Circuit-connecting adhesive film, method for manufacturing the same, method for manufacturing a circuit-connecting structure, and adhesive film storage assembly

Abstract

The present application provides an adhesive film for circuit connection, a method for manufacturing the same, a method for manufacturing a circuit connection structure, and an adhesive film storage assembly. The adhesive film for circuit connection includes a first adhesive layer containing conductive particles, and a second adhesive layer laminated on the first adhesive layer, a ratio of a DSC heat release amount of the first adhesive layer to a DSC heat release amount of the second adhesive layer is less than or equal to 0.4, the first adhesive layer is composed of a cured product of a first curable composition, the first curable composition contains a radical polymerizable compound having a radical polymerizable group and a thermal radical polymerization initiator, and the radical polymerizable compound having a radical polymerizable group is a (poly)urethane (meth)acrylate compound.

Description

[0001] This application is a divisional application of Chinese patent application No. 2018800586461, filed on September 7, 2018, entitled "Adhesive film for circuit connection and manufacturing method thereof, manufacturing method of circuit connection structure and adhesive film storage assembly". Technical Field

[0002] This invention relates to an adhesive film for circuit connection and a method for manufacturing the same, a method for manufacturing a circuit connection structure, and an adhesive film storage assembly. Background Technology

[0003] Conventionally, various adhesive materials have been used for circuit connections. For example, as an adhesive material for connecting a liquid crystal display to a tape-on-a-pack (TCP), a flexible printed circuit board (FPC) to a TCP, or an FPC to a printed circuit board, an adhesive film for circuit connections is used, which disperses conductive particles in the adhesive and has anisotropic conductivity. Specifically, a circuit connection structure is obtained by bonding circuit components to each other using circuit connection portions formed by the adhesive film for circuit connections, and electrically connecting the electrodes on the circuit components to each other via the conductive particles in the circuit connection portions.

[0004] In the field of precision electronic devices using adhesive films for circuit connections with anisotropic conductivity, the density of circuits is increasing, and electrode widths and electrode spacings are becoming extremely narrow. Therefore, achieving high connection reliability by efficiently capturing conductive particles on tiny electrodes (improving the capture rate of conductive particles) is not always easy.

[0005] In response, for example, Patent Document 1 proposes a method to concentrate conductive particles on one side of an anisotropic conductive adhesive sheet and separate the conductive particles from each other.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2005 / 54388 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in the method of Patent Document 1, conductive particles flow during circuit connection, and sometimes these particles leak out between opposing electrode circuits, leaving room for improvement in the capture rate of conductive particles. Furthermore, when a circuit connection structure obtained using a conventional circuit connection adhesive film is placed in a high-temperature and high-humidity environment (e.g., 85°C, 85%RH), peeling sometimes occurs between the circuit components and the circuit connection portion. Such peeling can reduce the connection reliability of the circuit connection structure.

[0011] Therefore, the object of the present invention is to provide an adhesive film for circuit connection that can improve the capture rate of conductive particles between the relative electrodes of the circuit connection structure and obtain a circuit connection structure that is not prone to peeling between circuit components and circuit connection parts under high temperature and high humidity environments, a method for manufacturing the same, a method for manufacturing a circuit connection structure using the adhesive film, and an adhesive film storage assembly having the adhesive film.

[0012] Methods for solving problems

[0013] An adhesive film for circuit connection according to one aspect of the present invention comprises: a first adhesive layer containing conductive particles, and a second adhesive layer laminated on the first adhesive layer, wherein the ratio of the DSC heat release of the first adhesive layer to the DSC heat release of the second adhesive layer is less than or equal to 0.4.

[0014] According to this adhesive film for circuit connection, the capture rate of conductive particles between the opposite electrodes of the circuit connection structure can be improved. Therefore, according to this adhesive film for circuit connection, the connection resistance between the opposite electrodes of the circuit connection structure can be reduced. Furthermore, according to this adhesive film for circuit connection, a circuit connection structure that is less prone to delamination between circuit components and circuit connections under high temperature and high humidity environments (e.g., 85°C, 85%RH) can be obtained. In other words, according to this adhesive film for circuit connection, the adhesion between circuit components and circuit connections under high temperature and high humidity environments can be improved. Moreover, according to this adhesive film for circuit connection, low connection resistance can be maintained even under high temperature and high humidity environments (e.g., 85°C, 85%RH). That is, according to this adhesive film for circuit connection, the connection reliability of the circuit connection structure can be improved.

[0015] A method for manufacturing an adhesive film for circuit connection according to one aspect of the present invention includes: a preparation step of preparing a first adhesive layer; and a lamination step of laminating a second adhesive layer composed of a second curable composition onto the first adhesive layer. The preparation step includes a curing step, wherein the first curable composition is cured by irradiating or heating the layer composed of the first curable composition containing conductive particles to obtain the first adhesive layer. In the curing step, the first curable composition is cured such that the ratio of the DSC heat release of the first adhesive layer to the DSC heat release of the second adhesive layer is less than or equal to 0.4. According to this method, an adhesive film for circuit connection of a circuit connection structure that can improve the capture rate of conductive particles between the opposite electrodes of the circuit connection structure and is less prone to delamination between circuit components and circuit connection portions under high temperature and high humidity environments can be obtained.

[0016] The first adhesive layer may be composed of a cured product of the first curable composition, which may contain a free radical polymerizable compound having free radical polymerizable groups.

[0017] The second adhesive layer may be composed of a second curable composition, which may contain a free radical polymerizable compound having free radical polymerizable groups.

[0018] The thickness of the first adhesive layer can be 0.2 to 0.8 times the average particle size of the conductive particles.

[0019] A method for manufacturing a circuit connection structure according to one aspect of the present invention includes the following steps: placing the aforementioned adhesive film for circuit connection between a first circuit member having a first electrode and a second circuit member having a second electrode; and thermally pressing the first circuit member and the second circuit member together to electrically connect the first electrode and the second electrode to each other. According to this method, a circuit connection structure with excellent capture rate of conductive particles between the opposing electrodes and which is less prone to peeling between the circuit member and the circuit connection portion under high temperature and high humidity conditions can be obtained.

[0020] An adhesive film storage assembly according to one aspect of the present invention includes the above-mentioned adhesive film for circuit connection and a storage member for storing the adhesive film. The storage member has a viewing portion that allows the interior of the storage member to be viewed from the outside, and the transmittance of the viewing portion for light with a wavelength of 365 nm is less than or equal to 10%.

[0021] Furthermore, the environment in which the adhesive film for circuit connections is used is generally a cleanroom, a room where temperature, humidity, and cleanliness are managed to a certain level. When the adhesive film for circuit connections is shipped from the production site, it is stored in packaging bags or other storage components to prevent direct exposure to outdoor air and subsequent quality degradation due to dust and moisture. Typically, to allow for the identification of information such as the product name, batch number, and expiration date affixed to the internal adhesive film from the outside of the storage component, a viewing section made of transparent material is provided on the storage component.

[0022] However, according to the research of the inventors, when the aforementioned adhesive film for circuit connection is stored or transported in conventional storage components, the following undesirable conditions sometimes occur: peeling easily occurs between the circuit components and the circuit connection parts under high temperature and humidity conditions; the effect of improving the capture rate is reduced, and the effect of reducing the connection resistance of the adhesive film is reduced due to decreased fluidity. Based on these research results, the inventors conducted further research and found that when the first adhesive layer is composed of a cured product of a photocurable composition and the second adhesive layer is composed of a curable composition containing a polymeric compound that can react with the photopolymerization initiator in the photocurable composition, the second adhesive layer will cure during storage and transportation, resulting in the aforementioned undesirable conditions. Therefore, based on the hypothesis that the polymerizable compound in the second adhesive layer was polymerized by free radicals derived from the photopolymerization initiator remaining in the first adhesive layer, the inventors conducted further research and found that by manufacturing an adhesive film storage assembly having the aforementioned specific storage component, the curing of the second adhesive layer during storage or transportation can be suppressed, and the occurrence of the aforementioned adverse conditions can be suppressed.

[0023] That is, according to one aspect of the adhesive film storage assembly of the present invention, when a compound that can react with the photopolymerization initiator in the first adhesive layer is used as the polymerizable compound in the second adhesive layer, the curing of the second adhesive layer during storage or transportation of the adhesive film can be suppressed, and adverse conditions such as peeling between circuit components and circuit connection parts that are prone to occur in high temperature and high humidity environments, reduced effect of improved capture rate and reduced flowability leading to reduced effect of reduced connection resistance of the adhesive film can be suppressed.

[0024] Invention Effects

[0025] According to the present invention, an adhesive film for circuit connection that can improve the capture rate of conductive particles between the opposite electrodes of a circuit connection structure and obtain a circuit connection structure that is not prone to peeling between circuit components and circuit connection parts under high temperature and high humidity environments can be provided, as well as a method for manufacturing the same, a method for manufacturing a circuit connection structure using the adhesive film, and an adhesive film storage assembly having the adhesive film. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view illustrating an adhesive film for circuit connection according to one embodiment of the present invention.

[0027] Figure 2 This is a schematic cross-sectional view illustrating a circuit connection structure according to one embodiment of the present invention.

[0028] Figure 3 This is a schematic cross-sectional view illustrating the manufacturing process of a circuit connection structure according to one embodiment of the present invention.

[0029] Figure 4 This is a perspective view illustrating an adhesive film storage assembly according to one embodiment of the present invention. Detailed Implementation

[0030] The following is an explanation of the appendix, which may vary depending on the circumstances. Figure 1 The embodiments of the present invention will be described in detail below. It should be noted that the upper and lower limits individually stated in this specification can be arbitrarily combined. Furthermore, in this specification, "(meth)acrylate" refers to at least one of an acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl".

[0031] <Adhesive film for circuit connection>

[0032] Figure 1 This is a schematic cross-sectional view illustrating an adhesive film for circuit connections in one embodiment. (Example) Figure 1 As shown, the adhesive film 1 for circuit connection (hereinafter also referred to as "adhesive film 1") includes a first adhesive layer 2 and a second adhesive layer 3 stacked on the first adhesive layer 2. The first adhesive layer 2 contains conductive particles 4.

[0033] In the adhesive film 1, conductive particles 4 are dispersed in the first adhesive layer 2. Therefore, the adhesive film 1 is an anisotropic conductive adhesive film with anisotropic conductivity. The adhesive film 1 is located between a first circuit component having a first electrode and a second circuit component having a second electrode, and is used to thermally press the first circuit component and the second circuit component together, and to electrically connect the first electrode and the second electrode to each other.

