TWI902637B - Curable resin composition, dry film, cured product, and printed wiring board - Google Patents

Abstract

A curable resin composition comprising (A) an alkaline soluble resin, (B) a photopolymerization initiator, (C) a thermosetting resin, and (D) a colorant, is formed on copper with a CZ-treated surface. The transmittance of the dried coating (20 μm thick) of the aforementioned curable resin composition formed on a glass substrate with a thickness of 2 mm is 30–50% at a wavelength of 430 nm and 28–45% at a wavelength of 530 nm.

Description

Curing resin compositions, dry films, cured materials, and printed circuit boards

This invention relates to curing resin compositions, dry films, curing materials, and printed wiring boards.

For example, in the manufacture of printed circuit boards, curable resin compositions are generally used in the formation of permanent films such as solder resist. Dry film and liquid compositions have been developed for these curable resin compositions. Among these, due to concerns about environmental issues, alkaline developing type curable resin compositions that use dilute alkaline aqueous solutions as the developer are the mainstream, and several composition systems have been proposed in the past (e.g., Patent 1).

In recent years, rapid advancements in semiconductor components have led to a trend towards smaller, thinner, and more compact electronic devices with higher performance and greater multifunctionality. Following this trend, the miniaturization and mass production of semiconductor packaging have become practical. Specifically, IC packaging types such as BGA (ball grid array) and CSP (chip scale package) are being used instead of QFP (quad flat pack package) and SOP (small outline package). Furthermore, in recent years, FC-BGA (flipchip ball grid array) has also become a more advanced form of high-density IC packaging. The permanent coating of solder resist and other materials formed in printed circuit boards (also known as packaging substrates) used in IC packaging requires further thinning. Furthermore, based on concealment and design considerations, solder resist is sometimes required to be black. Therefore, the curable resin composition used in solder resist may contain carbon black as a coloring agent, or may achieve a black appearance by combining pigments containing most colors other than black. [Prior Art Documents] [Patent Documents]

Patent Document 1: Japanese Patent Application Publication No. 61-243869 (Scope of Patent Application)

[Problems to be Solved by the Invention] Currently, most solder resists are photocured to form an image, followed by a heat-curing process. This heat-curing process sometimes causes copper circuits to discolor due to oxidation. Furthermore, when applying marking ink to the substrate, the subsequent printing and heat-curing of markings after the solder resist has cured may accelerate the discoloration of the copper circuits. Additionally, applying pressure and heat to correct substrate warping caused by the heat-curing of the solder resist can also lead to discoloration. This discoloration cannot be concealed with conventional black curable resin compositions, resulting in a deterioration of the substrate's appearance. Furthermore, even conventional hardened resin compositions that incorporate blue colorant to appear black by combining with the copper color of the copper circuit still lack sufficient concealment. This is especially true for copper circuits that have undergone CZ treatment to roughen the copper surface and improve adhesion; the concealment still has room for improvement. Moreover, in order to avoid resolution reduction due to the formulation of colorant and to achieve a high level of both concealment and resolution, solder resists previously required changes to components other than the color tone. Furthermore, when prioritizing resolution, the amount of black pigment added to maintain concealment had to be reduced. In such cases, depending on the hardening conditions, the color tone could change due to oxidation of the copper circuit.

Therefore, the purpose of this invention is to provide an alkali-developable curable resin composition that exhibits excellent concealment, minimal tonal variation after heating, and excellent resolution when a coating formed on copper after CZ treatment is heated; a dry film having a resin layer derived from the composition; a cured product of the composition or the resin layer of the dry film; and a printed circuit board having the cured product. [Means for Solving the Problem]

Based on the above and through active review, the inventors discovered that a hardened resin composition with a transmittance within a specific range under specific test conditions forms a coating on copper after CZ treatment that exhibits excellent concealment, minimal color variation after heating, and excellent resolution, thus completing this invention.

That is, the curable resin composition of this invention is characterized by containing (A) an alkaline-soluble resin, (B) a photopolymerization initiator, (C) a thermosetting resin, and (D) a colorant. It is a curable resin composition formed on a copper surface that has undergone CZ treatment. The transmittance of the dried coating (20 μm thick) of the aforementioned curable resin composition formed on a 2 mm thick glass substrate is 30–50% at a wavelength of 430 nm and 28–45% at a wavelength of 530 nm.

The curable resin composition of this invention has the advantage that the transmittance of the aforementioned dry coating is less than 12% at a wavelength of 720 nm.

The curable resin composition of this invention has a transmittance of more than 5% for the aforementioned dry coating at a wavelength of 365 nm.

The dry film of this invention is characterized by having a resin layer obtained from the aforementioned curing resin composition.

The characteristic of the hardened material of this invention is that it is obtained by hardening the aforementioned hardening resin composition or the resin layer of the aforementioned dry film.

The printed wiring of this invention is characterized by having the aforementioned hardened material. [Invention Effects]

According to the present invention, an alkaline-developable curable resin composition can be provided, which has excellent concealment, minimal color change after heating, and excellent resolution, resulting in a coating formed on copper after CZ treatment; a dry film having a resin layer obtained from the composition; a cured product of the resin layer of the composition or the dry film; and a printed circuit board having the cured product.

The curable resin composition of this invention is characterized by containing (A) an alkaline-soluble resin, (B) a photopolymerization initiator, (C) a thermosetting resin, and (D) a colorant. It is a curable resin composition formed on a copper surface that has undergone CZ treatment. The transmittance of the dried coating (20 μm thick) of the aforementioned curable resin composition formed on a 2 mm thick glass substrate is 30–50% at a wavelength of 430 nm and 28–45% at a wavelength of 530 nm. In one example, the red, yellow, blue, and black colorants in the curing resin composition were adjusted to achieve a transmittance of 30-50% at a wavelength of 430 nm and 28-45% at a wavelength of 530 nm when the coating was tested on a 2 mm thick glass substrate. The curable resin composition exhibiting this transmittance is neither the conventional black nor the conventional blue curable resin composition, but a novel curable resin composition. It is difficult to specify the colorant in a specific formulation ratio. Instead, it achieves a transmittance of 30-50% at 430nm and 28-45% at 530nm on a 2mm thick glass substrate, resulting in a dry coating of the aforementioned curable resin composition with a transmittance of 20μm thickness. This combination of transmittance and transmittance possesses the desired concealment and resolution of this invention. Therefore, the curable resin composition of this invention is characterized by its transmittance falling within a specific range under specific test conditions. Transmittance was measured by applying a 20 μm thick layer of the cured resin composition to a 2 mm thick glass substrate using a coating apparatus, or by laminating a 20 μm thick dry film onto a 2 mm thick glass substrate and then peeling it off from the carrier film. Measurements were performed using a V-670 UV-Vis-IR spectrophotometer (manufactured by Nippon Spectrophotometer Co., Ltd.). A preferred dry coating has a transmittance of less than 12% at a wavelength of 720 nm, which effectively suppresses color changes after heat treatment. A preferred dry coating has a transmittance of more than 5% at a wavelength of 365 nm, which improves resolution.

The following describes the components of the curing resin composition of the present invention. Furthermore, in this specification, the term (meth)acrylate is a general term for acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions.

