhesive component contains the radical polymerizable compound, the free radical generator, the thermosetting resin, and the aromatic heterocyclic compound described above.

[0065] In this embodiment, the total content of the radical polymerizable compound and the thermosetting resin may be, for example, 50% by mass or more, 80% by mass or less, or 50-80% by mass, based on the total amount of adhesive components.

[0066] In each of the embodiments described above, the adhesive component may further contain fillers such as silicone particles, softeners, accelerators, antioxidants, colorants, flame retardants, thixotropic agents, coupling agents, etc. The fillers are, for example, non-conductive particles, and in addition to nanofillers such as silica and alumina, urethane and ester-based organic fillers can also be used. These fillers are effective not only in controlling the elastic modulus of the resin but also in controlling film formation and softening point.

[0067] The adhesive component may also contain compounds having aromatic heterocyclic rings in addition to aromatic heterocyclic compound A. Examples of such compounds include 5-methyltetrazole, 5-amino-1H-tetrazole, 3-mercapto-1,2,4-triazole, benzotriazole, 2-aminopyrimidine, 5,6-dimethylbenzimidazole, 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercaptopyrimidine, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, and 2-mercaptobenzimidazole.

[0068] In one embodiment, the adhesive composition does not need to contain conductive particles.

[0069] The adhesive composition may be in the form of a paste or a film. From the viewpoint of ease of handling, the adhesive composition may be formed in the form of a film. If the adhesive composition is in the form of a paste, it may contain a solvent such as an organic solvent. Examples of organic solvents include toluene, hexane, acetone, ethyl acetate, methyl ethyl ketone, and ethanol. If the adhesive composition is in the form of a film, it does not need to contain substantially any organic solvent. The content of organic solvent in a film-type adhesive composition is, for example, 1% by mass or less based on the total amount of the adhesive composition.

[0070] When forming an adhesive composition into a film, the adhesive component may contain an insulating resin other than the thermosetting resin mentioned above as a film-forming component to enhance film-forming properties. Examples of insulating resins include polystyrene, polyethylene, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyvinyl chloride, polyphenylene oxide, urea resin, phenoxy resin, polyimide resin, and polyester urethane resin. From the viewpoint of further improving connection reliability, the insulating resin may be a high molecular weight phenoxy resin with a weight-average molecular weight of 10,000 or more, as determined by high-performance liquid chromatography (HPLC). The adhesive component may contain these resins modified with radically polymerizable functional groups, and may also contain a mixture of these resins with a styrene-based resin or an acrylic resin for purposes such as adjusting melt viscosity. In another embodiment, the adhesive component may contain rubber to enhance film-forming properties.

[0071] The adhesive composition described above exhibits excellent adhesive strength when used as a material for connecting circuit components, particularly for electrical connections between electrodes of circuit components (circuit connection material). That is, the above adhesive composition is suitably used as a circuit connection material, and is particularly suitably used as an anisotropic conductive adhesive composition for connecting circuit components. The reason for obtaining the above effect is not clear, but it is presumed to be as follows. First, in conventional adhesive compositions containing aromatic heterocyclic compounds, the aromatic heterocyclic compound is biased towards the electrode surface side to be adhered, and the adhesion between the polymeric organic component, such as the polymer of the radical polymerizable compound produced by the curing of the adhesive composition, and the adherend is inhibited by the aromatic heterocyclic compound. In contrast, in the above adhesive composition, it is presumed that the adhesion to the adherend is improved by the interaction between the long-chain alkyl and / or long-chain alkylene contained in the aromatic heterocyclic compound and the polymeric organic component produced after curing, thus obtaining the above effect. The above effect tends to be more pronounced when one or both of the electrodes to be adhered are formed of a metallic material containing at least one selected from the group consisting of Cu and Ag.

[0072] <Adhesive film> The adhesive film comprises, for example, a layer made of the adhesive composition of the above embodiment. The adhesive film is suitably used as a circuit connection material and is particularly suitably used as an anisotropic conductive adhesive film for connecting circuit members. If the adhesive composition does not contain conductive particles, the adhesive film may have a multilayer structure and further comprise a layer containing conductive particles, as will be described later. Hereinafter, depending on the case, the adhesive composition of the above embodiment that contains conductive particles will be referred to as the adhesive composition of the first embodiment, and the adhesive composition that does not contain conductive particles will be referred to as the adhesive composition of the second embodiment.

