Adhesive film for circuit connection, and circuit connection structure and method for producing the same

Abstract

To provide an adhesive film for circuit connection capable of improving a capture rate of conductive particles between opposing electrodes of a circuit connection structure and reducing connection resistance even when mounted at a low pressure.SOLUTION: The adhesive film 10 for circuit connection includes a first adhesive layer 1 containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component, and a second adhesive layer 2 provided on the first adhesive layer 1 and containing a second thermosetting resin component. The thickness of the first adhesive layer 1 is 5 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an adhesive film for circuit connection, as well as a circuit connection structure and a method for producing the same. [Background technology]

[0002] Conventionally, liquid crystal display panels, organic EL panels, etc. have been used as various display means in televisions, PC monitors, mobile phones, smartphones, etc. In these display devices, from the viewpoints of fine pitch, light weight and thinness, so-called COG (chip on glass) mounting is adopted, in which a driving IC is mounted directly on the glass substrate of the display panel.

[0003] In a liquid crystal display panel employing the COG mounting method, for example, a semiconductor element such as a liquid crystal driving IC is connected to a transparent substrate (such as a glass substrate) having a plurality of transparent electrodes (such as ITO (indium tin oxide)). An anisotropically conductive circuit connection adhesive film, in which conductive particles are dispersed in the adhesive, is used as an adhesive material for connecting the electrode terminals of the semiconductor element to the transparent electrodes. For example, when a liquid crystal driving IC is mounted as the semiconductor element, the liquid crystal driving IC has a plurality of electrode terminals on its mounting surface corresponding to the transparent electrodes, and the electrode terminals and the transparent electrodes are connected by thermocompression bonding the liquid crystal driving IC onto the transparent substrate via the anisotropically conductive circuit connection adhesive film, thereby obtaining a circuit connection structure.

[0004] In recent years, displays with curved surfaces (flexible displays) have been proposed. In such flexible displays, flexible plastic substrates (such as polyimide substrates) are used instead of glass substrates, and various electronic components such as driving ICs are also mounted on the plastic substrates. As a mounting method for such displays, chip-on-plastic (COP) mounting, which uses an anisotropically conductive circuit-connecting adhesive film, has been investigated (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2016-054288 Summary of the Invention [Problem to be solved by the invention]

[0006] Flexible displays used in organic electroluminescence (EL) panels and the like primarily use polyimide substrates with circuit electrodes that have a titanium layer on the outermost surface. The inventors' research has revealed that circuit electrodes with a titanium layer on the outermost surface have an oxide coating on their surfaces, and that the higher the resin fluidity of the circuit-connecting adhesive film, the lower the connection resistance between circuits. However, high resin fluidity also means that conductive particles are more likely to flow, which can easily cause short circuits between adjacent circuits.

[0007] On the other hand, for example, studies have been conducted to suppress the fluidity of conductive particles by curing the adhesive of the circuit connection adhesive film with heat or light, but in this case, the expulsion of the resin in the adhesive is also reduced, which is presumed to increase the connection resistance.

[0008] The resin removal itself can be achieved, in principle, by mounting at high pressure. However, in this case, an adhesive layer such as a pressure-sensitive resin and a film such as PET (polyethylene terephthalate) or PEN (polyethylene naphthalate) are usually placed on the underside of the polyimide substrate. This can lead to stress accumulation in the polyimide substrate and the circuit electrodes, which have a titanium layer on the outermost surface, causing cracks and circuit breaks. Therefore, flexible displays are preferably mounted at low pressure (e.g., an area-equivalent pressure of 0.1 to 50 MPa for bump electrodes). Circuit-connecting adhesive films used in COP mounting are required to suppress the fluidity of conductive particles and the increase in connection resistance under low-pressure mounting.

[0009] Therefore, the main object of the present disclosure is to provide an adhesive film for circuit connection that can improve the capture rate of conductive particles between opposing electrodes of a circuit connection structure and reduce connection resistance, even when mounted at low pressure. [Means for solving the problem]

[0010] One aspect of the present disclosure relates to an adhesive film for circuit connection. The adhesive film for circuit connection includes a first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component, and a second adhesive layer containing a second thermosetting resin component disposed on the first adhesive layer. The thickness of the first adhesive layer is 5 μm or less. With this adhesive film for circuit connection, the curing of the photocurable resin component can suppress the fluidity of the conductive particles during circuit connection while preventing a decrease in the removability of the resin. Furthermore, by having a thickness of 5 μm or less, the fluidity of the conductive particles during circuit connection can be further suppressed. Therefore, even when mounted at low pressure, it is possible to improve the capture rate of conductive particles between opposing electrodes of a circuit connection structure and reduce connection resistance. Such an adhesive film for circuit connection is suitable for COP mounting.

[0011] The first thermosetting resin component and the second thermosetting resin component may contain a cationic polymerizable compound and a thermal cationic polymerization initiator, and the photocurable resin component may contain a radically polymerizable compound. In this case, the first thermosetting resin component and the second thermosetting resin component have cationic curability, and the photocurable resin component has radical curability. According to the inventors' studies, such a combination of the first thermosetting resin component and the second thermosetting resin component with the photocurable resin component tends to provide better connection resistance than, for example, a combination in which all the curable resin components have cationic curability. The inventors of the present disclosure speculate that the reason for this effect is as follows: That is, if all the curable resin components contain cationic curable components, for example, cationic active species may remain in the first adhesive layer when forming a cured product of the photocurable resin component. These cationic active species may accelerate the curing reaction of the second thermosetting resin component in the second adhesive layer, reducing the resin's removability. Therefore, if the photocurable resin component has radical curing properties, no cationic active species are generated when the photocurable resin component is cured, and therefore the progress of the curing reaction of the second thermosetting resin component in the second adhesive layer can be suppressed, and it is expected that the decrease in resin expulsion ability will be suppressed and connection resistance will be reduced.

[0012] The cationically polymerizable compound may be at least one selected from the group consisting of an oxetane compound and an alicyclic epoxy compound. The thermal cationic polymerization initiator may be a salt compound having an anion containing boron as a constituent element.

[0013] The adhesive film for circuit connection may further include a third adhesive layer containing a third thermosetting resin component provided on the side of the first adhesive layer opposite the second adhesive layer. The third thermosetting resin component may include a cationically polymerizable compound and a thermal cationic polymerization initiator.

[0014] Another aspect of the present disclosure relates to a method for manufacturing a circuit connection structure, which includes the steps of interposing the above-mentioned adhesive film for circuit connection 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.

[0015] Another aspect of the present disclosure relates to a circuit connection structure. The circuit connection structure includes a first circuit member having a first electrode, a second circuit member having a second electrode, and a circuit connection part disposed between the first and second circuit members and electrically connecting the first and second electrodes to each other. The circuit connection part includes a cured product of the above-mentioned adhesive film for circuit connection. [Effects of the Invention]

[0016] The present disclosure discloses an adhesive film for circuit connection that can improve the capture rate of conductive particles between opposing electrodes of a circuit connection structure and reduce connection resistance, even when mounted at low pressure. Such an adhesive film for circuit connection can be suitably used for COP mounting. The present disclosure also discloses a circuit connection structure using such an adhesive film for circuit connection and a method for manufacturing the same. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connection. [Figure 2] FIG. 2 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. [Figure 3] 3A and 3B are schematic cross-sectional views showing one embodiment of a method for producing a circuit connection structure, in which Fig. 3A and Fig. 3B are schematic cross-sectional views showing each step. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent parts will be denoted by the same reference numerals, and duplicated explanations will be omitted. Note that the present disclosure is not limited to the following embodiments.