[0034] In this embodiment, the ratio (Cx / Cy) of the DSC heat release Cx of the first adhesive layer to the DSC heat release Cy of the second adhesive layer 3 is less than or equal to 0.4. Here, "DSC heat release" refers to the heat release (J / g) measured by DSC (Differential Scanning Calorimetry). A higher DSC heat release of the adhesive layer means a higher heat release of the adhesive layer when the circuit components are connected to each other. Regarding DSC heat release, there is a tendency that the higher the residual amount of components that undergo exothermic reactions (e.g., uncured components such as polymeric compounds) in the adhesive layer, the greater the heat release. The DSC heat release Cx and DSC heat release Cy can be determined by performing DSC measurements on the first adhesive layer 2 and the second adhesive layer 3 using the method described in the examples.

[0035] According to adhesive film 1, since the ratio of DSC heat release (Cx / Cy) is less than or equal to 0.4, the capture rate of conductive particles between the opposite electrodes of the circuit connection structure can be improved. Therefore, according to adhesive film 1, the connection resistance of the opposite electrodes of the circuit connection structure can be reduced.

[0036] Furthermore, according to the adhesive film 1, since the ratio of the DSC heat release (Cx / Cy) is less than or equal to 0.4, it is possible to obtain a circuit connection structure that is not prone to peeling between circuit components and circuit connection parts under high temperature and high humidity environments (e.g., 85°C, 85%RH).

[0037] Furthermore, according to adhesive film 1, since the ratio of DSC heat dissipation (Cx / Cy) is less than or equal to 0.4, low connection resistance can be maintained even under high temperature and high humidity environments (e.g., 85°C, 85%RH). That is, according to adhesive film 1, the connection reliability of the circuit connection structure can be improved.

[0038] Furthermore, the adhesive film 1 is sometimes stored and used as an adhesive roll by cutting it into narrow strips as an adhesive film with a substrate formed on one side of the substrate, and then winding it onto a core. For this adhesive roll, good anti-adhesion properties are required; that is, the adhesive film 1 should not easily peel off from the substrate when the adhesive film with the substrate is output from the adhesive roll. However, with conventional adhesive films, it may be difficult to obtain good anti-adhesion properties when cut into narrow strips with a width of 0.4 to 1.0 mm. On the other hand, in the adhesive film 1 of this embodiment, since the ratio of DSC heat release (Cx / Cy) is less than or equal to 0.4, adhesion (bonding) between the first adhesive layer 2 and the substrate can be suppressed. Therefore, by providing the substrate on the side of the second adhesive layer 3 opposite to the first adhesive layer 2, there is a tendency to obtain good anti-adhesion properties even when cut into narrow strips as described above. It should be noted that the adhesion resistance can be evaluated, for example, by testing whether the adhesive roll can be pulled out without any problems after being placed in a 30°C environment for 24 hours.

[0039] From the viewpoint of further improving the capture rate of conductive particles and reducing the likelihood of delamination between circuit components and circuit connections under high temperature and high humidity environments (e.g., 85°C, 85%RH), the ratio of DSC heat dissipation (Cx / Cy) is preferably less than or equal to 0.40, more preferably less than or equal to 0.30, and even more preferably less than or equal to 0.20. From the viewpoint of improving the affinity between the first adhesive layer and the second adhesive layer and obtaining better connection reliability, the ratio of DSC heat dissipation (Cx / Cy) can be greater than or equal to 0.01 or greater than or equal to 0.05. From these viewpoints, the ratio of DSC heat dissipation (Cx / Cy) can be 0.01~0.40, 0.01~0.30, 0.01~0.20, 0.05~0.40, 0.05~0.30, or 0.05~0.20.

[0040] (First adhesive layer)

[0041] The first adhesive layer 2 is, for example, composed of a cured product of a first curable composition. The first curable composition can be a photocurable composition or a thermosetting composition. The first curable composition, for example, contains (A) a polymerizable compound (hereinafter also referred to as "component (A)"), (B) a polymerization initiator (hereinafter also referred to as "component (B)"), and (C) conductive particles 4 (hereinafter also referred to as "component (C)"). In the case where the first curable composition is a photocurable composition, the first curable composition contains a photopolymerization initiator as component (B); in the case where the first curable composition is a thermosetting composition, the first curable composition contains a thermal polymerization initiator as component (B). Such a first adhesive layer 2 can be obtained, for example, by polymerizing component (A) by irradiating or heating the layer composed of the first curable composition with light, thereby curing the first curable composition. That is, the first adhesive layer 2 may contain conductive particles 4 and an adhesive component 5 formed by curing the components of the first curable composition other than the conductive particles 4. The first adhesive layer 2 can be a cured product formed by completely curing the first curing composition, or it can be a cured product formed by partially curing the first curing composition. That is, when the first curing composition contains component (A) and component (B), the adhesive component 5 can contain unreacted component (A) and component (B), or it can not contain unreacted component (A) and component (B).

[0042] [(A) Component: Polymer compound]

[0043] (A) Component is, for example, a compound that polymerizes by free radicals, cations, or anions generated by irradiation or heating of a polymerization initiator (photopolymerization initiator or thermal polymerization initiator) with light (e.g., ultraviolet light). (A) Component can be any of a monomer, oligomer, or polymer. As (A) Component, a single compound may be used alone, or multiple compounds may be used in combination.

[0044] Component (A) has at least one polymerizable group. The polymerizable group is, for example, a group containing a polymerizable unsaturated double bond (ethylene unsaturated bond). From the viewpoint of easily obtaining the desired DSC exothermic effect, and from the viewpoint of further improving the reduction effect of connection resistance and the superior connection reliability, the polymerizable group is preferably a free radical polymerizable group that reacts via a free radical. That is, component (A) is preferably a free radical polymerizable compound. Examples of free radical polymerizable groups include vinyl, allyl, styrene, alkenyl, alkenyl, (meth)acryloyl, maleimide, etc. From the viewpoint of easily obtaining the physical properties and crosslinking density required for reducing connection resistance after polymerization, the number of polymerizable groups in component (A) can be greater than or equal to 2; from the viewpoint of suppressing curing shrinkage during polymerization, the number of polymerizable groups in component (A) can be less than or equal to 10. Furthermore, in order to achieve a balance between crosslinking density and curing shrinkage, polymerizable compounds outside the above range can be used in addition to polymerizable compounds with a number of polymerizable groups within the above range.

[0045] Specific examples of component (A) include: (meth)acrylate compounds, maleimide compounds, vinyl ether compounds, allyl compounds, styrene derivatives, acrylamide derivatives, nadicimide derivatives, natural rubber, isoprene rubber, butyl rubber, nitrile rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxylated nitrile rubber, etc.

[0046] Examples of (meth)acrylate compounds include: epoxy (meth)acrylates, (poly)urethane (meth)acrylates, (meth)acrylate methyl methacrylate, polyether (meth)acrylates, polyester (meth)acrylates, polybutadiene (meth)acrylates, organosilicon acrylates, (meth)acrylate ethyl methacrylate, (meth)acrylate 2-cyanoethyl methacrylate, (meth)acrylate 2-(2-ethoxyethoxy)ethyl methacrylate, (meth)acrylate 2-ethoxyethyl methacrylate, (meth)acrylate 2-ethylhexyl methacrylate, (methyl)acrylate (Meth)hexyl acrylate, (Meth)acrylate 2-hydroxyethyl acrylate, (Meth)acrylate isopropyl acrylate, (Meth)acrylate hydroxypropyl acrylate, (Meth)acrylate isobutyl acrylate, (Meth)acrylate isobornyl acrylate, (Meth)acrylate isodecyl acrylate, (Meth)acrylate isooctyl acrylate, (Meth)acrylate lauryl acrylate, (Meth)acrylate 2-methoxyethyl acrylate, (Meth)acrylate 2-phenoxyethyl acrylate, (Meth)acrylate tetrahydrofurfuryl acrylate, 2-(Meth)acrylate acryloyloxyethyl phosphate, (Meth)acrylate N,N-dimethylamino acrylate ethyl methacrylate, N,N-dimethylaminopropyl methacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, polyethylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, cyclohexyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, neopentyl glycol di(meth)acrylate, pentaerythritol (meth)acrylate, dipentaerythritol Hexa(meth)acrylate, isocyanuric acid modified difunctional (meth)acrylate, isocyanuric acid modified trifunctional (meth)acrylate, tricyclodecyl acrylate, dihydroxymethyl-tricyclodecane diacrylate, 2-hydroxy-1,3-diacryloyloxypropane, 2,2-bis[4-(acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloyloxypolyethoxy)phenyl]propane, 2,2-di(meth)acryloyloxydiethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate, etc.

[0047] Examples of maleimide compounds include: 1-methyl-2,4-bismaleimide benzene, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, N,N'-m-tolylenebismaleimide, N,N'-4,4-biphenylenebismaleimide, N,N'-4,4-(3,3'-dimethylbiphenylene)bismaleimide, N,N'-4,4-(3,3'-dimethyldiphenylmethane)bismaleimide, N,N'-4,4-(3,3'-diethyldiphenylmethane)bismaleimide, and N,N'-4,4-diphenylmethanebismaleimide. N,N'-4,4-diphenylpropane bismaleimide, N,N'-4,4-diphenyl ether bismaleimide, N,N'-3,3-diphenyl sulfone bismaleimide, 2,2-bis(4-(4-maleimide phenoxy)phenyl)propane, 2,2-bis(3-sec-butyl-4-8(4-maleimide phenoxy)phenyl)propane, 1,1-bis(4-(4-maleimide phenoxy)phenyl)decane, 4,4'-cyclohexylene-bis(1-(4-maleimide phenoxy)-2-cyclohexylbenzene, 2,2'-bis(4-(4-maleimide phenoxy)phenyl)hexafluoropropane, etc.

[0048] Examples of vinyl ether compounds include diethylene glycol divinyl ether, dipropylene glycol divinyl ether, cyclohexanediethanol divinyl ether, and trimethylolpropane trivinyl ether.

[0049] Examples of allyl compounds include 1,3-diallyl phthalate, 1,2-diallyl phthalate, and triallyl isocyanurate.

[0050] From the viewpoint of achieving an excellent balance between curing reaction rate and cured physical properties, component (A) is preferably a (meth)acrylate compound. From the viewpoint of balancing cohesion for reducing bonding resistance with elongation for improving adhesive strength and obtaining superior adhesive properties, component (A) can be a (poly)urethane (meth)acrylate compound (urethane (meth)acrylate compound or polyurethane (meth)acrylate compound). Furthermore, from the viewpoint of improving cohesion and reducing bonding resistance, component (A) can be a (meth)acrylate compound with a high Tg backbone such as dicyclopentadiene.