[0073] Figure 1 is a schematic cross-sectional view showing an adhesive film according to one embodiment. As shown in Figure 1, in one embodiment, the adhesive film 1 is composed of a single layer consisting of an adhesive component 2 and conductive particles 3 dispersed in the adhesive component 2. In one embodiment, the adhesive component 2 and conductive particles 3 may be the adhesive component and conductive particles described above. The thickness of the adhesive film 1 may be, for example, 10 μm or more, 50 μm or less, or 10 to 50 μm. As shown in Figure 1, a substrate 100 (e.g., PET film) such as a resin film may be provided on the surface of the adhesive film 1. That is, in one embodiment, the adhesive film may be an adhesive film with a substrate. The adhesive film 1 can be obtained, for example, by applying a paste of the adhesive composition of the first embodiment onto the substrate 100 using a knife coater, roll coater, applicator, etc., and then reducing the organic solvent by heating.

[0074] In one embodiment, the adhesive film 1 can have a multilayer structure of two or more layers. In this case, at least one of the layers constituting the multilayer structure is the outermost layer (the outermost layer), and it is made of the adhesive composition of the above embodiment. The multilayer structure may include, for example, a layer containing conductive particles and a layer not containing conductive particles. Specifically, as shown in Figure 2, the multilayer structure may be a two-layer structure consisting of a layer containing conductive particles 3A (a layer consisting of adhesive component 2A and conductive particles 3A dispersed in adhesive component 2A) 1A and a layer not containing conductive particles (a layer consisting of adhesive component 2B) 1B. In this case, at least one layer may be made of the adhesive composition of the above embodiment (the adhesive composition of the first embodiment or the adhesive composition of the second embodiment), and both layers may be made of the adhesive composition of the above embodiment. The multilayer structure may be a three-layer structure, as shown in Figure 3, consisting of a layer containing conductive particles 3A (a layer consisting of adhesive component 2A and conductive particles 3A dispersed in adhesive component 2A) 1A, and layers 1B and 1C on either side that do not contain conductive particles (layers consisting of adhesive components 2B and 2C). In this case, at least one of the outermost layers 1B and 1C that do not contain conductive particles 3A may be made of the adhesive composition of the above embodiment (adhesive composition of the second embodiment), or both outermost layers may be made of the adhesive composition of the above embodiment (adhesive composition of the second embodiment). Alternatively, the layer 1A containing conductive particles 3A may be made of the adhesive composition of the above embodiment (adhesive composition of the first embodiment). The multilayer adhesive film may, for example, contain multiple layers 1A containing conductive particles 3A. These multilayer adhesive films are suitable for narrow-pitch connections because they allow for efficient placement of conductive particles on electrodes. The adhesive film may further have an adhesive layer that exhibits high adhesion to each circuit member to be connected, taking into consideration adhesion to the circuit members.

[0075] The multilayer structure may include, for example, a layer containing aromatic heterocyclic compound A (a layer made of the adhesive composition of the above embodiment) and a layer not containing aromatic heterocyclic compound A. The layer containing aromatic heterocyclic compound A and the layer not containing aromatic heterocyclic compound A may each be the outermost layer (exposed to the outside) of the adhesive film. Specifically, the multilayer structure may be a two-layer structure consisting of a layer containing aromatic heterocyclic compound A (a layer made of the adhesive composition of the above embodiment) and a layer not containing aromatic heterocyclic compound A. With an adhesive film having such a multilayer structure, only one of the electrodes of the connected circuit members can be selectively brought into contact with the layer containing aromatic heterocyclic compound A. For example, if only one of the electrodes of the circuit member is formed of a metallic material containing at least one selected from the group consisting of Cu and Ag, by making the outermost layer on the side in contact with the electrode a layer containing aromatic heterocyclic compound A, the adhesive film can exhibit high adhesion to each of the connected circuit members, and the circuit members can be bonded together more firmly. When the layer that does not contain aromatic heterocyclic compound A also does not contain any other aromatic heterocyclic compounds, the above effect tends to be more pronounced.

