Curable resin composition and printed circuit board

Abstract

To provide a curable resin composition that can be used in combination with an inorganic filler containing an alkaline earth metal and a photopolymerization initiator having an oxime ester bond, and that is less prone to sensitivity degradation over time, and a printed circuit board having a cured product of the curable resin composition. [Solution] A curable resin composition obtained by mixing liquid A and liquid B, wherein liquid A comprises a carboxyl group-containing resin (A) and an inorganic filler (B), liquid B comprises an epoxy compound (C) and a photopolymerization initiator (D) having an oxime ester bond, and the inorganic filler (B) comprises an inorganic filler (B-1) containing an alkaline earth metal.

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition and a printed circuit board having a cured product of the curable resin composition. [Background technology]

[0002] A curable resin composition containing a photosensitive resin is used as a material for forming a cured product (e.g., a solder resist layer) on a printed circuit board. Furthermore, to promote the photopolymerization reaction of the curable resin composition, a curable resin composition is provided that uses a photopolymerization initiator having a highly sensitive oxime ester bond as the photopolymerization initiator (see Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-107182 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0004] To reduce the thermal expansion coefficient of the cured product, curable resin compositions containing inorganic fillers such as barium sulfate and talc have also been provided. However, curable resin compositions containing inorganic fillers such as barium sulfate and alkaline earth metals such as talc, and the above-mentioned photopolymerization initiator having an oxime ester bond, have the problem that their sensitivity decreases over time.

[0005] From the above, the main object of the present invention is to provide a curable resin composition that does not easily experience a decrease in sensitivity over time, even when using an inorganic filler containing an alkaline earth metal and a photopolymerization initiator having an oxime ester bond in combination, and a printed circuit board having a cured product of the curable resin composition. [Means for solving the problem]

[0006] (1) A curable resin composition according to one aspect of the present disclosure is a curable resin composition obtained by mixing liquid A and liquid B, wherein liquid A comprises a carboxyl group-containing resin (A) and an inorganic filler (B), liquid B comprises an epoxy compound (C) and a photopolymerization initiator (D) having an oxime ester bond, and the inorganic filler (B) comprises an inorganic filler (B-1) containing an alkaline earth metal.

[0007] (2) In the configuration described in (1) above, the photopolymerization initiator (D) having an oxime ester bond may include a photopolymerization initiator having an oxime ester bond and a nitro group.

[0008] (3) In the configuration described in (2) above, the photopolymerization initiator (D) having an oxime ester bond may include a compound represented by the following general formula (1). [ka] (In formula (1) above, R1 represents hydrogen, an alkyl group having 1 to 17 carbon atoms, or an alkoxy group having 1 to 17 carbon atoms, and R2 represents a phenyl group, or an alkyl group having 1 to 5 carbon atoms, -OC m H 2m -CH3 and -OC n H 2n -OC p H 2p - Represents a phenyl group substituted with one or more substituents selected from the group consisting of CH3, where m is an integer from 0 to 5, n is an integer from 1 to 5, and p is an integer from 0 to 5.

[0009] (4) In the configuration described in any one of (1) to (3) above, the B liquid may contain the inorganic filler (B-1) in a mass ratio of the inorganic filler (B-1):the photopolymerization initiator (D) having an oxime ester bond in the range of 0:1 to 15:1.

[0010] (5) In the configuration described in any one of (1) to (4) above, the content ratio of the carboxyl group-containing resin (A), the inorganic filler (B-1), and the photopolymerization initiator (D) having an oxime ester bond contained in the curable resin composition may be, by mass ratio, the carboxyl group-containing resin (A): inorganic filler (B-1): photopolymerization initiator (D) having an oxime ester bond = 50:5:0.05 to 50:100:6.

[0011] (6) A cured product according to one aspect of the present disclosure is obtained by curing a curable resin composition described in any one of (1) to (5) above.

