JP7405803B2 - Photosensitive resin composition, photocured product of the photosensitive resin composition, and printed wiring board coated with the photosensitive resin composition - Google Patents

Description

The present invention relates to photosensitive resin compositions, particularly photosensitive resin compositions useful as insulation coatings for circuit boards such as printed wiring boards, photocured products of photosensitive resin compositions, and photocurable photosensitive resin compositions. The present invention relates to a printed wiring board having a coating obtained by the above method.

A printed wiring board with a conductor circuit pattern formed on a substrate such as a rigid board or a flexible board is used to mount electronic components on the soldering land of the conductor circuit pattern, and the circuit part other than the soldering land is covered with an insulating protective film. It is covered with a solder resist film. This prevents solder from adhering to unnecessary parts when soldering electronic components to circuit boards such as printed wiring boards, and also prevents conductor circuits from being directly exposed to air and causing oxidation and humidity. Prevent corrosion.

Further, as the wiring density of printed wiring boards becomes finer, a coating film of a photosensitive resin composition applied as an insulating protective film is required to have high resolution. In addition, in recent years, as electronic devices have become more sophisticated, the environment in which printed wiring boards are installed has become increasingly harsh, and it is also required to prevent deterioration of the insulating protective film due to thermal history and heat load.

Therefore, in order to suppress the deterioration of the insulating protective film due to thermal history and heat load, a heat dissipating insulating resin composition containing heat dissipating inorganic particles and a curable resin composition is provided, in which the heat dissipating inorganic particles include: A resin composition containing β-silicon carbide particles surface-treated with a coupling agent such as a silane coupling agent has been proposed (Patent Document 1). The resin composition of Patent Document 1 is said to improve thermal shock resistance and crack resistance while improving the thermal conductivity of the cured product.

However, in Patent Document 1, when the insulating protective film is repeatedly exposed to a low-temperature atmosphere and a high-temperature atmosphere, cracks may occur in the insulating protective film, and there is still room for improvement in crack resistance. That is, in Patent Document 1, there was a need for further improvement in the thermal shock resistance of the insulating protective film. In particular, Patent Document 1 has a problem in that cracks are likely to occur at the corners of the openings of the insulating protective film when the insulating protective film is repeatedly exposed to a low-temperature atmosphere and a high-temperature atmosphere.

On the other hand, the insulating protective film is sometimes required to have a matte appearance. In order to give the insulating protective film a matte appearance, the surface of the insulating protective film is sometimes roughened. In order to roughen the surface of the insulating protective film, inorganic filler particles having an average particle diameter of approximately 6.0 μm to 7.0 μm or more may be blended into the resin composition. However, when inorganic filler particles with an average particle size of approximately 6.0 μm to 7.0 μm or more are added to the resin composition in order to give the insulating protective film a matte appearance, the thermal shock resistance of the insulating protective film may decrease. was there.

Further, in order to give the insulating protective film a matte appearance, the surface of the insulating protective film may be roughened by blending urethane beads into the resin composition. However, since the thermal decomposition temperature of urethane beads is lower than that of inorganic fillers, when urethane beads are added to a resin composition, the soldering heat resistance required for the insulating protective film of a circuit board may be reduced.

JP2019-179910A

In view of the above circumstances, the present invention makes it possible to obtain a photocured product having a matte appearance and excellent soldering heat resistance and thermal shock resistance without impairing basic properties such as alkali developability and coating film appearance. The present invention aims to provide a photosensitive resin composition, 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, (B) photopolymerization initiator, (C) reactive diluent, (D) epoxy compound, (E) inorganic filler, (F) silica particles, Contains
(F) A photosensitive resin composition in which the silica particles have an average particle diameter of 3.0 μm or more and 5.0 μm or less.
[2] The photosensitive resin composition according to [1], wherein the silica particles (F) are surface-treated with an organosilicon compound or wax.
[3] The photosensitive resin composition according to [1] or [2], wherein the silica particles (F) have an average particle diameter of 3.5 μm or more and 4.5 μm or less.
[4] According to any one of [1] to [3], the (F) silica particles are contained in 2.0 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the (A) photosensitive resin. photosensitive resin composition.
[5] The photosensitive resin composition according to any one of [1] to [4], wherein the inorganic filler (E) contains scaly silica having a main surface and an end surface.
[6] The photosensitive resin according to [5], wherein the main surface of the primary particles of the scaly silica has a surface diameter of 1.0 μm or more and 10 μm or less, and the end face of the primary particles has a thickness of 0.20 μm or less. Composition.
[7] The photosensitive resin composition according to any one of [1] to [6], further containing (G) an elastomer.
[8] The photosensitive resin composition according to [7], wherein the elastomer (G) is a telechelic polymer.
[9] The photosensitive resin composition according to any one of [1] to [8], which is used as a solder resist for a printed wiring board.
[10] A photocured product of the photosensitive resin composition according to any one of [1] to [9].
[11] A printed wiring board coated with the photosensitive resin composition according to any one of [1] to [9].

In the present invention, the "average particle diameter" is the particle diameter at which the cumulative volume percentage is 50% by volume (D50), and means the particle diameter measured with a particle size distribution measuring device using a laser diffraction/scattering method.

According to an embodiment of the photosensitive resin composition of the present invention, it contains (F) silica particles, and the average particle diameter of the (F) silica particles is 3.0 μm or more and 5.0 μm or less, so that alkaline development is possible. It is possible to obtain a photocured product having a matte appearance and excellent solder heat resistance and thermal shock resistance without impairing basic properties such as properties and coating appearance.

