Curable resin composition, dry film, cured product, and electronic component

Abstract

[Problem] To achieve both high stability over time and excellent haloing resistance in a cured product. [Solution] The above problem is solved by a curable resin composition containing an alkali-soluble resin, a photopolymerization initiator, and a thermosetting compound, wherein the photopolymerization initiator is a compound represented by general formula (1) (In general formula (1), R1, R2, and R3 each independently represent a hydrogen atom (unsubstituted) or a substituent, and R4 represents a hydrogen atom (unsubstituted), an electron-withdrawing functional group, or a functional group that extends the conjugated system of a phenothiazine skeleton.).

Description

Curable resin compositions, dry films, cured products, and electronic components

[0001] The present invention relates to curable resin compositions, dry films, cured products, and electronic components.

[0002] In recent years, rapid advancements in semiconductor components have led to a trend towards smaller, lighter, and more compact electronic devices, higher performance, and greater functionality. Following this trend, semiconductor packages are also becoming smaller and having more pins.

[0003] Specifically, IC packages such as BGA (Ball Grid Array) and CSP (Chip Scale Package) are being used instead of IC packages such as QFP (Quad Flat Pack) and SOP (Small Outline Package). In recent years, FC-BGA (Flip Chip Ball Grid Array) has also been put into practical use as an even higher-density IC package.

[0004] In printed circuit boards used in these IC packages, the amount of heat generated by the chips tends to increase due to factors such as increased chip area and higher mounting density. Therefore, a high level of heat resistance is required for solder resists formed to protect the printed circuit boards, especially solder resists for FC-BGA and the like. As curable resin compositions for forming solder resists, for example, it has been proposed to contain resins having a predetermined carboxyl group, epoxy resins, inorganic fillers, etc. (Patent Document 1, etc.).

[0005] During the manufacturing of printed circuit boards, electroless gold plating is applied to the conductive pads formed in the solder resist openings. Printed circuit boards treated in this way have the problem of discoloration (haloing phenomenon) around the solder resist openings after electroless gold plating. As a means of solving the haloing phenomenon, a method of adding melamine to the curable resin composition that forms the solder resist has been proposed (Patent Document 2).

[0006] Japanese Patent Publication No. 2000-181058 Japanese Patent Publication No. 2012-017444

[0007] However, in printed circuit boards, the problem of haloing around solder resist openings after electroless gold plating can be solved by adding melamine to the curable resin composition. However, adding melamine accelerates the thermal reaction, which reduces the long-term stability of the resin composition and shortens the pot life at room temperature. Therefore, it has been difficult to achieve both long-term stability of the resin composition and resistance to haloing of the cured product with conventional curable resin compositions.

[0008] Therefore, the object of the present invention is to provide a curable resin composition having high stability over time and excellent haloing resistance in the cured product, a dry film having a resin layer obtained from the curable resin composition, a cured product of the resin layer of the curable resin composition or the dry film, and an electronic component having the cured product.

[0009] The inventors diligently studied to solve the above problems. As a result, they found that by including an oxime ester-based photopolymerization initiator having a predetermined chemical structure as a photopolymerization initiator in the curable resin composition, it is possible to achieve both the long-term stability of the curable resin composition and the suppression of the haloing phenomenon of the cured product. Based on this finding, further studies led to the completion of the present invention.

[0010] In other words, the present invention relates to the following curable resin compositions, dry films, cured products and electronic components: [1] A curable resin composition comprising an alkali-soluble resin, a photopolymerization initiator, and a thermosetting compound, wherein the photopolymerization initiator is of the following general formula (1): A curable resin composition which is a compound represented by the following formula (1) above: (In the above general formula (1), R1, R2, and R3 each independently represent a hydrogen atom (unsubstituted) or a substituent, and R4 represents a hydrogen atom (unsubstituted), an electron-withdrawing functional group, or a functional group that extends the conjugated system of the phenothiazine skeleton.) [2] The curable resin composition according to [1] above, wherein the content of the photopolymerization initiator is 0.02 to 20 parts by mass per 100 parts by mass of the alkali-soluble resin, on a solid content basis. [3] A dry film having a film and a resin layer made of the curable resin composition according to [1] or [2] above, laminated on at least one of the front and back surfaces of the film. [4] A cured product obtained by curing the curable resin composition according to [1] or [2] above. [5] A cured product obtained by curing the resin layer of the dry film according to [3] above. [6] An electronic component containing the cured product according to [4] above. [7] An electronic component containing the cured product according to [5] above.

[0011] According to the present invention, it is possible to achieve both high stability over time and excellent haloing resistance in the cured product.

[0012] The curable resin composition of the present invention contains an alkali-soluble resin, a photopolymerization initiator, and a thermosetting compound.

[0013] The components of the curable resin composition of the present invention are described below.

[0014] In this specification, "(meth)acrylate" is a general term referring to acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions ((meth)acrylic acid, (meth)acryloyl, etc.). Furthermore, when a numerical range is expressed using "~" such as "A to B", unless otherwise specified, this means "A or greater and B or less".

[0015] [Alkali-Soluble Resins] Alkali-soluble resins are resins that contain alkali-soluble groups in their molecules. For example, various known resins can be used, such as resins containing one or more alkali-soluble groups selected from the group consisting of phenolic hydroxyl groups and carboxyl groups. Specifically, examples of alkali-soluble resins include carboxyl group-containing resins, phenolic hydroxyl group-containing resins (especially resins containing two or more phenolic hydroxyl groups), and resins containing phenolic hydroxyl groups and carboxyl groups.

[0016] As for alkali-soluble resins, carboxyl group-containing resins are preferred from the viewpoint of developability, photocurability, and developability, and resins containing two or more carboxyl groups are more preferred. It is particularly preferable that the alkali-soluble resin contains ethylenically unsaturated groups in addition to carboxyl groups. The ethylenically unsaturated groups are preferably derived from acrylic acid, methacrylic acid, or their derivatives. This carboxyl group-containing resin having ethylenically unsaturated groups may hereafter be referred to as "carboxyl group-containing photosensitive resin." Note that only carboxyl group-containing resins without ethylenically unsaturated groups may be used as alkali-soluble resins. If the carboxyl group-containing resin does not have ethylenically unsaturated groups, a compound having multiple ethylenically unsaturated groups in its molecule, i.e., a photopolymerizable monomer, can be used in combination to make the curable resin composition photocurable.

[0017] Specific examples of alkali-soluble resins include the compounds listed below. These compounds may be either oligomers or polymers. Examples of carboxyl group-containing resins include the following compounds, which may be used individually or in combination of two or more: (1) Carboxyl group-containing resins obtained by copolymerization of an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

[0018] (2) A carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0019] (3) A carboxyl group-containing urethane resin obtained by a polyaddition reaction of a diisocyanate with a partially acid anhydride modified product of a reaction between a difunctional epoxy resin 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, and biphenol type epoxy resin, and a monocarboxylic acid compound having an ethylenically unsaturated double bond such as (meth)acrylic acid, and a carboxyl group-containing dialcohol compound and a diol compound.