[0019] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the Examples. Furthermore, individually described upper and lower limits can be arbitrarily combined. In a numerical range described as "A to B," the numerical values ​​A and B at both ends are included as the lower and upper limits, respectively, in the numerical range. In this specification, for example, the expression "10 or more" means "10" and "a number greater than 10," and this also applies when the numerical values ​​differ. Furthermore, for example, the expression "10 or less" means "10" and "a number less than 10," and this also applies when the numerical values ​​differ. Furthermore, in this specification, "(meth)acrylate" means at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl" and "(meth)acrylic acid." Furthermore, "A or B" may contain either A or B, or may contain both. Furthermore, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0020] [Adhesive film for circuit connection] Fig. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connection. The adhesive film 10 for circuit connection shown in Fig. 1 (hereinafter sometimes simply referred to as "adhesive film 10") comprises a first adhesive layer 1 containing conductive particles 4 and an adhesive component 5 including a cured product of a photocurable resin component and a (first) thermosetting resin component, and a second adhesive layer 2 provided on the first adhesive layer 1 and containing a (second) thermosetting resin component. The adhesive film 10 may have a first region formed from the first adhesive film (first adhesive layer 1) and a second region formed from the second adhesive film (second adhesive layer 2) provided adjacent to the first region. In other words, the adhesive film 10 can be said to have a first region containing conductive particles 4 and an adhesive component 5 including a cured product of a photocurable resin component and a (first) thermosetting resin component, and a second region adjacent to the first region containing a (second) thermosetting resin component.

[0021] The adhesive film 10 has conductive particles 4 dispersed in the first adhesive layer 1. Therefore, the adhesive film 10 can be an anisotropically conductive adhesive film for circuit connection (anisotropically conductive adhesive film). The adhesive film 10 can be interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and can be used to electrically connect the first electrode and the second electrode to each other by thermocompression bonding the first circuit member and the second circuit member.

[0022] <First adhesive layer> The first adhesive layer 1 contains conductive particles 4 (hereinafter sometimes referred to as "component (A)"), a cured product of a photocurable resin component (hereinafter sometimes referred to as "component (B)"), and a thermosetting resin component (hereinafter sometimes referred to as "component (C)"). The first adhesive layer 1 can be obtained, for example, by irradiating a composition layer made of a composition containing components (A), (B), and (C) with light energy to polymerize the components contained in component (B) and cure component (B). The first adhesive layer 1 contains component (A), a cured product of component (B), and an adhesive component 5 containing component (C). The cured product of component (B) may be a cured product obtained by completely curing component (B) or a cured product obtained by partially curing component (B). Component (C) is a component that can flow during circuit connection, such as an uncured curable resin component.

[0023] (A) Component: Conductive particles Component (A) is not particularly limited as long as it is a conductive particle, and may be, for example, a metal particle composed of a metal such as Au, Ag, Pd, Ni, Cu, or solder, or a conductive carbon particle composed of conductive carbon. Component (A) may also be a coated conductive particle comprising a core containing non-conductive glass, ceramic, or plastic (e.g., polystyrene), and a coating layer containing the metal or conductive carbon that coats the core. Among these, component (A) is preferably a metal particle formed of a heat-fusible metal, or a coated conductive particle comprising a core containing plastic and a coating layer containing a metal or conductive carbon that coats the core. Such coated conductive particles can be easily deformed by heating or applying pressure to a cured product of the thermosetting resin component. Therefore, when electrically connecting electrodes, the contact area between the electrodes and component (A) can be increased, thereby further improving the conductivity between the electrodes.

[0024] Component (A) may be an insulating coated conductive particle comprising the above-mentioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer containing an insulating material such as resin that coats the surface of the particles. When component (A) is an insulating coated conductive particle, even if the content of component (A) is high, the particle surface has an insulating layer, which can prevent short circuits caused by contact between components (A) and can also improve insulation between adjacent electrode circuits. Component (A) can be one of the above-mentioned various conductive particles, or a combination of two or more of them.

[0025] The maximum particle size of component (A) must be smaller than the minimum electrode spacing (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (A) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (A) may be 20 μm or less, 10 μm or less, or 5 μm or less. In this specification, the particle size of 300 random conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is defined as the maximum particle size of component (A). Note that when component (A) has protrusions or is not spherical, the particle size of component (A) is defined as the diameter of a circle circumscribing the conductive particle in an SEM image.

[0026] The average particle size of component (A) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more from the viewpoint of excellent dispersibility and conductivity. The average particle size of component (A) may be 20 μm or less, 10 μm or less, or 5 μm or less from the viewpoint of excellent dispersibility and conductivity. In this specification, the particle size of 300 random conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the particle sizes obtained is defined as the average particle size.

[0027] Component (A) is preferably uniformly dispersed in first adhesive layer 1. From the viewpoint of obtaining a stable connection resistance, the particle density of component (A) in adhesive film 10 is 100 particles / mm 2 More than 1000 pieces / mm 2More than 3000 pieces / mm 2 or more than 5000 pieces / mm 2 The particle density of component (A) in adhesive film 10 may be 100,000 particles / mm 3 or more from the viewpoint of improving the insulating properties between adjacent electrodes. 2 Below, 70000 pieces / mm 2 Below, 50000 pieces / mm 2 or less than 30,000 pieces / mm 2 It may be the following:

[0028] The content of component (A) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of further improving conductivity. The content of component (A) may be 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the first adhesive layer, from the viewpoint of easily suppressing short circuits. When the content of component (A) is within the above range, the effects of the present disclosure tend to be significantly exhibited. The content of component (A) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0029] (B) Component: Photocurable resin component Component (B) is not particularly limited as long as it is a resin component that cures upon irradiation with light, but when component (C) is a resin component having cation curability, component (B) may be a resin component having radical curability from the viewpoint of achieving better connection resistance. Component (B) may contain, for example, a radically polymerizable compound (hereinafter sometimes referred to as "component (B1)") and a photoradical polymerization initiator (hereinafter sometimes referred to as "component (B2)"). Component (B) may be a component consisting of components (B1) and (B2).

[0030] Component (B1): radical polymerizable compound Component (B1) is a compound that polymerizes due to radicals generated from component (B2) upon irradiation with light (e.g., ultraviolet light). Component (B1) may be either a monomer or a polymer (or oligomer) formed by polymerization of one or more monomers. Component (B1) may be used singly or in combination.

[0031] Component (B1) is a compound having a radically polymerizable group that reacts with radicals. Examples of the radically polymerizable group include (meth)acryloyl, vinyl, allyl, styryl, alkenyl, alkenylene, and maleimide groups. The number of radically polymerizable groups (functional groups) in component (B1) may be 2 or more, from the viewpoints of easily achieving a desired melt viscosity after polymerization, further improving the effect of reducing connection resistance, and providing superior connection reliability, and may be 10 or less, from the viewpoint of suppressing cure shrinkage during polymerization. Furthermore, in order to balance crosslink density and cure shrinkage, in addition to compounds having the number of radically polymerizable groups within the above range, compounds having the number of radically polymerizable groups outside the above range may be used.

[0032] From the viewpoint of suppressing the flow of the conductive particles, the component (B1) may contain, for example, a polyfunctional (difunctional or higher) (meth)acrylate. The polyfunctional (difunctional or higher) (meth)acrylate may be a difunctional (meth)acrylate, and the difunctional (meth)acrylate may be a difunctional aromatic (meth)acrylate.

