Photosensitive thermosetting resin composition, dry film, cured product, and electronic component

Abstract

The present invention provides a photosensitive thermosetting resin composition capable of forming a solder resist film having excellent surface curability and heat resistance and high reflectivity at a low exposure amount. A photosensitive thermosetting resin composition comprising a carboxyl group-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin. The photopolymerization initiator comprises an oxime ester-based photopolymerization initiator and a titanocene-based photopolymerization initiator, and the thermosetting resin comprises an epoxy resin. The cured product of the photosensitive thermosetting resin composition after thermosetting has an L * a * b * b in the color system * value of 2.0 or less and a reflectivity of 85% or more under a wavelength of 450 nm.

Description

Technical Field

[0001] This invention relates to photosensitive thermosetting resin compositions, dry films, cured products, and electronic components. Background Technology

[0002] Light-emitting devices in which light-emitting diodes (hereinafter sometimes simply referred to as LEDs) are mounted on printed circuit boards are known. To efficiently utilize the light from the LEDs mounted on the printed circuit board, a highly reflective white solder resist film is sometimes formed on the printed circuit board (e.g., see International Publication No. 2008 / 050768, Japanese Patent Application Publication No. 2008-134621, Japanese Patent Application Publication No. 2011-017010, and International Publication No. 2012 / 141124). Furthermore, Japanese Patent Application Publication No. 2013-210443 discloses a photocurable and thermocurable resin composition containing a photopolymerization initiator that does not contain phosphorus atoms in its molecular structure. Summary of the Invention

[0003] The problem that the invention aims to solve

[0004] One objective of this invention is to provide a photosensitive thermosetting resin composition capable of forming a solder resist film with excellent surface curability, heat resistance, and high reflectivity even with low exposure.

[0005] Methods for solving problems

[0006] The present invention includes the following solutions.

[0007] [1] A photosensitive thermosetting resin composition comprising a carboxyl-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin, wherein,

[0008] The photopolymerization initiator includes oxime ester-based photopolymerization initiators and titanium cadmium-based photopolymerization initiators.

[0009] The thermosetting resin includes epoxy resin.

[0010] L of the cured product after thermosetting of the photosensitive thermosetting resin composition * a * b * b in the color system * The reflectivity is above 85% under the condition that the value is below 2.0 and the wavelength is 450nm.

[0011] [2] The photosensitive thermosetting resin composition as described in [1], wherein the mass ratio of the oxime ester photoinitiator to the dicene-based photoinitiator is in the range of 1:10 to 10:1 for the photopolymerization initiator.

[0012] [3] A dry film, wherein the dry film has a resin layer obtained by coating a first film with the photosensitive thermosetting resin composition described in [1] or [2] and drying it.

[0013] [4] A cured product, wherein the cured product is formed by curing the photosensitive thermosetting resin composition described in [1] or [2].

[0014] [5] An electronic component, wherein the electronic component comprises the cured material described in [4].

[0015] The effects of the invention

[0016] According to one aspect of the present invention, a photosensitive thermosetting resin composition is provided that can form a solder resist film with excellent surface curability, heat resistance and high reflectivity even with low exposure. Detailed Implementation

[0017] In this specification, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from others, as long as the intended purpose of the process can be achieved. Furthermore, when a plurality of substances equivalent to each component are present in the composition, unless otherwise specified, the content of each component in the composition refers to the total amount of the plurality of substances present in the composition. Additionally, solid components refer to substances after the removal of volatile components (e.g., organic solvents). Furthermore, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined using numerical values ​​as examples of numerical ranges. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below exemplify photosensitive thermosetting resin compositions, dry films, cured products, and electronic components used to embody the technical concept of the present invention, and the present invention is not limited to the photosensitive thermosetting resin compositions, dry films, cured products, and electronic components shown below.

[0018] Photosensitive thermosetting resin composition

[0019] The photosensitive thermosetting resin composition comprises a carboxyl-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin. The photopolymerization initiator includes at least an oxime ester-based photopolymerization initiator and a titanium cadmium-based photopolymerization initiator. The thermosetting resin includes at least an epoxy resin. The cured product L after thermosetting of the photosensitive thermosetting resin composition... * a * b * b in the color system * The reflectivity is above 85% under the condition that the value is below 2.0 and the wavelength is 450nm.

[0020] The photosensitive thermosetting resin composition includes a photopolymerization initiator with a specific structure, which acts as a photopolymerization initiator, thereby enabling the formation of a cured product with excellent surface curing properties, heat resistance, and high reflectivity even with low exposure. Furthermore, it can suppress discoloration of the cured product caused by heat, light, etc. Moreover, it can form a latent image with high sensitivity and excellent resolution. This can be attributed, for example, to the synergistic effect of oxime ester-based photopolymerization initiators and titanium cadmium-based photopolymerization initiators. It should be noted that the low exposure amount in this invention specifically refers to 600 mJ / cm². 2 the following.

[0021] Carboxyl-containing resins

[0022] Carboxyl-containing resins are any resins containing carboxyl groups within their molecules; they may or may not have photosensitive functional groups. By including carboxyl-containing resins in photosensitive thermosetting resin compositions, the photocured product obtained by irradiation with active energy rays can be endowed with alkali-developable properties. For carboxyl-containing resins, from the perspectives of photocurability and developability, it is preferable that they have olefinic unsaturated double bonds as photosensitive functional groups in their molecules. The olefinic unsaturated double bonds in the molecule can be derived from acrylic acid, methacrylic acid, or their derivatives. The photosensitive thermosetting resin composition can contain only one type of carboxyl-containing resin, or it can contain two or more types in combination. It should be noted that when the photosensitive thermosetting resin composition contains only a carboxyl-containing resin without olefinic unsaturated double bonds, photocurability can be achieved by using compounds having multiple olefinic unsaturated groups in their molecules, i.e., photopolymerizable monomers, as described below. Specific examples of carboxyl-containing resins include compounds described below (which can be either oligomers or polymers). It should be noted that, hereinafter, "(meth)acrylate" refers to a collective term encompassing acrylates, methacrylates, and mixtures thereof, as do other similar expressions.

[0023] (1) A carboxyl-containing resin obtained by copolymerizing unsaturated carboxylic acids such as (meth)acrylic acid with compounds containing unsaturated groups such as styrene, α-methylstyrene, lower alkyl (meth)acrylates, and isobutylene.

[0024] (2) A carboxyl-containing urethane resin produced by the addition polymerization reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl-containing diols such as dimethylolpropionic acid and dimethylolbutyric acid, as well as dihydroxy compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A epoxy alkane adduct diols, and compounds with phenolic hydroxyl and alcoholic hydroxyl groups.

[0025] (3) Photosensitive urethane resin containing carboxyl groups produced by the addition polymerization of diisocyanate with bifunctional epoxy resins such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, biphenol type epoxy resin, etc., and monocarboxylic acid compounds such as (meth)acrylic acid with olefinic unsaturated double bonds, partially modified acid anhydride compounds, carboxyl-containing diol compounds, and dihydroxy compounds.

[0026] (4) In the synthesis of the resin in (2) or (3) above, a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as (meth)acrylic acid hydroxyalkyl ester, is added to the end (meth)acryloyl group to form a carboxyl-containing photosensitive urethane resin.

[0027] (5) A carboxyl-containing photosensitive urethane resin is obtained by adding equimolar reactants of isophorone diisocyanate and pentaerythritol triacrylate to the resin synthesis of (2) or (3) above and performing terminal (meth)acrylylation of compounds having one isocyanate group and one or more (meth)acryloyl groups in the molecule.

[0028] (6) A carboxyl-containing photosensitive resin is formed by reacting a difunctional or more multifunctional (solid) epoxy resin with (meth)acrylic acid to add a dicarboxylic acid anhydride to a hydroxyl group present in the side chain.

[0029] (7) A carboxyl-containing photosensitive resin is formed by reacting a multifunctional epoxy resin obtained by epoxidizing the hydroxyl groups of a bifunctional (solid) epoxy resin with (meth)acrylic acid and adding a dicarboxylic acid anhydride to the generated hydroxyl groups.

