Adhesive film for circuit connection, and circuit connection structure and production method therefor

Abstract

Disclosed is an adhesive film for circuit connection. The adhesive film for circuit connection comprises a first adhesive layer containing electroconductive particles, and a second adhesive layer provided on the first adhesive layer. The second adhesive layer contains a thermosetting resin component and a thermoplastic resin. The heat-curable resin component includes an alicyclic epoxy compound. The adhesive film for circuit connection has a lowest melt viscosity of 400 Pa·s or less.

Description

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

[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.

[0002] Conventionally, liquid crystal display panels, organic EL panels, etc. have been used as various display means for 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 has been 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 adhesive film for circuit connection having anisotropic conductivity, 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 circuit connection adhesive film having anisotropic conductivity, 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).

[0005] JP 2016-054288 A

[0006] In COP mounting, from the viewpoint of suppressing deformation of the plastic substrate during mounting, mounting at low temperature (e.g., 120 to 170°C) and low pressure (e.g., an area-equivalent pressure of 25 MPa or less at the bump electrode) is desired. However, when mounting is performed under such conditions, the connection reliability of the resulting circuit connection structure may be insufficient due to factors such as a decrease in resin fluidity caused by the low temperature and a decrease in resin expulsion caused by the low pressure.

[0007] Therefore, a main object of the present disclosure is to provide an adhesive film for circuit connection that is capable of forming a circuit connection structure with excellent connection reliability.

[0008] The inventors conducted research to solve the above problems and discovered that by adjusting the melt viscosity of the circuit connection adhesive film within a predetermined range, it is possible to suppress a decrease in resin fluidity and resin expulsion even in low-temperature, low-pressure mounting, thereby improving the connection reliability of the resulting circuit connection structure, and thus completed the invention of the present disclosure.

[0009] The present disclosure provides adhesive films for circuit connection according to [1] to [3], a method for producing a circuit connection structure according to [4], and a circuit connection structure according to [5]. [1] An adhesive film for circuit connection comprising a first adhesive layer containing conductive particles and a second adhesive layer provided on the first adhesive layer, wherein the second adhesive layer contains a thermosetting resin component and a thermoplastic resin, the thermosetting resin component includes an alicyclic epoxy compound, and the minimum melt viscosity of the adhesive film for circuit connection is 400 Pa·s or less. [2] The adhesive film for circuit connection according to [1], wherein the thermosetting resin component includes, as the alicyclic epoxy compounds, a first alicyclic epoxy compound that is liquid at 25°C and a second alicyclic epoxy compound that is solid at 25°C. [3] The adhesive film for circuit connection according to [1] or [2], wherein the thermosetting resin component includes a cationically polymerizable compound other than the alicyclic epoxy compound. [4] A method for producing a circuit connection structure, comprising the steps of: interposing the adhesive film for circuit connection according to any one of [1] to [3] between a first circuit member having a first electrode and a second circuit member having a second electrode; and thermocompression bonding the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other. [5] A circuit connection structure, comprising: 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 circuit member and the second circuit member and electrically connecting the first electrode and the second electrode to each other, wherein the circuit connection part comprises a cured product of the adhesive film for circuit connection according to any one of [1] to [3].

[0010] The present disclosure discloses an adhesive film for circuit connection that can form a circuit connection structure with excellent connection reliability. Such an adhesive film for circuit connection can be mounted at low temperatures (e.g., 120 to 170°C) and low pressures (e.g., an area-equivalent pressure of 25 MPa or less on a bump electrode), making it suitable for use in COP mounting. The present disclosure also discloses a circuit connection structure using such an adhesive film for circuit connection and a method for producing the same.

[0011] Fig. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connection. Fig. 2 is a schematic cross-sectional view showing another embodiment of an adhesive film for circuit connection. Fig. 3 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. Figs. 4(a) and 4(b) are schematic cross-sectional views showing one embodiment of a method for producing a circuit connection structure.

[0012] 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.

[0013] 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 a numerical range 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 term "10 or more" means "10" and "a number greater than 10," and this also applies when the numerical values ​​are different. Furthermore, for example, the term "10 or less" means "10" and "a number less than 10," and this also applies when the numerical values ​​are different.

[0014] In this specification, "(meth)acrylate" means at least one of an 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 include either A or B, or may include both.

[0015] In this specification, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0016] [Adhesive Film for Circuit Connection] The adhesive film for circuit connection comprises a first adhesive layer containing conductive particles and a second adhesive layer provided on the first adhesive layer. The first adhesive layer and the second adhesive layer contain a thermosetting resin component and a thermoplastic resin. The thermosetting resin component includes an alicyclic epoxy compound. The adhesive film for circuit connection has a minimum melt viscosity of 400 Pa·s or less.

[0017] Fig. 1 is a schematic cross-sectional view showing one embodiment of an adhesive film for circuit connection, and is a diagram showing a schematic longitudinal cross-section of the adhesive film for circuit connection. The adhesive film for circuit connection 10A shown in Fig. 1 comprises a first adhesive layer 1 containing a plurality of conductive particles 4 and an adhesive component 3, and a second adhesive layer 2 provided on the first adhesive layer 1. In this specification, the term "longitudinal cross-section" means a cross-section (cross-section in the thickness direction) perpendicular to the main surface (e.g., adhesive film for circuit connection 10A).

[0018] At least some of the conductive particles 4 may be arranged laterally in the longitudinal cross section of the circuit connection adhesive film 10A, with adjacent conductive particles spaced apart from each other. In other words, the circuit connection adhesive film 10A may be configured with a central region 10a in its longitudinal cross section, in which the conductive particles 4 are spaced apart from adjacent conductive particles and arranged in a horizontal row, and surface regions 10b and 10c in which no conductive particles 4 are present. Here, "lateral direction" refers to a direction parallel to the main surface of the circuit connection adhesive film (the left-right direction in FIG. 1 ). Note that, in FIG. 1 , some of the conductive particles 4 are exposed from the surface of the first adhesive layer 1 (e.g., protruding toward the second adhesive layer 2), but the entire conductive particles 4 may be embedded in the first adhesive layer 1 so as not to be exposed from the surface of the first adhesive layer 1.

[0019] The adhesive film for circuit connection 10A may have conductive particles 4 dispersed in the first adhesive layer 1. Therefore, the adhesive film for circuit connection 10A may be an adhesive film for circuit connection having anisotropic conductivity (anisotropically conductive adhesive film). The adhesive film for circuit connection 10A may be interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and may 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. Note that "anisotropically conductive" means that the film is conductive in the direction of pressure application and is insulating in the direction of no pressure application.

[0020] According to the studies of the inventors of the present disclosure, it has been found that when the minimum melt viscosity of the adhesive film for circuit connection 10A is 400 Pa·s or less, deterioration in resin fluidity and resin expulsion can be suppressed even during low-temperature, low-pressure mounting, thereby improving the connection reliability of the resulting circuit connection structure. The minimum melt viscosity of the adhesive film for circuit connection 10A may be 350 Pa·s or less, 300 Pa·s or less, 250 Pa·s or less, or 200 Pa·s or less, or may be 10 Pa·s or more, 30 Pa·s or more, or 50 Pa·s or more. The minimum melt viscosity of the adhesive film for circuit connection 10A tends to depend mainly on the properties of the second adhesive layer.

