TWI851680B - Adhesive film for circuit connection, method for manufacturing circuit connection structure, and adhesive film storage set - Google Patents

Abstract

The circuit connection adhesive film 11 includes: a peelable support film 12, a first adhesive layer 13 disposed on the support film and containing conductive particles P, and a second adhesive layer 14 laminated on the first adhesive layer 13, and the thickness of the first adhesive layer is 0.1 to 1.0 times the average particle size of the conductive particles.

Description

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

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

Previously, various adhesive materials were used for circuit connection. For example, as an adhesive material for connecting a liquid crystal display to a tape carrier package (TCP), connecting a flexible printed circuit (FPC) to a TCP, or connecting an FPC to a printed wiring board, an adhesive film for circuit connection in which conductive particles are dispersed and which has anisotropic conductivity has been used. Specifically, a circuit connection portion formed by the circuit connection adhesive film is used to connect circuit components to each other, and the electrodes on the circuit components are electrically connected to each other via the conductive particles in the circuit connection portion, thereby obtaining a circuit connection structure.

The adhesive film for circuit connection includes, for example, an adhesive component containing a thermoplastic resin, and conductive particles formulated as needed, and is formed into a film as an adhesive layer on a substrate such as a polyethylene terephthalate (PET) film. Furthermore, the adhesive film is sometimes used in the form of a reel formed by cutting the entire film sheet into a strip of a width suitable for the purpose and winding the strip around a winding core to form a winding body (for example, refer to Patent Document 1).

[Prior art literature]

[Patent Literature]

Patent document 1: Japanese Patent Publication No. 2003-34468

However, when using adhesive film to connect driver integrated circuits (driver ICs) and liquid crystal display (LCD) modules, the adhesive film was previously transferred to the glass panel first. However, in recent years, considering the trend of reducing the amount of adhesive film used in order to reduce the manufacturing cost of LCDs and the demand for panel design with narrow bezels, a manufacturing method of first attaching the adhesive film to a flexible substrate such as Chip On Film (COF) or FPC has begun to be adopted.

However, when using existing adhesive films, it is difficult to efficiently capture conductive particles between circuit electrodes, which deteriorates conduction reliability or increases the risk of short circuits due to the concentration of uncaptured conductive particles between circuits.

The present invention is completed to solve the above-mentioned problem, and its purpose is to provide a circuit connection adhesive film for a circuit connection structure that can obtain excellent connection reliability between opposing circuit components even when the circuit connection is first attached to a flexible substrate, and a manufacturing method of the circuit connection structure using the same, as well as an adhesive film storage group.

The circuit connection adhesive film of one aspect of the present invention includes: a peelable support film, a first adhesive layer disposed on the support film and containing conductive particles, and a second adhesive layer laminated on the first adhesive layer, and the thickness of the first adhesive layer is 0.1 to 1.0 times the average particle size of the conductive particles.

According to the circuit connection adhesive film, even if the circuit connection is first attached to a flexible substrate, a circuit connection structure with excellent connection reliability between opposing circuit components can be obtained. In the first adhesive layer, it is preferred that more than 90% of the conductive particles are separated from other conductive particles.

The first adhesive layer may include a cured product of the first curable composition, and the first curable composition may contain a free radical polymerizable compound having a free radical polymerizable group.

The second adhesive layer may include a second curable composition, and the second curable composition may contain a free radical polymerizable compound having a free radical polymerizable group.

The manufacturing method of the circuit connection structure of one aspect of the present invention includes: placing the first adhesive layer and the second adhesive layer of the above-mentioned circuit connection adhesive film between a first circuit component having a first electrode and a second circuit component having a second electrode, and hot pressing the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other.

According to this method, even when the circuit connection is performed by first attaching the circuit connection adhesive film to the flexible substrate, a circuit connection structure with excellent connection reliability between opposing circuit components can be obtained.

That is, in the manufacturing method of the circuit connection structure of the present invention, the first circuit component has a flexible substrate, and includes the step of attaching the circuit connection adhesive film to the first circuit component in such a way that the second adhesive layer contacts the first circuit component.

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

According to the present invention, a circuit connection adhesive film for a circuit connection structure that can obtain excellent connection reliability between opposing circuit components even when the circuit connection is first attached to a flexible substrate, a method for manufacturing a circuit connection structure using the same, and an adhesive film storage set can be provided.

1: Circuit connection structure

2: First circuit component

3: Second circuit component

4: Hardened adhesive film for circuit connection (second adhesive layer and first adhesive layer)

5: Main body

5a: Mounting surface

6: First circuit electrode

7: Main body

7a: Mounting surface

8: Second circuit electrode

9: First Area

10: Second area

11: Adhesive film for circuit connection

12: Support membrane

13: First adhesive layer

14: Second adhesive layer

15: Peel off membrane

21: Pull out the roller

22: Roller

23: Coating machine

24, 25: Magnet

120: Next, the membrane containment group

121: Scroll

122: Containment components

123: Roll core

124: First side panel

125: Second side panel

126: shaft hole

127: Insertion port

128: Visualization Department

P: Conductive particles

S: The boundary between the first adhesive layer and the second adhesive layer

W: Then apply the paste

FIG1 is a schematic cross-sectional view showing an embodiment of the adhesive film for circuit connection of the present invention.

FIG2 is a schematic cross-sectional view showing the steps of a method for manufacturing a circuit connection structure.

FIG3 is a schematic cross-sectional view showing the laminate obtained through FIG2.

FIG4 is a schematic cross-sectional view showing the subsequent steps of FIG2.

FIG5 is a schematic cross-sectional view showing the circuit connection structure obtained through FIG4.

FIG6 is a schematic diagram showing the manufacturing steps of the circuit connection adhesive film shown in FIG1.

Figure 7 is a schematic diagram showing the state of the magnetic field application step.

FIG8 is a schematic cross-sectional view showing the state of the circuit connection adhesive film after the magnetic field application step and the drying step.

FIG9 is a schematic cross-sectional view showing the lamination step after FIG7.

FIG. 10 is a three-dimensional diagram showing an implementation form of the adhesive film storage group of the present invention.

The following is a detailed description of the embodiments of the present invention with reference to the drawings as appropriate. Furthermore, in this specification, the upper and lower limits recorded 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)acryl".

<Adhesive film for circuit connection>

FIG1 is a schematic cross-sectional view of an embodiment of a circuit connection adhesive film. As shown in FIG1 , the circuit connection adhesive film 11 (hereinafter also referred to as "adhesive film 11") includes a peelable support film 12, a first adhesive layer 13 disposed on the support film 12, and a second adhesive layer 14 laminated on the first adhesive layer 13. The first adhesive layer 13 contains conductive particles P.

In the adhesive film 11, the conductive particles P are dispersed in the first adhesive layer 13. Therefore, the adhesive film 11 is an anisotropic conductive adhesive film with anisotropic conductivity. The adhesive film 11 is used to place the first adhesive layer and the second adhesive layer between a first circuit component having a first electrode and a second circuit component having a second electrode, and to heat-press the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other.

In addition, when the connected circuit component has a flexible substrate, the circuit connection adhesive film 11 can be attached to the first circuit component in such a way that the second adhesive layer contacts the first circuit component.

In this embodiment, the thickness of the first adhesive layer 13 can be 0.1 to 1.0 times the average particle size of the conductive particles P, and preferably 0.1 to 0.7 times. In addition, in the first adhesive layer 13, more than 90% of the conductive particles P can be separated from other conductive particles.

In addition, in this embodiment, the ratio (X/Y) of the melt viscosity X of the first adhesive layer 13 to the minimum melt viscosity Y of the second adhesive layer 14 at the temperature Ty at which the second adhesive layer 14 shows the minimum melt viscosity Y can be 10 or more.

From the viewpoint of improving the adhesion with the circuit components, the ratio of melt viscosity (X/Y) is preferably 10 or more, more preferably 20 or more, further preferably 50 or more, and particularly preferably 100 or more. From the viewpoint of wettability with respect to the circuit components, the ratio of melt viscosity (X/Y) may be 10000 or less, 5000 or less, or 1000 or less. Based on these viewpoints, the ratio of melt viscosity (X/Y) may be 10 to 10000, 20 to 5000, 50 to 5000, or 100 to 1000. The melt viscosity X and the minimum melt viscosity Y can be confirmed by the following method: First, the minimum melt viscosity Y of the second adhesive layer is determined by measuring the melt viscosity of the second adhesive layer (and the temperature Ty at which the second adhesive layer shows the minimum melt viscosity Y), and then the melt viscosity X of the first adhesive layer at the temperature Ty is determined by measuring the melt viscosity of the first adhesive layer. In addition, the melt viscosity can also be measured after obtaining the adhesive film.

(Supporting membrane)

The support film 12 is formed of, for example, polyethylene terephthalate (PET), polyethylene, polypropylene, etc. The support film 12 may also contain any filler. In addition, the surface of the support film 12 may be subjected to a demolding treatment or a plasma treatment. The support film 12 may be peeled off after the first adhesive layer and the second adhesive layer are transferred to the circuit component.

