JP2022039384A - Adhesive film for circuit connection and method for producing the same, and method for producing circuit connection structure - Google Patents

Abstract

To prevent peeling at an interface between a circuit member and a circuit connection, which occurs in the case where a circuit connection structure is used in high-temperature and high-humidity conditions, while improving the rate of catching conductive particles in the production of the circuit connection structure.SOLUTION: An adhesive film for circuit connection 1 has a first adhesive layer 2, and a second adhesive layer 3 deposited on the first adhesive layer 2. The first adhesive layer 2 is composed of a cured product of a photoradical curable composition containing a photoradical sensitizer and conductive particles 4. The second adhesive layer 3 is composed of a thermosetting composition.SELECTED DRAWING: Figure 1

Description

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

Conventionally, various adhesive materials have been used for circuit connection. For example, as an adhesive material for connecting a liquid crystal display to a tape carrier package (TCP), a flexible printed wiring board (FPC) to TCP, or an FPC to a printed wiring board, conductive particles in an adhesive. An adhesive film for circuit connection having an anisotropic conductivity in which is dispersed is used.

In the field of precision electronic devices in which an adhesive film for circuit connection having anisotropic conductivity is used, the density of circuits is increasing, and the electrode width and the electrode spacing are extremely narrow. Therefore, it is not always easy to efficiently capture conductive particles on microelectrodes and obtain high connection reliability.

On the other hand, for example, Patent Document 1 proposes a method in which conductive particles are unevenly distributed on one side of an anisotropic conductive adhesive sheet to separate the conductive particles from each other.

International Publication No. 2005/54388

However, in the method of Patent Document 1, since the conductive particles flow when the circuit is connected, a part of the conductive particles may not be captured between the counter electrodes. Therefore, as the circuit becomes higher in definition, there is a concern that conduction failure may occur due to insufficient capture of conductive particles, and there is still room for improvement.

Further, as a result of the study by the present inventors, by pre-curing the adhesive in the region where the conductive particles are unevenly distributed, the flow of the conductive particles at the time of circuit connection can be suppressed, and the capture rate of the conductive particles can be suppressed. Although it has been found that (the ratio of conductive particles captured between counter electrodes) can be improved, in this method, when the circuit connection structure is used in a high temperature and high humidity environment (for example, 85 ° C., 85% RH). , Peeling may occur at the interface between the circuit member and the circuit connection portion formed by the adhesive film.

Therefore, the present invention has a circuit member and a circuit connection portion that are generated when the circuit connection structure is used in a high temperature and high humidity environment while improving the capture rate of conductive particles at the time of manufacturing the circuit connection structure. One purpose is to suppress the peeling at the interface of.

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

[1] A first adhesive layer and a second adhesive layer laminated on the first adhesive layer are provided, and the first adhesive layer includes a photoradical sensitizer and conductive particles. The second adhesive layer is an adhesive film for circuit connection, which comprises a cured product of a photoradical curable composition containing and a thermosetting composition.

[2] The adhesive film for circuit connection according to [1], wherein the thermosetting composition is a thermosetting composition.

[3] The content of the photoradical sensitizer is 0.001 to 1.0% by mass based on the total amount of components other than the conductive particles in the photoradical curable composition [1]. Or the adhesive film for circuit connection according to [2].

[4] The content of the photoradical sensitizer is 0.001 to 1.0% by mass based on the total amount of components other than the conductive particles in the cured product, [1] or [2]. Adhesive film for circuit connection described in.

[5] The circuit connection according to any one of [1] to [4], wherein the thickness of the first adhesive layer is 0.1 to 0.8 times the average particle size of the conductive particles. Adhesive film.

According to the adhesive film for circuit connection on the above side surface, the circuit connection structure is in a high temperature and high humidity environment (for example, 85 ° C., 85% RH) while improving the capture rate of conductive particles at the time of manufacturing the circuit connection structure. It is possible to suppress the peeling at the interface between the circuit member and the circuit connection portion, which occurs when the circuit member is used in the above. Further, according to the adhesive film for circuit connection on the above side surface, there is a tendency that the connection resistance between the facing electrodes of the circuit connection structure can be reduced, and it is possible to reduce the connection resistance in a high temperature and high humidity environment (for example, 85 ° C., 85% RH). ), It tends to be possible to maintain a low connection resistance. That is, according to the circuit connection adhesive film on the side surface, there is a tendency that the connection reliability of the circuit connection structure can be improved.

Another aspect of the present invention is the method for producing an adhesive film for circuit connection according to any one of [1] to [5], wherein light is applied to a layer made of the photoradical curable composition. The present invention relates to a method for producing an adhesive film for circuit connection, which comprises a step of curing the photoradical curable composition by irradiation to form the first adhesive layer.

Another aspect of the present invention is described in any of [1] to [5] between the first circuit member having the first electrode and the second circuit member having the second electrode. A step of electrically connecting the first electrode and the second electrode to each other by thermally crimping the first circuit member and the second circuit member with an adhesive film for circuit connection interposed therebetween. The present invention relates to a method of manufacturing a circuit connection structure.

According to the present invention, the circuit member and the circuit connection portion generated when the circuit connection structure is used in a high temperature and high humidity environment while improving the capture rate of conductive particles at the time of manufacturing the circuit connection structure. It is possible to suppress peeling at the interface of.

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings in some cases, but the present invention is not limited to these embodiments. In the present specification, the numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. In addition, the upper limit value and the lower limit value described individually can be arbitrarily combined. Further, as used herein, the term "(meth) acrylate" means at least one of acrylate and the corresponding methacrylate. The same applies to other similar expressions such as "(meth) acryloyl". Further, "(poly)" means both with and without the prefix of "poly".

<Adhesive film for circuit connection>
FIG. 1 is a schematic cross-sectional view showing an adhesive film for circuit connection according to an embodiment. As shown in FIG. 1, the circuit connection adhesive film 1 (hereinafter, also simply referred to as “adhesive film 1”) is laminated on the first adhesive layer 2 and the first adhesive layer 2. A second adhesive layer 3 is provided.

(First adhesive layer)
The first adhesive layer 2 is made of a cured product (photo-cured product) of a photoradical curable composition. The photoradical curable composition is a composition that cures by a radical polymerization reaction by irradiation with light. The photoradical curable composition is, for example, (A) a radically polymerizable compound (hereinafter, also referred to as “(A) component”), (B) a photoradical polymerization initiator (hereinafter, also referred to as “(B) component”). ), (C) Photoradical sensitizer (hereinafter, also referred to as “(C) component”) and (D) Conductive particles 4 (hereinafter, also referred to as “(D) component”).

In the first adhesive layer 2, for example, the component (A) is polymerized by irradiating a layer made of a photoradical curable composition with light energy to cure the photoradical curable composition (photocuring). Obtained by letting it. That is, the first adhesive layer 2 is composed of, for example, conductive particles 4 and an adhesive component 5 obtained by curing components other than the conductive particles 4 of the photoradical curable composition. The adhesive component 5 contains at least the polymer of the component (A) and the component (C). The adhesive component 5 may or may not contain the unreacted components (A) and (B).

The photoradical curable composition may have thermosetting property. The photoradical curable composition may further contain, for example, (E) a thermal radical polymerization initiator.

[Component (A): radically polymerizable compound]
The component (A) is, for example, a compound polymerized by a radical generated by a photoradical polymerization initiator by irradiation with light (for example, ultraviolet light). The component (A) may be any of a monomer, an oligomer or a polymer. As the component (A), one kind of compound may be used alone, or a plurality of kinds of compounds may be used in combination.