[0051] From the viewpoint of achieving a balance between crosslinking density and curing shrinkage, further reducing connection resistance, and improving connection reliability, component (A) can be a compound with polymerizable groups such as vinyl, allyl, or (meth)acryloyl groups introduced into the ends or side chains of thermoplastic resins such as acrylic resin, phenoxy resin, and polyurethane resin (e.g., polyurethane (meth)acrylate). In this case, from the viewpoint of an excellent balance between crosslinking density and curing shrinkage, the weight-average molecular weight of component (A) can be greater than or equal to 3000, greater than or equal to 5000, or greater than or equal to 10,000. Furthermore, from the viewpoint of excellent compatibility with other components, the weight-average molecular weight of component (A) can be less than or equal to 1,000,000, less than or equal to 500,000, or less than or equal to 250,000. It should be noted that the weight-average molecular weight refers to the value determined by gel permeation chromatography (GPC) using a standard curve based on standard polystyrene, under the conditions described in the examples.

[0052] (A) The component preferably comprises a radical polymerizable compound having a phosphate ester structure represented by the following general formula (1) as a (meth)acrylate compound. In this case, the adhesive strength to inorganic surfaces (such as metals) is improved, thus making it suitable for bonding, for example, electrodes to each other (e.g., circuit electrodes to each other).

[0053] [Chemistry 1]

[0054]

[0055] [In the formula, n represents an integer from 1 to 3, and R represents a hydrogen atom or a methyl group.]

[0056] The aforementioned free radical polymerizable compounds with phosphate ester structures can be obtained, for example, by reacting anhydrous phosphoric acid with 2-hydroxyethyl (meth)acrylate. Specific examples of free radical polymerizable compounds with phosphate ester structures include mono(2-(meth)acryloyloxyethyl) phosphate esters and di(2-(meth)acryloyloxyethyl) phosphate esters.

[0057] From the viewpoint of easily obtaining the crosslinking density required to reduce connection resistance and improve connection reliability, the content of component (A) can be greater than or equal to 5% by mass, greater than or equal to 10% by mass, or greater than or equal to 20% by mass, based on the total mass of the first curable composition. From the viewpoint of suppressing curing shrinkage during polymerization, the content of component (A) can be less than or equal to 90% by mass, less than or equal to 80% by mass, or less than or equal to 70% by mass, based on the total mass of the first curable composition.

[0058] [(B) Component: Polymerization initiator]

[0059] Component (B) can be a photopolymerization initiator (photoradical polymerization initiator, photocationic polymerization initiator, or photoanionic polymerization initiator) that generates free radicals, cations, or anions 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 wavelengths in the range of 365 nm (e.g., ultraviolet light). It can also be a thermal polymerization initiator (thermal radical polymerization initiator, thermal cationic polymerization initiator, or thermal anionic polymerization initiator) that generates free radicals, cations, or anions upon irradiation with heat. From the viewpoints of easily obtaining the desired DSC heat release, further improving the reduction effect on connection resistance and enhancing connection reliability, and making curing at low temperatures and short times easier, component (B) is preferably a radical polymerization initiator (photoradical polymerization initiator or thermal radical polymerization initiator). As component (B), a single compound can be used, or multiple compounds can be used in combination. For example, the first curable composition may also contain both a photopolymerization initiator and a thermal polymerization initiator as component (B).

[0060] Photoradical polymerization initiators decompose upon exposure to light, generating free radicals. In other words, a photoradical polymerization initiator is a compound that generates free radicals by imparting light energy from an external source. Examples of photoradical polymerization initiators include compounds having structures such as oxime esters, biimidazoles, acridines, α-aminoalkylphenyl ketones, aminobenzophenones, N-phenylglycine, acylphosphine oxides, benzoyladium dimethyl ketals, and α-hydroxyalkylphenyl ketones. From the viewpoint of easily obtaining the desired DSC exothermic effect and achieving a superior reduction in connection resistance, photoradical polymerization initiators preferably have at least one structure selected from the group consisting of oxime esters, α-aminoalkylphenyl ketones, and acylphosphine oxides.

[0061] 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-benzoyl oxime, 1,3-diphenyltrione-2-(O-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxytrione-2-(O-benzoyl)oxime, 1,2-octanedione, 1-[4-(phenylthio)phenyl-,2-(O-benzoyl oxime)], acetone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-( O-acetyl oxime, etc.

[0062] Specific examples of compounds having the α-aminoalkylphenyl ketone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one, 2-benzyl-2-dimethylamino-1-morpholinylphenylbutanone-1, etc.

[0063] 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, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc.

[0064] Thermal free radical polymerization initiators decompose upon heating, generating free radicals. In other words, a thermal free radical polymerization initiator is a compound that generates free radicals by imparting thermal energy from an external source. As a thermal free radical polymerization initiator, one can arbitrarily choose from conventionally known organic peroxides and azo compounds. From the viewpoints of stability, reactivity, and compatibility, organic peroxides with a 1-minute half-life temperature of 90–175°C and a weight-average molecular weight of 180–1000 are preferred as thermal free radical polymerization initiators. Because the 1-minute half-life temperature is within this range, storage stability is superior, and the free radical polymerizability is sufficiently high, allowing for rapid curing.

[0065] Specific examples of organic peroxides include: 1,1,3,3-tetramethyl butyl peroxide, di(4-tert-butylcyclohexyl) peroxide dicarbonate, di(2-ethylhexyl) peroxide dicarbonate, cumyl peroxide, dilauroyl peroxide, 1-cyclohexyl-1-methyl ethyl peroxide, tert-hexyl peroxide, tert-butyl peroxide, tert-butyl peroxypentanoate, 1,1,3,3-tetramethyl butyl peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxide)hexane, tert-hexyl peroxide, tert-butyl peroxide, tert-butyl peroxide, tert-butyl peroxide, tert-butyl peroxide, tert-butyl peroxide, tert-butyl peroxide, tert-butyl peroxide, tert-pentyl peroxide, di-tert-butyl peroxide, and 3,5,5-trimethyl peroxide. The following are listed as examples of peroxides: tert-amyl hexanoate, 3-hydroxy-1,1-dimethyl butyl peroxynedecanoate, tert-amyl peroxynedecanoate, tert-amyl peroxy-2-ethylhexanoate, di(3-methylbenzoyl) peroxide, benzoyl peroxide, di(4-methylbenzoyl) peroxide, tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peroxymaleic acid, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, 2,5-dimethyl-2,5-di(3-methylbenzoyl peroxy)hexane, tert-butyl peroxy-2-ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoyl peroxy)hexane, tert-butyl peroxybenzoate, dibutyl peroxytrimethyl adipate, tert-amyl peroxyoctanoate, tert-amyl peroxyisononanoate, and tert-amyl peroxybenzoate.

[0066] Specific examples of azo compounds include: 2,2'-azobis-2,4-dimethylpentanonitrile, 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanopentanoic acid), 1,1'-azobis(1-cyclohexanecarboxylonitrile), etc.

[0067] From the viewpoints of excellent rapid curing properties and excellent reduction in connection resistance, the content of component (B) can be greater than or equal to 0.1% by mass or greater than or equal to 0.5% by mass, based on the total mass of the first curable composition. From the viewpoints of improved storage stability and excellent reduction in connection resistance, the content of component (B) can be less than or equal to 20% by mass, less than or equal to 10% by mass, or less than or equal to 5% by mass, based on the total mass of the first curable composition.

[0068] From the viewpoint of easily obtaining the desired viscosity, the first curable composition preferably contains at least one of a photopolymerization initiator and a thermal polymerization initiator as component (B). From the viewpoint of making the manufacture of adhesive films for circuit connection easier, the first curable composition more preferably contains a photopolymerization initiator.

[0069] [(C) Component: Conductive particles]

[0070] (C) is not particularly limited as long as it consists of conductive particles, and can be metal particles composed of metals such as Au, Ag, Ni, Cu, and solder; conductive carbon particles composed of conductive carbon, etc. (C) can also be coated conductive particles having a core and a coated layer, wherein the core includes non-conductive materials such as glass, ceramics, and plastics (polystyrene, etc.), and the coated layer contains the aforementioned metal or conductive carbon. Among these, coated conductive particles having a coated layer having a core and a coated layer, wherein the core comprises metal particles formed from a molten metal or plastic, and the coated layer contains metal or conductive carbon, are preferred. In this case, the cured product of the first curable composition can be easily deformed by heating or pressurizing, thus increasing the contact area between the electrodes and (C) when the electrodes are electrically connected to each other, further improving the conductivity between the electrodes.

[0071] Component (C) can also be insulating coated conductive particles, which include the aforementioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer covering the surface of the particles, wherein the insulating layer comprises an insulating material such as resin. If component (C) is an insulating coated conductive particle, even if the content of component (C) is high, the resin coating on the surface of the particles can suppress short circuits caused by contact between components (C), and can also improve the insulation between adjacent electrode circuits. Component (C) can be one of the aforementioned conductive particles used alone or in combination of two or more.

[0072] The maximum particle size of component (C) needs to be smaller than the minimum spacing between electrodes (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (C) can be greater than or equal to 1.0 μm, greater than or equal to 2.0 μm, or greater than or equal to 2.5 μm. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of component (C) can be less than or equal to 50 μm, less than or equal to 30 μm, or less than or equal to 20 μm. In this specification, for any 300 conductive particles, the particle size is measured using a scanning electron microscope (SEM), and the maximum value obtained is set as the maximum particle size of component (C). It should be noted that in cases where component (C) has protrusions or is not spherical, the particle size of component (C) is set as the diameter of the circle circumscribed by the conductive particles in the SEM image.

[0073] From the viewpoint of excellent dispersibility and conductivity, the average particle size of component (C) can be greater than or equal to 1.0 μm, greater than or equal to 2.0 μm, or greater than or equal to 2.5 μm. From the viewpoint of excellent dispersibility and conductivity, the average particle size of component (C) can be less than or equal to 50 μm, less than or equal to 30 μm, or less than or equal to 20 μm. In this specification, for any 300 conductive particles, the particle size is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle size is set as the average particle size.

[0074] In the first adhesive layer 2, component (C) is preferably uniformly dispersed. From the viewpoint of obtaining a stable connection resistance, the particle density of component (C) in the first adhesive layer 2 can be greater than or equal to 100 pcs / mm². 2 It can be greater than or equal to 1000 pcs / mm 2 It can also be greater than or equal to 2000pcs / mm 2 From the viewpoint of improving the insulation between adjacent electrodes, the particle density of component (C) in the first adhesive layer 2 can be less than or equal to 100,000 pcs / mm². 2 It can be less than or equal to 50,000 pcs / mm 2 It can also be less than or equal to 10000pcs / mm 2 .

[0075] From the viewpoint of further improving conductivity, the content of component (C) can be greater than or equal to 0.1% by volume, greater than or equal to 1% by volume, or greater than or equal to 5% by volume, based on the total volume of the first adhesive layer. From the viewpoint of easily suppressing short circuits, the content of component (C) can be less than or equal to 50% by volume, less than or equal to 30% by volume, or less than or equal to 20% by volume, based on the total volume of the first adhesive layer. It should be noted that the content of component (C) in the first curable composition (based on the total volume of the first curable composition) can be the same as the above range.