(First adhesive layer)

The first adhesive layer, for example, includes a cured product of a first curable composition. The first curable composition may be a photocurable composition, a thermosetting composition, or a mixture of a photocurable composition and a thermosetting composition. The first curable composition, for example, includes (A) a polymerizable compound (hereinafter also referred to as "(A) component"), (B) a polymerization initiator (hereinafter also referred to as "(B) component"), and (C) conductive particles (hereinafter also referred to as "(C) component"). When the first curable composition is a photocurable composition, the first curable composition includes a photopolymerization initiator as the (B) component, and when the first curable composition is a thermosetting composition, the first curable composition includes a thermopolymerization initiator as the (B) component. Such a first adhesive layer can be obtained, for example, by subjecting the layer containing the first curable composition to light irradiation or heating to polymerize the (A) component and curing the first curable composition. That is, the first adhesive layer can include conductive particles and an adhesive component formed by light curing the first curable composition. The first adhesive layer can be a cured product formed by completely curing the first curable composition, or a cured product formed by partially curing the first curable composition. That is, when the first curable composition contains the (A) component and the (B) component, the adhesive component may contain or may not contain unreacted (A) component and (B) component. Furthermore, the first adhesive layer can also include a resin component other than the cured product of the curable composition. For example, the first adhesive layer may include a resin composition containing phenoxy resins such as PKHC, polyester urethane resins, polyurethane resins, acrylic rubber and other resin components. By using such a resin component, the melt viscosity of the second adhesive layer at the temperature (e.g., 100°C) at which the second adhesive layer exhibits the lowest melt viscosity can be adjusted to about 100,000 Pa.s to 10,000,000 Pa.s, and the melt viscosity ratio (X/Y) can be made greater than 10.

[(A) Component: polymerizable compound]

The (A) component is, for example, a compound that polymerizes by free radicals, cations, or anions generated by a polymerization initiator (photopolymerization initiator or thermal polymerization initiator) due to irradiation with light (such as ultraviolet light) or heating. The (A) component may be any of a monomer, an oligomer, or a polymer. As the (A) component, one compound may be used alone, or a plurality of compounds may be used in combination.

The component (A) has at least one polymerizable group. The polymerizable group is, for example, a group containing a polymerizable unsaturated double bond (ethylenic unsaturated bond). From the viewpoint of easily obtaining the desired melt viscosity, the viewpoint of not easily causing separation between the circuit component and the circuit connection part in a high temperature and high humidity environment, and the viewpoint 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 by free radicals. That is, the component (A) is preferably a free radical polymerizable compound. Examples of the free radical polymerizable group include: vinyl, allyl, styryl, alkenyl, styrene, (meth)acryl, maleimide, etc. The number of polymerizable groups in component (A) may be two or more from the viewpoint of obtaining the desired melt viscosity after polymerization and controlling the physical properties of the resin after curing, and may be 10 or less from the viewpoint of suppressing curing shrinkage during polymerization. In addition, in order to achieve a balance between crosslinking density and curing shrinkage, in addition to using a polymerizable compound having a number of polymerizable groups within the above range, a polymerizable compound 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, carboxylated nitrile rubber, etc.

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) (meth)acrylate ethyl, 2-ethoxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and (meth) n-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-diphenylpropane bismaleimide, N,N'-4,4-diphenyl ether bismaleimide, N,N'-3,3-diphenylsulfone bismaleimide, 2,2-bis(4-(4-maleimide phenoxy)phenyl)propane, 2,2-bis(3-sec-butyl-4-8(4-maleimide phenoxy)phenyl)propane, 1,1-bis(4-(4-maleimide phenoxy)phenyl)decane, 4,4'-cyclohexylene-bis(1-(4-maleimide phenoxy)-2- cyclohexyl)benzene, 2,2'-bis(4-(4-maleimide phenoxy)phenyl)hexafluoropropane, etc.

As the vinyl ether compound, there can be listed: diethylene glycol divinyl ether, dipropylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, trihydroxymethylpropane trivinyl ether, etc.

As allyl compounds, 1,3-diallyl phthalate, 1,2-diallyl phthalate, triallyl isocyanurate, etc. can be cited.

From the perspective of easily obtaining the desired melt viscosity, and from the perspective of being able to select compounds of various structures and being easily available, component (A) is preferably a (meth)acrylate compound. From the perspective of obtaining more excellent bonding properties, component (A) may be a (poly)urethane (meth)acrylate compound (urethane (meth)acrylate compound or polyurethane (meth)acrylate compound). In addition, from the perspective of obtaining more excellent bonding properties, component (A) may be a (meth)acrylate compound having a high Tg skeleton such as a dicyclopentadiene skeleton.

From the perspective of easily obtaining the desired melt viscosity, achieving a balance between crosslinking density and curing shrinkage, further reducing connection resistance, and improving connection reliability, the component (A) may be a compound (e.g., polyurethane (meth)acrylate) having a polymerizable group such as a vinyl group, an allyl group, or a (meth)acrylic group introduced into the terminal or side chain of a thermoplastic resin such as an acrylic resin, a phenoxy resin, or a polyurethane resin. In this case, from the perspective of excellent balance between crosslinking density and curing shrinkage, the weight average molecular weight of the component (A) may be 3,000 or more, 5,000 or more, or 10,000 or more. In addition, from the perspective of excellent compatibility with other components, the weight average molecular weight of the component (A) may be 1,000,000 or less, 500,000 or less, or 250,000 or less. Furthermore, the weight average molecular weight refers to the value measured by gel permeation chromatograph (GPC) according to the conditions described in the examples and using a calibration curve obtained from standard polystyrene.

As the (meth)acrylate compound, component (A) is preferably a radical polymerizable compound containing a phosphate structure represented by the following general formula (1). In this case, the bonding strength to the surface of inorganic materials (metals, etc.) is improved, so it is suitable for bonding between electrodes (for example, between circuit electrodes).

[In the formula, n represents an integer from 1 to 3, and R represents a hydrogen atom or a methyl group]

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

From the perspective of easily obtaining the desired melt viscosity and the perspective of easily obtaining the desired physical properties of the cured product, the content of the component (A) may be 5% by mass or more, 10% by mass or more, or 20% by mass or more, based on the total mass of the first curable composition. From the perspective of suppressing curing shrinkage during polymerization, the content of the component (A) may be 90% by mass or less, 80% by mass or less, or 70% by mass or less, based on the total mass of the first curable composition.

[(B) Component: polymerization initiator]

Component (B) may be a photopolymerization initiator (photoradical polymerization initiator, photocationic polymerization initiator or photoanionic polymerization initiator) that generates free radicals, cations or anions by irradiation with light having a wavelength within the range of 150 nm to 750 nm, preferably light having a wavelength within the range of 254 nm to 405 nm, and more preferably light having a wavelength of 365 nm (e.g., ultraviolet light); or may be a thermal polymerization initiator (thermal radical polymerization initiator, thermal cationic polymerization initiator or thermal anionic polymerization initiator) that generates free radicals, cations or anions by heat. From the perspective of easily obtaining the desired melt viscosity, further improving the connection resistance reduction effect and improving the connection reliability, and making it easier to harden at low temperature and in a short time, the component (B) is preferably a radical polymerization initiator (photoradical polymerization initiator or thermal radical polymerization initiator). As the component (B), one compound may be used alone or in combination. For example, the first curable composition may contain both a photopolymerization initiator and a thermal polymerization initiator as the component (B).

The photoradical polymerization initiator is decomposed by light to generate free radicals. That is, the photoradical polymerization initiator is a compound that generates free radicals by applying light energy from the outside. As the photoradical polymerization initiator, compounds having structures such as oxime ester structure, bisimidazole structure, acridine structure, α-aminophenyl alkyl ketone structure, aminobenzophenone structure, N-phenylglycine structure, acylphosphine oxide structure, benzyl dimethyl ketal structure, and α-hydroxyphenyl alkyl ketone structure can be listed. From the viewpoint of easily obtaining the desired melt viscosity and having a better effect of reducing the connection resistance, the photoradical polymerization initiator preferably has at least one structure selected from the group consisting of an oxime ester structure, an α-aminophenylalkyl ketone structure, and an acylphosphine oxide structure.

Specific examples of the compound 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-diphenyl 1-[4-(phenylthio)phenyl-,2-(o-benzoyl)oxime], ethyl ketone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(o-acetyl)oxime, etc.

Specific examples of compounds having an α-aminophenylalkyl ketone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one, 2-benzyl-2-dimethylamino-1-morpholinylphenyl)-butanone-1, etc.

Specific examples of compounds having an acylphosphine oxide structure include bis(2,6-dimethoxybenzyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide, 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide, etc.

Thermal radical polymerization initiators decompose by heat to generate free radicals. That is, thermal radical polymerization initiators are compounds that generate free radicals by applying thermal energy from the outside. As thermal radical polymerization initiators, any of the known organic peroxides and azo compounds can be selected. From the perspective of stability, reactivity and compatibility, organic peroxides with a one-minute half-life temperature of 90°C to 175°C and a weight average molecular weight of 180 to 1000 can be preferably used as thermal radical polymerization initiators. With a one-minute half-life temperature within this range, storage stability is better, and radical polymerization is high enough to cure in a short time.