According to an aspect of the photosensitive resin composition of the present invention, the (F) silica particles are surface-treated silica particles with an organosilicon compound or wax, thereby further ensuring soldering heat resistance and thermal shock resistance. can be improved.

According to an aspect of the photosensitive resin composition of the present invention, the average particle diameter of the silica particles (F) is 3.5 μm or more and 4.5 μm or less, thereby further ensuring soldering heat resistance and thermal shock resistance. can be improved.

According to an aspect of the photosensitive resin composition of the present invention, by containing the silica particles (F) from 2.0 parts by mass to 50 parts by mass with respect to 100 parts by mass of the photosensitive resin (A), It is possible to reliably obtain a matte appearance while further reliably improving solder heat resistance and thermal shock resistance.

According to an aspect of the photosensitive resin composition of the present invention, the inorganic filler (E) contains scaly silica having a main surface and an end surface, thereby improving soldering heat resistance and heat resistance without impairing the matte appearance. Impact resistance is further improved.

According to the aspect of the photosensitive resin composition of the present invention, by further containing (G) an elastomer, the elasticity of the photocured product of the photosensitive resin composition is reduced, which can contribute to improving thermal shock resistance. .

Next, the photosensitive resin composition of the present invention will be explained below. The photosensitive resin composition of the present invention comprises (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, and (E) an inorganic filler. (F) silica particles, and the average particle diameter of the silica particles (F) is 3.0 μm or more and 5.0 μm or less. The photosensitive resin composition of the present invention contains (F) silica particles, and the average particle diameter of the (F) silica particles is 3.0 μm or more and 5.0 μm or less. A photocured product having a matte appearance and excellent solder heat resistance and thermal shock resistance can be obtained without impairing basic properties such as appearance.

(A) Photosensitive resin Examples of the photosensitive resin include carboxyl group-containing photosensitive resins. The chemical structure of the carboxyl group-containing photosensitive resin is not particularly limited, and examples include resins that have a free carboxyl group and one or more photosensitive unsaturated double bonds. As a carboxyl group-containing photosensitive resin, for example, acrylic acid or methacrylic acid (hereinafter referred to as "(meth)acrylic acid") is added to at least a part of the epoxy groups of a polyfunctional epoxy resin having two or more epoxy groups in one molecule. ) and other radically polymerizable unsaturated monocarboxylic acids such as epoxy acrylates and epoxy methacrylates (hereinafter, acrylates and methacrylates may be referred to as "(meth)acrylates"). Polybasic acid-modified epoxy (meth)acrylate, etc. having a chemical structure obtained by obtaining a saturated monocarboxylic oxidized epoxy resin and reacting the hydroxyl groups generated in the resin with a polybasic acid and/or a polybasic acid anhydride. Examples include polybasic acid-modified radically polymerizable unsaturated monocarboxylic oxidized epoxy resins.

The chemical structure of the polyfunctional epoxy resin is not particularly limited as long as it is a bifunctional or more functional epoxy resin. The epoxy equivalent of the polyfunctional epoxy resin is not particularly limited, and for example, the upper limit of the epoxy equivalent is preferably 2,000, more preferably 1,500, even more preferably 1,000, and particularly preferably 500. On the other hand, the lower limit of the epoxy equivalent of the polyfunctional epoxy resin is preferably 100, particularly preferably 200. Examples of polyfunctional epoxy resins 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, Phenol novolak type epoxy resins such as bisphenol F type epoxy resin and bisphenol AD type epoxy resin, cresol novolac type epoxy resin such as о-cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, cycloaliphatic epoxy resin, glycidyl ester type Epoxy resin, glycidylamine type epoxy resin, heterocyclic epoxy resin, bisphenol modified novolac type epoxy resin, polyfunctional modified novolac type epoxy resin, condensation product type epoxy resin of phenols and aromatic aldehyde having a phenolic hydroxyl group, etc. can be mentioned. Furthermore, epoxy resins obtained by introducing halogen atoms such as Br and Cl into these epoxy resins may also be used. These 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, crotonic acid, cinnamic acid, tiglic acid, and angelic acid. Among these, (meth)acrylic acid is preferred from the viewpoint of easy availability. These radically polymerizable unsaturated monocarboxylic acids may be used alone or in combination of two or more. When the radically polymerizable unsaturated monocarboxylic acid reacts with the epoxy group of the polyfunctional epoxy resin to form an ester bond, a photosensitive unsaturated double bond is introduced into the epoxy resin, making the epoxy resin photosensitive. will be granted.

The reaction method of the polyfunctional epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is not particularly limited. An example is a method of heating with stirring in an organic solvent).

By the reaction between the polyfunctional epoxy resin and the radically polymerizable unsaturated monocarboxylic acid, the polybasic acid and/or polybasic acid anhydride reacts with the hydroxyl groups generated in the radically polymerizable unsaturated monocarboxylated epoxy resin. , a free carboxyl group is further introduced into the resin into which a photosensitive unsaturated double bond has been introduced. By introducing a free carboxyl group into a resin into which a photosensitive unsaturated double bond has been introduced, alkaline developability is imparted to the resin. The polybasic acid is not particularly limited as long as it is a bifunctional or more functional carboxylic acid, and either saturated or unsaturated polybasic acids can be used. Examples of polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, and phthalic acid derivatives (e.g., tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyl Tetrahydrophthalic acid, 4-ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid Difunctional carboxylic acids such as phthalic acid, methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, diglycolic acid, trifunctional carboxylic acids such as trimellitic acid, pyromellitic acid, etc. Examples include tetrafunctional carboxylic acids. Further, 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 reaction method of the radically polymerizable unsaturated monocarboxylated epoxy resin and the polybasic acid and/or polybasic acid anhydride is not particularly limited. A method of heating the mixture and/or polybasic acid anhydride in an appropriate diluent (for example, an inert organic solvent) with stirring can be mentioned.

The polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin described above can also be used as a carboxyl group-containing photosensitive resin, but if necessary, the carboxyl group of the polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin Even if a carboxyl group-containing photosensitive resin has a chemical structure in which a compound (for example, a glycidyl compound) having one or more radically polymerizable unsaturated groups and an epoxy group is further reacted with a part of the group, good. In a resin obtained by further reacting a compound having a radically polymerizable unsaturated group and an epoxy group, the photosensitivity is further improved by further introducing a radically polymerizable unsaturated group into the side chain.

Since the carboxyl group-containing photosensitive resin has a chemical structure in which a part of the carboxyl group is reacted with a compound having a radically polymerizable unsaturated group and an epoxy group, polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy Since a radically polymerizable unsaturated group is further bonded to the side chain of the resin skeleton, the photopolymerization reactivity, that is, photocurability is further improved, and more excellent photosensitive characteristics are exhibited. Examples of compounds having one or more radically polymerizable unsaturated groups and epoxy groups include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, pentaerythritol triacrylate monoglycidyl ether, pentaerythritol trimethacrylate monoglycidyl ether, etc. It will be done. The above-mentioned compounds having one or more radically polymerizable unsaturated groups and epoxy groups may be used alone or in combination of two or more.

Furthermore, when the photosensitive resin composition is not developed with alkali, a photosensitive resin having no free carboxyl group may be used. Examples of photosensitive resins that do not have free carboxyl groups include polymers of monomers consisting of (meth)acrylate, epoxy (meth)acrylate obtained by reacting (meth)acrylic acid with epoxy resin, and urethane. (Meth)acrylate, etc. can be mentioned.

Examples of the epoxy (meth)acrylate include the epoxy (meth)acrylate obtained in the process of preparing the carboxyl group-containing photosensitive resin described above. Examples of urethane (meth)acrylate include urethane (meth)acrylate obtained by reacting urethane resin with (meth)acrylic acid. 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. Further, as the urethane (meth)acrylate, for example, epoxy (meth)acrylate is obtained by reacting (meth)acrylic acid with at least a part of the epoxy group of an epoxy resin having one or more epoxy groups in one molecule. , urethane (meth)acrylate obtained by adding a compound having one or more isocyanate groups in one molecule to the generated hydroxyl group, two or more hydroxyl groups in one molecule to the hydroxyl group generated in the above epoxy (meth)acrylate. Examples include urethane (meth)acrylate obtained by addition-reacting a polyisocyanate having an isocyanate group with a polyol.

When the photosensitive resin has a free carboxyl group, the acid value of the photosensitive resin is not particularly limited. For example, the lower limit of the acid value is preferably 30 mgKOH/g from the viewpoint of ensuring alkaline developability, and 40 mgKOH/g. /g is particularly preferred. On the other hand, the upper limit of the acid value of the photosensitive resin is preferably 200 mgKOH/g, for example, from the viewpoint of preventing dissolution of exposed areas by an alkaline developer, and reliably prevents deterioration of moisture resistance and insulation reliability of the photocured product. From this point of view, 150 mgKOH/g is particularly preferable.

The mass average molecular weight (Mw) of the photosensitive resin is not particularly limited, and for example, the lower limit of the mass average molecular weight (Mw) is preferably 6000 and 7000 from the viewpoint of toughness and dryness to the touch of the photocured product. is more preferred, and 8000 is particularly preferred. 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 alkali developability. In addition, the mass average molecular weight (Mw) means the molecular weight measured by gel permeation chromatography (GPC) measurement.

The photosensitive resin may be synthesized by the reaction described above using each of the starting materials, as exemplified above, or a commercially available photosensitive resin may be used. Examples of photosensitive resins on the market include "Lipoxy SP-4621" (Showa Denko K.K.), "KAYARAD ZAR-2000", "KAYARAD ZFR-1122", "KAYARAD FLX-2089", and "KAYARAD ZCR-". Examples include carboxyl group-containing photosensitive resins such as "Cyclomer P (ACA) Z-250" (Daicel Corporation) and "Cyclomer P (ACA) Z-250" (Nippon Kayaku Co., Ltd.). 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 commonly used. For example, 2-benzyl-2-(N,N-dimethylamino)-1-(4 α-aminoalkylphenone photopolymerization initiators such as -morpholinophenyl)butan-1-one, 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-methylbenzoyl)-9H-carbazol-3-yl]- 1-(0-acetyloxime), 2-(acetyloxyiminomethyl)thioxanthene-9-one, 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-carbazol-3-yl] -,1,8-bis(O-acetyloxime), (Z) -(9-ethyl-6-nitro-9H-carbazol-3-yl)(4-((1-methoxypropan-2-yl)oxy) ) -2-methylphenyl)methanone Oxime ester photopolymerization initiators such as O-acetyloxime and the like can be mentioned. Examples of photopolymerization initiators other than α-aminoalkylphenone photopolymerization initiators and oxime ester photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin, benzoin methyl ether, and benzoin methyl ether. 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-hydroxycyclohexylphenyl ketone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4 '-Diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4- Examples include 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 the photopolymerization initiator is not particularly limited, but is preferably 2.0 parts by mass or more and 30 parts by mass or less, and 5.0 parts by mass based on 100 parts by mass (solid content, the same applies hereinafter) of the photosensitive resin. Particularly preferably 20 parts by mass or less.

(C) Reactive diluent The reactive diluent is, for example, a photopolymerizable monomer, and is 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 impart mechanical strength to the photocured product by sufficiently photocuring the photosensitive resin composition, and to obtain a photocured product having acid resistance and alkali resistance.

