Adhesive film for circuit connection, method for manufacturing circuit connection structure, and adhesive film storage set

Abstract

An adhesive film 11 for circuit connection is provided with: a peelable support film 12, a first adhesive layer 13 containing conductive particles P, the first adhesive layer being disposed on the support film; and a second adhesive layer 14 disposed on the first adhesive layer 13. The thickness of the first adhesive layer is 0.1 to 1.0-times the average particle diameter of the conductive particles.

Description

[Technical Field]

[0001] The present invention relates to an adhesive film for circuit connection, a method for producing a circuit connection structure, and an adhesive film storage set. [Background technology]

[0002] Conventionally, various adhesive materials have been used to connect circuits. For example, anisotropically conductive adhesive films for circuit connection, in which conductive particles are dispersed in the adhesive, have been used as adhesive materials for connecting a liquid crystal display and a tape carrier package (TCP), connecting a flexible printed circuit board (FPC) and a TCP, or connecting an FPC and a printed wiring board. Specifically, a circuit connection structure is obtained by bonding circuit components together via a circuit connection portion formed by the adhesive film for circuit connection, and electrically connecting electrodes on the circuit components together via the conductive particles in the circuit connection portion.

[0003] An adhesive film for circuit connection contains, for example, an adhesive component containing a thermosetting resin or the like, and optionally conductive particles, and is formed as an adhesive layer on a substrate such as a polyethylene terephthalate (PET) film. Furthermore, the adhesive film may be used in the form of a reel, which is made by cutting a raw film into tapes of a width suitable for the application and winding the tapes around a core to form a wound body (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-34468 Summary of the Invention [Problem to be solved by the invention]

[0005] When connecting a driver IC or other component to an LCD module using an adhesive film, the adhesive film was conventionally transferred to the glass panel first. However, in recent years, there has been a trend to reduce the amount of adhesive film used in order to cut LCD manufacturing costs, and there is also a demand for panel designs with narrow bezels. As a result, a manufacturing method has been adopted in which the adhesive film is first attached to a flexible substrate such as a COF or FPC.

[0006] However, when using conventional adhesive films, it is difficult to efficiently capture conductive particles between circuit electrodes, which can lead to problems such as a deterioration in electrical reliability and an increased risk of short circuits due to the accumulation of conductive particles that are not captured between the circuits.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide an adhesive film for circuit connection that can obtain a circuit connection structure with excellent connection reliability between opposing circuit components, even when the film is first attached to a flexible substrate to make the circuit connection, a method for manufacturing a circuit connection structure using the same, and an adhesive film storage set. [Means for solving the problem]

[0008] An adhesive film for circuit connection according to one aspect of the present invention comprises a peelable support film, a first adhesive layer containing conductive particles provided on the support film, and a second adhesive layer laminated on the first adhesive layer, wherein the thickness of the first adhesive layer is 0.1 to 1.0 times the average particle size of the conductive particles.

[0009] This adhesive film for circuit connection can provide a circuit connection structure with excellent connection reliability between opposing circuit components, even when the film is first attached to a flexible substrate for circuit connection. In the first adhesive layer, it is preferable that 90% or more of the conductive particles are separated from other conductive particles.

[0010] The first adhesive layer may be made of a cured product of a first curable composition, and the first curable composition may contain a radically polymerizable compound having a radically polymerizable group.

[0011] The second adhesive layer may be made of a second curable composition, and the second curable composition may contain a radically polymerizable compound having a radically polymerizable group.

[0012] A method for manufacturing a circuit connection structure according to one aspect of the present invention includes the steps of interposing the first adhesive layer and the second adhesive layer of the above-described adhesive film for circuit connection between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermocompressing the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

[0013] According to this method, even when the circuit connection is performed by first attaching the adhesive film for circuit connection to the flexible substrate, a circuit connection structure having excellent connection reliability between opposing circuit members can be obtained.

[0014] That is, the method for manufacturing a circuit connection structure according to the present invention may include a step in which the first circuit member has a flexible substrate and the circuit connection adhesive film is attached to the first circuit member so that the second adhesive layer contacts the first circuit member.

[0015] An adhesive film storage set according to one aspect of the present invention comprises the above-described adhesive film for circuit connection and a storage member for storing the adhesive film, wherein the storage member has a visible portion that allows the interior of the storage member to be viewed from the outside, and the transmittance of light at a wavelength of 365 nm at the visible portion is 10% or less. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an adhesive film for circuit connection that can obtain a circuit connection structure with excellent connection reliability between opposing circuit components, even when the film is first attached to a flexible substrate to perform circuit connection, a method for manufacturing a circuit connection structure using the same, and an adhesive film storage set. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connection according to the present invention. [Figure 2] 3A to 3C are schematic cross-sectional views showing steps in a method for manufacturing a circuit connection structure. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a laminate obtained through the steps of FIG. 2. [Figure 4] FIG. 3 is a schematic cross-sectional view showing a step subsequent to that shown in FIG. 2. [Figure 5] FIG. 5 is a schematic cross-sectional view showing a circuit connection structure obtained through the steps of FIG. 4. [Figure 6] FIG. 2 is a schematic diagram showing a manufacturing process for the adhesive film for circuit connection shown in FIG. [Figure 7] FIG. 10 is a schematic diagram showing a magnetic field application step. [Figure 8] FIG. 2 is a schematic cross-sectional view showing the state of the adhesive film for circuit connection after undergoing a magnetic field application step and a drying step. [Figure 9] FIG. 8 is a schematic cross-sectional view showing a lamination step subsequent to FIG. 7. [Figure 10] 1 is a perspective view showing an embodiment of an adhesive film storage set according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail, possibly with reference to the drawings. In this specification, the upper and lower limits individually described can be arbitrarily combined. Furthermore, in this specification, "(meth)acrylate" means at least one of an acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl."

[0019] <Adhesive film for circuit connection> Fig. 1 is a schematic cross-sectional view showing an adhesive film for circuit connection according to one embodiment. As shown in Fig. 1, the adhesive film for circuit connection 11 (hereinafter also simply referred to as "adhesive film 11") comprises a peelable support film 12, a first adhesive layer 13 provided on the support film 12, and a second adhesive layer 14 laminated on the first adhesive layer 13. The first adhesive layer 13 contains conductive particles P.

[0020] In the adhesive film 11, conductive particles P are dispersed in the first adhesive layer 13. Therefore, the adhesive film 11 is an anisotropically conductive adhesive film having anisotropic conductivity. The adhesive film 11 is used to electrically connect the first electrode and the second electrode to each other by interposing a first adhesive layer and a second adhesive layer between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermocompression bonding the first circuit member and the second circuit member.

[0021] Furthermore, when the circuit component to be connected has a flexible substrate, the adhesive film for circuit connection 11 can be attached to the first circuit component so that the second adhesive layer contacts the first circuit component.

[0022] In this embodiment, the thickness of the first adhesive layer 13 may be 0.1 to 1.0 times, and more preferably 0.1 to 0.7 times, the average particle size of the conductive particles P. Furthermore, in the first adhesive layer 13, 90% or more of the conductive particles P may be separated from other conductive particles.

[0023] In this embodiment, the ratio (X / Y) of the melt viscosity X of the first adhesive layer 13 at the temperature Ty at which the second adhesive layer 14 exhibits the minimum melt viscosity Y to the minimum melt viscosity Y of the second adhesive layer 14 may be 10 or more.

[0024] From the viewpoint of improving adhesion to circuit members, the melt viscosity ratio (X / Y) is preferably 10 or more, more preferably 20 or more, even more preferably 50 or more, and particularly preferably 100 or more. From the viewpoint of wettability to circuit members, the melt viscosity ratio (X / Y) may be 10,000 or less, 5,000 or less, or 1,000 or less. From these viewpoints, the melt viscosity ratio (X / Y) may be 10 to 10,000, 20 to 5,000, 50 to 5,000, or 100 to 1,000. The melt viscosity X and minimum melt viscosity Y can be confirmed by first measuring the melt viscosity of the second adhesive layer to determine the minimum melt viscosity Y of the second adhesive layer (and the temperature Ty at which the second adhesive layer exhibits the minimum melt viscosity Y), and then measuring the melt viscosity of the first adhesive layer to determine the melt viscosity X of the first adhesive layer at temperature Ty. The melt viscosity measurement can also be performed after the adhesive film is obtained.

[0025] (support film) The support film 12 is formed of, for example, polyethylene terephthalate (PET), polyethylene, polypropylene, or the like. The support film 12 may contain any filler. The surface of the support film 12 may be subjected to a release treatment, a plasma treatment, or the like. The support film 12 can be peeled off after the first adhesive layer and the second adhesive layer are transferred to the circuit member.

[0026] (First adhesive layer) The first adhesive layer may be, for example, a cured product of a first curable composition. The first curable composition may be a photocurable composition, a thermosetting composition, or a mixture of a photocurable composition and a thermosetting composition. The first curable composition may contain, for example, (A) a polymerizable compound (hereinafter also referred to as "component (A)"), (B) a polymerization initiator (hereinafter also referred to as "component (B)"), and (C) conductive particles (hereinafter also referred to as "component (C)"). When the first curable composition is a photocurable composition, the first curable composition contains a photopolymerization initiator as component (B). When the first curable composition is a thermosetting composition, the first curable composition contains a thermal polymerization initiator as component (B). Such a first adhesive layer can be obtained, for example, by irradiating or heating a layer made of the first curable composition with light to polymerize component (A) and cure the first curable composition. That is, the first adhesive layer may be composed of conductive particles and an adhesive component formed by photocuring a first curable composition. The first adhesive layer may be a cured product obtained by completely curing the first curable composition, or a cured product obtained by partially curing the first curable composition. That is, when the first curable composition contains components (A) and (B), the adhesive component may or may not contain unreacted components (A) and (B). The first adhesive layer may be composed of a resin composition other than the cured product of the curable composition. For example, the first adhesive layer may be composed of a resin composition containing a resin component such as a phenoxy resin (e.g., PKHC), a polyester urethane resin, a polyurethane resin, or an acrylic rubber. By using such a resin component, the melt viscosity of the second adhesive layer at the temperature at which it exhibits the minimum melt viscosity (e.g., 100°C) can be adjusted to approximately 100,000 to 10,000,000 Pa·s, and the melt viscosity ratio (X / Y) can be set to 10 or more.