Specific examples of organic peroxides include: 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, cumyl peroxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, tert-hexyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxypival ... tributyl peroxide, 1,1,3,3-tetramethylbutyl peroxide-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, tert-hexyl peroxide-2-ethylhexanoate, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide neoheptanoate, tert-pentyl peroxide-2-ethylhexanoate, di-tert-butyl peroxide hexahydrophthalate, tert-butyl peroxide-3,5,5-trimethylhexane tert-amyl peroxide, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, tert-amyl peroxide neodecanoate, tert-amyl peroxide-2-ethylhexanoate, di(3-methylbenzoyl)peroxide, dibenzoyl peroxide, di(4-methylbenzoyl)peroxide, tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peroxymaleic acid, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-lauric acid peroxide butyl ester, 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, peroxy-2-ethylhexyl monocarbonate tert-butyl ester, peroxybenzoic acid tert-hexyl ester, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, peroxybenzoic acid tert-butyl ester, peroxytrimethyladipate dibutyl ester, peroxyoctanoic acid tert-amyl ester, peroxyisononanoic acid tert-amyl ester, peroxybenzoic acid tert-amyl ester, etc.

Specific examples of azo compounds include: 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), 1,1'-azobis(1-cyclohexanecarbonitrile), etc.

From the perspective of excellent rapid curing and excellent connection resistance reduction effect, the content of component (B) can be 0.1% by mass or more, or 0.5% by mass or more, based on the total mass of the first curable composition. From the perspective of improved storage stability and excellent connection resistance reduction effect, the content of component (B) can be 15% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total mass of the first curable composition.

From the perspective of easily obtaining the desired viscosity, the first curable composition preferably contains at least one of a photopolymerization initiator and a thermal polymerization initiator as component (B), and from the perspective of easily manufacturing an adhesive film for circuit connection, it is more preferably a photopolymerization initiator.

[(C) Component: Conductive particles]

The component (C) is not particularly limited if it is a particle with conductivity, and may be a metal particle containing a metal such as Au, Ag, Ni, Cu, solder, etc.; a conductive carbon particle containing conductive carbon, etc. The component (C) may also be a coated conductive particle including a core and a coating layer covering the core, wherein the core includes non-conductive glass, ceramic, plastic (polystyrene, etc.), etc., and the coating layer includes the metal or conductive carbon. Among these, a coated conductive particle including a core and a coating layer covering the core may be preferably used, wherein the core includes a metal particle or plastic formed of a hot-melt metal, and the coating layer includes a metal or conductive carbon. In this case, the cured product of the first curable composition can be easily deformed by heating or pressurizing, so 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.

The (C) component may be an insulating coated conductive particle including the metal particles, conductive carbon particles or coated conductive particles and an insulating layer, wherein the insulating layer includes an insulating material such as a resin and covers the surface of the particle. If the (C) component is an insulating coated conductive particle, even if the content of the (C) component is high, the surface of the particles is coated with the resin, which can suppress short circuits caused by contact between the (C) components, and can also improve the insulation between adjacent electrode circuits. The (C) component can use one of the various conductive particles described above alone or in combination of two or more.

The maximum particle size of the (C) component needs to be smaller than the minimum spacing between the electrodes (the shortest distance between adjacent electrodes). From the perspective of excellent dispersibility and conductivity, the maximum particle size of the (C) component may be greater than 1.0 μm, greater than 2.0 μm, or greater than 2.5 μm. From the perspective of excellent dispersibility and conductivity, the maximum particle size of the (C) component may be less than 50 μm, less than 30 μm, or less than 20 μm. In this specification, the particle size of any 300 (pcs) conductive particles is measured by observation using a scanning electron microscope (SEM), and the maximum value obtained is set as the maximum particle size of the (C) component. Furthermore, in the case where the (C) component has protrusions or is not spherical, the particle size of the (C) component is set to the diameter of the circle circumscribing the conductive particles in the SEM image.

From the perspective of excellent dispersibility and conductivity, the average particle size of the component (C) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more. From the perspective of excellent dispersibility and conductivity, the average particle size of the component (C) may be 50 μm or less, 30 μm or less, or 20 μm or less. In this specification, the particle size of any 300 (pcs) conductive particles is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle size is set as the average particle size.

In the first adhesive layer, it is preferred that the component (C) is uniformly dispersed. From the perspective of obtaining a stable connection resistance, the particle density of the component (C) in the first adhesive layer may be 100 pcs/ ^mm2 or more, 1000 pcs/ ^mm2 or more, or 2000 pcs/ ^mm2 or more. From the perspective of improving the insulation between adjacent electrodes, the particle density of the component (C) in the first adhesive layer may be 100,000 pcs/ ^mm2 or less, 50,000 pcs/ ^mm2 or less, or 10,000 pcs/ ^mm2 or less.

From the perspective of further improving the conductivity, the content of the component (C) may 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 the component (C) may be 50 volume % or less, 30 volume % or less, or 20 volume % or less, based on the total volume of the first adhesive layer. Furthermore, the content of the component (C) in the first curable composition (based on the total volume of the first curable composition) may be the same as the above range.

[Other ingredients]

The first curable composition may further contain other components besides component (A), component (B) and component (C). Examples of other components include thermoplastic resins, coupling agents and fillers. These components may also be contained in the first adhesive layer.

Examples of thermoplastic resins include phenoxy resins, polyester resins, polyamide resins, polyurethane resins, polyesterurethane resins, and acrylic rubbers. When the first curable composition contains a thermoplastic resin, the first adhesive layer can be easily formed. In addition, when the first curable composition contains a thermoplastic resin, the stress of the first adhesive layer generated when the first curable composition is cured can be alleviated. In addition, when the thermoplastic resin has a functional group such as a hydroxyl group, the adhesion of the first adhesive layer can be easily improved. Regarding the content of the thermoplastic resin, for example, based on the total mass of the first curable composition, it can be greater than 5 mass % and less than 80 mass %.

As coupling agents, there can be listed silane coupling agents having organic functional groups such as (meth)acryl, butyl, amino, imidazole, and epoxy groups; silane compounds such as tetraalkoxysilane; tetraalkoxy titanium ester derivatives, polydialkyl titanium ester derivatives, etc. When the first curable composition contains a coupling agent, the adhesion can be further improved. The content of the coupling agent, for example, based on the total mass of the first curable composition, can be 0.1 mass% or more and can be 20 mass% or less.

As fillers, for example, non-conductive fillers (such as non-conductive particles) can be listed. When the first curable composition contains a filler, it can be expected that the connection reliability will be further improved. The filler can be either an inorganic filler or an organic filler. As inorganic fillers, for example, metal oxide particles such as silica particles, alumina particles, silica-alumina particles, titanium dioxide particles, and zirconia particles; inorganic particles such as nitride particles can be listed. As organic fillers, for example, organic particles such as silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, and polyimide particles can be listed. These particles can 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. Regarding the content of the filler, for example, based on the total volume of the first curable composition, it can be greater than 0.1 volume % and less than 50 volume %.

The first curable composition may also contain other additives such as a softener, a promoter, a degradation inhibitor, a colorant, a flame retardant, and a tactile agent. Based on the total mass of the first curable composition, the content of these additives may be, for example, 0.1 mass% to 10 mass%. These additives may also be contained in the first adhesive layer.

The first curable composition may also contain a thermosetting resin instead of component (A) and component (B), or in addition to component (A) and component (B). Thermosetting resin is a resin that cures by heat and has at least one thermosetting group. Thermosetting resin is, for example, a compound that reacts with a curing agent by heat and thereby crosslinks. As the thermosetting resin, one compound may be used alone, or a plurality of compounds may be used in combination.

From the perspective of easily obtaining the desired melt viscosity, further improving the effect of reducing the connection resistance and improving the connection reliability, the thermosetting group may be, for example, an epoxy group, an oxycyclobutane group, an isocyanate group, etc.

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

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

When the first curable composition contains a thermosetting resin, the first curable composition may also contain a curing agent for the thermosetting resin described above. Examples of the curing agent for the thermosetting resin include thermal free radical generators, thermal cation generators, and thermal anion generators. The content of the curing agent may be, for example, 0.1 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the thermosetting resin.

The first adhesive layer may also contain unreacted (A) component, unreacted (B) component and other components derived from the first curable composition. It is speculated that when the adhesive film of this embodiment is stored and transported in an existing storage member, unreacted (B) component remains in the first adhesive layer, and thus a portion of the second curable composition in the second adhesive layer is cured during storage and transportation, resulting in undesirable conditions such as easy separation between the circuit component and the circuit connection portion in a high temperature and high humidity environment, and reduced effect of reducing the connection resistance of the adhesive film. Therefore, from the viewpoint of suppressing the occurrence of the above-mentioned defective condition, the content of the component (B) in the first adhesive layer may be 15% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total mass of the first adhesive layer. The content of the component (B) in the first adhesive layer may be 0.1% by mass or more, based on the total mass of the first adhesive layer. Furthermore, when the first adhesive layer contains a photopolymerization initiator as the component (B), the occurrence of the above-mentioned defective condition may be suppressed by accommodating the adhesive film in a accommodating member described later.