[0033] Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, and 1,3-butane. aliphatic (meth)acrylates such as diol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate;Aromatic (meth)acrylates such as ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, ethoxylated propoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, propoxylated bisphenol F di(meth)acrylate, ethoxylated propoxylated bisphenol F di(meth)acrylate, ethoxylated fluorene di(meth)acrylate, propoxylated fluorene di(meth)acrylate, and ethoxylated propoxylated fluorene di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, and pentaerythritol Aliphatic (meth)acrylates such as pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated propoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexa(meth)acrylate; aromatic epoxy (meth)acrylates such as bisphenol-type epoxy (meth)acrylate, phenol novolac-type epoxy (meth)acrylate, and cresol novolac-type epoxy (meth)acrylate;

[0034] The content of the polyfunctional (difunctional or higher) (meth)acrylate may be, for example, 40 to 100 mass%, 50 to 100 mass%, or 60 to 100 mass%, based on the total mass of the (B1) component, from the viewpoint of achieving both the effect of reducing connection resistance and the suppression of particle flow.

[0035] The component (B1) may further contain a monofunctional (meth)acrylate in addition to a polyfunctional (difunctional or higher) (meth)acrylate. Examples of the monofunctional (meth)acrylate include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octylheptyl (meth)acrylate, and nonyl (meth)acrylate. Decyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, mono(2-(meth)acryloyloxy) Aliphatic (meth)acrylates such as diethyl succinate; benzyl (meth)acrylate, phenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, 1-naphthoxyethyl (meth)acrylate, 2-naphthoxyethyl (meth)acrylate, phenoxypolyether aromatic (meth)acrylates such as ethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate, and 2-hydroxy-3-(2-naphthoxy)propyl (meth)acrylate;Examples of such acrylates include (meth)acrylates having an epoxy group such as glycidyl (meth)acrylate, (meth)acrylates having an alicyclic epoxy group such as 3,4-epoxycyclohexylmethyl (meth)acrylate, and (meth)acrylates having an oxetanyl group such as (3-ethyloxetan-3-yl)methyl (meth)acrylate.

[0036] The content of the monofunctional (meth)acrylate may be, for example, 0 to 60 mass %, 0 to 50 mass %, or 0 to 40 mass % based on the total mass of the component (B1).

[0037] The cured product of component (B) may have a polymerizable group that reacts by a mechanism other than a radical. The polymerizable group that reacts by a mechanism other than a radical may be, for example, a cationically polymerizable group that reacts by a cation. Examples of the cationically polymerizable group include epoxy groups such as glycidyl groups, alicyclic epoxy groups such as epoxycyclohexylmethyl groups, and oxetanyl groups such as ethyloxetanylmethyl groups. A cured product of component (B) having a polymerizable group that reacts by a mechanism other than a radical can be introduced by using, as component (B), a (meth)acrylate having a polymerizable group that reacts by a mechanism other than a radical, such as a (meth)acrylate having an epoxy group, a (meth)acrylate having an alicyclic epoxy group, or a (meth)acrylate having an oxetanyl group. The mass ratio of the (meth)acrylate having a polymerizable group that reacts by other than radicals to the total mass of the component (B1) (mass (charge amount) of the (meth)acrylate having a polymerizable group that reacts by other than radicals / total mass (charge amount) of the component (B1)) may be, for example, 0 to 0.7, 0 to 0.5, or 0 to 0.3, from the viewpoint of improving reliability.

[0038] The component (B1) may contain other radically polymerizable compounds in addition to polyfunctional (difunctional or higher) and monofunctional (meth)acrylates. Examples of other radically polymerizable compounds include maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, and nadimide derivatives. The content of other radically polymerizable compounds may be, for example, 0 to 40% by mass based on the total mass of the component (B1).

[0039] Component (B2): Photoradical polymerization initiator The component (B2) is a photopolymerization initiator that generates radicals when irradiated with light having a wavelength in the range of 150 to 750 nm, preferably light having a wavelength in the range of 254 to 405 nm, and more preferably light having a wavelength of 365 nm (e.g., ultraviolet light). The component (B2) may be used alone or in combination.

[0040] The component (B2) decomposes under light to generate free radicals. That is, the component (B2) is a compound that generates radicals upon application of external light energy. The component (B2) may be a compound 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 benzyl dimethyl ketal structure, an α-hydroxyalkylphenone structure, or the like. The component (B2) may be used alone or in combination. From the viewpoints of easily obtaining a desired melt viscosity and of achieving a superior effect of reducing connection resistance, the component (B2) may be a compound having at least one structure selected from the group consisting of an oxime ester structure, an α-aminoalkylphenone structure, and an acylphosphine oxide structure.

[0041] Specific examples of compounds having an oxime ester structure include 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-o-benzoyloxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime, 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(o-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime), and the like.

[0042] Specific examples of compounds having an α-aminoalkylphenone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-morpholinophenyl)-butanone-1, and the like.

[0043] Specific examples of compounds having an acylphosphine oxide structure include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0044] The content of the (B2) component may be, for example, 0.1 to 10 parts by mass, 0.3 to 7 parts by mass, or 0.5 to 5 parts by mass per 100 parts by mass of the (B1) component, from the viewpoint of suppressing the flow of the conductive particles.

[0045] The content of the cured product of component (B) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of suppressing the flow of conductive particles. The content of the cured product of component (B) may be 50% by mass or less, 40% by mass or less, or 30% by mass or less, based on the total mass of the first adhesive layer, from the viewpoint of exhibiting low resistance in low-pressure mounting. When the content of the cured product of component (B) is within the above range, the effects of the present disclosure tend to be significantly exhibited. The content of component (B) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0046] (C) Component: Thermosetting resin component Component (C) is not particularly limited as long as it is a resin component that cures when heated. However, when component (B) is a resin component having radical curing properties, component (C) may be a resin component having cation curing properties in order to achieve superior connection resistance. Component (C) may contain, for example, a cationically polymerizable compound (hereinafter sometimes referred to as "component (C1)") and a thermal cationic polymerization initiator (hereinafter sometimes referred to as "component (C2)"). Component (C) may consist of components (C1) and (C2). The terms "first thermosetting resin component," "second thermosetting resin component," and "third thermosetting resin component" refer to the thermosetting resin components contained in the first adhesive layer, the second adhesive layer, and the third adhesive layer, respectively. The components contained in the first thermosetting resin component, the second thermosetting resin component, and the third thermosetting resin component (e.g., component (C1), component (C2), etc.) and their contents may be the same or different.

[0047] Component (C1): Cationic polymerizable compound Component (C1) is a compound that crosslinks by reacting with component (C2) under heat. Component (C1) refers to a compound that does not have a radically polymerizable group that reacts with a radical, and component (C1) is not included in component (B1). From the viewpoint of further improving the effect of reducing connection resistance and achieving more excellent connection reliability, component (C1) may be, for example, at least one compound selected from the group consisting of an oxetane compound and an alicyclic epoxy compound. Component (C1) may be used alone or in combination. From the viewpoint of easily obtaining the desired melt viscosity, component (C1) preferably contains both at least one oxetane compound and at least one alicyclic epoxy compound.

