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

Abstract

To provide an adhesive composition excellent in adhesive force while containing a compound containing an aromatic heterocycle.SOLUTION: An adhesive composition comprising a compound including an aromatic heterocycle and a side chain group that is bonded to the aromatic heterocycle and includes 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.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, electronic components have become smaller, thinner, and more powerful, spurring the development of economical high-density packaging technologies. Connecting electronic components with fine circuit electrodes to circuit members using conventional solder and rubber connectors is difficult. Therefore, connection methods using anisotropically conductive adhesive compositions and films (adhesive films) with excellent resolution, such as those disclosed in Patent Documents 1 to 6, have been widely used. For example, when connecting the glass of a liquid crystal display (LCD) to circuit members such as TAB (Tape Automated Bonding) or FPC (Flexible Print Circuit), a method is known in which an anisotropically conductive adhesive film containing conductive particles is sandwiched between opposing electrodes and heated and pressurized. This method allows for electrical connection between adjacent electrodes on the same substrate while maintaining insulation between them. In this method, an electronic component with fine circuit electrodes and a circuit member are fixed together using an anisotropically conductive adhesive film.

[0003] The above connection method is advantageous for making modules lighter, thinner, and more sensitive, and is therefore applied to display modules such as liquid crystal display devices and electronic paper, and sensor substrates such as touch panels. For the circuit electrodes formed on these substrates, metal materials containing Ag (silver), Cu (copper), Au (gold), Al (aluminum), etc. (e.g., these metals alone or alloys) are used to reduce wiring resistance. In recent years, metal materials containing Cu and Ag have come to be used to form circuit electrodes due to their low cost, low surface resistance, ease of processing, and other factors.

[0004] When an anisotropically conductive adhesive composition is used to connect electrodes made of metal materials containing Cu and Ag, the electrodes are susceptible to oxidation and moisture absorption because the area near the connection is exposed to the atmosphere. In particular, when solid copper is used as the electrode, surface oxidation can cause a decrease in adhesive strength and an increase in circuit resistance, and moisture absorption can cause the electrode to corrode. Compounds containing aromatic heterocycles, such as benzotriazole, are known as rust inhibitors effective for such metal materials containing Cu and Ag (e.g., 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 Application Laid-Open No. 2011-91044 [Patent Document 5] Japanese Patent Application Laid-Open No. 2011-100605 [Patent Document 6] Japanese Patent Application Laid-Open No. 2013-55058 [Non-patent literature]

[0006] [Non-Patent Document 1] Satoshi Nakagawa, Genzo Hashizume, "Effect of Water-Soluble Organic Sulfides on the Rust Inhibitory Action of Benzotriazole," Corrosion Prevention Technology, Vol. 16, No. 1 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, the connection area of ​​connection structures has become smaller due to the trend toward higher definition and narrower frame sizes of modules. However, stable connectivity is required regardless of the connection area. Therefore, adhesive compositions are required to have excellent adhesive properties. However, when an adhesive composition contains a compound containing the above-mentioned aromatic heterocycle, the adhesive strength of the adhesive composition may decrease.

[0008] Therefore, one object of the present disclosure is to provide an adhesive composition that contains a compound that includes an aromatic heterocycle and yet has excellent adhesive strength. [Means for solving the problem]

[0009] One aspect of the present disclosure relates to an adhesive composition as shown below.

[0010] [1] An adhesive composition comprising a compound including an aromatic heterocycle and a side chain group bonded to the aromatic heterocycle and including 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 contains a nitrogen atom as a heteroatom.

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

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

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

[0015] [6] The adhesive composition according to any one of [1] to [5], which is used for connecting circuit members together.

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

[0017] In one embodiment, the adhesive film may have a multilayer structure of two or more layers. In this case, at least one outermost layer of the multilayer structure may be a layer made of the adhesive composition. At least one of the layers of the multilayer structure may contain 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 connecting 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 connecting member comprises a cured product of the adhesive composition according to any one of [1] to [6].

[0019] In one embodiment, 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 producing 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 described in any one of [1] to [6] between the first circuit member and the second circuit member; and crimping the first circuit member and the second circuit member via the adhesive composition to electrically connect the first electrode and the second electrode to each other. [Effects of the Invention]

[0021] According to the present disclosure, it is possible to provide an adhesive composition that contains a compound that includes an aromatic heterocycle and yet has excellent adhesive strength. [Brief explanation of the drawings]

[0022] [Figure 1]FIG. 1 is a schematic cross-sectional view showing an adhesive film (single layer structure) of one embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an adhesive film (two-layer structure) of one embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an adhesive film (three-layer structure) of one embodiment. [Figure 4] 4(a) and 4(b) are schematic cross-sectional views showing a method for manufacturing a connection structure according to one embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a copper electrode film patched body produced using the adhesive film (single layer structure) of the example. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a copper electrode film patched body produced using the adhesive film (two-layer structure) of the example. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a copper electrode film patched body produced using the adhesive film (three-layer structure) of the example. [Figure 8] FIG. 8 is a schematic cross-sectional view showing a copper electrode film patched body produced using the adhesive film of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0023] Preferred embodiments of the present disclosure will be described below, with reference to the drawings where necessary. However, the present disclosure is not limited to the following embodiments. In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. Furthermore, individually stated upper and lower limit values ​​can be combined in any way.