[(A) Alkali-soluble resin] Examples of (A) alkali-soluble resins include compounds having two or more phenolic hydroxyl groups, carboxyl-containing resins, compounds having both phenolic hydroxyl and carboxyl groups, and compounds having two or more thiol groups. Among these, alkali-soluble resins that are carboxyl-containing or phenolic resins exhibit improved adhesion to the substrate and are therefore preferred. Especially due to their excellent imaging properties, alkali-soluble resins are more preferably carboxyl-containing resins. Carboxyl-containing resins are preferably carboxyl-containing photosensitive resins with vinyl unsaturated double bonds, but carboxyl-containing resins without vinyl unsaturated double bonds are also acceptable.

Specific examples of carboxyl-containing resins include the following compounds (both oligomers and polymers).

(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 esters of (meth)acrylic acid, and isobutylene.

(2) A carboxyl-containing aminocarbamate resin obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, cycloaliphatic diisocyanates, and aromatic diisocyanates, carboxyl-containing diol compounds such as dihydroxymethylpropionic acid and dihydroxymethylbutyric acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A epoxide adduct diols, and compounds having phenolic hydroxyl and alcoholic hydroxyl groups.

(3) A carboxyl-terminated urethane resin obtained by reacting the end of an acid anhydride with diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, cycloaliphatic diisocyanates, and aromatic diisocyanates with diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A epoxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

(4) A carboxyl-containing aminocarbamate resin obtained by polyaddition reaction of diisocyanate with (meth)acrylate or partially modified acid anhydride of difunctional 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., carboxyl-containing diol compound and diol compound.

(5) In the synthesis of the resin in (2) or (4) above, a carboxyl-containing amino ester resin is formed by adding a compound having one hydroxyl group and one or more (meth)acrylic groups in the molecule, such as hydroxyalkyl methacrylate, to the resin and terminally (meth)acrylate it.

(6) In the resin synthesis of (2) or (4) above, a carboxyl-containing amino ester resin is formed by adding a compound having one isocyanate group and one or more (meth)acrylic groups at the end of the molecule, such as isoflavone diisocyanate and pentaerythritol triacrylate.

(7) A carboxyl-containing resin is formed by reacting a multifunctional epoxy resin with (meth)acrylic acid to form a hydroxyl group on the side chain and adding dicarboxylic anhydride such as isophthalic anhydride, tetrahydroisophthalic anhydride, or hexahydroisophthalic anhydride.

(8) The hydroxyl group of the difunctional epoxy resin is further epoxidized by epichlorohydrin to react with (meth)acrylic acid, and the resulting hydroxyl group is added to form a carboxyl-containing resin of a dicarboxylic acid anhydride.

(9) A polyfunctional oxocyclobutane resin is reacted with a dicarboxylic acid to produce a carboxyl-containing polyester resin containing a primary hydroxyl addition dicarboxylic acid anhydride.

(10) A carboxyl-containing resin is obtained by reacting a compound containing multiple phenolic hydroxyl groups in 1 part with epoxides such as ethylene oxide and propylene oxide, and then reacting the product with a monocarboxylic acid containing an unsaturated group, and then reacting the product with a polyacid anhydride.

(11) A carboxyl-containing resin is obtained by reacting a compound containing multiple phenolic hydroxyl groups in 1 part with cyclic carbonate compounds such as ethyl carbonate and propyl carbonate, and then reacting the resulting product with a monocarboxylic acid containing an unsaturated group, and reacting the resulting product with a polyacid anhydride.

(12) A carboxyl-containing resin obtained by reacting an epoxy compound having multiple 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-hydroxyphenylethanol, with a monocarboxylic acid containing an unsaturated group, such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polyacid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, phenyltricarboxylic anhydride, pyromellitic anhydride, adipic anhydride, etc.

(13) A carboxyl-containing resin formed by further addition of the carboxyl-containing resins described in (1) to (12) above to compounds having one epoxy group and one or more (meth)acrylic acid groups in the molecule of (meth)acrylate, α-methyl methacrylate, etc.

Among the above-mentioned carboxyl-containing resins, the carboxyl-containing resins described in (1), (7), (8), (10) to (13) are preferred.

As compounds containing phenolic hydroxyl groups, examples include compounds with a biphenyl skeleton or a p-phenyl skeleton or both, or phenolic resins with various skeletons synthesized using phenol, ortho-cresol, p-cresol, m-cresol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, catechol, resorcinol, hydroquinone, methyl hydroquinone, 2,6-dimethyl hydroquinone, trimethyl hydroquinone, pyrogallol, phlorogallol, etc.

Furthermore, examples of compounds containing phenolic hydroxyl groups include, for instance, phenolic varnish resins, alkylphenolic varnish resins, bisphenol A phenolic varnish resins, dicyclopentadiene-type phenolic resins, Xylok-type phenolic resins, terpene-modified phenolic resins, polyvinylphenols, bisphenol F, bisphenol S-type phenolic resins, poly-p-hydroxystyrene, condensates of naphthol and aldehydes, and condensates of dihydroxynaphthalene and aldehydes, as well as other commonly known phenolic resins.

Commercially available phenolic resins include, for example, HF1H60 (manufactured by Meiwa Kasei Corporation), Phenolite TD-2090, Phenolite TD-2131 (manufactured by DIC Corporation), Besmol CZ-256-A (manufactured by DIC Corporation), Shonol BRG-555, Shonol BRG-556 (manufactured by AICA Corporation), and polyvinylphenol CST70, CST90, S-1P, S-2P (manufactured by Maruzen Petroleum Corporation).

(A) The acid value of the alkali-soluble resin is preferably in the range of 40~200 mgKOH/g, and more preferably in the range of 45~120 mgKOH/g. When the acid value of the alkali-soluble resin is above 40 mgKOH/g, alkali imaging becomes easier. On the other hand, when it is below 200 mgKOH/g, normal inhibitor patterns can be easily drawn, which is better.

(A) The weight-average molecular weight of alkali-soluble resins varies depending on the resin skeleton, but is preferably in the range of 1,500 to 150,000, and more preferably in the range of 1,500 to 100,000. A weight-average molecular weight of 1,500 or higher results in good non-stick properties, good moisture resistance of the coating after exposure, and suppression of film degradation during development, as well as suppression of resolution reduction. Conversely, a weight-average molecular weight of 150,000 or lower results in good development properties and excellent storage stability.

(A) Alkali-soluble resins can be used alone or in combination with two or more.