The component (A) has at least one polymerizable group (radical polymerizable group) that reacts with a radical. Examples of the radically polymerizable group include a vinyl group, an allyl group, a styryl group, an alkenyl group, an alkenylene group, a (meth) acryloyl group, a maleimide group and the like.

The number of radically polymerizable groups contained in the component (A) may be 2 or more from the viewpoint that the physical properties necessary for reducing the connection resistance and the crosslink density can be easily obtained after the polymerization, and the curing shrinkage during the polymerization can be prevented. From the viewpoint of suppressing, it may be 10 or less. Suppressing the curing shrinkage during polymerization is preferable in that a uniform and stable film (first adhesive layer) can be obtained after light irradiation. In the present embodiment, in order to balance the crosslink density and the curing shrinkage, a radically polymerizable compound having a number of radically polymerizable groups within the above range is used, and the number of radically polymerizable groups is outside the above range. Radical polymerizable compounds may be additionally used.

Specific examples of the component (A) include (meth) acrylate compound, maleimide compound, vinyl ether compound, allyl compound, styrene derivative, acrylamide derivative, nadiimide derivative, natural rubber, isoprene rubber, butyl rubber, nitrile rubber, butadiene rubber, and styrene-. Examples thereof include butadiene rubber, acrylonitrile-butadiene rubber, and carboxylated nitrile rubber.

Examples of the (meth) acrylate compound include epoxy (meth) acrylate, (poly) urethane (meth) acrylate, methyl (meth) acrylate, polyether (meth) acrylate, polyester (meth) acrylate, polybutadiene (meth) acrylate, and 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 ( Meta) 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 (meth) acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylol propanetri (meth) acrylate, tetramethylol methanetetra (meth) acrylate, polyethylene glycol di. (Meta) acrylate, polyalkylene glycol di (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol (Meta) acrylate, dipentaerythritol hexa (meth) acrylate, isocyanuric acid-modified bifunctional (meth) acrylate, isocyanuric acid-modified trifunctional (meth) acrylate, tricyclodecanyl acrylate, dimethylol-tricyclodecanediacrylate, 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, 2- (meth) a Examples thereof include cryloyloxyethyl acid phosphate and the like.

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, N, N'-4,4- Diphenylpropane bismaleimide, N, N'-4,4-diphenylether bismaleimide, N, N'-3,3-diphenylsulfone bismaleimide, 2,2-bis (4- (4-maleimidephenoxy) phenyl) propane, 2,2-bis (3-s-butyl-4-8 (4-maleimidephenoxy) phenyl) propane, 1,1-bis (4- (4-maleimidephenoxy) phenyl) decane, 4,4'-cyclohexili Examples thereof include den-bis (1- (4 maleimide phenoxy) -2-cyclohexyl) benzene, 2,2'-bis (4- (4-maleimide phenoxy) phenyl) hexafluoropropane and the like.

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

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

The component (A) may be a (meth) acrylate compound from the viewpoint of excellent balance between the curing reaction rate and the physical properties after curing. The component (A) is a (poly) urethane (meth) acrylate compound from the viewpoint of achieving both cohesive force for reducing connection resistance and elongation for improving adhesive force and obtaining better adhesive properties. It's okay. Further, the component (A) may be a (meth) acrylate compound having a high Tg skeleton such as a tricyclodecane skeleton from the viewpoint of improving the cohesive force and further reducing the connection resistance.

The component (A) is the terminal or side of a thermoplastic resin such as an acrylic resin, a phenoxy resin, or a polyurethane resin from the viewpoint of balancing the crosslink density and the curing shrinkage, further reducing the connection resistance, and improving the connection reliability. It may be a compound (for example, polyurethane (meth) acrylate) in which a polymerizable group such as a vinyl group, an allyl group, or a (meth) acryloyl group is introduced into the chain. In this case, the weight average molecular weight of the component (A) may be 3000 or more, may be 5000 or more, and may be 10,000 or more from the viewpoint of excellent balance between the crosslink density and the curing shrinkage. Further, the weight average molecular weight of the component (A) may be 1 million or less, 500,000 or less, or 250,000 or less from the viewpoint of excellent compatibility with other components. The weight average molecular weight is a value measured by a gel permeation chromatograph (GPC) using a calibration curve made of standard polystyrene according to the conditions described in Examples.

式（１）中、ｎは１～３の整数を示し、Ｒは、水素原子又はメチル基を示す。 The component (A) may contain, as the (meth) acrylate compound, a radically polymerizable compound having a phosphoric acid ester structure represented by the following formula (1). In this case, since the adhesive strength to the surface of the inorganic substance (metal or the like) is improved, it is suitable for adhesion between electrodes (for example, circuit electrodes).

In formula (1), n represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group.

The radically polymerizable compound having the phosphoric acid ester structure can be obtained, for example, by reacting anhydrous phosphoric acid with 2-hydroxyethyl (meth) acrylate. Specific examples of the radically polymerizable compound having a phosphoric acid ester structure include mono (2- (meth) acryloyloxyethyl) acid phosphate, di (2- (meth) acryloyloxyethyl) acid phosphate and the like.

The content of the component (A) is the total amount of the components other than the conductive particles in the photoradical curable composition from the viewpoint that the crosslink density required for reducing the connection resistance and improving the connection reliability can be easily obtained. May be 5% by mass or more, 10% by mass or more, and 20% by mass or more. The content of the component (A) may be 90% by mass or less, and may be 80% by mass, based on the total amount of the components other than the conductive particles in the photoradical curable composition from the viewpoint of suppressing the curing shrinkage during polymerization. % Or less, and may be 70% by mass or less.

[Component (B): Photopolymerization Initiator]
The component (B) is radicalized by irradiation with light having a wavelength in the range of 150 to 750 nm, preferably light having a wavelength in the range of 254 to 405 nm, and more preferably light having a wavelength in the range of 365 nm (for example, ultraviolet light). , A photopolymerization initiator (photoradical polymerization initiator, photocationic polymerization initiator or photoanionic polymerization initiator) that generates a cation or anion. The component (B) may be a photoradical polymerization initiator from the viewpoint of facilitating curing at a low temperature for a short time. As the component (B), one kind of compound may be used alone, or a plurality of kinds of compounds may be used in combination.

The photoradical polymerization initiator is decomposed by light to generate free radicals. That is, the photoradical polymerization initiator is a compound that generates radicals by applying light energy from the outside. Examples of the photoradical polymerization initiator include an oxime ester structure, a bisimidazole structure, an acrydin structure, an α-aminoalkylphenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzyldimethylketal structure, and an α-hydroxy. Examples thereof include a photopolymerization initiator having a structure such as an alkylphenone structure.

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 flow suppressing effect of the conductive particles and the peeling suppressing effect. The photopolymerization initiator may have a plurality of structures represented by the above formula (I).

The structure represented by the above formula (I) may be an oxime ester structure, a bisimidazole structure or an acridine structure. That is, the photoradical curable composition contains a photopolymerization initiator having at least one structure selected from the group consisting of an oxime ester structure, a bisimidazole structure and an acridine structure as the structure represented by the above formula (I). You can do it. Among these, a photopolymerization initiator having an oxime ester structure may be used from the viewpoint of further improving the flow suppressing effect of the conductive particles and the peeling suppressing effect.

式（ＶＩ）中、Ｒ^１１、Ｒ^１２及びＲ^１３は、それぞれ独立して、水素原子、炭素数１～２０のアルキル基、又は芳香族系炭化水素基を含む有機基を示す。 As the compound having an oxime ester structure, a compound having a structure represented by the following formula (VI) may be used.

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

Specific examples of the compound having an oxime ester structure include 1-phenyl-1,2-butandion-2- (o-methoxycarbonyl) oxime and 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-diphenylpropantrione- 2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxypropanetrione-2- (o-benzoyl) oxime, 1,2-octanedione, 1- [4- (phenylthio) phenyl-, 2-( o-benzoyloxime)], etanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl]-, 1- (o-acetyloxime) and the like.