[0048] The oxetane compound as component (C1) can be used without any particular limitation as long as it has an oxetanyl group and does not have a radically polymerizable group. Commercially available oxetane compounds include, for example, ETERNACOLL OXBP (trade name: 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, manufactured by Ube Industries, Ltd.), OXSQ, OXT-121, OXT-221, OXT-101, and OXT-212 (trade names, manufactured by Toagosei Co., Ltd.). These compounds may be used alone or in combination.

[0049] The alicyclic epoxy compound as component (C1) can be used without particular limitation as long as it has an alicyclic epoxy group (e.g., an epoxycyclohexyl group) and does not have a radical polymerizable group. Commercially available alicyclic epoxy compounds include, for example, EHPE3150, EHPE3150CE, Celloxide 8010, Celloxide 2021P, and Celloxide 2081 (trade names, manufactured by Daicel Corporation). These compounds may be used alone or in combination.

[0050] Component (C2): thermal cationic polymerization initiator Component (C2) is a thermal polymerization initiator that generates an acid or the like when heated to initiate polymerization. Component (C2) may be a salt compound composed of a cation and an anion. Component (C2) is, for example, BF4 - , BR4 - (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups), PF6 - , SbF6 - , AsF6 - Examples of the anion include onium salts such as sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, and anilinium salts, each of which has an anion such as any of the above. These may be used alone or in combination.

[0051] From the viewpoint of storage stability, the component (C2) is, for example, an anion containing boron as a constituent element, i.e., BF4 - or BR4 - (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups). An anion containing boron as a constituent element may be a salt compound having BR4 - and more specifically, tetrakis(pentafluorophenyl)borate.

[0052] The onium salt as component (C2) may be, for example, an anilinium salt, since it is resistant to substances that can inhibit cationic curing. Examples of anilinium salt compounds include N,N-dialkylanilinium salts such as N,N-dimethylanilinium salt and N,N-diethylanilinium salt.

[0053] The component (C2) may be an anilinium salt having an anion containing boron as a constituent element. Commercially available products of such salt compounds include CXC-1821 (trade name, manufactured by King Industries).

[0054] The content of the (C2) component may be, for example, 0.1 to 20 parts by mass, 1 to 18 parts by mass, 3 to 15 parts by mass, or 5 to 12 parts by mass per 100 parts by mass of the (C1) component, from the viewpoint of ensuring the formability and curability of the adhesive film for forming the first adhesive layer.

[0055] The content of the (C) component may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of ensuring the curability of the adhesive film for forming the first adhesive layer. The content of the (C) component may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the first adhesive layer, from the viewpoint of ensuring the formability of the adhesive film for forming the first adhesive layer. When the content of the (C) component is within the above range, the effects of the present disclosure tend to be significantly exhibited. The content of the (C) component in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0056] [Other ingredients] The first adhesive layer 1 may further contain other components in addition to the component (A), the cured product of the component (B), and the component (C). Examples of other components include a thermoplastic resin (hereinafter sometimes referred to as "component (D)"), a coupling agent (hereinafter sometimes referred to as "component (E)"), and a filler (hereinafter sometimes referred to as "component (F)").

[0057] Examples of component (D) include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, acrylic rubber, and epoxy resin (solid at 25°C). These may be used alone or in combination. When a composition containing components (A), (B), and (C) further contains component (D), a composition layer (and further the first adhesive layer 1) can be easily formed from the composition. Among these, component (D) may be, for example, a phenoxy resin. The content of component (D) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, and 70% by mass or less, 50% by mass or less, or 30% by mass or less, based on the total mass of the first adhesive layer. The content of component (D) in the composition or composition layer (based on the total mass of the composition or composition layer) may be within the above range.

[0058] Examples of the (E) component include silane coupling agents having an organic functional group such as a (meth)acryloyl group, a mercapto group, an amino group, an imidazole group, or an epoxy group; silane compounds such as tetraalkoxysilane; tetraalkoxytitanate derivatives; and polydialkyltitanate derivatives. These may be used alone or in combination. The inclusion of the (E) component in the first adhesive layer 1 can further improve adhesion. The (E) component may be, for example, a silane coupling agent. The content of the (E) component may be 0.1 to 10% by mass, based on the total mass of the first adhesive layer. The content of the (E) component in the composition or composition layer (based on the total mass of the composition or composition layer) may be within the above-mentioned range.

[0059] Examples of the (F) component include non-conductive fillers (e.g., non-conductive particles). The (F) component may be either an inorganic filler or an organic filler. Examples of inorganic fillers include inorganic fine particles such as metal oxide fine particles, such as silica fine particles, alumina fine particles, silica-alumina fine particles, titania fine particles, and zirconia fine particles; and metal nitride fine particles. Examples of organic fillers 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 may be used alone or in combination. The (F) component may be, for example, silica fine particles. The content of the (F) component may be 0.1 to 10% by mass, based on the total mass of the first adhesive layer. The content of the (F) component in the composition or composition layer (based on the total mass of the composition or composition layer) may be within the above-mentioned range.

[0060] [Other additives] The first adhesive layer 1 may further contain other additives such as softeners, accelerators, anti-degradants, colorants, flame retardants, and thixotropic agents. The content of the other additives may be, for example, 0.1 to 10 mass % based on the total mass of the first adhesive layer. The content of the other additives in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0061] The thickness d1 of the first adhesive layer 1 is 5 μm or less, and may be, for example, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, or 2.5 μm or less. By having the thickness d1 of the first adhesive layer 1 be 5 μm or less, the fluidity of the conductive particles during circuit connection can be further suppressed. Therefore, even when mounted at low pressure, it is possible to improve the capture rate of the conductive particles between the opposing electrodes of the circuit connection structure and reduce the connection resistance. The thickness d1 of the first adhesive layer 1 may be, for example, 0.1 μm or more or 0.7 μm or more. The thickness d1 of the first adhesive layer 1 can be determined, for example, by the method described in the Examples. 1, when a portion of the conductive particles 4 is exposed from the surface of the first adhesive layer 1 (for example, protruding toward the second adhesive layer 2), the distance from the surface 2a of the first adhesive layer 1 opposite the second adhesive layer 2 to the boundary S between the first adhesive layer 1 and the second adhesive layer 2 located in the space between adjacent conductive particles 4,4 (the distance indicated by d1 in FIG. 1) is the thickness of the first adhesive layer 1, and the exposed portions of the conductive particles 4 are not included in the thickness of the first adhesive layer 1. The length of the exposed portions of the conductive particles 4 may be, for example, 0.1 μm or more and 5 μm or less.

[0062] <Second adhesive layer> The second adhesive layer 2 contains component (C). The components (C1) and (C2) used in component (C) (i.e., the second thermosetting resin component) in the second adhesive layer 2 are similar to the components (C1) and (C2) used in component (C) (i.e., the first thermosetting resin component) in the first adhesive layer 1, and therefore a detailed description thereof will be omitted here. The second thermosetting resin component may be the same as or different from the first thermosetting resin component.

[0063] The content of component (C) may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the second adhesive layer, from the viewpoint of maintaining reliability. The content of component (C) may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the second adhesive layer, from the viewpoint of preventing resin seepage problems in a reel, which is one embodiment of the supply form.

[0064] The second adhesive layer 2 may further contain other components and other additives than those in the first adhesive layer 1. Preferred embodiments of the other components and other additives are the same as those of the first adhesive layer 1.

[0065] The content of component (D) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, and may be 80% by mass or less, 60% by mass or less, or 40% by mass or less, based on the total mass of the second adhesive layer.

[0066] The content of the component (E) may be 0.1 to 10% by mass based on the total mass of the second adhesive layer.