[(B) Photopolymerization Initiator] In the curing resin composition of the present invention, the (B) photopolymerization initiator can be any known photopolymerization initiator or photoradical generator. Examples of photopolymerization initiators (B) 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, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, and bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad manufactured by IGM Resins). Diphenylphosphine oxides such as 819); 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, methyl 2,4,6-trimethylbenzoylphenylphosphine, 2-methylbenzoyldiphenylphosphine oxide, isopropyl tert-pentaylphenylphosphine, 2,4,6-trimethylbenzoyldiphenylphosphine (Omnirad TPO manufactured by IGM Resins). Mono-phosphine oxides such as H); hydroxyacetophenones such as 1-hydroxy-cyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropoxy)benzyl]phenyl}-2-methyl-propane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, etc.; benzoin, biphenyl, benzoin methyl ether, benzoin ethyl ether, benzoin Benzoin derivatives such as n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenone derivatives such as benzophenone, p-methylbenzophenone, Michlein ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bis(diethylamino)benzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, and 2-methyl-1-[4-( Acetophenones including [methylthiophenyl]-2-morpholin-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, N,N-dimethylaminoacetophenone, etc.; thiophene, 2-ethylthiophene, 2-isopropylthiophene, 2,4-dimethylthiophene, 2,4-diethylthiophene, 2-chlorothiophene. Thiones such as 2,4-diisopropylthiotonone; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-pentylanthraquinone, and 2-aminoanthraquinone; acetals such as acetophenone dimethyl acetal and benzyl dimethyl acetal; benzoate esters such as ethyl 4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoate; 1,2-octanedione, 1-[4-(phenylthio)-, Oxime esters such as 2-(O-benzoyloxime), acetone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetylated oxime); titanium cadmium metals such as bis(n5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl)titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyridinyl)ethyl)phenyl]titanium; phenyl disulfides such as 2-nitrofuran, butyroin, anisole, azobisisobutyronitrile, tetramethylthiuram disulfide, etc. The photopolymerization initiator can be used alone or in combination of two or more. Oxime esters (hereinafter also referred to as "oxime ester-based photopolymerization initiators") are preferred, and acetone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetylgoxime) is even more preferred. (B) The amount of photopolymerization initiator prepared is, for example, 0.01 to 30 parts by weight relative to 100 parts by weight of the alkaline soluble resin in (A). Furthermore, the amount of the oxime ester-based photopolymerization initiator, in terms of solids, is preferably 8% by weight or more, and more preferably 12% by weight or more. A content of 8% by weight or more readily achieves high sensitivity. Oxime ester-based photopolymerization initiators can be used alone or in combination of two or more.

As an oxime ester-based photopolymerization initiator, any known oxime ester-based photopolymerization initiator can be used. Examples of commercially available products include Irgacure OXE01 (1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyl oxime)]) and Irgacure OXE02 (acetone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetylated oxime)) manufactured by BASF Corporation, N-1919 and NCI-831 manufactured by ADEKA Corporation, and TR-PBG-304 manufactured by Changzhou Qiangli Electronic New Materials Co., Ltd.

Alternatively, initiators having two oxime ester groups within the molecule may be preferred, specifically oxime ester compounds having a carbazole structure represented by the following general formula. (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, a phenyl group (substituted with an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having 1 to 8 carbon atoms, or a dialkylamino group), a naphthyl group (substituted with an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having 1 to 8 carbon atoms, or a dialkylamino group), and Y and Z respectively represent a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a halogen group, a phenyl group, a phenyl group (substituted with an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group), and ... The following groups are substituted with alkyl, alkylamino or dialkylamino groups having 1 to 8 carbon atoms, naphthyl (substituted with alkyl, alkoxy or amino groups having 1 to 17 carbon atoms, alkylamino or dialkylamino groups having 1 to 8 carbon atoms), anthracene, pyridyl, benzofuranyl, benzothiophene, Ar represents a single bond, or alkyl, vinyl, phenyl, biphenyl, pyridyl, naphthyl, thiophene, anthracene, thiophene, furanyl, 2,5-pyrrolidinyl, 4,4'-diphenylvinyldiyl, 4,2'-styrenediyl, n represents an integer from 0 to 1).

In particular, in the aforementioned general formula, preferably X and Y are methyl or ethyl, Z is methyl or phenyl, n is 0, Ar is a single bond, or phenyl, naphthyl, thiophene or thiophene.

Furthermore, a preferred carbazole oxime ester compound may also be a compound represented by the following general formula. (In the formula, ^R1 represents an alkyl group with 1 to 4 carbon atoms or a phenyl group that can be substituted by a nitro group, a halogen atom, or an alkyl group with 1 to 4 carbon atoms; ^R2 represents an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, or a phenyl group that can be substituted by an alkyl group with 1 to 20 carbon atoms or an alkoxy group with 1 to 4 carbon atoms; ^R4 represents a nitro group or a cyano group represented by XC (=O); ^X represents an aryl group, thiophene group, morpholino group, thiophenyl group, or a structure represented by the following formula that can be substituted by an alkyl group with 1 to 4 carbon atoms.)

In addition, examples include carbazole oxime compounds disclosed in Japanese Patent Application Publication No. 2004-359639, Japanese Patent Application Publication No. 2005-097141, Japanese Patent Application Publication No. 2005-220097, Japanese Patent Application Publication No. 2006-160634, Japanese Patent Application Publication No. 2008-094770, Japanese Patent Application Publication No. 2008-509967, Japanese Patent Application Publication No. 2009-040762, and Japanese Patent Application Publication No. 2011-80036.

[(C) Thermosetting Resins] The thermosetting resin composition of this invention, by including thermosetting resins, is expected to have improved heat resistance. The thermosetting resin can be used alone or in combination with two or more others. Any known thermosetting resin can be used. For example, conventional thermosetting components such as melamine resin, benzoguanamine resin, melamine derivatives, benzoguanamine derivatives, etc., amino resins, isocyanate compounds, terminal isocyanate compounds, cyclic carbonate compounds, epoxide compounds, oxocyclobutane compounds, cyclosulfide resins, bismaleimide, and carbodiimide resins can be used. Preferably, it is a thermosetting resin having a plurality of cyclic ether groups or cyclic thioether groups (hereinafter referred to as cyclic (thio)ether groups) in its molecule.

The thermosetting resins with multiple cyclic (thio) ether groups in the above-mentioned molecules are preferably compounds with multiple cyclic (thio) ether groups with 3, 4 or 5 members in the molecule. Examples include compounds with multiple epoxy groups in the molecule, i.e., polyfunctional epoxy compounds; compounds with multiple oxocyclobutyl groups in the molecule, i.e., polyfunctional oxocyclobutane compounds; and compounds with multiple thioether groups in the molecule, i.e., cyclosulfide resins.

Examples of multifunctional epoxy compounds include epoxidized vegetable oils; bisphenol A type epoxy resins; hydroquinone type epoxy resins; bisphenol type epoxy resins; thioether type epoxy resins; brominated epoxy resins; phenolic varnish type epoxy resins; biphenolic varnish type epoxy resins; and bisphenol. Type F epoxy resins; hydrogenated bisphenol A epoxy resins; glycidylamine epoxy resins; acetylene epoxy resins; alicyclic epoxy resins; trihydroxyphenylmethane epoxy resins; bixylenol or biphenol epoxy resins or mixtures thereof; bisphenol S epoxy resins. Epoxy resins; bisphenol A phenolic varnish-type epoxy resins; tetrahydroxyphenyl ethane-type epoxy resins; heterocyclic epoxy resins; diglyceride phthalate resins; tetraglyceride-xylyl acetyl ethane resins; naphthyl-containing epoxy resins; epoxy resins having a dicyclopentadiene backbone; glycidyl methacrylate copolymer epoxy resins; copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate; epoxy-modified polybutadiene rubber derivatives; CTBN-modified epoxy resins, etc., but not limited to these. These epoxy compounds may be used alone or in combination of two or more. The preferred types are phenolic varnish-type epoxy resins, bisphenol-type epoxy resins, bixylenol-type epoxy resins, biphenol-type epoxy resins, biphenol-phenolic varnish-type epoxy resins, naphthalene-type epoxy resins, or mixtures thereof.

