Melamine-free photosensitive thermocurable and developable two-component resin composition, its dry film and cured product, and printed circuit boards

Abstract

This invention provides a melamine-free photosensitive thermosetting and developable two-component resin composition, its dry film and cured product, and printed circuit boards formed therefrom, exhibiting excellent acid resistance, metal plating resistance, high-temperature storage properties, colorfastness, reduced volatilization of harmful substances during soldering, and excellent drying management. The melamine-free photosensitive thermosetting and developable two-component resin composition comprises (A) a carboxyl vinyl ester resin, (B) a photopolymerization initiator, (C) melamine phthalate, and (D) an epoxy resin. The (A) carboxyl vinyl ester resin and the (B) photopolymerization initiator are contained in a first component, and the (D) epoxy resin is contained in a second component different from the first component. The (C) melamine phthalate is present in a quantity of 1.2 to 11.8 parts by weight relative to 100 parts by weight of the (A) carboxyl vinyl ester resin (based on solids).

Description

Technical Field

[0001] The present invention relates to a melamine-free, photosensitive and heat-curable, developable two-component resin composition, a dry film thereof, and a cured product thereof. More particularly, the present invention relates to a melamine-free, photosensitive and heat-curable, developable two-component resin composition, a dry film thereof, and a cured product thereof, which are suitable for forming a solder resist for long-term reliable printed circuit boards. Prior Art

[0002] Solder resist (also known as solder mask ink) has long been used as a protective material for printed circuit boards (PCBs). Currently, some consumer PCBs and almost all industrial PCBs use alkali-developable solder resists, which are developed after UV exposure to form an image and then fully cured (primary cure) by heat and / or light exposure. Furthermore, solder resists designed for high-reliability electronic materials are increasingly being used to ensure long-term reliability in semiconductor devices used in vehicles such as automobiles, trains, ships, and airplanes.

[0003] Currently available solder mask inks often contain melamine, which acts as a heat hardener and antioxidant, enhancing the ink's acid and alkali resistance, metal plating resistance, and adhesion. However, melamine in the ink also presents numerous issues. It evaporates during the soldering process (typically at 260°C), and under the EU REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulation, melamine is classified as an SVHC (Substances of Very High Concern) environmentally regulated substance.

[0004] For example, the high-adhesion solder mask coating disclosed in Patent Document 1, the two-component solder mask photoresist disclosed in Patent Document 2, and the high-resolution solder mask ink disclosed in Patent Document 3 all use melamine. Patent Document 4 discloses a photosensitive solder mask ink that adds a melamine copolymer resin to the hardener, thereby improving the coating's durability and corrosion resistance. Patent Document 5 discloses a thermosetting ink that is resistant to yellowing and does not dry out by grafting modified melamine onto an epoxy resin. The modified melamine is dimethoxymelamine, trimethoxymelamine, tetramethylolmelamine, methylenemelamine, or methylated melamine. Prior Art Literature Patent Literature

[0005] Patent Document 1: CN116239938A Patent Document 2: CN116560187A Patent Document 3: CN111100499A Patent Document 4: CN114605867A Patent Document 5: CN114656833A Summary of the Invention

[0006] Technical Problems to be Solved by the Invention

[0007] Traditionally, solder mask inks have typically contained melamine as a thermosetting agent and antioxidant. With increasingly stringent environmental regulations, there's a desire to reduce or eliminate the use of melamine. However, the present inventors have discovered that reducing the amount of melamine in existing solder mask inks (e.g., Patent Documents 1-3) can lead to a decrease in the solder mask's acid resistance and metal plating resistance after post-bake (i.e., post-curing). Furthermore, while prior art attempts have used melamine-derived resins as hardeners or curing components, these have failed to simultaneously meet the requirements for drying control range, acid resistance, metal plating resistance, high-temperature storage, and discoloration resistance. For example, Patent Document 4 uses a melamine copolymer resin, but due to its high molecular weight, it fails to impart sufficient thermosetting and antioxidant properties to the solder mask ink. Patent Document 5 uses trimethoxymelamine, which, due to its methoxy group, is highly reactive in thermosetting inks. However, its low developability in developing inks makes it impractical.

[0008] Therefore, there is an urgent need to produce a developable resin composition with an excellent drying management range without the use of melamine, and to further provide a cured product with excellent acid resistance, metal plating resistance (metallurgical resistance), high temperature storage ability, and discoloration resistance (i.e., susceptibility to oxidative discoloration).

[0009] Therefore, the object of the present invention is to provide a melamine-free, photosensitive, heat-curable, developable two-component resin composition whose cured product has excellent acid resistance, metal plating resistance, high-temperature storage stability, and discoloration resistance, while also reducing the volatilization of harmful substances during the soldering stage and having an excellent drying control range.

[0010] Furthermore, the present invention aims to provide a dry film and a cured product having the above-mentioned excellent properties obtained using such a melamine-free photosensitive and heat-curable two-component resin composition, and a printed wiring board formed with a cured coating such as a solder resist using such a melamine-free photosensitive and heat-curable two-component resin composition, its dry film, or its cured product. Solutions for solving problems

[0011] The present inventors have conducted repeated and in-depth research to solve the above-mentioned problems. As a result, they have discovered that when melamine phthalate is used as a hardener and antioxidant in a specific amount in place of melamine in a photosensitive heat-hardening and developable two-component resin composition, melamine phthalate does not volatilize during the soldering process due to its unique structure. In addition, its antioxidant properties are consistent with those of melamine. The resulting melamine-free photosensitive heat-hardening and developable two-component resin composition has substantially the same other properties when used in solder resist inks.

[0012] Based on this, the present inventors have discovered that the above-mentioned problems can be solved by the following melamine-free, photosensitive, heat-curable, developable two-component resin composition, thereby completing the present invention. The melamine-free, photosensitive, heat-curable, developable two-component resin composition is characterized by comprising (A) a carboxyl vinyl ester resin, (B) a photopolymerization initiator, (C) a melamine phthalate, and (D) an epoxy resin, wherein the (A) carboxyl vinyl ester resin and the (B) photopolymerization initiator are contained in a first component, and the (D) epoxy resin is contained in a second component different from the first component, and the (C) melamine phthalate is contained in an amount of 1.2 to 11.8 parts by weight per 100 parts by weight of the (A) carboxyl vinyl ester resin, calculated as a solid content.