[0020] (4) A carboxyl group-containing photosensitive urethane resin obtained by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, to the synthesis of the resin of (2) or (3) above, and then (meth)acrylizing the terminal (meth)acrylic.

[0021] (5) A carboxyl group-containing photosensitive urethane resin obtained by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in its molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, to the synthesis of the resin of (2) or (3) above, and then (meth)acrylicating the terminals.

[0022] (6) A carboxyl group-containing photosensitive resin obtained by reacting a bifunctional or polyfunctional epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chain. Here, the bifunctional or polyfunctional epoxy resin is preferably solid.

[0023] (7) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin, in which the hydroxyl groups of a bifunctional epoxy resin are further epoxidized with epichlorohydrin, with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups. Here, the bifunctional epoxy resin is preferably solid.

[0024] (8) A carboxyl group-containing polyester resin obtained by reacting a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid with a bifunctional oxetane resin, and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the resulting primary hydroxyl group.

[0025] (9) A carboxyl group-containing photosensitive resin obtained by reacting an epoxy compound having two or more epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic anhydride.

[0026] (10) A carboxyl group-containing photosensitive resin obtained by reacting a reaction product obtained by reacting a compound having two or more phenolic hydroxyl groups in one molecule, such as bisphenol A, bisphenol F, bisphenol S, novolac-type phenolic resin, poly-p-hydroxystyrene, a condensate of naphthol and aldehydes, or a condensate of dihydroxynaphthalene and aldehydes, with an alkylene oxide such as ethylene oxide or propylene oxide, with an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0027] (11) A carboxyl group-containing photosensitive resin obtained by reacting an unsaturated group-containing monocarboxylic acid with a reaction product obtained by reacting a compound having two or more phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0028] (12) A carboxyl group-containing photosensitive resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to one or more resins selected from the group consisting of any of (1) to (11) above.

[0029] When the alkali-soluble resin is a carboxyl group-containing resin, the acid value thereof is preferably 40 to 150 mgKOH / g. By setting the acid value of the carboxyl group-containing resin to 40 mgKOH / g or more, good alkali developability can be obtained. Further, by setting the acid value to 150 mgKOH / g or less, it becomes easy to draw a normal cured product pattern. The acid value of the carboxyl group-containing resin is more preferably 50 to 130 mgKOH / g.

[0030] There is no particular limitation on the phenolic hydroxyl group-containing resin as long as it has a phenolic hydroxyl group in the main chain or a side chain, that is, a hydroxyl group bonded to a benzene ring. The phenolic hydroxyl group-containing resin is preferably a resin containing two or more phenolic hydroxyl groups in one molecule. Examples of resins containing two or more phenolic hydroxyl groups in one molecule include, but are not limited to: catechol, resorcinol, hydroquinone, dihydroxytoluene, naphthalenediol, t-butylcatechol, t-butylhydroquinone, pyrogallol, phloroglucinol, bisphenol A, bisphenol F, bisphenol S, biphenol, bixylenol, novolac-type phenol resins, novolac-type alkylphenol resins, novolac resins of bisphenol A, dicyclopentadiene-type phenol resins, Xylok-type phenol resins, terpene-modified phenol resins, polyvinylphenols, condensates of phenols and aromatic aldehydes having a phenolic hydroxyl group, condensates of 1-naphthol or 2-naphthol and aromatic aldehydes, and the like.

[0031] Although the weight average molecular weight of the alkali-soluble resin varies depending on the resin skeleton, it is generally preferably 1,500 to 150,000, and more preferably 2,000 to 100,000. By setting the weight average molecular weight to 1,500 or more, at least one of tack-free performance and resolution can be improved. Further, by setting the weight average molecular weight to 150,000 or less, at least one of developability and storage stability can be improved. The weight average molecular weight (Mw) can be determined from a standard polystyrene conversion value measured by gel permeation chromatography (GPC).

[0032] The content of the alkali-soluble resin, in terms of solid content relative to the total amount of the curable resin composition, can be, for example, 15 to 60% by mass, preferably 20 to 60% by mass, and more preferably 20 to 55% by mass. When the content is 15% by mass or more, preferably 20% by mass or more, the strength of the cured product can be improved. Further, by setting the content of the alkali-soluble resin to 60% by mass or less, the viscosity becomes favorable and processability is improved.

[0033] [Photopolymerization Initiator] The photopolymerization initiator in the present invention is a compound represented by the following general formula (1).

[0034] The substitution position of the oxime ester group in the phenothiazine skeleton is not limited, but one preferred example is the position represented by the following general formula (2).

[0035] In the above general formulas (1) and (2), R1 represents a hydrogen atom (unsubstituted) or a substituent. Examples of R1 include C1-C12 alkyl groups (unsubstituted, or substituted with one or more halogen atoms, OH groups, alkoxy groups, phenyl groups, halogenated phenyl groups, or interrupted by an oxygen atom or -NH(CO)-), C1-C8 alkoxy groups, C5-C8 cycloalkyl groups (unsubstituted, or substituted with C1-C6 alkyl groups or phenyl groups), aryl groups, aralkyl groups, or heterocyclic groups. From the viewpoint of photocurability, R1 is preferably a linear or branched alkyl group. In the above general formulas (1) and (2), R2 represents a hydrogen atom (unsubstituted) or a substituent. Examples of R2 include C1-C12 alkyl groups (unsubstituted, or substituted with one or more halogen atoms, OH groups, alkoxy groups, phenyl groups, halogenated phenyl groups, or interrupted by an oxygen atom or -NH(CO)-), C1-C8 alkoxy groups, and aryl groups. Among these, from the viewpoint of rust prevention, R2 is preferably a hydrogen atom (unsubstituted). In the above general formulas (1) and (2), R3 represents a hydrogen atom (unsubstituted) or a substituent. In particular, R3 can be an alkyl group (unsubstituted, or substituted with one or more halogen atoms, OH groups, alkoxy groups, phenyl groups, halogenated phenyl groups, or interrupted by an oxygen atom or -NH(CO)-), C1-C8 alkoxy groups, and aryl groups. In the above general formulas (1) and (2), R4 is a hydrogen atom (unsubstituted) or various functional groups.Examples of functional groups include halogen atoms (fluorine, chlorine, bromine, iodine, etc.), hydroxyl groups, acidic groups (carboxyl groups, sulfonic acid groups, phenolic hydroxyl groups, thiol groups, phosphate groups, phosphonic acid groups, etc.) Phosphinic acid group, sulfonamide group, etc.), organic groups having aromatic rings (phenyl group, thienyl group, naphthyl group, acenes, organic groups having heteroaromatic rings, etc.), acyl group having 1 to 10 carbon atoms, alkoxycarbonyl group having 1 to 10 carbon atoms, alkyl group having 1 to 10 carbon atoms, cycloalkyl group having 3 to 12 carbon atoms, aryl group having 6 to 16 carbon atoms, aralkyl group having 6 to 12 carbon atoms, alkoxy group having 1 to 10 carbon atoms, hydroxyalkoxy group having 1 to 10 carbon atoms, cycloalkoxy group having 3 to 12 carbon atoms, aryloxy group having 6 to 12 carbon atoms, aralkyloxy group having 6 to 12 carbon atoms, alkylthio group having 1 to 10 carbon atoms, cycloalkylthio group having 3 to 12 carbon atoms, arylthio group having 6 to 12 carbon atoms, aralkylthio group having 6 to 12 carbon atoms, cyano group, nitro group, amino group (-NRA RB [the RA and RB Each is independently a hydrogen atom (unsubstituted) or an alkyl group having 1 to 10 carbon atoms. ]), -NH-C(=O)-RC [where RC is an alicyclic hydrocarbon group having 5 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms. ], -NH-SO. ２ Examples include -RD [where RD is synonymous with RC in -NH-C(=O)-RC]. Preferred are hydrogen atoms (unsubstituted), acetyl groups, nitro groups, alkoxy groups having 1 to 6 carbon atoms, alkyl groups having 1 to 6 carbon atoms, phenyl groups, and thienyl groups. More preferred are hydrogen atoms (unsubstituted), acetyl groups, nitro groups, and thienyl groups. These can be selected for the purpose of adjusting to the required starting wavelength. From the viewpoint of lengthening the absorption wavelength, electron-withdrawing functional groups or functional groups that extend the conjugated system of the phenothiazine skeleton are preferred, and from the viewpoint of shortening the absorption wavelength, electron-donating functional groups are preferred.

