Adhesive film for circuit connection, inorganic filler-containing composition, and circuit connection structure and method for manufacturing the same.

Abstract

This adhesive film for circuit connection, which is an adhesive film containing conductive particles, includes, in the thickness direction of the film, a region A containing an inorganic filler, wherein the region A is formed of a thermosetting composition that contains the inorganic filler, said inorganic filler having a particle diameter D50 at 50% accumulation in a particle size distribution on a volume basis of 0.5-1.0 μm and a particle diameter D95 at 95% accumulation therein of 0.9-2.0 μm.

Description

[Technical Field]

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

[0002] In recent years, the display industry has seen a paradigm shift in display modules, from liquid crystal displays (LCDs) to organic LEDs (Light Emitting Diodes), and this has led to changes in the materials used to construct the panels.

[0003] Conventional liquid crystal displays (LCDs) use glass substrates, and the circuit materials formed on the glass substrate include metals such as aluminum for the underlying circuit layer and ITO (Indium Ti Oxide) for the surface electrodes. On the other hand, while glass substrates also exist for organic LEDs, flexible plastic substrates such as polyimide substrates are increasingly being used as substrates to improve design diversity (curved displays, foldable displays, etc.), and titanium (Ti) is becoming the mainstream material for the circuit materials formed on the plastic substrate. Furthermore, a flexible material such as an adhesive layer and a polyethylene terephthalate (PET) substrate is usually placed on the underside of the polyimide substrate to provide flexibility (see, for example, Patent Document 1).

[0004] Incidentally, in liquid crystal displays, so-called COG (chip on glass) mounting is employed, in which various electronic components such as driver ICs are directly mounted on the glass substrate of the display panel, from the viewpoint of achieving finer pitch, lighter weight, and thinner design. Furthermore, as a COG mounting method, for example, a method is used in which a circuit connection structure is obtained by thermocompressing the liquid crystal driver IC onto the glass substrate via an anisotropically conductive circuit connection adhesive film in which conductive particles are dispersed in the adhesive. [Prior art documents] [Patent Documents]

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

[0006] In organic LEDs, chip-on-plastic (COP) mounting, where driver ICs and other components are directly mounted on a plastic substrate, is increasingly being adopted. However, excessive pressure on the plastic substrate can lead to problems such as deformation of the substrate, causing defects such as deformation, cracking, and disconnection of the Ti circuit on the substrate. Therefore, while COG mounting, which uses adhesive films for circuit connection, typically applies a pressure of 50-100 MPa on the bump electrodes of the IC chip, in COP mounting for organic LEDs, it is preferable to use a low pressure, such as 40 MPa or less, to prevent circuit disconnection. Furthermore, low-pressure mounting in COG mounting also offers the advantage of increased selectivity for connection and peripheral components. For example, it is possible to mount on thin-film glass substrates, which is expected to allow for thinner connection structures.

[0007] However, mounted components manufactured under such low-pressure conditions tend to have high connection resistance between opposing electrodes, making it difficult to obtain sufficient conductivity. Therefore, the inventors investigated how to increase the fluidity of the adhesive between the conductive particles and the electrodes during the thermocompression bonding of the adhesive film. When designing an adhesive with high fluidity, it is considered effective to incorporate inorganic fillers such as silica fillers with relatively large primary particle diameters. However, the inventors' investigation revealed that incorporating commonly available silica fillers can sometimes cause problems with defect detection in automated visual inspection equipment. In order to improve production efficiency, it is desirable to reduce the occurrence of defect detection. Therefore, when investigating the factors causing this problem, it was found that strong indentations (hereinafter also referred to as large indentations), which are visually more noticeable than indentations caused by conductive particles, occur in the wiring area of ​​the mounted area of ​​the circuit connection structure.

[0008] Therefore, the present disclosure aims to provide a circuit connection adhesive film and an inorganic filler-containing composition suitable for the manufacture of such circuit connection components, which can sufficiently ensure conductivity between opposing electrodes of a circuit connection structure even when connecting circuit components at low pressure, and which can sufficiently suppress the occurrence of large indentations that cause defects to be judged by an automated visual inspection device. Furthermore, the present disclosure aims to provide a method for manufacturing a circuit connection structure using the above-mentioned circuit connection adhesive film and a circuit connection structure. [Means for solving the problem]

[0009] To solve the above problems, one aspect of the present disclosure provides an adhesive film for circuit connection containing conductive particles, wherein the adhesive film includes a region A containing an inorganic filler in the thickness direction of the film, and region A is formed from a thermosetting composition containing an inorganic filler having a particle size D50 at 50% accumulation of 0.5 to 1.0 μm and a particle size D95 at 95% accumulation of 0.9 to 2.0 μm in a volume-based particle size distribution.

[0010] According to the above-mentioned side-mounted adhesive film for circuit connection, by containing inorganic fillers having the above-mentioned specific particle size distribution in region A, it is possible to ensure high fluidity while limiting the inclusion of inorganic fillers that cause large indentations within the film. This ensures sufficient conductivity between opposing electrodes of the circuit connection structure even when connecting circuit components at low pressure, and also sufficiently suppresses the occurrence of large indentations that could lead to defects detected by an automated visual inspection device.

[0011] The adhesive film for circuit connection on the side described above includes a region S in the thickness direction of the film that does not contain conductive particles, and region A may be provided in at least a part of region S. In this case, it becomes easier to prevent bridging by conductive particles between circuit electrodes of the adherend (e.g., circuit member) that comes into contact with the adhesive film on the region A side.

[0012] In the adhesive film for circuit connection on the side as described above, the inorganic filler may be silica filler.

[0013] Another aspect of the present disclosure provides an adhesive film for circuit connections comprising: a first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component; and a second adhesive layer provided on the first adhesive layer and containing a second thermosetting resin component, wherein the second adhesive layer is made of an inorganic filler-containing composition containing the second thermosetting resin component and an inorganic filler having a particle size D50 at 50% accumulation of 0.5 to 1.0 μm and a particle size D95 at 95% accumulation of 0.9 to 2.0 μm in a volume-based particle size distribution.

[0014] With the circuit connection adhesive film described above, even when connecting circuit components at low pressure, sufficient conductivity can be ensured between opposing electrodes of the circuit connection structure, and the occurrence of large indentations, which can cause defects in automatic visual inspection devices, can be sufficiently suppressed. Furthermore, with this circuit connection adhesive film, the flow of conductive particles during circuit connection can be suppressed by the photocured material, allowing conductive particles to be efficiently captured on the electrodes, thus making it easier to obtain high connection reliability.

[0015] In the adhesive film for circuit connection on the other side surface, the inorganic filler may be a silica filler.

[0016] The adhesive film for circuit connection on the other side surface may further include a third adhesive layer containing a third thermosetting resin component, which is laminated on the opposite side of the first adhesive layer to the second adhesive layer.

[0017] By including the third adhesive layer, the adhesive film for circuit connection on the other side surface can easily ensure transferability and characteristics in various reliability tests, and can easily improve the margin of the product.

[0018] Another aspect of the present disclosure is a composition used for forming an inorganic filler-containing region in a circuit connection member containing conductive particles and an inorganic filler, which contains an inorganic filler having a particle size D50 at 50% cumulative in a volume-based particle size distribution of 0.5 to 1.0 μm and a particle size D95 at 95% cumulative of 0.9 to 2.0 μm, and provides an inorganic filler-containing composition.

[0019] According to the inorganic filler-containing composition on the other side surface, it is possible to form an inorganic filler-containing region such as region A in the adhesive film for circuit connection on the one side surface, and the second adhesive layer in the adhesive film for circuit connection on the other side surface. Further, even when the inorganic filler-containing composition on the other side surface forms a thin layer by coating, coating defects are less likely to occur, and the coating yield can be increased. Furthermore, the inorganic filler-containing layer formed by the inorganic filler-containing composition on the other side surface can have sufficiently few appearance defects such as scratches.

[0020] In the inorganic filler-containing composition on the other side surface, the inorganic filler may be a silica filler.

[0021] The inorganic filler-containing composition on the other side surface can further contain a thermoplastic resin.

[0022] The inorganic filler-containing compositions described above can be used to form an adhesive layer with a thickness of 10 μm or less.

[0023] Another aspect of the present disclosure provides a method for manufacturing a circuit connection structure, comprising the steps of interposing the above-mentioned circuit connection adhesive film between a first circuit member having a first electrode and a second circuit member having a second electrode, and then heat-pressing the first circuit member and the second circuit member together to electrically connect the first electrode and the second electrode.

[0024] In the method for manufacturing the circuit connection structure described above, one of the first circuit member and the second circuit member may be an IC chip, and the other may be a plastic substrate having electrodes containing Ti.

[0025] Another aspect of the present disclosure provides 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 includes a cured product of the above-mentioned adhesive film for circuit connection.

[0026] In the circuit connection structure of the other aspect described above, one of the first circuit member and the second circuit member may be an IC chip, and the other may be a plastic substrate having electrodes containing Ti. [Effects of the Invention]

[0027] According to this disclosure, it is possible to provide a circuit connection adhesive film and an inorganic filler-containing composition suitable for manufacturing such circuit connection members, which can sufficiently ensure conductivity between opposing electrodes of a circuit connection structure even when connecting circuit members at low pressure, and which can sufficiently suppress the occurrence of large indentations that cause defects to be judged by an automatic visual inspection device. Furthermore, according to this disclosure, it is possible to provide a method for manufacturing a circuit connection structure using the above-mentioned circuit connection adhesive film and a circuit connection structure. [Brief explanation of the drawing]

[0028] [Figure 1] Figure 1 is a schematic cross-sectional view showing an embodiment of an adhesive film for circuit connection. [Figure 2] Figure 2 is a schematic cross-sectional view showing a method for manufacturing an adhesive film for circuit connections. [Figure 3] Figure 3 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. [Figure 4] Figure 4 is a schematic cross-sectional view showing one embodiment of the manufacturing process for a circuit connection structure. [Modes for carrying out the invention]

[0029] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described stepwise in this specification, the upper or lower limit of one step in the numerical range may be replaced with the upper or lower limit of another step in the numerical range. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. Furthermore, the upper and lower limits described individually can be combined in any way. In this specification, "(meth)acrylate" means at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl". Furthermore, "(poly)" means both with and without the prefix "poly". Furthermore, "A or B" means that either A or B is included, or both are included. Furthermore, unless otherwise specified, the materials exemplified below may be used individually or in combination of two or more. The content of each component in a composition refers to the total amount of any multiple substances present in the composition, unless otherwise specified.