[0013] As a preferred embodiment of the present invention, in the above-mentioned melamine-free photosensitive thermosetting and developable two-component resin composition, the amount of the (C) melamine phthalate is 1.8 to 18.2 parts by weight relative to 100 parts by weight of the (D) epoxy resin in terms of solid content.

[0014] As a preferred embodiment of the present invention, the above-mentioned (C) melamine phthalate is contained in the first component.

[0015] As a preferred embodiment of the present invention, the melamine-free photosensitive thermosetting developable two-component resin composition further contains (E) an inorganic filler.

[0016] As a more preferred embodiment of the present invention, in the above-mentioned melamine-free photosensitive thermosetting and developable two-component resin composition, the (E) inorganic filler is contained in the first component.

[0017] As a preferred embodiment of the present invention, the melamine-free photosensitive thermosetting developable two-component resin composition further contains (F) a photosensitive monomer.

[0018] As a more preferred embodiment of the present invention, in the melamine-free photosensitive thermosetting developable two-component resin composition, the (F) photosensitive monomer is contained in the second component.

[0019] As a preferred embodiment of the present invention, in the above-mentioned melamine-free photosensitive heat-hardening and developable two-component resin composition, the first component and / or the second component further contains (G) an organic solvent. Another embodiment of the present invention relates to a dry film comprising a carrier film and a resin layer obtained by coating the melamine-free photosensitive thermosetting and developable two-component resin composition on the carrier film and drying the coating.

[0020] Yet another embodiment of the present invention relates to the above-mentioned melamine-free photosensitive thermosetting and developable two-component resin composition, characterized in that it is used for a solder resist.

[0021] Yet another embodiment of the present invention relates to a cured product, characterized in that it is obtained by curing the above-mentioned melamine-free photosensitive thermosetting and developable two-component resin composition.

[0022] Still another aspect of the present invention relates to a cured product, characterized in that it is obtained by curing the resin layer of the dry film.

[0023] Yet another aspect of the present invention relates to a printed circuit board, characterized by comprising the above-mentioned cured product. Effects of the Invention

[0024] As described above, the present invention can provide a melamine-free, photosensitive, heat-curable, developable two-component resin composition, a dry film thereof, a cured product thereof, and a printed circuit board, the cured product of which has excellent acid resistance, metal plating resistance, high-temperature storage stability, and discoloration resistance, reduces the volatilization of harmful substances during the soldering stage, and has an excellent drying control range. Implementation Method

[0025] []

[0026] Hereinafter, the melamine-free photosensitive thermosetting and developable two-component resin composition of the present invention will be described.

[0027] The melamine-free, photosensitive, heat-hardening, developable two-component resin composition of the present invention (hereinafter sometimes referred to as a "photosensitive, heat-hardening, developable two-component resin composition," "two-component resin composition," or "composition") comprises (A) a carboxyl vinyl ester resin, (B) a photopolymerization initiator, (C) a melamine phthalate, and (D) an epoxy resin. The (A) carboxyl vinyl ester resin and the (B) photopolymerization initiator are contained in a first component, and the (D) epoxy resin is contained in a second component different from the first component. The (C) melamine phthalate is present in an amount of 1.2 to 11.8 parts by weight per 100 parts by weight of the (A) carboxyl vinyl ester resin, calculated as a solid content.

[0028] The melamine-free, photosensitive, heat-curable, developable two-component resin composition of the present invention comprises a first component and a second component different from the first component. "Two-component" herein means consisting of at least a two-component system. Therefore, the two-component resin composition of the present invention may further comprise a third component or other components in addition to the first and second components.

[0029] An example of a two-component system is one in which one resin composition serves as a base component and another resin composition serves as a hardener component. In a two-component resin composition, the different components, such as the base component and the hardener component, are mixed immediately before use. During preparation, storage, and transportation, the different components are kept separate and isolated from each other to prevent reactions.

[0030] In the present invention, the first component containing (A) the carboxyl vinyl ester resin and (B) the photopolymerization initiator can be considered the base component, while the second component containing (D) the epoxy resin can be considered the hardener component. Therefore, in the two-component resin composition of the present invention, to avoid a reaction between the base and hardener during storage that could impair the solder resist ink's performance, it is preferred that the first component not contain (D) the epoxy resin, and the second component not contain (A) the carboxyl vinyl ester resin and (B) the photopolymerization initiator.

[0031] Hereinafter, the components contained in the melamine-free photosensitive thermosetting and developable two-component resin composition of the present invention will be described.

[0032] (A) Carboxyl vinyl ester resin The first component of the two-component resin composition of the present invention comprises (A) a carboxyl group-containing vinyl ester resin. The carboxyl group-containing vinyl ester resin (A) used in the present invention is particularly preferably one having an ethylenically unsaturated double bond in its molecule, as it can impart alkali developability, photohardening properties, and developer resistance. Examples include resins starting from epoxy resins, polyurethane resins having a urethane backbone, copolymeric resins having a copolymeric structure of an unsaturated carboxylic acid, and resins starting from phenolic compounds. Specific examples of carboxyl group-containing vinyl ester resins are shown below. (1) A carboxyl group-containing vinyl ester resin obtained by reacting a reaction product of a polyfunctional epoxy compound and an unsaturated monocarboxylic acid with a compound having at least one alcoholic hydroxyl group and one reactive group other than the alcoholic hydroxyl group that reacts with an epoxy group in one molecule, with a saturated or unsaturated polybasic acid anhydride; (2) A carboxyl-containing vinyl ester resin obtained by reacting an unsaturated monocarboxylic acid with a polyfunctional epoxy resin and then reacting it with a polyacid anhydride, and then reacting it with a compound having one oxirane ring and one or more ethylenically unsaturated groups in the molecule; (3) a carboxyl group-containing vinyl ester resin obtained by reacting a polyfunctional epoxy resin such as a phenol novolac epoxy resin, a cresol novolac epoxy resin, a bisphenol A cresol novolac epoxy resin, or a dicyclopentadiene cresol novolac 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 chains; (4) reacting the multifunctional epoxy resin obtained by further epoxidizing the hydroxyl groups of the multifunctional epoxy resin in (3) with epichlorohydrin with (meth)acrylic acid, and adding a polybasic acid anhydride to the generated hydroxyl groups to obtain a carboxyl group-containing vinyl ester resin; (5) Carboxyl vinyl ester resins obtained by adding cyclic ethers such as ethylene oxide or cyclic carbonates such as propylene carbonate to polyfunctional phenolic compounds such as novolac resins, partially esterifying the resulting hydroxyl groups with (meth) acrylic acid, and reacting the remaining hydroxyl groups with polyacid anhydrides; (6) Carboxyl group-containing vinyl ester resins obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as (meth)acrylate glycidyl ester or (meth)acrylate α-methylglycidyl ester, to any of the resins described above (3) to (5). Particularly preferred among these examples are cresol novolac type and phenol novolac type carboxyl vinyl ester resins, namely the carboxyl vinyl ester resins of (3), (4), (5) and (6). It should be noted that, in this specification, (meth)acrylate is a term that collectively refers to acrylate, methacrylate and mixtures thereof, and the same applies to other similar expressions.

