JP2023075077A - Adhesive film for circuit connection and method for manufacturing the same, method for manufacturing circuit connection structure, and adhesive film-containing set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film for circuit connection that can reduce connection resistance between opposite electrodes in a circuit connection structure and a method for manufacturing the same; a method for manufacturing a circuit connection structure using the adhesive film; and an adhesive film-containing set provided with the adhesive film.

SOLUTION: An adhesive film 1 for circuit connection is provided with a first adhesive layer 2 and a second adhesive layer 3 that is laminated on the first adhesive layer 2, wherein: the first adhesive layer 2 is formed of a cured product of a photo-curable composition; the second adhesive layer 3 is formed of a heat-curable composition; and the photo-curable composition comprises a polymerizable compound, conductive particles 4 and a photopolymerization initiator having a structure represented by e.g. the formula (I).

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a circuit-connecting adhesive film and its manufacturing method, a circuit-connecting structure manufacturing method, and an adhesive film containing set.

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

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 electrode spacing are becoming extremely narrow. For this reason, it is not necessarily easy to efficiently capture the conductive particles on the microelectrodes and obtain high connection reliability.

On the other hand, for example, Patent Literature 1 proposes a method of unevenly distributing conductive particles on one side of an anisotropically conductive adhesive sheet to separate the conductive particles from each other.

WO2005/54388

However, in the technique of Patent Document 1, since the conductive particles flow during circuit connection, the conductive particles may aggregate between the electrodes and cause a short circuit. In addition, the uneven distribution of the conductive particles caused by the flow of the conductive particles may cause not only deterioration in insulating properties but also variations in connection resistance values, and there is still room for improvement.

Therefore, the present invention provides a circuit connection adhesive film capable of reducing the connection resistance between opposing electrodes of a circuit connection structure, a method for producing the same, a method for producing a circuit connection structure using the adhesive film, Another object of the present invention is to provide an adhesive film containing set including the adhesive film.

An adhesive film for circuit connection according to one aspect of the present invention comprises a first adhesive layer and a second adhesive layer laminated on the first adhesive layer, wherein the first adhesive The layer consists of a cured product of a photocurable composition, the second adhesive layer consists of a thermosetting composition, and the photocurable composition comprises a polymerizable compound, conductive particles, and the following formula (I): and a photopolymerization initiator having at least one structure selected from the group consisting of the structure represented by the following formula (II) and the structure represented by the following formula (III).

According to such a circuit connection adhesive film, it is possible to reduce the connection resistance between the opposing electrodes of the circuit connection structure. Furthermore, such a circuit-connecting adhesive film can maintain a low connection resistance even in a high-temperature and high-humidity environment (for example, 85° C., 85% RH). That is, according to this adhesive film for circuit connection, the connection reliability of the circuit connection structure can be improved.

A method for producing an adhesive film for circuit connection according to one aspect of the present invention includes a preparation step of preparing a first adhesive layer, and a second adhesive made of a thermosetting composition on the first adhesive layer. A laminating step of laminating layers, wherein the preparing step is a step of curing the photocurable composition by irradiating the layer made of the photocurable composition with light to obtain a first adhesive layer. The photocurable composition comprises a polymerizable compound, conductive particles, a structure represented by the above formula (I), a structure represented by the above formula (II), and a structure represented by the above formula (III) and a photopolymerization initiator having at least one structure selected from the group. According to this method, it is possible to obtain a circuit-connecting adhesive film capable of reducing the connection resistance between the opposing electrodes of the circuit-connecting structure.

［式（ＩＶ）中、Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又は炭素数１～２０のアルキル基を示す。］

The photopolymerization initiator has at least one structure selected from the group consisting of a structure represented by the following formula (IV) and a structure represented by the following formula (V) as the structure represented by the formula (II). It's okay.

[In formula (IV), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. ]

The polymerizable compound may be a radically polymerizable compound having a radically polymerizable group.

The photopolymerization initiator has at least one structure selected from the group consisting of an oxime ester structure, an α-aminoalkylphenone structure and an acylphosphine oxide structure as the structure represented by the above formulas (I) to (III). You can do it.

The thermosetting composition may contain a radically polymerizable compound having a radically polymerizable group.

The thickness of the first adhesive layer may be 0.2 to 0.8 times the average particle size of the conductive particles.

According to one aspect of the present invention, there is provided a method for manufacturing a circuit connection structure, wherein the circuit connection adhesive described above is placed between a first circuit member having a first electrode and a second circuit member having a second electrode. A step of thermally compressing the first circuit member and the second circuit member with the agent film interposed to electrically connect the first electrode and the second electrode to each other. According to this method, it is possible to obtain a circuit connection structure with reduced connection resistance between opposing electrodes.

An adhesive film containing set according to one aspect of the present invention includes the circuit-connecting adhesive film described above and a containing member that contains the adhesive film, and the containing member allows the inside of the containing member to be visually recognized from the outside. and the transmittance of light having a wavelength of 365 nm in the visible portion is 10% or less.

By the way, generally, the environment in which an adhesive film for circuit connection is used is a room called a clean room, in which temperature, humidity and cleanliness are controlled at a constant level. When the circuit-connecting adhesive film is shipped from the production site, the circuit-connecting adhesive film is stored in a packing bag or other container so as not to be directly exposed to the outside air and cause quality deterioration due to dust and moisture. do. Normally, this storage member has a visual indicator made of a transparent material so that various information such as the product name, lot number, and expiration date attached to the adhesive film inside the storage member can be confirmed even from the outside of the storage member. department is provided.

However, the inventors of the present invention found that when the above-described adhesive film for circuit connection is housed in a conventional housing member and stored or transported and then used, the effect of reducing the connection resistance of the adhesive film may not be obtained. It was clarified by the examination of As a result of further studies by the present inventors based on such study results, when a compound capable of reacting with the photopolymerization initiator in the photocurable composition is used as the polymerizable compound in the second adhesive layer, It has been found that the thermosetting composition hardens during storage and transportation of the adhesive film, reducing the effect of reducing the connection resistance. Therefore, the present inventors further studied based on the speculation that the polymerization of the polymerizable compound in the thermosetting composition is progressing due to the radicals derived from the photopolymerization initiator remaining in the first adhesive layer. As a result, it was found that by providing an adhesive film storage set including the above-mentioned specific storage member, it is possible to suppress the curing of the thermosetting composition during storage or transportation, and reduce the connection resistance of the adhesive film. It was found that the effect can be maintained.

