CN113574130A

CN113574130A - Adhesive film for circuit connection, method for manufacturing circuit connection structure, and adhesive film housing set

Info

Publication number: CN113574130A
Application number: CN202080019596.3A
Authority: CN
Inventors: 伊藤彰浩; 大当友美子; 工藤直
Original assignee: Showa Denko KK
Current assignee: Resonac Holdings Corp
Priority date: 2019-03-13
Filing date: 2020-03-11
Publication date: 2021-10-29
Also published as: KR20210141955A; TW202039764A; WO2020184636A1; JPWO2020184636A1

Abstract

An adhesive film (11) for circuit connection, comprising: a releasable support film (12), a first adhesive layer (13) containing conductive particles (P) provided on the support film, and a second adhesive layer (14) laminated on the first adhesive layer (13), the thickness of the first adhesive layer being 0.1 to 1.0 times the average particle diameter of the conductive particles.

Description

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

Technical Field

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

Background

Conventionally, various adhesive materials have been used for circuit connection. For example, as an adhesive material used for connection between a liquid crystal display and a Tape Carrier Package (TCP), connection between a Flexible Printed Circuit (FPC) and a TCP, or connection between an FPC and a Printed Circuit board, an adhesive film for Circuit connection having anisotropic conductivity in which conductive particles are dispersed in a binder is used. Specifically, circuit members are bonded to each other with circuit connecting portions formed of an adhesive film for circuit connection, and electrodes on the circuit members are electrically connected to each other via conductive particles in the circuit connecting portions, thereby obtaining a circuit connecting structure.

The circuit connecting adhesive film is formed as a film as an adhesive layer on a substrate such as a polyethylene terephthalate (PET) film, for example, containing a binder component such as a thermosetting resin and, if necessary, conductive particles. Further, there is a case where a film-shaped web is cut into a tape shape having a width suitable for the application, and an adhesive film is used in a state where the tape is wound around a winding core to form a reel of a wound body (for example, refer to patent document 1).

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2003-34468

Disclosure of Invention

Technical problem to be solved by the invention

However, in the case of connecting a driver IC and the like to an LCD module using an adhesive film, conventionally, the adhesive film is first transferred to a glass panel, but in recent years, a manufacturing method of first attaching the adhesive film to a flexible substrate such as a COF or an FPC is adopted from the viewpoint of requiring an operation of reducing the amount of the adhesive film used, a panel design of a narrow frame, and the like for the purpose of reducing the manufacturing cost of the LCD.

However, when a conventional adhesive film is used, it is difficult to efficiently capture conductive particles between circuit electrodes, and there is a problem that the conduction reliability is deteriorated or conductive particles not captured between circuits are aggregated, and therefore the short-circuit cost is increased.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an adhesive film for circuit connection, which can obtain a circuit connection structure having excellent connection reliability between opposing circuit components even when first attached to a flexible substrate for circuit connection, a method for manufacturing a circuit connection structure using the adhesive film, and an adhesive film housing set.

Means for solving the technical problem

An adhesive film for circuit connection according to an aspect of the present invention includes: the adhesive film comprises a releasable supporting film, a first adhesive layer containing conductive particles and arranged on the supporting film, and a second adhesive layer laminated on the first adhesive layer, wherein the thickness of the first adhesive layer is 0.1-1.0 times of the average particle size of the conductive particles.

According to the adhesive film for circuit connection, even when the adhesive film is first attached to a flexible substrate to perform circuit connection, a circuit connection structure excellent in connection reliability between opposing circuit components can be obtained. In the first binder layer, it is preferable that 90% or more of the conductive particles be in a state of being separated from other conductive particles.

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

The second adhesive layer may be formed of a second curable composition, and the second curable composition may contain a radical polymerizable compound having a radical polymerizable group.

A method for manufacturing a circuit connection structure according to an aspect of the present invention includes: and a step of interposing the first adhesive layer and the second adhesive layer of the adhesive film for circuit connection between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermally pressing the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

According to this method, even when the circuit connection adhesive film is first attached to the flexible substrate to perform circuit connection, a circuit connection structure excellent in connection reliability between the opposing circuit components can be obtained.

That is, according to the present invention, there is provided a method of manufacturing a circuit connection structure, the method including: and attaching the circuit-connecting adhesive film to the first circuit member so that the second adhesive layer is in contact with the first circuit member.

An adhesive film storage kit according to an aspect of the present invention includes: the adhesive film for circuit connection and the housing member housing the adhesive film, wherein the housing member has a visible portion that allows the inside of the housing member to be visible from the outside, and the visible portion has a transmittance of 10% or less for light having a wavelength of 365 nm.

Effects of the invention

According to the present invention, it is possible to provide an adhesive film for circuit connection, which can obtain a circuit connection structure having excellent connection reliability between circuit components even when first attached to a flexible substrate for circuit connection, a method for manufacturing a circuit connection structure using the adhesive film, and an adhesive film housing set.

Drawings

Fig. 1 is a schematic cross-sectional view showing one embodiment of the adhesive film for circuit connection according to the present invention.

Fig. 2 is a schematic cross-sectional view showing steps of a method for manufacturing a circuit connection structure.

Fig. 3 is a schematic cross-sectional view showing a laminate obtained through the process of fig. 2.

Fig. 4 is a schematic cross-sectional view showing a step subsequent to that of fig. 2.

Fig. 5 is a schematic cross-sectional view showing a circuit connection structure obtained through the process of fig. 4.

Fig. 6 is a schematic view showing a process for producing the adhesive film for circuit connection shown in fig. 1.

Fig. 7 is a schematic diagram showing a state of the magnetic field applying step.

Fig. 8 is a schematic cross-sectional view showing a state of the adhesive film for circuit connection after passing through the magnetic field application step and the drying step.

Fig. 9 is a schematic cross-sectional view showing a laminating step subsequent to fig. 7.

Fig. 10 is a perspective view showing an embodiment of an adhesive film storage kit according to the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the present specification, the upper limit and the lower limit described individually can be arbitrarily combined. In the present specification, the term "(meth) acrylate" refers to at least one of an acrylate and a methacrylate corresponding thereto. The same applies to other similar expressions such as "(meth) acryloyl group".

< adhesive film for circuit connection >

Fig. 1 is a schematic cross-sectional view showing an adhesive film for circuit connection according to an embodiment. As shown in fig. 1, an adhesive film 11 for circuit connection (hereinafter, also simply referred to as "adhesive film 11") includes a releasable support film 12, a first adhesive layer 13 provided 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. Thus, the adhesive film 11 is an anisotropic conductive adhesive film having anisotropic conductivity. The adhesive film 11 is used to interpose a first adhesive layer and a second adhesive layer between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermally press-bond the first circuit member and the second circuit member, thereby electrically connecting the first electrode and the second electrode to each other.

In the case where the first circuit component to be connected has a flexible substrate, the circuit-connecting adhesive film 11 can be attached to the first circuit component so that the second adhesive layer is in contact with the first circuit component.

In the present embodiment, the thickness of the first adhesive layer 13 is 0.1 to 1.0 times, and more preferably 0.1 to 0.7 times the average particle diameter of the conductive particles P. In the first adhesive layer 13, 90% or more of the conductive particles P may be separated from other conductive particles.

In the present 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 a temperature Ty at which the second adhesive layer 14 has the minimum melt viscosity Y may be 10 or more.

From the viewpoint of improving the adhesion to the circuit member, 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 to circuit members, the ratio of melt viscosity (X/Y) may be 10000 or less, 5000 or less, or 1000 or less. From these viewpoints, the ratio of melt viscosity (X/Y) may be 10 to 10000, 20 to 5000, 50 to 5000, and 100 to 1000. The melt viscosity X and the minimum melt viscosity Y can be determined by the following method: first, the lowest melt viscosity Y of the second adhesive layer (and the temperature Ty at which the second adhesive layer exhibits the lowest melt viscosity Y) is determined by the melt viscosity measurement of the second adhesive layer, and then the melt viscosity X of the first adhesive layer at the temperature Ty is determined by the melt viscosity measurement of the first adhesive layer. In addition, the measurement of the melt viscosity can be performed after obtaining the adhesive film.

(supporting film)

The support film 12 is formed of, for example, polyethylene terephthalate (PET), polyethylene, polypropylene, or the like. Any filler may be contained on the support film 12. Further, a mold release treatment, a plasma treatment, or the like may be performed on the surface of the support film 12. After the first adhesive layer and the second adhesive layer are transferred to the circuit member, the support film 12 can be peeled.