[0030] (8) A carboxyl-containing polyester resin is formed by reacting adipic acid, phthalic acid, hexahydrophthalic acid and other dicarboxylic acids with adipic acid, phthalic acid and hexahydrophthalic acid, etc., and adding phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride and other dicarboxylic anhydride to the generated primary hydroxyl group.

[0031] (9) An epoxy compound having multiple epoxy groups in one molecule is reacted with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenylethanol, and a monocarboxylic acid containing unsaturated groups, such as (meth)acrylic acid, so that the alcoholic hydroxyl group of the reaction product reacts with maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, adipic acid, etc., to obtain a carboxyl-containing photosensitive resin.

[0032] (10) A photosensitive resin containing carboxyl groups is obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with ethylene oxide, propylene oxide and other epoxides. The reaction product is then reacted with a monocarboxylic acid containing unsaturated groups, and the reaction product is then reacted with a polyacid anhydride.

[0033] (11) A photosensitive resin containing carboxyl groups is obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with cyclic carbonate compounds such as ethylene carbonate and propylene carbonate, and then reacting the resulting product with a monocarboxylic acid containing unsaturated groups, and then reacting the resulting product with a polyacid anhydride.

[0034] (12) A carboxyl-containing photosensitive resin formed by further adding a compound having an epoxy group and one or more (meth)acryloyl groups to the resins of (1) to (11) above.

[0035] From the viewpoints of suppressing warping of cured products, as well as heat resistance and reflectivity, it is preferred that the carboxyl-containing resin is a carboxyl-containing urethane resin produced by the addition polymerization reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl-containing diol compounds such as dimethylolpropionic acid and dimethylolbutyric acid, as well as dihydroxy compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A epoxy alkane adduct diols, and compounds having phenolic hydroxyl and alcoholic hydroxyl groups. The carboxyl-containing photosensitive urethane resin includes at least one of the following: (meth)acryloyl esters and other compounds having one or more (meth)acryloyl groups in their molecules are added during the synthesis of the urethane resin to achieve end (meth)acryloylation. More preferably, the carboxyl-containing resin is a carboxyl-containing urethane resin produced by the addition polymerization reaction of aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, etc., with carboxyl-containing diol compounds and dihydroxy compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, etc., and may include at least one of the carboxyl-containing photosensitive urethane resins obtained by adding (meth)acrylate hydroxyalkyl esters and terminal (meth)acrylylation during the synthesis of the urethane resin.

[0036] Furthermore, from the viewpoint of the heat resistance and reflectivity of the cured product, it is also preferable that the carboxyl-containing resin includes at least one of the following: a photosensitive resin containing carboxyl groups obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an epoxide such as ethylene oxide or propylene oxide, and reacting the resulting product with a monocarboxylic acid containing an unsaturated group, and then reacting the resulting product with a polyacid anhydride.

[0037] The acid value of the carboxyl-containing resin can be, for example, 10 mg KOH / g or more and 150 mg KOH / g or less, preferably 30 mg KOH / g or more and 120 mg KOH / g or less. With an acid value of 10 mg KOH / g or more, the photosensitive resin composition exhibits good alkaline developability. Furthermore, with an acid value of 150 mg KOH / g or less, it is easy to draw good resist patterns. It should be noted that the acid value of the carboxyl-containing resin is a value determined according to JIS K0070:1992.

[0038] The weight-average molecular weight of carboxyl-containing resins varies depending on the resin skeleton, typically being 2000 or more and 150,000 or less, preferably 5000 or more and 100,000 or less. A weight-average molecular weight of 2000 or more improves surface drying properties and resolution. Furthermore, a weight-average molecular weight of 150,000 or less improves the developability and storage stability of the photosensitive resin composition. Here, the weight-average molecular weight is a value converted from polystyrene determined by gel permeation chromatography.

[0039] Based on solid content conversion, the content of carboxyl-containing resin in the photosensitive thermosetting resin composition is, for example, 5% by mass or more and 40% by mass or less, preferably 10% by mass or more and 35% by mass or less. By having a carboxyl-containing resin content of 5% by mass or more, the coating film strength can be improved. Furthermore, by having a carboxyl-containing resin content of 40% by mass or less, the photosensitive resin composition has appropriate viscosity and improved processability.

[0040] Photosensitive compounds

[0041] The photosensitive thermosetting resin composition may also contain at least one photosensitive compound that does not have a carboxyl group. Examples of photosensitive compounds include those having olefinic unsaturated bonds. The photosensitive compound may also be a compound having a plurality of olefinic unsaturated bonds.

[0042] Specifically, compounds containing olefinic unsaturated bonds include: hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; acrylamides such as N,N-dimethylmethacrylamide, N-hydroxymethyl methacrylamide, and N,N-dimethylaminopropyl methacrylamide; aminoalkyl methacrylates such as N,N-dimethylaminoethyl methacrylate and N,N-dimethylaminopropyl methacrylate; and dimethacrylates derived from alkylene glycols such as ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol. Poly(meth)acrylates, including polyols such as acetal glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, trihydroxyethyl isocyanurate, etc., or their ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts; poly(meth)acrylates containing aromatic groups derived from bisphenol A, bisphenol F, and their ethylene oxide adducts or propylene oxide adducts; and poly(meth)acrylates derived from glycidyl ethers such as diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate, etc. Furthermore, not limited to the above, examples include (meth)acrylates obtained by directly (meth)acrylate esterification of polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadiene, and polyester polyols, or by esterification of polyols with diisocyanate compounds into urethane (meth)acrylates, and melamine (meth)acrylates, etc.

[0043] Furthermore, examples include epoxy (meth)acrylate resins prepared by reacting multifunctional epoxy resins such as cresol phenolic varnish-type epoxy resins with (meth)acrylic acid, and epoxy urethane (meth)acrylate compounds prepared by further reacting the hydroxyl groups of the epoxy (meth)acrylate resin with hydroxy acrylates such as pentaerythritol tri(meth)acrylate and semi-urethane compounds such as isophorone diisocyanate. Such epoxy (meth)acrylate resins can improve photocurability without reducing touch-drying properties.

[0044] The photosensitive compound may contain at least aromatic poly(meth)acrylates derived from bisphenol A, bisphenol F, and their ethylene oxide or propylene oxide adducts. The photosensitive resin may contain only one photosensitive compound or a combination of two or more.

[0045] When the photosensitive thermosetting resin composition contains a photosensitive compound, the content of the photosensitive compound, calculated based on solid content, is, for example, 5 parts by mass or more and 100 parts by mass or less, preferably 10 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the carboxyl-containing resin. If the content is 5 parts by mass or more, the photocurability is improved, and the pattern formation caused by alkaline development after irradiation with active energy rays tends to be further improved. Furthermore, if the content is 100 parts by mass or less, sufficient solubility in an alkaline aqueous solution after irradiation with active energy rays can be obtained, and the strength of the formed coating tends to be further improved.

[0046] Photopolymerization initiator

[0047] The photosensitive thermosetting resin composition contains at least an oxime ester-based photopolymerization initiator and a titanium ceramsite-based photopolymerization initiator as photopolymerization initiators.

[0048] Oxime ester photopolymerization initiators

[0049] Oxime ester photopolymerization initiators can be photopolymerization initiators that have an O-acyl oxime structure in the molecule, or for example, photopolymerization initiators that contain a partial structure represented by the following formula (I).