[0012] (7) A printed circuit board according to one aspect of the present disclosure has the cured product described in (6) above. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a curable resin composition that does not easily experience a decrease in sensitivity over time, even when using an inorganic filler containing an alkaline earth metal and a photopolymerization initiator having an oxime ester bond in combination, and a printed circuit board having a cured product of the curable resin composition. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments.

[0015] (1) Curable resin composition The curable resin composition of this embodiment is a curable resin composition obtained by mixing liquid A and liquid B, wherein liquid A comprises a carboxyl group-containing resin (A) and an inorganic filler (B), and liquid B comprises an epoxy compound (C) and a photopolymerization initiator (D) having an oxime ester bond.

[0016] (1-1)A liquid Carboxyl group-containing resin (A) As the carboxyl group-containing resin (A), any resin having a carboxyl group may be used. In particular, for imparting photosensitivity, a carboxyl group-containing resin having at least one unsaturated double bond can be mentioned. Examples of the carboxyl group-containing resin (A) include a carboxyl group-containing resin (A-1) obtained by reacting a polybasic acid or a polybasic acid anhydride with the hydroxyl group of a product obtained by reacting an epoxy compound having a plurality of epoxy groups in one molecule with a radically polymerizable unsaturated monocarboxylic acid (radically polymerizable unsaturated monocarboxylic acid-modified epoxy resin).

[0017] The epoxy equivalent of the epoxy compound having a plurality of epoxy groups in one molecule is not particularly limited, but is preferably 3,000 g / eq or less, more preferably 1,000 g / eq or less, and particularly preferably 100 g / eq or more and 500 g / eq or less. Examples of the epoxy compound having a plurality of epoxy groups in one molecule include biphenyl-type epoxy resins; naphthalene-type epoxy resins; dicyclopentadiene-type epoxy resins; rubber-modified epoxy resins such as silicone-modified epoxy resins; ε-caprolactone-modified epoxy resins; bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; novolak-type epoxy resins such as phenol novolak-type epoxy resins, о-cresol novolak-type epoxy resins, and p-tert-butylphenol novolak-type epoxy resins; alicyclic epoxy resins having a cyclohexene oxide group, a tricyclodecane oxide group, and a cyclopentene oxide group; triglycidyl isocyanurate having a triazine ring such as (2-hydroxyethyl) isocyanurate; dicyclopentadiene-type epoxy resins; adamantane-type epoxy resins, and the like. These can be used alone or in combination of two or more.

[0018] Examples of the radically polymerizable unsaturated monocarboxylic acid include acrylic acid, Methacrylic acid, crotonic acid, and cinnamic acid can be used. Among these, acrylic acid and methacrylic acid are preferred.

[0019] Furthermore, the epoxy compound having multiple epoxy groups in one molecule and the radically polymerizable unsaturated monocarboxylic acid can be reacted by known methods. For example, the epoxy compound having multiple epoxy groups in one molecule and the radically polymerizable unsaturated monocarboxylic acid can be reacted by heating in a suitable diluent.

[0020] The aforementioned polybasic acid or polybasic anhydride can be either saturated or unsaturated. Examples of the polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4-ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, trimellitic acid, pyromellitic acid, and diglycolic acid. Examples of the polybasic acid anhydrides include these anhydrides. These can be used individually or in combination. The polybasic acid or polybasic anhydride is introduced into the radical polymerizable unsaturated monocarboxylated epoxy resin by reacting it with the hydroxyl groups generated in the radical polymerizable unsaturated monocarboxylated epoxy resin.

[0021] Furthermore, as the carboxyl group-containing resin (A), a carboxyl group-containing resin (A-2) obtained by reacting the carboxyl group of the carboxyl group-containing resin (A-1) with a glycidyl compound having one or more radically polymerizable unsaturated groups and epoxy groups may be used. These can be used individually or in combination of multiple types.

[0022] Examples of glycidyl compounds having one or more radically polymerizable unsaturated groups and epoxy groups include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and pentaerythritol triacrylate monoglycidyl ether. Note that multiple glycidyl groups may be present in a single molecule of these glycidyl compounds.