(first adhesive layer)

The first adhesive layer is formed, for example, from 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 contains, for example, (a) a polymerizable compound (hereinafter also referred to as "component (a)"), (B) a polymerization initiator (hereinafter also referred to as "component (B)") and (C) conductive particles (hereinafter also referred to as "component (C)"). When the first curable composition is a photocurable composition, the first curable composition contains a photopolymerization initiator as the component (B), and when the first curable composition is a thermosetting composition, the first curable composition contains a thermal polymerization initiator as the component (B). Such a first adhesive layer may be obtained, for example, by: the component (a) is polymerized by irradiating or heating the layer formed from the first curable composition with light, and the first curable composition is cured. That is, the first adhesive layer may be formed of conductive particles and an adhesive component obtained by photocuring the first curable composition. The first adhesive layer may be a cured product obtained by completely curing the first curable composition or a cured product obtained by partially curing the first curable composition. That is, when the first curable composition contains the component (a) and the component (B), the binder component may contain or may not contain the unreacted component (a) and the unreacted component (B). In addition, the first adhesive layer may be formed of a resin composition other than a cured product of the curable composition. For example, the first adhesive layer may be formed of a resin composition containing a resin component of phenoxy resin such as PKHC, polyester urethane resin, polyurethane resin, acrylic rubber, or the like. By using such a resin component, the melt viscosity of the second adhesive layer at a temperature (e.g., 100 ℃) at which the minimum melt viscosity is achieved can be adjusted to about 100000 to 10000000Pa · s, and the ratio (X/Y) of the melt viscosity can be set to 10 or more.

[ (A) ingredient: polymerizable Compound ]

(A) The component (b) is, for example, a compound which is polymerized by a radical, cation or anion generated by irradiation of light (for example, ultraviolet light) or heating by a polymerization initiator (photopolymerization initiator or thermal polymerization initiator). (A) The component (b) may be any of a monomer, an oligomer, or a polymer. As the component (a), one compound may be used alone, or a plurality of compounds may be used in combination.

(A) The component (B) has at least one polymerizable group. The polymerizable group is, for example, a group containing a polymerizable unsaturated double bond (ethylenically unsaturated bond). The polymerizable group is preferably a radical polymerizable group that is produced by a radical reaction, from the viewpoint of easily obtaining a desired melt viscosity, from the viewpoint of being less likely to cause peeling between the circuit member and the circuit connecting portion in a high-temperature and high-humidity environment, and from the viewpoint of further improving the effect of reducing the connection resistance and further improving the connection reliability. That is, the component (A) is preferably a radical polymerizable compound. Examples of the radical polymerizable group include: vinyl, allyl, styryl, alkenyl, alkenylene, (meth) acryloyl, maleimido, and the like. The number of the polymerizable groups of the component (a) may be two or more from the viewpoint of easily obtaining a desired melt viscosity after polymerization and easily suppressing the physical properties of the resin after curing, and the number of the polymerizable groups of the component (a) may be 10 or less from the viewpoint of suppressing curing shrinkage during polymerization. In order to balance the crosslinking density and the curing shrinkage, a polymerizable compound having a number of polymerizable groups within the above range may be used in addition to the polymerizable compound having a number of polymerizable groups within the above range.

Specific examples of the component (A) include: a (meth) acrylate compound, a maleimide compound, a vinyl ether compound, an allyl compound, a styrene derivative, an acrylamide derivative, a nadimide (nadiimide) derivative, natural rubber, isoprene rubber, butyl rubber, nitrile rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxylated nitrile rubber, or the like.

Examples of the (meth) acrylate compound include: epoxy (meth) acrylate, (poly) urethane (meth) acrylate, methyl (meth) acrylate, polyether (meth) acrylate, polyester (meth) acrylate, polybutadiene (meth) acrylate, silicone acrylate, ethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-hexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, isopropyl (meth) acrylate, hydroxypropyl (meth) acrylate, isobutyl (meth) acrylate, isobornyl (meth) acrylate, isodecyl (meth) acrylate, isooctyl (meth) acrylate, urethane (meth) acrylate, polyether (meth) acrylate, polyether acrylate, N-lauryl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2- (meth) acryloyloxyethyl phosphate, N-dimethylaminoethyl (meth) acrylate, N-dimethylaminopropyl (meth) acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, polyethylene glycol di (meth) acrylate, polyalkylene glycol di (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, and mixtures thereof, Dipentaerythritol hexa (meth) acrylate, isocyanuric acid-modified difunctional (meth) acrylate, isocyanuric acid-modified trifunctional (meth) acrylate, tricyclodecyl acrylate, dimethylol-tricyclodecane diacrylate, 2-hydroxy-1, 3-diacryloyloxypropane, 2-bis [4- (acryloyloxymethyl) phenyl ] propane, 2-bis [4- (acryloyloxypolyethoxy) phenyl ] propane, 2-bis (meth) acryloyloxydiethylphosphate, 2- (meth) acryloyloxyethyl acid phosphate and the like.

As the maleimide compound, there can be mentioned: 1-methyl-2, 4-bismaleimide benzene, N '-m-phenylenebismaleimide, N' -p-phenylenebismaleimide, N '-m-tolylbismaleimide, N' -4, 4-biphenylenedimaleimide, N '-4,4- (3,3' -dimethyl-biphenylene) bismaleimide, N '-4,4- (3,3' -dimethyldiphenylmethane) bismaleimide, N '-4,4- (3,3' -diethyldiphenylmethane) bismaleimide, N '-4, 4-diphenylmethane bismaleimide, N' -4, 4-diphenylpropane bismaleimide, N, N '-4, 4-diphenylether bismaleimide, N' -3, 3-diphenylsulfone bismaleimide, 2-bis (4- (4-maleimidophenoxy) phenyl) propane, 2-bis (3-tert-butyl-4-8 (4-maleimidophenoxy) phenyl) propane, 1-bis (4- (4-maleimidophenoxy) phenyl) decane, 4 '-cyclohexylene-bis (1- (4-maleimidophenoxy) -2-cyclohexylbenzene, 2' -bis (4- (4-maleimidophenoxy) phenyl) hexafluoropropane, and the like.

As the vinyl ether compound, there can be mentioned: diethylene glycol divinyl ether, dipropylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, trimethylolpropane trivinyl ether, and the like.

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

The component (a) is preferably a (meth) acrylate compound, from the viewpoint of easily obtaining a desired melt viscosity and from the viewpoint of being able to select and easily obtain compounds having various structures. From the viewpoint of obtaining more excellent adhesion characteristics as described above, the component (a) may be a (poly) urethane (meth) acrylate compound (a urethane (meth) acrylate compound or a polyurethane (meth) acrylate compound). In addition, the component (a) may be a (meth) acrylate compound having a high Tg skeleton such as a dicyclopentadiene skeleton, from the viewpoint that the above-described adhesive properties are more excellent.

The component (a) may be a compound (for example, a urethane (meth) acrylate) having a polymerizable group such as a vinyl group, an allyl group, or a (meth) acryloyl group introduced into a terminal or side chain of a thermoplastic resin such as an acrylic resin, a phenoxy resin, or a polyurethane resin, from the viewpoint of easily obtaining a desired melt viscosity and from the viewpoint of achieving a balance between a crosslinking density and curing shrinkage, further reducing a connection resistance, and improving connection reliability. In this case, the weight average molecular weight of the component (a) may be 3000 or more, 5000 or more, and 1 ten thousand or more, from the viewpoint of excellent balance between the crosslinking density and the curing shrinkage. The weight average molecular weight of the component (a) may be 100 ten thousand or less, 50 ten thousand or less, and 25 ten thousand or less from the viewpoint of excellent compatibility with other components. The weight average molecular weight is a value measured by Gel Permeation Chromatography (GPC) under the conditions described in examples, using a calibration curve obtained from standard polystyrene.

The (meth) acrylate compound (a) preferably contains a radical polymerizable compound having a phosphate structure represented by the following general formula (1). In this case, since the adhesive strength to the surface of an inorganic substance (metal or the like) is improved, for example, the electrodes (for example, circuit electrodes) are preferably bonded to each other.

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

The radical polymerizable compound having a phosphate structure can be obtained by, for example, 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 and the like.

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

[ (B) ingredient: polymerization initiator

(B) The component (b) may be a photopolymerization initiator (photo radical polymerization initiator, photo cation polymerization initiator or photo anion polymerization initiator) which generates radicals, cations or anions by irradiation with light having a wavelength in the range of 150 to 750nm, preferably light having a wavelength in the range of 254 to 405nm, more preferably light having a wavelength of 365nm (e.g., ultraviolet light), or may be a thermal polymerization initiator (thermal radical polymerization initiator, thermal cation polymerization initiator or thermal anion polymerization initiator) which generates radicals, cations or anions by heat. The component (B) is preferably a radical polymerization initiator (photo radical polymerization initiator or thermal radical polymerization initiator) from the viewpoint of easily obtaining a desired melt viscosity, further improving the effect of reducing the connection resistance, and further improving the connection reliability, and from the viewpoint of easily curing at a low temperature in a short time. As the component (B), one compound may be used alone, or a plurality of compounds may be used in combination. For example, the first curable composition may contain two types of a photopolymerization initiator and a thermal polymerization initiator as the component (B).

The photo radical polymerization initiator is decomposed by light to generate a radical. That is, the photo radical polymerization initiator is a compound that generates radicals by applying light energy from the outside. Examples of the photo radical polymerization initiator include compounds having an oxime ester structure, a bisimidazole structure, an acridine structure, an α -aminoalkylphenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzoin bismethyl ether structure, an α -hydroxyalkylphenone structure, and the like. From the viewpoint of easily obtaining a desired melt viscosity and from the viewpoint of more excellent connection resistance reducing effect, the photo radical polymerization initiator preferably has at least one structure selected from the group consisting of an oxime ester structure, an α -aminoalkylphenone 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-ethoxycarbonyl) oxime, 1-phenyl-1, 2-propanedione-2-o-benzoyloxime, 1, 3-diphenylpropanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxypropanetrione-2- (o-benzoyl) oxime, 1, 2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (o-benzoyloxime) ], ethanone, 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazole- 3-yl-, 1- (o-acetyloxime), and the like.

