Adhesive film for circuit connection, circuit connection structure, and method for manufacturing the same.

Abstract

Disclosed is an adhesive film for circuit connection. This adhesive film for circuit connection comprises: a first adhesive layer that contains conductive particles, a cured product of a photocurable resin component, and a first heat-curable resin component; and a second adhesive layer that is provided on the first adhesive layer and contains a second heat-curable resin component. The first adhesive layer has a thickness of 5 μm or less.

Description

[Technical Field]

[0001] This disclosure relates to an adhesive film for circuit connections, a circuit connection structure, and a method for manufacturing the same. [Background technology]

[0002] Conventionally, liquid crystal display panels, organic EL panels, and the like have been used as various display means for televisions, PC monitors, mobile phones, smartphones, and other devices. In such display devices, so-called COG (chip on glass) mounting, in which the driver IC is directly mounted on the glass substrate of the display panel, has been adopted from the viewpoint of achieving finer pitch, lighter weight, and thinner design.

[0003] In liquid crystal display panels employing the COG mounting method, semiconductor elements such as liquid crystal driving ICs are connected to a transparent substrate (such as a glass substrate) that has multiple transparent electrodes (such as ITO (indium tin oxide)). As an adhesive material for connecting the electrode terminals of the semiconductor elements to the transparent electrodes, an anisotropically conductive circuit connection adhesive film is used, in which conductive particles are dispersed in the adhesive. For example, when mounting a liquid crystal driving IC as a semiconductor element, the liquid crystal driving IC has multiple electrode terminals corresponding to the transparent electrodes on its mounting surface. By thermocompressing the liquid crystal driving IC onto the transparent substrate via an anisotropically conductive circuit connection adhesive film, the electrode terminals and the transparent electrodes are connected, and a circuit connection structure can be obtained.

[0004] In recent years, curved displays (flexible displays) have been proposed. In such flexible displays, a flexible plastic substrate (such as a polyimide substrate) is used instead of a glass substrate, and various electronic components such as driver ICs are mounted on the plastic substrate. As a method of such mounting, COP (chip on plastic) mounting using an anisotropically conductive adhesive film for circuit connection is being considered (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-054288 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, in flexible displays used in organic EL panels and the like, polyimide substrates having circuit electrodes with a titanium layer on the outermost layer are mainly used. According to the inventors' studies, circuit electrodes with a titanium layer on the outermost layer have an oxide film on their surface, and it was found that the higher the resin fluidity of the adhesive film used for circuit connection, the lower the connection resistance between circuits tends to be. However, high resin fluidity also means that conductive particles flow easily, and short-circuit failures between adjacent circuits are more likely to occur due to the flowing conductive particles.

[0007] On the other hand, for example, it has been considered to suppress the fluidity of conductive particles by curing the adhesive in a circuit connection adhesive film with heat or light. However, in this case, the reductability of the resin in the adhesive will also decrease, which is expected to increase the connection resistance.

[0008] The repulsion of resin itself can, in principle, be tolerated by mounting under high pressure. However, in such cases, an adhesive layer such as 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. Along with the polyimide substrate, stress accumulates in the circuit electrodes, which have a titanium layer on the outermost surface, potentially causing cracks and circuit breakage. Therefore, in the mounting of flexible displays, it is desirable to mount under low pressure (for example, an area-equivalent pressure of 0.1 to 50 MPa at the bump electrodes), and the adhesive film used for circuit connections in COP mounting is required to suppress the fluidity of conductive particles and the increase in connection resistance under low-pressure mounting conditions.

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

[0010] One aspect of this disclosure relates to an adhesive film for circuit connections. The adhesive film for circuit connections comprises 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 provided on the first adhesive layer and containing a second thermosetting resin component. The thickness of the first adhesive layer is 5 μm or less. With such an adhesive film for circuit connections, the fluidity of conductive particles during circuit connection can be suppressed by curing the photocurable resin component, while suppressing a decrease in the exclaveability of the resin. Furthermore, by having a thickness of 5 μm or less in the first adhesive layer, the fluidity of 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 the circuit connection structure and reduce the connection resistance. Such an adhesive film for circuit connections can be suitably used 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 radical 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, when the first thermosetting resin component, the second thermosetting resin component and the photocurable resin component are in this combination, the connection resistance tends to be superior compared to, for example, when all curable resin components have cationic curability. The inventors of this disclosure speculate that the reason for this effect is as follows: If all curable resin components have cationic curability, for example, cationic active species may remain when forming the cured product of the photocurable resin component in the first adhesive layer, and these cationic active species cause the curing reaction of the second thermosetting resin component in the second adhesive layer to proceed, reducing the exclaveability of the resin. Therefore, if the photocurable resin component has radical curing properties, cationic active species are not generated when the cured product of the photocurable resin component is formed. This suppresses the progress of the curing reaction of the second thermosetting resin component in the second adhesive layer, which is expected to reduce the decrease in resin excludability and thus reduce connection resistance.