[0024] <Adhesive composition> The adhesive composition of 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 particles having conductivity, and may be metal particles made of metals such as Au, Ag, Ni, Cu, Pd, solder, etc., or conductive carbon particles made of conductive carbon.

[0026] The conductive particles may be coated conductive particles having a core containing non-conductive glass, ceramic, plastic (polystyrene, etc.), etc., and a coating layer containing the above-mentioned metal or conductive carbon that coats the core. The conductive particles may be metal particles made of a heat-fusible metal, or coated conductive particles having a core containing plastic, and a coating layer containing metal or conductive carbon that coats the core.

[0027] In one embodiment, the conductive particles include a core made of a polymer particle (plastic particle) such as polystyrene, and a metal layer covering the core. The polymer particle may have substantially the entire surface covered with the metal layer. A portion of the surface of the polymer particle may be exposed without being covered with the metal layer, as long as the function as a circuit connecting material is maintained. The polymer particle may be, for example, a particle containing a polymer containing 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 (for example, when the electrode surface is uneven), 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 or 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 of various metals such as Ni, Ni / Au, Ni / Pd, Cu, NiB, Ag, or Ru. The metal layer may be an alloy layer made of an alloy of Ni and Au, an alloy of Ni and Pd, or the like. The metal layer may have a multilayer structure made of multiple metal layers. For example, the metal layer may be made of a Ni layer and an Au layer. The thickness of the metal layer may be 10 nm or more or 20 nm or more, 500 nm or less or 300 nm or less, or may be 10 to 500 nm or 20 to 300 nm. The metal layer may be formed by plating, vapor deposition, sputtering, or the like. The metal layer may be a thin film (for example, a thin film formed by plating, vapor deposition, sputtering, or the like).

[0030] From the viewpoint of improving insulation, the conductive particles may have an insulating layer. Specifically, for example, in the conductive particles of the above embodiment including a core (e.g., a polymer particle) and a coating layer such as a metal layer that coats 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 particle. The insulating layer may be a layer formed from an insulating material such as silica or acrylic resin.

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

[0032] The maximum particle size of the conductive particles is desirably smaller than the smallest gap 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. From the above viewpoint, the maximum particle size of the conductive particles may be 1.0 to 50 μm, 2.0 to 30 μm, or 2.5 to 20 μm.

[0033] In this specification, the particle size of 300 random 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. Note that when the particle has protrusions or is not spherical, the particle size is defined as the diameter of the circle circumscribing the particle in the SEM image.

[0034] The content of the conductive particles is determined depending on the fineness of the electrodes to be connected, etc. For example, the content of the conductive particles may be 0.1 to 50 parts by mass per 100 parts by mass of the adhesive component (i.e., when the total of all non-volatile components contained in the adhesive composition other than the conductive particles is taken as 100 parts by mass). From the viewpoint of insulation properties and production costs, the content of the conductive particles may be 0.1 to 30 parts by mass per 100 parts by mass of the adhesive component. The content of the conductive particles may be 0.1 part 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 the adhesive component.

[0035] (adhesive component) The adhesive component is defined as the nonvolatile content of the adhesive composition other than the conductive particles. The nonvolatile content refers to components that volatilize 20% by mass or less of the total content when heated at 70°C for 10 minutes. For example, when the adhesive composition contains an organic solvent (described below), the nonvolatile content refers to the components other than the conductive particles in the adhesive composition other than the organic solvent. The adhesive component is, for example, composed of an insulating material and has insulating properties as a whole. The adhesive component includes at least a compound (hereinafter also referred to as "aromatic heterocyclic compound A") that includes an aromatic heterocycle and a side chain group bonded to the aromatic heterocycle and containing at least one selected from the group consisting of an alkyl chain having 3 or more carbon atoms (hereinafter also referred to as "long-chain alkyl") and an alkylene chain having 3 or more carbon atoms (hereinafter also referred to as "long-chain alkylene"). In this specification, "alkyl chain" refers to a monovalent saturated aliphatic hydrocarbon chain, and "alkylene chain" refers to a divalent saturated aliphatic hydrocarbon chain.

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

[0037] The radical polymerizable compound is a compound containing a functional group that polymerizes by radicals, and examples thereof include acrylate compounds, methacrylate compounds, and maleimide compounds. The content of the radical polymerizable compound may be, for example, 30% by mass or more, 80% by mass or less, or 30 to 80% by mass based on the total amount of the adhesive components.

