TWI899070B - Adhesive film for circuit connection and its manufacturing method, manufacturing method of circuit connection structure and adhesive film storage group - Google Patents

Abstract

An adhesive film 1 for circuit connection includes a first adhesive layer 2 and a second adhesive layer 3 laminated on the first adhesive layer 2. The first adhesive layer 2 comprises a cured product of a photocurable composition, and the second adhesive layer 3 comprises a thermosetting composition. The photocurable composition contains a polymerizable compound, a photopolymerization initiator having an oxime ester structure, and conductive particles 4. The content of the photopolymerization initiator is 0.3% by mass to 1.2% by mass, based on the total amount of components other than the conductive particles in the photocurable composition.

Description

Adhesive film for circuit connection and its manufacturing method, manufacturing method of circuit connection structure and adhesive film storage group

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

Various adhesive materials have been used for circuit connections. For example, circuit connection adhesive films with anisotropic conductivity and dispersed conductive particles have been used for connecting LCDs to tape carrier packages (TCPs), connecting flexible printed circuits (FPCs) to TCPs, and connecting FPCs to printed wiring boards.

In the field of precision electronic devices that use anisotropically conductive adhesive films for circuit connections, the advancement of circuit density is leading to extremely narrow electrode widths and spacing. Therefore, efficiently capturing conductive particles on tiny electrodes to achieve high connection reliability is not always easy.

For example, Patent Document 1 proposes a method for isolating conductive particles by biasing them to one side of an anisotropic conductive adhesive sheet. [Prior Art Document] [Patent Document]

Patent Document 1: International Publication No. 2005/54388

[Problem to be Solved by the Invention] However, in the method of Patent Document 1, the conductive particles flow during circuit connection, causing them to aggregate between the electrodes, potentially causing a short circuit. Furthermore, the resulting uneven distribution of the conductive particles due to the flow of the conductive particles not only degrades the insulation properties but also potentially causes variations in the connection resistance, leaving room for improvement.

Furthermore, the adhesive film used for circuit connection is required to not peel off from the circuit component after the circuit component is connected, even when the circuit connection structure is used for a long time in a high temperature and high humidity environment (e.g., 85°C, 85% RH).

Therefore, an object of the present invention is to provide an adhesive film for circuit connection that can suppress the flow of conductive particles that occurs during the manufacture of a circuit connection structure, and can also suppress the peeling at the interface between a circuit component and a circuit connection portion formed by the adhesive film when the circuit connection structure is used in a high-temperature, high-humidity environment. The present invention also provides a method for manufacturing the adhesive film, a method for manufacturing a circuit connection structure using the adhesive film, and an adhesive film storage kit including the adhesive film. [Means for Solving the Problem]

In one aspect of the present invention, an adhesive film for circuit connection includes a first adhesive layer and a second adhesive layer laminated on the first adhesive layer. The first adhesive layer includes a cured product of a photocurable composition, and the second adhesive layer includes a thermosetting composition. The photocurable composition contains a polymerizable compound, a photopolymerization initiator having an oxime ester structure, and conductive particles. The content of the photopolymerization initiator is 0.3% by mass to 1.2% by mass, based on the total amount of components other than the conductive particles in the photocurable composition.

The circuit connection adhesive film described herein can suppress the flow of conductive particles during the manufacture of a circuit connection structure and can also prevent peeling at the interface between circuit components and the adhesive film when the circuit connection structure is used in a high-temperature, high-humidity environment. This circuit connection adhesive film can reduce the connection resistance between opposing electrodes of the circuit connection structure, further maintaining a low connection resistance even in high-temperature, high-humidity environments (e.g., 85°C, 85% RH). In other words, this circuit connection adhesive film can improve the connection reliability of the circuit connection structure.

One aspect of the present invention provides a method for producing an adhesive film for circuit connection, comprising: a preparation step of preparing a first adhesive layer; and a lamination step of laminating a second adhesive layer comprising a thermosetting composition on the first adhesive layer, wherein the preparation step includes irradiating a layer comprising a photocurable composition with light to cure the photocurable composition, thereby obtaining the first adhesive layer, wherein the photocurable composition comprises a polymerizable compound, a photopolymerization initiator having an oxime ester structure, and conductive particles, and the content of the photopolymerization initiator is 0.3% by mass to 1.2% by mass, based on the total amount of components other than the conductive particles in the photocurable composition. According to this method, a circuit connection adhesive film can be obtained that can suppress the flow of conductive particles that occurs during the manufacture of the circuit connection structure and can suppress peeling at the interface between the circuit component and the adhesive film that occurs when the circuit connection structure is used in a high-temperature and high-humidity environment.

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

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

The photopolymerization initiator having an oxime ester structure may be a compound having a structure represented by the following formula (VI). [Chemistry 1] [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]

The thickness of the first adhesive layer may be 0.1 to 0.8 times the average particle size of the conductive particles.

One aspect of the present invention provides a method for manufacturing a circuit connection structure, comprising: interposing the aforementioned circuit connection adhesive film between a first circuit component having a first electrode and a second circuit component having a second electrode, and thermally pressing the first and second circuit components to electrically connect the first and second electrodes.

In one aspect of the present invention, an adhesive film storage set includes: the above-mentioned circuit connection adhesive film and a storage member for storing the adhesive film, and the storage member has a viewing portion that allows the interior of the storage member to be visible from the outside, and the transmittance of the viewing portion to light with a wavelength of 365 nm is less than 10%.

However, circuit connection adhesive films are typically used in a clean room, where the temperature, humidity, and cleanliness are maintained at a constant level. When shipped from the production site, the films are stored in packaging, such as packaging bags, to prevent direct exposure to the outside air and the resulting degradation of quality due to dust and moisture. Typically, this packaging bag is equipped with a transparent viewing area, allowing information such as the product name, batch number, and expiration date to be confirmed from the outside of the packaging bag.

However, the inventors' research revealed that the aforementioned circuit connection adhesive film sometimes fails to achieve the desired effect when used after being stored or transported in existing storage containers. Based on these findings, the inventors conducted further research and discovered that when a compound that reacts with the photopolymerization initiator in the photocurable composition is used as the polymerizable compound in the thermosetting composition, the thermosetting composition cures during storage and transport of the adhesive film, diminishing the effect of reducing connection resistance. Therefore, based on the speculation that the polymerization of the polymerizable compounds in the thermosetting composition is carried out by free radicals originating from the residual photopolymerization initiator in the first adhesive layer, the inventors and others conducted further research and found that by making an adhesive film storage group including the specific storage member, the curing of the thermosetting composition during storage or transportation can be suppressed, and the effect of reducing the connection resistance of the adhesive film can be maintained.

Specifically, according to one aspect of the adhesive film storage set of the present invention, when a compound that reacts with a photopolymerization initiator in a photocurable composition is used as the polymerizable compound in the thermosetting composition, curing of the thermosetting composition during storage or transportation of the adhesive film can be suppressed, thereby maintaining the adhesive film's connection resistance reduction effect. [Effects of the Invention]

The present invention provides an adhesive film for circuit connection that suppresses the flow of conductive particles during the manufacture of a circuit connection structure and prevents peeling at the interface between a circuit component and the adhesive film when the circuit connection structure is used in a high-temperature, high-humidity environment, and a method for manufacturing the same. Furthermore, the present invention provides a method for manufacturing a circuit connection structure using the adhesive film. Furthermore, the present invention provides an adhesive film storage kit including the adhesive film.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. Furthermore, in this specification, the numerical range represented by "～" represents a range that includes the numerical values described before and after "～" as the minimum and maximum values, respectively. In addition, the upper and lower limits described individually can be combined arbitrarily. In addition, in this specification, the so-called "(meth)acrylate" refers to at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl". In addition, the so-called "(poly)" refers to both the case where the prefix "poly" is present and the case where it is not present.

<Circuit Connection Adhesive Film> Figure 1 is a schematic cross-sectional view of an embodiment of a circuit connection adhesive film. As shown in Figure 1 , the circuit connection adhesive film 1 (hereinafter referred to as "adhesive film 1") includes a first adhesive layer 2 and a second adhesive layer 3 laminated on the first adhesive layer 2.