From the perspective of less likely to peel off, the melt viscosity X of the first adhesive layer at the temperature Ty at which the second adhesive layer shows the lowest melt viscosity Y can be 1000 Pa.s or more, 10000 Pa.s or more, or 50000 Pa.s or more. From the perspective of excellent wettability to the substrate, the melt viscosity X can be 10000000 Pa.s or less, 1000000 Pa.s or less, or 500000 Pa.s or less. The melt viscosity X can be adjusted by changing the composition of the first curable composition, changing the curing conditions of the first curable composition, etc.

From the viewpoint of facilitating the capture of conductive particles between electrodes and further reducing the connection resistance, the thickness of the first adhesive layer may be more than 0.1 times, more than 0.2 times, or more than 0.3 times the average particle size of the conductive particles. From the viewpoint of making it easier to crush the conductive particles when they are sandwiched between opposing electrodes during hot pressing and further reducing the connection resistance, the thickness of the first adhesive layer may be less than 1.0 times, less than 0.8 times, or less than 0.7 times the average particle size of the conductive particles. From these viewpoints, the thickness of the first adhesive layer may be 0.1 to 0.7 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the average particle size of the conductive particles. Furthermore, the thickness of the adhesive layer refers to the thickness of the adhesive layer located at the separation portion of the adjacent conductive particles. When the thickness of the first adhesive layer and the average particle size of the conductive particles satisfy the above relationship, for example, as shown in FIG. 1, a portion of the conductive particles P in the first adhesive layer 13 may protrude from the first adhesive layer 13 to the second adhesive layer 14 side. In this case, the boundary S between the first adhesive layer 13 and the second adhesive layer 14 is located at the separation portion of the adjacent conductive particles P. The conductive particles P may not be exposed on the surface of the first adhesive layer 13 opposite to the second adhesive layer 14 side, and the surface on the opposite side is a flat surface.

The thickness of the first adhesive layer can be appropriately set according to the electrode height of the connected circuit component, etc. The thickness of the first adhesive layer can be, for example, greater than 0.5 μm and less than 20 μm. Furthermore, in the case where a portion of the conductive particle is exposed from the surface of the first adhesive layer (for example, protruding to the side of the second adhesive layer), the distance from the surface of the first adhesive layer opposite to the side of the second adhesive layer to the boundary S between the first adhesive layer and the second adhesive layer at the separation portion of the adjacent conductive particles is the thickness of the first adhesive layer, and the exposed portion of the conductive particle is not included in the thickness of the first adhesive layer. The length of the exposed portion of the conductive particles can be, for example, greater than 0.1 μm and less than 20 μm. The thickness of the adhesive layer can be measured by the following method.

The adhesive film was sandwiched between two pieces of glass (thickness: about 1 mm), and 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.) was cast. The cross-section was polished using a grinder, and the thickness of each adhesive layer was measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-tech Science Co., Ltd.).

(Second adhesive layer)

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

[(a) Component: polymerizable compound]

Component (a) is, for example, a compound that polymerizes by free radicals, cations or anions generated by a polymerization initiator (photopolymerization initiator or thermal polymerization initiator) due to irradiation with light (e.g., ultraviolet light) or heating. As component (a), the compound exemplified as component (A) can be used. From the viewpoints of easy connection at low temperature and short time, easy acquisition of the desired melt viscosity, further improved connection resistance reduction effect and better connection reliability, component (a) is preferably a radical polymerizable compound having a radical polymerizable group that reacts by free radicals. Examples of preferred radical polymerizable compounds in component (a) and combinations of preferred radical polymerizable compounds are the same as those of component (A). When the component (a) is a radical polymerizable compound and the component (B) in the first adhesive layer is a photoradical polymerization initiator, by housing the adhesive film in a housing member described below, there is a tendency to significantly suppress the curing of the second curable composition during storage or transportation of the adhesive film.

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

From the perspective of easily obtaining the cross-linking density required for reducing connection resistance and improving 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 second curable composition. From the perspective of suppressing curing shrinkage during polymerization and obtaining 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 second curable composition.

[Component (b): polymerization initiator]

As component (b), the same polymerization initiator as the polymerization initiator exemplified as component (B) can be used. Component (b) is preferably a free radical polymerization initiator. Examples of preferred free radical polymerization initiators in component (b) are the same as those for component (B). As component (b), one compound can be used alone or a combination of multiple compounds can be used.

From the perspective of easier connection at low temperature and short time, and better 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 second curable 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 second curable composition.

[Other ingredients]

The second curable composition may further contain other components in addition to component (a) and component (b). Examples of other components include thermoplastic resins, coupling agents, fillers, softeners, accelerators, degradation inhibitors, colorants, flame retardants, and thixotropic agents. Details of other components are the same as those of other components in the first adhesive layer.

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

Regarding the content of the conductive particles in the second adhesive layer, for example, based on the total mass of the second adhesive layer, it can be less than 1 mass %, or can also be 0 mass %. The second adhesive layer preferably does not contain conductive particles.

From the perspective of obtaining excellent anti-blocking properties, the minimum melt viscosity Y of the second adhesive layer can be 50 Pa. s or more, 100 Pa. s or more, or 300 Pa. s or more. From the perspective of obtaining excellent filling properties (resin filling properties) between electrodes, the minimum melt viscosity Y can be 100000 Pa. s or less, 10000 Pa. s or less, or 5000 Pa. s or less. The minimum melt viscosity Y can be adjusted by changing the composition of the second curable composition, etc.

The thickness of the second adhesive layer can be appropriately set according to the electrode height of the connected circuit component. From the perspective of being able to fully fill the space between the electrodes and seal the electrodes to obtain better connection reliability, the thickness of the second adhesive layer can be greater than 5μm and less than 200μm. Furthermore, in the case where a portion of the conductive particles is exposed from the surface of the first adhesive layer (for example, protruding to the side of the second adhesive layer), the distance from the surface of the second adhesive layer opposite to the side of the first adhesive layer to the boundary S between the first adhesive layer and the second adhesive layer at the separation portion of the adjacent conductive particles is the thickness of the second adhesive layer.

From the perspective of being able to fully fill the space between the electrodes and seal the electrodes to obtain better reliability, the ratio of the thickness of the first adhesive layer to the thickness of the second adhesive layer (thickness of the first adhesive layer/thickness of the second adhesive layer) can be greater than 1 and less than 1000.

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

The above-mentioned circuit connection adhesive film may also be the following, which includes a peelable support film, and an adhesive layer provided on the support film and containing adhesive components and conductive particles, the conductive particles are biased to exist on the support film side, and are dispersed in a direction orthogonal to the thickness direction of the adhesive layer, and the adhesive layer has a first region containing a cured product of the above-mentioned first curable composition and a second region containing the above-mentioned second curable composition in the thickness direction of the adhesive layer from the support film side. The ranges of the first region and the second region in the thickness direction of the adhesive layer can be set in the same manner as the thicknesses of the above-mentioned first adhesive layer and the second adhesive layer, respectively. Regarding conductive particles, the same conditions as above can be set.

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

[Method for manufacturing circuit connection structure]

The manufacturing method of the circuit connection structure of the present embodiment is a method of manufacturing the circuit connection structure, wherein the circuit connection structure is formed by connecting a first circuit component provided with a first circuit electrode and a second circuit component provided with a second circuit electrode corresponding to the first circuit electrode via the circuit connection adhesive film of the present embodiment described above.

The method of this embodiment includes, for example, a preparation step of preparing the circuit connection adhesive film of the embodiment described above; a lamination step of laminating the circuit connection adhesive film on the first circuit component in such a manner that the second adhesive layer side of the circuit connection adhesive film faces the surface of the first circuit component on which the circuit electrode is disposed; and a heating step of laminating the circuit connection adhesive film on the first circuit component. In the pressing step, the second circuit component is arranged on the first circuit component laminated with the circuit connection adhesive film in a manner that the first circuit electrode and the second circuit electrode face each other, and the first circuit component and the second circuit component are pressed in the direction in which the first circuit electrode and the second circuit electrode face each other while heating the circuit connection adhesive film.

(Preparation steps)

In this step, the circuit connection adhesive film of the present embodiment described above can be manufactured.

The manufacturing method of the circuit connection adhesive film of this embodiment may include, for example: a preparation step of preparing the first adhesive layer described above (first preparation step); and a lamination step of laminating the second adhesive layer described above on the first adhesive layer. The manufacturing method of the circuit connection adhesive film may also further include: a preparation step of preparing the second adhesive layer (second preparation step).