As reactive diluents, mention may be made of (meth)acrylate monomers. Examples of the (meth)acrylate monomer include monofunctional (meth)acrylate monomers, bifunctional (meth)acrylate monomers, and trifunctional or more functional (meth)acrylate monomers. Specific examples include monofunctional (meth)acrylate such as 2-hydroxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. ) Acrylate monomer; 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, neopentyl hydroxypivalate glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, cyclohexyl allylate Bifunctional (meth)acrylate monomers such as di(meth)acrylate, isocyanurate di(meth)acrylate; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate , pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, ditrimethylolpropane tetra(meth)acrylate, propionic acid modified dipentaerythritol penta(meth)acrylate , dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. Examples of the (meth)acrylate monomer include other caprolactone-modified dipentaerythritol (meth)acrylates and urethane (meth)acrylates. These may be used alone or in combination of two or more.

Among these, caprolactone-modified dipentaerythritol (meth)acrylate such as caprolactone-modified dipentaerythritol hexa(meth)acrylate, dipentaerythritol Hexa(meth)acrylate is preferred.

The amount of the reactive diluent is not particularly limited, and for example, it is preferably 5.0 parts by mass or more and 100 parts by mass or less, particularly preferably 10 parts by mass or more and 50 parts by mass or less, based on 100 parts by mass of the photosensitive resin. .

(D) Epoxy compound The epoxy compound is a component for increasing the crosslinking density of the photocured product to obtain a photocured product with sufficient strength. Examples of epoxy compounds include epoxy resins. Examples of the epoxy resin include biphenyl-type epoxy resin, naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin, rubber-modified epoxy resin such as silicone-modified epoxy resin, ε-caprolactone-modified epoxy resin, bisphenol A-type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin such as bisphenol AD type epoxy resin, cresol novolak type epoxy resin such as о-cresol novolac type epoxy resin, biphenyl novolac type epoxy resin, bisphenol A novolac type epoxy resin, cycloaliphatic epoxy resin , glycidyl ester type epoxy resin, glycidylamine type epoxy resin, heterocyclic epoxy resin, bisphenol modified novolak type epoxy resin, polyfunctional modified novolak type epoxy resin, condensation product type of phenols and aromatic aldehyde having a phenolic hydroxyl group Examples include epoxy resin. These epoxy compounds may be used alone or in combination of two or more.

Among these epoxy compounds, when polybasic acid-modified radically polymerizable unsaturated monocarboxylic oxidized epoxy resin is used as a photosensitive resin, it also contributes to reliably improving thermal shock resistance and soldering heat resistance. Therefore, it is preferable that the epoxy resin contains the same epoxy resin as the epoxy resin forming the skeleton of the polybasic acid-modified radically polymerizable unsaturated monocarboxylated epoxy resin.

The amount of the epoxy compound is not particularly limited, and for example, from the viewpoint of obtaining a cured coating film with sufficient strength, it is preferably 10 parts by mass or more and 100 parts by mass or less, and 30 parts by mass, based on 100 parts by mass of the photosensitive resin. Particularly preferably 70 parts by mass or less.

(E) Inorganic filler By containing an inorganic filler, soldering heat resistance can be improved more reliably. Examples of the inorganic filler include talc, barium sulfate, alumina, aluminum hydroxide, mica, and scaly silica having a main surface and end surfaces. Among these, (E1) an inorganic filler containing scaly silica having a main surface and end faces is preferred because the solder heat resistance and thermal shock resistance are further improved without impairing the matte appearance.

(E1) The scaly silica having a main surface and end faces is a flaky silica, unlike an amorphous silica powder formed by crushing large particles of silica. Further, a plurality of flaky silica particles are interconnected to form a thin film-like connected aggregate. That is, a plurality of flaky silica particles, which are primary particles, are connected to form a thin film-like connected aggregate.

The size of the primary particles of scaly silica is not particularly limited, but from the viewpoint of forming a photocured product with further improved soldering heat resistance and thermal shock resistance, the surface diameter of the main surface is preferably 1.0 μm or more and 10 μm or less. , more preferably 2.0 μm or more and 7.0 μm or less, particularly preferably 2.5 μm or more and 6.0 μm or less. Further, the thickness of the end face of the primary particles of scaly silica is not particularly limited, but from the viewpoint of forming a photocured product with further improved solder heat resistance and thermal shock resistance, it is preferably 0.20 μm or less, and 0.15 μm or less. The following is more preferable, and 0.10 μm or less is particularly preferable. The lower limit of the thickness of the end face of the primary particles of scaly silica can be, for example, 0.05 μm. Note that the "surface diameter of the main surface" means the diameter of a virtual circle having the same area as the main surface.

The scale ratio (diameter of main surface/thickness of end face) in the primary particles of scale-like silica is not particularly limited, but from the point of view of forming a photocured product with further improved solder heat resistance and thermal shock resistance, It is preferably 20 or more and 200 or less, particularly preferably 30 or more and 100 or less. The size of the primary particles of scaly silica can be measured using an electron micrograph. The size of the connected aggregate (i.e., secondary particles or tertiary particles) formed by connecting a plurality of scaly silica particles, which are primary particles, is not particularly limited, and may be, for example, 5.0 μm or more and 200 μm or less. Note that the surface of the flaky silica does not need to be subjected to surface treatment such as hydrophobic treatment using a hydrophobic compound or the like.

