Photosensitive resin composition, dry film, cured product and electronic component

Abstract

To provide a photosensitive resin composition that enables formation of a pattern in which a development residue is suppressed, and suppresses occurrence of cracks in a cured film.SOLUTION: A photosensitive resin composition contains an alkali-soluble resin, a thermosetting component and a polymerizable compound having an ethylenic unsaturated group, a photopolymerization initiator and an inorganic filler. The alkali-soluble resin contains an alkali-soluble urethane resin, and has a percentage content of the alkali-soluble urethane resin to the total content of the alkali-soluble resin of 8 mass% or more and 75 mass% or less. When measurement is performed while the temperature is raised at speed of 10°C / min, after the temperature is raised from room temperature to 260°C at a test load of 5 g and a rate of 10°C / min, and then the temperature is lowered from 260°C to -70°C at a rate of 5°C / min, a coefficient of linear expansion indicated by a cured product with thickness of 25 μm obtained by curing the photosensitive resin composition is more than 5 ppm / °C and 35 ppm / °C or less at 0°C, and is more than 5 ppm / °C and 30 ppm / °C or less at -30°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photosensitive resin composition, a dry film, a cured product, and an electronic component. [Background technology]

[0002] In response to the increasing density of printed wiring boards used in electronic devices, package substrates such as BGA (ball grid array) are increasingly being adopted. Because wiring patterns are formed more densely and closely together on package substrates, permanent coatings such as solder resists used on such package substrates must be highly reliable. For example, Patent Document 1 describes a photosensitive composition for a solder-resistant resin layer containing an elastomer and an inorganic filler. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-013161 Summary of the Invention [Problem to be solved by the invention]

[0004] As package substrates become larger, stiffeners made of stainless steel or other materials are sometimes mounted on the solder resist around the semiconductor element to correct the warpage of the substrate. Mounting a stiffener increases stress, which can make the solder resist more susceptible to cracks.

[0005] An object of one aspect of the present invention is to provide a photosensitive resin composition that can form a pattern with reduced development residues and that suppresses the occurrence of cracks in a cured film. [Means for solving the problem]

[0006] The present invention includes the following aspects. [1] A photosensitive resin composition containing an alkali-soluble resin, a thermosetting component, a polymerizable compound having an ethylenically unsaturated group, a photopolymerization initiator, and an inorganic filler, the alkali-soluble resin includes an alkali-soluble urethane resin, and the content of the alkali-soluble urethane resin relative to the total content of the alkali-soluble resin is 8% by mass or more and 75% by mass or less; The photosensitive resin composition has a linear expansion coefficient of more than 5 ppm / °C and not more than 35 ppm / °C at 0°C and more than 5 ppm / °C and not more than 30 ppm / °C at -30°C, when the measurement is performed with a test load of 5 g, by heating from room temperature to 260°C at a rate of 10°C / min, cooling from 260°C to -70°C at a rate of 5°C / min, and then heating at a rate of 10°C / min.

[0007] [2] The photosensitive resin composition according to [1], wherein the inorganic filler contains silica.

[0008] [3] The photosensitive resin composition according to [2], wherein the content of the silica is 15% by mass or more and 60% by mass or less based on the total solid content of the photosensitive resin composition.

[0009] [4] The photosensitive resin composition according to any one of [1] to [3], wherein the content of the alkali-soluble urethane resin relative to the total content of the alkali-soluble resin is 8% by mass or more and 60% by mass or less.

[0010] [5] The photosensitive resin composition according to any one of [1] to [4], wherein the cured product has a glass transition temperature of 150°C or higher.

[0011] [6] A dry film having a resin layer obtained by applying the photosensitive resin composition according to any one of [1] to [5] to a first film and drying the applied composition.

[0012] [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].

[0013] [8] An electronic component comprising the cured product according to [7]. [Effects of the Invention]

[0014] According to one aspect of the present invention, it is possible to provide a photosensitive resin composition that can form a pattern with reduced development residues and that suppresses the occurrence of cracks in a cured film. DETAILED DESCRIPTION OF THE INVENTION

[0015] As used herein, the term "process" refers not only to an independent process, but also to processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. Furthermore, when multiple substances corresponding to each component are present in the composition, the content of each component refers to the total amount of those multiple substances present in the composition, unless otherwise specified. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. In this specification, "(meth)acrylate" is a general term for acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions. Furthermore, "solid content" refers to the residue remaining after removing volatile components (e.g., organic solvents) from a composition or its components. Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are intended to exemplify photosensitive resin compositions, dry films, cured products, and electronic components intended to embody the technical concept of the present invention. The present invention is not limited to the photosensitive resin compositions, dry films, cured products, and electronic components shown below.

[0016] Photosensitive resin composition The photosensitive resin composition contains an alkali-soluble resin, a thermosetting component, a polymerizable compound having an ethylenically unsaturated group, a photopolymerization initiator, and an inorganic filler. The alkali-soluble resin includes an alkali-soluble urethane resin, and the content of the alkali-soluble urethane resin relative to the total content of the alkali-soluble resin is 8% by mass or more and 75% by mass or less. The photosensitive resin composition is cured to a thickness of 25 μm, and the cured product exhibits a coefficient of linear expansion (CTE) of more than 5 ppm / °C and less than 35 ppm / °C at 0°C and more than 5 ppm / °C and less than 30 ppm / °C at -30°C. The coefficient of linear expansion is measured using a test load of 5 g, by heating from room temperature to 260°C at a rate of 10°C / min, cooling from 260°C to -70°C at a rate of 5°C / min, and then increasing the temperature at a rate of 10°C / min.

[0017] The photosensitive resin composition contains a predetermined amount of alkali-soluble urethane resin as the alkali-soluble resin, and the composition is adjusted so that the linear expansion coefficient at low temperatures falls within a predetermined range. This effectively suppresses the occurrence of cracks after curing and the occurrence of development residues during pattern formation. This is thought to be because, for example, the flexibility of the urethane resin suppresses the amount of warpage of the photosensitive resin composition after curing, and the difference in linear expansion coefficient between the photosensitive resin composition and other components such as a substrate is reduced, thereby reducing the stress generated and suppressing the occurrence of cracks. Furthermore, the content of the urethane resin is thought to be a predetermined amount, which adjusts the compatibility of the photosensitive resin composition with the developer and washing water, thereby suppressing the occurrence of development residues.

[0018] The photosensitive resin composition is prepared so that the linear expansion coefficient of the cured product having a predetermined thickness falls within a predetermined range. The linear expansion coefficient of the cured product can be adjusted by appropriately selecting the content and type of inorganic filler, thermosetting component, polymerizable compound, etc. in the photosensitive resin composition.

[0019] The cured product used to measure the linear expansion coefficient was prepared by applying the photosensitive resin composition to a polyethylene terephthalate film, drying it with hot air, and laminating the resulting photosensitive resin layer 25 μm thick on copper foil to form a dry coating film, which was then exposed to light and developed to form a cured film with the desired pattern, after which the film was exposed to light at an integrated exposure dose of 2000 mJ / cm 2 It is formed by irradiating ultraviolet light of 1000 kJ / cm2 with 100 kJ / cm2 and then heat-treating at 150°C for 1 hour. Specifically, it is formed by the following method.