[0036] The content of the photopolymerization initiator is preferably 0.02 to 20 parts by mass, more preferably 0.03 to 20 parts by mass, even more preferably 0.04 to 19 parts by mass, and particularly preferably 0.1 to 15 parts by mass, based on solid content, per 100 parts by mass of alkali-soluble resin. When the content is 0.02 parts by mass or more, good surface hardening is achieved, and when it is 20 parts by mass or less, halation is less likely to occur and good resolution can be obtained.

[0037] The curable resin composition of the present invention contains only the above-mentioned photopolymerization initiator as a photopolymerization initiator, but may also contain one or more other known photopolymerization initiators, as long as they do not interfere with its properties. Examples of such known photopolymerization initiators include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4 Bisacylphosphine oxides such as trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphine methyl ester, 2-methylbenzoyldiphenylphosphine oxide Monoacylphosphine oxides such as pivaloylphenylphosphinate isopropyl ester and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-hydroxy-2-methyl Hydroxyacetophenones such as -1-phenylpropan-1-one; benzoins such as benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michlar's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone-1, Acetophenones such as tanone and N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, and 2-amylanthraquinone Anthraquinones such as 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoate ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)], etanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetylo Examples include oxime esters such as xime; titanosenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc.

[0038] [Thermosetting Compounds] The curable resin composition of the present invention contains thermosetting compounds. The thermosetting compounds improve the heat resistance of the cured product and also improve adhesion to the substrate. Known and conventional thermosetting compounds such as isocyanate compounds, blocked isocyanate compounds, amino resins, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy compounds, polyfunctional oxetane compounds, and episulfide resins can be used as thermosetting compounds. Among these, epoxy compounds, polyfunctional oxetane compounds, and episulfide resins are preferred, and epoxy compounds are more preferred. The thermosetting compounds can be used individually or in combination of two or more.

[0039] The epoxy compounds mentioned above are compounds having epoxy groups, and any conventionally known ones can be used. Examples include polyfunctional epoxy resins having multiple epoxy groups in the molecule. Hydrogenated epoxy resins may also be used.

[0040] Polyfunctional epoxy resins include bisphenol A type epoxy resin; hydroquinone type epoxy resin; bisphenol type epoxy resin; thioether type epoxy resin; brominated epoxy resin; novolac type epoxy resin; biphenol novolac type epoxy resin; bisphenol F type epoxy resin; hydrogenated bisphenol A type epoxy resin; glycidylamine type epoxy resin; hydantoin type epoxy resin; alicyclic epoxy resin; trihydroxyphenylmethane type epoxy resin; alkylphenol type epoxy resin (e.g., bixylenol type epoxy resin); biphenol type epoxy resin; bisphenol S type epoxy resin; Examples of epoxy resins include, but are not limited to, bisphenol A novolac type epoxy resins; tetraphenyloleethane type epoxy resins; heterocyclic epoxy resins; diglycidyl phthalate resins; tetraglycidyl xylenoylethane resins; naphthalene group-containing epoxy resins; epoxy resins having a dicyclopentadiene skeleton; triphenylmethane type epoxy resins; epoxy resins having a silsesquioxane skeleton; glycidyl methacrylate copolymer epoxy resins; copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate; epoxy-modified polybutadiene rubber derivatives; and CTBN-modified epoxy resins. These epoxy resins can be used individually or in combination of two or more. Among these, at least one of novolac type epoxy resins, bisphenol type epoxy resins, bixylenol type epoxy resins, biphenol type epoxy resins, biphenol novolac type epoxy resins, naphthalene type epoxy resins, epoxy resins having a silsesquioxane skeleton, and triphenylmethane type epoxy resins, or mixtures thereof, are particularly preferred.

[0041] Examples of polyfunctional oxetane compounds include bis[(3-methyl-3-oxetanylmethoxy)methyl] ether, bis[(3-ethyl-3-oxetanylmethoxy)methyl] ether, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, (3-methyl-3-oxetanyl)methyl acrylate, (3-ethyl-3-oxetanyl)methyl Examples include polyfunctional oxetanes such as acrylates, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and their oligomers or copolymers, as well as ethers of oxetane alcohols with resins having hydroxyl groups such as novolac resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring with alkyl (meth)acrylates.

[0042] Examples of episulfide resins include bisphenol A type episulfide resins. Furthermore, episulfide resins obtained by replacing the oxygen atoms in the epoxy groups of novolac-type epoxy resins with sulfur atoms using a similar synthesis method can also be used.

[0043] The content of the thermosetting compound is preferably 3.0 to 30% by mass, more preferably 4.0 to 25% by mass, and even more preferably 5.0 to 20% by mass, based on the solid content of the total curable resin composition.