(First Adhesive Layer) The first adhesive layer 2 comprises a cured product of a photocurable composition (photocured product). The photocurable composition includes (A) a polymerizable compound (hereinafter referred to as "component (A)"), (B) a photopolymerization initiator having an oxime ester structure (hereinafter referred to as "component (B)"), and (C) conductive particles 4 (hereinafter referred to as "component (C)"). The photocurable composition may further include (D) a thermosetting resin (hereinafter referred to as "component (D)") and/or (E) a thermal polymerization initiator (hereinafter referred to as "component (E)"). In other words, the photocurable composition can be both light- and heat-curable.

The first adhesive layer 2 can be obtained, for example, by irradiating a layer containing a photocurable composition with light energy to polymerize component (A), thereby curing the photocurable composition. Specifically, the first adhesive layer 2 includes conductive particles 4 and an adhesive component 5 formed by photocuring the photocurable composition. Adhesive component 5 includes at least a polymer of component (A). Adhesive component 5 may or may not contain unreacted components (A) and (B).

[Component (A): Polymerizable Compound] Component (A) is a compound that polymerizes by free radicals, cations, or anions generated by a photopolymerization initiator upon exposure to light (e.g., ultraviolet light). Component (A) can be a monomer, oligomer, or polymer. Component (A) can be used singly or in combination.

Component (A) has at least one polymerizable group. From the perspective of further improving the effect of reducing the connection resistance and improving the connection reliability, the polymerizable group is preferably a free radical polymerizable group that reacts via free radicals. That is, component (A) is preferably a free radical polymerizable compound. Examples of free radical polymerizable groups include vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenyl groups, (meth)acryl groups, and maleimide groups. Regarding the number of polymerizable groups possessed by component (A), from the perspective of easily obtaining the physical properties and crosslinking density required for reducing the connection resistance after polymerization, the number may be two or more, and from the perspective of suppressing curing shrinkage during polymerization, the number may be 10 or less. From these perspectives, the number of polymerizable groups possessed by component (A) may be 2 to 10. In order to obtain a uniform and stable film (first adhesive layer) after light irradiation, it is preferable to suppress curing shrinkage during polymerization. In this embodiment, in order to achieve a balance between crosslinking density and curing shrinkage, in addition to using a polymerizable compound having a polymerizable group number within the above range, a polymerizable compound having a polymerizable group number outside the above range may also be used.

Specific examples of component (A) include (meth)acrylate compounds, maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadiimide derivatives, natural rubber, isoprene rubber, butyl rubber, nitrile rubber, butadiene rubber, styrene-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, silicone acrylate, ethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylate, ) hexyl 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-dimethylamino (meth)acrylate Ethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trihydroxymethylpropane tri(meth)acrylate, tetrahydroxymethylmethane tetra(meth)acrylate, polyethylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol (meth)acrylate, dipentaerythritol hexa(meth)acrylate acrylate, isocyanuric acid-modified difunctional (meth)acrylate, isocyanuric acid-modified trifunctional (meth)acrylate, tricyclodecyl acrylate, dihydroxymethyl-tricyclodecane diacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloyloxypolyethoxy)phenyl]propane, 2,2-di(meth)acryloyloxydiethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate, etc.

Examples of maleimide compounds include 1-methyl-2,4-dimaleimide benzene, N,N'-m-phenylenedimaleimide, N,N'-p-phenylenedimaleimide, N,N'-m-toluenedimaleimide, N,N'-4,4-biphenylenedimaleimide, N,N'-4,4-(3,3'-dimethyl-biphenyl)dimaleimide, N,N'-4,4-(3,3'-dimethyldiphenylmethane)dimaleimide, N,N'-4,4-(3,3'-diethyldiphenylmethane)dimaleimide, N,N'-4,4-diphenylmethanedimaleimide, N,N'-4,4-diphenylmethanedimaleimide, 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-sec-butyl-4-8(4-maleimidophenoxy)phenyl)propane, 1,1-bis(4-(4-maleimidophenoxy)phenyl)decane, 4,4'-cyclohexylene-bis(1-(4-maleimidophenoxy)-2-cyclohexyl)benzene, 2,2'-bis(4-(4-maleimidophenoxy)phenyl)hexafluoropropane, etc.

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

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

From the perspective of achieving an excellent balance between curing reaction speed and post-curing physical properties, component (A) is preferably a (meth)acrylate compound. To achieve both cohesive strength to reduce connection resistance and elongation to improve adhesion, resulting in superior adhesion properties, component (A) can be a (poly)urethane (meth)acrylate compound. Furthermore, to further improve cohesive strength and reduce connection resistance, component (A) can be a (meth)acrylate compound having a high Tg skeleton, such as a dicyclopentadiene skeleton.

To achieve a good balance between crosslink density and curing shrinkage, further reduce connection resistance, and improve connection reliability, component (A) can be a compound (e.g., polyurethane (meth)acrylate) in which polymerizable groups such as vinyl, allyl, or (meth)acryloyl groups are introduced into the terminals or side chains of thermoplastic resins such as acrylic resins, phenoxy resins, and polyurethane resins. In this case, the weight-average molecular weight of component (A) can be 3,000 or higher, 5,000 or higher, or 10,000 or higher, to achieve an excellent balance between crosslink density and curing shrinkage. Furthermore, to achieve excellent compatibility with other components, the weight-average molecular weight of component (A) can be 1,000,000 or lower, 500,000 or lower, or 250,000 or lower. From these perspectives, the weight-average molecular weight of component (A) can be 3,000 to 1,000,000, 5,000 to 500,000, or 10,000 to 250,000. The weight-average molecular weight refers to the value measured by gel permeation chromatograph (GPC) under the conditions described in the Examples using a calibration curve derived from standard polystyrene.

As the (meth)acrylate compound, component (A) is preferably a radically polymerizable compound having a phosphate structure represented by the following formula (1). In this case, the bonding strength to the surface of inorganic materials (such as metals) is improved, making it suitable for bonding between electrodes (for example, between circuit electrodes). [Chemistry 2]

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

From the perspective of easily achieving the crosslinking density required to reduce connection resistance and improve connection reliability, the content of component (A) can be 5% by mass or more, 10% by mass or more, or 20% by mass or more, based on the total amount of components other than the conductive particles in the photocurable composition. From the perspective of suppressing curing shrinkage during polymerization, the content of component (A) can be 90% by mass or less, 80% by mass or less, or 70% by mass or less, based on the total amount of components other than the conductive particles in the photocurable composition. From these perspectives, the content of component (A) can be 5% to 90% by mass, 10% to 80% by mass, or 20% to 70% by mass, based on the total amount of components other than the conductive particles in the photocurable composition.

[Component (B): Photopolymerization Initiator] The photocurable composition contains a photopolymerization initiator having an oxime ester structure as component (B).

The photopolymerization initiator may include multiple photopolymerization initiators having an oxime ester structure. As component (B), a single compound may be used alone, or multiple compounds may be used in combination.

As the compound having an oxime ester structure, a compound having a structure represented by the following formula (VI) is preferably used. [Chemistry 3]

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-dione-2-o-benzoyloxime, Phenylpropane-2-(o-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropane-2-(o-benzoyl)oxime, 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(o-benzoyloxime)], ethyl ketone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime), etc.

From the perspective of further enhancing the effect of suppressing the flow of the conductive particles, the content of the photopolymerization initiator having an oxime ester structure is 0.3 mass% or more, preferably 0.45 mass% or more, more preferably 0.55 mass% or more, and even more preferably 0.85 mass% or more, based on the total amount of components other than the conductive particles in the photocurable composition. From the perspective of further enhancing the effect of suppressing peeling, the content of the photopolymerization initiator having an oxime ester structure is 1.2 mass% or less, preferably 0.9 mass% or less, and even more preferably 0.6 mass% or less, based on the total amount of components other than the conductive particles in the photocurable composition. From these viewpoints, the content of the photopolymerization initiator having an oxime ester structure is 0.3% by mass to 1.2% by mass, preferably 0.45% by mass to 0.9% by mass, and more preferably 0.45% by mass to 0.6% by mass, based on the total amount of components other than the conductive particles in the photocurable composition.

In addition to the photopolymerization initiator having an oxime ester structure, the photocurable composition may further contain a photopolymerization initiator having a structure such as an α-amino alkyl phenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzoyldimethylketal structure, or an α-hydroxyalkyl phenone structure.