[0027] [Component (A): Polymerizable compound] Component (A) is a compound that polymerizes, for example, by the action of radicals, cations, or anions generated by a polymerization initiator (photopolymerization initiator or thermal polymerization initiator) upon irradiation with light (e.g., ultraviolet light) or heating. Component (A) may be a monomer, oligomer, or polymer. As component (A), one type of compound may be used alone, or multiple types of compounds may be used in combination.

[0028] Component (A) has at least one polymerizable group. The polymerizable group is, for example, a group containing a polymerizable unsaturated double bond (ethylenically unsaturated bond). From the viewpoints of easily obtaining a desired melt viscosity, reducing the likelihood of peeling between the circuit component and the circuit connection in a high-temperature, high-humidity environment, and further improving the effect of reducing connection resistance and providing superior connection reliability, the polymerizable group is preferably a radically polymerizable group that reacts with radicals. That is, component (A) is preferably a radically polymerizable compound. Examples of radically polymerizable groups include vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenylene groups, (meth)acryloyl groups, and maleimide groups. The number of polymerizable groups in component (A) may be 2 or more from the viewpoints of easily obtaining a desired melt viscosity after polymerization and easily controlling the physical properties of the cured resin, and may be 10 or less from the viewpoint of suppressing cure shrinkage during polymerization. In order to balance the crosslink density and cure shrinkage, a polymerizable compound having a number of polymerizable groups within the above range may be used, and then a polymerizable compound having a number outside the above range may be additionally used.

[0029] Specific examples of the component (A) include (meth)acrylate compounds, maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadimide derivatives, natural rubber, isoprene rubber, butyl rubber, nitrile rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and carboxylated nitrile rubber.

[0030] Examples of (meth)acrylate compounds include epoxy (meth)acrylate, (poly)urethane (meth)acrylate, methyl (meth)acrylate, polyether (meth)acrylate, polyester (meth)acrylate, polybutadiene (meth)acrylate, silicone acrylate, ethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-hexyl (meth)acrylate. Acrylate, 2-hydroxyethyl (meth)acrylate, isopropyl (meth)acrylate, hydroxypropyl (meth)acrylate, isobutyl (meth)acrylate, isobornyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, n-lauryl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-(meth)acryloyloxyethyl phosphate, N,N-di Methylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, polyethylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, neo Pentyl glycol di(meth)acrylate, pentaerythritol (meth)acrylate, dipentaerythritol hexa(meth)acrylate, isocyanuric acid modified bifunctional (meth)acrylate, isocyanuric acid modified trifunctional (meth)acrylate, tricyclodecanyl acrylate, dimethylol-tricyclodecane diacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxypolyethoxy)phenyl]propane, 2,Examples include 2-di(meth)acryloyloxydiethyl phosphate and 2-(meth)acryloyloxyethyl acid phosphate.

[0031] Examples of the maleimide compound include 1-methyl-2,4-bismaleimidebenzene, N,N'-m-phenylene bismaleimide, N,N'-p-phenylene bismaleimide, N,N'-m-toluylene bismaleimide, N,N'-4,4-biphenylene bismaleimide, N,N'-4,4-(3,3'-dimethyl-biphenylene) bismaleimide, N,N'-4,4-(3,3'-dimethyldiphenylmethane) bismaleimide, N,N'-4,4-(3,3'-diethyldiphenylmethane) bismaleimide, N,N'-4,4-diphenylmethane bismaleimide, and N,N'-4,4-diphenylpropane. Examples of suitable bismaleimides include propane bismaleimide, N,N'-4,4-diphenylether bismaleimide, N,N'-3,3-diphenylsulfone bismaleimide, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, 2,2-bis(3-s-butyl-4-8(4-maleimidophenoxy)phenyl)propane, 1,1-bis(4-(4-maleimidophenoxy)phenyl)decane, 4,4'-cyclohexylidene-bis(1-(4maleimidophenoxy)-2-cyclohexylbenzene), and 2,2'-bis(4-(4-maleimidophenoxy)phenyl)hexafluoropropane.

[0032] Examples of the vinyl ether compound include diethylene glycol divinyl ether, dipropylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether.

[0033] Examples of the allyl compound include 1,3-diallyl phthalate, 1,2-diallyl phthalate, and triallyl isocyanurate.

[0034] Component (A) is preferably a (meth)acrylate compound from the viewpoints of easily achieving the desired melt viscosity and of the availability and availability of compounds with various structures. Component (A) may be a (poly)urethane (meth)acrylate compound (a urethane (meth)acrylate compound or a polyurethane (meth)acrylate compound) from the viewpoint of achieving even more excellent adhesive properties. Furthermore, component (A) may be a (meth)acrylate compound having a high Tg skeleton such as a dicyclopentadiene skeleton from the viewpoint of achieving even more excellent adhesive properties.

[0035] From the viewpoint of easily achieving the desired melt viscosity, balancing crosslink density and cure shrinkage, further reducing connection resistance, and improving connection reliability, component (A) may be a compound (e.g., polyurethane (meth)acrylate) in which a polymerizable group such as a vinyl group, an allyl group, or a (meth)acryloyl group has been introduced into the terminal or side chain of a thermoplastic resin such as an acrylic resin, a phenoxy resin, or a polyurethane resin. In this case, from the viewpoint of an excellent balance between crosslink density and cure shrinkage, the weight-average molecular weight of component (A) may be 3,000 or more, 5,000 or more, or 10,000 or more. Furthermore, from the viewpoint of excellent compatibility with other components, the weight-average molecular weight of component (A) may be 1,000,000 or less, 500,000 or less, or 250,000 or less. The weight-average molecular weight refers to a value measured by gel permeation chromatography (GPC) using a calibration curve with standard polystyrene under the conditions described in the examples.

[0036] Component (A) preferably contains, as a (meth)acrylate compound, a radically polymerizable compound having a phosphate ester structure represented by the following general formula (1): In this case, adhesive strength to the surface of inorganic materials (such as metals) is improved, making it suitable for bonding electrodes (e.g., circuit electrodes) to each other, for example. [ka] [In the formula, n represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.]

[0037] The radical polymerizable compound having the phosphate ester structure can be obtained, for example, by reacting phosphoric anhydride with 2-hydroxyethyl (meth)acrylate. Specific examples of the radical polymerizable compound having the phosphate ester structure include mono(2-(meth)acryloyloxyethyl) acid phosphate and di(2-(meth)acryloyloxyethyl) acid phosphate.

[0038] The content of component (A), based on the total mass of the first curable composition, may be 5% by mass or more, 10% by mass or more, or 20% by mass or more, from the viewpoint of easily obtaining a desired melt viscosity and a desired physical property of the cured product. The content of component (A), based on the total mass of the first curable composition, may be 90% by mass or less, 80% by mass or less, or 70% by mass or less, from the viewpoint of suppressing cure shrinkage during polymerization.

[0039] [Component (B): Polymerization initiator] Component (B) may be a photopolymerization initiator (photoradical polymerization initiator, photocationic polymerization initiator, or photoanionic polymerization initiator) that generates radicals, cations, or anions upon irradiation with light having a wavelength in the range of 150 to 750 nm, preferably light having a wavelength in the range of 254 to 405 nm, and more preferably light having a wavelength of 365 nm (e.g., ultraviolet light), or a thermal polymerization initiator (thermal radical polymerization initiator, thermal cationic polymerization initiator, or thermal anionic polymerization initiator) that generates radicals, cations, or anions upon heat. Component (B) is preferably a radical polymerization initiator (photoradical polymerization initiator or thermal radical polymerization initiator) from the viewpoints of easily achieving a desired melt viscosity, further improving the effect of reducing connection resistance and providing more excellent connection reliability, and facilitating curing at low temperatures and in a short time. Component (B) may be a single compound or a combination of multiple compounds. For example, the first curable composition may contain both a photopolymerization initiator and a thermal polymerization initiator as component (B).

[0040] Photoradical polymerization initiators decompose when exposed to light to generate free radicals. That is, photoradical polymerization initiators are compounds that generate radicals when exposed to external light energy. Examples of photoradical polymerization initiators include compounds having an oxime ester structure, a bisimidazole structure, an acridine structure, an α-aminoalkylphenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzyl dimethyl ketal structure, an α-hydroxyalkylphenone structure, or the like. From the viewpoints of easily obtaining a desired melt viscosity and of achieving a superior effect of reducing connection resistance, the photoradical polymerization initiator preferably has at least one structure selected from the group consisting of an oxime ester structure, an α-aminoalkylphenone structure, and an acylphosphine oxide structure.

[0041] Specific examples of compounds having an oxime ester structure include 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-o-benzoyloxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime, 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(o-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime), and the like.

[0042] Specific examples of compounds having an α-aminoalkylphenone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-morpholinophenyl)-butanone-1, and the like.