[0076] <Connection Structure> A method for manufacturing a connecting structure according to one embodiment includes the steps of: preparing a first circuit member having a first electrode and a second circuit member having a second electrode; placing the adhesive composition of the above embodiment between the first circuit member and the second circuit member; and pressing the first circuit member and the second circuit member together via the adhesive composition to electrically connect the first electrode and the second electrode. In the step of placing the adhesive composition, a paste containing the adhesive composition (adhesive paste) may be placed, or a film containing the adhesive composition (adhesive film) may be placed. A method for manufacturing a connecting structure using the above adhesive film 1 will be described below with reference to the drawings.

[0077] Figures 4(a) and 4(b) are schematic cross-sectional views showing a method for manufacturing a connection structure according to one embodiment. First, as shown in Figure 4(a), a first circuit member 6 having a first base material 4 and a first electrode 5 provided on the first base material 4, and a second circuit member 9 having a second base material 7 and a second electrode 8 provided on the second base material 7 are prepared.

[0078] Next, the first circuit member 6 and the second circuit member 9 are positioned so that the first electrode 5 and the second electrode 8 face each other, and the adhesive film 1 is placed between the first circuit member 6 and the second circuit member 9.

[0079] Next, the adhesive film 1 is cured while applying pressure to the entire surface in the directions of arrows A and B. The pressure applied during curing may be, for example, 1 to 10 MPa per total contact area. The method for curing the adhesive film 1 may be by heating, or by combining heating with light irradiation. Heating may be performed at, for example, 100 to 170°C. The pressing and heating (and light irradiation if necessary) may be performed for, for example, 1 to 160 seconds. As a result, the first circuit member 6 and the second circuit member 9 are pressed together via the cured adhesive composition constituting the adhesive film 1.

[0080] In this embodiment, the adhesive film 1 is placed between the first circuit member 6 and the second circuit member 9. However, in other embodiments, instead of the adhesive film, an adhesive paste (a paste-like adhesive composition) may be applied to the first circuit member 6 or the second circuit member 9, or to both.

[0081] As shown in Figure 4(b), the connection structure 11 obtained in this manner, according to one embodiment, comprises a first circuit member 6 having a first substrate 4 and a first electrode 5 provided on the first substrate 4, a second circuit member 9 having a second substrate 7 and a second electrode 8 provided on the second substrate 7, and a circuit connection member 10 disposed between the first circuit member 6 and the second circuit member 9, which electrically connects the first electrode 5 and the second electrode 8 to each other. The circuit connection member 10 is made of a cured product of an adhesive composition, and consists of a cured product 12 of adhesive component 2 and conductive particles 3 dispersed in the cured product 12. In the connection structure 11, the conductive particles 3 are interposed between the first electrode 5 and the second electrode 8, thereby electrically connecting the first electrode 5 and the second electrode 8 to each other.

[0082] Examples of the first substrate 4 and the second substrate 7 include a plastic substrate, a glass substrate, a glass and / or plastic substrate, and a composite substrate having a conductive film and / or insulating film provided on the substrate. The first substrate 4 and the second substrate 7 may be the same or different from each other.

[0083] A plastic substrate is, for example, an organic substrate formed from a thermoplastic resin. A specific example is an organic substrate formed from an organic material containing at least one thermoplastic resin selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), cycloolefin polymer (COP), and polyethylene naphthalate (PEN).

[0084] The plastic substrate may further have a modified treatment film, such as a hard coat, and / or a protective film formed on the surface of the organic substrate to improve its optical and mechanical properties. To facilitate the handling and transport of the flexible substrate, a reinforcing material selected from glass, SUS, etc., may be bonded to the organic substrate.

[0085] The thickness of the plastic substrate may be 10 to 200 μm, or 10 to 125 μm, in order to ensure sufficient strength and flexibility as a film on its own. The thickness of the plastic substrate may be 10 μm or more, 200 μm or less, or 125 μm or less.

[0086] When conventional circuit connection materials are used, the heating and pressurizing required to bond circuit components together can cause electrodes on the plastic substrate to break or crack. Furthermore, for electrode connections where it is difficult to form a sufficient electrical connection, it is necessary to bond the circuit components under lower temperatures or lower stress conditions to suppress electrode damage. The adhesive film 1 of this embodiment may have advantages over conventional materials in these respects as well.

[0087] The glass substrate may be made of soda glass, quartz glass, or the like. From the viewpoint of preventing damage due to external stress, the substrate made of these materials may be subjected to chemical strengthening treatment.

[0088] The composite substrate may have a glass substrate and / or a plastic substrate, and an insulating film and / or conductive film provided on the surface of the substrate, which is made of polyimide or an organic or inorganic material used for coloring. In the composite substrate, electrodes may be formed on the insulating film.