From the perspective of further enhancing the effect of suppressing the flow of the conductive particles, the total content of the photopolymerization initiator is 0.3 mass% or more, preferably 0.45 mass% or more, more preferably 0.55 mass% or more, and even more preferably 0.85 mass% or more, based on the total amount of components other than the conductive particles in the photocurable composition. From the perspective of further enhancing the effect of suppressing peeling, the content of component (B) is preferably 1.2 mass% or less, more preferably 0.9 mass% or less, and even more preferably 0.6 mass% or less, based on the total amount of components other than the conductive particles in the photocurable composition. From these viewpoints, the content of component (B) is preferably 0.3 to 1.2 mass %, more preferably 0.45 to 0.9 mass %, and even more preferably 0.45 to 0.6 mass %, based on the total amount of components other than the conductive particles in the photocurable composition.

[Component (C): Conductive Particles] Component (C) is not particularly limited as long as it is conductive particles. Examples include metal particles containing metals such as Au, Ag, Ni, Cu, and solder; and conductive carbon particles containing conductive carbon. Component (C) may also be coated conductive particles comprising a core composed of non-conductive glass, ceramic, or plastic (e.g., polystyrene) and a coating containing the metal or conductive carbon. Of these, coated conductive particles comprising a core composed of metal particles formed of a thermoplastic metal or plastic and a coating containing the metal or conductive carbon are particularly preferred. In this case, the cured photocurable 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 (C) component can be increased, thereby further improving the conductivity between the electrodes.

Component (C) can be insulating-coated conductive particles comprising the aforementioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer comprising an insulating material such as a resin that covers the surface of the particles. Even when the content of component (C) is high, the resin-coated surface of the particles can suppress short circuits caused by contact between components (C) and improve the insulation between adjacent electrode circuits. Component (C) can be composed of any of the aforementioned conductive particles alone or in combination of two or more.

The maximum particle size of component (C) needs to be smaller than the minimum electrode spacing (the shortest distance between adjacent electrodes). To ensure excellent dispersibility and conductivity, the maximum particle size of component (C) can be 1.0 μm or larger, 2.0 μm or larger, or 2.5 μm or larger. To ensure excellent dispersibility and conductivity, the maximum particle size of component (C) can be 50 μm or smaller, 30 μm or smaller, or 20 μm or smaller. From these perspectives, the maximum particle size of component (C) can be 1.0 μm to 50 μm, 2.0 μm to 30 μm, or 2.5 μm to 20 μm. In this specification, the particle size of 300 random conductive particles (pcs) is measured using a scanning electron microscope (SEM), and the maximum value obtained is defined as the maximum particle size of component (C). Furthermore, if component (C) is non-spherical, such as due to protrusions, the particle size of component (C) is defined as the diameter of a circle circumscribing the conductive particles in the SEM image.

From the perspective of excellent dispersibility and conductivity, the average particle size of component (C) can be 1.0 μm or greater, 2.0 μm or greater, or 2.5 μm or greater. From the perspective of excellent dispersibility and conductivity, the average particle size of component (C) can be 50 μm or less, 30 μm or less, or 20 μm or less. From these perspectives, the average particle size of component (C) can be 1.0 μm to 50 μm, 2.0 μm to 30 μm, or 2.5 μm to 20 μm. In this specification, the average particle size is the average value of the particle sizes obtained by measuring the particle size of 300 arbitrary conductive particles (pcs) using a scanning electron microscope (SEM).

Component (C) is preferably uniformly dispersed in the first adhesive layer 2. To facilitate stable connection resistance, the particle density of component (C) in the first adhesive layer 2 can be 100 pcs/ ^mm² or higher, 1000 pcs/ ^mm² or higher, or 2000 pcs/ ^mm² or higher. To improve insulation between adjacent electrodes, the particle density of component (C) in the first adhesive layer 2 can be 100,000 pcs/ ^mm² or lower, 50,000 pcs/ ^mm² or lower, or 10,000 pcs/ ^mm² or lower. From these viewpoints, the particle density of component (C) in the first adhesive layer 2 may be 100 pcs/mm ² to 100,000 pcs/mm ² , 1,000 pcs/mm ² to 50,000 pcs/mm ² , or 2,000 pcs/mm ² to 10,000 pcs/mm ² .

From the perspective of further improving conductivity, the content of component (C) can be 0.1 volume % or more, 1 volume % or more, or 5 volume % or more, based on the total volume of the first adhesive layer. From the perspective of easily suppressing short circuits, the content of component (C) can be 50 volume % or less, 30 volume % or less, or 20 volume % or less, based on the total volume of the first adhesive layer. From these perspectives, the content of component (C) can be 0.1 volume % to 50 volume %, 1 volume % to 30 volume %, or 5 volume % to 20 volume %, based on the total volume of the first adhesive layer. The content of the component (C) based on the total volume of the photocurable composition may be within the above range.

[Component (D): Thermosetting Resin] Component (D) is a resin that cures with heat and has at least one thermosetting group. Component (D) is, for example, a compound that reacts with a curing agent under heat, thereby crosslinking. Component (D) may be a single compound or a combination of multiple compounds.

From the perspective of further improving the connection resistance reduction effect and improving the connection reliability, the thermosetting group may be, for example, an epoxy group, an oxycyclobutane group, or the like.

Specific examples of component (D) include bisphenol-type epoxy resins obtained by the reaction of epichlorohydrin with bisphenol A, bisphenol F, bisphenol AD, etc.; epoxy novolac resins obtained by the reaction of epichlorohydrin with phenol novolac, cresol novolac, etc.; naphthalene-based epoxy resins having a skeleton containing a naphthalene ring; and epoxy resins such as various epoxy compounds having two or more glycidyl groups per molecule, such as glycidylamine and glycidyl ether.

The content of component (D) may be 30% by mass or more and 70% by mass or less, and may be 30% by mass to 70% by mass, based on the total amount of components other than the conductive particles in the first adhesive layer.

When the first adhesive layer comprises a thermosetting resin, it may further contain a hardener for curing the thermosetting resin. The hardener is not particularly limited as long as it generates cationic species by heat, and may be appropriately selected depending on the intended purpose. Examples of such hardeners include cobalt salts and iodine salts. The content of the hardener may be, for example, 0.1 parts by mass or more and 50 parts by mass or less, and may be between 0.1 and 50 parts by mass, relative to 100 parts by mass of the thermosetting resin.

[Component (E): Thermal Polymerization Initiator] Component (E) can be a thermal polymerization initiator that generates free radicals, cations, or anions by heat (thermal radical polymerization initiator, thermal cationic polymerization initiator, or thermal anionic polymerization initiator). Thermal radical polymerization initiators are preferred from the perspective of further reducing connection resistance and improving connection reliability. Component (E) can be used singly or in combination.

Thermal radical polymerization initiators decompose upon exposure to heat, generating free radicals. Specifically, thermal radical polymerization initiators are compounds that generate free radicals upon application of external thermal energy. Thermal radical polymerization initiators can be selected from any of the known organic peroxides and azo compounds. From the perspective of further enhancing the effect of suppressing the flow and peeling of conductive particles, organic peroxides are preferred as thermal radical polymerization initiators. From the perspective of stability, reactivity, and compatibility, organic peroxides having a one-minute half-life temperature of 90°C to 175°C and a weight-average molecular weight of 180 to 1000 are more preferred. By keeping the one-minute half-life temperature within this range, the storage stability is improved, and the free radical polymerization is high enough to allow hardening within a short period of time.

Specific examples of the component (E) include: 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, cumyl peroxyneodecanoate, dilauryl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, tert-hexyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxytrimethylacetate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, Ester, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, tert-hexyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneoheptanoate, tert-pentyl peroxy-2-ethylhexanoate, di-tert-butyl peroxyhexahydrophthalate, tert-pentyl peroxy-3,5,5-trimethylhexanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, tert-pentyl peroxyneodecanoate, di(3-methylbenzoyl)peroxide ), dibenzoyl peroxide, di(4-methylbenzoyl peroxide), tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peroxymaleate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, 2,5-dimethyl-2,5-bis(3-methylbenzoylperoxy)hexane, tert-butyl peroxy-2-ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-butyl peroxybenzoate Organic peroxides such as tributyl ester, dibutyl peroxytrimethyladipate, t-amyl peroxyoctanoate, t-amyl peroxyisononanoate, and t-amyl peroxybenzoate; azo compounds such as 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(1-acetyloxy-1-phenylethane), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanovaleric acid), and 1,1'-azobis(1-cyclohexanecarbonitrile).