[0043] Specific examples of compounds having an acylphosphine oxide structure include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

[0044] A thermal radical polymerization initiator decomposes due to heat to generate free radicals. In other words, a thermal radical polymerization initiator is a compound that generates radicals when thermal energy is applied from the outside. The thermal radical polymerization initiator can be arbitrarily selected from conventionally known organic peroxides and azo compounds. From the viewpoints of stability, reactivity, and compatibility, the thermal radical polymerization initiator preferably uses an organic peroxide having a one-minute half-life temperature of 90 to 175°C and a weight-average molecular weight of 180 to 1000. Having a one-minute half-life temperature within this range results in even better storage stability, sufficiently high radical polymerizability, and rapid curing.

[0045] Specific examples of organic peroxides include 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-t-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, cumyl peroxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, 1,1,3,3-Tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydroterephthalate, t-amylperoxy-3,5,5-trimethylhexanoate peroxymethyl methyl ester, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, t-amyl peroxyneodecanoate, t-amyl peroxy-2-ethylhexanoate, di(3-methylbenzoyl) peroxide, dibenzoyl peroxide, di(4-methylbenzoyl) peroxide, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate peroxybenzoate, 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl peroxybenzoate, dibutyl peroxytrimethyl adipate, t-amyl peroxy normal octoate, t-amyl peroxy isononanoate, and t-amyl peroxybenzoate.

[0046] Specific examples of azo compounds include 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanovaleric acid), and 1,1'-azobis(1-cyclohexanecarbonitrile).

[0047] The content of the (B) component may be 0.1 mass % or more, or 0.5 mass % or more, based on the total mass of the first curable composition, from the viewpoint of excellent rapid curing properties and an excellent effect of reducing connection resistance. The content of the (B) component may be 15 mass % or less, or 10 mass % or less, or 5 mass % or less, based on the total mass of the first curable composition, from the viewpoint of improved storage stability and an excellent effect of reducing connection resistance.

[0048] The first curable composition preferably contains at least one of a photopolymerization initiator and a thermal polymerization initiator as component (B) from the viewpoint of easily obtaining the desired viscosity, and more preferably contains a photopolymerization initiator from the viewpoint of facilitating the production of the adhesive film for circuit connection.

[0049] [(C) Component: Conductive particles] Component (C) is not particularly limited as long as it is a conductive particle, and may be, for example, a metal particle composed of a metal such as Au, Ag, Ni, Cu, or solder, or a conductive carbon particle composed of conductive carbon. Component (C) may also be a coated conductive particle comprising a core containing a non-conductive material such as glass, ceramic, or plastic (e.g., polystyrene), and a coating layer containing the metal or conductive carbon that coats the core. Among these, metal particles formed of a heat-fusible metal or coated conductive particles comprising a core containing a plastic and a coating layer containing a metal or conductive carbon that coats the core are preferred. In this case, the cured product of the first curable composition can be easily deformed by heating or applying pressure, which increases the contact area between the electrodes and component (C) when electrically connecting the electrodes, thereby further improving the conductivity between the electrodes.

[0050] Component (C) may be an insulating coated conductive particle comprising the above-mentioned metal particles, conductive carbon particles, or coated conductive particles and an insulating layer containing an insulating material such as resin and coating the surface of the particle. When component (C) is an insulating coated conductive particle, even if the content of component (C) is high, the particle surface is coated with resin, which can prevent short circuits caused by contact between components (C) and can also improve insulation between adjacent electrode circuits. Component (C) can be used alone or in combination of two or more of the above-mentioned various conductive particles.

[0051] The maximum particle size of component (C) must be smaller than the minimum electrode spacing (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (C) 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 component (C) may be 50 μm or less, 30 μm or less, or 20 μm or less. In this specification, the particle size of 300 random conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is defined as the maximum particle size of component (C). Note that when component (C) has protrusions or is otherwise not spherical, the particle size of component (C) is defined as the diameter of a circle circumscribing the conductive particle in an SEM image.

[0052] From the viewpoint of excellent dispersibility and conductivity, the average particle size of component (C) 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 component (C) may be 50 μm or less, 30 μm or less, or 20 μm or less. In this specification, the particle size of 300 random conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the particle sizes obtained is defined as the average particle size.

[0053] In the first adhesive layer, the component (C) is preferably uniformly dispersed. From the viewpoint of obtaining a stable connection resistance, the particle density of the component (C) in the first adhesive layer is preferably 100 pcs / mm 2 It may be more than 1000pcs / mm 2 It may be more than 2000pcs / mm 2 The particle density of the component (C) in the first adhesive layer may be 100,000 pcs / mm or more from the viewpoint of improving the insulating properties between adjacent electrodes. 2 May be less than 50,000 pcs / mm 2 It may be less than 10000pcs / mm 2 It may be the following:

[0054] The content of component (C) may be 0.1 vol% or more, 1 vol% or more, or 5 vol% or more, based on the total volume of the first adhesive layer, from the viewpoint of further improving electrical conductivity. The content of component (C) may be 50 vol% or less, 30 vol% or less, or 20 vol% or less, based on the total volume of the first adhesive layer, from the viewpoint of easily suppressing short circuits. The content of component (C) in the first curable composition (based on the total volume of the first curable composition) may be the same as the above range.

[0055] [Other ingredients] The first curable composition may further contain components other than the components (A), (B), and (C). Examples of the other components include a thermoplastic resin, a coupling agent, and a filler. These components may be contained in the first adhesive layer.

[0056] Examples of thermoplastic resins include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, and acrylic rubber. When the first curable composition contains a thermoplastic resin, the first adhesive layer can be easily formed. Furthermore, when the first curable composition contains a thermoplastic resin, stress in the first adhesive layer that occurs when the first curable composition is cured can be alleviated. Furthermore, when the thermoplastic resin has a functional group such as a hydroxyl group, the adhesiveness of the first adhesive layer is likely to be improved. The content of the thermoplastic resin may be, for example, 5% by mass or more and 80% by mass or less, based on the total mass of the first curable composition.

[0057] Examples of coupling agents include silane coupling agents having organic functional groups such as (meth)acryloyl groups, mercapto groups, amino groups, imidazole groups, and epoxy groups; silane compounds such as tetraalkoxysilanes; tetraalkoxytitanate derivatives; and polydialkyltitanate derivatives. When the first curable composition contains a coupling agent, the adhesiveness can be further improved. The content of the coupling agent may be, for example, 0.1% by mass or more and 20% by mass or less, based on the total mass of the first curable composition.

[0058] Examples of the filler include non-conductive fillers (e.g., non-conductive particles). When the first curable composition contains a filler, further improvement in connection reliability can be expected. The filler may be either an inorganic filler or an organic filler. Examples of the inorganic filler include inorganic fine particles such as metal oxide fine particles, such as silica fine particles, alumina fine particles, silica-alumina fine particles, titania fine particles, and zirconia fine particles; and nitride fine particles. Examples of the organic filler include organic fine particles such as silicone fine particles, methacrylate-butadiene-styrene fine particles, acrylic-silicone fine particles, polyamide fine particles, and polyimide fine particles. These fine particles may have a uniform structure or a core-shell structure. The maximum diameter of the filler is preferably less than the minimum diameter of the conductive particles. The content of the filler may be, for example, 0.1% by volume or more and 50% by volume or less, based on the total volume of the first curable composition.

[0059] The first curable composition may contain other additives such as a softener, an accelerator, an anti-degradant, a colorant, a flame retardant, a thixotropic agent, etc. The content of these additives may be, for example, 0.1 to 10 mass% based on the total mass of the first curable composition. These additives may be contained in the first adhesive layer.

[0060] The first curable composition may contain a thermosetting resin instead of or in addition to the components (A) and (B). The thermosetting resin is a resin that hardens when heated and has at least one thermosetting group. The thermosetting resin is, for example, a compound that crosslinks when reacted with a curing agent by heat. As the thermosetting resin, one compound may be used alone, or multiple compounds may be used in combination.

[0061] The thermosetting group may be, for example, an epoxy group, an oxetane group, an isocyanate group, or the like, from the viewpoint of easily obtaining a desired melt viscosity, further improving the effect of reducing connection resistance, and providing more excellent connection reliability.

[0062] Specific examples of thermosetting resins include epoxy resins such as bisphenol-type epoxy resins which are reaction products of epichlorohydrin with bisphenol A, F, AD, etc., epoxy novolac resins which are reaction products of epichlorohydrin with phenol novolac, cresol novolac, etc., naphthalene-based epoxy resins having a skeleton containing a naphthalene ring, and various epoxy compounds having two or more glycidyl groups in one molecule, such as glycidyl amine and glycidyl ether.

[0063] When a thermosetting resin is used in place of the components (A) and (B), the content of the thermosetting resin in the first curable composition may be, for example, 20% by mass or more and 80% by mass or less, based on the total mass of the first curable composition. When a thermosetting resin is used in addition to the components (A) and (B), the content of the thermosetting resin in the first curable composition may be, for example, 30% by mass or more and 70% by mass or less, based on the total mass of the first curable composition.

[0064] When the first curable composition contains a thermosetting resin, the first curable composition may contain the above-mentioned curing agent for the thermosetting resin. Examples of the curing agent for the thermosetting resin include a thermal radical generator, a thermal cation generator, and a thermal anion generator. The content of the curing agent may be, for example, 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the thermosetting resin.

[0065] The first adhesive layer may contain components derived from the first curable composition, such as unreacted (A) and (B) components. When the adhesive film of this embodiment is stored and transported in a conventional container, residual unreacted (B) component in the first adhesive layer may cause a portion of the second curable composition in the second adhesive layer to harden during storage and transport, potentially resulting in problems such as increased peeling between the circuit component and the circuit connection in a high-temperature, high-humidity environment and a reduced effect of reducing the connection resistance of the adhesive film. Therefore, to prevent these problems, the content of the (B) component in the first adhesive layer may be 15% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total mass of the first adhesive layer. The content of the (B) component in the first adhesive layer may be 0.1% by mass or more, based on the total mass of the first adhesive layer. When the first adhesive layer contains a photopolymerization initiator as the component (B), the occurrence of the above-mentioned problems can be suppressed by storing the adhesive film in a storage member described below.