[0076] From the viewpoint of further improving conductivity, the content of component (C) can be greater than or equal to 0.05% by mass, greater than or equal to 0.5% by mass, or greater than or equal to 2.5% by mass, based on the total mass of the first adhesive layer. From the viewpoint of easily suppressing short circuits, the content of component (C) can be less than or equal to 25% by mass, less than or equal to 15% by mass, or less than or equal to 10% by mass, based on the total mass of the first adhesive layer. If the content of component (C) is within the above range, there is a tendency to significantly exert the effects of the present invention. It should be noted that the content of component (C) can be the same as the above range, based on the total mass of the first curable composition.

[0077] [Other ingredients]

[0078] The first curable composition may further contain other components besides components (A), (B), and (C). Examples of other components include thermoplastic resins, coupling agents, and fillers. These components may also be included in the first adhesive layer 2.

[0079] Examples of thermoplastic resins include phenoxy resins, polyester resins, polyamide resins, polyurethane resins, polyester-polyurethane resins, and acrylic rubber. When the first curing composition contains a thermoplastic resin, a first adhesive layer can be easily formed. Furthermore, when the first curing composition contains a thermoplastic resin, the stress in the first adhesive layer generated during the curing of the first curing composition can be mitigated. Additionally, when the thermoplastic resin has functional groups such as hydroxyl groups, the adhesiveness of the first adhesive layer is easily improved. Regarding the content of the thermoplastic resin, for example, based on the total mass of the first curing composition, it can be greater than or equal to 5% by mass and less than or equal to 80% by mass.

[0080] Examples of coupling agents include silane coupling agents having organic functional groups such as (meth)acryloyl, mercapto, amino, imidazole, and epoxy groups; silane compounds such as tetraalkoxysilanes; and tetraalkoxytitanate derivatives and polydialkyltitanate derivatives. When the first curable composition contains a coupling agent, the adhesion can be further improved. Regarding the content of the coupling agent, for example, based on the total mass of the first curable composition, it can be greater than or equal to 0.1% by mass and less than or equal to 20% by mass.

[0081] As a filler, examples include non-conductive fillers (e.g., non-conductive particles). When the first cured composition contains a filler, improved connection reliability can be further expected. The filler can be either inorganic or organic. Examples of inorganic fillers include metal oxide particles such as silica particles, alumina particles, silica-alumina particles, titanium dioxide particles, and zirconium oxide particles; and inorganic particles such as nitride particles. Examples of organic fillers include organic particles such as organosilicon particles, methacrylate-butadiene-styrene particles, acrylic-organosilicon particles, polyamide particles, and polyimide particles. These particles can have a uniform structure or a core-shell structure. The maximum diameter of the filler is preferably less than the minimum particle size of the conductive particles 4. Regarding the filler content, for example, based on the total volume of the first cured composition, it can be greater than or equal to 0.1% by volume and less than or equal to 50% by volume. Furthermore, regarding the filler content, for example, based on the total mass of the first cured composition, it can be greater than or equal to 0.05% by mass and less than or equal to 25% by mass.

[0082] The first curing composition may also contain other additives such as softeners, accelerators, degradation inhibitors, colorants, flame retardants, and thixotropic agents. The content of these additives, based on the total mass of the first curing composition, may be, for example, 0.1 to 10% by mass. These additives may also be included in the first adhesive layer 2.

[0083] The first curable composition may also contain a thermosetting resin in place of components (A) and (B), or contain a thermosetting resin in addition to components (A) and (B). The thermosetting resin is a resin that cures by heat and has at least one thermosetting group. For example, a thermosetting resin is a compound that crosslinks by reacting with a curing agent by heat. As a thermosetting resin, a single compound may be used, or multiple compounds may be used in combination.

[0084] From the perspective of easily obtaining the desired DSC heat release, and considering the further improvement in the reduction of connection resistance and the superior connection reliability, thermosetting groups can be, for example, epoxy groups, oxetyl groups, isocyanate groups, etc.

[0085] Specific examples of thermosetting resins include bisphenol-type epoxy resins, which are reaction products of epichlorohydrin with bisphenol A, F, AD, etc.; epoxy phenolic varnish resins, which are reaction products of epichlorohydrin with phenolic varnish, cresol phenolic varnish, etc.; naphthalene-based epoxy resins with a naphthalene ring-containing skeleton; and various epoxy compounds such as glycidyl amine and glycidyl ether, which have two or more glycidyl groups in one molecule.

[0086] When a thermosetting resin is used in place of components (A) and (B), for example, based on the total mass of the first curable composition, the content of the thermosetting resin in the first curable composition may be greater than or equal to 20% by mass and may be less than or equal to 80% by mass. When a thermosetting resin is used in addition to components (A) and (B), for example, based on the total mass of the first curable composition, the content of the thermosetting resin in the first curable composition may be greater than or equal to 30% by mass and may be less than or equal to 70% by mass.

[0087] When the first curable composition contains a thermosetting resin, the first curable composition may also contain a curing agent for the aforementioned thermosetting resin. Examples of curing agents for the thermosetting resin include thermal free radical generators, thermal cation generators, and thermal anion generators. Regarding the content of the curing agent, for example, it may be greater than or equal to 0.1 parts by weight and less than or equal to 20 parts by weight relative to 100 parts by weight of the thermosetting resin.

[0088] The first adhesive layer 2 may also contain unreacted components (A), (B), and other components derived from the first curing composition. It is speculated that if the adhesive film 1 of this embodiment is stored and transported using a conventional storage component, unreacted component (B) may remain in the first adhesive layer 2. Therefore, during storage and transport, a portion of the second curing composition in the second adhesive layer 3 may cure, resulting in the following adverse conditions: peeling between circuit components and circuit connections is likely to occur under high temperature and humidity conditions; the effect of improving the capture rate is reduced; and the effect of reducing the connection resistance of the adhesive film 1 is reduced due to decreased fluidity. Therefore, from the viewpoint of suppressing the occurrence of the above-mentioned adverse conditions, based on the total mass of the first adhesive layer, the content of component (B) in the first adhesive layer 2 can be less than or equal to 15% by mass, less than or equal to 10% by mass, or less than or equal to 5% by mass. Based on the total mass of the first adhesive layer, the content of component (B) in the first adhesive layer 2 can be greater than or equal to 0.1% by mass. It should be noted that when the first adhesive layer 2 contains a photopolymerization initiator as component (B), the occurrence of the above-mentioned adverse conditions can be suppressed by housing the adhesive film 1 in the housing member described later.

[0089] From the viewpoint of easily obtaining the cohesive strength required for good reliability after curing, the DSC heat release of the first curing composition can be greater than or equal to 5 J / g, greater than or equal to 10 J / g, or greater than or equal to 30 J / g. From the viewpoint of reducing curing shrinkage and obtaining good reliability, the DSC heat release of the first curing composition can be less than or equal to 300 J / g, less than or equal to 200 J / g, or less than or equal to 150 J / g.

[0090] From the viewpoint of improving adhesion to the second adhesive layer 3 and achieving good reliability, the DSC heat release Cx of the first adhesive layer 2 can be greater than or equal to 0.1 J / g, greater than or equal to 1 J / g, or greater than or equal to 2.5 J / g. From the viewpoint of further improving the capture rate of conductive particles and reducing the likelihood of delamination between circuit components and circuit connections under high temperature and high humidity environments (e.g., 85°C, 85%RH), the DSC heat release Cx can be less than or equal to 100 J / g, less than or equal to 50 J / g, or less than or equal to 35 J / g. The DSC heat release Cx can be adjusted by changing the composition of the first curing composition, changing the curing conditions of the first curing composition, etc.

[0091] From the viewpoint of easily suppressing short circuits caused by the aggregation of conductive particles 4, the thickness d1 of the first adhesive layer 2 can be greater than or equal to 0.2 times, or greater than or equal to 0.3 times, the average particle size of the conductive particles 4. From the viewpoint of easily capturing conductive particles 4 between electrodes, and further reducing connection resistance by efficiently flattening the conductive particles during hot pressing, the thickness d1 of the first adhesive layer 2 can be less than or equal to 0.8 times, or less than or equal to 0.7 times, the average particle size of the conductive particles 4. From these viewpoints, the thickness d1 of the first adhesive layer 2 can be 0.2 to 0.8 times, or 0.3 to 0.7 times, the average particle size of the conductive particles 4. When the thickness d1 of the first adhesive layer 2 and the average particle size of the conductive particles 4 satisfy the relationship described above, for example, as... Figure 1 As shown, a portion of the conductive particles 4 in the first adhesive layer 2 may protrude from the first adhesive layer 2 toward 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 of adjacent conductive particles 4, 4. Alternatively, the conductive particles 4 may not be exposed on the surface 2a of the first adhesive layer 2 opposite to the side opposite to the side of the second adhesive layer 3, and the opposite surface 2a becomes a flat surface.

[0092] The thickness d1 of the first adhesive layer 2 can be appropriately set according to the electrode height, etc., of the circuit components to be bonded. For example, the thickness d1 of the first adhesive layer 2 can be greater than or equal to 0.5 μm, and can be less than or equal to 20 μm. It should be noted that when a portion of the conductive particle 4 protrudes from the surface of the first adhesive layer 2 (e.g., protruding towards the second adhesive layer 3), the distance from the surface 2a of the first adhesive layer 2 opposite to the side of 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 of adjacent conductive particles 4, 4 (…). Figure 1The distance d1 represents 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 can be greater than or equal to 0.1 μm and less than or equal to 20 μm.

[0093] (Second adhesive layer)

[0094] The second adhesive layer 3 is, for example, composed of a second curable composition. The second curable composition contains, for example, (a) a polymerizable compound (hereinafter also referred to as component (a)) and (b) a polymerization initiator (hereinafter also referred to as component (b)). The second curable composition can be a thermosetting composition containing a thermal polymerization initiator as component (b), a photocurable composition containing a photopolymerization initiator as component (b), or a mixture of a thermosetting composition and a photocurable composition. The second curable composition constituting the second adhesive layer 3 is an uncured cured composition that can flow during circuit connection, for example, an uncured cured composition.