[0030] The embodiments of the present invention will be described in detail below, with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments.

[0031] <Adhesive film for circuit connections> The adhesive film for circuit connection of this embodiment contains conductive particles and includes a region A containing inorganic filler in the thickness direction of the film. Region A is formed from a thermosetting composition containing inorganic filler (hereinafter sometimes referred to as "inorganic filler A") whose particle size D50 at 50% accumulation in the volume-based particle size distribution is 0.5 to 1.0 μm and whose particle size D95 at 95% accumulation is 0.9 to 2.0 μm. The thermosetting composition forming region A may include a polymerizable compound and a thermal polymerization initiator.

[0032] The adhesive film for circuit connection in this embodiment includes a region S in the thickness direction of the film that does not contain conductive particles, and region A may be provided in at least a part of region S. From the viewpoint of making it easier to ensure conductivity between opposing electrodes even in low-voltage mounting, the proportion of region A in region S may be 60% or more, 80% or more, or 100%, based on the range in the thickness direction of the film.

[0033] The adhesive film for circuit connection of this embodiment includes a region P in the thickness direction of the film that further contains a cured product of a photocurable resin component, and conductive particles may be dispersed in the region P.

[0034] Figure 1 is a schematic cross-sectional view showing an embodiment of the circuit connection adhesive film of this embodiment. The circuit connection adhesive film 1a shown in Figure 1(a) (hereinafter sometimes simply referred to as "adhesive film 1a") comprises a first adhesive layer 2 containing conductive particles 4, and an adhesive component 5 containing a cured product of a photocurable resin component and a (first) thermosetting resin component, and a second adhesive layer 3 provided on the first adhesive layer 2 and containing a (second) thermosetting resin component. The circuit connection adhesive film 1b shown in Figure 1(b) (hereinafter sometimes simply referred to as "adhesive film 1b") has the same configuration as adhesive film 1a, except that a third adhesive layer containing a (third) thermosetting resin component is laminated on the side of the first adhesive layer 2 opposite to the second adhesive layer 3.

[0035] The circuit connection adhesive film of this embodiment will be described below with reference to Figure 1.

[0036] The adhesive films 1a and 1b have conductive particles 4 dispersed in the first adhesive layer 2. Therefore, the adhesive films 1a and 1b may be anisotropically conductive adhesive films for circuit connections (anisotropically conductive adhesive films). The adhesive films 1a and 1b may be interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and used to electrically connect the first electrode and the second electrode to each other by thermocompression bonding the first and second circuit members.

[0037] <First adhesive layer> The first adhesive layer 2 contains conductive particles 4 (hereinafter sometimes referred to as "component (A)"), a cured product of a photocurable resin component (hereinafter sometimes referred to as "component (B)"), and a thermosetting resin component (hereinafter sometimes referred to as "component (C)"). The first adhesive layer 2 can be obtained, for example, by irradiating a composition layer consisting of a composition containing component (A), component (B), and component (C) with light energy to polymerize the components contained in component (B) and cure component (B). The first adhesive layer 2 contains component (A), an adhesive component 5 containing a cured product of component (B) and component (C). The cured product of component (B) may be a cured product in which component (B) has been completely cured, or a cured product in which a part of component (B) has been cured. Component (C) is a component that can flow when a circuit is connected, and is, for example, an uncured curable resin component.

[0038] (A) Component: Conductive particles Component (A) is not particularly limited as long as it is a conductive particle, and may be metal particles composed of metals such as Au, Ag, Pd, Ni, Cu, or solder, or conductive carbon particles composed of conductive carbon. Component (A) may also be a coated conductive particle comprising a core containing non-conductive glass, ceramic, or plastic (such as polystyrene), and a coating layer containing the above-mentioned metal or conductive carbon that covers the core. Among these, component (A) is preferably a coated conductive particle comprising a core containing metal particles or plastic formed from a heat-meltable metal, and a coating layer containing metal or conductive carbon that covers the core. Since such coated conductive particles can be easily deformed by heating or pressurizing the cured product of the thermosetting resin component, the contact area between the electrodes and component (A) can be increased when electrically connecting electrodes, thereby further improving conductivity between electrodes.

[0039] From the viewpoint of easily exhibiting low resistance to circuits having a Ti surface, conductive particles with palladium plating can be used. In this case, palladium plating can be applied to the outermost surface of the conductive particles. Specifically, conductive particles can be used in which a plastic core body is plated with Ni and the outermost surface is replaced with Pd plating. Such conductive particles may also have insulating fine particles supported on their surface from the viewpoint of preventing short circuits between conductive particles. Furthermore, from the viewpoint of easily exhibiting low resistance, a ceramic core material of 100 nm to 200 nm may be incorporated into the plating process during the Ni plating process, followed by Pd plating, and insulating fine particles may be supported as needed.

[0040] Component (A) may be insulating coated conductive particles comprising the above-mentioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer that covers the surface of the particles and contains an insulating material such as resin. When component (A) is insulating coated conductive particles, even if the content of component (A) is high, the presence of an insulating layer on the surface of the particles can suppress the occurrence of short circuits due to contact between components (A) and can also improve the insulation between adjacent electrode circuits. Component (A) may be one of the above-mentioned conductive particles used alone or in combination of two or more types.

[0041] (A) The maximum particle size of component (A) must be smaller than the minimum electrode spacing (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (A) may be 1.0 μm or more, 2.0 μm or more, or 2.5 μm or more. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (A) may be 20 μm or less, 10 μm or less, or 5 μm or less. In this specification, the particle size of any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is taken as the maximum particle size of component (A). If component (A) has protrusions or is not spherical, the particle size of component (A) is taken as the diameter of the circle circumscribing the conductive particle in the SEM image.

[0042] The average particle size of component (A) may be 1.0 μm or larger, 2.0 μm or larger, or 2.5 μm or larger, from the viewpoint of excellent dispersibility and conductivity. The average particle size of component (A) may be 20 μm or smaller, 10 μm or smaller, or 5 μm or smaller, from the viewpoint of excellent dispersibility and conductivity. In this specification, the particle size of any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle sizes is defined as the average particle size.

[0043] In the first adhesive layer 2, it is preferable that component (A) is uniformly dispersed. From the viewpoint of obtaining stable connection resistance, the particle density of component (A) in the adhesive films 1a and 1b should be 100 particles / mm². 2 More than 1000 pieces / mm 2 More than 3000 pieces / mm 2 Above, or 5000 pieces / mm 2 The above is acceptable. The particle density of component (A) in adhesive films 1a and 1b is 100,000 particles / mm² from the viewpoint of improving the insulation between adjacent electrodes. 2 Below, 70000 pieces / mm 2 Below, 50000 pieces / mm 2 The following, or 30,000 pieces / mm 2 The following is acceptable:

[0044] (A) The content of component (A) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of further improving conductivity. (A) The content of component (A) may be 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the first adhesive layer, from the viewpoint of easily suppressing short circuits. When the content of component (A) is within the above range, the effects of the present invention tend to be significantly exhibited. The content of component (A) in the composition or composition layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0045] (B) Component: Photocurable resin component Component (B) is not particularly limited as long as it is a resin component that hardens by light irradiation, but from the viewpoint of having better connection resistance, it may be a resin component that has radical curability. Component (B) may include, for example, a radical polymerizable compound (hereinafter sometimes referred to as "component (B1)") and a photoradical polymerization initiator (hereinafter sometimes referred to as "component (B2)"). Component (B) may be a component consisting of component (B1) and component (B2).

[0046] (B1) Component: Radical polymerizable compound Component (B1) is a compound that polymerizes by radicals generated from component (B2) upon irradiation with light (e.g., ultraviolet light). Component (B1) may be a monomer, or a polymer (or oligomer) formed by the polymerization of one or more monomers. Component (B1) may be used alone or in combination of multiple components.

[0047] Component (B1) is a compound having radical polymerizable groups that react with radicals. Examples of radical polymerizable groups include (meth)acryloyl groups, vinyl groups, allyl groups, styryl groups, alkenyl groups, alkenylene groups, and maleimide groups. The number of radical polymerizable groups (number of functional groups) in component (B1) may be 2 or more from the viewpoint of easily obtaining the desired melt viscosity after polymerization, further improving the effect of reducing connection resistance, and providing superior connection reliability, and may be 10 or less from the viewpoint of suppressing curing shrinkage during polymerization. Furthermore, in order to balance the crosslinking density and curing shrinkage, in addition to compounds with a number of radical polymerizable groups within the above range, compounds with a number of radical polymerizable groups outside the above range may also be used.

[0048] Component (B1) may, for example, contain a polyfunctional (two- or more functional) (meth)acrylate from the viewpoint of suppressing the flow of conductive particles. The polyfunctional (two- or more functional) (meth)acrylate may be a bifunctional (meth)acrylate, and the bifunctional (meth)acrylate may be a bifunctional aromatic (meth)acrylate.

[0049] Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, and 1,3-butane. Aliphatic (meth)acrylates such as diol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecanedimethanol (meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate;Aromatic (meth)acrylates such as ethoxylated bisphenol A type di(meth)acrylate, propoxylated bisphenol A type di(meth)acrylate, ethoxylated propoxylated bisphenol A type di(meth)acrylate, ethoxylated bisphenol F type di(meth)acrylate, propoxylated bisphenol F type di(meth)acrylate, ethoxylated propoxylated bisphenol F type di(meth)acrylate, ethoxylated fluorene type di(meth)acrylate, propoxylated fluorene type di(meth)acrylate, ethoxylated propoxylated fluorene type di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol Examples include aliphatic (meth)acrylates such as methylmethylol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated propoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexa(meth)acrylate; and aromatic epoxy (meth)acrylates such as bisphenol-type epoxy (meth)acrylate, phenol novolac-type epoxy (meth)acrylate, and cresol novolac-type epoxy (meth)acrylate.