[0021] The melt viscosity of the adhesive film for circuit connection 10A at 60°C may be, for example, 3500 Pa·s or less, from the viewpoint of further improving the connection reliability of the circuit connection structure. The melt viscosity of the adhesive film for circuit connection 10A at 60°C may be 3000 Pa·s or less, 2500 Pa·s or less, 2000 Pa·s or less, or 1500 Pa·s or less, or may be 100 Pa·s or more, 300 Pa·s or more, or 500 Pa·s or more. The melt viscosity of the adhesive film for circuit connection 10A at 60°C tends to depend mainly on the properties of the second adhesive layer.

[0022] In this specification, melt viscosity can be measured as follows. First, a laminate is obtained by laminating adhesive films for circuit connection to a thickness of 500 μm or more using a laminator. The obtained laminate is cut into a 10.0 mm × 10.0 mm piece to obtain a measurement sample. The obtained measurement sample is measured using a viscoelasticity measuring device under conditions of a temperature rise rate of 10°C / min, a measurement frequency of 10 Hz, and a measurement temperature of 40 to 200°C, and the minimum melt viscosity, which is the lowest value within the measurement temperature range, and the melt viscosity at 60°C are calculated.

[0023] Next, we will explain one embodiment of the components that make up the first adhesive layer 1 and the second adhesive layer 2. By using these components, it tends to be easier to adjust the minimum melt viscosity of the adhesive film for circuit connection to fall within a predetermined range.

[0024] <First Adhesive Layer> The first adhesive layer 1 contains conductive particles 4 (hereinafter sometimes referred to as "component (A)") and may further contain 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 cured product of component (B) may be a cured product obtained by completely curing component (B), or may be a cured product obtained by partially curing component (B). Component (C) is a component that can flow during connection, and is, for example, an uncured curable component (e.g., a resin component). The components other than the conductive particles 4 that constitute the first adhesive layer 1 are, for example, components that do not have conductivity (e.g., an insulating resin component).

[0025] Component (A): Conductive Particles Component (A) is not particularly limited as long as it is a particle having conductivity, and may be, for example, a metal particle made of a metal such as Au, Ag, Pd, Ni, Cu, or solder, or a conductive carbon particle made of conductive carbon. Component (A) may also be a coated conductive particle having a core containing non-conductive glass, ceramic, plastic (polystyrene, etc.), or the like, and a coating layer containing the metal or the conductive carbon that coats the core. Among these, component (A) is preferably a coated conductive particle having a core containing plastic and a coating layer containing a metal or conductive carbon that coats the core, or a metal particle formed of a heat-fusible metal.

[0026] When component (A) is a coated conductive particle, the cured product of the thermosetting resin component can be easily deformed by heating or applying pressure. This increases the contact area between the electrodes and component (A) when electrically connecting the electrodes, thereby further improving the conductivity between the electrodes.

[0027] When component (A) is metal particles formed of a heat-fusible metal, the connection between the electrodes tends to be stronger, and this tendency is particularly pronounced when solder particles are used as component (A).

[0028] The solder particles may contain at least one selected from the group consisting of tin, a tin alloy, indium, and an indium alloy, from the viewpoint of achieving both connection strength and a low melting point. Furthermore, the solder particles may contain at least one selected from the group consisting of an In—Bi alloy, an In—Sn alloy, an In—Sn—Ag alloy, an Sn—Au alloy, an Sn—Bi alloy, an Sn—Bi—Ag alloy, an Sn—Ag—Cu alloy, and an Sn—Cu alloy, from the viewpoint of achieving higher reliability during a high-temperature, high-humidity test and a thermal shock test.

[0029] The component (A) may be an insulating coated conductive particle comprising the above-mentioned metal particle, the above-mentioned conductive carbon particle, or the above-mentioned coated conductive particle, and an insulating layer containing an insulating material such as a resin and coating the surface of the particle. When the component (A) is an insulating coated conductive particle, even if the content of the component (A) is high, the particle surface has an insulating layer, so that the occurrence of a short circuit due to contact between the components (A) can be suppressed and the insulation between adjacent electrode circuits can also be improved.

[0030] The maximum particle size of the (A) component 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 the (A) component 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 the (A) component may be 30.0 μm or less, 25.0 μm or less, 20.0 μm or less, 15.0 μm or less, 10.0 μm or less, or 5.0 μm or less. In this specification, the particle size of any 300 particles (pcs) of the (A) component in the first adhesive layer is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is defined as the maximum particle size of the (A) component. Note that when the (A) component has protrusions or is not spherical, the particle size of the (A) component is defined as the diameter of a circle circumscribing the conductive particle in the SEM image.

[0031] From the viewpoint of excellent dispersibility and conductivity, the average particle size of the (A) component may be 1.0 μm or more, 2.0 μm or more, 2.5 μm or more, or 3.0 μm or more. From the viewpoint of excellent dispersibility and conductivity, the average particle size of the (A) component may be 20.0 μm or less, 10.0 μm or less, 7.0 μm or less, or 5.0 μm or less. In this specification, the particle size of any 300 particles (pcs) of the (A) component in the first adhesive layer 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.

[0032] Component (A) is preferably uniformly dispersed in first adhesive layer 1. From the viewpoint of obtaining stable connection resistance, the particle density of component (A) in adhesive film for circuit connection 10A is 100 particles / mm ２ More than 1000 pieces / mm ２ More than 3000 pieces / mm ２ More than 5000 pieces / mm ２ More than 7000 pieces / mm ２ More than 10,000 pieces / mm ２ or more than 12,000 pieces / mm ２ From the viewpoint of improving the insulating properties between adjacent electrodes, the particle density of component (A) in adhesive film for circuit connection 10A may be 100,000 particles / mm ２ Below, 70,000 pieces / mm２ Below, 50,000 pieces / mm ２ Below, 30,000 pieces / mm ２ or less, or 20,000 pieces / mm ２ It may be the following:

[0033] The monodispersity of component (A) in the adhesive film for circuit connection 10A may be 90% or more. When the monodispersity of component (A) is within this range, short circuits between adjacent circuits are less likely to occur, and a circuit connection structure with sufficiently high connection reliability tends to be obtained. The monodispersity of component (A) may be 92% or more, 94% or more, 96% or more, 97% or more, 98% or more, or 99% or more. The upper limit of the monodispersity may be 100%. The monodispersity can be determined, for example, by observing the adhesive film for circuit connection 10A from the first adhesive layer side at a magnification of 200 times using a metallurgical microscope, and measuring the number of components (A) in the adhesive film for circuit connection 10A, according to the following formula: Monodispersity (%) = (2500 μm ２ Number of monodispersed conductive particles in the ２ (Number of conductive particles in the container) x 100

[0034] The content of the (A) component may be 5% by mass or more, 10% by mass or more, or 20% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of further improving conductivity. The content of the (A) component may be 60% by mass or less, 50% by mass or less, or 45% 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 the (A) component is within the above range, the effects of the present disclosure tend to be significantly exhibited.

[0035] Component (B): Photocurable Resin Component Component (B) is not particularly limited as long as it is a resin component that cures upon irradiation with light. However, when component (C) is a resin component having cationic 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 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).

[0036] Component (B1): Radically Polymerizable Compound Component (B1) is a compound that undergoes polymerization by 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) obtained by polymerization of one or more monomers.