[0038] Examples of acrylate compounds 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, dimethyloltricyclodecane 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. The radical polymerizable compound may be used alone or in combination of two or more. From the viewpoint of adhesiveness, the radical polymerizable compound may be a urethane acrylate or a urethane methacrylate.

[0039] As the 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 when crosslinked with an organic peroxide compound. Examples of the radical polymerizable compound that exhibits a Tg of 100°C or higher 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 effect of improving heat resistance, the radical polymerizable compound may be a compound containing a tricyclodecanyl group.

[0040] The viscosity of the radical polymerizable compound at 25°C is, for example, 100,000 to 1,000,000 mPa·s, and may be 100,000 to 500,000 mPa·s. The viscosity of the radical polymerizable compound at 25°C may be 100,000 mPa·s or more, or 1,000,000 mPa·s or less, or 500,000 mPa·s or less. The viscosity of the 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 generates free radicals upon decomposition by heat or light, such as a peroxide compound or an azo compound. The free radical generator is appropriately selected depending on the target connection temperature, connection time, pot life, etc. The free radical generator may be, for example, 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 having a 10-hour half-life temperature of 40°C or higher and a 1-minute half-life 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 the adhesive components. When the adhesive components contain a free radical generator, the free radical generator may be used in combination with a decomposition accelerator, inhibitor, 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, etc. The content of the polymerization inhibitor may be 0.05% by mass or more, 5% by mass or less, or may be 0.05 to 5% by mass, based on the total amount of the adhesive component.

[0044] The aromatic heterocyclic compound A is an organic compound containing an aromatic heterocycle and a side chain group bonded to the aromatic heterocycle.

[0045] An aromatic heterocycle is defined as an aromatic ring containing one or more heteroatoms (heteroatoms) within the ring, and is composed of carbon atoms and heteroatoms. Examples of heteroatoms include nitrogen atoms, sulfur atoms, and oxygen atoms. In the aromatic heterocycle, the heteroatoms act as a Lewis base on the metal surface constituting the electrode, becoming a ligand. When the aromatic heterocyclic compound A is used, the above-mentioned coordination action suppresses oxidation of the electrode surface, thereby suppressing an increase in connection resistance and improving connection reliability. The heteroatom may contain a nitrogen atom, a sulfur atom, or an oxygen atom, from the viewpoint of having a strong Lewis base and further improving connection reliability. Among these, when the heteroatom contains a nitrogen atom, the effect of improving connection reliability tends to be significantly improved. That is, from the viewpoint of significantly improving connection reliability, the aromatic heterocycle may be a nitrogen-containing aromatic heterocycle.

[0046] The number of heteroatoms contained in the aromatic heterocycle may be one or more, two or more, four or less, 1 to 4, or 2 to 4. The aromatic heterocycle may contain a plurality of heteroatoms of one kind, or may contain a plurality of kinds of heteroatoms. The aromatic heterocycle may contain, for example, 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. When the aromatic heterocycle contains one nitrogen atom, it may further contain other atoms (sulfur atom, oxygen atom, etc.) in addition to carbon atom and nitrogen atom.

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

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

[0049] The aromatic heterocyclic compound A may contain one or more aromatic heterocycles. When the aromatic heterocyclic compound A contains multiple aromatic heterocycles, the multiple aromatic heterocycles may be the same or different from one another. The aromatic heterocycle may or may not be fused with another ring. That is, the aromatic heterocyclic compound A may contain a single ring consisting of an aromatic heterocycle, or may contain a fused ring containing an aromatic heterocycle. The other ring may be an aromatic heterocycle or an aromatic carbocycle. That is, the aromatic heterocyclic compound A may contain a ring other than the aromatic heterocycle, or may not contain a ring other than the aromatic heterocycle. In terms of the effects of the present disclosure, the other ring may be an aromatic carbocycle.

[0050] An aromatic carbocycle is an aromatic ring composed only of carbon and hydrogen atoms and does not contain any heteroatoms. Examples of aromatic carbocycles include a benzene ring. Examples of fused rings containing an aromatic carbocycle and an aromatic heterocycle include a benzimidazole ring, a benzotriazole ring, a benzothiazole ring, and a 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 replaces 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 (e.g., an aromatic carbocycle) other than the aromatic heterocycle in a fused ring containing the aromatic heterocycle. That is, the side chain group may be a substituent that replaces a hydrogen atom bonded to a carbon atom constituting a ring other than the aromatic heterocycle. In terms of the effects of the present disclosure, the side chain group may be directly bonded to a heteroatom in the aromatic heterocycle. The number of side chain groups may be one or may be two or more. The number of side chain groups is, for example, three or less.

