Photosensitive resin composition and conductive adhesive using the same

Abstract

The present invention provides a resin composition that can suppress short circuits in fine patterns. [Solution] A photosensitive resin composition containing a polymer (A) having a structural unit represented by the following general formula (1), conductive particles (B), and a photopolymerization initiator (C). TIFF2026094708000019.tif49147 (In the above general formula (1), R 1 R represents a methyl group, and n is an integer from 0 to 3. 2 This represents a monovalent organic group having an ethylenically unsaturated double bond. 3 (This indicates a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms.)

Description

[Technical Field]

[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. [Background technology]

[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, for LED chips of 50 μm × 50 μm or less, known as micro-LEDs, fine-pitch mounting is being actively investigated, and the flip-chip method, which minimizes the area of ​​wiring between the chip and the substrate by forming electrodes on the chip surface and directly connecting the electrodes on the substrate to the chip, is preferably used. In the flip-chip method, a conductive paste containing organic components and conductive particles has been proposed as a suitable bonding material for electrically connecting the electrodes on the chip surface and the electrodes on the substrate, 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). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-68144 [Overview of the project] [Problems that the invention aims to solve]

[0004] While fine patterns can be formed using the conductive paste described in Patent Document 1, the increasing miniaturization of electronic devices in recent years has created a demand for even finer patterns. In particular, the smaller the spacing between patterns, the more likely it is that development residue will accumulate between the patterns, leading to short circuits caused by this residue. Therefore, there is a need for a resin composition that can suppress short circuits in fine patterns. [Means for solving the problem]

[0005] To solve the aforementioned problems, the present invention mainly has the following configuration. <1> A photosensitive resin composition containing a polymer (A) having a structural unit represented by the following general formula (1), conductive particles (B), and a photopolymerization initiator (C).

[0006] [ka]

[0007] In the above general formula (1), R 1 R represents a methyl group, and n is an integer from 0 to 3. 2 This represents a monovalent organic group having an ethylenically unsaturated double bond. 3 This represents a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms. <2> The above general formula (1) is expressed by the following general formula (2). <1> The photosensitive resin composition described.

[0008] [ka]

[0009] In the above general formula (2), R 1 R represents a methyl group, and n is an integer from 0 to 3. 3 R represents a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms. 4represents a divalent hydrocarbon group having 1 to 9 carbon atoms. R 5 represents a monovalent group having a hydroxy group and / or a carboxy group. R 6 represents hydrogen or a methyl group. <3>The photosensitive resin composition according to <1> or <2>, wherein the glass transition point of the polymer (A) having the structural unit represented by the general formula (1) is 40°C or higher and 150°C or lower. <4>R in the general formula (1) or general formula (2) 3 has a structure represented by the following general formula (3) or (4), and the photosensitive resin composition according to any one of <1> to <3>.

[0010]

Chemical formula

[0011] <5>The photosensitive resin composition according to any one of <1> to <5>, wherein the conductive particles (B) contain gold, silver, copper and / or carbon. <6>The photosensitive resin composition according to any one of <1> to <5>, further containing a thermosetting resin (D). <7>A conductive adhesive comprising the photosensitive resin composition according to any one of <1> to <6>. <8>A method for manufacturing a patterned substrate, comprising a step of forming a layer made of the photosensitive resin composition according to any one of <1> to <6> on a substrate, a step of exposing the layer made of the photosensitive resin composition in an image pattern, and a step of developing with an alkaline developer. <9>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 any one of <1> to <6>. <10>A method for manufacturing the electronic device according to <9>, 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 according to <8>, and heating and / or pressing the bump pattern to connect the electrode of the circuit board and the electrode of the electronic component.

Advantages of the Invention

[0012] According to the photosensitive resin composition of the present invention, short circuits can be suppressed even in fine patterns. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of the wiring board used in the example. [Figure 2] This is a schematic diagram of the substrate with a bump pattern used in the example. [Figure 3] This is a schematic diagram of the glass chip mounting substrate used in the example. [Modes for carrying out the invention]

[0014] The photosensitive resin composition of the present invention contains a polymer (A) having a structural unit represented by the general formula (1) described later (hereinafter sometimes abbreviated as "polymer (A)"), conductive particles (B), and a photopolymerization initiator (C). Preferably, the photosensitive resin composition of the present invention further contains a thermosetting resin (D). In the photosensitive resin composition of the present invention, polymer (A) functions as a binder resin that maintains the form of the photosensitive resin composition. Furthermore, polymer (A) has a high electron density due to having repeating units derived from phenol in its main chain, and its interaction with conductive particles (B) is enhanced, making it easier for both polymer (A) and conductive particles (B) to be developed and removed by alkaline developer in unexposed areas. Therefore, the phenomenon of conductive particles (B) remaining on the substrate in unexposed areas (development residue) can be suppressed, and short circuits between fine wirings can be suppressed. And, in the structural unit represented by the general formula (1), R 2 The presence of an ethylenically unsaturated double bond allows the exposed area to undergo radical polymerization, becoming insoluble in alkaline developer, and enabling patterning by photolithography. In the photosensitive resin composition of the present invention, the conductive particles (B) have the function of imparting conductivity to the photosensitive resin composition by heat curing or sintering. The photopolymerization initiator (C) has the function of imparting photosensitivity to the photosensitive resin composition. The thermosetting resin (D) has the function of improving the adhesion between the cured product of the photosensitive resin composition and the substrate.