[0050]

[0051] In the formula, R 1 R represents a hydrogen atom, a phenyl group that may have substituents, an alkyl group that may have 1 to 20 carbon atoms that may have substituents, a cycloalkyl group that may have 5 to 8 carbon atoms, an alkylyl group that may have 2 to 20 carbon atoms, or a benzoyl group that may have substituents. 2 This indicates a phenyl group that may have substituents, an alkyl group that may have substituents with 1 to 20 carbon atoms, a cycloalkyl group with 5 to 8 carbon atoms, an alkylyl group with 2 to 20 carbon atoms, or a benzoyl group that may have substituents. As a group composed of R... 1 or R 2 Examples of substituents in a phenyl group include alkyl groups, phenyl groups, and halogen atoms with 1 to 6 carbon atoms. The number of substituents in a phenyl group can range from 1 to 5. (The last part, "R," appears to be a typo and can be left as is.) 1 or R 2 The alkyl group can be straight-chain or branched and can be substituted with more than one hydroxyl group. Additionally, at least one of the methylene groups constituting the alkyl group can be substituted with an oxygen atom or a carbonyl group. As a group composed of R... 1 or R 2 Examples of substituents in the benzoyl group include alkyl groups and phenyl groups with 1 to 6 carbon atoms. The number of substituents in the benzoyl group can be 1 to 5.

[0052] Examples of compounds in which the partial structure represented by formula (I) can be substituted include diaryl sulfides, 9H-carbazole, thioxanth-9-one, fluorene, and their derivatives. The partial structure represented by formula (I) can substitute for hydrogen atoms in these compounds and bond them, or it can be bonded via a carbonyl group.

[0053] As oxime ester-based photopolymerization initiators containing a partial structure represented by formula (I), examples include compounds represented by formulas (I-1), (I-2), (I-3), etc.

[0054]

[0055] In equation (I-1), R 11 With R in equation (I) 1 The definitions are the same, R 12 With R in equation (I) 2 The definition is the same. R 13 Represents hydrogen atoms, hydroxyl groups, carboxyl groups, hydroxyalkoxy groups, hydroxyalkoxycarbonyl groups, etc. R 13 The number of carbon atoms in the hydroxyalkoxy group can be 1 to 20. n represents 0 or 1.

[0056]

[0057] In equation (I-2), R 21 With R in equation (I) 1 The definitions are the same, R 22 and R 24 Each can independently represent a phenyl group that may have substituents, an alkyl group that may have substituents with 1 to 20 carbon atoms, a cycloalkyl group with 5 to 8 carbon atoms, an alkanoyl group with 2 to 20 carbon atoms, or a benzoyl group that may have substituents. As a group composed of R... 24 The substituents in the phenyl group can be alkyl groups having 1 to 18 carbon atoms, or organic groups having an acetal bond. For example, an organic group having an acetal bond can be (2,2-dimethyl-1,3-dioxolane-4-yl)methoxy. R 23 This refers to a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group containing a substituent and having 5 to 12 carbon atoms, a phenyl group, a benzyl group, a benzoyl group, an alkanoyl group having 2 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, or a phenoxycarbonyl group. For those constituting R... 23 The alkyl group represented by the alkoxycarbonyl group, when having 2 or more carbon atoms, may be substituted by at least one hydroxyl group, and at least one of the methylene groups constituting the alkyl group may be substituted by an oxygen atom.

[0058]

[0059] In equation (I-3), R 31 With R in equation (I) 1 The definitions are the same, R 32 With R in equation (I) 2 The definition is the same. R 33 It can refer to hydrogen atoms, halogen atoms, alkyl groups with 1 to 12 carbon atoms, cycloalkyl groups containing substituents and with 5 to 12 carbon atoms, etc.

[0060] Examples of oxime ester-based photopolymerization initiators containing the structural moiety represented by formula (I) include 1-[4-(phenylsulfanyl))phenyl]-1,2-octanedione 2-(O-benzoyl oxime), 1-{4-[4-(2-hydroxyethoxy)phenylsulfanyl]phenyl}propane-1,2-dione 2-(O-acetyl oxime), 2-(acetoxyiminomethyl)thioxan-9-one, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetyl oxime), 1-[9-ethyl-6-]acetone 1-(O-acetyl oxime), 1-[9-ethyl-6-]acetone 1-(O-acetyl oxime), 1-[9-ethyl-6-]acetone 1-(O-acetyl oxime), 1-[9-ethyl-6-]acetone 1-(O-acetyl oxime]acetone 1-(O-acetyl oxime]acetone 1-(O-)acetyl oxime, 1-[9-ethyl-6- ... (2-Methyl-4-tetrahydrofuranylmethoxybenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetyl oxime), 1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolane)methoxybenzoyl}-9H-carbazole-3-yl]acetone 1-(O-acetyl oxime), 1-[4-[3-[4-[[2-(acetoxy)ethyl]sulfonyl]-2-methylbenzoyl]-6-[1-[(acetoxy)imino]ethyl]-9H-carbazole]-9-yl]phenyloctanone 1-(O-acetyl oxime), etc. These oxime ester photopolymerization initiators can be used alone or in combination of two or more.

[0061] Commercially available oxime ester-based photopolymerization initiators include Adeka Arkls NCI-700, Adeka Arkls NCI-730, Adeka Arkls NCI-831, Adeka Arkls NCI-930; 1-4-[[4-(2-hydroxyethoxy)phenyl]thio]phenyl]-1,2-propanedione 2-(O-acetyl oxime) (manufactured by ADEKA CORPORATION), DFI-020, DFI-091 (manufactured by Daito Chemix Co., Ltd.), CGI-325, Irgacure OXE01, Irgacure OXE02; 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetyl oxime), Irgacure OXE03, Irgacure... OXE04 (and above, manufactured by BASF Japan), etc.

[0062] Relative to 100 parts by weight of the carboxyl-containing resin, the content of the oxime ester-based photopolymerization initiator in the photosensitive thermosetting resin composition, calculated based on solid content, can be, for example, 0.01 parts by weight or more and 10 parts by weight or less, preferably 0.02 parts by weight or more and 8 parts by weight or less, and more preferably 0.05 parts by weight or more and 5 parts by weight or less. If the content of the oxime ester-based photopolymerization initiator is 0.01 parts by weight or more, sufficient photocuring can be achieved. Furthermore, if it is 10 parts by weight or less, there is a tendency for a good balance between surface curing and bottom curing. In one embodiment, the content of the oxime ester-based photopolymerization initiator can be 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less.

[0063] Titanium ceramsite photopolymerization initiator

[0064] Compounds represented by the following formula (II) can be cited as initiators of diacetic photopolymerization.

[0065]

[0066] In the formula, R 9 and R 10 Each can be independently represented as a halogen atom, aryl group, haloaryl group, or heterocyclic haloaryl group.