[0033] Since the carboxyl group-containing vinyl ester resin (A) described above has a plurality of free carboxyl groups on the side chains of the main chain polymer, it can be developed with a dilute aqueous alkaline solution. The acid value of the carboxyl group-containing vinyl ester resin (A) is preferably in the range of 40 to 200 mgKOH / g, more preferably in the range of 45 to 120 mgKOH / g. An acid value of less than 40 mgKOH / g makes alkali development difficult, while an acid value exceeding 200 mgKOH / g promotes dissolution of the exposed portion by the developer, resulting in thinner lines than desired. This can also cause both exposed and unexposed portions to be dissolved and peeled off indiscriminately by the developer, making it difficult to create a normal resist pattern. This is undesirable.

[0034] The weight-average molecular weight of the carboxyl group-containing vinyl ester resin (A) varies depending on the resin backbone, but is generally preferably in the range of 2,000 to 150,000, more preferably 5,000 to 100,000. A weight-average molecular weight of less than 2,000 may result in poor application to a substrate and poor tack-free performance (dry-to-touch) after drying. Furthermore, the moisture resistance of the coating film after exposure may deteriorate, and film loss may occur during development, leading to significantly reduced resolution. On the other hand, a weight-average molecular weight exceeding 150,000 may significantly deteriorate developability and storage stability.

[0035] The blending amount of the carboxyl group-containing vinyl ester resin (A) is preferably in the range of 20 to 60% by mass of the total composition, and preferably 25 to 50% by mass, based on the solid content. A blending amount of the carboxyl group-containing vinyl ester resin (A) below this range is not preferred because it reduces the coating film strength. On the other hand, a blending amount exceeding this range is not preferred because it increases the viscosity of the composition and reduces the coating properties.

[0036] (B) Photopolymerization initiator The first component of the photosensitive and thermosetting two-component resin composition of the present invention comprises (B) a photopolymerization initiator. The photopolymerization initiator (B) can be any photopolymerization initiator commonly used in photosensitive and thermosetting two-component resin compositions without particular limitation. As the photopolymerization initiator (B), a known substance can be used, for example, bis(2,6-dichlorobenzyl)phenylphosphine oxide, bis(2,6-dichlorobenzyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzyl)phenylphosphine oxide, bis(2,6-dimethoxybenzyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dimethoxybenzyl)-2,5-dimethylphenylphosphine oxide, bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide, and bis(2,6-dimethoxybenzyl)phenylphosphine oxide; Monoacyl phosphine oxides such as diphenylphosphine oxide, 2,6-dichlorobenzyldiphenylphosphine oxide, 2,4,6-trimethylbenzylphenylphosphine oxide, methyl 2,4,6-trimethylbenzylphenylphosphine oxide, isopropyl neopentanoylphenylphosphine oxide, 2,4,6-trimethylbenzyldiphenylphosphine oxide, 2,4,6-trimethylbenzyl-di(p-tolyl)phosphine oxide; 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-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, etc. Benzoin, benzoyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, benzoin n-butyl ether and other benzoins; benzoin alkyl ethers; benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone and other benzophenones; 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)- Acetophenones such as 2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone and N,N-dimethylaminoacetophenone; thioxanthones such as 2-thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzoic acid esters such as ethyl 4-dimethylamino benzoate, 2-(dimethylamino)ethyl benzoate, and ethyl p-dimethylbenzoate;Oxime esters such as 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime) and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-oxazol-3-yl]-ethanone 1-(O-acetyloxime); titanocenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrol-1-yl)ethyl)phenyl]titanium; 2-nitrofluorene phenyl disulfide, butyroin, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide. (B) Photopolymerization initiators may be used alone or in combination of two or more. Examples of commercially available photopolymerization initiators (B) include oxime esters such as Irgacure OXE01 and Irgacure OXE02 manufactured by BASF Japan, and N-1919 and NCI-831 manufactured by ADEKA CORPORATION; α-hydroxyalkyl phenones such as Omnirad 184, Omnirad 1173, Omnirad 2959, and Omnirad 127 manufactured by IGM Resins BV; acetophenones such as Omnirad 907, Omnirad 369, and Omnirad 379 manufactured by IGM Resins BV; acylphosphine oxides such as Omnirad TPO manufactured by IGM Resins, Ltcure TMO manufactured by Shanghai Feikai Materials Technology Co., Ltd., and Omnirad 819 and Omnipol TP manufactured by IGM Resins BV; and Omnirad 784 and other titanocenes manufactured by BV.

[0037] The compounding ratio of the photopolymerization initiator (B) is preferably 0.01 to 30 parts by weight, preferably 5 to 25 parts by weight, and more preferably 10 to 20 parts by weight, per 100 parts by weight of the carboxyl group-containing vinyl ester resin (A) as a solid content. If the amount of the photopolymerization initiator (B) used is less than this range, the photocurability of the composition will deteriorate. On the other hand, if the amount is too high, the solder resist properties of the two-component resin composition of the present invention will be degraded, which is not preferred.

[0038] (C) Melamine Phthalate

[0039] The photosensitive, thermosetting, developable two-component resin composition of the present invention contains (C) melamine phthalate. The melamine phthalate (C) may be contained in either the first component or the second component, but is preferably contained in the first component, that is, in the main component.