[0095] [(a) Component: Polymer compound]

[0096] Component (a) is, for example, a compound that polymerizes by free radicals, cations, or anions generated by irradiation or heating of a polymerization initiator (photopolymerization initiator or thermal polymerization initiator) under light (e.g., ultraviolet light). As component (a), the compound exemplified as component (A) can be used. Considering the ease of connection at low temperatures and short times, the ease of obtaining the desired DSC heat release, and the further improvement in the reduction of connection resistance and the superior connection reliability, component (a) is preferably a free radical polymerizable compound having free radical polymerizable groups that react via free radicals. Examples of preferred free radical polymerizable compounds in component (a) and combinations of preferred free radical polymerizable compounds are the same as those in component (A). When component (a) is a free radical polymerizable compound and component (B) in the first adhesive layer is a photofree radical polymerization initiator, by housing the adhesive film in the housing member described later, there is a significant tendency to suppress the curing of the second curable composition during storage or transport of the adhesive film.

[0097] (a) can be any of monomers, oligomers, or polymers. As (a), a single compound may be used alone, or multiple compounds may be used in combination. (a) may be the same as or different from (A).

[0098] From the viewpoint of easily obtaining the crosslinking density required to reduce connection resistance and improve connection reliability, based on the total mass of the second curing composition, the content of component (a) can be greater than or equal to 10% by mass, greater than or equal to 20% by mass, or greater than or equal to 30% by mass. From the viewpoint of suppressing curing shrinkage during polymerization and obtaining good reliability, based on the total mass of the second curing composition, the content of component (a) can be less than or equal to 90% by mass, less than or equal to 80% by mass, or less than or equal to 70% by mass.

[0099] [(b) Component: Polymerization initiator]

[0100] As component (b), the same polymerization initiator exemplified as component (B) can be used. Component (b) is preferably a free radical polymerization initiator. Examples of preferred free radical polymerization initiators in component (b) are the same as those in component (B). As component (b), a single compound can be used alone, or multiple compounds can be used in combination.

[0101] From the perspective of easier connection at low temperatures and shorter time, and from the perspective of superior connection reliability, based on the total mass of the second curing composition, the content of component (b) can be greater than or equal to 0.1% by mass, greater than or equal to 0.5% by mass, or greater than or equal to 1% by mass. From the perspective of pot life, based on the total mass of the second curing composition, the content of component (b) can be less than or equal to 30% by mass, less than or equal to 20% by mass, or less than or equal to 10% by mass.

[0102] [Other ingredients]

[0103] The second curable composition may further contain other components besides components (a) and (b). Examples of other components include, for instance, thermoplastic resins, coupling agents, fillers, softeners, accelerators, degradation inhibitors, colorants, flame retardants, thixotropic agents, etc. Details of these other components are the same as those of the other components in the first adhesive layer 2.

[0104] The second curable composition may also contain a thermosetting resin in place of components (a) and (b), or may contain a thermosetting resin in addition to components (a) and (b). When the second curable composition contains a thermosetting resin, it may also contain a curing agent for curing the thermosetting resin. The same thermosetting resin and curing agent as those exemplified as other components in the first curable composition may be used. When a thermosetting resin is used in place of components (a) and (b), for example, based on the total mass of the second curable composition, the content of the thermosetting resin in the second curable composition may be greater than or equal to 20% by mass and may be less than or equal to 80% by mass. When a thermosetting resin is used in addition to components (a) and (b), for example, based on the total mass of the second curable composition, the content of the thermosetting resin in the second curable composition may be greater than or equal to 20% by mass and may be less than or equal to 80% by mass. The content of the curing agent can be the same as the range of the curing agent content recorded in the first curing composition.

[0105] Regarding the content of conductive particles 4 in the second adhesive layer 3, for example, based on the total mass of the second adhesive layer, it can be less than or equal to 1% by mass, or it can be 0% by mass. The second adhesive layer 3 preferably does not contain conductive particles 4.

[0106] From the perspective of easily obtaining the cohesive strength required for good reliability after curing and easily improving the reliability of the connection, the DSC heat release Cy of the second adhesive layer 3 can be greater than or equal to 10 J / g, greater than or equal to 30 J / g, or greater than or equal to 50 J / g. From the perspective of suppressing curing shrinkage during polymerization and obtaining good reliability, the DSC heat release Cy can be less than or equal to 300 J / g, less than or equal to 200 J / g, or less than or equal to 150 J / g. The DSC heat release Cy can be adjusted by changing the composition of the second curable composition, etc.

[0107] The thickness d2 of the second adhesive layer 3 can be appropriately set according to the electrode height, etc., of the circuit components to be bonded. From the viewpoint of fully filling the gap between electrodes to seal them and obtain better reliability, the thickness d2 of the second adhesive layer 3 can be greater than or equal to 5 μm and less than or equal to 200 μm. It should be noted that when a portion of the conductive particle 4 protrudes from the surface of the first adhesive layer 2 (e.g., protruding towards the second adhesive layer 3), the distance from the surface 3a of the second adhesive layer 3 opposite to the side of the first adhesive layer 2 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, is... Figure 1The distance d2 represents the thickness of the second adhesive layer 3.

[0108] From the viewpoint of being able to fully fill the gap between electrodes to seal the electrodes and obtain better reliability, the ratio of the thickness d1 of the first adhesive layer 2 to the thickness d2 of the second adhesive layer 3 (thickness d1 of the first adhesive layer 2 / thickness d2 of the second adhesive layer 3) can be greater than or equal to 1 and can be less than or equal to 1000.

[0109] The thickness of adhesive film 1 (the total thickness of all layers constituting adhesive film 1). Figure 1 In the above, the thickness d1 of the first adhesive layer 2 and the thickness d2 of the second adhesive layer 3 are combined. For example, it can be greater than or equal to 5 μm and less than or equal to 200 μm.

[0110] The adhesive film for circuit connection in this embodiment has been described above, but the present invention is not limited to the above embodiment.

[0111] For example, the adhesive film for circuit connection can be composed of two layers: a first adhesive layer and a second adhesive layer, or it can be composed of three or more layers including a layer other than the first and second adhesive layers (e.g., a third adhesive layer). The third adhesive layer can be a layer having the same composition as described above for the first or second adhesive layer, or a layer having the same physical properties (e.g., DSC heat release) as described above for the first or second adhesive layer, or a layer having the same thickness as described above for the first or second adhesive layer. The adhesive film for circuit connection may, for example, further include a third adhesive layer on the side of the first adhesive layer opposite to the second adhesive layer. That is, the adhesive film for circuit connection is, for example, formed by sequentially stacking the second adhesive layer, the first adhesive layer, and the third adhesive layer. In this case, the third adhesive layer is, for example, composed of a second curable composition (e.g., a thermosetting composition) similar to the second adhesive layer.

[0112] Furthermore, the adhesive film for circuit connection in the above embodiment is an anisotropic conductive adhesive film with anisotropic conductivity, but the adhesive film for circuit connection may also be a conductive adhesive film without anisotropic conductivity.

[0113] <Method for manufacturing adhesive film for circuit connection>

[0114] The method for manufacturing the adhesive film 1 for circuit connection in this embodiment includes, for example, a preparation step (first preparation step) for preparing the first adhesive layer 2; and a lamination step for laminating the second adhesive layer 3 onto the first adhesive layer 2. The method for manufacturing the adhesive film 1 for circuit connection may further include a preparation step (second preparation step) for preparing the second adhesive layer 3.

[0115] In the first preparation step, for example, a first adhesive layer 2 is formed on a substrate to obtain a first adhesive film, thereby preparing the first adhesive layer 2. Specifically, components (A), (B), and (C), as well as other components added as needed, are first added to an organic solvent, and dissolved or dispersed by stirring, mixing, kneading, etc., to prepare a varnish composition. Then, the varnish composition is applied to a substrate that has undergone a demolding treatment using a doctor blade coater, roller coater, applicator, etc., and the organic solvent is evaporated by heating, thereby forming a layer composed of a first curable composition on the substrate. Next, the first curable composition is cured by irradiating the layer composed of the first curable composition with light or heating, forming the first adhesive layer 2 on the substrate (curing step). Thus, the first adhesive film is obtained.

[0116] As the organic solvent used in the preparation of the varnish composition, it is preferable to have the property of uniformly dissolving or dispersing the components, such as toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, etc. These organic solvents can be used alone or in combination of two or more. The stirring, mixing and kneading during the preparation of the varnish composition can be carried out, for example, using a mixer, sand mixer, three-roll mill, ball mill, bead mill or homogenizer.

[0117] As a substrate, there are no particular limitations as long as the first curable composition is cured by light and has heat resistance that can withstand the heating conditions that cause the organic solvent to evaporate, and there are no particular limitations as long as the first curable composition is cured by heating and has heat resistance that can withstand both the heating conditions that cause the organic solvent to evaporate and the heating conditions that cause the first curable composition to cure. As a substrate, for example, substrates (e.g., films) including stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefins, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber systems, liquid crystal polymers, etc., can be used.

[0118] The heating conditions for evaporating the organic solvent from the varnish composition coated on the substrate are preferably set to conditions that allow the organic solvent to evaporate sufficiently. For example, the heating conditions may be greater than or equal to 40°C and less than or equal to 120°C, and greater than or equal to 0.1 minutes and less than or equal to 10 minutes.

[0119] For light irradiation during the curing process, it is preferable to use irradiation light with wavelengths in the range of 150~750nm (e.g., ultraviolet light). 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, etc. The light irradiation dose can be adjusted so that the ratio of DSC heat release (Cx / Cy) is less than or equal to 0.4. For example, based on the cumulative light intensity of light with a wavelength of 365nm, the light irradiation dose can be greater than or equal to 100mJ / cm². 2 It can be greater than or equal to 200 mJ / cm 2 It can also be greater than or equal to 300 mJ / cm 2 For example, based on the cumulative light intensity of light with a wavelength of 365 nm, the light irradiation can be less than or equal to 10000 mJ / cm². 2 It can be less than or equal to 5000 mJ / cm 2 It can also be less than or equal to 3000mJ / cm 2 The greater the amount of light irradiation (cumulative light intensity), the smaller the heat release Cx of the DSC, and the smaller the ratio of heat release of the DSC (Cx / Cy).

[0120] The heating conditions in the curing process can be adjusted so that the ratio of DSC heat release (Cx / Cy) is less than or equal to 0.4. For example, heating conditions can be greater than or equal to 30°C and less than or equal to 300°C, greater than or equal to 0.1 minutes and less than or equal to 5000 minutes, or greater than or equal to 50°C and less than or equal to 150°C, greater than or equal to 0.1 minutes and less than or equal to 3000 minutes. Higher heating temperatures tend to result in lower DSC heat release Cx and a lower DSC heat release ratio (Cx / Cy). Similarly, longer heating times tend to result in lower DSC heat release Cx and a lower DSC heat release ratio (Cx / Cy).

[0121] In the second preparation step, except that components (a) and (b) and other components added as needed are used and a curing step is not performed (no light irradiation and heating is performed), a second adhesive layer 3 is formed on the substrate in the same manner as in the first preparation step to obtain a second adhesive film, thereby preparing the second adhesive layer 3.