[0050] The content of polyfunctional (two or more functional) (meth)acrylate may be, for example, 40-100% by mass, 50-100% by mass, or 60-100% by mass, based on the total mass of component (B1), from the viewpoint of achieving both the effect of reducing connection resistance and suppressing particle flow.

[0051] Component (B1) may further contain monofunctional (meth)acrylates in addition to polyfunctional (bifunctional or more) (meth)acrylates. Examples of monofunctional (meth)acrylates include (meth)acrylic acid; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octylheptyl (meth)acrylate, nonyl (meth)acrylate, Decyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, mono(2-(meth)acryloyl Aliphatic (meth)acrylates such as methyl succinate; benzyl (meth)acrylate, phenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, 1-naphthoxyethyl (meth)acrylate, 2-naphthoxyethyl (meth)acrylate, phenoxymethyl Aromatic (meth)acrylates such as ethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate, and 2-hydroxy-3-(2-naphthoxy)propyl (meth)acrylate;Examples include (meth)acrylates having epoxy groups such as glycidyl (meth)acrylate, (meth)acrylates having alicyclic epoxy groups such as 3,4-epoxycyclohexylmethyl (meth)acrylate, and (meth)acrylates having oxetanyl groups such as (3-ethyloxetan-3-yl)methyl (meth)acrylate.

[0052] The content of monofunctional (meth)acrylate may be, for example, 0-60% by mass, 0-50% by mass, or 0-40% by mass, based on the total mass of component (B1).

[0053] The cured product of component (B) may have polymerizable groups that react with a factor other than a radical. The polymerizable groups that react with a factor other than a radical may be cationic polymerizable groups that react with a cation. Examples of cationic polymerizable groups include epoxy groups such as glycidyl groups, alicyclic epoxy groups such as epoxycyclohexylmethyl groups, and oxetanyl groups such as ethyloxetanylmethyl groups. The cured product of component (B) having polymerizable groups that react with a factor other than a radical can be introduced by using a (meth)acrylate having polymerizable groups that react with a factor other than a radical, such as an epoxy group (meth)acrylate, an alicyclic epoxy group (meth)acrylate, or an oxetanyl group (meth)acrylate, as component (B). The mass ratio of (meth)acrylate having polymerizable groups reacting by means other than radicals to the total mass of component (B1) (mass of (meth)acrylate having polymerizable groups reacting by means other than radicals (amount charged) / total mass of component (B1) (amount charged)) may be, for example, 0 to 0.7, 0 to 0.5, or 0 to 0.3 from the viewpoint of improving reliability.

[0054] Component (B1) may contain polyfunctional (two or more functional) and monofunctional (meth)acrylates, as well as other radical polymerizable compounds. Examples of other radical polymerizable compounds include maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadiimide derivatives, and the like. The content of other radical polymerizable compounds may be, for example, 0 to 40% by mass based on the total mass of component (B1).

[0055] (B2) Component: Photoradical polymerization initiator Component (B2) is a photopolymerization initiator that generates radicals upon irradiation with light containing wavelengths in the range of 150 to 750 nm, preferably light containing wavelengths in the range of 254 to 405 nm, and more preferably light containing a wavelength of 365 nm (e.g., ultraviolet light). Component (B2) may be used alone or in combination of multiple components.

[0056] Component (B2) decomposes upon exposure to light, generating free radicals. In other words, component (B2) is a compound that generates radicals upon application of external light energy. Component (B2) may be a compound having structures such as an oxime ester structure, a bisimidazole structure, an acridine structure, an α-aminoalkylphenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzyldimethyl ketal structure, or an α-hydroxyalkylphenone structure. Component (B2) may be used alone or in combination of multiple components. From the viewpoint of easily obtaining the desired melt viscosity and being superior in reducing connection resistance, component (B2) may be a compound having at least one structure selected from the group consisting of an oxime ester structure, an α-aminoalkylphenone structure, and an acylphosphine oxide structure.

[0057] Specific examples of compounds having an oxime ester structure include 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-o-benzoyloxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime, 1,2-octanedione,1-[4-(phenylthio)phenyl-,2-(o-benzoyloxime)], etanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(o-acetyloxime), and others.

[0058] Specific examples of compounds having an α-aminoalkylphenone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-morpholinophenyl)-butanone-1.

[0059] Specific examples of compounds having an acylphosphine oxide structure include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0060] The content of component (B2) may be, for example, 0.1 to 10 parts by mass, 0.3 to 7 parts by mass, or 0.5 to 5 parts by mass per 100 parts by mass of component (B1), from the viewpoint of suppressing the flow of conductive particles.

[0061] The content of cured component (B) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of suppressing the flow of conductive particles. The content of cured component (B) may be 50% by mass or less, 40% by mass or less, or 30% by mass or less, based on the total mass of the first adhesive layer, from the viewpoint of exhibiting low resistance in low-pressure mounting. The content of component (B) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0062] (C) Component: Thermosetting resin component Component (C) may include, for example, a cationic polymerizable compound (hereinafter sometimes referred to as "component (C1)") and a thermal cationic polymerization initiator (hereinafter sometimes referred to as "component (C2)"). Component (C) may be a component consisting of component (C1) and component (C2). The first thermosetting resin component and the second thermosetting resin component refer to the thermosetting resin components contained in the first adhesive layer and the second adhesive layer, respectively. The types, combinations, and content of components (e.g., component (C1), component (C2), etc.) contained in the first thermosetting resin component and the second thermosetting resin component may be the same or different.

[0063] (C1) Component: Cationic polymerizable compound Component (C1) is a compound that crosslinks by reacting with component (C2) by heat. Note that component (C1) means a compound that does not have radical polymerizable groups that react with radicals, and component (C1) is not included in component (B1). Component (C1) may be a compound having one or more ring-opening polymerizable cyclic ether groups in its molecule, from the viewpoint of further improving the effect of reducing connection resistance and providing superior connection reliability. Component (C1) may be used alone or in combination of multiple types. As a compound having one or more ring-opening polymerizable cyclic ether groups in its molecule, for example, it may be at least one selected from the group consisting of oxetane compounds and alicyclic epoxy compounds. From the viewpoint of easily obtaining the desired melt viscosity, it is preferable that component (C1) contains both at least one oxetane compound and at least one alicyclic epoxy compound.

[0064] The oxetane compound used as component (C1) is not particularly limited as long as it has an oxetanyl group and does not have a radical polymerizable group. Examples of commercially available oxetane compounds include ETERNACOLL OXBP (trade name, manufactured by Ube Industries, Ltd.), OXSQ, OXT-121, OXT-221, OXT-101, and OXT-212 (trade names, manufactured by Toagosei Co., Ltd.). These may be used individually or in combination of multiple compounds.

[0065] The alicyclic epoxy compound used as component (C1) is not particularly limited as long as it has an alicyclic epoxy group (e.g., an epoxycyclohexyl group) and does not have a radical polymerizable group. Examples of commercially available alicyclic epoxy compounds include EHPE3150, EHPE3150CE, Celoxide 8010, Celoxide 2021P, and Celoxide 2081 (trade names, manufactured by Daicel Corporation). These may be used individually or in combination.

[0066] (C2) Component: Thermal cationic polymerization initiator (Component (C2) is a thermal polymerization initiator that generates an acid or the like upon heating to initiate polymerization. Component (C2) may be a salt compound composed of a cation and an anion. Component (C2) is, for example, BF4 - , BR4 - (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups), PF6 - , SbF6 - , AsF6 - and other onium salts such as sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, anilinium salts having anions such as these. These may be used alone or in combination of two or more.

[0067] (From the viewpoint of storage stability, component (C2) is, for example, an anion containing boron as a constituent element, that is, BF4 - or BR4 - (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups)) and may be a salt compound. The anion containing boron as a constituent element may be BR4 - , and more specifically, may be tetrakis(pentafluorophenyl)borate.

[0068] Since the onium salt as component (C2) has resistance to substances that can cause curing inhibition for cationic curing, it may be, for example, an anilinium salt. Examples of anilinium salt compounds include N,N-dialkylanilinium salts such as N,N-dimethylanilinium salt and N,N-diethylanilinium salt.

[0069] (Component (C2) may be an anilinium salt having an anion containing boron as a constituent element. Examples of commercially available products of such salt compounds include CXC-1821 (trade name, manufactured by King Industries) and the like.

[0070] The content of component (C2) may be, for example, 0.1 to 25 parts by mass, 1 to 20 parts by mass, 3 to 18 parts by mass, or 5 to 15 parts by mass per 100 parts by mass of component (C1), from the viewpoint of ensuring the formability and curability of the adhesive film for forming the first adhesive layer.

[0071] The content of component (C) may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the first adhesive layer, from the viewpoint of ensuring the curability of the adhesive film for forming the first adhesive layer. The content of component (C) may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the first adhesive layer, from the viewpoint of ensuring the formability of the adhesive film for forming the first adhesive layer. The content of component (C) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0072] [Other ingredients] The first adhesive layer 2 may further contain other components in addition to component (A), the cured product of component (B), and component (C). Examples of other components include thermoplastic resin (hereinafter sometimes referred to as "component (D)"), coupling agent (hereinafter sometimes referred to as "component (E)"), and filler (hereinafter sometimes referred to as "component (F)").

[0073] Component (D) can be a resin that functions as a film-forming component, such as phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester urethane resin, acrylic rubber, epoxy resin (solid at 25°C), etc. These may be used individually or in combination. A composition containing components (A), (B), and (C) can be further enriched with component (D) to easily form a composition layer (and further, a first adhesive layer 2) from the composition. Among these, component (D) may be, for example, a phenoxy resin.