[0020] First, a photosensitive resin composition was applied to a 150mm x 95mm polyethylene terephthalate film on the glossy side of a 18μm-thick copper foil (Furukawa Sangyo Co., Ltd., FV-WS) measuring 150mm x 95mm. The resulting 25μm-thick photosensitive resin layer was then dried at 80°C for 10 minutes in a hot air circulation oven. The resulting laminate was then laminated in a first chamber at 90°C using a vacuum laminator (CVP-300, manufactured by Nikko Materials Co., Ltd.) under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds. Next, the film was exposed to light using an exposure device (Ushio Inc., UFX-2223M-APU01) equipped with a high-pressure mercury lamp to form a 3mm x 10mm strip pattern. The exposure dose was adjusted to 10 levels of gloss sensitivity using a step tablet (Photec 41 level). After exposure, the polyethylene terephthalate film was peeled off from the dry film to expose the exposed photosensitive resin layer. Thereafter, development was carried out by spraying a 1% by mass aqueous solution of sodium carbonate (Na2CO3) at 30°C for 60 seconds at a spray pressure of 2 kg / cm2, yielding a cured film measuring 3 mm x 10 mm. 2 After irradiating the resin with ultraviolet light, the resin was cured by heating at 150°C for 1 hour to obtain a cured product. The copper foil was peeled off from the cured product to obtain a measurement sample.

[0021] The linear expansion coefficient of the cured product may be greater than 5 ppm / °C and less than 35 ppm / °C at 0°C. The linear expansion coefficient at 0°C may preferably be less than 30 ppm / °C. The linear expansion coefficient of the cured product may be greater than 5 ppm / °C and less than 30 ppm / °C at -30°C. The linear expansion coefficient at -30°C may preferably be less than 25 ppm / °C. The ratio of the linear expansion coefficient at 0°C to the linear expansion coefficient at -30°C may be, for example, from 0.8 to 2.0, preferably from 0.9 to 1.5. When the linear expansion coefficient of the cured product is within the above range, cracking tends to be more effectively suppressed.

[0022] The linear expansion coefficient of a cured product with a thickness of 25 μm is measured using a thermomechanical analyzer (TMA) with a test load of 5 g. The measurement is performed by heating from room temperature to 260°C at a rate of 10°C / min, then cooling from 260°C to -70°C at a rate of 5°C / min, and then increasing the temperature at a rate of 10°C / min.

[0023] The glass transition temperature (Tg) of the cured product may be, for example, 150°C or higher, preferably 160°C or higher, or 170°C or higher. The glass transition temperature of the cured product may be, for example, 200°C or lower. When the glass transition temperature of the cured product is within the above range, cracking tends to be further suppressed. The glass transition temperature of the cured product is measured using a thermomechanical analyzer (TMA).

[0024] The photosensitive resin composition contains an alkali-soluble resin, including at least an alkali-soluble urethane resin. The alkali-soluble resin may be any of various known alkali-soluble resins having a carboxyl group in the molecule. By including the alkali-soluble resin in the photosensitive resin composition, the photosensitive resin composition can be made alkaline developable. The alkali-soluble resin preferably contains an alkali-soluble photosensitive resin having an ethylenically unsaturated double bond in the molecule, in terms of photocurability, development resistance, and the like. The ethylenically unsaturated double bond is preferably derived from acrylic acid, methacrylic acid, or a derivative thereof. When using only an alkali-soluble resin without an ethylenically unsaturated double bond as the alkali-soluble urethane resin, the photosensitive resin composition can be made photocurable by using the alkali-soluble urethane resin in combination with a compound having an ethylenically unsaturated group in the molecule, as described below. Among alkali-soluble resins, examples of alkali-soluble urethane resins (hereinafter also referred to as "first alkali-soluble resins") include the following carboxyl group-containing urethane resins and phenolic hydroxy group-containing urethane resins. The first alkali-soluble resin preferably contains at least a carboxy group-containing urethane resin.

[0025] (1) A phenolic hydroxy group-containing urethane resin in which a phenolic hydroxy group has been introduced at the end by reacting a compound (a) having two or more isocyanate groups in one molecule, a compound (b) having two or more alcoholic hydroxy groups in one molecule, and a compound (c) having one alcoholic hydroxy group and one or more phenolic hydroxy groups in one molecule, which also functions as a reaction terminator.

[0026] (2) A phenolic hydroxy group-containing urethane resin obtained by reacting a compound (a) having two or more isocyanate groups in one molecule with a compound (b) having two or more alcoholic hydroxy groups in one molecule, in which a phenolic hydroxy group has been introduced into the molecular side chain using a compound having a phenolic hydroxy group and two or more alcoholic hydroxy groups as compound (b), and a carboxy group-containing urethane resin in which a carboxy group has been introduced into the molecular side chain using a compound having one or more carboxy groups and two or more alcoholic hydroxy groups in one molecule.

[0027] In the urethane resin (2), a compound (c) having one alcoholic hydroxy group and one or more phenolic hydroxy groups in one molecule can be used as an end-capping agent (reaction terminator). In addition, various conventionally known reaction terminators can be used, such as aliphatic alcohols, monohydroxy compounds such as monohydroxymono(meth)acrylate compounds, and monocarboxylic acids having functional groups capable of undergoing addition reaction or condensation reaction with isocyanate groups, such as alcoholic hydroxy groups, amino groups, and thiol groups.

[0028] Furthermore, during resin synthesis, a compound having one hydroxy group and one or more (meth)acrylic groups in the molecule, such as a hydroxyalkyl (meth)acrylate, or a compound having one isocyanate group and one or more (meth)acrylic groups in the molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol tri(meth)acrylate, may be added to produce a (meth)acrylic-terminated carboxyl group-containing photosensitive urethane resin. The photosensitive resin composition may contain one alkali-soluble urethane resin alone or two or more types in combination.

[0029] For example, in the case of the urethane resin (1), the urethane resin may be obtained by mixing and reacting a compound (a) having two or more isocyanate groups in one molecule, a compound (b) having two or more alcoholic hydroxy groups in one molecule, and a compound (c) having one alcoholic hydroxy group and one or more phenolic hydroxy groups in one molecule, all at once. Alternatively, the urethane resin may be obtained by reacting the compound (a) having two or more isocyanate groups in one molecule with the compound (b) having two or more alcoholic hydroxy groups in one molecule, followed by reaction with the compound (c) having one alcoholic hydroxy group and one or more phenolic hydroxy groups in one molecule, which also functions as a reaction terminator.

[0030] In the case of the urethane resin (2), it may be obtained by mixing and reacting a compound (a) having two or more isocyanate groups in one molecule, a compound (b) having a phenolic hydroxy group and / or one or more carboxy groups and two or more alcoholic hydroxy groups in one molecule, and a reaction terminator. From the viewpoint of molecular weight control, it is preferable to react the compound (a) having two or more isocyanate groups in one molecule with the compound (b), and then react with the reaction terminator.

[0031] The reaction proceeds without a catalyst by stirring and mixing at room temperature to 100°C, but it is preferable to heat to 70°C to 100°C to increase the reaction rate. The reaction ratio (molar ratio) of the components (a) to (c) may be (a):(b) = 1:1 to 2:1, preferably 1:1 to 1.5:1. The reaction ratio (molar ratio) of (a+b):(c) may be 1:0.01 to 0.5, preferably 1:0.02 to 0.3.