[0122] In the lamination process, the second adhesive layer 3 can be laminated on the first adhesive layer 2 by bonding the first adhesive film and the second adhesive film together, or the second adhesive layer 3 can be laminated on the first adhesive layer 2 by applying a varnish composition using components (a) and (b) and other components added as needed onto the first adhesive layer 2 and allowing the organic solvent to evaporate.

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

[0124] <Circuit connection structure and its manufacturing method>

[0125] The following describes a circuit connection structure and its manufacturing method that uses the above-mentioned circuit connection adhesive film 1 as the circuit connection material.

[0126] Figure 2 This is a schematic cross-sectional view illustrating a circuit connection structure in one embodiment. For example... Figure 2 As shown, the circuit connection structure 10 includes: a first circuit member 13 having a first circuit substrate 11 and a first electrode 12 formed on the main surface 11a of the first circuit substrate 11; a second circuit member 16 having a second circuit substrate 14 and a second electrode 15 formed on the main surface 14a of the second circuit substrate 14; and a circuit connection portion 17 disposed between the first circuit member 13 and the second circuit member 16 and electrically connecting the first electrode 12 and the second electrode 15 to each other.

[0127] The first circuit component 13 and the second circuit component 16 may be the same as or different from each other. The first circuit component 13 and the second circuit component 16 may be glass or plastic substrates with electrodes formed on them, printed wiring boards, ceramic wiring boards, flexible wiring boards, semiconductor silicon IC chips, etc. The first circuit substrate 11 and the second circuit substrate 14 may be formed of inorganic materials such as semiconductors, glass, and ceramics, organic materials such as polyimide and polycarbonate, glass / epoxy composites, etc. The first electrode 12 and the second electrode 15 may be formed of gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), etc. The first electrode 12 and the second electrode 15 may be circuit electrodes or bump electrodes. At least one of the first electrode 12 and the second electrode 15 may be a bump electrode. Figure 2 In the middle, the second electrode 15 is a bump electrode.

[0128] The circuit connection portion 17 is formed from the adhesive film 1 described above. The circuit connection portion 17 is, for example, a cured product of the adhesive film 1. The circuit connection portion 17 may have, for example, a first region 18 located on the side of the first circuit member 13 in a direction (hereinafter "opposite direction") where the first circuit member 13 and the second circuit member 16 are opposite to each other, and is composed of a cured product of the first curable composition containing components (A), (B), etc., other than the conductive particles 4; a second region 19 located on the side of the second circuit member 16 in the opposite direction, and is composed of a cured product of the second curable composition containing components (a), (b), etc.; and conductive particles 4, which are at least located between the first electrode 12 and the second electrode 15, electrically connecting the first electrode 12 and the second electrode 15 to each other. The circuit connection portion may also not have two regions as in the case of the first region 18 and the second region 19; for example, it may be composed of a cured product of the first curable composition containing components other than the conductive particles 4 mixed with a cured product of the second curable composition.

[0129] Figure 3 This is a schematic cross-sectional view illustrating the manufacturing method of the circuit connection structure 10. (See attached image.) Figure 3 As shown, the manufacturing method of the circuit connection structure 10 includes, for example, the following steps: placing the adhesive film 1 between a first circuit member 13 having a first electrode 12 and a second circuit member 16 having a second electrode 15, and thermally pressing the first circuit member 13 and the second circuit member 16 together, thereby electrically connecting the first electrode 12 and the second electrode 15 to each other.

[0130] Specifically, such as Figure 3 As shown in (a), firstly, a first circuit member 13 having a first circuit substrate 11 and a first electrode 12 formed on the main surface 11a of the first circuit substrate 11, and a second circuit member 16 having a second circuit substrate 14 and a second electrode 15 formed on the main surface 14a of the second circuit substrate 14 are prepared.

[0131] Next, the first circuit component 13 and the second circuit component 16 are arranged with the first electrode 12 and the second electrode 15 facing each other, and an adhesive film 1 is disposed between the first circuit component 13 and the second circuit component 16. For example, as Figure 3As shown in (a), an adhesive film 1 is laminated onto the first circuit member 13 with the first adhesive layer 2 side facing the mounting surface 11a of the first circuit member 13. Next, a second circuit member 16 is disposed on the first circuit member 13 on which the adhesive film 1 is laminated, with the first electrode 12 on the first circuit substrate 11 and the second electrode 15 on the second circuit substrate 14 facing each other. Alternatively, for example, the adhesive film 1 can be laminated onto the second circuit member 16 with the first adhesive layer 2 side facing the mounting surface 14a of the second circuit member 16. In this case, the first circuit member 13 is disposed on the second circuit member 16 on which the adhesive film 1 is laminated, with the first electrode 12 on the first circuit substrate 11 and the second electrode 15 on the second circuit substrate 14 facing each other.

[0132] Then, as Figure 3 As shown in (b), while heating the first circuit component 13, the adhesive film 1, and the second circuit component 16, pressure is applied to the first circuit component 13 and the second circuit component 16 in the thickness direction, thereby thermally bonding the first circuit component 13 and the second circuit component 16 together. At this time, as... Figure 3 As indicated by the arrow in (b), the second adhesive layer 3 flows to fill the gaps between the second electrodes 15, 15, and is simultaneously cured by the aforementioned heating. Thus, the first electrode 12 and the second electrode 15 are electrically connected to each other via the conductive particles 4, and the first circuit component 13 and the second circuit component 16 are bonded together, obtaining... Figure 2 The circuit connection structure 10 is shown. It should be noted that when the second curable composition includes a photocurable composition, the first circuit member 13 and the second circuit member 16 can be joined by applying pressure and light irradiation, or by applying pressure, heating and light irradiation, instead of using heated hot pressing.

[0133] <Adhesive Film Storage Component>

[0134] Figure 4 This is a perspective view illustrating an adhesive film receiving assembly according to one embodiment. Figure 4 As shown, the adhesive film storage assembly 20 includes: an adhesive film 1 for circuit connection, a spool 21 formed by winding the adhesive film 1, and a storage member 22 for storing the adhesive film 1 and the spool 21.

[0135] like Figure 4 As shown, the adhesive film 1 is, for example, in the form of a strip. The strip-shaped adhesive film 1 is manufactured, for example, by cutting a sheet-like template into strips of a suitable width. A substrate may also be provided on one side of the adhesive film 1. As the substrate, a substrate such as the aforementioned PET film can be used.

[0136] The spool 21 includes a first side plate 24 having a core 23 wound with adhesive film 1, and a second side plate 25 arranged opposite to the first side plate 24 in a manner that sandwiches the core 23.

[0137] The first side plate 24 is, for example, a circular plate made of plastic, with a circular opening in the central part of the first side plate 24.

[0138] The core 23 of the first side plate 24 is the portion for winding the adhesive film 1. The core 23 is made of, for example, plastic and is formed into a ring with the same thickness as the width of the adhesive film 1. The core 23 is fixed to the inner surface of the first side plate 24 in such a way that it surrounds the opening of the first side plate 24. In addition, a shaft hole 26 is provided in the center of the reel 21, which serves as a rotating shaft for inserting a winding device or an output device (not shown). When the rotating shaft is driven while the rotating shaft of the winding device or the output device is inserted into the shaft hole 26, the reel 21 will rotate without spinning freely. A desiccant container may also be inserted into the shaft hole 26.

[0139] The second side plate 25 is similar to the first side plate 24, for example, a circular plate made of plastic, and the central part of the second side plate 25 has an opening with the same diameter as the opening of the first side plate 24.

[0140] The storage member 22 is formed, for example, in the shape of a bag, and houses the adhesive film 1 and the roll 21. The storage member 22 has an insertion port 27 for storing (inserting) the adhesive film 1 and the roll 21 into the interior of the storage member 22.

[0141] The storage component 22 has a viewing section 28 that allows the interior of the storage component 22 to be viewed from the outside. Figure 4 The storage component 22 shown is configured such that the entire storage component 22 becomes the viewing part 28.

[0142] The viewing section 28 is transmissive to visible light. For example, when measuring the light transmittance of the viewing section 28 in the wavelength range of 450-750 nm, there exists at least one region in the wavelength range of 450-750 nm where the average light transmittance is greater than or equal to 30% and the wavelength width is 50 nm. The light transmittance of the viewing section 28 can be obtained by preparing a sample by cutting the viewing section 28 into a predetermined size and measuring the light transmittance of the sample using a UV-Vis spectrophotometer. Since the storage member 22 has such a viewing section 28, various information such as the product name, batch number, and expiration date of the scroll 21 attached inside the storage member 22 can be identified even from the outside of the storage member 22. As a result, it is expected to prevent the mixing of incorrect products and improve the efficiency of sorting operations.

[0143] The transmittance of the viewing portion 28 to light with a wavelength of 365 nm is less than or equal to 10%. Since the transmittance of the viewing portion 28 to light with a wavelength of 365 nm is less than or equal to 10%, the curing of the second curable composition caused by light incident from the outside of the housing member 22 and the photopolymerization initiator remaining in the first adhesive layer 2 when using a photopolymerization initiator as component (B) can be suppressed. As a result, the following undesirable conditions can be suppressed: easy peeling between circuit components and circuit connections in high temperature and high humidity environments; reduced effect of improved capture rate; and reduced flowability leading to a reduced effect of reduced adhesion resistance of the adhesive film. From the viewpoint of further suppressing the generation of active species (e.g., free radicals) from the photopolymerization initiator, the transmittance of the viewing portion 28 to light with a wavelength of 365 nm is preferably less than or equal to 10%, more preferably less than or equal to 5%, further preferably less than or equal to 1%, and particularly preferably less than or equal to 0.1%.

[0144] From the same perspective, the maximum transmittance of the viewing section 28 for light in the wavelength region from which free radicals, cations, or anions can be generated from the aforementioned photopolymerization initiator (component (B)) is preferably less than or equal to 10%, more preferably less than or equal to 5%, further preferably less than or equal to 1%, and particularly preferably less than or equal to 0.1%. Specifically, the maximum transmittance of the viewing section 28 for light with wavelengths of 254 to 405 nm is preferably less than or equal to 10%, more preferably less than or equal to 5%, further preferably less than or equal to 1%, and particularly preferably less than or equal to 0.1%.

[0145] The viewing section 28 (receiving member 22) is formed, for example, from a sheet with a thickness of 10 to 5000 μm. This sheet is made of a material whose transmittance of light with a wavelength of 365 nm is less than or equal to 10%. Such a material may contain one component or multiple components. Examples of such materials include low-density polyethylene, linear low-density polyethylene, polycarbonate, polyester, acrylic resin, polyamide, and glass. These materials may also contain ultraviolet absorbers. The viewing section 28 may also have a laminated structure formed by stacking multiple layers with different light transmittances. In this case, each layer constituting the viewing section 28 may contain the aforementioned materials.