[0074] The weight-average molecular weight (Mw) of component (D) may be, for example, 5000-200000, 10000-100000, 20000-80000, or 40000-60000, from the viewpoint of resin excludability during mounting. Note that Mw refers to the value measured by gel permeation chromatography (GPC) and converted using a calibration curve with standard polystyrene.

[0075] The content of component (D) may be 1% by mass or more, 5% by mass or more, 10% by mass or more, or 20% by mass or more, and 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. The content of component (D) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0076] Examples of component (E) include silane coupling agents having organic functional groups such as (meth)acryloyl groups, mercapto groups, amino groups, imidazole groups, and epoxy groups; silane compounds such as tetraalkoxysilanes; tetraalkoxytitanate derivatives; and polydialkyltitanate derivatives. These may be used individually or in combination. The adhesion of the first adhesive layer 2 can be further improved by containing component (E). Component (E) may be, for example, a silane coupling agent. The content of component (E) may be 0.1 to 10% by mass based on the total mass of the first adhesive layer. The content of component (E) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) may be the same as the above range.

[0077] Examples of component (F) include non-conductive fillers (e.g., non-conductive particles). Component (F) may be either an inorganic filler or an organic filler. Examples of inorganic fillers include metal oxide nanoparticles such as silica nanoparticles, alumina nanoparticles, silica-alumina nanoparticles, titania nanoparticles, and zirconia nanoparticles; and inorganic nanoparticles such as metal nitride nanoparticles. Examples of organic fillers include organic nanoparticles such as silicone nanoparticles, methacrylate-butadiene-styrene nanoparticles, acrylic-silicone nanoparticles, polyamide nanoparticles, and polyimide nanoparticles. These may be used individually or in combination. Component (F) can be appropriately blended within a range that does not impair the effects of the present invention, and the content of component (F) in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) can also be appropriately set within a range that does not impair the effects of the present invention.

[0078] [Other additives] The first adhesive layer 2 may further contain other additives such as softeners, accelerators, degradation inhibitors, colorants, flame retardants, and thixotropic agents. The content of these other additives may be, for example, 0.1 to 10% by mass, based on the total mass of the first adhesive layer. The content of other additives in the composition or composition layer for forming the first adhesive layer (based on the total mass of the composition or composition layer) may be the same as the range described above.

[0079] The thickness d1 of the first adhesive layer 2 may be 0.1 times or more, 0.2 times or more, or 0.3 times or more of the average particle size of the conductive particles 4, from the viewpoint of making it easier for the conductive particles 4 to be captured between opposing electrodes and further reducing connection resistance. The thickness d1 of the first adhesive layer 2 may be 0.8 times or less, or 0.7 times or less of the average particle size of the conductive particles 4, from the viewpoint of making the conductive particles more easily crushed when they are sandwiched between opposing electrodes during heat compression bonding and further reducing connection resistance. From these viewpoints, the thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the average particle size of the conductive particles 4. Note that the thickness d1 of the first adhesive layer 2 refers to the thickness of the first adhesive layer located in the spaced portion between adjacent conductive particles 4, 4.

[0080] When the thickness d1 of the first adhesive layer 2 and the average particle size of the conductive particles 4 satisfy the above relationship, for example, as shown in Figure 1, a portion of the conductive particles 4 in the first adhesive layer 2 may protrude from the first adhesive layer 2 towards the second adhesive layer 3. In this case, the boundary S between the first adhesive layer 2 and the second adhesive layer 3 is located at the spaced portion between adjacent conductive particles 4, 4. The above relationship may be satisfied without the conductive particles 4 in the first adhesive layer 2 protruding from the first adhesive layer 2 towards the second adhesive layer 3, by the existence of the boundary S on the conductive particles along the surface of the conductive particles. The conductive particles 4 are not exposed on the surface 2a of the first adhesive layer 2 opposite to the second adhesive layer 3, and the opposite surface 2a may be a flat surface.

[0081] The relationship between the thickness d1 of the first adhesive layer 2 and the maximum particle size of the conductive particles 4 may be the same as described above. For example, the thickness d1 of the first adhesive layer 2 may be 0.1 to 0.8 times, 0.2 to 0.8 times, or 0.3 to 0.7 times the maximum particle size of the conductive particles 4.

[0082] The thickness d1 of the first adhesive layer 2 may be, for example, 5.0 μm or less. The thickness d1 of the first adhesive layer 2 may also be 4.5 μm or less or 4.0 μm or less. By having a thickness d1 of 5.0 μm or less of the first adhesive layer 2, conductive particles can be captured more efficiently during circuit connection. The thickness d1 of the first adhesive layer 2 may be, for example, 0.1 μm or more, 0.5 μm or more, or 0.7 μm or more. The thickness d1 of the first adhesive layer 2 can be determined, for example, by sandwiching an adhesive film between two pieces of glass (thickness: about 1 mm), casting a resin composition consisting of 100 g of bisphenol A type epoxy resin (product name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of diethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.), performing cross-sectional polishing using a polishing machine, and measuring using a scanning electron microscope (SEM, product name: SE-8010, manufactured by Hitachi High-Tech Science Corporation). Furthermore, as shown in Figure 1, if a portion of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (for example, protruding toward the second adhesive layer 3), the distance from the surface 2a of the first adhesive layer 2 opposite to the second adhesive layer 3 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located at the spaced portion between adjacent conductive particles 4,4 (the distance shown as d1 in Figure 1) is the thickness of the first adhesive layer 2, and the exposed portion of the conductive particles 4 is not included in the thickness of the first adhesive layer 2. The length of the exposed portion of the conductive particles 4 may be, for example, 0.1 μm or more and 5.0 μm or less.

[0083] <Second adhesive layer> The second adhesive layer 3 may contain components (C) and (F). Since components (C1) and (C2) used in component (C) (i.e., the second thermosetting resin component) in the second adhesive layer 3 are the same as components (C1) and (C2) used in component (C) (i.e., the first thermosetting resin component) in the first adhesive layer 2, a detailed explanation is omitted here. The second thermosetting resin component may be the same as or different from the first thermosetting resin component.

[0084] (C) The content of component (C) may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the second adhesive layer, from the viewpoint of maintaining reliability. (C) The content of component (C) may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the second adhesive layer, from the viewpoint of preventing resin leakage defects in reels, which is one form of supply.

[0085] The second adhesive layer 3 may contain an inorganic filler as component (F). Even when connecting circuit members at low pressure, sufficient conductivity can be ensured between opposing electrodes of the circuit connection structure, and the occurrence of large indentations, which can be a cause of defects in automatic visual inspection devices, can be achieved by forming the second adhesive layer 3 from a thermosetting composition containing an inorganic filler having a particle size D50 of 0.5 to 1.0 μm at 50% accumulation and a particle size D95 of 0.9 to 2.0 μm at 95% accumulation in the volume-based particle size distribution.

[0086] As an inorganic filler, silica fillers such as silica nanoparticles can be used from the viewpoint of improving reliability. The silica content in the silica filler may be 99% by mass or more, or 100% by mass, based on the total amount of silica filler.

[0087] Inorganic fillers having the above-described volume-based particle size distribution can be obtained, for example, by preparing an inorganic filler containing inorganic particles with a primary particle size of 0.3 to 0.7 μm, or an inorganic filler with a volume-average particle size of 1.0 to 2.0 μm, and removing inorganic particles with a particle size of 2.0 μm or larger by known classification means such as air classification, filtration using filter paper or capsule filters.

[0088] From the viewpoint of ensuring fluidity, the inorganic filler D50 may be 0.5 to 1.0 μm, 0.6 to 0.9 μm, or 0.7 to 0.8 μm. Furthermore, from the viewpoint of suppressing the occurrence of large indentations, the inorganic filler D95 may be 0.9 to 2.0 μm, 1.0 to 1.8 μm, or 1.1 to 1.6 μm.

[0089] In order to facilitate conductivity between opposing electrodes even in low-voltage mounting and to ensure film properties as a tape-like product, the content of the inorganic filler in the second adhesive layer 3 or the thermosetting composition forming it may be 10 to 70% by mass, 20 to 60% by mass, or 30 to 50% by mass, based on the total mass of the second adhesive layer or thermosetting composition.

[0090] The second adhesive layer 3 may further contain other components and other additives of the first adhesive layer 2. Preferred embodiments of the other components and other additives are the same as those of the preferred embodiment of the first adhesive layer 2.

[0091] The content of component (D) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, and may be 80% by mass or less, 60% by mass or less, or 40% by mass or less, based on the total mass of the second adhesive layer.

[0092] The content of component (E) may be 0.1 to 10% by mass, based on the total mass of the second adhesive layer.

[0093] The content of other additives may be, for example, 0.1 to 10% by mass, based on the total mass of the second adhesive layer.

[0094] The thickness d2 of the second adhesive layer 3 may be set appropriately according to the height of the electrodes of the circuit members to be bonded. The thickness d2 of the second adhesive layer 3 may be 5 μm or more, 7 μm or more, 15 μm or less, or 11 μm or less, from the viewpoint of being able to sufficiently fill the space between electrodes and seal the electrodes and obtain better connection reliability. The thickness d2 of the second adhesive layer 3 can be determined, for example, by the same method as the measurement method for the thickness d1 of the first adhesive layer 2. Furthermore, if a part of the conductive particles 4 is exposed from the surface of the first adhesive layer 2 (for example, protruding toward the second adhesive layer 3), the distance from the surface 3a of the second adhesive layer 3 opposite to the first adhesive layer 2 to the boundary S between the first adhesive layer 2 and the second adhesive layer 3 located in the spaced portion between adjacent conductive particles 4, 4 (the distance shown as d2 in Figure 1) is the thickness of the second adhesive layer 3.

[0095] The third adhesive layer 6 may contain component (C). Since components (C1) and (C2) used in component (C) in the third adhesive layer (i.e., the third thermosetting resin component) are the same as components (C1) and (C2) used in component (C) in the first adhesive layer 2 (i.e., the first thermosetting resin component), a detailed explanation is omitted here. The third thermosetting resin component may be the same as or different from the first thermosetting resin component. The third thermosetting resin component may be the same as or different from the second thermosetting resin component.