Examples of the compound having a bisimidazole structure include 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer and 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, 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, etc. Included are 2,4,5-triarylimidazole dimers.

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

The content of the photopolymerization initiator having the structure represented by the above formula (I) is the total amount of the components other than the conductive particles in the photoradical curable composition from the viewpoint of further improving the flow suppressing effect of the conductive particles. As a reference, it may be 0.1% by mass or more, 0.3% by mass or more, 0.45% by mass or more, or 0.55% by mass or more. The content of the photopolymerization initiator having the structure represented by the above formula (I) is based on the total amount of components other than the conductive particles in the photoradical curable composition from the viewpoint of further improving the effect of suppressing peeling. , 1.0% by mass or less, 0.9% by mass or less, or 0.6% by mass or less. From these viewpoints, the content of the photopolymerization initiator having the structure represented by the above formula (I) is 0.1 to 1 based on the total amount of the components other than the conductive particles in the photoradical curable composition. It may be 0.0% by mass, 0.3 to 0.9% by mass or 0.45 to 0.6% by mass.

The content of the component (B) is the total amount of the components other than the conductive particles in the photoradical curable composition from the viewpoint of further improving the flow suppressing effect of the conductive particles. As a reference, it may be 0.1% by mass or more, 0.3% by mass or more, 0.45% by mass or more, or 0.55% by mass or more. The content of the component (B) is 1.0% by mass or less, 0.9, based on the total amount of the components other than the conductive particles in the photoradical curable composition, from the viewpoint of further improving the effect of suppressing peeling. It may be 0% by mass or less than 0.6% by mass. From these viewpoints, the content of the component (B) is 0.1 to 1.0% by mass and 0.3 to 0% by mass based on the total amount of the components other than the conductive particles in the photoradical curable composition. It may be 9% by mass or 0.45 to 0.6% by mass.

[Component (C): Photoradical sensitizer]
The component (C) is a substance that plays a role in assisting the reaction or luminescence process by transferring the energy obtained by absorbing light to another substance. In the present invention, it is a compound capable of enhancing the activity of a photoradical polymerization initiator by a photosensitizing action, and is a benzophenone-based photoradical sensitizer, m-dicyanobenzene-based photoradical sensitizer, and anthracene-based photoradical sensitizer. Agents, radical sensitizers such as Rose Bengal and the like are known. By using the component (C), the conductive particles are captured between the counter electrodes at a high rate while suppressing the occurrence of peeling at the interface between the circuit member and the circuit connection portion in a high temperature and high humidity environment. be able to. As the component (C), one kind of compound may be used alone, or a plurality of kinds of compounds may be used in combination.

The component (C) is an anthracene-based photoradical sensitizer from the viewpoint of further improving the capture rate of conductive particles and further suppressing peeling at the interface between the circuit member and the circuit connection portion in a high temperature and high humidity environment. It may be there.

The anthracene-based photoradical sensitizer has the following formula (2) from the viewpoint of further improving the capture rate of conductive particles and further suppressing the peeling at the interface between the circuit member and the circuit connection portion in a high temperature and high humidity environment. It may be a compound having a structure represented by.

In formula (2), R ²¹ and R ²² each independently represent an alkyl group or an acyl.

The alkyl group has, for example, 1 to 10 carbon atoms and may be 2 to 8 or 3 to 6 carbon atoms. The alkyl group may be linear or branched. Examples of the alkyl group include a butyl group, an isopropyl group, a pentyl group, an isobutyl group and the like.

The acyl group is, for example, a group represented by —C (O) R ²³ (where R ²³ represents an alkyl group). The number of carbon atoms of the alkyl group represented by R ²³ is, for example, 1 to 12, and may be 3 to 10 or 5 to 8. The alkyl group may be linear or branched. Examples of the alkyl group include an octyl group, a nonyl group, a decyl group and the like.

The compound represented by the above formula (2) has a viewpoint of further improving the capture rate of conductive particles and further suppressing peeling at the interface between the circuit member and the circuit connection portion in a high temperature and high humidity environment. It may be 10-bis (octanoyloxy) anthracene, 9,10-dibutoxyanthracene.

From the viewpoint of further improving the capture rate of the conductive particles, the content of the component (C) is 0.001% by mass or more, 0. It may be 005% by mass or more, 0.01% by mass or more, 0.025% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.07% by mass or more, or 0.10% by mass or more. .. The content of the component (C) is a component other than the conductive particles in the photoradical curable composition from the viewpoint of further improving the effect of suppressing peeling at the interface between the circuit member and the circuit connection portion in a high temperature and high humidity environment. 1.0% by mass or less, 0.75% by mass or less, 0.5% by mass or less, 0.25% by mass or less, 0.20% by mass or 0.15% by mass or less based on the total amount of good. From these viewpoints, the content of the component (C) is 0.001 to 1.0% by mass and 0.005 to 0. Based on the total amount of the components other than the conductive particles in the photoradical curable composition. 75% by mass, 0.01 to 0.5% by mass, 0.025 to 0.5% by mass, 0.05 to 0.25% by mass, 0.07 to 0.20% by mass or 0.10 to 0. It may be 15% by mass. The content of the component (C) can be confirmed by an analysis method such as HPLC.

The content of the component (C) is 0.001% by mass or more based on the total amount of the components other than the conductive particles in the cured product of the photoradical curable composition from the viewpoint of further improving the capture rate of the conductive particles. , 0.005% by mass or more, 0.01% by mass or more, 0.025% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.07% by mass or more or 0.10% by mass or more It may be there. The content of the component (C) is the conductive particles in the cured product of the photoradical curable composition from the viewpoint of further improving the effect of suppressing peeling at the interface between the circuit member and the circuit connection portion in a high temperature and high humidity environment. 1.0% by mass or less, 0.75% by mass or less, 0.5% by mass or less, 0.25% by mass or less, 0.20% by mass or 0.15% by mass or less based on the total amount of components other than May be. From these viewpoints, the content of the component (C) is 0.001 to 1.0% by mass, 0.005, based on the total amount of the components other than the conductive particles in the cured product of the photoradical curable composition. ~ 0.75% by mass, 0.01 to 0.5% by mass, 0.025 to 0.5% by mass, 0.05 to 0.25% by mass, 0.07 to 0.20% by mass or 0.10 It may be ~ 0.15% by mass. The content of the component (C) based on the total amount of the components other than the conductive particles in the first adhesive layer may be the same as the above range. The content of the component (C) can be confirmed by an analysis method such as HPLC.

[(D) component: conductive particles]
The component (D) is not particularly limited as long as it is conductive particles, such as metal particles made of metal such as Au, Ag, Ni, Cu, and solder, and conductive carbon particles made of conductive carbon. May be. The component (D) may be a coated conductive particle containing a nucleus containing non-conductive glass, ceramic, plastic (polystyrene, etc.) and the like, and a coating layer containing the metal or conductive carbon and covering the nucleus. good. Among these, when metal particles formed of a heat-meltable metal or a core containing a plastic and a coated conductive particle containing a metal or a conductive carbon and having a coating layer covering the core are used, photoradical curing is used. The cured product of the sex composition can be easily deformed by heating or pressurizing. Therefore, when the electrodes are electrically connected to each other, the contact area between the electrodes and the component (D) can be increased, and the conductivity between the electrodes can be further improved.