[0037] The component (B1) is a compound having a radical polymerizable group that reacts with a radical. Examples of the radical polymerizable group include a (meth)acryloyl group, a vinyl group, an allyl group, a styryl group, an alkenyl group, an alkenylene group, and a maleimide group. The number of radical polymerizable groups (the number of functional groups) contained in the component (B1) may be 2 or more from the viewpoint of easily obtaining a desired melt viscosity after polymerization and achieving better connection reliability, and may be 10 or less, 6 or less, or 4 or less from the viewpoint of further improving the effect of reducing connection resistance and suppressing cure shrinkage during polymerization. Furthermore, in order to balance the crosslink density and cure shrinkage, in addition to a compound having the number of radical polymerizable groups within the above range, a compound having the number of radical polymerizable groups outside the above range may also be used.

[0038] The component (B1) contains a polyfunctional (difunctional or higher) (meth)acrylate from the viewpoint of suppressing the flow of the conductive particles. The polyfunctional (difunctional or higher) (meth)acrylate may be a difunctional or trifunctional (meth)acrylate, and is preferably a difunctional (meth)acrylate. The difunctional (meth)acrylate may be a difunctional aromatic (meth)acrylate.

[0039] 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, and polypropylene glycol di( di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 1,3-butanediol 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, ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate aliphatic (meth)acrylates such as 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 (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; aromatic epoxy (meth)acrylates such as bisphenol epoxy (meth)acrylate, phenol novolac epoxy (meth)acrylate, and cresol novolac epoxy (meth)acrylate;

[0040] From the viewpoint of achieving both the effect of reducing connection resistance and the suppression of particle flow, the content of the polyfunctional (difunctional or higher) (meth)acrylate may be, for example, 50 to 100 mass %, 70 to 100 mass %, or 90 to 100 mass %, or may even be 100 mass %, based on the total mass of the component (B1).

[0041] 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 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;

[0042] The content of the monofunctional (meth)acrylate may be, for example, 0 to 50 mass%, 0 to 30 mass%, or 0 to 10 mass%, or may be 0 mass%, based on the total mass of the component (B1).

[0043] The cured product of component (B) may have, for example, 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. The cured product of component (B) having a polymerizable group that reacts by a mechanism other than a radical can be introduced by using, for example, 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, as component (B). From the viewpoint of improving reliability, the mass ratio of the (meth)acrylate having a polymerizable group that reacts by means 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 means 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.

[0044] 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).

[0045] Component (B2): Photoradical Polymerization Initiator The component (B2) is a photopolymerization initiator that generates radicals upon irradiation 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 (for example, ultraviolet light).

[0046] The component (B2) decomposes when exposed to light to generate free radicals. In other words, the component (B2) is a compound that generates radicals when exposed to 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. 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.

[0047] Specific examples of the compound having an oxime ester structure include 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-o-benzoyloxime, 1,3-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.

[0048] 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.

[0049] 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.

[0050] From the viewpoint of suppressing the flow of the conductive particles, 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.

[0051] The content of the cured product of component (B) may be 1% by mass or more, 3% by mass or more, or 5% 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 40% by mass or less, 30% by mass or less, or 20% 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.

[0052] Component (C): Thermosetting Resin Component Component (C) is not particularly limited as long as it is a resin component that cures with heat. 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 be a component consisting of components (C1) and (C2). The first thermosetting resin component, the second thermosetting resin component, and the 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, and the components (e.g., component (C1), component (C2), etc.) and contents contained in the first thermosetting resin component, the second thermosetting resin component, and the third thermosetting resin component may be the same as or different from one another.

[0053] Component (C1): Cationic Polymerizable Compound Component (C1) is a compound that crosslinks by reacting with component (C2) under heat. Note that component (C1) refers to a compound (resin) that does not have a radically polymerizable group that reacts with a radical, and component (C1) is not included in component (B1). Examples of component (C1) include compounds with cyclic ether groups, such as epoxy compounds and oxetane compounds. From the perspective of further improving the effect of reducing connection resistance and achieving superior connection reliability, component (C1) may also contain, for example, an alicyclic epoxy compound (a compound having a partial structure in which the carbon atoms that constitute the epoxy group directly constitute an alicyclic ring) (hereinafter, sometimes referred to as "component (C1-1)").

[0054] The component (C1-1) can be any compound that has an alicyclic epoxy group (for example, an epoxycyclohexyl group) and does not have a radically polymerizable group, and is not particularly limited. The component (C1-1) may have a cyclic ether group (structure) other than an alicyclic epoxy group (e.g., an epoxy group (structure), an oxetanyl group (structure), etc.). The component (C1-1) may be a first alicyclic epoxy compound that is liquid at 25°C (hereinafter sometimes referred to as "component (C1-1a)"), a second alicyclic epoxy compound that is solid at 25°C (hereinafter sometimes referred to as "component (C1-1b)"), or a combination thereof.

[0055] Component (C1-1a) may be, for example, an alicyclic epoxy compound having a softening point of 40° C. or lower. Component (C1-1b) may be, for example, an alicyclic epoxy compound having a softening point of more than 40° C. The softening point refers to a value measured by the ring and ball method in accordance with JIS K7234:1986.

[0056] Examples of commercially available products of component (C1-1a) include Celloxide 2021P (trade name, manufactured by Daicel Corporation), Celloxide 8010 (trade name, manufactured by Daicel Corporation), and Celloxide 2081 (trade name, manufactured by Daicel Corporation).

[0057] Other examples of the component (C1-1a) include compounds represented by general formula (I).

[0058]

[0059] In formula (I), R １ , R ２ , R ３ , and R ４ each independently represents a hydrogen atom or a methyl group, and m and n each independently represent 1 or 2.

[0060] An example of a commercially available product of component (C1-1b) is EHPE3150 (trade name, manufactured by Daicel Corporation, softening point: 75°C).

[0061] In addition to the component (C1-1), the component (C1) may also contain a cationically polymerizable compound other than the component (C1-1) (hereinafter, sometimes referred to as "component (C1-2)"). The component (C1-2) can be any compound that has a cyclic ether group other than an alicyclic epoxy group and does not have an alicyclic epoxy group, without any particular restrictions. The component (C1-2) may be, for example, a compound that has an oxetanyl group and does not have an alicyclic epoxy group.

[0062] Commercially available products of the component (C1-2) include, for example, ETERNACOLL OXBP (trade name, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, manufactured by UBE Inc.), OXSQ, OXT-121, OXT-221, OXT-101, and OXT-212 (trade names, manufactured by Toagosei Co., Ltd.).

[0063] Other examples of the component (C1-2) include bifunctional epoxy resins such as bisphenol A type epoxy, novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins.

[0064] Component (C2): Thermal Cationic Polymerization Initiator The component (C2) is a thermal polymerization initiator that generates an acid or the like upon heating to initiate polymerization. The component (C2) may be a salt compound composed of a cation and an anion. The component (C2) may be, for example, BF ４－ , B.R. ４ － (R represents a phenyl group in which a hydrogen atom is substituted with two or more fluorine atoms or two or more trifluoromethyl groups), PF ６ － , SbF ６ － , AsF ６ － and onium salts such as sulfonium salts, phosphonium salts, ammonium salts (quaternary ammonium salts), diazonium salts, iodonium salts, anilinium salts, and pyridium salts having anions such as those mentioned above.

[0065] From the viewpoint of storage stability, the component (C2) is, for example, an anion containing boron as a constituent element, i.e., BF ４ － or BR ４ － (R represents a phenyl group in which a hydrogen atom is 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 BR ４ － and more specifically, tetrakis(pentafluorophenyl)borate.