[0067] The content of component (F) may be 1% by mass or more, 10% by mass or more, or 30% by mass or more, and may be 90% by mass or less, 70% by mass or less, or 50% by mass or less, based on the total mass of the second adhesive layer.

[0068] The content of the other additives may be, for example, 0.1 to 10% by mass based on the total mass of the second adhesive layer.

[0069] The thickness d2 of the second adhesive layer 2 may be appropriately set depending on the height of the electrodes of the circuit components to be bonded. The thickness d2 of the second adhesive layer 2 may be 5 μm or more or 7 μm or more, and 15 μm or less or 11 μm or less, from the viewpoint of being able to sufficiently fill the space between the electrodes and seal the electrodes, thereby obtaining better connection reliability. The thickness d2 of the second adhesive layer 2 can be determined, for example, by the method described in the Examples. Furthermore, when a portion of the conductive particles 4 is exposed from the surface of the first adhesive layer 1 (for example, protruding toward the second adhesive layer 2), the thickness of the second adhesive layer 2 is the distance (d2 in FIG. 1 ) from the surface 3 a of the second adhesive layer 2 opposite the first adhesive layer 1 side to the boundary S between the first adhesive layer 1 and the second adhesive layer 2, which is located in the space between adjacent conductive particles 4, 4.

[0070] The thickness of the adhesive film 10 (the sum of the thicknesses of all layers constituting the adhesive film 10; in Figure 1, the sum of the thickness d1 of the first adhesive layer 1 and the thickness d2 of the second adhesive layer 2) may be, for example, 5 μm or more or 8 μm or more, and may be 30 μm or less or 20 μm or less.

[0071] In the adhesive film 10, conductive particles 4 are dispersed in the first adhesive layer 1. Therefore, the adhesive film 10 is an anisotropically conductive adhesive film having anisotropic conductivity. The adhesive film 10 is interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and is used to electrically connect the first electrode and the second electrode to each other by thermocompression bonding the first circuit member and the second circuit member.

[0072] The adhesive film 10 can suppress the fluidity of conductive particles during circuit connection by curing the photocurable resin component, while also suppressing a decrease in the resin's removability. Furthermore, by setting the thickness of the first adhesive layer to 5 μm or less, the fluidity of conductive particles during circuit connection can be further suppressed. Therefore, even when mounting at low pressure, it is possible to improve the capture rate of conductive particles between opposing electrodes of the circuit connection structure and reduce connection resistance. Such an adhesive film 10 can be suitably used for COP mounting.

[0073] Although the adhesive film of the present embodiment has been described above, the present disclosure is not limited to the above embodiment.

[0074] The adhesive film may be, for example, composed of two layers, a first adhesive layer and a second adhesive layer, or may be composed of three or more layers, including two layers, a first adhesive layer and a second adhesive layer. The adhesive film may further include, for example, a third adhesive layer containing a (third) thermosetting resin component, provided on the side of the first adhesive layer opposite the second adhesive layer. The adhesive film may have a first region formed from the first adhesive film (first adhesive layer), and a third region formed from a third adhesive film (third adhesive layer) provided adjacent to the first region. It can also be said that the adhesive film further includes a third region containing a (third) thermosetting resin component, provided adjacent to the first region on the side opposite the second region.

[0075] The third adhesive layer contains component (C). Components (C1) and (C2) used in component (C) (i.e., the third thermosetting resin component) in the third adhesive layer are similar to components (C1) and (C2) used in component (C) (i.e., the first thermosetting resin component) in the first adhesive layer 1, and therefore detailed description thereof will be omitted here. The third thermosetting resin component may be the same as or different from the first thermosetting resin component. The third thermosetting resin component may be the same as or different from the second thermosetting resin component.

[0076] The content of component (C) may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the third adhesive layer, from the viewpoint of imparting good transferability and peel resistance. The content of component (C) may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the third adhesive layer, from the viewpoint of imparting good half-cut properties and blocking resistance (suppression of resin bleeding from the reel).

[0077] The third adhesive layer may further contain other components and other additives than those in the first adhesive layer 1. Preferred embodiments of the other components and other additives are the same as those of the first adhesive layer 1.

[0078] The content of component (D) may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and may be 80% by mass or less, 70% by mass or less, or 60% by mass or less, based on the total mass of the third adhesive layer.

[0079] The content of the component (E) may be 0.1 to 10% by mass based on the total mass of the third adhesive layer.

[0080] The content of component (F) may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 50% by mass or less, 40% by mass or less, or 30% by mass or less, based on the total mass of the third adhesive layer.

[0081] The content of the other additives may be, for example, 0.1 to 10% by mass based on the total mass of the third adhesive layer.

[0082] The thickness of the third adhesive layer may be appropriately set depending on the height of the electrodes of the circuit component to be bonded, etc. The thickness of the third adhesive layer may be 0.2 μm or more and 3.0 μm or less from the viewpoint of being able to sufficiently fill the space between the electrodes and seal the electrodes, thereby obtaining better connection reliability. The thickness of the third adhesive layer can be determined, for example, by the method described in the Examples.

[0083] Furthermore, although the adhesive film for circuit connection in the above embodiment is an anisotropic conductive adhesive film having anisotropic conductivity, the adhesive film for circuit connection may also be a conductive adhesive film that does not have anisotropic conductivity.

[0084] <Method of manufacturing an adhesive film for circuit connection> A method for producing an adhesive film for circuit connection according to one embodiment may include, for example, a first step of irradiating a composition layer made of a composition containing components (A), (B), and (C) (first thermosetting resin component) with light to form a first adhesive layer, and a second step of laminating a second adhesive layer containing component (C) (second thermosetting resin component) on the first adhesive layer. The first step may be a step of forming a first adhesive layer having a thickness of 5 μm or less. The production method may further include a third step of laminating a third adhesive layer containing component (C) (third thermosetting resin component) on the layer of the first adhesive layer opposite the second adhesive layer.

[0085] In the first step, for example, a composition containing components (A), (B), and (C), as well as other components and additives added as needed, is first dissolved or dispersed in an organic solvent by stirring, mixing, kneading, or the like to prepare a varnish composition. The varnish composition is then applied to a release-treated substrate using a knife coater, roll coater, applicator, comma coater, die coater, or the like, and the organic solvent is then volatilized by heating to form a composition layer composed of the composition on the substrate. The thickness of the final first adhesive layer (first adhesive film) can be adjusted by adjusting the amount of varnish composition applied. Subsequently, the composition layer composed of the composition is irradiated with light to cure component (B) in the composition layer, forming a first adhesive layer on the substrate. This first adhesive layer can be referred to as a first adhesive film.

[0086] The organic solvent used in preparing the varnish composition is not particularly limited as long as it has the property of being able to uniformly dissolve or disperse each component. Examples of such organic solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, etc. These organic solvents can be used alone or in combination of two or more. The stirring, mixing, or kneading in preparing the varnish composition can be carried out using, for example, a stirrer, a grinder, a three-roll mill, a ball mill, a bead mill, a homodisper, etc.

[0087] The substrate is not particularly limited as long as it has heat resistance sufficient to withstand the heating conditions required for volatilizing the organic solvent. Examples of such substrates include substrates (e.g., films) made of oriented polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, and liquid crystal polymer.

[0088] The heating conditions for volatilizing the organic solvent from the varnish composition applied to the substrate can be appropriately set depending on the organic solvent used, etc. The heating conditions may be, for example, 40 to 120°C for 0.1 to 10 minutes.

