Photosensitive resin composition and conductive adhesive agent using same

Abstract

Provided is a photosensitive resin composition capable of reducing connection resistance even in a fine pattern. This photosensitive resin composition comprises: metal particles (A) containing a metal having a Young's modulus of less than 70 GPa; an alkali-soluble resin (B); and a photosensitizer (C). The median diameter of the metal particles (A) is 500 nm or less.

Description

Photosensitive resin composition and conductive adhesive using the same

[0001] The present invention relates to a photosensitive resin composition, a conductive adhesive using the same, a method for manufacturing a patterned substrate, an electronic device, and a method for manufacturing the same.

[0002] In recent years, with the miniaturization of electronic devices, mounting methods for electronic components, such as wire bonding and flip-chip methods, have become widely known. In particular, fine-pitch mounting of LED chips smaller than 50 μm x 50 μm, known as micro-LEDs, is being actively investigated. In micro-LED mounting, the flip-chip method is preferably used because it minimizes the wiring area between the chip and the substrate by forming electrodes on the chip surface and directly connecting the chip to the electrodes on the substrate. In the flip-chip mounting method, the bonding material used to electrically connect the electrodes on the chip surface and the electrodes on the substrate is called a bump. Conventionally, bumps have generally been formed mainly with solder. However, since the formation of bumps and the connection of bumps to electrodes involve melting of solder due to heating, when the electrode pitch is less than 20 μm, short circuits are likely to occur when adjacent bumps are connected by molten solder. Therefore, alternative bonding materials to solder are being investigated.

[0003] As a new bonding material to replace solder, for example, a conductive paste containing organic components and conductive particles has been proposed, wherein the storage modulus G'(P100) of the dried film of the conductive paste at 100°C is 0.01 MPa or less, and the storage modulus G'(C25) at 25°C after heating at 140°C for 30 minutes is 0.01 MPa or more (see, for example, Patent Document 1).

[0004] Japanese Patent Publication No. 2022-68144

[0005] The conductive paste described in Patent Document 1 can be used to form fine patterns. On the other hand, in recent years, there has been a demand for reduced power consumption in electronic devices, which has led to a need for even lower resistance in bonding materials.

[0006] Therefore, the present invention aims to provide a photosensitive resin composition that can reduce connection resistance even in fine patterns.

[0007] To solve the above problems, the present invention mainly has the following configuration: <1> A photosensitive resin composition comprising metal particles (A) containing a metal having a Young's modulus of less than 70 GPa, an alkali-soluble resin (B), and a photosensitive agent (C), wherein the median diameter of the metal particles (A) is 500 nm or less. <2> The photosensitive resin composition according to <1>, further comprising a thermosetting resin (D) having a softening point of 40°C or higher and less than 150°C. <3> The photosensitive resin composition according to <2>, wherein the thermosetting resin (D) has a structure represented by the following general formula (1A).

[0008] In the above general formula (1A), R １Ａ and R ２Ａ Each of these independently represents a C1-C6 alkyl group in which a hydrogen atom or a terminal hydrogen atom is substituted by an epoxy group. However, R １Ａ and R ２Ａ At least one of them is a C1-C6 alkyl group in which the terminal hydrogen atom is substituted with an epoxy group. <4> The photosensitive resin composition according to <3>, wherein the thermosetting resin (D) has both the structure represented by the above general formula (1A) and the structure represented by the following general formula (2).

[0009] In the above general formula (2), R ３ This represents an alkyl group having 1 to 6 carbon atoms, in which the terminal hydrogen atoms are substituted by epoxy groups. ４This represents a hydrogen atom, a methyl group, a methoxymethyl group, an ethoxymethyl group, a hydroxymethyl group, a hydroxyethyl group, or a C1-C6 alkyl group in which the terminal hydrogen atom is substituted with a glycidyloxy group. <5> A photosensitive resin composition according to any one of <1> to <4>, wherein the content of the metal particles (A) in the total solids is 10% by volume or more and 40% by volume or less. <6> A photosensitive resin composition according to any one of <1> to <5>, wherein the metal particles (A) contain tin. <7> A photosensitive resin composition according to any one of <1> to <6>, wherein the alkali-soluble resin (B) contains a novolac-type resin having an ethylenically unsaturated double bond in its side chain. <8> A photosensitive resin composition according to any one of <1> to <7>, further containing carbon particles. <9> A conductive adhesive comprising the photosensitive resin composition according to any one of <1> to <8>. <10> A method for manufacturing a patterned substrate, comprising the steps of forming a layer made of a photosensitive resin composition according to any one of <1> to <8> on a substrate, exposing the layer made of the photosensitive resin composition to an image, and developing it with an alkaline developer. <11> An electronic device in which a circuit board and an electronic component are electrically connected by a cured product of a photosensitive resin composition according to any one of <1> to <8>. <12> A method for manufacturing an electronic device according to <11>, comprising the steps of forming a bump pattern between an electrode of a circuit board and an electrode of an electronic component by the method according to <10>, and connecting the electrode of the circuit board and the electrode of the electronic component by heating and / or pressurizing the bump pattern.

[0010] According to the present invention, it is possible to provide a photosensitive resin composition that has low connection resistance even in fine patterns.

[0011] This is a schematic diagram of the circuit board used in the example. This is a schematic diagram of the substrate with a bump pattern used in the example. This is a schematic diagram of the glass chip with ITO electrodes used in the example. This is a schematic diagram of the glass chip mounting substrate with ITO electrodes used in the example. This is a schematic diagram of the circuit board used to evaluate the uniformity of connection resistance in the example. This is a schematic diagram of the substrate with a bump pattern used to evaluate the uniformity of connection resistance in the example. This is a schematic diagram of the glass chip with ITO electrodes used to evaluate the uniformity of connection resistance in the example. This is a schematic diagram of the glass chip mounting substrate with ITO electrodes used to evaluate the uniformity of connection resistance in the example.

[0012] The photosensitive resin composition of the present invention contains metal particles (A) containing a metal with a Young's modulus of less than 70 GPa (hereinafter sometimes abbreviated as "metal particles (A)"), an alkali-soluble resin (B), and a photosensitive agent (C). In the photosensitive resin composition of the present invention, the metal particles (A) have the function of exhibiting conductivity when the photosensitive resin composition is heat-cured, sintered, or compressed. In the present invention, by including a metal with a Young's modulus of less than 70 GPa in the metal particles (A), connection resistance can be significantly reduced as described later. Furthermore, by setting the median diameter of the metal particles (A) to 500 nm or less, fine patterns can be formed with high precision. The alkali-soluble resin (B) has the function of a binder resin that maintains the shape of the photosensitive resin composition and has the property of dissolving in an alkaline developer, thereby enabling patterning by photolithography. The photosensitive agent (C) has the function of imparting photosensitivity to the photosensitive resin composition. The details thereof will be described below.

[0013] <Metal Particles (A)> In the photosensitive resin composition of the present invention, the metal particles (A) include a metal having a Young's modulus of less than 70 GPa. As described above, the metal particles (A) have the function of exhibiting conductivity when the photosensitive resin composition is heat-cured, sintered, or compressed. For example, when the photosensitive resin composition is used as a bonding material (bump), in the connection process described later, when the bump is compressed, nearby metal particles present within the bump come into contact with each other to form a conductive path. At this time, the lower the Young's modulus of the metal particles, the greater the deformation when the metal particles come into contact with each other, increasing the contact area between the metal particles and thus lowering the connection resistance. In the present invention, by using metal particles (A) containing a metal having a Young's modulus of less than 70 GPa, the connection resistance can be lowered even in fine patterns. When metal particles made of a metal with a Young's modulus of 70 GPa or more are used, the contact area between the metal particles is small in the connection process, and the connection resistance is high. The Young's modulus of the metal is preferably 10 GPa or more, which allows the shape of the metal particles (A) to be appropriately maintained while forming a conductive path. Here, the Young's modulus of metals is listed in the "Science Almanac 2025" (edited by the National Astronomical Observatory of Japan, 2024). More specifically, the "Science Almanac 2025" lists the Young's modulus at 25°C measured for metal test pieces made of specific metal elements, and in this invention, that value is used as the Young's modulus of the metal.

[0014] Examples of metals with a Young's modulus of less than 70 GPa include cadmium, tin, bismuth, lead, indium, gallium, and thallium. Two or more of these may be included. Among these, metals selected from indium, bismuth, and tin are preferred from the viewpoint of compatibility with alkali-soluble resin (B) and particle dispersibility. In particular, tin is more preferred because it easily provides good adhesion with materials such as gold, silver, copper, titanium, aluminum, and indium tin oxide, which are used as electrodes for circuit boards and electronic components. That is, it is most preferable that the metal particles (A) contain tin.