[0066] The melt viscosity X of the first adhesive layer at the temperature Ty at which the second adhesive layer exhibits the minimum melt viscosity Y may be 1,000 Pa·s or more, 10,000 Pa·s or more, or 50,000 Pa·s or more, from the viewpoint of reducing the likelihood of peeling. The melt viscosity X may be 10,000,000 Pa·s or less, 1,000,000 Pa·s or less, or 500,000 Pa·s or less, from the viewpoint of achieving excellent wettability to the substrate. The melt viscosity X can be adjusted by changing the composition of the first curable composition, changing the curing conditions of the first curable composition, or the like.

[0067] The thickness of the first adhesive layer may be 0.1 times or more, 0.2 times or more, or 0.3 times or more the average particle size of the conductive particles, from the viewpoint of making it easier for the conductive particles to be trapped between electrodes and further reducing connection resistance. The thickness of the first adhesive layer 2 may be 1.0 times or less, 0.8 times or less, or 0.7 times or less the average particle size of the conductive particles, from the viewpoint of making it easier for the conductive particles to be crushed when sandwiched between opposing electrodes during thermocompression bonding and further reducing connection resistance. From these viewpoints, the thickness of the first adhesive layer may be 0.1 to 0.7 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the average particle size of the conductive particles. The thickness of the adhesive layer refers to the thickness of the adhesive layer located in the space between adjacent conductive particles. When the thickness of the first adhesive layer and the average particle size of the conductive particles satisfy the above-mentioned relationship, for example, as shown in Fig. 1, some of the conductive particles P in the first adhesive layer 13 may protrude from the first adhesive layer 13 toward the second adhesive layer 14. In this case, the boundary S between the first adhesive layer 13 and the second adhesive layer 14 is located in the space between adjacent conductive particles P. The conductive particles P are not exposed on the surface of the first adhesive layer 13 opposite the second adhesive layer 14 side, and the opposite surface may be flat.

[0068] The thickness of the first adhesive layer may be appropriately set depending on the height of the electrodes of the circuit components to be bonded, etc. The thickness of the first adhesive layer may be, for example, 0.5 μm or more and 20 μm or less. Note that if some of the conductive particles are exposed from the surface of the first adhesive layer (e.g., protruding toward the second adhesive layer), the thickness of the first adhesive layer is the distance from the surface of the first adhesive layer opposite the second adhesive layer to the boundary S between the first and second adhesive layers located in the space between adjacent conductive particles, and the exposed portions of the conductive particles are not included in the thickness of the first adhesive layer. The length of the exposed portions of the conductive particles may be, for example, 0.1 μm or more and 20 μm or less. The thickness of the adhesive layer can be measured by the following method. The adhesive film was sandwiched between two pieces of glass (thickness: approximately 1 mm) and a resin composition consisting of 100 g of bisphenol A type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (trade name: Epomount Curing Agent, manufactured by Refine Tech Co., Ltd.) was poured into the mold. The cross section was then polished using a polishing machine, and the thickness of each adhesive layer was measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Corporation).

[0069] (Second adhesive layer) The second adhesive layer is made of, for example, a second curable composition. The second curable composition contains, for example, (a) a polymerizable compound (hereinafter also referred to as component (a)) and (b) a polymerization initiator (hereinafter also referred to as component (b)). The second curable composition may be a thermosetting composition containing a thermal polymerization initiator as component (b), a photocurable composition containing a photopolymerization initiator as component (b), or a mixture of a thermosetting composition and a photocurable composition. The second curable composition constituting the second adhesive layer is an uncured curable composition that is flowable when a circuit is connected, for example, an uncured curable composition.

[0070] [Component (a): Polymerizable compound] Component (a) is a compound that polymerizes, for example, by radicals, cations, or anions generated by a polymerization initiator (photopolymerization initiator or thermal polymerization initiator) upon irradiation with light (e.g., ultraviolet light) or heating. The compounds exemplified as component (A) can be used as component (a). From the viewpoints of facilitating connection at low temperatures and in a short time, making it easier to achieve a desired melt viscosity, and further improving the effect of reducing connection resistance and providing superior connection reliability, component (a) is preferably a radically polymerizable compound having a radically polymerizable group that reacts with radicals. Examples of preferred radically polymerizable compounds and combinations of preferred radically polymerizable compounds for component (a) are the same as those for component (A). When component (a) is a radically polymerizable compound and component (B) in the first adhesive layer is a photoradical polymerization initiator, storing the adhesive film in a storage member described below tends to significantly suppress curing of the second curable composition during storage or transportation of the adhesive film.

[0071] Component (a) may be a monomer, oligomer, or polymer. As component (a), one compound may be used alone, or multiple compounds may be used in combination. Component (a) may be the same as or different from component (A).

[0072] The content of component (a) may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the second curable composition, from the viewpoint of reducing connection resistance and easily obtaining a crosslink density necessary for improving connection reliability. The content of component (a) may be 90% by mass or less, 80% by mass or less, or 70% by mass or less, based on the total mass of the second curable composition, from the viewpoint of suppressing cure shrinkage during polymerization and obtaining good reliability.

[0073] [Component (b): Polymerization initiator] As component (b), the same polymerization initiators as those exemplified as component (B) can be used. Component (b) is preferably a radical polymerization initiator. Preferred examples of radical polymerization initiators for component (b) are the same as those for component (B). As component (b), one compound may be used alone, or multiple compounds may be used in combination.

[0074] The content of component (b) may be 0.1 mass % or more, 0.5 mass % or more, or 1 mass % or more, based on the total mass of the second curable composition, from the viewpoint of facilitating connection at low temperature in a short time and achieving better connection reliability.The content of component (b) may be 30 mass % or less, 20 mass % or less, or 10 mass % or less, based on the total mass of the second curable composition, from the viewpoint of pot life.

[0075] [Other ingredients] The second curable composition may further contain other components in addition to the components (a) and (b). Examples of the other components include a thermoplastic resin, a coupling agent, a filler, a softener, an accelerator, an anti-degradant, a colorant, a flame retardant, a thixotropic agent, etc. Details of the other components are the same as those of the other components in the first adhesive layer.

[0076] The second curable composition may contain a thermosetting resin instead of or in addition to the components (a) and (b). When the second curable composition contains a thermosetting resin, the second curable composition may contain a curing agent used to cure the thermosetting resin. The thermosetting resin and curing agent may be the same as the thermosetting resin and curing agent exemplified as other components in the first curable composition. When a thermosetting resin is used instead of the components (a) and (b), the content of the thermosetting resin in the second curable composition may be, for example, 20% by mass or more and 80% by mass or less, based on the total mass of the second curable composition. When a thermosetting resin is used in addition to the components (a) and (b), the content of the thermosetting resin in the second curable composition may be, for example, 20% by mass or more and 80% by mass or less, based on the total mass of the second curable composition. The content of the curing agent may be in the same range as the content of the curing agent in the first curable composition.

[0077] The content of the conductive particles in the second adhesive layer may be, for example, 1% by mass or less, or may be 0% by mass, based on the total mass of the second adhesive layer. It is preferable that the second adhesive layer does not contain conductive particles.

[0078] The minimum melt viscosity Y of the second adhesive layer may be 50 Pa·s or more, 100 Pa·s or more, or 300 Pa·s or more, from the viewpoint of obtaining excellent blocking resistance. The minimum melt viscosity Y may be 100,000 Pa·s or less, 10,000 Pa·s or less, or 5,000 Pa·s or less, from the viewpoint of obtaining excellent filling properties (resin filling properties) between electrodes. The minimum melt viscosity Y can be adjusted by changing the composition of the second curable composition, for example.

[0079] The thickness of the second adhesive layer may be appropriately set depending on the height of the electrodes of the circuit component to be bonded, etc. The thickness of the second adhesive layer may be 5 μm or more and 200 μm or less, from the viewpoint of being able to sufficiently fill the space between the electrodes to seal the electrodes and obtain better reliability. Note that when some of the conductive particles are exposed from the surface of the first adhesive layer (for example, protruding toward the second adhesive layer), the thickness of the second adhesive layer is the distance from the surface of the second adhesive layer opposite the first adhesive layer side to the boundary S between the first adhesive layer and the second adhesive layer, which is located in the space between adjacent conductive particles.

[0080] The ratio of the thickness of the first adhesive layer 2 to the thickness of the second adhesive layer (thickness of the first adhesive layer / thickness of the second adhesive layer) may be 1 or more and 1000 or less, from the viewpoint of being able to sufficiently fill the space between the electrodes and seal the electrodes, thereby obtaining better reliability.

[0081] The thickness of the adhesive film (the total thickness of all layers constituting the adhesive film) may be, for example, 5 μm or more and 200 μm or less.

[0082] The adhesive film for circuit connection described above comprises a peelable support film and an adhesive layer provided on the support film, the adhesive layer containing an adhesive component and conductive particles, the conductive particles being unevenly distributed on the support film side and dispersed in a direction perpendicular to the thickness direction of the adhesive layer, and the adhesive layer may have, from the support film side to the thickness direction of the adhesive layer, a first region containing a cured product of the first curable composition described above and a second region containing the second curable composition described above. The ranges of the first and second regions in the thickness direction of the adhesive layer can be set in the same manner as the thicknesses of the first and second adhesive layers described above, respectively. The conductive particles can also be set in the same manner as the conditions described above.

[0083] Although the adhesive film for circuit connection of this embodiment has been described above, the present invention is not limited to the above embodiment.

