Photosensitive resin composition, dry film, cured product, and printed wiring board

Abstract

[Problem] To provide a photosensitive resin composition which is excellent in terms of resolution and curability in deep portions even if the photosensitive resin composition contains a specific amount of an inorganic filler. [Solution] Disclosed is a photosensitive resin composition which contains at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a sensitizer, (D) an inorganic filler, and (E) a photopolymerizable monomer, the photosensitive resin composition being characterized in that: the photopolymerization initiator (B) contains an acylphosphine oxide-based photopolymerization initiator and a titanocene-based photopolymerization initiator; the sensitizer (C) contains an anthracene-based sensitizer; the inorganic filler (D) is contained in an amount of 50-90% by mass with respect to the total solid content in the photosensitive resin composition; and the average particle diameter (D50) of the inorganic filler (D) is 0.1-1.0 μm.

Description

Photosensitive resin composition, dry film, cured product, and printed wiring board

[0001] The present invention relates to a photosensitive resin composition, and more particularly to a photosensitive resin composition that can be suitably used for forming an insulating layer such as a solder resist, a dry film using the photosensitive resin composition, a cured product of the photosensitive resin composition or the dry film, and a printed wiring board using these cured products.

[0002] In general, in printed wiring boards used in electronic devices, a solder resist layer is formed on the substrate on which a circuit pattern is formed, except for connection holes, in order to prevent solder from adhering to unnecessary portions of the printed wiring board during processes such as solder reflow when mounting electronic components on the printed wiring board. Solder resist layers are typically formed using so-called photosolder resist, in which a photosensitive resin composition is applied to the substrate, dried, exposed to light, and developed to form a pattern, and the patterned resin is then fully cured by heating or light irradiation. It has also been proposed to form a solder resist layer using a photosensitive dry film without using the liquid photosensitive resin composition described above.

[0003] These photosensitive resin compositions and photosensitive dry films contain an alkali-soluble photosensitive resin component to enable exposure and development, and optionally contain other photopolymerizable monomers and thermosetting components such as epoxy in consideration of heat resistance, substrate adhesion, etc. Furthermore, inorganic fillers are sometimes blended into the photosensitive resin composition to reduce the linear expansion coefficient and suppress peeling of the solder resist layer and warping of the substrate (Patent Document 1, etc.).

[0004] In the field of photosensitive resin compositions, high resolution is required for insulating layers such as solder resists so as to accommodate finer wiring patterns. For example, it has been proposed that excellent resolution can be achieved by focusing on initiators used in photosensitive resin compositions and using specific initiators in combination (Patent Document 2, etc.).

[0005] JP 2001-72834 A JP 2013-228758 A

[0006] As mentioned above, inorganic fillers such as silica have a low thermal expansion coefficient and are therefore widely used to improve the properties of solder resists. However, inorganic fillers generally have low optical transparency, and therefore, as the amount of inorganic filler added increases, there is a problem that light during exposure does not easily reach the bottom of the coating film of the photosensitive resin composition. Furthermore, since the resin components constituting the photosensitive resin composition and the inorganic filler have different refractive indices, light incident on the coating film during exposure is scattered, resulting in a phenomenon in which the resolution becomes poorer toward the bottom (undercut).

[0007] Therefore, an object of the present invention is to provide a photosensitive resin composition that is excellent in resolution and deep curing properties even when it contains a predetermined amount of inorganic filler.

[0008] In view of the above problems, the present inventors conducted studies and found that the use of a specific photopolymerization initiator proposed in Patent Document 2, which is said to be capable of improving resolution, alone does not provide sufficient resolution in photosensitive resin compositions containing a high amount of inorganic filler.Further studies led to the discovery that the use of a specific sensitizer in combination with the specific initiator can provide a photosensitive resin composition with excellent resolution, even when the inorganic filler content is high.The present invention is based on this discovery.That is, the gist of the present invention is as follows.

[0009] [1] A photosensitive resin composition comprising at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a sensitizer, (D) an inorganic filler, and (E) a photopolymerizable monomer, wherein the (B) photopolymerization initiator comprises an acylphosphine oxide photopolymerization initiator and a titanocene photopolymerization initiator, the (C) sensitizer comprises an anthracene sensitizer, the (D) inorganic filler is contained in a proportion of 50 to 90 mass% based on the total solid content of the photosensitive resin composition, and the (D) inorganic filler has an average particle size (D50) of 0.1 to 1.0 μm. [2] The photosensitive resin composition according to claim 1, wherein the acylphosphine oxide photopolymerization initiator and the titanocene photopolymerization initiator are contained in a proportion of 10:1 to 90:1 by mass. [3] The photosensitive resin composition according to claim 1, wherein the (C) sensitizer is contained in a proportion of 2 to 18% by mass relative to the (B) photopolymerization initiator. [4] The photosensitive resin composition according to claim 1, wherein the (D) inorganic filler comprises silica. [5] The photosensitive resin composition according to claim 1, further comprising (F) a thermosetting component. [6] A dry film comprising a first film and a resin layer obtained by applying the photosensitive resin composition according to [1] to one side of the first film and drying the composition. [7] A cured product obtained by curing the photosensitive resin composition according to any one of [1] to [5] or the resin layer of the dry film according to [6]. [8] A printed wiring board comprising a coating made of the cured product according to [7].

[0010] According to the present invention, by using two specific photopolymerization initiators and a specific sensitizer in combination, it is possible to achieve excellent resolution and deep curing properties even in a photosensitive resin composition containing an inorganic filler having a predetermined average particle size in the range of 50 to 90 mass %.

[0011] FIG. 1 is a schematic cross-sectional view of a solder resist for explaining the evaluation of resolution.

[0012] [Photosensitive Resin Composition] The photosensitive resin composition according to the present invention contains at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a sensitizer, (D) an inorganic filler, and (E) a photopolymerizable monomer. Each component constituting the photosensitive resin composition will be described below. In this specification, the term "(meth)acrylic" is used as a general term for both acrylic and methacrylic. Furthermore, the term "(meth)acryloyl" is used as a general term for both acryloyl and methacryloyl. Furthermore, the term "(meth)acrylate" is used as a general term for acrylate, methacrylate, and a mixture thereof.

