JP7545447B2 - Photosensitive resin composition, photocured product of photosensitive resin composition, and printed wiring board coated with photosensitive resin composition - Google Patents

Description

The present invention relates to a photosensitive resin composition, in particular a photosensitive resin composition useful as an insulating protective film for circuit boards such as printed wiring boards having a conductor circuit pattern formed on a substrate such as a rigid substrate or a flexible substrate, a photocured product of the photosensitive resin composition, and a printed wiring board having a coating obtained by photocuring the photosensitive resin composition.

Printed wiring boards are used to mount electronic components on the soldering lands of a conductor circuit pattern, and the conductor circuit portion excluding the soldering lands is covered with a solder resist film, which is an insulating protective film. This prevents solder from adhering to unnecessary areas when soldering electronic components to a circuit board such as a printed wiring board, and also prevents the conductor circuit from being directly exposed to air and corroding due to oxidation or humidity.

In addition, the insulating protective film of a printed wiring board may be required to have a matte appearance due to the conditions of use as an insulating protective film, such as imparting a luxurious feel. As a resin composition for forming a solder resist film with a matte appearance, a photocurable/thermosetting matte solder resist ink composition containing (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) an organic filler, (D) a diluent, and (E) an epoxy resin has been proposed (Patent Document 1). In Patent Document 1, an organic filler with a lower hardness than an inorganic filler is blended as a matting agent to prevent the copper, solder, etc. from being scraped off and the solder resist film from becoming dirty when the solder resist film comes into contact with copper, solder, etc., such as when a printed wiring board on which the solder resist film is formed comes into contact with another printed wiring board, etc.

However, when an organic filler is blended as a matting agent as in Patent Document 1, there are cases where the insulating protective film cannot be provided with sufficient heat resistance and insulating reliability. Furthermore, when an inorganic filler such as non-surface-treated silica particles or aluminum silicate particles is blended as a matting agent instead of an organic filler, the heat resistance tends to be improved compared to when an organic filler is blended, but there are still cases where the insulating reliability cannot be provided with sufficient reliability.

For this reason, wax-surface-treated inorganic fillers, such as wax-treated silica particles, in which the surface of inorganic fillers such as silica particles is treated with wax, are sometimes blended as a matting agent. In wax-treated silica particles, the silanol groups (SiOH groups) on the silica particle surface are covered with wax, improving insulation reliability.

However, the insulating reliability of wax-surface-treated inorganic fillers tends to decrease in high-temperature and high-humidity environments, leaving room for improvement in maintaining insulating reliability over the long term.

JP 2006-040935 A

In view of the above circumstances, the present invention aims to provide a photosensitive resin composition capable of producing a photocured product having excellent insulation reliability over a long period of time and a matte appearance, a photocured product of the photosensitive resin composition, and a printed wiring board coated with the photosensitive resin composition.

The gist of the configuration of the present invention is as follows.
[1] A photosensitive resin composition comprising (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) a filler, and (F) a matting agent that has been surface-treated with an organosilicon compound.
[2] The photosensitive resin composition according to [1], wherein the matting agent (F) that has been surface-treated with an organosilicon compound is (F1) silicon dioxide particles that have been surface-treated with an organosilicon compound.
[3] The photosensitive resin composition according to [2], wherein the average particle diameter of the silicon dioxide particles that have been surface-treated with the organosilicon compound (F1) is 1.0 μm or more and 10 μm or less.
[4] The photosensitive resin composition according to any one of [1] to [3], wherein the organosilicon compound is a polydialkylsiloxane.
[5] The photosensitive resin composition according to [4], wherein the number of carbon atoms in the alkyl group of the polydialkylsiloxane is 1 or more and 5 or less.
[6] The photosensitive resin composition according to [4], wherein the polydialkylsiloxane is polydimethylsiloxane.
[7] The photosensitive resin composition according to any one of [1] to [3], further comprising 5.0 parts by mass or more and 100 parts by mass or less of the matting agent (F) that has been surface-treated with an organosilicon compound, per 100 parts by mass of the photosensitive resin (A).
[8] The photosensitive resin composition according to any one of [1] to [3], wherein the (A) photosensitive resin is a polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin having a chemical structure obtained by reacting a radically polymerizable unsaturated monocarboxylic acid with at least a part of the epoxy groups of a multifunctional epoxy resin having two or more epoxy groups in one molecule to obtain a radically polymerizable unsaturated monocarboxylated epoxy resin, and reacting a polybasic acid and/or a polybasic acid anhydride with a hydroxyl group of the radically polymerizable unsaturated monocarboxylated epoxy resin, and the (D) epoxy compound contains the same type of epoxy resin as the multifunctional epoxy resin.
[9] The photosensitive resin composition according to any one of [1] to [3], further comprising a matting agent that has been surface-treated with a hydrophobic organic compound other than an organosilicon compound.
[10] The photosensitive resin composition according to any one of [1] to [3], further comprising an inorganic ion exchanger.
[11] The photosensitive resin composition according to any one of [1] to [3], which is used for a solder resist of a printed wiring board.
[12] A photocured product of the photosensitive resin composition according to any one of [1] to [3].
[13] A printed wiring board coated with the photosensitive resin composition according to any one of [1] to [3].

In the present invention, "average particle size" refers to the particle size at a cumulative volume percentage of 50 volume% (D50), measured with a particle size distribution analyzer using a laser diffraction/scattering method.

According to an embodiment of the photosensitive resin composition of the present invention, by containing (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) a filler, and (F) a matting agent that has been surface-treated with an organosilicon compound, it is possible to obtain a photocured product that has excellent insulation reliability over a long period of time and has a matte appearance.

According to an embodiment of the photosensitive resin composition of the present invention, the matting agent (F) that has been surface-treated with an organosilicon compound is (F1) silicon dioxide particles that have been surface-treated with an organosilicon compound, i.e., silica particles that have been surface-treated with an organosilicon compound, so that a photocured product with a matte appearance and excellent insulation reliability over a long period of time can be obtained more reliably.

According to an embodiment of the photosensitive resin composition of the present invention, the average particle size of the silicon dioxide particles that have been surface-treated with the (F1) organosilicon compound is 1.0 μm or more and 10 μm or less, so that a photocured product can be obtained that has excellent insulation reliability over a long period of time and excellent pattern formability while more reliably imparting a matte appearance.