[0032] The compound (a) having two or more isocyanate groups in one molecule can be any of various conventionally known compounds having two or more isocyanate groups in one molecule, and is not limited to a specific compound. Specific examples of the compound (a) having two or more isocyanate groups in one molecule include aliphatic diisocyanates such as hexamethylene diisocyanate, branched aliphatic diisocyanates such as trimethylhexamethylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, (o, m, or p)-(hydrogenated)xylylene diisocyanate, methylenebis(cyclohexyl isocyanate), cyclohexane-1,3-dimethylene diisocyanate, and cyclohexane-1,4-dimethylene diisocyanate, and aromatic diisocyanates. Among these, the chain aliphatic diisocyanates of hexamethylene diisocyanate, which is an aliphatic diisocyanate, and trimethylhexamethylene diisocyanate, which is a branched aliphatic diisocyanate, are preferred. These compounds having two or more isocyanate groups in one molecule can be used alone or in combination of two or more. When these diisocyanate compounds are used, a cured product with excellent low warpage can be obtained.

[0033] The compound (b) having two or more alcoholic hydroxy groups in one molecule can be any of various conventionally known polyols, and is not limited to a specific compound. Suitable examples include polycarbonate polyols such as polycarbonate diols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, hydrogenated polybutadiene polyols, hydrogenated isoprene polyols, phosphorus-containing diols, bisphenol A alkylene oxide adduct diols, compounds having a carboxy group and an alcoholic hydroxy group, compounds having a phenolic hydroxy group and an alcoholic hydroxy group, and phosphorus-containing polyols. Examples of polycarbonate diols include polycarbonate diols (b-1) containing repeating units derived from at least one linear aliphatic diol as a structural unit, polycarbonate diols (b-2) containing repeating units derived from at least one alicyclic diol as a structural unit, and polycarbonate diols (b-3) containing repeating units derived from both linear aliphatic diols and alicyclic diols as structural units. Furthermore, when compounds (b-4) containing a carboxyl group and two or more alcoholic hydroxyl groups or compounds (b-5) containing a phenolic hydroxyl group and two or more alcoholic hydroxyl groups are used, functional groups (phenolic hydroxyl groups, carboxyl groups, etc.) can be provided on the molecular side chains. When phosphorus-containing polyols (b-6) are used, flame retardancy can be imparted to urethane resins. These compounds (b-1) to (b-6) can be used alone or in combination.

[0034] Specific examples of the polycarbonate diol (b-1) containing, as a constituent unit, a repeating unit derived from at least one kind of linear aliphatic diol include polycarbonate diol derived from 1,6-hexanediol, polycarbonate diol derived from 1,5-pentanediol and 1,6-hexanediol, polycarbonate diol derived from 1,4-butanediol and 1,6-hexanediol, polycarbonate diol derived from 3-methyl-1,5-pentanediol and 1,6-hexanediol, and polycarbonate diol derived from 1,9-nonanediol and 2-methyl-1,8-octanediol.

[0035] Specific examples of the polycarbonate diol (b-2) containing, as a constituent unit, a repeating unit derived from at least one kind of alicyclic diol include polycarbonate diols derived from 1,4-cyclohexanedimethanol.

[0036] A specific example of the polycarbonate diol (b-3) containing repeating units derived from both a linear aliphatic diol and an alicyclic diol as constituent units is a polycarbonate diol derived from 1,6-hexanediol and 1,4-cyclohexanedimethanol.

[0037] Specific examples of the compound (b-4) having a carboxy group and two or more alcoholic hydroxy groups include dimethylolpropionic acid, dimethylolbutanoic acid, etc. By using these compounds having a carboxy group and two or more alcoholic hydroxy groups, it is possible to easily introduce a carboxy group into the urethane resin.

[0038] Specific examples of the compound (b-5) having a phenolic hydroxy group and two or more alcoholic hydroxy groups include 6-hydroxy-5-methyl-1,3-benzenedimethanol, 2,4-bis(hydroxymethyl)-6-cyclohexylphenol, 3,3'-methylenebis(2-hydroxy-5-methyl-benzenemethanol), 4,4'-(1-methylethylidene)bis[2-methyl-6-hydroxymethylphenol], 4,4'-[1,4-phenylenebis(1-methylethylidene)bis[2-methyl-6-hydroxymethylphenol], 2 -Hydroxy-5-fluoro-1,3-benzenedimethanol, 4,4'-methylenebis(2-methyl-6-hydroxymethylphenol), 4,4'-methylenebis(2,5-dimethyl-3-hydroxymethylphenol), 4,4'-cyclohexylidenebis(2-methyl-6-hydroxymethylphenol), 4,4'-cyclohexylidenebis(2-cyclohexyl-6-hydroxymethylphenol), 2,6-bis[(2-hydroxy-3-hydroxymethyl-5-methylphenyl)methyl]-4-methylphenol, 2-hydroxy-5-en 2-hydroxy-4,5-dimethyl-1,3-benzenedimethanol, 2-hydroxy-5-(1-methylpropyl)-1,3-benzenedimethanol, 4-(1,1-dimethylethyl)-2-hydroxy-1,3-benzenedimethanol, 2-hydroxy-5-cyclohexyl-1,3-benzenedimethanol, 2-hydroxy-5-(1,1,3,3-tetramethylbutyl)-1,3-benzenedimethanol, 2,6-bis[(4-hydroxy-3-hydroxymethyl-2,5-dimethylphenyl)methyl]- Examples include 3,4-dimethylphenol, 2,6-bis[(4-hydroxy-3-hydroxymethyl-2,5-dimethylphenyl)methyl]-4-cyclohexylphenol, 2-hydroxy-1,3,5-benzenetrimethanol, 3,5-dimethyl-2,4,6-trihydroxymethylphenol, 4,4',4"-ethylidinetris(2-methyl-6-hydroxymethylphenol), 2,3,5,6-tetrakis(hydroxymethyl)-1,4-benzenediol, and 4,4'-methylenebis[2,6-bis(hydroxymethyl)phenol].By using these compounds having a phenolic hydroxy group and an alcoholic hydroxy group, the phenolic hydroxy group can be easily introduced into the urethane resin.

[0039] Polycarbonate diols containing repeating units derived from the linear aliphatic diols as structural units tend to have excellent properties such as low warpage and flexibility. Polycarbonate diols containing repeating units derived from alicyclic diols as structural units tend to have excellent properties such as tin plating resistance and solder heat resistance. From these perspectives, two or more of these polycarbonate diols can be used in combination, or a polycarbonate diol containing repeating units derived from both a linear aliphatic diol and an alicyclic diol as structural units can be used. By using a polycarbonate diol in which the copolymerization ratio of the linear aliphatic diol to the alicyclic diol is, for example, 3:7 to 7:3 by mass, it is possible to achieve a good balance between properties such as low warpage and flexibility and properties such as solder heat resistance and tin plating resistance.

[0040] The number average molecular weight of the polycarbonate diol may be, for example, 200 to 5,000. When the polycarbonate diol contains repeating units derived from a linear aliphatic diol and an alicyclic diol as constituent units and the copolymerization ratio of the linear aliphatic diol to the alicyclic diol is 3:7 to 7:3 by mass, the number average molecular weight may be 400 to 2,000.