[0044] [Inorganic Filler] The curable resin composition of the present invention may further contain an inorganic filler. The inorganic filler is preferably used to improve various properties of the photosensitive resin composition, such as adhesion, heat resistance, and coating strength. The inorganic filler is not particularly limited and any inorganic filler known to those skilled in the art may be used. These inorganic fillers can be used individually or in combination of two or more. Furthermore, the inorganic filler may be surface-treated or unsurface-treated.

[0045] The average particle size of the inorganic filler can be, for example, 0.1 to 10.0 μm, preferably 0.1 to 2.0 μm. In this specification, the average particle size of the inorganic filler is the average particle size (D50) which includes not only the particle size of the primary particles but also the particle size of the secondary particles (aggregates), and is the value of D50 measured by laser diffraction. An example of a laser diffraction measuring device is the Microtrac MT3300EXII manufactured by Microtrac-Bell Corporation.

[0046] The average particle size of the inorganic filler can be adjusted, and it is preferable to adjust it by pre-dispersing it using, for example, a bead mill or jet mill. Furthermore, it is preferable to formulate the inorganic filler in a slurry state, as this facilitates high dispersion, prevents aggregation, and makes handling easier.

[0047] The inorganic filler content is preferably 10 to 70% by mass, and more preferably 15 to 70% by mass, based on the solid content relative to the total amount of the curable resin composition.

[0048] [Photopolymerizable monomer] The curable resin composition of the present invention may further contain a photopolymerizable monomer. Examples of photopolymerizable monomers include compounds having one or more ethylenically unsaturated bonds in their molecules. The photopolymerizable monomer assists in the photocuring of alkali-soluble resins (especially carboxyl group-containing resins) by irradiation with active energy rays such as ultraviolet light.

[0049] Examples of compounds used as photopolymerizable monomers include conventionally known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, and the like.

[0050] The content of photopolymerizable monomers can be, for example, 15% by mass or less on a solid content basis relative to the total amount of curable resin composition, preferably 1 to 15% by mass, more preferably 1 to 10% by mass, and even more preferably 3 to 9% by mass.

[0051] (Thermosetting Catalyst) The curable resin composition of the present invention may contain a thermosetting catalyst within a range that does not impair the properties of the present invention. Examples of such thermosetting catalysts include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; 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 adipic acid dihydrazide and sebacate dihydrazide; and phosphorus compounds such as triphenylphosphine. Furthermore, guanamine, acetoganaamine, and benzoguanamine can also be used, and preferably these compounds, which also function as adhesion promoters, can be used in combination with the thermosetting catalyst. As can be seen from this, the thermosetting catalyst may be used alone or in combination of two or more types.

[0052] The content of the thermosetting catalyst can be, in terms of solid content, for example, more than 0 and up to 20 parts by mass per 100 parts by mass of the thermosetting compound, preferably 0.05 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass.

[0053] (Melamine) The curable resin composition of the present invention preferably does not contain melamine, but it may contain a small amount of melamine as long as it does not impair the properties of the present invention. If melamine is contained, the content is preferably 3.0% by mass or less, and more preferably 2.5% by mass or less, on a solid content basis relative to the total amount of the curable resin composition.

[0054] (Curing Agent) The curable resin composition of the present invention may contain a curing agent. Examples of curing agents include phenolic resins, polycarboxylic acids and their acid anhydrides, cyanate ester resins, activated ester resins, maleimide compounds, alicyclic olefin polymers, and the like. One curing agent may be used alone or two or more may be used in combination.

[0055] (Coloring agent) The curable resin composition of the present invention may contain a coloring agent. Known coloring agents such as red, blue, green, yellow, black, and white can be used as the coloring agent, and may be pigments, dyes, or colorants. However, from the viewpoint of reducing environmental impact and affecting the human body, it is preferable that the coloring agent does not contain halogens.

[0056] There are no particular restrictions on the amount of coloring agent, but usually, based on solid content, it is sufficient to have 10 parts by mass or less, and more preferably 0.1 to 7 parts by mass, per 100 parts by mass of alkali-soluble resin.

[0057] (Organic Solvents) The curable resin composition of the present invention may contain organic solvents for purposes such as preparing the composition and adjusting the viscosity when applying it to a substrate or carrier film (hereinafter also referred to as the "first film"). As organic solvents, known and commonly used organic solvents can be used, such as ketones like methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons like toluene, xylene, and tetramethylbenzene; glycol ethers like cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters like ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons like octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used individually or in combination of two or more types.

[0058] (Other Optional Components) Furthermore, the curable resin composition of the present invention may contain other additives known and commonly used in the field of electronic materials. Examples of other additives include thermal polymerization inhibitors, ultraviolet absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, anti-aging agents, antibacterial and antifungal agents, defoaming agents, leveling agents, thickeners, adhesion promoters, thixotropic agents, photoinitiator aids, sensitizers, thermoplastic resins, organic fillers, mold release agents, surface treatment agents, dispersants, dispersion aids, surface modifiers, stabilizers, phosphors, AB-type or ABA-type block copolymers, and the like.

[0059] [Dry Film] The curable resin composition of the present invention can be made into a dry film. The dry film of the present invention has a first film and a resin layer made of the curable resin composition of the present invention laminated on at least one side of the front and back of the first film. The first film in the present invention is adhered to the resin layer made of the curable resin composition, and is at least adhered to the resin layer when it is laminated onto a substrate so that the resin layer side of the dry film is in contact with the substrate for integral molding. The first film may be peeled off from the resin layer in a process after lamination. In particular, in the present invention, it is preferable to peel it off from the resin layer in a process after exposure. When forming a dry film, first, the curable resin composition of the present invention is diluted with the above organic solvent to adjust to an appropriate viscosity, and then applied to the first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, etc. Subsequently, the coated composition can be dried at a temperature of, for example, 40 to 130°C for 1 to 30 minutes to form a resin layer, which can then be laminated onto the first film. There are no particular restrictions on the coating thickness, but generally, the film thickness after drying can be appropriately selected within the range of 3 to 150 μm, preferably 5 to 60 μm.

[0060] As the first film, a plastic film can be used, such as a polyester film like polyethylene terephthalate (PET), a polyimide film, a polyamide-imide film, a polypropylene film, or a polystyrene film. A laminate of these films can also be used as the first film. There are no particular restrictions on the thickness of the first film, but it can generally be appropriately selected in the range of 10 to 150 μm, and more preferably in the range of 15 to 130 μm.

[0061] After laminating a resin layer made of the curable resin composition of the present invention onto the first film, it is preferable to further laminate a peelable cover film (hereinafter also referred to as the "second film") onto the surface of the resin layer for purposes such as preventing dust from adhering to the surface of the resin layer. The second film in the present invention refers to a film that is peeled off from the resin layer before lamination when integrally forming by laminating a dry film onto a substrate by heating or the like so that the resin layer side of the dry film is in contact with it. Examples of peelable second films include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper. The second film should be such that when peeled off, its adhesive strength is less than that between the resin layer and the first film. There are no particular restrictions on the thickness of the second film, but it can generally be appropriately selected within the range of 5 to 100 μm.