In the first preparation step, for example, a first adhesive layer is formed on a support film to obtain a first adhesive film, thereby preparing the first adhesive layer. Specifically, first, component (A), component (B), component (C), and other components added as needed are added to an organic solvent, and dissolved or dispersed by stirring, mixing, kneading, etc. to prepare a varnish composition. Then, the varnish composition is applied to a substrate subjected to a demolding treatment using a doctor blade coater, a roller coater, an applicator, a notched wheel coater, a die coater, etc., and then the organic solvent is volatilized by heating, thereby forming a layer containing the first curable composition on the substrate. Next, the first curable composition is cured by irradiating the layer containing the first curable composition with light or heating, thereby forming a first adhesive layer on the substrate (curing step). Thus, a first adhesive film is obtained.

The organic solvent used in the preparation of the varnish composition is preferably one that has the property of dissolving or dispersing each component uniformly, for example, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, etc. These organic solvents can be used alone or in combination of two or more. The stirring, mixing and kneading when preparing the varnish composition can be carried out, for example, using a stirrer, a grinder, a three-roller, a ball mill, a bead mill or a homogenizer.

The supporting film is not particularly limited as long as it has heat resistance that can withstand the heating conditions for volatilizing the organic solvent when the first curable composition is cured by light, and is not particularly limited as long as it has heat resistance that can withstand the heating conditions for volatilizing the organic solvent and the heating conditions for curing the first curable composition when the first curable composition is cured by heat. As the supporting film, for example, a substrate (such as a film) 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. From the perspective of high versatility, polyethylene terephthalate can be preferably used.

The heating conditions for volatilizing the organic solvent from the varnish composition applied to the support film are preferably set to conditions that allow the organic solvent to fully volatilize. The heating conditions may be, for example, 40°C or higher and 120°C or lower, and 0.1 minute or higher and 10 minutes or lower.

In the light irradiation in the curing step, it is preferred to use irradiation light (e.g., ultraviolet light) having a wavelength in the range of 150 nm to 750 nm. The 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, etc. The light irradiation amount can be adjusted so that the ratio of the melt viscosity (X/Y) becomes 10 or more. The light irradiation amount can be, for example, 100 mJ/ ^cm2 or more, 200 mJ/ ^cm2 or more, or 300 mJ/ ^cm2 or more, as the cumulative light amount of light with a wavelength of 365 nm. The irradiation amount of light, for example, can be 10000 mJ/ ^cm2 or less, 5000 mJ/ ^cm2 or less, or 3000 mJ/ ^cm2 or less, as measured by the cumulative amount of light at a wavelength of 365 nm. The greater the irradiation amount of light (the cumulative amount of light), the greater the melt viscosity X tends to be, and the greater the melt viscosity ratio (X/Y) tends to be.

The heating conditions in the curing step can be adjusted so that the ratio of melt viscosity (X/Y) becomes 10 or more. The heating conditions can be, for example, 30°C or more and 300°C or less, 0.1 minute or more and 5000 minutes or less, or 50°C or more and 150°C or less, 0.1 minute or more and 3000 minutes or less. The higher the heating temperature, the greater the melt viscosity X tends to be, and the greater the ratio of melt viscosity (X/Y) tends to be. In addition, the longer the heating time, the greater the melt viscosity X tends to be, and the greater the ratio of melt viscosity (X/Y) tends to be.

In the second preparation step, except that components (a) and (b) and other components added as needed are used and the curing step (no light irradiation and heating) is not performed, a second adhesive layer is formed on the substrate to obtain a second adhesive film in the same manner as in the first preparation step, thereby preparing the second adhesive layer. The substrate can be the same as the support film described above.

In the lamination step, the second adhesive layer may be laminated on the first adhesive layer by laminating the first adhesive film and the second adhesive film, or the second adhesive layer may be laminated on the first adhesive layer by applying a varnish composition obtained by using components (a) and (b) and other components added as needed on the first adhesive layer and causing the organic solvent to volatilize.

As methods for bonding the first adhesive film to the second adhesive film, for example, there are methods such as heat pressing, roller lamination, and vacuum lamination. Lamination can be performed under heating conditions of 0°C to 80°C, for example.

In addition, in the present embodiment, when a circuit connection adhesive film is used in which more than 90% of the conductive particles P are separated from other conductive particles in the first adhesive layer, this dispersed state can be formed by the magnetic field application step described later. In this case, as the conductive particles P, from the perspective of dispersion by the magnetic field application step, it is preferable to use particles containing nickel. In general, iron, cobalt, and nickel are known to be ferromagnetic substances and are magnetized by an external magnetic field. Among them, nickel is meaningful in terms of having both conductivity and dispersion achieved by magnetic field application. In addition, in order to obtain the storage stability of the conductive particles P, the surface layer of the conductive particles P may not be nickel, but may be a precious metal such as platinum such as gold or silver. In addition, the surface of nickel may be coated with a precious metal such as Au. Furthermore, non-conductive glass, ceramics, plastics, etc. coated with the above-mentioned conductive materials such as metals may also be used. In this case, a nickel layer may be provided to form a multi-layer structure.

In addition, the magnetism of nickel is affected by the concentration of phosphorus contained in the nickel plating, so it is better to adjust the magnetism required to disperse the conductive particles P using the magnetic field in a timely manner. The magnetism of the conductive particles P can be measured by, for example, the saturated magnetization using a sample vibration magnetometer (VSM: Vibrating Sample Magnetometer). In order to disperse the conductive particles P using an external magnetic field, it is better to have a saturated magnetization in the range of 5.0emu/g to 50emu/g in the VSM measurement. If it is above 5.0emu/g, it is easy to fully disperse the conductive particles P. On the other hand, if it is below 50emu/g, the magnetization of the conductive particles P will not be too large, and the conductive particles P can be suppressed from combining in the thickness direction of the first adhesive layer 13, and there is a tendency for the dispersibility of the conductive particles P to become higher.

The average particle size of the conductive particles P is preferably greater than 1.0 μm and less than 10.0 μm. When the average particle size of the conductive particles P is greater than 1.0 μm, the coating accuracy of the support film is high, and the conductive particles P are easily dispersed well in the first adhesive layer. When the average particle size of the conductive particles P is less than 10.0 μm, there is a tendency to obtain good insulation between adjacent circuit electrodes of the connection structure. In order to obtain good dispersibility of the conductive particles P, the average particle size of the conductive particles P is more preferably greater than 2.0 μm, and further preferably greater than 2.5 μm. On the other hand, from the perspective of ensuring the insulation between adjacent circuit electrodes of the connection structure, the average particle size of the conductive particles P is preferably 8.5 μm or less, further preferably 7 μm or less, and further preferably 6.0 μm or less.

The amount of conductive particles P is preferably set to 1 to 100 parts by volume relative to 100 parts by volume of components other than the conductive particles P of the first adhesive layer. From the viewpoint of preventing short circuits of adjacent circuit electrodes caused by the excessive presence of conductive particles P, the amount of conductive particles P is more preferably set to 10 to 50 parts by volume. Furthermore, within the range of an average particle size of the conductive particles being greater than 1.0 μm and less than 10.0 μm, the particle density of the conductive particles is preferably greater than 1,000 particles/mm ² and less than 50,000 particles/mm ^2. In this case, both the dispersibility of the conductive particles P and the insulation between adjacent circuit electrodes can be better achieved.

(Lamination step)

FIG2 is a schematic cross-sectional view showing the lamination step in the manufacturing method of the connection structure of the present embodiment. In this step, as shown in the figure, the circuit connection adhesive film 11 is laminated on the first circuit component 2 in such a manner that the second adhesive layer 14 side of the circuit connection adhesive film 11 faces the surface of the first circuit component 2 on which the first circuit electrode 6 is provided. Furthermore, in the case where the circuit connection adhesive film 11 has a peeling film provided on the second adhesive layer 14, lamination can be performed in such a manner that the second adhesive layer 14 is in close contact with the first circuit component 2 after the peeling film is peeled off or while the peeling film is peeled off.

The first circuit component 2 has a circuit electrode 6 on the mounting surface 5a side of the main body 5. As the first circuit component 2, for example, a chip on plastic (COP), a flip chip package (FCP), a component with a flexible substrate such as polyimide can be listed. The circuit electrode 6 can be, for example, copper plated with a metal such as tin. Furthermore, an insulating layer can also be formed on the mounting surface 5a in the portion where the circuit electrode 6 is not formed.

As a lamination mechanism, a known lamination press can be used. The lamination conditions can be appropriately set.

FIG3 is a schematic cross-sectional view showing a laminate obtained after a lamination step.

(Heating and pressurizing steps)

FIG4 is a schematic cross-sectional view showing the heating and pressurizing step in the manufacturing method of the connection structure of the present embodiment. In this step, as shown in the figure, the second circuit component 3 is arranged on the first circuit component 2 laminated with the circuit connection adhesive film (the second adhesive layer 14 and the first adhesive layer 13) in a manner that the first circuit electrode 6 and the second circuit electrode 8 face each other, and the circuit connection adhesive film (the second adhesive layer 14 and the first adhesive layer 13) is heated while the first circuit component 2 and the second circuit component 3 are pressurized in the direction in which the first circuit electrode 6 and the second circuit electrode 8 face each other.