[0066] The onium salt as component (C2) may be, for example, a quaternary ammonium salt or anilinium salt, since these salts are 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.

[0067] Component (C2) may be a quaternary ammonium salt or 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).

[0068] From the viewpoint of ensuring the formability and curability of the first adhesive layer, 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.

[0069] 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 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 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.

[0070] Other Components 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 the 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)").

[0071] Examples of the (D) component include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, acrylic rubber, and epoxy resin (solid at 25°C). When a composition containing the (A), (B), and (C) components further contains the (D) component, a composition layer (and further the first adhesive layer 1) can be easily formed from the composition. Among these, the (D) component may be, for example, a phenoxy resin. The content of the (D) component 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.

[0072] Examples of the 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. By including the component (E) in the first adhesive layer 1, the adhesiveness can be further improved. The component (E) may be, for example, a silane coupling agent. The content of the component (E) may be 0.1 to 10% by mass, based on the total mass of the first adhesive layer.

[0073] Examples of the component (F) include non-conductive fillers (e.g., non-conductive particles). The component (F) may be either an inorganic filler or an organic filler. Examples of the inorganic filler 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 the organic filler include organic fine particles such as silicone fine particles, methacrylate-butadiene-styrene fine particles, acrylic-silicone fine particles, polyamide fine particles, and polyimide fine particles. The component (F) may be, for example, silica fine particles. The content of the component (F) may be 0.1 to 10 mass % based on the total mass of the first adhesive layer.

[0074] Other Additives The first adhesive layer 1 may further contain other additives such as a softener, an accelerator, an anti-degradant, a colorant, a flame retardant, a thixotropic agent, etc. 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.

[0075] The thickness d1 of the first adhesive layer 1 may be, for example, 30.0 μm or less, 20.0 μm or less, 15.0 μm or less, 10.0 μm or less, 8.0 μm or less, 5.0 μm or less, 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. When the thickness d1 of the first adhesive layer 1 is 30.0 μm or less, the resin content between the opposing circuits is reduced, thereby suppressing an increase in connection resistance between the opposing circuits. This tendency is more pronounced when the thickness d1 of the first adhesive layer 1 is 5.0 μm or less. The thickness d1 of the first adhesive layer 1 may be, for example, 0.1 μm or more or 0.7 μm or more. 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 1a 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, which is 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 5.0 μm or less.

[0076] The thickness d1 of the first adhesive layer 1 can be determined, for example, by the method described in the Examples. Specifically, the adhesive film for circuit connection is 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.) is poured into the mold. The cross section is then polished using a polishing machine, and the thickness d1 can be measured using a scanning electron microscope (SEM, trade name: SE-8020, manufactured by Hitachi High-Tech Science Corporation). This operation may be performed multiple times, and the average value may be used as the thickness d1 of the first adhesive layer 1.

[0077] The ratio of the thickness of the first adhesive layer 1 to the average particle size of the conductive particles 4 (thickness of the first adhesive layer 1 / average particle size of the conductive particles 4) may be, for example, 0.30 or more, 0.35 or more, or 0.40 or more. When this ratio is 0.30 or more, the resin content between the opposing circuits is reduced, and an increase in the connection resistance between the opposing circuits can be suppressed. This ratio may be, for example, 2.00 or less, 1.50 or less, 1.20 or less, or 1.00 or less.

[0078] <Second Adhesive Layer> The second adhesive layer 2 may be, for example, an insulating adhesive layer composed of a non-conductive component (insulating resin component). The second adhesive layer 2 contains a component (C) (second thermosetting resin component) and a component (D). The component (C) contains a component (C1-1), which may contain a component (C1-1a) and a component (C1-1b).

[0079] The components (C1), (C2), and (D) used in the component (C) (i.e., the second thermosetting resin component) in the second adhesive layer 2 are the same as the components (C1), (C2), and (D) used in the component (C) (i.e., the first thermosetting resin component) in the first adhesive layer 1, and therefore detailed explanations thereof will be omitted here.

[0080] 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 achieving better connection reliability. The content of component (C) may be 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% 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.

[0081] From the viewpoint of achieving better connection reliability, the content of the (D) component may be 1 mass % or more, 3 mass % or more, or 5 mass % or more, based on the total mass of the second adhesive layer, and may be 60 mass % or less, 40 mass % or less, or 20 mass % or less.

[0082] From the viewpoint of sufficiently reducing the melt viscosity of the adhesive film for circuit connection and improving the connection reliability of the resulting circuit connection structure, the content of component (D) is 50 parts by mass or less, or may be 48 parts by mass or less, 45 parts by mass or less, 42 parts by mass or less, or 40 parts by mass or less, relative to 100 parts by mass of the total mass of component (C1-1). The content of component (D) may be, for example, 1 part by mass or more, 5 parts by mass or more, 10 parts by mass or more, or 15 parts by mass or more, relative to 100 parts by mass of the total mass of component (C1-1).

[0083] From the viewpoint of more sufficiently reducing the melt viscosity of the adhesive film for circuit connection and further improving the connection reliability of the resulting circuit connection structure, the content of component (D) may be at least 50 parts by mass, at least 55 parts by mass, or at least 60 parts by mass, and may be at most 150 parts by mass, at most 120 parts by mass, or at most 100 parts by mass, relative to the total mass of component (C1-1a).

[0084] From the viewpoint of more sufficiently reducing the melt viscosity of the adhesive film for circuit connection and further improving the connection reliability of the resulting circuit connection structure, the content of component (D) may be no more than 120 parts by mass, no more than 110 parts by mass, or no more than 100 parts by mass, or may be no less than 30 parts by mass, no less than 40 parts by mass, or no less than 50 parts by mass, relative to 100 parts by mass of the total mass of component (C1-1b).

[0085] From the viewpoint of more sufficiently reducing the melt viscosity of the adhesive film for circuit connection and further improving the connection reliability of the resulting circuit connection structure, the total content of the component (C1-1) and the component (D) may be 15% by mass or more, 20% by mass or more, or 25% by mass or more, and may be 50% by mass or less, 40% by mass or less, or 35% by mass or less, based on the total mass of the second adhesive layer.

[0086] The second adhesive layer 2 may further contain other components and other additives than those in the first adhesive layer 1. Preferred aspects of the other components and other additives are the same as those of the first adhesive layer 1.

[0087] The content of the component (E) may be 0.1 to 10% by mass based on the total mass of the second adhesive layer.

[0088] The content of component (F) may be 1 mass % or more, 10 mass % or more, or 30 mass % or more, based on the total mass of the second adhesive layer, and may be 90 mass % or less, 70 mass % or less, or 50 mass % or less.

[0089] 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.

[0090] 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. From the viewpoint of being able to sufficiently fill the space between the electrodes and seal the electrodes, and thus obtaining better connection reliability, the thickness d2 of the second adhesive layer 2 may be 1.0 μm or more, 3.0 μm or more, or 5.0 μm or more, and may be 30.0 μm or less, 20.0 μm or less, 15.0 μm or less, or 13.0 μm or less. Note that, when a portion of the conductive particles 4 is exposed from the surface of the first adhesive layer 1 (e.g., protruding toward the second adhesive layer 2), the distance (d2 in FIG. 1 ) from the surface 2 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, is the thickness of the second adhesive layer 2.

