JP7582379B2 - Photosensitive resin composition, and photosensitive film, resist pattern forming method, and printed wiring board using the same - Google Patents

Description

The present invention relates to an alkaline-developable photosensitive resin composition for protective films on printed wiring boards, and more specifically to a photosensitive resin composition for protective films on printed wiring boards used as a permanent mask resist in the field of resists for semiconductor package substrates, as well as a photosensitive film, a method for forming a resist pattern, and a printed wiring board using the same.

In the field of printed wiring boards, a permanent mask resist (protective film) has been formed on a printed wiring board. The mainstream method for forming a pattern using a photosensitive resist is photolithography, in which a colored photosensitive resin composition is applied to a substrate, dried, and then selectively irradiated with ultraviolet light to harden the composition, and then only the unhardened parts are developed and removed with an alkaline solution to form a pattern. This permanent mask resist prevents solder from adhering to unnecessary parts of the conductor layer of the printed wiring board, for example, in the process of flip-chip mounting a semiconductor element on a printed wiring board via solder. Furthermore, the permanent mask resist also prevents corrosion of the conductor layer and maintains electrical reliability between the conductor layers when the printed wiring board is in use.

Traditionally, permanent mask resists in printed wiring board manufacturing have been produced by screen printing or roll coating a thermosetting or photosensitive resin composition.

For example, in flexible wiring boards using mounting methods such as FC, TAB, and COF, except for the rigid wiring board, IC chip, electronic components, or LCD panel and the connection wiring pattern portion, a thermosetting resin paste is screen printed and thermally cured to form a permanent mask resist (see, for example, Patent Document 1).

In recent years, with the increasing density of wiring patterns, permanent mask resists are required to have high resolution, and photosensitive resin compositions that form patterns using a photographic method are being used extensively. Among them, alkaline development types that can be developed with a weak alkaline aqueous solution such as a sodium carbonate aqueous solution are becoming mainstream from the viewpoint of preserving the working environment and the global environment. In addition, with the trend toward miniaturization and high performance of electronic devices, there is a remarkable tendency for semiconductor chips to have narrower pitches for wiring and therefore higher density. As a semiconductor mounting method that corresponds to this, the flip chip connection method in which a semiconductor chip and a substrate are joined by solder bumps has become mainstream. This flip chip connection method is a semiconductor mounting method using a reflow method in which solder balls are placed between the substrate and the semiconductor chip and the entire substrate is heated to melt and join them. Therefore, during solder reflow, the substrate itself is exposed to a high temperature environment, and the thermal contraction of the substrate generates large stress in the solder balls that connect the substrate and the semiconductor, which can cause poor connection of the wiring and cracks in the permanent mask resist and underfill. For this reason, insulating materials used in printed wiring boards are required to have a low thermal expansion coefficient.

As wiring patterns and insulating patterns (permanent mask resists) in printed wiring boards become increasingly fine, the pitch between wiring lines becomes finer, and this requires excellent electrical reliability between wiring lines (especially electrical reliability after moisture absorption (HAST (High Accelerated Stress Test) resistance)).
In the manufacture of the mask resist, electroless plating, which does not require lead wires, has been adopted (see, for example, Patent Document 2). The electroless plating method has features such as uniform plating thickness and high smoothness. However, the plating solution has a high pH and is strongly alkaline, and the solution temperature is raised to a high temperature of about 90° C. in order to improve the plating deposition rate, so that the damage to the permanent mask resist tends to be large. Therefore, the permanent mask resist is required to be resistant to damage caused by the plating solution used in the electroless plating and to have further improved resistance to electroless plating.

In addition, increasing the amount of inorganic filler to reduce the thermal expansion coefficient tends to result in the phenomenon of filler remaining after alkaline development. The occurrence of this filler residue leads to insufficient electrical connection and reduced electrical reliability, so there is a need to improve the filler residue.

JP 2003-198105 A JP 2006-190848 A

The present invention provides a photosensitive resin composition that has excellent heat resistance and a low coefficient of thermal expansion, and also achieves good resolution, electrical reliability (HAST resistance), and filler developability, as well as a photosensitive film, a method for forming a resist pattern, and a printed wiring board that use the same.

After extensive research into solder resist properties and compositions that can satisfy these high heat resistance, low thermal expansion coefficient, good electrical reliability (HAST resistance), good filler developability, and elimination of filler residue, the inventors discovered that a photosensitive resin composition containing (A) an acid-modified vinyl group-containing epoxy resin, (B) a photopolymerizable monomer having an ethylenically unsaturated bond, (C) a photopolymerization initiator, and (D) an inorganic filler can be used, and that the acid-modified vinyl group-containing epoxy resin of component (A) is a specific highly heat-resistant compound, and that the resin has a polydispersity expressed as Mw/Mn of 2.0 to 5.0, and that the inorganic filler is contained in an amount of 30 to 70 mass %, thereby achieving both heat resistance, electrical reliability, and filler developability (elimination of filler residue) without deteriorating the linear thermal expansion coefficient.

The photosensitive resin composition of the present invention is a photosensitive resin composition comprising [1] (A) an acid-modified vinyl group-containing epoxy resin, (B) a photopolymerizable monomer having an ethylenically unsaturated bond, (C) a photopolymerization initiator, and (D) an inorganic filler, characterized in that the acid-modified vinyl group-containing epoxy resin of component (A) contains a compound represented by general formula (1) or general formula (2) (wherein the polydispersity represented by Mw/Mn (weight average molecular weight/number average molecular weight) is 2.0 to 5.0), and the content of the inorganic filler (D) is 30 to 70 mass% based on the total solid content.

[In general formula (1), R ¹¹ represents a hydrogen atom or a methyl group, Y ¹ represents a hydrogen atom or a glycidyl group, and n1 represents an integer of 1 or more. Note that multiple R ^11s and multiple Y ^1s may be the same or different. However, at least one Y ¹ represents a glycidyl group. In general formula (2), R ¹² represents a hydrogen atom or a methyl group, and Y ^2s each independently represent a hydrogen atom or a glycidyl group. Note that two R ^12s may be the same or different. However, at least one of Y ^2s represents a glycidyl group.]

The photosensitive resin composition of the present invention is also the photosensitive resin composition according to the above item [1], in which the photopolymerizable monomer having an ethylenically unsaturated bond (B) is a polyfunctional photopolymerizable monomer having three or more ethylenically unsaturated bonds in one molecule.
The photosensitive resin composition of the present invention is the photosensitive resin composition according to the above item [1] or [2], further comprising [3] (E) a pigment.

The photosensitive film of the present invention includes a support [4] and a photosensitive layer formed from the photosensitive resin composition according to any one of the above [1] to [3].
Further, a method for forming a resist pattern of the present invention includes the steps of: laminating a photosensitive layer on a laminate substrate including an insulating substrate and a conductor layer having a circuit pattern formed on the insulating substrate, using the photosensitive resin composition described in any one of the above [1] to [3] so as to cover the conductor layer; irradiating a predetermined portion of the photosensitive layer with active light to form an exposed portion; and then removing a portion of the photosensitive layer other than the exposed portion.
The printed wiring board of the present invention includes an insulating substrate, a conductor layer having a circuit pattern formed on the insulating substrate, and a permanent resist layer formed using the photosensitive resin composition according to any one of the above items [1] to [3] so as to cover the conductor layer.