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

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

The thermal radical polymerization initiator is decomposed by heat to generate a radical. That is, the thermal radical polymerization initiator is a compound that generates radicals by applying thermal energy from the outside. The thermal radical polymerization initiator can be arbitrarily selected from conventionally known organic peroxides and azo compounds. From the viewpoint of stability, reactivity and compatibility, it is preferable to use, as the thermal radical polymerization initiator, an organic peroxide having a half-life temperature of 90 to 175 ℃ for one minute and a weight-average molecular weight of 180 to 1000. When the one-minute half-life temperature is within this range, the storage stability is further excellent, the radical polymerizability is sufficiently high, and the curing can be performed in a short time.

Specific examples of the organic peroxide include: 1,1,3, 3-tetramethylbutylperoxyneodecanoate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, bis (2-ethylhexyl) peroxydicarbonate, cumyl peroxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, tert-hexyl peroxyneodecanoate, tert-butyl peroxypivalate, 1,3, 3-tetramethylbutyl peroxy2-ethylhexanoate, 2, 5-dimethyl-2, 5-di (2-ethylhexanoylperoxy) hexane, tert-hexyl peroxy2-ethylhexanoate, tert-butyl peroxyneoheptanoate, and mixtures thereof, T-amyl peroxy-2-ethylhexanoate, di-t-butyl peroxyhexahydrophthalate, t-amyl peroxy-3, 5, 5-trimethylhexanoate, 3-hydroxy-1, 1-dimethylbutyl peroxyneodecanoate, t-amyl peroxy-2-ethylhexanoate, bis (3-methylbenzoyl) peroxide, dibenzoyl peroxide, bis (4-methylbenzoyl) peroxide, t-hexyl peroxyisopropylmonocarbonate, t-butyl peroxymaleic acid, t-butyl peroxy-3, 5, 5-trimethylhexanoate, t-butyl peroxylaurate, 2, 5-dimethyl-2, 5-bis (3-methylbenzoyl peroxide) hexane, t-butyl peroxy-2-ethylhexyl monocarbonate, t-butyl peroxy2-ethylhexylmonocarbonate, t-butyl peroxycarbonate, t-butyl peroxy2, 5-trimethylhexanoate, t-butyl peroxylaurate, di (3-methylbenzoyl peroxide) hexane, t-butyl peroxydicarbonate, n-butyl peroxyneodecanoate, n-2-butyl peroxyl, n, tert-hexyl peroxybenzoate, 2, 5-dimethyl-2, 5-di (benzoylperoxy) hexane, tert-butyl peroxybenzoate, trimethyl dibutyl peroxyadipate, tert-amyl n-octanoate peroxide, tert-amyl isononanoate peroxide, tert-amyl peroxybenzoate, and the like.

Specific examples of the azo compound include: 2,2 '-azobis-2, 4-dimethylvaleronitrile, 1' -azobis (1-acetoxy-1-phenylethane), 2 '-azobisisobutyronitrile, 2' -azobis (2-methylbutyronitrile), 4 '-azobis (4-cyanovaleric acid), 1' -azobis (1-cyclohexanecarbonitrile) and the like.

The content of the component (B) may be 0.1 mass% or more and 0.5 mass% or more based on the total mass of the first curable composition, from the viewpoint of excellent rapid curability and the viewpoint of excellent reduction effect of connection resistance. The content of the component (B) may be 15 mass% or less, 10 mass% or less, or 5 mass% or less based on the total mass of the first curable composition, from the viewpoint of improving storage stability and from the viewpoint of having an excellent effect of reducing connection resistance.

The first curable composition preferably contains at least one of a photopolymerization initiator and a thermal polymerization initiator as the component (B) from the viewpoint of easily obtaining a desired viscosity, and more preferably contains a photopolymerization initiator from the viewpoint of easily producing the adhesive film for circuit connection.

[ (C) ingredient: conductive particles

(C) The component is not particularly limited as long as it is a particle having conductivity, and may be a metal particle made of a metal such as Au, Ag, Ni, Cu, or solder, a conductive carbon particle made of conductive carbon, or the like. (C) The component (c) may be coated conductive particles each including a core containing a non-conductive glass, ceramic, plastic (polystyrene, etc.), and a coating layer containing the metal or conductive carbon. Among these, coated conductive particles having a core containing metal particles or plastic formed of a heat-fusible metal and a coating layer containing a metal or conductive carbon and coating the core can also be preferably used. In this case, since the cured product of the first curable composition is easily deformed by heating or pressing, when the electrodes are electrically connected to each other, the contact area between the electrodes and the component (C) can be increased, and the conductivity between the electrodes can be further improved.

(C) The component (b) may be an insulating coated conductive particle comprising the above metal particle, conductive carbon particle or coated conductive particle and an insulating layer containing an insulating material such as a resin and coating the surface of the particle. When the component (C) is the insulating coated conductive particle, even when the content of the component (C) is large, the surface of the particle is coated with the resin, so that short circuit due to contact between the components (C) can be suppressed, and the insulation between adjacent electrode circuits can be improved. (C) The component (c) may be one of the above-mentioned various conductive particles alone or two or more of them may be used in combination.

(C) The maximum particle size of the component needs to be smaller than the minimum spacing of the electrodes (the shortest distance between adjacent electrodes). The maximum particle diameter of the component (C) may be 1.0 μm or more, 2.0 μm or more, and 2.5 μm or more, from the viewpoint of excellent dispersibility and conductivity. The maximum particle diameter of the component (C) may be 50 μm or less, 30 μm or less, or 20 μm or less from the viewpoint of excellent dispersibility and electrical conductivity. In the present specification, the particle size of an arbitrary 300 (pcs) conductive particles is measured by observation using a Scanning Electron Microscope (SEM), and the maximum value obtained is the maximum particle size of the component (C). In the case where the component (C) is not spherical, for example, when the component (C) has a protrusion, the particle diameter of the component (C) is the diameter of a circle circumscribing the conductive particles in the image of the SEM.

The average particle diameter of the component (C) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more, from the viewpoint of excellent dispersibility and conductivity. The average particle diameter of the component (C) may be 50 μm or less, 30 μm or less, or 20 μm or less from the viewpoint of excellent dispersibility and electrical conductivity. In the present specification, the particle size of an arbitrary 300 (pcs) conductive particles is measured by observation using a Scanning Electron Microscope (SEM), and the average value of the obtained particle sizes is defined as an average particle size.

In the first adhesive layer, it is preferable that the (C) component be uniformly dispersed. The particle density of the component (C) in the first binder layer may be 100pcs/mm from the viewpoint of obtaining stable connection resistance²Above, it can be 1000pcs/mm²Above, it can be 2000pcs/mm²The above. The particle density of the component (C) in the first binder layer may be 100000pcs/mm from the viewpoint of improving the insulation between adjacent electrodes²Hereinafter, it may be 50000pcs/mm²May be 10000pcs/mm or less²The following.

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

[ other ingredients ]

The first curable composition may further contain other components in addition to the component (a), the component (B), and the component (C). Examples of the other components include a thermoplastic resin, a coupling agent, and a filler. These components may also be contained in the first adhesive layer.

Examples of the thermoplastic resin include: phenoxy resins, polyester resins, polyamide resins, polyurethane resins, polyester urethane resins, acrylic rubbers, and the like. In the case where 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 relaxed. In addition, when the thermoplastic resin has a functional group such as a hydroxyl group, the adhesiveness of the first adhesive layer is easily improved. The content of the thermoplastic resin may be, for example, 5 mass% or more and 80 mass% or less based on the total mass of the first curable composition.

Examples of the coupling agent include silane coupling agents having an organic functional group such as a (meth) acryloyl group, mercapto group, amino group, imidazolyl group, or epoxy group; silane compounds such as tetraalkoxysilane; tetraalkoxy titanate derivatives, polydialkyl titanate derivatives, and the like. When the first curable composition contains a coupling agent, the adhesion can be further improved. The content of the coupling agent may be, for example, 0.1 mass% or more and 20 mass% or less based on the total mass of the first curable composition.

Examples of the filler include non-conductive fillers (e.g., non-conductive particles). When the first curable composition contains a filler, further improvement in connection reliability can be expected. The filler may be any of an inorganic filler and an organic filler. Examples of the inorganic filler include metal oxide fine particles such as silica fine particles, alumina fine particles, silica-alumina fine particles, titania fine particles, and zirconia fine particles; inorganic fine particles such as nitride fine particles. Examples of the organic filler include organic fine particles such as silicone fine particles, methacrylate-butadiene-styrene fine particles, acrylic-silicone fine particles, polyamide fine particles, and polyimide fine particles. These microparticles may have a uniform structure or a core-shell structure. The maximum diameter of the filler material is preferably smaller than the minimum particle diameter of the conductive particles. The content of the filler may be, for example, 0.1 vol% or more and 50 vol% or less based on the total volume of the first curable composition.