[0052] The side chain group contains a long-chain alkyl and / or a 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 achieving 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 each having three 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 the 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 the 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 a decrease in coordination ability due to increased steric hindrance. From the above viewpoint, the carbon number of the long-chain alkyl and long-chain alkylene is, for example, 3 to 30. The 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 of the long-chain alkyl (the chain with the largest number of consecutive carbon atoms) may be within the above range. Similarly, when the long-chain alkylene is branched, the carbon number of the main chain of the long-chain alkylene (the chain with the largest number of consecutive carbon atoms) may be within the above range.

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

[0055] The side chain group may contain a functional group other than a long-chain alkyl or long-chain alkylene. Examples of such functional groups include an amino group, a silyl group (such as an alkoxysilyl group or an alkylsilyl group), a hydroxyl group, an ester group, and a mercapto group. The side chain group may contain an alkoxysilyl group from the viewpoint of improving adhesive strength. Examples of the alkoxysilyl group include a methoxysilyl group, a dimethoxysilyl group, a trimethoxysilyl group, an ethoxysilyl group, a diethoxysilyl group, a triethoxysilyl group, a propyloxysilyl group, a butoxysilyl group, and an isopropyloxysilyl group. The functional group may be a substituent that replaces a hydrogen atom bonded to a carbon atom of the long-chain alkyl or long-chain alkylene. The number of functional groups contained in the side chain group may be one or two or more. The type of functional group contained in the side chain group may be one or two or more types.

[0056] When the side chain group contains an alkoxysilyl group, the radical polymerizable compound may contain a functional group that reacts with the alkoxysilyl group to bond. Examples of such functional groups include a hydroxyl group, a carboxyl group, and an alkoxysilyl group. When 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 linking the long-chain alkyl and / or long-chain alkylene to the aromatic heterocycle. When 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, for example, a divalent or trivalent group (e.g., an organic group) containing a heteroatom such as a nitrogen atom, sulfur atom, or oxygen atom. The side chain group may not contain a linking group, and instead be bonded to the aromatic heterocycle by directly bonding the long-chain alkyl or long-chain alkylene to the aromatic heterocycle or a fused ring containing the aromatic heterocycle.

[0058] The aromatic heterocycle may be substituted with a substituent other than the above-mentioned side chain group. Such a substituent may be, for example, a hydrocarbon group (excluding those containing a long-chain alkyl or long-chain alkylene) or the above-mentioned functional group that can be contained in the side chain group. The hydrocarbon group may be an alkyl group or the like.

[0059] From the viewpoint of achieving superior adhesive strength and suppressing an increase in connection resistance to improve connection reliability, the content of the aromatic heterocyclic compound 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 the adhesive component (i.e., when the total of all non-volatile components contained in the adhesive composition other than the conductive particles is taken as 100 parts by mass). From the viewpoint of achieving superior adhesive strength and suppressing an increase in connection resistance to improve connection reliability, the content of the aromatic heterocyclic compound 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 above viewpoint, the content of the aromatic heterocyclic compound 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, relative to 100 parts by mass of the adhesive component.

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

[0061] Examples of thermosetting resins include epoxy resins, cyanate ester resins, maleimide resins, allylnadimide 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 trimellitate, thermosetting resins synthesized from cyclopentadiene, and thermosetting resins obtained by trimerization of aromatic dicyanamide. These thermosetting resins may be used alone or in combination of two or more. The content of the thermosetting resin may be, for example, 20% by mass or more, or 50% by mass or less, or 20 to 50% by mass, based on the total amount of the adhesive components.

[0062] When 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 hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, diaminomaleonitrile, polyamine salt, dicyandiamide, etc., or a modified product thereof. The curing agent may be a polyaddition curing agent such as polyamine, polymercaptan, polyphenol, acid anhydride, etc. As the curing agent, a polyaddition curing agent and a catalytic curing agent may be used in combination. These curing agents may be used alone or in combination of two or more. The content of the curing agent may be 0.5% by mass or more, or 15% by mass or less, based on the total amount of the adhesive component, and may be 0.5 to 15% by mass.

[0063] The curing agent may be a microencapsulated curing agent coated with a polymer compound such as a polyurethane or polyester compound, a thin metal film such as Ni or Cu, or an inorganic compound such as calcium silicate. Such a curing agent can extend the usable time.

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

[0065] In the present 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 to 80% by mass based on the total amount of the adhesive components.

[0066] In each of the above-described embodiments, the adhesive components 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 may include nanofillers such as silica and alumina, as well as urethane and ester-based organic fillers. These fillers are effective in controlling the elastic modulus of the resin, as well as controlling the film-forming properties and softening point.

[0067] The adhesive component may also contain a compound having an aromatic heterocycle in addition to the 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 may not 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 into a film. When the adhesive composition is in the form of a paste, the adhesive composition may contain a solvent such as an organic solvent. Examples of organic solvents include toluene, hexane, acetone, ethyl acetate, methyl ethyl ketone, and ethanol. When the adhesive composition is in the form of a film, the adhesive composition may be substantially free of an organic solvent. The content of the organic solvent in the film-like adhesive composition is, for example, 1 mass % or less based on the total amount of the adhesive composition.