[0040] The inventors compared the weight loss (i.e., volatile content) of two-component photosensitive, heat-curable, developable resin compositions containing melamine and melamine phthalate after thermal curing. They found that the composition containing melamine phthalate had significantly lower volatile content than the composition containing melamine. Furthermore, the composition containing melamine phthalate achieved comparable drying control margins, high-temperature storage stability, discoloration resistance, acid resistance, and metal plating resistance of its cured product. While the mechanism behind this is not fully elucidated, the inventors speculate as follows. On the one hand, melamine phthalate, because its structure contains melamine, acts as a hardener and antioxidant, similar to melamine. In other words, melamine phthalate prevents oxidation of copper circuits, thereby improving adhesion between the cured product and the substrate containing the copper circuits. Consequently, acid resistance, metal plating resistance, and high-temperature storage properties are improved. Furthermore, melamine phthalate suppresses discoloration of the copper circuitry that serves as the base of the cured product, thereby improving the cured product's discoloration resistance. Furthermore, due to its unique structure, melamine phthalate remains relatively stable in the composition during the soldering process, typically performed at 260°C. It is less likely to volatilize in the same large quantities as melamine. Therefore, using melamine phthalate instead of melamine can reduce the volatilization of harmful substances during soldering without affecting the performance of the composition.

[0041] The blending ratio of the melamine phthalate (C) is 1.2 to 11.8 parts by weight, preferably 1.8 to 10.2 parts by weight, per 100 parts by weight of the carboxyl group-containing vinyl ester resin (A), calculated as a solid content. If the amount of the melamine phthalate (C) used is less than 1.2 parts by weight, the curing agent and antioxidant functions are not effectively exerted, resulting in a cured product with good discoloration resistance. The acid resistance, high-temperature storage properties, and metal plating resistance tend to be insufficient. If the amount of the melamine phthalate (C) used exceeds 11.8 parts by weight, the drying range of the composition is poor, and volatile matter emissions during soldering increase significantly.

[0042] (D) Epoxy resin The second component of the photosensitive and heat-curable two-component resin composition of the present invention comprises (D) an epoxy resin. The (D) epoxy resin functions as a heat-curing component in the photosensitive and heat-curable two-component resin composition of the present invention to form a cured product. As such an epoxy resin, a well-known and commonly used multifunctional epoxy resin having at least two epoxy groups in one molecule can be used. The epoxy resin (D) used in the present invention may be liquid at room temperature, or may be solid or semi-solid. As the multifunctional epoxy resin, preferably bisphenol A type epoxy resin; brominated epoxy resin; 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; trishydroxyphenylmethane type epoxy resin; bixylenol type or biphenol type epoxy resin or a mixture thereof; bisphenol S type epoxy resin; bisphenol A novolac type epoxy resin; tetrahydroxyphenylethane type epoxy resin; Resins; heterocyclic epoxy resins; diglycidyl phthalate resins; tetraglycidyl dimethylbenzene resins; naphthyl-containing epoxy resins; epoxy resins having a dicyclopentadiene skeleton; glycidyl methacrylate copolymerized epoxy resins; cyclohexylmaleimide and glycidyl methacrylate copolymerized epoxy resins; epoxy-modified polybutadiene rubber derivatives; CTBN-modified epoxy resins; epoxy resins having an isocyanurate ring, etc., are not limited to these. These epoxy resins may be used alone or in combination of two or more.

[0043] "Epoxy resins that are solid or semi-solid at room temperature" can also be used as known and commonly used ones. For example, epoxy resins that are solid at room temperature include bisphenol A epoxy resin (jER1001 manufactured by Mitsubishi Chemical Corporation), bisphenol F epoxy resin (jER4004P manufactured by Mitsubishi Chemical Corporation), naphthalene epoxy resin (HP-4700 manufactured by DIC Corporation), polyfunctional solid epoxy resin containing a naphthalene skeleton (NC-7000 manufactured by Nippon Kayaku Co., Ltd.), trisphenol epoxy resin (EPPN-502H manufactured by Nippon Kayaku Co., Ltd.), polyfunctional solid epoxy resin containing a dicyclopentadiene skeleton (Epiclon manufactured by DIC Corporation), and epoxy resins that are solid or semi-solid at room temperature. HP-7200, HP-7200H), phosphorus-containing epoxy resin (TX0712 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), tris(2,3-epoxypropyl)isocyanurate (TEPIC manufactured by Nissan Chemical Industries, Ltd.). Epoxy resins that are semi-solid at room temperature include bisphenol A-type epoxy resin (jER834 manufactured by Mitsubishi Chemical Corporation) and naphthalene-type epoxy resins (HP-4032, EXA-4750, EXA-4700 manufactured by DIC Corporation, and ESN-190 and ESN-360 manufactured by Nippon Steel Chemical & Material Co., Ltd.). In the present invention, "solid or semi-solid at room temperature" means solid or semi-solid at 15°C. Determination of solid or semi-solid can be made in accordance with Annex 2, "Method for Confirming Liquid State," to the Ministerial Ordinance on the Testing and Properties of Dangerous Substances (Ministry of Home Affairs Ordinance No. 1, 1991). As the biphenyl-type epoxy resin, a well-known and commonly used multifunctional epoxy resin having a biphenyl skeleton can be used. Examples thereof include multifunctional solid epoxy resins containing a biphenyl skeleton (NC-3000H and NC-3000 manufactured by Nippon Kayaku Co., Ltd.) and biphenyl-type epoxy resins (YX-4000 and YL-6121HA manufactured by Mitsubishi Chemical Corporation). Examples of the novolac epoxy resin include cresol novolac epoxy resin (Epiclon N-690 manufactured by DIC Corporation), phenol novolac epoxy resin (Epiclon N-770 manufactured by DIC Corporation, jER152 manufactured by Mitsubishi Chemical Corporation), and the like.

[0044] The content of the epoxy resin (D) described above is preferably in the range of approximately 30 to 100 parts by weight, more preferably in the range of 40 to 90 parts by weight, and even more preferably in the range of 50 to 85 parts by weight, relative to 100 parts by weight of the carboxyl group-containing vinyl ester resin (A) as a solid content.

[0045] From the perspective of further exerting the effects of the present invention, such as improved discoloration resistance and reduced volatilization of harmful substances during the soldering stage, the amount of the melamine phthalate (C) is preferably 1.8 to 18.2 parts by weight, more preferably 2.3 to 16.9 parts by weight, and even more preferably 3.0 to 16.0 parts by weight, relative to 100 parts by weight of the epoxy resin (D) on a solids basis.