From the perspective of achieving excellent rapid curing properties and further enhancing the effects of suppressing the flow and peeling of the conductive particles, the content of component (E) can be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total amount of components other than the conductive particles in the first adhesive layer. From the perspective of pot life, the content of component (E) can be 20% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total amount of components other than the conductive particles in the first adhesive layer. From these perspectives, the content of component (E) can be 0.1% by mass to 20% by mass, 0.5% by mass to 10% by mass, or 1% by mass to 5% by mass, based on the total amount of components other than the conductive particles in the first adhesive layer. The first adhesive layer 2 may not contain the component (E). The content of the component (E) based on the total amount of the components other than the conductive particles in the photocurable composition may be within the same range as described above.

[Other Ingredients] The photocurable composition may contain other ingredients besides component (A), component (B), component (C), component (D), and component (E). Examples of other ingredients include thermoplastic resins, coupling agents, fillers, and the aforementioned hardeners. These ingredients may also be included in the first adhesive layer 2.

Examples of thermoplastic resins include phenoxy resins, polyester resins, polyamide resins, polyurethane resins, polyesterurethane resins, and acrylic rubbers. When the photocurable composition contains a thermoplastic resin, the first adhesive layer can be easily formed. Furthermore, when the photocurable composition contains a thermoplastic resin, the stress in the first adhesive layer generated during curing of the photocurable composition can be alleviated. Furthermore, when the thermoplastic resin has functional groups such as hydroxyl groups, the adhesion of the first adhesive layer is easily improved. The content of the thermoplastic resin can be, for example, 5% by mass or more and 80% by mass or less, and can be 5% by mass to 80% by mass, based on the total amount of components other than the conductive particles in the photocurable composition.

Examples of coupling agents include silane coupling agents having organic functional groups such as (meth)acryl, alkyl, amino, imidazole, and epoxy groups; silane compounds such as tetraalkoxysilane; tetraalkoxytitanium ester derivatives; and polydialkyltitanium ester derivatives. When a photocurable composition contains a coupling agent, adhesion can be further improved. The coupling agent content can be, for example, 0.1% by mass or more and 20% by mass or less, based on the total amount of components other than the conductive particles in the photocurable composition, and can be in the range of 0.1% by mass to 20% by mass.

Examples of fillers include non-conductive fillers (e.g., 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 particles such as silica particles, alumina particles, silica-alumina particles, titanium dioxide particles, and zirconium oxide particles; and inorganic particles such as nitride particles. Examples of organic fillers include organic particles such as silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, and polyimide particles. These particles may have a uniform structure or a core-shell structure. The maximum diameter of the filler is preferably smaller than the minimum particle size of the conductive particles 4. The filler content can be, for example, 1 volume % or more and 30 volume % or less, and can be 1 volume % to 30 volume % based on the total volume of the photocurable composition.

The photocurable composition may also contain other additives such as softeners, accelerators, degradation inhibitors, colorants, flame retardants, and activators. The content of these additives may be, for example, 0.1% to 10% by mass, based on the total amount of components other than the conductive particles in the photocurable composition. These additives may also be included in the first adhesive layer 2.

The first adhesive layer 2 may also contain unreacted component (B). It is speculated that when the adhesive film 1 of this embodiment is stored and transported in an existing storage member, unreacted component (B) remains in the first adhesive layer 2. As a result, during storage and transport, the thermosetting composition in the second adhesive layer 3 partially cures, reducing the connection resistance reduction effect of the adhesive film 1. Therefore, when the first adhesive layer 2 contains component (B), by storing the adhesive film 1 in a storage member described below, this reduction in connection resistance can be prevented.

From the perspective of facilitating the capture of the conductive particles 4 between the opposing electrodes and further reducing the connection resistance, the thickness d1 of the first adhesive layer 2 can be at least 0.1 times, at least 0.2 times, or at least 0.3 times the average particle size of the conductive particles 4. From the perspective of making it easier to crush the conductive particles when sandwiched between the opposing electrodes during hot pressing, further reducing the connection resistance, the thickness d1 of the first adhesive layer 2 can be at most 0.8 times, or at most 0.7 times, the average particle size of the conductive particles 4. From these perspectives, the thickness d1 of the first adhesive layer 2 can be between 0.1 and 0.8 times, between 0.2 and 0.8 times, or between 0.3 and 0.7 times the average particle size of the conductive particles 4. Furthermore, the thickness d1 of the first adhesive layer 2 refers to the thickness of the first adhesive layer located between adjacent conductive particles 4 and the spaced apart portions of the conductive particles 4 .

When the thickness d1 of the first adhesive layer 2 and the average particle size of the conductive particles 4 satisfy the aforementioned relationship, for example, as shown in FIG1 , a portion of the conductive particles 4 in the first adhesive layer 2 may protrude from the first adhesive layer 2 to the side of 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 between adjacent conductive particles 4 and the portion separating the conductive particles 4. Alternatively, the aforementioned relationship can be satisfied by providing the boundary S along the surface of the conductive particles, without the conductive particles 4 in the first adhesive layer 2 protruding from the first adhesive layer 2 to the side of the second adhesive layer 3. Conductive particles 4 may not be exposed on surface 2a of first adhesive layer 2 opposite to second adhesive layer 3; surface 2a on the opposite side may be flat. The relationship between thickness d1 of first adhesive layer 2 and the maximum particle size of conductive particles 4 can be the same as described above. For example, thickness d1 of first adhesive layer 2 can be 0.1 to 0.8 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the maximum particle size of conductive particles 4.

The thickness d1 of the first adhesive layer 2 can be appropriately set according to the height of the electrode of the circuit component to be bonded, etc. The thickness d1 of the first adhesive layer 2 can be, for example, not less than 0.5 μm and not more than 20 μm, and can be in the range of 0.5 μm to 20 μm. Furthermore, if a portion of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (e.g., protruding onto the side of the second adhesive layer 3), the shortest distance (denoted by d1 in FIG1 ) from the surface 2a of the first adhesive layer 2 opposite the side of the second adhesive layer 3 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 between the adjacent conductive particles 4 and the portion separating the conductive particles 4 is the thickness of the first adhesive layer 2. 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 can be, for example, 0.1 μm or greater and 20 μm or less, and can be between 0.1 μm and 20 μm.

The thickness of the adhesive layer can be measured using the following method. First, sandwich the adhesive film between two pieces of glass (approximately 1 mm thick). Next, cast a resin composition containing 100 g of bisphenol A epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Co., Ltd.) and 10 g of hardener (trade name: Epomount Hardener, manufactured by Refine Tec Co., Ltd.). The film is then cross-sectioned using a grinder, 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) Second adhesive layer 3 comprises, for example, a thermosetting composition containing (a) a polymerizable compound (hereinafter referred to as component (a)) and (b) a thermal polymerization initiator (hereinafter referred to as component (b)). The thermosetting composition constituting second adhesive layer 3 is a thermosetting composition that is fluid during circuit connection, and is, for example, an uncured thermosetting composition.

[Component (a): Polymerizable Compound] Component (a) is a compound that polymerizes via free radicals, cations, or anions generated by heat from a thermal polymerization initiator. Component (a) can be any of the compounds listed for component (A). From the perspectives of facilitating connection at low temperatures and in a short time, further reducing connection resistance, and achieving superior connection reliability, component (a) is preferably a radically polymerizable compound having a radically polymerizable group that reacts with free radicals. Examples of preferred radically polymerizable compounds in component (a) and combinations of preferred radically polymerizable compounds are the same as those for component (A). When component (a) is a radically polymerizable compound and component (B) in the first adhesive layer is a photoradical polymerization initiator, by housing the adhesive film in a housing member described below, curing of the thermosetting composition during storage or transportation of the adhesive film tends to be significantly suppressed.

Component (a) may be a monomer, oligomer, or polymer. Component (a) may be a single compound or a combination of multiple compounds. Component (a) may be the same as or different from component (A).

From the perspective of easily achieving the crosslinking density required to reduce connection resistance and improve connection reliability, the content of component (a) can be 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the thermosetting composition. From the perspective of suppressing curing shrinkage during polymerization and achieving good reliability, the content of component (a) can be 90% by mass or less, 80% by mass or less, or 70% by mass or less, based on the total mass of the thermosetting composition. From these perspectives, the content of component (a) can be 10% to 90% by mass, 20% to 80% by mass, or 30% to 70% by mass, based on the total mass of the thermosetting composition.