[0012] The cationic polymerizable compound may be at least one selected from the group consisting of oxetane compounds and alicyclic epoxy compounds. 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 to the second adhesive layer. The third thermosetting resin component may include a cationic polymerizable compound and a thermo-cationic polymerization initiator.

[0014] Another aspect of the present disclosure relates to a method for manufacturing a circuit connection structure. The method for manufacturing the circuit connection structure includes interposing the above-described 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 portion disposed between the first circuit member and the second circuit member and electrically connecting the first electrode and the second electrode to each other. The circuit connection portion includes a cured product of the above-described adhesive film for circuit connection.

Advantages of the Invention

[0016] According to the present disclosure, there is disclosed an adhesive film for circuit connection capable of improving the capture rate of conductive particles between opposing electrodes of a circuit connection structure and reducing the connection resistance even when mounted at a low pressure. Such an adhesive film for circuit connection can be suitably used for COP mounting. Further, according to the present disclosure, there are disclosed a circuit connection structure using such an adhesive film for circuit connection and a method for manufacturing the same.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an embodiment of an adhesive film for circuit connection. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an embodiment of a circuit connection structure. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a circuit connection structure. FIGS. 3(a) and 3(b) are schematic cross-sectional views showing each step.

Modes for Carrying Out the Invention

[0018] Embodiments of this disclosure will be described in detail below with reference to the drawings. In the following description, the same or corresponding parts will be denoted by the same reference numerals, and redundant descriptions will be omitted. However, this disclosure is not limited to the embodiments described below.

[0019] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of one stage of the numerical range may be replaced with the upper or lower limit of another stage of the numerical range. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. Furthermore, the upper and lower limits described individually can be combined in any way. In the notation "A~B" for a numerical range, the numbers A and B at both ends are included in the numerical range as the lower and upper limits, respectively. In this specification, for example, the description "10 or more" means "10" and "numbers greater than 10," and the same applies when the numbers are different. Also, for example, the description "10 or less" means "10" and "numbers less than 10," and the same applies when the numbers are different. 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" means that either A or B is included, or both may be included. Also, unless otherwise specified, the materials exemplified below may be used individually or in combination of two or more. The content of each component in a composition refers to the total amount of any multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition.

[0020] [Adhesive film for circuit connections] Figure 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connections. The adhesive film 10 for circuit connections shown in Figure 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 containing 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. In the adhesive film 10, there may be a first region which is a region formed from the first adhesive film (first adhesive layer 1), and a second region which is a 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 also be said to comprise a first region containing conductive particles 4, as well as an adhesive component 5 containing 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 may be an anisotropically conductive adhesive film for circuit connection (anisotropically conductive adhesive film). The adhesive film 10 may be interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and used to electrically connect the first electrode and the second electrode to each other by thermocompression bonding the first and second circuit members.

[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 consisting 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), an adhesive component 5 containing a cured product of component (B) and component (C). The cured product of component (B) may be a cured product in which component (B) has been completely cured, or a cured product in which a part of component (B) has been cured. Component (C) is a component that can flow when a circuit is connected, and is, for example, 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 metal particles composed of metals such as Au, Ag, Pd, Ni, Cu, or solder, or conductive carbon particles composed of conductive carbon. Component (A) may also be a coated conductive particle comprising a core containing non-conductive glass, ceramic, or plastic (such as polystyrene), and a coating layer containing the above-mentioned metal or conductive carbon that covers the core. Among these, component (A) is preferably a coated conductive particle comprising a core containing metal particles or plastic formed from a heat-meltable metal, and a coating layer containing metal or conductive carbon that covers the core. Since such coated conductive particles can be easily deformed by heating or pressurizing the cured product of the thermosetting resin component, the contact area between the electrodes and component (A) can be increased when electrically connecting electrodes, thereby further improving conductivity between electrodes.

[0024] Component (A) may be insulating coated conductive particles comprising the above-mentioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer that covers the surface of the particles and contains an insulating material such as resin. When component (A) is insulating coated conductive particles, even if the content of component (A) is high, the presence of an insulating layer on the surface of the particles can suppress the occurrence of short circuits due to contact between components (A) and can also improve the insulation between adjacent electrode circuits. Component (A) may be one of the above-mentioned conductive particles used alone or in combination of two or more types.

[0025] (A) 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 any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is taken as the maximum particle size of component (A). If component (A) has protrusions or is not spherical, the particle size of component (A) is taken as the diameter of the circle circumscribing the conductive particle in the SEM image.

