Adhesive film and connector for circuit connection

Abstract

A bonding film for circuit connection, the bonding film being used for the purpose of connecting a first circuit member, which is obtained by forming a first circuit electrode on a main surface of a first substrate, and a second circuit member, which is obtained by forming a second circuit electrode on a main surface of a second substrate, with each other in such a manner that the first circuit electrode and the second circuit electrode face each other. This bonding film for circuit connection contains (a) a thermoplastic resin, (b) a radically polymerizable compound, (c) a radical polymerization initiator and (d) insulating particles; the radically polymerizable compound (b) contains a (meth)acrylate compound; the flow rate of this bonding film is 140% or more as determined at a heating temperature of 160°C under a pressure of 2 MPa with a heating time of 5 seconds; and the linear expansion coefficient of a cured product of this bonding film is 130 ppm / K or less on average for the temperature range 80°C to 90°C.

Description

[Technical Field]

[0001] This disclosure relates to an adhesive film for circuit connection and a connector for circuit components. [Background technology]

[0002] In semiconductor devices and liquid crystal display devices, various adhesive compositions have conventionally been used as circuit connection materials for the purpose of bonding various components within the device. These adhesive compositions require a variety of properties, including adhesiveness, heat resistance, and reliability under high temperature and high humidity conditions.

[0003] In recent years, mobile devices have become smaller, and the development of wearable devices has also become more active. Furthermore, wearable devices require excellent weather resistance due to their intended use. In recent years, saltwater resistance has become a key requirement for this weather resistance.

[0004] On the other hand, methods have been used to prevent moisture from entering the circuit connection area by applying a sealing resin (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-203628 [Patent Document 2] Japanese Patent Publication No. 2003-151762 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, because wearable devices are small, the circuit connection points are often small, making it difficult to apply sealing resin. Even if application is possible, the technical difficulty and increased cost are challenges. Therefore, for small mobile devices such as wearable devices, the use of film-type adhesives (adhesive films) that allow for easy sealing even when the circuit connection points are small is being considered.

[0007] However, when adhesive films are used to bond circuit components together and seal circuit connections, saltwater resistance tends to be insufficient.

[0008] This disclosure has been made in view of the problems of the prior art described above, and aims to provide an adhesive film for circuit connections that can form a connector having excellent saltwater resistance, and a connector for a circuit member using the same. [Means for solving the problem]

[0009] To achieve the above objective, the present disclosure provides a circuit connection adhesive film for connecting a first circuit member having a first circuit electrode formed on the main surface of a first substrate and a second circuit member having a second circuit electrode formed on the main surface of a second substrate, with the first circuit electrode and the second circuit electrode positioned opposite each other, wherein the adhesive film comprises (a) a thermoplastic resin, (b) a radical polymerizable compound, (c) a radical polymerization initiator, and (d) insulating particles, wherein the (b) radical polymerizable compound comprises a (meth)acrylate compound, the flow rate of the adhesive film is 140% or more at a heating temperature of 160°C, a pressure of 2 MPa, and a heating time of 5 seconds, and the coefficient of linear expansion of the cured product of the adhesive film is 130 ppm / K or less on average at 80-90°C.

[0010] The above-described adhesive film for circuit connections, being in film form, facilitates the connection of circuit components and sealing of circuit connections in small mobile devices such as wearable devices, and also forms a connector with excellent saltwater resistance. The inventors speculate that the reason for the excellent saltwater resistance is as follows. First, chloride ions, which are components of saltwater, penetrate the interface between the circuit component and the connector, which is the cured product of the adhesive film, more easily than the components of water, thereby easily causing delamination between the circuit component and the connector. Therefore, even if delamination does not occur when the connector is exposed to ordinary water, delamination is likely to occur when exposed to saltwater. In contrast, with the above-described adhesive film, the coefficient of linear expansion of its cured product is within the above range, which increases the adhesion at the interface between the circuit component and the connector to the extent that it prevents the penetration of saltwater components, and thus suppresses delamination even when the connector is exposed to saltwater. Furthermore, with the above-described adhesive film, the flow rate is within the above range, which causes the adhesive film to flow and moderately protrude from between the circuit components when connecting them, and this protruding portion acts as a lid to protect the circuit connection. Furthermore, because this lid portion also has high adhesion to the circuit component, it can prevent the penetration of saltwater components into the interface between the circuit component and the connecting component. Therefore, the above-mentioned adhesive film for circuit connections can form a connector with excellent saltwater resistance. Moreover, the above effect is greatest when a (meth)acrylate compound is used as the radical polymerizable compound.

[0011] The insulating particles (d) described above may include silica particles. Furthermore, the insulating particles (d) described above may include organic fine particles. Here, the organic fine particles may include fine particles made of at least one resin selected from the group consisting of polyurethane resin and silicone resin. Moreover, the average particle size of the insulating particles (d) described above may be 0.001 to 35 μm. By using these insulating particles, it is easier to adjust the flow rate of the adhesive film and the coefficient of thermal expansion of the cured product to a suitable range, and to further improve the saltwater resistance of the resulting connection.

[0012] The adhesive film for circuit connection described above may further contain (e) conductive particles. By containing (e) conductive particles, conductivity or anisotropic conductivity can be imparted to the adhesive film for circuit connection, so that the adhesive film can be more suitably used as a circuit connection material. Further, the connection resistance between circuit electrodes electrically connected via the adhesive film can be more easily reduced.

[0013] The present disclosure also provides a connected body comprising: a pair of oppositely disposed circuit members each having a circuit electrode; and a connecting member provided between the pair of circuit members and bonding the pair of circuit members to each other, wherein the circuit electrode of one circuit member and the circuit electrode of the other circuit member are electrically connected to each other, and the connecting member is a cured product of the above-mentioned adhesive film for circuit connection. Such a connected body can have excellent salt water resistance.

Effects of the Invention

[0014] According to the present disclosure, there can be provided an adhesive film for circuit connection capable of forming a connected body having excellent salt water resistance, and a connected body of circuit members using the same.