[0013] <(A) Alkali-Soluble Resin> The alkali-soluble resin (A) contained in the photosensitive resin composition according to the present invention may be any alkali-soluble resin, and known and commonly used ones may be used. The alkali-soluble resin may be used alone or in combination of two or more. Examples include water-soluble resins such as carboxyl group-containing resins and phenolic hydroxyl group-containing resins. Among these, carboxyl group-containing resins and phenolic hydroxyl group-containing resins are preferred due to their excellent developability, and carboxyl group-containing resins are more preferred. By including a carboxyl group in the alkali-soluble resin, it can be made alkaline-developable. Furthermore, from the viewpoint of photosensitivity, it is preferable for the resin to have an ethylenically unsaturated double bond in the molecule in addition to the carboxyl group. However, it is also possible to use only a carboxyl group-containing resin without an ethylenically unsaturated double bond. When the carboxyl group-containing resin does not have an ethylenically unsaturated double bond, a photopolymerizable monomer must be used in combination to render the composition photocurable. The ethylenically unsaturated double bond is preferably derived from acrylic acid, methacrylic acid, or a derivative thereof.

[0014] Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers): In this specification, (meth)acrylate is a general term for acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions.

[0015] (1) Carboxyl group-containing resins obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

[0016] (2) Carboxyl group-containing urethane resins obtained by the polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0017] (3) Carboxylic acid group-containing photosensitive urethane resins obtained by polyaddition reaction of diisocyanates with partially acid anhydride-modified products of reaction products of bifunctional epoxy resins such as bisphenol A epoxy resins, hydrogenated bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bixylenol epoxy resins, and biphenol epoxy resins with monocarboxylic acid compounds having ethylenically unsaturated double bonds such as (meth)acrylic acid, carboxyl group-containing dialcohol compounds, and diol compounds.

[0018] (4) A carboxyl group-containing photosensitive urethane resin having a terminal (meth)acrylate formed by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as a hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (3).

[0019] (5) A carboxyl group-containing photosensitive urethane resin that has been (meth)acrylated at its terminal by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (2) or (3).

[0020] (6) A carboxyl group-containing photosensitive resin obtained by reacting a difunctional or more polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl group present in the side chain.

[0021] (7) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0022] (8) Carboxyl group-containing polyester resins obtained by reacting a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid with a bifunctional oxetane resin, and then adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the resulting primary hydroxyl groups.

[0023] (9) A carboxyl group-containing photosensitive resin obtained by reacting an epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid, such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl groups of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

[0024] (10) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0025] (11) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0026] (12) A carboxyl group-containing photosensitive resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to any of the resins (1) to (11).

[0027] These carboxyl group-containing resins are not limited to those listed above, and may be used alone or in combination. Among them, carboxyl group-containing resins synthesized using compounds having phenolic hydroxyl groups as starting materials, such as carboxyl group-containing resins (10) and (11), are preferably used because of their excellent HAST resistance and PCT resistance.

[0028] The acid value of the carboxyl group-containing resin is preferably 40 to 150 mgKOH / g. By making the acid value of the carboxyl group-containing resin 40 mgKOH / g or more, alkaline development becomes good. Furthermore, by making the acid value 150 mgKOH / g or less, it becomes easier to draw a good resist pattern. More preferably, it is 50 to 130 mgKOH / g.

[0029] The weight-average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. By making the weight-average molecular weight 2,000 or more, tack-free performance and resolution can be improved. Furthermore, by making the weight-average molecular weight 150,000 or less, developability and storage stability can be improved. A weight-average molecular weight of 5,000 to 15,000 is more preferable. The weight-average molecular weight can be determined from a standard polystyrene equivalent value by gel permeation chromatography (GPC).

[0030] The amount of the alkali-soluble resin (A) in the photosensitive resin composition is preferably 10 to 50% by mass, calculated as solids. By adjusting the amount to 10% by mass or more, the coating strength can be improved. By adjusting the amount to 50% by mass or less, the viscosity becomes appropriate and printability is improved. A more preferred amount is 10 to 30% by mass.

[0031] <(B) Photopolymerization Initiator> The photosensitive resin composition according to the present invention contains a (B) photopolymerization initiator in order to photopolymerize the above-described (A) alkali-soluble resin and the (D) photopolymerizable monomer described below. In the present invention, the (B) photopolymerization initiator contains an acylphosphine oxide-based photopolymerization initiator and a titanocene-based photopolymerization initiator. By using an acylphosphine oxide-based photopolymerization initiator and a titanocene-based photopolymerization initiator in combination as the photopolymerization initiator, absorption and reactivity are improved not only in the short wavelength region but also in the long wavelength region, and as a result, resolution can be improved.

[0032] Any known photopolymerization initiator can be used as the acylphosphine oxide photopolymerization initiator. Specific examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphinenate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide. These acylphosphine oxide photopolymerization initiators may be used alone or in combination of two or more.

[0033] Of the (B) photopolymerization initiators, the content of the acylphosphine oxide-based photopolymerization initiator is preferably 0.5 to 50 parts by mass, and more preferably 1 to 30 parts by mass, relative to 100 parts by mass of the (A) carboxyl group-containing resin.

[0034] The titanocene photopolymerization initiator used in combination with the acylphosphine oxide photopolymerization initiator may be any known photopolymerization initiator having a titanocene structure. Specific examples of the titanocene photopolymerization initiator include bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyl-1-yl)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(1-pyl-1-yl)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((1-pyl-1-yl)methyl)phenyl]titanium, bis(methylcyclopentadienyl)-bis[2,6-difluoro-3-((1-pyl-1-yl)methyl)phenyl]titanium, and bis(cyclopentadienyl)-bis[2,6-difluoro-3-((1-pyl-1-yl)methyl)phenyl]titanium. Fluoro-3-((2,5-dimethyl-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2-isopropyl-5-methyl-1-pyr-1,6-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2-(2-methoxyethyl)-5-methyl-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((3-trimethylsilyl-2,5-dimethyl-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl) -bis[2,6-difluoro-3-((2,5-dimethyl-3-(bis(2-methoxyethyl)aminomethyl)-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2,5-bis(morpholinomethyl)-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2,5-dimethyl-3-(1,3-dioxolan-2-yl)-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-4-((2,5-dimethyl-1-pyr-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-methyl-4-(2-(1-pyl-1-yl)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2,3,4,5-tetramethyl-1-pyl-1-yl)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,3,5,6-tetrafluoro-4-(3-(1-pyl-1-yl)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyl-1-yl)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(1-methyl-2-(1-pyl-1-yl)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(1-methyl-2-(1-pyl-1-yl)ethyl)phenyl]titanium Fluoro-3-(3-(2-isoindol-2-yl)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(4,5,6,7-tetrahydro-isoindol-2-yl)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(6-(9-carbazol-9-yl)hexyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(2,3,4,5,6,7,8,9-octahydro-1-carbazol-9-yl)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(4,5,6,7-tetrahydro-2-methyl-1-indol-1-yl) propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((acetylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(propionylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(acetylamino)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(4-(pivaloylamino)butyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(2,2-dimethylpentanoylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(benzoylamino)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2,2-dimethylpentanoylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(2,2-dimethyl-3-chloropropanoylamino)ethyl)phenyl]titanium, Bis(cyclopentadienyl)-bis[2,6-difluoro-3-((2,2-dimethyl-3-ethoxypropanoylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(lauroylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(N-allylmethylsulfonylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(N-isobutylphenylsulfonylamino)propyl)phenyl] yl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-((methylsulfonylamino)methyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(3-(ethylsulfonylamino)propyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(butylsulfonylamino)ethyl)phenyl]titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(4-(trisulfonylamino)propyl)phenyl]titanium, bis(η, ５ 3-(1H-pyrrol-1-yl)phenyl)titanium, etc. These titanocene photopolymerization initiators can be used alone or in combination of two or more.