The component (D) may be an insulating coated conductive particle including the above-mentioned metal particles, conductive carbon particles, or coated conductive particles and an insulating material such as a resin and having an insulating layer covering the surface of the particles. good. When the component (D) is an insulating coated conductive particle, even when the content of the component (D) is large, the surface of the particle is coated with the resin, so that the component (D) is short-circuited due to contact with each other. The generation can be suppressed, and the insulation between adjacent electrode circuits can be improved. As the component (D), one of the above-mentioned various conductive particles may be used alone or in combination of two or more.

The maximum particle size of the component (D) needs to be smaller than the minimum distance between the electrodes (the shortest distance between adjacent electrodes). The maximum particle size of the 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 the component (D) may be 50 μm or less, 30 μm or less, or 20 μm or less from the viewpoint of excellent dispersibility and conductivity. In the present specification, the particle size of any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is the maximum particle size of the component (D). And. When the component (D) is not spherical such as having protrusions, the particle size of the component (D) is the diameter of a circle circumscribing the conductive particles in the SEM image.

The average particle size of the 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 the component (D) may be 50 μm or less, 30 μm or less, or 20 μm or less from the viewpoint of excellent dispersibility and conductivity. In the present specification, the particle size of any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle sizes is taken as the average particle size.

In the first adhesive layer 2, the component (D) may be uniformly dispersed. The particle density of the component (D) in the first adhesive layer 2 may be 100 pcs / mm ^{2 or more, 1000 pcs / mm 2 or} more, and 2000 pcs / mm from the viewpoint that stable connection resistance can be easily obtained. It may be mm ² or more. The particle density of the component (D) in the first adhesive layer 2 may be 100,000 pcs / mm ² or less, and may be 50,000 pcs / mm ² or less, from the viewpoint of improving the insulating property between adjacent electrodes. It may be 10000 pcs / mm ² or less.

The content of the component (D) may be 0.1% by volume or more based on the total volume in the first adhesive layer from the viewpoint of further improving the conductivity, and may be 1% by volume or more. It may be 5% by volume or more. The content of the component (D) may be 50% by volume or less, 30% by volume or less, and 20% by volume based on the total volume in the first adhesive layer from the viewpoint of easily suppressing a short circuit. It may be less than or equal to%. The content of the component (D) based on the total volume of the photoradical curable composition may be the same as the above range, and the total volume of the cured product of the photoradical curable composition is used as a reference (D). ) The content of the component may be the same as the above range.

The content of the component (D) may be 10% by mass or more, and 15% by mass or more, based on the total mass in the first adhesive layer, from the viewpoint of further improving the conductivity. It may be 20% by mass or more. The content of the component (D) may be 70% by mass or less, 60% by mass or less, and 50% by mass based on the total mass in the first adhesive layer from the viewpoint of easily suppressing a short circuit. It may be less than or equal to%. The content of the component (D) based on the total mass of the photoradical curable composition may be the same as the above range, and the total mass of the cured product of the photoradical curable composition is used as a reference (D). ) The content of the component may be the same as the above range.

[(E) Thermal Radical Polymerization Initiator]
The component (E) is a polymerization initiator that generates radicals by heat. As the component (E), one kind of compound may be used alone, or a plurality of kinds of compounds may be used in combination.

The component (E) is decomposed by heat to generate free radicals. That is, the thermal radical polymerization initiator is a compound that generates radicals by applying thermal energy from the outside. The thermal radical polymerization initiator can be arbitrarily selected from conventionally known organic peroxides and azo compounds. The thermal radical polymerization initiator may be an organic peroxide from the viewpoint of further improving the flow suppressing effect of the conductive particles and the peeling suppressing effect, and may be an organic peroxide from the viewpoint of stability, reactivity and compatibility. It may be an organic peroxide having a minute half-life temperature of 90 to 175 ° C. and a weight average molecular weight of 180 to 1000. When the half-life temperature for 1 minute is in this range, the storage stability is further excellent, the radical polymerizable property is sufficiently high, and the curing can be performed in a short time.

Specific examples of the component (E) include 1,1,3,3-tetramethylbutylperoxyneodecanoate, di (4-t-butylcyclohexyl) peroxydicarbonate, and di (2-ethylhexyl) peroxy. Dicarbonate, Cumylperoxyneodecanoate, Dilauroyl peroxide, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate , T-Butylperoxypivalate, 1,1,3,3-Tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) Hexanoate, 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-amylper Oxyneodecanoate, di (3-methylbenzoyl) peroxide, 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-butylperoxybenzoate, dibutylperoxytrimethyl adipate, t-amylperoxynormal Organic peroxides such as octoate, t-amylperoxyisononanoate, t-amylperoxybenzoate; 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), 1,1 '-Azobis (1-cyclohexanecarbonitrile), etc. Azo compounds and the like can be mentioned.

The content of the component (E) is other than the conductive particles in the first adhesive layer from the viewpoint of excellent quick-curing property, flow suppressing effect of the conductive particles, and further improvement of the peeling suppressing effect. Based on the total amount of the components, it may be 0.1% by mass or more, 0.5% by mass or more, and 1% by mass or more. From the viewpoint of pot life, the content of the thermal polymerization initiator may be 20% by mass or less, and 10% by mass or less, based on the total amount of the components other than the conductive particles in the first adhesive layer. It may be 5% by mass or less. The content of the component (E) based on the total amount of the components other than the conductive particles in the photoradical curable composition may be the same as the above range, and the content of the component (E) in the cured product of the photoradical curable composition may be the same. The content of the component (E) based on the total amount of the components other than the conductive particles may be the same as the above range.

[Other ingredients]
The photoradical curable composition may further contain other components other than the component (A), the component (B), the component (C), the component (D) and the component (E). Other components include, for example, thermoplastic resins, coupling agents and fillers. These components may be contained in the first adhesive layer 2.

Examples of the thermoplastic resin include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, acrylic rubber and the like. When the photoradical curable composition contains a thermoplastic resin, the first adhesive layer can be easily formed. Further, when the photoradical curable composition contains a thermoplastic resin, the stress of the first adhesive layer generated during the curing of the photoradical curable composition can be relieved. Further, when the thermoplastic resin has a functional group such as a hydroxyl group, the adhesiveness of the first adhesive layer is likely to be improved. The content of the thermoplastic resin may be, for example, 5% by mass or more and 80% by mass or less based on the total amount of components other than the conductive particles in the photoradical curable composition.

Examples of the coupling agent include a silane coupling agent having an organic functional group such as a (meth) acryloyl group, a mercapto group, an amino group, an imidazole group and an epoxy group, a silane compound such as tetraalkoxysilane, a tetraalkoxy titanate derivative and a polydialkyl. Examples include titanate derivatives. When the photoradical curable composition contains a coupling agent, the adhesiveness can be further improved. The content of the coupling agent may be, for example, 0.1% by mass or more and 20% by mass or less based on the total amount of the components other than the conductive particles in the photoradical curable composition. In addition, in this specification, a silane coupling agent having a polymerizable group such as a (meth) acryloyl group is not included in the polymerizable compound.

Examples of the filler include non-conductive fillers (for example, non-conductive particles).
When the photoradical curable composition contains a filler, further improvement in connection reliability can be expected. The filler may be either an inorganic filler or an organic filler. Examples of the inorganic filler include metal oxide fine particles such as silica fine particles, alumina fine particles, silica-alumina fine particles, titania fine particles, and zirconia fine particles; and inorganic fine particles such as nitride fine particles.
Examples of the organic filler include organic fine particles such as silicone fine particles, methacrylate-butadiene-styrene fine particles, acrylic-silicone fine particles, polyamide fine particles, and polyimide fine particles. These fine particles may have a uniform structure or may have a core-shell type structure. The maximum diameter of the filler may be less than the minimum particle size of the conductive particles 4. The content of the filler may be, for example, 1% by volume or more and 30% by volume or less based on the total volume of the photoradical curable composition.