The amount of scaly silica to be blended is not particularly limited, and for example, the lower limit is set to 100 parts by mass of the photosensitive resin in order to more reliably form a photocured product with excellent solder heat resistance and thermal shock resistance. The amount is preferably 5.0 parts by mass, more preferably 10 parts by mass, and particularly preferably 15 parts by mass. On the other hand, the upper limit of the blending amount of scaly silica is preferably 50 parts by mass, and 40 parts by mass, based on 100 parts by mass of the photosensitive resin, from the viewpoint of imparting excellent coating properties to the photosensitive resin composition. is more preferable, and 25 parts by mass is particularly preferable.

The blending amount of the inorganic filler is not particularly limited, and for example, the lower limit thereof is preferably 20 parts by mass, and 40 parts by mass, based on 100 parts by mass of the photosensitive resin, in order to reliably contribute to improving the soldering heat resistance. parts by weight is more preferable, and 60 parts by weight is particularly preferable. On the other hand, the upper limit of the blending amount of the inorganic filler is preferably 150 parts by mass with respect to 100 parts by mass of the photosensitive resin, from the viewpoint of imparting excellent coating properties to the photosensitive resin composition, and 100 parts by mass is preferable. More preferably, 80 parts by mass is particularly preferred.

(F) Silica particles In the photosensitive resin composition of the present invention, silica particles having an average particle diameter of 3.0 μm or more and 5.0 μm or less are blended as silica particles. By incorporating silica particles with an average particle diameter of 3.0 μm or more and 5.0 μm or less, the product has excellent solder heat resistance and thermal shock resistance without impairing basic properties such as alkali developability and coating appearance. A photocured product with a matte appearance can be obtained. Component (F), silica particles with an average particle diameter of 3.0 μm or more and 5.0 μm or less (hereinafter sometimes simply referred to as "silica particles of component (F)"), functions as a matting agent. . By blending the silica particles of component (F), it has a matte appearance and excellent thermal shock resistance, so even if the insulating protective film is repeatedly exposed to low-temperature and high-temperature atmospheres, it will not protect the insulation. It is possible to prevent cracks from occurring at the corners of the opening of the membrane.

By blending silica particles with an average particle diameter controlled in the range of 3.0 μm or more and 5.0 μm or less, that is, the silica particles of component (F) as a matting agent, the silica particles in the photosensitive resin composition can be blended. Since the dispersibility of particles can be made uniform, it is thought that uneven distribution of thermal stress generated at the interface between the photosensitive resin and the inorganic filler can be prevented, and a photocured product with excellent thermal shock resistance can be obtained.

The external shape of the silica particles of component (F) is not particularly limited, but examples thereof include powder, spherical, crushed, fibrous, and acicular shapes. Among these, spherical and crushed shapes are preferable from the viewpoint of forming a uniform, finely uneven rough surface on the surface of the cured product and easily obtaining a matte appearance. The silica particles of component (F) are, for example, an aggregate of primary particles.

The silica particles of component (F) can further reliably improve soldering heat resistance and thermal shock resistance, and can also make the dispersibility in the photosensitive resin composition more uniform, so the silica particles can be combined with organosilicon compounds or wax. Preferably, silica particles are surface-treated with In addition, when the silica particles which are component (F) are surface-treated with an organosilicon compound or wax, the average particle diameter is the average particle diameter including the organosilicon compound or wax on the surface of the silica particles.

The average particle diameter of the silica particles of component (F) is not particularly limited as long as it is in the range of 3.0 μm or more and 5.0 μm or less, but the lower limit is set in 3. 3 μm is preferred, 3.5 μm is more preferred, and 3.7 μm is particularly preferred. On the other hand, the upper limit of the average particle diameter of the silica particles of component (F) is preferably 4.7 μm, particularly preferably 4.5 μm, from the standpoint of further reliably improving soldering heat resistance and thermal shock resistance. .

The amount of silica particles as component (F) is not particularly limited, but the lower limit is to ensure that a matte appearance is obtained and to further improve soldering heat resistance and thermal shock resistance based on 100 parts by mass of the photosensitive resin. From the viewpoint of reliably improving the amount, 2.0 parts by mass is preferred, 5.0 parts by mass is more preferred, and 10 parts by mass is particularly preferred. On the other hand, the upper limit of the blending amount of the silica particles as component (F) is preferably 50 parts by mass based on 100 parts by mass of the photosensitive resin to ensure excellent coating properties and thermal shock resistance. 40 parts by mass is more preferred, and 30 parts by mass is particularly preferred.

In addition to the above-mentioned components (A) to (F), the photosensitive resin composition of the present invention may optionally contain various components such as (G) an elastomer, a colorant, various additives, and A reactive diluent or the like may be included.

(G) Elastomer By containing an elastomer, the elasticity of the photocured product of the photosensitive resin composition is reduced, contributing to improvement in thermal shock resistance. Examples of the elastomer include (G1) telechelic polymer. Since telechelic polymers can moderately reduce the elasticity of photocured products of photosensitive resin compositions, they can reduce thermal stress on photocured products even if the photocured products are repeatedly exposed to low-temperature and high-temperature environments. Contribute to Therefore, by blending a telechelic polymer as an elastomer, it can contribute to forming a photocured product with even better thermal shock resistance. Moreover, since the telechelic polymer can react with the resin component of the photosensitive resin composition, it contributes to obtaining solder heat resistance.

Examples of telechelic polymers include telechelic polymers having an [a1]-[b]-[a2] structure. [a1] and [a2] are terminal sites that are reactive functional groups, and [b] is a main chain site that has a flexible structure. The telechelic polymer having the [a1]-[b]-[a2] structure is a bifunctional telechelic polymer having reactive functional groups at both ends.