The first curable composition may contain other additives such as a softening agent, an accelerator, a deterioration inhibitor, a colorant, a flame retardant, and a thixotropic agent. The content of these additives may be, for example, 0.1 to 10% by mass based on the total mass of the first curable composition. These additives may also be contained in the first adhesive layer.

The first curable composition may contain a thermosetting resin instead of or in addition to the components (a) and (B). The thermosetting resin is a resin that is cured by heat, and has at least one thermosetting group. The thermosetting resin is, for example, a compound which is crosslinked by reacting with a curing agent by heat. As the thermosetting resin, one compound may be used alone, or a plurality of compounds may be used in combination.

The thermosetting group may be, for example, an epoxy group, an oxetane group, an isocyanate group, or the like, from the viewpoint of easily obtaining a desired melt viscosity, further improving the effect of reducing the connection resistance, and further improving the connection reliability.

Specific examples of the thermosetting resin include bisphenol type epoxy resins which are reaction products of epichlorohydrin and bisphenol a, bisphenol F, bisphenol AD, and the like; epoxy novolac resins as reaction products of epichlorohydrin with phenol novolac, cresol novolac, and the like; a naphthalene-based epoxy resin having a skeleton containing a naphthalene ring; epoxy resins such as various epoxy compounds having two or more glycidyl groups in one molecule, for example, glycidyl amine and glycidyl ether.

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

When the first curable composition contains a thermosetting resin, the first curable composition may contain a curing agent for the thermosetting resin. Examples of the curing agent for thermosetting resins include a thermal radical generator, a thermal cation generator, and a thermal anion generator. The content of the curing agent may be, for example, 0.1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the thermosetting resin.

The first adhesive layer may contain unreacted components derived from the first curable composition, such as the component (a) and the component (B). Presume that: when the adhesive film of the present embodiment is stored in a conventional storage member and stored and transported, the unreacted component (B) remains in the first adhesive layer, and thus a part of the second curable composition in the second adhesive layer is cured during storage and transportation, and there are problems that peeling between the circuit member and the circuit connecting portion is likely to occur under a high-temperature and high-humidity environment, and the effect of reducing the connection resistance of the adhesive film is reduced. Therefore, from the viewpoint of being able to suppress the occurrence of the above-described failure, the content of the component (B) in the first adhesive layer may be 15 mass% or less, may be 10 mass% or less, and may be 5 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 mass% or more based on the total mass of the first adhesive layer. In the case where the first adhesive layer contains a photopolymerization initiator as the component (B), the adhesive film is accommodated in an accommodating member described later, whereby the occurrence of the above-described problem can be suppressed.

From the viewpoint of making the peeling more difficult, the melt viscosity X of the first adhesive layer at the temperature Ty at which the second adhesive layer has the lowest melt viscosity Y may be 1000Pa · s or more, 10000Pa · s or more, and 50000Pa · s or more. The melt viscosity X may be 10000000Pa · s or less, 1000000Pa · s or less, and 500000Pa · s or less, from the viewpoint of excellent wettability to the substrate. 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, and the like.

From the viewpoint of facilitating trapping of the conductive particles between the electrodes and further reducing the connection resistance, the thickness of the first binder layer may be 0.1 times or more, 0.2 times or more, and 0.3 times or more the average particle diameter of the conductive particles. From the viewpoint that the conductive particles are more easily crushed when they are sandwiched between the counter electrodes at the time of thermocompression bonding, and the connection resistance can be further reduced, the thickness of the first adhesive layer 2 may be 1.0 times or less, 0.8 times or less, and 0.7 times or less the average particle diameter of the conductive particles. From these viewpoints, the thickness of the first adhesive layer may be 0.1 to 0.7 times, may be 0.2 to 0.8 times, and may be 0.3 to 0.7 times the average particle diameter of the conductive particles. In addition, the thickness of the adhesive layer refers to the thickness of the adhesive layer located at the spaced apart portions of the adjacent conductive particles. In the case where the thickness of the first adhesive layer and the average particle diameter of the conductive particles satisfy the relationship as described above, for example, as shown in fig. 1, a part 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. At this time, the boundary S of the first adhesive layer 13 and the second adhesive layer 14 is located at the spaced portion of the adjacent conductive particles P. The conductive particles P may not be exposed on the surface of the first adhesive layer 13 on the side opposite to the second adhesive layer 14, and the surface on the opposite side may be a flat surface.

The thickness of the first adhesive layer may be appropriately set according to the height of the electrode of the circuit part to be bonded, and the like. The thickness of the first adhesive layer may be, for example, 0.5 μm or more and 20 μm or less. In addition, when a part of the conductive particles is exposed from the surface of the first adhesive layer (for example, protrudes to the second adhesive layer side), the distance from the surface of the first adhesive layer on the side opposite to the second adhesive layer side to the boundary S between the first adhesive layer and the second adhesive layer located at the separation portion of the adjacent conductive particles is the thickness of the first adhesive layer, and the exposed portion of the conductive particles is not included in the thickness of the first adhesive layer. The length of the exposed portion of the conductive particles may be, for example, 0.1 μm or more and 20 μm or less. The thickness of the adhesive layer can be measured by the following method.

An adhesive film was sandwiched between two sheets of glass (thickness: about 1 mm), and after casting with a resin composition formed of 100g of bisphenol a type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10g of a curing agent (trade name: Epomount curing agent, manufactured by Refine Tec ltd.), cross-sectional grinding was performed 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 Corporation).

(second adhesive layer)

The second adhesive layer is formed of, for example, a second curable composition. The second curable composition contains, for example, (a) a polymerizable compound (hereinafter also referred to as a component (a)) and (b) a polymerization initiator (hereinafter also referred to as a component (b)). The second curable composition constituting the second adhesive layer may be an uncured curable composition, for example, an uncured curable composition, which is flowable at the time of circuit connection.

[ (a) ingredient: polymerizable Compound ]

(a) The component (b) is, for example, a compound which is polymerized by a radical, cation or anion generated by irradiation of light (for example, ultraviolet light) or heating by a polymerization initiator (photopolymerization initiator or thermal polymerization initiator). As the component (a), compounds exemplified as the component (a) can be used. The component (a) is preferably a radical polymerizable compound having a radical polymerizable group that reacts with a radical, from the viewpoint of facilitating connection at low temperature in a short time, easily obtaining a desired melt viscosity, further improving the effect of reducing connection resistance, and further improving connection reliability. (a) Examples of the preferable radical polymerizable compound in the component (a) and combinations of the preferable radical polymerizable compounds are the same as those of the component (a). When the component (a) is a radical polymerizable compound and the component (B) in the first adhesive layer is a photo radical polymerization initiator, the adhesive film is stored in a storage member described later, and thus curing of the second curable composition during storage or transportation of the adhesive film tends to be significantly suppressed.

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

The content of the component (a) may be 10 mass% or more, 20 mass% or more, and 30 mass% or more based on the total mass of the second curable composition, from the viewpoint of easily obtaining a crosslinking density required for reducing connection resistance and improving connection reliability. From the viewpoint of suppressing curing shrinkage during polymerization and obtaining good reliability, the content of the component (a) may be 90 mass% or less, may be 80 mass% or less, and may be 70 mass% or less, based on the total mass of the second curable composition.

[ (b) component: polymerization initiator

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

The content of the component (b) may be 0.1 mass% or more, 0.5 mass% or more, and 1 mass% or more based on the total mass of the second curable composition, from the viewpoint of facilitating connection at low temperature in a short time and from the viewpoint of further improving connection reliability. From the viewpoint of pot life, the content of the component (b) may be 30% by mass or less, 20% by mass or less, and 10% by mass or less, based on the total mass of the second curable composition.

[ other ingredients ]

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

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

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

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

The thickness of the second adhesive layer may be appropriately set according to the height of the electrode of the circuit part to be bonded, and the like. The thickness of the second adhesive layer may be 5 μm or more and 200 μm or less from the viewpoint of sufficiently filling the space between the electrodes to seal the electrodes and obtain more excellent reliability. In addition, when a part of the conductive particles is exposed from the surface of the first adhesive layer (for example, protrudes to the second adhesive layer side), the distance from the surface of the second adhesive layer on the side opposite to the first adhesive layer side to the boundary S between the first adhesive layer and the second adhesive layer located at the separation portion of the adjacent conductive particles is the thickness of the second adhesive layer.

From the viewpoint of being able to sufficiently fill the space between the electrodes to seal the electrodes and obtain more excellent reliability, the ratio of the thickness of the first adhesive layer 2 to the thickness of the second adhesive layer (thickness of the first adhesive layer/thickness of the second adhesive layer) may be 1 or more and 1000 or less.