The photoradical curable composition may contain other additives such as softeners, accelerators, antioxidants, colorants, flame retardants, thixotropic agents and the like. The content of these additives may be, for example, 0.1 to 10% by mass based on the total amount of the components other than the conductive particles in the photoradical curable composition. These additives may be contained in the first adhesive layer 2.

The thickness d1 of the first adhesive layer 2 is 0.1 times or more the average particle size of the conductive particles 4 from the viewpoint that the conductive particles 4 are easily captured between the facing electrodes and the connection resistance can be further reduced. It may be present, 0.2 times or more, and may be 0.3 times or more. The thickness d1 of the first adhesive layer 2 is such that the conductive particles are more easily crushed when the conductive particles are sandwiched between the electrodes facing each other during thermocompression bonding, and the connection resistance can be further reduced. The average particle size of the particles may be 0.8 times or less, and may be 0.7 times or less. From these viewpoints, the thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, and 0.2 to 0.8 times, the average particle size of the conductive particles 4. It may be 0.3 to 0.7 times. The thickness d1 of the first adhesive layer 2 refers to the thickness of the first adhesive layer located at the separated portion of the adjacent conductive particles 4 and 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, for example, as shown in FIG. 1, the conductive particles in the first adhesive layer 2 A part of 4 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 separated portion of the adjacent conductive particles 4 and 4. Due to the presence of the boundary S on the conductive particles along the surface of the conductive particles, the conductive particles 4 in the first adhesive layer 2 are moved from the first adhesive layer 2 to the second adhesive layer 3 side. The above relationship may be satisfied without protruding. The conductive particles 4 may not be exposed on the surface 2a of the first adhesive layer 2 opposite to the side of the second adhesive layer 3, and the surface 2a on the opposite side may be a flat surface.

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 described above. For example, the thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, 0.2 to 0.8 times, the maximum particle size of the conductive particles 4, and may be 0. It may be 3 to 0.7 times.

The thickness d1 of the first adhesive layer 2 may be appropriately set according to the height of the electrodes of the circuit member to be adhered. The thickness d1 of the first adhesive layer 2 may be, for example, 0.5 μm or more, and may be 20 μm or less. When a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (for example, protruding toward the second adhesive layer 3), the second adhesive layer 2 has a second surface. The distance from the surface 2a on the side opposite to the adhesive layer 3 side to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located at the separated portions of the adjacent conductive particles 4 and 4 ( (Distance indicated by d1 in FIG. 1) is the thickness of the first adhesive layer 2, and the exposed portion of the conductive particles 4 is not included in the thickness of the first adhesive layer 2. The length of the exposed portion of the conductive particles 4 may be, for example, 0.1 μm or more, and may be 20 μm or less.

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

(Second adhesive layer)
The second adhesive layer 3 contains, for example, (a) a polymerizable compound (hereinafter, also referred to as a component (a)) and (b) a thermal polymerization initiator (hereinafter, also referred to as a component (b)). It consists of a thermosetting composition. The thermosetting composition constituting the second adhesive layer 3 is a thermosetting composition that can flow when connected to a circuit, and is, for example, an uncured thermosetting composition.

The thermosetting composition may be a thermosetting composition from the viewpoint of facilitating connection at a low temperature in a short time, further improving the effect of reducing connection resistance, and being more excellent in connection reliability. That is, the component (a) contained in the thermosetting composition may be a radically polymerizable compound, and the component (b) may be a thermosetting polymerization initiator.

[(A) component: polymerizable compound]
The component (a) is, for example, a compound polymerized by a radical, a cation or an anion generated by a thermal polymerization initiator by heat. The component (a) is a radically polymerizable compound having a radically polymerizable group that reacts with radicals from the viewpoint of facilitating connection at a low temperature in a short time, further improving the effect of reducing connection resistance, and improving connection reliability. It's okay. Examples of the radically polymerizable compound and the combination thereof in the component (a) are the same as those in the component (A).

(A) The component may be any of a monomer, an oligomer or a polymer. As the component (a), one kind of compound may be used alone, or a plurality of kinds of compounds may be used in combination. The component (a) may be the same as or different from the component (A).

The content of the component (a) is 10% by mass or more based on the total mass of the thermosetting composition from the viewpoint that the crosslink density required for reducing the connection resistance and improving the connection reliability can be easily obtained. It may be 20% by mass or more, and may be 30% by mass or more. The content of the component (a) may be 90% by mass or less based on the total mass of the thermosetting composition from the viewpoint that curing shrinkage during polymerization can be suppressed and good reliability can be obtained. It may be 80% by mass or less, and may be 70% by mass or less.

[Component (b): Thermal polymerization initiator]
The component (b) may be a thermal polymerization initiator (thermal radical polymerization initiator, thermal cationic polymerization initiator or thermal anionic polymerization initiator) that generates radicals, cations or anions by heat. (B) As a component, one kind of compound may be used alone, or a plurality of kinds of compounds may be used in combination.

The component (b) may be a thermal radical polymerization initiator from the viewpoint that the effect of reducing the connection resistance is further improved and the connection reliability is more excellent. The example of the thermal radical polymerization initiator in the component (b) is the same as that of the component (E).

The content of the component (b) may be 0.1% by mass or more based on the total mass of the thermosetting composition, and may be 0, from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability. It may be 5.5% by mass or more, and may be 1% by mass or more. The content of the component (b) may be 30% by mass or less, 20% by mass or less, and 10% by mass or less based on the total mass of the thermosetting composition from the viewpoint of pot life. It's okay.

[Other ingredients]
The thermosetting composition may further contain other components other than the component (a) and the component (b). Examples of other components include thermoplastic resins, coupling agents, fillers, softeners, accelerators, deterioration inhibitors, colorants, flame retardants, thixotropic agents and the like. The details of the other components are the same as the details of the other components in the first adhesive layer 2.

The content of the photopolymerization initiator in the thermosetting composition may be, for example, 1% by mass or less, or 0% by mass, based on the total mass of the thermosetting composition.

The content of the photoradical sensitizer in the thermosetting composition may be, for example, 1% by mass or less, or 0% by mass, based on the total mass of the thermosetting composition.

The content of the conductive particles 4 in the second adhesive layer 3 may be, for example, 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 appropriately set according to the height of the electrodes of the circuit member to be adhered. The thickness d2 of the second adhesive layer 3 may be 5 μm or more from the viewpoint that the space between the electrodes can be sufficiently filled to seal the electrodes and better connection reliability can be obtained. , 200 μm or less. When a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (for example, protruding toward the second adhesive layer 3), the first in the second adhesive layer 3 The distance from the surface 3a on the side opposite to the adhesive layer 2 side to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located at the separated portions of the adjacent conductive particles 4 and 4 ( The distance (d2) in FIG. 1 is the thickness of the second adhesive layer 3.

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 1 / thickness d2 of the second adhesive layer 3). May be 1 or more, and may be 100 or less, from the viewpoint that the space between the electrodes can be sufficiently filled to seal the electrodes and better reliability can be obtained.

The thickness of the adhesive film 1 (the total thickness of all the layers constituting the adhesive film 1. In FIG. 1, the thickness d1 of the first adhesive layer 2 and the thickness of the second adhesive layer 3 are used. The total of d2) may be, for example, 5 μm or more, and may be 200 μm or less.

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

According to the adhesive film 1, the flow of the conductive particles generated during the manufacture of the circuit connection structure can be suppressed, and the capture rate of the conductive particles can be improved. Further, according to the adhesive film 1, it is possible to suppress peeling at the interface between the circuit member and the adhesive film, which occurs when the circuit connection structure is used in a high temperature and high humidity environment.