Examples of oxocyclobutane compounds include bis[(3-methyl-3-oxocyclobutylmethoxy)methyl] ether, bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl] ether, 1,4-bis[(3-methyl-3-oxocyclobutylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl]benzene, (3-methyl-3-oxocyclobutyl)methyl acrylate, and (3-ethyl-3-oxocyclobutyl)methyl acrylate. Multifunctional oxocyclobutanes, such as methyl methacrylate (3-methyl-3-oxocyclobutane), methyl methacrylate (3-ethyl-3-oxocyclobutane), or oligomers or copolymers thereof, are also examples. Other examples include ethers of resins containing hydroxyl groups, such as oxocyclobutanol and phenolic varnish resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, resorcinol calixarene, or sesquioxanes. Furthermore, copolymers of unsaturated monomers with oxocyclobutane rings and alkyl (meth)acrylates are also examples.

Compounds having a plurality of cyclic thioether groups in their molecules include bisphenol A type cyclothiolated resins, etc. Furthermore, cyclothiolated resins, etc., can also be used by replacing the oxygen atom of the epoxy group of phenolic varnish-type epoxy resins with a sulfur atom using the same synthetic method. The amount of these thermosetting resins having a plurality of cyclic (thio)ether groups in their molecules is preferably 0.6 to 2.5 equivalents of the cyclic (thio)ether groups relative to 1 equivalent of the alkali-soluble group such as the carboxyl group or phenolic hydroxyl group of the (A) alkali-soluble resin, more preferably 0.8 to 2.0 equivalents.

Examples of amino resins that are derivatives of melamine, benzoguanamine, etc., include hydroxymethylmelamine compounds, hydroxymethylbenzoguanamine compounds, hydroxymethylglyuridine compounds, and hydroxymethylurea compounds.

As an isocyanate compound, it can be used to formulate polyisocyanate compounds. Examples of polyisocyanate compounds include aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, naphthalene-1,5-diisocyanate, ortho-xylene diisocyanate, m-xylene diisocyanate, and 2,4-toluene dimers; tetramethylene diisocyanate, hexamethylene diisocyanate, etc. Aliphatic polyisocyanates such as methyl diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylene bis(cyclohexyl) isocyanate and isoflavone diisocyanate; alicyclic polyisocyanates such as dicycloheptane triisocyanate; and adducts, biuret forms and isocyanurate forms of the previously exemplified isocyanate compounds.

The isocyanate compound can be the product of an addition reaction between an isocyanate compound and an isocyanate terminator. Examples of isocyanate compounds that can react with isocyanate terminators include, for example, the polyisocyanate compounds mentioned above. Examples of isocyanate terminators include, for example, phenolic terminators; lactamine terminators; active methylene terminators; alcohol terminators; oxime terminators; thiol terminators; acetylammine terminators; amide terminators; imidazole terminators; and imine terminators.

Thermosetting resins can be used alone or in combination with two or more. The preferred amount of thermosetting resin relative to 100 parts by weight of the solids of (A) alkali-soluble resin is 20-60 parts by weight, more preferably 30-50 parts by weight. When the amount is 20 parts by weight or more, excellent heat resistance is observed. When the amount is 60 parts by weight or less, storage stability improves accordingly.

[(D) Coloring Agents] Coloring agents may include one or a suitable combination of two or more of the following: red, green, blue, yellow, white, black, or other colors. Pigments, dyes, and pigments are all acceptable. Specifically, those with a color index (C.I.; issued by The Society of Dyers and Colourists) number may be cited. However, from the perspective of reducing environmental impact and human health effects, halogen-free coloring agents are preferred.

Examples of red colorants include monoazo, diazo, azo pigments, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone pigments. Green colorants include phthalocyanine, anthraquinone, and perylene pigments, which may be metal-substituted or unsubstituted. Blue colorants can be pigments, dyes, or dyes, preferably those without halogen atoms. Phthalocyanine and anthraquinone pigments are examples of blue colorants. Pigment-based pigments are classified as pigment compounds, and specific examples include: Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, and 60. Solvent blues such as 35, 63, 68, 70, 83, 87, 94, 97, 122, 136, 67, and 70 can be used as dyes. In addition to the above, metal-substituted or unsubstituted phthalocyanine compounds can also be used. A single blue colorant can be used alone, or two or more can be used in combination. Examples of yellow colorants include monoazo, diazo, condensed azo, benzimidazolone, isoindolone, and anthraquinone compounds. Examples of white colorants include rutile and rutilated titanium oxides. Examples of black colorants include titanium black, carbon black, graphite black, iron oxide black, anthraquinone black, cobalt oxide black, copper oxide black, manganese black, antimony oxide black, nickel oxide black, perylene oxide black, and aniline black pigments, as well as molybdenum sulfide and bismuth sulfide. Furthermore, for the purpose of adjusting the hue, colorants such as purple, orange, and brown can also be added. When creating an alkaline-developable curable resin composition that produces a coating on CZ-treated copper with excellent concealment, minimal hue change after heating, and excellent resolution, a preferred combination of colorants is red, yellow, blue, and black. In this case, the amount of colorant (D) prepared relative to 100 parts by weight of the solids of the alkali-soluble resin (A) is preferably 0.01-0.04 parts by weight of black colorant, 1.10-2.45 parts by weight of blue colorant, 0.01-0.08 parts by weight of yellow colorant, and 0.60-2.00 parts by weight of red colorant. More preferably, the amounts are 0.02-0.03 parts by weight of black colorant, 1.40-2.20 parts by weight of blue colorant, 0.03-0.06 parts by weight of yellow colorant, and 0.75-1.20 parts by weight of red colorant.

[Inorganic Filler] The curable resin composition of this invention preferably includes an inorganic filler. The inorganic filler is not particularly limited; conventionally used inorganic fillers can be used, such as silica, crystalline silica, Newberg silica, aluminum hydroxide, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, aluminum hydroxide, barium sulfate, barium titanium dioxide, iron oxide, non-fibrous glass, hydrotalcite, slag wool, aluminum silicate, calcium silicate, zinc oxide, etc., or a combination of two or more of these inorganic fillers. Silica is preferred because it has a small surface area, disperses stress throughout, and is less likely to become the starting point for cracking; spherical silica is even more preferred.

Inorganic fillers can also undergo surface treatment. Here, surface treatment of inorganic fillers refers to treatments used to improve their compatibility with resin components. Surface treatment of inorganic fillers can be either a surface treatment that introduces curing reactive groups into the surface of the inorganic filler, or a surface treatment without introducing such groups. Here, the curing reactive group is not particularly limited to any curing compound that reacts with curing compounds such as (A) alkali-soluble resins or (C) thermosetting resins; it can be either a curing reactive group or a thermosetting reactive group. Examples of curing reactive groups include methacrylate, acrylic, vinyl, and styrene groups, while examples of thermosetting reactive groups include epoxy, amino, hydroxyl, carboxyl, isocyanate, imino, oxacyclobutyl, teryl, methoxymethyl, methoxyethyl, ethoxymethyl, ethoxyethyl, and oxazolinyl groups. The method for introducing curing reactive groups onto the surface of inorganic fillers is not particularly limited; any conventional method can be used. The surface of the inorganic filler can be treated with a surface treatment agent containing curing reactive groups, such as a coupling agent with curing reactive groups as organic groups. Silicone coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents can be used as coupling agents. Furthermore, examples of surface-treated inorganic fillers that do not possess hardening reactive groups include inorganic fillers that have undergone silica-alumina surface treatment, titanium ester coupling agent treatment, aluminum ester coupling agent treatment, organic treatment, etc.