[0062] In addition, in the present invention, a resin layer may be formed by applying and drying the curable resin composition of the present invention on the second film, laminating it on the second film, and then laminating the first film on its surface. That is, in the present invention, when manufacturing a dry film, either the first film or the second film may be used as the film to which the curable resin composition of the present invention is applied.

[0063] [Electronic Components] The electronic components of the present invention have a cured product obtained from the curable resin composition of the present invention or a resin layer of a dry film. Here, "electronic components" means components used in electronic circuits, and include active components such as printed circuit boards, transistors, light-emitting diodes, and laser diodes, as well as passive components such as resistors, capacitors, inductors, and connectors, and the cured product layer made from the curable resin composition of the present invention is what provides the effects of the present invention.

[0064] [Method for Manufacturing Cured Products] The electronic components of the present invention have a cured product obtained from the curable resin composition of the present invention or from the resin layer of a dry film. In the present invention, electronic components mean components used in electronic circuits, and include active components such as printed circuit boards, transistors, light-emitting diodes, and laser diodes, as well as passive components such as resistors, capacitors, inductors, and connectors. The cured products obtained from the curable resin composition of the present invention serve as insulating cured films for these components and exert the effects of the present invention.

[0065] The cured product of the present invention can be manufactured, for example, as follows. That is, the curable resin composition of the present invention is adjusted to a viscosity suitable for the coating method using the above-mentioned organic solvent, and then applied to a substrate by methods such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating. After that, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer (cured product) on the substrate. In the case of a dry film, the resin layer of the dry film is bonded to the substrate using a laminator or the like so that it comes into contact with the substrate, and then the first film is peeled off to form a resin layer on the substrate described later.

[0066] Specifically, the above-mentioned substrates include printed circuit boards and flexible printed circuit boards with circuits pre-formed using copper, as well as copper-clad laminates, metal substrates, polyimide substrates such as polyimide films, PET substrates such as PET films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafers, and the like.

[0067] The volatilization drying performed after applying the curable resin composition of the present invention can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air inside the dryer is brought into countercurrent contact with a heat source equipped with a steam-heated air heating method, and a method in which hot air is blown onto the support from a nozzle).

[0068] In the case of dry films, lamination to the substrate is preferably performed under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, even if the surface of the circuit board has irregularities when a circuit-formed substrate is used, the resin layer of the dry film adheres closely to the surface of the circuit board, preventing the inclusion of air bubbles and improving the ability to fill in depressions on the substrate surface. The pressure is preferably around 0.1 to 2.0 MPa, and the heating is preferably around 40 to 120°C.

[0069] During exposure, the cured material side of the substrate is selectively exposed with active energy rays through a photomask with a predetermined pattern. Then, in the case of a dry film, the first film is peeled off from the dry film, and the unexposed areas are developed with a dilute alkaline aqueous solution (for example, a 0.3 to 3% by mass sodium carbonate aqueous solution at 30°C) (for example, for 30 to 180 seconds) to form the pattern of the cured material. In the case of a dry film, exposure can be performed without peeling off the first film from the dry film, or, as long as the properties are not impaired, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed.

[0070] Furthermore, by irradiating the cured material with active energy rays and then heat-curing it (for example, at 100-220°C), or by irradiating it with active energy rays after heat curing, or by performing final finishing curing (main curing) by heat curing alone, it is possible to form a cured material with excellent properties such as adhesion and hardness.

[0071] The exposure machine used for the above-mentioned active energy ray irradiation can be any device equipped with a high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, mercury short-arc lamp, etc., that irradiates ultraviolet light in the range of 350 to 450 nm. Furthermore, a direct writing device (for example, a laser direct imaging device that directly draws images with a laser using CAD data from a computer) can also be used. The lamp light source or laser light source of the direct writing device can have a maximum wavelength in the range of 350 to 450 nm. The exposure amount for image formation varies depending on the film thickness, etc., but is generally 10 to 1000 mJ / cm². ２ Preferably 20 to 800 mJ / cm² ２ It can be within the range of

[0072] The above-mentioned development method can be the dipping method, shower method, spray method, brush method, etc., and alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines can be used as the developing solution.

[0073] Furthermore, by curing the cured material using either active energy ray irradiation or heating, or both (final curing), a cured material with excellent properties such as adhesion and hardness can be formed. The order and number of times active energy ray irradiation and heating are performed can be selected as appropriate. Curing by active energy ray irradiation can be performed in the same manner as the exposure described above, but it is preferable to perform it under conditions with a stronger irradiation energy than that used during exposure. For example, 500 mJ / cm². ２ ~3,000mJ / cm ２This can be done. Furthermore, curing by heating can be carried out under heating conditions of 100°C to 200°C for about 20 to 90 minutes. The film thickness of the formed cured product is preferably 10 to 40 μm, which satisfies various properties required for solder resist, such as insulation.

[0074] When the cured product of the present invention obtained above is used as a solder resist for printed circuit boards, etc., it does not cause discoloration (haloing phenomenon) around the solder resist openings after electroless gold plating. The reason for this effect is not entirely clear, but it is presumed that the phenothiazine skeleton present in the photopolymerization initiator takes on a planar structure by having radicals after exposure, and reacts with the metal on the substrate to bond or adhere strongly. Furthermore, the curable resin composition of the present invention has high stability over time, making it effective in improving yield during substrate manufacturing.

[0075] Therefore, the curable resin composition of the present invention and the dry film having a resin layer obtained from this curable resin composition can be suitably used to form cured products on printed wiring boards used for semiconductor packages and the like, more preferably to form permanent films, and even more preferably to form solder resists, interlayer insulating layers, and coverlays. Furthermore, since the cured product of the present invention does not exhibit discoloration (haloing phenomenon) around the solder resist openings after electroless gold plating, it can be suitably used, for example, to form permanent films such as solder resists used in high-density IC package substrates.

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the following, "parts" and "%" all refer to mass unless otherwise specified.

[0077] (Synthesis of alkali-soluble resin A-1) In an autoclave equipped with a thermometer, a nitrogen introduction device / alkylene oxide introduction device, and a stirring device, 119.4 parts by mass of novolac-type cresol resin (product name "Shounol CRG951", manufactured by Aica Kogyo Co., Ltd., OH equivalent: 119.4), 1.19 parts by mass of potassium hydroxide, and 119.4 parts by mass of toluene were introduced. The system was then heated and the temperature increased while stirring and purged with nitrogen. Next, 63.8 parts by mass of propylene oxide were gradually added dropwise to 125-132°C and 0-4.8 kg / cm³. ２ The reaction was carried out for 16 hours. After cooling to room temperature, 1.56 parts by mass of 89% phosphoric acid was added to the reaction solution and mixed to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac-type cresol resin with a solid content of 62.1% and a hydroxyl value of 182.2 mg KOH / g (307.9 g / eq.). This solution contained an average of 1.08 moles of propylene oxide added per equivalent of phenolic hydroxyl groups.