[0015] In the photosensitive resin composition of the present invention, polymer (A) has structural units represented by the following general formula (1). It may also have other structural units. If it has other structural units, polymer (A) may be a block copolymer or a random copolymer. It is preferable that polymer (A) contains 20 mol% or more of the structural units represented by the following general formula (1), which can improve the dispersibility of conductive particles (B).

[0016] [ka]

[0017] In the above general formula (1), R 1 R represents a methyl group, and n is an integer from 0 to 3. 2 This represents a monovalent organic group having an ethylenically unsaturated double bond. 3 This represents a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms.

[0018] From the viewpoint of ease of manufacturing polymer (A), n is preferably 0.

[0019] R 2 It is preferable that the compound has (meth)acryloyl groups. Here, (meth)acryloyl groups are a general term for acryloyl groups and methacryloyl groups. By having (meth)acryloyl groups, solubility in alkaline developers can be further reduced by radical polymerization due to exposure. 2 It is preferable that the material further has a hydroxyl group and / or a carboxyl group. Having a hydroxyl group and / or a carboxyl group further improves the solubility of the unexposed area for alkaline development, thereby further suppressing development residue and thus reducing short circuits. 2Examples include structures in which a branched organic group, linked by a urethane bond, ester bond, or ether bond containing the oxygen atom of phenol, has a (meth)acryloyl group at one end. Preferably, the other end of the branched organic group has a hydroxyl group and / or a carboxyl group.

[0020] Examples of alicyclic hydrocarbon groups include groups derived from cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and tricyclodecane. The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 12. Examples of aromatic hydrocarbon groups include groups derived from benzene, naphthalene, biphenyl, and anthracene. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 to 18. These may have substituents. Examples of substituents include linear or cyclic alkyl and / or alkylene groups having 1 to 12 carbon atoms. When substituents are present, the carbon atoms of the substituents are not included in the aforementioned carbon number. Examples of divalent organic groups having an alicyclic hydrocarbon group and / or aromatic hydrocarbon group include divalent alicyclic hydrocarbon groups and aromatic hydrocarbon groups, and divalent groups having an alkylene group and an alicyclic hydrocarbon group and / or aromatic hydrocarbon group. Examples of these include structures such as cyclohexane, tricyclodecane, benzene, biphenyl, and naphthalene with two methylene groups bonded to them.

[0021] Examples of alkylene groups having 1 to 9 carbon atoms include methylene, ethylene, propylene, and butynyl groups. These may have substituents.

[0022] Among these, R 3 It is preferable that the structure has the structure represented by the following general formula (3) or (4). Having these structures results in a higher electron density, which in turn suppresses development residue and short circuits.

[0023] [ka]

[0024] The structural unit represented by the above general formula (1) is preferably represented by the following general formula (2).

[0025] [ka]

[0026] In the above general formula (2), R 1 R represents a methyl group, and n is an integer from 0 to 3. 3 R represents a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms. 4 R represents a divalent hydrocarbon group with 1 to 9 carbon atoms. 5 R indicates a monovalent group having a hydroxyl group and / or a carboxyl group. 6 This indicates a hydrogen or methyl group.

[0027] R 1 , R 3 and n is R in the general formula (1) above. 1 , R 3 And is the same as n.

[0028] Examples of divalent hydrocarbon groups having 1 to 9 carbon atoms include alkylene groups, alkenyl groups, alkynyl groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. Among these, R 4 From the viewpoint of ease of manufacturing polymer (A), alkylene groups are preferred, and methylene groups are more preferred.

[0029] R 5 R may be a hydroxyl group or a carboxyl group, or a monovalent organic group having a hydroxyl group and / or a carboxyl group. Examples of organic groups include cyclic hydrocarbon groups and groups having ester bonds. Among these, R 5From the viewpoint of further improving solubility in alkaline developer and suppressing development residue and short circuits, monovalent organic groups having a carboxyl group are preferred. Examples of monovalent organic groups having a carboxyl group include groups derived from saturated or unsaturated carboxylic acids in which a linear or cyclic hydrocarbon is bonded via an ester bond. More specifically, groups in which one of the two carboxylic acids in dicarboxylic acid compounds such as maleic acid, phthalic acid, and tetrahydrophthalic acid is R 5 Examples include structures in which carbon atoms directly connected to the atom are ester-bonded.