The second circuit component 3 is, for example, a glass substrate or plastic substrate, a ceramic wiring board, etc., which is formed with a circuit made of indium tin oxide (ITO), indium zinc oxide (IZO) or metal, etc., used in a liquid crystal display. As shown in FIG. 4 , the second circuit component 3 has a second circuit electrode 8 corresponding to the first circuit electrode 6 on the mounting surface 7a side of the main body 7.

The circuit electrode 8 is rectangular in plan view, for example, and has a thickness of about 100 nm to 1000 nm. The surface of the circuit electrode 8 includes, for example, one or more materials selected from gold, silver, copper, tin, ruthenium, rhodium, palladium, niolide, iridium, platinum, indium tin oxide (ITO) and indium zinc oxide (IZO). Furthermore, an insulating layer may be formed on the mounting surface 7a in the portion where the circuit electrode 8 is not formed.

As a heating mechanism, a known heat pressing device can be used. The heating temperature of the circuit connection adhesive film (the second adhesive layer 14 and the first adhesive layer 13) is preferably a temperature above which polymerization active species are generated in the hardener and polymerization of the polymerization monomer begins. The heating temperature is, for example, 80°C to 200°C, preferably 100°C to 180°C. In addition, the heating time is, for example, 0.1 seconds to 30 seconds, preferably 1 second to 20 seconds. If the heating temperature is above 80°C, it is easy to obtain a sufficient curing speed, and if it is below 200°C, it is difficult for undesirable side reactions to occur. In addition, if the heating time is 0.1 seconds or longer, the curing reaction can be easily carried out sufficiently, and if it is less than 30 seconds, the productivity of the cured product can be easily maintained, and undesirable side reactions are less likely to occur.

As a pressurizing mechanism, a known heat pressing device can be used. The pressurizing pressure and time can be appropriately set.

Fig. 5 is a schematic cross-sectional view of a circuit connection structure obtained after the heating and pressurizing step. In the heating and pressurizing step, the adhesive component of the circuit connection adhesive film (the second adhesive layer 14 and the first adhesive layer 13) flows, and the second adhesive layer and the first adhesive layer are hardened in a state where the distance between the first circuit electrode 6 and the second circuit electrode 8 is reduced and the conductive particles P are entangled. By curing the second adhesive layer and the first adhesive layer, a cured product 4 of the circuit connection adhesive film (the second adhesive layer 14 and the first adhesive layer 13) is formed in a state where the first circuit electrode 6 and the second circuit electrode 8 are electrically connected, and adjacent circuit electrodes 6 and circuit electrodes 6 are electrically insulated from each other and adjacent circuit electrodes 8 and circuit electrodes 8 are electrically insulated, thereby obtaining the circuit connection structure 1 shown in Figure 5. In the obtained circuit connection structure 1, the hardened material 4 of the circuit connection adhesive film (the second adhesive layer 14 and the first adhesive layer 13) can fully prevent the time-dependent change of the distance between the first circuit electrode 6 and the second circuit electrode 8, and can also ensure the long-term reliability of the electrical characteristics.

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

The conductive particles P are placed between the first circuit electrode 6 and the second circuit electrode 8 in a state of being slightly flattened and deformed by crimping. Thus, electrical connection between the first circuit electrode 6 and the second circuit electrode 8 is achieved. In addition, the conductive particles P are separated between the adjacent first circuit electrodes 6 and the first circuit electrodes 6 and between the adjacent second circuit electrodes 8 and the second circuit electrodes 8, thereby achieving electrical insulation between the adjacent first circuit electrodes 6 and the first circuit electrodes 6 and between the adjacent second circuit electrodes 8 and the second circuit electrodes 8.

[Method for manufacturing adhesive film for circuit connection]

Fig. 6 is a schematic diagram showing the manufacturing steps of the adhesive film for circuit connection shown in Fig. 1. In the example shown in the figure, the long support film 12 is conveyed at a predetermined speed by the take-out roller 21 and the winding roller 22. On the conveying path of the support film 12, there is arranged a coating machine 23 for coating the adhesive paste W which becomes the forming material of the first adhesive layer 13, and the adhesive paste W in which the conductive particles P are dispersed is coated on the support film 12 by the coating machine 23 (coating step). The thickness of the adhesive paste W applied to the support film 12 by the coating machine 23 varies according to the proportion of the solvent contained in the resin composition, but is preferably less than 1.6 times the average particle size of the conductive particles P.

The viscosity of the adhesive paste W can vary depending on the application and coating method, and is generally preferably set to 10mPa.s~10000mPa.s. From the perspective of suppressing the separation of the formulation in the adhesive paste W and improving compatibility, it is more preferably set to 50mPa.s~5000mPa.s. In addition, in order to improve the appearance of the adhesive film 11 for circuit connection, it is preferably set to 100mPa.s~3000mPa.s. If it is less than 10000mPa.s, it is difficult to suppress the dispersion of the conductive particles P in the subsequent magnetic field application step. If it is more than 10mPa.s, it is not easy to produce separation of the formulation of the adhesive paste W.

The coating method of the adhesive paste W is not limited to the above method, and a known method can be used. For example, spin coating, roller coating, rod coating, dip coating, micro-gravure coating, curtain coating, die coating, spray coating, scraper coating, kneader coating, flow coating, screen printing, casting, etc. Rod coating, die coating, micro-gravure coating, etc. are suitable for the preparation of the adhesive film 11 for circuit connection. From the perspective of the accuracy of the film thickness, the micro-gravure coating method is particularly preferred.

On the rear side of the coating machine 23, a pair of magnets 24 and 25 are arranged facing each other in the upper and lower directions so as to sandwich the supporting film 12. In this embodiment, as shown in FIG. 7, the magnet 24 arranged on the upper side is an N pole, and the magnet 25 arranged on the lower side is an S pole, and a magnetic field is formed in a substantially vertical direction from the magnet 24 toward the magnet 25. Therefore, if the supporting film 12 is transported between the magnets 24 and 25, the conductive particles P in the bonding paste W are magnetized, and the conductive particles P are separated from each other in the in-plane direction of the bonding paste W by repulsion (magnetic field application step).

In addition, in order to maintain the separated state of the conductive particles P in the magnetic field application step, the adhesive paste W is dried by hot air or the like while the supporting film 12 passes between the magnets 24 and 25 (drying step). As a result, the viscosity of the adhesive paste W increases, and as shown in FIG8 , a first adhesive layer 13 is formed on the supporting film 12 in which more than 70%, preferably more than 90%, of the conductive particles P are separated from other adjacent conductive particles P. In addition, the thickness of the adhesive paste W gradually decreases during the drying step. By making the thickness of the adhesive paste W less than 1.6 times the average particle size of the conductive particles P as described above, it is easy to make the thickness of the first adhesive layer 13 more than 0.6 times and less than 1.0 times the average particle size of the conductive particles P. In addition, by using an adhesive paste (varnish) diluted with an organic solvent (such as methyl ethyl ketone, etc.), the thickness of the adhesive layer can also be made thin to about 0.1 times the average particle size of the conductive particles P. The amount of the organic solvent to be diluted is not particularly limited, and it is preferably added in an amount of 50 to 500 parts by mass relative to 100 parts by mass of the adhesive component.

Furthermore, the drying temperature of the adhesive paste W is preferably, for example, 20°C to 80°C. In addition, the conveying speed of the support film 12 is preferably, for example, 30 mm/s to 160 mm/s. For example, when using conductive particles P having an average particle size of 3 μm, the thickness of the adhesive paste W is preferably 5 μm to 10 μm. When the conveying speed of the support film 12 is 30 mm/s or more, the adhesive paste W is dried in a state where the conductive particles P are sufficiently separated, so there is a tendency for the dispersion to become sufficient. When the conveying speed of the support film 12 is 160 mm/s or less, there is a tendency for the application of the magnetic field to be terminated after drying, which can suppress the re-agglomeration of the conductive particles P. In addition, when the thickness of the adhesive paste W is 5 μm or more, the gap between the coating machine 23 can be suppressed, and the number of conductive particles P in the first adhesive layer 13 can be suppressed. When the thickness of the adhesive paste W is 10 μm or less, the gap between the coating machine 23 can be suppressed, and the number of conductive particles P in the first adhesive layer 13 can be suppressed.

After forming the first adhesive layer 13, as shown in FIG9, the second adhesive layer 14 formed on the release film 15 is separately pressed on the first adhesive layer 13 (lamination step). In this way, the circuit connection adhesive film 11 shown in FIG2 is obtained. Furthermore, in lamination of the second adhesive layer 14, for example, a hot roll lamination press can be used. In addition, it is not limited to lamination, and the adhesive paste that becomes the material of the second adhesive layer 14 can also be applied on the first adhesive layer 13 and dried.