[0091] The thickness d2 of the second adhesive layer 2 can be determined, for example, in the same manner as the method for measuring the thickness d1 of the first adhesive layer 1 described above.

[0092] The thickness of the adhesive film 10A for circuit connection (the total thickness of all layers constituting the adhesive film 10A for circuit connection; in FIG. 1, the total thickness d1 of the first adhesive layer 1 and the thickness d2 of the second adhesive layer 2) may be, for example, 3.0 μm or more, 5.0 μm or more, or 7.0 μm or more, and may be 60.0 μm or less, 40.0 μm or less, 30.0 μm or less, 20.0 μm or less, or 15.0 μm or less.

[0093] The adhesive film for circuit connection 10A is an adhesive film used for connecting circuits. The adhesive film for circuit connection 10A may or may not have anisotropic conductivity. That is, the adhesive film for circuit connection may be an anisotropically conductive adhesive film or a non-anisotropically conductive (e.g., isotropically conductive) adhesive film. The adhesive film for circuit connection 10A may be interposed between a first circuit member having a first electrode (the surface on which the first electrode is provided) and a second circuit member having a second electrode (the surface on which the second electrode is provided), and may be used to electrically connect the first electrode and the second electrode to each other (via conductive particles (or molten and solidified conductive particles)) by thermocompression bonding the first circuit member and the second circuit member (by heating a laminate including the first circuit member, the adhesive film for circuit connection 10A, and the second circuit member while being pressed in the thickness direction of the laminate).

[0094] The adhesive film 10A for circuit connection can suppress a decrease in resin fluidity and a decrease in resin expulsion even when mounted at low temperature and low pressure, making it possible to form a circuit connection structure with excellent connection reliability.

[0095] Although the adhesive film for circuit connection of the present embodiment has been described above, the present disclosure is not limited to the above embodiment.

[0096] 2 is a schematic cross-sectional view showing another embodiment of an adhesive film for circuit connection, and is a diagram showing a schematic longitudinal section of the adhesive film for circuit connection. The adhesive film for circuit connection may be composed of, for example, 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 for circuit connection may further include, for example, a third adhesive layer 5 provided on the side of the first adhesive layer opposite the second adhesive layer, as in the adhesive film for circuit connection 10B shown in FIG.

[0097] The third adhesive layer 5 contains at least the component (C). The components (C1) and (C2) used in the component (C) (i.e., the third thermosetting resin component) in the third adhesive layer are the same as the components (C1) and (C2) used in the 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.

[0098] 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 third adhesive layer, from the viewpoint of imparting good transferability and peel resistance. 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 third adhesive layer, from the viewpoint of imparting good half-cut property and blocking resistance (suppression of resin bleeding from the reel).

[0099] The third adhesive layer 5 may further contain other components and other additives than those in the first adhesive layer 1. Preferred aspects of the other components and other additives are the same as those of the first adhesive layer 1.

[0100] The content of component (D) may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the third adhesive layer, and may be 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0101] The content of the component (E) may be 0.1 to 10% by mass based on the total mass of the third adhesive layer.

[0102] The content of component (F) may be 1 mass% or more, 3 mass% or more, or 5 mass% or more, based on the total mass of the third adhesive layer, and may be 50 mass% or less, 40 mass% or less, or 30 mass% or less.

[0103] 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.

[0104] The thickness d3 of the third adhesive layer 5 may be set appropriately depending on the height of the electrodes of the circuit component to be bonded, etc. The thickness d3 of the third adhesive layer 5 may be 0.2 μm or more or 0.5 μm or more, and may be 5.0 μm or less or 2.5 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 d3 of the third adhesive layer 5 is the distance from the surface 5 a of the third adhesive layer 5 opposite the first adhesive layer 1 side to the surface 1 a of the first adhesive layer 1 opposite the second adhesive layer 2 side (the distance indicated by d3 in FIG. 2 ).

[0105] The thickness d3 of the third adhesive layer 5 can be determined, for example, in the same manner as the method for measuring the thickness d1 of the first adhesive layer 1 described above.

[0106] When the adhesive film for circuit connection has a layer other than the first adhesive layer and the second adhesive layer (e.g., a third adhesive layer), the thickness of the adhesive film for circuit connection (the total thickness of all layers constituting the adhesive film for circuit connection) may be the same as the range of thicknesses that the adhesive film for circuit connection 10A can have.

[0107] [Method for producing an adhesive film for circuit connection] In one embodiment, a method for producing an adhesive film for circuit connection may include a step (first step) of forming a first adhesive layer containing component (A), and a step (second step) of laminating a second adhesive layer containing component (C) on the first adhesive layer.

[0108] In the first step, for example, a first adhesive composition containing components (A), (B), and (C) (first thermosetting resin components), other components, and other additives is first dissolved or dispersed in an organic solvent by stirring, mixing, kneading, or the like to prepare a first varnish composition. The first 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 consisting of the first adhesive composition on the substrate. The thickness of the final first adhesive layer can be adjusted by adjusting the amount of varnish composition applied.

[0109] When the composition layer contains component (B), the first step may be a step of irradiating a composition layer made of a first adhesive composition with light (actinic rays) to cure component (B) in the composition layer, thereby forming an adhesive layer containing component (A), a cured product of component (B), component (C), other components, other additives, etc. The first adhesive layer can be referred to as a first adhesive film.

[0110] The organic solvent used in preparing the first 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 during the preparation of the first varnish composition can be performed using, for example, a mixer, a kneading machine, a three-roll mill, a ball mill, a bead mill, a homodisper, etc.

[0111] The substrate is not particularly limited as long as it has heat resistance that can withstand the heating conditions when 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, liquid crystal polymer, etc.

[0112] The heating conditions for volatilizing the organic solvent from the first 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.

[0113] A portion of the organic solvent may remain in the first adhesive layer without being removed. The content of the organic solvent in the first adhesive layer may be, for example, 10 mass % or less based on the total mass of the first adhesive layer.

[0114] For the light irradiation, light having a wavelength in the range of 150 to 750 nm (for example, ultraviolet light) can be used. The 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, or the like. The integrated light amount of the irradiated light can be set as appropriate, but is, for example, 500 to 3000 mJ / cm. ２ It may be.

[0115] 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 varnish composition is prepared in the same manner as the first step, except that a second adhesive composition containing component (C) (second thermosetting resin component), component (D), other components, other additives, etc. is used (and light irradiation is not performed), and a second adhesive layer is formed on a substrate to obtain a second adhesive film. Next, the first adhesive layer (first adhesive film) and the second adhesive layer (second adhesive film) are bonded together to laminate the second adhesive layer on the first adhesive layer. In addition, in the second step, the second adhesive layer can also be laminated on the first adhesive layer by, for example, directly applying the second varnish composition on the first adhesive layer and volatilizing the organic solvent.

[0116] A portion of the organic solvent may remain in the second adhesive layer without being removed. The content of the organic solvent in the second adhesive layer may be, for example, 10 mass % or less based on the total mass of the second adhesive layer.

[0117] Examples of methods for bonding the first adhesive layer (first adhesive film) and the second adhesive layer (second adhesive film) include hot pressing, roll lamination, vacuum lamination, etc. These bonding methods can be performed under temperature conditions of, for example, 0 to 80°C.