The present invention provides a photosensitive resin composition for protective films on printed wiring boards that can achieve high heat resistance, resolution, electrical reliability (HAST resistance), and filler developability without deteriorating the linear thermal expansion coefficient, as well as a photosensitive film, a method for forming a resist pattern, and a printed wiring board using the same.

In the present invention, (meth)acrylic acid refers to acrylic acid or methacrylic acid, (meth)acrylate refers to an acrylate or the corresponding methacrylate, and (meth)acryloyl group refers to an acryloyl group or methacryloyl group.
Preferred embodiments of the present invention will now be described in detail.
First, a photosensitive resin composition according to a preferred embodiment will be described.

[(A) Acid-modified vinyl group-containing epoxy resin]
The acid-modified vinyl group-containing epoxy resin (A) used in the present invention (having a polydispersity represented by Mw/Mn of 2.0 to 5.0) will now be described.
The acid-modified vinyl-group-containing epoxy resin (A) used in the present invention has a dispersity represented by Mw/Mn of 2.0 to 5.0. From the viewpoints of alkali developability and excellent resolution and adhesion, it is preferable that the acid-modified vinyl-group-containing epoxy resin (A) is a resin (A″) obtained by reacting at least one epoxy resin (a) selected from the group consisting of novolac epoxy resins represented by the following general formula (1) and bisphenol novolac resins having a structural unit represented by the following general formula (2) or (3) with a vinyl-group-containing monocarboxylic acid (b), and then reacting the resulting resin (A′) with a saturated or unsaturated group-containing polybasic acid anhydride.

[In the general formula (1), R ¹¹ represents a hydrogen atom or a methyl group, Y ¹ represents a hydrogen atom or a glycidyl group, and n1 represents an integer of 1 or more. Note that a plurality of R ¹¹ and Y ¹ may be the same or different. However, at least one Y ¹ represents a glycidyl group.]

[In the general formula (2), R ¹² represents a hydrogen atom or a methyl group, and Y ² each independently represents a hydrogen atom or a glycidyl group. The two R ¹² may be the same or different. However, at least one of Y ² represents a glycidyl group.]

[In the general formula (3), R ¹³ represents a hydrogen atom or a methyl group, and Y ³ each independently represents a hydrogen atom or a glycidyl group. The two R ¹³ may be the same or different. However, at least one of Y ³ represents a glycidyl group.]

Resin (A') obtained by reacting epoxy resin (a) with vinyl-containing monocarboxylic acid (b) is presumed to have hydroxyl groups formed by addition reaction between the epoxy groups of epoxy resin (a) and the carboxyl groups of vinyl-containing monocarboxylic acid (b).

Novolac type epoxy resins represented by general formula (1) include phenol novolac type epoxy resins and cresol novolac type epoxy resins. These novolac type epoxy resins can be obtained, for example, by reacting phenol novolac resin or cresol novolac resin with epichlorohydrin by a known method.

As the epoxy resin (a), a novolac-type epoxy resin represented by general formula (1) is preferred from the viewpoint of excellent process tolerance and improved solvent resistance.

Examples of phenol novolac type epoxy resins or cresol novolac type epoxy resins represented by general formula (1) include YDCN-701, YDCN-702, YDCN-703, YDCN-704, YDCN-704L, YDPN-638, YDPN-602 (all of which are product names manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.), DEN-431, DEN-439 (all of which are product names manufactured by Huntsman Corporation), EOCN-120, EOCN-102S, EOCN-120 ... Commercially available products include N-103S, EOCN-104S, EOCN-1012, EOCN-1025, EOCN-1027, BREN (all trade names manufactured by Nippon Kayaku Co., Ltd.), EPN-1138, EPN-1235, EPN-1299 (all trade names manufactured by Huntsman Corporation), N-730, N-770, N-865, N-870, N-665, N-673, VH-4150, and VH-4240 (all trade names manufactured by DIC Corporation).

In addition, as the epoxy resin (a), it is preferable to use an epoxy resin having structural units represented by general formula (2) and/or general formula (3), from the viewpoint of further reducing the warpage of the thin film substrate and further improving the thermal shock resistance.

In the above general formula (3), those in which R ¹³ is a hydrogen atom and Y ³ is a glycidyl group are commercially available as the EXA-7376 series (trade name, manufactured by DIC Corporation), and those in which R ¹³ is a methyl group and Y ³ is a glycidyl group are commercially available as the EPON SU8 series (trade name, manufactured by the former Japan Epoxy Resins Co., Ltd.).

Examples of the vinyl group-containing monocarboxylic acid (b) include acrylic acid, acrylic acid dimers, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, α-cyanocinnamic acid, and other acrylic acid derivatives, half-ester compounds which are reaction products of hydroxyl group-containing acrylates and dibasic acid anhydrides, and half-ester compounds which are reaction products of vinyl group-containing monoglycidyl ethers or vinyl group-containing monoglycidyl esters and dibasic acid anhydrides.

The half-ester compound can be obtained by reacting a hydroxyl group-containing acrylate, a vinyl group-containing monoglycidyl ether, or a vinyl group-containing monoglycidyl ester with a dibasic acid anhydride in an equimolar ratio. These vinyl group-containing monocarboxylic acids (b) can be used alone or in combination of two or more.

Examples of the hydroxyl group-containing acrylate, vinyl group-containing monoglycidyl ether, and vinyl group-containing monoglycidyl ester used in the synthesis of the above-mentioned half-ester compound, which is an example of the vinyl group-containing monocarboxylic acid (b), include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, pentaerythritol pentamethacrylate, glycidyl acrylate, and glycidyl methacrylate.

The dibasic acid anhydride used in the synthesis of the above-mentioned half ester compound may be one containing a saturated group or one containing an unsaturated group. Specific examples of dibasic acid anhydrides include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, itaconic anhydride, etc.

In the reaction between the epoxy resin (a) and the vinyl group-containing monocarboxylic acid (b) described above, it is preferable to react in a ratio of 0.6 to 1.05 equivalents of the vinyl group-containing monocarboxylic acid (b) per 1 equivalent of the epoxy group of the epoxy resin (a), and more preferably in a ratio of 0.8 to 1.0 equivalents.

The epoxy resin (a) and the vinyl group-containing monocarboxylic acid (b) can be dissolved in an organic solvent and reacted. Examples of the organic solvent include ketones such as ethyl methyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene, glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether, esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate, aliphatic hydrocarbons such as octane and decane, and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

Furthermore, it is preferable to use a catalyst to promote the reaction. Examples of the catalyst that can be used include triethylamine, benzylmethylamine, methyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylmethylammonium iodide, and triphenylphosphine. The amount of catalyst used is preferably 0.1 to 10 parts by mass per 100 parts by mass of the epoxy resin (a) and the vinyl group-containing monocarboxylic acid (b) combined.

In addition, it is preferable to use a polymerization inhibitor to prevent polymerization during the reaction. Examples of polymerization inhibitors include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, etc. The amount of polymerization inhibitor used is preferably 0.01 to 1 part by mass per 100 parts by mass of the epoxy resin (a) and the vinyl group-containing monocarboxylic acid (b) combined. The reaction temperature is preferably 60 to 150°C, and more preferably 80 to 120°C.

If necessary, the vinyl group-containing monocarboxylic acid (b) can be used in combination with a phenolic compound such as p-hydroxyphenethyl alcohol, or a polybasic acid anhydride such as trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, or biphenyltetracarboxylic anhydride.