[0030] The weight-average molecular weight (Mw) of polymer (A) is preferably 2,000 or more, and more preferably 3,000 or more, from the viewpoint of making it easier to coat conductive particles (B) and improving dispersibility. On the other hand, the Mw of polymer (A) is preferably 15,000 or less, and more preferably 10,000 or less, from the viewpoint of improving solubility in alkaline developer, further suppressing development residue, and further suppressing short circuits. Here, Mw refers to the polystyrene equivalent value measured by gel permeation chromatography (GPC). When there are two or more types of polymer (A), Mw refers to the Mw of the two or more types of polymer (A) as a whole.

[0031] The acid value of polymer (A) is preferably 30 mg KOH / g or higher, and more preferably 50 mg KOH / g or higher, from the viewpoint of further improving solubility in alkaline developer and further suppressing development residue and short-circuiting. On the other hand, the acid value of polymer (A) 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 alkaline developer and moderately suppressing development speed. Here, the acid value refers to the weight of potassium hydroxide that reacts with 1 g of polymer (A), and can be determined by titrating 1 g of polymer (A) with an aqueous potassium hydroxide solution. When there are two or more types of polymer (A), the acid value refers to the acid value of the two or more types of polymer (A) as a whole.

[0032] The glass transition temperature (Tg) of polymer (A) is preferably 40°C or higher, and more preferably 90°C or higher, from the viewpoint of suppressing the adhesion of foreign matter due to its tackiness. On the other hand, when the photosensitive resin composition is used as a bump, the Tg of polymer (A) is preferably 150°C or lower, from the viewpoint of making the bump easier to deform at a low temperature of 150°C or lower, thereby facilitating the adhesion of electronic components. Here, the glass transition temperature (Tg) can be measured by the DSC method. When there are two or more types of polymer (A), it is preferable that the Tg of the polymer (A) with the highest content is within the above range, and it is more preferable that all polymers (A) are within the above range.

[0033] Polymer (A) can be synthesized, for example, by (i) reacting epichlorohydrin with the phenolic hydroxyl groups of a resin containing phenolic hydroxyl groups in its main chain, such as a novolac resin, to introduce epoxy groups, and then adding acrylic acid or methacrylic acid to the epoxy groups; or (ii) adding acrylic acid or methacrylic acid to the epoxy groups of a novolac-type epoxy resin. In this case, a catalyst may be used to increase the reaction efficiency and shorten the 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, NC3100, 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, etc. You may use two or more of these.

[0034] After adding acrylic acid by the methods described in (i) or (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 anhydride, tetrahydrophthalic anhydride, maleic acid anhydride, glutaric acid anhydride, succinic acid anhydride, and derivatives thereof.

[0035] In the photosensitive resin composition of the present invention, the content of polymer (A) is preferably 10% by mass or more, and more preferably 25% by mass or more, of the solid content, from the viewpoint of maintaining appropriate viscosity characteristics to improve the processability of the photosensitive resin composition and further suppressing developing residue in finer patterns to further suppress short circuits. On the other hand, from the viewpoint of further reducing the connection resistance between the electrodes of the circuit board and the electrodes of the electronic components, the content of polymer (A) is preferably 80% by mass or less of the solid content.

[0036] In the photosensitive resin composition of the present invention, conductive particles (B) refer to particles having a resistivity of 1 Ω·cm or less. Examples of conductive particles (B) include metals such as silver, gold, copper, platinum, nickel, aluminum, tungsten, molybdenum, chromium, titanium, and palladium, as well as alloys thereof, ITO, tin oxide, antimond-doped tin oxide, and carbon black. Conductive particles (B) can also include insulating particles such as resins and inorganic oxides, or conductive particles having a coating layer of the aforementioned metals or carbon on their surface. Two or more of these particles may be included. Among these particles, gold, silver, and copper particles are preferred from the viewpoint of conductivity. On the other hand, when the photosensitive resin composition is used for conductive adhesive applications, carbon black is preferred as conductive particles (B) from the viewpoint of connectivity.

[0037] The volume-average particle diameter of conductive particles (B) is preferably 0.01 μm or greater from the viewpoint of dispersibility in the photosensitive resin composition. On the other hand, the volume-average particle diameter of conductive particles (B) is preferably 3.0 μm or less, and more preferably 1.0 μm or less, from the viewpoint of forming a finer pattern in photolithography. Here, the volume-average particle diameter of conductive particles (B) can be determined by dynamic light scattering. Specifically, it can be determined by irradiating a dispersion of conductive particles (B) with a concentration of 5 to 30 volume percent with light of a wavelength of 780 nm using a semiconductor laser, measuring the scattered light, and then performing frequency analysis by the FFT-heterodyne method.