[0046] (E) Inorganic fillers The melamine-free, photosensitive, heat-curable, developable two-component resin composition of the present invention may contain (E) an inorganic filler. The inorganic filler (E) may be used alone or in combination of two or more. Examples of the inorganic filler (E) include titanium oxide, silicon dioxide, barium sulfate, barium titanate, Neuburg silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, and aluminum nitride. Among these, the inclusion of at least one of talc, silicon dioxide, and barium sulfate is preferred, as it can suppress the curing shrinkage of the cured product of the photosensitive and thermosetting two-component resin composition, thereby improving properties such as adhesion, hardness, and gloss. From the perspective of improving the mechanical properties, high-temperature storage resistance, processability, and chemical resistance of the cured product, the inorganic filler (E) is preferably included in the main component, that is, in the first component of the two-component resin composition of the present invention. In this case, the inorganic filler (E) is preferably at least one of silicon dioxide and barium sulfate.

[0047] (E) The inorganic filler may be surface-treated and used. More preferably, the surface of the inorganic filler is surface-treated to introduce a curable reactive group. Here, the term "hardening reactive group" refers to a group that undergoes a hardening reaction with (A) a carboxyl group-containing vinyl ester resin, (E) an epoxy resin, or the like. It may be a photocurable reactive group or a thermosetting reactive group. Examples of photocurable reactive groups include methacrylic, acryl, vinyl, and styryl groups. Examples of thermocurable reactive groups include epoxy, amino, hydroxyl, carboxyl, isocyanate, imino, oxetane, mercapto, methoxymethyl, methoxyethyl, ethoxymethyl, ethoxyethyl, and oxazoline groups. The method for introducing hardening reactive groups onto the surface of an inorganic filler is not particularly limited; any commonly known method can be used. The surface of the inorganic filler can be treated with a surface treatment agent having hardening reactive groups, such as a coupling agent having hardening reactive groups as organic groups. Examples of coupling agents include silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents. Examples of inorganic fillers that have been surface-treated to not have hardening reactive groups include silica-alumina surface treatment, titanate-based coupling agent treatment, aluminate-based coupling agent treatment, and organically treated inorganic fillers.

[0048] (E) The shape of the inorganic filler may be spherical, needle-like, flake-like, scaly, hollow, irregular, hexagonal, cubic, or flake-like. From the viewpoint of high filling of the inorganic filler, a spherical shape is preferred.

[0049] The average particle size (D50) of the inorganic filler (E) is 2000 nm or less, more preferably 1200 nm or less. The lower limit of the average particle size (D50) is preferably 0.1 nm or more. (E) The smaller the average particle size of the inorganic filler, the more diffuse reflection during light irradiation is suppressed, making it easier to finely process the pattern of the cured product. The average particle size (D50) can be determined using a laser diffraction particle size distribution analyzer or a dynamic light scattering analyzer. Examples of laser diffraction analyzers include the Microtrac MT3300EXII manufactured by MicrotracBEL Inc., and examples of dynamic light scattering analyzers include the Nanotrac Wave II UT151 manufactured by MicrotracBEL Inc.

[0050] The amount of the inorganic filler (E) is preferably in the range of 20 to 240 parts by weight, more preferably 50 to 200 parts by weight, and even more preferably 80 to 160 parts by weight, relative to 100 parts by weight of the carboxyl group-containing vinyl ester resin (A) as a solid content. When the inorganic filler is present in an amount of 20 parts by weight or greater, a cured film with superior acid resistance, metal plating resistance, and discoloration resistance tends to be obtained. When the inorganic filler is present in an amount of 240 parts by weight or less, a photosensitive and thermosetting two-component resin composition with superior degassing properties, resolution, and deep curing properties tends to be obtained.

[0051] (F) Photosensitive monomer The melamine-free, photosensitive, heat-curable, developable two-component resin composition of the present invention may contain (F) a photosensitive monomer. The photosensitive monomer (F) may be used alone or in combination of two or more. The photosensitive monomer (F) in the present invention is not particularly limited, and any known and commonly used photosensitive monomer can be used. For example, the photosensitive monomer (F) may be a compound having one or more ethylenically unsaturated groups in its molecule. Such a photosensitive monomer (if containing an ethylenically unsaturated group) contributes to the photocuring of the carboxyl group-containing vinyl ester resin (A) upon irradiation with active energy rays, thereby curing the photosensitive and thermosetting developable two-component resin composition.

[0052] From the perspective of avoiding a reaction during storage that would impair the performance of the solder resist ink, the photosensitive monomer (F) is preferably contained in the hardener, that is, in the second component of the two-component resin composition of the present invention.

[0053] (F) The photosensitive monomer preferably used in the present invention includes, for example, methyl α-(allyloxymethyl)acrylate, or diol diacrylates such as 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and 1,10-decanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, Tripropylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, diol diacrylates obtained by adding at least one of ethylene oxide and propylene oxide to neopentyl glycol, diol diacrylates such as caprolactone-modified hydroxypivalate neopentyl glycol diacrylate, bisphenol A EO adduct diacrylate, bisphenol A PO adduct diacrylate, tricyclodecane dimethanol diacrylate, hydrogenated dicyclopentadienyl diacrylate, cyclohexyl diacrylate esters, or bifunctional (meth)acrylates such as methacrylate monomers corresponding thereto, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolmethane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate, epichlorohydrin-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, tetramethylolmethane tetraacrylate, ethylene oxide-modified phosphoric acid triacrylate, epichlorohydrin-modified glycerol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, or polyfunctional acrylates such as silsesquioxane-modified products thereof, or methacrylate monomers corresponding thereto, trifunctional methacrylates, polyfunctional (meth)acrylates such as ε-caprolactone-modified tris(acryloyloxyethyl)isocyanurate, or combinations of two or more thereof.

[0054] The content of the photosensitive monomer (F) is preferably in the range of 5 to 90 parts by weight, more preferably 20 to 60 parts by weight, and even more preferably 30 to 50 parts by weight, relative to 100 parts by weight of the carboxyl group-containing vinyl ester resin (A) as a solid component. When the content of the photosensitive monomer (F) is within this range, the melamine-free photosensitive thermosetting and developable two-component resin composition has sufficient photocurability, and patterning during development is improved, and dryness to touch is also improved.

[0055] (G) Organic solvents

[0056] In the melamine-free, photosensitive, thermosetting, developable two-component resin composition of the present invention, an organic solvent (G) may be used in at least one component to synthesize the carboxyl vinyl ester resin (A), prepare the individual components of the composition, or adjust the overall viscosity of the composition obtained by mixing the components for coating on a substrate or carrier film.

[0057] Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. More specifically, they include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha. The above organic solvents may be used alone or in the form of a mixture of two or more.