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

The adhesive film for circuit connection may include a releasable support film and an adhesive layer containing an adhesive component and conductive particles provided on the support film, the conductive particles may be present on the support film side and dispersed in a direction orthogonal to the thickness direction of the adhesive layer, and the adhesive layer may have a first region containing a cured product of the first curable composition and a second region containing the second curable composition in the thickness direction of the adhesive layer from the support film side. The ranges in the thickness direction of the adhesive layers of the first and second regions can be set in the same manner as the thicknesses of the first and second adhesive layers described above, respectively. The conductive particles can be set in the same manner as the above conditions.

The adhesive film for circuit connection of the present embodiment has been described above, but the present invention is not limited to the above embodiment.

[ method for producing Circuit connection Structure ]

The method for manufacturing a circuit connection structure according to the present embodiment is a method for manufacturing a circuit connection structure in which a first circuit member provided with a first circuit electrode and a second circuit member provided with a second circuit electrode corresponding to the first circuit electrode are connected to each other via the adhesive film for circuit connection according to the present embodiment.

The method of the present embodiment includes, for example:

a preparation step of preparing the adhesive film for circuit connection of the present embodiment, a lamination step of laminating the adhesive film for circuit connection on the first circuit member so that the second adhesive layer side of the adhesive film for circuit connection faces the surface on which the circuit electrode of the first circuit member is provided, and

and a heating and pressing step of disposing a second circuit member on the first circuit member on which the adhesive film for circuit connection is laminated so that the first circuit electrode and the second circuit electrode face each other, and pressing the first circuit member and the second circuit member in a direction in which the first circuit electrode and the second circuit electrode face each other while heating the adhesive film for circuit connection.

(preparation Process)

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

The method for producing the adhesive film for circuit connection according to the present embodiment may include, for example: a preparation step (first preparation step) of preparing the first adhesive layer; and a laminating step of laminating the second adhesive layer on the first adhesive layer. The method for producing an adhesive film for circuit connection may further comprise: and a preparation step (second preparation step) of preparing a second adhesive layer.

In the first preparation process, for example, a first adhesive film is obtained by forming a first adhesive layer on a support film, thereby preparing the first adhesive layer. Specifically, the varnish composition is prepared by first adding the component (a), the component (B), and the component (C), and other components added as needed, to an organic solvent, and dissolving or dispersing the components by stirring, mixing, kneading, or the like. Then, after the varnish composition is applied to the substrate subjected to the release treatment using a knife coater, a roll coater, an applicator, a comma coater, a die coater, or the like, the organic solvent is volatilized by heating, and a layer composed of the first curable composition is formed on the substrate. Next, the layer formed of the first curable composition is irradiated with light or heated to cure the first curable composition, thereby forming a first adhesive layer on the substrate (curing step). Thereby, a first adhesive film was obtained.

The organic solvent used for the preparation of the varnish composition is preferably an organic solvent having a property of uniformly dissolving or dispersing each component, and examples thereof include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These organic solvents can be used alone or in combination of two or more. The stirring, mixing and kneading in the preparation of the varnish composition can be carried out using, for example, a stirrer, a mill, a three-roll mill, a ball mill, a bead mill or a homogenizer.

The support film is not particularly limited as long as it has heat resistance that can withstand heating conditions when the organic solvent is volatilized when the first curable composition is cured by light, and is not particularly limited as long as it has heat resistance that can withstand heating conditions when the organic solvent is volatilized and heating conditions when the first curable composition is cured by heating. As the support film, for example, a substrate (e.g., a film) formed of oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, an ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, a synthetic rubber system, a liquid crystal polymer, or the like can be used. From the viewpoint of high versatility, polyethylene terephthalate can be preferably used.

The heating condition for evaporating the organic solvent from the varnish composition applied to the support film is preferably a condition under which the organic solvent is sufficiently evaporated. The heating conditions may be, for example, 40 ℃ to 120 ℃, 0.1 minute to 10 minutes.

In the irradiation with light in the curing step, it is preferable to use irradiation light (for example, ultraviolet light) having a wavelength in the range of 150 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 ultrahigh-pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like. The irradiation amount of light can be adjusted so that the ratio of melt viscosity (X/Y) is 10 or more. The dose of light irradiation may be, for example, 100mJ/cm in terms of the integrated dose of light having a wavelength of 365nm²Above, it may be 200mJ/cm²Above, it may be 300mJ/cm²The above. The dose of light irradiation may be 10000mJ/cm, for example, in terms of the integrated dose of light having a wavelength of 365nm²Below, it may be 5000mJ/cm²Below, 3000mJ/cm²The following. As the irradiation amount of light (integrated amount of light) is larger, the melt viscosity X tends to be larger, and the ratio (X/Y) of the melt viscosity tends to be larger.

The heating condition in the curing step may be adjusted so that the ratio of melt viscosity (X/Y) is 10 or more. The heating conditions may be, for example, 30 ℃ to 300 ℃, 0.1 to 5000 minutes, or 50 ℃ to 150 ℃, 0.1 to 3000 minutes. The higher the heating temperature, the higher the melt viscosity X tends to be, and the higher the ratio (X/Y) of the melt viscosity X tends to be. Further, the melt viscosity X tends to be larger as the heating time is longer, and the ratio (X/Y) of the melt viscosity tends to be larger.

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

In the laminating 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 the component (a) and the component (b) and other components added as needed on the first adhesive layer and volatilizing an organic solvent.

Examples of the method for bonding the first adhesive film and the second adhesive film include a method of heating and pressing, a method of roll lamination, and a method of vacuum lamination. The lamination can be carried out, for example, under heating conditions of 0 to 80 ℃.

In the present embodiment, when the adhesive film for circuit connection is used in which 90% or more of the conductive particles P in the first adhesive layer are separated from other conductive particles, the dispersed state can be formed by the subsequent magnetic field application step. In this case, particles containing nickel are preferably used as the conductive particles P from the viewpoint of dispersing the conductive particles P in the magnetic field application step. In general, it is known that iron, cobalt, and nickel are ferromagnetic substances and are magnetized by an external magnetic field, but among them, nickel is used significantly in terms of compatibility between electrical conductivity and dispersibility by application of a magnetic field. In order to obtain storage stability of the conductive particles P, the surface layer of the conductive particles P may be made of a noble metal such as gold or silver, which is a white metal, instead of nickel. Further, the surface of the nickel may be coated with a noble metal such as Au. Further, glass, ceramics, plastics, or the like, which is non-conductive and is coated with a conductive material such as the above-described metal, may be used, and in this case, a nickel layer may be provided to form a multilayer structure.

Further, since the magnetic properties of nickel are affected by the concentration of phosphorus contained in nickel plating, it is preferable to adjust the magnetic properties necessary for dispersing the conductive particles P by a magnetic field at appropriate times. The magnetic properties of the conductive particles P can be measured, for example, by a Sample vibration magnetometer (VSM). In order to disperse the conductive particles P by an external magnetic field, the saturation magnetization is preferably in the range of 5.0 to 50emu/g in the VSM measurement. When the amount is 5.0emu/g or more, the conductive particles P are easily dispersed sufficiently. On the other hand, if it is 50emu/g or less, the magnetization of the conductive particles P is not excessively large, and the conductive particles P are prevented from being bonded in the thickness direction of the first adhesive layer 13, and the dispersibility of the conductive particles P tends to be high.

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

The blending amount of the conductive particles P is preferably set to 1 to 100 volume parts with respect to 100 volume parts of the component of the first adhesive layer other than the conductive particles P. From preventing the conductive particles P from passingThe amount of the conductive particles P to be mixed is more preferably 10 to 50 parts by volume from the viewpoint of short-circuiting between adjacent circuit electrodes due to the presence of the conductive particles P. Further, the particle density of the conductive particles is preferably 1000 particles/mm in the range of the average particle diameter of the conductive particles from 1.0 μm to 10.0 μm²Above 50000 pieces/mm²The following. In this case, the dispersibility of the conductive particles P and the insulation between adjacent circuit electrodes can be preferably both satisfied.

(laminating step)

Fig. 2 is a schematic cross-sectional view showing a lamination step in the method for manufacturing a connection structure according to the present embodiment. In this step, as shown in the drawing, the circuit-connecting adhesive film 11 is laminated on the first circuit member 2 so that the second adhesive layer 14 side of the circuit-connecting adhesive film 11 faces the surface of the first circuit member 2 on which the first circuit electrodes 6 are provided. In the case where the circuit-connecting adhesive film 11 has a release film provided on the second adhesive layer 14, the second adhesive layer 14 can be laminated so as to be in close contact with the first circuit member 2 after or while the release film is peeled.

The first circuit member 2 has a circuit electrode 6 on the mounting surface 5a side of the main body 5. Examples of the first circuit member 2 include a flexible substrate member having COP, FCP, polyimide, or the like. The circuit electrode 6 is made of copper plated with a metal such as tin, for example. In addition, an insulating layer may be formed on the mounting surface 5a at a portion where the circuit electrode 6 is not formed.

As the laminating mechanism, a known laminator can be used. The conditions for lamination can be set appropriately.

Fig. 3 is a schematic cross-sectional view showing a laminate obtained through a lamination process.