In addition, in the present invention, it is also preferable to use, as the acid-modified vinyl group-containing epoxy resin (A), a resin (A″) obtained by reacting the above-mentioned resin (A’) with a polybasic acid anhydride (c).

In resin (A"), it is presumed that the hydroxyl groups in resin (A') (including the hydroxyl groups originally present in epoxy resin (a)) and the acid anhydride groups in polybasic acid anhydride (c) are semi-esterified.

As the polybasic acid anhydride (c), those containing saturated groups and those containing unsaturated groups can be used. Specific examples of the polybasic acid anhydride (c) include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, and itaconic anhydride.

In the reaction between resin (A') and polybasic acid anhydride (c), the acid value of the acid-modified vinyl group-containing epoxy resin can be adjusted by reacting 0.1 to 1.0 equivalents of polybasic acid anhydride (c) with one equivalent of hydroxyl groups in resin (A').

The acid value of (A) the acid-modified vinyl group-containing epoxy resin is preferably 30 to 150 mgKOH/g, more preferably 40 to 120 mgKOH/g, and even more preferably 50 to 100 mgKOH/g. If the acid value is less than 30 mgKOH/g, the solubility of the photosensitive resin composition in a dilute alkaline solution tends to decrease, and if it exceeds 150 mgKOH/g, the electrical properties of the cured film tend to decrease.

The reaction temperature between resin (A') and polybasic acid anhydride (c) is preferably 60 to 120°C.

If necessary, for example, hydrogenated bisphenol A type epoxy resin can be used in part as the epoxy resin (a). Furthermore, as the acid-modified vinyl group-containing epoxy resin (A), a styrene-maleic acid resin such as a hydroxyethyl acrylate modified styrene-maleic anhydride copolymer or a hydroxyethyl acrylate modified styrene-maleic anhydride copolymer can be used in part as the acid-modified vinyl group-containing epoxy resin (A).

In the photosensitive resin composition, the content of component (A) is preferably 5 to 60 mass %, more preferably 10 to 50 mass %, and even more preferably 15 to 40 mass %, based on the total solid content of the photosensitive resin composition. When the content of component (A) is within the above range, a coating film with superior heat resistance, electrical properties, and chemical resistance can be obtained.

[(B) Photopolymerizable monomer having an ethylenically unsaturated bond]
As the photopolymerizable monomer (B) having an ethylenically unsaturated bond, a compound having a molecular weight of 1000 or less is preferable, and examples thereof include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate, mono- or di(meth)acrylates of glycols such as ethylene glycol, methoxytetraethylene glycol and polyethylene glycol, (meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N-methylol(meth)acrylamide, aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, Examples of the photopolymerizable monomer include polyhydric alcohols such as dipentaerythritol and tris-hydroxyethyl isocyanurate, polyhydric (meth)acrylates of their ethylene oxide or propylene oxide adducts, (meth)acrylates of ethylene oxide or propylene oxide adducts of phenols such as phenoxyethyl (meth)acrylate and polyethoxy di(meth)acrylate of bisphenol A, (meth)acrylates of glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate, as well as melamine (meth)acrylate, acrylamide, acrylonitrile, diacetone acrylamide, styrene, and vinyl toluene. These (B) photopolymerizable monomers having an ethylenically unsaturated group may be used alone or in combination of two or more. In addition, in order to increase the crosslink density by photocuring and improve the heat resistance and electrical reliability, it is more preferable that the photopolymerizable monomer has three or more ethylenically unsaturated bonds in one molecule. Examples of such compounds having an ethylenically unsaturated bond include trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO/PO-modified trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, dipentaerythritol triacrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.
Above, "EO" refers to "ethylene oxide" and "PO" refers to "propylene oxide." Additionally, "EO-modified" means having a block structure of ethylene oxide units (-CH ₂ -CH ₂ -O-), and "PO-modified" means having a block structure of propylene oxide units (-CH ₂ -CH(CH ₃ )-O-).

[(C) Photopolymerization initiator]
Examples of the photopolymerization initiator (C) include benzoins such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, and N,N-dimethylaminoacetophenone; anthraquinones such as anthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(diethylamino)benzophenone, Michler's ketone, 4-benzoyl-4'-methyl benzophenones such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer, etc. Examples of the photopolymerization initiator (C) include acridines such as 5-triarylimidazole dimers, 9-phenylacridine, and 1,7-bis(9,9'-acridinyl)heptane; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and oxime esters such as 1,2-octanedione-1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetyloxime), and 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl)oxime]. These photopolymerization initiators (C) can be used alone or in combination of two or more. In addition, Irgacure 819 (trade name, manufactured by BASF Japan Ltd., "Irgacure" is a registered trademark), which has good bottom hardening properties for photobleaching, and Irgacure 369 (trade name, manufactured by BASF Japan Ltd.), which is less likely to volatilize and therefore less likely to generate outgassing, are preferred.

Furthermore, (C) photopolymerization initiator assistants such as tertiary amines such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine, etc. can be used alone or in combination of two or more kinds.

[(D) Inorganic filler]
(D) Inorganic filler will be described. (D) Inorganic filler may be, for example, silica ( _SiO2 ), alumina ( _Al2O3 ), titania ( _TiO2 ), tantalum oxide ( _Ta2O5 ), zirconia ( _ZrO2 ), silicon nitride ( _Si3N4 ) _{, barium} titanate ( _BaO.TiO2 ), barium carbonate ( _BaCO3 ), magnesium carbonate, aluminum oxide _, aluminum hydroxide, magnesium hydroxide, lead titanate ( _PbO.TiO2 ), lead zirconate titanate (PZT) _, lead lanthanum zirconate titanate (PLZT ₎ , gallium oxide ( _Ga2O3 ), _spinel (MgO.Al2O3 _{) ,} mullite ( _3Al2O3.2SiO2 ), cordierite ( _2MgO.2Al2O3 / _{5SiO2 )} , or the like. ), talc ( _{3MgO.4SiO2.H2O} ), aluminum titanate ( _TiO2 - _Al2O3 ), yttria-containing zirconia ( _Y2O3 - _ZrO2 ), barium silicate ( _BaO.8SiO2 ), boron nitride (BN), calcium carbonate ( _CaCO3 ), barium sulfate ( _BaSO4 ), calcium sulfate ( _CaSO4 ), zinc oxide ( _ZnO ), magnesium titanate ( _MgO.TiO2 ), hydrotalcite, mica, calcined kaolin, carbon (C ₎ , etc. These (D) inorganic fillers can be used alone or in combination of two or more.