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

[0027] In the first adhesive layer 1, it is preferable that component (A) is uniformly dispersed. From the viewpoint of obtaining stable connection resistance, the particle density of component (A) in the adhesive film 10 should be 100 particles / mm². 2 More than 1000 pieces / mm 2More than 3000 pieces / mm 2 Above, or 5000 pieces / mm 2 The above is acceptable. The particle density of component (A) in the adhesive film 10 is 100,000 particles / mm² from the viewpoint of improving the insulation between adjacent electrodes. 2 Below, 70000 pieces / mm 2 Below, 50000 pieces / mm 2 The following, or 30,000 pieces / mm 2 The following is acceptable:

[0028] (A) 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. (A) 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 this 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 hardens by light irradiation, however, if component (C) is a resin component that has cationic curability, component (B) may be a resin component that has radical curability from the viewpoint of having better connection resistance. Component (B) may include, for example, a radical 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] (B1) Component: Radical polymerizable compound Component (B1) is a compound that polymerizes by radicals generated from component (B2) upon irradiation with light (e.g., ultraviolet light). Component (B1) may be a monomer, or a polymer (or oligomer) formed by the polymerization of one or more monomers. Component (B1) may be used alone or in combination of multiple components.

[0031] Component (B1) is a compound having radical polymerizable groups that react with radicals. Examples of radical polymerizable groups include (meth)acryloyl groups, vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenylene groups, maleimide groups, etc. The number of radical polymerizable groups (number of functional groups) in component (B1) may be 2 or more from the viewpoint of easily obtaining the 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 curing shrinkage during polymerization. Furthermore, in order to balance the crosslinking density and curing shrinkage, in addition to compounds with a number of radical polymerizable groups within the above range, compounds with a number of radical polymerizable groups outside the above range may also be used.

[0032] Component (B1) may, for example, contain a polyfunctional (two- or more functional) (meth)acrylate from the viewpoint of suppressing the flow of conductive particles. The polyfunctional (two- or more functional) (meth)acrylate may be a bifunctional (meth)acrylate, and the bifunctional (meth)acrylate may be a bifunctional 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, tricyclodecanedimethanol (meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate;Aromatic (meth)acrylates such as ethoxylated bisphenol A type di(meth)acrylate, propoxylated bisphenol A type di(meth)acrylate, ethoxylated propoxylated bisphenol A type di(meth)acrylate, ethoxylated bisphenol F type di(meth)acrylate, propoxylated bisphenol F type di(meth)acrylate, ethoxylated propoxylated bisphenol F type di(meth)acrylate, ethoxylated fluorene type di(meth)acrylate, propoxylated fluorene type di(meth)acrylate, ethoxylated propoxylated fluorene type di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol Examples include aliphatic (meth)acrylates such as methylmethylol 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; and 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 polyfunctional (two or more functional) (meth)acrylate may be, for example, 40-100% by mass, 50-100% by mass, or 60-100% by mass, based on the total mass of component (B1), from the viewpoint of achieving both the effect of reducing connection resistance and suppressing particle flow.

[0035] Component (B1) may further contain monofunctional (meth)acrylates in addition to polyfunctional (bifunctional or more) (meth)acrylates. Examples of monofunctional (meth)acrylates 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, 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)acryloyl Aliphatic (meth)acrylates such as methyl 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, phenoxymethyl Aromatic (meth)acrylates such as ethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene 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 include (meth)acrylates having epoxy groups such as glycidyl (meth)acrylate, (meth)acrylates having alicyclic epoxy groups such as 3,4-epoxycyclohexylmethyl (meth)acrylate, and (meth)acrylates having oxetanyl groups such as (3-ethyloxetan-3-yl)methyl (meth)acrylate.

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

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

[0038] Component (B1) may contain polyfunctional (two or more functional) and monofunctional (meth)acrylates, as well as other radical polymerizable compounds. Examples of other radical polymerizable compounds include maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadiimide derivatives, and the like. The content of other radical polymerizable compounds may be, for example, 0 to 40% by mass based on the total mass of component (B1).

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

[0040] Component (B2) decomposes upon exposure to light, generating free radicals. In other words, component (B2) is a compound that generates radicals upon application of external light energy. Component (B2) may be a compound having structures such as 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 benzyldimethyl ketal structure, or an α-hydroxyalkylphenone structure. Component (B2) may be used alone or in combination of multiple components. From the viewpoint of easily obtaining the desired melt viscosity and being superior in reducing connection resistance, 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)], etanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(o-acetyloxime), and others.

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

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

[0044] The content of component (B2) 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 component (B1), from the viewpoint of suppressing the flow of conductive particles.