[0023] Furthermore, as the carboxyl group-containing resin (A), a carboxyl group-containing resin (A-3) can also be used, which is obtained by reacting a copolymer obtained by reacting (meth)acrylic acid with a (meth)acrylic acid ester with an alicyclic epoxy skeleton having an ethylenically unsaturated bond to some of the carboxyl groups. (Meth)acrylic acid esters are not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, butyl (meth)acrylate, hydroxybutyl (meth)acrylate, propyl (meth)acrylate, and hydroxypropyl (meth)acrylate. Alicyclic epoxy is a compound or resin having an alicyclic skeleton and epoxy groups, where the skeleton is formed by an aliphatic cyclic compound or a chain thereof. The epoxy equivalent is not particularly limited, but is preferably 100 to 1000, and particularly preferably 100 to 500. Examples of aliphatic cyclic compounds include cyclohexane and cyclopentane. Examples of alicyclic epoxy include 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate, vinylcyclohexene monooxide 1,2-epoxy-4-vinylcyclohexane, and the 1,2-epoxy-4-(2-oxyranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol. Examples of ethylenically unsaturated bonds include acrylic groups and methacrylic groups. When a copolymer obtained by reacting (meth)acrylic acid with a (meth)acrylic acid ester is reacted with an epoxy group of an alicyclic epoxy having an ethylenically unsaturated bond, the epoxy group cleaves due to the reaction between the epoxy group and the carboxyl group, generating a hydroxyl group and an ester bond, thereby obtaining the carboxyl group-containing resin (A-3).

[0024] Inorganic filler (B) Examples of inorganic fillers (B) include titanium oxide, zirconium oxide, niobium oxide, antimony oxide, tartan oxide, tin oxide, zinc oxide, magnesium oxide, iron oxide, calcium carbonate, barium titanate, barium sulfate, aluminum borate, alumina, silica, and talc. These can be used individually or in combination. Among these, inorganic fillers (B-1) containing alkaline earth metals such as calcium carbonate, barium titanate, barium sulfate, magnesium oxide, and talc are preferred.

[0025] The total content of inorganic filler (B) can be 10 parts by mass or more and 200 parts by mass or less per 100 parts by mass of solid content of carboxyl group-containing resin (A). Alternatively, the content can be 15 parts by mass or more and 150 parts by mass or 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of solid content of carboxyl group-containing resin (A).

[0026] Furthermore, the content of inorganic filler (B-1) can be 10 parts by mass or more and 200 parts by mass or less per 100 parts by mass of solid content of carboxyl group-containing resin (A). Alternatively, the content can be 15 parts by mass or more and 150 parts by mass or 20 parts by mass or more and 100 parts by mass or less per 100 parts by mass of solid content of carboxyl group-containing resin (A).

[0027] (1-2)B liquid Epoxy compound (C) Examples of epoxy compounds (C) include biphenyl-type epoxy resins; naphthalene-type epoxy resins; dicyclopentadiene-type epoxy resins; rubber-modified epoxy resins such as silicone-modified epoxy resins; ε-caprolactone-modified epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins, o-cresol novolac-type epoxy resins, and p-tert-butylphenol novolac-type epoxy resins; alicyclic epoxy resins having cyclohexene oxide groups, tricyclodecane oxide groups, and cyclopentene oxide groups; triglycidyl isocyanurates having a triazine ring such as (2-hydroxyethyl) isocyanurate; dicyclopentadiene-type epoxy resins; and adamantane-type epoxy resins. These can be used individually or in combination of multiple types.

[0028] The content of the epoxy compound (C) can be 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the solid content of the carboxyl group-containing resin (A). Further, the content can also be 20 parts by mass or more and 80 parts by mass or less, or 25 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the solid content of the carboxyl group-containing resin (A).

