JP7764858B2 - Adhesive film for circuit connection, method for producing same, and method for producing circuit connection structure - Google Patents

Description

The present invention relates to an adhesive film for circuit connection and a method for manufacturing the same, as well as a method for manufacturing a circuit connection structure.

Traditionally, various adhesive materials have been used to make circuit connections. For example, anisotropically conductive circuit-connecting adhesive films with conductive particles dispersed in the adhesive have been used as adhesive materials for connecting liquid crystal displays and tape carrier packages (TCPs), flexible printed circuit boards (FPCs) and TCPs, or FPCs and printed wiring boards.

Adhesive films for circuit connection are typically stored laminated on a substrate. Therefore, when using an adhesive film for circuit connection to connect the above-mentioned circuit components, it is first necessary to transfer the adhesive film for circuit connection onto the circuit component. In this case, if the transferability of the adhesive film for circuit connection is insufficient, there is a concern that productivity will decrease due to longer transfer times, and that insufficient adhesion between circuits will result in increased connection resistance and reduced adhesive strength. Therefore, adhesive films for circuit connection are required to have sufficient transferability.

In the field of precision electronic devices, where anisotropically conductive adhesive films for circuit connection are used, circuits are becoming increasingly dense, with electrode widths and electrode spacing becoming extremely narrow. As a result, it is not always easy to efficiently capture conductive particles on tiny electrodes and achieve high connection reliability. In response to this, for example, Patent Document 1 proposes a method of distributing conductive particles unevenly on one side of an anisotropically conductive adhesive sheet, spacing the conductive particles apart.

WO 2005/54388

However, with the method described in Patent Document 1, the conductive particles flow when the circuit is connected, which can lead to agglomeration of the conductive particles between the electrodes and the occurrence of a short circuit. The uneven distribution of conductive particle density that accompanies the flow of conductive particles not only reduces insulation properties, but also raises concerns about variations in connection resistance values, leaving room for improvement.

In response to this issue, the inventors conducted extensive research and discovered that the flow of conductive particles during circuit connection can be suppressed by pre-curing the adhesive in areas where conductive particles are unevenly distributed. However, it became clear that this method does not provide sufficient transferability and that peeling may occur at the interface between the circuit component and the adhesive film.

The present invention therefore aims to provide an adhesive film for circuit connection that has sufficient transferability while suppressing the flow of conductive particles that occurs during the manufacture of a circuit connection structure, a method for manufacturing the same, and a method for manufacturing a circuit connection structure using the adhesive film.

One aspect of the present invention relates to an adhesive film for circuit connection as shown below.

[1] An adhesive film for circuit connection comprising a first adhesive layer and a second adhesive layer laminated on the first adhesive layer, wherein the first adhesive layer contains a cured product of a photo- and thermosetting composition, and the second adhesive layer contains a thermosetting composition, and the photo- and thermosetting composition contains a polymerizable compound, a photopolymerization initiator, a thermopolymerization initiator, conductive particles, and a thiol compound.

[2] An adhesive film for circuit connection described in [1], wherein the polymerizable compound includes a radically polymerizable compound.

[3] An adhesive film for circuit connection described in [2], wherein the radically polymerizable compound includes a (meth)acrylate compound.

[4] An adhesive film for circuit connection described in any of [1] to [3], wherein the content of the thiol compound is 0.05 to 5.0 mass %, based on the total amount of components other than conductive particles in the photo- and thermosetting composition.

[5] An adhesive film for circuit connection described in any of [1] to [4], wherein the thermosetting composition contains a radically polymerizable compound.

[6] An adhesive film for circuit connection described in any of [1] to [5], wherein the thickness of the first adhesive layer is 0.1 to 0.8 times the average particle size of the conductive particles.

The adhesive film for circuit connection described above can suppress the flow of conductive particles that occurs during the manufacture of a circuit connection structure, and can also suppress peeling at the interface between the circuit component and the adhesive film due to insufficient transferability.

The adhesive film for circuit connection described above also tends to suppress peeling at the interface between the circuit component and the circuit connection portion, which occurs when the circuit connection structure is used for a long period of time in a high-temperature, high-humidity environment (e.g., 85°C, 85% RH).

[7] A method for producing an adhesive film for circuit connection described in any one of [1] to [6], comprising a step of irradiating light onto a layer containing the photo- and thermosetting composition to cure the photo- and thermosetting composition and form the first adhesive layer.

[8] A method for manufacturing a circuit connection structure, comprising the steps of: preparing a first circuit member having a first electrode, a second circuit member having a second electrode, and a substrate-attached adhesive film for circuit connection, the substrate comprising an adhesive film for circuit connection described in any one of [1] to [6] on a substrate; transferring the adhesive film for circuit connection from the substrate to the surface of the first circuit member on which the first electrode is formed; arranging the first circuit member, the adhesive film for circuit connection, and the second circuit member in this order so that the first electrode and the second electrode face each other, and then thermocompressing the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

The present invention provides an adhesive film for circuit connection that has sufficient transferability while suppressing the flow of conductive particles that occurs during the production of a circuit connection structure, a method for producing the same, and a method for producing a circuit connection structure using the adhesive film.

FIG. 1 is a schematic cross-sectional view showing an adhesive film for circuit connection according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a circuit connection structure according to one embodiment of the present invention. 3A to 3C are schematic cross-sectional views showing the manufacturing process of a circuit connection structure according to one embodiment of the present invention.

In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. In numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. Individually described upper and lower limits may be combined in any combination. In this specification, "(meth)acrylate" refers to at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl." "(Poly)" refers to both the presence and absence of the "poly" prefix. "A or B" may include either A or B, or both. Unless otherwise specified, the materials exemplified below may be used alone or in combinations of two or more. When a composition contains multiple substances corresponding to each component, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

Below, we will explain in detail the embodiments of the present invention, occasionally referring to the drawings. However, the present invention is not limited to the following embodiments.

<Adhesive film for circuit connection>
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 1 (hereinafter also simply referred to as "adhesive film 1") comprises a first adhesive layer 2 and a second adhesive layer 3 laminated on the first adhesive layer 2.

(First adhesive layer)
The first adhesive layer 2 includes a cured product (e.g., a photocured product) of a photo- and thermosetting composition. The first adhesive layer 2 is composed of, for example, a photocured product of the photo- and thermosetting composition. However, the first adhesive layer 2 can be further cured by heating. Therefore, the first adhesive layer 2 can be said to have thermosetting properties. The first adhesive layer 2 can also be described as a cured product of a layer containing a photo- and thermosetting composition (e.g., a layer composed of a photo- and thermosetting composition). The photo- and thermosetting composition contains (A) a polymerizable compound (hereinafter also referred to as "component (A)"), (B) a photopolymerization initiator (hereinafter also referred to as "component (B)"), (C) a thermal polymerization initiator (hereinafter also referred to as "component (C)"), (D) conductive particles (hereinafter also referred to as "component (D)"), and (E) a thiol compound.

The first adhesive layer 2 is obtained, for example, by irradiating a layer containing a photo- and thermosetting composition with light energy to polymerize component (A) and cure (photocure) the photo- and thermosetting composition. Therefore, the first adhesive layer 2 includes, for example, conductive particles 4 and adhesive component 5, which is obtained by curing components of the photo- and thermosetting composition other than the conductive particles 4. Adhesive component 5 includes, for example, a polymer of component (A) and component (C). The adhesive component may also include a reaction product of component (A) or a polymer of component (A) with component (E). That is, during polymerization of component (A), component (E) may react with component (A) or a polymer of component (A), thereby incorporating component (E) into the polymer of component (A). Adhesive component 5 may or may not contain unreacted components (A), (B), and (E).

[Component (A): Polymerizable compound]
Component (A) is a compound that polymerizes, for example, by radicals, cations, or anions. Therefore, component (A) polymerizes when a photopolymerization initiator generates radicals, cations, or anions upon irradiation with light (e.g., ultraviolet light). 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) has at least one polymerizable group. From the perspective of further improving the effect of reducing connection resistance and achieving better connection reliability, the polymerizable group may be a polymerizable group that reacts with radicals (i.e., a radically polymerizable group). In other words, component (A) may be a radically polymerizable compound. Examples of radically polymerizable groups include vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenylene groups, (meth)acryloyl groups, (meth)acryloyloxy groups, and maleimide groups.