[0084] [Method of manufacturing a circuit connection structure] The method for manufacturing a circuit connection structure of this embodiment is a method for manufacturing a circuit connection structure in which a first circuit member provided with a first circuit electrode and a second circuit member provided with a second circuit electrode corresponding to the first circuit electrode are connected via the above-mentioned adhesive film for circuit connection of this embodiment.

[0085] The method of the present embodiment includes, for example, a preparation step of preparing the adhesive film for circuit connection of the present embodiment described above; a laminating step of laminating the adhesive film for circuit connection onto the first circuit member such that the second adhesive layer side of the adhesive film for circuit connection faces the surface of the first circuit member on which the circuit electrodes are provided; a heating and pressurizing step of placing a second circuit member on a first circuit member laminated with an adhesive film for circuit connection so that the first circuit electrodes and the second circuit electrodes face each other, and pressurizing the first circuit member and the second circuit member in a direction in which the first circuit electrodes and the second circuit electrodes face each other while heating the adhesive film for circuit connection; Equipped with.

[0086] (preparation process) In this step, the adhesive film for circuit connection of the present embodiment described above can be produced. The method for producing an adhesive film for circuit connection of this embodiment may, for example, comprise a preparation step (first preparation step) of the above-described first adhesive layer, and a lamination step of laminating the above-described second adhesive layer on the first adhesive layer. The method for producing an adhesive film for circuit connection may further comprise a preparation step (second preparation step) of the second adhesive layer.

[0087] In the first preparation step, the first adhesive layer is prepared, for example, by forming a first adhesive layer on a support film to obtain a first adhesive film. Specifically, first, components (A), (B), and (C), as well as other components added as needed, are added to an organic solvent and dissolved or dispersed by stirring, mixing, kneading, or the like to prepare a varnish composition. The varnish composition is then applied to a release-treated substrate using a knife coater, roll coater, applicator, comma coater, die coater, or the like, and the organic solvent is then volatilized by heating to form a layer of the first curable composition on the substrate. Subsequently, the layer of the first curable composition is cured by light irradiation or heating, forming a first adhesive layer on the substrate (curing step). This results in a first adhesive film.

[0088] The organic solvent used in preparing the varnish composition is preferably one that has the property of being able to uniformly dissolve or disperse each component, and examples thereof include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, etc. These organic solvents can be used alone or in combination of two or more. The stirring, mixing, and kneading in preparing the varnish composition can be carried out using, for example, a stirrer, a kneading machine, a three-roll mill, a ball mill, a bead mill, or a homodisper.

[0089] The support film is not particularly limited as long as it has heat resistance sufficient to withstand the heating conditions used to volatilize the organic solvent when the first curable composition is cured by light. When the first curable composition is cured by heat, the support film is not particularly limited as long as it has heat resistance sufficient to withstand the heating conditions used to volatilize the organic solvent and the heating conditions used to cure the first curable composition. Examples of the support film include substrates (e.g., films) made of oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, and the like. From the viewpoint of high versatility, polyethylene terephthalate is preferably used.

[0090] The heating conditions for volatilizing the organic solvent from the varnish composition applied to the support film are preferably conditions that allow the organic solvent to volatilize sufficiently, such as at 40°C or higher and 120°C or lower for 0.1 to 10 minutes.

[0091] For the light irradiation in the curing step, it is preferable to use irradiation light (e.g., ultraviolet light) having a wavelength in the range of 150 to 750 nm. Light irradiation can be carried out using, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like. The amount of light irradiation may be adjusted so that the melt viscosity ratio (X / Y) is 10 or more. The amount of light irradiation is, for example, 100 mJ / cm2 in terms of the integrated light amount of light with a wavelength of 365 nm. 2 may be 200 mJ / cm or more, 2 may be 300 mJ / cm or more, 2 The amount of light irradiation may be, for example, 10,000 mJ / cm 2 in terms of the integrated light amount of light with a wavelength of 365 nm. 2 may be less than or equal to 5000 mJ / cm 2 may be less than or equal to 3000 mJ / cm 2The greater the amount of light irradiation (integrated amount of light), the greater the melt viscosity X tends to be, and the greater the melt viscosity ratio (X / Y) tends to be.

[0092] The heating conditions in the curing step may be adjusted so that the melt viscosity ratio (X / Y) is 10 or more. The heating conditions may be, for example, 30°C to 300°C and 0.1 to 5000 minutes, or 50°C to 150°C and 0.1 to 3000 minutes. The higher the heating temperature, the greater the melt viscosity X tends to be, and the greater the melt viscosity ratio (X / Y). Furthermore, the longer the heating time, the greater the melt viscosity X tends to be, and the greater the melt viscosity ratio (X / Y).

[0093] In the second preparation step, the second adhesive layer is formed on a substrate to obtain a second adhesive film in the same manner as in the first preparation step, except that the components (a) and (b) and other components added as needed are used, and the curing step is not performed (light irradiation and heating are not performed), thereby preparing the second adhesive layer. The substrate can be the same as the support film described above.

[0094] In the lamination process, the second adhesive layer may be laminated onto the first adhesive layer by bonding the first adhesive film and the second adhesive film together, or the second adhesive layer may be laminated onto the first adhesive layer by applying a varnish composition obtained using component (a) and component (b), as well as other components added as necessary, onto the first adhesive layer and volatilizing the organic solvent.

[0095] Examples of methods for bonding the first adhesive film and the second adhesive film include hot pressing, roll lamination, vacuum lamination, etc. Lamination may be performed under heating conditions of, for example, 0 to 80°C.

[0096] Furthermore, in this embodiment, when an adhesive film for circuit connection is used in which 90% or more of the conductive particles P are separated from other conductive particles in the first adhesive layer, such a dispersed state can be formed by the magnetic field application process described below. In this case, nickel-containing particles are preferably used as the conductive particles P from the viewpoint of performing dispersion by the magnetic field application process. Generally, iron, cobalt, and nickel are ferromagnetic materials and are known to be magnetized by an external magnetic field. Among these, the use of nickel is advantageous in that it can achieve both conductivity and dispersibility by applying a magnetic field. Furthermore, to ensure the storage stability of the conductive particles P, the surface layer of the conductive particles P may be made of a platinum group precious metal such as gold or silver instead of nickel. The surface of nickel may also be coated with a precious metal such as Au. Furthermore, non-conductive glass, ceramic, plastic, etc. coated with a conductive material such as the above metals may also be used, and in this case, a nickel layer may also be provided to form a multilayer structure.

[0097] Furthermore, because the magnetism of nickel is affected by the phosphorus concentration contained in the nickel plating, it is preferable to adjust the magnetism required for dispersing the conductive particles P using a magnetic field as needed. The magnetism of the conductive particles P can be measured, for example, by saturation magnetization using a vibrating sample magnetometer (VSM). In order to disperse the conductive particles P using an external magnetic field, it is preferable that the saturation magnetization measured by VSM be in the range of 5.0 emu / g to 50 emu / g. If the saturation magnetization is 5.0 emu / g or higher, it becomes easy to sufficiently disperse the conductive particles P. On the other hand, if the saturation magnetization is 50 emu / g or lower, the magnetization of the conductive particles P does not become too large, which prevents the conductive particles P from bonding in the thickness direction of the first adhesive layer 13, and the dispersibility of the conductive particles P tends to be improved.

[0098] The average particle size of the conductive particles P is preferably 1.0 μm or more and 10.0 μm or less. When the average particle size of the conductive particles P is 1.0 μm or more, the coating accuracy onto the support film is high, and it becomes easy to disperse the conductive particles P well in the first adhesive layer. When the average particle size of the conductive particles P is 10.0 μm or less, good insulation between adjacent circuit electrodes of the connection structure tends to be obtained. In order to obtain good dispersibility of the conductive particles P, the average particle size of the conductive particles P is more preferably 2.0 μm or more, and even more preferably 2.5 μm or more. On the other hand, from the viewpoint of ensuring insulation between adjacent circuit electrodes of the connection structure, the average particle size of the conductive particles P is more preferably 8.5 μm or less, even more preferably 7 μm or less, and even more preferably 6.0 μm or less.

[0099] The blending amount of the conductive particles P is preferably 1 to 100 parts by volume per 100 parts by volume of the components other than the conductive particles P in the first adhesive layer. From the viewpoint of preventing short-circuiting between adjacent circuit electrodes due to the presence of excessive conductive particles P, the blending amount of the conductive particles P is more preferably 10 to 50 parts by volume. Furthermore, when the average particle size of the conductive particles is in the range of 1.0 μm or more and 10.0 μm or less, the particle density of the conductive particles is more preferably 1000 particles / mm 2 More than 50000 pieces / mm 2 In this case, it is possible to more suitably achieve both the dispersibility of the conductive particles P and the insulating properties between adjacent circuit electrodes.

[0100] (Lamination process) 2 is a schematic cross-sectional view showing the laminating step in the manufacturing method of the connection structure of this embodiment. In this step, as shown in the figure, the adhesive film for circuit connection 11 is laminated onto the first circuit member 2 so that the second adhesive layer 14 side of the adhesive film for circuit connection 11 faces the surface of the first circuit member 2 on which the first circuit electrodes 6 are provided. If the adhesive film for circuit connection 11 has a release film provided on the second adhesive layer 14, the second adhesive layer 14 can be laminated onto the first circuit member 2 after or while peeling off the release film so that the second adhesive layer 14 is in close contact with the first circuit member 2.

[0101] The first circuit member 2 has circuit electrodes 6 on the mounting surface 5a side of the main body 5. Examples of the first circuit member 2 include members having flexible substrates such as COP, FCP, and polyimide. Examples of the circuit electrodes 6 include copper plated with a metal such as tin. Note that an insulating layer may be formed on the mounting surface 5a in areas where the circuit electrodes 6 are not formed.