[0146] To prevent air from entering during storage, the insertion port 27 can be sealed, for example, by using a sealing machine. In this case, it is preferable to remove the air from the storage member 22 before sealing the insertion port 27. It is expected that the moisture inside the storage member 22 will decrease from the initial stage of storage, and air will be prevented from entering from the outside. In addition, by sealing the inner surface of the storage member 22 with the roller 21, it is possible to prevent the inner surface of the storage member 22 from rubbing against the surface of the roller 21 due to vibration during handling, thus preventing the generation of foreign objects, and it is also possible to prevent scratches on the outer surfaces of the side plates 24 and 25 of the roller 21.

[0147] In the above embodiments, the storage member is configured such that the entire storage member forms the viewing portion. However, in another embodiment, the storage member may also have a viewing portion on a portion thereof. For example, the storage member may have a rectangular viewing portion approximately at the center of its side. In this case, the portion of the storage member other than the viewing portion may be black to prevent it from transmitting, for example, ultraviolet and visible light.

[0148] Furthermore, in the above embodiment, the storage component is bag-shaped, but it can also be, for example, box-shaped. The storage component preferably has slits for opening. In this case, opening during use becomes easier.

[0149] Example

[0150] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the embodiments.

[0151] <Synthesis of Polyurethane Acrylate (UA1)>

[0152] In a reaction vessel equipped with a stirrer, thermometer, reflux cooling tube with calcium chloride drying tube, and nitrogen inlet tube, 2500 parts by mass (2.50 mol) of poly(1,6-hexanediol carbonate) (trade name: Duranol T5652, manufactured by Asahi Kasei Chemicals Co., Ltd., number average molecular weight 1000) and 666 parts by mass (3.00 mol) of isophorone diisocyanate (manufactured by Sigma-Aldrich) were uniformly added dropwise over 3 hours. Next, nitrogen was thoroughly introduced into the reaction vessel, and the reaction was carried out at 70-75°C. Next, 0.53 parts by mass (4.3 mmol) of hydroquinone monomethyl ether (Sigma-Aldrich) and 5.53 parts by mass (8.8 mmol) of dibutyltin dilaurate (Sigma-Aldrich) were added to the reaction vessel, followed by 238 parts by mass (2.05 mol) of 2-hydroxyethyl acrylate (Sigma-Aldrich). The reaction was carried out at 70°C for 6 hours in air. This yielded polyurethane acrylate (UA1). The weight-average molecular weight of polyurethane acrylate (UA1) was 15,000. It should be noted that the weight-average molecular weight was determined by gel permeation chromatography (GPC) under the following conditions using a standard curve based on standard polystyrene.

[0153] (Measurement conditions)

[0154] Device: GPC-8020 manufactured by Tosoh Corporation

[0155] Detector: Tosoh Corporation RI-8020

[0156] Column: Gelpack GLA160S+GLA150S manufactured by Hitachi Chemical Co., Ltd.

[0157] Sample concentration: 120 mg / 3 mL

[0158] Solvent: Tetrahydrofuran

[0159] Injection volume: 60μL

[0160] Pressure: 2.94 × 10 6 Pa(30kgf / cm 2 )

[0161] Flow rate: 1.00 mL / min

[0162] <The Production of Conductive Particles>

[0163] A nickel-containing layer is formed on the surface of polystyrene particles with a thickness of 0.2 μm. This yields conductive particles with an average particle size of 4 μm, a maximum particle size of 4.5 μm, and a specific gravity of 2.5.

[0164] <Preparation of the varnish (varnish composition) of the first curing composition>

[0165] Mix the components shown below in the proportions (parts by mass) shown in Table 1 to prepare varnishes of the first curing compositions 1 to 4. It should be noted that the content (volume %) of conductive particles and the content (volume %) of filler material listed in Table 1 are based on the total volume of the first curing compositions.

[0166] (polymeric compounds)

[0167] A1: Dicyclopentadiene diacrylate (trade name: DCP-A, manufactured by Toa Synthetic Co., Ltd.)

[0168] A2: Polyurethane acrylate (UA1) synthesized as described above.

[0169] A3: 2-Methacryloxyethyl phosphate (trade name: Light Ester P-2M, manufactured by Kyoei Chemical Co., Ltd.)

[0170] (Polymerization initiator)

[0171] B1: 1,2-Octanedione, 1-[4-(phenylthio)phenyl-,2-(O-benzoyl oxime)] (Trade name: Irgacure (registered trademark) OXE01, manufactured by BASF)

[0172] B2: Benzoyl peroxide (trade name: NYPER BMT-K40, manufactured by Nippon Yu Co., Ltd.)

[0173] (Conductive particles)

[0174] C1: Conductive particles prepared as described above

[0175] (Thermoplastic resin)

[0176] D1: Bisphenol A type phenoxy resin (trade name: PKHC, manufactured by Union Carbide Corporation)

[0177] (Coupled agent)

[0178] E1: 3-Methacryloxypropyltrimethoxysilane (trade name: KBM 503, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0179] (filler material)

[0180] F1: Silica microparticles (trade name: R104, manufactured by AEROSIL Co., Ltd., Japan, average particle size (primary particle size): 12nm, specific gravity: 2)

[0181] (solvent)

[0182] G1: Methyl ethyl ketone

[0183] [Table 1]

[0184]

[0185] <Preparation of the varnish (varnish composition) of the second curing composition>

[0186] The second curable composition 1 is prepared by mixing the same polymerizable compounds a1-a3, polymerization initiator b1, thermoplastic resin d1, coupling agent e1, filler f1, and solvent g1 as those in the first curable composition. These components are mixed in the proportions (parts by mass) shown in Table 2. It should be noted that the filler content (volume %) listed in Table 2 is based on the total volume of the second curable composition.

[0187] [Table 2]

[0188]

[0189] (Example 1)

[0190] [Preparation of the first adhesive film]

[0191] The varnish of the first curing composition 1 was applied onto a 50 μm thick PET film using a coating apparatus. Next, hot air drying at 70°C for 3 minutes was performed to form a 2 μm thick layer (after drying) containing the first curing composition 1 on the PET film. Then, the layer containing the first curing composition 1 was subjected to a metal halide lamp with a cumulative light intensity of 2000 mJ / cm². 2 The polymerizable compound is polymerized by irradiation with light. This causes the first curable composition 1 to cure, forming a first adhesive layer. Through the above operations, a first adhesive film having a first adhesive layer with a thickness of 2 μm on a PET film is obtained. The conductive particle density at this time is approximately 7000 pcs / mm². 2 It should be noted that the thickness of the first adhesive layer was measured using an Olympus OLS4100 laser microscope manufactured by Olympus Corporation.

[0192] [Preparation of the second adhesive film]

[0193] The varnish of the second curing composition 1 is applied to a PET film with a thickness of 50 μm using a coating apparatus. Next, hot air drying at 70°C for 3 minutes is performed to form a second adhesive layer (containing the second curing composition 1) with a thickness of 10 μm on the PET film. Through the above operations, a second adhesive film having a second adhesive layer on the PET film is obtained.

[0194] [Preparation of adhesive film for circuit connections]

[0195] The first adhesive film and the second adhesive film, together with a PET film as a substrate, are heated at 40°C and laminated using a roller laminator. This produces a substrate-based adhesive film for circuit connection, comprising two layers of adhesive film consisting of a first adhesive layer and a second adhesive layer laminated together.

[0196] [Determination of DSC heat release]

[0197] A portion of the first and second adhesive layers was excised from the obtained adhesive film for circuit connection, yielding 5 mg of evaluation samples of the first and second adhesive layers respectively. Next, for both evaluation samples, differential scanning calorimetry (DSC) was performed using a DSC device (product name DSC7, manufactured by PERKIN ELMER) under a nitrogen flow, at a temperature range of 30°C to 250°C and a heating rate of 10°C / min, to calculate the DSC heat release.

[0198] The DSC heat release (DSC heat release Cx) of the first adhesive layer is 36 J / g. The DSC heat release (DSC heat release Cy) of the second adhesive layer is 120 J / g. Based on these results, the DSC heat release ratio (Cx / Cy) is 0.30.

[0199] [Construction of circuit connection structures]

[0200] Using a heat-pressing device (heating method: contact heat type, manufactured by Taiyo Kaisha Co., Ltd.), heat and pressurize the glass substrate 1 (manufactured by Geomatec Co., Ltd.) at 170°C, 6MPa, and 4 seconds for a period of 4 seconds, and connect the glass substrate 1 (connecting structure 1) and 2 (connecting structure 2) with a circuit connection portion formed by the adhesive film for circuit connection. The circuit connection structure 1 (connecting structure 1) and the circuit connection structure 2 (connecting structure 2) are made with a circuit connection portion formed by the adhesive film for circuit connection. The circuit connection structure 1 has a 25μm COF (manufactured by FLEXSEED Co., Ltd.) and a glass substrate 2 (manufactured by Geomatec Co., Ltd.) with a COF (2000Å), a Cr (500Å), and an indium zinc oxide (IZO) (1000Å) film stacked sequentially from the surface of the glass substrate. The connection structure 2 has a 1mm width and a COF (25μm) with a COF (2000Å ... It should be noted that, during connection, the adhesive film for circuit connection is disposed on the glass substrate with the first adhesive layer side facing the glass substrate.

[0201] [Evaluation of capture rate]

[0202] The phase difference observation of the connection appearance of the obtained circuit connection structure 1 was performed using an optical microscope to evaluate the capture rate. Specifically, the number of conductive particles on the thin film electrode containing AlNd, Cr and IZO was measured from the glass substrate side with the thin film electrode, and the capture rate of conductive particles was calculated based on the following formula.

[0203] Capture rate (%) = (Number of conductive particles on the thin film electrode / (1 mm)) 2 / area of ​​thin film electrode / per 1mm 2 (Number of conductive particles in the adhesive film for circuit connection) × 100

[0204] It should be noted that in the above measurements, the average value of the number of conductive particles measured at 100 locations on the thin-film electrode was taken as the total number of conductive particles on the thin-film electrode. The results are shown in Table 3.

[0205] [Evaluation of connection resistors]

[0206] For the obtained circuit connection structure 1, the connection resistance between the opposing electrodes after connection was measured using a multimeter. The connection resistance value was calculated as the average resistance at 16 points between the opposing electrodes. The results are shown in Table 3.

[0207] [Stripping Evaluation]

[0208] The appearance of the obtained circuit connection structure 2 after the high temperature and high humidity test was observed using an optical microscope to evaluate the peeling. Specifically, the area of ​​peeling that occurred between the glass substrate with the thin-film electrode and the circuit connection was measured from the glass substrate side (peeling area). The high temperature and high humidity test was conducted by placing the structure in a constant temperature and humidity bath at 85°C and 85%RH for 200 hours. The results are shown in Table 3.