[0038] From the viewpoint of improving conductivity, the content of conductive particles (B) in the photosensitive resin composition of the present invention is preferably 10% by volume or more of the solid content of the photosensitive resin composition. On the other hand, from the viewpoint of transmittance of exposure light in the exposure process described later, the content of conductive particles (B) is preferably 50% by volume or less. Here, the content of conductive particles (B) in the photosensitive resin composition can be calculated by applying the photosensitive resin composition to a substrate, drying and removing any liquid components such as solvents, scraping off a portion of the photosensitive resin composition layer, and removing organic components by holding it at 600°C in air for 1 hour using a thermogravimetric analyzer, and determining the weight fraction of conductive particles (B) and the weight fraction of organic components from the percentage of the remaining weight (thermogravimetric analysis residue rate) and the percentage of the reduced weight (thermogravimetric analysis reduction rate), respectively, and calculating using the following formula [1]. Here, the density of the organic component is 1.1 g / cm³. 3 However, if the raw material composition ratio of the photosensitive resin composition is known, it can be calculated from that composition ratio.

[0039]

number

[0040] In the photosensitive resin composition of the present invention, examples of the photopolymerization initiator (C) 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. Among these, oxime compounds that have high sensitivity to a common exposure wavelength of 365 nm are preferred.

[0041] In the photosensitive resin composition of the present invention, the content of the photopolymerization initiator (C) is preferably 1% by mass or more in the solid content, from the viewpoint of increasing the curing density of the exposed area and forming a finer pattern in the exposure process described later. On the other hand, the content of the photopolymerization initiator (C) is preferably 30% by mass or less in the solid content, from the viewpoint of suppressing excessive light absorption in the surface layer and forming a finer pattern in the exposure process.

[0042] In the photosensitive resin composition of the present invention, examples of thermosetting resin (D) include phenolic resin, epoxy resin, melamine resin, urea resin, and alkyd resin. However, those having a structure represented by general formula (1) shall be classified as polymer (A). Two or more of these may be included. Among these, epoxy resin is preferred because the thermosetting reaction with polymer (A) proceeds easily, and the adhesion between the cured product of the photosensitive resin composition and the substrate can be improved.

[0043] In the photosensitive resin composition of the present invention, the content of the thermosetting resin (D) is preferably 1% by mass or more in the solid content, from the viewpoint of further improving adhesion to the substrate. On the other hand, the content of the thermosetting resin (D) is preferably 30% by mass or less in the solid content, from the viewpoint of smoothly advancing the photocuring reaction in the exposure process described later, increasing the crosslinking density, and forming a finer pattern.

[0044] The photosensitive resin composition in the present invention may further contain photopolymerizable compounds other than polymer (A). A photopolymerizable compound is a compound having a (meth)acryloyl group and / or a maleimide skeleton. Examples of photopolymerizable compounds include difunctional (meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, tripropylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, ethoxylated (4) bisphenol A di(meth)acrylate, ethoxylated (10) bisphenol A di(meth)acrylate, (meth)acrylic acid adducts of ethylene glycol diglycidyl ether, and (meth)acrylic acid adducts of neopentyl glycol diglycidyl ether. Trifunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxytri(meth)acrylate, glycerin propoxytri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Examples include tetrafunctional (meth)acrylates such as “EBECRYL”® 204, “EBECRYL”® 210, “EBECRYL”® 220, “EBECRYL”® 264, “EBECRYL”® 265, and “EBECRYL”® 284 manufactured by Daicel Ornex, as well as urethane-bonded (meth)acrylates such as CN972, CN975, and CN978 manufactured by Sartomer, and maleimide compounds such as N-phenylmaleimide. Two or more of these may be included.

[0045] In the photosensitive resin composition of the present invention, the content of the photopolymerizable compound is preferably 1% by mass or more in the solid content, from the viewpoint of increasing the curing density of the exposed area and forming a finer pattern in the exposure process described later. On the other hand, the content of the photopolymerizable compound is preferably 30% by mass or less in the solid content, from the viewpoint of suppressing excessive light absorption in the surface layer and forming a finer pattern in the exposure process.

[0046] The photosensitive resin composition of the present invention preferably further contains 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, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, and dipropylene glycol monomethyl ether. Two or more of these may be included. Among these, solvents with a boiling point of 120°C or higher are preferred, as they can suppress variations in film thickness in the photosensitive resin composition layer formation process described later.

[0047] 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.

[0048] The photosensitive resin composition of the present invention can be manufactured by mixing the above-mentioned components (A) to (D) and, if necessary, photopolymerizable compounds, solvents, and other additives. Examples of mixing equipment include dispersers and kneaders such as three-roller mills, ball mills, and planetary ball mills.