Brief Description of Drawings

[0015] [Figure 1] Fig. 1 is a schematic cross-sectional view showing one embodiment of a laminated film having an adhesive film for circuit connection. [Figure 2] Fig. 2 is a schematic cross-sectional view showing one embodiment of a connected body. [Figure 3] Fig. 3 is a schematic cross-sectional view showing one embodiment of a method for producing a connected body.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as necessary. The present disclosure is not limited to the following embodiments. Unless otherwise specified, the materials exemplified below may be used singly or in combination of two or more kinds. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. A numerical range indicated using "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present specification, the upper limit or lower limit of the numerical range at one step may be replaced with the upper limit or lower limit of the numerical range at another step. In the numerical ranges described in the present specification, the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples. In the present specification, (meth)acrylate means acrylate or methacrylate corresponding thereto, and (meth)acryloyloxy group means acryloyloxy group or methacryloyloxy group.

[0017] The present embodiment relates to the following [1] to [7]. [1] An adhesive film for circuit connection for connecting a first circuit member having a first circuit electrode formed on a main surface of a first substrate and a second circuit member having a second circuit electrode formed on a main surface of a second substrate in a state where the first circuit electrode and the second circuit electrode are arranged opposite to each other, wherein the adhesive film comprises (a) a thermoplastic resin, (b) a radical polymerizable compound, (c) a radical polymerization initiator, and (d) insulating particles, the (b) radical polymerizable compound comprises a (meth)acrylate compound, a flow rate of the adhesive film is 140% or more under a heating temperature of 160° C., a pressure of 2 MPa, and a heating time of 5 seconds, and a coefficient of linear expansion of a cured product of the adhesive film is 130 ppm / K or less as an average at 80 to 90° C. [2] The adhesive film for circuit connection according to [1] above, wherein the (d) insulating particles comprise silica fine particles. [3] The adhesive film for circuit connection according to [1] or [2] above, wherein the (d) insulating particles comprise organic fine particles. [4] The circuit connection adhesive film according to [3] above, wherein the organic fine particles include fine particles made of at least one resin selected from the group consisting of polyurethane resin and silicone resin. [5] The circuit connection adhesive film according to any of [1] to [4] above, wherein the average particle size of the insulating particles (d) above is 0.001 to 35 μm. [6](e) A circuit connection adhesive film according to any of [1] to [5] above, further containing conductive particles. [7] A connector comprising a pair of circuit members having circuit electrodes and arranged opposite each other, and a connecting member provided between the pair of circuit members for bonding the pair of circuit members together, wherein the circuit electrodes of one of the circuit members and the circuit electrodes of the other circuit member are electrically connected, and the connecting member is a cured product of the adhesive film for circuit connection described in any of [1] to [6] above.

[0018] (Adhesive film for circuit connections) The adhesive film for circuit connection according to this embodiment (hereinafter also simply referred to as "adhesive film") comprises (a) a thermoplastic resin, (b) a radical polymerizable compound, (c) a radical polymerization initiator, and (d) insulating particles. The (b) radical polymerizable compound includes a (meth)acrylate compound. The flow rate of the adhesive film is 140% or more at a heating temperature of 160°C, a pressure of 2 MPa, and a heating time of 5 seconds. The coefficient of linear expansion (CTE) of the cured product of the adhesive film is 130 ppm / K or less on average at 80-90°C. The adhesive film having the above configuration can be formed using an adhesive composition comprising the (a) thermoplastic resin, the (b) radical polymerizable compound, the (c) radical polymerization initiator, and the (d) insulating particles. The adhesive film and adhesive composition may also contain (e) conductive particles. Each component will be described below.

[0019] (a) The thermoplastic resin is not particularly limited, but examples include one or more resins selected from polyimide resins, polyamide resins, phenoxy resins, poly(meth)acrylate resins, polyimide resins, polyester resins, polyurethane resins, and polyvinyl butyral resins. The thermoplastic resin may contain siloxane bonds and / or fluorine groups. When two or more thermoplastic resins are used, they may be completely miscible or combinations that result in microphase separation and turbidity.

[0020] The weight-average molecular weight of the thermoplastic resin is not particularly limited, but may be between 5,000 and 200,000, or between 10,000 and 150,000. When the weight-average molecular weight of the thermoplastic resin is 5,000 or higher, the adhesive strength of the adhesive film tends to improve. When the weight-average molecular weight of the thermoplastic resin is 200,000 or lower, good compatibility with other components tends to be easily obtained, and the fluidity of the adhesive film tends to improve.

[0021] The thermoplastic resin content may be 20-80% by mass, 25-70% by mass, or 30-60% by mass, based on the total amount of components (a) and (b). When the thermoplastic resin content is 20% by mass or more, the adhesive strength of the adhesive film tends to improve, and the film-forming properties when forming an adhesive film from the adhesive composition tend to improve, while when it is 80% by mass or less, the fluidity of the adhesive film tends to be easily obtained.

[0022] As a thermoplastic resin, rubber components can also be used for stress relaxation and improved adhesion. Examples of rubber components include acrylic rubber, polyisoprene, polybutadiene, carboxyl-terminated polybutadiene, hydroxyl-terminated polybutadiene, 1,2-polybutadiene, carboxyl-terminated 1,2-polybutadiene, hydroxyl-terminated 1,2-polybutadiene, styrene-butadiene rubber, hydroxyl-terminated styrene-butadiene rubber, carboxylated nitrile rubber, hydroxyl-terminated poly(oxypropylene), alkoxysilyl-terminated poly(oxypropylene), poly(oxytetramethylene) glycol, polyolefin glycol, and poly-ε-caprolactone. From the viewpoint of improving adhesion, the rubber components may have highly polar groups such as cyano groups or carboxyl groups as side chain groups or terminal groups. These rubber components can be used individually or in combination of two or more.