That is, according to the adhesive film storage set of one aspect of the present invention, when a compound capable of reacting with the photopolymerization initiator in the photocurable composition is used as the polymerizable compound in the thermosetting composition, adhesion Curing of the thermosetting composition during storage or transportation of the adhesive film can be suppressed, and the effect of reducing the connection resistance of the adhesive film can be maintained.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive film for circuit connection which can reduce the connection resistance between the electrodes which oppose the circuit connection structure, and its manufacturing method can be provided. Further, according to the present invention, it is possible to provide a method for manufacturing a circuit connection structure using such an adhesive film. Further, according to the present invention, it is possible to provide an adhesive film storage set comprising such an 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. FIG. 3 is a schematic cross-sectional view showing a manufacturing process of a circuit connection structure according to one embodiment of the present invention. FIG. 4 is a perspective view showing an adhesive film containing set according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as the case may be. In addition, in this specification, the upper limit value and the lower limit value described individually can be combined arbitrarily. Moreover, in this specification, "(meth)acrylate" means at least one of acrylate and methacrylate corresponding thereto. The same applies to other similar expressions such as "(meth)acryloyl".

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

(First adhesive layer)
The first adhesive layer 2 is composed of a cured product (photocured product) of a photocurable composition. The photocurable composition includes (A) a polymerizable compound (hereinafter also referred to as "(A) component"), (B) a photopolymerization initiator (hereinafter also referred to as "(B) component"), and ( C) Contains conductive particles 4 (hereinafter also referred to as “component (C)”). The photocurable composition contains (D) a thermosetting resin (hereinafter also referred to as "(D) component") and/or (E) a thermal polymerization initiator (hereinafter also referred to as "(E) component"). may further contain. The first adhesive layer 2 is obtained, for example, by irradiating a layer made of a photocurable composition with light energy to polymerize the component (A) and cure the photocurable composition. That is, the first adhesive layer 2 is composed of the conductive particles 4 and the adhesive component 5 obtained by curing the components of the photocurable composition other than the conductive particles 4 . The first adhesive layer 2 may be a cured product obtained by completely curing a photocurable composition, or may be a cured product obtained by partially curing a photocurable composition. That is, the adhesive component 5 may or may not contain unreacted components (A) and (B) (furthermore, components (D) and (E)).

[(A) component: polymerizable compound]
The component (A) is, for example, a compound polymerized by radicals, cations, or anions generated by a photopolymerization initiator upon irradiation with light (eg, ultraviolet light). Component (A) may be a monomer, an oligomer or a polymer. As the component (A), one type of compound may be used alone, or multiple types of compounds may be used in combination.

(A) Component has at least one or more polymerizable groups. A polymerizable group is, for example, a group containing a polymerizable unsaturated double bond (ethylenically unsaturated bond). The polymerizable group is preferably a radically polymerizable group that reacts with radicals, from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability. That is, the component (A) is preferably a radically polymerizable compound. Examples of radically polymerizable groups include vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenylene groups, (meth)acryloyl groups, and maleimide groups. The number of polymerizable groups possessed by the component (A) may be 2 or more from the viewpoint of easily obtaining the physical properties and crosslink density necessary for reducing the connection resistance after polymerization, and suppresses curing shrinkage during polymerization. From a viewpoint, it may be 10 or less. Suppressing 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 cross-linking density and cure shrinkage, the number of polymerizable groups uses a polymerizable compound having the number of polymerizable groups within the above range, and the number of polymerizable groups is the polymerizable compound having the number outside the above range. may additionally be 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, carboxylated nitrile rubber, and the like.

(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 (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, penta Erythritol (meth)acrylate, dipentaerythritol hexa(meth)acrylate, isocyanuric acid-modified bifunctional (meth)acrylate, isocyanuric acid-modified trifunctional (meth)acrylate, tricyclodecanyl acrylate, dimethylol-tricyclodecane diacrylate, 2 -hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxypolyethoxy)phenyl]propane, 2,2 -di(meth)acryloyloxydiethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate and the like.

Maleimide compounds include 1-methyl-2,4-bismaleimidobenzene, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, and N,N'-m-toluylenebismaleimide. , N,N′-4,4-biphenylenebismaleimide, 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-diphenylmethanebismaleimide, N,N'-4,4- diphenylpropane bismaleimide, N,N'-4,4-diphenylether bismaleimide, N,N'-3,3-diphenylsulfone bismaleimide, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, 2,2-bis(3-s-butyl-4-8(4-maleimidophenoxy)phenyl)propane, 1,1-bis(4-(4-maleimidophenoxy)phenyl)decane, 4,4'-cyclohexyl den-bis(1-(4-maleimidophenoxy)-2-cyclohexylbenzene, 2,2'-bis(4-(4-maleimidophenoxy)phenyl)hexafluoropropane and the like.

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

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

Component (A) is preferably a (meth)acrylate compound from the viewpoint of a good balance between curing reaction speed and physical properties after curing. Component (A) is a (poly)urethane (meth)acrylate compound (urethane (meth)acrylate compounds or polyurethane (meth)acrylate compounds). Moreover, the (A) component may be a (meth)acrylate compound having a high Tg skeleton such as a dicyclopentadiene skeleton, from the viewpoint of improving the cohesive force and further reducing the connection resistance.

Component (A) balances cross-linking density and curing shrinkage, further reduces connection resistance, and improves 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 component (A) may be 3,000 or more, 5,000 or more, or 10,000 or more from the viewpoint of excellent balance between crosslink density and curing shrinkage. The weight average molecular weight of component (A) may be 1,000,000 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 gel permeation chromatography (GPC) using a standard polystyrene calibration curve under 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。 Component (A) preferably contains, as a (meth)acrylate compound, a radically polymerizable compound having a phosphate ester structure represented by the following general formula (1). In this case, since the adhesive strength to the surface of an inorganic substance (metal etc.) is improved, it is suitable for bonding 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 phosphate ester structure can be obtained, for example, by reacting phosphoric anhydride with 2-hydroxyethyl (meth)acrylate. Specific examples of the radical polymerizable compound having a phosphate 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 5% by mass or more based on the total mass of the photocurable composition, from the viewpoint of easily obtaining the crosslink density necessary for reducing the connection resistance and improving the connection reliability. may be present, may be 10% by mass or more, and may be 20% by mass or more. From the viewpoint of suppressing curing shrinkage during polymerization, the content of component (A) may be 90% by mass or less, 80% by mass or less, or 70% by mass, based on the total mass of the photocurable composition. % or less.