The number of polymerizable groups in component (A) may be 2 or more, from the viewpoint of easily achieving the physical properties and crosslink density necessary for reducing connection resistance after polymerization. The number of polymerizable groups in component (A) may be 10 or less, from the viewpoint of suppressing cure shrinkage during polymerization. Suppressing cure shrinkage during polymerization is preferable in that a uniform and stable film (first adhesive layer) is obtained after light irradiation. In this embodiment, to balance crosslink density and cure shrinkage, a polymerizable compound with a number of polymerizable groups within the above range may be used, and then a polymerizable compound with a number of polymerizable groups outside the above range may be additionally used.

Specific examples of 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.

(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, n-hexyl (meth)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-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl propyl (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, neopentyl glycol di(meth)acrylate, pentaerythritol (meth)acrylate, dipentaerythritol Examples of the copolymer include lithritol 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, 2,2-di(meth)acryloyloxydiethyl phosphate, and 2-(meth)acryloyloxyethyl acid phosphate.

Examples of maleimide compounds 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 such bismaleimide include panbismaleimide, N,N'-4,4-diphenyletherbismaleimide, N,N'-3,3-diphenylsulfonebismaleimide, 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-cyclohexyl)benzene, and 2,2'-bis(4-(4-maleimidophenoxy)phenyl)hexafluoropropane.

Examples of vinyl ether compounds include diethylene glycol divinyl ether, dipropylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether.

Allyl compounds include 1,3-diallyl phthalate, 1,2-diallyl phthalate, triallyl isocyanurate, etc.

Component (A) may contain a (meth)acrylate compound in order to achieve an excellent balance between the curing reaction rate and the physical properties after curing.

Component (A) may contain a (poly)urethane (meth)acrylate compound from the perspective of achieving both cohesive strength for reducing connection resistance and elongation for improving adhesive strength, thereby achieving better transferability and better adhesive properties. From the perspective of achieving even better transferability and even better adhesive properties, the content of the (poly)urethane (meth)acrylate compound may be 30% by mass or more, 50% by mass or more, or 70% by mass or more, and may be 96% by mass or less, 93% by mass or less, or 90% by mass or less, or may be 30 to 96% by mass, 50 to 93% by mass, or 70 to 90% by mass, based on the total mass of component (A).

From the perspective of improving cohesion, further reducing connection resistance, and achieving better transferability, component (A) may contain a (meth)acrylate compound having a high Tg skeleton, such as a tricyclodecane skeleton. The (meth)acrylate compound having a high Tg skeleton preferably has two or more (meth)acryloyloxy groups, and more preferably has two (meth)acryloyloxy groups (i.e., is a diacrylate). From the perspective of further improving cohesion, further reducing connection resistance, and achieving better transferability, the content of the (meth)acrylate compound having a high Tg skeleton may be 3% by mass or more, 6% by mass or more, or 9% by mass or more, and may be 30% by mass or less, 20% by mass or less, or 15% by mass or less, or may be 3 to 30% by mass, 6 to 20% by mass, or 9 to 15% by mass, based on the total mass of component (A).

From the perspective of balancing crosslink density and cure shrinkage, further reducing connection resistance, improving connection reliability, and achieving better transferability, component (A) may contain a compound (e.g., polyurethane (meth)acrylate) in which a polymerizable group such as a vinyl group, allyl group, or (meth)acryloyl group has been introduced into the end or side chain of a thermoplastic resin such as an acrylic resin, phenoxy resin, or polyurethane resin.

The weight-average molecular weight of a compound having a polymerizable group introduced into the end or side chain of a thermoplastic resin may be 3,000 or more, 5,000 or more, or 10,000 or more, from the viewpoint of achieving an excellent balance between crosslink density and cure shrinkage. The weight-average molecular weight of a compound having a polymerizable group introduced into the end or side chain of a thermoplastic resin may be 1,000,000 or less, 500,000 or less, or 250,000 or less, from the viewpoint of achieving excellent compatibility with other components (e.g., component (E)). Note that the weight-average molecular weight in this specification refers to a value measured by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene.

From the perspective of further reducing connection resistance, further improving connection reliability, and achieving even better transferability, the content of the compound having a radically polymerizable group introduced at the end or side chain of the thermoplastic resin may be 30% by mass or more, 50% by mass or more, or 70% by mass or more, and may be 96% by mass or less, 93% by mass or less, or 90% by mass or less, or may be 30 to 96% by mass, 50 to 93% by mass, or 70 to 90% by mass, based on the total mass of component (A).

The component (A) may contain a (meth)acrylate compound (a (meth)acrylate compound having a phosphate ester structure) represented by the following formula (1): In this case, the adhesive strength to the surface of an inorganic material (such as a metal) is improved, and the adhesiveness between electrodes (for example, between circuit electrodes) is improved.
In formula (1), n represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.

The (meth)acrylate compound represented by formula (1) can be obtained, for example, by reacting phosphoric anhydride with 2-hydroxyethyl (meth)acrylate. Specific examples of the (meth)acrylate compound represented by formula (1) include mono(2-(meth)acryloyloxyethyl) acid phosphate and di(2-(meth)acryloyloxyethyl) acid phosphate.

From the perspective of further improving the adhesive strength to the surface of inorganic materials (such as metals) and further improving the adhesive strength between electrodes (for example, between circuit electrodes), the content of the (meth)acrylate compound represented by formula (1) may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, and may be 20% by mass or less, 10% by mass or less, or 5% by mass or less, or may be 0.1 to 20% by mass, 0.5 to 10% by mass, or 1 to 5% by mass, based on the total mass of component (A).

From the viewpoints of further reducing connection resistance and facilitating the achievement of the crosslink density required to further improve connection reliability, and further suppressing the flow of conductive particles, the content of component (A) may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, or 40% by mass or more, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. From the viewpoints of suppressing cure shrinkage during polymerization and achieving even better transferability, the content of component (A) may be 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. From these viewpoints, the content of component (A) may be 5 to 90% by mass, 10 to 80% by mass, 20 to 70% by mass, 30 to 60% by mass, or 40 to 60% by mass, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. The above "total amount of components other than conductive particles in the photo- and thermosetting composition" does not include the amount of solvent used in forming the layer.

[Component (B): Photopolymerization initiator]
The component (B) may be a photoradical polymerization initiator, a photocationic polymerization initiator, or a photoanionic polymerization initiator. The component (B) generates radicals, cations, or anions upon irradiation with, for example, 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). The component (B) may be a photoradical polymerization initiator from the viewpoint of facilitating curing at low temperatures in a short time. As the component (B), one compound may be used alone, or multiple compounds may be used in combination.

Photoradical polymerization initiators decompose when exposed to light, generating free radicals. In other words, photoradical polymerization initiators are compounds that generate radicals when exposed to external light energy. Examples of photoradical polymerization initiators include photopolymerization initiators with structures such as oxime ester structures, bisimidazole structures, acridine structures, α-aminoalkylphenone structures, aminobenzophenone structures, N-phenylglycine structures, acylphosphine oxide structures, benzyl dimethyl ketal structures, and α-hydroxyalkylphenone structures.

As the component (B), a photopolymerization initiator having a structure represented by the following formula (I) may be used, from the viewpoint of further improving the effect of suppressing the flow of conductive particles and the effect of suppressing peeling after transfer.

The photopolymerization initiator may have multiple structures represented by formula (I). The structure represented by formula (I) may be an oxime ester structure, a bisimidazole structure, or an acridine structure. That is, the photo- and thermosetting composition may contain at least one photopolymerization initiator selected from the group consisting of photopolymerization initiators having an oxime ester structure, photopolymerization initiators having a bisimidazole structure, and photopolymerization initiators having an acridine structure. Among these, using a photopolymerization initiator having an oxime ester structure tends to further improve the effect of suppressing the flow of conductive particles and the effect of suppressing peeling after transfer.