[0023] The adhesive film according to this embodiment may contain any radical polymerizable compound, but at least a (meth)acrylate compound. This radical polymerizable compound may be a monomer or an oligomer, or a combination of both.

[0024] The radical polymerizable compound may be one or more polyfunctional (meth)acrylate compounds having two or more (meth)acryloyloxy groups. Examples of such (meth)acrylate compounds include monomers or oligomers such as epoxy (meth)acrylate, urethane (meth)acrylate, polyether (meth)acrylate, and polyester (meth)acrylate, trimethylolpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and neopentyl glycol di(meth)acrylate. Examples include dipentaerythritol hexa(meth)acrylate, isocyanuric acid-modified bifunctional (meth)acrylate, isocyanuric acid-modified trifunctional (meth)acrylate, epoxy (meth)acrylate produced by adding (meth)acrylic acid to two glycidyl groups of bisphenol full orange glycidyl ether, and compounds in which a (meth)acryloyloxy group is introduced to a compound obtained by adding ethylene glycol and / or propylene glycol to two glycidyl groups of bisphenol full orange glycidyl ether. These compounds may be used individually or in combination of two or more.

[0025] The adhesive film may contain (b) a monofunctional (meth)acrylate compound as a radical polymerizable compound for purposes such as adjusting fluidity. Examples of monofunctional (meth)acrylate compounds include pentaerythritol (meth)acrylate, 2-cyanoethyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and hydroxypropyl Examples include (meth)acrylate, isobornyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, n-lauryl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-(meth)acryloyloxyethyl phosphate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and (meth)acryloylmorpholine. These compounds may be used individually or in combination of two or more.

[0026] The adhesive film may, for the purpose of improving the crosslinking ratio, etc., contain, in addition to the (meth)acrylate compound mentioned above, compounds having radically polymerizable functional groups such as aryl groups, maleimide groups, and vinyl groups as (b) radical polymerizable compounds. Examples of such compounds include N-vinylimidazole, N-vinylpyridine, N-vinylpyrrolidone, N-vinylformamide, N-vinylcaprolactam, 4,4'-vinylidenebis(N,N-dimethylaniline), N-vinylacetamide, N,N-dimethylacrylamide, N-isopropylacrylamide, and N,N-diethylacrylamide.

[0027] For the purpose of improving adhesive force, the adhesive film may contain a radical polymerizable compound having a phosphate group as (b) the radical polymerizable compound. Examples of the radical polymerizable compound having a phosphate group include compounds represented by the following formula (1), (2) or (3).

[0028] Chemical formula

[0029] In formula (1), R 5 represents a (meth)acryloyloxy group, R 6 represents a hydrogen atom or a methyl group, and w and x each independently represent an integer of 1 to 8. A plurality of R 5 , R 6 , w and x in the same molecule may each be the same or different.

[0030] Chemical formula

[0031] In formula (2), R 7 represents a (meth)acryloyloxy group, and y and z each independently represent an integer of 1 to 8. A plurality of R 7 , y and z in the same molecule may each be the same or different.

[0032] Chemical formula

[0033] In formula (3), R 8 represents a hydrogen atom or a methyl group, R 9 represents a (meth)acryloyloxy group, and b and c each independently represent an integer of 1 to 8. R 8 in the same molecule may be the same or different.

[0034] Examples of radical polymerizable compounds having a phosphate group include acid phosphooxyethyl methacrylate, acid phosphooxyethyl acrylate, acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol monomethacrylate, acid phosphooxypolyoxypropylene glycol monomethacrylate, 2,2'-di(meth)acryloyloxydiethyl phosphate, EO-modified phosphate dimethacrylate, phosphate-modified epoxy acrylate, and vinyl phosphate.

[0035] The content of the radical polymerizable compound having a phosphate group may be 0.1 to 15% by mass or 0.5 to 10% by mass, based on the total amount of components (a) and (b). When the content of the radical polymerizable compound having a phosphate group is 0.1% by mass or more, high adhesive strength tends to be easily obtained, and when it is 15% by mass or less, the deterioration of the physical properties of the adhesive film after curing is less likely to occur, resulting in a good effect of improving reliability.

[0036] The total content of the radical polymerizable compound (b) in the adhesive film may be 20-80% by mass, 25-70% by mass, or 30-60% by mass, based on the total amount of components (a) and (b). If the total content is 20% by mass or more, the heat resistance tends to improve, and if it is 80% by mass or less, the effect of suppressing peeling after being left in a high-temperature, high-humidity environment tends to increase.

[0037] (c) The radical polymerization initiator can be arbitrarily selected from compounds such as peroxides and azo compounds. From the viewpoint of stability, reactivity and compatibility, it may also be a peroxide with a 1-minute half-life temperature of 90 to 175°C and a molecular weight of 180 to 1000. "1-minute half-life temperature" refers to the temperature at which the half-life of the peroxide is 1 minute. "Half-life" refers to the time it takes for the concentration of a compound to decrease to half of its initial value at a given temperature.

[0038] Radical polymerization initiators include, for example, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t- Butyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydroterephthalate, t-amylperoxy-3,5,5-trimethylhexanoate, 3 -Hydroxy-1,1-dimethylbutyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, t-amyl peroxyneodecanoate, t-amyl peroxy-2-ethylhexanoate, 3-methylbenzoyl peroxide, 4-methylbenzoyl peroxide, di(3-methylbenzoyl) peroxide, dibenzoyl peroxide, di(4-methylbenzoyl) peroxide, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobi (1-acetoxy-1-phenylethane), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), 1,1'-azobis(1-cyclohexanecarbonitride), t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,Examples include 5-di(3-methylbenzoylperoxy)hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxybenzoate, dibutylperoxytrimethyladipate, t-amylperoxyn-octoate, t-amylperoxyisononanoate, and t-amylperoxybenzoate. These can be used individually or in combination of two or more.