[0015] The metal particles (A) may contain other metals in addition to a metal with a Young's modulus of less than 70 GPa. Examples of other metals include gold, silver, and aluminum. If the metal particles (A) contain tin, it is preferable to also contain silver, as this can suppress oxidation and further reduce connection resistance. In order to fully obtain the effect of the metal with a Young's modulus of less than 70 GPa, the content of other metals is preferably less than 30% by mass of the metal particles (A), more preferably 20% by mass or less, and even more preferably 10% by mass or less. The surface of the metal particles (A) may be oxidized in the atmosphere. However, particles containing 90% by mass or more of metal compounds such as metal oxides are not included in the metal particles (A) of this invention.

[0016] The median diameter of the metal particles (A) is 500 nm or less. As mentioned above, by making the median diameter of the metal particles (A) 500 nm or less, fine patterns can be formed with high precision. For example, when using a photosensitive resin composition as the bonding material (bump) as described above, it becomes necessary to form bumps on the order of several μm in size as the electrode pitch is narrowed. If the median diameter of the metal particles (A) exceeds 500 nm, it becomes difficult to form such fine patterns with high precision. The median diameter is preferably 200 nm or less, and more preferably 100 nm or less, as it allows for the formation of finer patterns with higher precision. On the other hand, the median diameter of the metal particles (A) is preferably 10 nm or more from the viewpoint of appropriately suppressing surface energy and inhibiting rapid oxidation reactions. Here, the median diameter of the metal particles (A) refers to the median diameter of the primary particles and can be determined by dynamic light scattering. Specifically, the median diameter can be determined by irradiating a dispersion of metal particles (A) with a concentration of 0.1 to 1 volume percent with light of a wavelength of 780 nm using a semiconductor laser, measuring the scattered light, and then performing frequency analysis using the FFT-heterodyne method. When there are two or more types of metal particles (A), the median diameter refers to the median diameter of the two or more types of metal particles (A) as a whole.

[0017] In terms of reducing the connection resistance, the content of the metal particles (A) in the total solid content of the photosensitive resin composition is preferably 10% by volume or more, more preferably 18% by volume or more. On the other hand, from the perspective of improving the transmittance of the exposure light in the exposure process described later and forming a finer pattern, the content of the metal particles (A) is preferably 40% by volume or less. Further, for example, when the photosensitive resin composition is used as the above-mentioned bonding material (bump), from the perspective of improving the bonding strength between the bump and the electrode by thermosetting in the curing process described later, it is more preferably 30% by volume or less, and even more preferably 28% by volume or less. Here, the solid content refers to the components constituting the photosensitive resin composition excluding liquid components such as solvents.

[0018] The content of the metal particles (A) in the total solid content of the photosensitive resin composition can be determined as follows. Apply the photosensitive resin composition on a substrate, and if it contains liquid components such as solvents, remove them by drying to form a photosensitive resin composition layer. Scrape off a part of the photosensitive resin composition layer to obtain a measurement sample. Place the measurement sample in a thermogravimetric analyzer and hold it at 800 °C in the air for 1 hour to remove the organic components. The ratio of the weight of the residue to the weight of the measurement sample (thermogravimetric analysis residue ratio) corresponds to the weight fraction of the metal particles (A) in the photosensitive resin composition. Also, the ratio of the weight reduced by measurement to the weight of the measurement sample (thermogravimetric analysis reduction rate) corresponds to the weight fraction of the organic components in the photosensitive resin composition. The content of the metal particles (A) in the total solid content of the photosensitive resin composition can be calculated by the following formula [1]. Here, 1.1 in formula [1] means the density of the organic components in the photosensitive resin composition. Most of the organic components used in the photosensitive resin composition have a density close to 1.1 g / cm ３ So, as an approximation, the density of the organic components is calculated as 1.1 g / cm ３ If the raw material composition ratio of the photosensitive resin composition is known, it can also be calculated from that composition ratio.

[0019]

[0020] <Alkali-soluble resin (B)>In the photosensitive resin composition of the present invention, the alkali-soluble resin refers to a polymer having a hydroxy group and / or a carboxy group. However, it does not include the thermosetting resin (D) described later.

[0021] In the photosensitive resin composition of the present invention, the glass transition point (Tg) of the alkali-soluble resin (B) is preferably 40°C or higher and 150°C or lower. When the Tg of the alkali-soluble resin (B) is 40°C or higher, the tackiness of the layer formed from the photosensitive resin composition described later can be suppressed, and the adhesion of foreign substances can be suppressed. On the other hand, when the Tg of the alkali-soluble resin (B) is 150°C or lower, for example, when the photosensitive resin composition is used as the above-mentioned bonding material (bump), in the connection process described later, the adhesiveness for fixing electronic components at a low temperature can be exhibited, so the load on the electronic components and the substrate can be reduced. Here, the Tg of the alkali-soluble resin (B) can be measured by the DSC method. When two or more kinds of alkali-soluble resins (B) are present, it is preferable that the Tg of the alkali-soluble resin (B) having the largest content is within the above range, and it is more preferable that the Tg of all the alkali-soluble resins (B) is within the above range.

[0022] Examples of alkali-soluble resins (B) include epoxy resins, polysiloxanes, polyimides, polyimide precursors, polybenzoxazoles, polybenzoxazole precursors, polyamide-imides, cardo resins, novolac-type resins, and (meth)acrylic resins. Two or more of these may be included. Among these, novolac-type resins or (meth)acrylic resins are preferred from the viewpoint of ease of manufacture. Here, (meth)acrylic resin refers to a polymer or copolymer of acrylic monomers and / or methacrylic monomers. Other monomers may be further copolymerized in the (meth)acrylic resin. Examples of (meth)acrylic monomers include methyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, benzyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Here, (meth)acrylate is a general term for acrylate and methacrylate. Other monomers include compounds having a carbon-carbon double bond, such as aromatic vinyl compounds like styrene and α-methylstyrene, and amide unsaturated compounds like (meth)acrylamide.

[0023] From the viewpoint of the dispersibility of metal particles (A), a novolac-type resin is more preferable as the alkali-soluble resin (B). Novolac-type resins have a high electron density due to having repeating phenol units in their main chain, and because they have a strong interaction with metal particles (A), the settling of metal particles (A) can be suppressed. Furthermore, the dispersibility of metal particles (A) can be further improved and the connection resistance can be further reduced. Novolac-type resins preferably have ethylenically unsaturated double bonds in their side chains, and can form a negative-type pattern in which the exposed area undergoes radical polymerization and becomes insoluble in the alkaline developer.

[0024] Novolac-type resins having ethylenically unsaturated double bonds in their side chains can be synthesized, for example, by (i) reacting epichlorohydrin with phenolic hydroxyl groups in a resin having phenolic hydroxyl groups in its main chain, such as a novolac resin, to introduce epoxy groups, and then adding (meth)acrylic acid to the epoxy groups; or (ii) adding (meth)acrylic acid to the epoxy groups of a novolac-type epoxy resin. Here, (meth)acrylic acid is a general term for acrylic acid and methacrylic acid. A catalyst may be used in this process to increase reaction efficiency and shorten reaction time. Examples of novolac resins used in method (i) include WR-101, WR-102, WR-103, WR-104, PR-50, PR-100L-50P, and PR-30-40P, all manufactured by DIC Corporation. Two or more of these may be used. Examples of novolac-type epoxy resins used in method (ii) include NC-3000, NC-3000-H, NC-3100, CER-3000, NC-2000, XD-1000, NC-7000, NC-7300, EPPN-501, EPPN-502, EOCN-1020, EOCN-102, EOCN-103, EOCN-104, CER-1020, EPPN-201, BREN-S, BREN-105, etc., all manufactured by Nippon Kayaku Co., Ltd. Two or more of these may be used. Examples of catalysts used in method (i) or (ii) include triethylamine, benzyldimethylamine, triethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium iodide, triphenylphosphine, triphenylstybin, methyltriphenylstybin, chromium octanoate, zirconium octanoate, and the like. Two or more of these may be used.

[0025] After adding (meth)acrylic acid by the methods described in (i) and (ii) above, a dicarboxylic acid anhydride may be added to the resulting hydroxyl group to introduce a carboxyl group and adjust the acid value. Examples of dicarboxylic acid anhydrides include phthalic acid anhydride, tetrahydrophthalic acid anhydride, maleic acid anhydride, glutaric acid anhydride, succinic acid anhydride, and derivatives thereof. Two or more of these may be used.