A silane coupling agent is used for the inorganic filler (D) used in the present invention in order to disperse the inorganic filler in the resin without agglomerating while maintaining the primary particle size. As the silane coupling agent, a commonly available one can be used, for example, alkylsilane, alkoxysilane, vinylsilane, epoxysilane, aminosilane, acrylicsilane, methacrylsilane, mercaptosilane, sulfidesilane, isocyanatesilane, sulfursilane, styrylsilane, alkylchlorosilane, etc. can be used. Specific compound names include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, methyltriphenoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, diisopropyldimethoxysilane, isobutyltrimethoxysilane, diisobutyldimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, n-Dodecylmethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, triphenylsilanol, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, n-Octyldimethylchlorosilane, tetraethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-phenylaminopropyltrimethoxysilane silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, bis(3-(triethoxysilyl)propyl)disulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, allyltrimethoxysilane, diallyldimethylsilane, 3-methacryloylsilane, Examples of the silane coupling agent include acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, N-(1,3-dimethylbutylidene)-3-aminopropyltriethoxysilane, aminosilane, monomethyltriisocyanatesilane, tetraisocyanatesilane, and γ-isocyanatepropyltriethoxysilane. The silane coupling agent used is preferably one that reacts with the carboxyl group of the acid-modified vinyl group-containing epoxy resin (A) contained in the photosensitive resin composition, and is preferably, for example, epoxysilane, acrylicsilane, or methacrylsilane. These silane coupling agents strengthen the bond between silica and resin, and therefore strengthen the strength of the film when used as a permanent mask resist, and contribute to crack resistance in a temperature cycle test. Mercaptosilane and isocyanatesilane may also be used. (B) It is believed to react with the ethylenically unsaturated group of the photopolymerizable monomer having an ethylenically unsaturated bond, and exert an effect similar to that achieved when the silane coupling agent is used.

In the photosensitive resin composition, the content of component (D) is 30 to 70% by mass based on the total solid content of the photosensitive resin composition from the viewpoint of resolution and low thermal expansion coefficient, but 40 to 65% by mass is preferable, and 45 to 60% by mass is more preferable. When the content of component (D) is within the above range, low thermal expansion coefficient, heat resistance, electrical reliability (HAST resistance), thermal shock resistance, resolution, film strength, etc. can be further improved. If the filling amount exceeds 70% by mass, it becomes difficult to disperse in the resin, and the flowability of the photosensitive resin composition tends to decrease. If the filling amount is less than 30% by mass, it tends to be difficult to obtain crack resistance during reflow mounting.

The average particle size of the inorganic filler (D) is preferably 0.01 to 1 μm, and from the viewpoint of practicality and resolution, it is more preferably 0.1 to 1 μm, and most preferably 0.3 to 0.7 μm. The maximum particle size of the inorganic filler (D) is preferably 0.1 to 5 μm, more preferably 0.1 to 3 μm, and even more preferably 0.1 to 1 μm. If the maximum particle size exceeds 5 μm, resolution and electrical reliability tend to be impaired.

(D) Among inorganic fillers, it is preferable to use silica fine particles from the viewpoint of improving the low expansion coefficient and heat resistance. It is also preferable to use barium sulfate fine particles from the viewpoint of improving solder heat resistance, HAST properties (electrical reliability), crack resistance (thermal shock resistance), and adhesive strength between the underfill material and the cured film after PCT resistance test (pressure cooker test). It is also preferable that the silica fine particles are surface-treated with alumina and/or an organosilane compound from the viewpoint of improving the aggregation prevention effect.

When the silica is used, the content is preferably 30 to 60% by mass, and more preferably 35 to 55% by mass, based on the total solid content of the photosensitive resin composition. When the content of silica fine particles is within the above range, it is possible to further improve the low expansion coefficient, solder heat resistance, and adhesive strength between the underfill material and the cured film after the PCT resistance test.

The photosensitive resin composition of the present invention may further contain (E) a pigment, (F) a curing agent, and/or (G) an elastomer in addition to the above-mentioned components (A) to (D). It may also further contain (H) an epoxy resin curing agent. Each component will be described below.

[(E) Pigment]
The photosensitive resin composition preferably contains a pigment as component (E). The pigment (E) is preferably used according to the desired color in order to improve the identification and appearance of the manufacturing equipment, and when concealing the wiring pattern, etc. The pigment (E) is used as necessary according to the desired color, and a colorant that develops the desired color may be appropriately selected and used. Preferred examples of the colorant include known colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, and crystal violet.
The content of the pigment (E) is preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total solid content in the photosensitive resin composition. When the content of the component (E) is within the above range, the wiring pattern can be concealed.

[(F) Curing Agent]
The (F) curing agent is preferably a compound that itself cures with heat, ultraviolet light, etc., or a compound that cures by reacting with a carboxyl group or a hydroxyl group of the (A) acid-modified vinyl group-containing epoxy resin with heat, ultraviolet light, etc. Use of the (F) curing agent can improve the heat resistance, adhesiveness, chemical resistance, etc. of the cured film formed from the photosensitive resin composition.

Examples of the (F) curing agent include thermosetting compounds such as epoxy compounds, melamine compounds, urea compounds, oxazoline compounds, blocked isocyanates, etc. Examples of the epoxy compounds include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, novolac type epoxy resins, bisphenol S type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclo type epoxy resins, hydantoin type epoxy resins, heterocyclic epoxy resins such as triglycidyl isocyanurate, and bixylenol type epoxy resins.
Examples of the melamine compound include triaminotriazine, hexamethoxymelamine, and hexabutoxylated melamine.
An example of the urea compound is dimethylol urea.

As the blocked isocyanate, an addition reaction product of a polyisocyanate compound and an isocyanate blocking agent is used. Examples of the polyisocyanate compound include polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, naphthylene diisocyanate, bis(isocyanatemethyl)cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, and isophorone diisocyanate, as well as their adducts, biuret forms, and isocyanurates.

Examples of isocyanate blocking agents include phenol-based blocking agents such as phenol, cresol, xylenol, chlorophenol, and ethylphenol; lactam-based blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; active methylene-based blocking agents such as ethyl acetoacetate and acetylacetone; methanol, ethanol, propanol, butanol, amyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, benzyl ether, methyl glycolate, butyl glycolate, diacetone alcohol, and methyl lactate. Examples of blocking agents include alcohol-based blocking agents such as ethyl lactate and ethyl lactate; oxime-based blocking agents such as formaldehyde oxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monoxime, and cyclohexane oxime; mercaptan-based blocking agents such as butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, thiophenol, methylthiophenol, and ethylthiophenol; acid amide-based blocking agents such as acetate amide and benzamide; imide-based blocking agents such as succinimide and maleimide; amine-based blocking agents such as xylidine, aniline, butylamine, and dibutylamine; imidazole-based blocking agents such as imidazole and 2-ethylimidazole; and imine-based blocking agents such as methyleneimine and propyleneimine.

The (F) curing agent preferably contains an epoxy compound (epoxy resin) and/or a blocked isocyanate, from the viewpoint of further improving the heat resistance of the cured film, and more preferably uses an epoxy compound and a blocked isocyanate in combination.

The (F) curing agent may be used alone or in combination of two or more. When the (F) curing agent is used, its content is preferably 2 to 40 mass %, more preferably 3 to 30 mass %, and even more preferably 5 to 20 mass %, based on the total solid content of the photosensitive resin composition. By setting the content of the (F) curing agent within the range of 2 to 40 mass %, it is possible to further improve the heat resistance of the cured film formed while maintaining good developability.

[(G) Elastomer]
The elastomer (G) can be suitably used when the photosensitive resin composition of the present invention is used for a semiconductor package substrate. By adding the elastomer (G) to the photosensitive resin composition of the present invention, the problem of the crosslinking reaction (curing reaction) proceeding due to ultraviolet light or heat, the acid-modified vinyl group-containing epoxy resin (A) curing and shrinking, and distortion (internal stress) being applied to the inside of the resin, resulting in reduced flexibility and adhesiveness, can be solved.

(G) Elastomers include, for example, styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers. These (G) elastomers consist of hard segment components and soft segment components, with the former generally contributing to heat resistance and strength, and the latter to flexibility and toughness.

Examples of styrene-based elastomers include styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, and styrene-ethylene-propylene-styrene block copolymers.