[0039] As a radical polymerization initiator, a compound that generates radicals upon irradiation with light at a wavelength of 150 to 750 nm can also be used. Such a compound is not particularly limited, but for example, due to its high sensitivity to light irradiation, α-acetaminophenone derivatives and phosphine oxide derivatives described in *Photoinitiation, Photopolymerization, and Photocuring*, J.-P. Fouassier, Hanser Publishers (1995), pp. 17-35 may be used. These compounds may be used individually or in combination of two or more. These compounds may also be combined with the above-mentioned peroxides and azo compounds. Alternatively, the adhesive film may contain a radical polymerization initiator that generates radicals upon irradiation with ultrasound, electromagnetic waves, etc.

[0040] To suppress corrosion of the connection terminals (circuit electrodes) of circuit components, the amount of chloride ions or organic acids contained in the radical polymerization initiator may be 5000 ppm or less. From a similar viewpoint, a radical polymerizable compound that generates less organic acid after decomposition may also be used. Since the stability of the circuit connection material is improved, a radical polymerization initiator having a mass retention rate of 20% by mass or more after being left open for 24 hours at room temperature and atmospheric pressure may also be used.

[0041] The amount of radical polymerization initiator may be 0.5 to 15 parts by mass or 1.5 to 10 parts by mass per 100 parts by mass of the total amount of component (a) and component (b).

[0042] The adhesive film contains (d) insulating particles. Examples of insulating particles include organic fine particles and inorganic fine particles.

[0043] Examples of inorganic nanoparticles include metal oxide nanoparticles such as silica nanoparticles, alumina nanoparticles, silica-alumina nanoparticles, titania nanoparticles, and zirconia nanoparticles, as well as nitride nanoparticles.

[0044] Examples of organic microparticles include urethane microparticles, silicone microparticles, methacrylate-butadiene-styrene microparticles, acrylic-silicone microparticles, polyamide microparticles, and polyimide microparticles. These organic microparticles function as impact absorbers with stress-relaxing properties.

[0045] These insulating particles may have a uniform structure or a core-shell structure.

[0046] Insulating particles can be used individually or in combination of two or more types. Insulating particles may also be used in combination of inorganic and organic fine particles. Using inorganic and organic fine particles in combination tends to further improve the saltwater resistance of the joint formed using the adhesive film.

[0047] The average particle size of the insulating particles may be 0.001 to 35 μm, 0.005 to 20 μm, or 0.001 to 10 μm. An average particle size of 0.001 μm or more tends to improve the cohesive force of the insulating particles, while an average particle size of 35 μm or less tends to improve the dispersibility of the insulating particles.

[0048] The average particle size in this specification can be measured, for example, by a scanning electron microscope (SEM).

[0049] The content of insulating particles may be 5 parts by mass or more, 7.5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more, based on 100 parts by mass of the total amount of components (a) and (b). If the content of insulating particles is 5 parts by mass or more, it tends to be relatively easy to maintain electrical connection between opposing electrodes. The content of insulating particles may also be 45 parts by mass or less, 40 parts by mass or less, or 35 parts by mass or less, based on 100 parts by mass of the total amount of components (a) and (b). If the content of insulating particles is 45 parts by mass or less, the fluidity of the adhesive film tends to improve. Furthermore, the type and content of insulating particles affect the flow rate and coefficient of thermal expansion of the adhesive film. Therefore, the type and content of insulating particles may be adjusted so that the flow rate and coefficient of thermal expansion of the adhesive film are within a specific range.

[0050] The adhesive film according to this embodiment may contain a silane coupling agent. The silane coupling agent may be a compound represented by the following formula (4).

[0051] [ka] In formula (4), R 1 , R 2 and R 3 Each of these independently represents a hydrogen atom, a C1-C5 alkyl group, a C1-C5 alkoxy group, a C1-C5 alkoxycarbonyl group, or an aryl group. 1 , R 2 and R 3 At least one of them is an alkoxy group. 4 represents a (meth)acryloyl group, vinyl group, isocyanate group, imidazole group, mercapto group, amino group, methylamino group, dimethylamino group, benzylamino group, phenylamino group, cyclohexylamino group, morpholino group, piperazino group, ureido group, or glycidyl group. a represents an integer from 1 to 10.

[0052] Examples of silane coupling agents of formula (4) include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatetopropyltriethoxysilane.

[0053] The amount of silane coupling agent may be 0.1 to 10 parts by mass, 0.25 to 7 parts by mass, or 0.5 to 5 parts by mass per 100 parts by mass of the total amount of components (a) and (b). If the amount of silane coupling agent is 0.1 parts by mass or more, the effect of suppressing the generation of delamination bubbles at the interface between the circuit member and the circuit connection material tends to be greater, and if the amount of silane coupling agent is 10 parts by mass or less, the decrease in fluidity when the adhesive film is stored for a long period of time tends to be suppressed.

[0054] The adhesive film according to this embodiment may further contain (e) conductive particles. The adhesive film containing conductive particles can be particularly suitable as an anisotropic conductive adhesive film.

[0055] Examples of conductive particles include metal particles containing Au, Ag, Pd, Ni, Cu, and solder, as well as carbon particles. Furthermore, conductive particles may be composite particles comprising a core particle made of a non-conductive material such as glass, ceramic, and plastic, and a conductive layer coating the core particle containing metal, metal particles, and carbon. Metal particles may also be particles having copper particles and a silver layer coating the copper particles. The core particle of the composite particle may be a plastic particle.

[0056] The composite particles, with the above-mentioned plastic particles as core particles, are deformable by heating and pressurizing, thus increasing the contact area between the circuit electrodes of the circuit members and the conductive particles when bonding the circuit members together. Therefore, an adhesive film containing these composite particles as conductive particles provides a connector with even greater reliability.

[0057] The adhesive film may contain insulating coated conductive particles having the above-mentioned conductive particles and an insulating layer or insulating particles covering at least a portion of their surface. The insulating layer can be provided by methods such as hybridization. The insulating layer or insulating particles are formed from an insulating material such as a polymer resin. By using such insulating coated conductive particles, short circuits due to contact between adjacent conductive particles become less likely to occur.