[0029] A photopolymerization initiator (D) having an oxime ester bond Examples of the photopolymerization initiator (D) having an oxime ester bond include a photopolymerization initiator having a carbazole skeleton, a photopolymerization initiator having a diketone skeleton, a photopolymerization initiator having a thioxanthene skeleton, a photopolymerization initiator having a phenylthio skeleton, and the like. These can be used alone or in combination of two or more. Among these, a photopolymerization initiator having an oxime ester bond and a carbazole skeleton is preferably used, and among them, a photopolymerization initiator having a nitro group is more preferably used.

[0030] Further, as the photopolymerization initiator having an oxime ester bond, a carbazole skeleton, and a nitro group, a compound represented by the following general formula (1) can be used.

Chemical formula

[0031] Examples of photopolymerization initiators having oxime ester bonds and a carbazole skeleton include ethanolone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime); 1,8-octanedione, 1,8-bis[9-ethyl-6-nitro-9H-carbazole-3-yl]-,1,8-bis(O-acetyloxime); 1,8-octanedione, 1,8-bis[9-(2-ethylhexyl)-6-nitro-9H-carbazole-3-yl]-,1,8-bis(O-acetyloxime); and methanone (9-ethyl-6-nitro-9H-carbazole-3-yl)[4-(2-methoxy-1-methylethoxy)-2-methylphenyl]-O-acetyloxime. Among these, metanon(9-ethyl-6-nitro-9H-carbazole-3-yl)[4-(2-methoxy-1-methylethoxy)-2-methylphenyl]-O-acetyloxime is preferably used as the compound represented by the above general formula (1).

[0032] The content of the photopolymerization initiator (D) having an oxime ester bond may be 0.05 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the solid content of the carboxyl group-containing resin (A). Alternatively, the content may be 0.08 parts by mass or more and 2.0 parts by mass or 0.1 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the solid content of the carboxyl group-containing resin (A).

[0033] The curable resin composition of this embodiment, having such a configuration, uses an inorganic filler containing an alkaline earth metal and a photopolymerization initiator having an oxime ester bond in combination, yet is less prone to sensitivity degradation over time. Therefore, the curable resin composition of this embodiment, while containing an inorganic filler containing an alkaline earth metal, can form a cured product with a desired pattern, particularly a fine pattern. Furthermore, since the curable resin composition of this embodiment is less prone to sensitivity degradation over time, improvements in adhesion and deep curing properties of the cured product to the bonded material can also be expected.

[0034] Furthermore, the curable resin composition of this embodiment may contain the inorganic filler (B-1) in liquid B in a mass ratio of inorganic filler (B-1):photopolymerization initiator (D) having an oxime ester bond = 0:1 to 15:1. That is, the inventors of this application have found a content ratio that allows the inorganic filler (B-1) and the photopolymerization initiator (D) having an oxime ester bond to be contained in the same composition while minimizing the decrease in sensitivity of the curable resin composition over time. In addition, if the inorganic filler (B-1) is also contained in liquid B in the above content ratio, it can be expected that the inorganic filler (B-1) will disperse more easily in the curable resin composition when liquid A and liquid B are mixed.

[0035] Furthermore, the curable resin composition of this embodiment can have a mass ratio of carboxyl group-containing resin (A), inorganic filler (B-1), and photopolymerization initiator (D) having an oxime ester bond, such that the ratio is carboxyl group-containing resin (A): inorganic filler (B-1): photopolymerization initiator (D) having an oxime ester bond = 50:5:0.05 to 50:100:6. Preferably, the ratio can be 50:10:0.1 to 50:50:1. By setting the content ratio of the carboxyl group-containing resin (A), the inorganic filler (B-1), and the photopolymerization initiator (D) having an oxime ester bond within this range, the decrease in sensitivity of the curable resin composition over time can be made less likely.

[0036] Furthermore, the curable resin composition of this embodiment may contain the following components as optional components.