[0041] Compound (c) having one alcoholic hydroxy group and one or more phenolic hydroxy groups per molecule is used for the purpose of introducing phenolic hydroxy groups into polyurethane, and also functions as an end-capping agent or reaction terminator for polyurethane. Specific examples of such compound (c) include hydroxymethylphenol, hydroxymethylcresol, hydroxymethyl-di-t-butylphenol, p-hydroxyphenyl-2-methanol, p-hydroxyphenyl-3-propanol, p-hydroxyphenyl-4-butanol, hydroxyethylcresol, 2,6-dimethyl-4-hydroxymethylphenol, 2,4-dimethyl-6-hydroxymethylphenol, 2,3,6-trimethyl-4-hydroxymethylphenol, 2-cyclohexyl-4-hydroxymethyl-5-methylphenol, 4-methyl-6-hydroxymethylbenzene-1,2-diol, 4-(1,1- Examples of the compound (c) include, but are not limited to, hydroxyalkylphenols or hydroxyalkylcresols such as (dimethylethyl)-6-hydroxymethylbenzene-1,2-diol; esters of phenols having a carboxyl group-containing substituent, such as hydroxybenzoic acid, hydroxyphenylbenzoic acid, or hydroxyphenoxybenzoic acid, with ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, or tripropylene glycol; monoethylene oxide adducts of bisphenols, monopropylene oxide adducts of bisphenols, and p-hydroxyphenethyl alcohol. These compounds (c) can be used alone or in combination of two or more.

[0042] Considering the developability and resist pattern drawability when using a weak alkaline developer such as an aqueous sodium carbonate solution, the acid value of the alkali-soluble urethane resin may be, for example, 30 mgKOH / g or more and 150 mgKOH / g or less, preferably 40 mgKOH / g or more, 50 mgKOH or more, or 80 mgKOH or more, and may be 120 mgKOH / g or less. The higher the acid value of the alkali-soluble urethane resin, the more improved the developability tends to be. When the acid value of the alkali-soluble urethane resin is below the upper limit, excessive dissolution of the exposed area by the developer is suppressed, and dissolution and peeling by the developer without distinction between the exposed area and the unexposed area is suppressed.

[0043] The alkali-soluble urethane resins obtained using the above-mentioned compounds having two or more isocyanate groups per molecule can be used alone or in combination of two or more. The weight-average molecular weight of the alkali-soluble urethane resin may be, for example, 500 to 100,000, preferably 8,000 to 50,000. Here, the weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography. When the weight-average molecular weight of the alkali-soluble urethane resin is 500 or more, the cured film tends to have good elongation, flexibility, strength, etc. On the other hand, when the weight-average molecular weight is 100,000 or less, the solubility in solvents is good, and the viscosity of the solution tends not to be too high.

[0044] The photosensitive resin composition may further contain, in addition to the alkali-soluble urethane resin, a second alkali-soluble resin that does not contain a urethane structure in its molecule. The photosensitive resin composition may contain one type of second alkali-soluble resin alone, or two or more types in combination.

[0045] Examples of the second alkali-soluble resin other than the alkali-soluble urethane resin include the following carboxy group-containing resins.

[0046] (1) Carboxy group-containing resins obtained by copolymerizing unsaturated carboxylic acids such as (meth)acrylic acid with unsaturated group-containing compounds such as styrene, α-methylstyrene, lower alkyl (meth)acrylates, and isobutylene.

[0047] (2) 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.

[0048] (3) A carboxyl group-containing photosensitive resin in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin to form a multifunctional epoxy resin, which is then reacted with (meth)acrylic acid, and a dibasic acid anhydride is added to the resulting hydroxyl groups.

[0049] (4) Carboxy 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.

[0050] (5) 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 hydroxy group and one phenolic hydroxy 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 hydroxy group of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

[0051] (6) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxy 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.

[0052] (7) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxy 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.

[0053] (8) 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 the resins (1) to (7).

[0054] Considering the developability and drawability of the resist pattern when using a weak alkaline developer such as an aqueous sodium carbonate solution, the acid value of the second alkali-soluble resin may be, for example, in the range of 30 mgKOH / g or more and 150 mgKOH / g or less, and preferably in the range of 50 mgKOH / g or more and 120 mgKOH / g or less. The higher the acid value of the second alkali-soluble resin, the more improved the developability tends to be. When the acid value of the second alkali-soluble resin is equal to or less than the upper limit, excessive dissolution of the exposed area by the developer is suppressed, and dissolution and peeling of the exposed area and the unexposed area by the developer without distinction is suppressed.

[0055] The weight-average molecular weight of the second alkali-soluble resin varies depending on the resin skeleton, but may generally be in the range of 2,000 to 150,000, preferably 5,000 to 100,000. By using a second alkali-soluble resin with a weight-average molecular weight of 2,000 or more, resolution, tack-free performance, etc. can be improved. Furthermore, by using a second alkali-soluble resin with a weight-average molecular weight of 150,000 or less, developability, storage stability, etc. can be improved. The weight-average molecular weight can be measured by gel permeation chromatography (GPC).

[0056] The total content of alkali-soluble resins in the photosensitive resin composition, calculated as solid content relative to the total solid content of the photosensitive resin composition, may be, for example, 10% by mass to 60% by mass, preferably 15% by mass to 55% by mass, and more preferably 20% by mass to 50% by mass. When the total content of alkali-soluble resins in the photosensitive resin composition is within the above range, the composition tends to exhibit better alkali developability. The content of alkali-soluble urethane resins relative to the total amount of alkali-soluble resins in the photosensitive resin composition, calculated as solid content, may be, for example, 8% by mass to 75% by mass, preferably 10% by mass to 60% by mass, and more preferably 20% by mass to 50% by mass. When the content of alkali-soluble urethane resins relative to the total amount of alkali-soluble resins is within the above range, the composition tends to exhibit better alkali developability and to further reduce development residues.

[0057] The photosensitive resin composition contains a thermosetting component. The inclusion of the thermosetting component is expected to improve the heat resistance of the cured product of the photosensitive resin composition. The thermosetting component may be used alone or in combination of two or more. Any known thermosetting component can be used. For example, known thermosetting components such as amino resins such as melamine resins, benzoguanamine resins, melamine derivatives, and benzoguanamine derivatives, isocyanate compounds, blocked isocyanate compounds, cyclocarbonate compounds, epoxy compounds, oxetane compounds, episulfide resins, bismaleimides, and carbodiimide resins can be used. Particularly preferred are thermosetting components having multiple cyclic ether groups or cyclic thioether groups (hereinafter, sometimes collectively referred to as cyclic (thio)ether groups) in the molecule.

[0058] The thermosetting component having multiple cyclic (thio)ether groups in the molecule is a compound having multiple 3-, 4-, or 5-membered cyclic (thio)ether groups in the molecule, and examples thereof include a compound having multiple epoxy groups in the molecule, i.e., a polyfunctional epoxy compound, a compound having multiple oxetanyl groups in the molecule, i.e., a polyfunctional oxetane compound, and a compound having multiple thioether groups in the molecule, i.e., an episulfide resin.

[0059] Examples of polyfunctional epoxy compounds include bisphenol A type epoxy resins, hydroquinone type epoxy resins, bisphenol type epoxy resins, thioether type epoxy resins, brominated epoxy resins, novolac type epoxy resins, biphenol novolac type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, glycidylamine type epoxy resins, hydantoin type epoxy resins, alicyclic epoxy resins, trihydroxyphenylmethane type epoxy resins, bixylenol type or biphenol type epoxy resins or mixtures thereof, bisphenol Examples of epoxy resins include, but are not limited to, phenol S-type epoxy resins, bisphenol A novolac-type epoxy resins, tetraphenylolethane-type epoxy resins, heterocyclic epoxy resins, diglycidyl phthalate resins, tetraglycidyl xylenoylethane resins, naphthalene group-containing epoxy resins, epoxy resins having a dicyclopentadiene skeleton, glycidyl methacrylate copolymer epoxy resins, cyclohexylmaleimide and glycidyl methacrylate copolymer epoxy resins, epoxy-modified polybutadiene rubber derivatives, and CTBN-modified epoxy resins. These epoxy resins may be used alone or in combination of two or more.