[0026] The weight-average molecular weight (Mw) of the alkali-soluble resin (B) is preferably 2,000 or more, and more preferably 3,000 or more, from the viewpoint of further improving the dispersibility of the metal particles (A). On the other hand, the Mw of the alkali-soluble resin (B) is preferably 20,000 or less, and more preferably 15,000 or less, from the viewpoint of obtaining appropriate solubility in the alkaline developer and forming a finer pattern. Here, Mw refers to the polystyrene equivalent value measured by gel permeation chromatography (GPC). When there are two or more types of alkali-soluble resin (B), Mw refers to the Mw of the two or more types of alkali-soluble resin (B) as a whole.

[0027] The acid value of the alkali-soluble resin (B) is preferably 30 mg KOH / g or higher, and more preferably 50 mg KOH / g or higher, from the viewpoint of improving solubility in the alkaline developer. On the other hand, the acid value of the alkali-soluble resin (B) is preferably 120 mg KOH / g or lower, and more preferably 110 mg KOH / g or lower, from the viewpoint of moderately suppressing solubility in the alkaline developer. Here, the acid value refers to the weight of potassium hydroxide that reacts with 1 g of alkali-soluble resin (B), and can be determined by titrating the alkali-soluble resin (B) with an aqueous potassium hydroxide solution. When there are two or more types of alkali-soluble resin (B), the acid value refers to the acid value of the two or more types of alkali-soluble resin (B) as a whole.

[0028] The content of the alkali-soluble resin (B) in the total solid content of the photosensitive resin composition of the present invention is preferably 5% by mass or more, for example, when the photosensitive resin composition is used as the aforementioned bonding material (bump), from the viewpoint of improving the adhesion between the bump pattern and the electrode in the connection process described later, and further increasing the bonding strength between the bump and the electrode by thermosetting. Furthermore, from the viewpoint of improving the processability of the photosensitive resin composition by maintaining appropriate viscosity characteristics and forming a finer pattern, it is preferably 10% by mass or more, and more preferably 15% by mass or more. On the other hand, from the viewpoint of further reducing connection resistance, the content of the alkali-soluble resin (B) is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0029] <Photosensitive agent (C)> Examples of photosensitive agent (C) include photopolymerization initiators and photoacid generators. When a photopolymerization initiator is included as the photosensitive agent (C), it is preferable to further include a component having an ethylenically unsaturated double bond, which allows for the formation of a negative-type pattern in which the exposed area becomes insoluble due to photopolymerization of the exposed area during the exposure process. On the other hand, when a photoacid generator is included as the photosensitive agent (C), it is possible to form a positive-type pattern in which the solubility of the exposed area increases during the exposure process.

[0030] Examples of photopolymerization initiators include benzophenone derivatives, acetophenone derivatives, thioxanthone derivatives, benzyl derivatives, benzoin derivatives, oxime compounds, α-hydroxyketone compounds, α-aminoalkylphenone compounds, phosphine oxide compounds, anthrone compounds, and anthraquinone compounds. Two or more of these may be included.

[0031] When the photosensitive agent (C) contains a photopolymerization initiator, the content of the photopolymerization initiator in the total solid content of the photosensitive resin composition of the present invention is preferably 0.5 to 5% by mass.

[0032] Examples of photoacid generators include naphthoquinone diazide compounds, such as compounds having a 5-naphthoquinone diazidosulfonyl group and a 4-naphthoquinone diazidosulfonyl group. Two or more of these may be included.

[0033] When the photosensitive resin composition of the present invention contains a photoacid generator as the photosensitive agent (C), the content of the photoacid generator in the total solid content is preferably 1 to 20% by mass.

[0034] <Components having ethylenically unsaturated double bonds> When a photopolymerization initiator is included as the photosensitive agent (C), examples of components having ethylenically unsaturated double bonds include those alkali-soluble resins (B) mentioned above that have double bonds in their side chains, and monomers or oligomers having two or more ethylenically unsaturated double bonds in their molecules. Two or more of these may be included. Among these, monomers or oligomers having two or more (meth)acryloyl groups in their molecules are preferred. Examples include compounds having two acryloyl groups, such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,4-butanediol diacrylate, glycerin diacrylate, tripropylene glycol diacrylate, ethoxylated (4) bisphenol A diacrylate, ethoxylated (10) bisphenol A diacrylate, and acrylic acid adducts of ethylene glycol diglycidyl ether; compounds having three acryloyl groups, such as pentaerythritol triacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, and glycerin propoxytriacrylate; compounds having four acryloyl groups, such as dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, and ditrimethylolpropane tetraacrylate, as well as compounds in which the acrylic groups are replaced with methacrylic groups.

[0035] The content of monomers and oligomers having ethylenically unsaturated double bonds in the total solid content of the photosensitive resin composition of the present invention is preferably 2 to 20% by mass.

[0036] <Thermosetting Resin (D)> The photosensitive resin composition of the present invention preferably further contains a thermosetting resin (D) (hereinafter sometimes abbreviated as "thermosetting resin (D)") having a softening point of 40°C or more and less than 150°C. The thermosetting resin (D) in the present invention refers to a resin having a group selected from epoxy group, glycidyl group, oxetanyl group, styryl group, hydroxysilyl group, methoxymethyl group, amino group, vinyloxy group, and cyclobutenyl group. Among these groups, it is preferable to have an epoxy group because the introduction of substituents is easy and it has high reactivity. The thermosetting resin (D) may further have other groups. Resins having the above-mentioned groups, as well as both a hydroxyl group and / or a carboxyl group, shall be classified as thermosetting resin (D). When such a thermosetting resin (D) is used, for example, as a bonding material (bump) as described above, its fluidity is improved by heating and / or pressurizing in the connection step described later, thereby improving the adhesion between the bump pattern and the electrode. Furthermore, thermosetting can further increase the bonding strength between the bump and the electrode. The softening point of the thermosetting resin (D) is more preferably 60°C or higher. On the other hand, from the viewpoint of performing connection at a lower temperature during the connection process, the softening point of the thermosetting resin (D) is preferably 120°C or lower, and more preferably 100°C or lower. Here, the softening point of the thermosetting resin (D) can be measured using an automatic softening point measuring device, for example, the automatic softening point measuring system DP90 (manufactured by Mettler Toledo K.K.), under the condition of a heating rate of 1°C / min.

[0037] Examples of thermosetting resins (D) include epoxy resins, methylol resins, melamine resins, and siloxane resins. Two or more of these may be included. Among these, epoxy resins having a novolac-type structure or a bisphenol-type structure are preferred. Having these structures suppresses oxidative degradation of the metal particles (A) and improves the uniformity of the connection resistance.

[0038] Examples of epoxy resins having a bisphenol-type structure include resins having a structure represented by the following general formula (1A), compounds having a structure represented by the following general formula (1B), or epoxy ring-opening adducts thereof.

[0039]

[0040] In the general formula (1A), R １Ａ and R ２Ａ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms in which the terminal hydrogen atom is substituted by an epoxy group. However, at least one of R １Ａ and R ２Ａ is an alkyl group having 1 to 6 carbon atoms in which the terminal hydrogen atom is substituted by an epoxy group.

[0041] In the general formula (1B), R １Ｂ and R ２Ｂ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms in which the terminal hydrogen atom is substituted by an epoxy group.

[0042] The epoxy ring-opening adduct of the compound having the structure represented by the general formula (1B) means that, as the compound having the structure represented by the general formula (1B), when both a compound having a structure in which at least one of R １Ｂ and R ２Ｂ is a hydrogen atom and a compound having a structure in which at least one of R １Ｂ and R ２Ｂ is an alkyl group having 1 to 6 carbon atoms in which the terminal hydrogen atom is substituted by an epoxy group are present, it refers to a product in which the hydroxyl group of one compound and the epoxy group of the other compound are bonded by an epoxy ring-opening addition reaction.

[0043] Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, etc. The alkyl group may have any of a linear, branched, or cyclic structure. Note that the carbon number of the alkyl group does not include the carbon number of the substituted epoxy group. In some cases, a structure in which the hydrogen of the methyl group is substituted by an epoxy group may be described as a glycidyl group.

[0044] The resin having the structure represented by the above general formula (1A) preferably has a structure in which the structure represented by the above general formula (1A) is linked via alkylene groups. A methylene group is preferred as the alkylene group. The number of repetitions of the structure represented by the above general formula (1A) is preferably 2 to 5 from the viewpoint of adjusting the softening point to an appropriate range. Also, R １Ａ and R ２Ａ It is preferable that both are alkyl groups having 1 to 6 carbon atoms substituted with epoxy groups.

[0045] Epoxy resins having a novolac-type structure preferably have a structure represented by the following general formula (2). More preferably, the epoxy resin contains both the structure represented by the above general formula (1A) and the structure represented by the following general formula (2).