[0102] As a means for lamination, a known laminator can be used, and the lamination conditions can be set appropriately.

[0103] FIG. 3 is a schematic cross-sectional view showing a laminate obtained through a lamination step.

[0104] (heat and pressure process) 4 is a schematic cross-sectional view showing the heating and pressurizing step in the manufacturing method of the connection structure of this embodiment. In this step, as shown in the figure, the second circuit member 3 is placed on the first circuit member 2 laminated with the circuit connection adhesive film (second adhesive layer 14 and first adhesive layer 13) so that the first circuit electrode 6 and the second circuit electrode 8 face each other, and while heating the circuit connection adhesive film (second adhesive layer 14 and first adhesive layer 13), the first circuit member 2 and the second circuit member 3 are pressed in the direction so that the first circuit electrode 6 and the second circuit electrode 8 face each other.

[0105] The second circuit member 3 is, for example, a glass substrate or plastic substrate on which a circuit is formed using ITO, IZO, or metal, which are used in liquid crystal displays, or a ceramic wiring board. As shown in Fig. 4, the second circuit member 3 has second circuit electrodes 8 corresponding to the first circuit electrodes 6 on the mounting surface 7a side of the main body 7.

[0106] The circuit electrodes 8 are, for example, rectangular in plan view and have a thickness of, for example, about 100 nm to 1000 nm. The surfaces of the circuit electrodes 8 are made of one or more materials selected from, for example, gold, silver, copper, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, indium tin oxide (ITO), and indium zinc oxide (IZO). An insulating layer may also be formed on the mounting surface 7a in areas where the circuit electrodes 8 are not formed.

[0107] A known thermocompression bonding device can be used as the heating means. The heating temperature of the circuit-connecting adhesive film (second adhesive layer 14 and first adhesive layer 13) is preferably equal to or higher than the temperature at which active polymerization species are generated in the curing agent and polymerization of the polymerization monomer is initiated. This heating temperature is, for example, 80°C to 200°C, and preferably 100°C to 180°C. The heating time is, for example, 0.1 seconds to 30 seconds, and preferably 1 second to 20 seconds. A heating temperature of 80°C or higher facilitates a sufficient curing rate, while a heating temperature of 200°C or lower prevents undesired side reactions from progressing. A heating time of 0.1 seconds or longer facilitates sufficient curing reaction, while a heating time of 30 seconds or shorter facilitates maintaining productivity of the cured product and also prevents undesired side reactions from progressing.

[0108] As the pressing means, a known thermocompression bonding device can be used. The pressure and time of pressing can be set appropriately.

[0109] 5 is a schematic cross-sectional view showing a circuit connection structure obtained through a heating and pressurizing step. In the heating and pressurizing step, the adhesive components of the circuit connection adhesive film (second adhesive layer 14 and first adhesive layer 13) flow, shortening the distance between the first circuit electrode 6 and the second circuit electrode 8 and causing the conductive particles P to interlock, and then the second adhesive layer and the first adhesive layer are cured. The curing of the second adhesive layer and the first adhesive layer electrically connects the first circuit electrode 6 and the second circuit electrode 8, and electrically insulates adjacent circuit electrodes 6, 6 from each other and adjacent circuit electrodes 8, 8 from each other, forming a cured product 4 of the circuit connection adhesive film (second adhesive layer 14 and first adhesive layer 13), thereby obtaining the circuit connection structure 1 shown in FIG. 5. In the obtained circuit connection structure 1, the cured product 4 of the circuit connection adhesive film (second adhesive layer 14 and first adhesive layer 13) sufficiently prevents the distance between the first circuit electrode 6 and the second circuit electrode 8 from changing over time, and also ensures long-term reliability of the electrical properties.

[0110] The cured product 4 of the adhesive film for circuit connection (second adhesive layer 14 and first adhesive layer 13) has a first region 9 formed by curing the first adhesive layer 13 and a second region 10 formed by curing the second adhesive layer 14. In this embodiment, the first region 9 is located on the second circuit member 3 side, and the second region 10 is located on the first circuit member 2 side.

[0111] The conductive particles P are interposed between the first circuit electrode 6 and the second circuit electrode 8 in a state where they have been slightly flattened by the pressure bonding. This achieves electrical connection between the first circuit electrode 6 and the second circuit electrode 8. Furthermore, the conductive particles P are spaced apart between adjacent first circuit electrodes 6, 6 and between adjacent second circuit electrodes 8, 8, thereby achieving electrical insulation between adjacent first circuit electrodes 6, 6 and adjacent second circuit electrodes 8, 8.

[0112] [Method of manufacturing circuit connecting adhesive film] 6 is a schematic diagram showing the manufacturing process of the adhesive film for circuit connection shown in FIG. 1. In the example shown in the figure, a long support film 12 is transported at a predetermined speed by a payout roller 21 and a take-up roller 22. A coater 23 is arranged on the transport path of the support film 12 to apply an adhesive paste W, which is the material for forming the first adhesive layer 13, and the coater 23 applies the adhesive paste W, in which conductive particles P are dispersed, onto the support film 12 (application step). The thickness of the adhesive paste W applied onto the support film 12 by the coater 23 varies depending on the proportion of solvent contained in the resin composition, but is preferably less than 1.6 times the average particle size of the conductive particles P.

[0113] The viscosity of the adhesive paste W can be varied depending on the application and application method, but is generally preferably 10 mPa·s to 10,000 mPa·s. From the viewpoint of suppressing separation of the components in the adhesive paste W and improving compatibility, a viscosity of 50 mPa·s to 5,000 mPa·s is more preferable. Furthermore, to improve the appearance of the circuit-connecting adhesive film 11, a viscosity of 100 mPa·s to 3,000 mPa·s is preferable. If the viscosity is 10,000 mPa·s or less, it becomes difficult to suppress the dispersion of the conductive particles P in the subsequent magnetic field application step, and if it is 10 mPa·s or more, separation of the components in the adhesive paste W becomes difficult.

[0114] The method for applying the adhesive paste W is not limited to the above, and known methods can be used. Examples include spin coating, roller coating, bar coating, dip coating, microgravure coating, curtain coating, die coating, spray coating, doctor coating, kneader coating, flow coating, screen printing, and casting. Bar coating, die coating, and microgravure coating are suitable for producing the circuit-connecting adhesive film 11, and microgravure coating is particularly suitable from the viewpoint of the accuracy of the film thickness.

[0115] A pair of magnets 24, 25 are arranged facing each other above and below on the rear side of the coater 23, sandwiching the support film 12. In this embodiment, as shown in Fig. 7, the magnet 24 arranged on the upper side is the north pole and the magnet 25 arranged on the lower side is the south pole, and a magnetic field is formed in a substantially vertical direction from the magnet 24 to the magnet 25. Therefore, when the support film 12 is transported between the magnets 24, 25, the conductive particles P in the adhesive paste W are magnetized, and a state is formed in which the conductive particles P, P are spaced apart in the in-plane direction of the adhesive paste W due to repulsive force (magnetic field application process).

[0116] To maintain the spacing of the conductive particles P during the magnetic field application process, the adhesive paste W is dried using hot air or the like while the support film 12 passes between the magnets 24 and 25 (drying process). This increases the viscosity of the adhesive paste W, resulting in the formation of a first adhesive layer 13 on the support film 12 in which 70% or more, preferably 90% or more, of the conductive particles P are spaced apart from adjacent conductive particles P, as shown in FIG. 8. The thickness of the adhesive paste W is reduced by the drying process. As described above, by setting the thickness of the adhesive paste W to less than 1.6 times the average particle size of the conductive particles P, it becomes easy to set the thickness of the first adhesive layer 13 to between 0.6 and 1.0 times the average particle size of the conductive particles P. Furthermore, by using an adhesive paste (varnish) diluted with an organic solvent (e.g., methyl ethyl ketone), the thickness of the adhesive layer can be reduced to approximately 0.1 times the average particle size of the conductive particles P. There are no particular restrictions on the amount of organic solvent used for dilution, but it is preferable to add 50 to 500 parts by mass per 100 parts by mass of the adhesive component.

[0117] The drying temperature of the adhesive paste W is preferably, for example, 20°C to 80°C. The conveying speed of the support film 12 is preferably, for example, 30 mm / s to 160 mm / s. The thickness of the adhesive paste W is preferably 5 μm to 10 μm when using conductive particles P with an average particle size of 3 μm. When the conveying speed of the support film 12 is 30 mm / s or more, the adhesive paste W dries in a state where the conductive particles P are sufficiently spaced apart, and therefore dispersion tends to be sufficient. When the conveying speed of the support film 12 is 160 mm / s or less, application of the magnetic field tends to end after drying, and re-aggregation of the conductive particles P can be suppressed. When the thickness of the adhesive paste W is 5 μm or more, the gap of the coater 23 can be prevented from becoming insufficient, and the number of conductive particles P in the first adhesive layer 13 can be prevented from becoming insufficient. When the thickness of the adhesive paste W is 10 μm or less, the gap of the coater 23 can be prevented from becoming excessive, and the number of conductive particles P in the first adhesive layer 13 can be prevented from becoming excessive.

[0118] After the first adhesive layer 13 is formed, as shown in FIG. 9, a second adhesive layer 14 formed separately on a release film 15 is laminated onto the first adhesive layer 13 (lamination step). This results in the adhesive film 11 for circuit connection shown in FIG. 2. Note that a hot roll laminator, for example, can be used to laminate the second adhesive layer 14. Furthermore, instead of being limited to lamination, an adhesive paste that is the material for the second adhesive layer 14 may be applied onto the first adhesive layer 13 and dried.