Examples of the reactive functional groups constituting [a1] include alkenyl groups, acryloyl groups, and methacryloyl groups.Acryloyl groups and/or methacryloyl groups (hereinafter referred to as "( meth)acryloyl group) is preferred. Examples of the reactive functional group constituting [a2] include an alkenyl group, an acryloyl group, and a methacryloyl group, and a (meth)acryloyl group is preferred since it contributes more reliably to improving thermal shock resistance. The reactive functional group constituting [a2] may be the same as or different from the reactive functional group constituting [a1].

The structure of [b], which is the main chain part, can be achieved by, for example, reducing the elasticity of the photocured product of the photosensitive resin composition more reliably and appropriately, so that the photocured product is repeatedly exposed to low-temperature atmosphere and high-temperature atmosphere. The structure of a polymer of (meth)acrylic acid and/or (meth)acrylic acid ester is preferable because it contributes more reliably to preventing the occurrence of cracks even if the structure is oxidized.

The chemical structure of the polymer of (meth)acrylic acid and/or (meth)acrylic acid ester having the structure [b] is, for example, the following formula (1).
(CH ₂ -C(COOR ¹ )R ² ) _n (1)
(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ² is a hydrogen atom or a methyl group, and n is an integer of 1 to 300.) An example is the structure of a polymer.

The number average molecular weight (Mn) of the telechelic polymer is not particularly limited, but is preferably 5,000 or more and 40,000 or less since it can reliably contribute to improving thermal shock resistance. The number average molecular weight (Mn) of 5,000 or more and 40,000 or less is obtained, for example, by polymerizing (meth)acrylic acid and/or (meth)acrylic acid ester using an organic halogen compound or a halogenated sulfonyl compound as an initiator and a transition metal complex as a catalyst. It can be obtained by living radical polymerization. That is, a telechelic polymer having a number average molecular weight (Mn) of 5,000 or more and 40,000 or less has a main chain formed by living radical polymerization.

Examples of the elastomer include polymers that are liquid at room temperature (23° C.) before the photosensitive resin composition of the present invention is cured. The telechelic polymer described above, in which [a1] and [a2] are (meth)acryloyl groups, and [b] is a polymer structure of a (meth)acrylic acid ester represented by formula (1), can be used at room temperature. It is liquid at (23°C). Since the elastomer is liquid at room temperature (23°C), the dispersibility of the elastomer in the photosensitive resin composition can be made uniform.

The amount of the elastomer to be blended is not particularly limited, but the lower limit is preferably 5.0 parts by mass, and 10 parts by mass, based on 100 parts by mass of the photosensitive resin, in order to reliably contribute to improving thermal shock resistance. is more preferable, and 15 parts by mass is particularly preferable. On the other hand, the upper limit of the blending amount of the elastomer is preferably 50 parts by mass, more preferably 35 parts by mass, and particularly preferably 25 parts by mass from the viewpoint of obtaining excellent soldering heat resistance.

The coloring agent is not particularly limited to pigments, dyes, etc., and may also include white coloring agent, blue coloring agent, green coloring agent, yellow coloring agent, purple coloring agent, black coloring agent, red coloring agent, orange coloring agent, etc. Any colorant can be used depending on the desired color. Examples of the above-mentioned colorants include titanium dioxide which is a white colorant, inorganic colorants such as acetylene black and carbon black which are black colorants, phthalocyanine green and lyonol green which are green colorants, and blue colorants. Examples include organic colorants such as phthalocyanine colorants such as phthalocyanine blue and lyonol blue, and diketopyrrolopyrrole colorants such as chromophthalo orange, which is an orange colorant.

Examples of additives include silicone-based, hydrocarbon-based, acrylic-based antifoaming agents, silane-based, titanate-based, alumina-based coupling agents, boron trifluoride-amine complexes, dicyandiamide (DICY), and the like. derivatives, organic acid hydrazides, diaminomaleonitrile (DAMN) and its derivatives, guanamine and its derivatives, melamine and its derivatives, amine imide (AI) and latent curing agents such as polyamines, acetylacenate Zn and acetylacenate Cr, etc. Metal salts of acetylacetone, enamines, tin octylate, quaternary sulfonium salts, triphenylphosphine, imidazoles such as mercaptobenzimidazole, mercaptobenzoxazole, imidazolium salts, thermosetting accelerators such as triethanolamine borate, polycarbonate Examples include thixotropic agents such as acid amides, dispersants, and the like.

The non-reactive diluent is a component for adjusting the drying properties and coating properties of the photosensitive resin composition, if necessary. Non-reactive diluents include, for example, organic solvents. Organic solvents include, for example, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, and propylene glycol monomethyl ether. Glycol ethers such as , diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene Examples include esters such as glycol monomethyl ether acetate and esterified products of the above-mentioned glycol ethers; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; petroleum naphtha; and the like. These non-reactive diluents may be used alone or in combination of two or more.

The method for producing the photosensitive resin composition of the present invention is not limited to a specific method, and for example, after blending each of the above components in a predetermined ratio, at room temperature (for example, 10°C to 30°C), It can be produced by kneading or mixing using a mixing and kneading means such as a ball mill, a sand mill, a bead mill, a kneader, or a stirring and mixing means such as a super mixer, a planetary mixer, and a trimix. Further, before kneading or mixing, preliminary kneading or preliminary mixing may be performed as necessary.

Next, an example of how to use the photosensitive resin composition of the present invention will be explained. Here, a method of coating the photosensitive resin composition of the present invention on a printed wiring board to form an insulating film such as a solder resist film on the printed wiring board will be described as an example. In this case, the photosensitive resin composition of the present invention is used as a solder resist for printed wiring boards.