Among compounds having an oxime ester structure, when a compound having a structure represented by the following formula (VI) is used, the above effect tends to be more pronounced.

In formula (VI), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an organic group containing an aromatic hydrocarbon group.

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), etc.

Examples of compounds having a bisimidazole structure include 2,4,5-triarylimidazole dimers such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-phenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, and 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer.

Examples of compounds having an acridine structure include 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane.

In order to further improve the effect of suppressing the flow of conductive particles, the content of the photopolymerization initiator having the structure represented by formula (I) above may be 0.1% by mass or more, 0.3% by mass or more, 0.45% by mass or more, 0.55% by mass or more, or 0.85% by mass or more, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. In order to further improve the effect of suppressing peeling after transfer, the content of the photopolymerization initiator having the structure represented by formula (I) above may be 1.2% by mass or less, 0.9% by mass or less, or 0.6% by mass or less, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. In view of these points, the content of the photopolymerization initiator having the structure represented by formula (I) above may be 0.1 to 1.2% by mass, 0.3 to 1.2% by mass, 0.45 to 0.9% by mass, or 0.45 to 0.6% by mass, based on the total amount of components other than conductive particles in the photo- and thermosetting composition.

From the viewpoint of further improving the effect of suppressing the flow of conductive particles, the content of component (B) (total content of photopolymerization initiators) may be 0.3% by mass or more, 0.45% by mass or more, 0.55% by mass or more, or 0.85% by mass or more, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. From the viewpoint of further improving the effect of suppressing peeling after transfer, the content of component (B) may be 1.2% by mass or less, 0.9% by mass or less, or 0.6% by mass or less, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. From these viewpoints, the content of component (B) may be 0.3 to 1.2% by mass, 0.45 to 0.9% by mass, or 0.45 to 0.6% by mass, based on the total amount of components other than conductive particles in the photo- and thermosetting composition.

[Component (C): Thermal Polymerization Initiator]
The component (C) may be a polymerization initiator that generates radicals, cations, or anions by heat (a thermal radical polymerization initiator, a thermal cationic polymerization initiator, or a thermal anionic polymerization initiator). From the viewpoint of further improving the effect of reducing connection resistance and achieving more excellent connection reliability, the component (C) may be a thermal radical polymerization initiator. As the component (C), one type of compound may be used alone, or multiple types of compounds may be used in combination.

A thermal radical polymerization initiator decomposes when exposed to heat to generate free radicals. In other words, a thermal radical polymerization initiator is a compound that generates radicals when exposed to external thermal energy. The thermal radical polymerization initiator can be selected from conventionally known organic peroxides and azo compounds. The thermal radical polymerization initiator may be an organic peroxide, which further improves the conductive particle flow suppression effect and the post-transfer peel suppression effect. To achieve better stability, reactivity, and compatibility, the thermal radical polymerization initiator may be an organic peroxide with a one-minute half-life temperature of 90 to 175°C and a weight-average molecular weight of 180 to 1,000. When the one-minute half-life temperature of the organic peroxide is within the above range, storage stability tends to be even better, and sufficiently high radical polymerization properties are achieved, enabling curing in a short period of time.

Specific examples of component (C) 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, and 1,1,3,3-tetramethylbutyl peroxy-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, 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, t-amylperoxyneodecanoate, di(3-methylbenzoyl)peroxy oxide, dibenzoyl peroxide, di(4-methylbenzoyl) peroxide, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzyl Examples of the organic peroxide include organic peroxides such as t-amylperoxyn-octoate, dibutylperoxytrimethyladipate, t-amylperoxynormaloctoate, t-amylperoxyisononanoate, and t-amylperoxybenzoate; and azo compounds such as 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).

From the viewpoint of excellent fast-curing properties, and further improving the effect of suppressing the flow of conductive particles and the effect of suppressing peeling after transfer, the content of component (C) may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total amount of adhesive components (components other than conductive particles in the cured product of the photo- and thermosetting composition). From the viewpoint of pot life, the content of component (C) may be 20% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total amount of adhesive components (components other than conductive particles in the cured product of the photo- and thermosetting composition). Note that the content of component (C) based on the total amount of components other than conductive particles in the photo- and thermosetting composition may be the same as the above-mentioned range, and the content of component (C) based on the total amount of components other than conductive particles in the first adhesive layer may also be the same as the above-mentioned range.

[(D) Component: Conductive particles]
The component (D) 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. The component (D) may also be a coated conductive particle comprising a core containing non-conductive glass, ceramic, or plastic (such as polystyrene), and a coating layer containing the metal or conductive carbon that coats the core. Among these, when using metal particles formed of a heat-fusible metal or coated conductive particles comprising a core containing plastic and a coating layer containing a metal or conductive carbon that coats the core, it becomes easier to deform the cured product of the photo- and thermosetting composition by heating or pressure. Therefore, when electrically connecting electrodes, the contact area between the electrodes and the component (D) can be increased, further improving the conductivity between the electrodes.

Component (D) 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 particles. When component (D) is an insulating-coated conductive particle, even if the content of component (D) is high, the particle surface is coated with resin, which can suppress the occurrence of short circuits due to contact between components (D), and can also improve the insulation between adjacent electrode circuits. Component (D) can be one type of the various conductive particles described above, or a combination of two or more types.

The maximum particle size of component (D) is preferably smaller than the minimum electrode spacing (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (D) 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 (D) may be 50 μm or less, 30 μm or less, or 20 μm or less. From these viewpoints, the maximum particle size of component (D) may be 1.0 to 50 μm, 2.0 to 30 μm, or 2.5 to 20 μm. 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 (D). Note that if component (D) is not spherical due to the presence of protrusions or other reasons, the particle size of component (D) is defined as the diameter of a circle circumscribing the conductive particle in the SEM image.

From the viewpoint of excellent dispersibility and conductivity, the average particle size of component (D) 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 (D) may be 50 μm or less, 30 μm or less, or 20 μm or less. From these viewpoints, the average particle size of component (D) may be 1.0 to 50 μm, 2.0 to 30 μm, or 2.5 to 20 μm. 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 obtained particle sizes is defined as the average particle size.

The component (D) may be uniformly dispersed in the first adhesive layer 2. From the viewpoint of easily obtaining a stable connection resistance, the particle density of the component (D) in the first adhesive layer 2 may be 100 pcs/mm2 or ^more , 1000 pcs/ ^mm2 or more, or 2000 pcs/ ^mm2 or more. From the viewpoint of improving the insulation between adjacent electrodes, the particle density of the component (D) in the first adhesive layer 2 may be 100,000 pcs/ ^mm2 or less, 50,000 pcs/ ^mm2 or less, or 10,000 pcs/ ^mm2 or less.

From the viewpoint of further improving conductivity, the content of component (D) may be 5% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the photo- and thermosetting composition. From the viewpoint of easily suppressing short circuits, the content of component (D) may be 50% by mass or less, 40% by mass or less, or 30% by mass or less, based on the total mass of the photo- and thermosetting composition. From these viewpoints, the content of component (D) may be 5 to 50% by mass, 10 to 40% by mass, or 20 to 30% by mass, based on the total mass of the photo- and thermosetting composition. The content of component (D) based on the total mass of the cured product of the photo- and thermosetting composition may be the same as the above-mentioned range, and the content of component (D) based on the total mass of the first adhesive layer may also be the same as the above-mentioned range.

The content of component (D) may be 0.1 vol% or more, 1 vol% or more, or 5 vol% or more, based on the total volume of the cured product of the photo- and thermosetting composition, from the viewpoint of further improving conductivity. The content of component (D) may be 50 vol% or less, 30 vol% or less, or 20 vol% or less, based on the total volume of the cured product of the photo- and thermosetting composition, from the viewpoint of easily suppressing short circuits. The content of component (D) based on the total volume of the photo- and thermosetting composition may be the same as the above-mentioned range, and the content of component (D) based on the total volume of the first adhesive layer may also be the same as the above-mentioned range.