(heating and pressurizing step)

Fig. 4 is a schematic cross-sectional view showing a heating and pressing step in the method for manufacturing a connection structure according to the present embodiment. In this step, as shown in the drawing, the second circuit member 3 is disposed on the first circuit member 2 on which the adhesive film for circuit connection (the second adhesive layer 14 and the first adhesive layer 13) is laminated so that the first circuit electrode 6 and the second circuit electrode 8 face each other, and the first circuit member 2 and the second circuit member 3 are pressed in the direction in which the first circuit electrode 6 and the second circuit electrode 8 face each other while heating the adhesive film for circuit connection (the second adhesive layer 14 and the first adhesive layer 13).

The second circuit member 3 is, for example, a glass substrate, a plastic substrate, a ceramic wiring board, or the like used in a liquid crystal display, on which a circuit is formed of ITO, IZO, metal, or the like. As shown in fig. 4, the second circuit member 3 has second circuit electrodes 8 corresponding to the first circuit electrodes 6 on the mounting surface 7a side of the main body portion 7.

The circuit electrode 8 has a rectangular shape in plan view, for example, and has a thickness of about 100nm to 1000nm, for example. The surface of the circuit electrode 8 is made of one or more materials selected from gold, silver, copper, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, Indium Tin Oxide (ITO), and Indium Zinc Oxide (IZO), for example. In addition, an insulating layer may be formed on the mounting surface 7a at a portion where the circuit electrode 8 is not formed.

A known thermocompression bonding apparatus can be used as the heating mechanism. The heating temperature of the circuit connecting adhesive film (the second adhesive layer 14 and the first adhesive layer 13) is preferably not lower than the temperature at which the polymerization active species is generated in the curing agent and the polymerization of the monomer starts. The heating temperature is, for example, 80 to 200 ℃ and preferably 100 to 180 ℃. The heating time is, for example, 0.1 to 30 seconds, preferably 1 to 20 seconds. When the heating temperature is 80 ℃ or higher, a sufficient curing rate can be easily obtained, and when the heating temperature is 200 ℃ or lower, undesirable side reactions are less likely to proceed. When the heating time is 0.1 seconds or more, the curing reaction is likely to sufficiently proceed, and when the heating time is 30 seconds or less, the productivity of the cured product is likely to be maintained, and further, undesirable side reactions are unlikely to proceed.

A known thermocompression bonding apparatus can be used as the pressing mechanism. The pressure and time for pressurization can be set appropriately.

Fig. 5 is a schematic cross-sectional view showing a circuit connection structure obtained through a heating and pressing step. In the heat and pressure step, the adhesive component of the adhesive film for circuit connection (the second adhesive layer 14 and the first adhesive layer 13) flows, and the second adhesive layer and the first adhesive layer are cured 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 engaged with each other. The circuit connecting structure 1 shown in fig. 5 is obtained by forming the cured product 4 of the adhesive film for circuit connection (the second adhesive layer 14 and the first adhesive layer 13) in a state where the first circuit electrode 6 and the second circuit electrode 8 are electrically connected and the adjacent circuit electrodes 6 and the

adjacent circuit electrodes

8 and 8 are electrically insulated from each other by curing the second adhesive layer and the first adhesive layer. In the obtained circuit connection structure 1, the cured product 4 of the adhesive film for circuit connection (the second adhesive layer 14 and the first adhesive layer 13) can sufficiently prevent a change with time in the distance between the first circuit electrode 6 and the second circuit electrode 8, and can also ensure long-term reliability of electrical characteristics.

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

The conductive particles P are interposed between the first circuit electrode 6 and the second circuit electrode 8 in a state of being slightly deformed flatly by pressure bonding. Thereby, the electrical connection between the first circuit electrode 6 and the second circuit electrode 8 is achieved. The conductive particles P are spaced apart from each other between the

first circuit electrodes

6 and 6 adjacent to each other and between the

second circuit electrodes

8 and 8 adjacent to each other, thereby electrically insulating the

first circuit electrodes

6 and 6 adjacent to each other and the

second circuit electrodes

8 and 8 adjacent to each other.

[ method for producing adhesive film for Circuit connection ]

Fig. 6 is a schematic view showing a process for producing 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 delivery roll 21 and the take-up roll 22. A coater 23 for coating a binder paste W to be a material for forming the first binder layer 13 is disposed on the transport path of the support film 12, and the binder paste W in which the conductive particles P are dispersed is coated on the support film 12 by the coater 23 (coating step). The thickness of the binder paste W applied to the support film 12 by the coater 23 varies depending on the proportion of the solvent contained in the resin composition, but is preferably less than 1.6 times the average particle diameter of the conductive particles P.

The viscosity of the binder paste W may vary depending on the application and the coating method, and is usually preferably 10 to 10000mPa · s. From the viewpoint of suppressing the separation of the formulation in the adhesive paste W and improving the compatibility, it is more preferably 50 to 5000mPa · s. In order to improve the appearance of the adhesive film 11 for circuit connection, it is preferable to set the pressure-sensitive adhesive film to 100 to 3000mPa · s. When the viscosity is 10000mPa · s or less, it is difficult to suppress dispersion of the conductive particles P in the subsequent magnetic field application step, and when the viscosity is 10mPa · s or more, it is difficult to cause separation of the formulation of the adhesive paste W.

The method of applying the adhesive paste W is not limited to the above method, and a known method can be used. Examples thereof include spin coating, roll coating, bar coating, dip coating, microgravure coating, curtain coating, die coating, spray coating, blade coating, kneader coating, flow coating, screen printing, and casting. The bar coating method, the die coating method, the micro-gravure coating method, and the like are suitable for producing the adhesive film 11 for circuit connection, and the micro-gravure coating method is particularly preferable from the viewpoint of accuracy of film thickness.

On the rear stage side of the coater 23, a pair of

magnets

24 and 25 are arranged to face each other in the vertical direction so as to sandwich the support film 12. In the present embodiment, as shown in fig. 7, the magnet 24 disposed on the upper side is an N-pole, the magnet 25 disposed on the lower side is an S-pole, and a magnetic field is formed in a direction substantially perpendicular from the magnet 24 to the magnet 25. Therefore, when the support film 12 is transported between the

magnets

24 and 25, the conductive particles P in the adhesive paste W are magnetized, and the conductive particles P are separated from each other in the in-plane direction of the adhesive paste W by the repulsive force (magnetic field applying step).

In order to maintain the spaced 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 support 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 fig. 8, the first adhesive layer 13 in which 70% or more, preferably 90% or more of the conductive particles P are separated from other adjacent conductive particles P is formed on the support film 12. In addition, the thickness of the adhesive paste W is gradually reduced by the drying step, and by making the thickness of the adhesive paste W smaller than 1.6 times the average particle diameter of the conductive particles P in advance as described above, the thickness of the first adhesive layer 13 is easily made 0.6 times or more and smaller than 1.0 times the average particle diameter of the conductive particles P. Further, by using a binder paste (varnish) diluted with an organic solvent (for example, methyl ethyl ketone), the thickness of the binder layer can be reduced to about 0.1 times the average particle diameter of the conductive particles P. The amount of the organic solvent to be diluted is not particularly limited, and is preferably 50 to 500 parts by mass per 100 parts by mass of the binder component.

The drying temperature of the binder paste W is preferably 20 to 80 ℃. The transport speed of the support film 12 is preferably 30mm/s to 160mm/s, for example. For example, when the conductive particles P having an average particle diameter of 3 μm are used, the thickness of the adhesive paste W is preferably 5 μm to 10 μm. When the transport speed of the support film 12 is 30mm/s or more, the adhesive paste W is dried in a state where the conductive particles P are sufficiently spaced apart, and thus the dispersion tends to be sufficient. When the transport speed of the support film 12 is 160mm/s or less, the application of the magnetic field after drying tends to be completed, and re-aggregation of the conductive particles P can be suppressed. In addition, when the thickness of the adhesive paste W is 5 μm or more, the gap shortage of the coater 23 can be suppressed, and the shortage of the number of the 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 of the coater 23 can be suppressed from being excessive, and the number of conductive particles P in the first adhesive layer 13 can be suppressed from being excessive.

After the first adhesive layer 13 is formed, as shown in fig. 9, a second adhesive layer 14 formed on a release film 15 is separately laminated on the first adhesive layer 13 (laminating step). Thereby, the adhesive film 11 for circuit connection shown in fig. 2 was obtained. In the lamination of the second adhesive layer 14, for example, a hot roll laminator can be used. Further, the adhesive paste which becomes the material of the second adhesive layer 14 may be applied to the first adhesive layer 13 and dried, without being limited to lamination.

As described above, in the adhesive film 11 for circuit connection, 70% or more, preferably 90% or more 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 member 2 and the second circuit member 3 are connected, aggregation of the adjacent conductive particles P and conductive particles P can be suppressed, and insulation between the adjacent first circuit electrodes 6 and insulation between the adjacent second circuit electrodes 8 and second circuit electrodes 8 can be ensured. In the adhesive film 11 for circuit connection, the thickness of the first adhesive layer 13 can be set to 0.1 to 1.0 times, 0.1 to 0.7 times, or 0.6 to less than 1.0 times the average particle diameter of the conductive particles P. At this time, the flow of the conductive particles P at the time of pressure bonding is 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 part 2 and the second circuit part 3 can be ensured.