[0078] 293.0 parts by mass of the propylene oxide reaction solution of the obtained novolac-type cresol resin, 43.2 parts by mass of acrylic acid, 11.53 parts by mass of methanesulfonic acid, 0.18 parts by mass of methylhydroquinone, and 252.9 parts by mass of toluene were introduced into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and the mixture was reacted at 110°C for 12 hours while stirring. Of the water produced by the reaction, 12.6 parts by mass of water was distilled off as an azeotropic mixture with toluene. The mixture was then cooled to room temperature, and the resulting reaction solution was neutralized with 35.35 parts by mass of a 15% sodium hydroxide aqueous solution, followed by washing with water. Subsequently, toluene was removed by distillation in an evaporator while substituting it with 118.1 parts by mass of diethylene glycol monoethyl ether acetate to obtain a novolac-type acrylate resin solution.

[0079] Next, 332.5 parts by mass of the obtained novolac-type acrylate resin solution and 1.22 parts by mass of triphenylphosphine were introduced into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and while stirring, 60.8 parts by mass of tetrahydrophthalic anhydride were gradually added. The mixture was reacted at 95-101°C for 6 hours, and after cooling, it was removed. In this way, a solution of alkali-soluble resin A-1 (photosensitive carboxyl group-containing resin) with a solid content of 70.6% and an acid value of 87.7 mg KOH / g of the solid content was obtained.

[0080] (Synthesis of Intermediate 1) 60 mL of dry THF (tetrahydrofuran) was mixed with phenothiazine (10 g, 50.2 mmol) and potassium tert-butoxide (8.44 g, 75.4 mmol). The suspension was stirred for 10 minutes, and then iodomethane (10.7 g, 75.4 mmol) was added dropwise to obtain a solution. This solution was stirred overnight at room temperature, then pentane (100 mL) was added, and the entire mixture was filtered through a silica gel column. After removing the solvent from the filtered fraction under reduced pressure, intermediate 1 was obtained by recrystallization (ether / pentane) (10.0 g, yield 93%). １ ¹H NMR spectroscopy confirmed that the obtained intermediate 1 is represented by the following structural formula (3). １ H-NMR (400MHz, CHLOROFORM-d) δ7.21-7.13 (m, 4H), 6.94 (td, 2H), 6.82 (d, 2H), 3.38 (s, 3H)

[0081] (Synthesis of Intermediate 2) Phosphoryl chloride (8.97 g, 58.5 mmol) was slowly added to 8 mL of dry DMF (dimethylformamide) at 0° C., and the mixture was stirred at room temperature for 2 hours. Next, a solution of Intermediate 1 (6.08 g, 28.5 mmol) dissolved in 1,2-dichloroethane (50 mL) was added, and after an additional 1 hour, the reaction mixture was heated at 90° C. for 15 hours. Finally, the solution was cooled and poured into 300 mL of water. The product was extracted with dichloromethane (100 mL × 3), dried over anhydrous magnesium sulfate, then the solvent was removed, and the residue was purified by column chromatography using dichloromethane as an eluent to obtain Intermediate 2 (10.5 g, yield 74%). １ It was confirmed by ¹H NMR spectrum measurement that the obtained Intermediate 2 is represented by the following structural formula (4). １ ¹H-NMR (400 MHz, CHLOROFORM-d) δ 9.80 (s, 1H), 7.65 (dd, 1H), 7.60 (d, 1H), 7.19 (m, 1H), 7.13 (dd, 1H), 6.98 (td, 1H), 6.88-6.82 (m, 2H), 3.42 (s, 3H)

[0082] (Synthesis of Intermediate 3) Intermediate 2 (0.19 g, 0.79 mmol), hydroxylamine hydrochloride (0.11 g, 1.58 mmol) and sodium acetate (0.13 g, 1.58 mmol) were dissolved in a mixed solvent of methanol:water:THF (50 / 10 / 10), the solution was refluxed overnight, then the solvent was removed under reduced pressure. A precipitate formed during solvent evaporation. This was filtered, washed several times with water, and dried under vacuum to obtain the product. The product was obtained in quantitative yield. １ It was confirmed by ¹H NMR spectrum measurement that the obtained Intermediate 3 is represented by the following structural formula (5). １ ¹H-NMR (400 MHz, CHLOROFORM-d) δ 8.02 (s, 1H), 7.39-7.31 (m, 3H), 7.21-7.11 (m, 2H), 6.95 (td, 1H), 6.82 (dd, 1H), 6.80-6.76 (m, 1H), 3.39 (s, 3H).

[0083] (Synthesis of Initiator B-1) Intermediate 3 (1.53 g, 6.0 mmol) and dried triethylamine (4.5 mL) were dissolved in anhydrous dichloromethane (100 mL). Next, acetyl chloride (465 mg, 6.0 mmol) was added to this solution and stirred overnight at room temperature under a nitrogen atmosphere. After that, the solution was washed with water and dried over magnesium sulfate. The resulting yellow precipitate was filtered after removing the solvent, washed several times with pentane, and dried under vacuum to obtain initiator B-1 (1.13 g, yield 63%). １ ¹H NMR spectroscopy confirmed that the obtained initiator B-1 has the structure represented by the following structural formula (6). １ H-NMR (400MHz, CHLOROFORM-d) δ8.22 (s, 1H), 7.52-7.48 (m, 2H), 7.21-7. 12 (m, 2H), 7.00-6.94 (m, 1H), 6.84-6.79 (m, 2H), 3.40 (s, 3H), 2.22 (s, 3H)

[0084] (Synthesis of Intermediate 4) Intermediate 2 (4.06 g, 16.8 mmol) was dissolved in glacial acetic acid (100 mL) and treated with a solution of fuming nitric acid (4 mL) in glacial acetic acid (16 mL) to obtain the reaction mixture. The reaction mixture was left at room temperature overnight. The solvent was then removed under reduced pressure, and the product was extracted with dichloromethane. The organic phase was washed several times with water and dried under vacuum (2.9 g, 60% yield). １ ¹H NMR spectroscopy confirmed that the obtained intermediate 4 is represented by the following structural formula (7). １ H-NMR (400 MHz, CHLOROFORM-d) δ10.07 (s, 1H), 8.92 (d, 1H), 8.58 (dd, 1H), 8.53 (d, 1H), 8.29 (dd, 1H), 7.69 (d, 1H), 7.64 (d, 1H), 3.99 (s, 3H)