[Component (b): Thermal Polymerization Initiator] Component (b) can be the same thermal polymerization initiator as component (E). Component (b) can be a single compound or a combination of multiple compounds. Component (b) is preferably a thermal radical polymerization initiator. Preferred examples of thermal radical polymerization initiators for component (b) are the same as for component (E).

From the perspective of further improving the connection resistance reduction effect and improving connection reliability, the content of component (b) can be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total mass of the thermosetting composition. From the perspective of pot life, the content of component (b) can be 30% by mass or less, 20% by mass or less, or 10% by mass or less, based on the total mass of the thermosetting composition. From these perspectives, the content of component (b) can be 0.1% by mass to 30% by mass, 0.5% by mass to 20% by mass, or 1% by mass to 10% by mass, based on the total mass of the thermosetting composition.

[Other Ingredients] The thermosetting composition may contain other ingredients besides components (a) and (b). Examples of these other ingredients include thermoplastic resins, coupling agents, fillers, softeners, accelerators, degradation inhibitors, colorants, flame retardants, and activators. Details of these other ingredients are the same as those for the first adhesive layer 2.

The thermosetting composition may contain a thermosetting resin similar to component (D) described above, in place of components (a) and (b), or in addition to components (a) and (b). In this case, the thermosetting composition may also contain a hardener for hardening the thermosetting resin. When a thermosetting resin is used in place of components (a) and (b), the content of the thermosetting resin in the thermosetting composition may be, for example, 20% by mass or more and 80% by mass or less, or 20% to 80% by mass, based on the total mass of the thermosetting composition. When a thermosetting resin is used in addition to components (a) and (b), the content of the thermosetting resin in the thermosetting composition may be, for example, 20% by mass or more and 80% by mass or less, or 20% by mass or less and 80% by mass or less, based on the total mass of the thermosetting composition. The content of the hardener may be within the same range as that specified for the hardener content 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 may be 0% by mass, based on the total mass of the second adhesive layer. The second adhesive layer 3 preferably does not contain the conductive particles 4.

The thickness d2 of the second adhesive layer 3 can be appropriately set based on factors such as the height of the electrodes of the connected circuit component. To fully fill the space between the electrodes, sealing the electrodes and achieving better connection reliability, the thickness d2 of the second adhesive layer 3 can be greater than 5 μm and less than 200 μm, preferably between 5 μm and 200 μm. Furthermore, when a portion of the conductive particles 4 are exposed from the surface of the first adhesive layer 2 (for example, protruding onto the side of the second adhesive layer 3), the distance from the surface 3a of the second adhesive layer 3 opposite to the side of the first adhesive layer 2 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located at the adjacent conductive particles 4 and the portion separating the conductive particles 4 (the distance represented by d2 in FIG. 1 ) is the thickness of the second adhesive layer 3.

From the perspective of fully filling the space between the electrodes and sealing the electrodes to achieve better reliability, the ratio of the thickness d1 of the first adhesive layer 2 to the thickness d2 of the second adhesive layer 3 (thickness d1 of the first adhesive layer 2 /thickness d2 of the second adhesive layer 3) can be greater than 1 and can be less than 100.

The thickness of the adhesive film 1 (the total thickness of all layers constituting the adhesive film 1; in FIG1 , the total thickness d1 of the first adhesive layer 2 and the thickness d2 of the second adhesive layer 3) can be, for example, 5 μm or more and 200 μm or less, and can be 5 μm to 200 μm.

In adhesive film 1, conductive particles 4 are dispersed within first adhesive layer 2. Therefore, adhesive film 1 is an anisotropically conductive adhesive film with anisotropic conductivity. Adhesive film 1 is used to interpose between a first circuit component having a first electrode and a second circuit component having a second electrode, thermally pressing the first and second circuit components together to electrically connect the first and second electrodes.

The adhesive film 1 can suppress the flow of conductive particles that occurs during the manufacture of the circuit connection structure, and can suppress the peeling at the interface between the circuit component and the circuit connection portion formed by the adhesive film that occurs when the circuit connection structure is used in a high-temperature and high-humidity environment.

While the circuit connection adhesive film according to the present embodiment has been described above, the present invention is not limited to the above embodiment.

For example, the circuit connection adhesive film may comprise two layers, a first adhesive layer and a second adhesive layer, or may comprise three or more layers, including a layer other than the first and second adhesive layers (e.g., a third adhesive layer). The third adhesive layer may have the same composition as described above for the first or second adhesive layer, and may have the same thickness as described above for the first or second adhesive layer. For example, the circuit connection adhesive film may further include a third adhesive layer on the surface of the first adhesive layer opposite to the second adhesive layer. That is, the circuit connection adhesive film is formed by, for example, sequentially stacking a second adhesive layer, a first adhesive layer, and a third adhesive layer. In this case, the third adhesive layer contains, for example, a thermosetting composition similar to the second adhesive layer.

In addition, the circuit-connecting adhesive film in the above embodiment is an anisotropic conductive adhesive film having anisotropic conductivity, but the circuit-connecting adhesive film may also be a conductive adhesive film without anisotropic conductivity.

<Method for Manufacturing Adhesive Film for Circuit Connection> The method for manufacturing the adhesive film for circuit connection 1 of this embodiment includes, for example, a preparatory step of preparing the first adhesive layer 2 described above (a first preparatory step) and a laminating step of laminating the second adhesive layer 3 described above on the first adhesive layer 2. The method for manufacturing the adhesive film for circuit connection 1 may further include a preparatory step of preparing the second adhesive layer 3 (a second preparatory step).

In the first preparation step, for example, a first adhesive layer 2 is formed on a substrate to obtain a first adhesive film, thereby preparing the first adhesive layer 2. Specifically, components (A), (B), and (C), as well as other components (D) and (E) as needed, are first added to an organic solvent and dissolved or dispersed by stirring, mixing, or kneading to prepare a varnish composition (a varnish of a photocurable composition). The varnish composition is then applied to a release-treated substrate using a doctor blade coater, roll coater, applicator, notched wheel coater, die coater, or the like. The organic solvent is then volatilized by heating, thereby forming a layer containing the photocurable composition on the substrate. Next, the layer containing the photocurable composition is irradiated with light to cure the photocurable composition, thereby forming a first adhesive layer 2 on the substrate (curing step). Thus, a first adhesive film is obtained.

The organic solvent used in preparing the varnish composition is preferably one that uniformly dissolves or disperses the various components. Examples include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These organic solvents may be used alone or in combination. Stirring, mixing, and kneading during the preparation of the varnish composition can be performed using, for example, a stirrer, attritor, three-roll mill, ball mill, bead mill, or homogenizer.

The substrate is not particularly limited as long as it has heat resistance that can withstand the heating conditions for volatilizing the organic solvent. For example, substrates (e.g., films) including oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. can be used.

The heating conditions for volatilizing the organic solvent from the varnish composition applied to the substrate are preferably such that the organic solvent fully volatilizes. For example, the heating conditions may be 40°C to 120°C and 0.1 minute to 10 minutes.

During the curing step, light irradiation with a wavelength of 150 nm to 750 nm (e.g., ultraviolet light) is preferably used. Light irradiation can be performed using, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, metal halide lamps, or light-emitting diode (LED) light sources. The amount of light irradiation is not particularly limited; for example, the cumulative amount of light at a wavelength of 365 nm can be 100 mJ/ ^cm² or greater, 200 mJ/ ^cm² or greater, or 300 mJ/cm² or ^greater . The irradiation amount of light can be, for example, 10,000 mJ/cm ² or less, 5,000 mJ/cm ² or less, or 3,000 mJ/cm ² or less in terms of the cumulative amount of light with a wavelength of 365 nm.

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

In the lamination step, the second adhesive layer 3 can be deposited on the first adhesive layer 2 by laminating the first adhesive film to the second adhesive film. Alternatively, a varnish composition (a thermosetting varnish) obtained by using components (a) and (b) and optionally other components is applied to the first adhesive layer 2, and the organic solvent is volatilized to deposit the second adhesive layer 3 on the first adhesive layer 2. The lamination step can also be performed during the first preparatory step. For example, after forming a layer containing a photocurable composition, a lamination step may be performed to obtain a laminate comprising a layer containing a photocurable composition (a precursor for the first adhesive layer 2) and a layer containing a thermosetting composition (the second adhesive layer 3). In this case, the obtained laminate can be irradiated with light to cure the layer containing the photocurable composition, completing the first preparatory step.