[0067] Examples of diacetaxel-based photopolymerization initiators represented by formula (II) include di(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1H-pyrrolo-1-yl)ethyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(1H-pyrrolo-1-yl)propyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-((1H-pyrrolo-1-yl)methyl)phenyl]titanium, di(methylcyclopentadienyl)-bis[2,6-difluoro-3-((1H-pyrrolo-1-yl)methyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-((2,5-dimethyl-1H-pyrrolo-1-yl)methyl)phenyl]titanium, and ... 2,6-difluoro-3-((2-isopropyl-5-methyl-1H-pyrrole-1,6-yl)methyl)phenyl]titanium, 2,6-difluoro-3-((2-(2-methoxyethyl)-5-methyl-1H-pyrrole-1-yl)methyl)phenyl]titanium, 2,6-difluoro-3-((3-trimethylsilyl-2,5-dimethyl-1H-pyrrole-1-yl)methyl)phenyl]titanium, 2,6-difluoro-3-((2,5-dimethyl-3-(bis(2-methoxyethyl)aminomethyl) ...2,6-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di-di- Fluoro-3-((2,5-bis(morpholinomethyl)-1H-pyrrolo-1-yl)methyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-((2,5-dimethyl-3-(1,3-dioxolane-2-yl)-1H-pyrrolo-1-yl)methyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-4-((2,5-dimethyl-1H-pyrrolo-1-yl)methyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-methyl-4-(2-(1H-pyrrolo-1-yl)ethyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-((2,3,4,5-tetramethyl-1H-pyrrolo-1-yl)methyl)phenyl]titanium [2,6-difluoro-3-(2-(1H-pyrrolo-1-yl)propyl)phenyl]titanium, 2,6-difluoro-3-(2-(1H-pyrrolo-1-yl)propyl)phenyl]titanium, 2,6-difluoro-3-(1-methyl-2-(1H-pyrrolo-1-yl)ethyl)phenyl]titanium, 2,6-difluoro-3-(1-methyl-2-(1H-pyrrolo-1-yl)ethyl)phenyl]titanium, 2,6-difluoro-3-(3-(2-isoindol-2-yl)propyl)phenyl]titanium, 2,6-difluoro-3-(2-(4,5,6,7-tetrahydro-isoindol-2-yl)ethyl ...6-Difluoro-3-(6-(9-carbazol-9-yl)hexyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(2,3,4,5,6,7,8,9-octahydro-1-carbazol-9-yl)propyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(4,5,6,7-tetrahydro-2-methyl-1-indol-1-yl)propyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-((acetamido)methyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3- (2-(propionylamino)ethyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(acetamido)propyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(4-(neopentylamino)butyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(2,2-dimethylpentanoylamino)ethyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(benzoylamino)propyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(benzoylamino)propyl)phenyl]titanium, di(cyclopentadienyl)-bis[2,6-difluoro-3-((2,2- [Dimethylpentadienylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)bis[2,6-difluoro-3-(2-(2,2-dimethyl-3-chloropropionylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)bis[2,6-difluoro-3-((2,2-dimethyl-3-ethoxypropionylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)bis[2,6-difluoro-3-(2-(lauroylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)bis[2,6-difluoro-3-(2-(N-allylmethylsulfonylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)bis[2,6-difluoro-3-(2-(N-allylmethyl ... (enyl)-bis[2,6-difluoro-3-(3-(N-isobutylphenylsulfonylamino)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((methylsulfonylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(ethylsulfonylamino)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(butylsulfonylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(4-(trisulfonylamino)propyl)phenyl]titanium, bis(η, 5 -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl)titanium, etc. These titanium-ceramic photopolymerization initiators can be used alone or in combination of two or more.

[0068] Commercially available products that serve as diacene-based photopolymerization initiators include JMT-784 (manufactured by Yueyang Jinmaotai Technology Co., Ltd.); diacene-784 is an example of a diacene-based photopolymerization initiator. 5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl)titanium, etc.

[0069] Relative to 100 parts by weight of the carboxyl-containing resin, the content of the titanium-based photopolymerization initiator in the photosensitive thermosetting resin composition, calculated on a solids basis, can be, for example, 0.01 parts by weight or more and 10 parts by weight or less, preferably 0.02 parts by weight or more and 8 parts by weight or less, more preferably 0.05 parts by weight or more and 5 parts by weight or less. If the content of the titanium-based photopolymerization initiator is 0.01 parts by weight or more, sufficient photocuring can be achieved. Furthermore, if it is 10 parts by weight or less, there is a tendency to suppress uneven curing. In one embodiment, the content of the titanium-based photopolymerization initiator can be 2 parts by weight or less, 1 part by weight or less, or 0.5 parts by weight or less.

[0070] The mass ratio of oxime ester-based photopolymerization initiator to titanium cadmium-based photopolymerization initiator in the photopolymerization initiator can be, for example, 1:10 to 10:1, preferably 1:8 to 8:1, more preferably 1:5 to 5:1, and even more preferably 1:2 to 2:1. Within these ranges, a good balance between surface curing and deep curing is achieved, resulting in the formation of good patterns.

[0071] Relative to 100 parts by weight of carboxyl-containing resin, the total content of the diacene-based photopolymerization initiator and the oxime ester-based photopolymerization initiator in the photosensitive thermosetting resin composition, calculated on a solids basis, can be, for example, 0.01 parts by weight or more and 10 parts by weight or less, preferably 0.1 parts by weight or more and 2 parts by weight or less, more preferably 0.2 parts by weight or more and 1 part by weight or less. If the total content of the diacene-based photopolymerization initiator and the oxime ester-based photopolymerization initiator is 0.01 parts by weight or more, sufficient photocuring can be achieved. Furthermore, if it is 10 parts by weight or less, there is a tendency to suppress uneven curing.

[0072] Photopolymerization initiators, besides oxime ester-based and titanium-ceramic-based photopolymerization initiators, can also include other photopolymerization initiators besides oxime ester-based and titanium-ceramic-based initiators. Examples of other photopolymerization initiators include benzophenone-based photopolymerization initiators, acetophenone-based photopolymerization initiators, aminoacetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, benzyl ketal-based photopolymerization initiators, oxime ether-based photopolymerization initiators, alkyl phenyl ketone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.

[0073] When the photopolymerization initiator contains other photopolymerization initiators, in one embodiment, the content of the solids component relative to the total mass of the photopolymerization initiator can be, for example, 80% by mass or more and 99% by mass or less, preferably 90% by mass or less and 97% by mass or less. In another embodiment, the content can be, for example, 10% by mass or less, preferably 1% by mass or less, and more preferably 0.1% by mass or less.

[0074] White pigment

[0075] The photosensitive thermosetting resin composition contains at least one white pigment. By including a white pigment, the cured product can be whitened. Examples of white pigments include zinc oxide, potassium titanate, zirconium oxide, antimony oxide, lead white, zinc sulfide, lead titanate, etc. From the viewpoint of reflectivity and the effect of inhibiting discoloration, it is preferable that the white pigment contains at least titanium oxide. As titanium oxide, titanium oxide produced by the sulfuric acid process, chlorination process, etc., rutile titanium oxide, anatase titanium oxide, or titanium oxide that has undergone surface treatment with an aqueous metal oxide or with an organic compound can be used. Among these titanium oxides, rutile titanium oxide is preferred from the viewpoint of photocatalyst activity. By using rutile titanium oxide, a more stable cured product (e.g., solder resist film) can be obtained. Specifically, examples of rutile titanium dioxide include TR-600, TR-700, TR-750, TR-840 (and above, manufactured by Fuji Titanium Industry Co., Ltd.), R-550, R-580, R-630, R-820, CR-50, CR-60, CR-90 (and above, manufactured by Ishihara Kogyo Co., Ltd.), KR-270, KR-310, and KR-380 (and above, manufactured by Titanium Industry Co., Ltd.). Among these rutile titanium dioxides, from the viewpoints of dispersibility in the composition, storage stability, and flame retardancy, titanium dioxide with a surface treated with hydrated alumina or aluminum hydroxide is particularly preferred. White pigments can be used alone or in combination of two or more.

[0076] The volume average particle size of the white pigment can be, for example, 10 nm or more and 5 μm or less, preferably 100 nm or more and 1 μm or less. The volume average particle size of the white pigment is determined as the particle size corresponding to 50% of the cumulative volume from the small diameter side in the cumulative particle size distribution of the volume reference measured, for example, using a laser diffraction particle size distribution measuring device.

[0077] The whiteness of the white pigment can be, for example, 80 or higher, preferably 85 or higher. The whiteness is measured, for example, using a spectrophotometer (such as the PF10 manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS P8148:2018 "Method for determination of whiteness (diffuse blue light reflectance)".

[0078] Relative to 100 parts by weight of carboxyl-containing resin, the content of white pigment in the photosensitive thermosetting resin composition, calculated based on solid content, can be, for example, 200 parts by weight or more and 1000 parts by weight or less, preferably 250 parts by weight or more and 800 parts by weight or less. If the content of white pigment is 200 parts by weight or more, sufficient reflectivity can be achieved in the cured product. Furthermore, if it is 1000 parts by weight or less, the viscosity increase of the composition can be suppressed, resulting in good coating and molding properties, and a tendency to suppress the brittleness of the cured product.

[0079] thermosetting resins

[0080] The photosensitive thermosetting resin composition comprises at least one thermosetting resin. Commonly known resins such as isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclic carbonate compounds, epoxy resins, polyfunctional oxobutane compounds, and cyclic sulfide resins can be used as thermosetting resins. Preferably, the thermosetting resin has at least one of a plurality of cyclic ether groups and cyclic sulfide groups (hereinafter simply referred to as cyclic (sulfide) ether groups) in one molecule. Many commercially available types of these thermosetting components having cyclic (sulfide) ether groups are available, and their structures can impart a wide variety of properties.