[(B) component: photopolymerization initiator]
Component (B) has at least one structure selected from the group consisting of a structure represented by formula (I) below, a structure represented by formula (II) below, and a structure represented by formula (III) below.

Component (B) may have a plurality of structures represented by formulas (I) to (III) above. The multiple structures may be the same or different from each other. As the component (B), one type of compound may be used alone, or a plurality of types of compounds may be used in combination.

Component (B) is radicalized by irradiation with light containing a wavelength within the range of 150 to 750 nm, preferably light containing a wavelength within the range of 254 to 405 nm, more preferably light containing a wavelength of 365 nm (for example, ultraviolet light). , It may be a photopolymerization initiator (photoradical polymerization initiator, photocationic polymerization initiator or photoanion polymerization initiator) that generates cations or anions, and the effect of reducing connection resistance is further improved, and connection reliability is more excellent. A photoradical polymerization initiator is preferred from the viewpoint of facilitating curing at a low temperature in a short period of time.

The structure represented by formula (I) above may be an oxime ester structure, a bisimidazole structure or an acridine structure. That is, component (B) may have 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 formula (I) above.

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) is preferably used.

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) and the like.

Compounds 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. 2,4,5-triarylimidazole dimers are included.

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

式（ＩＶ）中、Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又は炭素数１～２０のアルキル基を示す。

The structure represented by the above formula (II) may be, for example, a structure represented by the following formula (IV) or a structure represented by the following formula (V). That is, the component (B) has at least one structure selected from the group consisting of a structure represented by the following formula (IV) and a structure represented by the following formula (V) as the structure represented by the formula (II). may have. The component (B) may have at least one of a structure represented by the following formula (IV) and a structure represented by the following formula (V) from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability. preferable.

In formula (IV), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.

The structure represented by formula (II) above may be an α-aminoalkylphenone structure, an aminobenzophenone structure or an N-phenylglycine structure. That is, component (B) may have at least one structure selected from the group consisting of an α-aminoalkylphenone structure, an aminobenzophenone structure and an N-phenylglycine structure.

式（ＶＩＩ）中、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４は、それぞれ独立して、水素原子、炭素数１～２０のアルキル基、芳香族系炭化水素基を含む有機基、上記式（ＩＶ）で示される構造からなる官能基又は上記式（Ｖ）で示される構造からなる官能基を示す。Ｒ^２２、Ｒ^２３及びＲ^２４のうちの少なくとも一つは、上記式（ＩＶ）で示される構造からなる官能基又は上記式（Ｖ）で示される構造からなる官能基である。 A compound having a structure represented by the following formula (VII) is preferably used as the compound having an α-aminoalkylphenone structure.

In formula (VII), R ²¹ , R ²² , R ²³ and R ²⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an organic group containing an aromatic hydrocarbon group, or the above formula ( IV) or a functional group having the structure represented by formula (V) above. At least one of R ²² , R ²³ and R ²⁴ is a functional group having a structure represented by formula (IV) above or a functional group having a structure represented by formula (V) above.

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

Compounds having an aminobenzophenone structure include 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone and the like.

Compounds having an N-phenylglycine structure include N-phenylglycine and the like.

The structure represented by formula (III) may be an acylphosphine oxide structure. That is, the component (B) may have an acylphosphine oxide structure as the structure represented by the formula (III).

式（ＶＩＩＩ）中、Ｒ^３１、Ｒ^３２及びＲ^３３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、カルボニル基若しくは芳香族系炭化水素基を含む有機基を示す。 As the compound having an acylphosphine oxide structure, a compound having a structure represented by the following formula (VIII) is preferably used.

In formula (VIII), R ³¹ , R ³² and R ³³ each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an organic group containing a carbonyl group or an aromatic hydrocarbon group. .

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

Component (B) is at least one selected from the group consisting of an oxime ester structure, an α-aminoalkylphenone structure and an acylphosphine oxide structure, from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability. Having a structure is preferred.

The content of the component (B) is preferably 0 based on the total mass of the photocurable composition, from the viewpoint of excellent rapid curability, the effect of further improving the connection resistance reduction effect, and the excellent connection reliability. 0.1% by mass or more, more preferably 0.3% by mass or more. The content of component (B) may be 1% by mass or more, 1.5% by mass or more, 2% by mass or more, or 2.5% by mass or more based on the total mass of the photocurable composition. The content of the component (B) is preferably based on the total mass of the photocurable composition, from the viewpoint of improving the storage stability, further improving the effect of reducing the connection resistance, and improving the connection reliability. It is 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. The content of component (B) is 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, and 1.5% by mass or less, based on the total mass of the photocurable composition. , 1% by mass or less, or 0.7% by mass or less. From these viewpoints, the content of component (B) is preferably 0.1 to 15% by mass, more preferably 0.1 to 10% by mass, and still more preferably 0% by mass, based on the total mass of the photocurable composition. .3 to 5% by mass. The content of component (B) is, for example, 0.1 to 1% by mass, 0.3 to 0.7% by mass, 1.5 to 3.5% by mass, or It may be 2 to 3% by mass.

[(C) component: conductive particles]
Component (C) is not particularly limited as long as it is a particle having conductivity, and includes metal particles composed of metals such as Au, Ag, Ni, Cu, solder, and conductive carbon particles composed of conductive carbon. can be Component (C) is a coated conductive particle comprising a nucleus containing non-conductive glass, ceramic, plastic (such as polystyrene), etc., and a coating layer containing the above metal or conductive carbon and covering the nucleus. good. Among these, coated conductive particles comprising a core containing metal particles made of a heat-fusible metal or plastic and a coating layer containing metal or conductive carbon and covering the core are preferably used. In this case, since it is easy to deform the cured product of the photocurable composition by heating or pressing, when the electrodes are electrically connected to each other, the contact area between the electrodes and the component (C) is increased. , the conductivity between the electrodes can be further improved.

Component (C) is an insulating coated conductive particle comprising the above metal particles, conductive carbon particles, or coated conductive particles, and an insulating material such as a resin, and an insulating layer covering the surface of the particles. good. When the component (C) is an insulating coating conductive particle, even if the content of the component (C) is large, the surface of the particle is coated with a resin, so the short circuit due to the contact between the components (C) The occurrence can be suppressed, and the insulation between adjacent electrode circuits can be improved. (C) component is used individually by 1 type in the various electroconductive particles mentioned above, or in combination of 2 or more types.