In addition to styrene, styrene derivatives such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, and 4-cyclohexylstyrene can be used as components constituting the styrene-based elastomer. More specifically, Tufprene, Solprene T, Asaprene T, and Tuftec (all manufactured by Asahi Kasei Corporation), Elastomer AR (manufactured by Aronkasei Corporation), Kraton G, Cariflex (manufactured by Kraton Polymer Japan Co., Ltd.), JSR-TR, TSR-SIS, and Dynaron (manufactured by JSR Corporation), Denka STR (manufactured by Denka Co., Ltd.), Quintac (manufactured by Zeon Corporation), TPE-SB series (manufactured by Sumitomo Chemical Co., Ltd.), Rabalon (manufactured by Mitsubishi Chemical Corporation), Septon and Hybra (manufactured by Kuraray Co., Ltd.), Sumiflex (manufactured by Sumitomo Bakelite Co., Ltd.), Leostomer, and Actimer (manufactured by Riken Technos Corporation), etc. can be used.

Olefin elastomers are copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methyl-pentene. Specific examples include ethylene-propylene copolymers (EPR), ethylene-propylene-diene copolymers (EPDM), copolymers of non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene, and α-olefin copolymers, and carboxy-modified NBR obtained by copolymerizing butadiene-acrylonitrile copolymers with methacrylic acid. More specific examples include ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, propylene-α-olefin copolymer rubber, and butene-α-olefin copolymer rubber. More specifically, Milastomer (Mitsui Chemicals), EXACT (Exxon Mobil), ENGAGE (Dow Chemical), hydrogenated styrene-butadiene rubber "DYNABON HSBR" (JSR Corporation), butadiene-acrylonitrile copolymer "NBR series" (JSR Corporation), butadiene-acrylonitrile copolymer "XER series" (JSR Corporation) modified with carboxyl groups at both ends, epoxidized polybutadiene BF-1000 (Nippon Soda Co., Ltd.), PB-3600 (Daicel Corporation), etc., which are partially epoxidized polybutadiene, can be used.

Urethane elastomers consist of structural units of hard segments made of low molecular weight glycols and diisocyanates, and soft segments made of high molecular weight (long chain) diols and diisocyanates.

As low molecular weight glycols, short chain diols such as ethylene glycol, propylene glycol, 1,4-butanediol, and bisphenol A can be used. The number average molecular weight of the short chain diol is preferably 48 to 500.

Examples of polymeric (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene-neopentylene adipate). The number average molecular weight of the polymeric (long-chain) diol is preferably 500 to 10,000.

Specific examples of urethane-based elastomers include PANDEX T-2185 and T-2983N (manufactured by DIC Corporation) and Miractoran E790 (manufactured by Nippon Miractoran Co., Ltd.).

Examples of polyester-based elastomers include those obtained by polycondensation of dicarboxylic acid or a derivative thereof and a diol compound or a derivative thereof.
Specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, aromatic dicarboxylic acids in which the hydrogen atoms of the aromatic nuclei are substituted with methyl groups, ethyl groups, phenyl groups, etc., aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These compounds can be used alone or in combination of two or more.
Specific examples of the diol compound include aliphatic diols and alicyclic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 1,4-cyclohexanediol, or dihydric phenols represented by the following general formula (4).

[In general formula (4), Y ¹¹ represents an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 4 to 8 carbon atoms, -O-, -S-, or -SO ₂ -; R ²¹ and R ²² represent a halogen atom or an alkyl group having 1 to 12 carbon atoms; p and q represent integers of 0 to 4; and r represents 0 or 1.]

Specific examples of dihydric phenols represented by general formula (4) include bisphenol A, bis-(4-hydroxyphenyl)methane, bis-(4-hydroxy-3-methylphenyl)propane, and resorcinol. These compounds can be used alone or in combination of two or more.

It is also possible to use a multiblock copolymer in which an aromatic polyester (e.g., polybutylene terephthalate) portion serves as the hard segment component and an aliphatic polyester (e.g., polytetramethylene glycol) portion serves as the soft segment component. There are various grades available depending on the type, ratio, and molecular weight of the hard and soft segments. Specific examples include Hytrel (manufactured by DuPont-Toray Co., Ltd.), Pelprene (manufactured by Toyobo Co., Ltd.), and Espel (manufactured by Hitachi Chemical Co., Ltd.).

Polyamide elastomers are broadly divided into two types: polyether block amide type, which uses polyamide for the hard segment and polyether or polyester for the soft segment, and polyether ester block amide type.

Polyamides that can be used include polyamide-6, 11, 12, etc. Polyethers that can be used include polyoxyethylene, polyoxypropylene, polytetramethylene glycol, etc. Specifically, UBE polyamide elastomer (manufactured by Ube Industries, Ltd.), DAIAMID (manufactured by Daicel-Evonik Ltd.), PEBAX (manufactured by Toray Industries, Inc.), GRILLON ELY (manufactured by M-Chemie Japan, Ltd.), NOPAMIDT (manufactured by Mitsubishi Chemical Corporation), and GLYX (manufactured by DIC Corporation) can be used.

Acrylic elastomers are mainly composed of acrylic esters, and ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, etc. are used. In addition, glycidyl methacrylate, allyl glycidyl ether, etc. are used as cross-linking point monomers. Furthermore, acrylonitrile and ethylene can also be copolymerized. Specifically, acrylonitrile-butyl acrylate copolymers, acrylonitrile-butyl acrylate-ethyl acrylate copolymers, acrylonitrile-butyl acrylate-glycidyl methacrylate copolymers, etc. can be used.

Silicone elastomers are primarily made of organopolysiloxane and are divided into polydimethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane types. Some are partially modified with vinyl groups, alkoxy groups, etc. Specific examples include the KE series (manufactured by Shin-Etsu Chemical Co., Ltd.), SE series, CY series, and SH series (all manufactured by Dow Corning Toray Silicone Co., Ltd.).

In addition to the above-mentioned elastomers, rubber-modified epoxy resins can also be used. Rubber-modified epoxy resins can be obtained by modifying, for example, a portion or all of the epoxy groups of bisphenol F epoxy resins, bisphenol A epoxy resins, salicylaldehyde epoxy resins, phenol novolac epoxy resins, or cresol novolac epoxy resins with butadiene-acrylonitrile rubber modified at both ends with carboxylic acid, or silicone rubber modified at both ends with amino. Among these elastomers, butadiene-acrylonitrile copolymers modified at both ends with carboxyl groups, Espel (Hitachi Chemical Co., Ltd., Espel 1612, 1620, which are polyester-based elastomers having hydroxyl groups), and epoxidized polybutadiene are preferred in terms of shear adhesion. Elastomers that are liquid at room temperature (25°C) are particularly preferred.

When the (G) elastomer is used, its content is preferably 1 to 20 mass %, more preferably 2 to 15 mass %, and even more preferably 3 to 10 mass %, based on the total solid content of the photosensitive resin composition. By setting the (G) elastomer content within the range of 1 to 20 mass %, it is possible to further improve the thermal shock resistance and the adhesive strength between the underfill material and the cured film while maintaining good developability. In addition, when used on a thin film substrate, it is possible to reduce the warpage of the thin film substrate.

[(H) Epoxy resin curing agent]
An epoxy resin curing agent (H) may also be added to the photosensitive resin composition of the present invention for the purpose of further improving the properties of the cured film formed, such as heat resistance, adhesiveness, and chemical resistance.