[0070] When the adhesive composition is formed into a film, the adhesive component may contain an insulating resin other than the above-mentioned thermosetting resin as a film-forming component to improve film formability. 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. To further improve connection reliability, the insulating resin may be a high-molecular-weight phenoxy resin having a weight-average molecular weight of 10,000 or more as determined by high-performance liquid chromatography (HPLC). The adhesive component may contain a resin modified with a radically polymerizable functional group, or a mixture of a resin modified with a styrene-based resin or an acrylic resin to adjust melt viscosity, etc. In another embodiment, the adhesive component may contain rubber to improve film formability.

[0071] The adhesive composition described above exhibits excellent adhesive strength when used as a material (circuit connecting material) for connecting circuit components, particularly for electrically connecting electrodes of circuit components. That is, the adhesive composition is suitable for use as a circuit connecting material, and particularly suitable as an anisotropically conductive adhesive composition for connecting circuit components. The reason for the above-described effect is unclear, but is presumed to be as follows. First, in conventional adhesive compositions containing an aromatic heterocyclic compound, the aromatic heterocyclic compound is unevenly distributed on the surface of the electrode to be adhered, and the aromatic heterocyclic compound inhibits adhesion between the adherend and the high molecular weight organic component, such as a polymer of a radically polymerizable compound, produced by curing the adhesive composition. In contrast, in the adhesive composition described above, the long-chain alkyl and / or long-chain alkylene contained in the aromatic heterocyclic compound interacts with the high molecular weight organic component produced after curing, improving adhesion to the adherend, presumably resulting in the above-described effect. The above-described effect tends to be more pronounced when one or both of the electrodes to be adhered are formed of a metal material containing at least one metal selected from the group consisting of Cu and Ag.

[0072] <Adhesive film> The adhesive film includes, for example, a layer made of the adhesive composition of the above embodiment. The adhesive film is preferably used as a circuit connecting material, and is particularly preferably used as an anisotropic conductive adhesive film for connecting circuit components together. When the adhesive composition does not contain conductive particles, the adhesive film may have a multilayer structure and further include a layer containing conductive particles, as described below. Hereinafter, of the adhesive compositions of the above embodiment, an adhesive composition containing conductive particles may sometimes be referred to as an adhesive composition of a first embodiment, and an adhesive composition not containing conductive particles may sometimes be referred to as an adhesive composition of a second embodiment.

[0073] FIG. 1 is a schematic cross-sectional view showing an adhesive film of one embodiment. As shown in FIG. 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 the 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 FIG. 1, a substrate 100 such as a resin film (e.g., a PET film) may be provided on the surface of the adhesive film 1. That is, in one embodiment, the adhesive film may be a substrate-attached adhesive film. 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, or the like, and then heating to reduce the organic solvent.

[0074] In one embodiment, the adhesive film 1 may have a multilayer structure of two or more layers. In this case, at least one outermost layer (the layer located on the outermost side) of the layers constituting the multilayer structure is a layer made of the adhesive composition of the above embodiment. The multilayer structure may, for example, be a structure including a layer containing conductive particles and a layer not containing conductive particles. Specifically, as shown in FIG. 2, the multilayer structure may be a two-layer structure including a layer 1A containing conductive particles 3A (a layer consisting of adhesive component 2A and conductive particles 3A dispersed in adhesive component 2A) and a layer 1B not containing conductive particles (a layer consisting of adhesive component 2B). In this case, it is sufficient that at least one layer is a layer 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 layers made of the adhesive composition of the above embodiment. As shown in FIG. 3 , the multilayer structure may be a three-layer structure composed of a layer 1A containing conductive particles 3A (a layer composed of adhesive component 2A and conductive particles 3A dispersed in adhesive component 2A) and two layers 1B and 1C (layers composed of adhesive components 2B and 2C) that do not contain conductive particles and are provided on both sides of the layer 1A. In this case, at least one of the outermost layers 1B and 1C that do not contain conductive particles 3A may be a layer composed of the adhesive composition of the above embodiment (adhesive composition of the second embodiment), and both outermost layers may be layers composed of the adhesive composition of the above embodiment (adhesive composition of the second embodiment). Furthermore, the layer 1A containing conductive particles 3A may be a layer composed of the adhesive composition of the above embodiment (adhesive composition of the first embodiment). A multilayer adhesive film may, for example, contain a plurality of layers 1A containing conductive particles 3A. These multilayer adhesive films are suitable for narrow-pitch connections because they allow efficient placement of conductive particles on electrodes. In consideration of adhesion to circuit components, the adhesive film may further have adhesive layers that exhibit high adhesion to each circuit component to be connected.