[0081] Thermosetting resins having a plurality of cyclic (thio)ether groups in their molecules are compounds having at least one of cyclic ether groups or cyclic thioether groups with a plurality of 3, 4, or 5-membered rings in their molecules. Examples include compounds having a plurality of epoxy groups in their molecules, i.e., polyfunctional epoxy compounds; compounds having a plurality of oxocyclobutyl groups in their molecules, i.e., polyfunctional oxocyclobutane compounds; and compounds having a plurality of thioether groups in their molecules, i.e., cyclic sulfur compounds.

[0082] Specific examples of multifunctional epoxy compounds include, for instance, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenolic varnish type epoxy resin, phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, N-glycidyl type epoxy resin, bisphenol A phenolic varnish type epoxy resin, bixylenol type epoxy resin, biphenol type epoxy resin, chelated epoxy resin, glyoxal type epoxy resin, amino-containing epoxy resin, rubber-modified epoxy resin, dicyclopentadienol type epoxy resin, diglycidyl phthalate resin, heterocyclic epoxy resin, tetraglycidyl xylenoyl ethane resin, silicone-modified epoxy resin, ε-caprolactone-modified epoxy resin, etc. Furthermore, as a multifunctional epoxy resin, a resin formed by introducing halogen atoms such as chlorine and bromine, or atoms such as phosphorus, into its structure can be used. This, for example, imparts flame retardancy. A single multifunctional epoxy resin can be used, or two or more can be used in combination.

[0083] As a multifunctional oxetane compound, besides bis[(3-methyl-3-oxetane-butylmethoxy)methyl] ether, bis[(3-ethyl-3-oxetane-butylmethoxy)methyl] ether, 1,4-bis[(3-methyl-3-oxetane-butylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, (3-methyl-3-oxetane-butyl)methyl acrylate, (3-ethyl-3-oxetane-butyl)methoxy]methyl acrylate, (3-ethyl-3-oxetane-butyl)methoxy]methyl acrylate, etc. Besides polyfunctional oxetanes such as methyl butyl acrylate, (3-methyl-3-oxetane)methyl methacrylate, (3-ethyl-3-oxetane)methyl methacrylate, and their oligomers or copolymers, examples include etherifications of resins containing hydroxyl groups such as oxetane alcohols and phenolic varnish resins, poly(p-hydroxystyrene), Cardo-type bisphenols, calixarenes, resorcinol calixarenes, or silsesquioxanes. Additionally, copolymers of unsaturated monomers with oxetane rings and alkyl (meth)acrylates can also be cited.

[0084] Examples of cyclic sulfur resins include YL7000 (bisphenol A type cyclic sulfur resin) manufactured by Mitsubishi Chemical Corporation. Alternatively, cyclic sulfur resins can be obtained by replacing the oxygen atom in the epoxy group of a phenolic varnish-type epoxy resin with a sulfur atom using the same synthesis method.

[0085] Relative to 100 parts by weight of carboxyl-containing resin, the content of thermosetting resin in the photosensitive thermosetting resin composition, calculated based on solid content, can be, for example, 10 parts by weight or more and 100 parts by weight or less, preferably 20 parts by weight or more and 80 parts by weight or less. If the content of thermosetting resin is within the above range, good soldering heat resistance can be obtained in the cured product of the photosensitive resin composition. In addition, it tends to have good properties, especially electrical insulation, when used as an insulating protective film for printed wiring substrates.

[0086] In addition to a thermosetting resin, the photosensitive thermosetting resin composition may also contain a thermosetting catalyst. Examples of thermosetting catalysts include, for instance, imidazole derivatives such as imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 4-phenylimidazolium, 1-cyanoethyl-2-phenylimidazolium, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazolium; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipate dihydrazide and sebacate dihydrazide; and phosphorus compounds such as triphenylphosphine. In addition, commercially available substances include, for example, 2MZ-A, 2MA-OK, 2PHZ-PW, 2P4BHZ-PW (all manufactured by Shikoku Chemical Industry Co., Ltd.; all are trade names of imidazole compounds), DBU, DBN, U-CATSA102, U-CAT5002 (all manufactured by San Apro Co., Ltd.; all are bicyclic amidine compounds and their salts), etc. In particular, it is not limited to these, as long as it is a thermosetting catalyst for epoxy resins or oxetane compounds, or a substance that promotes the reaction of at least one of the epoxy groups and oxetane groups with a carboxyl group. In addition, S-triazine derivatives such as guanidine, acetylguanidine, benzoguanidine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine-isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine-isocyanuric acid adduct can also be used. A single thermosetting catalyst can be used, or two or more can be used in combination.

[0087] When the photosensitive thermosetting resin composition contains a thermosetting catalyst, the amount of solid content relative to 100 parts by weight of the thermosetting resin can be, for example, 0.1 parts by weight or more and 20 parts by weight or less, preferably 0.5 parts by weight or more and 15 parts by weight or less.

[0088] Furthermore, as needed, to improve properties such as adhesion, hardness, and heat resistance, the photosensitive thermosetting resin composition may also include at least one filler selected from the group consisting of inorganic and organic fillers. Examples of inorganic fillers include barium sulfate, calcium carbonate, silica, amorphous silica, talc, clay, hydrotalcite, and mica powder; examples of organic fillers include silicon powder, nylon powder, and fluorine powder. Among the above fillers, silica is particularly excellent in terms of low hygroscopicity and low volume expansion. Silica can be a mixture of these fillers regardless of its melting or crystallinity; in particular, silica that has undergone surface treatment with a coupling agent or the like can improve electrical insulation and is therefore preferred. The average particle size of the filler is 25 μm or less, more preferably 10 μm or less, and even more preferably 3 μm or less. When the photosensitive thermosetting resin composition includes a filler, the filler content, calculated based on solid content, may be, for example, 150 parts by weight or less, preferably 50 parts by weight or less, relative to 100 parts by weight of the carboxyl-containing resin. If the filler content is in the above proportion, the cured film will have good folding resistance.

[0089] The photosensitive thermosetting resin composition may also contain other additives besides the aforementioned components. Examples of additives include tackifiers such as organobentonite and montmorillonite, defoamers such as silicone-based, fluorine-based, and polymer-based defoamers and leveling agents, and fiber-reinforcing materials such as glass fiber, carbon fiber, and boron nitride fiber. Furthermore, depending on the requirements, adhesion promoters, thermal polymerization inhibitors, peroxide decomposition agents, ultraviolet absorbers, silane coupling agents such as thiazole-based and triazole-based agents, dispersants, defoamers, plasticizers, foaming agents, flame retardants, antistatic agents, anti-aging agents, and antibacterial / antifungal agents may be added.

[0090] Depending on the requirements, the photosensitive thermosetting resin composition may also contain at least one of a free radical supplement and a peroxide decomposer. This inhibits the degradation of the cured product's functionality. The free radical supplement and the peroxide decomposer can be so-called antioxidants.

[0091] Examples of free radical supplements include hydroquinone, 4-tert-butylcatechol, 2-tert-butylhydroquinone, hydroquinone monomethyl ether, 2,6-di-tert-butyl-p-cresol, 2,2-methylene-bis(4-methyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3',5'-di-tert-butyl-4-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, quinone compounds such as methoxyquinone and benzoquinone, amine compounds such as bis(2,2,6,6-tetramethyl-4-piperidinyl)-sebate, and phenothiazine.

[0092] Free radical supplements can be commercially available products, such as ADKSTAB (registered trademark) AO-30, ADKSTABAO-330, ADKSTABAO-20, ADKSTABLA-77, ADKSTABLA-57, ADKSTABLA-67, ADKSTABLA-68, ADKSTABLA-87 (all manufactured by Adico Corporation), Irganox (registered trademark) 1010, Irganox 1035, Irganox 1076, Irganox 1135, Tinuvin (registered trademark) 111FDL, Tinuvin 123, Tinuvin 144, Tinuvin 152, Tinuvin 292, Tinuvin 5100 (all manufactured by BASF Japan), etc.