[0060] Examples of polyfunctional oxetane compounds include bis[(3-methyl-3-oxetanylmethoxy)methyl]ether, bis[(3-ethyl-3-oxetanylmethoxy)methyl]ether, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, (3-methyl-3-oxetanyl)methyl acrylate, and (3-ethyl-3-oxetanyl)methyl acrylate. Examples of suitable oxetane compounds include polyfunctional oxetanes such as acrylate, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and oligomers or copolymers thereof, as well as ethers of oxetane alcohols with novolak resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or resins having a hydroxy group such as silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring and alkyl (meth)acrylates.

[0061] Examples of compounds with multiple cyclic thioether groups in the molecule include bisphenol A episulfide resins. Using a similar synthesis method, episulfide resins can also be produced in which the oxygen atoms in the epoxy groups of novolac epoxy resins are replaced with sulfur atoms.

[0062] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylolmelamine compounds, methylolbenzoguanamine compounds, methylolglycoluril compounds, and methylolurea compounds.

[0063] The isocyanate compound may be a polyisocyanate compound, such as aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and 2,4-tolylene dimer; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), and isophorone diisocyanate; alicyclic polyisocyanates such as bicycloheptane triisocyanate; and adducts, biuret compounds, and isocyanurates of the above-mentioned isocyanate compounds.

[0064] The blocked isocyanate compound can be an addition reaction product of an isocyanate compound and an isocyanate blocking agent. Examples of isocyanate compounds that can react with an isocyanate blocking agent include the polyisocyanate compounds described above. Examples of the isocyanate blocking agent include phenol-based blocking agents, lactam-based blocking agents, active methylene-based blocking agents, alcohol-based blocking agents, oxime-based blocking agents, mercaptan-based blocking agents, acid amide-based blocking agents, imide-based blocking agents, amine-based blocking agents, imidazole-based blocking agents, and imine-based blocking agents.

[0065] The content of the thermosetting component in the photosensitive resin composition may be such that the number of functional groups in the thermosetting component that reacts with 1 mole of carboxyl groups contained in the alkali-soluble resin is 0.5 to 2.5 moles, preferably 0.8 to 2.0 moles. The ratio of the content of the thermosetting component to the total content of the alkali-soluble resin in the photosensitive resin composition, calculated on a solids basis, may be, for example, 0.2 to 2, preferably 0.3 to 1. When the content of the thermosetting component is within the above range, the storage stability of the photosensitive resin composition and the strength of the coating film tend to be better.

[0066] The photosensitive resin composition may contain a thermosetting catalyst, such as 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 catalysts include 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all trade names of imidazole-based compounds) manufactured by Shikoku Chemical Industry Co., Ltd., and U-CAT3513N (trade name of dimethylamine-based compound), DBU, DBN, and U-CATSA102 (all bicyclic amidine compounds and salts thereof) manufactured by San-Apro Co., Ltd. The thermosetting catalyst is not limited to these, and any catalyst may be used as long as it promotes the reaction of an epoxy resin, an oxetane compound, or at least one of an epoxy group and an oxetanyl group with a carboxy group, and one type may be used alone or two or more types may be used in combination.

[0067] Furthermore, 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 can also be used, and these compounds that also function as adhesion promoters are preferably used in combination with a heat curing catalyst.The heat curing catalyst may be used alone or in combination of two or more.

[0068] The content of the thermosetting catalyst in the photosensitive resin composition may be, for example, 0.1 to 10 parts by mass, preferably 1 to 8 parts by mass, based on 100 parts by mass of the alkali-soluble resin, calculated as solid content. When the content is 0.1 part by mass or more, the heat resistance is more excellent. When the content is 10 parts by mass or less, the storage stability tends to be further improved.

[0069] The photosensitive resin composition may contain a polymerizable compound having an ethylenically unsaturated bond (hereinafter also referred to as a photopolymerizable monomer). Examples of the photopolymerizable monomer include alkyl (meth)acrylates such as 2-ethylhexyl (meth)acrylate and cyclohexyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; mono- or di(meth)acrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, and dipentaerythritol. Examples of the photopolymerizable monomer include polyhydric (meth)acrylates of polyhydric alcohols such as tris(hydroxyethyl)isocyanurate or their ethylene oxide or propylene oxide adducts; (meth)acrylates of ethylene oxide or propylene oxide adducts of phenols such as phenoxyethyl (meth)acrylate and polyethoxydi(meth)acrylate of bisphenol A; (meth)acrylates of glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether and triglycidyl isocyanurate; and melamine (meth)acrylate. The photopolymerizable monomer may be used alone or in combination of two or more.

[0070] The content of the photopolymerizable monomer in the photosensitive resin composition may be, for example, 0.1 to 40 parts by mass, calculated as solid content, relative to 100 parts by mass of the total amount of the alkali-soluble resin. When the content of the photopolymerizable monomer is 0.1 parts by mass or more, the photocurability is good and pattern formation is easy in alkaline development after irradiation with active energy rays. On the other hand, when the content of the photopolymerizable monomer is 40 parts by mass or less, halation is less likely to occur and better resolution can be obtained.

[0071] The photosensitive resin composition may contain a photopolymerization initiator. Any known photopolymerization initiator may be used. The photopolymerization initiator may be used alone or in combination of two or more.

[0072] Specific examples of the photopolymerization initiator include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Sphingoxide, bisacylphosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, monoacylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 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, 2-hydroxy hydroxyacetophenones such as hydroxy-2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone, and N,N-dimethylaminoacetophenone; thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropyl Thioxanthones such as thioxanthone; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime); bis(η); 5 titanocenes such as bis(cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1H-pyrrol-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, and the like.

[0073] Commercially available α-aminoacetophenone photopolymerization initiators include Omnirad 907, 369, 369E, and 379 manufactured by IGMResins. Commercially available acylphosphine oxide photopolymerization initiators include Omnirad TPO and 819 manufactured by IGMResins. Commercially available oxime ester photopolymerization initiators include Irgacure OXE01 and OXE02 manufactured by BASF Japan Ltd., N-1919, ADEKA Arcures NCI-831 and NCI-831E manufactured by ADEKA Corporation, and TR-PBG-304 manufactured by Changzhou New Advanced Electronic Materials Co., Ltd.

[0074] Other examples include carbazole oxime ester compounds described in JP-A Nos. 2004-359639, 2005-097141, 2005-220097, 2006-160634, 2008-094770, JP-T Nos. 2008-509967, 2009-040762, and 2011-80036.

[0075] The content of the photopolymerization initiator in the photosensitive resin composition may be, for example, 0.01 to 30 parts by mass, calculated as solid content, relative to 100 parts by mass of the total amount of the alkali-soluble resin. When the content of the photopolymerization initiator is 0.01 parts by mass or more, the photocurability of the photosensitive resin composition is good, and coating properties such as chemical resistance are also good. On the other hand, when the content of the photopolymerization initiator is 30 parts by mass or less, the effect of reducing outgassing is obtained, and further, light absorption at the surface of the resist film (cured coating) is good, and deep curing is less likely to decrease.