As described above, in the circuit connection adhesive film 11, more than 70%, preferably more than 90%, of the conductive particles P in the first adhesive layer 13 can be separated from other adjacent conductive particles P. In this case, when the first circuit component 2 and the second circuit component 3 are connected, the aggregation of the adjacent conductive particles P and the conductive particles P can be suppressed, and the insulation between the adjacent first circuit electrodes 6 and the adjacent first circuit electrodes 6 and the adjacent second circuit electrodes 8 and the adjacent second circuit electrodes 8 can be well ensured. In addition, in the circuit connection adhesive film 11, the thickness of the first adhesive layer 13 can be 0.1 times or more and 1.0 times or more, 0.1 times or more and 0.7 times or more, or 0.6 times or more and less than 1.0 times the average particle size of the conductive particles P. In this case, the flow of the conductive particles P during crimping can be suppressed, and the capture efficiency of the conductive particles P between the first circuit electrode 6 and the second circuit electrode 8 can be improved. Therefore, the connection reliability between the first circuit component 2 and the second circuit component 3 can be ensured.

<Next is the membrane containment group>

FIG10 is a three-dimensional diagram of an adhesive film storage group showing an embodiment. As shown in FIG10 , the adhesive film storage group 120 includes: an adhesive film 11 for circuit connection, a reel 121 around which the adhesive film 11 is wound, and a storage member 122 for storing the adhesive film 11 and the reel 121.

As shown in FIG. 10 , the adhesive film 11 is, for example, in a strip shape. The strip-shaped adhesive film 11 is, for example, produced by cutting a sheet of a whole sheet into strips according to the width of the intended use. The adhesive film 11 may also have a supporting film 12 on the first adhesive layer side. As the supporting film 12, a substrate such as the PET film described above may be used.

The reel 121 includes a first side plate 124 having a core 123 for winding the agent film 11, and a second side plate 125 arranged to face the first side plate 124 with the core 123 interposed therebetween.

The first side plate 124 is, for example, a circular plate made of plastic, and an opening with a circular cross-section is provided in the central portion of the first side plate 124.

The core 123 of the first side plate 124 is a portion around which the adhesive film 11 is wound. The core 123 is made of, for example, plastic and is formed into a ring shape having a thickness equal to the width of the adhesive film 11. The core 123 is fixed to the inner surface of the first side plate 124 in a manner surrounding the opening of the first side plate 124. In addition, a shaft hole 126 is provided in the central portion of the reel 121 as a portion for inserting a rotating shaft of a winding device or a extraction device (not shown). When the rotating shaft is driven with the rotating shaft of the winding device or the extraction device inserted into the shaft hole 126, the reel 121 rotates without idling. A desiccant container for containing desiccant may also be embedded in the shaft hole 126.

The second side plate 125 is similar to the first side plate 124, for example, a circular plate made of plastic, and a circular opening having the same diameter as the opening of the first side plate 124 is provided in the central portion of the second side plate 125.

The storage member 122 is, for example, in the shape of a bag, and stores the adhesive film 11 and the reel 121. The storage member 122 has an insertion port 127 for storing (inserting) the adhesive film 11 and the reel 121 into the storage member 122.

The storage member 122 has a visual portion 128 that allows the interior of the storage member 122 to be visually recognized from the outside. The storage member 122 shown in FIG. 10 is configured in such a way that the entire storage member 122 serves as the visual portion 128.

The visual portion 128 is transmissive to visible light. For example, when the transmittance of the visual portion 128 to light is measured in the range of wavelengths of 450nm to 750nm, there is at least one region between the wavelengths of 450nm to 750nm where the average transmittance of light is greater than 30% and the wavelength width is 50nm. The transmittance of the visual portion 128 to light can be obtained by making a sample of a specified size by cutting the visual portion 128 and measuring the transmittance of the sample to light using an ultraviolet-visible spectrophotometer. The storage component 122 has such a visual portion 128, so that various information inside the storage component 122, such as the product name, batch number, expiration date, etc. attached to the reel 121, can also be confirmed from the outside of the storage component 122. This can be expected to prevent the mixing of incorrect products and improve the efficiency of sorting operations.

The transmittance of the visual part 128 to light with a wavelength of 365nm is less than 10%. The transmittance of the visual part 128 to light with a wavelength of 365nm is less than 10%, so the curing of the second curable composition caused by light incident from the outside of the housing member 122 to the inside and the residual photopolymerization initiator in the first adhesive layer when a photopolymerization initiator is used as the (B) component can be suppressed. From the perspective of further suppressing the generation of active species (such as free radicals) from the photopolymerization initiator, the transmittance of the visual part 128 to light with a wavelength of 365nm is preferably less than 10%, more preferably less than 5%, further preferably less than 1%, and particularly preferably less than 0.1%.

From the same point of view, the maximum value of the transmittance of the visual part 128 to light in the wavelength region where free radicals, cations or anions can be generated 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 value of the transmittance of the visual part 128 to light with a wavelength of 254nm ~405nm is preferably 10% or less, more preferably 5% or less, further preferably 1% or less, and particularly preferably 0.1% or less.

The visual part 128 (housing member 122) is formed of a sheet with a thickness of 10 μm to 5000 μm, for example. The sheet includes a material whose transmittance of the visual part 128 to light of a wavelength of 365 nm is less than 10%. Such a material may contain one component or multiple components. Examples of such materials include low-density polyethylene, linear low-density polyethylene, polycarbonate, polyester, acrylic resin, polyamide, glass, etc. These materials may also include ultraviolet absorbers. The visual part 128 may also have a laminated structure formed by laminating multiple layers with different light transmittance. In this case, each layer constituting the visual part 128 may include the materials described above.

In order to prevent air from intruding from the outside during storage, the insertion port 127 can be sealed by, for example, using a sealing machine. In this case, it is preferable to remove the air in the storage member 122 before sealing the insertion port 127. It can be expected that the humidity in the storage member 122 will decrease from the initial stage of storage, and air from the outside will be prevented from entering. In addition, by the inner surface of the storage member 122 being in close contact with the reel 121, the inner surface of the storage member 122 and the surface of the reel 121 can be prevented from rubbing against foreign matter due to vibration during transportation, and the outer surface of the side plate 124 and the side plate 125 of the reel 121 can be prevented from being scratched.

In the above-mentioned embodiment, the storage member is configured in such a way that the entire storage member becomes the visual recognition portion. In another embodiment, the storage member may also have a visual recognition portion in a part of the storage member. For example, the storage member may have a rectangular visual recognition portion in the approximate center of the side surface of the storage member. In this case, the portion of the storage member other than the visual recognition portion may be black, for example, so as not to transmit ultraviolet light and visible light.

In addition, in the above-mentioned embodiment, the shape of the storage member is bag-shaped, and the storage member may also be box-shaped, for example. The storage member is preferably provided with a cut for unsealing. In this case, the unsealing operation during use becomes easier.

[Implementation example]

The present invention is described in detail below based on embodiments, but the present invention is not limited to these embodiments.

<Preparation method of polyester urethane resin>

In a stainless steel autoclave with a heater and equipped with a stirrer, thermometer, condenser, vacuum generator and nitrogen inlet pipe, 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were added, and further, 0.02 parts by mass of tetrabutoxytitanium ester as a catalyst was added. Then, the temperature was raised to 220°C under a nitrogen flow and stirred directly for 8 hours. Then, the pressure was reduced to atmospheric pressure (760 mmHg), cooled to room temperature, and the white precipitate was taken out, washed with water, and vacuum dried to obtain polyester polyol.

The polyester polyol obtained by the reaction of the dicarboxylic acid and the diol described above was fully dried, dissolved in methyl ethyl ketone (MEK), and placed in a four-necked flask equipped with a stirrer, a dropping funnel, a reflux cooler, and a nitrogen inlet tube. In addition, 0.05 parts by mass of dibutyltin laurate was added as a catalyst relative to 100 parts by mass of the polyester polyol, and 50 parts by mass of 4,4'-diphenylmethane diisocyanate dissolved in MEK was added using a dropping funnel relative to 100 parts by mass of the polyester polyol, and stirred at 80°C for 4 hours to obtain the target polyester urethane resin.

<Synthesis of polyurethane acrylate (UA1)>

In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooling tube with a calcium chloride drying tube, and a nitrogen inlet tube, 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. Then, after nitrogen was fully introduced into the reaction vessel, the reaction vessel was heated to 70°C to 75°C to carry out the 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, and then 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (manufactured by Sigma-Aldrich) was added, and the mixture was reacted at 70°C for 6 hours in an air environment. Thus, polyurethane acrylate (UA1) was obtained. The weight average molecular weight of polyurethane acrylate (UA1) was 15,000. In addition, the weight average molecular weight was measured by gel permeation chromatography (GPC) under the following conditions, using a calibration curve obtained from standard polystyrene.

(Measurement conditions)

Device: GPC-8020 manufactured by Tosoh Corporation

Detector: RI-8020 manufactured by Tosoh Co., Ltd.

Column: Gelpack GLA160S+GLA150S manufactured by Hitachi Chemical Co., Ltd.

Sample concentration: 120mg/3mL

Solvent: Tetrahydrofuran

Injection volume: 60μL

Pressure: 2.94×10 ⁶ Pa (30kgf/cm ² )

Flow rate: 1.00mL/min

<Production of conductive particles>

A layer containing nickel is formed on the surface of polystyrene particles in a manner with a layer thickness of 0.2 μm. In this manner, 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 are obtained.