According to an embodiment of the photosensitive resin composition of the present invention, the organosilicon compound is a polydialkylsiloxane, so that a photocured product having excellent insulation reliability over a long period of time and a matte appearance can be obtained more reliably.

According to an embodiment of the photosensitive resin composition of the present invention, the alkyl group of the polydialkylsiloxane has 1 to 5 carbon atoms, which more reliably improves the insulation reliability and matte appearance over a long period of time.

According to an embodiment of the photosensitive resin composition of the present invention, the (F) matting agent that has been surface-treated with an organosilicon compound is contained in an amount of 5.0 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the (A) photosensitive resin, thereby more reliably imparting a matte appearance while further improving insulation reliability and coatability over a long period of time.

According to an embodiment of the photosensitive resin composition of the present invention, the photosensitive resin (A) is a polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin having a chemical structure obtained by reacting a radically polymerizable unsaturated monocarboxylated epoxy resin with at least a part of the epoxy groups of a multifunctional epoxy resin having two or more epoxy groups in one molecule, and reacting a polybasic acid and/or a polybasic acid anhydride with the hydroxyl groups of the radically polymerizable unsaturated monocarboxylated epoxy resin, and the epoxy compound (D) contains the same type of epoxy resin as the multifunctional epoxy resin, thereby contributing to improved insulation reliability over a long period of time and also contributing to improved heat resistance of the photocured product.

Next, the photosensitive resin composition of the present invention will be described below. The photosensitive resin composition of the present invention contains (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) a filler, and (F) a matting agent that has been surface-treated with an organosilicon compound. With the photosensitive resin composition of the present invention, it is possible to obtain a photocured product that has excellent insulation reliability over a long period of time and has a matte appearance.

Examples of photosensitive resins include carboxyl group-containing photosensitive resins. The chemical structure of the carboxyl group-containing photosensitive resin is not particularly limited, and examples include resins having free carboxyl groups and photosensitive unsaturated double bonds. Examples of carboxyl group-containing photosensitive resins include polybasic acid-modified radically polymerizable unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid (hereinafter sometimes referred to as "(meth)acrylic acid") reacted with at least a portion of the epoxy groups of a multifunctional epoxy resin having two or more epoxy groups in one molecule to obtain radically polymerizable unsaturated monocarboxylated epoxy resins such as epoxy acrylate and epoxy methacrylate (hereinafter acrylate and methacrylate are sometimes referred to as "(meth)acrylate"), and the hydroxyl groups generated in the radically polymerizable unsaturated monocarboxylated epoxy resin are reacted with polybasic acids and/or polybasic acid anhydrides to obtain polybasic acid-modified epoxy (meth)acrylate and other polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resins having a chemical structure obtained by reacting the hydroxyl groups generated in the radically polymerizable unsaturated monocarboxylated epoxy resins.

The chemical structure of the multifunctional epoxy resin is not particularly limited as long as it is a bifunctional or higher epoxy resin having two or more epoxy groups in one molecule. The epoxy equivalent of the multifunctional epoxy resin is not particularly limited, and for example, the upper limit of the epoxy equivalent is preferably 2000, more preferably 1500, even more preferably 1000, and particularly preferably 500. On the other hand, the lower limit of the epoxy equivalent of the multifunctional epoxy resin is preferably 100, and particularly preferably 200. Examples of the types of polyfunctional epoxy resins include rubber-modified epoxy resins such as biphenyl-type epoxy resins, biphenylaralkyl-type epoxy resins, naphthalene-type epoxy resins, dicyclopentadiene-type epoxy resins, and silicone-modified epoxy resins, ε-caprolactone-modified epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins such as o-cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, cyclic aliphatic epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, heterocyclic epoxy resins, bisphenol-modified novolac-type epoxy resins, polyfunctional modified novolac-type epoxy resins, and condensation-type epoxy resins of phenols and aromatic aldehydes having phenolic hydroxyl groups. In addition, epoxy resins in which halogen atoms such as Br and Cl have been introduced into these epoxy resins may be used. These polyfunctional epoxy resins may be used alone or in combination of two or more.

The radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and examples thereof include (meth)acrylic acid, furfurylacrylic acid, crotonic acid, cinnamic acid, tiglic acid, angelic acid, and the like. Of these, (meth)acrylic acid is preferred because of its excellent photosensitivity and reactivity, and ease of handling. These radically polymerizable unsaturated monocarboxylic acids may be used alone or in combination of two or more. The carboxyl group of the radically polymerizable unsaturated monocarboxylic acid reacts with the epoxy group of the multifunctional epoxy resin to form an ester bond, thereby introducing a photosensitive unsaturated double bond into the epoxy resin and imparting photosensitivity to the epoxy resin.

The method for reacting the polyfunctional epoxy resin with the radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and an example of the method is to heat the polyfunctional epoxy resin and the radically polymerizable unsaturated monocarboxylic acid in an appropriate dispersion medium (e.g., an inert organic solvent) while stirring them.

By the reaction of a polyfunctional epoxy resin with a radically polymerizable unsaturated monocarboxylic acid, a hydroxyl group is generated in the radically polymerizable unsaturated monocarboxylated epoxy resin, and the generated hydroxyl group is reacted with a polybasic acid and/or a polybasic acid anhydride to further introduce a free carboxyl group into the resin having a photosensitive unsaturated double bond introduced. By introducing a free carboxyl group into the resin having a photosensitive unsaturated double bond introduced, the resin having a photosensitive unsaturated double bond introduced is given alkaline developability. The polybasic acid is not particularly limited as long as it is a carboxylic acid having two or more functionalities, and may be a saturated polybasic acid or an unsaturated polybasic acid. Examples of polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, itaconic acid, citraconic acid, phthalic acid, phthalic acid derivatives (e.g., 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, etc.), bifunctional carboxylic acids such as diglycolic acid, trifunctional carboxylic acids such as trimellitic acid, and tetrafunctional carboxylic acids such as pyromellitic acid. The polybasic acid anhydride is not particularly limited, and examples thereof include anhydrides of the above-mentioned polybasic acids. These compounds may be used alone or in combination of two or more.

The method for reacting the radically polymerizable unsaturated monocarboxylated epoxy resin with the polybasic acid and/or polybasic acid anhydride is not particularly limited, and examples include a method in which the radically polymerizable unsaturated monocarboxylated epoxy resin and the polybasic acid and/or polybasic acid anhydride are heated while being stirred in a suitable dispersion medium (e.g., an inert organic solvent).