[0058] The content of the organic solvent (G) is preferably in the range of 30 to 200 parts by weight, more preferably in the range of 40 to 150 parts by weight, and even more preferably in the range of 50 to 120 parts by weight, relative to 100 parts by weight of the carboxyl group-containing vinyl ester resin (A) calculated as solid content.

[0059] Other ingredients The melamine-free photosensitive thermosetting and developable two-component resin composition of the present invention may, of course, contain further additives as other components as needed without departing from the purpose of the present invention. Examples of such other ingredients include colorants such as pigments and dyes, thermal polymerization inhibitors, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, antioxidants, antibacterial / antifungal agents, defoaming agents, leveling agents, anti-sag agents, thickeners, adhesion-imparting agents, thixotropy-imparting agents, photoinitiator aids, sensitizers, photobase generators, thermoplastic resins, elastomers, organic fillers, release agents, surface treatment agents, dispersants, dispersing aids, surface modifiers, stabilizers, phosphors, and cellulose resins.

[0060] It should be noted that the photosensitive and thermosetting developable two-component resin composition of the present invention does not contain melamine, and therefore, the aforementioned other components do not include melamine.

[0061] The blending ratio of the aforementioned other components is preferably from 0.01% to 20% by weight of the total weight of the photosensitive / thermosetting / developable two-component resin composition. A blending ratio of less than 0.01% by weight fails to achieve the desired effect, while a blending ratio exceeding 20% by weight deteriorates the printability and hardness of the photosensitive / thermosetting / developable two-component resin composition, which is not preferred.

[0062] The first component and the second component of the photosensitive and heat-curable two-component developable resin composition of the present invention can be prepared by mixing and dispersing the respective components to be contained in predetermined amounts, for example, using a three-roll mill.

[0063] dry film A dry film can be prepared from the photosensitive and thermosetting developable two-component resin composition of the present invention. The dry film of the present invention comprises a resin layer obtained by coating the photosensitive, heat-curable, developable two-component resin composition of the present invention on a carrier film and drying the resin layer. To form the dry film, the first and second components (i.e., the base component and the hardener component) of the photosensitive, heat-curable, developable two-component resin composition of the present invention are thoroughly mixed. The mixed composition is then adjusted to an appropriate viscosity, either directly or by diluting it with a solvent as needed. The mixed composition is then applied to a uniform thickness on the carrier film using a comma coater, knife coater, lip coater, bar coater, extrusion coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like. The applied composition is then dried, typically at a temperature of 50-130°C for 1-30 minutes, to form the resin layer. The coating film thickness is not particularly limited, but is generally selected within the range of 10-150 μm, preferably 20-60 μm, after drying.

[0064] The carrier film is made of a plastic film, for example, polyester films such as polyethylene terephthalate (PET), polyimide films, polyamide-imide films, polypropylene films, polystyrene films, etc. The thickness of the carrier film is not particularly limited, but is generally selected within the range of 10 to 150 μm.

[0065] After forming a resin layer made from the composition of the present invention on a carrier film, it is preferable to further laminate a removable cover film on the surface of the resin layer to prevent dust and the like from adhering to the surface of the resin layer. Examples of the removable cover film include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper. The cover film may be any film as long as it is smaller than the adhesion between the resin layer and the carrier film when the cover film is peeled off.

[0066] It should be noted that in the present invention, the composition of the present invention may be applied to the aforementioned cover film and dried to form a resin layer, and a carrier film may be laminated on the surface of the resin layer. In other words, in the present invention, when producing a dry film, either a carrier film or a cover film may be used as the thin film to which the composition of the present invention is applied.

[0067] Here, a tack-free resin layer can also be formed by adjusting the photosensitive, thermosetting, developable two-component resin composition of the present invention to a viscosity suitable for the coating method using, for example, a high-boiling-point solvent, and applying it to a substrate by dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, or other methods. The high-boiling-point solvent contained in the composition is then evaporated and dried (temporarily dried) at a temperature of approximately 60-100°C. Alternatively, when the composition is applied to a carrier film or cover film, dried, and wound into a thin film, the resin layer can be formed by laminating the composition of the present invention to the substrate using a laminator, etc., with the layer in contact with the substrate, and then removing the carrier film.

[0068] As the above-mentioned substrate, in addition to printed circuit boards and flexible printed circuit boards with circuits pre-formed from copper or the like, there can also be mentioned: copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, PET films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc. The copper-clad laminates use materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, and copper-clad laminates for high-frequency circuits using fluorine, polyethylene, polyphenylene ether (polyphenylene oxide), cyanate ester, etc.

[0069] Hardened material When forming a cured product using the photosensitive, heat-curable, developable two-component resin composition of the present invention, the composition is applied to a substrate, the solvent evaporated, and dried to form a resin layer. The resulting resin layer is then exposed (irradiated with light) to cure the exposed areas (the areas exposed to light). Specifically, exposure is selectively performed with active energy rays through a patterned photomask using a contact or non-contact method, or direct pattern exposure is performed using a laser direct exposure system. The unexposed areas are then developed using an alkaline aqueous solution (e.g., a 0.3-3% by mass sodium carbonate aqueous solution) to form a resist pattern. The composition is then heated to a temperature of approximately 100-180°C for heat curing (post-curing), resulting in a cured film (cured product) with excellent properties such as heat resistance, chemical resistance, moisture absorption resistance, adhesion, and electrical properties.

[0070] The volatilization drying or thermal curing when forming the above-mentioned cured product can be carried out, for example, using a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven, etc. (using a device with a heat source using steam to heat the air, a method of causing the hot air in the dryer to contact by convection, or a method of blowing the hot air onto the support using a nozzle).

[0071] Furthermore, exposure equipment used for the above-mentioned active energy ray irradiation can be any device equipped with a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a mercury short-arc lamp, or the like, and capable of irradiating ultraviolet light within a wavelength range of 350 to 450 nm. Furthermore, direct drawing equipment (e.g., a laser direct imaging device that directly draws an image using a laser using CAD data from a computer) can also be used. The lamp or laser light source used in a direct drawing equipment can have a maximum wavelength within the range of 350 to 410 nm. The exposure dose used for image formation varies depending on film thickness, but is generally within the range of 20 to 1000 mJ / cm², preferably 20 to 800 mJ / cm².

[0072] Next, in the development step, the dried coating film after the exposure step is treated with a developer. This removes the unexposed portions of the coating film, thereby forming a patterned film of the curable composition of the present invention.