[0049] The photosensitive resin composition of the present invention exhibits conductivity upon heat curing or firing, 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.

[0050] The photosensitive conductive adhesive of the present invention comprises the aforementioned photosensitive resin composition.

[0051] <Manufacturing method for patterned substrates> Next, the method for manufacturing a patterned substrate of the present invention will be described. The method for manufacturing a patterned substrate of 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).

[0052] In the method for manufacturing a patterned substrate of the present invention, it is preferable to have a step of heat-curing the obtained pattern (hereinafter sometimes abbreviated as a curing step) or a firing step (hereinafter sometimes abbreviated as a firing step) after the developing step. Either the curing step or the firing step can be selected according to the composition of the photosensitive resin composition, the heat resistance temperature of the substrate, and the desired characteristics.

[0053] First, the process of forming the photosensitive resin composition layer will be described. One method involves applying the photosensitive resin composition of the present invention onto a substrate to form a coating film, and if the photosensitive resin composition contains a solvent, removing the solvent by drying to form a photosensitive resin composition layer.

[0054] 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.

[0055] 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.

[0056] The thickness of the resulting coating film can be appropriately determined from the desired thickness of the photosensitive resin composition layer and the total solid content concentration of the photosensitive resin composition.

[0057] 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.

[0058] 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.

[0059] Next, the exposure process will be described. The image may be exposed through an arbitrary pattern-forming mask, or it may be exposed 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.

[0060] Next, the development process will be described. The material is developed using an alkaline developer to dissolve and remove unexposed areas and obtain the desired pattern. Examples of alkaline developers include strong alkaline aqueous solutions such as TMAH, 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 weight or more, from the viewpoint of suppressing development time fluctuations due to carbonates produced by reaction with carbon dioxide in the air.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] If the photosensitive resin composition constituting the resulting pattern exhibits tackiness upon thermocompression bonding, it can be used as an adhesive for bonding electronic components and the like to a substrate. Examples of thermocompression bonding equipment include heat-pressure bonding tools for flip-chip bonders and vacuum diaphragm laminators.

[0065] Next, the curing process will be explained. The curing process can improve conductivity due to volume shrinkage caused by 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 polymer (A) and further improving adhesion, a heating temperature of 280°C or lower is preferred.

[0066] 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.

[0067] Next, the firing process will be explained. The firing process can improve conductivity through volume shrinkage. From the viewpoint of sufficiently advancing the thermal decomposition of organic components and the sintering of conductive particles (B) 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 over-sintering of conductive particles (B), a firing temperature of 1,000°C or lower is preferred.

[0068] 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 apparatus include box furnaces and firing furnaces. The firing conditions can be appropriately selected according to the type of conductive particles (B) and the desired properties.

[0069] <Electronic devices and their manufacturing methods> The electronic device of the present invention is configured such that a circuit board and electronic components are 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.

[0070] The electronic device of the present invention can be manufactured, for example, by a method that includes a connection step in which a bump pattern formed by the photosensitive resin composition layer formation step, exposure step, and development step in the above-mentioned method for manufacturing a patterned substrate is heated and / or pressurized to connect the electrodes of the circuit board and the electrodes of the electronic component between the electrodes of the circuit board and the electrodes of the electronic component. [Examples]

[0071] The present invention will be described below with reference to examples. The embodiments of the present invention are not limited to these examples.

[0072] The evaluation method for each example is as follows.

[0073] <Short between bumps> As shown in Figure 1, 75 mm square wiring boards were prepared, each with ITO wiring 2 formed in pairs at intervals of 3 μm, 5 μm, and 7 μm on a glass substrate 1. The ITO wiring 2 has terminal electrodes a and b on a portion of it. The photosensitive resin compositions obtained in each example and comparative example were coated over the entire surface of these wiring boards to a dry film thickness of 1.5 μm. The boards were then dried in a drying oven at 100°C for 10 minutes to form a 1.5 μm thick photosensitive resin composition layer. For the obtained photosensitive resin composition layer, as shown in Figure 2, a photomask with a square pattern of 10 μm × 10 μm aperture was placed on the ITO wiring 2 so that square bump patterns 3 were positioned at intervals of 3 μm, 5 μm, and 7 μm. An exposure apparatus (PEM-6M; manufactured by Union Optical Co., Ltd.) with an ultra-high pressure mercury lamp was used to expose the 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 wt% TMAH aqueous solution, rinsed with ultrapure water to form a bump pattern, 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 substrate has a bump pattern 3 on the ITO wiring 2.