Examples of methods for laminating the first adhesive film and the second adhesive film include heat pressing, roll pressing, and vacuum lamination. Lamination can be performed at a temperature of 0°C to 80°C.

<Circuit Connection Structure and Manufacturing Method Thereof> The following describes a circuit connection structure and a manufacturing method thereof using the aforementioned circuit connection adhesive film 1 as a circuit connection material.

Figure 2 is a schematic cross-sectional view of a circuit connection structure according to one embodiment. As shown in Figure 2, circuit connection structure 10 includes: a first circuit component 13 having a first circuit substrate 11 and a first electrode 12 formed on a principal surface 11a of first circuit substrate 11; a second circuit component 16 having a second circuit substrate 14 and a second electrode 15 formed on a principal surface 14a of second circuit substrate 14; and a circuit connection portion 17 disposed between first circuit component 13 and second circuit component 16 to electrically connect first electrode 12 and second electrode 15.

The first circuit component 13 and the second circuit component 16 may be the same or different. They may be glass or plastic substrates with electrodes, printed wiring boards, ceramic wiring boards, flexible wiring boards, semiconductor integrated circuit (IC) chips, etc. The first circuit board 11 and the second circuit board 14 may be formed from inorganic materials such as semiconductors, glass, and ceramics; organic materials such as polyimide and polycarbonate; or glass/epoxy composites. The first electrode 12 and the second electrode 15 can be formed from gold, silver, tin, ruthenium, rhodium, palladium, zirconium, 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 can be circuit electrodes or bump electrodes. At least one of the first electrode 12 and the second electrode 15 can be a bump electrode. In FIG2 , the second electrode 15 is a bump electrode.

Circuit connection portion 17 comprises a cured product of the aforementioned adhesive film 1. Circuit connection portion 17 includes, for example, a first region 18 located on the first circuit component 13 side in the direction in which the first and second circuit components 13 and 16 face each other (hereinafter referred to as the "facing direction"), comprising a cured product comprising components (A) and (B) of the aforementioned photocurable composition, other than the conductive particles 4; a second region 19 located on the second circuit component 16 side in the facing direction, comprising a cured product comprising components (a) and (b) of the aforementioned thermosetting composition; and conductive particles 4 located at least between first electrode 12 and second electrode 15 to electrically connect the first and second electrodes 12 and 15. The circuit connection portion may not have two regions like the first region 18 and the second region 19 , and may include, for example, a mixture of a cured product of the photocurable composition other than the conductive particles 4 and a cured product of the thermosetting composition.

FIG3 is a schematic cross-sectional view illustrating a method for manufacturing a circuit connection structure 10. As shown in FIG3 , the method for manufacturing a circuit connection structure 10 includes, for example, the following steps: interposing the aforementioned adhesive film 1 between a first circuit component 13 having a first electrode 12 and a second circuit component 16 having a second electrode 15, and then thermally pressing the first circuit component 13 and the second circuit component 16 to electrically connect the first electrode 12 and the second electrode 15 to each other.

Specifically, as shown in FIG3(a), first, a first circuit component 13 including a first circuit substrate 11 and a first electrode 12 formed on a main surface 11a of the first circuit substrate 11, and a second circuit component 16 including a second circuit substrate 14 and a second electrode 15 formed on a main surface 14a of the second circuit substrate 14 are prepared.

Next, first circuit component 13 and second circuit component 16 are arranged so that first electrode 12 and second electrode 15 face each other, and adhesive film 1 is placed between first circuit component 13 and second circuit component 16. For example, as shown in FIG3(a), adhesive film 1 is laminated onto first circuit component 13 so that the side of first adhesive layer 2 faces mounting surface 11a of first circuit component 13. Next, second circuit component 16 is arranged on first circuit component 13 with adhesive film 1 laminated thereon, so that first electrode 12 on first circuit substrate 11 and second electrode 15 on second circuit substrate 14 face each other.

As shown in Figure 3(b), while heating first circuit member 13, adhesive film 1, and second circuit member 16, pressure is applied to the first circuit member 13 and the second circuit member 16 in the thickness direction, thereby thermocompression bonding the first circuit member 13 and the second circuit member 16. At this time, as indicated by the arrow in Figure 3(b), the second adhesive layer 3, which contains a fluid, uncured thermosetting composition, flows to fill the gaps between the second electrodes 15 and cures due to the heating. Thus, first electrode 12 and second electrode 15 are electrically connected to each other via conductive particles 4. Furthermore, first circuit component 13 and second circuit component 16 are bonded to each other, resulting in circuit connection structure 10 as shown in FIG2 . In the manufacturing method of circuit connection structure 10 of this embodiment, since first adhesive layer 2 is a pre-cured layer, conductive particles 4 are fixed within first adhesive layer 2. Furthermore, first adhesive layer 2 hardly flows during the thermal pressing process, effectively capturing conductive particles between the opposing electrodes. This reduces the connection resistance between opposing electrodes 12 and 15. Consequently, a circuit connection structure with excellent connection reliability is achieved.

<Adhesive Film Storage Assembly> Figure 4 is a perspective view of an adhesive film storage assembly according to one embodiment. As shown in Figure 4 , the adhesive film storage assembly 20 includes an adhesive film 1 for circuit connection, a reel 21 around which the adhesive film 1 is wound, and a storage member 22 for storing the adhesive film 1 and the reel 21.

As shown in Figure 4, the adhesive film 1 is, for example, in the form of a strip. The strip-shaped adhesive film 1 is produced by, for example, cutting a sheet into strips of a desired width. A substrate can be placed on one surface of the adhesive film 1. The substrate can be, for example, the PET film described above.

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

The first side plate 24 is, for example, a circular plate made of plastic, and an opening with a circular cross-section is provided at the center of the first side plate 24 .

The first side plate 24 includes a core 23 around which the adhesive film 1 is wound. The core 23 is made of, for example, plastic and is formed into a ring shape with a thickness equal to the width of the adhesive film 1. The 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. Furthermore, a shaft hole 26 is provided in the center of the reel 21, which serves as a portion for inserting the rotating shaft of a reel or output device (not shown). When the rotating shaft of the reel or output device is inserted into this shaft hole 26 and then driven, the reel 21 rotates without idling. A desiccant container for storing desiccant can also be inserted into the shaft hole 26.

The second side plate 25 is similar to the first side plate 24 and is a circular plate made of plastic, for example. A circular opening having the same diameter as the opening of the first side plate 24 is provided at the center of the second side plate 25 .

The storage member 22 is, for example, in a bag shape, and stores the adhesive film 1 and the reel 21. The storage member 22 has an insertion port 27 for storing (inserting) the adhesive film 1 and the reel 21 inside the storage member 22.

The storage member 22 has a viewing portion 28 that allows the interior of the storage member 22 to be viewed from the outside. The storage member 22 shown in FIG.

The visual portion 28 is transmissive to visible light. For example, when the transmittance of the visual portion 28 to light is measured in a wavelength range of 450 nm to 750 nm, there is at least one region between 450 nm and 750 nm in which the average transmittance of light is greater than 30% and the wavelength width is 50 nm. The transmittance of the visual portion 28 to light can be obtained by making a sample of a specified size by cutting the visual portion 28 and measuring the transmittance of the sample to light using an ultraviolet-visible spectrophotometer. The storage component 22 has such a visual portion 28, so that various information inside the storage component 22, such as the product name, batch number, and expiration date attached to the reel 21, can also be confirmed from the outside of the storage component 22. This can prevent the mixing of incorrect products and improve the efficiency of sorting operations.

The transmittance of the visual portion 28 to light having a wavelength of 365 nm is 10% or less. The transmittance of the visual portion 28 to light having a wavelength of 365 nm is 10% or less, thereby suppressing the curing of the thermosetting composition caused by light entering the interior from the outside of the housing component 22 and residual photopolymerization initiators in the first adhesive layer 2. 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 to connect circuit components to each other, the connection resistance between opposing electrodes can be reduced. From the perspective of further suppressing the generation of free radicals from the photopolymerization initiator, the transmittance of the visual portion 28 to light having a wavelength of 365 nm is preferably 10% or less, more preferably 5% or less, further preferably 1% or less, and particularly preferably 0.1% or less.