Specific examples of such (H) epoxy resin curing agents include imidazole derivatives such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; guanamines such as acetoguanamine and benzoguanamine; polyamines such as diaminodiphenylmethane, m-phenylenediamine, m-xylylenediamine, diaminodiphenylsulfone, dicyandiamide, urea, urea derivatives, melamine, and polybasic hydrazides; organic acid salts and/or epoxy adducts thereof: amine complexes of boron trifluoride; triazine derivatives such as ethyldiamino-S-triazine, 2,4-diamino-S-triazine, and 2,4-diamino-6-xylyl-S-triazine; trimethylamine, triethanolamine, N,N-dimethyloctylamine, N-benzyldimethylamine, pyridine, N-methylmonoamine, etc. Tertiary amines such as fluoroline, hexa(N-methyl)melamine, 2,4,6-tris(dimethylaminophenol), tetramethylguanidine, and m-aminophenol; polyphenols such as polyvinylphenol, polyvinylphenol bromide, phenol novolac, and alkylphenol novolac; organic phosphines such as tributylphosphine, triphenylphosphine, and tris-2-cyanoethylphosphine; phosphonium salts such as tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide and hexadecyltributylphosphonium chloride; quaternary ammonium salts such as benzyltrimethylammonium chloride and phenyltributylammonium chloride; the above-mentioned polybasic acid anhydrides; diphenyliodonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, and 2,4,6-triphenylthiopyrylium hexafluorophosphate. These (H) epoxy resin curing agents can be used alone or in combination of two or more.

When an epoxy resin curing agent (H) is used, its content is preferably 0.01 to 20 mass % based on the total solid content of the photosensitive resin composition, and more preferably 0.1 to 10 mass %.

[(I) Thermoplastic resin]
In addition, in order to further improve the flexibility of the cured film, (I) a thermoplastic resin may be added to the photosensitive resin composition of the present invention.

(I) Examples of thermoplastic resins include acrylic resins and urethane resins. (I) When a thermoplastic resin is included, the content is preferably 1 to 30 mass % and more preferably 5 to 20 mass % based on the total solid content of the photosensitive resin composition.

Furthermore, various known and commonly used additives such as organic fine particles such as melamine and organic bentonite, polymerization inhibitors such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol, thickeners such as bentone and montmorillonite, silicone-based, fluorine-based, and vinyl resin-based defoamers, silane coupling agents, and diluents can be added to the photosensitive resin composition of the present invention as necessary. Furthermore, flame retardants such as brominated epoxy compounds, acid-modified brominated epoxy compounds, antimony compounds, and phosphate compounds of phosphorus-based compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters can also be added.

As the diluent, for example, an organic solvent can be used. Examples of the organic solvent include ketones such as ethyl methyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene, glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether, esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate, aliphatic hydrocarbons such as octane and decane, and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The diluent is used alone or in combination of two or more. When a diluent is used, the content can be appropriately adjusted from the viewpoint of the coatability of the photosensitive resin composition.

The photosensitive resin composition of the present invention can be obtained by uniformly kneading and mixing the above-mentioned components using a roll mill, bead mill, etc.

The photosensitive resin composition of the present invention can satisfy the characteristics and reliability required for solder resists, interlayer insulating films, surface protective films for semiconductors, etc., which are provided on printed wiring boards such as rigid wiring boards and flexible wiring boards, and package substrates. The solder resist obtained from the photosensitive resin composition of the present invention is not only sufficiently excellent in thermal shock resistance, but also, due to the same factors, is excellent in mechanical properties such as alkali resistance, solder heat resistance, electrolytic Ni/Au plating resistance, elongation and tensile strength, and HAST resistance.

[Photosensitive film]
A preferred embodiment of the photosensitive film of the present invention will be described below. The photosensitive film includes a support layer, a photosensitive layer containing the photosensitive resin composition formed on the support layer, and a protective film layer laminated on the photosensitive layer.

The photosensitive layer is preferably formed by dissolving the above-mentioned photosensitive resin composition in a solvent (diluent) as described above as necessary to obtain a solution with a solid content of about 30 to 70% by mass, and then coating the solution on the support layer and drying it. The coating can be performed by a known method using, for example, a roll coater, a comma coater, a gravure coater, an air knife coater, a die coater, a bar coater, or the like. The thickness of the above-mentioned photosensitive layer varies depending on the application, but is preferably 5 to 100 μm, and more preferably 10 to 60 μm, after drying in which the diluent is removed by heating and/or hot air blowing. If the thickness is less than 5 μm, industrial coating tends to be difficult, and if it exceeds 100 μm, the sensitivity and resolution of the photosensitive resin composition layer tend to decrease.

Examples of the support layer that the photosensitive film has include polymer films that are heat-resistant and solvent-resistant, such as polyesters such as polyethylene terephthalate, polypropylene, and polyethylene.

The thickness of the support layer is preferably 5 to 100 μm, and more preferably 10 to 30 μm. If the thickness is less than 5 μm, the support tends to be easily torn when peeled off from the photosensitive film before development, and if the thickness exceeds 100 μm, the resolution and flexibility tend to decrease. In this embodiment, the photosensitive layer is formed using the polyester resin described above, so that the flexibility and resolution can be maintained even when the thickness of the support layer is thicker than conventional ones, for example, when it is greater than 25 μm and less than 100 μm.

Examples of the protective film layer include polyethylene film, polypropylene film, polyethylene terephthalate film, surface-treated paper, etc. It is preferable that the adhesive strength between the photosensitive layer and the protective film layer is smaller than the adhesive strength between the photosensitive layer and the support layer.

The photosensitive film, which is composed of three layers, a support layer, a photosensitive layer, and a protective film layer, as described above, can be stored as is, or it can be stored after being wound up in a roll on a core with a protective film layer interposed therebetween.

[Method of forming resist pattern, printed wiring board]
The method for forming a resist pattern of the present invention is characterized in that a photosensitive layer is laminated on the insulating substrate of a laminated substrate comprising an insulating substrate and a conductor layer having a circuit pattern formed on the insulating substrate, using a photosensitive resin composition, so as to cover the conductor layer, predetermined parts of the photosensitive layer are irradiated with active light rays to form exposed parts, and then parts of the photosensitive layer other than the exposed parts are removed.

In an embodiment, the photosensitive layer of the photosensitive film is used as the photosensitive layer using the photosensitive resin composition. A photosensitive layer made of the photosensitive resin composition is formed on a substrate on which a resist is to be formed. The protective film of the photosensitive film is peeled off from the photosensitive resin composition layer, and the exposed surface is adhered by lamination or the like. From the viewpoint of improving adhesion and followability, a method of laminating under reduced pressure is also preferred. The photosensitive resin composition can also be applied to the substrate by a known method such as a method of applying a varnish of the photosensitive resin composition by screen printing or a roll coater. Next, an exposure process is performed in which a predetermined portion of the photosensitive resin composition layer is irradiated with active light through a mask pattern, and the photosensitive resin composition layer in the irradiated portion is photocured.

As the light source of the actinic rays, known light sources that effectively radiate ultraviolet light, such as carbon arc lamps, mercury vapor arc lamps, ultra-high pressure mercury lamps, high pressure mercury lamps, and xenon lamps, can be used. In addition, light sources that effectively radiate visible light or ultraviolet light, such as photographic flood lamps and sun lamps, can also be used.