[0073] Here, methods used in the development step include immersion, showering, spraying, and brushing. A typical developer is a 0.5-5% sodium carbonate aqueous solution. Other alkaline aqueous solutions, such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines, can also be used.

[0074] The developing step is performed at a developer temperature of 20 to 40° C. and a developing time of 180 seconds or less.

[0075] It should be noted that in the development step, the obtained pattern film is washed with a rinse solution as needed. As the rinse solution, distilled water, methanol, ethanol, isopropyl alcohol, etc. can be used alone or in combination.

[0076] printed circuit boards The present invention can also provide a printed circuit board having the above-mentioned cured product. The photosensitive and thermosetting developable two-component resin composition, dry film or cured product of the present invention can be used as a solder resist for printed circuit boards.

[0077] The present invention will be described in further detail based on Examples and Comparative Examples. However, the scope of the present invention and its embodiments are not limited to these. "Parts" and "%" in the Examples and Comparative Examples are by weight unless otherwise specified. The properties of the compositions of these Examples were tested using the methods described below. Example

[0078] [Synthesis Example: Synthesis of Carboxyl Vinyl Ester Resin]

[0079] In a four-necked flask equipped with a stirrer and a reflux condenser, 214 parts of cresol novolac-type epoxy resin EPICLON N-695 (manufactured by DIC Corporation, epoxy equivalent = 214) were added, followed by 103 parts of carbitol acetate and 103 parts of a petroleum hydrocarbon solvent (trade name: Cactus Fines SF-01, manufactured by Japan Energy Corporation) and dissolved by heating. Next, 0.1 parts of hydroquinone as a polymerization inhibitor and 2.0 parts of triphenylphosphine as a reaction catalyst were added. The mixture was heated to 95-105°C, and 72 parts of acrylic acid was slowly added dropwise. The reaction mixture was allowed to react for 16 hours. The resulting reaction product was cooled to 80-90°C, and 91.2 parts of tetrahydrophthalic anhydride was added. The reaction mixture was allowed to react for 8 hours, cooled, and then removed. The resulting carboxyl vinyl ester resin had a nonvolatile content of 65% and an acid value of 87.5 mgKOH / g on solids.

[0080] The carboxyl vinyl ester resin solution (varnish) from the above synthesis example was blended with the various components and proportions (parts by weight) listed in Table 1. After premixing with a blender, the mixture was kneaded with a three-roll mill to prepare a photosensitive, heat-curable, developable two-component resin composition. The composition was then evaluated for drying control margin, acid resistance, metal plating resistance, high-temperature storage stability, volatile matter content, and discoloration resistance according to the following methods. "ND" indicates that the result was not detected and was below the detection limit. The components described in Table 1 are as follows. *1: Carboxyl vinyl ester resin obtained in Synthesis Example, solid content 65%, solvent 35% *2: Pigment: 6Y-501, manufactured by TOYOCOLOR CO., LTD. *3: Additives: KS-66, manufactured by Shin-Etsu Chemical Co., Ltd., BYK-1790, manufactured by BYK Additives (Shanghai) Co., Ltd. *4: Initiator: ITX, isopropylthioxanthone (manufactured by DKSH JAPAN), #907: α-aminoacetophenone-based photopolymerization initiator (Omnirad 907 manufactured by IGM Resins) *5: Filler: B-30, manufactured by Sakai Chemical Industry Co., Ltd., A-8, manufactured by Sibelco *6:Solvent: DPM: dipropylene glycol monomethyl ether, manufactured by Taiwan Leander Co., Ltd. *7: Melamine: MELAMINE-JC, manufactured by Jiangsu Jinxiang Sairui Chemical Technology Co., Ltd. *8: Melamine Phthalate: THPAMELAMINESALT, manufactured by Shikoku Chemical Industry Co., Ltd. *9: Epoxy resin: N-770, manufactured by DIC Corporation, novolac-type multifunctional epoxy resin, solid content 100% *10: Photosensitive monomer: DPHA, dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd.

[0081] For the photosensitive and heat-curable developable two-component resin compositions of the above-mentioned examples and comparative examples, the following tests were conducted after mixing the first component and the second component.

[0082] <Drying Management Scope (Time from Drying to Exposure and Development)> Each composition listed in Table 1 was screen-printed onto the entire surface of a patterned copper foil substrate and dried in a hot air recirculating oven at 80°C. From 20 to 70 minutes after the start of drying, the substrate was removed every 10 minutes and slowly cooled to room temperature. The substrate was then developed using a 1 wt% sodium carbonate aqueous solution at 30°C at a spray pressure of 0.2 MPa for 60 seconds. The maximum allowable drying time without residue was used as the drying control range. ○: The maximum allowable drying time without leaving residue is more than 50 minutes ×: The maximum allowable drying time without leaving residue is less than 50 minutes

[0083] <Acid resistance> Each composition listed in Table 1 was screen-printed to a thickness of 40 μm onto the entire surface of a substrate with a 2 mm copper wire pattern. The coating was then dried in a hot air circulation oven at 80°C for 30 minutes. After cooling to room temperature, the pattern was exposed using an exposure device equipped with a high-pressure mercury lamp at 400 mJ / cm². The coating was then developed in a 1 wt% sodium carbonate aqueous solution at a pressure of 0.2 MPa and a temperature of 30°C for 60 seconds, followed by curing in a hot air circulation oven at 150°C for 60 minutes. Evaluation substrates were prepared by irradiating the substrate with ultraviolet light in a UV conveyor oven at a cumulative exposure dose of 2000 mJ / cm². The evaluation substrate was immersed in a 10 vol% H2SO4 aqueous solution at room temperature for 20 minutes, repeated a total of 5 times, and the penetration and dissolution of the cured coating were visually confirmed, and further peeling due to tape peeling was confirmed. ○: No change observed △: Only slightly changed ×: The coating film is bulging or swelling and falling off

[0084] <Metal plating resistance> Separate evaluation substrates were prepared using the same method as for the evaluation substrate described in the "Acid Resistance" section above. These evaluation substrates were plated using commercially available electroless nickel and gold plating baths to a thickness of 0.5 μm for nickel and 0.03 μm for gold. The presence of plating penetration was evaluated, and the presence of peeling of the cured coating was evaluated by tape stripping. The evaluation criteria were as follows. ○: No penetration or peeling is observed △: Slight penetration can be seen after plating, and peeling can be seen after stripping ×: Peeling occurs after plating

[0085] <High-temperature storage stability (TS test)>

[0086] Prepare another evaluation substrate using the same method as the evaluation substrate described in "Acid Resistance" above. Place this evaluation substrate in a 160°C oven for several different times and perform a 100-grid test as follows. Record the maximum number of hours it takes for the 100-grid test to show no signs of peeling.