From a similar perspective, the maximum transmittance of the visual portion 28 for light in a wavelength range capable of generating free radicals, cations, or anions from the photopolymerization initiator (component (B)) is preferably 10% or less, more preferably 5% or less, further preferably 1% or less, and particularly preferably 0.1% or less. Specifically, the maximum transmittance of the visual portion 28 for light in a wavelength range of 254 nm to 405 nm is preferably 10% or less, more preferably 5% or less, further preferably 1% or less, and particularly preferably 0.1% or less.

The visual portion 28 (housing component 22) is formed of a sheet having a thickness of 10 μm to 5000 μm, for example. The sheet includes a material whose transmittance of the visual portion 28 to light of a wavelength of 365 nm is less than 10%. Such a material may contain one component or a plurality of components. Examples of such a material include low-density polyethylene, linear low-density polyethylene, polycarbonate, polyester, polyacrylate, polyamide, glass, and the like. These materials may also contain ultraviolet absorbers. The visual portion 28 may also have a laminated structure formed by laminating a plurality of layers having different light transmittances. In this case, each layer constituting the visual portion 28 may contain the materials described above.

In order to prevent air from entering from the outside during storage, the insertion port 27 can be sealed by, for example, using a sealing machine. In this case, it is preferable to remove the air in the storage member 22 before sealing the insertion port 27. It can be expected that the humidity in the storage member 22 will decrease from the initial stage of storage, and the entry of air from the outside will be prevented. In addition, by the inner surface of the storage member 22 being in close contact with the reel 21, the inner surface of the storage member 22 and the surface of the reel 21 due to vibration during transportation can be prevented from rubbing against foreign matter, and scratches on the outer surfaces of the side plates 24 and 25 of the reel 21 can be prevented.

In the aforementioned embodiment, the storage member is configured so that the entire storage member serves as the viewing portion. In another embodiment, the storage member may include a viewing portion on a portion of the storage member. For example, the storage member may include a rectangular viewing portion approximately in the center of a side surface of the storage member. In this case, the portion of the storage member other than the viewing portion may be black, for example, to prevent transmission of ultraviolet and visible light.

In the above embodiment, the container is in the form of a bag. However, the container may also be in the form of a box. The container preferably has a cutout for opening. This facilitates opening during use. [Example]

The present invention is described in more detail below with reference to embodiments, but the present invention is not limited to the embodiments.

<Synthesis of Polyurethane Acrylate (UA1)> In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler with a calcium chloride drying tube, and a nitrogen inlet, 2500 parts by mass (2.50 mol) of poly(1,6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei Chemicals Co., Ltd., number-average molecular weight 1000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich) were uniformly added dropwise over 3 hours. Nitrogen was then introduced into the reaction vessel and the reaction was carried out by heating the reaction vessel to 70°C to 75°C. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (Sigma-Aldrich) were added to the reaction vessel, followed by 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich). The mixture was reacted at 70°C in an air atmosphere for 6 hours. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of polyurethane acrylate (UA1) was 15,000. The weight-average molecular weight was determined by gel permeation chromatography (GPC) using a calibration curve derived from standard polystyrene under the following conditions. (Measurement Conditions) Apparatus: 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: 120 mg/3 mL Solvent: Tetrahydrofuran Injection volume: 60 μL Pressure: 2.94×10 ⁶ Pa (30 kgf/cm ² ) Flow rate: 1.00 mL/min

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

<Polyester Urethane Resin Preparation Method> In a stainless steel autoclave equipped with a stirrer, thermometer, condenser, vacuum generator, and nitrogen inlet, 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were placed, along with 0.02 parts by mass of tetrabutoxytitanium ester as a catalyst. The mixture was then heated to 220°C under a nitrogen stream and stirred for 8 hours. The pressure was then reduced to atmospheric pressure (760 mmHg) and cooled to room temperature. A white precipitate formed. The precipitate was removed, washed with water, and vacuum-dried to obtain polyester polyol. The obtained polyester polyol was thoroughly dried, dissolved in methyl ethyl ketone (MEK), and placed in a four-necked flask equipped with a stirrer, dropping funnel, reflux cooler, and nitrogen inlet. Dibutyltin laurate was added as a catalyst at a rate of 0.05 parts by mass per 100 parts by mass of the polyester polyol. 4,4'-diphenylmethane diisocyanate was dissolved in MEK at a rate of 50 parts by mass per 100 parts by mass of the polyester polyol and added using a dropping funnel. The mixture was stirred at 80°C for 4 hours to obtain the target polyester urethane resin.

<Preparation of Photocurable Varnishes (Varnish Compositions)> The following components were mixed in the amounts (parts by mass) shown in Table 1 to prepare varnishes for photocurable compositions 1 to 8.

(Polymerizable compound) A1: Dicyclopentadiene diacrylate (trade name: DCP-A, manufactured by Toagosei Co., Ltd.) A2: Polyurethane acrylate (UA1) synthesized as described above A3: 2-Methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd. (Photopolymerization initiator) B1: 1,2-Octanedione, 1-[4-(phenylthio)phenyl-, 2-(O-benzoyl oxime)] (Trade name: Irgacure (registered trademark) OXE01, manufactured by BASF) B2: Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyl oxime) (Trade name: Irgacure (registered trademark) OXE02, manufactured by BASF) (Conductive particles ) C1: Conductive particles prepared as described above (Thermal polymerization initiator) E1: Benzoyl peroxide (trade name: NYPER BMT-K40, manufactured by NOF Corporation) (Thermoplastic resin) F1: Polyester urethane resin synthesized as described above (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 AEROSIL Co., Ltd., average particle size (primary particle size): 12 nm) (Solvent) I1: Methyl ethyl ketone

[Table 1] 1 2 3 4 5 6 7 8 Composition (mass) polymerizable compounds A1 5 5 5 5 5 5 5 5 A2 37.5 37.5 37.5 37.5 37.5 37.5 37.5 37.5 A3 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Photopolymerization initiator B1 0.5 - - - - - 1.25 - B2 - 0.5 0.4 0.3 0.75 1 - - conductive particles C1 30 30 30 30 30 30 30 30 Thermal polymerization initiator E1 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Thermoplastic resin F1 35 35 35 35 35 35 35 35 coupling agent G1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Filling material H1 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 solvent I1 150 150 150 150 150 150 150 150 Content of photopolymerization initiator (mass %) 0.59 0.59 0.47 0.36 0.88 1.18 1.47 -

<Preparation of a Thermosetting Composition Varnish (Varnish Composition)> The polymerizable compounds a1 to a3, thermal polymerization initiator b1, coupling agent g1, filler h1, and solvent i1 used in the photocurable composition were the same as those in the photocurable composition. The thermoplastic resin f1 used the following components. These components were mixed in the amounts (parts by mass) shown in Table 2 to prepare a varnish for the thermosetting composition 1. (Thermoplastic Resin) f1: Phenoxy Resin (Trade Name: PKHC, manufactured by Union Carbide Corporation)

[Table 2] 1 Composition (mass) polymerizable compounds a1 5 a2 27.5 a3 1.5 Thermal polymerization initiator b1 2.5 Thermoplastic resin f1 35 coupling agent g1 1.0 Filling material h1 2.5 solvent i1 150

(Example 1) [Preparation of the First Adhesive Film] A coating apparatus was used to apply a varnish of photocurable composition 1 onto a 50 μm thick PET film. This was then dried with hot air at 70°C for 3 minutes, forming a layer of photocurable composition 1 with a thickness (after drying) of 4 μm on the PET film. The thickness was measured using a contact thickness gauge. Furthermore, the use of a contact thickness gauge reflects the size of the conductive particles, measuring the thickness of the area containing the conductive particles. Therefore, after depositing the second adhesive layer to create a two-layer circuit connection adhesive film, the thickness of the first adhesive layer located between adjacent conductive particles was measured using the method described below.

Next, the layer containing photocurable composition 1 was irradiated with light from a metal halide lamp at a cumulative light intensity of 1500 mJ/ ^cm² to polymerize the polymerizable compound. This cured the photocurable composition 1, forming a first adhesive layer. This procedure yielded a first adhesive film (thickness of the conductive particle region: 4 μm) on the PET film. The conductive particle density at this point was approximately 7000 pcs/ ^mm² .

[Preparation of the Second Adhesive Film] Using a coating device, a clear coat of thermosetting composition 1 was applied to a 50 μm thick PET film. This was then dried with hot air at 70°C for 3 minutes to form an 8 μm thick second adhesive layer (containing thermosetting composition 1) on the PET film. This procedure yielded a second adhesive film having a second adhesive layer on the PET film.