Furthermore, if a support is present on the photosensitive layer, the support is removed, and then the non-photocured portions (unexposed portions) are removed by wet or dry development, followed by development to form a resist pattern. In the case of wet development, the developer used is, for example, an alkaline aqueous solution such as sodium hydroxide, a water-based developer, or an organic solvent, which is safe, stable, and easy to operate. Development methods include the dip method, the bath method, the spray method, the high-pressure spray method, brushing, and slapping.

After the development step, it is preferable to irradiate the resist with ultraviolet light using a high-pressure mercury lamp or heat the resist in order to improve solder heat resistance, chemical resistance, etc. When irradiating the resist with ultraviolet light, the amount of irradiation can be adjusted as necessary, and for example, irradiation can be performed at an amount of irradiation of about 0.05 to 10 J/ ^cm2 . When heating the resist pattern, it is preferable to heat the resist pattern at a temperature in the range of about 130 to 200°C for about 15 to 90 minutes.

Both ultraviolet irradiation and heating may be performed. In this case, both may be performed simultaneously, or one may be performed after the other. When ultraviolet irradiation and heating are performed simultaneously, it is preferable to heat the material to 60 to 150°C in order to provide better solder heat resistance and chemical resistance.

The permanent resist thus formed also serves as a protective film for the wiring after soldering to the board, and has the properties of a solder resist, making it possible to use it as a solder resist for printed wiring boards, semiconductor package boards, and flexible wiring boards. For example, when plating or etching a board, the solder resist is used as a plating resist or etching resist, and is also left on the board as is and used as a protective film to protect the wiring, etc.

The substrate with the permanent resist is then mounted with semiconductor elements (e.g., wire bonding, solder connection) and then installed in an electronic device such as a personal computer.

Although the above describes a preferred embodiment of the present invention, the present invention is not limited to the above embodiment.

For example, in another embodiment of the photosensitive film of the present invention, the film may have only a photosensitive layer and a support layer, without having a protective film layer. The printed wiring board of the present invention may also be a multilayer printed wiring board in which multiple conductive layers and insulating layers are alternately laminated on an insulating substrate or on both sides of an insulating substrate, in which case the cured product of the photosensitive resin composition of the present invention functions as an interlayer insulating film to reliably insulate the conductive layers from each other.

The photosensitive resin composition of the present invention may also be used in a method for producing a printed wiring board. For example, there may be mentioned a method for producing a printed wiring board comprising an insulating substrate, a conductor layer having a circuit pattern formed on the insulating substrate, and a permanent resist layer formed so as to cover the conductor layer, in which a photosensitive layer is laminated on the insulating substrate so as to cover the conductor layer using the photosensitive resin composition of the present invention, a predetermined portion of the photosensitive layer is irradiated with active light to form an exposed portion, and then the portion other than the exposed portion is removed.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Synthesis Example: Production of Acid-Modified Vinyl Group-Containing Epoxy Resins (A-1, 2, 3, 4)]
350 parts by mass of bisphenol F novolac epoxy resin (EXA-7376, manufactured by DIC Corporation) having a structural unit represented by general formula (3) (R ¹³ = hydrogen atom, Y ³ = glycidyl group), 70 parts by mass of acrylic acid, 0.5 parts by mass of methyl hydroquinone, 120 parts by mass of carbitol acetate, and a catalyst (triphenylphosphine) were charged and reacted by heating to 90° C. and stirring to completely dissolve the mixture. Next, the resulting solution was cooled to 60° C., 2 parts by mass of triphenylphosphine was added, and the mixture was heated to 100° C. and reacted until the acid value of the solution reached 1 mgKOH/g. To the reaction solution, 98 parts by mass of tetrahydrophthalic anhydride (THPAC) and 85 parts by mass of carbitol acetate were added, and the mixture was heated to 80°C and reacted for about 6 hours, followed by cooling to obtain a solution of THPAC-modified bisphenol F-type novolak epoxy acrylate (hereinafter referred to as "acid-modified vinyl group-containing epoxy resin (A-1, 2, 3, 4) (dispersity; A-1 = 6.0, A-2 = 4.5, A-3 = 3.5, A-4 = 2.5)) as component (A) having a solid content concentration of 73% by mass. Here, resins with different dispersities were obtained by changing the amount of catalyst (0 to 2 parts by mass), heating temperature (80 to 120°C), and time.

(Measurement of Dispersion Degree)
The number average molecular weight (Mn), weight average molecular weight (Mw) and Mw/Mn (dispersity) of the THPAC-modified bisphenol F-type novolac epoxy acrylate were determined by measuring the chromatogram of the molecular weight distribution of the THPAC-modified bisphenol F-type novolac epoxy acrylate by GPC (gel permeation chromatography) and converting it from the elution time of standard polystyrene at 25° C. The measurement device used was EcoSEC, HLC-8320GPC manufactured by Tosoh Corporation, the eluent used was tetrahydrofuran, and the column used was a Gelpack GL-A-150 and a Gelpack GL-A-10 (manufactured by Hitachi High-Technologies Corporation, product name) directly connected together.

(Examples 1 to 3, Comparative Examples 1 to 4)
The materials shown in Table 1 below were mixed in the amounts (unit: parts by mass) shown in the table, then kneaded in a three-roll mill, and carbitol acetate was added so that the solid content concentration became 70% by mass to obtain a photosensitive resin composition. The amount of each material in Table 1 below indicates the amount of solid content.

The details of each material in Table 1 are as follows.
[(A) Acid-modified vinyl group-containing epoxy resin]
*1 (Acid-modified vinyl group-containing epoxy resin (A-1)): THPAC-modified bisphenol F-type novolac epoxy acrylate (dispersity Mw/Mn = 6.0) prepared in the synthesis example.
*2 (Acid-modified vinyl group-containing epoxy resin (A-2)): THPAC-modified bisphenol F-type novolac epoxy acrylate (dispersity Mw/Mn = 4.5) prepared in the synthesis example.
*3 (Acid-modified vinyl group-containing epoxy resin (A-3)): THPAC-modified bisphenol F-type novolac epoxy acrylate (dispersity Mw/Mn = 3.5) prepared in the synthesis example.
* 4 (Acid-modified vinyl group-containing epoxy resin (A-4)): THPAC-modified bisphenol F-type novolac epoxy acrylate (dispersity Mw/Mn = 2.5) prepared in the synthesis example.
[(B) Photopolymerizable monomer having an ethylenically unsaturated bond]
*5 (Aronix M402): Dipentaerythritol hexaacrylate (manufactured by Toagosei Co., Ltd.)
[(C) Photopolymerization initiator]
*6 (Irgacure 907): (2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, manufactured by BASF Japan Ltd.)
[(D) Inorganic filler]
* 7 (SFP-20M): Silica fine particles (ultrafine spherical silica, average particle size 0.3 μm, manufactured by Denka Co., Ltd.)
* 8 (B-34): Barium sulfate microparticles (average particle size 0.3 μm, manufactured by Sakai Chemical Industry Co., Ltd.)
[(F) Curing Agent]
* 9 (YSLV-80XY): Epoxy resin (tetramethylbisphenol F type, epoxy equivalent = 192 g / eq, melting point = 72 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)
*10 (RE-306): Epoxy resin (phenol novolac type epoxy resin, manufactured by Nippon Kayaku Co., Ltd.)
[(G) Elastomer]
*11 (PB-3600): Epoxidized polybutadiene (manufactured by Daicel Corporation)