[0096] The content of component (C) may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the third adhesive layer, from the viewpoint of providing good transferability and peel resistance. The content of component (C) may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the third adhesive layer, from the viewpoint of providing good half-cutability and blocking resistance (suppression of resin seepage from the reel).

[0097] The third adhesive layer may further contain other components and other additives of the first adhesive layer 2.

[0098] The content of component (D) may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and may be 80% by mass or less, 70% by mass or less, or 60% by mass or less, based on the total mass of the third adhesive layer.

[0099] The content of component (E) may be 0.1 to 10% by mass, based on the total mass of the third adhesive layer.

[0100] The content of component (F) can be appropriately set within a range that does not impair the effects of the present invention.

[0101] The content of other additives may be, for example, 0.1 to 10% by mass, based on the total mass of the third adhesive layer.

[0102] The thickness of the third adhesive layer may be set appropriately according to the minimum melt viscosity of the adhesive film, the height of the electrodes of the circuit members to be bonded, etc. Preferably, the thickness of the third adhesive layer is smaller than the thickness d2 of the second adhesive layer 3. The thickness of the third adhesive layer may be 0.2 μm or more and 3.0 μm or less, from the viewpoint of being able to sufficiently fill the space between electrodes and seal the electrodes and obtain better connection reliability. The thickness of the third adhesive layer can be determined, for example, by the same method as the measurement method for the thickness d1 of the first adhesive layer 2.

[0103] The thickness of the adhesive films 1a and 1b (the sum of the thicknesses of all the layers constituting the adhesive films 1a and 1b; in Figure 1(a), this is the sum of the thickness d1 of the first adhesive layer 2 and the thickness d2 of the second adhesive layer 3; and in Figure 1(b), this is the sum of the thickness of the third adhesive layer as well) may be, for example, 5 μm or more or 8 μm or more, and 30 μm or less or 20 μm or less.

[0104] In adhesive films 1a and 1b, for example, the first adhesive layer may be the region P described above. In this case, the range of region P in the thickness direction of the film can be the same as the thickness d1 of the first adhesive layer 2 described above. Region P can be formed by a composition obtained by removing conductive particles from the composition for forming the first adhesive layer described above.

[0105] In the adhesive films 1a and 1b, for example, the second adhesive layer may be in the region A described above.

[0106] If the second adhesive layer is region A, the extent of region A in the thickness direction of the film can be the same as the thickness d2 of the second adhesive layer 3 described above. Region A can be formed by the composition for forming the second adhesive layer described above.

[0107] In adhesive films 1a and 1b, the second adhesive layer, or the second and third adhesive layers, may be regions S that do not contain conductive particles. Region S can be formed by the compositions for forming the second adhesive layer and the composition for forming the third adhesive layer described above.

[0108] In adhesive films 1a and 1b, the second adhesive layer contains an inorganic filler whose particle size D50 at 50% accumulation in the volume-based particle size distribution is 0.5 to 1.0 μm, and whose particle size D95 at 95% accumulation is 0.9 to 2.0 μm, but which may not be included in the first and third adhesive layers.

[0109] The minimum melt viscosity of adhesive films 1a and 1b is 450 to 1600 Pa·s. The minimum melt viscosity of adhesive films 1a and 1b may be 500 Pa·s or more, 600 Pa·s or more, 700 Pa·s or more, or 800 Pa·s or more. If the minimum melt viscosity of adhesive films 1a and 1b is 450 Pa·s or more, deformation of the plastic substrate during thermocompression bonding can be suppressed, and circuit disconnection can be prevented. The minimum melt viscosity of adhesive films 1a and 1b may be 1500 Pa·s or less, 1400 Pa·s or less, 1300 Pa·s or less, 1200 Pa·s or less, 1100 Pa·s or less, or 1000 Pa·s or less. If the minimum melt viscosity of adhesive films 1a and 1b is 1600 Pa·s or less, the decrease in resin excludability during circuit connection can be suppressed, thereby reducing the connection resistance between opposing electrodes of the circuit connection structure and ensuring good conductivity characteristics. The minimum melt viscosity of the adhesive film can be determined, for example, by the following method. (Method for measuring minimum melt viscosity) Each adhesive film is laminated using a laminator to obtain a laminate with a thickness of 200 μm or more. The release-treated PET is peeled off from the obtained laminate and cut into 10.0 mm × 10.0 mm pieces to obtain a measurement sample. The minimum melt viscosity of the obtained measurement sample is measured using a viscoelasticity analyzer (product name: ARES-G2, manufactured by TA Instruments, heating rate: 10°C / min).

[0110] In adhesive films 1a and 1b, the second adhesive layer 3 is usually thicker than the first adhesive layer 2. Therefore, the minimum melt viscosity of adhesive films 1a and 1b tends to vary depending on the second adhesive layer 3. The minimum melt viscosity of adhesive films 1a and 1b can be adjusted, for example, by adjusting the type and content of the constituent components (especially component (D)) contained in the second adhesive layer 3. Alternatively, the minimum melt viscosity of adhesive films 1a and 1b can also be adjusted by incorporating the inorganic filler A mentioned above as component (F). By incorporating inorganic filler A into the second adhesive layer 3, the minimum melt viscosity can be reduced while sufficiently suppressing the occurrence of large indentations.

[0111] In adhesive films 1a and 1b, conductive particles 4 are dispersed in the first adhesive layer 2. Therefore, adhesive films 1a and 1b are anisotropically conductive adhesive films having anisotropic conductivity. Adhesive films 1a and 1b are interposed between a first circuit member having a first electrode and a second circuit member having a second electrode, and are used to electrically connect the first electrode and the second electrode to each other by thermocompression bonding the first and second circuit members.

[0112] With adhesive films 1a and 1b, by designating the second adhesive layer 3 as region A, it is possible to ensure conductivity between opposing electrodes of the circuit connection structure even when connecting circuit components at low pressure, and to sufficiently suppress the occurrence of large indentations that could be a cause of defect detection by an automated visual inspection device.

[0113] The circuit connection adhesive film of this embodiment can be suitably used for COP mounting. More specifically, it can be suitably used for connecting a plastic substrate on which circuit electrodes (e.g., electrodes containing Ti) are formed in an organic EL display to an IC chip such as a driver IC.

[0114] <Method for manufacturing adhesive film for circuit connections> A method for manufacturing an adhesive film for circuit connections according to one embodiment may include the steps of: irradiating a composition layer, which is made up of a composition containing, for example, component (A), component (B), and component (C) (a first thermosetting resin component), and optionally other components, with light to form a first adhesive layer (first step); and laminating a second adhesive layer containing component (C) (a second thermosetting resin component), inorganic filler A, and optionally other components, on the first adhesive layer (second step). The manufacturing method may further include the step of laminating a third adhesive layer containing component (C) (a third thermosetting resin component), and optionally inorganic filler A and other components, on the side of the first adhesive layer opposite to the second adhesive layer (third step). In this case, the second step may be performed first, or the third step may be performed first. If the third step is performed first, the third adhesive layer is laminated on the side of the first adhesive layer opposite to the side on which the second adhesive layer is to be laminated. Figure 2 is a schematic cross-sectional view showing a manufacturing method comprising the steps described above.

[0115] In the first step, for example, a composition containing components (A), (B), and (C), as well as additives added as needed, is dissolved or dispersed in an organic solvent by stirring, mixing, kneading, etc., to prepare a varnish composition (a varnish-like first adhesive composition). Then, the varnish composition is applied to a substrate that has been treated with a mold release agent using a knife coater, roll coater, applicator, comma coater, die coater, etc., and the organic solvent is evaporated by heating to form a composition layer on the substrate. At this time, the thickness of the final obtained first adhesive layer (first adhesive film) can be adjusted by adjusting the amount of varnish composition applied. Subsequently, the composition layer is irradiated with light to cure component (B) in the composition layer and form a first adhesive layer on the substrate. The first adhesive layer can be called a first adhesive film. Through the first step, the first adhesive layer 2 provided on the substrate 22, as shown in Figure 2(a), can be prepared.

[0116] The organic solvent used in the preparation of the varnish composition is not particularly limited as long as it has the property of uniformly dissolving or dispersing each component. Examples of such organic solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These organic solvents can be used individually or in combination of two or more. Stirring, mixing, or kneading during the preparation of the varnish composition can be carried out using, for example, a stirrer, a 3-roll mill, a ball mill, a bead mill, a homodisper, etc.

[0117] The substrate is not particularly limited as long as it has heat resistance that can withstand the heating conditions when volatilizing organic solvents. Examples of such substrates include stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymers, etc. (for example, films).

[0118] The heating conditions for volatilizing the organic solvent from the varnish composition applied to the substrate can be appropriately set according to the organic solvent used. For example, the heating conditions may be 40 to 120°C for 0.1 to 10 minutes.

[0119] Some of the solvent may remain in the first adhesive layer without being removed. The solvent content in the first adhesive layer may be, for example, 10% by mass or less based on the total mass of the first adhesive layer.

[0120] Furthermore, the content of component (B) in the varnish composition may be 10% by mass or more and less than 60% by mass, based on the total amount of component (A) and components other than organic solvents in the varnish composition. In this case, the effect of suppressing the flow of conductive particles is more easily obtained, and coating while maintaining a good appearance is easier.

[0121] For light irradiation during the curing process, it is preferable to use irradiation light (e.g., ultraviolet light) that includes wavelengths in the range of 150 to 750 nm. Light irradiation can be performed using, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, metal halide lamps, LED light sources, etc. The integrated light intensity of the light irradiation can be set as appropriate, for example, 500 to 3000 mJ / cm². 2 That's fine.

[0122] The second step is to laminate a second adhesive layer on the first adhesive layer. In the second step, for example, first, a second adhesive layer is formed on the substrate in the same manner as in the first step, except that component (C) and inorganic filler A are used and light irradiation is not performed, thereby obtaining a second adhesive film. For example, a second adhesive layer 3 provided on the substrate 20 as shown in Figure 2(a) can be prepared. Next, the second adhesive layer can be laminated on the first adhesive layer by bonding the first adhesive film and the second adhesive film together (see Figures 2(a) and (b)). Alternatively, in the second step, the second adhesive layer can also be laminated on the first adhesive layer by applying a varnish composition (a varnish-like second adhesive composition) obtained using component (C), inorganic filler A, and other additives added as needed onto the first adhesive layer, and then volatilizing the organic solvent.