[0045] The content of 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 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 cured product of component (B) is within the above range, the effects of this 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 hardens with heat, but if component (B) is a resin component that has radical curability, component (C) may be a resin component that has cationic curability from the viewpoint of being superior in terms of connection resistance. Component (C) may include, for example, a cationic 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 be a component consisting of component (C1) and component (C2). The first thermosetting resin component, the second thermosetting resin component, and the third thermosetting resin component refer to thermosetting resin components contained in the first adhesive layer, the second adhesive layer, and the third adhesive layer, respectively, and the components (e.g., component (C1), component (C2), etc.) and their content contained in the first thermosetting resin component, the second thermosetting resin component, and the third thermosetting resin component may be the same or different from each other.

[0047] (C1) Component: Cationic polymerizable compound Component (C1) is a compound that crosslinks by reacting with component (C2) by heat. Note that component (C1) means a compound that does not have radical polymerizable groups that react with radicals, and component (C1) is not included in component (B1). Component (C1) may be at least one selected from the group consisting of, for example, oxetane compounds and alicyclic epoxy compounds, from the viewpoint of further improving the effect of reducing connection resistance and achieving superior connection reliability. Component (C1) may be used alone or in combination of multiple types. From the viewpoint of easily obtaining the desired melt viscosity, it is preferable that component (C1) contains both at least one oxetane compound and at least one alicyclic epoxy compound.

[0048] The oxetane compound used as component (C1) is not particularly limited as long as it has an oxetanyl group and does not have a radical polymerizable group. Examples of commercially available oxetane compounds include 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 individually or in combination.

[0049] The alicyclic epoxy compound used as component (C1) is not particularly limited as long as it has an alicyclic epoxy group (e.g., an epoxycyclohexyl group) and does not have a radical polymerizable group. Examples of commercially available alicyclic epoxy compounds include EHPE3150, EHPE3150CE, Celoxide 8010, Celoxide 2021P, and Celoxide 2081 (trade names, manufactured by Daicel Corporation). These may be used individually or in combination.

[0050] (C2) Component: Thermal cationic polymerization initiator (Component (C2) is a thermal polymerization initiator that generates an acid or the like upon heating 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 - and other onium salts such as sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, anilinium salts having anions. These may be used singly or in combination of two or more.

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

[0052] Since the onium salt as component (C2) has resistance to substances that can cause curing inhibition for cationic curing, it may be, for example, an anilinium salt. Examples of anilinium salt compounds include N,N-dialkylanilinium salts such as N,N-dimethylanilinium salt and N,N-diethylanilinium salt.

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

[0054] The content of component (C2) 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 component (C1), from the viewpoint of ensuring the formability and curability of the adhesive film for forming the first adhesive layer.

[0055] 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 first adhesive layer, from the viewpoint of ensuring the curability of the adhesive film for forming the first adhesive layer. 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 first adhesive layer, from the viewpoint of ensuring the formation of the adhesive film for forming the first adhesive layer. When the content of component (C) is within the above ranges, the effects of this disclosure tend to be significantly exhibited. The content of component (C) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above ranges.

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

[0057] Examples of component (D) include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, acrylic rubber, epoxy resin (solid at 25°C), etc. These may be used individually or in combination. A composition containing components (A), (B), and (C) can be further enriched with component (D) to easily form a composition layer (and further, the first adhesive layer 1) from the composition. Among these, component (D) may be, for example, 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 may be 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 the same as the above range.

[0058] Examples of component (E) include silane coupling agents having organic functional groups such as (meth)acryloyl groups, mercapto groups, amino groups, imidazole groups, and epoxy groups; silane compounds such as tetraalkoxysilanes; tetraalkoxytitanate derivatives; and polydialkyltitanate derivatives. These may be used individually or in combination. The adhesion of the first adhesive layer 1 can be further improved by containing component (E). Component (E) may be, for example, a silane coupling agent. The content of component (E) may be 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of component (E) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the range described above.

[0059] Component (F) may be, for example, a non-conductive filler (e.g., non-conductive particles). Component (F) may be either an inorganic filler or an organic filler. Examples of inorganic fillers include metal oxide nanoparticles such as silica nanoparticles, alumina nanoparticles, silica-alumina nanoparticles, titania nanoparticles, and zirconia nanoparticles; and inorganic nanoparticles such as metal nitride nanoparticles. Examples of organic fillers include organic nanoparticles such as silicone nanoparticles, methacrylate-butadiene-styrene nanoparticles, acrylic-silicone nanoparticles, polyamide nanoparticles, and polyimide nanoparticles. These may be used individually or in combination. Component (F) may be, for example, silica nanoparticles. The content of component (F) may be 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of component (F) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the range described above.

[0060] [Other additives] The first adhesive layer 1 may further contain other additives such as softeners, accelerators, degradation inhibitors, colorants, flame retardants, and thixotropic agents. The content of these other additives may be, for example, 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of 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 range described above.