[0058] The average particle size of conductive particles may be 1 to 18 μm from the viewpoint of obtaining good 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.

[0059] The content of conductive particles is not particularly limited, but may be 0.1 to 30 volume%, 0.1 to 10 volume%, or 0.5 to 7.5 volume%, based on the total volume of the adhesive film. A conductive particle content of 0.1 volume% or more tends to improve conductivity. A conductive particle content of 30 volume% or less tends to reduce the likelihood of short circuits between circuit electrodes. The conductive particle content (volume%) is determined based on the volume at 23°C of each component constituting the adhesive film or adhesive composition before curing. The volume of each component can be determined by converting mass to volume using specific gravity. Alternatively, without dissolving or swelling the component to be measured, a suitable solvent (water, alcohol, etc.) that can thoroughly wet the component can be placed in a graduated cylinder, and the increased volume of the component to be measured can be determined as its volume.

[0060] Adhesive films may contain stabilizers to control the curing rate and provide storage stability. Such stabilizers are not particularly limited, but examples include quinone derivatives such as benzoquinone and hydroquinone, phenol derivatives such as 4-methoxyphenol and 4-t-butylcatechol, aminooxyl derivatives such as 2,2,6,6-tetramethylpiperidine-1-oxyl and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and hindered amine derivatives such as tetramethylpiperidyl methacrylate.

[0061] The amount of stabilizer may be 0.01 to 30 parts by mass or 0.05 to 10 parts by mass per 100 parts by mass of the total amount of component (a) and component (b). When the amount of stabilizer is 0.01 parts by mass or more, the effect of the stabilizer tends to be greater. When the amount of stabilizer is 30 parts by mass or less, the decrease in compatibility with other components tends to be suppressed.

[0062] The adhesive film according to this embodiment is obtained by forming an adhesive composition containing the above-mentioned components into a film to form a film-like adhesive. The adhesive film can be obtained, for example, by applying a solution obtained by adding a solvent or the like to the adhesive composition as needed onto a release support such as a fluororesin film, polyethylene terephthalate film, or release paper, or by impregnating a substrate such as a nonwoven fabric with the above solution and placing it on a release substrate, and then removing the solvent or the like. The adhesive film is convenient in terms of handling and other aspects.

[0063] The flow rate of the adhesive film according to this embodiment is 140% or more at a heating temperature of 160°C, a pressure of 2 MPa, and a heating time of 5 seconds. A flow rate of 140% or more allows the adhesive film to flow and moderately protrude from between circuit members during connection, with the protruding portion acting as a protective cover for the circuit connection. Therefore, the connection obtained using the adhesive film according to this embodiment can prevent the intrusion of saltwater components into the interface between the circuit member and the connection member, thus possessing excellent saltwater resistance. From the viewpoint of further improving the above effect, the flow rate of the adhesive film may be 145% or more. The flow rate of the adhesive film can be measured by the method shown in the examples.

[0064] The coefficient of linear expansion (CTE) of the cured adhesive film according to this embodiment is 130 ppm / K or less on average at 80-90°C. A CTE of 130 ppm / K or less for the cured adhesive film enhances the adhesion at the interface between the circuit member and the connecting member to the extent that it prevents the penetration of saltwater components when a connection is formed, thereby suppressing delamination even when the connection is exposed to saltwater. From the viewpoint of further improving the above effect, the CTE of the cured adhesive film may be 128 ppm / K or less. The CTE of the cured adhesive film can be measured by the method shown in the examples.

[0065] Figure 1 is a schematic cross-sectional view showing one embodiment of a laminated film having an adhesive film. The laminated film 100 shown in Figure 1 has a support 8 and an adhesive film 40 provided on the support 8. The adhesive film 40 is the above-mentioned adhesive composition molded into a film shape, and consists of an insulating adhesive layer 5 and insulating particles 6 and conductive particles 7 dispersed in the insulating adhesive layer 5. The insulating adhesive layer 5 consists of components of the above-mentioned adhesive composition other than the insulating particles and conductive particles. With this adhesive film, handling is easy, it can be easily installed on the adherend, and connection work can be easily performed. The adhesive film may have a multilayer structure consisting of two or more layers. The adhesive film does not have to contain conductive particles, but if the adhesive film contains conductive particles, the adhesive film can be suitably used as an anisotropic conductive film.

[0066] According to the adhesive film of this embodiment, adherends can usually be bonded together by a combination of heating and pressurizing. The heating temperature is not particularly limited, but may be between 100 and 250°C. The pressure is not particularly limited as long as it does not damage the adherends, but may generally be between 0.1 and 10 MPa. These heating and pressurizing steps may be performed for a period of 0.5 to 120 seconds. According to the adhesive film of this embodiment, for example, adherends can be sufficiently bonded together even with short heating and pressurizing periods of 5 seconds at conditions of approximately 140 to 200°C and 1 MPa.

[0067] The adhesive film according to this embodiment can be used as an adhesive for different types of adherends with different coefficients of thermal expansion. Specifically, the adhesive film can be used as a circuit connection material such as anisotropic conductive adhesives, silver paste and silver film, or as a semiconductor device adhesive material such as CSP elastomers, CSP underfill materials and LOC tape.

[0068] The following describes an example of manufacturing a connector by using the adhesive film according to this embodiment as an anisotropic conductive film to connect circuit boards and circuit members having circuit electrodes formed on the main surface of the circuit boards as adherends.

[0069] Figure 2 is a schematic cross-sectional view showing one embodiment of a connecting body comprising a connecting member made of a cured adhesive film according to this embodiment. The connecting body 1 shown in Figure 2 comprises a first circuit member 20 and a second circuit member 30 arranged opposite each other. A connecting member 10 is provided between the first circuit member 20 and the second circuit member 30 for bonding and connecting them.