The maximum particle size of component (C) must be smaller than the minimum distance between electrodes (the shortest distance between adjacent electrodes). The maximum particle size of component (C) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more from the viewpoint of excellent dispersibility and conductivity. The maximum particle size of component (C) may be 50 µm or less, 30 µm or less, or 20 µm or less from the viewpoint of excellent dispersibility and conductivity. In this specification, for 300 arbitrary conductive particles (pcs), the particle size is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is the maximum particle size of the component (C) and When the component (C) is not spherical, such as when the component (C) has projections, the particle size of the component (C) is the diameter of a circle circumscribing the conductive particles in the SEM image.

The average particle diameter of component (C) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more from the viewpoint of excellent dispersibility and conductivity. The average particle size of component (C) may be 50 µm or less, 30 µm or less, or 20 µm or less from the viewpoint of excellent dispersibility and conductivity. In this specification, 300 arbitrary conductive particles (pcs) are observed with a scanning electron microscope (SEM) to measure the particle size, and the average value of the obtained particle sizes is defined as the average particle size.

Component (C) is preferably dispersed uniformly in the first adhesive layer 2 . The particle density of the component (C) 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 of easily obtaining stable connection resistance. mm ² or more. The particle density of the component (C) in the first adhesive layer 2 may be 100,000 pcs/mm ² or less, or 50,000 pcs/mm ² or less, from the viewpoint of improving insulation between adjacent electrodes. It may be 10000 pcs/mm ² or less.

From the viewpoint of further improving conductivity, the content of component (C) may be 0.1% by volume or more, or 1% by volume or more, based on the total volume in the first adhesive layer. may be present, and may be 5% by volume or more. From the viewpoint of easily suppressing short circuits, the content of component (C) may be 50% by volume or less, 30% by volume or less, or 20% by volume, based on the total volume in the first adhesive layer. % or less. In addition, the content of the component (C) based on the total volume of the photocurable composition may be the same as the above range.

[(D) component: thermosetting resin]
Component (D) is a resin that is cured by heat and has at least one or more thermosetting groups. Component (D) is, for example, a compound that crosslinks by reacting with a curing agent by heat. As the component (D), one type of compound may be used alone, or a plurality of types of compounds may be used in combination.

The thermosetting group may be, for example, an epoxy group, an oxetane group, or the like from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability.

Specific examples of component (D) include bisphenol-type epoxy resins that are reaction products of epichlorohydrin and bisphenol A, F, AD, etc.; Epoxy resins such as various epoxy compounds having two or more glycidyl groups in one molecule such as novolac resins, naphthalene-based epoxy resins having a skeleton containing a naphthalene ring, glycidyl amines, glycidyl ethers, and the like.

The content of component (D) may be 30% by mass or more and 70% by mass or less based on the total mass of the first adhesive layer.

When the first adhesive layer contains a thermosetting resin, the first adhesive layer may further contain a curing agent used to cure the thermosetting resin. The curing agent is not particularly limited as long as it is a curing agent that generates cationic species by heat, and can be appropriately selected according to the purpose. Examples of curing agents include sulfonium salts and iodonium salts. The content of the curing agent may be, for example, 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the thermosetting resin.

[(E) component: thermal polymerization initiator]
The component (E) 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, and has the effect of reducing connection resistance. It is preferably a thermal radical polymerization initiator from the viewpoint of further improving and being more excellent in connection reliability. As the component (E), one type of compound may be used alone, or multiple types of compounds may be used in combination.

Thermal radical polymerization initiators are decomposed by heat to generate free radicals. In other words, the thermal radical polymerization initiator is a compound that generates radicals when thermal energy is applied from the outside. The thermal radical polymerization initiator can be arbitrarily selected from conventionally known organic peroxides and azo compounds. As the thermal radical polymerization initiator, an organic peroxide having a 1-minute half-life temperature of 90 to 175° C. and a weight average molecular weight of 180 to 1000 is preferably used from the viewpoint of stability, reactivity and compatibility. be done. When the 1-minute half-life temperature is in this range, the storage stability is further excellent, the radical polymerizability is sufficiently high, and curing in a short time is possible.

Specific examples of component (E) include 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxy Dicarbonate, cumyl peroxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate , t-butyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy) Hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate , di-t-butylperoxyhexahydroterephthalate, t-amylperoxy-3,5,5-trimethylhexanoate, 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, t-amylper oxyneodecanoate, t-amylperoxy-2-ethylhexanoate, di(3-methylbenzoyl)peroxide, dibenzoylperoxide, 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-ethylhexylmonocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate , dibutyl peroxytrimethyl adipate, t-amyl peroxy normal octoate, t-amyl peroxy isononanoate, t-amyl peroxy benzoate and other organic peroxides; 2,2'-azobis-2,4-dimethyl valeronitrile, 1,1′-azobis(1-acetoxy-1-phenylethane), 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 4,4 and azo compounds such as '-azobis(4-cyanovaleric acid), 1,1'-azobis(1-cyclohexanecarbonitrile), and the like.

The content of the component (E) may be 0.1% by mass or more based on the total mass of the first adhesive layer, from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability, It may be 0.5% by mass or more, and may be 1% by mass or more. From the viewpoint of pot life, the content of component (E) may be 20% by mass or less, 10% by mass or less, or 5% by mass or less based on the total mass of the first adhesive layer. It's okay. The first adhesive layer 2 may not contain the (E) component. In addition, the content of the component (E) based on the total mass of the photocurable composition may be the same as the above range.

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

Examples of photopolymerization initiators other than component (B) include photopolymerization initiators having a benzyldimethylketal structure and photopolymerization initiators having an α-hydroxyalkylphenone structure. The content of photopolymerization initiators other than component (B) may be, for example, 1 part by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of component (B).

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

Coupling agents include silane coupling agents having organic functional groups such as (meth)acryloyl groups, mercapto groups, amino groups, imidazole groups and epoxy groups, silane compounds such as tetraalkoxysilanes, tetraalkoxytitanate derivatives, polydialkyl titanate derivatives and the like. Adhesion can be further improved when the photocurable composition contains a coupling agent. The content of the coupling agent may be, for example, 0.1% by mass or more and 20% by mass or less based on the total mass of the photocurable composition.

Fillers include, for example, non-conductive fillers (eg, non-conductive particles). When the photocurable 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 inorganic fillers 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 organic fillers include organic fine particles such as silicone fine particles, methacrylate-butadiene-styrene fine particles, acryl-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 is preferably less than the minimum diameter 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 photocurable composition.

The photocurable composition may contain other additives such as softeners, accelerators, antidegradants, 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 mass of the photocurable composition. These additives may be contained in the first adhesive layer 2 .