[0035] Of the photopolymerization initiators (B), the content of the titanocene-based photopolymerization initiator is preferably 0.01 to 10 parts by mass, and more preferably 0.01 to 8 parts by mass, relative to 100 parts by mass of the carboxyl group-containing resin (A).

[0036] In the present invention, the (B) photopolymerization initiator preferably contains an acylphosphine oxide photopolymerization initiator and a titanocene photopolymerization initiator in a mass ratio of 10:1 to 90:1, and more preferably 15:1 to 50:1.

[0037] In the present invention, the photopolymerization initiator (B) may contain a known photopolymerization initiator other than the above-mentioned acylphosphine oxide photopolymerization initiator and titanocene photopolymerization initiator, and examples thereof include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, N,N-dimethyl α-aminoacetophenone-based photopolymerization initiators such as phenylaminoacetophenone: hydroxyacetophenone-based photopolymerization initiators such as 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzoin, benzyl, benzyl benzoin-based photopolymerization initiators such as benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ether-based photopolymerization initiators; benzophenone-based photopolymerization initiators such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diphenyl-2-benzophenone, and the like; acetophenone-based photopolymerization initiators such as 2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-pumorpholino; thioxanthone-based photopolymerization initiators such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone;Examples of the photopolymerization initiator include anthraquinone-based photopolymerization initiators such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; ketal-based photopolymerization initiators such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid ester-based photopolymerization initiators such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; and oxime ester-based photopolymerization initiators such as 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, and 1-(O-acetyloxime);

[0038] The amount of the photopolymerization initiator (B) in the photosensitive resin composition is preferably 1 to 50 parts by mass, and more preferably 1 to 20 parts by mass, based on 100 parts by mass of the alkali-soluble resin (A) in terms of solid content, which can improve the curability in deep portions.

[0039] <(C) Sensitizer> The photosensitive resin composition according to the present invention contains an anthracene-based sensitizer as the sensitizer (C) in combination with the specific photopolymerization initiator described above. By including an anthracene-based sensitizer in addition to an acylphosphine oxide-based photopolymerization initiator and a titanocene-based photopolymerization initiator, the curing efficiency by light irradiation during exposure is high, and even in a photosensitive resin composition containing 50 to 90 mass % of an inorganic filler having a specified average particle size, excellent resolution can be achieved and a cured product having sufficient hardness can be formed throughout the entire solder resist layer.

[0040] As the anthracene-based sensitizer, an anthracene compound represented by the following general formula can be preferably used.

[0041] In the above formula, A represents a single bond or an alkylene group having 1 to 20 carbon atoms, and the alkylene group may be branched with an alkyl group. R represents an alkyl group having 1 to 20 carbon atoms, and the alkyl group may be branched with an alkyl group, may be a cycloalkyl group or a cycloalkylalkyl group, may be substituted with a hydroxy group, or may have some of the carbon atoms replaced with oxygen atoms (except in the case where a peroxide is formed). P and Q may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a halogen atom.

[0042] In the above formula, examples of the alkylene group having 1 to 20 carbon atoms represented by A include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, and icosylene. The alkylene group may be branched by an alkyl group.

[0043] In the above formula, examples of the alkyl group having 1 to 8 carbon atoms represented by P or Q include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an n-pentyl group, an i-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and a 2-ethylhexyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0044] In the above formula, examples of the alkyl group having 1 to 20 carbon atoms represented by R include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, an i-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group. Examples of these alkyl groups substituted with a hydroxy group include 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 7-hydroxyheptyl, 8-hydroxyoctyl, 6-hydroxy-2-ethylhexyl, 9-hydroxynonyl, 10-hydroxydecyl, 11-hydroxyundecyl, 12-hydroxydodecyl, 2-hydroxy-3-methyl-2-propanol ... Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, adamantyl, 4-n-dodecylcyclohexyl, decahydronaphthyl, and hydroxycyclohexyl groups.Examples of the cycloalkylalkyl group include a cyclopropylmethyl group, a cyclobutylmethyl group, a cyclopentylmethyl group, a cyclohexylmethyl group, a cycloheptylmethyl group, a cyclooctylmethyl group, a cyclononylmethyl group, a cyclodecylmethyl group, a 2-cyclobutylethyl group, a 2-cyclopentylethyl group, a 2-cyclohexylethyl group, a 2-cycloheptylethyl group, a 2-cyclooctylethyl group, a 2-cyclononylethyl group, a 2-cyclodecylethyl group, a 3-cyclobutylpropyl group, a 3-cyclopropylmethyl ... 3-cyclopentylpropyl group, 3-cyclohexylpropyl group, 3-cycloheptylpropyl group, 3-cyclooctylpropyl group, 3-cyclononylpropyl group, 3-cyclodecylpropyl group, 4-cyclobutylbutyl group, 4-cyclopentylbutyl group, 4-cyclohexylbutyl group, 4-cycloheptylbutyl group, 4-cyclooctylbutyl group, 4-cyclononylbutyl group, 4-cyclodecylbutyl group, 3-3-adamantylpropyl group, and decahydronaphthylpropyl group.