[0093] Ultraviolet absorbers can be commercially available products, such as Tinuvin PS, Tinuvin 99-2, Tinuvin 109, Tinuvin 384-2, Tinuvin 900, Tinuvin 928, Tinuvin 1130, Tinuvin 400, Tinuvin 405, Tinuvin 460, and Tinuvin 479 (all manufactured by BASF Japan).

[0094] The photosensitive thermosetting resin composition may also contain an organic solvent. By containing an organic solvent, the components can be easily dissolved or dispersed. In addition, the viscosity can be easily adjusted to suit coating and other application methods. Examples of organic solvents include, for example, aromatic solvents such as toluene, xylene, ethylbenzene, and nitrobenzene; aliphatic hydrocarbon solvents such as cyclohexane; ether solvents such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether; ester solvents such as carbitol acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethyl ethoxypropionate, ethyl acetate, n-butyl acetate, isoamyl acetate, ethyl lactate, and γ-butyrolactone; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and isophorone; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; and halogenated hydrocarbon solvents such as chloroform and dichloromethane. Organic solvents can be used alone or in combination of two or more. In addition, the content of organic solvents can be set appropriately according to the desired viscosity, etc.

[0095] The photosensitive thermosetting resin composition is obtained by dissolving or dispersing the above components using a mixer, such as a disperser, kneader, three-roll mill, bead mill, etc.

[0096] In one embodiment, the photosensitive thermosetting resin composition comprises a photosensitive resin, a photopolymerization initiator, a white pigment, and an epoxy resin. The photosensitive resin includes a carboxyl-containing resin, and the photopolymerization initiator includes an oxime ester-based photopolymerization initiator and a titanium-based photopolymerization initiator. The mass ratio of the white pigment content to the photosensitive resin content is 1.2 or more and 5 or less, and the mass ratio of the total content of the oxime ester-based photopolymerization initiator and the titanium-based photopolymerization initiator to the white pigment content can be 0.0004 or more and 0.002 or less. With the white pigment content and the photopolymerization initiator content within the specified ranges, excellent whiteness and high reflectivity at a wavelength of 450 nm can be achieved.

[0097] Cured material

[0098] The cured product of the photosensitive thermosetting resin composition exhibits high whiteness and excellent reflectivity at a wavelength of 450 nm. The cured product of the photosensitive thermosetting resin composition can be obtained, for example, under the following curing conditions.

[0099] Curing conditions

[0100] A photosensitive thermosetting resin composition was applied to a substrate to achieve a film thickness of 55 μm after thermosetting, and then dried at 80°C for 30 minutes. A high-pressure mercury lamp at 400 mJ / cm² was used. 2Expose and develop (30°C, 0.2 MPa, 1% Na₂CO₃ aqueous solution) for 60 seconds. Then, a cured product can be obtained by heat curing at 150°C for 60 minutes.

[0101] L of the cured product after thermosetting of the photosensitive thermosetting resin composition * a * b * b in the color system * Values ​​below 2.0. * The value is preferably 1.8 or less, more preferably 1.5 or less. It should be noted that for L... * a * b * b in the color system * The value was determined using a spectrophotometer (Konica Minolta CM-5) for a 55 μm thick cured material produced under the above conditions. The value was measured by the b value of the cured material. * Within the specified range, there is a tendency to suppress yellowing caused by heating.

[0102] Furthermore, the reflectance of the cured material at a wavelength of 450 nm is 85% or higher. Preferably, the reflectance at 450 nm is 88% or higher. It should be noted that the reflectance at 450 nm was measured using a spectrophotometer (Konica Minolta, model CM-5) with a diameter of 8 mm, for a 55 μm thick cured material prepared under the above curing conditions, via SCI method. When the reflectance of the cured material is within the specified range, the light extraction efficiency in the display is improved, indicating a tendency to effectively utilize reflected light.

[0103] Cured products formed from photosensitive thermosetting resin compositions exhibit excellent heat resistance and maintain whiteness and reflectivity. Specifically, for example, ΔEab after undergoing a heat treatment (reflow process) at a maximum temperature of 260°C for 10 seconds... * For example, it can be below 2.0, preferably below 1.0. Here, ΔEab * It is used as L before heat treatment * a * b * With heat-treated L * a * b * The difference ΔL * , Δa * Δb * The value obtained by formula (1) is an indicator of the degree of discoloration.

[0104] ΔEab * =((ΔL) * ) 2 +(Δa * ) 2 +(Δb * ) 2 ) (1 / 2) (1)

[0105] Furthermore, the reduction in reflectance under the 450nm wavelength condition can be, for example, 5% or less, preferably 2% or less. Here, the reduction in reflectance is calculated by subtracting the reflectance (%) measured in the cured product after heat treatment from the reflectance (%) measured in the cured product before heat treatment.

[0106] The photosensitive thermosetting resin composition can be applied to a printed circuit board to form a resin composition layer by means of an application method selected from commonly used application methods. Furthermore, it can be used in various forms and applications, such as dry film or prepreg. Depending on the method of application and purpose, various solvents can be used; however, depending on the circumstances, not only good solvents but also unsuitable solvents can be used.

[0107] For photosensitive thermosetting resin compositions, for example, the viscosity is adjusted to a suitable application method using the aforementioned organic solvent, applied to a substrate, and dried (pre-dried) by evaporating the organic solvent contained in the composition at a temperature of approximately 60°C to 100°C, thereby forming a surface-dried resin composition layer. Examples of application methods include dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, and spray coating. Alternatively, the aforementioned photosensitive thermosetting resin composition can be coated onto a carrier film, dried, and then bonded as a film-wound material to a substrate to form a resin composition layer. Then, by contact (or non-contact) exposure using an active energy ray through a patterned photomask or by direct pattern exposure using a laser direct exposure machine, the unexposed areas are developed using a dilute alkaline aqueous solution (e.g., a 0.3% to 3% sodium carbonate aqueous solution) to form a resist pattern (pattern image). The exposure conditions are as described below. Furthermore, for example, by heating at a temperature of approximately 140°C to 180°C and thermosetting it, the carboxyl groups (or further phenolic hydroxyl groups) of the carboxyl-containing resin react with the cyclic (thio) ether groups of the thermosetting resin. In addition to properties such as adhesion to the substrate, flexural strength, low warpage, resistance to electroless gold plating, weld heat resistance, and electrical insulation, softness and high reflectivity are achieved at a high level of uniformity. Moreover, a white cured film is formed in which the decrease in reflectivity and whiteness over time is suppressed.

[0108] As a substrate, it can utilize printed wiring boards, flexible printed wiring boards, copper-clad laminates using all grades (FR-4, etc.) of composite materials such as paper-phenolic resin, paper-epoxy resin, glass cloth-epoxy resin, glass-polyimide, glass cloth / non-woven fabric-epoxy resin, glass cloth / paper-epoxy resin, synthetic fiber-epoxy resin, fluoropolymer-polyethylene-PPO-cyanate, polyimide films, PET films, glass substrates, ceramic substrates, wafer boards, etc. Circuits can be formed on the above-mentioned substrates, and structures such as transistors can also be formed and mounted.

[0109] For the volatile drying after applying the photosensitive resin composition, hot air circulating drying ovens, IR ovens, hot plates, convection ovens, etc. (using a heat source with a steam-based air heating method, a method of hot air convection contact within the dryer and a method of spraying from a nozzle onto the support) can be used.

[0110] A photosensitive resin composition is applied to a substrate, and after evaporation and drying, the resulting resin composition layer is exposed (irradiated with active energy rays). The exposed portion of the resin composition layer (the portion irradiated with active energy rays) is cured.