The above-mentioned polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin can also be used as a photosensitive resin, but if necessary, a carboxyl group-containing photosensitive resin having a chemical structure in which a compound having one or more radically polymerizable unsaturated groups and an epoxy group (e.g., a glycidyl compound) is further reacted with a part of the carboxyl groups of the above-mentioned polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin may be used. In the carboxyl group-containing photosensitive resin in which a compound having a radically polymerizable unsaturated group and an epoxy group is further reacted, the photopolymerization reactivity, i.e., the photosensitive properties, are further improved compared to the polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin by having a chemical structure in which a radically polymerizable unsaturated group is further introduced into the side chain.

Examples of compounds having one or more radically polymerizable unsaturated groups and an epoxy group include glycidyl (meth)acrylate, allyl glycidyl ether, pentaerythritol tri(meth)acrylate monoglycidyl ether, etc. The above-mentioned compounds having one or more radically polymerizable unsaturated groups and an epoxy group may be used alone or in combination of two or more kinds.

In addition, when the photosensitive resin composition is not subjected to an alkali development treatment, a photosensitive resin having no carboxyl group may be used. Examples of photosensitive resins having no carboxyl group include polymers of monomers consisting of esters of the above-mentioned radically polymerizable unsaturated monocarboxylic acids such as (meth)acrylate, copolymers consisting of esters of radically polymerizable unsaturated monocarboxylic acids such as (meth)acrylate and other polymerizable monomers, resins in which at least a part of the epoxy groups of a copolymer of an ester of a radically polymerizable unsaturated monocarboxylic acid such as (meth)acrylic acid and a compound having one or more radically polymerizable unsaturated groups and an epoxy group is reacted with a radically polymerizable unsaturated monocarboxylic acid such as (meth)acrylic acid, and radically polymerizable unsaturated monocarboxylic acid such as (meth)acrylic acid. Examples of such resins include a resin obtained by reacting a compound having one or more radically polymerizable unsaturated groups and an epoxy group with at least a portion of the carboxyl groups of a polymer of acrylic acid or at least a portion of the carboxyl groups of a copolymer obtained by reacting a radically polymerizable unsaturated monocarboxylic acid such as (meth)acrylic acid with an ester of a radically polymerizable unsaturated monocarboxylic acid such as (meth)acrylic acid; a radically polymerizable unsaturated monocarboxylated epoxy resin such as epoxy (meth)acrylate, which can be obtained by reacting an epoxy resin with a radically polymerizable unsaturated monocarboxylic acid such as (meth)acrylic acid; and a urethane (meth)acrylate.

The above-mentioned photosensitive resin without a carboxyl group can be prepared using the same radically polymerizable unsaturated monocarboxylic acid and compound having one or more radically polymerizable unsaturated groups and an epoxy group as those used in the preparation of the carboxyl group-containing photosensitive resin.

Examples of radically polymerizable unsaturated monocarboxylated epoxy resins such as epoxy (meth)acrylate include radically polymerizable unsaturated monocarboxylated epoxy resins such as epoxy (meth)acrylate obtained in the process of preparing the carboxyl group-containing photosensitive resin described above.

Examples of the urethane (meth)acrylate include (i) urethane (meth)acrylate obtained by reacting urethane resin with (meth)acrylic acid. The urethane resin is a resin obtained by reacting a compound having two or more isocyanate groups in one molecule with a polyol compound having two or more hydroxyl groups in one molecule. Examples of the urethane (meth)acrylate include (ii) urethane (meth)acrylate obtained by reacting at least a part of the epoxy group of an epoxy resin having one or more epoxy groups in one molecule with (meth)acrylic acid to obtain an epoxy (meth)acrylate, and then adding a compound having one or more isocyanate groups in one molecule to the generated hydroxyl group, and (iii) urethane (meth)acrylate obtained by adding a polyisocyanate having two or more isocyanate groups in one molecule to the hydroxyl group generated in the epoxy (meth)acrylate, and then adding a hydroxyl group of a polyol to the isocyanate group of the added polyisocyanate.

When the photosensitive resin is a carboxyl group-containing photosensitive resin, the acid value of the photosensitive resin is not particularly limited, and for example, the lower limit of the acid value is preferably 30 mgKOH/g from the viewpoint of reliably imparting alkaline developability, and particularly preferably 40 mgKOH/g. On the other hand, the upper limit of the acid value of the photosensitive resin is preferably 200 mgKOH/g from the viewpoint of preventing dissolution of the exposed portion by an alkaline developer, and particularly preferably 150 mgKOH/g from the viewpoint of reliably preventing a decrease in the moisture resistance and insulation reliability of the photocured product.

The mass average molecular weight (Mw) of the photosensitive resin is not particularly limited. For example, the lower limit of the mass average molecular weight (Mw) is preferably 6,000, more preferably 7,000, and particularly preferably 8,000, from the viewpoint of improving the toughness of the photocured product and the dryness to touch before the exposure treatment. On the other hand, the upper limit of the mass average molecular weight (Mw) of the photosensitive resin is preferably 200,000, more preferably 100,000, and particularly preferably 50,000, from the viewpoint of reliably preventing a decrease in alkaline developability. The mass average molecular weight (Mw) means the molecular weight measured by gel permeation chromatography (GPC).

The photosensitive resin may be prepared by the above reaction using the above starting materials, or a commercially available photosensitive resin may be used. Examples of commercially available photosensitive resins include carboxyl group-containing photosensitive resins such as "Lipoxy SP-4621" (Showa Denko K.K.), "KAYARAD ZAR-2000", "KAYARAD ZFR-1122", "KAYARAD FLX-2089", and "KAYARAD ZCR-1569H" (all Nippon Kayaku Co., Ltd.), and "Cyclomer P (ACA) Z-250" (Daicel Corporation). These photosensitive resins may be used alone or in combination of two or more.