The first adhesive layer 2 may contain components derived from the photocurable composition such as unreacted components (A) and (B). When the adhesive film 1 of the present embodiment is housed in a conventional housing member and stored and transported, the unreacted component (B) remains in the first adhesive layer 2, which may cause problems during storage and transport. It is presumed that part of the thermosetting composition in the second adhesive layer 3 is cured inside, and the effect of reducing the connection resistance of the adhesive film 1 is reduced. Therefore, when the first adhesive layer 2 contains the component (B), the effect of reducing the connection resistance can be prevented from decreasing by housing the adhesive film 1 in a housing member, which will be described later. The content of the component (B) in the first adhesive layer 2 is the total mass of the first adhesive layer from the viewpoint that the curing of the thermosetting composition is difficult to occur and the effect of reducing the connection resistance is sufficiently obtained. may be 15% by mass or less, may be 10% by mass or less, or may be 5% by mass or less. The content of component (B) in the first adhesive layer 2 may be 0.1% by mass or more based on the total mass of the first adhesive layer.

The thickness d1 of the first adhesive layer 2 is 0.2 times or more the average particle diameter 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 0.3 times or more. The thickness d1 of the first adhesive layer 2 is such that when the conductive particles are sandwiched between opposing electrodes during thermocompression bonding, the conductive particles are more likely to be crushed, and the connection resistance can be further reduced. may be 0.8 times or less, and may be 0.7 times or less of the average particle size of From these viewpoints, the thickness d1 of the first adhesive layer 2 may be 0.2 to 0.8 times the average particle diameter of the conductive particles 4, and 0.3 to 0.7 times. good. 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. 4 may protrude from the first adhesive layer 2 toward the second adhesive layer 3 side. In this case, a boundary S between the first adhesive layer 2 and the second adhesive layer 3 is positioned at the spaced portion between the adjacent conductive particles 4,4. The conductive particles 4 are not exposed on the surface 2a of the first adhesive layer 2 opposite to the second adhesive layer 3 side, and the opposite surface 2a may be a flat surface.

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 20 μm or less. In addition, when a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (for example, protruding to the second adhesive layer 3 side), the second adhesive layer 2 The distance from the surface 2a on the opposite side of the adhesive layer 3 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located in the spaced part between the adjacent conductive particles 4, 4 ( 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. As shown in FIG. The length of the exposed portion of the conductive particles 4 may be, for example, 0.1 μm or more and 20 μm or less.

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

[(a) component: polymerizable compound]
The component (a) is, for example, a compound that is polymerized by radicals, cations, or anions generated by a thermal polymerization initiator with heat. As the component (a), the compounds exemplified as the component (A) can be used. Component (a) is a radically polymerizable compound having a radically polymerizable group that reacts with radicals, from the viewpoints of facilitating connection at low temperatures in a short period of time, further improving the effect of reducing connection resistance, and improving connection reliability. is preferred. Examples of preferred radically polymerizable compounds and preferred combinations of radically polymerizable compounds in component (a) are the same as for component (A). When the component (a) is a radically polymerizable compound and the component (B) in the first adhesive layer is a photoradical polymerization initiator, the adhesive film is housed in a housing member to be described later to achieve adhesion. Curing of the thermosetting composition during storage or transportation of the agent film tends to be significantly suppressed.

Component (a) may be a monomer, oligomer or polymer. As the component (a), one type of compound may be used alone, or a plurality of types 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 of easily obtaining the crosslink density necessary for reducing the connection resistance and improving the connection reliability. may be present, may be 20% by mass or more, and may be 30% by mass or more. The content of component (a) may be 90% by mass or less based on the total mass of the thermosetting composition from the viewpoint of suppressing curing shrinkage during polymerization and obtaining good reliability, It may be 80% by mass or less, and may be 70% by mass or less.

[(b) component: thermal polymerization initiator]
As component (b), the same thermal polymerization initiator as component (E) can be used. As the component (b), one type of compound may be used alone, or multiple types of compounds may be used in combination. Component (b) is preferably a thermal radical polymerization initiator. Examples of preferred thermal radical polymerization initiators for component (b) are the same as those for component (E).

The content of component (b) may be 0.1% by mass or more based on the total mass of the thermosetting composition, from the viewpoint of further improving the effect of reducing the connection resistance and improving the connection reliability. .5% by mass or more, or 1% by mass or more. 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 the viewpoint of pot life. you can

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

The thermosetting composition contains a thermosetting resin similar to component (D) described above instead of components (a) and (b) or in addition to components (a) and (b). You may have In this case, the thermosetting composition may contain a curing agent used for curing the thermosetting resin described above. When using a thermosetting resin instead of the components (a) and (b), the content of the thermosetting resin in the thermosetting composition is, for example, 20 based on the total mass of the thermosetting composition. It may be greater than or equal to 80% by mass or less. When a thermosetting resin is used in addition to the components (a) and (b), the content of the thermosetting resin in the thermosetting composition is, for example, 20 based on the total mass of the thermosetting composition. It may be greater than or equal to 80% by mass or less. The content of the curing agent may be the same as the range described as the content of the curing agent in the photocurable 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 second adhesive layer 3 preferably does not contain conductive particles 4 .

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 of sufficiently filling the space between the electrodes to seal the electrodes and obtaining better connection reliability. , 200 μm or less. In addition, when a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (for example, protruding to the second adhesive layer 3 side), the first The distance from the surface 3a on the opposite side of the adhesive layer 2 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located in the spaced part between the adjacent conductive particles 4, 4 ( The distance indicated by d2 in FIG. 1) is the thickness of the second adhesive layer 3 .

Ratio of thickness d1 of first adhesive layer 2 to thickness d2 of second adhesive layer 3 (thickness d1 of first adhesive layer 2/thickness d2 of 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 (total thickness of all 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 ) may be, for example, 5 μm or more and may be 200 μm or less.

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 having 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 to connect the first circuit member and the second circuit member. Thermocompression bonding is used to electrically connect the first electrode and the second electrode to each other.

According to the adhesive film 1, the connection resistance between the opposing electrodes can be reduced, and the connection reliability can be improved. Although the reason why such an effect is obtained is not clear, the present inventors speculate as follows. First, in the adhesive film 1, since the conductive particles 4 are fixed by the cured photocurable composition, it is possible to suppress the flow of the conductive particles 4 during connection. Therefore, the capture efficiency of the conductive particles 4 at the electrodes can be improved. Furthermore, in the present embodiment, the photopolymerization initiator has at least one structure among the structures represented by formulas (I) to (III). Such a photopolymerization initiator changes the reactivity of the resin (for example, the reactivity of the resin in the vicinity of the conductive particles), and changes the crosslinked state, surface state, etc. of the resin, so that the surface of the conductive particles and the electrode surface during pressure bonding. contact can be easily obtained. Therefore, in this embodiment, the connection resistance can be reduced as compared with the case of using a photopolymerization initiator that does not have the structure represented by the above formulas (I) to (III). The present inventors presume that the above effect can be obtained for the reasons described above.