[0087] 100-grid test: After post-baking, use a brand new blade to scratch the surface of the hardened coating at a 30-degree angle to the board surface, creating a grid pattern. Then, use 3M tape to perform a peel test. The judgment criteria are as follows.

[0088] ○: The high temperature storage time without shedding in the 100-grid test is more than 1000 hours

[0089] ×: The high temperature storage time without shedding in the 100-grid test is less than 1000 hours

[0090] <Volatile Matter Evaluation> Another evaluation substrate was prepared using the same method as the evaluation substrate described in the "Acid Resistance" section above. The cured coating film on this evaluation substrate was pretreated according to US EPA 3550C:2007 after post-curing, and the volatile content was analyzed using HPLC, GC-MC, and LC-MS-MS.

[0091] The lower the amount of volatile matter measured by LC-MS / MS, the less harmful substances are volatilized during the welding process. In the present invention, a volatile matter level of less than 1000 ppm is considered acceptable.

[0092] <Discoloration resistance> A separate evaluation substrate was prepared using the same method as the evaluation substrate described in the "Acid Resistance" section above. The L*a*b* values of the cured coating film were measured using a Konica Minolta CM-2600d spectrophotometer. Subsequently, the substrate was heat treated at 150°C for 2 hours (i.e., accelerated degradation) and the L*a*b* values were measured using the same method. ΔEab was calculated from the measured values using the following formula. ΔEab=((L * 2-L * 1) 2+(a * 2-a * 1) 2+(b * 2-b * 1) 2) 0.5 (Wherein, L*1, a*1, and b*1 represent the values of L*, a*, and b* before heat treatment, respectively; L*2, a*2, and b*2 represent the values of L*, a*, and b* after heat treatment, respectively.)

[0093] Here, ΔEab is calculated as the difference between the initial value and the value after accelerated degradation in the L*a*b* colorimetric system. A larger value indicates a greater likelihood of oxidative discoloration, indicating lower discoloration resistance.

[0094] As shown above, Examples 1-4, by incorporating melamine phthalate in appropriate amounts, can produce melamine-free, photosensitive, heat-curable, developable two-component resin compositions that excel in all evaluations of drying control margin, acid resistance, metal plating resistance, high-temperature storage stability, volatiles, and discoloration resistance. In contrast, Comparative Example 1, which contains neither melamine phthalate nor melamine, yields a cured product with poor acid resistance, metal plating resistance, and discoloration resistance. Comparative Example 2, which contains a small amount of melamine, and Comparative Example 7, which contains an insufficient amount of melamine phthalate, exhibit slightly improved acid resistance and metal plating resistance compared to Comparative Example 1, but these are still insufficient, and discoloration resistance remains poor. Comparative Examples 2-6, while using a certain amount of melamine improves acid resistance, metal plating resistance, and discoloration resistance, significantly increases volatiles. In addition, in Comparative Example 6 containing a large amount of melamine and Comparative Example 8 containing an excessive amount of melamine phthalate, the drying control range was poor and the amount of volatile matter was slightly high.

[0095] These results demonstrate that the melamine-free, photosensitive and heat-curable, two-component resin composition of the present invention has an excellent drying control range, can reduce the volatilization of harmful substances during the soldering process, and can produce a cured product with excellent acid resistance, metal plating resistance, high-temperature storage resistance, and discoloration resistance. The melamine-free, photosensitive and heat-curable, two-component resin composition of the present invention, dry films using the composition, and cured products thereof are suitable for use as solder resists for printed circuit boards.

Claims

1. A melamine-free photosensitive thermocurable and developable two-component resin composition, characterized in that it comprises (A) a carboxyl vinyl ester resin, (B) a photopolymerization initiator, (C) melamine phthalate, and (D) an epoxy resin, wherein the aforementioned (A) carboxyl vinyl ester resin and the aforementioned (B) photopolymerization initiator are contained in a first component, and the aforementioned (D) epoxy resin is contained in a second component different from the aforementioned first component, wherein the aforementioned (C) melamine phthalate is 1.2 to 11.8 parts by weight relative to 100 parts by weight of the aforementioned (A) carboxyl vinyl ester resin based on solids, and the aforementioned (C) melamine phthalate is 1.8 to 18.2 parts by weight relative to 100 parts by weight of the aforementioned (D) epoxy resin based on solids.

2. The melamine-free photosensitive thermocurable and developable two-component resin composition of claim 1, characterized in that the aforementioned (C) melamine phthalate is contained in the aforementioned first component.

3. The melamine-free photosensitive thermosetting and developable two-component resin composition of claim 1 or 2, characterized in that it further contains (E) inorganic filler.

4. The melamine-free photosensitive thermocurable and developable two-component resin composition of claim 3, characterized in that the aforementioned inorganic filler (E) is contained in the aforementioned first component.

5. The melamine-free photosensitive thermocurable and developable two-component resin composition of claim 1 or 2, characterized in that it further contains (F) a photosensitive monomer.

6. The melamine-free photosensitive thermocurable and developable two-component resin composition of claim 5, characterized in that the aforementioned (F) photosensitive monomer is contained in the aforementioned second component.

7. The melamine-free photosensitive thermosetting and developable two-component resin composition of claim 1 or 2, characterized in that the aforementioned first component and / or the aforementioned second component further contain (G) an organic solvent.

8. A melamine-free photosensitive thermosetting and developable two-component resin composition as claimed in claim 1 or 2, characterized in that it is used as a solder resist.

9. A dry film, characterized in that it comprises: a carrier film, and a resin layer obtained by coating the aforementioned carrier film with a melamine-free photothermal curing and developing two-component resin composition as claimed in any one of claims 1 to 8 and drying it.

10. A cured material, characterized in that it is obtained by curing a melamine-free photothermolytic and developable two-component resin composition as claimed in any one of claims 1 to 8.

11. A hardened material, characterized in that it is obtained by hardening the resin layer of the dry film as claimed in claim 9.

12. A printed circuit board, characterized in that it has a hardened material as claimed in claim 10 or 11.