[0045] Among the above, when comprehensively judging from the ease of production, availability of raw materials, and ease of handling, it is preferable that R in the above general formula is an alkyl group having 1 to 20 carbon atoms and not containing an oxygen atom. Also, it is preferable that A in the above general formula is a single bond or a methylene group having 1 carbon atom. Taking into consideration various physical properties such as migration properties and hydrophobicity, it is preferable that R is an alkyl group having 3 or more carbon atoms. From these viewpoints, anthracene-based sensitizers represented by the following formula (1-a) or (1-b) are particularly preferably used.

[0046] As the anthracene-based sensitizer, commercially available products may be used, such as UVS-581, UVS-1101, and UVS-1331 manufactured by Air Performance Chemical Co., Ltd.

[0047] The sensitizer (C) is preferably contained in an amount of 2 to 18% by mass, more preferably 5 to 15% by mass, relative to the photopolymerization initiator (B).

[0048] <(D) Inorganic Filler> The photosensitive resin composition according to the present invention contains (D) an inorganic filler. By blending an inorganic filler into the photosensitive resin composition, it is possible to improve the physical strength of the cured product of the photosensitive resin composition, i.e., the solder resist layer. Furthermore, from the viewpoint of improving the physical strength of the solder resist layer, the photosensitive resin composition according to the present invention contains (D) an inorganic filler in a proportion of 50 to 90 mass % based on the total solid content of the photosensitive resin composition. A more preferred blend proportion is 60 to 90 mass %.

[0049] Furthermore, from the viewpoints of resolution, deep curing, releasability, residue, etc., the inorganic filler (D) used has an average particle size (D50) of 0.1 to 1.0 μm. Inorganic fillers with a D50 of less than 0.1 μm may remain on the pretreated copper-plated sheet after development. Furthermore, the photosensitive resin composition may thicken, resulting in poor coatability. On the other hand, inorganic fillers with a D50 of more than 1.0 μm may deteriorate resolution and deep curing. Furthermore, when the photosensitive resin composition is applied to a substrate to form a cured product, adhesion to the substrate may deteriorate. The preferred average particle size of the inorganic filler is 0.4 to 0.8 μm. The average particle size refers to the particle size at 50% cumulative volume obtained using a laser diffraction / scattering particle size distribution measurement method. The average particle size of silica refers to the value measured as described above for silica before preparing (pre-stirring, kneading) the photosensitive resin composition.

[0050] (D) The inorganic filler may be any conventionally known inorganic filler, such as silica, talc, mica, aluminum oxide, calcium oxide, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, fly ash, dewatered sludge, kaolin, clay, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, potassium titanate, magnesium sulfate, calcium sulfate, magnesium phosphate, sepiolite, zonolite, boron nitride, aluminum borate, silica balloons, glass flakes, glass balloons, steelmaking slag, copper, iron, iron oxide, sendust, alnico magnets, various ferrites and other magnetic powders, cement, glass powder, Neuburg silica, diatomaceous earth, antimony trioxide, magnesium oxysulfate, aluminum hydrate, hydrated gypsum, alum, and barium sulfate. These inorganic fillers may be used alone or in combination of two or more. Among the above, silica can be preferably used from the viewpoint of being able to reduce the thermal expansion coefficient of the cured product of the photosensitive resin composition.

[0051] When silica is used as inorganic filler, from the viewpoint of dispersibility etc., it is preferable that it is surface-treated with silane coupling agent etc. In this case, it is preferable that it is surface-treated with two kinds of silane coupling agents, namely, a silane coupling agent that does not have a reactive functional group and a silane coupling agent that has at least one reactive functional group selected from the group consisting of vinyl group, (meth)acryloyl group and styryl group.In this way, by using silica that is surface-treated with two kinds of silane coupling agents, namely, a silane coupling agent that does not have a reactive functional group and a silane coupling agent that has a specific reactive functional group, it can suppress the deterioration of coating film properties such as elastic modulus, and can also be made into a photosensitive resin composition that is excellent in storage stability.

[0052] Examples of silane coupling agents having no reactive functional group include compounds containing Si element and having an alkoxysilyl group or a silanol group, such as methyltrimethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-pentyltrimethoxysilane, cyclopentyltrimethoxysilane, n-hexyltrimethoxysilane, cyclohexyltrimethoxysilane, n-octyltrimethoxysilane, isooctyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, n-tetradecyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, and vinyltrimethoxysilane. , allyltrimethoxysilane, 7-octenyltrimethoxysilane, phenyltrimethoxysilane, benzyltrimethoxysilane, 1-naphthyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, n-propyltriethoxysilane, isopropyltriethoxysilane, n-butyltriethoxysilane, isobutyltriethoxysilane, n-pentyltriethoxysilane, cyclopentyltriethoxysilane, n-hexyltriethoxysilane, cyclohexyltriethoxysilane, n-octyltriethoxysilane, isooctyltriethoxysilane, n-decyltriethoxysilane, n-dodecyltriethoxysilane, n-tetradecyltriethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltriethoxysilane, and the like. These silane coupling agents having no reactive functional groups may be used alone or in combination of two or more. Among these, methyltrimethoxysilane and ethyltrimethoxysilane are preferably used.

[0053] Examples of the silane coupling agent having a reactive functional group include a vinyl group-containing silane coupling agent, a (meth)acryloyl group-containing silane coupling agent, and a styryl group-containing silane coupling agent. These may be used alone or in combination of two or more.

[0054] Examples of vinyl group-containing silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltris(2-methoxyethoxy)silane, vinylmethyldimethoxysilane, octenyltrimethoxysilane, and allyltrimethoxysilane.

[0055] Furthermore, examples of the (meth)acryloyl group-containing silane coupling agent include 1,3-bis(acryloyloxymethyl)-1,1,3,3-tetramethyldisilazane, 1,3-bis(methacryloyloxymethyl)-1,1,3,3-tetramethyldisilazane, 1,3-bis(γ-acryloyloxypropyl)-1,1,3,3-tetramethyldisilazane, 1,3-bis(γ-methacryloyloxypropyl)-1,1,3,3-tetramethyldisilazane, acryloyloxymethylmethyltrisilazane, methacryloyloxymethylmethyltrisilazane, acryloyloxymethylmethyltetrasilazane, and methacryloyloxymethylmethyltetrasilazane. Examples thereof include acryloyloxymethylmethylpolysilazane, methacryloyloxymethylmethylpolysilazane, 3-acryloyloxypropylmethyltrisilazane, 3-methacryloyloxypropylmethyltrisilazane, 3-acryloyloxypropylmethyltetrasilazane, 3-methacryloyloxypropylmethyltetrasilazane, 3-acryloyloxypropylmethylpolysilazane, 3-methacryloyloxypropylmethylpolysilazane, acryloyloxymethylpolysilazane, methacryloyloxymethylpolysilazane, 3-acryloyloxypropylpolysilazane, and 3-methacryloyloxypropylpolysilazane.