[0123] Methods for bonding the first adhesive film and the second adhesive film include, for example, heat pressing, roll lamination, and vacuum lamination. Lamination can be carried out, for example, under temperature conditions of 0 to 80°C.

[0124] Some of the solvent may remain in the second adhesive layer without being removed. The solvent content in the second adhesive layer may be, for example, 10% by mass or less based on the total mass of the second adhesive layer.

[0125] The third step is to laminate the third adhesive layer on the side of the first adhesive layer opposite to the second adhesive layer. In the third step, for example, first, a third adhesive layer is formed on the substrate in the same manner as in the second step to obtain a third adhesive film. For example, a third adhesive layer 6 provided on the substrate 24, as shown in Figure 2(c), can be prepared. Next, the third adhesive layer can be laminated on the side of the first adhesive layer opposite to the second adhesive layer by bonding the third adhesive film to the side of the first adhesive film opposite to the second adhesive film (see Figure 2(c)). Alternatively, in the third step, for example, the third adhesive layer can also be laminated on the first adhesive layer by applying a varnish composition (a varnish-like third adhesive composition) to the side of the first adhesive layer opposite to the second adhesive layer in the same manner as in the second step, and then volatilizing the organic solvent. The bonding method and conditions are the same as in the second step.

[0126] Some of the solvent may remain in the third adhesive layer without being removed. The solvent content in the third adhesive layer may be, for example, 10% by mass or less based on the total mass of the third adhesive layer.

[0127] <Inorganic filler-containing composition> The inorganic filler-containing composition of this embodiment contains an inorganic filler in which the particle size D50 at 50% accumulation in the volume-based particle size distribution is 0.5 to 1.0 μm, and the particle size D95 at 95% accumulation is 0.9 to 2.0 μm. The inorganic filler can be the same as the inorganic filler A described above.

[0128] The inorganic filler-containing composition of this embodiment can be used to form an inorganic filler-containing region in a circuit connection member containing conductive particles and an inorganic filler. An example of a circuit connection member is the circuit connection adhesive film described above. According to the inorganic filler-containing composition of this embodiment, the inorganic filler-containing region can be formed as region A described above and the second adhesive layer.

[0129] The composition of the inorganic filler-containing composition in this embodiment can be set in the same way as the composition of the second adhesive layer described above. For example, the composition may further contain a thermoplastic resin.

[0130] The inorganic filler-containing composition of this embodiment may be a varnish composition (varnish-like inorganic filler-containing composition) containing the organic solvent described above.

[0131] The inorganic filler-containing composition of this embodiment can be used to form an adhesive layer with a thickness of 10 μm or less, 9 to 4 μm, or 8 to 5 μm. According to the inorganic filler-containing composition of this embodiment, even when coating with such design thicknesses, appearance defects such as scratches are less likely to occur, and a high coating yield can be obtained.

[0132] <Circuit connection structure and method for manufacturing the same> The following describes a circuit connection structure using the above-mentioned circuit connection adhesive film 1a as the circuit connection material, and a method for manufacturing the same.

[0133] Figure 3 is a schematic cross-sectional view showing one embodiment of a circuit connection structure. As shown in Figure 3, the circuit connection structure 10 includes a first circuit board 11 and a first circuit member 13 having a first electrode 12 formed on the main surface 11a of the first circuit board 11, a second circuit board 14 and a second circuit member 16 having a second electrode 15 formed on the main surface 14a of the second circuit board 14, and a circuit connection portion 17 disposed between the first circuit member 13 and the second circuit member 16, which electrically connects the first electrode 12 and the second electrode 15 to each other.

[0134] The first circuit member 13 and the second circuit member 16 may be the same or different from each other. The first circuit member 13 and the second circuit member 16 may be a glass or plastic substrate on which circuit electrodes are formed; a printed circuit board; a ceramic circuit board; a flexible circuit board; an IC chip such as a driving IC, etc. The first circuit board 11 and the second circuit board 14 may be made of 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. The first circuit board 11 may be a plastic substrate. The first circuit member 13 may be, for example, a plastic substrate on which circuit electrodes are formed (a plastic substrate made of an organic material such as polyimide, polycarbonate, polyethylene terephthalate, or cycloolefin polymer), and the second circuit member 16 may be, for example, an IC chip such as a driving IC. The plastic substrate on which the electrodes are formed may be a plastic substrate on which a display area is formed by regularly arranging, for example, a pixel driving circuit such as an organic TFT or a plurality of organic EL elements R, G, B in a matrix.

[0135] The first electrode 12 and the second electrode 15 may be electrodes containing metals such as gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, and titanium, or oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium zinc oxide (IGZO). The first electrode 12 and the second electrode 15 may also be electrodes formed by laminating two or more of these metals, oxides, etc. The electrodes formed by laminating two or more types may have two or more layers, or three or more layers. If the first circuit member 13 is a plastic substrate, the first electrode 12 may be an electrode containing Ti, and more specifically, an electrode having a titanium layer on its outermost surface. The first electrode 12 and the second electrode 15 may be circuit electrodes or bump electrodes. At least one of the first electrode 12 and the second electrode 15 may be a bump electrode. In Figure 3, the first electrode 12 is a circuit electrode and the second electrode 15 is a bump electrode.

[0136] The circuit connection portion 17 includes the cured product of the adhesive film 1a described above. The circuit connection portion 17 may consist of the cured product of the adhesive film 1a described above. The circuit connection portion 17 includes, for example, a first region 18 located on the first circuit member 13 side in the direction in which the first circuit member 13 and the second circuit member 16 face each other (hereinafter referred to as the "facing direction"), which consists of cured products of component (B) and component (C), other than the conductive particles 4 in the first adhesive layer described above; a second region 19 located on the second circuit member 16 side in the facing direction, which consists of cured products of component (C), etc., in the second adhesive layer described above; and conductive particles 4 interposed between at least the first electrode 12 and the second electrode 15 to electrically connect the first electrode 12 and the second electrode 15 to each other. As shown in Figure 3, the circuit connection portion 17 does not necessarily have two distinct regions between the first region 18 and the second region 19; the cured material derived from the first adhesive layer and the cured material derived from the second adhesive layer may be mixed together to form a single region.

[0137] The circuit connection structure may consist of a first circuit member and a second circuit member, one of which is an IC chip, and the other being a plastic substrate having electrodes containing Ti. Examples of circuit connection structures include a flexible organic electroluminescent color display (organic EL display) in which a plastic substrate with regularly arranged organic EL elements is connected to a driving circuit element that is a driver for displaying images, and a touch panel in which a plastic substrate with regularly arranged organic EL elements is connected to a position input element such as a touchpad. The circuit connection structure can be applied to various monitors such as smartphones, tablets, televisions, vehicle navigation systems, and wearable devices; furniture; home appliances; and daily necessities.

[0138] Figure 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 the circuit connection structure 10 includes the step of interposing the adhesive film 1a described above between a first circuit member 13 having a first electrode 12 and a second circuit member 16 having a second electrode 15, and then heat-pressing the first circuit member 13 and the second circuit member 16 together to electrically connect the first electrode 12 and the second electrode 15 to each other.

[0139] Specifically, as shown in Figure 4(a), first, a first circuit member 13 comprising a first circuit board 11 and a first electrode 12 formed on the main surface 11a of the first circuit board 11, and a second circuit member 16 comprising a second circuit board 14 and a second electrode 15 formed on the main surface 14a of the second circuit board 14 are prepared.

[0140] Next, the first circuit member 13 and the second circuit member 16 are arranged so that the first electrode 12 and the second electrode 15 face each other, and the adhesive film 1a is placed between the first circuit member 13 and the second circuit member 16. For example, as shown in Figure 4(a), the adhesive film 1a is laminated onto the first circuit member 13 so that the side with the first adhesive layer 2 faces the main surface 11a of the first circuit board 11. Next, the second circuit member 16 is placed on the first circuit member 13, to which the adhesive film 1a has been laminated, so that the first electrode 12 on the first circuit board 11 and the second electrode 15 on the second circuit board 14 face each other.

[0141] Then, as shown in Figure 4(b), the first circuit member 13, the adhesive film 1a, and the second circuit member 16 are heated, and the first circuit member 13 and the second circuit member 16 are pressed together in the thickness direction, thereby thermocompressing them together. At this time, as indicated by the arrows in Figure 4(b), the second adhesive layer 3 has a flowable, uncured thermosetting component, so it flows to fill the gaps between the second electrodes 15 and hardens due to the heating. As a result, the first electrode 12 and the second electrode 15 are electrically connected to each other via the conductive particles 4, and the first circuit member 13 and the second circuit member 16 are bonded to each other, thereby obtaining the circuit connection structure 10 shown in Figure 3. In the manufacturing method of the circuit connection structure 10 of this embodiment, a portion of the first adhesive layer 2 is hardened by light irradiation, so the flow of conductive particles in the first adhesive layer 2 is suppressed, and the first adhesive layer 2 hardly flows during the heat-compression bonding, allowing the conductive particles to be efficiently captured between the opposing electrodes, thereby reducing the connection resistance between the opposing first electrode 12 and second electrode 15. Furthermore, when the thickness of the first adhesive layer is 5 μm or less, conductive particles tend to be captured even more efficiently during circuit connection.

[0142] Furthermore, by including the inorganic filler A described above in the second adhesive layer 3, high fluidity is achieved, reducing the connection resistance between the opposing first electrode 12 and second electrode 15, and effectively suppressing the occurrence of large indentations.