< adhesive film containing set >

Fig. 10 is a perspective view showing an adhesive film containing kit according to an embodiment. As shown in fig. 10, the adhesive film housing kit 120 includes: an adhesive film 11 for circuit connection, a reel 121 on which the adhesive film 11 is wound, and a housing member 122 for housing the adhesive film 11 and the reel 121.

As shown in fig. 10, the adhesive film 11 is, for example, a tape. The tape-like adhesive film 11 is produced by cutting a sheet-like roll into a long strip shape with a width according to the application, for example. The adhesive film 11 may have a support film 12 on the first adhesive layer side. As the support film 12, the above-described base material such as a PET film can be used.

The spool 121 includes: the adhesive film 11 includes a first side plate 124 having a winding core 123 for winding the adhesive film 11 and a second side plate 125 disposed to face the first side plate 124 with the winding core 123 interposed therebetween.

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

The first side plate 124 has a winding core 123 that is a portion around which the adhesive film 11 is wound. The winding core 123 is formed of, for example, plastic and has a ring shape having the same thickness as the width of the adhesive film 11. The winding core 123 is fixed to the inner surface of the first side plate 124 so as to surround the opening of the first side plate 124. A shaft hole 126, into which a rotating shaft of a winding device or an output device (not shown) is inserted, is provided in the center of the spool 121. When the rotating shaft of the winding device or the output device is driven in a state where the rotating shaft is inserted into the shaft hole 126, the spool 121 rotates without idling. A desiccant container for containing a desiccant may be fitted into the shaft hole 126.

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

The housing member 122 is, for example, a bag-like shape, and houses the adhesive film 11 and the reel 121. The receiving member 122 has an insertion opening 127 for receiving (inserting) the adhesive film 11 and the reel 121 into the receiving member 122.

The housing member 122 has a visible portion 128 through which the inside of the housing member 122 can be seen from the outside. The storage member 122 shown in fig. 10 is configured such that the entire storage member 122 becomes the visible portion 128.

The visible portion 128 has transmissivity to visible light. For example, when the transmittance of the visible light part 128 with respect to light is measured in the wavelength range of 450 to 750nm, at least one region having a transmittance of 30% or more on the average and a wavelength width of 50nm exists between the wavelengths of 450 to 750 nm. The transmittance of the visible part 28 with respect to light can be obtained by preparing a sample in which the visible part 128 is cut into a predetermined size and measuring the transmittance of the sample with respect to light with an ultraviolet-visible spectrophotometer. Since the storage member 122 has such a visible portion 128, various information such as a product name, a lot number, and an expiration date attached to the reel 121 inside the storage member 122 can be confirmed from the outside of the storage member 122. This can prevent the product from being mixed with an error and improve the efficiency of the sorting operation.

The visible part 128 has a transmittance of 10% or less for light having a wavelength of 365 nm. Since the visible light portion 128 has a transmittance of light having a wavelength of 365nm of 10% or less, curing of the second curable composition due to light entering from the outside to the inside of the housing member 122 and the photopolymerization initiator remaining in the first adhesive layer when the photopolymerization initiator is used as the component (B) can be suppressed. From the viewpoint of further suppressing generation of active species (for example, radicals) from the photopolymerization initiator, the transmittance of the visible region 128 for light having a wavelength of 365nm is preferably 10% or less, more preferably 5% or less, still more preferably 1% or less, and particularly preferably 0.1% or less.

From the same viewpoint, the maximum value of the transmittance of light in the visible region 128 in the wavelength region in which radicals, cations, or anions can be generated from the photopolymerization initiator (component (B)) is preferably 10% or less, more preferably 5% or less, still more preferably 1% or less, and particularly preferably 0.1% or less. Specifically, the maximum value of the transmittance of the visible region 128 for light having a wavelength of 254 to 405nm is preferably 10% or less, more preferably 5% or less, still more preferably 1% or less, and particularly preferably 0.1% or less.

The visible part 128 (housing member 122) is formed of a sheet having a thickness of 10 to 5000 μm, for example. The sheet is made of a material having a transmittance of the visible region 128 of 10% or less with respect to light having a wavelength of 365 nm. Such a material may be formed of one component or may be formed of a plurality of components. Examples of the material include low-density polyethylene, linear low-density polyethylene, polycarbonate, polyester, acrylic resin, polyamide, and glass. These materials may also contain uv absorbers. The visible portion 128 may have a laminated structure formed by laminating a plurality of layers having different light transmittances. In this case, each layer constituting the visible part 128 may be formed of the above-described material.

In order to prevent air from entering from the outside during storage, the insertion port 127 may be sealed by, for example, sealing with a sealer or the like. In this case, it is preferable to suck and remove air in the storage member 122 in advance before closing the insertion port 127. It is expected that moisture in the housing member 122 is reduced from the initial stage of housing, and that air is prevented from entering from the outside. Further, since the inner surface of the housing member 122 is in close contact with the spool 121, it is possible to prevent the inner surface of the housing member 122 from rubbing against the surface of the spool 121 due to vibration during transportation, thereby preventing the

side plates

124 and 125 of the spool 121 from being scratched.

In the above embodiment, the storage member is configured such that the entire storage member is the visible portion, but in another embodiment, the storage member may have a visible portion in a part of the storage member. For example, the housing member may have a visible portion of a rectangular shape at substantially the center of the side surface of the housing member. In this case, the portion of the receiving member other than the visible portion may be black so as not to transmit, for example, ultraviolet light and visible light.

In the above embodiment, the housing member is formed in a bag shape, and the housing member may be formed in a box shape, for example. The receiving member is preferably provided with a cut for unsealing. In this case, the unsealing operation at the time of use becomes easy.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

< preparation of polyester urethane resin >

In a stainless steel autoclave equipped with a heater and equipped with a stirrer, a thermometer, a condenser, a vacuum generator, and a nitrogen gas inlet tube, 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were charged, and 0.02 part by mass of tetrabutoxy titanate as a catalyst was further charged. Then, the temperature was raised to 220 ℃ under a nitrogen stream, and the mixture was stirred for 8 hours. Then, the pressure was reduced to atmospheric pressure (760mmHg), and after cooling to room temperature, a white precipitate was taken out, washed with water, and vacuum-dried to obtain a polyester polyol.

The polyester polyol obtained by the reaction of the dicarboxylic acid and the diol was sufficiently dried, dissolved in MEK (Methyl Ethyl Ketone), and charged into a four-neck flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a nitrogen gas introduction tube. Then, dibutyltin laurate as a catalyst in an amount of 0.05 parts by mass per 100 parts by mass of the polyester polyol, 4' -diphenylmethane diisocyanate dissolved in MEK in an amount of 50 parts by mass per 100 parts by mass of the polyester polyol was introduced via a dropping funnel, and the mixture was stirred at 80 ℃ for 4 hours, thereby obtaining an intended polyester urethane resin.

< Synthesis of polyurethane acrylate (UA1) >

2500 parts by mass (2.50mol) of poly (1, 6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei corporation, number average molecular weight: 1000) and 666 parts by mass (3.00mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich Co. LLC) were uniformly dropped over 3 hours in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser having a calcium chloride drying tube, and a nitrogen introduction tube. Then, after sufficiently introducing nitrogen gas into the reaction vessel, the reaction vessel is heated to 70 to 75 ℃ to carry out a reaction. Subsequently, 0.53 parts by mass (4.3mmol) of hydroquinone monomethyl ether (manufactured by Sigma-Aldrich co.llc) and 5.53 parts by mass (8.8mmol) of dibutyltin dilaurate (manufactured by Sigma-Aldrich co.llc) were added to the reaction vessel, and then 238 parts by mass (2.05mol) of 2-hydroxyethyl acrylate (manufactured by Sigma-Aldrich co.llc) were added thereto, and the reaction was carried out at 70 ℃ for 6 hours under an air atmosphere. Thus, a polyurethane acrylate (UA1) was obtained. The weight average molecular weight of the polyurethane acrylate (UA1) was 15000. In addition, the weight average molecular weight was determined by Gel Permeation Chromatography (GPC) using a calibration curve obtained from standard polystyrene according to the following conditions.

(measurement conditions)

The device comprises the following steps: GPC-8020 manufactured by TOSOH CORPORATION

A detector: RI-8020 manufactured by TOSOH CORPORATION

Pipe column: gelpackg LA160S + GLA150S manufactured by Hitachi Chemical Co., Ltd

Sample concentration: 120mg/3mL

Solvent: tetrahydrofuran (THF)

Injection amount: 60 μ L

Pressure: 2.94X 10⁶Pa(30kgf/cm²)

Flow rate: 1.00mL/min

< production of conductive particles >

On the surface of the polystyrene particles, a layer made of nickel was formed so that the thickness of the layer became 0.2 μm. Thus, conductive particles having an average particle diameter of 4 μm, a maximum particle diameter of 4.5 μm and a specific gravity of 2.5 were obtained.

< preparation of varnish (varnish composition) of layer containing conductive particles >

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

(polymerizable Compound)

A1: dicyclopentadiene type diacrylate (trade name: DCP-A, manufactured by TOAGOSEI CO., LTD.)