[0056] Furthermore, examples of styryl group-containing silane coupling agents include p-styryltrimethoxysilane.

[0057] Among the above-mentioned silane coupling agents having a reactive functional group, a silane coupling agent containing a (meth)acryloyl group can be used, and for example, methacryloxypropyltrimethoxysilane can be suitably used.

[0058] The surface treatment of silica is preferably carried out by adding 0.5 to 10 parts by mass of a silane coupling agent per 100 parts by mass of silica, more preferably 0.5 to 2.0 parts by mass. The surface treatment of silica can be carried out by preparing a dispersion of silica in an appropriate solvent, adding a predetermined amount of a silane coupling agent to the silica dispersion, and stirring. To promote the surface treatment reaction, stirring may be carried out in a heated environment at a temperature of 50 to 100°C.

[0059] It is preferable that the amount of silane coupling agent coated on the silica surface, which is the silane coupling agent having the reactive functional group, is greater than the amount of silane coupling agent not having the reactive functional group. Silanes having the above-mentioned coating ratio can be obtained, for example, by adjusting the blending amounts of the silane coupling agent and the silane coupling agent not having the reactive functional group when adding them to a silica dispersion, thereby surface treating the silica so that the amount of silane coupling agent having the reactive functional group is greater than the amount of silane coupling agent not having the reactive functional group. In particular, silica in which the ratio of the amount coated with the silane coupling agent having the reactive functional group to the amount coated with the silane coupling agent not having the reactive functional group is 2:1 to 10:1 by mass is preferable. Silica having such a coating ratio can be obtained, for example, by surface treating silica with a silane coupling agent containing a silane coupling agent having a reactive functional group and a silane coupling agent not having the reactive functional group in a mass ratio of 2:1 to 10:1. The presence or absence of surface treatment can be confirmed by quantifying the free, unreacted coupling agent in the silica slurry using LC-MS. The added silane coupling agent covers approximately 60 to 90% of the surface. Furthermore, compared to adding silica and a silane coupling agent separately, using surface-treated silica provides a greater effect.

[0060] The silica to be surface-treated may be any known silica without any limitation, and may be either amorphous or crystalline, or a mixture of these. Amorphous (fused) silica is particularly preferred.

[0061] <(E) Photopolymerizable Monomer> The photosensitive resin composition of the present invention contains (E) a photopolymerizable monomer. The photopolymerizable monomer is a monomer having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include commonly known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, and epoxy (meth)acrylates. Specific examples include alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or diacrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; and various alkyl acrylates such as hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and trishydroxyethyl isocyanurate. The photopolymerizable monomer may be selected from the following: polyhydric acrylates derived from hydroxyl alcohols or their alkylene oxide adducts or ε-caprolactone adducts; polyhydric acrylates such as phenols such as phenoxy acrylate and bisphenol A diacrylate or their alkylene oxide adducts; acrylates derived from glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, without limitation, acrylates and melamine acrylates obtained by directly acridating polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols or by urethane acrylates via diisocyanates, and at least one of the methacrylates corresponding to the above acrylates. Such photopolymerizable monomers can also be used as reactive diluents.

[0062] The (E) photopolymerizable monomer can be used alone or in combination of two or more. The amount of the photopolymerizable monomer is preferably 0.5 to 30 parts by mass, calculated as solid content, per 100 parts by mass of the (A) alkali-soluble resin. When the amount is 0.5 parts by mass or more, the photocurability is good, and pattern formation is easy in alkaline development after irradiation with active energy rays. Furthermore, when the amount is 30 parts by mass or less, halation is less likely to occur and good resolution can be obtained.

[0063] <(F) Thermosetting Component> The photosensitive resin composition of the present invention may contain (F) a thermosetting component in addition to the components described above. Examples of the thermosetting component include known and commonly used components such as isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy compounds, oxetane compounds, and episulfide resins. Among these, the preferred thermosetting component is an epoxy resin.

[0064] Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, and triphenylmethane type epoxy resins. These may be used alone or in combination of two or more.

[0065] Examples of commercially available epoxy resins include jER 828, 806, 807, YX8000, YX8034, and 834 manufactured by Mitsubishi Chemical Corporation; YD-128, YDF-170, ZX-1059, and ST-3000 manufactured by Nippon Steel Chemical & Material Co., Ltd.; EPICLON 830, 835, 840, 850, N-730A, and N-695 manufactured by DIC Corporation; and RE-306 manufactured by Nippon Kayaku Co., Ltd.

[0066] The epoxy group equivalent of the epoxy resin in the photosensitive resin composition is preferably 0.5 to 2.5 in terms of solid content relative to 1 equivalent of the carboxyl group of the carboxyl group-containing resin. By setting the amount to 0.5 equivalents or more, it is possible to prevent carboxyl groups from remaining in the cured product, thereby achieving good heat resistance, alkali resistance, electrical insulation, etc. Furthermore, by setting the blending amount to 2.5 equivalents or less, it is possible to prevent low-molecular-weight cyclic (thio)ether groups from remaining in the dried coating film, thereby ensuring good strength, etc. of the cured product.

[0067] When the photosensitive resin composition of the present invention contains a thermosetting component, it may contain a thermosetting catalyst for accelerating the curing of the thermosetting component. Examples of the thermosetting catalyst include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; and phosphorus compounds such as triphenylphosphine. Commercially available compounds include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all of which are trade names of imidazole-based compounds) manufactured by Shikoku Chemicals Corporation, and U-CAT 3513N (a trade name of a dimethylamine-based compound), DBU, DBN, and U-CAT SA 102 (all of which are bicyclic amidine compounds and salts thereof) manufactured by San-Apro Co., Ltd.

[0068] The compounds are not limited to those listed above, and any heat curing catalyst for epoxy resins or oxetane compounds, or any compound that promotes the reaction between at least one of an epoxy group and an oxetanyl group and a carboxyl group, may be used alone or in combination of two or more. Also usable are S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine-isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine-isocyanuric acid adduct. These compounds that also function as adhesion promoters are preferably used in combination with the heat curing catalyst.