Inorganic fillers can be used alone or in combination of two or more. The preferred amount of inorganic filler relative to 100 parts by weight of the solids of (A) alkali-soluble resin is 80-450 parts by weight, more preferably 100-200 parts by weight. When the amount is 80 parts by weight or more, excellent heat resistance is observed. When the amount is 450 parts by weight or less, superior resolution is observed.

(Compounds with vinyl unsaturated groups) The curable resin composition of this invention may contain compounds that, unlike the alkali-soluble resin (A), function as reactive thinners, specifically compounds with vinyl unsaturated groups. Commonly used photopolymerizable oligomers and photopolymerizable vinyl monomers can be used as compounds with vinyl unsaturated groups.

Examples of photopolymerizable oligomers include unsaturated polyester oligomers and (meth)acrylate oligomers. Examples of (meth)acrylate oligomers include epoxy (meth)acrylates in phenolic varnishes, epoxy (meth)acrylates in cresol phenolic varnishes, epoxy (meth)acrylates in bisphenol type epoxy (meth)acrylates, urethane (meth)acrylates, epoxy urethane (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, and polybutadiene-modified (meth)acrylates.

As photopolymerizable vinyl monomers, commonly used ones include, for example, styrene derivatives such as styrene, chlorostyrene, and α-methylstyrene; vinyl esters such as vinyl acetate, vinyl butyrate, or vinyl benzoate; vinyl ethers such as vinyl isobutyl ether, vinyl n-butyl ether, vinyl tributyl ether, vinyl n-pentyl ether, vinyl isopentyl ether, vinyl n-octadecyl ether, vinyl cyclohexyl ether, ethylene glycol monobutyl vinyl ether, and triethylene glycol monomethyl vinyl ether; acrylamide, methacrylamide, and N-hydroxymethyl... (Meth)acrylamides, such as N-hydroxymethylmethacrylamide, N-methoxymethacrylamide, N-ethoxymethacrylamide, and N-butoxymethacrylamide; allyl compounds, such as triallyl isocyanurate, diallyl phthalate, and diallyl isophthalate; and (meth)acrylic acids, such as 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate. Esters; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, and other hydroxyalkyl (meth)acrylates; alkoxyalkylene glycol mono(meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)propylene. Poly(meth)acrylates such as alkyl polyols including dipentaerythritol hexa(meth)acrylate; polyoxyalkylene glycol poly(meth)acrylates such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethoxytrimethylpropane triacrylate, propoxytrimethylpropane tri(meth)acrylate; poly(meth)acrylates such as neopentyl glycol hydroxypentanoate di(meth)acrylate; and isocyanurate-type poly(meth)acrylates such as tri[(meth)acryloxyethyl]isocyanurate. These can be used alone or in combination of two or more to meet desired properties.

Compounds containing vinyl unsaturated groups can be used alone or in combination of two or more. The amount of the compound containing vinyl unsaturated groups relative to 100 parts by weight of the solids of (A) alkali-soluble resin is preferably 3 to 25 parts by weight, more preferably 5 to 20 parts by weight. A amount of 3 parts by weight or more contributes to high sensitivity. A amount of 25 parts by weight or less provides good resolution.

(Thermosetting Catalyst) The curable resin composition of this invention may contain a thermosetting catalyst. Examples of such 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; acehydrazine compounds such as diacetylhydrazine adipate and diacetylhydrazine sebacate; and phosphorus compounds such as triphenylphosphine. Furthermore, S-triazine derivatives such as guanidineamine, acetylguanidine, phenylguanidine, melamine, 2,4-diamino-6-methacryloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine•isocyanuric acid adduct, and 2,4-diamino-6-methacryloxyethyl-S-triazine•isocyanuric acid adduct can also be used, preferably in combination with thermosetting catalysts. These compounds can also function as adhesion promoters. Furthermore, if used in thermosetting catalysts, they can also be used as organic fillers.

The thermosetting catalyst is preferably an organic filler with an amine group, specifically preferably at least one of melamine and dicyandiamide (DICY).

The thermosetting catalyst can be used alone or in combination with two or more other catalysts. The preferred amount of the thermosetting catalyst relative to 100 parts by weight of the solids of (A) alkali-soluble resin is 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight. When the amount is 0.5 parts by weight or more, excellent heat resistance is observed. When the amount is 10 parts by weight or less, improved storage stability is observed.

(Organic solvents) The curable resin composition of the present invention may contain organic solvents for purposes such as the formulation of the composition or viscosity adjustment when coated on a substrate or carrier film. As organic solvents, commonly used organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as lysozyme, methyl lysozyme, butyl lysozyme, 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 such as ethyl acetate, butyl acetate, butyl lactate, lysozyme acetate, butyl lysozyme acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propyl carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used alone or in combination of two or more.

(Other optional ingredients) Other curing ingredients or other additives commonly used in the field of electronic materials can also be incorporated into the curing resin composition of this invention. Examples of other curing ingredients include cyanate resins, reactive ester resins, maleimide compounds, and cycloaliphatic olefin polymers. Other additives include, for example, thermal polymerization inhibitors, ultraviolet absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, antioxidants, antibacterial and antifungal agents, defoamers, leveling agents, tackifiers, adhesion promoters, thixotropic promoters, photoinitiators, sensitizers, thermoplastic resins, organic fillers, mold release agents, surface treatment agents, dispersants, dispersing aids, surface modifiers, stabilizers, and fluorophores.

The curable resin composition of this invention can be used as a dry film or as a liquid. When used as a liquid, it can be a single liquid or two or more liquids.

The curable resin composition of the present invention comprises a resin layer obtained by coating the curable resin composition of the present invention onto a carrier film and drying it. When forming a dry film, the curable resin composition of the present invention is first diluted with the above-mentioned organic solvent to adjust to an appropriate viscosity, and then coated onto the carrier film with a uniform thickness using a corner roller coater, a scraper coater, a lip mold coater, a rod coater, a rubber roller coater, a reverse roller coater, a conveyor roller coater, a gravure coater, a spray coater, etc. Subsequently, the coated composition is dried at a temperature of 40~130℃ for 1~30 minutes to form a resin layer. There are no particular restrictions on the coating film thickness, but the film thickness after drying is generally 3~150μm, with 5~60μm being a suitable range.

Plastic films can be used as carrier films, such as polyester films (e.g., polyethylene terephthalate (PET), polyimide films, polyamide-imide films, polypropylene films, and polystyrene films. There are no particular limitations on the thickness of the carrier film, but a range of 10–150 μm is generally suitable. A range of 15–130 μm is preferred.

After forming a resin layer composed of the curable resin of the present invention on a carrier film, it is preferable to further deposit a peelable cover film on the surface of the resin layer to prevent dust and other contaminants from adhering to the surface of the resin layer. The peelable cover film can be, for example, polyethylene film, polytetrafluoroethylene film, polypropylene film, or surface-treated paper. As long as the adhesive force is less than the adhesive force between the resin layer and the carrier film when the cover film is peeled off, it is acceptable.