[0046]

[0047] In the above general formula (2), R ３ This represents an alkyl group having 1 to 6 carbon atoms, in which the terminal hydrogen atoms are substituted by epoxy groups. ４ This represents a C1-C6 alkyl group in which a hydrogen atom, a methyl group, a methoxymethyl group, an ethoxymethyl group, a hydroxymethyl group, a hydroxyethyl group, or a terminal hydrogen atom is substituted with a glycidyloxy group.

[0048] An epoxy resin having both the structure represented by the above general formula (1A) and the structure represented by the above general formula (2) preferably has a structure in which the structure represented by the above general formula (1A) and the structure represented by the above general formula (2) are linked via an alkylene group, and a methylene group is preferred as the alkylene group. Also, R ４ Preferably, the alkyl group has 1 to 6 carbon atoms in which the terminal hydrogen atoms are substituted with glycidyloxy groups.

[0049] Examples of epoxy resins having the structure represented by the general formula (1A) include the trade name "jER®" 157S65 (epoxy equivalent: 205, softening point: 65°C, manufactured by Mitsubishi Chemical Corporation) and "jER" 157S70 (epoxy equivalent: 210, softening point: 70°C, manufactured by Mitsubishi Chemical Corporation).

[0050] Examples of epoxy ring-opening adducts of compounds having the structure represented by the general formula (1B) include: Trade name: "EPICLON®" 1050 (epoxy equivalent: 475, softening point: 69°C, manufactured by DIC Corporation), Trade name: "EPICLON" 2050 (epoxy equivalent: 635, softening point: 85°C, manufactured by DIC Corporation), Trade name: "EPICLON" 3050 (epoxy equivalent: 780, softening point: 96°C, manufactured by DIC Corporation), Trade name: "EPICLON" 4050 (epoxy equivalent: 950, softening point: 100°C, manufactured by DIC Corporation), Trade name: "EPIC Examples include "LON" 7050 (epoxy equivalent: 1,930, softening point: 127°C, manufactured by DIC Corporation), "EPICLON" HM-091 (epoxy equivalent: 2,600, softening point: 143°C, manufactured by DIC Corporation), "jER" 1003F (epoxy equivalent: 750, softening point: 96°C, manufactured by Mitsubishi Chemical Corporation), "jER" 1004FS (epoxy equivalent: 810, softening point: 100°C, manufactured by Mitsubishi Chemical Corporation), and "jER" 1005F (epoxy equivalent: 1,000, softening point: 103°C, manufactured by Mitsubishi Chemical Corporation).

[0051] Examples of epoxy resins having the structure represented by the general formula (2) include the following: trade name: "EPICLON" N-770 (epoxy equivalent: 188, softening point: 70°C, manufactured by DIC Corporation), trade name: "EPICLON" N-775 (epoxy equivalent: 189, softening point: 75°C, manufactured by DIC Corporation), and trade name: "EPICLON" N-660 (epoxy equivalent: 208, softening point: 65°C, manufactured by DIC Corporation).

[0052] Examples of epoxy resins having both the structure represented by the general formula (1A) and the structure represented by the general formula (2) include the product name "EPICLON" N-865 (epoxy equivalent: 208, softening point: 68°C, manufactured by DIC Corporation), the product name "EPICLON" N-885 (epoxy equivalent: 210, softening point: 80°C, manufactured by DIC Corporation), and the product name "EPICLON" N-890 (epoxy equivalent: 210, softening point: 83°C, manufactured by DIC Corporation).

[0053] The content of the thermosetting resin (D) in the total solid content of the photosensitive resin composition of the present invention is preferably 1% by mass or more, and more preferably 3% by mass or more, from the viewpoint of improving the fluidity of the bump pattern in the connection process. On the other hand, the content of the thermosetting resin (D) is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of increasing the content of metal particles (A) and further reducing connection resistance.

[0054] <Conductive components other than metal particles (A)> The photosensitive resin composition of the present invention preferably further contains conductive components other than metal particles (A), which can further reduce the connection resistance. Nonmetals are preferred as conductive components other than metal particles (A) from the viewpoint of improving compatibility with alkali-soluble resin (B). Examples include carbon particles, conductive polymers, and organic semiconductors such as charge transfer complexes. Two or more of these may be included. Among these, carbon particles are preferred from the viewpoint of further reducing the connection resistance without requiring treatments such as doping or orientation control. Carbon particles can take various forms such as graphene, graphene nanoribbons, carbon nanotubes, and conductive carbon black, but conductive carbon black, which is inexpensive and readily available, is preferably used.

[0055] The content of conductive components other than metal particles (A) in the solid content of the photosensitive resin composition of the present invention is preferably 3% by mass or more and 25% by mass or less. From the viewpoint of lowering the connection resistance, the content is preferably 3% by mass or more, and more preferably 5% by mass or more. From the viewpoint of improving the bonding strength between the bump and the electrode, the content is preferably 25% by mass or less, and more preferably 20% by mass or less.

[0056] <Solvent> The photosensitive resin composition of the present invention may further contain a solvent. Examples of solvents include N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethyl sulfoxide, γ-butyrolactone, ethyl lactate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. Two or more of these may be included.

[0057] <Other Components> The photosensitive resin composition of the present invention may contain additives such as plasticizers, leveling agents, surfactants, silane coupling agents, defoamers, and pigments, to the extent that they do not impair the desired properties.

[0058] <Method for Producing Photosensitive Resin Composition> The photosensitive resin composition of the present invention can be produced by mixing the above-mentioned components (A) to (C) and, if necessary, other components. Examples of mixing equipment include dispersers and kneaders such as mechanical stirrers, three-roller mills, ball mills, and planetary ball mills, and an appropriate mixing equipment can be selected according to the viscosity of the photosensitive resin composition.

[0059] The photosensitive resin composition of the present invention exhibits conductivity upon heat curing, firing, or compression, and can therefore be used for wiring applications such as routing wires and ITO substitute mesh wiring, as well as for conductive adhesive applications for mounting electronic components on circuit boards. Among these, it is particularly suitable for use as a conductive adhesive.

[0060] The conductive adhesive of the present invention comprises the above-mentioned photosensitive resin composition.

[0061] <Method for Manufacturing a Patterned Substrate> Next, the method for manufacturing a patterned substrate according to the present invention will be described. The method for manufacturing a patterned substrate according to the present invention comprises the steps of forming a layer made of the photosensitive resin composition of the present invention on a substrate (hereinafter sometimes abbreviated as the "photosensitive resin composition layer formation step"), exposing the layer made of the photosensitive resin composition to an image (hereinafter sometimes abbreviated as the "exposure step"), and developing it with an alkaline developer (hereinafter sometimes abbreviated as the "development step"). This makes it possible to form a bump pattern on the substrate.

[0062] In the method for manufacturing a patterned substrate of the present invention, it is preferable to further include a step of compressing the obtained bump pattern (hereinafter sometimes abbreviated as "compression step"), a step of heat curing (hereinafter sometimes abbreviated as "cure step"), or a step of firing (hereinafter sometimes abbreviated as "firing step") after the development step. Depending on the composition of the photosensitive resin composition, the heat resistance temperature of the substrate, and the desired properties, one of the compression step, cure step, or firing step can be selected.

[0063] First, the process of forming the photosensitive resin composition layer will be described. One method is to apply the photosensitive resin composition of the present invention onto a substrate to form a coating film, thereby forming a layer made of the photosensitive resin composition (hereinafter also referred to as the photosensitive resin composition layer). If the photosensitive resin composition contains a solvent, the solvent is removed by drying after the coating film is formed.

[0064] Examples of substrates include polyester films such as PET film, polyimide films, aramid films, epoxy resin substrates, polyetherimide resin substrates, polyetherketone resins, polysulfone resin substrates, glass substrates, silicon wafers, alumina substrates, aluminum nitride substrates, silicon carbide substrates, decorative layer-forming substrates, insulating layer-forming substrates, and ceramic green sheets.

[0065] Methods for applying the photosensitive resin composition of the present invention to a substrate include, for example, a rotary coating method using a spinner, a spray coating method, a roll coating method, a screen printing method, and a coating method using a coater such as a blade coater, die coater, calender coater, meniscus coater, or bar coater.

[0066] The thickness of the resulting coating film can be appropriately set from the total solid content concentration of the photosensitive resin composition so that the thickness of the photosensitive resin composition layer after drying becomes the desired thickness.

[0067] Methods for drying the coated film include, for example, heat drying using an oven, hot plate, or infrared radiation, as well as vacuum drying. In the case of heat drying, the heating temperature is preferably 50 to 180°C, and the heating time is preferably 1 minute to several hours.