(B) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is a commonly used one. For example, α-aminoalkylphenone photopolymerization initiators such as 2-benzyl-2-(N,N-dimethylamino)-1-(4-morpholinophenyl)butan-1-one and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone 1-[9-ethyl-6-(2-methylbenzyl)oxime], 1-[4-methylbenzyl] ... Examples of the oxime ester photopolymerization initiator include (Z)-(9-ethyl-6-nitro-9H-carbazol-3-yl)(4-((1-methoxypropan-2-yl)oxy)-2-methylphenyl)methanone O-acetyloxime. The photopolymerization initiator may be other photopolymerization initiators than the α-aminoalkylphenone-based photopolymerization initiators and the oxime ester-based photopolymerization initiators. Examples of other photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 4-(2-hydroxyethoxy) Examples of the photopolymerization initiator include phenyl-2-(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, and p-dimethylaminobenzoic acid ethyl ester. These photopolymerization initiators may be used alone or in combination of two or more.

The amount of photopolymerization initiator is not particularly limited, but is preferably 1.0 parts by mass or more and 20 parts by mass or less, and more preferably 2.0 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of photosensitive resin.

(C) Reactive Diluent The reactive diluent is, for example, a photopolymerizable monomer, a compound having at least one polymerizable double bond per molecule, preferably at least two polymerizable double bonds per molecule. The reactive diluent is blended in order to provide the photocured product with mechanical strength by sufficiently photocuring the photosensitive resin composition, and to obtain a photocured product excellent in acid resistance, alkali resistance, chemical resistance, etc.

Examples of reactive diluents include (meth)acrylate monomers. Examples of (meth)acrylate monomers include monofunctional (meth)acrylate monomers, bifunctional (meth)acrylate monomers, and trifunctional or higher (meth)acrylate monomers. Specific examples of such monomers include monofunctional (meth)acrylate monomers such as 2-hydroxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)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, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, and allylated cyclohexyl di(meth)acrylate. and isocyanurate di(meth)acrylate; trifunctional (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, and tris(acryloxyethyl)isocyanurate; tetrafunctional (meth)acrylate monomers such as ditrimethylolpropane tetra(meth)acrylate; pentafunctional (meth)acrylate monomers such as propionic acid-modified dipentaerythritol penta(meth)acrylate; and hexafunctional (meth)acrylate monomers such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate. In addition, examples of (meth)acrylate monomers include (meth)acrylates of other caprolactone-modified dipentaerythritol. These photopolymerizable monomers may be used alone or in combination of two or more.

The amount of reactive diluent is not particularly limited, but is preferably 5.0 parts by weight or more and 100 parts by weight or less, and more preferably 10 parts by weight or more and 40 parts by weight or less, per 100 parts by weight of photosensitive resin.

(D) Epoxy Compounds Epoxy compounds are components for increasing the crosslink density of the photocured product to obtain a photocured product with sufficient strength. Examples of epoxy compounds include epoxy resins. Examples of epoxy resins include rubber-modified epoxy resins such as biphenyl-type epoxy resins, biphenylaralkyl-type epoxy resins, naphthalene-type epoxy resins, dicyclopentadiene-type epoxy resins, and silicone-modified epoxy resins, ε-caprolactone-modified epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, phenol novolac-type epoxy resins, and cresol novolac-type epoxy resins such as o-cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, cyclic aliphatic epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, heterocyclic epoxy resins, bisphenol-modified novolac-type epoxy resins, polyfunctionally modified novolac-type epoxy resins, and condensation-type epoxy resins of phenols and aromatic aldehydes having a phenolic hydroxyl group. These epoxy compounds may be used alone or in combination of two or more kinds.

When using a polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin as the photosensitive resin contained in the photosensitive resin composition among these epoxy resins, it is preferable to use an epoxy resin of the same type as the polyfunctional epoxy resin that forms the skeleton of the polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin as the epoxy compound, since this contributes to improving the insulation reliability over a long period of time and also contributes to improving the heat resistance of the photocured product.

The amount of epoxy compound is not particularly limited, but for example, in order to obtain a cured coating film with sufficient strength, it is preferably 5.0 parts by mass or more and 100 parts by mass or less, and particularly preferably 15 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of photosensitive resin.

(E) Filler By including a filler, the mechanical strength of the photocured product is improved, and the solder heat resistance required as a basic property of the insulating protective film for printed wiring boards is improved. Examples of the filler include inorganic fillers and organic fillers.

Examples of inorganic fillers include talc, barium sulfate, alumina, aluminum hydroxide, mica, calcium carbonate, clay, etc. Examples of organic fillers include urethane-based beads, polymethyl methacrylate-based beads, polybutyl methacrylate-based beads, acrylic-based beads, acrylic copolymer-based beads, polyacrylic acid ester-based beads, nylon-based beads, silicone-based beads, polyethylene-based beads, polypropylene-based beads, polystyrene-based beads, polycarbonate-based beads, polyimide-based beads, polyamide-based beads, polyester-based beads, polyvinyl chloride-based beads, polyvinylidene chloride-based beads, fluororesin-based beads, urea resin-based beads, melamine resin-based beads, phenolic resin-based beads, etc. Among these fillers, inorganic fillers are preferred because they reliably improve solder heat resistance.

The filler is a particulate component. The average particle size of the filler is not particularly limited, but is preferably 0.5 μm or more and 50 μm or less, and particularly preferably 1.0 μm or more and 20 μm or less, in order to reliably improve the mechanical strength of the photocured product while providing excellent dispersibility in the photosensitive resin composition.

The shape of the filler is not particularly limited, and examples include spherical, needle-like, plate-like, etc.

The amount of filler to be blended is not particularly limited, and the lower limit is preferably 2.0 parts by mass, and more preferably 4.0 parts by mass, per 100 parts by mass of photosensitive resin, in order to ensure that the amount of filler contributes to improving the mechanical strength of the photocured product. On the other hand, the upper limit of the amount of filler to be blended is preferably 30 parts by mass, and more preferably 15 parts by mass, per 100 parts by mass of photosensitive resin, in order to ensure that the photosensitive resin composition has excellent coatability.

(F) Matting agent surface-treated with an organosilicon compound In the photosensitive resin composition of the present invention, a matting agent surface-treated with an organosilicon compound is blended, so that a photocured product having excellent insulation reliability over a long period of time and a matte appearance can be obtained. As the matting agent surface-treated with an organosilicon compound, (F1) silicon dioxide particles surface-treated with an organosilicon compound, that is, silica particles surface-treated with an organosilicon compound, are preferred, since they can more reliably obtain a photocured product having excellent insulation reliability over a long period of time and a matte appearance. The (F1) component is silicon dioxide particles hydrophobized with an organosilicon compound.