Furthermore, in this invention, the curable resin composition of this invention can also be coated onto the aforementioned cover film and dried to form a resin layer, and a carrier film can be deposited on its surface. That is, in this invention, either a carrier film or a cover film can be used as the thin film for coating the curable resin composition of this invention when manufacturing the dry film.

The printed circuit board of the present invention is a cured product obtained from a resin layer of the curable resin composition or dry film of the present invention. As a manufacturing method of the printed circuit board of the present invention, for example, the curable resin composition of the present invention is adjusted to a viscosity suitable for coating methods using the above-mentioned organic solvent, and then coated on a substrate by methods such as dip coating, flow coating, roller coating, rod coating, screen printing, curtain coating, etc., and the organic solvent contained in the composition is evaporated and dried (temporarily dried) at a temperature of 60~100°C to form a non-adhesive resin layer. Furthermore, in the case of dry film, after the resin layer is brought into contact with the substrate and bonded to the substrate by a laminating machine or the like, the resin layer can be formed on the substrate by peeling off the carrier film.

As for the aforementioned substrates, in addition to printed circuit boards or flexible printed circuit boards that pre-form circuits using copper or the like, materials such as paper phenolic resin, paper epoxy resin, glass cloth epoxy resin, glass polyimide, glass cloth/non-woven epoxy resin, glass cloth/paper epoxy resin, synthetic fiber epoxy resin, fluororesin, polyethylene, polyphenylene ether, polyphenylene oxide, and cyanate ester can be used for high-frequency circuit copper-mounted multilayer boards, including all grades (FR-4, etc.), as well as metal substrates, polyimide films, PET films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, and wafers.

The volatile drying after applying the curable resin composition of this invention can be carried out using a hot air circulating dryer, IR oven, heating plate, forced drying oven, etc. (using a heat source that utilizes air heating to make hot air convection contact within the dryer, or using a nozzle to blow onto the support body).

After forming a resin layer on a substrate, a photomask with a specific pattern is selectively exposed using active energy lines. Unexposed areas are developed using a dilute alkaline aqueous solution (e.g., 0.3-3% by mass sodium carbonate aqueous solution), forming a pattern of the cured material. The cured material is then irradiated with active energy lines and then heat-cured (e.g., at 100-220°C), or heat-cured and then irradiated with active energy lines, or only heat-cured, ultimately completing the curing process (formal curing) and forming a cured film with excellent adhesion, hardness, and other properties. Furthermore, when the curable resin composition of this invention contains a photoalkali generator, heating is preferably performed after exposure and before development. The preferred heating conditions before development are, for example, heating at 60-150°C for 1-60 minutes.

For the exposure machine used in the aforementioned active energy line irradiation, any device equipped with a high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halogen lamp, mercury arc lamp, etc., that irradiates ultraviolet light in the range of 350~450nm is acceptable. Alternatively, a direct drawing device (such as a laser direct imaging device that directly draws images from CAD data from a computer) can also be used. The lamp or laser light source for the direct drawing machine should preferably have a maximum wavelength in the range of 350~450nm. The exposure amount used for image formation varies with film thickness, but is generally 10~1000 mJ/ ^cm² , preferably in the range of 20~800 mJ/ ^cm² .

As for the above-mentioned developing methods, methods such as immersion, rinsing, spraying, and brushing can be used. As for the developing solution, alkaline aqueous solutions of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, etc. can be used.

The curable resin composition of this invention is preferably used to form curable films on printed circuit boards, especially suitable for forming permanent coatings, and further suitable for forming solder resists, interlayer insulating films, and capping layers. Furthermore, according to the thermosetting resin composition of this invention, even as a thin film, a cured product with excellent appearance and surface smoothness can be obtained. Due to its excellent sensitivity and resolution, it is suitable for forming thin films on printed circuit boards requiring high reliability, such as packaging substrates, especially permanent coatings (especially solder resists) for FC-BGAs.

In particular, the curable resin composition of this invention is suitable for forming thin films, preferably 3-40 μm, more preferably 5-30 μm. [Example]

The following examples and comparative examples illustrate the invention in detail, but the invention is not limited to the examples described below. In addition, unless otherwise specified, "parts" and "%" below are all quality standards.

(Synthesis of Alkali-Soluble Resin A-1) In a high-pressure reactor equipped with a thermometer, a nitrogen inlet device, an epoxide inlet device, and a stirring device, 119.4 parts of cresol varnish resin (Shonol CRG951 manufactured by AICA Industrial Co., Ltd., OH equivalent: 119.4), 1.19 parts of potassium hydroxide, and 119.4 parts of toluene were introduced. While stirring, nitrogen was introduced into the system, and the temperature was raised. Next, 63.8 parts of propylene oxide were slowly added dropwise, and the reaction was carried out at 125~132℃ and 0~4.8 kg/ ^cm² for 16 hours. Subsequently, the mixture was cooled to room temperature, and 1.56 parts of mixed 89% phosphoric acid were added to the reaction solution to neutralize potassium hydroxide, yielding a propylene oxide reaction solution of phenolic varnish-type cresol resin with 62.1% nonvolatile matter and a hydroxyl value of 182.2 mgKOH/g (307.9 g/eq.). This is based on an average addition of 1.08 moles of phenolic hydroxyl groups per equivalent of propylene oxide. 293.0 parts of the obtained phenolic varnish-type cresol resin propylene oxide reaction solution, 43.2 parts of acrylic acid, 11.53 parts of methanesulfonic acid, 0.18 parts of methyl hydroquinone, and 252.9 parts of toluene were introduced into a reactor equipped with a stirrer, thermometer, and air blow-in tube. Air was blown in at a rate of 10 ml/min, and the reaction was carried out at 110°C for 12 hours with stirring. Since the water produced in the reaction is an azeotropic mixture with toluene, 12.6 parts of water were extracted. The mixture was then cooled to room temperature, and the resulting reaction solution was neutralized with 35.35 parts of a 15% sodium hydroxide aqueous solution, followed by washing with water. Subsequently, toluene was replaced and distilled off using 118.1 parts of diethylene glycol monoethyl ether acetate in an evaporator to obtain a phenolic varnish-type acrylate resin solution. Next, 332.5 parts of the obtained phenolic varnish-type acrylate resin solution and 1.22 parts of triphenylphosphine were introduced into a reactor equipped with a stirrer, thermometer, and air blow-in tube. Air was blown in at a rate of 10 ml/min, and 60.8 parts of tetrahydrophthalic anhydride were slowly added while stirring. The reaction was carried out at 95–101 °C for 6 hours, and then cooled. This yielded an acrylate resin A-1 solution with a solid content of 65% and an acid value of 87.7 mgKOH/g.