[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 making the thickness d1 of the first adhesive layer 1 5 μm or less, the fluidity of 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 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. Furthermore, as shown in Figure 1, if 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 to the second adhesive layer 2 to the boundary S between the first adhesive layer 1 and the second adhesive layer 2 located in the spaced portion between adjacent conductive particles 4,4 (the distance shown as d1 in Figure 1) is the thickness of the first adhesive layer 1, and the exposed portion of the conductive particles 4 is not included in the thickness of the first adhesive layer 1. The length of the exposed portion of the conductive particles 4 may be, for example, 0.1 μm or more, or 5 μm or less.

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

[0063] (C) 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. (C) 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 leakage defects in reels, which is one form of supply.

[0064] The second adhesive layer 2 may further contain other components and other additives of the first adhesive layer 1. Preferred embodiments of the other components and other additives are the same as those of the preferred embodiments 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 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 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 set appropriately according to the height of the electrodes of the circuit member to be bonded. The thickness d2 of the second adhesive layer 2 may be 5 μm or more, 7 μm or more, 15 μm or less, or 11 μm or less, from the viewpoint of being able to sufficiently fill the space between electrodes and seal the electrodes and obtain 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, if a part 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 side), the distance from the surface 3a of the second adhesive layer 2 opposite to the first adhesive layer 1 side to the boundary S between the first adhesive layer 1 and the second adhesive layer 2 located in the spaced portion between adjacent conductive particles 4, 4 (the distance shown as d2 in Figure 1) is the thickness of the second adhesive layer 2.

[0070] The thickness of the adhesive film 10 (the sum of the thicknesses of all the 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 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 suppresses the fluidity of conductive particles during circuit connection by curing the photocurable resin component, while also suppressing a decrease in the resin's excludability. Furthermore, by having a thickness of 5 μm or less for the first adhesive layer, the fluidity of 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 the circuit connection structure and reduce the connection resistance. Such an adhesive film 10 can be suitably used for COP mounting.

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

[0074] The adhesive film may consist of two layers, for example, a first adhesive layer and a second adhesive layer, or it may consist of three or more layers, including the first adhesive layer and the 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 to the second adhesive layer. In the adhesive film, there may be a first region, which is a region formed from the first adhesive film (first adhesive layer), and a third region, which is a region formed from the third adhesive film (third adhesive layer), provided adjacent to the first region. The adhesive film may further include a third region containing a (third) thermosetting resin component, provided adjacent to the side of the first region opposite to the second region.

[0075] The third adhesive layer contains component (C). Since components (C1) and (C2) used in component (C) in the third adhesive layer (i.e., the third thermosetting resin component) are the same as components (C1) and (C2) used in component (C) in the first adhesive layer 1 (i.e., the first thermosetting resin component), a detailed explanation is 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 providing 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 providing good half-cutability and blocking resistance (suppression of resin seepage from the reel).

[0077] The third adhesive layer may further contain other components and other additives of the first adhesive layer 1. Preferred embodiments of the other components and other additives are the same as those of the preferred embodiment 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 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 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 set appropriately according to the height of the electrodes of the circuit components to be bonded. The thickness of the third adhesive layer may be 0.2 μm or more and 3.0 μm or less, from the viewpoint of sufficiently filling the space between electrodes and sealing 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 circuit connection adhesive film in the above embodiment is an anisotropically conductive adhesive film having anisotropic conductivity, the circuit connection adhesive film may also be a conductive adhesive film that does not have anisotropic conductivity.

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

[0085] In the first step, for example, a composition containing components (A), (B), and (C), as well as other components and additives as needed, is first dissolved or dispersed in an organic solvent by stirring, mixing, kneading, etc., to prepare a varnish composition. Then, the varnish composition is applied to a substrate that has been treated with a mold release agent using a knife coater, roll coater, applicator, comma coater, die coater, etc., and the organic solvent is evaporated by heating to form a composition layer on the substrate. At this time, 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 is irradiated with light to cure component (B) in the composition layer and form a first adhesive layer on the substrate. The first adhesive layer can be called the first adhesive film.

[0086] The organic solvent used in the preparation of the varnish composition is not particularly limited as long as it has the property of uniformly dissolving or dispersing each component. Examples of such organic solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These organic solvents can be used individually or in combination of two or more. Stirring, mixing, or kneading during the preparation of the varnish composition can be carried out using, for example, a stirrer, a 3-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 that can withstand the heating conditions when volatilizing organic solvents. Examples of such substrates include stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymers, etc. (for example, films).