[0074] Next, a 50 mm square glass chip 4 was placed on the bump pattern 3 so as to be positioned between terminal electrodes a and b, and mounted using a bonder FC-3000 (Toray Engineering Co., Ltd.) under the conditions of a temperature of 130°C, a pressurizing pressure of 1 MPa, and a pressurizing time of 10 seconds to fabricate a glass chip mounting substrate. Figure 3 shows a schematic plan view (a) and a schematic cross-sectional view (b) of the obtained glass chip mounting substrate. The glass chip 4 is located on the bump pattern 3 between terminal electrodes a and b of the ITO wiring 2.

[0075] The resulting glass chip-mounted substrate was heated in a hot air oven at 230°C for 30 minutes. Then, terminal electrodes a and b were connected with a tester, and the resistance between the terminal electrodes was measured. If the resistance value exceeded MΩ, it was determined that no short circuit had occurred between the bumps.

[0076] <Bump deformation evaluation> A substrate with a bump pattern, as shown in Figure 2, was fabricated in the same manner as the evaluation of <short circuits between wiring> described above. Using a digital microscope VHX-7000 (manufactured by Keyence Corporation), the diagonal dimensions of randomly selected square bump patterns were measured and defined as the pre-mount dimensions. Subsequently, a glass chip mounted substrate, as shown in Figure 3, was fabricated in the same manner as the evaluation of <short circuits between bumps> described above, except that the pressure was set to two conditions: 5 MPa and 2 MPa. After that, the diagonal dimensions of the bumps whose pre-mount dimensions were measured were measured through the glass chip and defined as the post-mount dimensions. The rate of change of bump dimensions ((post-mount dimensions / pre-mount dimensions) × 100 (%)) was calculated from the ratio of the post-mount dimensions to the pre-mount dimensions. A larger rate of change of bump dimensions was judged to indicate better mountability.

[0077] The materials used in the examples and comparative examples are as follows:

[0078] [Polymer (A)] (Synthesis Example 1: Polymer (A-1)) In a reaction vessel equipped with a stirrer, condenser, thermometer, and gas inlet, 50 g of WR-104 (DIC Corporation), a propylene glycol monomethyl ether monoacetate (PGMEA) solution of phenol novolac resin with a solid content of 40% by weight, was added. Subsequently, 18.0 g of 1,1-(bisacryloyloxymethyl)ethyl isocyanate "Karenz" (registered trademark) BEI (manufactured by Resona Corporation) was added. 0.2 g of dibutyltin(IV) dilaurate was added as a catalyst, and the polymerization reaction was carried out under an air atmosphere by stirring at 80°C for 8 hours to obtain a PGMEA solution (solid content 55.9% by weight) of polymer (A-1) having structural units represented by the following structural formula (5). The solid content acid value of the obtained polymer (A-1) was 1 mg KOH / g, and the glass transition temperature measured by DSC was 172°C. The weight-average molecular weight Mw in polystyrene equivalent, measured by GPC, was 8,900.

[0079] [ka]

[0080] (Synthesis Example 2: Polymer (A-2)) In a reaction vessel equipped with a stirrer, condenser, thermometer, and gas inlet, 199.0 g of novolac-type epoxy resin EOCN-1020 (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 199 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 weight. The mixture was heated and stirred at 100°C for 24 hours to obtain a precursor solution of polymer (A-2). 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 weight. The mixture was heated and stirred at 100°C for 3 hours to obtain a PGMEA solution of polymer (A-2) having the structure represented by the following structural formula (6). The solid content acid value of the obtained polymer (A-2) was 87 mg KOH / g, and the glass transition temperature was 152°C. The weight-average molecular weight (Mw) in terms of polystyrene was 3,300.

[0081] [ka]

[0082] (Synthesis Example 3: Polymer (A-3)) A PGMEA solution of polymer (A-3) having the structure shown in the following structural formula (7) was obtained in the same manner as in Synthesis Example 2, except that 169.0 g of EPPN-501H (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 169 g / eq) was used instead of 199.0 g of EOCN-1020 as the novolac-type epoxy resin. The obtained polymer (A-3) had a solid content acid value of 93 mg KOH / g and a glass transition temperature of 162°C. The weight-average molecular weight Mw on a polystyrene basis was 4,700.

[0083] [ka]

[0084] (Synthesis Example 4: Polymer (A-4)) A PGMEA solution of polymer (A-4) having the structure shown in the following structural formula (8) was obtained in the same manner as in Synthesis Example 1, except that 236.0 g of NC-2000-L (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 236 g / eq) was used instead of 199.0 g of EOCN-1020 as the novolac-type epoxy resin. The obtained polymer (A-4) had a solid content acid value of 71 mg KOH / g and a glass transition temperature of 130°C. The weight-average molecular weight Mw on a polystyrene basis was 4,100.