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 circuit-connecting adhesive film may be composed of two layers, a first adhesive layer and a second adhesive layer, except for the first adhesive layer and the second adhesive layer. It may be composed of three or more layers, including a layer of (for example, a third adhesive layer). The third adhesive layer may be a layer having a composition similar to that described above for the first adhesive layer or the second adhesive layer, wherein the first adhesive layer or the second adhesive layer It may be a layer having a thickness similar to that described above for . The circuit-connecting adhesive film may, for example, further comprise a third adhesive layer on the side of the first adhesive layer opposite the second adhesive layer. That is, the circuit-connecting adhesive film is formed by laminating, for example, a second adhesive layer, a first adhesive layer and a third adhesive layer in this order. In this case, the third adhesive layer consists, for example, of a thermosetting composition like the second adhesive layer.

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

<Method for producing adhesive film for circuit connection>
The method for producing the circuit-connecting adhesive film 1 of the present embodiment includes, for example, a preparation step (first preparation step) of preparing the first adhesive layer 2 described above, and and a lamination step of laminating the second adhesive layer 3 described above. The method for manufacturing the circuit-connecting adhesive film 1 may further include a preparation step (second preparation step) of preparing the second adhesive layer 3 .

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) and (C), and optionally added other components such as components (D) and (E) are mixed in an organic solvent. In addition, they are dissolved or dispersed by stirring, mixing, kneading, or the like to prepare a varnish composition. After that, the varnish composition is applied to the substrate that has been subjected to the release treatment using a knife coater, roll coater, applicator, comma coater, die coater, etc., and then the organic solvent is volatilized by heating, and the A layer made of a photocurable composition is formed on the substrate. Subsequently, by irradiating the layer made of the photocurable composition with light, the photocurable composition is cured to form the first adhesive layer 2 on the substrate (curing step). This gives the first adhesive film.

The organic solvent used for the preparation of the varnish composition is preferably a solvent capable of uniformly dissolving or dispersing each component, such as toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, and the like. is mentioned. These organic solvents can be used alone or in combination of two or more. Stirring, mixing and kneading during preparation of the varnish composition can be carried out using, for example, a stirrer, a kneader, a three-roll mill, a ball mill, a bead mill, or a homodisper.

The substrate is not particularly limited as long as it has heat resistance that can withstand the heating conditions when volatilizing the organic solvent. Phthalate, 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 organic solvent from the varnish composition applied to the substrate are preferably conditions under which the organic 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.

It is preferable to use irradiation light (for example, ultraviolet light) having a wavelength within the range of 150 to 750 nm for light irradiation 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 may be, for example, 0.01 to 10 J/cm ² in terms of integrated light amount of light with a wavelength of 365 nm.

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

In the lamination 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 adhesive layer 3 may be laminated. A varnish composition obtained by using the components (a) and (b) and other components added as necessary is applied onto the adhesive layer 2, and the organic solvent is volatilized to form the first A second adhesive layer 3 may be laminated on the adhesive layer 2 of the above.

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

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

FIG. 2 is a schematic cross-sectional view showing a circuit connection structure according to one embodiment. 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 a main surface 11a of the first circuit board 11. , a second circuit member 16 having a second circuit board 14 and a second electrode 15 formed on a main surface 14a of the second circuit board 14; and a first circuit member 13 and a second circuit member. 16 and 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 or different. The first circuit member 13 and the second circuit member 16 may be a glass substrate 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 made of an inorganic material such as semiconductor, glass, or ceramic, an organic material such as polyimide or polycarbonate, a composite material such as glass/epoxy, or the like. The first electrode 12 and the second electrode 15 are made of 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 is made of the cured adhesive film 1 described above. The circuit connection portion 17 is positioned, 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 the “opposing direction”), and the above-described photo-curing Positioned on the side of the second circuit member 16 in the direction facing the first region 18 made of a cured product of components such as the (A) component and the (B) component other than the conductive particles 4 of the conductive composition, (a) A second region 19 made of a cured product of the above thermosetting composition containing the component (b) and the like, and at least the first electrode 12 and the second electrode 15 interposed between the first electrode 12 and the second electrode 15 and conductive particles 4 electrically connecting the electrode 12 and the second electrode 15 to each other. The circuit connection part may not have two regions such as the first region 18 and the second region 19, and for example, the cured product of the components other than the conductive particles 4 of the photocurable composition described above and the cured product of the thermosetting composition described above may be mixed together.

3A to 3C are schematic cross-sectional views showing a method for manufacturing the circuit connection structure 10. FIG. As shown in FIG. 3, the method for manufacturing the circuit connection structure 10 includes, for example, a first circuit member 13 having a first electrode 12 and a second circuit member 16 having a second electrode 15. Then, the above-described adhesive film 1 is interposed, and the first circuit member 13 and the second circuit member 16 are thermally compressed to electrically connect the first electrode 12 and the second electrode 15 to each other. Prepare.

Specifically, first, as shown in FIG. A member 13, 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 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, a first adhesive film 1 is laminated such 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. A second circuit member 16 is arranged on the circuit member 13 .

Then, as shown in FIG. 3B, the first circuit member 13 and the second circuit member 16 are heated while the first circuit member 13, the adhesive film 1 and the second circuit member 16 are heated. By applying pressure 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 indicated by arrows in FIG. It flows so as to fill the voids and is cured by the heating. As a result, the first electrode 12 and the second electrode 15 are electrically connected to each other through the conductive particles 4, and the first circuit member 13 and the second circuit member 16 are adhered to each other. 2 is obtained. In the method for manufacturing the circuit connection structure 10 of the present embodiment, the first adhesive layer 2 is a pre-cured layer, so the conductive particles 4 are fixed in the first adhesive layer 2, and , the first adhesive layer 2 hardly flows during the thermocompression bonding, and the conductive particles are efficiently captured between the facing electrodes, so that the connection resistance between the facing electrodes 12 and 15 is reduced. Therefore, a circuit connection structure having excellent connection reliability can be obtained.