[0069] The thermosetting catalyst may be used alone or in combination of two or more. From the viewpoint of the storage stability of the resin composition and the heat resistance of the cured coating (i.e., the coating made of the cured product), the amount of the thermosetting catalyst is preferably 0.01 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, calculated as solid content per 100 parts by mass of the alkali-soluble resin (A).

[0070] <Other Components> In addition to the components described above, the photosensitive resin composition according to the present invention may contain, as necessary, components such as colorants, elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, at least one of silicone-based, fluorine-based, and polymer-based antifoaming agents and leveling agents, and flame retardants such as phosphorus compounds such as phosphinates, phosphate ester derivatives, and phosphazene compounds. These may be compounds known in the field of electronic materials.

[0071] The photosensitive resin composition of the present invention may contain an organic solvent from the viewpoint of ease of preparation and coating properties. 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 cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used alone or in combination of two or more.

[0072] The amount of the organic solvent in the photosensitive resin composition can be appropriately changed depending on the materials constituting the photosensitive resin composition.

[0073] The photosensitive resin composition of the present invention may be used in the form of a dry film or in the form of a liquid. When used in the form of a liquid, the composition may be one-component or two or more-component.

[0074] <Dry Film> The photosensitive resin composition of the present invention can also be in the form of a dry film comprising a first film and a resin layer made of the photosensitive resin composition formed on the first film. The first film in the dry film of the present invention refers to a film that is adhered to at least the resin layer when the dry film is integrally formed by laminating the dry film onto a substrate or other base material by heating or the like so that the resin layer made of the photosensitive resin composition formed on the dry film is in contact with the first film. The first film may be peeled from the resin layer in a step after lamination. In particular, in the present invention, it is preferable to peel the first film from the resin layer in a step after exposure.

[0075] To prepare a dry film, the photosensitive resin composition of the present invention is diluted with an organic solvent to adjust the viscosity to an appropriate level, and then coated onto a first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like, and dried for 1 to 30 minutes at a temperature of 50 to 130° C. to obtain a film. There are no particular restrictions on the thickness of the coated film, but the thickness after drying is generally selected appropriately from the range of 1 to 150 μm, preferably 5 to 60 μm.

[0076] The first film can be any known film without particular limitation, and examples of suitable films include polyester films such as polyethylene terephthalate and polyethylene naphthalate, and films made of thermoplastic resins such as polyimide films, polyamideimide films, polypropylene films, and polystyrene films. Among these, polyester films are preferred from the viewpoints of heat resistance, mechanical strength, ease of handling, etc. A laminate of these films can also be used as the first film.

[0077] From the viewpoint of improving mechanical strength, the thermoplastic resin film as described above is preferably a film stretched in a uniaxial or biaxial direction.

[0078] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0079] After forming a resin layer of the photosensitive resin composition of the present invention on the first film, it is preferable to further laminate a peelable second film on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer, etc. The second film in the dry film of the present invention refers to a film that is peeled from the resin layer before lamination when the dry film is integrally molded by laminating it by heating or the like so that the resin layer side of the dry film is in contact with a base material such as a substrate.

[0080] The second film that can be peeled off from the resin layer may be, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, or surface-treated paper, as long as the adhesive strength between the resin layer and the second film is smaller than the adhesive strength between the resin layer and the first film when the second film is peeled off.

[0081] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0082] <Cured Product> The cured product of the present invention is obtained by curing the above-described photosensitive resin composition or the resin layer of the above-described dry film.

[0083] <Printed Wiring Board> The printed wiring board of the present invention has a cured product obtained from the photosensitive resin composition of the present invention or a resin layer of a dry film. A method for producing a printed wiring board of the present invention includes, for example, adjusting the viscosity of the photosensitive resin composition of the present invention using the organic solvent described above to a level suitable for the coating method, applying the composition to a substrate by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating, and then evaporating and drying (pre-drying) the organic solvent contained in the composition at a temperature of 60 to 100°C to form a tack-free resin layer. In the case of a dry film, the resin layer is formed on the substrate by laminating it onto the substrate using a laminator or the like so that the resin layer contacts the substrate.

[0084] Examples of the substrate include printed wiring boards and flexible printed wiring boards on which circuits have been formed in advance using copper or the like, as well as copper-clad laminates for high-frequency circuits made of materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, and the like, including copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc.

[0085] When the film is in the form of a dry film, it is preferable to apply pressure and heat to the substrate using a vacuum laminator or the like. By using such a vacuum laminator, even if a circuit-formed substrate is used, the dry film adheres tightly to the circuit substrate, even if the circuit substrate surface is uneven, preventing the inclusion of air bubbles and improving the filling of recesses in the substrate surface. The pressure condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 120°C.

[0086] When the photosensitive resin composition of the present invention contains an organic solvent, it is preferable to apply the photosensitive resin composition to the surface of a substrate and then subject it to volatilization drying, which can be performed using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like (a method in which hot air in a dryer equipped with a heat source of an air heating method using steam is brought into countercurrent contact with the substrate, or a method in which hot air is blown onto the substrate from a nozzle).

[0087] After forming a resin layer on a substrate, the resin layer is selectively exposed to active energy rays through a photomask with a predetermined pattern, and the unexposed areas are developed with a dilute alkaline aqueous solution (e.g., a 0.3 to 3% by weight aqueous solution of sodium carbonate) to form a cured product pattern. In the case of a dry film, after exposure, the first film is peeled off from the dry film and development is carried out, thereby forming a patterned cured product on the substrate. In the case of a dry film, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed, as long as the properties are not impaired. Furthermore, a cured coating with excellent properties such as adhesion and hardness can be formed by irradiating the cured product with active energy rays and then heat-curing (e.g., 100 to 220°C), or by irradiating active energy rays after heat-curing, or by heat-curing alone to perform final finish curing (main curing).

[0088] The exposure device used for the active energy ray irradiation may be any device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, or the like, and capable of irradiating ultraviolet rays in the range of 350 to 450 nm. Furthermore, a direct imaging device (for example, a laser direct imaging device that draws an image directly with a laser based on CAD data from a computer) may also be used. The lamp or laser light source of the direct imaging device may have a maximum wavelength in the range of 350 to 450 nm. The exposure dose for image formation varies depending on factors such as the film thickness, but is generally 10 to 1,000 mJ / cm. ２ , preferably 20 to 800 mJ / cm ２ The range may be:

[0089] The developing method may be a dipping method, a shower method, a spray method, a brush method, or the like, and the developing solution may be an aqueous alkali solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, or an amine.