The photosensitive resin composition of the present invention produced as described above is applied to a printed wiring board to a desired thickness (for example, a thickness of 5 μm to 100 μm). As the coating means, any known means can be used, such as screen printing, bar coater, spray coating, applicator, blade coater, knife coater, roll coater, gravure coater, and the like. After coating the photosensitive resin composition, if necessary, the photosensitive resin composition is pre-dried using a heating device (e.g., hot air oven, far infrared oven, etc.), and a non-reactive diluent is removed from the photosensitive resin composition. evaporates to make the surface of the paint 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 preliminary drying, a negative film (photomask) having a pattern in which areas other than the lands of the circuit pattern are made translucent is closely adhered to the coating film of the photosensitive resin composition, and ultraviolet rays (for example, The coating film of the photosensitive resin composition is photocured by irradiating it with light (in the range of 300 nm to 400 nm) to form a photocured product. Next, the unexposed areas corresponding to the lands are removed with a dilute alkaline aqueous solution to develop the coating film. As the developing method, for example, a spray method or a shower method is used, and as the dilute alkali aqueous solution, for example, a 0.5% to 5% by mass sodium carbonate aqueous solution can be used. Next, the developed coating film is thermally cured (post-cured) at 130°C to 170°C for 20 to 80 minutes using a heating device (for example, a hot air circulation dryer, etc.). An insulating film (solder resist film) having a desired pattern can be formed on a wiring board.

Next, examples of the present invention will be described, but the present invention is not limited to these examples unless it exceeds the spirit thereof.

Examples 1 to 5, Comparative Examples 1 to 5
The components shown in Table 1 below were blended in the proportions shown in Table 1 below, mixed and dispersed at room temperature using three rolls, and the photosensitive materials used in Examples 1 to 5 and Comparative Examples 1 to 5 were prepared. A synthetic resin composition was prepared. Then, the prepared photosensitive resin composition was applied as follows to prepare a test sample. The numbers in Table 1 below indicate parts by mass unless otherwise specified. In addition, a blank column in Table 1 below means no compounding.

The details of each component in Table 1 below are as follows.
(A) Photosensitive resin/Lipoxy SP-4621: Epoxy acrylate is obtained by reacting at least a portion of the epoxy groups of a cresol novolac type epoxy resin with acrylic acid, and the resulting hydroxyl groups are reacted with a polybasic acid. A polybasic acid-modified epoxy acrylate with a chemical structure of 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: IGM Resins B. V. Company.
・SPEEDCURE TPO: Japan Siberhegner Co., Ltd.
・KAYACURE DETX: Nippon Kayaku Co., Ltd.

(C) Reactive diluent/KAYARAD DPCA-60: Nippon Kayaku Co., Ltd.
・DPHA: Toagosei Co., Ltd.

(D) Epoxy compound/EPICRON N-695: DIC Company.
・NC-3000: Nippon Kayaku Co., Ltd.
・YX-4000HK: Mitsubishi Chemical Corporation.

(E) Inorganic filler/barium sulfate B-30: Sakai Chemical Industry Co., Ltd.
・FH105: Fuji Talc Co., Ltd.
- Sun Lovely: scaly silica, primary particle main surface diameter of 3 μm or more and 5 μm or less, primary particle end face thickness of 0.1 μm or less, AGC SI Tech Co., Ltd.

(F) Silica particles/ACEMATT OK-607: Silica particles surface-treated with wax (wax-treated silica), average particle size 4.4 μm, Evonik Industries.
- EXP8018-1: Silica particles surface-treated with wax (wax-treated silica) average particle diameter 3.9 μm, manufactured by Evonik Industries.
- Cyrophobic 200: Silica particles surface-treated with an organosilicon compound (organosilicon-treated silica), average particle diameter 3.9 μm, Fuji Silicia Co., Ltd.

(G) Elastomer/XMAP RC100C: Telechelic polymer with [a1]-[b]-[a2] structure (wherein [a1] and [a2] are acryloyl groups, [b] is (CH ₂ -CH (COOR ¹ )) _n ), number average molecular weight (Mn) 5000 to 40000, liquid at 23°C, viscosity 160 Pa·s at 23°C, Kaneka Corporation.

Other matting agents・ACEMATT OK-412: Silica particles surface-treated with wax (wax-treated silica), average particle size 6.3 μm, Evonik Industries.
- ACEMATT OK-520: Silica particles surface-treated with wax (wax-treated silica), average particle size 6.5 μm, manufactured by Evonik Industries.
- RHC-732: urethane beads coated with silica, average particle size 3.3 μm, Dainichiseika Kagyo Co., Ltd.

Colorant/LIONOL GREEN JZF-8623: Toyo Color Co., Ltd.
Additive/Melamine: Nissan Chemical Industries, Ltd.
・DICY-7: Japan Epoxy Resin Co., Ltd.
・Antage MB: Kawaguchi Chemical Industry Co., Ltd.
・2MBO: Aldrich chemical company.
Non-reactive diluent/EDGAC: Sanyo Chemical Co., Ltd.