[0075] The multilayer structure may include, for example, a layer containing an aromatic heterocyclic compound A (a layer made of the adhesive composition of the above embodiment) and a layer not containing an aromatic heterocyclic compound A. The layer containing an aromatic heterocyclic compound A and the layer not containing an 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 an aromatic heterocyclic compound A (a layer made of the adhesive composition of the above embodiment) and a layer not containing an aromatic heterocyclic compound A. An adhesive film having such a multilayer structure allows only one of the electrodes of the circuit components to be connected to be selectively brought into contact with the layer containing an aromatic heterocyclic compound A. For example, when only one of the electrodes of the circuit components is formed of a metal material containing at least one selected from the group consisting of Cu and Ag, by using a layer containing an aromatic heterocyclic compound A as the outermost layer on the side in contact with the electrode, the adhesive film will exhibit high adhesion to each of the circuit components to be connected, allowing the circuit components to be more firmly bonded together. When the layer not containing the aromatic heterocyclic compound A also does not contain any compound having an aromatic heterocycle other than the aromatic heterocyclic compound A, the above effect tends to be more pronounced.

[0076] <Connection structure> A method for manufacturing a connection 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; disposing the adhesive composition of the above embodiment between the first circuit member and the second circuit member; and compressing the first circuit member and the second circuit member via the adhesive composition to electrically connect the first electrode and the second electrode to each other. In the step of disposing the adhesive composition, a paste (adhesive paste) containing the adhesive composition may be disposed, or a film (adhesive film) containing the adhesive composition may be disposed. A method for manufacturing a connection structure using the adhesive film 1 will now be described with reference to the drawings.

[0077] 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 FIG. 4(a), a first circuit member 6 having a first substrate 4 and a first electrode 5 provided on the first substrate 4, and a second circuit member 9 having a second substrate 7 and a second electrode 8 provided on the second substrate 7 are prepared.

[0078] Next, the first circuit member 6 and the second circuit member 9 are arranged so that the first electrode 5 and the second electrode 8 face each other, and an 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 may be, for example, 1 to 10 MPa per total connection area. The adhesive film 1 may be cured by heating, or by combining heating with light irradiation. Heating may be carried out at, for example, 100 to 170°C. Pressurization and heating (and light irradiation, if necessary) may be carried out for, for example, 1 to 160 seconds. This results in the first circuit member 6 and the second circuit member 9 being pressure-bonded together via the cured product of the adhesive composition that constitutes the adhesive film 1.

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

[0081] As shown in FIG. 4( b), the connection structure 11 of one embodiment thus obtained 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 connecting member 10 disposed between the first circuit member 6 and the second circuit member 9 and electrically connecting the first electrode 5 and the second electrode 8 to each other. The circuit connecting member 10 is formed from a cured product of an adhesive composition, and comprises a cured product 12 of an 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 composite substrate having a glass and / or plastic substrate and a conductive film and / or an insulating film provided on the substrate, etc. The first substrate 4 and the second substrate 7 may be the same as or different from each other.

[0083] The plastic substrate is, for example, an organic substrate made of a thermoplastic resin. Specific examples include organic substrates made of 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 modification film such as a hard coat and / or a protective film formed on the surface of the organic substrate to improve optical and mechanical properties.To facilitate handling and transportation 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 the strength and flexibility of the substrate as a film, or 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 pressure applied to bond circuit components together can cause electrodes on plastic substrates to break or crack. Furthermore, when connecting electrodes that are difficult to form sufficient electrical connections with, circuit components must be bonded under lower temperatures or lower stress conditions to prevent electrode damage. The adhesive film 1 of the present embodiment can also have advantageous effects compared to conventional materials in these respects.

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

[0088] The composite substrate may include a glass substrate and / or a plastic substrate, and an insulating film and / or a conductive film made of polyimide or an organic or inorganic material with a decorative color formed on the surface of the substrate. In the composite substrate, an electrode 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 may be, for example, a combination in which the first substrate 4 is a plastic substrate and the second substrate 7 is a plastic substrate, or a combination in which the first substrate 4 is a plastic substrate and the second substrate 7 is a glass substrate or a composite substrate. When the first substrate 4 and the second substrate 7 are plastic substrates, the above-mentioned adhesive film 1 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 electrode and the second electrode are formed from a metal material containing at least one selected from the group consisting of Cu and Ag, the rust prevention effect of the aromatic heterocyclic compound A tends to be significantly enhanced. From the viewpoints of reduced connection resistance and ease of availability, one or both of the first electrode and the second electrode may be formed from a metal material containing Cu (e.g., copper, a copper alloy, or a copper oxide). When the adhesive film has a multilayer structure, the electrode in contact with the outermost layer containing the aromatic heterocyclic compound A (the layer made of the adhesive composition of the above embodiment) may be formed from a metal material containing at least one selected from the group consisting of Cu and Ag. The electrode in contact with the outermost layer containing the aromatic heterocyclic compound A (the layer made of the adhesive composition of the above embodiment) may be an electrode made of a metal material containing Cu (e.g., copper, a copper alloy, or a copper oxide) from the viewpoints of reducing connection resistance and easy availability. The first electrode 5 and the second electrode 8 may be made of the same material or different materials.