[0090] After forming the cured coating on the substrate as described above, components such as electronic elements are mounted on the substrate by solder reflow processing. The solder reflow processing can be performed by a conventionally known method. Furthermore, solder reflow is typically performed under processing conditions such as 245 to 260°C for 5 to 10 seconds.

[0091] The photosensitive resin composition or dry film of the present invention is preferably used for producing electronic components such as printed wiring boards, and more preferably for forming a permanent coating. In this case, the photosensitive resin composition or dry film of the present invention is used to form a cured product by the method described above or the like. When the resin layer of the photosensitive resin composition or dry film of the present invention is insulating, it is preferably used to form a solder resist, coverlay, or interlayer insulating layer. In particular, it is suitable for use in forming permanent coatings such as solder resists used on package substrates. The photosensitive resin composition of the present invention may also be used to form solder dams.

[0092] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all by mass unless otherwise specified.

[0093] Synthesis Example 1 (Synthesis of Alkali-Soluble Resin A) 119.4 parts by mass of a novolac cresol resin (trade name "Shounol CRG951", manufactured by Aica Kogyo Co., Ltd., OH equivalent: 119.4), 1.19 parts by mass of potassium hydroxide, and 119.4 parts by mass of toluene were introduced into an autoclave equipped with a thermometer, a nitrogen introducing device, an alkylene oxide introducing device, and a stirrer, and the system was purged with nitrogen while stirring, and the temperature was raised. Next, 63.8 parts by mass of propylene oxide was gradually added dropwise, and the mixture was stirred at 125 to 132°C and 0 to 4.8 kg / cm. ２The mixture was reacted at 100°C for 16 hours. The mixture was then cooled to room temperature, and 1.56 parts by mass of 89% phosphoric acid was added to the reaction solution, followed by mixing to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac cresol resin [solids content: 62.1%; hydroxyl value: 182.2 mg KOH / g (307.9 g / eq.)]. This propylene oxide reaction solution contained an average of 1.08 moles of propylene oxide added per equivalent of phenolic hydroxyl group. 293.0 parts by mass of the resulting propylene oxide reaction solution of novolac cresol resin, 43.2 parts by mass of acrylic acid, 11.53 parts by mass of methanesulfonic acid, 0.18 parts by mass of methylhydroquinone, and 252.9 parts by mass of toluene were introduced into a reactor equipped with a stirrer, thermometer, and air inlet tube. Air was blown in at a rate of 10 ml / min, and the mixture was reacted at 110°C for 12 hours with stirring. 12.6 parts by mass of water produced by the reaction was distilled off as an azeotropic mixture with toluene. The mixture was then cooled to room temperature, neutralized with 35.35 parts by mass of 15% aqueous sodium hydroxide, and then washed with water. The toluene was then replaced with 118.1 parts by mass of propylene glycol monomethyl ether acetate (PMA) using an evaporator, and the mixture was distilled off to obtain a novolac acrylate resin solution. Next, 332.5 parts by mass of the resulting novolac acrylate resin solution and 1.22 parts by mass of triphenylphosphine were introduced into a reactor equipped with a stirrer, thermometer, and air inlet tube. Air was blown in at a rate of 10 ml / min. While stirring, 60.8 parts by mass of tetrahydrophthalic anhydride was gradually added. The mixture was allowed to react at 95 to 101°C for 6 hours, cooled, and then removed. In this way, a solution of alkali-soluble resin A (solid content: 65% by mass, acid value of solid content: 87.7 mgKOH / g) was obtained.

[0094] <Preparation of Inorganic Filler> [Silica 1] A preliminary dispersion was prepared by adding 70 g of spherical silica (Admafine SO-C2, manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) to 30 g of propylene glycol monomethyl ether acetate (PMA) as a solvent and stirring. Next, 0.8 g of methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.1 g of methyltrimethoxysilane (KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this preliminary dispersion and stirred at 50°C, thereby obtaining a silica slurry (solid content of silica 70% by mass) surface-treated with two types of silane coupling agents.

[0095] [Silica 2] A preliminary dispersion was prepared by adding 70 g of spherical silica (Admafine SO-C1, manufactured by Admatechs Co., Ltd., average particle size 0.3 μm) to 30 g of propylene glycol monomethyl ether acetate (PMA) as a solvent and stirring. Next, 0.8 g of methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.1 g of methyltrimethoxysilane (KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this preliminary dispersion and stirred at 50°C, thereby obtaining a silica slurry (solid content of silica 70% by mass) surface-treated with two types of silane coupling agents.

[0096] [Silica 3] A preliminary dispersion was prepared by adding 70 g of spherical silica (Admafine SO-C4, manufactured by Admatechs Co., Ltd., average particle size 1.2 μm) to 30 g of propylene glycol monomethyl ether acetate (PMA) as a solvent and stirring. Next, 0.8 g of methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.1 g of methyltrimethoxysilane (KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this preliminary dispersion and stirred at 50°C, thereby obtaining a silica slurry (solid content of silica 70% by mass) surface-treated with two types of silane coupling agents.

[0097] [Silica 4] A preliminary dispersion was prepared by adding 70 g of spherical silica (Admanano YA050C, manufactured by Admatechs Co., Ltd., average particle size 0.05 μm) to 30 g of propylene glycol monomethyl ether acetate (PMA) as a solvent and stirring. Next, 0.8 g of methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.1 g of methyltrimethoxysilane (KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this preliminary dispersion and stirred at 50°C to obtain a silica slurry (solid content of silica 70% by mass) surface-treated with two types of silane coupling agents.

[0098] <Preparation of Photosensitive Resin Compositions> The components shown in Table 1 below were blended and mixed at room temperature using a three-roll mill to obtain the photosensitive resin compositions shown in the table. Each value in the table indicates parts by mass (mass including solvent).