[Component (E): Thiol compound]
The component (E) is a compound having at least one thiol group. By using the component (E), it is possible to achieve both sufficient transferability and suppression of the flow of conductive particles.

The reason why the above effect is achieved is not clear, but one possible reason is that component (E) functions as an accelerator for the polymerization reaction of component (A), allowing the photocuring of the photo- and thermosetting composition to proceed quickly and sufficiently, and as a result, the photo- and thermosetting composition can be cured to an extent that suppresses the flow of conductive particles without impairing transferability.

Component (E) may be a monomer or an oligomer. Component (E) may be used alone or in combination with multiple types. For example, component (E) may be a combination of a monomer and an oligomer.

Component (E) may be a thiol compound having one thiol group (monofunctional thiol compound) or a thiol compound having multiple thiol groups (polyfunctional thiol compound). In particular, when component (E) is a polyfunctional thiol compound, component (E) also functions as a crosslinker during curing (polymerization of component (A)), resulting in the formation of a crosslinked structure (-C-S-C-) derived from component (E). Therefore, when a polyfunctional thiol compound is used as component (E), a cured product tends to be obtained that has flexibility that does not interfere with transferability, while also having a high crosslink density that further suppresses the flow of conductive particles. To more easily achieve this effect, the number of thiol groups may be one or more, two or more, or four or more. On the other hand, to more easily achieve superior transferability, the number of thiol groups may be 12 or less, or 10 or less. From these perspectives, the number of thiol groups may be 1 to 12, 2 to 10, or 4 to 10.

The thiol group contained in component (E) may be a primary thiol group, a secondary thiol group, or a tertiary thiol group. From the viewpoint of achieving a better balance between transferability and suppression of conductive particle flow, the thiol group contained in component (E) may be a secondary or tertiary thiol group (a thiol group to which the carbon atom bonded is a secondary or tertiary carbon atom). When component (E) is a polyfunctional thiol compound, from the viewpoint of achieving a better balance between transferability and suppression of conductive particle flow, all of the thiol groups may be secondary or tertiary thiol groups.

Examples of monofunctional thiol compounds include 2-mercaptobenzothiazole, 2-methyl-4,5-dihydrofuran-3-thiol, 3-mercapto-1-hexanol, mercaptomethylbutanol, 3-mercapto-2-methylpentanol, 3-mercapto-3-methylbutanol, 4-ethoxy-2-methyl-2-butanethiol, hexanethiol, isobutylthiol, 1,1-dimethylheptanethiol, 2-ethylhexyl-3-mercaptopropionate, n-octyl-3-mercaptopropionate, methoxybutyl-3-mercaptopropionate, and stearyl-3-mercaptopropionate.

Examples of polyfunctional thiol compounds include pentaerythritol tetrakis(3-mercaptobutyrate), ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, tris-[(3-mercaptobutyryloxy)-ethyl]-isocyanurate, tetraethylene glycol bis(3-mercaptopropionate), and 1,4-bis(3-mercaptobutyryloxy)butane.

From the viewpoint of further improving the flexibility of the cured product and making it easier to obtain superior transferability, the component (E) may have a pentaerythritol skeleton represented by the following formula (2).

From the viewpoint of achieving an even better balance between transferability and suppression of flow of conductive particles, the component (E) having a pentaerythritol skeleton may be a compound represented by the following formula (3).

In formula (3), R ²¹ , R ²² , R ²³ , and R ²⁴ each independently represent an alkyl group which may be substituted with a thiol group. However, at least one of R ²¹ , R ²² , R ²³ , and R ²⁴ has a thiol group bonded to a carbon atom having 0, 1, or 2 hydrogen atoms bonded thereto. All of R ²¹ , R ²² , R ²³ , and R ²⁴ may have thiol groups bonded to carbon atoms having 0, 1, or 2 hydrogen atoms bonded thereto. The alkyl group may have, for example, 1 to 10 carbon atoms. Specific examples of the alkyl group which may be substituted with a thiol group include a 2-mercaptoethyl group, a 2-mercaptopropyl group, a 2-mercapto-2-methyl-propyl group, and a 3-mercaptobutyl group.

A specific example of a compound represented by formula (3) is pentaerythritol tetrakis(3-mercaptobutyrate).

From the viewpoint of further improving the flexibility of the cured product and making it easier to obtain superior transferability, the component (E) may be a compound represented by the following formula (4).

In formula (4), L represents a linking group. The linking group is, for example, a divalent hydrocarbon group, preferably an alkylene group (also known as an alkanediyl group). The divalent hydrocarbon group has, for example, 1 to 10 carbon atoms, preferably 3 to 6 carbon atoms. Specific examples of divalent hydrocarbon groups include ethylene, propylene, butylene, pentylene, and hexylene groups.

In formula (4), R ³¹ and R ³² each independently represent an alkyl group which may be substituted with a thiol group. However, at least one of R ³¹ and R ³² has a thiol group bonded to a carbon atom having 0, 1, or 2 hydrogen atoms bonded thereto. Both R ³¹ and R ³² may have a thiol group bonded to a carbon atom having 0, 1, or 2 hydrogen atoms bonded thereto. The alkyl group may have, for example, 1 to 10 carbon atoms. Specific examples of the alkyl group which may be substituted with a thiol group include a 2-mercaptoethyl group, a 2-mercaptopropyl group, a 2-mercapto-2-methyl-propyl group, and a 3-mercaptobutyl group.

Specific examples of compounds represented by formula (3) include tetraethylene glycol bis(3-mercaptopropionate) and 1,4-bis(3-mercaptobutyryloxy)butane.

The molecular weight of component (E) may be 150 or more, 200 or more, or 250 or more, from the viewpoint of suppressing volatilization during the drying step in the manufacturing process when used as a film-like adhesive. The molecular weight of component (E) may be 5000 or less, 3000 or less, or 1500 or less, from the viewpoint of improving compatibility with other components. From these viewpoints, the molecular weight of component (E) may be 150 to 5000, 200 to 3000, or 250 to 1500.

From the viewpoint of further improving the effect of suppressing the flow of conductive particles, the content of component (E) may be 0.05% by mass or more, 0.5% by mass or more, 1.0% by mass or more, or 1.5% by mass or more, based on the total amount of components other than conductive particles in the photo- and thermosetting composition. From the viewpoint of further improving transferability and further improving the effect of suppressing peeling after a high-temperature, high-humidity test, the content of component (E) may be 5.0% by mass or less, 3.0% by mass or less, 2.5% by mass or less, or 2.0% by mass or less. From these viewpoints, the content of component (E) may be 0.05 to 5.0% by mass, 0.05 to 3.0% by mass, 0.5 to 3.0% by mass, 0.5 to 2.0% by mass, 1.0 to 2.0% by mass, or 1.5 to 2.0% by mass, based on the total amount of components other than conductive particles in the photo- and thermosetting composition.

In order to achieve an even better balance between transferability and suppression of the flow of conductive particles, the total number of moles of thiol groups in component (E) contained in the photo- and thermosetting composition may be 0.05 or more, 0.1 or more, or 0.15 or more, and may be 0.5 or less, 0.4 or less, or 0.3 or less, or may be 0.05 to 0.5, 0.1 to 0.4, or 0.15 to 0.3, relative to the total number of moles of polymerizable groups in component (A) contained in the photo- and thermosetting composition (for example, the total number of moles of (meth)acryloyl groups in component (A)).

[Other ingredients]
The photo- and thermosetting composition may further contain components other than the components described above. Examples of the other components include a thermoplastic resin, a coupling agent, a filler, etc. These components may be contained in the first adhesive layer 2.