Although the circuit connection adhesive film of the present embodiment has been described above, 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, other than the first adhesive layer and the second adhesive layer. It may be composed of three or more layers including a layer (for example, a third adhesive layer). The third adhesive layer may be a layer having the same composition as the above-mentioned composition for the first adhesive layer or the second adhesive layer, and may be a first adhesive layer or a second adhesive layer. It may be a layer having the same thickness as the above-mentioned thickness.

Further, the circuit connection adhesive film of the above embodiment is an anisotropically conductive adhesive film having anisotropic conductivity, but the circuit connection adhesive film does not have anisotropic conductivity. It may be an adhesive film.

<Manufacturing method of adhesive film for circuit connection>
The method for manufacturing the circuit connection adhesive film 1 of the present embodiment is, for example, a preparation step for preparing the first adhesive layer 2 described above (first preparation step) and a method for producing the adhesive film 1 for circuit connection on the first adhesive layer 2. It includes a laminating step of laminating the second adhesive layer 3 described above. The method for manufacturing the circuit connection adhesive film 1 may further include a preparation step (second preparation step) for 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 the first preparation step may be performed first, or the second preparation step may be performed first.

In the first preparation step, for example, the first adhesive layer 2 is prepared by forming the first adhesive layer 2 on the base material to obtain the first adhesive film. Specifically, first, the component (A), the component (B), the component (C), and the component (D), and other components added as needed are added to the solvent (organic solvent). A varnish composition (varnish-like photoradical curable composition) is prepared by dissolving or dispersing by stirring and mixing, kneading, or the like. Then, the varnish composition is applied onto the release-treated substrate using a knife coater, a roll coater, an applicator, a comma coater, a die coater, etc., and then the solvent is volatilized by heating to form the substrate on the substrate. It forms a layer of a photoradical curable composition. Subsequently, by irradiating the layer made of the photoradical curable composition with light, the photoradical curable composition is cured (photocured), and the first adhesive layer 2 is formed on the substrate. (Curing step). As a result, the first adhesive film is obtained.

As the solvent used for preparing the varnish composition, a solvent having a property of uniformly dissolving or dispersing each component may be used. Examples of such a solvent include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate and the like. These solvents can be used alone or in combination of two or more. Stirring and mixing and kneading in the preparation of the varnish composition can be carried out by using, for example, a stirrer, a raider, a three-roll, a ball mill, a bead mill or a homodisper.

The base material is not particularly limited as long as it has heat resistance that can withstand the heating conditions when the solvent is volatilized. For example, stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, and polyethylene isophthalate are used. , Polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene / vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. Film) can be used.

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

A part of the solvent may remain in the layer made of the first adhesive composition without being removed. The content of the solvent in the layer made of the first adhesive composition may be, for example, 10% by mass or less based on the total mass of the layer made of the first adhesive composition.

Irradiation light having a wavelength in the range of 150 to 750 nm (for example, ultraviolet light) may be used for irradiation of light in the curing step. Light irradiation can be performed 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 irradiation amount of light is not particularly limited, and for example, the integrated light amount of light having a wavelength of 365 nm may be 100 mJ / cm ² or more, 200 mJ / cm ² or more, and 300 mJ / cm ² or more. good. The irradiation amount of light may be, for example, the integrated light amount of light having a wavelength of 365 nm, which may be 10000 mJ / cm ² or less, 5000 mJ / cm ² or less, or 3000 mJ / cm ² or less.

In the second preparation step, the same as in the first preparation step, except that the component (a) and the component (b), and other components added as needed are used and no light irradiation is performed. The second adhesive layer 3 is prepared by forming the second adhesive layer 3 on the substrate to obtain the second adhesive film.

A part of the solvent may remain in the second adhesive layer 3 without being removed. The content of the solvent in the second adhesive layer 3 may be, for example, 10% by mass or less based on the total mass of the second adhesive layer 3.

In the laminating step, the second adhesive layer 3 may be laminated on the first adhesive layer 2 by laminating the first adhesive film and the second adhesive film, and the first A first varnish composition obtained by using the component (a) and the component (b) and other components added as needed is applied onto the adhesive layer 2 and the solvent is volatilized. The second adhesive layer 3 may be laminated on the adhesive layer 2.

Examples of the method of adhering the first adhesive film and the second adhesive film include methods such as heat pressing, roll laminating, and vacuum laminating. Lamination may be performed, for example, under temperature conditions of 0 to 80 ° C.

The method for manufacturing the circuit connection adhesive film 1 of the present embodiment is not limited to the above. For example, before forming the first adhesive layer 2, a layer made of a thermosetting composition (second) on a layer made of a photoradical curable composition (precursor of the first adhesive layer 2). An adhesive layer 3) may be formed to obtain a laminated body including a layer made of a photoradical curable composition and a layer made of a thermosetting composition. In this case, the layer made of the photoradical curable composition may be cured by irradiating the obtained laminate with light to form the first adhesive layer 2. Further, for example, a layer made of a photoradical curable composition (precursor of the first adhesive layer 2) is formed on a layer made of a thermosetting composition (second adhesive layer 3), and photoradicals are formed. A laminate including a layer made of a curable composition and a layer made of a thermosetting composition may be obtained.

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

FIG. 2 is a schematic cross-sectional view showing a circuit connection structure of one embodiment. As shown in FIG. 2, the circuit connection structure 10 includes a first circuit member 13 having a first electrode 12 formed on a main surface 11a of the first circuit board 11 and the first circuit board 11. , A second circuit member 16 having a second electrode 15 formed on the main surface 14a of the second circuit board 14 and the second circuit board 14, and the first circuit member 13 and the second circuit member. It is arranged between 16 and includes a circuit connection portion 17 that electrically connects 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 as or different from each other. The first circuit member 13 and the second circuit member 16 may be a glass substrate or a 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 of an inorganic substance such as semiconductor, glass, or ceramic, an organic substance such as polyimide or polycarbonate, or a composite such as glass / epoxy. The first electrode 12 and the second electrode 15 are gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, indium tin oxide (ITO), and indium zinc oxidation. It may be made of a substance (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 is made of the cured product of the adhesive film 1 described above. The circuit connection portion 17 is located, for example, on the side of the first circuit member 13 in the direction in which the first circuit member 13 and the second circuit member 16 face each other (hereinafter referred to as “opposite direction”), and the above-mentioned optical radical is located. The first region 18 made of a cured product of a component other than the conductive particles 4 of the curable composition and the second region 18 made of the cured product of the above-mentioned heat-curable composition located on the side of the second circuit member 16 in the facing direction. It has a region 19 of 2 and conductive particles 4 that are interposed between at least the first electrode 12 and the second electrode 15 and 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 like the first region 18 and the second region 19, and for example, the curing of components other than the conductive particles 4 of the above-mentioned photoradical curable composition. It may consist of a cured product in which a product and a cured product of the above-mentioned thermosetting composition are mixed.

FIG. 3 is a schematic cross-sectional view showing a method of manufacturing the circuit connection structure 10. As shown in FIG. 3, a method of manufacturing the circuit connection structure 10 is, for example, between a first circuit member 13 having a first electrode 12 and a second circuit member 16 having a second electrode 15. The above-mentioned adhesive film 1 is interposed, and the first circuit member 13 and the second circuit member 16 are thermally pressure-bonded to electrically connect the first electrode 12 and the second electrode 15 to each other. To prepare for.

Specifically, as shown in FIG. 3A, first, a first circuit including a first electrode 12 formed on a main surface 11a of a first circuit board 11 and a first circuit board 11. A member 13 and a second circuit member 16 provided with a second electrode 15 formed on the main surface 14a of the second circuit board 14 and the second circuit board 14 are prepared.