[0089] The combination of the first substrate 4 and the second substrate 7 is not particularly limited, but for example, the first substrate 4 may be a plastic substrate and the second substrate 7 may be a plastic substrate, or the first substrate 4 may be a plastic substrate and the second substrate 7 may be a glass substrate or a composite substrate. When the first substrate 4 and the second substrate 7 are plastic substrates, the adhesive film 1 described above is used for FOP (Film on Plastic substrate) connection.

[0090] Examples of electrode materials for forming the first electrode 5 and the second electrode 8 include metals such as Ag, Ni, Al, Au, Cu, Ti, and Mo, and transparent conductors such as ITO, IZO, silver nanowires, and carbon nanotubes. When one or both of the first and second electrodes are formed from a metallic material containing at least one selected from the group consisting of Cu and Ag, a significant rust-preventive effect by aromatic heterocyclic compound A tends to be obtained. From the viewpoint of reducing connection resistance and ease of availability, one or both of the first and second electrodes may be formed from a metallic material containing Cu (e.g., copper, copper alloy, or copper oxide). When the adhesive film has a multilayer structure, the electrode in contact with the outermost layer containing aromatic heterocyclic compound A (the layer consisting of the adhesive composition of the above embodiment) may be an electrode formed from a metallic material containing at least one selected from the group consisting of Cu and Ag. The electrode in contact with the outermost layer containing aromatic heterocyclic compound A (the layer consisting of the adhesive composition of the above embodiment) may be made of a Cu-containing metallic material (e.g., copper, copper alloy, or copper oxide) from the viewpoint of reducing connection resistance and ease of availability. The first electrode 5 and the second electrode 8 may be made of the same material or of different materials.

[0091] From the viewpoint of preventing wire breakage, a surface layer such as an oxide or nitride film, an alloy film, or an organic film may be provided on the first electrode 5 and the second electrode 8. The first circuit member 6 and the second circuit member 9 may each be provided with one first electrode 5 and one second electrode 8, or multiple first electrodes 5 and second electrodes 8 may be provided at predetermined intervals.

[0092] A specific example of the first circuit member 6 may be a printed circuit board and a glass substrate on which a circuit is formed using ITO or the like. In this case, the base material (second base material 7) of the second circuit member 9 is, for example, a plastic substrate.

[0093] The first circuit component 6 can also be an electronic component such as a semiconductor chip, an active element such as a transistor, a diode, or a thyristor, or a passive element such as a capacitor, a resistor, or a coil. In this case, the substrate (second substrate 7) of the second circuit component 9 is, for example, a plastic substrate, a glass substrate, or a composite substrate. When the first circuit component 6 is an IC chip and the second substrate 7 is a plastic substrate, the adhesive film 1 described above is used for COP (Chip on Plastic substrate) connection.

[0094] As the first circuit member 6, for example, a circuit member having a protruding electrode (such as a semiconductor chip having a protruding electrode or a glass substrate having a protruding electrode) may be used. The protruding electrode may be a bump formed by plating, or it may be a wire bump formed using a gold wire. A wire bump may be obtained, for example, by melting the tip of a gold wire with a torch or the like to form a gold ball, pressing this gold ball onto the electrode pad of a substrate having an electrode pad, and then cutting the wire. [Examples]

[0095] The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to these examples.

[0096] <Example 1> 13 parts by mass of urethane acrylate (product name: UA-5500T, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), which is a radical polymerizable compound; 10 parts by mass of bis(acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.); 5 parts by mass of dimethylol tricyclodecanediaacrylate (product name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.); and 1 part by mass of 2-methacryloyloxyethyl acid phosphate (product name: P-2M, manufactured by Kyoeisha Chemical Co., Ltd.); and the aromatic heterocyclic compound A (1-[N,N-bis(2-ethyl)) shown in formula (1) below. A methyl ethyl ketone solution containing 1 part by mass of xyl)aminomethyl]methylbenzotriazole (product name: TT-LX, manufactured by Johoku Chemical Industry Co., Ltd.), 5 parts by mass of benzoyl peroxide (product name: Niper BMT-K, manufactured by NOF Corporation), which is a free radical generator, and 52 parts by mass of polyester urethane resin (product name: UR4800, manufactured by Toyobo Co., Ltd.), which is an insulating resin, was mixed and stirred to obtain a solution (hereinafter referred to as "Solution A") containing a radical polymerizable compound, aromatic heterocyclic compound A, a free radical generator, and an insulating resin. [ka]

[0097] On the other hand, metal layers (Ni layer: 200 nm, Au layer: 50 nm) were deposited on the surface of plastic particles (nuclei) by plating with Ni and Au. This resulted in conductive particles with an average particle size of 5 μm.