Examples of thermoplastic resins include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, and acrylic rubber. When the photo- and thermosetting composition contains a thermoplastic resin, the first adhesive layer can be easily formed. When the photo- and thermosetting composition contains a thermoplastic resin, stress in the first adhesive layer that occurs during curing of the photo- and thermosetting composition can be alleviated. When the thermoplastic resin has functional groups such as hydroxyl groups, the adhesiveness of the first adhesive layer is likely to be improved. From this perspective, phenoxy resin may be used as the thermoplastic resin. The content of the thermoplastic resin may be 5% by mass or more, 80% by mass or less, or 5 to 80% by mass, based on the total amount of components other than the conductive particles in the photo- and thermosetting composition.

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 (e.g., 3-(meth)acryloyloxypropyltrimethoxysilane), silane compounds such as tetraalkoxysilane, tetraalkoxytitanate derivatives, and polydialkyltitanate derivatives. When the photo- and thermosetting composition contains a coupling agent, adhesion can be further improved. The content of the coupling agent may be 0.1% by mass or more and 20% by mass or less, based on the total amount of components other than the conductive particles in the photo- and thermosetting composition. Note that, in this specification, silane coupling agents having polymerizable groups such as (meth)acryloyl groups are not considered to be polymerizable compounds.

Examples of fillers include non-conductive fillers (non-conductive particles, etc.). When the photo- and thermosetting composition contains a filler, further improvement in connection reliability can be expected. The filler may be either an inorganic or organic filler. Examples of inorganic fillers 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 organic fillers 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 may be less than the minimum diameter of the conductive particles 4. The content of the filler may be 1% by volume or more, or 30% by volume or less, or 1 to 30% by volume, based on the total volume of the photo- and thermosetting composition.

The photo- and thermosetting composition may contain other additives such as softeners, accelerators, anti-degradants, colorants, flame retardants, and thixotropic agents. The content of these additives may be 0.1 to 10 mass % based on the total amount of components other than the conductive particles in the photo- and thermosetting composition. These additives may also be contained in the first adhesive layer 2.

The thickness d1 of the first adhesive layer 2 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 4, from the viewpoint of making it easier for the conductive particles 4 to be trapped between opposing electrodes and further reducing connection resistance. The thickness d1 of the first adhesive layer 2 may be 0.8 times or less, or 0.7 times or less the average particle size of the conductive particles 4, from the viewpoint of making it easier for the conductive particles 4 to be crushed when sandwiched between opposing electrodes during thermocompression bonding and further reducing connection resistance. From these viewpoints, the thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the average particle size of the conductive particles 4. The thickness d1 of the first adhesive layer 2 refers to the thickness of the first adhesive layer located in the space between adjacent conductive particles 4, 4.

When the thickness d1 of the first adhesive layer 2 and the average particle size of the conductive particles 4 satisfy the above relationship, as shown in FIG. 1, some of the conductive particles 4 in the first adhesive layer 2 may protrude from the first adhesive layer 2 toward the second adhesive layer 3. In this case, the boundary S between the first adhesive layer 2 and the second adhesive layer 3 is located at the space between adjacent conductive particles 4. The presence of the boundary S on the conductive particles (along the surface of the conductive particles) may prevent the conductive particles 4 in the first adhesive layer 2 from protruding from the first adhesive layer 2 toward the second adhesive layer 3, thereby satisfying the above relationship. The conductive particles 4 may not be exposed on the surface 2a of the first adhesive layer 2 opposite the second adhesive layer 3, and the opposite surface 2a may be flat.

The relationship between the thickness d1 of the first adhesive layer 2 and the maximum particle size of the conductive particles 4 may be the same as the relationship between the thickness d1 of the first adhesive layer 2 and the average particle size of the conductive particles 4. The thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the maximum particle size of the conductive particles 4.

The thickness d1 of the first adhesive layer 2 may be set appropriately depending on the height of the electrodes of the circuit components to be bonded. The thickness d1 of the first adhesive layer 2 may be 0.5 μm or more and 20 μm or less. If a portion of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (e.g., protruding toward the second adhesive layer 3), the distance from the surface 2a of the first adhesive layer 2 opposite the second adhesive layer 3 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3, located between adjacent conductive particles 4, 4 (the distance indicated by d1 in FIG. 1), is the thickness of the first adhesive layer 2. The exposed portions of the conductive particles 4 (portions not covered by the first adhesive layer 2) are not included in the thickness of the first adhesive layer 2. The length of the exposed portions of the conductive particles 4 may be 0.1 μm or more and 20 μm or less, and may be 0.1 to 20 μm.

The thickness of the adhesive layer can be measured using the following method. First, the adhesive film is sandwiched between two pieces of glass (thickness: approximately 1 mm). Next, a resin composition consisting of 100 g of bisphenol A epoxy resin (product name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (product name: Epomount Curing Agent, manufactured by Refine Tech Co., Ltd.) is poured into the mold. The cross section is then polished using a polishing machine, and the thickness of each adhesive layer is measured using a scanning electron microscope (SEM, product name: SE-8020, manufactured by Hitachi High-Tech Science Corporation).

(Second adhesive layer)
The second adhesive layer 3 includes, for example, a thermosetting composition containing (a) a polymerizable compound (hereinafter also referred to as component (a)) and (b) a thermal polymerization initiator (hereinafter also referred to as component (b)). The second adhesive layer 3 is composed of, for example, a thermosetting composition. The thermosetting composition constituting the second adhesive layer 3 is a thermosetting composition that can flow when connecting circuits, and is, for example, an uncured thermosetting composition.

[Component (a): Polymerizable compound]
Component (a) is, for example, a compound that polymerizes by the action of radicals, cations, or anions generated by a thermal polymerization initiator due to heat. The compounds exemplified as component (A) can be used as component (a). From the viewpoints of facilitating connection at low temperatures in a short time, further improving the effect of reducing connection resistance, and providing superior connection reliability, component (a) may be a radically polymerizable compound having a radically polymerizable group that reacts with radicals. Examples of radically polymerizable compounds and combinations thereof are the same as those for component (A).

Component (a) may be a monomer, oligomer, or polymer. As component (a), a single 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).

From the viewpoint of easily achieving the crosslink density required to reduce connection resistance and improve connection reliability, 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 thermosetting composition. From the viewpoint of suppressing cure shrinkage during polymerization and achieving good 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 thermosetting composition. From these viewpoints, the content of component (a) may be 10 to 90% by mass, 20 to 80% by mass, or 30 to 70% by mass, based on the total mass of the thermosetting composition.

[Component (b): Thermal Polymerization Initiator]
The thermal polymerization initiators exemplified as the component (C) can be used as the component (b). As the component (b), one type of compound may be used alone, or multiple types of compounds may be used in combination. From the viewpoint of further improving the effect of reducing connection resistance and achieving more excellent connection reliability, the component (b) may be a thermal radical polymerization initiator. Examples of the thermal radical polymerization initiator for the component (b) are the same as those for the component (C).

From the viewpoint of further improving the effect of reducing connection resistance and achieving better connection reliability, the content of component (b) may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total mass of the thermosetting composition. From the viewpoint of pot life, the content of component (b) may be 30% by mass or less, 20% by mass or less, or 10% by mass or less, based on the total mass of the thermosetting composition. From these viewpoints, the content of component (b) may be 0.1 to 30% by mass, 0.5 to 20% by mass, or 1 to 10% by mass, based on the total mass of the thermosetting composition.

[Other ingredients]
The thermosetting 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 2.

The second adhesive layer 3 (thermosetting composition) may not contain a photopolymerization initiator and conductive particles 4. The content of the photopolymerization initiator in the second adhesive layer 3 may be 1% by mass or less, 0.1% by mass or less, or 0% by mass, based on the total mass of the second adhesive layer 3. The content of the conductive particles 4 in the second adhesive layer 3 may be 1% by mass or less, or 0% by mass, based on the total mass of the second adhesive layer.

The thickness d2 of the second adhesive layer 3 may be set appropriately depending on the height of the electrodes of the circuit components to be bonded. From the viewpoint of being able to sufficiently fill the space between the electrodes and seal them, and thus obtaining better connection reliability, the thickness d2 of the second adhesive layer 3 may be 5 μm or more, 200 μm or less, or 5 to 200 μm. Note that if some of the conductive particles 4 are exposed from the surface of the first adhesive layer 2 (e.g., protruding toward the second adhesive layer 3), the thickness of the second adhesive layer 3 is the distance (d2 in FIG. 1) from the surface 3a of the second adhesive layer 3 opposite the first adhesive layer 2 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3, which is located between adjacent conductive particles 4, 4.