(Synthesis of Alkali-Soluble Resin A-2) In a flask equipped with a cooler and a stirrer, 456 parts of bisphenol A, 228 parts of water, and 649 parts of 37% formaldehyde were added. The temperature was maintained below 40°C. 228 parts of a 25% sodium hydroxide aqueous solution were then added. After the addition was complete, the reaction was carried out at 50°C for 10 hours. After the reaction was complete, the temperature was cooled to 40°C and maintained below 40°C. The solution was then neutralized to pH 4 with a 37.5% phosphoric acid aqueous solution. The aqueous layer was then separated by standing. After separation, 300 parts of methyl isobutyl ketone were added and dissolved uniformly. The solution was then washed three times with 500 parts of distilled water. Water and solvent were removed under reduced pressure at a temperature below 50°C. The obtained polyhydroxymethyl compound was dissolved in 550 parts of methanol to obtain 1230 parts of a methanol solution of the polyhydroxymethyl compound. A portion of the obtained methanol solution of the polyhydroxymethyl compound was dried in a vacuum dryer at room temperature, with a solid content of 55.2%. 500 parts of the obtained methanol solution of the polyhydroxymethyl compound and 440 parts of 2,6-xylenol were added and dissolved uniformly at 50°C. After uniform dissolution, methanol was removed under reduced pressure at a temperature below 50°C. Subsequently, 8 parts of oxalic acid were added, and the reaction was carried out at 100°C for 10 hours. After the reaction was completed, the distillate was removed under reduced pressure at 180°C and 50 mmHg to obtain 550 parts of phenolic varnish resin A. Next, in a high-pressure reactor equipped with a thermometer, a nitrogen inlet device, an epoxide inlet device, and a stirring device, 130 parts of the above-mentioned phenolic varnish resin A, 2.6 parts of 50% sodium hydroxide aqueous solution, and 100 parts of toluene/methyl isobutyl ketone (mass ratio = 2/1) were added. While stirring, nitrogen was introduced into the system. The mixture was then heated to 150°C and 8 kg/ ^cm² , and 45 parts of ethylene oxide were slowly introduced to initiate the reaction. The reaction continued for approximately 4 hours until the gauge pressure reached 0.0 kg/ ^cm² , after which it was cooled to room temperature. 3.3 parts of a mixed 36% hydrochloric acid aqueous solution were added to the reaction solution to neutralize the sodium hydroxide. The neutralization reaction product was diluted with toluene, washed three times with water, and the solvent was removed by evaporation to obtain an ethylene oxide adduct of phenolic varnish resin A with a hydroxyl value of 175 g/eq. This is based on an average addition of 1 mole of ethylene oxide per 1 equivalent of phenolic hydroxyl group. 175 parts of the thus obtained ethylene oxide adduct of phenolic varnish resin A, 50 parts of acrylic acid, 3.0 parts of p-toluenesulfonic acid, 0.1 parts of hydroquinone monomethyl ether, and 130 parts of toluene were fed into a reactor equipped with a stirrer, thermometer, and air inlet tube. The mixture was stirred while blowing air in, heated to 115°C, and the water generated during the reaction was distilled off as an azeotropic mixture with toluene. The reaction was then carried out for 4 hours and cooled to room temperature. The resulting reaction solution was washed with 5% NaCl aqueous solution, and toluene was removed by reduced pressure distillation. Diethylene glycol monoethyl ether acetate was then added to obtain an acrylate resin solution with a solid content of 68%. Next, 312 parts of the obtained acrylate resin solution, 0.1 parts of hydroquinone monomethyl ether, and 0.3 parts of triphenylphosphine were added to a four-necked flask equipped with a stirrer and reflux cooler. The mixture was heated to 110°C, and 45 parts of tetrahydrophthalic anhydride were added. The reaction was carried out for 4 hours, and then cooled. The resulting carboxyl-containing photosensitive resin had a non-volatile content of 72% and a solid content acid value of 65 mgKOH/g. This carboxyl-containing photosensitive resin is referred to as A-2 varnish.

(Synthesis of Alkali-Soluble Photosensitive Resin A-3) In a flask equipped with a cooler and a stirrer, 456 parts of bisphenol A, 228 parts of water, and 649 parts of 37% formaldehyde were added. The temperature was maintained below 40°C. 228 parts of a 25% sodium hydroxide aqueous solution were then added. After the addition was complete, the reaction was carried out at 50°C for 10 hours. After the reaction was complete, the temperature was cooled to 40°C and maintained below 40°C. The solution was then neutralized to pH 4 with a 37.5% phosphoric acid aqueous solution. The aqueous layer was then separated by standing. After separation, 300 parts of methyl isobutyl ketone were added and dissolved uniformly. The solution was then washed three times with 500 parts of distilled water. Water and solvents were removed under reduced pressure at a temperature below 50°C. The obtained polyhydroxymethyl compound was dissolved in 550 parts of methanol to obtain 1230 parts of a methanol solution of the polyhydroxymethyl compound. A portion of the obtained methanol solution of the polyhydroxymethyl compound was dried in a vacuum dryer at room temperature, with a solid content of 55.2%. 500 parts of the obtained methanol solution of the polyhydroxymethyl compound and 440 parts of 2,6-xylenol were added and dissolved uniformly at 50°C. After uniform dissolution, methanol was removed under reduced pressure at a temperature below 50°C. Subsequently, 8 parts of oxalic acid were added, and the reaction was carried out at 100°C for 10 hours. After the reaction was completed, the distillate was removed under reduced pressure at 180°C and 50 mmHg to obtain 550 parts of phenolic varnish resin A. Next, in a high-pressure reactor equipped with a thermometer, a nitrogen inlet device, an epoxide inlet device, and a stirring device, 130 parts of the above-mentioned phenolic varnish resin A, 2.6 parts of 50% sodium hydroxide aqueous solution, and 100 parts of toluene/methyl isobutyl ketone (mass ratio = 2/1) were added. While stirring, nitrogen was introduced into the system. The mixture was then heated to 150°C and 8 kg/ ^cm² , and 45 parts of ethylene oxide were slowly introduced to initiate the reaction. The reaction continued for approximately 4 hours until the gauge pressure reached 0.0 kg/ ^cm² , after which it was cooled to room temperature. 3.3 parts of a mixed 36% hydrochloric acid aqueous solution were added to the reaction solution to neutralize the sodium hydroxide. The neutralization reaction product was diluted with toluene, washed three times with water, and the solvent was removed by evaporation to obtain an ethylene oxide adduct of phenolic varnish resin A with a hydroxyl value of 175 g/eq. This is an average addition of 1 mole per 1 equivalent of phenolic hydroxyl group to ethylene oxide. 175 parts of the thus obtained ethylene oxide adduct of phenolic varnish resin A, 75 parts of methacrylic acid, 3.0 parts of p-toluenesulfonic acid, 0.1 parts of hydroquinone monomethyl ether, and 130 parts of toluene were fed into a reactor equipped with a stirrer, thermometer, and air inlet tube. The mixture was stirred while blowing air in, heated to 115°C, and the water generated during the reaction was distilled off as an azeotropic mixture with toluene. The reaction was then carried out for 4 hours and cooled to room temperature. The resulting reaction solution was washed with 5% NaCl aqueous solution, and toluene was removed by reduced pressure distillation. Then, diethylene glycol monoethyl ether acetate was added to obtain an acrylic resin solution with a solid content of 68%. This acrylic resin solution is referred to as resin solution A-3 below.

(Synthesis of Spherical Silica) 70g of spherical silica (DENKA SFP-30M) and 30g of PMA (propylene glycol monomethyl ether acetate) as solvent were mixed and dispersed to obtain an inorganic filler.