[0098] The conductive particles obtained above were dispersed in solution A prepared above. The amount of conductive particles used was 5 parts by mass. Furthermore, silicone fine particles with an average particle size of 2 μm (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd.) were dispersed at a ratio of 13 parts by mass to obtain a coating solution for the adhesive composition. Note that all of the above blending amounts are relative to 100 parts by mass of the total non-volatile content (excluding conductive particles) in the adhesive composition. This coating solution was applied to a polyethylene terephthalate (PET) film (thickness 50 μm) with one side treated for release using a coating apparatus. The coating film was dried by hot air drying at 70°C to form an anisotropic conductive adhesive film (thickness 18 μm) consisting of the adhesive composition on the PET film.

[0099] <Example 2> In Example 2, an anisotropic conductive adhesive film was prepared in the same manner as in Example 1, except that the aromatic heterocyclic compound A shown in formula (1) was replaced with the aromatic heterocyclic compound A shown in formula (2) below (1-[(2-ethylhexylamino)methyl]benzotriazole, product name: BT-260, manufactured by Johoku Chemical Industry Co., Ltd.). [ka]

[0100] <Example 3> Except for using 12 parts by mass of bis(acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.), and not using 2-methacryloyloxyethyl acid phosphate (product name: P-2M, manufactured by Kyoeisha Chemical Co., Ltd.), aromatic heterocyclic compound A shown in formula (1) (1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, product name: TT-LX, manufactured by Johoku Chemical Industry Co., Ltd.), and conductive particles, an adhesive film (adhesive layer A) with a thickness of 13 μm was formed on a PET film to obtain adhesive film A with a PET film.

[0101] Except for changing the amount of coating liquid used in the adhesive composition, an anisotropic conductive adhesive film (adhesive layer B) with a thickness of 5 μm was formed on a PET film in the same manner as in Example 1, thereby obtaining adhesive film B with a PET film.

[0102] A PET film-attached adhesive film A and a PET film-attached adhesive film B were bonded together to obtain a two-layer anisotropic conductive adhesive film consisting of adhesive layer A and adhesive layer B.

[0103] <Example 4> Except for not using conductive particles, an adhesive film (adhesive layer C1) with a thickness of 1 μm was formed on a PET film in the same manner as in Example 1 to obtain PET film-attached adhesive film C1. Similarly, an adhesive film (adhesive layer C2) with a thickness of 12 μm was formed on a PET film in the same manner as in Example 1, except for not using conductive particles to obtain PET film-attached adhesive film C2.

[0104] Except for using 11 parts by mass of bis(acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.) and not using aromatic heterocyclic compound A (1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, product name: TT-LX, manufactured by Johoku Chemical Industry Co., Ltd.) shown in formula (1), an anisotropically conductive adhesive film (adhesive layer D) with a thickness of 5 μm was formed on a PET film to obtain adhesive film D with a PET film.

[0105] A PET film-backed adhesive film C1 and a PET film-backed adhesive film D were bonded together to obtain a laminate consisting of adhesive layers C1 and D. Next, the PET film on the adhesive layer D side (the PET film in the PET film-backed adhesive film D) was removed, and then the laminate and the PET film-backed adhesive film C2 were bonded together so that adhesive layer D and adhesive layer C2 of the laminate were in contact. This resulted in an anisotropic conductive adhesive film with a three-layer structure in which adhesive layers C1, D, and C2 were laminated in this order.

[0106] <Example 5> An anisotropic conductive adhesive film with a thickness of 18 μm was formed on a PET film in the same manner as in Example 1, except that the amount of aromatic heterocyclic compound A (1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, product name: TT-LX, manufactured by Johoku Chemical Industry Co., Ltd.) shown in formula (1) was 5 parts by mass, and the amount of polyester urethane resin (product name: UR4800, manufactured by Toyobo Co., Ltd.) was 48 parts by mass.