<Adhesive film storage set>
FIG. 4 is a perspective view of an adhesive film containing set according to one embodiment. As shown in FIG. 4, the adhesive film containing set 20 includes a circuit-connecting adhesive film 1, a reel 21 around which the adhesive film 1 is wound, and a containing member 22 containing the adhesive film 1 and the reel 21. And prepare.

As shown in FIG. 4, the adhesive film 1 is tape-shaped, for example. The tape-shaped adhesive film 1 is produced, for example, by cutting a sheet-shaped raw material into a long length having a width according to the application. A substrate may be provided on one surface of the adhesive film 1 . As the base material, a base material such as the PET film described above can be used.

The reel 21 includes a first side plate 24 having a core 23 around which the adhesive film 1 is wound, and a second side plate 25 arranged to face the first side plate 24 with the core 23 interposed therebetween. Prepare.

The first side plate 24 is, for example, a disk made of plastic, and an opening having a circular cross section is provided in the central portion of the first side plate 24 .

A winding core 23 of the first side plate 24 is a portion around which the adhesive film 1 is wound. The winding core 23 is made of plastic, for example, and has an annular shape with the same thickness as the width of the adhesive film 1 . The winding core 23 is fixed to the inner surface of the first side plate 24 so as to surround the opening of the first side plate 24 . A central portion of the reel 21 is provided with a shaft hole 26 into which a rotating shaft of a winding device or a feeding device (not shown) is inserted. When the rotating shaft of the winding device or the feeding device is inserted into the shaft hole 26 and the rotating shaft is driven, the reel 21 rotates without idling. A desiccant storage container containing a desiccant may be fitted in the shaft hole 26 .

Like the first side plate 24, the second side plate 25 is a circular plate made of plastic, for example. is provided with an opening.

The containing member 22 has, for example, a bag shape and contains the adhesive film 1 and the reel 21 . The containing member 22 has an insertion opening 27 for containing (inserting) the adhesive film 1 and the reel 21 inside the containing member 22 .

The containing member 22 has a viewing portion 28 that allows the inside of the containing member 22 to be visually recognized from the outside. The housing member 22 shown in FIG. 4 is configured such that the entire housing member 22 serves as the visual recognition portion 28 .

The visual recognition portion 28 has transparency to visible light. For example, when the light transmittance in the visible portion 28 is measured in the wavelength range of 450 to 750 nm, the average value of the light transmittance is 30% or more between the wavelengths of 450 to 750 nm, and the wavelength width is 50 nm. There is at least one region. The light transmittance of the visible part 28 is obtained by cutting a sample of the visible part 28 to a predetermined size and measuring the light transmittance of the sample with an ultraviolet-visible spectrophotometer. Since the housing member 22 has such a visual recognition part 28, various kinds of information such as the product name, lot number, expiration date, etc. attached to the reel 21 inside the housing member 22 can be confirmed even from the outside of the housing member 22. be able to. This can be expected to prevent mixing of different products and to improve the efficiency of sorting work.

The transmittance of light with a wavelength of 365 nm in the visual recognition portion 28 is 10% or less. Since the transmittance of light with a wavelength of 365 nm in the visible part 28 is 10% or less, the light entering from the outside to the inside of the housing member 22 and the photopolymerization initiator remaining in the first adhesive layer 2 Curing of the resulting thermosetting composition can be suppressed. As a result, the effect of reducing the connection resistance of the adhesive film 1 can be maintained, and when the adhesive film 1 is used for connecting circuit members, the connection resistance between opposing electrodes can be reduced. From the viewpoint of further suppressing the generation of active species (for example, radicals) from the photopolymerization initiator, the transmittance of light having a wavelength of 365 nm in the visible portion 28 is preferably 10% or less, more preferably 5% or less, and even more preferably. is 1% or less, particularly preferably 0.1% or less.

From the same point of view, the maximum value of light transmittance in the wavelength region capable of generating radicals, cations or anions from the photopolymerization initiator (component (B)) in the visible portion 28 is preferably It is 10% or less, more preferably 5% or less, still more preferably 1% or less, and particularly preferably 0.1% or less. Specifically, the maximum transmittance of light at a wavelength of 254 to 405 nm in the visible portion 28 is preferably 10% or less, more preferably 5% or less, even more preferably 1% or less, and particularly preferably 0.1%. It is below.

The visual recognition portion 28 (accommodating member 22) is formed of a sheet having a thickness of 10 to 5000 μm, for example. The sheet is made of a material having a transmittance of 10% or less for light with a wavelength of 365 nm in the visible portion 28 . Such materials may consist of one type of component, or may consist of multiple types of components. Examples of such materials include low-density polyethylene, linear low-density polyethylene, polycarbonate, polyester, acrylic resin, polyamide, and glass. These materials may contain UV absorbers. The visual recognition part 28 may have a laminated structure formed by laminating a plurality of layers with different light transmittance. In this case, each layer constituting the visual recognition portion 28 may be made of the materials described above.

The insertion opening 27 may be closed by, for example, a sealing machine or the like to prevent air from entering from the outside during accommodation. In this case, it is preferable to remove the air inside the housing member 22 by suction before closing the insertion port 27 . It can be expected that the humidity in the housing member 22 will be reduced from the initial stage of housing, and the intrusion of air from the outside will be prevented. In addition, since the inner surface of the housing member 22 and the reel 21 are in close contact with each other, the inner surface of the housing member 22 and the surface of the reel 21 rub against each other due to vibration during transportation, and foreign matter is generated. , 25 can be prevented from being damaged.

In the above embodiment, the housing member is configured so that the entire housing member serves as the visual recognition portion. good too. For example, the housing member may have a rectangular viewing portion approximately in the center of the side surface of the housing member. In this case, the portion of the housing member other than the viewing portion may be black, for example, so as not to transmit ultraviolet light and visible light.

Further, in the above embodiment, the shape of the containing member is bag-like, but the containing member may be box-shaped, for example. The containing member preferably has a notch for opening. In this case, the unsealing operation at the time of use is facilitated.