[0118] While one embodiment of the method for manufacturing an adhesive film for circuit connection has been described above using the method for manufacturing the adhesive film for circuit connection 10A as an example, the present disclosure is not limited to the above embodiment.

[0119] For example, the method for producing an adhesive film for circuit connection may further include a step (third step) of laminating a third adhesive layer on the surface of the first adhesive layer opposite the second adhesive layer. Such a production method can produce an adhesive film for circuit connection further comprising a third adhesive layer (e.g., adhesive film 10B for circuit connection shown in FIG. 2).

[0120] The third adhesive layer can be formed using a third adhesive composition containing component (C) (a third thermosetting resin component), other components, other additives, etc. In the third step, for example, a third varnish composition is first prepared in the same manner as in the first step, except that the third adhesive composition is used (and light irradiation is not performed), and a third adhesive layer is formed on a substrate to obtain a third adhesive film. Next, the first adhesive layer (first adhesive film) and the third adhesive layer (third adhesive film) are bonded together to form the third adhesive layer on the first adhesive layer. In addition, in the third step, the third adhesive layer can also be laminated on the first adhesive layer by, for example, directly applying the third varnish composition on the first adhesive layer and volatilizing the organic solvent.

[0121] [Circuit Connection Structure and Manufacturing Method Thereof] Hereinafter, a circuit connection structure and a manufacturing method therefor will be described, taking as an example an embodiment in which the above-mentioned adhesive film for circuit connection 10A is used as the circuit connecting material.

[0122] 3 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. As shown in FIG. 3, the circuit connection structure 100 includes a first circuit board 21 and a first circuit member 23 having a first electrode 22 formed on the main surface 21a of the first circuit board 21, a second circuit member 26 having a second electrode 25 formed on the main surface 24a of the second circuit board 24, and a circuit connection portion 27 that includes a cured body of the adhesive film for circuit connection 10A and is disposed between the first circuit member 23 and the second circuit member 26, electrically connecting the first electrode 22 and the second electrode 25 to each other via the conductive particles 4 (or a molten and solidified product of the conductive particles 4) and bonding the first circuit member 23 and the second circuit member 26 together.

[0123] The first circuit member 23 and the second circuit member 26 may be the same or different. The first circuit member 23 and the second circuit member 26 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 21 and the second circuit board 24 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 adhesive film 10A for circuit connection can be suitably used for COP mounting, the first circuit member 23 may be a plastic substrate made of an organic material such as polyimide, polycarbonate, polyethylene terephthalate, or cycloolefin polymer, and the second circuit board 24 may be an IC chip, for example.

[0124] The first electrode 22 and the second electrode 25 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 22 and the second electrode 25 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 three or more layers. When the first circuit member 23 is a plastic substrate, the first electrode 22 may be an electrode having a titanium layer on the outermost surface. The first electrode 22 and the second electrode 25 may be circuit electrodes or bump electrodes. At least one of the first electrode 22 and the second electrode 25 may be a bump electrode. The circuit connection structure shown in FIG. 3 is an embodiment in which the first electrode 22 is a circuit electrode and the second electrode 25 is a bump electrode.

[0125] The circuit connection portion 27 includes a cured product of the adhesive film 10A for circuit connection. The circuit connection portion 27 may be made of a cured product of the adhesive film 10A for circuit connection. The circuit connection portion 27 has, for example, a first cured product region 28 located on the first circuit member 23 side in the direction in which the first circuit member 23 and the second circuit member 26 face each other (hereinafter referred to as the "facing direction") and made of a cured product derived from the first adhesive layer other than the conductive particles 4, a second cured product region 29 located on the second circuit member 26 side in the facing direction and made of a cured product derived from the second adhesive layer, and conductive particles 4 interposed at least between the first electrode 22 and the second electrode 25 to electrically connect the first electrode 22 and the second electrode 25 to each other. As shown in Figure 3, the circuit connection portion 27 does not have to have two distinct hardened body regions, the first hardened body region 28 and the second hardened body region 29, but may have a single hardened body region in which the hardened body derived from the first adhesive layer and the hardened body derived from the second adhesive layer are mixed.

[0126] 4 is a schematic cross-sectional view showing one embodiment of a method for manufacturing a circuit connection structure. Figures 4(a) and 4(b) are schematic cross-sectional views showing each step. As shown in Figure 4, the method for manufacturing a circuit connection structure 100 includes the steps of interposing an adhesive film for circuit connection 10A between a first circuit member 23 having a first electrode 22 and a second circuit member 26 having a second electrode 25, and thermocompression bonding the first circuit member 23 and the second circuit member 26 to electrically connect the first electrode 22 and the second electrode 25 to each other.

[0127] Specifically, first, a first circuit member 23 including a first circuit board 21 and a first electrode 22 formed on the main surface 21a of the first circuit board 21, and a second circuit member 26 including a second circuit board 24 and a second electrode 25 formed on the main surface 24a of the second circuit board 24 are prepared.

[0128] Next, the first circuit member 23 and the second circuit member 26 are arranged so that the first electrode 22 and the second electrode 25 face each other, and the adhesive film for circuit connection 10A is placed between the first circuit member 23 and the second circuit member 26. For example, as shown in Figure 4(a) , the adhesive film for circuit connection 10A is laminated on the first circuit member 23 so that the first adhesive layer 1 faces the main surface 21a of the first circuit board 21. Next, the second circuit member 26 is placed on the first circuit member 23 on which the adhesive film for circuit connection 10A has been laminated so that the first electrode 22 on the first circuit board 21 and the second electrode 25 on the second circuit board 24 face each other.

[0129] 4(b), the first circuit member 23 and the second circuit member 26 are heated while being pressed in the thickness direction, thereby thermocompressing the first circuit member 23 and the second circuit member 26 together. During this process, as indicated by the arrows in FIG. 4(b), the second adhesive layer 2 contains a flowable uncured thermosetting resin component, so that it flows to fill the gaps between the second electrodes 25 and is cured by the heat of the thermocompression bonding. As a result, the first electrode 22 and the second electrode 25 are electrically connected to each other via the conductive particles 4, and the first circuit member 23 and the second circuit member 26 are bonded to each other, thereby obtaining the circuit connection structure 100 shown in FIG. 2.

[0130] In the manufacturing method of the circuit connection structure 100 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 thermocompression bonding, so the conductive particles are efficiently captured between the opposing electrodes, thereby reducing the connection resistance between the opposing first electrode 22 and second electrode 25. Furthermore, by having a thickness of the first adhesive layer of 5.0 μm or less and a ratio of the thickness of the first adhesive layer to the average particle size of the conductive particles of 0.50 or more, the resin content between the opposing circuits is reduced, making it possible to suppress an increase in the connection resistance between the opposing circuits.

[0131] The heating temperature in thermocompression bonding can be set appropriately, but may be, for example, 50 to 190°C. In the case of COP mounting, the heating temperature may be, for example, 120 to 170°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 area pressure at the bump electrode may be 25 MPa or less, or may be 0.1 to 20 MPa. In addition, in the case of COG mounting, for example, the equivalent area pressure at 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.