[0119] As described above, in the adhesive film for circuit connection 11, 70% or more, preferably 90% or more, of the conductive particles P in the first adhesive layer 13 can be spaced apart from adjacent conductive particles P. In this case, aggregation of adjacent conductive particles P is suppressed when connecting the first circuit member 2 and the second circuit member 3, thereby ensuring good insulation between adjacent first circuit electrodes 6 and between adjacent second circuit electrodes 8. Furthermore, in this adhesive film for circuit connection 11, the thickness of the first adhesive layer 13 can be set to 0.1 to 1.0 times, 0.1 to 0.7 times, or 0.6 to less than 1.0 times the average particle size of the conductive particles P. In this case, the flow of the conductive particles P during pressure bonding is suppressed, improving the efficiency of capturing the conductive particles P between the first circuit electrode 6 and the second circuit electrode 8. Therefore, the reliability of the connection between the first circuit member 2 and the second circuit member 3 can be ensured.

[0120] <Adhesive film storage set> Fig. 10 is a perspective view showing an adhesive film storage set of one embodiment. As shown in Fig. 10, the adhesive film storage set 120 includes an adhesive film 11 for circuit connection, a reel 121 around which the adhesive film 11 is wound, and a storage member 122 that stores the adhesive film 11 and the reel 121.

[0121] As shown in Fig. 10, the adhesive film 11 is, for example, in the form of a tape. The tape-shaped adhesive film 11 is produced, for example, by cutting a sheet-shaped raw material into a long piece with a width appropriate for the intended use. The adhesive film 11 may have a support film 12 on the first adhesive layer side. The support film 12 may be a substrate such as the above-mentioned PET film.

[0122] The reel 121 includes a first side plate 124 having a winding core 123 around which the adhesive film 11 is wound, and a second side plate 125 arranged opposite the first side plate 124 with the winding core 123 sandwiched therebetween.

[0123] The first side plate 124 is a circular plate made of, for example, plastic, and has an opening with a circular cross section in the center thereof.

[0124] The winding core 123 of the first side plate 124 is a portion around which the adhesive film 11 is wound. The winding core 123 is made of, for example, plastic, and has an annular shape with a thickness similar to the width of the adhesive film 11. The winding core 123 is fixed to the inner surface of the first side plate 124 so as to surround the opening of the first side plate 124. Furthermore, a shaft hole 126 is provided in the center of the reel 121, into which the rotating shaft of a winding device or a feeding device (not shown) is inserted. When the rotating shaft of the winding device or the feeding device is inserted into this shaft hole 126 and the rotating shaft is driven, the reel 121 rotates without spinning freely. A desiccant container containing a desiccant may be fitted into the shaft hole 126.

[0125] The second side plate 125, like the first side plate 124, is a circular plate made of, for example, plastic, and has an opening in the center of the second side plate 125 that has a circular cross-section and the same diameter as the opening of the first side plate 124.

[0126] The storage member 122 is, for example, bag-shaped, and stores the adhesive film 11 and the reel 121. The storage member 122 has an insertion opening 127 for storing (inserting) the adhesive film 11 and the reel 121 inside the storage member 122.

[0127] The storage member 122 has a visual confirmation portion 128 that allows the interior of the storage member 122 to be visually confirmed from the outside. The storage member 122 shown in FIG.

[0128] The visual confirmation section 128 is transparent to visible light. For example, when the light transmittance of the visual confirmation section 128 is measured in the wavelength range of 450 to 750 nm, there is at least one region with a wavelength width of 50 nm between 450 and 750 nm, where the average light transmittance is 30% or more. The light transmittance of the visual confirmation section 128 can be obtained by cutting the visual confirmation section 128 to a predetermined size to prepare a sample and measuring the light transmittance of the sample with an ultraviolet-visible spectrophotometer. Because the storage member 122 has such a visual confirmation section 128, various information inside the storage member 122, such as the product name, lot number, and expiration date affixed to the reel 121, can be confirmed from the outside of the storage member 122. This is expected to prevent the mixing of incorrect products and improve the efficiency of sorting work.

[0129] The transmittance of light with a wavelength of 365 nm through the viewing portion 128 is 10% or less. Because the transmittance of light with a wavelength of 365 nm through the viewing portion 128 is 10% or less, when a photopolymerization initiator is used as component (B), it is possible to suppress curing of the second curable composition caused by light entering from the outside to the inside of the containing member 122 and the photopolymerization initiator remaining in the first adhesive layer. From the viewpoint of further suppressing the generation of active species (e.g., radicals) from the photopolymerization initiator, the transmittance of light with a wavelength of 365 nm through the viewing portion 128 is preferably 10% or less, more preferably 5% or less, even more preferably 1% or less, and particularly preferably 0.1% or less.

[0130] From the same viewpoint, the maximum transmittance of light in the wavelength region capable of generating radicals, cations, or anions from the photopolymerization initiator (component (B)) in the visualizing portion 128 is preferably 10% or less, more preferably 5% or less, even more preferably 1% or less, and particularly preferably 0.1% or less. Specifically, the maximum transmittance of light in the wavelength region of 254 to 405 nm in the visualizing portion 128 is preferably 10% or less, more preferably 5% or less, even more preferably 1% or less, and particularly preferably 0.1% or less.

[0131] The visual confirmation section 128 (housing member 122) is formed of a sheet having a thickness of, for example, 10 to 5000 μm. The sheet is made of a material that has a transmittance of 10% or less for light with a wavelength of 365 nm in the visual confirmation section 128. Such a material may consist of a single component or multiple components. Examples of such materials include low-density polyethylene, linear low-density polyethylene, polycarbonate, polyester, acrylic resin, polyamide, and glass. These materials may contain an ultraviolet absorber. The visual confirmation section 128 may have a layered structure formed by stacking multiple layers with different light transmittances. In this case, each layer constituting the visual confirmation section 128 may be made of the above-mentioned material.

[0132] The insertion opening 127 may be sealed by being closed with a sealer or the like to prevent the intrusion of air from the outside when the product is stored. In this case, it is preferable to remove the air from inside the storage member 122 by suction before closing the insertion opening 127. This is expected to reduce humidity inside the storage member 122 from the initial stage of storage and prevent the intrusion of air from the outside. Furthermore, by closely contacting the inner surface of the storage member 122 with the surface of the reel 121, it is possible to prevent the generation of foreign matter caused by rubbing between the inner surface of the storage member 122 and the surface of the reel 121 due to vibration during transportation, and to prevent damage to the outer surfaces of the side plates 124, 125 of the reel 121.

[0133] In the above embodiment, the housing member is configured so that the entire housing member is the visible portion. However, in another embodiment, the housing member may have the visible portion only in a portion of the housing member. For example, the housing member may have a rectangular visible portion approximately in the center of a side surface of the housing member. In this case, the portion of the housing member other than the visible portion may be black so as to prevent transmission of ultraviolet light and visible light, for example.

[0134] In the above embodiment, the container is bag-shaped, but the container may be box-shaped, for example. The container preferably has a notch for easy opening, which makes it easier to open when in use. [Example]

[0135] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0136] <Method for preparing polyester urethane resin> 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were added to a heated stainless steel autoclave equipped with a stirrer, thermometer, condenser, vacuum generator, and nitrogen gas inlet tube, and 0.02 parts by mass of tetrabutoxy titanate as a catalyst was further added. The mixture was then heated to 220°C under a nitrogen stream and stirred for 8 hours. The pressure was then reduced to atmospheric pressure (760 mmHg) and cooled to room temperature. The white precipitate was then removed, washed with water, and vacuum dried to obtain a polyester polyol.

[0137] The polyester polyol obtained by the reaction of the dicarboxylic acid and diol described above was thoroughly dried, then dissolved in MEK and charged into a four-neck flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a nitrogen gas inlet tube. Furthermore, dibutyltin laurate was added as a catalyst in an amount of 0.05 parts by mass per 100 parts by mass of the polyester polyol, and 4,4'-diphenylmethane diisocyanate dissolved in MEK was added using a dropping funnel in an amount of 50 parts by mass per 100 parts by mass of the polyester polyol, and the mixture was stirred at 80°C for 4 hours to obtain the desired polyester urethane resin.

[0138] <Synthesis of polyurethane acrylate (UA1)> Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a calcium chloride drying tube, and a nitrogen gas inlet tube, 2500 parts by mass (2.50 mol) of poly(1,6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight 1000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich) were uniformly added dropwise over 3 hours. Next, after sufficient nitrogen gas was introduced into the reaction vessel, the reaction vessel was heated to 70-75°C and the mixture was allowed to react. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (Sigma-Aldrich) were added to the reaction vessel, followed by 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich). The mixture was allowed to react for 6 hours at 70°C under an air atmosphere. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of polyurethane acrylate (UA1) was 15,000. The weight-average molecular weight was measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene under the following conditions. (Measurement conditions) Equipment: Tosoh GPC-8020 Detector: Tosoh Corporation RI-8020 Column: Gelpack GLA160S+GLA150S manufactured by Hitachi Chemical Co., Ltd. Sample concentration: 120mg / 3mL Solvent: tetrahydrofuran Injection volume: 60μL Pressure: 2.94 x 10 6 Pa(30kgf / cm 2 ) Flow rate: 1.00mL / min

[0139] <Preparation of conductive particles> A nickel layer was formed on the surface of the polystyrene particles to a thickness of 0.2 μm, yielding conductive particles with an average particle size of 4 μm, a maximum particle size of 4.5 μm, and a specific gravity of 2.5.