[0037] Reactive diluent The curable resin composition of this embodiment may contain a reactive diluent for the purpose of promoting the photocuring of the curable resin composition. It is preferable that the reactive diluent be contained in solution B. The reactive diluent is a compound having one or more polymerizable double bonds in one molecule and undergoing a reaction in which molecules bond together when exposed to light energy. For example, (meth)acrylate compounds such as monofunctional (meth)acrylate compounds and polyfunctional (meth)acrylate compounds can be used. Examples of such reactive diluents include 2-hydroxyethyl methacrylate, phenoxyethyl methacrylate, diethylene glycol monomethacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, and dicyclopentanyl di(meth)acrylate. Examples include ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. These can be used individually or in combination of multiple types.

[0038] The content of the reactive diluent can be 10 parts by mass or more and 120 parts by mass per 100 parts by mass of the solid content of the carboxyl group-containing resin (A). Alternatively, the content can be 20 parts by mass or more and 80 parts by mass, or 25 parts by mass or more and 50 parts by mass per 100 parts by mass of the solid content of the carboxyl group-containing resin (A).

[0039] Coloring agents The curable resin composition of this embodiment may contain a coloring agent for the purpose of imparting color to the curable resin composition. Pigments and dyes can be used as the coloring agent. Its components are not particularly limited, nor is its color particularly limited. The content of the coloring agent is not particularly limited, but for example, it can be 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the solid content of the carboxyl group-containing resin (A).

[0040] The curable resin composition of this embodiment may contain a curing catalyst for the purpose of accelerating the curing of the curable resin composition. Examples of the curing catalyst include amine compounds such as dicyandiamide, melamine and its derivatives, boron trifluoride-amine complex and polyamine, amineimide compounds, imidazole compounds, organic acid hydrazides, diaminomaleonitrile, guanamine, and other compounds. These can be used individually or in combination of multiple types. It is desirable that the curing catalyst be contained in solution A. The content of the curing catalyst is not particularly limited, but for example, it can be 0.001 parts by mass or more and 10 parts by mass, 0.1 parts by mass or more and 5 parts by mass, or 0.5 parts by mass or more and 1 part by mass, per 100 parts by mass of the solid content of the epoxy compound (C).

[0041] Other photopolymerization initiators The curable resin composition of this embodiment may contain other photopolymerization initiators, provided that they do not impair its effects. Such other photopolymerization initiators are not particularly limited as long as they initiate the polymerization reaction of the curable resin composition upon irradiation with active energy rays. Examples include α-aminoalkylphenone-based photopolymerization initiators, benzoin-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzophenone-based photopolymerization initiators, anthraquinone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, dimethyl ketal-based photopolymerization initiators, phosphine oxide-based photopolymerization initiators, and ketone-based photopolymerization initiators. These can be used individually or in combination.

[0042] The curable resin composition of this embodiment may contain non-reactive diluents other than the reactive diluent for mixing, dispersion, or viscosity adjustment during manufacturing. Examples of the non-reactive diluent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, tetramethylbenzene, and petroleum naphtha; glycol ethers such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and esterified products of the above glycol ethers; and alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol. These can be used individually or in combination.

[0043] Furthermore, the curable resin composition of this embodiment may also contain, for example, other resins, defoamers, flame retardants, antioxidants, and additives. These components are appropriately included in either liquid A or liquid B.

[0044] The curable resin composition of this embodiment is prepared using known methods. For example, it is prepared by kneading or mixing predetermined amounts of each of the above components at room temperature (e.g., 25°C) using a kneading device such as a three-roll mill, ball mill, and sand mill, or a stirring means such as a super mixer or planetary mixer. Pre-kneading or pre-mixing may also be performed as needed.

[0045] (2) Cured product The cured product of this embodiment is produced by curing the curable resin composition obtained as described above. For example, when the cured product is used as a solder resist layer provided on a printed circuit board, the cured product is produced by the following method.