[0107] <Comparative Examples 1-2> In Comparative Examples 1 and 2, anisotropic conductive adhesive films were prepared in the same manner as in Example 1, except that aromatic heterocyclic compound A was not used, and instead 5-methyltetrazole (product name: M5T, manufactured by Tokyo Chemical Industry Co., Ltd.) or 3-mercaptotriazole (product name: 3MT, manufactured by Tokyo Chemical Industry Co., Ltd.) was used in place of aromatic heterocyclic compound A shown in formula (1).

[0108] <Comparative Example 3> In Comparative Example 3, an anisotropically conductive adhesive film was prepared in the same manner as in Example 1, except that aromatic heterocyclic compound A was not used.

[0109] <Rating> [Connection reliability evaluation] As a substrate mimicking a circuit component, a copper electrode film member was prepared, having a PET film and a copper film formed on the PET film. The adhesive films obtained above (adhesive films of Examples 1-5 and Comparative Examples 1-3) were attached to the copper film of this copper electrode film member, and the entire assembly was pressurized for 10 seconds at a pressure of 2 MPa per total contact area while heating the adhesive film to a temperature of 70°C. At this time, the adhesive film of Example 3 was attached so that the surface of adhesive layer B was in contact with the copper film, and the adhesive film of Example 4 was attached so that the surface of adhesive layer C2 was in contact with the copper film. This resulted in obtaining a copper electrode film attachment comprising a cured adhesive film (a cured product of the adhesive composition derived from the adhesive film). Figure 5 is a schematic cross-sectional view showing the copper electrode film attachments of Examples 1-2 and 5. Figure 6 is a schematic cross-sectional view showing the copper electrode film attachment of Example 3. Figure 7 is a schematic cross-sectional view showing the copper electrode film attachment of Example 4. Figure 8 is a schematic cross-sectional view showing the copper electrode film attachments of Comparative Examples 1-3. As shown in Figures 5-8, in copper electrode film attachments 13A-13D, a copper film 15 is formed on a PET film 14, and a cured adhesive film is provided on the side 15a of the copper film 15 opposite to the PET film 14. The cured adhesive film 20A shown in Figure 5 is composed of a cured product of an adhesive composition containing aromatic heterocyclic compound A and conductive particles (consisting of a cured adhesive component 22 containing aromatic heterocyclic compound A and conductive particles 3). The cured adhesive film 20B shown in Figure 6 is composed of a cured product of an adhesive composition containing aromatic heterocyclic compound A and conductive particles (consisting of a cured adhesive component 22 containing aromatic heterocyclic compound A and conductive particles 3) and a cured product of an adhesive composition that does not contain aromatic heterocyclic compound A (consisting of a cured adhesive component 32 that does not contain aromatic heterocyclic compound A). The cured adhesive film 20C shown in Figure 7 consists of a cured product of an adhesive composition containing conductive particles but not aromatic heterocyclic compound A (consisting of a cured product 32 of an adhesive component not containing aromatic heterocyclic compound A and conductive particles 3), and a cured product of an adhesive composition containing aromatic heterocyclic compound A (cured product 22 of an adhesive component containing aromatic heterocyclic compound A).The cured adhesive film 20D shown in Figure 8 is composed of a cured product of an adhesive composition that contains conductive particles but does not contain aromatic heterocyclic compound A (consisting of a cured product 32 of an adhesive component that does not contain aromatic heterocyclic compound A and conductive particles 3).

[0110] The obtained copper electrode film-attached bodies were subjected to reliability testing by being left to stand for 100 hours in an environment of 85°C and 85%RH. For the copper electrode film-attached bodies 13 (13A to 13D) before and after the test, the appearance of the portion (attachment area) of the copper film 15 opposite the PET film 14 on the surface 15a where the cured material 20 is in contact was visually observed. Those with almost no discoloration before and after the test were classified as A, those with slight discoloration as B, and those with severe discoloration (judged to be corrosion) as C, and their reliability was evaluated. The results are shown in Table 1. If the evaluation result was A or B, it was judged to be excellent connection reliability.