[0143] The heating temperature for heat-compression bonding can be set as appropriate, but for example, it may be between 50 and 190°C. The pressurization is not particularly limited as long as it does not damage the adherend, but in the case of COP mounting, for example, the area-equivalent pressure at the bump electrode may be between 0.1 and 50 MPa, or 40 MPa or less, or between 0.1 and 40 MPa. In the case of COG mounting, for example, the area-equivalent pressure at the bump electrode may be between 10 and 100 MPa. The heating and pressurizing times may be in the range of 0.5 to 120 seconds. [Examples]

[0144] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples.

[0145] [Preparation of the first adhesive layer, the second adhesive layer, and the third adhesive layer] The following materials were used in the preparation of the first adhesive layer, the second adhesive layer, and the third adhesive layer.

[0146] <Preparation of conductive particles> A 3 μm plastic core was plated with 80 nm Ni on its surface, and the outermost 20 nm was replaced with Pd plating. In this way, conductive particles with an average particle size of 3.2 μm were obtained.

[0147] (A) Component: Conductive particles A-1: Conductive particles prepared as described above

[0148] (B) Component: Photocurable resin component (B1) Component: Radical polymerizable compound B1-1: NK ester A-BPEF70T (ethoxylated fluorene-type di(meth)acrylate (bifunctional), manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), diluted with toluene to 70% by mass of non-volatile content. B1-2: Lipoxy VR-90 (Bisphenol A type epoxy (meth)acrylate (bifunctional) (vinyl ester resin), manufactured by Showa Denko Corporation)

[0149] (B2) Component: Photoradical polymerization initiator B2-1: Irgacure OXE-02 (Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(0-acetyloxime), manufactured by BASF), diluted with MEK to 10% by mass of non-volatile content.

[0150] (C) Component: Thermosetting resin component (C1) Component: Cationic polymerizable compound C1-1: ETERNACOLL OXBP (3-ethyl-3-hydroxymethyloxetane, manufactured by Ube Industries, Ltd.) C1-2: EHPE3150 (1,2-epoxy-4-(2-oxyranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, manufactured by Daicel Corporation) C1-3: Celoxide 2021P (3,4-Epoxycyclohexylmethyl(3,4-Epoxy)cyclohexanecaloboxylate, manufactured by Daicel Corporation) C1-4:OXSQ-TX100 (Poly({3-[(3-ethyl-3-oxetanyl)methoxy]propyl}silsesquioxane) derivative, manufactured by Toagosei Co., Ltd.) C1-5: Ceroxide 8010 (B-7-oxabicyclo[4.1.0]heptane, manufactured by Daicel Corporation)

[0151] (C2) Component: Thermal cationic polymerization initiator C2-1: CXC-1821 (manufactured by King Industries)

[0152] (D) Component: Thermoplastic resin D-1: Pheno-Tote YP-50S (Bisphenol A type phenoxy resin, weight-average molecular weight: 60,000, glass transition temperature: 84°C, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with MEK to 40% by mass of non-volatile content. D-2: TOPR-300 (high Tg type epoxy resin, epoxy equivalent: 900-1,000, softening point: 120°C, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with MEK to 60% by mass of non-volatile content. D-3: Pheno-Tote FX-293 (phenoxy resin containing a fluorene skeleton, weight-average molecular weight: 45,000, glass transition temperature: 158°C, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with MEK to 60% by mass of non-volatile content. D-4: Pheno-Tote ZX-1356-2 (a copolymer phenoxy resin of bisphenol A and bisphenol F types, weight-average molecular weight: 70,000, glass transition temperature: 71°C, manufactured by Nippon Steel Chemical & Material Co., Ltd.), diluted with MEK to 40% by mass of non-volatile content.

[0153] (E) Component: Coupling agent E-1: SH-6040 (3-Glycidoxypropyltrimethoxysilane, manufactured by Toray Dow Corning Co., Ltd.)

[0154] (F) Component: Filler (F1) Ingredients: Inorganic filler F-1: AdmaFine SE2050 (silica filler, manufactured by Admatex Co., Ltd.), after removing as many particles larger than 1 μm as possible by air classification, is used, diluted with MEK to 70% by mass of non-volatile content. F-2: AdmaFine SE2050 (silica filler, manufactured by Admatex Co., Ltd.), diluted with MEK to 70% by mass of non-volatile content. F-3: Admanano YA050C (silica filler, manufactured by Admatex Co., Ltd.), diluted with MEK to 50% by mass of non-volatile content. F-4: Aerosil R805 (silica filler, manufactured by Evonik Industries AG), diluted with MEK to 10% by mass of non-volatile content.

[0155] <Measurement of particle size distribution of inorganic fillers - 1> The particle size D50 (particle size at 50% cumulative distribution) and D95 ​​(particle size at 95% cumulative distribution) of the above inorganic filler were measured in the volume-based particle size distribution. For the measurements, a Microtorac MT3300EXII manufactured by Nikkiso Co., Ltd. was used as the measuring device, and methyl ethyl ketone was used as the measurement solvent.

[0156] [Table 1]

[0157] <Preparation of the first adhesive layer> Compositions were obtained by mixing the materials shown in Table 2 in the composition ratios (mass ratios) shown in Table 2 (the values ​​in Table 2 represent the non-volatile content). These compositions were then coated onto a release-treated PET (polyethylene terephthalate) film while applying a magnetic field, and then dried with hot air at 70°C for 5 minutes using an organic solvent, etc., to obtain composition layers containing each component. The composition layers were coated to a thickness of 3-4 μm after drying. Subsequently, each composition layer was irradiated with light (UV irradiation: metal halide lamp, integrated light intensity: 2100 mJ / cm²). 2 A first adhesive layer in which conductive particles were dispersed was prepared. The thickness of this layer was measured using a contact-type thickness gauge.

[0158] Furthermore, if the thickness of the layer or adhesive layer made of the first adhesive composition is less than the thickness (diameter) of the conductive particles, measuring the thickness of the layer using a contact-type thickness gauge will reflect the thickness of the conductive particles, and the thickness of the region where the conductive particles are present will be measured. Therefore, after preparing a two-layer adhesive film in which the first adhesive layer and the second adhesive layer are laminated, the thickness of the first adhesive layer located in the spaced portion between adjacent conductive particles was measured using a scanning electron microscope by the method described later.

[0159] [Table 2]

[0160] <Preparation of the second adhesive layer> Compositions were prepared by mixing the materials shown in Table 3 in the composition ratios (mass ratios) shown in Table 3 (the values ​​in Table 3 represent the non-volatile content). These compositions were then coated onto a release-treated PET (polyethylene terephthalate) film, and a second adhesive layer containing each component was prepared by hot-air drying with an organic solvent at 70°C for 5 minutes. The adhesive layers were coated to a thickness of 8-9 μm after drying. The thickness was measured using a contact thickness gauge.

[0161] (Coating yield) The coating yield when forming the second adhesive layer was determined by calculating the percentage (Y) of no white lines or scratches, and evaluated according to the following criteria. A+:Y is 95% or higher. A:Y is between 90% and 95%. B:Y is between 80% and 90%. The C:Y ratio is less than 80%.

[0162] [Table 3]

[0163] <Measurement of particle size distribution of inorganic fillers - 2> For the inorganic filler contained in composition S1-4 (a mixture of 80 parts by mass of F-1 and 5 parts by mass of F-3), the particle size D50 at 50% cumulative (particle size at 50% cumulative distribution) and the particle size D95 at 95% cumulative (particle size at 95% cumulative distribution) in the volume-based particle size distribution were measured in the same manner as described above.

[0164] [Table 4]

[0165] <Preparation of the third adhesive layer> Compositions were obtained by mixing the materials shown in Table 5 in the composition ratios (mass ratios) shown in Table 5 (the values ​​in Table 5 represent the non-volatile content). These compositions were then coated onto a release-treated PET (polyethylene terephthalate) film, and a third adhesive layer consisting of compositions containing each component was prepared by hot-air drying with an organic solvent at 70°C for 5 minutes. The adhesive layers were coated so that their thickness after drying was 0.5 to 1.5 μm. The thickness was measured using a contact thickness gauge.

[0166] [Table 5]

[0167] (Examples 1-5 and Comparative Examples 1-5) [Fabrication of adhesive film] Using the first, second, and third adhesive layers prepared as described above, adhesive films with the configurations shown in Table 6 were fabricated. For example, in the adhesive film of Example 1, the first adhesive layer formed with composition P-1 was bonded to the second adhesive layer formed with composition S1-1 while applying a temperature of 50-60°C, and the PET film on the first adhesive layer side was peeled off. Next, the third adhesive layer formed with composition S2-1 was bonded to the exposed first adhesive layer while applying a temperature of 50-60°C to obtain the adhesive film of Example 1. In order to facilitate the peeling of the PET film during these processes and when connecting the circuit, each PET film was selected such that the peeling force between the second adhesive layer and the PET film was greater than the peeling force between the first adhesive layer and the PET film, and between the third adhesive layer and the PET film.

[0168] For the adhesive films of Examples 2-4 and Comparative Examples 1-4, adhesive films with the configurations shown in Table 6 were prepared in the same manner as in Example 1. For Example 5 and Comparative Example 5, adhesive films with the configurations shown in Table 6 were prepared in the same manner as in Example 1, except that a third adhesive layer was not laminated.

[0169] The thickness of the first adhesive layer of the fabricated circuit connection adhesive film was measured using the following method. First, the circuit connection adhesive film 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 (product name: JER811, manufactured by Mitsubishi Chemical Corporation) and 10 g of diethylenetriamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was cast into the film. Subsequently, the cross-section was polished using a polishing machine, and the thickness of the first adhesive layer located in the spaced portion between adjacent conductive particles was measured using a scanning electron microscope (SEM, product name: SE-8010, manufactured by Hitachi High-Tech Science Corporation). The thickness of the first adhesive layer was 1.8 μm.

[0170] When the particle density of the adhesive films obtained in Examples 1-5 and Comparative Examples 1-5 was measured, it was found to be approximately 18,000 particles / mm³ in all cases. 2 That was the case.