Next, the first circuit member 13 and the second circuit member 16 are arranged so that the first electrode 12 and the second electrode 15 face each other, and the first circuit member 13 and the second circuit member 16 are arranged. The adhesive film 1 is arranged between the circuit member 16 and the circuit member 16. For example, as shown in FIG. 3A, the adhesive film 1 is laminated on the first circuit member 13 so that the first adhesive layer 2 side faces the mounting surface 11a of the first circuit member 13. do. Next, the adhesive film 1 is laminated so that the first electrode 12 on the first circuit board 11 and the second electrode 15 on the second circuit board 14 face each other. The second circuit member 16 is arranged on the circuit member 13.

Then, as shown in FIG. 3B, the first circuit member 13, the adhesive film 1, and the second circuit member 16 are heated while the first circuit member 13 and the second circuit member 16 are heated. By pressurizing in the thickness direction, the first circuit member 13 and the second circuit member 16 are thermocompression bonded to each other. At this time, as shown by an arrow in FIG. 3B, since the second adhesive layer 3 is made of a flowable uncured thermosetting composition, it is between the second electrodes 15 and 15. It flows so as to fill the voids and is cured by the above 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 adhered to each other. The circuit connection structure 10 shown in 2 is obtained. In the method for manufacturing the circuit connection structure 10 of the present embodiment, since the first adhesive layer 2 is a pre-cured layer, the conductive particles 4 hardly flow during the thermocompression bonding, and the conductive particles are efficiently produced. Since it is captured between the facing electrodes, the connection resistance between the facing electrodes 12 and 15 is reduced. Therefore, a circuit connection structure having excellent connection reliability can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples.

<Synthesis of polyurethane acrylate (UA1)>
Poly (1,6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei Chemicals Co., Ltd.) in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser having a calcium chloride drying tube, and a nitrogen gas introduction tube. , 2500 parts by mass (2.50 mol) with a number average molecular weight of 1000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma Aldrich) were uniformly added dropwise over 3 hours. Then, after sufficiently introducing nitrogen gas into the reaction vessel, the inside of the reaction vessel was heated to 70 to 75 ° C. for reaction. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (manufactured by Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (manufactured by Sigma-Aldrich) were added to the reaction vessel. After that, 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (manufactured by Sigma-Aldrich) was added, and the mixture was reacted at 70 ° C. for 6 hours under an air atmosphere. As a result, polyurethane acrylate (UA1) was obtained. The weight average molecular weight of the polyurethane acrylate (UA1) was 15,000. The weight average molecular weight was measured by a gel permeation chromatograph (GPC) using a standard polystyrene calibration curve according to the following conditions.
(Measurement condition)
Equipment: GPC-8020 manufactured by Tosoh Corporation
Detector: RI-8020 manufactured by Tosoh Corporation
Column: Gelpack GLA160S + GLA150S manufactured by Hitachi Kasei Co., Ltd.
Sample concentration: 120 mg / 3 mL
Solvent: Tetrahydrofuran Injection amount: 60 μL
Pressure: 2.94 × 10 ⁶ Pa (30 kgf / cm ² )
Flow rate: 1.00 mL / min

<Manufacturing of conductive particles>
A layer made of nickel was formed on the surface of the polystyrene particles so that the thickness of the layer was 0.2 μm. In this way, conductive particles having an average particle size of 4 μm, a maximum particle size of 4.5 μm, and a specific gravity of 2.5 were obtained.

<Preparation method of polyester urethane resin>
48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were put into a stainless steel autoclave equipped with a stirrer, a thermometer, a condenser, a vacuum generator and a nitrogen gas introduction tube, and tetrabutoxytitanate as a catalyst. 0.02 parts by mass was charged. Then, the temperature was raised to 220 ° C. under a nitrogen stream, and the mixture was stirred as it was for 8 hours. Then, the pressure was reduced to atmospheric pressure (760 mmHg), and the mixture was cooled to room temperature. This caused a white precipitate to precipitate. Then, the white precipitate was taken out, washed with water, and vacuum dried to obtain a polyester polyol. After the obtained polyester polyol was sufficiently dried, it was dissolved in MEK (methyl ethyl ketone) and placed in a four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser and a nitrogen gas introduction tube. Further, dibutyltin dilaurate was added as a catalyst in an amount of 0.05 parts by mass with respect to 100 parts by mass of the polyester polyol, and 4,4'-diphenylmethane diisocyanate was added in an amount of 50 parts by mass with respect to 100 parts by mass of the polyester polyol. The target polyester urethane resin was obtained by dissolving it in MEK, adding it with a dropping funnel, and stirring it at 80 ° C. for 4 hours.

<Preparation of the first varnish composition (varnish-like photoradical curable composition)>
The components shown below were mixed in the blending amounts (parts by mass) shown in Table 1 to prepare the first varnish compositions 1 to 8.

(Radical polymerizable compound)
A1: Diacrylate having a tricyclodecane skeleton (trade name: DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.)
A2: Polyurethane acrylate synthesized as described above (UA1)
A3: 2-methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.)
(Photoradical polymerization initiator)
B1: 1,2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (O-benzoyloxime)] (trade name: Irgacure (registered trademark) OXE01, manufactured by BASF)
(Photo radical sensitizer)
C1: 9,10-bis (octanoyloxy) anthracene C2: 9,10-dibutoxyanthracene (conductive particles)
D1: Conductive particles prepared as described above (thermal radical polymerization initiator)
E1: Benzoyl peroxide (trade name: Niper BMT-K40, manufactured by NOF CORPORATION)
(Thermoplastic resin)
F1: Polyester urethane resin (coupling agent) synthesized as described above
G1: 3-methacryloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.)
(Filler)
H1: Silica fine particles (trade name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm)
(solvent)
I1: Methyl ethyl ketone

<Preparation of a second varnish composition (varnish-like thermosetting composition)>
As the radically polymerizable compounds a1 to a3, the thermal radical polymerization initiator b1, the coupling agent d1, the filler e1 and the solvent f1, the polymerizable compounds A1 to A3 in the photoradical curable composition, the thermal radical polymerization initiator E1, and the cup. Using the same ring agent G1, filler H1 and solvent I1, the thermoplastic resin c1 uses the components shown below, and these components are mixed in the blending amounts (parts by mass) shown in Table 2 to form a second varnish. Composition 1 was prepared.
(Thermoplastic resin)
c1: Phenoxy resin (trade name: PKHC, manufactured by Union Carbide)

(Example 1)
[Preparation of first adhesive film]
The first varnish composition 1 was applied onto a PET film having a thickness of 50 μm using a coating device. Then, it was dried with hot air at 70 ° C. for 3 minutes to form a layer made of a photoradical curable composition having a thickness (thickness after drying) of 4 μm on the PET film. The thickness here was measured using a contact thickness gauge. Next, the layer made of the photoradical curable composition was irradiated with light using a metal halide lamp so that the integrated light amount was 1500 mJ / cm ² , and the polymerizable compound was polymerized. As a result, the photoradical curable composition was cured to form a first adhesive layer. By the above operation, a first adhesive film provided with the first adhesive layer (thickness of the region where the conductive particles are present: 4 μm) on the PET film was obtained. The conductive particle density at this time was about 7000 pcs / mm ² . When the thickness of the first adhesive layer is smaller than the thickness (diameter) of the conductive particles, the thickness of the layer is measured using a contact type thickness gauge, and the thickness of the conductive particles is reflected to be conductive. The thickness of the area where the particles are present is measured. Therefore, after producing a circuit-connecting adhesive film having a two-layer structure in which a first adhesive layer and a second adhesive layer are laminated, they are located at separated portions of adjacent conductive particles by a method described later. The thickness of the second adhesive layer was measured.