[0091] To prevent disconnection, 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 a plurality of first electrodes 5 and second electrodes 8 may be provided at predetermined intervals.

[0092] Specific examples of the first circuit member 6 include a printed circuit board and a glass substrate on which a circuit is formed using ITO, etc. In this case, the base material (second base material 7) of the second circuit member 9 is, for example, a plastic substrate.

[0093] Electronic components such as active elements such as semiconductor chips, transistors, diodes, and thyristors, and passive elements such as capacitors, resistors, and coils can also be used as the first circuit member 6. In this case, the substrate (second substrate 7) in the second circuit member 9 is, for example, a plastic substrate, a glass substrate, or a composite substrate. When the first circuit member 6 is an IC chip and the second substrate 7 is a plastic substrate, the above-mentioned adhesive film 1 is used for COP (Chip on Plastic Substrate) connection.

[0094] The first circuit member 6 may be, for example, a circuit member having protruding electrodes (such as a semiconductor chip having protruding electrodes or a glass substrate having protruding electrodes). The protruding electrodes may be bumps formed by plating, or may be wire bumps formed using gold wire. The 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, and then crimping this gold ball onto an electrode pad of a substrate having the electrode pad, and then cutting the wire. [Example]

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

[0096] Example 1 A mixture of 13 parts by mass of urethane acrylate (product name: UA-5500T, manufactured by Shin-Nakamura Chemical Co., Ltd.), 10 parts by mass of bis(acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.), 5 parts by mass of dimethyloltricyclodecane diacrylate (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.), which are radical polymerizable compounds, and an aromatic heterocyclic compound A (1-[N,N-bis(2-ethylhexyl)propionate]) represented by the following formula (1) was used. 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) as a free radical generator, and 52 parts by mass of polyester urethane resin (product name: UR4800, manufactured by Toyobo Co., Ltd.) as an insulating resin was mixed and stirred to obtain a solution containing a radical polymerizable compound, aromatic heterocyclic compound A, the free radical generator, and the insulating resin (hereinafter referred to as "solution A"). [ka]

[0097] On the other hand, metal layers (Ni layer: 200 nm, Au layer: 50 nm) were formed on the surfaces of plastic particles (cores) by plating with Ni and Au, thereby obtaining conductive particles with an average particle size of 5 μm.

[0098] The conductive particles obtained above were dispersed in the solution A prepared above. The amount of conductive particles used was 5 parts by mass. Furthermore, silicone microparticles (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd.) with an average particle size of 2 μm were dispersed in a proportion of 13 parts by mass to obtain a coating liquid of the adhesive composition. All of the above blending amounts are based on a total of 100 parts by mass of the non-volatile content (excluding the conductive particles) in the adhesive composition. This coating liquid was applied to a polyethylene terephthalate (PET) film (thickness: 50 μm) with one side treated for release using a coating device. The coating film was dried with hot air at 70°C to form an anisotropic conductive adhesive film (thickness: 18 μm) made 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 aromatic heterocyclic compound A shown in formula (1) was replaced with 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 A 13 μm thick adhesive film (adhesive layer A) was formed on a PET film in the same manner as in Example 1, except that 12 parts by mass of bis(acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.) was used, and 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 were not used, and adhesive film A with PET film was obtained.

[0101] Except for changing the amount of coating liquid of the adhesive composition used, an anisotropic conductive adhesive film (adhesive layer B) having 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] The adhesive film A with a PET film and the adhesive film B with a PET film were bonded together to obtain an anisotropic conductive adhesive film having a two-layer structure consisting of the adhesive layer A and the adhesive layer B.

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

[0104] An anisotropically conductive adhesive film (adhesive layer D) having a thickness of 5 μm was formed on a PET film in the same manner as in Example 1, except that 11 parts by mass of bis(acryloxyethyl) isocyanurate (product name: M-215, manufactured by Toagosei Co., Ltd.) was used and the 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.) was not used, and adhesive film D with PET film was obtained.

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

[0106] <Example 5> An anisotropic conductive adhesive film having 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.) used was 5 parts by mass, and the amount of polyester urethane resin (product name: UR4800, manufactured by Toyobo Co., Ltd.) used was 48 parts by mass.

[0107] <Comparative Examples 1 and 2> In Comparative Examples 1 and 2, anisotropically conductive adhesive films were prepared in the same manner as in Example 1, except that aromatic heterocyclic compound A was not used, and 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 instead of aromatic heterocyclic compound A shown in formula (1).