(F1) Silicon dioxide particles surface-treated with an organosilicon compound The average particle size of silicon dioxide particles surface-treated with an organosilicon compound (hereinafter, simply referred to as "organosilicon compound-treated silicon dioxide particles") is not particularly limited, but the lower limit is preferably 1.0 μm, more preferably 2.0 μm, and particularly preferably 2.5 μm, from the viewpoint of more reliably imparting a matte appearance. On the other hand, the upper limit of the average particle size of the organosilicon compound-treated silicon dioxide particles is preferably 10 μm, from the viewpoint of obtaining a photocured product having excellent insulation reliability over a long period of time and excellent pattern formability, and is more preferably 8.0 μm, and particularly preferably 7.0 μm, from the viewpoint of reliably preventing the decrease in adhesion of the organosilicon compound-treated silicon dioxide particles to the substrate, etc. in the photocured product. The average particle size of the organosilicon compound-treated silicon dioxide particles is the average particle size measured in the form of organosilicon compound-treated silicon dioxide particles, and therefore is the average particle size including the organosilicon compound that coats at least a portion of the surface of the silicon dioxide particles.

The organosilicon compound used in the surface treatment of silicon dioxide particles is not particularly limited, but polydialkylsiloxane is preferred, for example, because it can more reliably obtain a photocured product having excellent insulation reliability over a long period of time and a matte appearance. The number of carbon atoms in the alkyl group in the dialkylsiloxane unit constituting the polydialkylsiloxane is not particularly limited, but is preferably in the range of 1 to 5, more preferably 1 to 3, in order to more reliably improve insulation reliability and matte appearance over a long period of time, and as the dialkylsiloxane unit, dimethylsiloxane unit, i.e., polydimethylsiloxane, is particularly preferred.

The amount of the matting agent that has been surface-treated with an organosilicon compound, such as organosilicon compound-treated silicon dioxide particles, is not particularly limited, but the lower limit is preferably 5.0 parts by mass, more preferably 20 parts by mass, per 100 parts by mass of photosensitive resin, in order to more reliably impart a matte appearance, and more preferably 30 parts by mass, and particularly preferably 40 parts by mass, in order to further improve the matte appearance. On the other hand, the upper limit of the amount of the matting agent that has been surface-treated with an organosilicon compound, per 100 parts by mass of photosensitive resin, is preferably 100 parts by mass, in order to further improve insulation reliability and coatability over a long period of time, and more preferably 80 parts by mass, and particularly preferably 60 parts by mass, in order to reliably prevent a decrease in developability and adhesion of the organosilicon compound-treated silicon dioxide particles to the base, such as a substrate.

In addition to the above-mentioned components (A) to (F), the photosensitive resin composition of the present invention may contain various other components as necessary, such as matting agents that have been surface-treated with hydrophobic organic compounds other than organosilicon compounds, inorganic ion exchangers, colorants, various additives, and non-reactive diluents.

Matting agent surface-treated with a hydrophobic organic compound other than an organosilicon compound In the photosensitive resin composition of the present invention, as the surface-treated matting agent, a matting agent surface-treated with a hydrophobic organic compound other than an organosilicon compound may be used in combination with the matting agent surface-treated with an organosilicon compound, which is the component (F). Examples of the matting agent surface-treated with a hydrophobic organic compound other than an organosilicon compound include silicon dioxide particles surface-treated with a hydrophobic organic compound other than an organosilicon compound (hereinafter, sometimes referred to as "other surface-treated silicon dioxide particles").

The average particle size of the other surface-treated silicon dioxide particles is not particularly limited, but the lower limit is preferably 1.0 μm, more preferably 2.0 μm, and particularly preferably 2.5 μm, in order to more reliably impart a matte appearance. On the other hand, the upper limit of the average particle size of the other surface-treated silicon dioxide particles is preferably 10 μm, more preferably 8.0 μm, and particularly preferably 7.0 μm, in order to reliably prevent a decrease in the adhesion of the other surface-treated silicon dioxide particles to the base such as a substrate. The average particle size of the other surface-treated silicon dioxide particles is the average particle size measured in the form of the other surface-treated silicon dioxide particles, and therefore is the average particle size including the hydrophobic organic compound that covers at least a portion of the surface of the silicon dioxide particles.

The hydrophobic organic compound used in the other surface-treated silicon dioxide particles is not particularly limited as long as it is a hydrophobic organic compound other than an organosilicon compound, and examples thereof include wax. That is, examples of other surface-treated silicon dioxide particles include silicon dioxide particles that have been surface-treated with wax. Examples of silicon dioxide particles that have been surface-treated with wax include silicon dioxide particles that have been surface-treated with polyethylene wax and silicon dioxide particles that have been surface-treated with paraffin wax. Of these, silicon dioxide particles that have been surface-treated with paraffin wax are preferred because they contribute to further improving insulation reliability.

The amount of the matting agent that has been surface-treated with a hydrophobic organic compound other than an organosilicon compound is not particularly limited, but the lower limit is preferably 1.0 part by mass, and more preferably 10 parts by mass, per 100 parts by mass of photosensitive resin, in order to impart a matte appearance. On the other hand, the upper limit of the amount of the matting agent that has been surface-treated with a hydrophobic organic compound other than an organosilicon compound is preferably 40 parts by mass, and more preferably 30 parts by mass, in order to prevent deterioration of insulation reliability and coatability over a long period of time, per 100 parts by mass of photosensitive resin.

Inorganic ion exchangers Inorganic ion exchangers are ion trapping agents, and in combination with matting agents that have been surface-treated with organosilicon compounds and matting agents that have been surface-treated with hydrophobic organic compounds other than organosilicon compounds, they contribute to obtaining a cured product with excellent insulation reliability.

The inorganic ion exchanger may be at least one selected from the group consisting of cation exchangers (cation exchange type), anion exchangers (anion exchange type), and amphoteric ion exchangers (amphoteric ion exchange type).