[0099] The components *1 to *6 in Table 1 below are as follows: *1: Acylphosphine oxide photopolymerization initiator (2,4,6-trimethylbenzoyldiphenylphosphine oxide) *2: Titanocene photopolymerization initiator (manufactured by Yueyang Jinmaotai Technology Co., Ltd.) *3: Anthracene sensitizer (manufactured by Air Performance Chemical Co., Ltd.) *4: Anthracene sensitizer (manufactured by Air Performance Chemical Co., Ltd.) *5: Dipentaerythritol hexaacrylate *6: Bisphenol A epoxy resin (solvent-free product manufactured by DIC Corporation, solid content: 85% by mass) *7: Blue pigment and yellow pigment *8: Propylene glycol monomethyl ether acetate (PMA)

[0100] <Evaluation of Resolution> Each photosensitive resin composition obtained as described above was applied to the surface of a polyethylene terephthalate film (T-60, manufactured by Toray Industries, Inc., thickness 38 μm) using an applicator and dried at 80°C for 20 minutes to produce a dry film with a resin layer thickness of 25 μm. Subsequently, a resin layer was formed on the substrate by laminating the dry film to a BT substrate using a vacuum laminator (CVP-600, manufactured by Nikko Materials Co., Ltd.). Thereafter, the resin layer side of the substrate was subjected to pattern exposure with a line and space (L / S) of 100 μm / 100 μm at an optimal exposure dose using a DI exposure device (manufactured by Oak Manufacturing Co., Ltd.) equipped with a high-pressure mercury lamp. Here, the optimal exposure dose was determined by exposing the resin layer obtained above using a DI exposure device through a step tablet with 21 steps of sensitivity, and then exposing the resin layer to 1% by mass NaCl at a liquid temperature of 30°C. ２ CO ３ The exposure amount was set to such that when development was carried out for 60 seconds under the condition of a spray pressure of 0.2 MPa using an aqueous solution, the remaining step tablet pattern would have 9 steps. ２ CO ３ The coating was developed using an aqueous solution, washed with water, and then cured at 170°C for 60 minutes to prepare a sample for evaluation.

[0101] The evaluation sample was sealed with a cold-mounting resin (105NSP, manufactured by Struers Corporation), cured, and then cut. The cross section was observed under an electron microscope (×1000 magnification). Figure 1 is a schematic diagram of the cross section. In the cross-sectional observation of the cured coating, the widest part was marked with W. Ｍａｘ (μm), the narrowest part is W ＭＩＮ The resolution was evaluated based on the difference in the resolution (μm) and the following criteria: ＭＡＸ -W Ｍｉｎ The difference is less than 10 μm. ＭＡＸ -W Ｍｉｎ The difference is 10 μm or more and less than 16 μm ×: W ＭＡＸ -W Ｍｉｎ The evaluation results are shown in Table 1 below.

[0102] <Gloss Sensitivity> In <Evaluation of Resolution>, a copper-plated plate pretreated with CZ-8100 manufactured by MEC Co., Ltd. was used, and the exposure dose was 200 mJ / cm ２ An evaluation sample was prepared in the same manner as above, except that the following was used. The sensitivity was evaluated according to the following evaluation criteria: ○: 7 or more steps △: Less than 7 steps ×: Unable to form The evaluation results are shown in Table 1 below.

[0103] <Margin> In <Evaluation of Resolution>, evaluation samples were prepared in the same manner as above, except that a copper-plated plate pretreated using MEC Co., Ltd.'s CZ-8100 was used, and pattern exposure was performed with an aperture diameter of 200 μm, with the focal point shifted by +60 μm from the substrate surface during exposure. The obtained evaluation samples were observed with an optical microscope (×500x), and the top diameter of the aperture diameter was measured. ○: The difference in aperture diameter was less than 1 μm from the design value (200 μm). ×: The difference in aperture diameter was 1 μm or more from the design value (200 μm), or formation was not possible. The evaluation results are shown in Table 1 below.

[0104] <Adhesion> In <Evaluation of resolution>, evaluation samples were obtained in the same manner as above, except that the exposure pattern was a 40 μm / 100 μm line and space (L / S) pattern. Tape peeling was performed twice with cellophane tape, and the cured coating remaining on the substrate side was observed under an optical microscope (×30 magnification) to evaluate adhesion according to the following evaluation criteria: ○: Not a single line peeled off ×: A single line peeled off in part or in whole, or no line could be formed The evaluation results are shown in Table 1 below.

[0105] <Evaluation of Coating Properties (Elastic Modulus)> An 8 cm long and 1 cm wide piece of cured coating was peeled from an evaluation sample obtained in the same manner as in <Evaluation of Resolution>, except that copper foil was used as the substrate. The peeled cured coating was subjected to an autograph (AG-X, manufactured by Shimadzu Corporation) to measure the elastic modulus at room temperature. The evaluation criteria were as follows: ◯: Elastic modulus of 6 GPa or more ×: Elastic modulus less than 6 GPa The evaluation results are shown in Table 1 below.

[0106] <Confirmation of Residues> In <Evaluation of Resolution>, except that a copper-plated sheet pretreated with CZ-8100 manufactured by MEC Co., Ltd. was used, the copper surface of an opening diameter of 200 μm of an evaluation sample obtained in the same manner as above was observed with an electron microscope (×5000 magnification), and the number of fillers that could be confirmed was counted. The evaluation criteria were as follows: ○: Less than 10 particles ×: 10 particles or more The evaluation results are shown in Table 1 below.

[0107]

Claims

1. A photosensitive resin composition comprising at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a sensitizer, (D) an inorganic filler, and (E) a photopolymerizable monomer, wherein the (B) photopolymerization initiator comprises an acylphosphine oxide-based photopolymerization initiator and a titanocene-based photopolymerization initiator, the (C) sensitizer comprises an anthracene-based sensitizer, the (D) inorganic filler is contained in a proportion of 50 to 90 mass% based on the total solid content in the photosensitive resin composition, and the (D) inorganic filler has an average particle size (D50) of 0.1 to 1.0 μm.

2. The photosensitive resin composition according to claim 1, wherein the acylphosphine oxide photopolymerization initiator and the titanocene photopolymerization initiator are contained in a ratio of 10:1 to 90:1 on a mass basis.

3. The photosensitive resin composition according to claim 1, wherein the sensitizer (C) is contained in an amount of 2 to 18% by mass relative to the photopolymerization initiator (B).

4. The photosensitive resin composition according to claim 1, wherein the inorganic filler (D) comprises silica.

5. The photosensitive resin composition according to claim 1, further comprising (F) a thermosetting component.

6. A dry film comprising a first film and a resin layer formed by applying the photosensitive resin composition according to claim 1 onto one surface of the first film and drying it.

7. A cured product obtained by curing the photosensitive resin composition according to any one of claims 1 to 5 or the resin layer of the dry film according to claim 6.

8. A printed wiring board provided with a coating made of the cured product according to claim 7.

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