[0070] The first circuit member 20 comprises a first circuit board 21 and a first circuit electrode 22 formed on the main surface 21a of the circuit board 21. An insulating layer may be formed on the main surface 21a of the circuit board 21.

[0071] The second circuit member 30 comprises a second circuit board 31 and a second circuit electrode 32 formed on the main surface 31a of the circuit board 31. An insulating layer may also be formed on the main surface 31a of the circuit board 31.

[0072] The first and second circuit members 20 and 30 are not particularly limited as long as they have circuit electrodes that require electrical connection. Examples of circuit boards 21 and 31 include substrates of inorganic materials such as semiconductors, glass and ceramics, substrates of organic materials such as polyimide and polycarbonate, and substrates containing both inorganic and organic materials such as glass / epoxy. The first circuit board 21 may be a glass substrate and the second circuit board 31 may be a flexible substrate (for example, a resin film such as a polyimide film).

[0073] Specific examples of circuit components to be connected include glass or plastic substrates with electrodes such as ITO (indium tin oxide) films formed on them, printed circuit boards, ceramic circuit boards, flexible circuit boards, and semiconductor silicon chips used in liquid crystal displays. These are used in combination as needed. Thus, according to the adhesive film of this embodiment, in addition to components having surfaces formed from organic materials such as printed circuit boards and polyimide films, metals such as copper and aluminum, ITO, and silicon nitride (SiN) can be used. x It can be used to bond circuit members having a wide variety of surface conditions, such as members having surfaces formed from inorganic materials like silicon dioxide (SiO2).

[0074] For example, when one circuit component is a solar cell having electrodes such as finger electrodes and busbar electrodes, and the other circuit component is a tab wire, the connection obtained by connecting them is a solar cell module comprising a solar cell, a tab wire, and a connecting component (cured adhesive film) that adheres them together.

[0075] The connecting member 10 is made of a cured adhesive film according to this embodiment. The connecting member 10 contains an insulating layer 11 and conductive particles 7 dispersed in the insulating layer 11. The conductive particles 7 are arranged not only between the opposing circuit electrodes 22 and 32, but also between the main surfaces 21a and 31a. The circuit electrodes 22 and 32 are electrically connected via the conductive particles 7. The conductive particles 7 are in direct contact with both the circuit electrodes 22 and 32. As a result, the connection resistance between the circuit electrodes 22 and 32 is sufficiently reduced. Therefore, the current flow between the circuit electrodes 22 and 32 can be made smooth, and the circuit can fully perform its function. If the connecting member does not contain conductive particles, the circuit electrodes 22 and 32 are electrically connected by direct contact.

[0076] Since the connecting member 10 is formed from the cured adhesive film according to this embodiment, the adhesive strength of the connecting member 10 to the circuit member 20 or 30 is sufficiently high. Therefore, even after reliability testing (high temperature and high humidity testing), a decrease in adhesive strength and an increase in connection resistance can be sufficiently suppressed.

[0077] The connector 1 can be manufactured, for example, by a method comprising the steps of: arranging a pair of circuit members having circuit electrodes and positioned opposite each other with an adhesive film made of an adhesive composition in between; and bonding the pair of circuit members and the adhesive film via the cured adhesive film by heating and curing them while applying pressure in the thickness direction of the adhesive film (this connection step).

[0078] Figure 3 is a schematic cross-sectional view showing one embodiment of a method for manufacturing a connector using an adhesive film according to this embodiment. As shown in Figure 3(a), the adhesive film 40 is placed on the main surface of the first circuit member 20 on the side of the circuit electrode 22. When the adhesive film 40 is provided on the support described above, the laminate of the adhesive film and the support is placed on the circuit member in an orientation where the adhesive film 40 is positioned towards the first circuit member 20. Since the adhesive film 40 is in film form, it is easy to handle. For this reason, the adhesive film 40 can be easily interposed between the first circuit member 20 and the second circuit member 30, and the connection work between the first circuit member 20 and the second circuit member 30 can be easily performed.

[0079] The adhesive film 40 is the aforementioned adhesive composition (circuit connection material) molded into a film, and has insulating particles 6, conductive particles 7, and an insulating adhesive layer 5. Even if the adhesive film does not contain conductive particles, it can be used as a circuit connection material for anisotropic conductive bonding. Circuit connection materials that do not contain conductive particles are sometimes called NCF (Non-Conductive Film). When the adhesive film contains conductive particles, the circuit connection material using it is sometimes called ACF (Anisotropic Conductive Film).

[0080] The thickness of the adhesive film 40 may be 10 to 50 μm. If the thickness of the adhesive film 40 is 10 μm or more, the space between the circuit electrodes 22 and 32 tends to be easily filled with the adhesive film. If the thickness of the adhesive film is 50 μm or less, the adhesive film between the circuit electrodes 22 and 32 can be sufficiently removed, and electrical conductivity between the circuit electrodes 22 and 32 can be easily ensured.

[0081] By applying pressures A and B in the thickness direction of the adhesive film 40, as shown in Figure 3(a), the adhesive film 40 is temporarily connected to the first circuit member 20 (see Figure 3(b)). At this time, heating may be applied while applying pressure. However, the heating temperature is set to a temperature that is sufficiently lower than the temperature at which the adhesive composition in the adhesive film 40 does not harden, i.e., the temperature at which the radical polymerization initiator rapidly generates radicals.

[0082] Next, as shown in Figure 3(c), the second circuit member 30 is placed on the adhesive film 40 with the second circuit electrode facing the first circuit member 20. If the adhesive film 40 is provided on a support, the support is peeled off before placing the second circuit member 30 on the adhesive film 40.

[0083] Subsequently, the adhesive film 40 is heated while applying pressures A and B in its thickness direction. The heating temperature at this time is set to a temperature at which the radical polymerization initiator generates sufficient radicals. As a result, radicals are generated from the radical polymerization initiator, and polymerization of the radical polymerizable compound begins. By heating the adhesive film 40, the insulating adhesive hardens with the distance between the first circuit electrode 22 and the second circuit electrode 32 sufficiently reduced, forming an insulating layer 11. As a result, the first circuit member 20 and the second circuit member 30 are firmly connected via the connecting member 10 which includes the insulating layer 11. This connection yields the connected body shown in Figure 2.