[0085] [ka]

[0086] (Synthesis Example 5: Polymer (A-5)) A PGMEA solution of polymer (A-4) having the structure shown in the following structural formula (9) was obtained in the same manner as in Synthesis Example 1, except that 288.0 g of NC-3000H (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 288 g / eq) was used instead of 199.0 g of EOCN-1020 as the novolac-type epoxy resin. The solid content acid value of the obtained polymer (A-4) was 62 mg KOH / g at 112°C. The weight-average molecular weight Mw in polystyrene terms, measured by GPC, was 3,600.

[0087] [ka]

[0088] [Conductive particles (B)] • Carbon black particles: Carbon black particles manufactured by Cabot (volume average particle size 50 nm, specific gravity 1.9 g / cm³) 3 , specific resistance 1.7mΩ cm) • Carbon-coated Ag particles: Carbon-coated Ag particles manufactured by Nisshin Engineering Co., Ltd. (average thickness of surface carbon coating layer: 1 nm, volume average particle diameter: 40 nm, specific gravity: 9.5 g / cm³) 3 , resistivity 3.2μΩ·cm).

[0089] (Manufacturing example 1: Carbon black dispersion) 15.0 g of the above-mentioned Cabot carbon black particles, 4.0 g of the dispersant "DISPERBYK" (registered trademark) 2200 (manufactured by Bic Chemie), and 81.0 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 atomizer "Nanomizer" (registered trademark) (Nanomizer Co., Ltd.) to obtain a carbon black dispersion with a volume-average particle diameter of 0.15 μm, a solid content of 19% by weight, and a conductive particle content of 15.0% by weight.

[0090] (Manufacturing example 2: Carbon-coated Ag particle dispersion) 15.0 g of carbon-coated Ag particles manufactured by Nisshin Engineering Co., Ltd., 1.0 g of the dispersant "DISPERBYK" (registered trademark) 2200 (manufactured by Bic Chemie Co., Ltd.), and 84.0 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" (registered trademark) (Nanomizer Co., Ltd.) to obtain a carbon-coated Ag dispersion with a volume-average particle diameter of 0.2 μm, a solid content of 16% by weight, and a conductive particle content of 15.0% by weight.

[0091] [Photopolymerization initiator (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 (phenol novolac type epoxy resin manufactured by DIC Corporation) [Photopolymerizable compound] TMPA: Acrylic monomer manufactured by Kyoeisha Chemical Co., Ltd. [others] • "SPCR-10": Alkali-soluble acrylic resin manufactured by Resonaq Corporation (PGMEA solution with an acid value of 100 mg KOH / g and a solid content of 37% by weight).

[0092] (Example 1) In a 100 mL clean bottle, 17.8 g of the PGMEA solution of polymer (A-1) obtained in Synthesis Example 1, 1.0 g of photopolymerization initiator (C) OXE-04, 2.0 g of thermosetting resin (D) N-865, 2.0 g of TMPA, and 50.5 g of PGMEA were added. The mixture was then mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (registered trademark) (manufactured by Thinky Co., Ltd.) to obtain 73.3 g of an organic component solution.

[0093] To this solution, 26.7 g of the carbon black dispersion obtained in Production Example 1 was added as conductive particles (B) and mixed to obtain 100.0 g of a photosensitive resin composition (conductive particle ratio in solid content: 12.2 vol%). Table 1 shows the composition of the photosensitive resin composition.

[0094] (Example 2) In a 100 mL clean bottle, 15.3 g of the PGMEA solution of polymer (A-2) obtained in Synthesis Example 2, 1.0 g of photopolymerization initiator (C) OXE-04, 2.0 g of thermosetting resin (D) N-865, 2.0 g of TMPA, and 53.0 g of PGMEA were added. The mixture was then mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (registered trademark) (manufactured by Thinky Co., Ltd.) to obtain 73.3 g of an organic component solution.

[0095] To this solution, 26.7 g of the carbon black dispersion obtained in Production Example 1 was added as conductive particles (B) and mixed to obtain 100.0 g of a photosensitive resin composition (conductive particle ratio in solid content: 12.2 vol%). Table 1 shows the composition of the photosensitive resin composition.

[0096] Table 2 shows the results of evaluating the obtained photosensitive resin composition using the method described above.

[0097] (Examples 3-5) A photosensitive resin composition was prepared and evaluated in the same manner as in Example 1, except that the PGMEA solution of polymer (A-2) was replaced with the PGMEA solutions of polymers (A-3) to (A-5) obtained by synthesis examples 3 to 5. The composition of the photosensitive resin composition is shown in Table 1, and the evaluation results are shown in Table 2.

[0098] (Example 6) A 100.0 g photosensitive resin composition was obtained in the same manner as in Example 5, except that the amount of PGMEA solution of polymer (A-5) was changed to 11.4 g, the amount of PGMEA to 43.6 g, and the amount of carbon black dispersion to 40.0 g. Table 1 shows the composition of the photosensitive resin composition.