[0140] <Preparation of Varnish (Varnish Composition) for Conductive Particle-Containing Layer> The components shown below were mixed in the amounts (parts by mass) shown in Table 1 to prepare a varnish of photocurable composition 1. The content (volume %) of conductive particles and the content (volume %) of filler shown in Table 1 are based on the total volume of the photocurable composition. (polymerizable compound) A1: Dicyclopentadiene diacrylate (trade name: DCP-A, manufactured by Toagosei Co., Ltd.) A2: Polyurethane acrylate (UA1) synthesized as described above A3: 2-Methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.) (Photopolymerization initiator) B1: B1: 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(O-benzoyloxime)] (trade name: Irgacure® OXE01, manufactured by BASF) (thermal polymerization initiator) C1: Benzoyl peroxide (product name: Niper BMT-K40, manufactured by NOF Corporation) (conductive particles) D1: Conductive particles prepared as described above (thermoplastic resin) E1: Polyester urethane resin synthesized above (coupling agent) F1: 3-methacryloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) (filling material) G1: Silica fine particles (product name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm) (solvent) H1: Methyl ethyl ketone

[0141] [Table 1]

[0142] <Preparation of Thermosetting Varnish (Varnish Composition)> The polymerizable compounds a1 to a3, thermoplastic resin e1, coupling agent f1, filler g1, and solvent h1 were the same as the polymerizable compounds A1 to A3, thermoplastic resin E1, coupling agent F1, filler G1, and solvent H1 in the photocurable composition, and these components and the thermal polymerization initiator shown below were mixed in the amounts (parts by mass) shown in Table 2 to prepare a varnish of thermosetting composition 1. The content (vol %) of the filler shown in Table 2 is based on the total volume of the thermosetting composition. (thermal polymerization initiator) c1: Benzoyl peroxide (product name: Niper BMT-K40, manufactured by NOF Corporation)

[0143] [Table 2]

[0144] Example 1 [Preparation of first adhesive film] A varnish of photocurable composition 1 was applied to a 50 μm-thick PET film using a coating device. This was followed by hot air drying at 70°C for 3 minutes, with a magnetic field simultaneously applied to form a layer of photocurable composition 1 with a thickness (after drying) of 4 μm on the PET film. The thickness was measured using a contact thickness meter. Note that the size of the conductive particles is reflected when using a contact thickness meter, and the thickness of the region where the conductive particles are present is measured. Therefore, after laminating the second adhesive layer to produce a two-layer circuit connection adhesive film, the thickness of the first adhesive layer located in the space between adjacent conductive particles was measured using the method described below. Next, the layer made of the photocurable composition 1 was exposed to a metal halide lamp with an integrated light dose of 1500 mJ / cm 2 2 The polymerizable compound was polymerized by irradiating the film with light so that the photocurable composition 1 was cured to form a first adhesive layer. The above operations resulted in a first adhesive film having a first adhesive layer with a thickness of 4 μm (the thickness of the region where the conductive particles are present) on the PET film. The conductive particle density at this time was approximately 7000 pcs / mm2 It was.

[0145] [Evaluation of monodispersity of conductive particles] The monodispersity of the conductive particles (the ratio of conductive particles separated from adjacent conductive particles (monodispersed state)) of the first adhesive film was evaluated, and the monodispersity was 70% or more. The monodispersity ratio is expressed as follows: Monodispersity ratio (%) = (2500 μm 2 Number of monodispersed conductive particles in 2500μm 2 The number of conductive particles was calculated by multiplying the number of conductive particles by 100. The number of conductive particles was measured by observing with a metallurgical microscope at a magnification of 200 times.

[0146] [Preparation of the second adhesive film] The varnish of thermosetting composition 1 was applied to a 50 μm thick PET film using a coating device. Next, hot air drying was carried out at 70°C for 3 minutes to form a second adhesive layer (a layer made of thermosetting composition 1) with a thickness of 8 μm on the PET film. Through the above operations, a second adhesive film having a second adhesive layer on the PET film was obtained.

[0147] [Preparation of adhesive film for circuit connection] The first adhesive film and the second adhesive film were laminated together with the PET film substrate using a roll laminator while being heated at 40°C. At this time, the PET film on the second adhesive film side was peeled off. This produced an adhesive film for circuit connection with a laminated structure in which the PET film, the first adhesive layer, and the second adhesive layer were laminated in this order. The thickness of the first adhesive layer of the prepared adhesive film for circuit connection was measured using the method described above. Specifically, it was measured using the following method. The adhesive film for circuit connection was sandwiched between two sheets of glass (thickness: approximately 1 mm) and a resin composition consisting of 100 g of bisphenol A epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (trade name: Epomount Curing Agent, manufactured by Refine Tech Co., Ltd.) was poured into the mold. The cross section was polished using a polishing machine, and the thickness of the first adhesive layer located in the space between adjacent conductive particles was measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Corporation). The thickness of the first adhesive layer was 2 μm.

[0148] [Fabrication of circuit connection structure] A 25 μm-pitch COF (manufactured by FLEXSEED Corp.) and a glass substrate (manufactured by Geomatec Corp.) with thin-film electrodes (height: 1200 Å) made of amorphous indium tin oxide (ITO) on the glass substrate were connected via the prepared circuit connection adhesive film over a width of 1 mm by heating and pressing at 170°C, 6 MPa, and for 4 seconds using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.), to produce a circuit connection structure (connection structure). Note that, during connection, the circuit connection adhesive film was first attached to the COF substrate from the second adhesive layer side, and after peeling off the separator, the substrate was placed facing the glass substrate and heated and pressed.

[0149] [Evaluation of circuit connection structures] The connection resistance between the opposing electrodes of the resulting circuit connection structure was measured with a multimeter immediately after connection, and the connection resistance was calculated as the average value of 16 resistance points between the opposing electrodes. Next, a 10 μm × 200 μm (= 2000 μm) 2 The number of captures in the area of ​​) was counted and the average value of 20 lines was calculated. The results are shown in Table 3. The particle dispersion after mounting was also observed under a microscope and was rated as 1 if the state before mounting was maintained, 3 if it was not maintained at all, and 2 as intermediate. 1 and 2 are at levels that pose no practical problems.

[0150] (Reference example 1) Evaluation was performed in the same manner as in Example 1, except that an adhesive film for circuit connection having a laminated structure in which the first adhesive layer, the second adhesive layer, and the PET film were laminated in this order was produced by laminating the first adhesive layer and the second adhesive layer and then peeling off the PET film on the first adhesive layer side. When connecting, the adhesive film for circuit connection was first attached to the COF substrate from the first adhesive layer side, and after peeling off the separator, it was placed opposite the glass substrate and heated and pressurized. The results are shown in Table 3.

[0151] Examples 2 and 3 Adhesive films for circuit connection and circuit connection structures were prepared in the same manner as in Example 1, except that the thickness of the first adhesive layer was changed to 1.5 μm and 3.0 μm. The prepared circuit connection structures were evaluated in the same manner as in Example 1. The results are shown in Table 3. The monodispersity of the conductive particles in the first adhesive layer was 70% or more.

[0152] [Table 3]

[0153] When the adhesive film for circuit connection obtained in Example 1 was first attached to a COF substrate and then mounted, it was found that the number of captured conductive particles was greater than in Reference Example 1, and the fluidity of the particles was also suppressed. [Explanation of symbols]

[0154] 1...circuit connection structure, 2...first circuit member, 3...second circuit member, 6...first circuit electrode, 8...second circuit electrode, 11...circuit connection adhesive film, 12, 15...support film (release film), 13...first adhesive layer, 14...second adhesive layer, P...conductive particles, W...adhesive paste.

Claims

1. The adhesive tape comprises a peelable support film, a first adhesive layer containing conductive particles provided on the support film, and an uncured second adhesive layer laminated on the first adhesive layer, the first adhesive layer is made of a photocured product of a first curable composition containing the conductive particles, a polymerizable compound, and a photopolymerization initiator; an adhesive film for circuit connection, wherein the thickness of the first adhesive layer is 0.1 to 1.0 times the average particle size of the conductive particles.

2. 2. The adhesive film for circuit connection according to claim 1, wherein the first curable composition contains, as the polymerizable compound, a radically polymerizable compound having a radically polymerizable group.

3. the second adhesive layer comprises a second curable composition; 3. The adhesive film for circuit connection according to claim 1, wherein the second curable composition contains a radically polymerizable compound having a radically polymerizable group.

4. 4. The adhesive film for circuit connection according to claim 1, wherein the ratio of the melt viscosity of the first adhesive layer at the temperature at which the second adhesive layer exhibits its minimum melt viscosity to the minimum melt viscosity of the second adhesive layer is 20 or more.

5. The adhesive film for circuit connection according to any one of claims 1 to 4, wherein the melt viscosity of the first adhesive layer at the temperature at which the second adhesive layer shows its minimum melt viscosity is 10,000 Pa·s or more.

6. 4. A method for manufacturing a circuit connection structure, comprising the steps of: interposing the first adhesive layer and the second adhesive layer of the adhesive film for circuit connection according to any one of claims 1 to 3 between a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode; and thermocompression bonding the first circuit member and the second circuit member to electrically connect the first circuit electrode and the second circuit electrode to each other.

7. the first circuit member has a flexible substrate; a laminating step of attaching the adhesive film for circuit connection to the first circuit member so that the second adhesive layer is in contact with the first circuit member; 7. The method for manufacturing a circuit connection structure according to claim 6, further comprising the steps of: after the laminating step, placing the second circuit member on the first circuit member on which the second adhesive layer and the first adhesive layer have been laminated so that the first circuit electrode and the second circuit electrode face each other; and thermocompression bonding the first circuit member and the second circuit member together.

8. An adhesive film for circuit connection according to any one of claims 1 to 5, and a housing member for housing the adhesive film, the storage member has a visual confirmation portion that allows the inside of the storage member to be visually confirmed from the outside, The adhesive film storage set has a transmittance of 10% or less for light with a wavelength of 365 nm in the visible portion.

Images