[0068] The thickness of the photosensitive resin composition layer formed in the photosensitive resin composition layer formation process is preferably 0.1 to 10 μm. Here, the thickness of the photosensitive resin composition layer can be measured using a stylus-type step meter such as "Surfcom" (registered trademark) 1400 (manufactured by Tokyo Seimitsu Co., Ltd.). More specifically, the thickness can be calculated by measuring the thickness at three randomly selected locations using a stylus-type step meter under the conditions of measuring length: 1 mm and scanning speed: 0.3 mm / second, and then calculating the average value.

[0069] Next, the exposure process will be described. The photosensitive resin composition layer may be exposed to image-like light through an arbitrary pattern-forming mask, or it may be exposed to image-like light using a direct-writing exposure apparatus. As the light source for exposure, the i-line (365 nm), h-line (405 nm), and g-line (436 nm) of a mercury lamp are preferably used.

[0070] Next, the development process will be described. The photosensitive resin composition layer exposed in the exposure process is developed using an alkaline developer to dissolve and remove unexposed areas to obtain a bump pattern of the desired shape. Examples of alkaline developers include strong alkaline aqueous solutions such as TMAH (tetramethylammonium hydroxide), sodium hydroxide, and potassium hydroxide, and weak alkaline aqueous solutions such as diethanolamine, diethylaminoethanol, sodium carbonate, and potassium carbonate. Since the photosensitive resin composition of the present invention can form fine patterns even when developed using a strong alkaline developer, a strong alkaline aqueous solution is preferred as the developer, and a TMAH aqueous solution is more preferred. The content of the alkaline component in the alkaline developer is preferably 1% by mass or more, from the viewpoint of suppressing development time fluctuations due to carbonates generated by reaction with carbon dioxide in the air.

[0071] These alkaline developers may further contain polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and γ-butyrolactone; alcohols such as methanol, ethanol, and isopropanol; esters such as ethyl lactate and propylene glycol monomethyl ether acetate; ketones such as cyclopentanone, cyclohexanone, isobutyl ketone, and methyl isobutyl ketone; and surfactants.

[0072] Examples of development methods include spraying the developer onto the exposed film surface while the substrate is stationary or rotating, immersing the substrate in the developer, and applying ultrasonic waves while the substrate is immersed in the developer.

[0073] The pattern obtained by development may be subjected to a rinsing treatment with a rinsing solution. Examples of rinsing solutions include water, and aqueous solutions of the aforementioned alcohols and esters.

[0074] Next, the compression process will be explained. The compression process reduces the volume of the bump pattern, thereby improving its conductivity.

[0075] Compression methods include, for example, using a heat-pressing tool for flip-chip bonders to heat-press electronic components onto a substrate at a desired load and temperature, or pre-arranging electronic components on a substrate and then heat-pressing them using a vacuum diaphragm laminator.

[0076] Next, the curing process will be explained. The curing process improves the conductivity of the bump pattern by causing volume shrinkage of the bump pattern due to the curing of the organic components. From the viewpoint of sufficiently promoting volume shrinkage due to the curing of the organic components to further improve conductivity and adhesion, a heating temperature of 120°C or higher is preferred. On the other hand, from the viewpoint of suppressing thermal decomposition of the alkali-soluble resin (B) and further improving adhesion, a heating temperature of 280°C or lower is preferred.

[0077] Curing methods include, for example, heating and drying using an oven, inert oven, or hot plate, as well as heating and drying using electromagnetic waves such as ultraviolet lamps, infrared heaters, halogen heaters, and xenon flash lamps, or microwaves. The curing process increases the hardness of the pattern, suppressing chipping and peeling due to contact with other materials. It also improves adhesion to the substrate.

[0078] Next, the firing process will be explained. The firing process can improve the conductivity of the bump pattern by causing volume shrinkage of the bump pattern. From the viewpoint of sufficiently advancing the thermal decomposition of organic components and the sintering of metal particles (A) to further improve conductivity and adhesion, a firing temperature of 600°C or higher is preferred. On the other hand, from the viewpoint of suppressing wire breakage due to oversintering of metal particles (A), a firing temperature of 1,000°C or lower is preferred.

[0079] Examples of firing methods include atmospheric firing, inert atmosphere firing, and reducing atmosphere firing. Inert atmosphere firing is a method of firing while flowing an inert gas such as nitrogen gas, while reducing atmosphere firing is a method of firing while flowing a reducing gas such as hydrogen gas. Examples of firing equipment include box furnaces and firing furnaces. The firing conditions can be appropriately selected according to the type of metal particles (A) and the desired properties.

[0080] <Electronic Device and Method for Manufacturing the Same> The electronic device of the present invention comprises a circuit board and electronic components electrically connected by a cured product of the photosensitive resin composition of the present invention. Examples of electronic components include light-emitting components such as micro-LEDs and mini-LEDs, circuit components such as inductors and SAW filters, and semiconductor components such as memory and diodes.

[0081] The electronic device of the present invention can be manufactured by the following method. For example, first, a bump pattern is formed between the electrodes of the circuit board and the electrodes of the electronic component by the photosensitive resin composition layer formation step, exposure step, and development step in the method for manufacturing a patterned substrate described above. Next, a connection step is performed in which the electrodes of the circuit board and the electrodes of the electronic component are connected by heating and / or pressurizing this bump pattern.

[0082] In the pre-connection state, the alkali-soluble resin (B) acts as the matrix of the bump pattern, suppressing the aggregation of metal particles (A) and the formation of conductive paths. Therefore, the bump pattern is not electrically conductive before connection.

[0083] In the connection process, the circuit board and electronic components are bonded via the bump pattern, and the electrodes of the circuit board and the electrodes of the electronic components are electrically connected. Furthermore, the metal particles within the bump pattern come into contact with each other, forming a conductive path. In other words, the bump pattern becomes electrically conductive only after the connection process. This creates a conductive path between the electrodes of the circuit board and the electrodes of the electronic components. At this point, the bump pattern hardens and becomes a bump. To obtain a stable conductive path, heating and pressurizing are preferable during the connection process.

[0084] Examples of heating / pressurizing devices used in the connection process include heating and crimping tools for flip-chip bonders and vacuum diaphragm laminators.

[0085] The present invention will be described below with reference to examples. The embodiments of the present invention are not limited to these examples.

[0086] The evaluation method for each example is as follows.

[0087] <Connection Resistance> A 50 mm square circuit board was prepared, with an ITO electrode 2 formed on a glass substrate 1, as shown in Figure 1. The ITO electrode 2 has terminal electrodes a and b on a part of it. The photosensitive resin composition obtained in each example and comparative example was coated over the entire surface of this circuit board so that the film thickness after drying would be 1.5 μm. It was dried in a drying oven at a temperature of 100°C for 10 minutes to form a photosensitive resin composition layer with a film thickness of 1.5 μm. For the obtained photosensitive resin composition layer, as shown in Figure 2, a photomask having a rectangular pattern with an aperture of 1 mm × 10 mm was placed so that the bump pattern 3 was positioned on the ITO electrode 2, and exposure was performed using an exposure apparatus with an ultra-high pressure mercury lamp (PEM-6M; manufactured by Union Optical Co., Ltd.) with i-line (wavelength 365 nm) at an exposure dose of 500 mJ / cm². ２ Exposure was performed. After exposure, the substrate was developed using a 2.38 mass% TMAH aqueous solution, rinsed with ultrapure water to form a bump pattern 3, and obtained a substrate with a bump pattern. Figure 2 shows a schematic plan view (a) and a schematic cross-sectional view (b) of the obtained substrate with a bump pattern. The bump pattern 3 is located on the ITO electrode 2.

[0088] Next, an ITO electrode-equipped glass chip was prepared, as shown in Figure 3, in which a 0.2 mm x 3 mm ITO electrode 5 was formed in the center of a 1 mm x 3 mm glass chip 4. Figure 3 shows a schematic plan view (a) and a schematic cross-sectional view (b) of the ITO electrode-equipped glass chip. Next, as shown in Figure 4(a), the ITO electrodes 5 of the ITO electrode-equipped glass chip were placed in the center of each of the three pairs of bump patterns 3 of the bump pattern substrate obtained by the method described above, so that the ITO electrodes 5 face the bump pattern 3. In this state, the ITO electrode-equipped glass chip mounting substrate was fabricated by mounting using a bonder FC-3000 (Toray Engineering Co., Ltd.) under the conditions of a temperature of 130°C, a pressurizing pressure of 5 MPa, and a pressurizing time of 10 seconds. Figure 4 shows a schematic plan view (a) and a schematic cross-sectional view (b) of the obtained ITO electrode-equipped glass chip mounting substrate. A glass chip 4 with an ITO electrode is provided on the bump pattern 3 between terminal electrodes a and b of the ITO electrode 2.