[0089] For the light irradiation 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. Light irradiation can be carried out using, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a metal halide lamp, an LED light source, etc. The cumulative light amount of the light irradiation can be set appropriately, but is, for example, 500 to 3000 mJ / cm. 2 It may be.

[0090] The second step is a step of laminating a second adhesive layer on the first adhesive layer. In the second step, for example, a second adhesive layer is first formed on a substrate in the same manner as the first step, except that component (C) and other components and additives added as needed are used and light irradiation is not performed, to obtain a second adhesive film. Next, the first adhesive film and the second adhesive film are bonded together to laminate the second adhesive layer on the first adhesive layer. In addition, in the second step, for example, a varnish composition obtained using component (C) and other components and additives added as needed is applied to the first adhesive layer, and the organic solvent is then volatilized to laminate the second adhesive layer on the first adhesive layer.

[0091] Examples of methods for bonding the first adhesive film and the second adhesive film include hot pressing, roll lamination, vacuum lamination, etc. Lamination can be carried out under temperature conditions of 0 to 80°C, for example.

[0092] The third step is a step of laminating a third adhesive layer on the layer of the first adhesive layer opposite the second adhesive layer. In the third step, for example, first, a third adhesive layer is formed on a substrate in the same manner as in the second step to obtain a third adhesive film. Next, the third adhesive layer can be laminated on the layer of the first adhesive layer opposite the second adhesive layer by laminating the third adhesive film on the side of the first adhesive film opposite the second adhesive layer. In addition, in the third step, for example, a varnish composition can be applied to the layer of the first adhesive layer opposite the second adhesive layer, and the organic solvent can be volatilized, similar to the second step, to laminate the second adhesive layer on the first adhesive layer. The lamination method and conditions are the same as in the second step.

[0093] <Circuit connection structure and method for manufacturing the same> A circuit connection structure using the above-mentioned adhesive film 10 for circuit connection as the circuit connecting material and a method for producing the same will now be described.

[0094] Fig. 2 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. As shown in Fig. 2, a circuit connection structure 20 includes a first circuit board 11 and a first circuit member 13 having a first electrode 12 formed on a main surface 11a of the first circuit board 11, a second circuit board 14 and a second circuit member 16 having a second electrode 15 formed on a main surface 14a of the second circuit board 14, and a circuit connection portion 17 disposed between the first circuit member 13 and the second circuit member 16 and electrically connecting the first electrode 12 and the second electrode 15 to each other.

[0095] The first circuit member 13 and the second circuit member 16 may be the same or different. The first circuit member 13 and the second circuit member 16 may be a glass or plastic substrate on which electrodes are formed, a printed wiring board, a ceramic wiring board, a flexible wiring board, an IC chip, or the like. The first circuit board 11 and the second circuit board 14 may be formed from an inorganic material such as a semiconductor, glass, or ceramic, an organic material such as polyimide or polycarbonate, or a composite material such as glass / epoxy. Among these, since the above-mentioned adhesive film 10 for circuit connection can be suitably used for COP mounting, the first circuit member 13 may be a plastic substrate made of an organic material such as polyimide, polycarbonate, polyethylene terephthalate, or cycloolefin polymer, and the second circuit board 14 may be an IC chip, for example.

[0096] The first electrode 12 and the second electrode 15 may be electrodes containing metals such as gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, and titanium, or oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium zinc oxide (IGZO). The first electrode 12 and the second electrode 15 may be electrodes formed by laminating two or more of these metals, oxides, and the like. An electrode formed by laminating two or more of these metals, oxides, and the like may have two or more layers, or may have three or more layers. When the first circuit member 13 is a plastic substrate, the first electrode 12 may be an electrode having a titanium layer on its outermost surface. The first electrode 12 and the second electrode 15 may be circuit electrodes or bump electrodes. At least one of the first electrode 12 and the second electrode 15 may be a bump electrode. FIG. 2 shows an embodiment in which the first electrode 12 is a circuit electrode and the second electrode 15 is a bump electrode.

[0097] The circuit connection portion 17 includes a cured product of the adhesive film 10. The circuit connection portion 17 may be made of a cured product of the adhesive film 10. For example, the circuit connection portion 17 is located on the first circuit member 13 side in the direction in which the first circuit member 13 and the second circuit member 16 face each other (hereinafter referred to as the "facing direction") and has a first cured product region 18 consisting of a cured product of the component (B) and a cured product of the component (C) and the like other than the conductive particles 4 in the first adhesive layer; a second cured product region 19 located on the second circuit member 16 side in the facing direction and consisting of a cured product of the component (C) and the like in the second adhesive layer; and conductive particles 4 interposed at least between the first electrode 12 and the second electrode 15 to electrically connect the first electrode 12 and the second electrode 15 to each other. As shown in FIG. 2, the circuit connection portion 17 does not have to have two distinct regions between the first cured material region 18 and the second cured material region 19, but may have a single cured material region formed by a mixture of the cured material derived from the first adhesive layer and the cured material derived from the second adhesive layer.

[0098] Fig. 3 is a schematic cross-sectional view showing one embodiment of a method for manufacturing a circuit connection structure. Fig. 3(a) and Fig. 3(b) are schematic cross-sectional views showing each step. As shown in Fig. 3, the method for manufacturing a circuit connection structure 20 includes the steps of interposing the above-mentioned adhesive film 10 between a first circuit member 13 having a first electrode 12 and a second circuit member 16 having a second electrode 15, and thermocompression bonding the first circuit member 13 and the second circuit member 16 to electrically connect the first electrode 12 and the second electrode 15 to each other.

[0099] Specifically, as shown in FIG. 3(a), first, a first circuit member 13 including a first circuit board 11 and a first electrode 12 formed on the main surface 11a of the first circuit board 11, and a second circuit member 16 including a second circuit board 14 and a second electrode 15 formed on the main surface 14a of the second circuit board 14 are prepared.

[0100] Next, the first circuit member 13 and the second circuit member 16 are arranged so that the first electrode 12 and the second electrode 15 face each other, and the adhesive film 10 is placed between the first circuit member 13 and the second circuit member 16. For example, as shown in FIG. 3( a), the adhesive film 10 is laminated onto the first circuit member 13 so that the first adhesive layer 1 faces the main surface 11a of the first circuit board 11. Next, the second circuit member 16 is placed on the first circuit member 13 on which the adhesive film 10 has been laminated so that the first electrode 12 on the first circuit board 11 and the second electrode 15 on the second circuit board 14 face each other.

[0101] 3(b), the first circuit member 13 and the second circuit member 16 are heated while being pressed against each other in the thickness direction, thereby thermocompression-bonding the first circuit member 13 and the second circuit member 16. During this process, as indicated by the arrows in FIG. 3(b), the second adhesive layer 2 contains a flowable, uncured thermosetting component, so that it flows to fill the gaps between the second electrodes 15 and is cured by the heating. As a result, the first electrode 12 and the second electrode 15 are electrically connected to each other via the conductive particles 4, and the first circuit member 13 and the second circuit member 16 are bonded to each other, thereby obtaining the circuit connection structure 20 shown in FIG. 2. In the manufacturing method of the circuit connection structure 20 of this embodiment, the first adhesive layer 1 can be said to be a layer in which a portion of it has been hardened by light irradiation, so the conductive particles 4 are fixed in the first adhesive layer 1, and the first adhesive layer 1 hardly flows during the thermocompression bonding, so the conductive particles are efficiently captured between the opposing electrodes, thereby reducing the connection resistance between the opposing first electrode 12 and second electrode 15. Furthermore, by making the thickness of the first adhesive layer 5 μm or less, the fluidity of the conductive particles during circuit connection can be further suppressed.