The inorganic ion exchanger captures and fixes ionic impurities such as sodium ions and chloride ions remaining in the photosensitive resin composition of the present invention by taking in ions of the opposite charge and performing ion exchange, and also captures and fixes metal ions that become ions and move when a voltage is applied. The inorganic ion exchanger captures and fixes ionic impurities and metal ions, thereby contributing to improved insulation reliability. In addition, when the photosensitive resin composition is applied to a substrate and the coating film of the photosensitive resin composition is developed with an alkaline solution such as sodium carbonate, the carboxyl group (-COOH) of the photosensitive resin, which is the base resin, becomes a sodium salt (-COONa). On the other hand, it is believed that the inorganic ion exchanger captures the sodium ions applied to the coating film of the photosensitive resin composition in the development process, thereby suppressing the carboxyl group (-COOH) from becoming a sodium salt (-COONa). It is believed that suppressing the carboxyl group (-COOH) from becoming a sodium salt (-COONa) contributes to preventing a decrease in adhesion of the coating film of the photosensitive resin composition to the substrate.

Examples of inorganic ion exchangers include Zr (zirconium), Sb (antimony), Bi (bismuth), Zr-Al (zirconium-aluminum), Sb-Bi (antimony-bismuth), Mg-Al (magnesium-aluminum), Zr-Bi (zirconium-bismuth), and Zr-Mg-Al (zirconium-magnesium-aluminum). Among these, zirconia compounds, mixtures of aluminum compounds and zirconia compounds, bismuth compounds, and mixtures of bismuth compounds and zirconia compounds are preferred in terms of more reliable and excellent insulation reliability, and Bi (bismuth) and Zr-Bi (zirconium-bismuth) are particularly preferred in terms of further improving insulation reliability. These inorganic ion exchangers may be used alone or in combination of two or more.

Examples of inorganic ion exchangers include cation exchangers such as "IXE-100" and "IXE-300" from Toagosei Co., Ltd., anion exchangers such as "IXE-500", "IXE-530", "IXE-550", "IXE-700F", "IXE-770D", and "IXE-800" from Toagosei Co., Ltd., and both ion exchangers such as "IXE-600", "IXE-633", "IXE-6107", "IXE-6136", "IXEPLAS-A1", "IXEPLAS-A2", and "IXEPLAS-B1" from Toagosei Co., Ltd. These inorganic ion exchangers may be used alone or in combination of two or more kinds.

The amount of inorganic ion exchanger is not particularly limited, but the lower limit is preferably 0.5 parts by mass, more preferably 1.0 parts by mass, and particularly preferably 1.5 parts by mass, per 100 parts by mass of photosensitive resin, in order to ensure that the inorganic ion exchanger contributes to improving insulation reliability. On the other hand, the upper limit of the amount of inorganic ion exchanger is preferably 10 parts by mass, in order to ensure that excellent coating hardness is obtained, and more preferably 5.0 parts by mass, and particularly preferably 3.0 parts by mass, in order to ensure that the adhesion to the substrate is improved.

Colorants The colorants are not particularly limited to pigments, dyes, dyes, etc., and any colorants can be used depending on the desired color, such as white colorants, blue colorants, green colorants, yellow colorants, purple colorants, black colorants, red colorants, orange colorants, etc. Examples of the colorants include inorganic colorants such as titanium dioxide as a white colorant, acetylene black as a black colorant, carbon black, etc., phthalocyanine colorants such as phthalocyanine green and lyonol green as green colorants, phthalocyanine blue and lyonol blue as blue colorants, diketopyrrolopyrrole colorants such as chromophthalic orange as an orange colorant, and organic colorants such as anthraquinone colorants. These colorants may be used alone or in combination of two or more.

Various Additives Examples of the various additives include a curing accelerator, an antifoaming agent, a coupling agent, and a flame retardant.

Examples of curing accelerators include boron trifluoride-amine complex, dicyandiamide (DICY) and its derivatives, organic acid hydrazides, diaminomaleonitrile (DAMN) and its derivatives, guanamine and its derivatives, melamine and its derivatives, aminimides (AI), polyamines, metal salts of acetylacetone such as Zn acetylacetonate and Cr acetylacetonate, enamines, tin octylate, quaternary sulfonium salts, triphenylphosphine, imidazoles such as mercaptobenzimidazole, mercaptobenzoxazole, imidazolium salts, and triethanolamine borate.

Examples of defoaming agents include silicone-based, hydrocarbon-based, and acrylic-based agents. Examples of coupling agents include silane-based, titanate-based, and alumina-based agents. Examples of flame retardants include phosphorus-based flame retardants such as organic phosphates. By incorporating a flame retardant into the photosensitive resin composition, it is possible to prevent combustion of the insulating protective film even if the amount of heat generated by electronic components mounted on printed wiring boards and the like increases, thereby improving safety.

Non-reactive diluent The non-reactive diluent is a component for adjusting the drying property, coatability, etc. of the photosensitive resin composition. Examples of the non-reactive diluent include organic solvents. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, diethylene 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 esters of the above glycol ethers; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol, and petroleum naphtha. These non-reactive diluents may be used alone or in combination of two or more kinds.

2. Method for Producing Photosensitive Resin Composition The method for producing the photosensitive resin composition of the present invention is not limited to a specific method, and the composition can be produced by a commonly used kneading or mixing means. Specifically, for example, the above-mentioned components are mixed in a predetermined ratio, and then kneaded or mixed at room temperature (for example, 10°C to 30°C) by a mixing or kneading means such as a triple roll, a ball mill, a sand mill, a bead mill, or a kneader, or a stirring or mixing means such as a super mixer, a planetary mixer, or a trimix, to produce the photosensitive resin composition of the present invention. Furthermore, prior to kneading or mixing, pre-kneading or pre-mixing may be performed as necessary.

Next, an example of a method for using the photosensitive resin composition of the present invention will be described. Here, an example of a method for forming an insulating protective film such as a solder resist film on a printed wiring board by applying the photosensitive resin composition of the present invention onto the printed wiring board will be described. In this case, the photosensitive resin composition of the present invention is for use as a solder resist for the printed wiring board.