[0089] The obtained ITO electrode-equipped glass chip mounting substrate was heated in an inert oven under a nitrogen atmosphere at 230°C for 30 minutes. Then, terminal electrode a and terminal electrode b were connected with a tester, and the resistance value between the terminal electrodes was measured.

[0090] The connection resistance was calculated by subtracting the resistance of the ITO electrode from the obtained resistance value.

[0091] <Bonding Strength> For the ITO electrode-equipped glass chip mounting substrate used in the evaluation of <Connection Resistance> above, the substrate was heated in an inert oven under a nitrogen atmosphere at 230°C for 30 minutes. Then, using a die shear strength measuring device (Dage series 4000; manufactured by Dage), the die shear strength of each of the three mounted ITO electrode-equipped glass chips was measured under conditions of a temperature of 25°C and a shear rate of 200 μm / second, and the average value was calculated.

[0092] <Fine Pattern Processing Capability> The photosensitive resin compositions obtained in each example and comparative example were coated over the entire surface of a glass substrate so that the film thickness after drying was 1.5 μm. The substrate was dried in a drying oven at a temperature of 100°C for 10 minutes to form a photosensitive resin composition layer with a film thickness of 1.5 μm. Photomasks having circular openings with diameters of φ3, 5, 7, 10, 12, 15, and 30 μm were placed on the obtained photosensitive resin composition layer, and exposure was performed using an exposure apparatus with an ultra-high pressure mercury lamp (PEM-6M; manufactured by Union Optical Co., Ltd.) with i-line (wavelength 365 nm) at an exposure dose of 500 mJ / cm². ２ Exposure was performed. After exposure, the substrate was developed using a 2.38% by mass TMAH aqueous solution, rinsed with ultrapure water to form a bump pattern, and obtained a substrate for evaluating fine pattern processability.

[0093] Each bump pattern on the obtained substrate for evaluating fine pattern machinability was observed under magnification using an optical microscope. Among the patterns in which no residue or pattern delamination was observed between bump patterns, the bump diameter of the pattern with the smallest bump diameter value was defined as the fine pattern machinability.

[0094] <Uniformity of Connection Resistance> Figure 5 shows a schematic diagram of the circuit board used to evaluate the uniformity of connection resistance. It is a 100 mm square circuit board with four of the circuit boards shown in Figure 1 arranged on the same plane. Each circuit board has an ITO electrode 2 formed on a glass substrate 1, similar to the circuit board shown in Figure 1, and the ITO electrode 2 has terminal electrodes a and b on a part of it. Using the same method as for the evaluation of <connection resistance> above, bump patterns were formed on the four circuit boards using the photosensitive resin compositions obtained in Examples 15 to 22 and Comparative Example 3 to obtain substrates with bump patterns. Figure 6 shows a schematic plan view of the obtained substrates with bump patterns.

[0095] Next, three types of ITO electrode-equipped glass chips were prepared, each consisting of a 1 mm x 3 mm glass chip 4 with ITO electrodes 5 measuring 0.2 mm x 3 mm, 0.1 mm x 3 mm, and 0.05 mm x 3 mm formed in the center, as shown in Figure 7. Figure 7 shows a schematic plan view (a) and a schematic cross-sectional view (b) of the ITO electrode-equipped glass chip. Using the same method as for the evaluation of the <connection resistance> described above, the ITO electrode-equipped glass chip was mounted on a substrate with a bump pattern to produce an ITO electrode-equipped glass chip mounting substrate. Figure 8 shows a schematic plan view of the obtained ITO electrode-equipped glass chip mounting substrate.

[0096] The obtained glass chip mounting substrates with ITO electrodes were heated in an inert oven under a nitrogen atmosphere at 230°C for 30 minutes. Then, all terminal electrodes in the plane were connected using a tester, and the resistance value between each terminal electrode was measured. The connection resistance was calculated by subtracting the resistance value of the ITO electrodes from the obtained resistance value. Of all the obtained connection resistance values, the percentage of the difference between the maximum and minimum values ​​divided by the minimum value was calculated as the variation in connection resistance and used as an indicator of the uniformity of connection resistance. A smaller variation in connection resistance indicates better uniformity of connection resistance.

[0097] The materials used in the examples and comparative examples are as follows:

[0098] [Metal particles (A)] ・Tin particles (A-1): Manufactured by Nisshin Engineering Co., Ltd. (median diameter 40 nm, specific gravity 7.2 g / cm³) ３(Resistivity 13 μΩ·cm, Young's modulus 51 GPa) • Tin particles (A-2): Manufactured by Nisshin Engineering Co., Ltd. (Median diameter 120 nm, specific gravity 7.2 g / cm³) ３ (With a resistivity of 13 μΩ·cm and a Young's modulus of 51 GPa).

[0099] • Tin-silver alloy particles (A-3): Manufactured by Nisshin Engineering Co., Ltd. (median diameter 80 nm, specific gravity 7.4 g / cm³) ３ Resistivity 13 μΩ·cm, Young's modulus 51 GPa, Sn / Ag = 97 / 3 (mass ratio) • Tin-silver alloy particles (A-4): Manufactured by Nisshin Engineering Co., Ltd. (median diameter 290 nm, specific gravity 7.4 g / cm³) ３ Resistivity 13 μΩ·cm, Young's modulus 51 GPa, Sn / Ag = 97 / 3 (mass ratio) • Tin-silver alloy particles (A-5): Manufactured by Nisshin Engineering Co., Ltd. (median diameter 790 nm, specific gravity 7.4 g / cm³) ３ Resistivity 13 μΩ·cm, Young's modulus 51 GPa, Sn / Ag = 97 / 3 (mass ratio) • Indium particles (A-6): Manufactured by Merck KGaA (median diameter 80 nm, specific gravity 7.3 g / cm³) ３ (Resistivity 8.4 μΩ・cm, Young's modulus 11 GPa) (Production Example 1: Tin particle (A-1) dispersion) 20.0 g of the above tin particle (A-1), 2.0 g of the dispersant "DISPERBYK®" 2200 (manufactured by Bic Chemie), and 78.0 g of propylene glycol monomethyl ether monoacetate (PGMEA) were mixed and subjected to a mixing treatment using a homogenizer at 1,200 rpm for 30 minutes. Thereafter, the mixture was further dispersed using a high-pressure wet medialess atomizer "Nanomizer®" (Nanomizer Co., Ltd.) to obtain a tin particle dispersion with a solid content of 22.0 mass% and a tin particle (A-1) content of 20.0 mass%.

[0100] (Production Example 2: Tin particle (A-2) dispersion) A tin particle dispersion with a solid content of 22.0% by mass and a tin particle (A-2) content of 20.0% by mass was obtained in the same manner as in Production Example 1, except that 20.0 g of the above tin particle (A-2) was used instead of 20.0 g of tin particle (A-1).

[0101] (Production Examples 3-5: Dispersions of tin-silver alloy particles (A-3) to (A-5)) Except that 20.0 g of the above tin-silver alloy particles (A-3) to (A-5) were used instead of 20.0 g of tin particle (A-1), a dispersion of tin-silver alloy particles with a solid content of 22.0 mass% and a tin-silver alloy particle (A-3) to (A-5) content of 20.0 mass% was obtained in the same manner as in Production Example 1.

[0102] (Production Example 6: Indium Particle (A-6) Dispersion) An indium particle dispersion with a solid content of 22.0% by mass and an indium particle (A-6) content of 20.0% by mass was obtained in the same manner as in Production Example 1, except that 20.0 g of the above indium particles (A-6) were used instead of 20.0 g of tin particles (A-1).

[0103] [Conductive components other than metal particles (A)] ・Carbon-coated Ag particles: Carbon-coated Ag particles manufactured by Nisshin Engineering Co., Ltd. (average thickness of surface carbon coating layer: 1 nm, median diameter: 40 nm, specific gravity: 9.5 g / cm²) ３ (Resistivity 3.2 μΩ·cm, Young's modulus 83 GPa) • Conductive carbon particles: Conductive carbon particles manufactured by Cabot (volume average particle diameter 50 nm, specific gravity 1.9 g / cm³) ３ , specific resistance 1.7 mΩ・cm).

[0104] (Manufacturing Example 7: Carbon-Coated Ag Particle Dispersion) 20.0 g of the above carbon-coated Ag particles, 2.0 g of the dispersant "DISPERBYK" 2200 (manufactured by Bic Chemie), and 78.0 g of PGMEA were mixed and subjected to a homogenizer mixing process at 1,200 rpm for 30 minutes. Subsequently, the mixture was further dispersed using a high-pressure wet media-less atomization device "Nanomizer" (Nanomizer Co., Ltd.) to obtain a carbon-coated Ag dispersion with a volume-average particle diameter of 0.10 μm, a solid content of 22.0% by mass, and a carbon-coated Ag particle content of 20.0% by mass.