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

[0089] For light irradiation during the curing process, it is preferable to use irradiation light (e.g., ultraviolet light) that includes wavelengths in the range of 150 to 750 nm. Light irradiation can be performed using, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, metal halide lamps, LED light sources, etc. The integrated light intensity of the light irradiation can be set as appropriate, for example, 500 to 3000 mJ / cm². 2 That's fine.

[0090] The second step is to laminate a second adhesive layer onto the first adhesive layer. In the second step, for example, first, a second adhesive layer is formed on the substrate in the same manner as in the first step, except that component (C) and other components and additives added as needed are used, and light irradiation is not performed, thereby obtaining a second adhesive film. Then, the second adhesive layer can be laminated onto the first adhesive layer by bonding the first adhesive film and the second adhesive film together. Alternatively, in the second step, for example, the second adhesive layer can also be laminated onto the first adhesive layer by applying a varnish composition obtained using component (C) and other components and additives added as needed onto the first adhesive layer and volatilizing the organic solvent.

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

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

[0093] <Circuit connection structure and method for manufacturing the same> The following describes a circuit connection structure using the above-mentioned circuit connection adhesive film 10 as a circuit connection material, and a method for manufacturing the same.

[0094] Figure 2 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. As shown in Figure 2, the circuit connection structure 20 includes a first circuit board 11 and a first circuit member 13 having a first electrode 12 formed on the 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 the 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, which electrically connects 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 from each other. The first circuit member 13 and the second circuit member 16 may be a glass substrate or plastic substrate on which electrodes are formed, a printed circuit board, a ceramic circuit board, a flexible circuit board, an IC chip, etc. The first circuit board 11 and the second circuit board 14 may be made of inorganic materials such as semiconductors, glass, or ceramics, organic materials such as polyimide or polycarbonate, or composite materials such as glass / epoxy. Among these, since the above-mentioned circuit connection adhesive film 10 can be suitably used for COP mounting, the first circuit member 13 may be a plastic substrate made of organic materials 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 also be electrodes formed by laminating two or more of these metals, oxides, etc. The electrodes formed by laminating two or more types may have two or more layers, or three or more layers. If 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. Figure 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 the cured product of the adhesive film 10 described above. The circuit connection portion 17 may consist of the cured product of the adhesive film 10 described above. For example, the circuit connection portion 17 has a first cured product region 18 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 consisting of cured products of component (B) and component (C), other than the conductive particles 4 in the first adhesive layer described above; a second cured product region 19 located on the second circuit member 16 side in the facing direction, and consisting of cured products of component (C), etc., in the second adhesive layer described above; 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 Figure 2, the circuit connection portion 17 does not necessarily have two distinct regions between the first cured material region 18 and the second cured material region 19, and the cured material derived from the first adhesive layer and the cured material derived from the second adhesive layer may be mixed together to form a single cured material region.

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

[0099] Specifically, as shown in Figure 3(a), first, a first circuit member 13 comprising 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 comprising 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 Figure 3(a), the adhesive film 10 is laminated onto the first circuit member 13 so that the side with 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, to 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] Then, as shown in Figure 3(b), the first circuit member 13, the adhesive film 10, and the second circuit member 16 are heated, and the first circuit member 13 and the second circuit member 16 are pressed together in the thickness direction, thereby thermocompressing them together. At this time, as indicated by the arrows in Figure 3(b), the second adhesive layer 2 has a flowable, uncured thermosetting component, so it flows to fill the gaps between the second electrodes 15 and hardens due to 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 Figure 2. In the manufacturing method of the circuit connection structure 20 of this embodiment, a portion of the first adhesive layer 1 is hardened by light irradiation, so the conductive particles 4 are fixed in the first adhesive layer 1. Furthermore, the first adhesive layer 1 hardly flows during the heat-compression bonding process, and 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. In addition, by having a thickness of 5 μm or less for the first adhesive layer, the fluidity of the conductive particles during circuit connection can be further suppressed.

[0102] The heating temperature for heat-compression bonding can be set as appropriate, but for example, it may be between 50 and 190°C. The pressurization is not particularly limited as long as it does not damage the adherend, but in the case of COP mounting, for example, the area-equivalent pressure at the bump electrode may be between 0.1 and 50 MPa. In the case of COG mounting, for example, the area-equivalent pressure at the bump electrode may be between 10 and 100 MPa. The heating and pressurization times may be in the range of 0.5 to 120 seconds. [Examples]

[0103] The present disclosure will be described in more detail below with reference to examples. However, 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 following materials were used in the preparation of the first adhesive layer, the second adhesive layer, and the third adhesive layer.

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

[0106] (B) Component: Photocurable resin component (B1) By combining a radical polymerizable compound and (B2) a photoradical polymerization initiator, it can be made to act as a photocurable resin component (i.e., component (B)). On the other hand, by combining (B1) a radical polymerizable compound and (b2) a thermal radical polymerization initiator, it can be made to act as a thermosetting component.