The photosensitive resin composition of the present invention is applied to a printed wiring board in a desired thickness (for example, 5 μm to 100 μm). Any known method can be used as the coating means, such as screen printing, bar coater, spray coating, applicator, blade coater, knife coater, roll coater, gravure coater, etc. After coating of the photosensitive resin composition, if necessary, the photosensitive resin composition is pre-dried with a heating device (for example, a hot air oven, a far-infrared oven, etc.) to volatilize the non-reactive diluent from the photosensitive resin composition and make the surface of the coating film tack-free. Pre-drying conditions include, for example, a drying temperature of 60°C to 90°C and a drying time of 10 minutes to 60 minutes. After the preliminary drying, a negative film (photomask) having a pattern in which the areas other than the lands of the circuit pattern are made light-transmitting is attached to the coating film of the photosensitive resin composition, and a predetermined amount of ultraviolet light (for example, wavelengths in the range of 300 nm to 400 nm) is irradiated from above the negative film to photocure the coating film of the photosensitive resin composition to form a photocured product. Next, the coating film is developed by removing the non-exposed areas corresponding to the lands of the circuit pattern with a dilute alkaline aqueous solution. Examples of the developing method include a spray method and a shower method. Examples of the dilute alkaline aqueous solution include a 0.5% to 5% by weight aqueous sodium carbonate solution. Next, the developed coating film is subjected to a heat curing treatment (post cure) at 130°C to 170°C for 20 to 80 minutes in a heating device (for example, a hot air circulation dryer, etc.), thereby forming an insulating protective film (solder resist film) having a desired pattern on the printed wiring board.

Next, examples of the present invention will be described, but the present invention is not limited to these examples as long as they do not deviate from the spirit of the invention.

Examples 1 to 12, Comparative Examples 1 to 5
The components shown in Table 1 below were blended in the blending ratios shown in Table 1 below, and mixed and dispersed at room temperature using a three-roll mill to prepare photosensitive resin compositions used in Examples 1 to 12 and Comparative Examples 1 to 5. The prepared photosensitive resin compositions were then coated as follows to prepare test samples. The blend amounts in Table 1 below indicate parts by mass unless otherwise specified. Additionally, blank spaces in Table 1 below mean no blending.

Details of each component in Table 1 are as follows.
(A) Photosensitive Resin Lipoxy SP-4621: A polybasic acid-modified cresol novolac epoxy acrylate having a chemical structure obtained by reacting acrylic acid with at least a portion of the epoxy groups of a cresol novolac epoxy resin to obtain an epoxy acrylate, and then reacting the resulting hydroxyl groups with a polybasic acid. Solid content 65% by mass, diethylene glycol monoethyl ether acetate 17.5% by mass, petroleum naphtha 17.5% by mass, Showa Denko K.K.

(B) Photopolymerization initiator Omnirad 369: α-aminoalkylphenone photopolymerization initiator, IGM Resins B.V.

(C) Reactive diluent DPHA: Toagosei Co., Ltd.

(D) Epoxy compound EPICRON N-695: DIC Corporation.
・YX-4000HK: Mitsubishi Chemical Corporation.

(E) Filler: Barium sulfate B-30: Sakai Chemical Industry Co., Ltd.

(F) Matting agent surface-treated with an organosilicon compound - Silophobic 100: silicon dioxide particles surface-treated with polydimethylsiloxane (dimethylsiloxane-treated silicon dioxide), average particle size 2.7 μm, Fuji Silysia Chemical Ltd.
- Silophobic 200: silicon dioxide particles surface-treated with polydimethylsiloxane (dimethylsiloxane-treated silicon dioxide), average particle size 3.9 μm, Fuji Silysia Chemical Ltd.
- Silophobic 704: Silicon dioxide particles surface-treated with polydimethylsiloxane (dimethylsiloxane-treated silicon dioxide), average particle size 6.2 μm, Fuji Silysia Chemical Ltd.

Matting agents that have been surface-treated with hydrophobic organic compounds other than organosilicon compounds: ACEMATT OK-412: silicon dioxide particles surface-treated with polyethylene wax (polyethylene wax-treated silicon dioxide), average particle size 6.3 μm, Evonik Industries.
ACEMATT OK-607: Silicon dioxide particles surface-treated with polyethylene wax (polyethylene wax-treated silicon dioxide), average particle size 4.4 μm, Evonik Industries.
- Silica 436: Silicon dioxide particles surface-treated with paraffin wax (paraffin wax-treated silicon dioxide), average particle size 4.1 μm, Fuji Silysia Chemical Ltd.

Non-surface-treated matting agent - Silica 350: untreated silicon dioxide particles, average particle size 4.0 μm, Fuji Silysia Chemical Ltd.

Colorant - Lionol Blue FG-7351: Blue colorant, Toyo Ink Mfg. Co., Ltd.
MA14: Black colorant, Mitsubishi Chemical Corporation.
Various additives/melamine: Nissan Chemical Industries, Ltd.
-DICY-7: Japan Epoxy Resin Co., Ltd.
-2MBO: Tokyo Chemical Industry Co., Ltd.
Non-reactive diluent EDGAC: Sanyo Chemical Industries, Ltd.

Inorganic ion exchanger IXE-550: Bi-based anion exchanger (hydrated bismuth nitrate, total exchange capacity Cl ⁻ 4.1 meq/g), Toagosei Co., Ltd.
IXE-530: Bi-based anion exchanger (hydrated bismuth nitrate, total exchange capacity Cl ⁻ 3.7 meq/g), Toagosei Co., Ltd.
IXE-500: Bi-based anion exchanger (hydrated bismuth nitrate, total exchange capacity Cl ⁻ 3.9 meq/g), Toagosei Co., Ltd.
IXEPLAS-B1: Zr-Bi based amphoteric ion exchanger, Toagosei Co., Ltd.

Test sample preparation process Substrate: Printed wiring board (glass epoxy board "FR-4", board thickness 1.6 mm, conductor (Cu foil) thickness 50 μm)
Substrate surface treatment: Buffing Coating method: Screen printing Dry film thickness: 20μm to 25μm
Pre-drying: 80°C, 20 minutes Exposure: UV light (wavelength 300 nm to 400 nm) is irradiated onto the photosensitive resin composition at 300 mJ/ ^cm2 (exposure device: Oak Manufacturing Co., Ltd. "HMW-680GW")
Alkaline development: 1% by weight _{Na2CO3 aqueous} solution, liquid temperature 30°C, spray pressure 0.2 MPa, development time 60 seconds Heat curing treatment (post cure): 150°C, 60 minutes

The evaluation and measurement items are as follows:
(1) Matte Appearance The 60 degree specular reflectance of the cured coating film surface of the test sample was measured using a glossmeter (VG-2000, Nippon Denshoku Industries Co., Ltd.). A 60 degree gloss value of 55 or less was evaluated as a matte appearance.