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

[0109] <Evaluation> [Connection reliability evaluation] A copper electrode film member having a PET film and a copper film formed on the PET film was prepared as an adherend simulating a circuit component. The adhesive films obtained above (the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3) were attached to the copper film of this copper electrode film member, and the entire assembly was pressed for 10 seconds at a pressure of 2 MPa per total connection area while being heated so that the adhesive film reached a temperature of 70°C. 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 copper electrode film patches comprising a cured adhesive film (a cured product of the adhesive composition derived from the adhesive film). Fig. 5 is a schematic cross-sectional view showing the copper electrode film patches of Examples 1 to 5. Fig. 6 is a schematic cross-sectional view showing the copper electrode film patch of Example 3. Fig. 7 is a schematic cross-sectional view showing the copper electrode film patch of Example 4. Fig. 8 is a schematic cross-sectional view showing the copper electrode film patch of Comparative Examples 1 to 3. As shown in Figures 5 to 8, in copper electrode film adhesive bodies 13A to 13D, a copper film 15 is formed on a PET film 14, and a cured adhesive film is provided on a surface 15a of the copper film 15 opposite the PET film 14. The cured adhesive film 20A shown in Figure 5 is composed of a cured product of an adhesive composition containing an aromatic heterocyclic compound A and conductive particles (composed of a cured product 22 of adhesive components 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 an aromatic heterocyclic compound A and conductive particles (composed of a cured product 22 of adhesive components 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 (composed of a cured product 32 of adhesive components that do not contain aromatic heterocyclic compound A). The cured adhesive film 20C shown in FIG. 7 is composed of a cured product of an adhesive composition that contains conductive particles but does not contain aromatic heterocyclic compound A (composed of a cured product 32 of adhesive components that do not contain aromatic heterocyclic compound A and conductive particles 3), and a cured product of an adhesive composition that contains aromatic heterocyclic compound A (cured product 22 of adhesive components that contain aromatic heterocyclic compound A).The cured adhesive film 20D shown in FIG. 8 is composed of a cured product of an adhesive composition that contains conductive particles but does not contain aromatic heterocyclic compound A (composed 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 body was left to stand in an environment of 85°C and 85% RH for 100 hours and subjected to a reliability test. The appearance of the portion (attached portion) of the surface 15a of the copper film 15 opposite the PET film 14, where the cured product 20 was in contact, of the copper electrode film-attached body 13 (13A to 13D) before and after the test was visually observed. Reliability was evaluated as follows: A indicates that almost no discoloration was observed before and after the test; B indicates that discoloration was observed but to a small extent; and C indicates that severe discoloration was observed (determined to have occurred). The results are shown in Table 1. Note that an evaluation result of A or B was determined to have excellent connection reliability.

[0111] [Conductivity evaluation] A copper electrode film member having a PET film and a copper film formed on the PET film was prepared as an adherend simulating a circuit component. After the adhesive film (adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3) obtained above was attached to this copper electrode film member, a plastic circuit board was placed on top of the adhesive film (on the side opposite the copper electrode film member). While heating the adhesive film to a temperature of 170°C, the entire structure was pressed for 10 seconds at a pressure of 2 MPa per total connection area. The adhesive film of Example 3 was attached so that the surface of adhesive layer B contacted the copper film, and the adhesive film of Example 4 was attached so that the surface of adhesive layer C2 contacted the copper film. This resulted in an adhesive film mounting body a (connection structure). The plastic circuit board used had an electrode width of 150 μm, an interelectrode spacing of 150 μm, an interelectrode pitch of 300 μm, and a copper foil thickness of 18 μm, with a Ni film (thickness 3 μm) and an Au film (thickness 0.01 μm) formed on the surface.

[0112] The resulting adhesive film mounting body a was subjected to a reliability test by standing for 100 hours in an environment of 85°C and 85% RH. After the test, the connection resistance of the adhesive film mounting body a was measured. The results are shown in Table 1. Connection resistance of less than 1 Ω was determined to have good conductivity.

[0113] [Adhesion evaluation] Adhesive film mounting body b was obtained in the same manner as adhesive film mounting body a in [Conductivity Evaluation], except that a PET film (easy-adhesion film) with an SiO2 film on its surface was used as the adherend instead of the copper electrode film member.

[0114] The resulting adhesive film mounting body b was subjected to a reliability test by leaving it for 100 hours in an environment of 85°C and 85% RH. After the test, adhesive film mounting body b was cut into 1 cm widths, and the FPC was peeled from adhesive film mounting body b using the 90° peel method to evaluate adhesion. The test equipment used was a Tensilon STA-1150 (product name, manufactured by A&D Co., Ltd.). Adhesion was judged to be good when the measured strength was 5 N / cm or more.

[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 connecting member (cured product of adhesive composition), 11...connection structure.

Claims

1. An adhesive composition used for connecting circuit members, It contains a curable component that hardens with heat or light, and an aromatic heterocyclic compound. 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 positioned 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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