[0076] The photosensitive resin composition may contain a photoinitiator aid or sensitizer in combination with the photopolymerization initiator. Examples of the photoinitiator aid or sensitizer include benzoin compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. Thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone are particularly preferred. The inclusion of a thioxanthone compound can improve deep curing properties. While these compounds may be used as photopolymerization initiators, they are preferably used in combination with the photopolymerization initiator. The photoinitiator aid or sensitizer may be used alone or in combination of two or more.

[0077] These photopolymerization initiators, photoinitiator assistants, and sensitizers absorb light of specific wavelengths, which may reduce sensitivity in some cases and function as ultraviolet absorbers. However, these are not used solely for the purpose of improving the sensitivity of the resin composition. By absorbing light of specific wavelengths as needed, they can increase the photoreactivity of the surface, change the line shape and openings of the resist pattern to vertical, tapered, or reverse tapered, and improve the accuracy of the line width and opening diameter.

[0078] The photosensitive resin composition may contain an inorganic filler. One type of inorganic filler may be used alone, or two or more types may be used in combination. Any inorganic filler usable as a filler for electronic materials may be used. Examples of inorganic fillers include silica, crystalline silica, Neuburg silica, aluminum hydroxide, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, aluminum hydroxide, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, and zinc oxide. Preferred inorganic fillers include silica and barium sulfate, and the composition may contain at least one selected from the group consisting of these. The inorganic filler may contain at least silica and barium sulfate.

[0079] The average particle size of the inorganic filler may be, for example, 10 nm to 1000 nm, preferably 200 nm to 800 nm. The average particle size of the inorganic filler refers to the volume-average particle size (D50) including not only the particle size of primary particles but also the particle size of secondary particles (aggregates), and is the D50 value measured by laser diffraction. An example of a measuring device using laser diffraction is the MicrotracMT3300EXII manufactured by Microtrac-Bell Corporation. The maximum particle size (D100) and particle size (D10) can also be measured using the above device. The average particle size of the inorganic filler contained in the photosensitive resin composition refers to the value measured as described above for the inorganic filler before preparing (pre-stirring, kneading) the photosensitive resin composition.

[0080] When silica is used as the inorganic filler, the average particle size of the silica may be, for example, 300 nm or more and 1000 nm or less, preferably 500 nm or more and 700 nm or less. When barium sulfate is used as the inorganic filler, the average particle size of the barium sulfate may be, for example, 100 nm or more and 800 nm or less, preferably 200 nm or more and 400 nm or less. When silica and barium sulfate are used as the inorganic filler, the ratio of the average particle size of the silica to the average particle size of the barium sulfate may be, for example, 1 or more and 5 or less, preferably 1.5 or more or 3 or less.

[0081] It is preferable to use spherical silica as the inorganic filler. The method for producing spherical silica is not particularly limited, and methods known to those skilled in the art can be applied. For example, spherical silica can be produced by burning silicon powder using the VMC (Vaporized Metal Combustion) method. The VMC method involves forming a chemical flame using a burner in an oxygen-containing atmosphere, adding a metal powder that constitutes part of the target oxide particles into the chemical flame in an amount sufficient to form a dust cloud, and causing a deflagration to occur, thereby obtaining oxide particles.

[0082] Examples of commercially available spherical silica include ADMAFINE SO-C2 and SO-E2 manufactured by Admatechs Co., Ltd., SFP-20M and SFP-30M manufactured by Denka Co., Ltd., Admanano manufactured by Admatechs Co., Ltd., UFP-30 manufactured by Denka Co., Ltd., the Seahoster series manufactured by Nippon Shokubai Co., Ltd., the Sciqas series manufactured by Sakai Chemical Industry Co., Ltd., and SG-SO100 manufactured by Kyoritsu Material Co., Ltd.

[0083] There is no particular limitation on whether the inorganic filler is surface-treated. Since the photosensitive resin composition is highly filled with inorganic filler and has a relatively low resin content, it is preferable that the inorganic filler is surface-treated to improve dispersibility. By using a surface-treated inorganic filler, aggregation can be suppressed. When two or more inorganic fillers are used in combination, only one of the inorganic fillers may be surface-treated, or all of the inorganic fillers may be surface-treated.

[0084] The surface treatment method of the inorganic filler is not particularly limited, and any known or commonly used method may be used, but it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a curable reactive group, such as a coupling agent having a curable reactive group as an organic group. As the coupling agent, silane-based, titanate-based, aluminate-based, zircoaluminate-based coupling agents can be used. Among them, silane-based coupling agents are preferred. Examples of such silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These can be used alone or in combination. These silane coupling agents are preferably immobilized on the surface of spherical silica by adsorption or reaction. Here, the amount of coupling agent to be treated per 100 parts by mass of inorganic filler may be, for example, from 1 part by mass to 10 parts by mass. Note that the reactive functional groups derived from the coupling agent applied to the inorganic filler are not included in the compounds having photocurable reactive groups or thermosetting functional groups.

[0085] Examples of the photocurable reactive group include ethylenically unsaturated groups such as vinyl, styryl, methacryl, and acrylic groups, among which at least one of vinyl and (meth)acrylic groups is preferred.

[0086] Examples of the thermosetting reactive group include a hydroxy group, a carboxy group, an isocyanate group, an amino group, an imino group, an epoxy group, an oxetanyl group, a mercapto group, a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, an oxazole group, etc. Among these, at least one of an amino group and an epoxy group is preferred.

[0087] The surface-treated inorganic filler may be contained in the photosensitive resin composition in a surface-treated state, and the inorganic filler may be surface-treated in the composition by separately blending a surface-untreated inorganic filler and a surface treatment agent, or it is preferable to blend an inorganic filler that has been surface-treated in advance. When the surface is treated in advance, it is preferable to blend a pre-dispersion in which the inorganic filler is pre-dispersed in a solvent and a curable component, and it is more preferable to pre-disperse the surface-treated inorganic filler in a solvent and then blend this pre-dispersion in the composition, or to sufficiently surface-treat the surface-untreated inorganic filler when pre-dispersing it in a solvent, and then blend this pre-dispersion in the composition.

[0088] Depending on the mode of use of the photosensitive resin composition, the inorganic filler may be mixed with the alkali-soluble resin or the like in a powder or solid state, or may be mixed with a solvent and a dispersant to form a slurry, which is then mixed with the alkali-soluble resin or the like.

[0089] The content of the inorganic filler in the photosensitive resin composition may be 5% by mass or more and 90% by mass or less, preferably 10% by mass or more, 15% by mass or more, or 20% by mass or more, and preferably 80% by mass or less, 70% by mass or less, or 60% by mass or less, based on the total solid content of the photosensitive resin composition. When the content of the inorganic filler is 5% by mass or more, the cured product can have high strength and high rigidity and a low coefficient of linear expansion (CTE).

[0090] When silica is used as the inorganic filler, from the viewpoint of the linear expansion coefficient, the content of silica in the photosensitive resin composition may be 5% by mass or more and 90% by mass or less, and preferably 8% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, converted into solid content, and may be preferably 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0091] The photosensitive resin composition may contain a colorant. As the colorant, a commonly used and known colorant such as red, blue, green, yellow, white, or black can be used, and any of a pigment, dye, and coloring matter can be used.