A2: polyurethane acrylates synthesized as described above (UA1)

A3: 2-methacryloyloxyethyl acid phosphate (trade name: Light Ester P-2M, manufactured by KYOEISHA CHEMICAL Co., LTD.)

(photopolymerization initiator)

B1: b1: 1, 2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (o-benzoyloxime) ] (trade name: Irgacure (registered trademark) OXE01, manufactured by BASF SE)

(thermal polymerization initiator)

C1: benzoyl peroxide (trade name: NYPER BMT-K40, manufactured by NOF CORPORATION)

(conductive particles)

D1: conductive particles produced as described above

(thermoplastic resin)

E1: the polyester urethane resin synthesized above

(coupling agent)

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

(Filler)

G1: fine silica particles (trade name: R104, Nippon AEROSIL CO., manufactured by LTD., average particle diameter (primary particle diameter): 12nm)

(solvent)

H1: methyl ethyl ketone

[ Table 1]

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

The same components as those of the polymerizable compounds a1 to A3, the thermoplastic resin E1, the coupling agent F1, the filler G1 and the solvent H1 in the photocurable composition were used as the polymerizable compounds a1 to A3, the thermoplastic resin E1, the coupling agent F1, the filler G1 and the solvent H1, and these components and a thermal polymerization initiator shown below were mixed in the blending amounts (parts by mass) shown in table 2 to prepare a varnish of the thermosetting composition 1. The content (vol%) of the filler described in table 2 is based on the total volume of the thermosetting composition.

(thermal polymerization initiator)

c 1: benzoyl peroxide (trade name: NYPER BMT-K40, manufactured by NOF CORPORATION)

[ Table 2]

(example 1)

[ production of first adhesive film ]

The varnish of the photocurable composition 1 was coated on a PET film having a thickness of 50 μm using a coating apparatus. Subsequently, hot air drying was performed at 70 ℃ for 3 minutes while applying a magnetic field, thereby forming a layer of the photocurable composition 1 having a thickness (thickness after drying) of 4 μm on the PET film. The thickness here is measured using a contact thickness meter. In addition, when a contact thickness meter is used, the thickness of the region where the conductive particles are present is measured by reflecting the size of the conductive particles. Therefore, after the second adhesive layer is laminated to produce a two-layer circuit connecting adhesive film, the thickness of the first adhesive layer located at the separation portion between adjacent conductive particles is measured by a method described later.

Next, a metal halide lamp was used to add up to an amount of light of 1500mJ/cm to the layer formed of the photocurable composition 1²The method (3) is a method of polymerizing the polymerizable compound by irradiation with light. Thereby, the photocurable composition 1 is cured to form the first adhesive layer. Through the above operation, a first adhesive film having a first adhesive layer having a thickness of 4 μm (the thickness of the region where the conductive particles are present) on the PET film was obtained. The density of the conductive particles at this time was about 7000pcs/mm²。

[ evaluation of the monodispersion ratio of conductive particles ]

For the first adhesive film, the monodispersity of the conductive particles (the ratio at which the conductive particles exist in a state of being spaced from other adjacent conductive particles (monodispersed state)) was evaluated. The monodispersion rate is more than 70%.

The monodispersion ratio was determined by using a monodispersion ratio (%) (2500 μm)²Number of conductive particles in a monodisperse state/2500 μm²The number of conductive particles in (c) × 100. In the actual measurement of the conductive particles, observation was performed at a magnification of 200 times using a metal microscope.

[ production of second adhesive film ]

The varnish of the thermosetting composition 1 was coated on a PET film having a thickness of 50 μm using a coating apparatus. Subsequently, hot air drying was performed at 70 ℃ for 3 minutes to form a second adhesive layer (layer formed of the thermosetting composition 1) having 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 was obtained.

[ production of adhesive film for Circuit connection ]

The first adhesive film and the second adhesive film were laminated together with a PET film as a base material by a roll laminator while heating at 40 ℃. At this time, the PET film on the second adhesive film side is peeled off, thereby producing an adhesive film for circuit connection having a laminated structure in which the PET film, the first adhesive layer, and the second adhesive layer are laminated in this order.

The thickness of the first adhesive layer of the produced adhesive film for circuit connection was measured by the method. Specifically, the measurement was performed by the following method. An adhesive film was sandwiched between two sheets of glass (thickness: about 1 mm), and after casting with a resin composition formed of 100g of bisphenol a type epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10g of a curing agent (trade name: Epomount curing agent, manufactured by Refine Tec ltd.), cross-sectional grinding was performed using a grinder, and the thickness of the first adhesive layer located at the partition portion of the adjacent conductive particles was measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Corporation). The thickness of the first adhesive layer was 2 μm.

[ production of Circuit connection Structure ]

With the prepared adhesive film for circuit connection, a thin film electrode (height:

) The glass substrate with a thin film electrode (manufactured by geomantec co., ltd.) of (1) was manufactured using a thermocompression bonding apparatus (heating method: a circuit connection structure (connection structure) was fabricated by heating and pressing a contact heat type (manufactured by TAIYO KIKAI Ltd.) at 170 ℃ and 6MPa for 4 seconds to connect the circuit connection structure over a width of 1 mm. In connection, first, the circuit connection adhesive film is attached to the COF substrate from the second adhesive layer side, and after the separator is peeled off, the COF substrate is heated and pressed so as to face the glass substrate.

[ rating of Circuit connection Structure ]

The obtained circuit connection structure was measured for the connection resistance value between the opposing electrodes immediately after connection by a multimeter. The connection resistance value was determined as an average value of the resistance between the opposing electrodes at 16 points.

Then, 10 μm × 200 μm (═ 2000 μm) was measured on each electrode²) The average value of 20 columns was obtained as the number of captured regions. The results are shown in table 3.

Then, the particle dispersibility after mounting was observed using a microscope. The evaluation of the state before mounting was 1, the evaluation of no mounting was 3, and the intermediate evaluation was 2.

1 and 2 are levels that are practically unproblematic.

(reference example 1)

Evaluation was performed in the same manner as in example 1 except that an adhesive film for circuit connection having a laminated structure in which the first adhesive layer, the second adhesive layer, and the PET film were laminated in this order was produced by laminating the first adhesive layer and the second adhesive layer and then peeling off the PET film on the side of the first adhesive layer. In connection, first, the circuit connection adhesive film is attached to the COF substrate from the first adhesive layer side, and after the separator is peeled off, the COF substrate is heated and pressed so as to face the glass substrate. The results are shown in table 3.

(examples 2 and 3)

An adhesive film for circuit connection and a circuit connection structure were produced in the same manner as in example 1, except that the thickness of the first adhesive layer was changed to 1.5 μm and 3.0 μm. The circuit connection structure thus produced was evaluated in the same manner as in example 1. The results are shown in table 3. The monodispersion ratio of the conductive particles in the first binder layer is 70% or more.

[ Table 3]

	Example 1	Reference example 1	Example 2	Example 3
					Thickness of first adhesive layer (μm)	2.0	2.0	1.5	3.0
Connecting resistance (omega) (just after connection)	1.9	2.0	1.8	2.0
					Mean value of conductive particle trapping number	13.6	11.7	13.5	13.9
Flowability of the particles	1	3	1	1

It is known that: in comparison with reference example 1, when the circuit-connecting adhesive film obtained in example 1 was first attached to a COF substrate and mounted, the number of conductive particles captured increased, and the fluidity of the particles was also suppressed.

Description of the symbols

1-circuit connecting structure, 2-first circuit member, 3-second circuit member, 6-first circuit electrode, 8-second circuit electrode, 11-adhesive film for circuit connection, 12, 15-supporting film (release film), 13-first adhesive layer, 14-second adhesive layer, P-conductive particles, W-adhesive paste.

Claims

1. An adhesive film for circuit connection, comprising: a releasable supporting film, a first adhesive layer containing conductive particles provided on the supporting film, and a second adhesive layer laminated on the first adhesive layer,

the thickness of the first adhesive layer is 0.1 to 1.0 times the average particle diameter of the conductive particles.

2. The adhesive film for circuit connection according to claim 1,

the first adhesive layer is formed from a cured product of a first curable composition,

the first curable composition contains a radically polymerizable compound having a radically polymerizable group.

3. The adhesive film for circuit connection according to claim 1 or 2, wherein,

the second adhesive layer is formed from a second curable composition,

the second curable composition contains a radically polymerizable compound having a radically polymerizable group.

4. A method of manufacturing a circuit connection structure, comprising:

a step of interposing the first adhesive layer and the second adhesive layer of the adhesive film for circuit connection according to any one of claims 1 to 3 between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermocompression-bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

5. The method of manufacturing a circuit connection structure according to claim 4,

the first circuit member has a flexible substrate,

the method for manufacturing the circuit connection structure includes: and attaching the circuit-connecting adhesive film to the first circuit member so that the second adhesive layer is in contact with the first circuit member.

6. An adhesive film storage kit comprising: the adhesive film for circuit connection according to any one of claims 1 to 3 and a housing member housing the adhesive film,

the housing member has a visible portion capable of externally viewing the interior of the housing member,

the visible part has a transmittance of 10% or less for light having a wavelength of 365 nm.