[0107] (B1) Component: Radical polymerizable compound Radical polymerizable compound B1-1:NK ester A-BPEF (ethoxylated fluorene-type di(meth)acrylate (bifunctional), manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), diluted with an organic solvent to a non-volatile content of 70% by mass was used. 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% by mass of non-volatile 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 non-volatile content.

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

[0109] (b2) Ingredients: Thermal radical polymerization initiator Thermal radical polymerization initiator b2-1: Perkmyl 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 By combining (C1) a cationic polymerizable compound with (C2) a thermal cationic polymerization initiator, it can be made to act as a thermosetting component (i.e., component (C)). On the other hand, by combining (C1) a cationic polymerizable compound with (C2) a photocatalytic cationic polymerization initiator, it can be made to act as a photocurable component.

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

[0112] (C2) Component: 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% by mass of non-volatile content.

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

[0114] (D) Component: Thermoplastic resin Thermoplastic resin D-1: Phenotot 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: Phenotot 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 an organic solvent to a non-volatile content of 60% by mass, was used. 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, was used. Thermoplastic resin D-5: Phenotote 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] (E) Component: Coupling agent Coupling agent E-1: SH-6040 (3-glycidoxypropyltrimethoxysilane, manufactured by Toray Dow Corning Co., Ltd.), used at 100% by mass of non-volatile content.

[0116] (F) Component: Filler Filler F-1: Admanano YA050-MJL (silica microparticles, manufactured by Admatex Co., Ltd.), diluted with an organic solvent to 50% by mass of non-volatile content. Filler F-2: Aerosil R805 (silica microparticles, 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 microparticles, manufactured by Admatex Co., Ltd.), diluted with an organic solvent to a non-volatile content of 70% by mass.

[0117] <Preparation of the first adhesive film (first adhesive layer)> Compositions were obtained by mixing the materials shown in Table 1 in the composition ratios shown in Table 1 (the values ​​in Table 1 represent the non-volatile content). These compositions were then coated onto a release-treated PET (polyethylene terephthalate) film while applying a magnetic field, and then dried with hot air at 70°C for 5 minutes using an organic solvent, etc., to obtain composition layers 1a to 1i containing each component. Composition layers 1a to 1i were coated so that the final thickness after drying was as shown in Tables 4 and 5. Subsequently, composition layers 1a to 1f were irradiated with light (UV irradiation: metal halide lamp, cumulative light intensity: 1900 to 2300 mJ / cm²). 2 ), first adhesive films 1A to 1F were obtained. For 1 g of the composition layer, the layer was irradiated with light (UV irradiation: metal halide lamp, integrated light intensity: 1000 to 1500 mJ / cm²). 2), and the first adhesive film 1G was obtained. On the other hand, no treatment was performed on the composition layers 1h and 1i, and they were used as the first adhesive films 1H and 1I.

[0118] [Table 1]

[0119] <Preparation of the second adhesive film (second adhesive layer)> The materials shown in Table 2 were mixed in the composition ratios shown in Table 2 (the values ​​in Table 2 represent the non-volatile content), and then coated onto a mold-released PET (polyethylene terephthalate) film. By drying the organic solvent, etc., second adhesive films 2A to 2C containing each component were obtained. Second adhesive film 2A was coated to a thickness of 9 μm after drying, second adhesive film 2B was coated to a thickness of 10 μm after drying, and second adhesive film 2C was coated to a thickness of 7 μm after drying.

[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 represent the non-volatile content), and then coated onto a mold-released PET (polyethylene terephthalate) film. The third adhesive film 3A was obtained by drying off organic solvents, etc. The third adhesive film 3A was coated to a thickness of 1 μm after drying.

[0122] [Table 3]

[0123] (Examples 1-8 and Comparative Examples 1-5) [Fabrication of adhesive film] Using the first adhesive film, the second adhesive film, and the third adhesive film prepared as described above, adhesive films with the configurations shown in Tables 4 and 5 were manufactured. For example, in the adhesive film of Example 1, the first adhesive film 1A was bonded to the second adhesive film 2A while applying a temperature of 50-60°C, and the release film of the first adhesive film 1A was peeled off. Next, the third adhesive film 3A was bonded to the first adhesive film 1A, which was exposed by peeling off the release film, while applying a temperature of 50-60°C, to obtain the adhesive film of Example 1. For the three-layer adhesive films of Examples 2-4, 7 and Comparative Examples 3 and 5, adhesive films with the configurations shown in Tables 4 and 5 were manufactured in the same manner as in Example 1. For the two-layer adhesive films of Examples 5, 6, 8 and Comparative Examples 1, 2, and 4, adhesive films with the configurations shown in Tables 4 and 5 were manufactured in the same manner as in Example 1, except that the third adhesive film was not attached.