(2) Insulation reliability (HAST test)
A cured coating film was formed in accordance with the above test sample preparation process, except that the substrate was changed from a printed wiring board to a comb-shaped test pattern (line width 50 μm, line spacing 50 μm). Using a highly accelerated life testing device (HAST device), a direct current of 20 V was applied in an atmosphere at a temperature of 130° C. and a humidity of 85%, and the resistance value was measured in a tank and rated on a 5-point scale as follows, with a rating of ○ or higher being considered a pass.
⊚: More than 1.0 x 10 ⁸ Ω after 200 hours ⊚: More than 1.0 x 10 ⁸ Ω after 150 hours, 1.0 x 10 ⁸ Ω or less after 200 hours ◯: More than 1.0 x 10 ⁸ Ω after 100 hours, 1.0 x 10 ⁸ Ω or less after 150 hours △: 1.0 x 10 ⁸ Ω or less after 100 hours ×: Short circuit due to migration within 100 hours

The evaluation results for Examples 1 to 12 and Comparative Examples 1 to 5 are shown in Table 1 below.

As shown in Table 1 above, in Examples 1 to 12, which are photosensitive resin compositions containing (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) a filler, and (F) a matting agent surface-treated with an organosilicon compound (using silicon dioxide particles surface-treated with polydimethylsiloxane having an average particle size of 2.7 μm to 6.2 μm), the HAST test gave a rating of ○ or higher, and it was found that excellent insulation reliability was obtained in high-temperature and high-humidity environments and that insulation reliability could be maintained for a long period of time. In addition, in Examples 1 to 12, a cured coating film with a matte appearance was obtained.

In particular, in Examples 1 to 6, in which only silicon dioxide particles surface-treated with polydimethylsiloxane were used as the surface-treated matting agent without using silicon dioxide particles surface-treated with polyethylene wax, the insulation reliability was further improved compared to Examples 7 and 8, in which silicon dioxide particles surface-treated with polyethylene wax were used in combination. In addition, in Example 4, in which about 26 parts by mass of a matting agent surface-treated with an organosilicon compound was blended with 100 parts by mass of photosensitive resin, the matting appearance was further improved, in Example 3, in which about 35 parts by mass of a matting agent surface-treated with an organosilicon compound was blended, the matting appearance was further improved, and in Examples 1, 2, and 6, in which about 44 parts by mass of a matting agent surface-treated with an organosilicon compound was blended, a particularly excellent matting appearance was obtained.

In addition, in Examples 10 to 12, in which silicon dioxide particles surface-treated with polydimethylsiloxane and silicon dioxide particles surface-treated with paraffin wax were used in combination as the surface-treated matting agent, and further, about 2.0 parts by mass of both ion exchangers or an anion exchanger having a total exchange capacity of Cl ⁻ 3.9 meq/g or less was blended with 100 parts by mass of the photosensitive resin, particularly excellent insulation reliability was obtained. In addition, in Examples 9 to 12, in which silicon dioxide particles surface-treated with polydimethylsiloxane and silicon dioxide particles surface-treated with paraffin wax were used in combination as the surface-treated matting agent, and further, an inorganic ion exchanger was blended, particularly excellent matte appearance was obtained similarly to Examples 1, 2, and 6.

On the other hand, in Comparative Examples 1, 2, and 5, in which silicon dioxide particles surface-treated with polyethylene wax were used instead of the matting agent surface-treated with an organosilicon compound, a matte appearance was obtained, but sufficient insulation reliability could not be obtained in a high-temperature, high-humidity environment. In Comparative Examples 3 and 4, in which untreated silicon dioxide particles were used instead of the matting agent surface-treated with an organosilicon compound, insulation reliability could not be obtained in a high-temperature, high-humidity environment.

The photosensitive resin composition of the present invention can produce a photocured product with excellent insulation reliability over a long period of time and a matte appearance, making it highly useful in the field of printed wiring boards, where a matte appearance is required.

Claims (10)

(A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) a filler, and (F) a matting agent that has been surface-treated with an organosilicon compound;
the matting agent (F) that has been surface-treated with an organosilicon compound is (F1) silicon dioxide particles that have been surface-treated with an organosilicon compound,
The silicon dioxide particles (F1) that have been surface-treated with an organosilicon compound have an average particle size (D50) of 1.0 μm or more and 10 μm or less , the particle size being a cumulative volume percentage of 50 volume%;
The photosensitive resin composition , wherein the organosilicon compound is a polydialkylsiloxane . (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) a filler, and (F) a matting agent that has been surface-treated with an organosilicon compound;
the matting agent (F) that has been surface-treated with an organosilicon compound is (F1) silicon dioxide particles that have been surface-treated with an organosilicon compound,
The silicon dioxide particles (F1) that have been surface-treated with an organosilicon compound have an average particle size (D50) of 1.0 μm or more and 10 μm or less, the particle size being a cumulative volume percentage of 50 volume%;
Further, the photosensitive resin composition contains a matting agent which has been surface-treated with a hydrophobic organic compound other than an organosilicon compound. 2. The photosensitive resin composition according to claim 1 , wherein the number of carbon atoms in the alkyl group of the polydialkylsiloxane is 1 or more and 5 or less. 2. The photosensitive resin composition according to claim 1 , wherein the polydialkylsiloxane is polydimethylsiloxane. 3. The photosensitive resin composition according to claim 1, further comprising 5.0 parts by mass or more and 100 parts by mass or less of the matting agent (F) that has been surface-treated with an organosilicon compound, relative to 100 parts by mass of the photosensitive resin (A) . 3. The photosensitive resin composition according to claim 1, wherein the photosensitive resin (A) is a polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin having a chemical structure obtained by reacting a radically polymerizable unsaturated monocarboxylic acid with at least a part of the epoxy groups of a multifunctional epoxy resin having two or more epoxy groups in one molecule to obtain a radically polymerizable unsaturated monocarboxylated epoxy resin, and reacting a polybasic acid and/or a polybasic acid anhydride with hydroxyl groups of the radically polymerizable unsaturated monocarboxylated epoxy resin, and the epoxy compound (D) contains the same type of epoxy resin as the multifunctional epoxy resin. The photosensitive resin composition according to claim 1 or 2 , further comprising an inorganic ion exchanger. 3. The photosensitive resin composition according to claim 1, which is used as a solder resist for a printed wiring board. A photocured product of the photosensitive resin composition according to claim 1 or 2 . A printed wiring board coated with the photosensitive resin composition according to claim 1 or 2 .