[0092] Specifically, the following colors may be given the Color Index (CI; published by The Society of Dyers and Colorists) numbers:

[0093] Red colorants include monoazo, disazodisazo, azolake, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone. Blue colorants include phthalocyanine and anthraquinone, and pigment compounds classified as pigments can be used. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Green colorants include phthalocyanine, anthraquinone, and perylene. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Yellow colorants include monoazo, disazo, condensed azo, benzimidazolone, isoindolinone, and anthraquinone. White colorants include rutile or anatase titanium oxide. Examples of black colorants include carbon black, graphite, iron oxide, titanium black, iron oxide, anthraquinone, cobalt oxide, copper oxide, manganese oxide, antimony oxide, nickel oxide, perylene, aniline, molybdenum sulfide, bismuth sulfide, etc. In addition, purple, orange, brown, etc. colorants may be added to adjust the color tone.

[0094] The content of the colorant in the photosensitive resin composition is preferably 0.1% by mass or more and 1.0% by mass or less, and more preferably 0.2% by mass or more and 0.5% by mass or less, calculated as solid content relative to the total solid content of the photosensitive resin composition. When the content of the colorant in the photosensitive resin composition is within the above range, the circuit hiding ability and the resolution tend to be improved.

[0095] The photosensitive resin composition may contain an organic solvent for the purpose of adjusting the viscosity when preparing the composition or when applying it to a substrate, film, or the like. 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 may be used alone or in combination of two or more.

[0096] The photosensitive resin composition may further contain, as necessary, components such as cyanate compounds, elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper inhibitors, antioxidants, rust inhibitors, thickeners such as finely divided silica, organic bentonite, and montmorillonite, at least one of silicone-based, fluorine-based, and polymer-based antifoaming agents and leveling agents, imidazole-based, thiazole-based, and triazole-based silane coupling agents, and flame retardants such as phosphinates, phosphate ester derivatives, and phosphorus compounds such as phosphazene compounds. These may be known in the field of electronic materials.

[0097] The photosensitive resin composition may be used in the form of a dry film or in a liquid form. When used in a liquid form, it may be one-component or two or more-component.

[0098] Photosensitive resin compositions are useful for forming pattern layers as permanent coatings on printed wiring boards, such as solder resists, coverlays, and interlayer insulating layers, and are particularly useful for forming solder resists. Furthermore, photosensitive resin compositions can form cured products that have excellent film strength and crack resistance even when thin, and therefore can be suitably used for forming pattern layers on printed wiring boards that require thinning, such as package substrates (printed wiring boards used in semiconductor packages). Furthermore, cured products obtained from the photosensitive resin compositions have excellent crack resistance, and therefore can be suitably used for forming pattern layers on package substrates on which stiffeners are mounted.

[0099] The photosensitive resin composition can also be in the form of a dry film comprising a first film (e.g., a support (carrier) film) and a resin layer consisting of a dried coating of the photosensitive resin composition formed on the first film. That is, the present invention may encompass a dry film as one embodiment. To form the dry film, the photosensitive resin composition is diluted with an organic solvent to adjust the viscosity appropriately, and then coated onto the first film in 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. The dried coating is typically obtained by drying at a temperature of 50°C to 130°C for 1 minute to 30 minutes. The thickness of the coating film is not particularly limited, but may be, for example, 1 μm to 150 μm after drying, preferably selected from the range of 10 μm to 60 μm.

[0100] 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.

[0101] Furthermore, from the viewpoint of improving mechanical strength, the thermoplastic resin film as described above is preferably uniaxially stretched. Alternatively, it is preferably a biaxially stretched film.

[0102] The thickness of the first film is not particularly limited, but may be, for example, 10 μm or more and 150 μm or less.

[0103] After forming a resin layer consisting of a dried coating film of a photosensitive resin composition on a first film, it is preferable to further laminate a peelable second film (e.g., a protective (cover) film) on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer. Examples of the peelable second film that can be used include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper, and any film can be used 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.

[0104] The thickness of the second protective film is not particularly limited, but may be, for example, 10 μm or more and 150 μm or less.

[0105] To prepare a cured coating on a printed wiring board using a dry film, the second film is peeled off from the dry film, and the exposed resin layer of the dry film is placed on a substrate with a circuit formed thereon, and the two are bonded together using a laminator or the like to form a resin layer on the substrate with a circuit formed thereon. The formed resin layer is then exposed to light, developed, and heat-cured to form a cured coating. The first film can be peeled off either before or after exposure.

[0106] The present invention may include a cured product as one embodiment. The cured product is obtained by curing the above-mentioned photosensitive resin composition or the resin layer of the above-mentioned dry film. The linear expansion coefficient of a 25 μm-thick test piece of the cured product may be greater than 5 ppm / °C and less than 35 ppm / °C at 0°C, and greater than 5 ppm / °C and less than 30 ppm / °C at -30°C, when measured with a test load of 5 g, after heating from room temperature to 260°C at a rate of 10°C / min, cooling from 260°C to -70°C at a rate of 5°C / min, and then heating at a rate of 10°C / min. The linear expansion coefficient of the cured product may preferably be less than 30 ppm / °C at 0°C and less than 25 ppm / °C at -30°C. The glass transition temperature of the cured product may be 150°C or higher.

[0107] One embodiment of the present invention may include an electronic component having a cured product. Here, the term "electronic component" refers to a component used in an electronic circuit, and includes active components such as printed wiring boards, particularly flip-chip ball grid array (FC-BGA) wiring boards, transistors, light-emitting diodes, and laser diodes, as well as passive components such as resistors, capacitors, inductors, and connectors. The cured product of the photosensitive resin composition is suitable as a solder resist for these components.

[0108] In a printed wiring board having a cured product of the photosensitive resin composition as a solder resist, the occurrence of cracks can be effectively suppressed regardless of whether a stiffener is mounted or not. [Example]

[0109] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" are by mass.

[0110] [Synthesis Example 1] Preparation of alkali-soluble resin A solution (varnish A) Into an autoclave equipped with a thermometer, a nitrogen inlet, an alkylene oxide inlet, and a stirrer, 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, 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 temperature was raised to 125 to 132°C and 0 kgf / cm. 2 to 4.8 kgf / cm 2 The mixture was reacted for 16 hours under a gauge pressure of 0.05 gage. Thereafter, the mixture was cooled to room temperature, and 1.56 parts by mass of 89% phosphoric acid was added to the reaction solution. The potassium hydroxide was neutralized with mixing to obtain a propylene oxide reaction solution of a novolak cresol resin [solid content: 62.1%; hydroxyl value: 182.2 mg KOH / g (307.9 g / eq.)]. This propylene oxide reaction solution had an average of 1.08 moles of propylene oxide added per equivalent of phenolic hydroxy group.

[0111] 293.0 parts by weight of the resulting propylene oxide reaction solution of novolac cresol resin, 43.2 parts by weight of acrylic acid, 11.53 parts by weight of methanesulfonic acid, 0.18 parts by weight of methylhydroquinone, and 252.9 parts by weight 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 weight of water produced by the reaction was distilled off as an azeotrope with toluene. The mixture was then cooled to room temperature, neutralized with 35.35 parts by weight of 15% aqueous sodium hydroxide solution, and then washed with water. The mixture was then distilled off while replacing the toluene with 118.1 parts by weight of diethylene glycol monoethyl ether acetate in an evaporator, yielding a novolac acrylate resin solution. Next, 332.5 parts by mass of the obtained 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, and 60.8 parts by mass of tetrahydrophthalic anhydride was gradually added while blowing air at a rate of 10 ml / min and stirring. The mixture was reacted 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%; acid value of solid content: 87.7 mg KOH / g) was obtained.