[0085] (Synthesis of Intermediate 5) Intermediate 4 (0.21 g, 0.72 mmol), hydroxylamine hydrochloride (0.1 g, 1.44 mmol), and sodium acetate (0.12 g, 1.44 mmol) were dissolved in a mixed solvent of ethanol:water:THF (50 / 10 / 10). The solution was refluxed overnight, and the solvent was removed under reduced pressure. The residue was suspended in dichloromethane, filtered, washed three times with dichloromethane, and dried under vacuum. An oily substance was obtained in crude yield of 81% (0.18 g). １ ¹H NMR spectroscopy confirmed that the obtained intermediate 5 is represented by the following structural formula (8). １ H-NMR (400MHz, CHLOROFORM-d) δ11.38 (s, 1H), 8.90 (d, 1H), 8.49 (dd, 1H) , 8.28 (d, 1H), 8.20 (d, 1H), 8.02 (dd, 1H), 7.84-7.76 (m, 2H), 3.90 (s, 3H)

[0086] (Synthesis of Initiator B-2) Intermediate 5 (1.0 g, 3.3 mmol) and 2.5 mL of dried triethylamine were dissolved in 80 mL of anhydrous dichloromethane. Next, acetyl chloride (257 mg, 3.3 mmol) was added to this solution and stirred overnight at room temperature under a nitrogen atmosphere. Subsequently, this solution was washed with water and dried over magnesium sulfate. The resulting yellow precipitate was filtered after evaporation of the solvent, washed several times with pentane, and dried under vacuum to obtain initiator B-2 (0.95 g, yield 83%). １ ¹H NMR spectroscopy confirmed that the obtained initiator B-2 is represented by the following structural formula (9). １ H-NMR (400 MHz, CHLOROFORM-d) δ8.87 (t, 1H), 8.51-8.47 (m, 1H), 8.44 (s, 1H), 8. 25 (d, 1H), 8.19-8.15 (m, 1H), 7.54 (d, 1H), 7.52 (d, 1H), 3.91 (d, 3H), 2.25 (d, 3H)

[0087] (Synthesis of Intermediate 6) Intermediate 1 (2.00 g, 8.36 mmol) was dissolved in 1,2-dichloroethane (50 mL), and anhydrous iron(III) chloride (1.63 g, 10.0 mmol) was added under a nitrogen atmosphere. The temperature was raised to 50°C and held there, and acetyl chloride (0.78 g, 10.0 mmol) was gradually added over 30 minutes, after which the temperature was raised to 70°C and stirred for 2 hours. Finally, this solution was cooled and poured into 200 mL of water. The product was then extracted with dichloromethane (100 mL x 3), dried over anhydrous magnesium sulfate, the solvent was removed, and the residue was purified by column chromatography with dichloromethane as the eluent to obtain intermediate 6 (1.7 g, yield 72%). １ ¹H NMR spectroscopy confirmed that the obtained intermediate 6 is represented by the following structural formula (10). １ H-NMR (400MHz, CHLOROFORM-d) δ7.64 (dd, 1H), 7.59 (d, 1H), 7.20-7.08 ( m, 2H), 7.00-6.93 (m, 1H), 6.92-6.85 (m, 2H), 3.41 (s, 3H), 2.35 (s, 3H).

[0088] (Synthesis of Intermediate 7) Intermediate 6 (0.184 g, 0.72 mmol), hydroxylamine hydrochloride (0.1 g, 1.44 mmol), and sodium acetate (0.12 g, 1.44 mmol) were dissolved in a mixed solvent of ethanol:water:THF (50 / 10 / 10). The solution was refluxed overnight, and the solvent was removed under reduced pressure. A precipitate formed during the evaporation of the solvent. This precipitate was washed several times with water and dried under vacuum to obtain intermediate 7 (0.173 g, yield 89%). １ ¹H NMR spectroscopy confirmed that the obtained intermediate 7 is represented by the following structural formula (11). １ H-NMR (400MHz, CHLOROFORM-d) δ7.48 (s, 1H), 7.39-7.30 (m, 2H), 7.20-7.1 0 (m, 2H), 6.96-6.89 (m, 1H), 6.88-6.78 (m, 2H), 3.39 (s, 3H), 2.03 (s, 3H).

[0089] (Synthesis of Initiator B-3) Intermediate 7 (0.292 g, 1.08 mmol) and dried triethylamine (2.5 mL) were dissolved in anhydrous THF (20 mL). Next, acetyl chloride (0.128 g, 1.62 mmol) was added to this solution and stirred overnight at room temperature under a nitrogen atmosphere. After that, the solution was washed with water and dried over magnesium sulfate. The residue obtained by removing the solvent was purified by column chromatography with dichloromethane as the eluent to obtain initiator B-3 (0.236 g, yield 70%). １ ¹H NMR spectroscopy confirmed that the obtained initiator B-3 is represented by the following structural formula (12). １ H-NMR (400MHz, CHLOROFORM-d) δ7.50-7.48 (m, 2H), 7.20-7.10 (m, 2H), 7.00-6.94 (m, 1H), 6.92-6.85 (m, 2H), 3.03 (s, 3H), 2.27-2.22 (m, 6H).

[0090] (Preparation of Curable Resin Compositions) The various components shown in Table 1 were blended in the indicated proportions (parts by mass), pre-mixed in a stirrer, and then kneaded in a planetary stirrer to prepare the curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 4. The values ​​in Table 1 are based on solid content. The blending amounts in Table 1 are also based on solid content.

[0091]

[0092] In Table 1, OXE02 refers to Irgacure OXE02, a photopolymerization initiator manufactured by BASF Japan Ltd., and has the structure represented by the following formula (13).

[0093] The phenothiazines in Table 1 have the structure represented by the following formula (14).

[0094] In Table 1, thermosetting resin 1 is HP-7200L, a dicyclopentadiene type epoxy resin manufactured by DIC Corporation, and thermosetting resin 2 is VG3101L, a trifunctional epoxy resin manufactured by Air Water Inc.

[0095] The silica in Table 1 is Admatex Co., Ltd.'s Silica SO-C4 (average particle size 0.9-1.2 μm).

[0096] The acrylate monomer in Table 1 is ethoxylated dipentaerythritol polyacrylate (A-DPH-12E), manufactured by Shin Nakamura Kogyo Co., Ltd., which is a photopolymerizable monomer.

[0097] The melamine in Table 1 has a structure represented by the following formula (15).

[0098] (Preparation of Dry Film) Each of the curable resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 3 as described above was diluted with 150 g of propylene glycol monomethyl ether acetate (PMA), and stirred with a stirrer for 15 minutes to obtain a coating solution. This coating solution was applied to a first film, a polyethylene terephthalate film with a thickness of 38 μm (Emblet PTH-38: manufactured by Unitika Ltd.), and dried at a temperature of 80°C for 20 minutes to form a resin layer with a thickness of 20 μm. Next, a second film, a polypropylene film with a thickness of 18 μm (OPP-FOA: manufactured by Futamura Chemical Co., Ltd.), was laminated onto the resin layer to prepare a dry film.