[0132] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0133] [Material Preparation] Synthesis of Cationic Polymerizable Compound C1-1a-1 4.71 g (42.0 mmol) of 3-cyclohexene-1-methanol (FUJIFILM Wako Pure Chemical Industries, Ltd.) and 50 mL of dimethylformamide (FUJIFILM Wako Pure Chemical Industries, Ltd.) were placed in a 300 mL recovery flask and ice-cooled to 5°C with stirring. Subsequently, 4.71 g (42.0 mmol) of potassium tert-butoxide (FUJIFILM Wako Pure Chemical Industries, Ltd.) was added at 5°C, and 4.87 g (20.0 mmol) of 3,3-bis(bromomethyl)oxetane (FUJIFILM Wako Pure Chemical Industries, Ltd.) was added dropwise. The mixture was then heated to room temperature (25°C) and stirred for 14 hours. Subsequently, toluene (FUJIFILM Wako Pure Chemical Industries, Ltd.) was added to the reaction solution, and the mixture was washed with water. The organic solvent was then distilled off from the resulting organic layer. The resulting concentrate was purified by distillation to obtain 3.98 g (13.0 mol / yield 65%) of 3,3-bis[(3-cyclohexen-1-ylmethoxy)methyl]oxetane) as a colorless, transparent liquid.

[0134] 3.98 g (13.0 mmol) of 3,3-bis[(3-cyclohexen-1-ylmethoxy)methyl]oxetane, 0.53 g (3.90 mmol) of potassium carbonate (FUJIFILM Wako Pure Chemical Industries, Ltd.), 4 mL of acetonitrile (FUJIFILM Wako Pure Chemical Industries, Ltd.), and 6 mL of methanol (FUJIFILM Wako Pure Chemical Industries, Ltd.) were placed in a 300 mL recovery flask and stirred at room temperature (25°C). Subsequently, 5.19 g (45.5 mmol) of a 30% aqueous hydrogen peroxide solution (FUJIFILM Wako Pure Chemical Industries, Ltd.) was added dropwise, and the mixture was stirred for 18 hours. 50 g of toluene was added to this reaction solution, and the product was extracted and washed with water. The organic solvent was distilled off from the obtained organic layer, and the obtained concentrate was purified by silica gel column chromatography (ethyl acetate / hexane=2 / 8 (volume ratio)) to obtain 2.54 g (7.50 mmol / yield 58%) of 3,3-bis[(3,4-epoxycyclohexyl-1-methoxy)methyl]oxetane as a colorless, transparent liquid.

[0135] In the examples and comparative examples, the materials shown below were used as component (A), component (B), component (C), component (D), component (E), and component (F).

[0136] Component (A): Conductive particles Conductive particles A-1: ​​Conductive particles in which the surface of a plastic core is Ni-plated and the outermost surface is subjected to displacement plating with Pd (average particle size: 3.2 μm)

[0137] Component (B): Photocurable resin component Component (B1): Radical polymerizable compound Radical polymerizable compound B1-1: VR-90 (bisphenol A type epoxy (meth)acrylate (bifunctional) (vinyl ester resin), manufactured by Resonac Co., Ltd.) Radical polymerizable compound B1-2: A-1000 (polyethylene glycol diacrylate (bifunctional), manufactured by Shin-Nakamura Chemical Co., Ltd.) Component (B2): Photoradical polymerization initiator Photoradical polymerization initiator B2-1: Omnirad 907 (compound having an α-aminoalkylphenone structure, manufactured by IGM Resins)

[0138] Component (C): thermosetting resin component; Component (C1): cationically polymerizable compound; Component (C1-1): alicyclic epoxy compound; Component (C1-1a): first alicyclic epoxy compound; Cationically polymerizable compound C1-1a-1: 3,3-bis[(3,4-epoxycyclohexyl-1-methoxy)methyl]oxetane synthesized above (liquid at 25°C); Cationically polymerizable compound C1-1a-2: Celloxide 2021P (manufactured by Daicel Corporation, liquid at 25°C); Component (C1-1b): second alicyclic epoxy compound; Cationically polymerizable compound C1-1b-1: EHPE3150 (manufactured by Daicel Corporation, solid at 25°C); Component (C1-2): cationically polymerizable compound other than component (C1-1); Cationically polymerizable compound C1-2-1: ETERNACOLL OXBP (oxetane compound, manufactured by UBE Inc.) Cationically polymerizable compound C1-2-2: OXT-212 (oxetane compound, manufactured by Toagosei Co., Ltd.) Cationically polymerizable compound C1-2-3: jER1007 (epoxy compound, manufactured by Mitsubishi Chemical Corporation) 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)

[0139] Component (D): Thermoplastic resin Thermoplastic resin D-1: Phenototo FX-293 (phenoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.) Thermoplastic resin D-2: Phenototo YP-70 (phenoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.)

[0140] Component (E): Coupling Agent Coupling Agent E-1: SH-6040 (3-glycidoxypropyltrimethoxysilane, manufactured by Dow-Toray Industries, Inc.) Coupling Agent E-2: KBM-303 (ethyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0141] Component (F): Filler Filler F-1: ADMAFINE SE2050 (silica fine particles, manufactured by Admatechs Co., Ltd.) Filler F-2: AEROSIL R805 (silica fine particles, manufactured by Evonik Industries AG)

[0142] Example 1 [Preparation of Adhesive Film for Circuit Connection] <Preparation of First Adhesive Film (First Adhesive Layer)> The materials shown in Table 1 were mixed in the amounts shown in Table 1 (the values ​​in Table 1 indicate the non-volatile content) to obtain a first varnish composition. Next, the first varnish composition was applied to a 50 μm-thick release-treated PET (polyethylene terephthalate) film, which was a release-treated substrate, while a magnetic field was applied, and the organic solvent and the like were dried to obtain a composition layer containing each component. Next, the composition layer was irradiated with light (UV irradiation: metal halide lamp, cumulative light amount: 2000 mJ / cm ２ (wavelength: 365 nm) to obtain a first adhesive film 1A (first adhesive layer 1A). The first adhesive film 1A contains conductive particles, a cured product of a photocurable resin component, and a thermosetting resin component.

[0143]

[0144] <Preparation of Second Adhesive Film (Second Adhesive Layer)> A second varnish composition was obtained by mixing the materials shown in Table 2 in the amounts shown in Table 2 (the values ​​in Table 2 indicate the non-volatile content). The composition was then applied to a release-treated PET (polyethylene terephthalate) film with a thickness of 50 μm, which was a release-treated substrate, and the organic solvent and the like were dried to obtain a second adhesive film 2A (second adhesive layer 2A).

[0145]

[0146] <Preparation of adhesive film for circuit connection> Using the first adhesive film 1A (first adhesive layer 1A) and second adhesive film 2A (second adhesive layer 2A) prepared above, the first adhesive film 1A (first adhesive layer 1A) and the second adhesive film 2A (second adhesive layer 2A) were bonded together using a hot roll laminator heated to 50°C, to obtain the adhesive film for circuit connection of Example 1.

[0147] [Measurement of Thickness of Each Adhesive Layer] The thicknesses of the first adhesive layer and the second adhesive layer were measured for the adhesive film for circuit connection of Example 1. In the measurement, the adhesive film for circuit connection was sandwiched between two pieces of glass (thickness: approximately 1 mm), and a resin composition consisting of 100 g of bisphenol A type 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 polished using a polishing machine, and the thicknesses of the first adhesive layer and the second 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 Table 4.