[0111] Examples of exposure machines used for irradiating the aforementioned active energy rays include direct drawing devices (e.g., laser direct imaging devices that directly draw images using lasers from CAD data from a computer), exposure machines equipped with metal halide lamps, exposure machines equipped with (ultra) high-pressure mercury lamps, exposure machines equipped with mercury short-arc lamps, or direct drawing devices using ultraviolet lamps such as (ultra) high-pressure mercury lamps. As for the active energy rays, any laser with a maximum wavelength in the range of 350 nm to 450 nm is acceptable. For example, gas lasers or solid-state lasers can be used for irradiation. Furthermore, the exposure dose can be appropriately selected based on factors such as film thickness, and is typically set to 5 mJ / cm². 2 Up to 800mJ / cm 2 It can be preferably set to 5mJ / cm 2 Up to 500mJ / cm 2 Within the range described above. As a direct drawing device, for example, a device manufactured by Orbotech Corporation of Japan can be used, as long as it is a device that emits a laser with a maximum wavelength of 350nm to 450nm, any device can be used.

[0112] Examples of developing methods include immersion, spraying, misting, and brushing. As developing solutions, alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines can be used.

[0113] In addition to being applied directly to a substrate in liquid form, photosensitive thermosetting resin compositions can also be used as dry films having a resin composition layer formed by pre-coating a film such as polyethylene terephthalate with the photosensitive thermosetting resin composition and then drying it. An example of using a photosensitive resin composition as a dry film is shown below.

[0114] dry film

[0115] The dry film has a resin composition layer obtained by coating the above-mentioned photosensitive thermosetting resin composition onto a film and drying it. The dry film may have a structure in which a first film, a resin composition layer, and a peelable second film, used as needed, are sequentially laminated. The resin composition layer is, for example, a layer obtained by coating the photosensitive thermosetting resin composition onto the first film or the second film and drying it. A dry film can be obtained by laminating the second film onto the first film after forming the resin composition layer on the first film, or by laminating a laminate obtained by forming the resin composition layer on the second film onto the first film.

[0116] As the first film, a thermoplastic film such as a polyester film with a thickness of 2 μm to 150 μm is used. For the resin composition layer, the photosensitive thermosetting resin composition is uniformly coated onto the first or second film with a thickness of 10 μm to 150 μm using a doctor blade coater, lip coater, comma coater, or film coater, and then dried to form the second film. As the second film, polyethylene film, polypropylene film, etc., can be used, but it is preferable that the adhesion to the resin composition layer is smaller than that of the first film.

[0117] To create a protective film (permanent protective film) on a substrate using dry film, a second film is peeled off, and a resin composition layer is overlapped with the substrate on which the circuitry is formed. This is then bonded using a laminator or similar method to form the resin composition layer on the substrate. By exposing, developing, and heat-curing the formed resin composition layer in the same manner as described above, a cured coating can be formed. The first film can be peeled off before or after exposure.

[0118] Electronic components

[0119] The electronic component comprises a cured product of the aforementioned photosensitive thermosetting resin composition. Examples of electronic components include printed circuit boards (PCBs) and light source modules. The PCB includes: a substrate having patterned conductors; and a cured product of the photosensitive thermosetting resin composition disposed on the substrate. The cured product disposed on the substrate can be patterned into a desired shape. The light source module includes: a PCB; and a semiconductor light-emitting element disposed on the PCB and connected to the patterned conductors. In the light source module, the semiconductor light-emitting element can be coated with a cured resin layer. The cured resin layer coating the semiconductor light-emitting element may, for example, contain silicone resin.

[0120] As another aspect of the invention, it also includes the use of the photosensitive thermosetting resin composition in the manufacture of dry film or electronic components, and the use of the photosensitive thermosetting resin composition in the manufacture of dry film or electronic components.

[0121] Example

[0122] The present invention will be specifically described below through embodiments, but the present invention is not limited to these embodiments.

[0123] The following are the materials used to prepare the photosensitive thermosetting resin composition.

[0124] Carboxyl-containing resins

[0125] (Synthesis Example 1) Varnish A-1

[0126] 2400 g (3 mol) of polycarbonate diol (manufactured by Asahi Kasei Corporation, TJ5650J, number average molecular weight 800), 603 g (4.5 mol) of dimethylolpropionic acid, and 238 g (2.6 mol) of 2-hydroxyethyl acrylate as a monohydroxy compound were added to a reaction vessel equipped with a stirrer, thermometer, and condenser. Then, 1887 g (8.5 mol) of isophorone diisocyanate as a polyisocyanate was added. The mixture was heated to 60°C while stirring and then stopped. Heating was resumed when the temperature inside the reaction vessel began to decrease, and stirring continued at 80°C. The absorption spectrum of the isocyanate group (2280 cm⁻¹) was confirmed by infrared absorption spectroscopy. -1 The reaction ended after the solids disappeared. Varnish A-1 was obtained by adding carbitol acetate to make the solids content 50% by mass. The acid value of the solid was 50 mg KOH / g, and the weight-average molecular weight (Mw) was approximately 17000.

[0127] (Synthesis Example 2) Varnish A-2

[0128] 220g of cresol-phenolic varnish-type epoxy resin (manufactured by DIC Corporation, EPICLON N-695, epoxy equivalent: 220g / eq.) was placed in a four-necked flask equipped with a stirrer and a reflux cooler. 214g of carbitol acetate was added, and the mixture was heated to dissolve. Then, 0.1g of hydroquinone as a polymerization inhibitor and 2.0g of dimethylbenzylamine as a reaction catalyst were added. The mixture was heated to 95°C–105°C, and 72g of acrylic acid was slowly added dropwise, allowing the reaction to proceed for 16 hours. The reaction product was cooled to 80°C–90°C, and 106g of tetrahydrophthalic anhydride was added, allowing the reaction to proceed for 8 hours. After cooling, the product was removed. The resulting carboxyl-containing resin varnish A-2 had a solid content of 65%, an acid value of 100 mg KOH / g, and a weight-average molecular weight (Mw) of approximately 3500.

[0129] Photosensitive compounds

[0130] BPE-900: Manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Ethoxylated bisphenol A dimethacrylate.

[0131] Photopolymerization initiator

[0132] Oxime esters

[0133] Adeka Arkls NCI-930: Manufactured by Adeka Co., Ltd.; 1,4-[[4-(2-hydroxyethoxy)phenyl]thio]phenyl]-1,2-propanedione 2-(O-acetyloxime).

[0134] Adeka Arkls NCI-730: Manufactured by Adeka Co., Ltd.

[0135] Irgacure OXE04: BASF Japan.

[0136] Irgacure OXE02: Manufactured by BASF Japan; 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] ethyl ketone 1-(O-acetyl oxime).

[0137] Diocene titanium series

[0138] JMT-784: Manufactured by Yueyang Jinmaotai Technology Co., Ltd.; Double (η) 5 -2,4-Cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl)titanium).

[0139] Alkyl phenyl ketones

[0140] Omnirad 184: Manufactured by IGM Japan; 1-hydroxycyclohexylphenyl ketone.

[0141] α-Aminoacetophenone system

[0142] Omnirad 379: Manufactured by IGM Japan; 2-Dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butane-1-one.

[0143] Omnirad 907: Manufactured by IGM Japan; 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one.

[0144] White pigment

[0145] CR-90: Manufactured by Ishihara Kogyo Co., Ltd.; rutile titanium oxide.

[0146] thermosetting resins

[0147] jER834: Manufactured by Mitsubishi Chemical Corporation; Bisphenol A type epoxy resin, epoxy equivalent 250g / eq.

[0148] Thermosetting catalyst

[0149] DICY7: Made by Mitsubishi Chemical Co., Ltd.; dicyandiamide.

[0150] wetting and dispersing agents

[0151] Disperbyk-111: Manufactured by BYK Chemicals Japan.

[0152] Defoamer

[0153] KS-66: Manufactured by Shin-Etsu Chemical Industry Co., Ltd.; silicone-based oil complex type defoamer.