[0105] (Manufacturing Example 8: Conductive Carbon Particle Dispersion) 13.6 g of the above conductive carbon particles, 1.4 g of the dispersant "DISPERBYK" 2200 (manufactured by Bic Chemie), and 85.0 g of PGMEA were mixed and subjected to a homogenizer mixing process at 1,200 rpm for 30 minutes. Subsequently, the mixture was further dispersed using a high-pressure wet media-less atomization device "Nanomizer" (Nanomizer Co., Ltd.) to obtain a conductive carbon particle dispersion with a volume-average particle diameter of 0.15 μm, a solid content of 15.0 mass%, and a conductive carbon particle content of 13.6 mass%.

[0106] [Alkali-soluble resin (B)] ・Alkali-soluble resin (B-1) SPCR-10: Alkali-soluble acrylic resin manufactured by Resonaq Corporation (acid value 100 mg KOH / g, glass transition temperature 71°C, Mw 18,000, solids content 37% by mass in PGMEA solution) ・Alkali-soluble resin (B-2) SPCR-199X: Alkali-soluble acrylic resin manufactured by Resonaq Corporation (acid value 71 mg KOH / g, glass transition temperature 55°C, Mw 12,000, solids content 37% by mass in PGMEA solution) ・Alkali-soluble resin (B-3) (Synthesis example 1: Alkali-soluble resin (B-3)) In a reaction vessel equipped with a stirrer, condenser, thermometer, and gas inlet, 288.0 g of novolac-type epoxy resin NC-3000-H (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 288 g / eq) and 72.1 g of acrylic acid were added. 3 g of triphenylphosphine was added as a catalyst and PGMEA as a solvent to a solid content of 80% by mass. The mixture was heated and stirred at 100°C for 24 hours to obtain a precursor solution of alkali-soluble resin (B-3). To 200.0 g of the obtained solution, 30.9 g of 1,2,3,6-tetrahydrophthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) and PGMEA were added to a solid content of 65% by mass. The mixture was heated and stirred at 100°C for 3 hours to obtain a PGMEA solution of alkali-soluble resin (B-3). The obtained alkali-soluble resin (B-3) had a solid content acid value of 62 mg KOH / g and a glass transition temperature of 112°C. The weight-average molecular weight Mw on a polystyrene basis was 3,600.

[0107] [Photosensitive agent (C)] ・OXE-04: "IRGACURE (registered trademark)" OXE-04 (oxime ester photopolymerization initiator manufactured by BASF Japan Ltd.) [Thermosetting resin (D)] ・N-865: "EPICLON (registered trademark)" N-865 (manufactured by DIC Corporation, represented by general formula (1A), R １Ａ and R ２Ａ The structure is a glycidyl group, and is represented by general formula (2), R ３ is a glycidyl group, R ４ A bisphenol A novolac type epoxy resin having a structure in which the terminal hydrogen atom is a methyl group substituted with a glycidyloxy group, softening point 68°C, epoxy equivalent 205 g / eq) ・N-890: “EPICLON (registered trademark)” N-890 (manufactured by DIC Corporation, represented by general formula (1A), R １Ａ and R ２Ａ The structure is a glycidyl group, and is represented by general formula (2), R ３ is a glycidyl group, R ４ A bisphenol A novolac type epoxy resin having a structure in which the terminal hydrogen atom is a methyl group substituted with a glycidyloxy group, softening point 82°C, epoxy equivalent 210 g / eq) ・1050: “EPICLON (registered trademark)” 1050 (manufactured by DIC Corporation, represented by general formula (1B), R １Ｂ and R ２Ｂ Bisphenol A type epoxy resin, which is an epoxy ring-opening adduct of a compound having a structure in which is a hydrogen atom or a glycidyl group, softening point 67°C, epoxy equivalent 475 g / eq) ・3050: “EPICLON (registered trademark)” 3050 (manufactured by DIC Corporation, represented by general formula (1B), R １Ｂ and R ２Ｂ Bisphenol A type epoxy resin, which is an epoxy ring-opening adduct of a compound having a structure in which is a hydrogen atom or a glycidyl group, softening point 95°C, epoxy equivalent 800 g / eq) ・N-660: “EPICLON (registered trademark)” N-660 (manufactured by DIC Corporation, represented by general formula (2), R ３ is a glycidyl group, R ４A cresol novolac type epoxy resin having a structure in which is a methyl group, softening point 65°C, epoxy equivalent 208 g / eq) ・N-770: “EPICLON (registered trademark)” N-770 (manufactured by DIC Corporation, represented by general formula (2), R ３ is a glycidyl group, R ４ ・1032H60: “jER(registered trademark)” 1032H60 (manufactured by Mitsubishi Chemical Corporation, aromatic epoxy resin that does not contain any of the structures of general formula (1A), general formula (1B), and general formula (2), softening point 62°C, epoxy equivalent 168 g / eq) ・1031S: “jER(registered trademark)” 1031S (manufactured by Mitsubishi Chemical Corporation, aromatic epoxy resin that does not contain any of the structures of general formula (1A), general formula (1B), and general formula (2), softening point 92°C, epoxy equivalent 198 g / eq) ・1009F: “jER(registered trademark)” 1009F (manufactured by Mitsubishi Chemical Corporation, represented by general formula (1B), R １Ｂ and R ２Ｂ Bisphenol A type epoxy resin, which is an epoxy ring-opening adduct of a compound having a structure in which is a hydrogen atom or a glycidyl group, softening point 144°C, epoxy equivalent 2,000 g / eq) [Others] ・825: “jER (registered trademark)” 825 (manufactured by Mitsubishi Chemical Corporation, represented by general formula (1A), R １Ａ and R ２Ａ Bisphenol A type epoxy resin having a structure in which the group is a glycidyl group, liquid at room temperature, epoxy equivalent 170 g / eq) ・TMPA: Acrylic monomer manufactured by Kyoeisha Chemical Co., Ltd.

[0108] (Example 1) 61.4 g of the tin particle (A-1) dispersion obtained in Production Example 1, 13.2 g of alkali-soluble resin (B-1) SPCR-10 (37% by mass PGMEA solution), 0.6 g of photopolymerization initiator (C) OXE-04, 1.0 g of TMPA, and 23.8 g of PGMEA were placed in a 100 mL clean bottle and mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (registered trademark) (manufactured by Thinky Co., Ltd.) to obtain 100 g of photosensitive resin composition 1.

[0109] (Example 2) Photosensitive resin composition 2 was obtained in the same manner as in Example 1, except that 13.2 g of alkali-soluble resin (B-1) SPCR-10 (37% by mass PGMEA solution) was replaced with 7.5 g of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1, and 23.8 g of PGMEA was replaced with 29.4 g.

[0110] (Example 3) Photosensitive resin composition 3 was obtained in the same manner as in Example 2, except that 7.5 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed to 6.0 g, 29.4 g of PGMEA was changed to 30.0 g, and 1.0 g of thermosetting resin (D) N-865 was added.

[0111] (Example 4) Photosensitive resin composition 4 was obtained in the same manner as in Example 2, except that 7.5 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed to 4.4 g, 29.4 g of PGMEA was changed to 30.6 g, and 2.0 g of thermosetting resin (D) N-865 was added.

[0112] (Example 5) In a 100 mL clean bottle, 60.3 g of the tin particle (A-1) dispersion obtained in Production Example 1, 4.9 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1, 0.6 g of the photopolymerization initiator (C) OXE-04, 1.0 g of TMPA, 1.0 g of the thermosetting resin (D) N-865, and 25.9 g of PGMEA were added and mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (manufactured by Thinky Co., Ltd.). Then, 6.3 g of the conductive carbon particle dispersion obtained in Production Example 8 was mixed in to obtain 100 g of photosensitive resin composition 5.

[0113] (Example 6) Photosensitive resin composition 6 was obtained in the same manner as in Example 5, except that the amount of dispersion of tin particles (A-1) obtained in Production Example 1 was changed from 60.3 g to 59.0 g, the amount of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed from 4.9 g to 3.9 g, the amount of PGMEA was changed from 25.0 g to 22.1 g, and the amount of conductive carbon particle dispersion obtained in Production Example 8 was changed from 6.3 g to 12.4 g.

[0114] (Example 7) Photosensitive resin composition 7 was obtained in the same manner as in Example 5, except that the amount of tin particle (A-1) dispersion obtained in Production Example 1 was changed from 60.3 g to 56.9 g, the amount of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed from 4.9 g to 2.0 g, the amount of PGMEA was changed from 25.0 g to 14.7 g, and the amount of conductive carbon particle dispersion obtained in Production Example 8 was changed from 6.3 g to 23.8 g.