[0148] [Melt Viscosity Measurement] The melt viscosity of the adhesive film for circuit connection of Example 1 was measured. The adhesive film for circuit connection was laminated using a laminator to a thickness of 500 μm or more to obtain a laminate. The resulting laminate was cut into a 10.0 mm × 10.0 mm measurement sample. The resulting measurement sample was measured using a viscoelasticity measuring device (product name: ARES-G2, manufactured by TA Instruments) under conditions of a heating rate of 10°C / min, a measurement frequency of 10 Hz, and a measurement temperature of 40 to 200°C, and the minimum melt viscosity, which was the lowest value within the measurement temperature range, and the melt viscosity at 60°C were calculated. The results are shown in Table 4.

[0149] [Measurement of Substrate Peel Strength] First, a glass substrate (thickness 0.5 mm) with ITO (indium tin oxide) was prepared. The adhesive film for circuit connection of Example 1 was cut to a width of 2 mm and a length of 23 mm, and the cut adhesive film for circuit connection was placed on the glass substrate so that the first adhesive layer abutted against the ITO surface to obtain a laminate. Next, using a thermal temporary pressure bonding device (LD-06, manufactured by Ohashi Manufacturing Co., Ltd.) consisting of a ceramic stage and a metal pressure bonding head (8 mm x 50 mm) with a built-in heater, the obtained laminate was heated and pressurized in the lamination direction to perform temporary fixation, and a measurement sample was obtained. The heating temperature for temporary fixation was 60 ° C. for the temperature of the first adhesive layer, the pressurization time was 1 second, and the pressurization pressure was 1 MPa. The obtained measurement sample was used to peel the glass substrate using a Tensilon universal testing machine (STA-1150, manufactured by A&D Co., Ltd.) at a peel angle of 90 ° and a peel speed of 50 mm / min, and the substrate peel strength was determined. The results are shown in Table 4.

[0150] [Connection Reliability Test] (Preparation of Circuit Connection Structure) A circuit connection structure was prepared using the adhesive film for circuit connection of Example 1. The adhesive film for circuit connection was cut to a width of 2.0 mm, and the adhesive film for circuit connection was placed on a first circuit member (plastic substrate) so that the first adhesive layer and the first circuit member were in contact. Using a thermal temporary pressure bonding device (LD-06, manufactured by Ohashi Manufacturing Co., Ltd.) consisting of a stage made of a ceramic heater and a tool (8 mm x 50 mm), heating and pressure were applied for 1 second under conditions of 60°C and 1 MPa, so that the adhesive film for circuit connection was attached to the first circuit member, and the PET film on the side of the adhesive film for circuit connection opposite the first circuit member was peeled off. Next, after aligning the bump electrodes of the first circuit member with the circuit electrodes of the second circuit member (IC chip), an 8 mm x 45 mm heat tool was used to apply heat and pressure for 5 seconds under conditions of a connection temperature of 160°C and an area-equivalent pressure of 17 MPa on the bump electrodes, using 50 μm thick Teflon (registered trademark) as a buffer material, to attach the second adhesive layer of the circuit connection adhesive film to the second circuit member, thereby producing a circuit connection structure.

[0151] (Evaluation of Connection Resistance) The connection resistance was evaluated using the circuit connection structure of Example 1. The connection resistance was evaluated by a four-terminal measurement method immediately after the production of the circuit connection structure and after a high-temperature, high-humidity test, and the average value of the connection resistance values ​​measured at 14 locations was used for evaluation. The high-temperature, high-humidity test was performed by treating the circuit connection structure for 500 hours in a high-temperature, high-humidity test chamber at a temperature of 85°C and a humidity of 85% RH. For the measurement, a constant current (1 mA) was applied between the circuit electrode of the first circuit member and the circuit electrode of the second circuit member (connection portion) of the circuit connection structure using a direct current power supply device 6243 manufactured by ADC Corporation. The potential difference at the connection portion during current application was measured at 14 random locations using a digital multimeter (7461A, manufactured by ADC Corporation), and the average value was calculated. Immediately after production of the circuit connection structure, when the connection resistance value was 1.00Ω or less, the connection resistance was evaluated as "S" for superior connection resistance, when the connection resistance value was more than 1.00Ω but less than 1.20Ω, the connection resistance was evaluated as "A", and when the connection resistance value was more than 1.20Ω, the connection resistance was evaluated as "B". After the high temperature and high humidity test, when the connection resistance value was 1.20Ω or less, the connection resistance was evaluated as "S", when the connection resistance value was more than 1.20Ω but less than 1.30Ω, the connection resistance was evaluated as "A", and when the connection resistance value was more than 1.30Ω, the connection resistance was evaluated as "B". The results are shown in Table 4.

[0152] (Examples 2 to 5 and Comparative Example 1) In <Preparation of Second Adhesive Film (Second Adhesive Layer)>, a second varnish composition was prepared and second adhesive layers 2B to 2F were prepared in the same manner as in Example 1, except that the types and / or amounts of the materials to be blended were changed as shown in Table 3. Subsequently, in the same manner as in Example 1, second adhesive layers 2B to 2F were laminated on the first adhesive layer 1A, respectively, to prepare two-layer adhesive films for circuit connection of Examples 2 to 5 and Comparative Example 1. For the adhesive films for circuit connection of Examples 2 to 5 and Comparative Example 1, the thickness, melt viscosity, and substrate peel strength of each adhesive layer were determined in the same manner as in Example 1. Furthermore, circuit connection structures were prepared and connection reliability tests were performed in the same manner as in Example 1. The results are shown in Table 4.

[0153]

[0154]

[0155] As shown in Table 4, the adhesive films for circuit connection of Examples 1 to 5, which had a minimum melt viscosity of 400 Pa s or less, were superior to the adhesive film for circuit connection of Comparative Example 1, which did not satisfy this requirement, particularly in terms of connection resistance after high-temperature, high-humidity testing. These results confirmed that the adhesive film for circuit connection of the present disclosure is capable of forming a circuit connection structure with excellent connection reliability.

[0156] 1...first adhesive layer, 2...second adhesive layer, 3...adhesive component, 4...conductive particles, 5...third adhesive layer, 10A, 10B...adhesive film for circuit connection, 21...first circuit board, 22...first electrode (circuit electrode), 23...first circuit member, 24...second circuit board, 25...second electrode (bump electrode), 26...second circuit member, 27...circuit connection portion, 100...circuit connection structure.

Claims

1. An adhesive film for circuit connection comprising: a first adhesive layer containing conductive particles; and a second adhesive layer provided on the first adhesive layer, wherein the second adhesive layer contains a thermosetting resin component and a thermoplastic resin, the thermosetting resin component includes an alicyclic epoxy compound, and the minimum melt viscosity of the adhesive film for circuit connection is 400 Pa·s or less.

2. The adhesive film for circuit connection according to claim 1, wherein the thermosetting resin component contains, as the alicyclic epoxy compound, a first alicyclic epoxy compound that is liquid at 25°C and a second alicyclic epoxy compound that is solid at 25°C.

3. The adhesive film for circuit connection according to claim 1 or 2, wherein the thermosetting resin component contains a cationically polymerizable compound other than the alicyclic epoxy compound.

4. A method for manufacturing a circuit connection structure, comprising the steps of: interposing an adhesive film for circuit connection according to claim 1 or 2 between a first circuit member having a first electrode and a second circuit member having a second electrode; and thermocompressing the first circuit member and the second circuit member to electrically connect the first electrode and the second electrode to each other.

5. A circuit connection structure comprising: 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, wherein the circuit connection portion comprises a cured product of the adhesive film for circuit connection according to claim 1 or 2.

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