[Silica Residue]
The photosensitive resin compositions of the examples and comparative examples were applied to a copper-clad laminate substrate (MCL-E-67, glass cloth-based epoxy resin substrate, manufactured by Hitachi Chemical Co., Ltd.) by screen printing so that the film thickness after drying was 15 μm, and then dried at 75 ° C. for 30 minutes using a hot air circulation dryer. The resulting coating film was irradiated with ultraviolet light at an integrated exposure of 100 mJ / cm ² through a negative film having a 1 × 1 cm square area dotted with light non-transmitting parts of 80 μm in diameter, and spray-developed with a 1 mass % aqueous sodium carbonate solution at a pressure of 1.8 kgf / cm ² for 60 seconds, and the unexposed parts were dissolved and developed to form an image. Thereafter, the opening was observed at 10,000 times using a SEM (manufactured by High Technologies Corporation, model number: S4200, field emission scanning electron microscope), and the remaining condition of silica residue was evaluated according to the following criteria. The evaluation results are shown in Table 2.
A: 1 or less silica residues in one visual field. B: 2 or more but less than 10 silica residues in one visual field. C: 10 or more silica residues in one visual field.

[Evaluation of HAST resistance]
A copper surface of a printed wiring board substrate (MCL-E-679, glass cloth substrate high Tg epoxy resin substrate, Hitachi Chemical Co., Ltd., product name) in which 12 μm thick copper foil was laminated on a glass epoxy substrate was etched to form a comb-shaped electrode with a line/space of 28 μm/32 μm. This substrate was used as an evaluation substrate, and a cured resist was formed on the substrate as described above, followed by exposure for 200 hours under conditions of 135° C., 85% RH, and DC 5 V. The extent of migration was then observed with a 100x metallurgical microscope and evaluated according to the following criteria.
That is, a permanent resist film in which no migration occurred and no decrease in resistance value was rated as "3," a permanent resist film in which no decrease in resistance value occurred but migration occurred was rated as "2," and a permanent resist film in which significant migration occurred and resistance value decreased was rated as "1."
The evaluation results are shown in Table 2.

[Evaluation of thermal expansion coefficient and glass transition point (Tg)]
The photosensitive resin composition solution was uniformly applied onto a 16 μm thick polyethylene terephthalate film (G2-16, Teijin Ltd., product name) as a support layer so that the film thickness after drying was 30 μm, and then dried at 75 ° C. for about 30 minutes using a hot air convection dryer. Subsequently, a polyethylene film (NF-15, Tamapoly Co., Ltd., product name) was laminated as a protective film on the surface opposite to the side in contact with the support of the photosensitive resin composition layer to obtain a photosensitive film. The entire surface of the photosensitive film was exposed to light, and then the film was left to stand at room temperature (25 ° C.) for 1 hour, after which the polyethylene film was peeled off and spray-developed with a 1% by mass aqueous solution of sodium carbonate at 30 ° C. After spray development, the film was irradiated with ultraviolet light at 2 J / cm2 using an ultraviolet light irradiation device manufactured by Oak Seisakusho Co., Ltd., and further heated at 170 ° C. for 60 minutes. Next, the laminate was cut into a width of 3 mm and a length of 30 mm with a cutter knife, and the polyethylene terephthalate film, which was the support on the laminate, was peeled off to obtain a photosensitive resin cured product (test piece) for evaluating the thermal expansion coefficient. The thermal expansion coefficient (10 ^-6 /°C, ppm) in the tensile mode was measured using a TMA device (thermomechanical analyzer) SS6000 (manufactured by Seiko Instruments Inc.). The tensile load was 5 g, the span (distance between chucks) was 15 mm, and the heating rate was 10°C/min. First, the test piece was mounted on the device, heated from room temperature (25°C) to 160°C, and left for 15 minutes. Then, it was cooled to -60°C, and measurements were performed under the condition of a heating rate of 10°C/min from -60°C to 250°C, and the glass transition point and the thermal expansion coefficient were measured. The evaluation results are shown in Table 2.

As is clear from Table 2, Examples 1 to 3 are excellent in general properties such as silica residue, electrical reliability (HAST resistance), low thermal expansion coefficient, and high Tg. In addition, it is clear that acid-modified vinyl group-containing epoxy resins with a dispersity of 3.5 or less have particularly low silica residue and excellent thermal expansion coefficient and heat resistance. In contrast, as is clear from Table 2, Comparative Examples 1 to 4 have insufficient silica residue and electrical reliability. Therefore, according to the photosensitive resin composition of the present invention, a permanent mask resist with low silica residue, low thermal expansion coefficient, excellent HAST resistance, and high Tg can be obtained.

Claims (6)

The photosensitive resin composition comprises (A) an acid-modified vinyl group-containing epoxy resin, (B) a photopolymerizable monomer having an ethylenically unsaturated bond, (C) a photopolymerization initiator, and (D) an inorganic filler, wherein the acid-modified vinyl group-containing epoxy resin of component (A) is a resin (A″) obtained by reacting an epoxy resin (a) which is a bisphenol-type novolak resin having a structural unit represented by the following general formula (2) or (3) with a vinyl group-containing monocarboxylic acid (b) to obtain a resin (A′), with a saturated or unsaturated group-containing polybasic acid anhydride (wherein Mw/Mn and a polydispersity represented by (weight average molecular weight/number average molecular weight) of 2.0 to 5.0. Also excluding a resin obtained by reacting an o-cresol novolac resin with acrylic acid, followed by reaction with tetrahydrophthalic anhydride, and a resin obtained by reacting an o-cresol novolac resin with acrylic acid and a pentaerythritol triacrylate-succinic anhydride adduct, followed by reaction with succinic anhydride and tetrahydrophthalic anhydride.), wherein (D) the inorganic filler comprises silica and barium sulfate, and the content of the inorganic filler is 40 to 70 mass% based on the total solid content.


[In the general formula (2), R ¹² represents a hydrogen atom or a methyl group, and Y ² each independently represents a hydrogen atom or a glycidyl group. The two R ¹² may be the same or different. However, at least one of Y ² represents a glycidyl group. In the general formula (3), R ¹³ represents a hydrogen atom or a methyl group, and Y ³ each independently represents a hydrogen atom or a glycidyl group. The two R ¹³ may be the same or different. However, at least one of Y ³ represents a glycidyl group.] The photosensitive resin composition according to claim 1, wherein (B) the photopolymerizable monomer having an ethylenically unsaturated bond is a polyfunctional photopolymerizable monomer having three or more ethylenically unsaturated bonds in one molecule. The photosensitive resin composition according to claim 1 or 2, further comprising (E) a pigment. A photosensitive film comprising a support and a photosensitive layer formed from the photosensitive resin composition according to any one of claims 1 to 3. A method for forming a resist pattern, comprising: laminating a photosensitive layer on a laminate substrate having an insulating substrate and a conductor layer having a circuit pattern formed on the insulating substrate, using the photosensitive resin composition according to any one of claims 1 to 3, so as to cover the conductor layer; irradiating a predetermined portion of the photosensitive layer with active light to form an exposed portion; and then removing the portion of the photosensitive layer other than the exposed portion. A printed wiring board comprising an insulating substrate, a conductor layer having a circuit pattern formed on the insulating substrate, and a permanent resist layer formed using the photosensitive resin composition according to any one of claims 1 to 3 so as to cover the conductor layer.