[0099] (Evaluation of Haloing Resistance) A 17 μm thick electrolytic copper plating was applied to an FR-4.0 glass cloth substrate epoxy resin multilayer substrate material (1.6 mm thick, copper-clad laminate with 18 μm thick copper foil). This substrate was then etched to a thickness equivalent to 1.0 μm using CZ-8101B manufactured by MEC Corporation. Next, the second film was peeled from the resin layer of the dry film prepared in the above (dry film preparation) and the resin layer was bonded to the substrate. Lamination was performed in the first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.). After that, pressing was performed under conditions of a press pressure of 0.5 MPa and a press time of 30 seconds.

[0100] Next, exposure was performed using an exposure apparatus equipped with a high-pressure mercury lamp at aperture patterns of Φ40, 50, and 60 μm. The exposure amount was adjusted using a step tablet (Photec 41 step) so that the gloss sensitivity was 10 steps. After exposure, the first film was peeled off from the resin layer (including the cured material) of the dry film, exposing the resin layer.

[0101] Subsequently, 1% by mass of Na at 30°C ２ CO ３ Using an aqueous solution, spray pressure 2 kg / cm² ２ The substrate was developed for 30 seconds under the specified conditions to obtain a cured substrate. This substrate was then subjected to an integrated exposure of 1000 mJ / cm² in a UV conveyor oven. ２ After UV irradiation under the specified conditions, the substrate was heat-cured at 150°C for 60 minutes. Electroless gold plating (Ni: 3.00 μm, Au: 0.03 μm) was performed on the test substrate prepared according to this manufacturing process, and the discoloration (haloing) around the openings after electroless gold plating was observed using an optical microscope. The evaluation method is as follows. ◎ and ○ are considered passing criteria. ◎ No discoloration was observed. ○ Slight discoloration was observed. × Discoloration was observed. ×× Evaluation impossible due to poor resolution or insufficient curing.

[0102] (Evaluation of stability over time) A 17 μm thick electrolytic copper plating was applied to an FR-4.0 glass cloth substrate epoxy resin multilayer substrate material (1.6 mm thick, copper-clad laminate with 18 μm thick copper foil). This substrate was then etched to a thickness equivalent to 1.0 μm using CZ-8101B manufactured by MEC Corporation. Next, the dry film prepared as described above, and the dry film prepared as described above, which was exposed to room temperature for 24 hours, were each peeled off from the resin layer, and the resin layer was bonded to the substrate. Lamination was then performed in the first chamber at 90°C using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, followed by pressing under conditions of a press pressure of 0.5 MPa and a press time of 30 seconds.

[0103] Next, exposure was performed using an exposure apparatus equipped with a high-pressure mercury lamp, with an aperture pattern of Φ100 μm. The exposure amount was adjusted using a step tablet (Photec 41 step) so that the gloss sensitivity was 10 steps. After exposure, the first film was peeled off from the resin layer (including the cured material) of the dry film, exposing the resin layer.

[0104] Subsequently, 1% by mass of Na at 30°C ２ CO ３ Using an aqueous solution, spray pressure 2 kg / cm² ２ The substrate was developed for 30 seconds under the specified conditions to obtain a cured substrate. This substrate was then subjected to an integrated exposure of 1000 mJ / cm² in a UV conveyor oven. ２ After UV irradiation under the specified conditions, the substrate was heat-cured at 150°C for 60 minutes. The aperture size of the test substrate prepared according to this manufacturing process was observed with an optical microscope. The evaluation method is as follows. Among the evaluation criteria, ◎ and ○ are considered passing criteria. ◎ The aperture size of Φ100 μm was compared with and without exposure to room temperature, and the size variation from the design size (100 μm) was less than ±10%. ○ The aperture size of Φ100 μm was compared with and without exposure to room temperature, and the size variation from the design size (100 μm) was ±10% or more and less than ±15%. × The aperture size of Φ100 μm was compared with and without exposure to room temperature, and the size variation from the design size (100 μm) was ±15% or more.

[0105] The results in Table 1 show that the resin compositions of Examples 1 to 7 exhibit sufficient haloing resistance and long-term stability. In particular, a comparison of Example 1 with Comparative Example 1 revealed that Example 1, which contains the photopolymerization initiator having a phenothiazine skeleton of the present invention, enables the simultaneous achievement of haloing resistance and long-term stability, which was not possible with Comparative Example 1, which combined a conventional oxime ester initiator with melamine.

[0106] Furthermore, a comparison between Example 1 and Comparative Example 2 revealed that the use of the photopolymerization initiator and thermosetting compound having the phenothiazine skeleton of the present invention is important for the development of haloing resistance.

[0107] Furthermore, a comparison between Example 1 and Comparative Example 1 revealed that the melamine content in the curable resin composition tended to significantly reduce its stability over time.

[0108] The resin layer made from the curable resin composition of the present invention has a sufficiently long usable time at room temperature and high stability over time, making it suitable for use in the manufacture of electronic components such as substrates from the viewpoint of improving yield. Furthermore, the curable resin composition of the present invention can be suitably used in a wide range of applications such as the formation of solder resists, interlayer insulating layers, or coverlays. In addition, the cured product is less prone to discoloration (haloing phenomenon) around the solder resist openings after electroless gold plating and has excellent haloing resistance. For this reason, the curable resin composition of the present invention can be suitably used as a high-quality solder resist material for mounting substrates of high-density IC packages such as FC-BGA.

Claims

1. A curable resin composition containing an alkali-soluble resin, a photopolymerization initiator, and a thermosetting compound, wherein the photopolymerization initiator is of the following general formula (1): A curable resin composition that is a compound represented by the following formula (1) above: (In the above general formula (1), R1, R2, and R3 each independently represent a hydrogen atom (unsubstituted) or a substituent, and R4 represents a hydrogen atom (unsubstituted), an electron-withdrawing functional group, or a functional group that extends the conjugated system of the phenothiazine skeleton.) 2. The curable resin composition according to claim 1, wherein the content of the photopolymerization initiator is 0.02 to 20 parts by mass per 100 parts by mass of the alkali-soluble resin, on a solid content basis.

3. A dry film comprising a film and a resin layer made of the curable resin composition described in claim 1 or 2, laminated on at least one of the front and back surfaces of the film.

4. A cured product obtained by curing the curable resin composition according to claim 1 or 2.

5. A cured product obtained by curing the resin layer of the dry film described in claim 3.

6. An electronic component comprising the cured product described in claim 4.

7. An electronic component comprising the cured product described in claim 5.

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