The ratio of the thickness d1 of the first adhesive layer 2 to the thickness d2 of the second adhesive layer 3 (thickness d1 of the first adhesive layer 2/thickness d2 of the second adhesive layer 3) may be 1 or more, 100 or less, or between 1 and 100, from the viewpoint of being able to sufficiently fill the space between the electrodes and seal the electrodes, thereby achieving better reliability.

The thickness of the adhesive film 1 (the sum of the thicknesses of all layers constituting the adhesive film 1; in Figure 1, the sum of the thickness d1 of the first adhesive layer 2 and the thickness d2 of the second adhesive layer 3) may be 5 μm or more, may be 200 μm or less, or may be 5 to 200 μm.

In the adhesive film 1, conductive particles 4 are dispersed in the first adhesive layer 2. Therefore, the adhesive film 1 is an anisotropically conductive adhesive film with anisotropic conductivity. The adhesive film 1 is interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and is used to electrically connect the first electrode and the second electrode to each other by thermocompression bonding the first circuit member and the second circuit member.

Adhesive film 1 can suppress the flow of conductive particles that occurs during the manufacture of a circuit connection structure. Adhesive film 1 can also suppress peeling at the interface between the circuit component and adhesive film 1 due to insufficient transferability. Adhesive film 1 also tends to suppress peeling at the interface between the circuit component and the circuit connection component that occurs when the circuit connection structure is used in a high-temperature, high-humidity environment.

The above describes the adhesive film for circuit connection of this embodiment, but the present invention is not limited to the above embodiment.

For example, the adhesive film for circuit connection may be composed of two layers, a first adhesive layer and a second adhesive layer, or may be composed of three or more layers, including a layer other than the first adhesive layer and the second adhesive layer (e.g., a third adhesive layer). The third adhesive layer may be a layer having the same composition as the first adhesive layer or the second adhesive layer described above, and may be a layer having the same thickness as the first adhesive layer or the second adhesive layer described above.

The adhesive film for circuit connection in the above embodiment is an anisotropic conductive adhesive film having anisotropic conductivity, but the adhesive film for circuit connection may also be a conductive adhesive film that does not have anisotropic conductivity.

<Method of manufacturing an adhesive film for circuit connection>
The method for producing an adhesive film for circuit connection 1 of this embodiment comprises, for example, a preparation step (first preparation step) of preparing the above-described first adhesive layer 2, and a lamination step of laminating the above-described second adhesive layer 3 on the first adhesive layer 2. The method for producing an adhesive film for circuit connection 1 may further comprise a preparation step (second preparation step) of preparing the second adhesive layer 3. The order in which the first preparation step and the second preparation step are performed is not limited, and either the first preparation step or the second preparation step may be performed first.

In the first preparation step, the first adhesive layer 2 is prepared, for example, by forming the first adhesive layer 2 on a substrate to obtain a first adhesive film. Specifically, first, components (A), (B), (C), and (D), as well as other components added as needed, are added to a solvent (organic solvent) and dissolved or dispersed by stirring, mixing, kneading, or the like to prepare a varnish composition (a varnish-like photo- and thermosetting composition). The varnish composition is then applied to a release-treated substrate using a knife coater, roll coater, applicator, comma coater, die coater, or the like, and the solvent is then volatilized by heating to form a layer containing the photo- and thermosetting composition on the substrate. Next, the layer containing the photo- and thermosetting composition is irradiated with light to cure (photo-cure) the photo- and thermosetting composition, forming the first adhesive layer 2 on the substrate (curing step). This results in a first adhesive film.

The solvent used in preparing the varnish composition may be one that has the ability to uniformly dissolve or disperse each component. Examples of such solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These solvents can be used alone or in combination of two or more. The stirring, mixing, and kneading used in preparing the varnish composition can be performed using, for example, a mixer, a kneading machine, a three-roll mill, a ball mill, a bead mill, or a homodisper.

There are no particular restrictions on the substrate, as long as it is heat-resistant enough to withstand the heating conditions required to evaporate the solvent. For example, 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, etc. can be used.

The heating conditions for volatilizing the solvent from the varnish composition applied to the substrate may be such that the solvent is sufficiently volatilized. The heating conditions may be 40°C or higher and 120°C or lower for 0.1 minutes or longer and 10 minutes or shorter.

A portion of the solvent may remain in the layer containing the photo- and thermosetting composition. The solvent content in the layer containing the photo- and thermosetting composition may be 10% by mass or less, based on the total mass of the layer containing the photo- and thermosetting composition.

For the light irradiation in the curing step, irradiation light having a wavelength in the range of 150 to 750 nm (e.g., ultraviolet light) may be used. 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, an LED light source, or the like. The amount of light irradiation is not particularly limited, and may be 100 mJ/cm ² or more, 200 mJ/cm ² or more, or 300 mJ/cm 2 or more in terms of the integrated light amount of light with a wavelength of 365 nm. The amount of light irradiation may be 10,000 mJ/cm ² or less, 5,000 mJ/cm ² or less, or 3,000 mJ/cm ² or less in terms of the integrated light amount of light with a ^wavelength of 365 nm.

In the second preparation step, the second adhesive layer 3 is prepared by forming the second adhesive layer 3 on the substrate to obtain a second adhesive film, in the same manner as in the first preparation step, except that components (a) and (b) and other components added as necessary are used and light irradiation is not performed.

Some of the solvent may remain unremoved in the second adhesive layer 3. The solvent content in the second adhesive layer 3 may be 10% by mass or less, based on the total mass of the second adhesive layer 3.

In the lamination process, the second adhesive layer 3 may be laminated on the first adhesive layer 2 by bonding the first adhesive film and the second adhesive film together, or the second adhesive layer 3 may be laminated on the first adhesive layer 2 by applying a varnish composition obtained using components (a) and (b), as well as other components added as necessary, to the first adhesive layer 2 and volatilizing the solvent.

Methods for bonding the first adhesive film and the second adhesive film include, for example, hot pressing, roll lamination, and vacuum lamination. Lamination may be performed at a temperature of 0 to 80°C.

<Circuit connection structure and method for manufacturing the same>
Hereinafter, a circuit connection structure using the above-described adhesive film for circuit connection 1 as the circuit connecting material and a method for producing the same will be described.

2 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. As shown in FIG. 2, the circuit connection structure 10 includes a first circuit board 11 and a first circuit member 13 having a first electrode 12 formed on the main surface 11a of the first circuit board 11, a second circuit board 14 and a second circuit member 16 having a second electrode 15 formed on the main surface 14a of the second circuit board 14, and a circuit connection portion 17 disposed between the first circuit member 13 and the second circuit member 16, electrically connecting the first electrode 12 and the second electrode 15 to each other.

The first circuit member 13 and the second circuit member 16 may be the same or different. The first circuit member 13 and the second circuit member 16 may be a glass or plastic substrate on which electrodes are formed, a printed wiring board, a ceramic wiring board, a flexible wiring board, a semiconductor silicon IC chip, or the like. The first circuit board 11 and the second circuit board 14 may be formed from inorganic materials such as semiconductors, glass, and ceramics, organic materials such as polyimide and polycarbonate, and composites such as glass/epoxy. The first electrode 12 and the second electrode 15 may be formed from gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), or the like. The first electrode 12 and the second electrode 15 may be circuit electrodes or bump electrodes. At least one of the first electrode 12 and the second electrode 15 may be a bump electrode. In Fig. 2, the second electrode 15 is a bump electrode.