[Preparation of second adhesive film]
The second varnish composition 1 was applied onto a PET film having a thickness of 50 μm using a coating device. Then, it was dried with hot air at 70 ° C. for 3 minutes to form a second adhesive layer (layer made of a thermosetting composition) having a thickness of 8 μm on the PET film. By the above operation, a second adhesive film having a second adhesive layer on the PET film was obtained.

[Manufacturing adhesive film for circuit connection]
The first adhesive film and the second adhesive film were arranged so that the respective adhesive layers faced each other, and were laminated with a roll laminator while being heated at 40 ° C. together with the PET film as a base material. As a result, a circuit connection adhesive film having a two-layer structure in which the first adhesive layer and the second adhesive layer were laminated was produced.

The thickness of the first adhesive layer of the produced adhesive film for circuit connection was measured by the following method. First, the adhesive film for circuit connection is sandwiched between two sheets of glass (thickness: about 1 mm), 100 g of bisphenol A type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Co., Ltd.) and a curing agent (trade name: Epomount). It was cast with a resin composition consisting of 10 g of a curing agent (manufactured by Refine Tech Co., Ltd.). After that, the cross section is polished using a polishing machine, and a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Co., Ltd.) is used to perform the first section located at the separated portion of the adjacent conductive particles. The thickness of the adhesive layer was measured. The thickness of the first adhesive layer was 2 μm.

[Creation of circuit connection structure]
A thin film electrode (height: 1200 Å) composed of COF (manufactured by FLEXSEED, electrode tip width 10 μm) having a pitch of 25 μm and amorphous indium tin oxide (ITO) on a glass substrate via the prepared adhesive film for circuit connection. A glass substrate with a thin film electrode (manufactured by Geomatec), which is equipped with a thin film electrode, is heated at 170 ° C. and 6 MPa for 4 seconds using a thermal pressure bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Co., Ltd.). A circuit connection structure (connection structure) was produced by applying pressure and connecting over a width of 1 mm. At the time of connection, the circuit connection adhesive film was arranged on the glass substrate so that the surface of the circuit connection adhesive film on the first adhesive layer side faced the glass substrate.

(Examples 2 to 5 and Comparative Examples 1 to 3)
An adhesive film for circuit connection and a circuit connection structure were produced in the same manner as in Example 1 except that the first varnish compositions 2 to 8 were used instead of the first varnish composition 1.

<Evaluation of circuit connection structure 1>
First, the connection resistance value, particle fluidity, and capture rate of the obtained circuit connection structure were evaluated. The specific evaluation method is shown below, and the results are shown in Table 3.

[Evaluation of connection resistance]
The connection resistance value between the opposing electrodes in the circuit connection structure immediately after connection was measured with a multimeter. The connection resistance value was obtained as the average value of 16 resistance points between the opposing electrodes.

[Evaluation of particle fluidity]
The particle fluidity was evaluated by observing the particle flow state of the resin-exuded portion of the circuit connection adhesive film in the circuit connection structure using a microscope (trade name: ECLIPSE L200, manufactured by Nikon Corporation). Specifically, the produced circuit connection structure was observed from the glass substrate side with a microscope, and the particle state of the portion exuded outside the width of the circuit connection adhesive film was evaluated in three stages. The state where the particles hardly move and there are no particles in the exuded part 1. The state where the particles move a little but the particles are not connected to each other 2. The state where the particles flow and the particles are connected to each other. Was set to 3.

[Evaluation of capture rate]
First, the connection area of the obtained circuit connection structure was calculated, and the number of particles per connection area before mounting (number of particles before mounting) was calculated by the following formula.
Number of particles before mounting = particle density x connection area Since the particle density was 7000 (pcs / mm ² ) and the connection area was 1 (mm) x 10 x 10 ^-3 (mm), the connection area before mounting. The number of particles per particle was 70.

Next, the number of conductive particles captured on one electrode is counted for 20 electrodes, the average value of the number of captured particles per electrode after mounting (the number of captured particles after mounting) is obtained, and then the following formula is used. The capture rate was calculated by.
Capture rate (%) = number of captured particles after mounting / number of particles before mounting x 100

<Evaluation of circuit connection structure 2>
Next, a high-temperature and high-humidity test was performed on the circuit connection structures of Examples and Comparative Examples other than Comparative Example 1 in which the evaluation result of the capture rate was poor. The high temperature and high humidity test was carried out by leaving it in a constant temperature and constant humidity bath at 85 ° C. and 85% RH for 200 hours. Next, the circuit connection structure after the high temperature and high humidity test was evaluated for connection resistance and peeling. The connection resistance value was evaluated in the same manner as immediately after the connection, and the peeling evaluation was performed by the method shown below. The results are shown in Table 4.

[Peeling evaluation]
The presence or absence of peeling in the circuit connection portion of the circuit connection structure after the high temperature and high humidity test was evaluated using a microscope (trade name: ECLIPSE L200, manufactured by Nikon Corporation). Specifically, the circuit connection structure produced as described above is observed from the glass substrate side with a microscope, and the peeled state at the interface between the glass substrate and the circuit connection portion (cured product of the circuit connection adhesive film) is observed. It was evaluated on a three-point scale. The ratio of the part peeled off from the glass substrate in the total area of the circuit connection part was calculated, and the one with almost no peeling (the ratio of the peeled part is less than 5% of the whole) was A, and a small amount of peeling occurred. (The ratio of the peeled portion is 5% or more and less than 20% of the whole) is designated as B, and the peeled portion (the ratio of the peeled portion is 20% or more of the whole) is designated as C.

As shown in Tables 3 and 4, in Examples 1 to 5, good connection resistance and good capture rate were obtained, and no peeling was confirmed. On the other hand, in the comparative example in which the photoradical sensitizer was not used, it was not possible to confirm that a sufficient capture rate and suppression of exfoliation after the high temperature and high humidity test could be achieved at the same time.

1 ... Circuit connection adhesive film, 2 ... First adhesive layer, 3 ... Second adhesive layer, 4 ... Conductive particles, 10 ... Circuit connection structure, 12 ... Circuit electrode (first electrode), 13 ... 1st circuit member, 15 ... Bump electrode (second electrode), 16 ... 2nd circuit member.

Claims (7)

With the first adhesive layer,
A second adhesive layer laminated on the first adhesive layer is provided.
The first adhesive layer comprises a cured product of a photoradical curable composition containing a photoradical sensitizer and conductive particles.
The second adhesive layer is an adhesive film for circuit connection, which is made of a thermosetting composition. The adhesive film for circuit connection according to claim 1, wherein the thermosetting composition is a thermosetting composition. The content of the photoradical sensitizer is 0.001 to 1.0% by mass based on the total amount of components other than the conductive particles in the photoradical curable composition, according to claim 1 or 2. The described circuit connection adhesive film. The circuit connection according to claim 1 or 2, wherein the content of the photoradical sensitizer is 0.001 to 1.0% by mass based on the total amount of components other than the conductive particles in the cured product. Adhesive film for. The adhesive film for circuit connection according to any one of claims 1 to 4, wherein the thickness of the first adhesive layer is 0.1 to 0.8 times the average particle size of the conductive particles. .. The method for manufacturing an adhesive film for circuit connection according to any one of claims 1 to 5.
A circuit connection adhesive comprising a step of curing the photoradical curable composition by irradiating the layer made of the photoradical curable composition with light to form the first adhesive layer. How to make a film. The circuit connection adhesive film according to any one of claims 1 to 5 is interposed between a first circuit member having a first electrode and a second circuit member having a second electrode. A method for manufacturing a circuit connection structure, comprising a step of thermally crimping the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other. ..

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