[0084] This connection may be performed under conditions of a heating temperature of 100 to 250°C, a pressure of 0.1 to 10 MPa, and a pressurizing time of 0.5 to 120 seconds. These conditions are appropriately selected depending on the application, adhesive film, and circuit components. After this connection, post-curing may be performed as needed.

[0085] The pressure of this connection is calculated from the applied load and the contact area using the formula: load / contact area. The contact area is the area of ​​the smallest rectangular region that encloses the entire overlapping portion of the first and second circuit electrodes when viewed from the thickness direction of the adhesive film, and which is the area that is pressed.

[0086] If the adhesive film contains a radical polymerization initiator that generates radicals upon light irradiation, light irradiation may be used instead of heating when curing the adhesive film for this connection. Alternatively, instead of a pre-prepared adhesive film, a paste-like adhesive composition may be used as the circuit connection material. For example, an adhesive film can be formed by a method that includes the steps of applying a coating solution prepared by dissolving the adhesive composition in a solvent as needed to the first circuit member 20 or the second circuit member 30, and drying the coating film. [Examples]

[0087] The present disclosure will be described in more detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the following examples.

[0088] (Synthesis of polyurethane resin) In a separable flask equipped with a reflux condenser, thermometer, and stirrer, 1000 parts by mass of polypropylene glycol (Mn=2000), a diol with ester bonds, and 4000 parts by mass of methyl ethyl ketone as a solvent were added and stirred at 40°C for 30 minutes. After raising the temperature of the solution to 70°C, 0.0127 parts by mass of dimethyltin laurate as a catalyst were added. Next, a solution prepared by dissolving 125 parts by mass of 4,4-diphenylmethane-diisocyanate, a diisocyanate compound, in 125 parts by mass of methyl ethyl ketone was added dropwise to this solution over 1 hour. After that, stirring was continued at this temperature until the absorption peak of NCO was no longer observed using an infrared spectrophotometer, to obtain a methyl ethyl ketone solution of polyurethane resin. The solid content concentration (concentration of polyurethane resin) of this solution was adjusted to 30% by mass. The weight-average molecular weight of the obtained polyurethane resin was 320,000 (equivalent to standard polystyrene) as measured by GPC. The GPC analysis conditions are shown in Table 1 below.

[0089] [Table 1]

[0090] (Synthesis of urethane acrylate) A reaction solution was prepared by charging a 2-liter four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser with 4000 parts by mass of polycarbonate diol (Aldrich, number average molecular weight 2000), 238 parts by mass of 2-hydroxyethyl acrylate, 0.49 parts by mass of hydroquinone monomethyl ether, and 4.9 parts by mass of tin-based catalyst. To the reaction solution heated to 70°C, 666 parts by mass of isophorone diisocyanate (IPDI) was uniformly added dropwise over 3 hours and the reaction was allowed to proceed. After the addition was complete, the reaction was continued for 15 hours, and the reaction was terminated when the NCO content was confirmed to be 0.2% by mass or less using a potentiometric automatic titrator (product name AT-510, Kyoto Electronics Manufacturing Co., Ltd.), yielding urethane acrylate. Analysis by GPC revealed that the weight-average molecular weight of the urethane acrylate was 8500 (equivalent to standard polystyrene). The GPC analysis was performed under the same conditions as the analysis of the weight-average molecular weight of the polyurethane resin described above.

[0091] (Preparation of conductive particles) A nickel layer with a thickness of 0.2 μm was formed on the surface of polystyrene particles, and then a gold layer with a thickness of 0.04 μm was formed on the outside of this nickel layer. In this way, conductive particles with an average particle size of 5 μm were produced.

[0092] [Examples 1-5 and Comparative Examples 1-3] (Preparation of laminated films with adhesive films) The raw materials shown in Table 2 were mixed in the mass ratio (solid content mass ratio) shown in Table 2 to obtain a coating solution for forming an adhesive film. This coating solution was applied to a 50 μm thick polyethylene terephthalate (PET) film using a coating apparatus. The coating film was hot-air dried at 70°C for 10 minutes to form an adhesive film with a thickness of 16 μm. This resulted in a laminated film in which the adhesive film was laminated on a PET film support.

[0093] The details of each component shown in Table 2 are as follows: (a) Component: Thermoplastic resin Polyurethane resin: A polyurethane resin synthesized as described above was used. Phenoxy resin: The PKHC (manufactured by Union Carbide Co., Ltd., trade name, weight-average molecular weight 45000) was used in the form of a 40% by mass solution prepared by dissolving 40 g of PKHC in 60 g of methyl ethyl ketone. ((b) Component: Radical polymerizable compound) Urethane acrylate: The urethane acrylate synthesized as described above was used. Acrylate phosphate: P-2M (Kyoeisha Chemical Co., Ltd., product name) ((c) Component: Radical polymerization initiator) The peroxide used was 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (trade name: Perocta-O, manufactured by NOF Corporation, half-life temperature at 1 minute: 124.3°C). ((d) component: insulating particles) Silica microparticles: 10 g of R104 (manufactured by Nippon Aerosil Co., Ltd., trade name, average particle size: 12 nm) were dispersed in a mixed solvent of 45 g of toluene and 45 g of ethyl acetate, and used in the form of a dispersion with a solid content of 10% by mass. Organic microparticles A: BTA 751 (manufactured by Rohm & Haas, trade name, core-shell type microparticles, average particle size: 0.2-0.3 μm) were dispersed in 90 g of methyl ethyl ketone in the form of a dispersion with a solid content of 10% by mass. Organic microparticles B: CE-800T (manufactured by Negami Kogyo Co., Ltd., product name, polyurethane beads, average particle size: 6 μm) were dispersed in 90 g of methyl ethyl ketone in the form of a dispersion with a solid content of 10% by mass. ((e) Component: Conductive particles) Conductive particles: Conductive particles prepared as described above were used. (Other ingredients) Silane coupling agent: KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd., product name)

[0094] (Fabrication of the connector) Using the above adhesive film as a circuit connection material, a flexible circuit board (FPC) having 220 copper circuits with a line width of 75 μm, a pitch of 150 μm, and a thickness of 18 μm was connected to a glass substrate. The connection was made using a thermocompression bonding device (heating method: constant heat type, manufactured by Nichika Setsubi Engineering Co., Ltd.) by heating and pressurizing at 160°C and 2 MPa for 5 seconds. As a result, a connection body was created in which the FPC and the glass substrate were connected by the cured adhesive film over a width of 1.2 mm.