[0046] First, the curable resin composition is printed onto a printed circuit board on which a predetermined circuit is formed to a desired thickness, thereby forming a printed layer. Known printing methods such as screen printing, spray coating, bar coating, applicator coating, blade coating, knife coating, roll coating, and gravure coating can be used. If the curable resin composition contains a non-reactive diluent, the coating on the printed circuit board is dried in a dryer at 60°C to 80°C for 15 to 60 minutes to form a dried coating. Next, the dried coating film is irradiated with active energy rays (e.g., ultraviolet rays) according to a predetermined pattern to harden the dried coating film in that pattern. Then, the areas of the dried coating film that were not irradiated with active energy rays (unexposed areas) are removed with a dilute alkaline aqueous solution to form a photocured layer on the printed circuit board. Examples of methods for removing the unexposed areas include the spray method and the shower method. Examples of the dilute alkaline aqueous solution include a 0.5 to 5% by mass sodium carbonate aqueous solution. Then, the photocured layer is heated (post-cured) to heat-cur it. This provides the cured material to the printed circuit board. The heating conditions are, for example, a heating temperature of 130 to 170°C and a heating time of 20 to 80 minutes.

[0047] Since the cured product of this embodiment is a cured product of the curable resin composition obtained as described above, it can have a desired pattern, in particular a high-resolution pattern, while containing an inorganic filler containing an alkaline earth metal. Furthermore, the cured product of this embodiment can be expected to have improved adhesion to the bonded material and deep curing properties. Therefore, the cured product of this embodiment can be suitably used as a resist layer for printed circuit boards where high reliability is required.

[0048] (3) Printed circuit board The printed circuit board of this embodiment has a cured product obtained as described above. Therefore, the printed circuit board of this embodiment can be suitably used in applications where high reliability is required. [Examples]

[0049] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples.

[0050] <Preparation of curable resin compositions> The components were mixed and dispersed using a three-roll mixing system according to the composition and formulation shown in Table 1 to obtain Solution A and Solution B, respectively. Unless otherwise specified, the units of the numerical values ​​representing the compositional content in Table 1 are parts by mass.

[0051] [Table 1] *1 Resona Co., Ltd. Acid pendant epoxy acrylate resin 65% by mass, diethylene glycol monoethyl ether acetate 17.5% by mass, petroleum naphtha 17.5% by mass *2 Barium sulfate manufactured by Sakai Chemical Industry Co., Ltd. *3 Talc manufactured by Fuji Talc Industry Co., Ltd. *4 Compounds having an oxime ester bond represented by the following general formula (2) [ka] Methanone (9-ethyl-6-nitro-9H-carbazole-3-yl)[4-(2-methoxy-1-methylethoxy)-2-methylphenyl]-O-acetyloxime *5 Ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), manufactured by BASF Japan Ltd. *6 α-aminoalkylphenone-based photopolymerization initiator manufactured by IGM Resins BV. *7 Blue coloring agent manufactured by Toyo Color Co., Ltd. *8 Triglycidyl isocyanurate manufactured by Nissan Chemical Corporation

[0052] (1) Sensitivity test in the initial stages of preparation For the examples and comparative examples, the prepared solutions A and B were mixed to obtain each curable resin composition. Sensitivity tests were performed on each of the obtained curable resin compositions according to the following procedure. A curable resin composition was printed onto a glass epoxy substrate (FR-4, thickness: 1.6 mm, conductor (Cu foil) thickness: 50 μm) with a buffed surface using a screen printing method to achieve a film thickness of 20 μm to 25 μm after drying. The coating was then formed by drying in a dryer at 80°C for 20 minutes. Next, the coating film was subjected to a sensitivity test using Kodak's 21-step sensitivity measurement step tablet. Specifically, with the sensitivity measurement step tablet in close contact with the coating film, an exposure device (product name: HMW-680GW, manufactured by Oak Manufacturing Co., Ltd.) was used to expose the film to ultraviolet light (wavelength: 300nm~400nm, main peak: 365nm) at an integrated light intensity of 300mJ / cm². 2 The coating film was exposed under the following conditions, and after ultraviolet irradiation, it was developed under the following conditions. • Developer: 1% by mass sodium carbonate aqueous solution • Liquid temperature: 30°C • Spray pressure: 2.0 kg / cm² 2 • Development time: 60 seconds Then, the sensitivity (number of steps on the step tablet) of the portion of the coating film that remained on the glass epoxy substrate after development was checked using the sensitivity measurement step tablet. The results (number of steps on the step tablet) are shown in Table 2. Note that a higher number of steps on the step tablet indicates better light sensitivity, and a number of 3 or less is considered a failure.