The circuit connection portion 17 includes the cured product of the adhesive film 1 described above. The circuit connection portion 17 includes, for example, a first region 18 located on the first circuit member 13 side in the direction in which the first circuit member 13 and the second circuit member 16 face each other (hereinafter referred to as the "facing direction") and made of a cured product of components other than the conductive particles 4 of the photo- and thermosetting composition described above; a second region 19 located on the second circuit member 16 side in the facing direction and made of a cured product of the thermosetting composition described above; and conductive particles 4 interposed between at least the first electrode 12 and the second electrode 15 to electrically connect the first electrode 12 and the second electrode 15 to each other. The circuit connection portion does not have to have two regions, such as the first region 18 and the second region 19. The circuit connection portion may also include a region where a cured product of components other than the conductive particles 4 of the photo- and thermosetting composition described above and a cured product of the thermosetting composition described above are mixed.

The manufacturing method for the circuit connection structure 10 described above includes, for example, the steps of preparing a first circuit member 13 having a first electrode 12, a second circuit member 16 having a second electrode 15, and a substrate-attached adhesive film (substrate-attached adhesive film for circuit connection) having an adhesive film (adhesive film for circuit connection) 1 on a substrate; transferring (laminating) the adhesive film 1 from the substrate onto the surface of the first circuit member 13 on which the first electrode 12 is formed; and arranging the first circuit member 13, adhesive film 1, and second circuit member 16 in this order so that the first electrode 12 and the second electrode 15 face each other, and then thermocompressing the first circuit member 13 and the second circuit member 16 to electrically connect the first electrode 12 and the second electrode 15 to each other.

Specifically, first, a first circuit board 11 and a first circuit member 13 having a first electrode 12 formed on the main surface 11a of the first circuit board 11, a second circuit board 14 and a second circuit member 16 having a second electrode 15 formed on the main surface 14a of the second circuit board 14, and a substrate-attached adhesive film having an adhesive film 1 on a substrate are prepared. The substrate of the substrate-attached adhesive film may be the substrate used in manufacturing the adhesive film described above.

Next, the adhesive film 1 is transferred (laminated) from the substrate onto the surface of the first circuit member 13 on which the first electrode 12 is formed. Specifically, for example, the adhesive film 1 is laminated onto the first circuit member 13 so that the first adhesive layer 2 side faces the main surface (mounting surface) 11a of the first circuit member 13.

There are no particular restrictions on the lamination method, but roll laminators, diaphragm laminators, vacuum roll laminators, and vacuum diaphragm laminators can be used. After pre-lamination, the layers may be pressed using a thermocompression device.

The lamination conditions may be set appropriately depending on the type of laminator, substrate, first circuit member 13, second circuit member 16, etc. used. The temperature during lamination (compression temperature) may be 50 to 90°C. The pressure during lamination (compression pressure) may be 0.5 to 1.5 MPa. The lamination time (compression time) may be 0.5 to 1.5 seconds.

Next, as shown in Figure 3(a), a second circuit member 16 is placed on the first circuit member 13 laminated with the adhesive film 1 so that the first electrode 12 and the second electrode 15 face each other.

3(b), the first circuit member 13 and the second circuit member 16 are heated while being pressed against each other in the thickness direction, thereby thermocompressing the first circuit member 13 and the second circuit member 16 together. During this process, as indicated by the arrows in FIG. 3(b), the second adhesive layer 3 contains a flowable, uncured thermosetting composition, so it flows to fill the gaps between the second electrodes 15, 15 and hardens due to the heating. As a result, the first electrode 12 and the second electrode 15 are electrically connected to each other via the conductive particles 4, and the first circuit member 13 and the second circuit member 16 are bonded to each other, resulting in the circuit connection structure 10 shown in FIG. 2. In the method for producing the circuit connection structure 10 of this embodiment, the first adhesive layer 2 is a pre-cured layer, so the conductive particles 4 hardly flow during the thermocompression bonding and are efficiently captured between the opposing electrodes, thereby reducing the connection resistance between the opposing electrodes (between the first electrode 12 and the second electrode 15). As a result, a circuit connection structure with excellent connection reliability can be obtained.

The temperature and time during thermocompression bonding may be any temperature that sufficiently cures the adhesive film 1 and bonds the first circuit member 13 and the second circuit member 16. The thermocompression bonding temperature may be 150 to 200°C. The thermocompression bonding time may be 4 to 7 seconds.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

<Synthesis of polyurethane acrylate (UA1)>
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 Co.) were uniformly added dropwise over 3 hours to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a calcium chloride drying tube, and a nitrogen gas inlet tube. Next, nitrogen gas was sufficiently introduced into the reaction vessel, and the reaction vessel was then heated to 70 to 75°C to allow the mixture to react. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (Sigma-Aldrich) were added to a reaction vessel, followed by the addition of 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich), and the mixture was allowed to react for 6 hours at 70°C 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)
Apparatus: GPC-8020 manufactured by Tosoh Corporation
Detector: Tosoh Corporation RI-8020
Column: Gelpack GLA160S + GLA150S manufactured by Hitachi Chemical Co., Ltd.
Sample concentration: 120mg/3mL
Solvent: tetrahydrofuran Injection volume: 60 μL
Pressure: 2.94×10 ⁶ Pa (30 kgf/cm ² )
Flow rate: 1.00mL/min

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

<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 mixture was then depressurized to atmospheric pressure (760 mmHg) and cooled to room temperature. This resulted in the precipitation of a white precipitate. The white precipitate was then removed, washed with water, and vacuum-dried to obtain a polyester polyol. The resulting polyester polyol was thoroughly dried and then dissolved in MEK (methyl ethyl ketone) and placed in a four-neck flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a nitrogen gas inlet tube. Dibutyltin dilaurate was added as a catalyst in an amount of 0.05 parts by mass per 100 parts by mass of polyester polyol, and 4,4'-diphenylmethane diisocyanate in an amount of 50 parts by mass per 100 parts by mass of polyester polyol was dissolved in MEK and added using a dropping funnel, followed by stirring at 80°C for 4 hours to obtain the desired polyester urethane resin.

<Preparation of First Varnish Composition (Varnish-like Photo- and Thermosetting Composition)>
First varnish compositions 1 to 9 were prepared by mixing the components shown below in the amounts (parts by mass) shown in Table 1. The "thiol compound content" shown in Table 1 is the content based on the total amount of components other than the conductive particles and solvent in the varnish composition.

[Polymerizable compound]
A1: Diacrylate having a tricyclodecane skeleton (trade name: DCP-A, manufactured by Kyoeisha Chemical 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: 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(O-benzoyloxime)] (trade name: Irgacure (registered trademark) 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 [thiol compound]
E1: Pentaerythritol tetrakis(3-mercaptobutyrate) (trade name: Karenz MTPE1 ("Karenz MT" is a registered trademark; the same applies hereinafter), manufactured by Showa Denko K.K.)
E2: 1,4-bis(3-mercaptobutyryloxy)butane (trade name: Karenz MTBD1, manufactured by Showa Denko K.K.)
[Thermoplastic resin]
F1: Phenoxy resin (product name: PKHC, manufactured by Union Carbide Corporation)
[Coupling agent]
G1: 3-methacryloyloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.)
[Filling material]
H1: Silica fine particles (product name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm)
[solvent]
I1: Methyl ethyl ketone

<Preparation of second varnish composition (varnish-like thermosetting composition)>
The polymerizable compounds a1 to a3, thermal polymerization initiator b1, coupling agent d1, filler e1, and solvent f1 used were the same as the polymerizable compounds A1 to A3, thermal polymerization initiator C1, coupling agent G1, filler H1, and solvent I1 in the photo- and thermosetting composition, and the thermoplastic resin c1 used was the component shown below. These components were mixed in the blending amounts (parts by mass) shown in Table 2 to prepare a second varnish composition.
(thermoplastic resin)
c1: Polyester urethane resin synthesized as described above

Example 1
[Preparation of First Adhesive Film]
The first varnish 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, forming a layer of the photo- and thermosetting composition with a thickness of 4 μm (thickness after drying) on the PET film. The thickness was measured using a contact thickness gauge. Next, the layer of the photo- and thermosetting composition was irradiated with light using a metal halide lamp at an integrated light dose of 1500 mJ/ ^cm2 , polymerizing the polymerizable compound. This cured the photo- and thermosetting composition, forming a first adhesive layer. Through these operations, a first adhesive film was obtained on the PET film, comprising a first adhesive layer (thickness of the region where the conductive particles were present: 4 μm). The conductive particle density at this time was approximately 7000 pcs/ ^mm2 . Note that if the thickness of the first adhesive layer is smaller than the thickness (diameter) of the conductive particles, measuring the layer thickness using a contact thickness gauge will reflect the thickness of the conductive particles, and the thickness of the region where the conductive particles were present will be measured. Therefore, after producing a two-layer adhesive film for circuit connection in which a first adhesive layer and a second adhesive layer were laminated, the thickness of the first adhesive layer located in the space between adjacent conductive particles was measured using the method described below.