[0115] Table 1 shows the compositions of the photosensitive resin compositions obtained in Examples 1 to 7.

[0116]

[0117] (Example 8) Photosensitive resin composition 8 was obtained in the same manner as in Example 5, except that 4.9 g of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was replaced with 8.6 g of alkali-soluble resin (B-2) SPCR-199X (37% by mass PGMEA solution), and 25.9 g of PGMEA was changed to 22.2 g.

[0118] (Example 9) A photosensitive resin composition 9 was obtained in the same manner as in Example 8, except that the alkali-soluble resin (B-2) SPCR-199X (a PGMEA solution with a solid content of 37% by mass) was replaced with the alkali-soluble resin (B-1) SPCR-10 (a PGMEA solution with a solid content of 37% by mass).

[0119] (Example 10) A photosensitive resin composition 10 was obtained in the same manner as in Example 5, except that the tin particle (A-1) dispersion obtained in Production Example 1 was replaced with the tin particle (A-2) dispersion obtained in Production Example 2.

[0120] (Example 11) In a 100 mL clean bottle, 40.4 g of the tin particle (A-1) dispersion obtained in Production Example 1, 11.1 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1, 0.6 g of the photopolymerization initiator (C) OXE-04, 1.0 g of TMPA, 1.0 g of the thermosetting resin (D) N-865, and 37.4 g of PGMEA were added and mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (manufactured by Thinky Co., Ltd.). Then, 8.4 g of the conductive carbon particle dispersion obtained in Production Example 8 was mixed in to obtain 100 g of photosensitive resin composition 11.

[0121] (Example 12) A photosensitive resin composition 12 was obtained in the same manner as in Example 11, except that the 40.4 g of tin particle (A-1) dispersion obtained in Production Example 1 was changed to 51.8 g, the 11.1 g of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed to 7.6 g, the 37.4 g of PGMEA was changed to 30.8 g, and the 8.4 g of conductive carbon particle dispersion obtained in Production Example 8 was changed to 7.2 g.

[0122] (Example 13) A photosensitive resin composition 13 was obtained in the same manner as in Example 11, except that the 40.4 g of tin particle (A-1) dispersion obtained in Production Example 1 was changed to 72.0 g, the 11.1 g of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed to 1.2 g, the 37.4 g of PGMEA was changed to 19.1 g, and the 8.4 g of conductive carbon particle dispersion obtained in Production Example 8 was changed to 5.1 g.

[0123] (Example 14) A photosensitive resin composition 14 was obtained in the same manner as in Example 11, except that the 40.4 g of tin particle (A-1) dispersion obtained in Production Example 1 was changed to 73.8 g, the 11.1 g of alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed to 0.7 g, the 37.4 g of PGMEA was changed to 18.1 g, and the 8.4 g of conductive carbon particle dispersion obtained in Production Example 8 was changed to 4.8 g.

[0124] Table 2 shows the compositions of the photosensitive resin compositions obtained in Examples 8 to 14.

[0125]

[0126] (Example 15) 73.2 g of the tin particle (A-1) dispersion obtained in Production Example 1, 6.5 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1, 0.6 g of the photopolymerization initiator (C) OXE-04, 0.4 g of TMPA, 1.6 g of the thermosetting resin (D) N-865, and 22.2 g of PGMEA were placed in a 100 mL clean bottle and mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (manufactured by Thinky Co., Ltd.) to obtain 100 g of photosensitive resin composition 15.

[0127] (Examples 16-17) Photosensitive resin compositions 16-17 were obtained in the same manner as in Example 15, except that the tin particle (A-1) dispersion obtained in Production Example 1 was replaced with tin-silver alloy particles (A-3) to (A-4) obtained in Production Examples 3-4, respectively.

[0128] (Examples 18-26) Photosensitive resin compositions 18-26 were obtained in the same manner as in Example 16, except that N-865, which is a thermosetting resin (D) component, was replaced with the thermosetting resin (D) listed in Table 3.

[0129] (Example 27) A photosensitive resin composition 27 was obtained in the same manner as in Example 15, except that the tin particle (A-1) dispersion obtained in Production Example 1 was replaced with indium particle (A-6) obtained in Production Example 6.

[0130] Table 3 shows the compositions of the photosensitive resin compositions obtained in Examples 15 to 27.

[0131]

[0132] (Comparative Example 1) In a 100 mL clean bottle, 67.2 g of the carbon-coated Ag particle dispersion obtained in Production Example 7, 4.0 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1, 0.6 g of the photopolymerization initiator (C) OXE-04, 1.0 g of TMPA, 1.0 g of the thermosetting resin (D) N-865, and 26.2 g of PGMEA were placed and mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (manufactured by Thinky Co., Ltd.) to obtain 100 g of photosensitive resin composition 28.

[0133] (Comparative Example 2) A photosensitive resin composition 29 was obtained in the same manner as in Comparative Example 1, except that 4.0 g of the alkali-soluble resin (B-3) (65% by mass PGMEA solution) obtained in Synthesis Example 1 was changed to 15.6 g, 26.2 g of PGMEA was changed to 35.6 g, and 67.2 g of carbon-coated Ag particle dispersion was changed to 45.8 g of conductive carbon particle dispersion obtained in Production Example 8.

[0134] (Comparative Example 3) A photosensitive resin composition 30 was obtained in the same manner as in Example 15, except that the tin particle (A-1) dispersion obtained in Production Example 1 was replaced with a tin-silver alloy particle (A-5) dispersion obtained in Production Example 5.

[0135] Table 4 shows the compositions of the photosensitive resin compositions obtained in Comparative Examples 1 to 3.

[0136]

[0137] Tables 5 and 6 show the results of evaluating each example and comparative example using the method described above.

[0138]

[0139]

[0140] 1. Glass substrate 2. ITO electrode 3. Bump pattern 4. Glass chip 5. ITO electrode a. Terminal electrode b. Terminal electrode

Claims

1. A photosensitive resin composition comprising metal particles (A) having a Young's modulus of less than 70 GPa, an alkali-soluble resin (B), and a photosensitive agent (C), wherein the median diameter of the metal particles (A) is 500 nm or less.

2. The photosensitive resin composition according to claim 1, further comprising a thermosetting resin (D) having a softening point of 40°C or higher and less than 150°C.

3. The photosensitive resin composition according to claim 2, wherein the thermosetting resin (D) has a structure represented by the following general formula (1A): In the above general formula (1A), R １Ａ and R ２Ａ Each of these independently represents a C1-C6 alkyl group in which a hydrogen atom or a terminal hydrogen atom is substituted by an epoxy group; however, R １Ａ and R ２Ａ At least one of them is a C1-C6 alkyl group in which the terminal hydrogen atoms are substituted by epoxy groups.

4. The photosensitive resin composition according to claim 3, wherein the thermosetting resin (D) has both the structure represented by the above general formula (1A) and the structure represented by the following general formula (2): In the above general formula (2), R ３ R represents a C1-C6 alkyl group in which the terminal hydrogen atoms are substituted by epoxy groups; ４ This represents a C1-C6 alkyl group in which a hydrogen atom, a methyl group, a methoxymethyl group, an ethoxymethyl group, a hydroxymethyl group, a hydroxyethyl group, or a terminal hydrogen atom is substituted with a glycidyloxy group.

5. The photosensitive resin composition according to claim 1 or 2, wherein the content of the metal particles (A) in the total solid content is 10% by volume or more and 40% by volume or less.

6. The photosensitive resin composition according to claim 1 or 2, wherein the metal particles (A) contain tin.

7. The photosensitive resin composition according to claim 1 or 2, wherein the alkali-soluble resin (B) comprises a novolac-type resin having an ethylenically unsaturated double bond in its side chain.

8. The photosensitive resin composition according to claim 1 or 2, further comprising carbon particles.

9. A conductive adhesive comprising the photosensitive resin composition according to claim 1 or 2.

10. A method for manufacturing a patterned substrate, comprising the steps of forming a layer made of the photosensitive resin composition according to claim 1 or 2 on a substrate, exposing the layer made of the photosensitive resin composition to an image, and developing it with an alkaline developer.

11. An electronic device in which a circuit board and an electronic component are electrically connected by a cured product of the photosensitive resin composition according to claim 1 or 2.

12. A method for manufacturing an electronic device according to claim 11, comprising a connection step of forming a bump pattern between an electrode of a circuit board and an electrode of an electronic component by the method described in claim 10, and heating and / or pressurizing the bump pattern to connect the electrode of the circuit board and the electrode of the electronic component.

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