<Preparation of varnish (varnish composition) containing a layer of conductive particles>

The following components were mixed in the amounts (parts by mass) shown in Table 1 to prepare a varnish of the photocurable composition 1. The content (volume %) of the conductive particles and the content (volume %) of the filler described in Table 1 are based on the total volume of the photocurable composition.

(Polymerizable compound)

A1: Dicyclopentadiene diacrylate (trade name: DCP-A, manufactured by Toa Gosei Co., Ltd.)

A2: Polyurethane acrylate (UA1) synthesized as described above

A3: 2-Methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by Kyoei 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)

(Thermal polymerization initiator)

C1: Benzoyl peroxide (trade name: NYPER BMT-K40, manufactured by NOF Corporation)

(Conductive particles)

D1: Conductive particles made as described above

(Thermoplastic resin)

E1: Polyester urethane resin synthesized above

(Coupling agent)

F1: 3-Methacryloyloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.)

(Filling material)

G1: Silica microparticles (trade name: R104, manufactured by AEROSIL Co., Ltd., Japan, average particle size (primary particle size): 12nm)

(Solvent)

H1: Methyl ethyl ketone

<Preparation of varnish of thermosetting composition (varnish composition)>

As polymerizable compounds a1 to a3, thermoplastic resin e1, coupling agent f1, filler g1 and solvent h1, the same polymerizable compounds A1 to A3, thermoplastic resin E1, coupling agent F1, filler G1 and solvent H1 in the photocurable composition are used, and these components and the thermal polymerization initiator shown below are mixed in the blending amounts (parts by mass) shown in Table 2 to prepare a varnish of thermosetting composition 1. In addition, the content (volume %) of the filler described in Table 2 is the content based on the total volume of the thermosetting composition.

(Thermal polymerization initiator)

c1: Benzoyl peroxide (trade name: NYPER BMT-K40, manufactured by NOF Corporation)

(Implementation Example 1)

[Preparation of the first adhesive film]

The varnish of the photocurable composition 1 is applied to a PET film with a thickness of 50 μm using a coating device. Then, hot air drying is performed at 70°C for 3 minutes, and a magnetic field is applied at the same time, thereby forming a layer containing the photocurable composition 1 with a thickness (thickness after drying) of 4 μm on the PET film. The thickness here is measured using a contact thickness gauge. Furthermore, if a contact thickness gauge is used, the size of the conductive particles is reflected, and the thickness of the area where the conductive particles exist is measured. Therefore, after laminating the second adhesive layer and making a circuit connection adhesive film consisting of two layers, the thickness of the first adhesive layer located at the separation portion of the adjacent conductive particles is measured by the method described below.

Next, the layer containing the photocurable composition 1 was irradiated with light using a metal halide lamp at a cumulative light intensity of 1500 mJ/ ^cm2 to polymerize the polymerizable compound. The photocurable composition 1 was thereby cured to form a first adhesive layer. By the above operation, a first adhesive film having a first adhesive layer with a thickness of 4 μm (the thickness of the region where the conductive particles exist) was obtained on the PET film. The density of the conductive particles at this time was about 7000 pcs/ ^mm2 .

[Evaluation of the monodispersity of conductive particles]

For the first adhesive film, the monodispersity of the conductive particles (the ratio of the conductive particles existing in a state separated from other adjacent conductive particles (monodispersed state)) was evaluated. The monodispersity was 70% or more.

The monodispersity was calculated using the formula: monodispersity (%) = (number of monodisperse conductive particles in 2500 μm ² / number of conductive particles in 2500 μm ² ) × 100. The conductive particles were measured using a metal microscope at a magnification of 200.

[Preparation of the second adhesive film]

Use a coating device to apply the varnish of the thermosetting composition 1 on a PET film with a thickness of 50 μm. Then, perform hot air drying at 70°C for 3 minutes to form a second adhesive layer (including the layer of the thermosetting composition 1) with a thickness of 8 μm on the PET film. Through the above operation, a second adhesive film having a second adhesive layer on the PET film is obtained.

[Production of adhesive film for circuit connection]

The first adhesive film and the second adhesive film are heated at 40°C together with the PET film as the base material, and laminated using a roller press. At this time, the PET film on the side of the second adhesive film is peeled off. In this way, an adhesive film for circuit connection is produced, which is composed of a laminated structure of PET film, a first adhesive layer, and a second adhesive layer in sequence.

The thickness of the first adhesive layer of the produced circuit connection adhesive film is measured by the above method. Specifically, the measurement is performed by the following method. The circuit connection adhesive film was sandwiched between two pieces of glass (thickness: about 1 mm). After casting 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 cross-section was polished using a grinder, and the thickness of the first adhesive layer located at the separation portion of the 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 was 2 μm.

[Manufacturing of circuit connection structures]

The circuit connection adhesive film made by the dielectric was used to heat and press the COF (manufactured by FLEXSEED) with a pitch of 25μm and the glass substrate with a thin film electrode (height: 1200Å) containing amorphous indium tin oxide (ITO) on the glass substrate (manufactured by Geomatec) at 170°C and 6MPa for 4 seconds using a heat press device (heating method: contact heat type, manufactured by Taiyang Machinery Manufacturing Co., Ltd.) to connect across a width of 1mm to produce a circuit connection structure (connection structure). Furthermore, when connecting, first attach the circuit connection adhesive film to the COF substrate from the second adhesive layer side, and after peeling off the spacer, place it facing the glass substrate and heat and pressurize it.

[Evaluation of circuit connection structures]

For the obtained circuit connection structure, the connection resistance between the electrodes facing each other just after connection is measured by a multimeter. The connection resistance is calculated as the average value of the resistance between the electrodes facing each other at 16 locations.

Next, the number of captured particles in an area of 10 μm×200 μm (=2000 μm ² ) on each electrode was measured, and the average value of 20 rows was calculated.

In addition, the dispersion of particles after installation was observed using a microscope. The evaluation was 1 for those that maintained the state before installation, 3 for those that did not maintain the state at all, and 2 for those in between.

1 and 2 are practically acceptable levels.

(Reference Example 1)

After laminating the first adhesive layer and the second adhesive layer, the PET film on the side of the first adhesive layer was peeled off, thereby preparing a circuit connection adhesive film composed of the first adhesive layer, the second adhesive layer and the PET film laminated in sequence, and the evaluation was performed in the same manner as in Example 1. Furthermore, when connecting, the circuit connection adhesive film was first attached to the COF substrate from the side of the first adhesive layer, and after peeling off the spacer, it was heated and pressurized so as to face the glass substrate. The results are shown in Table 3.

(Example 2 and Example 3)

The thickness of the first adhesive layer was changed to 1.5 μm and 3.0 μm, and the adhesive film for circuit connection and the circuit connection structure were prepared in the same manner as in Example 1. The prepared circuit connection structure was evaluated in the same manner as in Example 1. The results are shown in Table 3. Furthermore, the monodispersity of the conductive particles in the first adhesive layer was 70% or more.

It was found that compared with Reference Example 1, when the circuit connection adhesive film obtained in Example 1 was first attached to the COF substrate for installation, the number of conductive particles captured increased and the mobility of the particles was also suppressed.

11: Adhesive film for circuit connection

12: Support membrane

13: First adhesive layer

14: Second adhesive layer

P: Conductive particles

S: The boundary between the first adhesive layer and the second adhesive layer

Claims (4)

A circuit connection adhesive film comprises: a peelable support film; a first adhesive layer, disposed on the support film and containing conductive particles; and a second adhesive layer, laminated on the first adhesive layer, wherein the thickness of the first adhesive layer is 0.1 to 1.0 times the average particle size of the conductive particles, wherein the first adhesive layer comprises a cured product of a first curable composition, wherein the first curable composition comprises a radically polymerizable compound having a radically polymerizable group, and wherein the second adhesive layer comprises a second curable composition, wherein the second curable composition comprises a radically polymerizable compound having a radically polymerizable group, wherein the radically polymerizable compound comprises a radically polymerizable compound having a phosphate structure represented by the following general formula (1):

In the formula, n represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group. A method for manufacturing a circuit connection structure, comprising: placing the first adhesive layer and the second adhesive layer of the circuit connection adhesive film as described in claim 1 between a first circuit component having a first electrode and a second circuit component having a second electrode, and hot pressing the first circuit component and the second circuit component to electrically connect the first electrode and the second electrode to each other. The method for manufacturing a circuit connection structure as described in claim 2, wherein the first circuit component has a flexible substrate, and the method for manufacturing the circuit connection structure includes the step of attaching the circuit connection adhesive film to the first circuit component in such a manner that the second adhesive layer contacts the first circuit component. An adhesive film storage set, comprising: an adhesive film for circuit connection as described in claim 1, and a storage component for storing the adhesive film, wherein the storage component has a viewing portion that enables the interior of the storage component to be viewed from the outside, and the transmittance of the viewing portion to light with a wavelength of 365nm is less than 10%.

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