[0171] [Evaluation of circuit connection structures] <Fabrication of Circuit Connection Structure-1> As the first circuit component, an IC chip (0.9 mm × 20.3 mm, thickness: 0.3 mm, bump electrode size: 70 μm × 12 μm, bump electrode spacing: 12 μm, bump electrode thickness: 9 μm) with bump electrodes arranged in a staggered pattern in two rows was prepared. As the second circuit component, a polyimide substrate (manufactured by Toray DuPont, 200H) (38 mm × 28 mm, thickness: 0.05 mm) was prepared with a Ti: 50 nm / Al: 400 nm wiring pattern (pattern width: 19 μm, electrode spacing: 5 μm) formed on its surface.

[0172] Circuit connection structures were fabricated using the adhesive films of Examples 1-5 and Comparative Examples 1-5. The adhesive film was cut to a width of 2.0 mm and placed on the first circuit member so that the third adhesive layer (the second adhesive layer in Examples 5 and Comparative Example 5) and the first circuit member were in contact. A thermocompression bonding apparatus consisting of a ceramic heater stage and a tool (8 mm x 50 mm) was used, at 70°C and 0.98 MPa (10 kgf / cm²). 2 The adhesive film was attached to the first circuit member by heating and pressurizing for 2 seconds under the specified conditions, and the release film on the side of the adhesive film opposite to the first circuit member was peeled off. Next, after aligning the bump electrode of the first circuit member with the wiring pattern of the second circuit member, a heat tool measuring 8 mm x 45 mm was used, and a 50 μm thick Teflon® buffer was used as a buffer material. The adhesive film was heated and pressurized for 5 seconds under the conditions of a measured maximum temperature of 170°C and an area-converted pressure of 30 MPa at the bump electrode, thereby attaching the first adhesive layer of the adhesive film to the second circuit member, thereby fabricating circuit connection structures-1.

[0173] <Fabrication of Circuit Connection Structure-2> As the first circuit component, an IC chip (0.9 mm × 20.3 mm, thickness: 0.3 mm, bump electrode size: 70 μm × 12 μm, space between bump electrodes: 12 μm, bump electrode thickness: 5 μm) with bump electrodes arranged in a staggered pattern in two rows was prepared. As the second circuit component, a glass substrate (25 mm × 35 mm, thickness: 0.2 mm) with a 150 nm thick Al / Nd film deposited on its surface was prepared.

[0174] Except for using the first and second circuit members described above, circuit connection structures-2 were fabricated in the same manner as the fabrication of circuit connection structure-1, using the respective adhesive films of Examples 1 to 5 and Comparative Examples 1 to 5.

[0175] (Evaluation of connection resistance) The initial connection resistance (continuity resistance) of the fabricated circuit connection structure-1 was measured using the four-terminal method. A multimeter MLR21 manufactured by Kusumoto Kasei Co., Ltd. was used for the measurement. The potential difference was measured at 14 arbitrary points, and the average value was calculated. The average value of the potential difference was converted to a connection resistance value and evaluated according to the following criteria. The results are shown in Table 6. A: Connection resistance is less than 0.6Ω B: Connection resistance value is 0.6Ω or more and less than 1.0Ω C: Connection resistance value is 1.0Ω or higher

[0176] (Evaluation of large indentations) The fabricated circuit connection structure-2 was observed from the glass substrate side using a differential interference microscope to check for the presence or absence of indentations (large indentations) that were clearly stronger (visually noticeable) than the indentations of conductive particles. The structure was evaluated as "A" if no such large indentations were observed and "B" if they were observed.

[0177] [Table 6]

[0178] <Preparation of the first adhesive layer-B> Compositions were obtained by mixing the materials shown in Table 7 in the composition ratios (mass ratios) shown in Table 7 (the values ​​in Table 7 represent the non-volatile content). These compositions were then coated onto a release-treated PET (polyethylene terephthalate) film, and hot-air dried with an organic solvent at 70°C for 5 minutes to obtain composition layers containing each component. The composition layers were coated to a thickness of 5 μm after drying to prepare the first adhesive layer-B. The thickness here was measured using a contact thickness gauge.

[0179] [Table 7]

[0180] <Preparation of the second adhesive layer - B> Compositions were prepared by mixing the materials shown in Table 8 in the composition ratios (mass ratios) shown in Table 8 (the values ​​in Table 8 represent the non-volatile content). These compositions were then coated onto a release-treated PET (polyethylene terephthalate) film, and a second adhesive layer-B, containing each component, was prepared by hot-air drying with an organic solvent at 70°C for 5 minutes. The adhesive layers were coated to a thickness of 11 μm after drying. The thickness was measured using a contact thickness gauge.

[0181] (Coating yield) The coating yield when forming the second adhesive layer-B was determined by calculating the percentage (Y) of no white lines or scratches, and evaluated according to the following criteria. A+:Y is 95% or higher. A:Y is between 90% and 95%. B:Y is between 80% and 90%. The C:Y ratio is less than 80%.

[0182] [Table 8]

[0183] (Example 6 and Comparative Examples 6-8) [Fabrication of adhesive film] Using the first adhesive layer-B and the second adhesive layer-B prepared as described above, adhesive films with the configurations shown in Table 9 were prepared. For example, in the adhesive film of Example 6, the first adhesive layer-B, formed with composition P-2, was bonded to the second adhesive layer-B, formed with composition S1-9, while applying a temperature of 50-60°C to obtain the adhesive film of Example 6.

[0184] For the adhesive films of Comparative Examples 6 to 8, adhesive films with the configurations shown in Table 9 were prepared in the same manner as in Example 6.

[0185] <Fabrication of Circuit Connection Structure-3> As the first circuit component, an IC chip (0.9 mm × 20.3 mm, thickness: 0.3 mm, bump electrode size: 70 μm × 12 μm, space between bump electrodes: 12 μm, bump electrode thickness: 5 μm) with bump electrodes arranged in a staggered pattern in two rows was prepared. As the second circuit component, a glass substrate (25 mm × 35 mm, thickness: 0.2 mm) with a 150 nm thick Ti / Al / Ti film deposited on its surface was prepared.

[0186] Circuit connection structures were fabricated using the adhesive films of Example 6 and Comparative Examples 6-8. The adhesive film was cut to a width of 2.0 mm and placed on the first circuit member so that the second adhesive layer-B and the first circuit member were in contact. A thermocompression bonding apparatus consisting of a ceramic heater stage and a tool (8 mm x 50 mm) was used, at 70°C and 0.98 MPa (10 kgf / cm²). 2 The adhesive film was attached to the first circuit member by heating and pressurizing for 2 seconds under the specified conditions, and the release film on the side of the adhesive film opposite to the first circuit member was peeled off. Next, after aligning the bump electrode of the first circuit member with the wiring pattern of the second circuit member, a heat tool measuring 8 mm x 45 mm was used, and a 50 μm thick Teflon® buffer was used as a buffer material. The adhesive film was heated and pressurized for 5 seconds under the conditions of a measured maximum temperature of 145°C and an area-converted pressure of 30 MPa at the bump electrode, thereby attaching the first adhesive layer of the adhesive film to the second circuit member, thereby fabricating the circuit connection structure-3.

[0187] (Evaluation of connection resistance) The initial connection resistance (continuity resistance) of the fabricated circuit connection structure-3 was measured using the four-terminal method. A multimeter MLR21 manufactured by Kusumoto Kasei Co., Ltd. was used for the measurement. The potential difference was measured at 14 arbitrary points, and the average value was calculated. The average value of the potential difference was converted to a connection resistance value and evaluated according to the following criteria. The results are shown in Table 9. A: Connection resistance less than 5Ω B: Connection resistance value is 5Ω or more and less than 10Ω C: Connection resistance value is 10Ω or higher

[0188] (Evaluation of large indentations) The fabricated circuit connection structure-3 was observed from the glass substrate side using a differential interference microscope to check for the presence or absence of indentations (large indentations) that were clearly stronger (visually noticeable) than the indentations of conductive particles. The structure was evaluated as "A" if no such large indentations were observed and as "B" if they were observed.

[0189] [Table 9] [Explanation of symbols]

[0190] 1a, 1b... Adhesive film for circuit connection, 2... First adhesive layer, 3... Second adhesive layer, 4... Conductive particles, 6... Third adhesive layer, 10... Circuit connection structure, 12... Circuit electrode (first electrode), 13... First circuit member, 15... Bump electrode (second electrode), 16... Second circuit member, 20, 22, 24... Substrate.

Claims

1. The adhesive comprises a first adhesive layer containing conductive particles, a cured product of a photocurable resin component, and a first thermosetting resin component, and a second adhesive layer provided on the first adhesive layer and containing a second thermosetting resin component. The second adhesive layer is made of an inorganic filler-containing composition comprising the second thermosetting resin component and an inorganic filler A having a particle size D50 of 0.5 to 1.0 μm at 50% accumulation and a particle size D95 of 0.9 to 2.0 μm at 95% accumulation in a volume-based particle size distribution. The inorganic filler A is a silica filler with a primary particle size of 0.3 to 0.7 μm. A circuit connection adhesive film wherein the content of the inorganic filler A in the second adhesive layer is 10 to 70% by mass, based on the total mass of the second adhesive layer.

2. The circuit connection adhesive film according to claim 1, further comprising a third adhesive layer containing a third thermosetting resin component, laminated on the side of the first adhesive layer opposite to the second adhesive layer.

3. A method for manufacturing a circuit connection structure, comprising the steps of interposing a circuit connection adhesive film 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 then heat-pressing the first circuit member and the second circuit member together to electrically connect the first electrode and the second electrode.

4. A method for manufacturing a circuit connection structure according to claim 3, wherein one of the first circuit member and the second circuit member is an IC chip, and the other is a plastic substrate having electrodes containing Ti.

5. A first circuit member having a first electrode, A second circuit member having a second electrode, A circuit connection portion is disposed between the first circuit member and the second circuit member and electrically connects the first electrode and the second electrode to each other, Equipped with, A circuit connection structure wherein the circuit connection portion includes a cured product of the circuit connection adhesive film described in claim 1 or 2.

6. The circuit connection structure according to claim 5, wherein one of the first circuit member and the second circuit member is an IC chip, and the other is a plastic substrate having electrodes containing Ti.

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