[0154] Preparation of photosensitive resin compositions

[0155] Using the obtained varnishes A-1 and A-2, the various components shown in Table 1 were combined in the proportions (parts by weight) recorded, premixed using a mixer, and then kneaded using a three-roll mill to prepare the photosensitive thermosetting resin compositions of Examples 1-13 and Comparative Examples 1-5. Unless otherwise stated, the values ​​in the tables are parts by weight. It should be noted that "-" in Tables 1 and 2 indicates that it was not added or not evaluated (because it could not be evaluated).

[0156] The photosensitive thermosetting resin compositions of Examples 1-13 and Comparative Examples 1-5 obtained in this way were evaluated as follows. These results are shown together in Tables 1 and 2.

[0157] Fabrication of evaluation substrate

[0158] The photosensitive thermosetting resin compositions of Examples 1-13 and Comparative Examples 1-5 were screen-printed twice onto a full copper substrate to form a coating with a total film thickness of 55 μm after thermosetting. Specifically, the coating was screen-printed onto the entire surface of the full copper substrate and dried in a hot air circulating dryer at 80°C for 10 minutes to form a first layer. The first layer was then screen-printed onto the entire surface and dried in a hot air circulating dryer at 80°C for 20 minutes to form a second layer. The formed coating was exposed to the optimal exposure using an exposure apparatus (Mms60: manufactured by ORCMANUFACTURING CO.,LTD.) equipped with a high-pressure mercury lamp and developed for 60 seconds (30°C, 0.2 MPa, 1% Na₂CO₃ aqueous solution). Then, the coating was thermo-cured in a hot air circulating dryer at 150°C for 60 minutes to form a resin layer, thus producing an evaluation substrate. It should be noted that the optimal exposure is defined as the exposure level of the dried coating film when exposed using an exposure device (Mms60: manufactured by Oku Corporation) equipped with a high-pressure mercury lamp and a StepTablet with a Stoutffer 41-step exposure table, and the pattern remaining on the StepTablet after 60 seconds of development with a 1% Na2CO3 aqueous solution at a jet pressure of 0.2 MPa and a liquid temperature of 30°C is considered to be an exposure level of 15 to 20.

[0159] Evaluation of surface curing properties

[0160] In addition to setting the exposure from "optimal exposure" to "400mJ / cm", 2 In addition, according to the fabrication of the evaluation substrate, after development and before thermal curing, the surface of the substrate is visually observed. The evaluation criteria for surface curability are as follows.

[0161] a: The surface is smooth and in good condition.

[0162] b: Roughness is observed on a portion of the surface.

[0163] c: Roughness is observed across the entire surface.

[0164] Evaluation of reflectivity

[0165] The reflectance and b* of the resin layer formed on each evaluation substrate obtained during the fabrication of the above-mentioned evaluation substrates were measured at 450 nm using the SCI method with a measurement diameter of 8 mm on a Konica Minolta CM-5 spectrophotometer. The measurement results are shown in Table 1 under the headings "Reflectance" and "b*". * OK.

[0166] In addition, the evaluation substrate was subjected to a reflow process once using a reflow apparatus (NIS-20-82C manufactured by Aitek Electronics Technology Co., Ltd.) at a maximum temperature of 260°C for 10 seconds. Then, the reflectivity and b were measured in the same manner as above. * The measurement results will be used as the reflectance after the heat resistance test and the b after the heat resistance test. * As shown in Table 1.

[0167] ΔEab * Evaluation

[0168] ΔEab * It is L before using reflux * a * b * and L after reflux * a * b * The value obtained by formula (1) is an indicator of the degree of color change. It was measured using a spectrophotometer (Konica Minolta, model: CM-5). The calculation results are shown in Table 1 as ΔEab. * OK.

[0169] ΔEab * =((ΔL) * ) 2 +(Δa * ) 2 +(Δb * ) 2 ) (1 / 2) (1)

[0170] Evaluation of weld heat resistance

[0171] Rosin-based flux was applied to each of the evaluation substrates obtained above, and the substrates were immersed in a solder bath pre-set to 260°C for 10 seconds. Then, the flux was washed off with modified alcohol, and the swelling and peeling of the resin layer were visually evaluated. The evaluation criteria for heat resistance are as follows.

[0172] a: After immersion for 10 seconds, the resin layer did not swell or peel off.

[0173] b: After immersion for 5 seconds, the resin layer did not swell or peel off.

[0174] c: After immersion for 5 seconds, the expansion and peeling of the resin layer are obvious.

[0175] Evaluation of deep curing properties (undercut)

[0176] The photosensitive thermosetting resin compositions of Examples 1-13 and Comparative Examples 1-5 were screen-printed twice onto a full copper substrate to form a coating film with a total film thickness of 55 μm after thermosetting. Specifically, the coating was applied to the entire surface of the full copper substrate by screen printing and dried in a hot air circulating drying oven at 80°C for 10 minutes to form a first layer. The first layer was then applied to the entire surface by screen printing and dried in a hot air circulating drying oven at 80°C for 20 minutes to form a second layer. An exposure apparatus (Mms60: manufactured by Oku Co., Ltd.) equipped with a high-pressure mercury lamp was used at 400 mJ / cm². 2 The formed coating was patterned and exposed to light, followed by 60 seconds of development (30°C, 0.2 MPa, 1% Na₂CO₃ aqueous solution). The cross-section of the opening portion of the resulting pattern was observed, and the lengths of the upper (air side) and lower (substrate side) portions were measured. Side etching was calculated using the following formula, and deep curing performance was evaluated.

[0177] Lateral erosion = (length of the upper part - length of the lower part) / 2

[0178] Table 1

[0179]

[0180] Table 2

[0181]

[0182] As described above, according to the present invention, it is known that a photosensitive resin composition can be provided that exhibits minimal discoloration after a heating process and maintains high reflectivity. In particular, Examples 2 and 4, which have lower amounts of oxime ester-based photopolymerization initiators and titanium-based photopolymerization initiators and higher amounts of white pigment than Example 3, exhibit higher reflectivity, and b * It exhibits excellent performance in terms of initiation value, surface curing properties, and weldability. This can be attributed to, for example, the synergistic effect of the oxime ester-based photopolymerization initiator and the titanium cadmium-based initiator, allowing the desired properties to be exhibited with a small initiation dosage.

[0183] Regarding Comparative Example 1, although a coating film could be formed, no robust pattern sufficient for evaluating lateral etching remained after development; therefore, deep curing properties could not be evaluated. In Comparative Example 2, since a coating film could not be formed, all evaluation items could not be evaluated. In Comparative Examples 4 and 5, the exposure levels used to evaluate surface curing and deep curing properties could not form a resin layer; therefore, evaluation was not possible.

[0184] The entire disclosure of Japanese Patent Application No. 2023-055267 (filed on March 30, 2023) is incorporated herein by reference. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent that each document, patent application, and technical standard is explicitly and individually indicated as incorporated by reference.

Claims

1. A photosensitive thermosetting resin composition comprising a carboxyl-containing resin, a photopolymerization initiator, a white pigment, and a thermosetting resin, wherein, The photopolymerization initiator includes oxime ester-based photopolymerization initiators and titanium cadmium-based photopolymerization initiators. The thermosetting resin includes epoxy resin. L of the cured product after thermosetting of the photosensitive thermosetting resin composition * a * b * b in the color system * The reflectivity is above 85% under the condition that the value is below 2.0 and the wavelength is 450nm.

2. The photosensitive thermosetting resin composition according to claim 1, wherein, For the aforementioned photopolymerization initiator, the mass ratio of the oxime ester-based photopolymerization initiator to the titanium ceramsite-based photopolymerization initiator is in the range of 1:10 to 10:

1.

3. A dry film, wherein, The dry film has a resin layer obtained by coating a first film with the photosensitive thermosetting resin composition of claim 1 or 2 and then drying it.

4. A solidified material, wherein, The cured product is formed by curing the photosensitive thermosetting resin composition according to claim 1 or 2.

5. An electronic component, wherein, The electronic component comprises the cured material as described in claim 4.

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