[0111] [Conductivity evaluation] As a substrate mimicking a circuit component, a copper electrode film member was prepared, having a PET film and a copper film formed on the PET film. After attaching the adhesive film obtained above (adhesive films of Examples 1-5 and Comparative Examples 1-3) to this copper electrode film member, a plastic circuit board was placed on top of the adhesive film (on the opposite side from the copper electrode film member), and the entire structure was pressurized for 10 seconds at a pressure of 2 MPa per total contact area while heating the adhesive film to a temperature of 170°C. At this time, the adhesive film of Example 3 was attached so that the surface of adhesive layer B was in contact with the copper film, and the adhesive film of Example 4 was attached so that the surface of adhesive layer C2 was in contact with the copper film. This obtained an adhesive film mounted body a (connection structure). As the plastic circuit board, one was used with an electrode width of 150 μm, an electrode spacing of 150 μm, an electrode pitch of 300 μm, a copper foil thickness of 18 μm, and a Ni film (film thickness 3 μm) and an Au film (film thickness 0.01 μm) formed on the surface.

[0112] The resulting adhesive film-mounted assembly a was subjected to reliability testing by being left to stand for 100 hours in an environment of 85°C and 85%RH. After the test, the connection resistance of adhesive film-mounted assembly a was measured. The results are shown in Table 1. A connection resistance of less than 1Ω was considered to indicate good conductivity.

[0113] [Adhesion evaluation] Except for using a PET film (easy-adhesion film) having an SiO2 film on its surface as the adherend, adhesive film mount b was obtained in the same manner as the method for producing adhesive film mount a in the [conductivity evaluation].

[0114] The obtained adhesive film assembly b was subjected to reliability testing by being left to stand for 100 hours in an environment of 85°C and 85%RH. After the test, the adhesive film assembly b was cut into 1 cm wide strips, and the adhesion was evaluated by peeling the FPC from the adhesive film assembly b using the 90° peel method. The test apparatus used was Tensilon STA-1150 (product name, manufactured by A&D Co., Ltd.). Adhesion was judged to be good if the measured strength was 5 N / cm or higher.

[0115] [Table 1] [Explanation of Symbols]

[0116] 1...Adhesive film (adhesive composition), 2...Adhesive component, 3...Conductive particles, 4...First substrate, 5...First electrode, 6...First circuit member, 7...Second substrate, 8...Second electrode, 9...Second circuit member, 10...Circuit connection member (cured product of adhesive composition), 11...Connection structure.

Claims

1. An adhesive composition used to connect circuit components, It contains a radical polymerizable compound, a free radical generator, and an aromatic heterocyclic compound. The radical polymerizable compound includes urethane acrylate or urethane methacrylate. The adhesive composition comprising the aromatic heterocyclic compound, an aromatic heterocyclic compound containing a nitrogen atom, and a side chain group bonded to the aromatic heterocyclic compound and comprising at least one selected from the group consisting of alkyl chains having 3 or more carbon atoms and alkylene chains having 3 or more carbon atoms.

2. The adhesive composition according to claim 1, wherein the side chain group comprises two or more alkyl chains having three or more carbon atoms.

3. The adhesive composition according to claim 1 or 2, further comprising conductive particles.

4. The adhesive composition according to any one of claims 1 to 3, wherein when the total amount of nonvolatile components other than conductive particles in the adhesive composition is 100 parts by mass, the content of the aromatic heterocyclic compound is 0.01 to 10 parts by mass.

5. An adhesive film comprising a layer made of the adhesive composition according to any one of claims 1 to 4.

6. Having a multilayer structure of two or more layers, The adhesive film according to claim 5, wherein at least one of the layers constituting the multilayer structure is a layer made of the adhesive composition.

7. The adhesive film according to claim 6, wherein at least one of the layers constituting the multilayer structure is a layer containing conductive particles.

8. The device comprises a first circuit member having a first electrode, a second circuit member having a second electrode, and a circuit connecting member disposed between the first circuit member and the second circuit member, which electrically connects the first electrode and the second electrode to each other. The circuit connection member is a connection structure comprising a cured product of the adhesive composition according to any one of claims 1 to 4.

9. The connecting structure according to claim 8, wherein one or both of the first electrode and the second electrode are formed of a metallic material including at least one selected from the group consisting of Cu and Ag.

10. A step of preparing a first circuit member having a first electrode and a second circuit member having a second electrode, A step of placing the adhesive composition according to any one of claims 1 to 4 between the first circuit member and the second circuit member, A method for manufacturing a connection structure, comprising the steps of: pressing the first circuit member and the second circuit member together via the adhesive composition to electrically connect the first electrode and the second electrode to each other.

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