[Preparation of Circuit Connection Adhesive Film] The first and second adhesive films were placed with their respective adhesive layers facing each other. They were heated at 40°C and laminated with a PET film substrate using a roll press. This produced a two-layered circuit connection adhesive film consisting of the first and second adhesive layers.

The thickness of the first adhesive layer of the fabricated circuit connection adhesive film was measured using the following method. First, the circuit connection adhesive film was sandwiched between two sheets of glass (approximately 1 mm thick) and cast using a resin composition consisting of 100 g of bisphenol A epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of hardener (trade name: Epomount Hardener, manufactured by Refine Tec Co., Ltd.). The film was then cross-sectioned using a grinder, and the thickness of the first adhesive layer located between adjacent conductive particles was measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Co., Ltd.). The thickness of the first adhesive layer is 2 μm.

[Fabrication of Circuit Connection Structure] A circuit connection adhesive film was used to bond a 25 μm-pitch COF (manufactured by FLEXSEED) to a glass substrate with a thin-film electrode (1200 Å height) made of amorphous indium tin oxide (ITO) on a glass substrate (manufactured by Geomatec). Using a heat press (contact heat type, manufactured by Taiyo Machinery Co., Ltd.), the two layers were heated and pressed at 170°C and 6 MPa for 4 seconds, creating a circuit connection structure (connection structure). Furthermore, during connection, the circuit-connecting adhesive film is disposed on the glass substrate in such a manner that the surface of the first adhesive layer side of the circuit-connecting adhesive film faces the glass substrate.

<Evaluation of Circuit Connection Structures> [Particle Mobility Evaluation] The particle mobility of the resin-exuded portion of the circuit connection adhesive film in the resulting circuit connection structures was evaluated using a microscope (ECLIPSE L200, manufactured by Nikon Corporation). Specifically, the fabricated circuit connection structures were observed from the glass substrate side using a microscope, and the particle state of the portion extending outward from 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 seepage area is evaluated as 1, the state where the particles move slightly but no connection between particles is observed is evaluated as 2, and the state where the particles flow and the connection between particles is observed is evaluated as 3.

[Connection Resistance Evaluation] The connection resistance between opposing electrodes of the obtained circuit connection structures was measured using a multimeter immediately after connection and after the high-temperature, high-humidity test. The high-temperature, high-humidity test was conducted by placing the structures in a constant temperature and humidity chamber at 85°C and 85% RH for 200 hours. The connection resistance was calculated as the average of the resistances between the opposing electrodes at 16 locations.

[Peeling Evaluation] A microscope (ECLIPSE L200, manufactured by Nikon Corporation) was used to evaluate the presence of peeling in the circuit connection sections of the circuit connection structures after the high-temperature and high-humidity test. Specifically, the circuit connection structures fabricated as described above were observed from the glass substrate side using a microscope, and the peeling state between the glass substrate and the circuit connection adhesive film was evaluated in three stages. The percentage of the circuit connection adhesive film that peeled from the glass substrate was determined. A rating was assigned for films with little to no peeling (less than 5% of the total area), B rating for films with minimal peeling (5% to less than 20% of the total area), and C rating for films with significant peeling (20% or more of the total area).

(Examples 2 to 6 and Comparative Examples 1 to 2) Circuit connection adhesive films and circuit connection structures were prepared in the same manner as in Example 1, except that Photocurable Compositions 2 to 8 were used as the photocurable compositions. The circuit connection structures were evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

[Table 3] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Photocurable composition 1 2 3 4 5 6 Connection resistance (Ω) After connecting 1.9 1.8 1.7 1.8 1.7 1.8 After high temperature and high humidity test 2.5 2.3 2.4 2.4 2.6 2.5 Particle mobility 1 1 1 2 1 1 peeling A A A A A B

[Table 4] Comparative example 1 Comparative example 2 Photocurable composition 7 8 Connection resistance (Ω) After connecting 1.6 1.6 After high temperature and high humidity test 2.9 2.4 Particle mobility 1 3 peeling C A

1: Circuit connection adhesive film 2: First adhesive layer 2a: Surface of the first adhesive layer opposite to the second adhesive layer 3: Second adhesive layer 3a: Surface of the second adhesive layer opposite to the first adhesive layer 4: Conductive particles 5: Adhesive component 10: Circuit connection structure 11: First circuit substrate 11a: Main surface (mounting surface) of the first circuit substrate 12: Circuit electrode (first electrode) 13: First circuit component 14: Second circuit substrate 14a: Second Main surface of the second circuit board 15: Bump electrode (second electrode) 16: Second circuit component 17: Circuit connection portion 18: First area 19: Second area 20: Adhesive film storage assembly 21: Reel 22: Storage member 23: Reel core 24: First side panel 25: Second side panel 26: Axis hole 27: Insertion port 28: Visible area d1: Thickness (distance) of the first adhesive layer d2: Thickness (distance) of the second adhesive layer S: Boundary between the first and second adhesive layers

Figure 1 is a schematic cross-sectional view of an adhesive film for circuit connection according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view of a circuit connection structure according to one embodiment of the present invention. Figure 3 is a schematic cross-sectional view illustrating the manufacturing steps of the circuit connection structure according to one embodiment of the present invention. Figure 4 is a perspective view of an adhesive film storage assembly according to one embodiment of the present invention.

1: Adhesive film for circuit connection

2: First adhesive layer

2a: The surface of the first adhesive layer opposite to the second adhesive layer.

3: Second adhesive layer

3a: The surface of the second adhesive layer opposite to the first adhesive layer

4: Conductive particles

5: Follow-up Ingredients

d1: Thickness of the first adhesive layer (distance)

d2: Thickness of the second adhesive layer (distance)

S: The boundary between the first and second adhesive layers

Claims (11)

An adhesive film for circuit connection includes: a first adhesive layer; and a second adhesive layer deposited on the first adhesive layer. The first adhesive layer comprises a cured product of a photocurable composition, and the second adhesive layer comprises a thermosetting composition. The photocurable composition contains a polymerizable compound, a photopolymerization initiator having an oxime ester structure, and conductive particles. The content of the photopolymerization initiator is 0.3% by mass to 1.2% by mass, based on the total amount of components other than the conductive particles in the photocurable composition. The circuit connection adhesive film according to claim 1, wherein the polymerizable compound is a free radical polymerizable compound having a free radical polymerizable group. The circuit connection adhesive film according to claim 1 or claim 2, wherein the thermosetting composition contains a radical polymerizable compound having a radical polymerizable group. The circuit connection adhesive film according to claim 1 or claim 2, wherein the thickness of the first adhesive layer is 0.1 to 0.8 times the average particle size of the conductive particles. The circuit connection adhesive film according to claim 1 or claim 2, wherein the photopolymerization initiator having an oxime ester structure is a compound having a structure represented by the following formula (VI): 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. A method for manufacturing an adhesive film for circuit connection includes: a preparation step of preparing a first adhesive layer; and a lamination step of laminating a second adhesive layer comprising a thermosetting composition on the first adhesive layer. The preparation step includes irradiating a layer comprising a photocurable composition with light to cure the photocurable composition, thereby obtaining the first adhesive layer. The photocurable composition contains a polymerizable compound, a photopolymerization initiator having an oxime ester structure, and conductive particles. The content of the photopolymerization initiator is 0.3% by mass to 1.2% by mass, based on the total amount of components other than the conductive particles in the photocurable composition. The method for producing a circuit connection adhesive film according to claim 6, wherein the polymerizable compound is a radical polymerizable compound having a radical polymerizable group. The method for producing a circuit connection adhesive film according to claim 6 or claim 7, wherein the thermosetting composition contains a radically polymerizable compound having a radically polymerizable group. The method for manufacturing a circuit connection adhesive film according to claim 6 or claim 7, wherein the thickness of the first adhesive layer is 0.1 to 0.8 times the average particle size of the conductive particles. A method for manufacturing a circuit connection structure comprises: interposing the circuit connection adhesive film according to any one of claims 1 to 5 between a first circuit component having a first electrode and a second circuit component having a second electrode, and thermally pressing the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other. An adhesive film storage set comprising: the circuit connection adhesive film according to any one of claims 1 to 5; and a storage member for storing the adhesive film, wherein the storage member has a visible portion that allows the interior of the storage member to be viewed from the outside, and the transmittance of the visible portion to light with a wavelength of 365 nm is 10% or less.