[Preparation of second adhesive film]
The second varnish composition 1 was applied to a 50 μm-thick PET film using a coating device. The film was then dried with hot air at 70°C for 3 minutes to form an 8 μm-thick second adhesive layer (a layer made of a thermosetting composition) on the PET film. This procedure resulted in a second adhesive film having a second adhesive layer on the PET film.

[Preparation of adhesive film for circuit connection]
The first adhesive film and the second adhesive film were arranged so that their adhesive layers faced each other, and were laminated together with the PET film substrate using a roll laminator while being heated at 40° C. This produced an adhesive film for circuit connection with a PET film, which had a two-layer structure in which the first adhesive layer and the second adhesive layer were laminated.

The thickness of the first adhesive layer of the prepared circuit-connecting adhesive film was measured using the following method. First, the circuit-connecting adhesive film was sandwiched between two sheets of glass (thickness: approximately 1 mm) and a resin composition consisting of 100 g of bisphenol A epoxy resin (product name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (product 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 the first adhesive layer located between adjacent conductive particles was measured using a scanning electron microscope (SEM, product name: SE-8020, manufactured by Hitachi High-Tech Science Corporation). The thickness of the first adhesive layer was 2 μm.

[Evaluation of transferability]
A glass substrate with thin-film electrodes (manufactured by Geomatec Co., Ltd.) was prepared, which had a thin-film electrode (height: 1200 Å) made of amorphous indium tin oxide (ITO) on the glass substrate. Next, the PET film on the first adhesive layer side of the PET film-attached circuit connection adhesive film obtained above was peeled off, and the circuit connection adhesive film was transferred onto the glass substrate with thin-film electrodes. Specifically, using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.), heating and pressurization were performed at 80°C and 1 MPa for 1 second, thereby bonding the first adhesive layer side of the circuit connection adhesive film to the thin-film electrode side of the glass substrate with thin-film electrodes over a width of 1 mm. Next, the PET film on the second adhesive layer side was peeled off, and the interface between the glass substrate and the circuit connection adhesive film was observed under a microscope from the glass substrate side, and the transfer state of the circuit connection adhesive film to the glass substrate was evaluated using a three-point scale. The percentage of the total area of the adhesive film for circuit connection that was peeled off from the glass substrate was determined, and those with almost no peeling (less than 5% of the total) were rated A, those with a small amount of peeling (5% to less than 20% of the total) were rated B, and those with significant peeling (20% or more of the total) were rated C. The results are shown in Table 3.

[Fabrication of circuit connection structure]
A 25 μm pitch COF (manufactured by FLEXSEED) and a glass substrate (manufactured by Geomatec Co., Ltd.) with thin-film electrodes (height: 1200 Å) made of amorphous indium tin oxide (ITO) on the glass substrate were connected over a width of 1 mm using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.) at 170 ° C., 6 MPa, and 4 seconds to produce a circuit connection structure (connection structure). During connection, the circuit connection adhesive film was laminated onto the glass substrate so that the surface of the circuit connection adhesive film facing the first adhesive layer faced the glass substrate. Lamination was performed using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.) at 80 ° C., 1 MPa, and 1 second.

[Evaluation of particle flowability]
The resulting circuit connection structure was evaluated for particle flow in the resin exuded portion of the circuit connection adhesive film using a microscope (product name: ECLIPSE L200, manufactured by Nikon Corporation). Specifically, the produced circuit connection structure was observed with a microscope from the glass substrate side, and the particle state in the portion that exuded outside the width of the circuit connection adhesive film was evaluated on a three-point scale. A state in which the particles barely moved and there were no particles in the exuded portion was evaluated as 1; a state in which the particles moved slightly but no connection between particles was observed was evaluated as 2; and a state in which the particles flowed and connection between particles was observed was evaluated as 3. The results are shown in Table 3.

[Peeling evaluation]
The presence or absence of peeling at the circuit connection portion of the circuit connection structure after the high-temperature, high-humidity test was evaluated using a microscope (product name: ECLIPSE L200, manufactured by Nikon Corporation). Specifically, the circuit connection structure prepared as described above was first placed in a constant temperature and humidity chamber at 85°C and 85% RH for 200 hours to perform the high-temperature, high-humidity test. Next, the circuit connection portion of the circuit connection structure after the high-temperature, high-humidity test was observed using a microscope from the glass substrate side, and the peeling state at the interface between the glass substrate and the circuit connection adhesive film was evaluated using a three-point scale. The percentage of the entire area of the circuit connection adhesive film that was peeled from the glass substrate was determined, and A was assigned to cases where almost no peeling occurred (the peeled portion accounted for less than 5% of the total), B to cases where slight peeling occurred (the peeled portion accounted for 5% to 20% of the total), and C to cases where peeling occurred (the peeled portion accounted for 20% or more of the total). The results are shown in Table 3.

(Examples 2 to 7 and Comparative Examples 1 and 2)
The preparation of adhesive films for circuit connection and circuit connection structures, as well as the evaluation of transferability, particle fluidity, and peelability, were carried out in the same manner as in Example 1, except that first varnish compositions 2 to 9 were used instead of first varnish composition 1. The results are shown in Table 3.

1...adhesive film for circuit connection, 2...first adhesive layer, 3...second adhesive layer, 4...conductive particles, 10...circuit connection structure, 12...circuit electrode (first electrode), 13...first circuit member, 15...bump electrode (second electrode), 16...second circuit member.

Claims (7)

a first adhesive layer; and
a second adhesive layer laminated on the first adhesive layer,
the first adhesive layer comprises a cured product of a photo- and thermosetting composition;
the second adhesive layer comprises a thermosetting composition;
the photo- and thermosetting composition contains a polymerizable compound, a photopolymerization initiator, a thermal polymerization initiator, conductive particles, and a thiol compound ;
The adhesive film for circuit connection , wherein the content of the thiol compound is 0.05 to 2.0 mass % based on the total amount of components other than the conductive particles in the photo- and thermosetting composition . The adhesive film for circuit connection according to claim 1, wherein the polymerizable compound includes a radically polymerizable compound. The adhesive film for circuit connection according to claim 2, wherein the radically polymerizable compound includes a (meth)acrylate compound. The adhesive film for circuit connection according to any one of claims 1 to 3 , wherein the thermosetting composition contains a radically polymerizable compound. 5. The adhesive film for circuit connection according to claim 1, wherein the thickness of the first adhesive layer is 0.1 to 0.8 times the average particle size of the conductive particles. A method for producing an adhesive film for circuit connection according to any one of claims 1 to 5 , comprising:
A method for manufacturing an adhesive film for circuit connection, comprising a step of irradiating light onto a layer containing the photo- and thermosetting composition to harden the photo- and thermosetting composition and form the first adhesive layer. A step of preparing a first circuit member having a first electrode, a second circuit member having a second electrode, and a substrate-attached adhesive film for circuit connection comprising the adhesive film for circuit connection according to any one of claims 1 to 5 on a substrate;
transferring the adhesive film for circuit connection from the substrate onto a surface of the first circuit member on which the first electrodes are formed;
and a step of arranging the first circuit member, the circuit connection adhesive film, and the second circuit member in this order so that the first electrode and the second electrode face each other, and then thermocompression bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.