[0099] Table 2 shows the results of evaluating the obtained photosensitive resin composition using the method described above.

[0100] (Example 7) A 100.0 g photosensitive resin composition was prepared and evaluated in the same manner as in Example 5, except that the amount of PGMEA solution for polymer (A-5) was changed to 7.5 g, the amount of PGMEA to 34.2 g, and the amount of carbon black dispersion to 53.3 g. The composition of the photosensitive resin composition is shown in Table 1, and the evaluation results are shown in Table 2.

[0101] (Example 8) In a 100 mL clean bottle, 9.6 g of the PGMEA solution of polymer (A-5) obtained in Synthesis Example 5, 1.0 g of photopolymerization initiator (C) OXE-04, 1.0 g of thermosetting resin (D) N-865, and 15.1 g of PGMEA were added. The mixture was then mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (registered trademark) (manufactured by Thinky Co., Ltd.) to obtain 26.7 g of organic component solution.

[0102] To this solution, 73.3 g of the carbon black dispersion obtained in Production Example 2 was added as conductive particles (B) and mixed to obtain 100.0 g of a photosensitive resin composition. Table 1 shows the composition of the photosensitive resin composition.

[0103] Table 2 shows the results of evaluating the obtained photosensitive resin composition using the method described above.

[0104] (Comparative Example 1) In a 100 mL clean bottle, 26.8 g of SPCR-10, 1.0 g of photopolymerization initiator (C) OXE-04, 2.0 g of thermosetting resin (D) N-865, 2.0 g of TMPA, and 41.5 g of PGMEA were added and mixed using a rotation-revolution vacuum mixer ARE-310 "Awatori Rentaro" (registered trademark) (manufactured by Thinky Co., Ltd.) to obtain 73.3 g of organic component solution.

[0105] To this solution, 26.7 g of the carbon black dispersion obtained in Production Example 1 was added as conductive particles (B) and mixed to obtain a photosensitive resin composition. Table 1 shows the composition of the photosensitive resin composition.

[0106] Table 2 shows the results of evaluating the obtained photosensitive resin composition using the method described above.

[0107] (Comparative Example 2) A photosensitive resin composition was obtained in the same manner as in Comparative Example 1, except that the amount of SPCR-10 was changed to 20.0 g, the amount of PGMEA to 35.0 g, and the amount of carbon black dispersion to 40.0 g. Table 1 shows the composition of the photosensitive resin composition.

[0108] Table 2 shows the results of evaluating the obtained photosensitive resin composition using the method described above.

[0109] (Comparative Example 3) A photosensitive resin composition was obtained in the same manner as in Comparative Example 1, except that the amount of SPCR-10 was changed to 13.2 g, the amount of PGMEA to 28.5 g, and the amount of carbon dispersion to 53.3 g. Table 1 shows the composition of the photosensitive resin composition.

[0110] Table 2 shows the results of evaluating the obtained photosensitive resin composition using the method described above.

[0111] [Table 1]

[0112] [Table 2] [Explanation of symbols]

[0113] 1. Glass substrate 2 ITO wiring 3 Bump Patterns 4 glass chips a Terminal electrode b Terminal electrode

Claims

1. A photosensitive resin composition containing a polymer (A) having a structural unit represented by the following general formula (1), conductive particles (B), and a photopolymerization initiator (C). 【Chemistry 1】 (In the above general formula (1), R １ R represents a methyl group, and n is an integer between 0 and 3. ２ R represents a monovalent organic group having an ethylenically unsaturated double bond. ３ (This represents a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms.)

2. The photosensitive resin composition according to claim 1, wherein the general formula (1) is represented by the following general formula (2). 【Chemistry 2】 (In the above general formula (2), R １ R represents a methyl group, and n is an integer between 0 and 3. ３ R represents a divalent organic group having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, or an alkylene group having 1 to 9 carbon atoms. ４ R represents a divalent hydrocarbon group having 1 to 9 carbon atoms. ５ R indicates a monovalent group having a hydroxyl group and / or a carboxyl group. ６ (This indicates a hydrogen or methyl group.)

3. The photosensitive resin composition according to claim 1 or 2, wherein the glass transition temperature of the polymer (A) having the structural unit represented by the general formula (1) is 40°C or higher and 150°C or lower.

4. R in the general formula (1) or general formula (2) ３ The photosensitive resin composition according to claim 1 or 2, wherein has a structure represented by the following general formula (3) or (4). 【Transformation 3】

5. The photosensitive resin composition according to claim 1 or 2, wherein the conductive particles (B) contain gold, silver, copper, and / or carbon.

6. The photosensitive resin composition according to claim 1 or 2, further comprising a thermosetting resin (D).

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

8. 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.

9. 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.

10. A method for manufacturing an electronic device according to claim 9, 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 8, 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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