[0209] [Evaluation of adhesion resistance]

[0210] The prepared adhesive film for circuit connections with a substrate is cut into 0.6mm pieces to obtain a strip-shaped adhesive film with a substrate. A spool for adhesive tape is prepared, comprising a core, annular side plates, and a core with a width of 0.7mm, an inner diameter of 40mm, and an outer diameter of 65mm. Two annular side plates (two in total) are provided at each end of the core, each with a thickness of 2mm, an inner diameter of 40mm, and an outer diameter of 125mm, and are made of plastic. The strip-shaped adhesive film with the substrate is wound onto the spool with the adhesive film side facing inwards. By repeating the above operations, an adhesive spool is obtained, consisting of an adhesive film with a length of 50m and a width of 0.6mm wound onto the core.

[0211] The obtained adhesive rolls were placed in a constant temperature bath at 30°C for 24 hours, after which it was confirmed that the adhesive film could be pulled out without any problems. Cases where the film was pulled out without problems were rated A, and cases where problems such as adhesion to the substrate occurred during pulling out were rated B. The results are shown in Table 3.

[0212] (Example 2)

[0213] First curing composition 2 was used instead of first curing composition 1, and the first adhesive film was cured by heating the layer containing first curing composition 2 at 100°C for 180 minutes instead of light irradiation. Otherwise, the same procedure as in Example 1 was followed to prepare the adhesive film for circuit connection and the circuit connection structure. The DSC heat release, capture rate evaluation, connection resistance evaluation, peel evaluation, and adhesion resistance evaluation were performed in the same manner as in Example 1. The results are shown in Table 3.

[0214] (Example 3)

[0215] In the production of the first adhesive film, a first curing composition 3 is used instead of the first curing composition 1. The layer containing the first curing composition 3 is cured by heating it at 100°C for 180 minutes instead of light irradiation. A varnish containing the first curing composition 3 is applied to a thickness of 3 μm, and the conductive particle density in the first adhesive film is 3000 pcs / mm². 2Otherwise, the same procedures were followed as in Example 1 to fabricate the adhesive film for circuit connection and the circuit connection structure, and the same procedures were followed as in Example 1 to measure the DSC heat release, evaluate the capture rate, evaluate the connection resistance, evaluate the peeling, and evaluate the adhesion resistance. The results are shown in Table 3.

[0216] (Example 4)

[0217] In the production of the first adhesive film, a first curing composition 4 is used instead of the first curing composition 1. The layer containing the first curing composition 4 is cured by heating it at 100°C for 180 minutes instead of light irradiation. A varnish containing the first curing composition 4 is applied to a thickness of 1 μm, and the conductive particle density in the first adhesive film is 10000 pcs / mm². 2 Otherwise, the same procedures were followed as in Example 1 to fabricate the adhesive film for circuit connection and the circuit connection structure, and the same procedures were followed as in Example 1 to measure the DSC heat release, evaluate the capture rate, evaluate the connection resistance, evaluate the peeling, and evaluate the adhesion resistance. The results are shown in Table 3.

[0218] (Comparative Example 1)

[0219] During the fabrication of the first adhesive film, no light irradiation was performed (the layer containing the first curable composition 1 was not cured). Otherwise, the same procedure as in Example 1 was followed to fabricate the adhesive film for circuit connection and the circuit connection structure. The DSC heat release, capture rate, connection resistance, peel strength, and adhesion resistance were measured, and the same procedure as in Example 1 was performed. The results are shown in Table 4.

[0220] (Comparative Example 2)

[0221] When preparing the first adhesive film, the cumulative light intensity was 50 mJ / cm. 2 The light was irradiated in the same manner as in Example 1. Otherwise, the same procedure was followed to fabricate the adhesive film and circuit connection structure for circuit connection, and the DSC heat release, capture rate, connection resistance, peeling, and adhesion resistance were measured, all in accordance with Example 1. The results are shown in Table 4.

[0222] (Comparative Example 3)

[0223] First curing composition 2 was used instead of first curing composition 1, and the first adhesive film was cured by heating the layer containing first curing composition 2 at 60°C for 30 minutes instead of light irradiation. Otherwise, the same procedure as in Example 1 was followed to fabricate the adhesive film for circuit connection and the circuit connection structure, and the same procedure as in Example 1 was followed to measure the DSC heat release, evaluate the capture rate, evaluate the connection resistance, evaluate the peel strength, and evaluate the adhesion resistance. The results are shown in Table 4.

[0224] (Comparative Example 4)

[0225] The first curing composition 3 is used instead of the first curing composition 1. No light irradiation is applied during the fabrication of the first adhesive film. The varnish of the first curing composition 3 is applied to a thickness of 3 μm, and the conductive particle density in the first adhesive film is 3000 pcs / mm². 2 Otherwise, the same procedures were followed as in Example 1 to fabricate the adhesive film for circuit connection and the circuit connection structure, and the same procedures were followed as in Example 1 to measure the DSC heat release, evaluate the capture rate, evaluate the connection resistance, evaluate the peeling, and evaluate the adhesion resistance. The results are shown in Table 4.

[0226] (Comparative Example 5)

[0227] The first curing composition 4 is used instead of the first curing composition 1. No light irradiation is applied during the fabrication of the first adhesive film. The varnish of the first curing composition 4 is applied to a thickness of 1 μm, and the conductive particle density in the first adhesive film is 10000 pcs / mm². 2 Otherwise, the same procedures were followed as in Example 1 to fabricate the adhesive film for circuit connection and the circuit connection structure, and the same procedures were followed as in Example 1 to measure the DSC heat release, evaluate the capture rate, evaluate the connection resistance, evaluate the peeling, and evaluate the adhesion resistance. The results are shown in Table 4.

[0228] (Comparative Example 6)

[0229] In place of the first curing composition 1, the first adhesive film was prepared by heating the layer containing the first curing composition 2 at 100°C for 180 minutes instead of light irradiation. Similarly, the second adhesive film was prepared by heating the layer containing the second curing composition 1 at 100°C for 180 minutes. Otherwise, the same procedure as in Example 1 was followed to prepare the adhesive film and the circuit connection structure. The DSC heat release, capture rate, connection resistance, peel strength, and adhesion resistance were measured, as well as in Example 1. The results are shown in Table 4.

[0230] [Table 3]

[0231]

[0232] [Table 4]

[0233]

[0234] Symbol Explanation

[0235] 1: Adhesive film for circuit connection; 2: First adhesive layer; 3: Second adhesive layer; 4: Conductive particles; 10: Circuit connection structure; 12: Circuit electrode (first electrode); 13: First circuit component; 15: Bump electrode (second electrode); 16: Second circuit component; 20: Adhesive film storage assembly; 22: Storage component; 28: Viewing section.

Claims

1. An adhesive film for circuit connection, comprising: a first adhesive layer containing conductive particles, and a second adhesive layer laminated on the first adhesive layer. The ratio of the DSC heat release of the first adhesive layer to the DSC heat release of the second adhesive layer is less than or equal to 0.

4. The first adhesive layer is composed of a cured product of a first curable composition, which contains a free radical polymerizable compound having free radical polymerizable groups and a thermal free radical polymerization initiator. The free radical polymerizable compound having free radical polymerizable groups is a (poly)urethane (meth)acrylate compound.

2. The adhesive film for circuit connection according to claim 1, wherein the second adhesive layer is composed of a second curable composition. The second curable composition contains a free radical polymerizable compound having free radical polymerizable groups.

3. The adhesive film for circuit connection according to claim 1 or 2, wherein the thickness of the first adhesive layer is 0.2 to 0.8 times the average particle size of the conductive particles.

4. The adhesive film for circuit connection according to claim 1, wherein the ratio of the DSC heat release of the first adhesive layer to the DSC heat release of the second adhesive layer is 0.05 to 0.

30.

5. The adhesive film for circuit connection according to claim 1, wherein the first curable composition contains a photoradical polymerization initiator having an oxime ester structure.

6. The adhesive film for circuit connection according to claim 2, wherein the free radical polymerizable compound having free radical polymerizable groups contained in the second curable composition comprises a (poly)urethane (meth)acrylate compound.

7. The adhesive film for circuit connection according to claim 2, wherein the first curable composition and the second curable composition comprise phenoxy resin as a thermoplastic resin.

8. A method for manufacturing an adhesive film for circuit connection, comprising: Preparation steps include preparing the first adhesive layer; and In the lamination process, a second adhesive layer composed of a second curable composition is laminated onto the first adhesive layer. The preparation process includes a curing process: the first curing composition is cured by irradiating it with light or heating it to obtain the first adhesive layer. In the curing process, the first curable composition is cured such that the ratio of the DSC heat release of the first adhesive layer to the DSC heat release of the second adhesive layer is less than or equal to 0.

4. The first curable composition contains a free radical polymerizable compound having free radical polymerizable groups and a thermal free radical polymerization initiator, wherein the free radical polymerizable compound having free radical polymerizable groups is a (poly)urethane (meth)acrylate compound.

9. The method for manufacturing an adhesive film for circuit connection according to claim 8, wherein the second curable composition contains a free radical polymerizable compound having free radical polymerizable groups.

10. The method for manufacturing an adhesive film for circuit connection according to claim 8 or 9, wherein the thickness of the first adhesive layer is 0.2 to 0.8 times the average particle size of the conductive particles.

11. The method for manufacturing an adhesive film for circuit connection according to claim 8, wherein the ratio of the DSC heat release of the first adhesive layer to the DSC heat release of the second adhesive layer is 0.05 to 0.

30.

12. The method for manufacturing an adhesive film for circuit connection according to claim 8, wherein the first curable composition contains a photoradical polymerization initiator having an oxime ester structure.

13. The method for manufacturing an adhesive film for circuit connection according to claim 9, wherein the free radical polymerizable compound having free radical polymerizable groups contained in the second curable composition comprises a (poly)urethane (meth)acrylate compound.

14. The method for manufacturing an adhesive film for circuit connection according to claim 8, wherein the first curable composition and the second curable composition comprise phenoxy resin as a thermoplastic resin.

15. A method for manufacturing a circuit connection structure, comprising the following steps: placing an adhesive film for circuit connection as described in any one of claims 1 to 7 between a first circuit member having a first electrode and a second circuit member having a second electrode, and thermally pressing the first circuit member and the second circuit member together, thereby electrically connecting the first electrode and the second electrode to each other.

16. An adhesive film storage assembly comprising: an adhesive film for circuit connection as described in any one of claims 1 to 7, and a storage member for storing the adhesive film. The storage component has a viewing section that allows the interior of the storage component to be viewed from the outside. The transmittance of the viewing element for light with a wavelength of 365nm is less than or equal to 10%.

Images