[Examples and Comparative Examples] The ingredients were mixed according to the formula shown in Table 1 in the proportions (parts by weight) shown in Table 1. After pre-mixing with a mixer, the mixture was then kneaded with a bead mill to prepare a hardened resin composition. The amounts in the table represent the solids content (non-volatile components).

(Preparation of Dry Film) The prepared curable resin composition is applied onto a PET film using a coating machine to achieve a specific film thickness after drying. The film is then dried at 80°C for 30 minutes to obtain the dry film.

(Transmittance) Following the method described above (Preparation of Dry Film), a 20 μm thick resin layer film was prepared. The 20 μm thick dry film was laminated onto a 2 mm thick glass substrate, and the PET film was then peeled off. Subsequently, the absorbance was measured using a V-670 spectrophotometer.

(Concealment) Following the method described above (Dry Film Fabrication), dry films with resin layer thicknesses of 20μm and 25μm were fabricated after drying. Next, 18μm copper foil was subjected to CZ treatment (roughening treatment) with an etching rate of 1μm using a MECetchBOND CZ-8101 manufactured by MERCK Corporation, followed by rust prevention treatment using a MECetchBOND CL-8300 manufactured by MERCK Corporation, forming a printed circuit board with a comb-shaped pattern and a Cu thickness of 17μm and L/S = 12μm/13μm. The films were then fully exposed using an HMW680G (metal halogen lamp, diffused light) manufactured by OAK Corporation at the optimal exposure level of 800mJ. After peeling off the PET film, the circuit was irradiated with ultraviolet light at a cumulative exposure of 1000 mJ, and then cured (post-cured) at 160°C for 60 minutes in a circulating box furnace. The concealment of the circuits on the printed circuit board with the resulting cured film was visually evaluated. ◎: No Cu circuits were visible in either the 20μm or 25μm cured film. ○: Cu circuits were visible in the 20μm cured film, but not in the 25μm cured film. ×: Cu circuits were visible in both the 20μm and 25μm cured films.

(Resolution) Following the method described above (Dry Film Fabrication), a dry film with a resin layer thickness of 20 μm was prepared. A 20 μm thick dry film with a resin layer was laminated onto a substrate with a 34 μm copper foil that had undergone CZ treatment (roughening treatment) with an etching rate of 1 μm using a MECetchBOND CZ-8101 manufactured by MERCK Corporation, followed by rust prevention treatment using a MECetchBOND CL-8300 manufactured by MERCK Corporation. Exposure was performed using a UFX-2223M-APU01 projection exposure machine that cuts off the wavelength side longer than the i-line to create an opening pattern with a diameter of 40~350 nm. The PET film was peeled off and developed using a 1.0 wt% sodium carbonate aqueous solution. The minimum possible opening diameter was confirmed by SEM. ○: Minimum diameter less than 40 μm. ×: Minimum diameter greater than 40 μm.

(Confirmation Test of Tone Change) Following the method described above (Preparation of Dry Film), a dry film with a resin layer thickness of 20 μm was prepared after drying. The aforementioned 20 μm thick dry film was laminated onto a substrate with a 34 μm copper foil that had undergone CZ treatment (roughening treatment) with an etching rate of 1 μm using a MECetchBOND CZ-8101 (MERCK Corporation) and subsequently rust-proofed using a MECetchBOND CL-8300 (MERCK Corporation). The film was then fully exposed using an HMW680G (metal halogen lamp, diffused light) manufactured by OAK Corporation at the optimal exposure level of 800 mJ. After peeling off the PET film, the substrate was irradiated with ultraviolet light at a cumulative exposure of 1000 mJ. The color change confirmation test was conducted on the substrate after irradiation with ultraviolet light using a thermal cycling oven under two conditions: curing at 150°C for 60 minutes and curing at 170°C for 60 minutes. The colorimetry was measured using a KONICA MINOLTA CM-2600d colorimeter in SCI mode using CIE L*a*b* method.

The annotations in the title section of Table 1 are as follows. *1: Solution A-1 of the alkali-soluble resin synthesized above *2: Solution A-2 of the alkali-soluble resin synthesized above *3: Solution A-3 of the alkali-soluble resin synthesized above *4: Neomer DA-600 manufactured by Sanyo Chemical Industries, Ltd. *5: Laromer LR8863 manufactured by BASF Corporation, Japan *6: N-870-75EA manufactured by DIC Corporation *7: NC-3000H manufactured by Nippon Kayaku Co., Ltd. *8: HP-7200L manufactured by DIC Corporation *9: C.I. Pigment Red 149 *10: C.I. Pigment Yellow 147 *11: Phthalocyanine (C.I. Pigment Blue 15) *12: Carbon Black *13: B-30 manufactured by Sakai Kagaku Kogyo Co., Ltd. *14: Spherical silicon oxide synthesized above *15: IGM *16: Omnirad TPO H (Resins), a phosphine oxide-based photopolymerization initiator *17: JMT-784 (DSKH, Japan), a titanium thiocene-based photopolymerization initiator *18: Melamine *19: DICY (diacyanodiacetylamine) *10: QUINO POWER QS-30 (Kawasaki Chemicals)

The results shown in the table above demonstrate that the hardening resin composition of this invention exhibits excellent concealment and resolution. In contrast, Comparative Example 1 showed poor concealment. Comparative Examples 2 and 3 showed poor resolution. Comparative Example 4 showed poor concealment. Comparative Examples 5, 6, and 7 showed poor resolution. Furthermore, color changes were observed in Examples 1-4 and Comparative Example 3 before and after heating. Since Comparative Examples 1 and 4 showed poor concealment, and Comparative Examples 2, 5, 6, and 7 showed poor resolution, color changes were not confirmed. As a result, Examples 1-4 showed less color change before and after heating, while Comparative Example 3 showed a greater color change compared to Examples 1-4. Although not shown in the table, Comparative Example 8, except for the pigment, was formulated in the same amount as Comparative Example 2. The pigment contained no black, yellow, or red, but only 1.89 parts by weight of blue. Regarding Comparative Example 8, although the resolution improved to 30 μm, the concealment evaluation result was ×, therefore no further evaluation was performed.

Claims (4)

A curable resin composition comprising (A) an alkaline-soluble resin, (B) a photopolymerization initiator, (C) a thermosetting resin, and (D) a colorant, which is formed on copper with a CZ-treated surface; The aforementioned colorant (D) comprises a red colorant, a blue colorant, a yellow colorant, and a black colorant; The content of the aforementioned colorant (D), relative to 100 parts by weight of the solids of the alkali-soluble resin (A), is as follows: red colorant: 0.60-2.00 parts by weight; blue colorant: 1.10-2.45 parts by weight; yellow colorant: 0.01-0.08 parts by weight; and black colorant: 0.01-0.04 parts by weight. The transmittance of the dried coating (20 μm thick) of the aforementioned curable resin composition formed on a 2 mm thick glass substrate is 30-50% at a wavelength of 430 nm, 28-45% at a wavelength of 530 nm, more than 5% at a wavelength of 365 nm, and less than 12% at a wavelength of 720 nm. A dry film having a resin layer obtained from the curable resin composition described in claim 1. A hardened material obtained by hardening a resin layer of a hardening resin composition as described in claim 1 or a dry film as described in claim 2. A printed wiring board having the hardened material described in claim 3.