Test sample production process Board: 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: Irradiation of ultraviolet light (wavelength 300 nm to 400 nm) onto the photosensitive resin composition at 300 mJ/ ^cm2 (Exposure device: Oak Seisakusho Co., Ltd. "HMW-680GW")
Alkaline development: 1% by mass Na ₂ CO ₃ , liquid temperature 30°C, spray pressure 0.2MPa, development time 60 seconds Heat curing treatment (post cure): 150°C, 60 minutes

The evaluation/measurement items are as follows.
(1) Thermal Shock Resistance The 100 test samples produced in the above test sample production process were tested at -40°C/ A thermal shock test was conducted for 1000 cycles, with one cycle ranging from 15 minutes to 160°C/15 minutes. Thereafter, the coating film of the printed wiring board was observed using a microscope (×200), and the crack occurrence rate of the coating film was evaluated based on the following criteria. The observation position of the coating film was set at each corner of the coating film that had been alkali-developed into a square shape (each side length 2.4 mm) surrounding the exposed Cu foil (2.0 mm square pad). In addition, those with a rating of ○ or higher were considered to have passed.
◎: Crack occurrence rate is 10% or less ○: Crack occurrence rate is 11% or more and 30% or less ×: Crack occurrence rate is 31% or more

(2) Soldering heat resistance The cured coating film of the test sample prepared in the above test sample preparation process was immersed in a 260°C solder bath for 30 seconds in accordance with the test method of JIS C-6481, and then soldered with cellophane adhesive tape. One cycle of the peeling test (peel test) was repeated 1 to 3 times, and the state of the coating film was visually observed and evaluated based on the following criteria. In addition, those with a rating of ○ or higher were considered to have passed.
◎: No change observed in the coating film even after repeating 3 cycles
○: Changes are observed in the paint film after repeating 3 cycles. △: Changes are observed in the paint film after repeating 2 cycles. ×: Changes are observed in the paint film after 1 cycle.

(3) Alkaline developability Time required to develop the coating film after preliminary drying in the above test sample preparation process at a spray pressure of 0.2 MPa (30°C, using 1% by mass sodium carbonate developer) was set as a break point, the time was measured, and evaluation was made based on the following criteria.
○: Break point less than 30 seconds △: Break point 30 seconds or more and less than 60 seconds ×: Break point 60 seconds or more

(4) Paint film glossiness The 60 degree glossiness (gloss value) of the cured paint film of the test sample prepared in the above test sample preparation process was measured using Micro Trigloss (manufactured by BIC Chemie Japan). , the matte appearance was evaluated. Note that the 60 degree glossiness is expressed as an integer by rounding off the first decimal place of the average value.

(5) Appearance of paint film The state of the paint film of the test sample produced in the above test sample production process was visually observed and evaluated according to the following criteria.
○: No abnormality in the paint film △: Slight whitening in the paint film ×: Significant whitening in the paint film

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

As shown in Table 1 above, (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) an inorganic filler, and (F ) silica particles, and the average particle diameter of the silica particles is 3.0 μm or more and 5.0 μm or less, Examples 1 to 5 have excellent alkali developability and coating film appearance, and also have excellent soldering heat resistance and heat resistance. It was possible to form a cured coating film with improved impact resistance and a matte appearance. Examples 1 to 5 had excellent thermal shock resistance because cracks could be prevented from occurring at the corners of the openings of the cured coatings.

In particular, in Examples 5 and 6, in which about 20 parts by mass of silica particles as component (F) were blended with 100 parts by mass of photosensitive resin, about 20 parts by mass of silica particles as component (F) were blended with 100 parts by mass of photosensitive resin. Compared to Examples 1 and 2, in which 12 parts by mass was added, a more excellent matte appearance could be obtained.

On the other hand, as shown in Table 1 above, in Comparative Examples 1 and 2 in which the average particle diameter of the silica particles was 6.3 μm, although a matte appearance was obtained, thermal shock resistance could not be obtained. Further, in Comparative Examples 4 and 5 in which the average particle diameter of the silica particles was 6.5 μm, although a matte appearance was obtained, thermal shock resistance could not be obtained. In addition, in Comparative Example 3 in which urethane beads coated with silica with an average particle diameter of 3.3 μm were used instead of silica particles, although a matte appearance was obtained, soldering heat resistance was not obtained. Thermal shock resistance was also inferior compared to Examples 1-5.

The photosensitive resin composition of the present invention makes it possible to obtain a photocured product having a matte appearance and excellent soldering heat resistance and thermal shock resistance without impairing basic properties such as alkali developability and coating film appearance. Therefore, it has high utility value, for example, in the field of printed wiring boards that are used in environments where they are repeatedly exposed to low-temperature and high-temperature atmospheres and require a matte appearance.

Claims (10)

Contains (A) a photosensitive resin, (B) a photopolymerization initiator, (C) a reactive diluent, (D) an epoxy compound, (E) an inorganic filler, and (F) silica particles. ,
The average particle diameter of the silica particles (F) is 3.0 μm or more and 5.0 μm or less,
A photosensitive resin composition in which the silica particles (F) are surface-treated with wax . The photosensitive resin composition according to claim 1 , wherein the average particle diameter of the silica particles (F) is 3.5 μm or more and 4.5 μm or less. The photosensitive resin composition according to claim 1 or 2 , comprising 2.0 parts by mass or more and 50 parts by mass or less of the silica particles (F) based on 100 parts by mass of the photosensitive resin (A). The photosensitive resin composition according to any one of claims 1 to 3, wherein the inorganic filler (E) contains scaly silica having a main surface and an end surface. The photosensitive resin composition according to claim 4 , wherein the main surface of the primary particle of the scaly silica has a surface diameter of 1.0 μm or more and 10 μm or less, and the thickness of the end face of the primary particle is 0.20 μm or less. The photosensitive resin composition according to any one of claims 1 to 5 , further comprising (G) an elastomer. The photosensitive resin composition according to claim 6 , wherein the elastomer (G) is a telechelic polymer. The photosensitive resin composition according to any one of claims 1 to 7 , which is used as a solder resist for a printed wiring board. A photocured product of the photosensitive resin composition according to any one of claims 1 to 8 . A printed wiring board coated with the photosensitive resin composition according to any one of claims 1 to 8 .