[0095] (Measurement of mean linear expansion coefficient (CTE)) Multiple adhesive films were laminated together using a laminator to a thickness of 100 ± 20 μm, and then cured in an oven at 180°C for 1 hour to prepare a cured sample. The linear expansion coefficient of the obtained cured sample was measured using a thermal expansion coefficient measuring device (manufactured by Hitachi High-Tech Science Co., Ltd.) with a sample length of 10 mm and a width of 5 mm, using the tensile mode and load applied to the cross-sectional area (mm²). 2 ) 163.4 mN / mm 2 The value obtained by multiplying by was used, and measurements were taken under conditions of a temperature range of -5 to 250°C and a heating rate of 5°C per minute. From the measurement results, the mean coefficient of linear thermal expansion (CTE) at 80 to 90°C was read.

[0096] (Measurement of flow rate) The above adhesive film was punched out into a circle with a diameter of 1.0 mm, sandwiched between cover slips (manufactured by AS ONE Corporation) to form a test specimen, and a photograph of the adhesive film portion was taken using a microscope (manufactured by Nikon Corporation). The area A1 of the adhesive film was measured using image analysis software NIS-Elements D (manufactured by Nikon Corporation). Next, the adhesive film was heated and pressurized at 160°C and 2 MPa for 5 seconds using a flip-chip bonder FCB3 (manufactured by Panasonic Corporation), and the area A2 of the adhesive film was measured in the same manner. The flow rate was calculated from the rate of change of the area of ​​the adhesive film before and after heating and pressurizing (see formula below). Flow rate (%) = (A2 / A1) × 100

[0097] (Evaluation of saltwater resistance) The connectors prepared as described above were immersed in a 5% by mass NaCl aqueous solution at 25°C for 12 hours, then dried. The presence or absence of delamination at the circuit connection area was checked using a microscope (product name: ECLIPSE L200, manufactured by Nikon Corporation). The percentage of the total area of ​​the circuit connection area that was delaminated from the circuit material (FPC and glass substrate) was determined. Those with no delamination were classified as A, those with a small amount of delamination (delamination area less than 20% of the total area) as B, and those with delamination (delamination area 20% or more of the total area) as C. The results are shown in Table 2.

[0098] [Table 2]

[0099] As is clear from the results shown in Table 2, the adhesive film of the example was found to exhibit excellent saltwater resistance when the flow rate was 140% or more at a heating temperature of 160°C, a pressure of 2 MPa, and a heating time of 5 seconds, and the CTE was 130 ppm / K or less on average at 80-90°C. In contrast, it was found that excellent saltwater resistance could not be obtained when the flow rate was less than 140% or when the CTE was greater than 130 ppm / K. [Explanation of Symbols]

[0100] 1...Connector, 5...Insulating adhesive layer, 6...Insulating particles, 7...Conductive particles, 8...Support, 10...Connecting member, 11...Insulating layer, 20...First circuit member, 21...First circuit board, 21a...Main surface, 22...First circuit electrode, 30...Second circuit member, 31...Second circuit board, 31a...Main surface, 32...Second circuit electrode, 40...Adhesive film, 100...Laminated film.

Claims

1. A circuit connection adhesive film for connecting a first circuit member, on which a first circuit electrode is formed on the main surface of a first substrate, and a second circuit member, on which a second circuit electrode is formed on the main surface of a second substrate, with the first circuit electrode and the second circuit electrode facing each other. The adhesive film comprises (a) a thermoplastic resin, (b) a radical polymerizable compound, (c) a radical polymerization initiator, and (d) insulating particles. The thermoplastic resin (a) comprises a polyurethane resin and a phenoxy resin. The (b) radical polymerizable compound includes a (meth)acrylate compound, The (d) insulating particles include silica fine particles, The content of the silica fine particles is 1500 / 72.5 to 2000 / 72.5 parts by mass per 100 parts by mass of the total amount of (a) thermoplastic resin and (b) radical polymerizable compound. An adhesive film for circuit connection, wherein the flow rate of the adhesive film is 140% or more at a heating temperature of 160°C, a pressure of 2 MPa, and a heating time of 5 seconds, and the coefficient of linear expansion of the cured product of the adhesive film is 130 ppm / K or less on average at 80-90°C.

2. The circuit connection adhesive film according to claim 1, wherein the insulating particles (d) include organic fine particles.

3. The circuit connection adhesive film according to claim 2, wherein the organic fine particles include fine particles made of at least one resin selected from the group consisting of polyurethane resins and silicone resins.

4. The circuit connection adhesive film according to any one of claims 1 to 3, wherein the average particle size of the insulating particles (d) is 0.001 to 35 μm.

5. (e) The circuit connection adhesive film according to any one of claims 1 to 4, further comprising conductive particles.

6. A connecting body comprising a pair of circuit members having circuit electrodes and arranged opposite each other, and a connecting member provided between the pair of circuit members for bonding the pair of circuit members together, wherein the circuit electrode of one of the circuit members and the circuit electrode of the other circuit member are electrically connected, and the connecting member is a cured product of the adhesive film for circuit connection described in any one of claims 1 to 5.

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