[0053] (2) Sensitivity test one month after preparation After storing the prepared solutions A and B at 25°C for one month, they were mixed to obtain each curable resin composition. Then, a sensitivity test was performed on each curable resin composition under the same conditions as the initial sensitivity test described in (1) above, to confirm the sensitivity (number of steps in the step tablet). The results (number of steps in the step tablet) are shown in Table 2. A score of 3 or less was considered a failure.

[0054] (3) Sensitivity test 3 months after preparation After storing the prepared solutions A and B at 25°C for 3 months, they were mixed to obtain each curable resin composition. Sensitivity tests were then performed on each curable resin composition under the same conditions as the initial sensitivity test described in (1) above, to confirm the sensitivity (number of step tablets). The results (number of step tablets) are shown in Table 2. A score of 3 or less was considered a failure.

[0055] [Table 2]

[0056] As described above, each curable resin composition in the examples, while using an inorganic filler containing an alkaline earth metal and a photopolymerization initiator having an oxime ester bond, is less prone to sensitivity degradation over time. Therefore, each curable resin composition in the examples, while containing an inorganic filler containing an alkaline earth metal, can form cured products with desired patterns, particularly fine patterns. Furthermore, since each curable resin composition in the examples is less prone to sensitivity degradation over time, improvements in adhesion and deep curing properties of the cured product to the bonded material can also be expected.

[0057] Furthermore, the results from Examples 4 and 5 show that it is possible to include an inorganic filler (B-1) in a predetermined amount within a specified range in solution B while minimizing the decrease in sensitivity of the curable resin composition over time.

[0058] Furthermore, the cured products formed using each of the curable resin compositions in these examples can be suitably used as resist layers for printed circuit boards where high reliability is required. In other words, each of the curable resin compositions in these examples can provide highly reliable printed circuit boards.

Claims

1. A curable resin composition obtained by mixing liquid A and liquid B, The aforementioned liquid A comprises a carboxyl group-containing resin (A) and an inorganic filler (B), The aforementioned liquid B comprises an epoxy compound (C) and a photopolymerization initiator (D) having an oxime ester bond. The inorganic filler (B) is a curable resin composition comprising an inorganic filler (B-1) containing an alkaline earth metal.

2. The curable resin composition according to claim 1, wherein the photopolymerization initiator (D) having an oxime ester bond comprises a photopolymerization initiator having an oxime ester bond and a nitro group.

3. The curable resin composition according to claim 2, wherein the photopolymerization initiator (D) having an oxime ester bond comprises a compound represented by the following general formula (1). 【Chemistry 1】 (In the above formula (1), R １ represents hydrogen, an alkyl group having 1 to 17 carbon atoms or an alkoxy group having 1 to 17 carbon atoms, and R ２ represents a phenyl group, or an alkyl group having 1 to 5 carbon atoms, -O-C ｍ H ２ｍ -CH ３ and -O-C ｎ H ２ｎ -O-C ｐ H ２ｐ -CH ３ represents a phenyl group substituted with one or more substituents selected from the group consisting of, m represents an integer of 0 or 1 to 5, n represents an integer of 1 to 5, and p represents an integer of 0 or 1 to 5.)

4. The curable resin composition according to any one of claims 1 to 3, wherein the liquid B may contain the inorganic filler (B-1) in a mass ratio of the inorganic filler (B-1) to the photopolymerization initiator (D) having an oxime ester bond in the range of 0:1 to 15:

1.

5. A printed circuit board having a cured product of a curable resin composition according to any one of claims 1 to 3.

6. A printed circuit board having a cured product of the curable resin composition according to claim 4.

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