[0102] The heating temperature for thermocompression bonding can be set appropriately, but may be, for example, 50 to 190°C. The pressure to be applied is not particularly limited as long as it does not damage the adherend, but in the case of COP mounting, for example, the equivalent surface area pressure for the bump electrode may be 0.1 to 50 MPa. In the case of COG mounting, for example, the equivalent surface area pressure for the bump electrode may be 10 to 100 MPa. The heating and pressurizing time may be in the range of 0.5 to 120 seconds. [Example]

[0103] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0104] [Preparation of the first adhesive layer, the second adhesive layer, and the third adhesive layer] The materials shown below were used in producing the first adhesive layer, the second adhesive layer, and the third adhesive layer.

[0105] (A) Component: Conductive particles Conductive particles A-1: ​​Conductive particles with an average particle size of 3.2 μm, with the surface of the plastic core plated with Ni and the outermost surface plated with Pd.

[0106] (B) Component: Photocurable resin component The combination of the radical polymerizable compound (B1) and the photoradical polymerization initiator (B2) can function as a photocurable resin component (i.e., component (B)). On the other hand, the combination of the radical polymerizable compound (B1) and the thermal radical polymerization initiator (b2) can function as a thermosetting component.

[0107] Component (B1): radical polymerizable compound Radical polymerizable compound B1-1: NK Ester A-BPEF (ethoxylated fluorene-type di(meth)acrylate (bifunctional), manufactured by Shin-Nakamura Chemical Co., Ltd.), diluted with an organic solvent to a non-volatile content of 70% by mass. Radical polymerizable compound B1-2: Lipoxy VR-90 (bisphenol A type epoxy (meth)acrylate (bifunctional) (vinyl ester resin), manufactured by Showa Denko K.K.), used at 100% nonvolatile content Radical polymerizable compound B1-3: Cyclomer M100 (methacrylate (monofunctional) having an alicyclic epoxy group, manufactured by Daicel Corporation), used at 100% by mass of nonvolatile content

[0108] Component (B2): Photoradical polymerization initiator Photoradical polymerization initiator B2-1: IrgacureOXE-02 (a compound with an oxime ester structure, manufactured by BASF), diluted with an organic solvent to a non-volatile content of 10% by mass.

[0109] Component (b2): thermal radical polymerization initiator Thermal radical polymerization initiator b2-1: Percumyl D (dialkyl peroxide, manufactured by NOF Corporation), diluted with an organic solvent to a non-volatile content of 20% by mass.

[0110] (C) Component: Thermosetting resin component The cationic polymerizable compound (C1) can be combined with the thermal cationic polymerization initiator (C2) to function as a thermosetting component (i.e., component (C)). On the other hand, the cationic polymerizable compound (C1) can be combined with the photocationic polymerization initiator (c2) to function as a photosetting component.

[0111] Component (C1): Cationic polymerizable compound Cationic polymerizable compound C1-1: ETERNACOLL OXBP (oxetane compound, manufactured by Ube Industries, Ltd.), used at 100% nonvolatile content by mass Cationic polymerizable compound C1-2: OXSQ (oxetane compound, manufactured by Toagosei Co., Ltd.), used at 100% nonvolatile content Cationic polymerizable compound C1-3: EHPE3150 (alicyclic epoxy compound, manufactured by Daicel Corporation), diluted with an organic solvent to a non-volatile content of 70% by mass. Cationic polymerizable compound C1-4: Celloxide 8010 (alicyclic epoxy compound, manufactured by Daicel Corporation), used at 100% nonvolatile content by mass Cationic polymerizable compound C1-5: Celloxide 2021P (alicyclic epoxy compound, manufactured by Daicel Corporation), used at 100% nonvolatile content by mass Cationically polymerizable compound C1-6: A mixture of cationic polymerizable compound C1-5 and butadiene rubber fine particles with a primary particle size of less than 1 μm in a ratio of 3:1 (cationically polymerizable compound: butadiene rubber fine particles), used at 100% nonvolatile content.

[0112] Component (C2): thermal cationic polymerization initiator Thermal cationic polymerization initiator C2-1: CXC-1821 (N-(p-methoxybenzyl)-N,N-dimethylanilium tetrakis(pentafluorophenyl)borate, manufactured by King Industries), used at 100% nonvolatile content.

[0113] Component (c2): Photocationic polymerization initiator Photocationic polymerization initiator c2-1: CPI-310B (manufactured by San-Ablo Co., Ltd.), diluted with an organic solvent to a non-volatile content of 10% by mass.

[0114] (D) Component: Thermoplastic resin Thermoplastic resin D-1: Phenototo FX-293 (phenoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with an organic solvent to a non-volatile content of 40% by mass. Thermoplastic resin D-2: Phenototo YP-50S (phenoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with an organic solvent to a non-volatile content of 40% by mass. Thermoplastic resin D-3: TOPR-300 (phenoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with organic solvent to 60% non-volatile content by mass. Thermoplastic resin D-4: jER1007 (epoxy resin, manufactured by Mitsubishi Chemical Corporation), diluted with an organic solvent to a non-volatile content of 70% by mass. Thermoplastic resin D-5: Phenototo ZX-1356-2 (phenoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with an organic solvent to a non-volatile content of 40% by mass.

[0115] Component (E): Coupling agent Coupling agent E-1: SH-6040 (3-glycidoxypropyltrimethoxysilane, manufactured by Dow Corning Toray Co., Ltd.), used at 100% non-volatile content

[0116] (F) Component: Filler Filler F-1: Admanano YA050-MJL (silica fine particles, manufactured by Admatechs Co., Ltd.), diluted with organic solvent to 50% non-volatile content by mass Filler F-2: Aerosil R805 (silica fine particles, manufactured by Evonik Industries AG), diluted with an organic solvent to a non-volatile content of 10% by mass. Filler F-3: ADMAFINE SE2050 (silica fine particles, manufactured by Admatechs Co., Ltd.), diluted with organic solvent to 70% non-volatile content by mass

[0117] <Preparation of First Adhesive Film (First Adhesive Layer)> The materials shown in Table 1 were mixed in the composition ratios shown in Table 1 (the values ​​in Table 1 indicate the non-volatile content), to obtain compositions. These compositions were then coated on a release-treated PET (polyethylene terephthalate) film while applying a magnetic field, and the organic solvent and the like were dried with hot air at 70°C for 5 minutes, thereby obtaining composition layers 1a to 1i made of compositions containing the respective components. The composition layers 1a to 1i were coated so that the final thickness after drying would be as shown in Tables 4 and 5. Next, the composition layers 1a to 1f were each irradiated with light (UV irradiation: metal halide lamp, cumulative light intensity: 1900 to 2300 mJ / cm). 2 ), first adhesive films 1A to 1F were obtained. The composition layer 1g was irradiated with light (UV irradiation: metal halide lamp, cumulative light amount: 1000 to 1500 mJ / cm ). 2) to obtain a first adhesive film 1G. On the other hand, the composition layers 1h and 1i were not treated and were used as first adhesive films 1H and 1I.