EXAMPLES The present invention will be described in more detail with reference to examples below, 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.) was added to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser with a calcium chloride drying tube, and a nitrogen gas introduction tube. , number average molecular weight 1000) 2500 parts by mass (2.50 mol) and isophorone diisocyanate (manufactured by Sigma-Aldrich) 666 parts by mass (3.00 mol) 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 reacted at 70° C. for 6 hours in an air atmosphere. This gave a polyurethane acrylate (UA1). The weight average molecular weight of polyurethane acrylate (UA1) was 15,000. The weight average molecular weight was measured using a standard polystyrene calibration curve from gel permeation chromatography (GPC) under the following conditions.
(Measurement condition)
Device: GPC-8020 manufactured by Tosoh Corporation
Detector: RI-8020 manufactured by Tosoh Corporation
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

<Production of conductive particles>
A layer of nickel was formed on the surface of the polystyrene particles so that the layer thickness was 0.2 μm. Thus, 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 of varnish of photocurable composition (varnish composition)>
The components shown below were mixed in the blending amounts (parts by weight) shown in Table 1 to prepare varnishes of photocurable compositions 1 to 18. The content (% by volume) of the conductive particles and the content (% by volume) of the filler described in Table 1 are based on the total volume of the photocurable composition.
(Polymerizable compound)
A1: Dicyclopentadiene type diacrylate (trade name: DCP-A, manufactured by Toagosei Co., Ltd.)
A2: Polyurethane acrylate (UA1) synthesized as described above
A3: 2-methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.)
(Photoinitiator)
B1: 1,2-octanedione, 1-[4-(phenylthio)phenyl-,2-(O-benzoyloxime)] (trade name: Irgacure (registered trademark) OXE01, manufactured by BASF)
B2: Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime) (trade name: Irgacure (registered trademark) OXE02, BASF company)
B3: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (trade name: Irgacure (registered trademark) 369, manufactured by BASF)
B4: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name: Irgacure (registered trademark) 907, manufactured by BASF)
B5: Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure (registered trademark) 279, manufactured by BASF)
B6: 1-hydroxy-cyclohexyl-phenyl-ketone (trade name: Irgacure (registered trademark) 184, manufactured by BASF)
B7: 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name: Irgacure (registered trademark) 1173, manufactured by BASF)
B8: 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (trade name: Irgacure (registered trademark) 2959, manufactured by BASF)
B9: 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propane (trade name: Irgacure (registered trademark) 127, BASF Corporation made)
(Conductive particles)
C1: Conductive particles (thermoplastic resin) produced as described above
F1: Bisphenol A type phenoxy resin (trade name: PKHC, manufactured by Union Carbide)
(coupling agent)
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 varnish of thermosetting composition (varnish composition)>
Polymerizable compounds a1 to a3, thermoplastic resin f1, coupling agent g1, filler h1 and solvent i1 as polymerizable compounds A1 to A3, thermoplastic resin F1, coupling agent G1 and filler in the photocurable composition A varnish of thermosetting composition 1 was prepared by using the same H1 and solvent I1, and mixing these components and the thermal polymerization initiator shown below in the amounts (parts by mass) shown in Table 2. The content (% by volume) of the filler described in Table 2 is based on the total volume of the thermosetting composition.
(Thermal polymerization initiator)
b1: benzoyl peroxide (trade name: Nyper BMT-K40, manufactured by NOF Corporation)

(Example 1)
[Preparation of first adhesive film]
A varnish of photocurable composition 1 was applied onto a PET film having a thickness of 50 μm using a coating device. Then, hot air drying was performed at 70° C. for 3 minutes to form a layer of photocurable composition 1 having a thickness (thickness after drying) of 2 μm on the PET film. Next, the layer composed of the photocurable composition 1 was irradiated with light using a metal halide lamp so that the integrated light amount was 3000 mJ/cm ² to polymerize the polymerizable compound. Thereby, the photocurable composition 1 was cured to form a first adhesive layer. Through the above operations, a first adhesive film having a first adhesive layer with a thickness of 2 μm on a PET film was obtained. The conductive particle density at this time was about 7000 pcs/mm ² . The thickness of the first adhesive layer was measured using a laser microscope OLS4100 manufactured by Olympus Corporation.

[Preparation of second adhesive film]
The varnish of thermosetting composition 1 was applied onto a PET film having a thickness of 50 μm using a coating device. Then, hot air drying was performed at 70° C. for 3 minutes to form a second adhesive layer (layer made of thermosetting composition 1) having a thickness of 10 μm on the PET film. A second adhesive film having a second adhesive layer on a PET film was obtained by the above operation.

[Preparation of adhesive film for circuit connection]
The first adhesive film and the second adhesive film were laminated with a roll laminator while being heated at 40° C. together with the PET film as the substrate. Thus, an adhesive film for circuit connection having a two-layer structure in which the first adhesive layer and the second adhesive layer were laminated was produced.

[Production of circuit connection structure]
A thin film electrode comprising a COF (manufactured by FLEXSEED) with a pitch of 25 μm and a thin film electrode (height: 1200 Å) made of amorphous indium tin oxide (ITO) on a glass substrate through the prepared adhesive film for circuit connection. A glass substrate (manufactured by Geomatec) is heated and pressed at 170 ° C. and 6 MPa for 4 seconds using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.). A circuit connection structure (connection structure) was produced by connecting over 1 mm. At the time of connection, the circuit-connecting adhesive film was arranged on the glass substrate so that the surface of the circuit-connecting adhesive film on the first adhesive layer side faced the glass substrate.

[Evaluation of circuit connection structure]
With respect to the obtained circuit connection structure, the connection resistance value between the opposing electrodes immediately after connection and after the high-temperature and high-humidity test was measured with a multimeter. The high temperature and high humidity test was performed by leaving the circuit connection structure in a constant temperature and humidity chamber at 85° C. and 85% RH for 200 hours. The connection resistance value was obtained as an average value of 16 points of resistance between opposing electrodes. Table 3 shows the results.

(Examples 2 to 10 and Comparative Examples 1 to 8)
A circuit-connecting adhesive film and a circuit-connecting structure were prepared in the same manner as in Example 1, except that photocurable compositions 2 to 18 were used as the photocurable composition, and the same as in Example 1. Then, the circuit connection structure was evaluated. The results are shown in Tables 3-5.

In Examples 1 to 10 using a photopolymerization initiator having a structure represented by formula (I), formula (II), or formula (III), compared to Comparative Examples 1 to 8, the connection resistance value was reduced. It was confirmed that the connection reliability of the circuit connection structure was excellent.

DESCRIPTION OF SYMBOLS 1... Adhesive film for circuit connection, 2... 1st adhesive layer, 3... 2nd adhesive layer, 4... Conductive particle, 10... Circuit connection structure, 12... Circuit electrode (first electrode), DESCRIPTION OF SYMBOLS 13... 1st circuit member, 15... Bump electrode (2nd electrode), 16... 2nd circuit member, 20... Adhesive film accommodation set, 22... Accommodating member, 28... Visible part.

Claims (1)

The invention described in the specification.

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