[0124] [Measurement of the thickness of each adhesive layer in an adhesive film] For the adhesive films of Examples 1-8 and Comparative Examples 1-5, the thicknesses of the first, second, and third adhesive layers were measured. In the measurement, the adhesive film was sandwiched between two pieces of glass (thickness: approximately 1 mm), and after casting with a resin composition consisting of 100 g of bisphenol A type epoxy resin (product name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of a hardener (product name: Epomount hardener, manufactured by Refinetech Co., Ltd.), the cross-section was polished using a polishing machine, and the thicknesses of the first, second, and third adhesive layers were measured using a scanning electron microscope (SEM, product name: SE-8020, manufactured by Hitachi High-Tech Science Corporation). The results are shown in Tables 4 and 5.

[0125] [Measurement of conductive particle density] The adhesive films of Examples 1-8 and Comparative Examples 1-5 were examined using a microscope and image analysis software (product name: ImagePro, manufactured by Hakuto Co., Ltd.) at a depth of 25,000 μm. 2 The number of conductive particles per 1 mm was measured at 20 locations, and the average value was calculated. 2The conductive particle density was calculated by converting it to the number of conductive particles per unit area. The results are shown in Tables 4 and 5.

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

[0127] (Fabrication of circuit connection structures) Circuit connection structures were constructed using the adhesive films of Examples 1-8 and Comparative Examples 1-5. The adhesive film was placed on the first circuit member so that the first or third adhesive layer of the adhesive film was in contact with the first circuit member. A thermocompression bonding apparatus (BS-17U, manufactured by Ohashi Seisakusho Co., Ltd.) consisting of a ceramic heater stage and a tool (8 mm x 50 mm) was used at 70°C and 0.98 MPa (10 kgf / cm²). 2 The adhesive film was attached to the first circuit member by heating and pressurizing for 2 seconds under the conditions specified above, and the release film on the side of the adhesive film opposite to the first circuit member was peeled off. Next, the bump electrode of the first circuit member and the circuit electrode of the second circuit member were aligned, and then the second adhesive layer of the adhesive film was attached to the second circuit member by heating and pressurizing for 5 seconds under the conditions specified above the measured maximum temperature of the adhesive film (170°C) and the area-converted pressure at the bump electrode (30 MPa), thereby fabricating a circuit connection structure.

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

[0129] (Evaluation of connection resistance) The connection resistance was evaluated using the circuit connection structures obtained with the adhesive films of Examples 1-8 and Comparative Examples 1-5. The connection resistance was evaluated using the four-terminal measurement method, and the average value of the connection resistance values ​​measured at 14 locations was used for evaluation. A multimeter (MLR21, ETAC Corporation) was used for measurement. A connection resistance value of less than 0.6Ω was judged as "S", a connection resistance value of less than 1.0Ω was judged as "A", and a connection resistance value of 1.0Ω or more was judged 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 superior in both 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 following respects: conductive particle capture rate or connection resistance. From this, it was confirmed 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 components, 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 part, 20...Circuit connection structure.

Claims

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 containing a second thermosetting resin component is provided on the first adhesive layer, Equipped with, The first thermosetting resin component and the second thermosetting resin component each contain a cationic polymerizable compound and a thermal cationic polymerization initiator. The photocurable resin component includes a radical polymerizable compound, The cationic polymerizable compound comprises both an oxetane compound and an alicyclic epoxy compound. The thickness of the first adhesive layer is 5 μm or less. Adhesive film for circuit connections, used in COP (Computer-Assisted Packet) mounting.

2. The thermal cationic polymerization initiator is a salt compound having an anion containing boron as a constituent element. The adhesive film for circuit connection according to claim 1.

3. The present invention further comprises a third adhesive layer containing a third thermosetting resin component, provided on the side of the first adhesive layer opposite to the second adhesive layer. The adhesive film for circuit connection according to claim 1 or 2.

4. The third thermosetting resin component comprises a cationic polymerizable compound and a thermal cationic polymerization initiator. The adhesive film for circuit connection according to claim 3.

5. The method comprises the steps of interposing a circuit connection adhesive film according to any one of claims 1 to 4 between a first circuit member having a first electrode and a second circuit member having a second electrode, and then heat-pressing the first circuit member and the second circuit member together to electrically connect the first electrode and the second electrode to each other. A method for manufacturing a circuit connection structure.

6. A first circuit member having a first electrode, A second circuit member having a second electrode, A circuit connection portion is disposed between the first circuit member and the second circuit member and electrically connects the first electrode and the second electrode to each other, Equipped with, The circuit connection portion includes a cured product of the circuit connection adhesive film described in any one of claims 1 to 4. Circuit connection structure.

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