[0118] [Table 1]

[0119] <Preparation of second adhesive film (second adhesive layer)> The materials shown in Table 2 were mixed in the composition ratios shown in Table 2 (the numbers in Table 2 indicate the non-volatile content), and then coated onto a release-treated PET (polyethylene terephthalate) film. The organic solvent and other organic solvents were dried off, yielding second adhesive films 2A to 2C containing each component. Second adhesive film 2A was coated to a dry thickness of 9 μm, second adhesive film 2B was coated to a dry thickness of 10 μm, and second adhesive film 2C was coated to a dry thickness of 7 μm.

[0120] [Table 2]

[0121] <Third adhesive film (third adhesive layer)> The materials shown in Table 3 were mixed in the composition ratios shown in Table 3 (the values ​​in Table 3 indicate the non-volatile content), and then coated onto a release-treated PET (polyethylene terephthalate) film, and the organic solvent was dried to obtain a third adhesive film 3A. The third adhesive film 3A was coated so that its thickness after drying would be 1 μm.

[0122] [Table 3]

[0123] (Examples 1 to 8 and Comparative Examples 1 to 5) [Preparation of adhesive film] Adhesive films having the structures shown in Tables 4 and 5 were produced using the first adhesive film, second adhesive film, and third adhesive film produced as described above. For example, in the adhesive film of Example 1, a first adhesive film 1A was attached to a second adhesive film 2A while heating to 50 to 60°C, and the release film of the first adhesive film 1A was peeled off. Next, a third adhesive film 3A was attached to the first adhesive film 1A exposed by peeling off the release film while heating to 50 to 60°C, thereby obtaining the adhesive film of Example 1. For the three-layer adhesive films of Examples 2 to 4, and 7 and Comparative Examples 3 and 5, adhesive films having the structures shown in Tables 4 and 5 were produced in the same manner as Example 1. For the two-layer adhesive films of Examples 5, 6, and 8 and Comparative Examples 1, 2, and 4, adhesive films having the structures shown in Tables 4 and 5 were produced in the same manner as Example 1, except that a third adhesive film was not attached.

[0124] [Measurement of the thickness of each adhesive layer in the adhesive film] The thicknesses of the first adhesive layer, second adhesive layer, and third adhesive layer were measured for the adhesive films of Examples 1 to 8 and Comparative Examples 1 to 5. The adhesive film was sandwiched between two sheets of glass (thickness: approximately 1 mm) and a resin composition consisting of 100 g of bisphenol A epoxy resin (trade name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a curing agent (trade name: Epomount Curing Agent, manufactured by Refine Tech Co., Ltd.) was poured into a mold. The cross section was then polished using a polishing machine, and the thicknesses of the first adhesive layer, second adhesive layer, and third adhesive layer were measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Corporation). The results are shown in Tables 4 and 5.

[0125] [Conductive particle density measurement] The adhesive films of Examples 1 to 8 and Comparative Examples 1 to 5 were analyzed using a microscope and image analysis software (trade name: ImagePro, manufactured by Hakuto Co., Ltd.) at a 25,000 μm 2 The number of conductive particles per 1 mm was measured at 20 points and the average value was calculated. 2The conductive particle density was calculated by converting the number of conductive particles per square inch. The results are shown in Tables 4 and 5.

[0126] [Evaluation of conductive particle capture rate and connection resistance] (Preparation of circuit components) The first circuit component was a polyimide substrate (200H, manufactured by DuPont-Toray Co., Ltd., dimensions: 38 mm × 28 mm, thickness: 0.05 mm) with a Ti (50 nm) / Al (400 nm) wiring pattern (pattern width: 19 μm, inter-electrode spacing: 5 μm) formed on its surface. The second circuit component was an IC chip (dimensions: 0.9 mm × 20.3 mm, thickness: 0.3 mm, bump electrode size: 70 μm × 12 μm, inter-electrode spacing: 12 μm, bump electrode thickness: 9 μm) with bump electrodes arranged in two staggered rows.

[0127] (Fabrication of circuit connection structure) Circuit connection structures were made using the adhesive films of Examples 1 to 8 and Comparative Examples 1 to 5. The adhesive film was placed on the first circuit member so that the first adhesive layer or the third adhesive layer of the adhesive film was in contact with the first circuit member. Using a thermocompression bonding device (BS-17U, manufactured by Ohashi Manufacturing Co., Ltd.) consisting of a stage made of a ceramic heater and a tool (8 mm x 50 mm), the adhesive film was bonded at 70°C and 0.98 MPa (10 kgf / cm 2 ) for 2 seconds to attach the adhesive film to the first circuit member, and then the release film on the side of the adhesive film opposite the first circuit member was peeled off. Next, the bump electrodes of the first circuit member were aligned with the circuit electrodes of the second circuit member, and then the adhesive film was heated and pressed for 5 seconds under conditions of a measured maximum temperature of 170°C and an area-equivalent pressure of 30 MPa on the bump electrodes to attach the second adhesive layer of the adhesive film to the second circuit member, thereby producing a circuit connection structure.

[0128] (Evaluation of capture rate of conductive particles) The conductive particle capture rate between the bump electrode and the circuit electrode was evaluated for the circuit connection structures obtained using each of the adhesive films of Examples 1 to 8 and Comparative Examples 1 to 5. Here, the conductive particle capture rate refers to the ratio of the conductive particle density on the bump electrode to the conductive particle density in the adhesive film, and was calculated using the following formula. The average number of conductive particles on the bump electrode was determined by observing the mounted circuit component from the polyimide substrate using a differential interference microscope and measuring the number of conductive particles captured per bump via the metal electrode. A conductive particle capture rate of 80% or more was rated "S," a conductive particle capture rate of 60% or more was rated "A," and a conductive particle capture rate of less than 60% was rated "B." The results are shown in Tables 4 and 5. Conductive particle capture rate (%) = (average number of conductive particles on bump electrode / (bump electrode area x conductive particle density in adhesive film)) x 100

[0129] (Evaluation of connection resistance) The connection resistance was evaluated using the circuit connection structures obtained using each of the adhesive films of Examples 1 to 8 and Comparative Examples 1 to 5. The connection resistance was evaluated using a four-terminal measurement method, and the average connection resistance value measured at 14 locations was used for evaluation. A multimeter (MLR21, manufactured by ETAC) was used for the measurement. A connection resistance value of less than 0.6 Ω was rated as "S," a connection resistance value of less than 1.0 Ω was rated as "A," and a connection resistance value of 1.0 Ω or more was rated as "B." The results are shown in Tables 4 and 5.

[0130] [Table 4]

[0131] [Table 5]

[0132] As shown in Tables 4 and 5, the adhesive films of Examples 1 to 8 were excellent in both the conductive particle capture rate and connection resistance when mounted at low pressure. On the other hand, the adhesive films of Comparative Examples 1 to 5 were insufficient in at least one of the conductive particle capture rate and connection resistance. This confirms that the adhesive film of the present disclosure can improve the conductive particle capture rate between opposing electrodes of a circuit connection structure and reduce connection resistance, even when mounted at low pressure. [Explanation of symbols]

[0133] 1...first adhesive layer, 2...second adhesive layer, 4...conductive particles, 5...adhesive component, 10...adhesive film for circuit connection (adhesive film), 11...first circuit board, 12...first electrode (circuit electrode), 13...first circuit member, 14...second circuit board, 15...second electrode (bump electrode), 16...second circuit member, 17...circuit connection portion, 20...circuit connection structure.

Claims

[Claim 1] a first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component; a second adhesive layer provided on the first adhesive layer and containing a second thermosetting resin component; Equipped with The thickness of the first adhesive layer is 5 μm or less. Adhesive film for circuit connection.

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