[0112] [Synthesis Example 2] Preparation of alkali-soluble urethane resin B solution (varnish B) A reaction vessel equipped with a stirrer, thermometer, and condenser was charged with 360 g (0.45 mol) of a polycarbonate diol (PCDL800, number average molecular weight 800, manufactured by Ube Industries, Ltd.) derived from 1,5-pentanediol and 1,6-hexanediol as a compound having two or more alcoholic hydroxyl groups, 81.4 g (0.55 mol) of dimethylol butanoic acid, and 22.1 g (0.16 mol) of hydroxyphenylethyl alcohol as a compound having one alcoholic hydroxyl group and one or more phenolic hydroxyl groups per molecule. Next, 200.9 g (1.08 mol) of trimethylhexamethylene diisocyanate as a compound having an isocyanate group not directly bonded to an aromatic ring was charged, and the mixture was heated to 60 °C with stirring. The temperature in the reaction vessel began to decrease, and the mixture was heated again at 80 °C and continued stirring. The absorption spectrum of the isocyanate group (2280 cm) was measured by infrared absorption spectroscopy. -1 The reaction was terminated after confirming that the carboxyl group had disappeared. Carbitol acetate was then added so that the solids content was 50% by mass, yielding a viscous liquid containing a diluent, carboxyl group-containing urethane resin (varnish B) having phenolic hydroxy groups at its terminals. The acid value of the solids of the resulting carboxyl group-containing urethane resin having phenolic hydroxy groups at its terminals was 48.8 mg KOH / g.

[0113] [Preparation example] Preparation of surface-treated inorganic fillers A surface-treated inorganic filler (solid content 70%) was obtained by uniformly dispersing 70 g of spherical silica (SFP-30M manufactured by Denka Co., Ltd., average particle size: 600 nm), 28 g of propylene glycol monomethyl ether acetate (PMA), and 2 g of a silane coupling agent having a methacrylic group (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.).

[0114] Preparation of photosensitive resin composition The photosensitive resin compositions of the Examples and Comparative Examples were prepared by blending the various components shown in Table 1 in the indicated proportions (parts by mass) using the above-mentioned varnish as the alkali-soluble resin, premixing in a stirrer, and then kneading in a bead mill. The stirring conditions for the stirrer were a rotation speed of 800 rpm, a stirring time of 10 min, and a stirrer blade of 12 cm. A conical bead mill K-8 (manufactured by Buhler) was used, and the kneading conditions were zirconia beads, a rotation speed of 1000 rpm, a discharge rate of 20%, a bead particle diameter of 0.65 mm, and a filling rate of 88%. The values ​​in Table 1 are the blend amounts in parts by mass in a solution containing solids and solvent.

[0115] [Table 1]

[0116] In addition, ingredients *1 to *8 in Table 1 are as follows. *1: Polyurethane resin (manufactured by Nippon Kayaku Co., Ltd., product name "UXE-3000", weight average molecular weight = 7,500, acid value = 100, solid content 65%) *2: Acylphosphine oxide photoinitiator (IGM Resins Omnirad 819) *3: Barium sulfate (Sakai Chemical Industry Co., Ltd., D50 = 300 nm) *4: Dipentaerythritol hexaacrylate (manufactured by Sanyo Chemical Industries, Ltd.) *5: Phenol novolac epoxy resin (DIC Corporation) *6: Melamine (D50 = 0.5 μm, solid content 55%) *7: Dicyandiamide (Mitsubishi Chemical Corporation, solid content 73%) *8: A mixture of phthalocyanine blue and PIGMENT Yellow 147 (57:43 content, 10% solids)

[0117] Dry film preparation The photosensitive resin compositions of the Examples and Comparative Examples prepared above were each applied using an applicator to the entire surface of a polyethylene terephthalate film (TN-100, manufactured by Toyobo Co., Ltd.) measuring 150 mm × 95 mm and having a thickness of 38 μm, and then dried at 80°C for 10 minutes in a hot air circulation drying oven (DF610, manufactured by Yamato Chemical Co., Ltd.) to produce a dry film having a photosensitive resin layer having a thickness of 25 μm.

[0118] Evaluation of the cured product (1) Coefficient of linear expansion (CTE) and glass transition temperature (Tg) The resin layer of each dry film obtained in the Examples and Comparative Examples was laminated onto the glossy side of a 150mm x 95mm, 18μm-thick copper foil (FV-WS, manufactured by Furukawa Sangyo Co., Ltd.) using a vacuum laminator (CVP-300, manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds. Exposure was then carried out using an exposure device (Ushio Inc., UFX-2223M-APU01) equipped with a high-pressure mercury lamp. The exposure dose was adjusted using a step tablet (Photec 41 step) to achieve 10 steps of gloss sensitivity. The polyethylene terephthalate film was then peeled off from the dry film to expose the exposed photosensitive resin layer. A 1% by mass aqueous sodium carbonate (Na2CO3) solution at 30°C was sprayed at a pressure of 2 kg / cm. 2 The resulting solution was sprayed for 60 seconds under the conditions of 1000 mJ / cm 2 and developed to obtain a cured film pattern measuring 3 mm x 10 mm. 2The coating was then irradiated with UV light and then heated at 150°C for 1 hour to cure, yielding a cured coating. The copper foil was peeled off from the resulting cured coating to prepare a measurement sample. The coefficient of linear expansion (CTE) of the resulting sample was measured in tensile mode using a thermomechanical analysis (TMA) measuring device (Q400EM, manufactured by TA Instruments). The measurement conditions were a test load of 5 g, a temperature increase from room temperature to 260°C at a rate of 10°C / min, a decrease from 260°C to -70°C at a rate of 5°C / min, and a temperature increase at a rate of 10°C / min. The coefficient of linear expansion (CTE(α1)) at a given temperature and the glass transition temperature (Tg) were determined as the intersection of the tangents at 100°C and 250°C of the linear expansion curve. The coefficient of linear expansion (CTE) and glass transition temperature (Tg) at 0°C and -30°C were evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0119] Evaluation criteria for coefficient of linear expansion (CTE) at 0°C A: More than 5 ppm / ℃ and less than 30 ppm / ℃ B: Greater than 30 ppm / ℃ and less than or equal to 35 ppm / ℃ C: Greater than 35 ppm / ℃

[0120] Evaluation criteria for coefficient of linear expansion (CTE) at -30°C A: Greater than 5 ppm / ℃ and less than 25 ppm / ℃ B: More than 25 ppm / ℃ and less than 30 ppm / ℃ C: Greater than 30 ppm / ℃

[0121] Glass transition temperature (Tg) evaluation criteria A: Higher than 170℃ B: Higher than 150℃ and lower than 170℃ C: Below 150℃

[0122] Crack resistance evaluation Each dry film obtained in the examples and comparative examples was laminated onto an FC-BGA evaluation board formed with a pad pitch of 200 μm using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds. After adjusting the exposure dose using a step tablet (Photec 41 step) so that the gloss sensitivity was 10 steps, direct imaging exposure was performed with an opening size of 80 μm. The polyethylene terephthalate film was then peeled off from the dry film, exposing the exposed photosensitive resin layer, and a 1% by mass aqueous sodium carbonate solution at 30°C was sprayed at a pressure of 2 kg / cm. 2 The resulting solution was sprayed for 60 seconds under the conditions of 1000 mJ / cm 2 and developed to obtain a cured film pattern. 2 The cured film was then irradiated with ultraviolet light and then heated to 150°C for 1 hour for curing. Gold plating, solder bump formation, and Si chip mounting were then performed on evaluation boards. Evaluation board 1, which did not have a stiffener, and evaluation board 2, which had a stainless steel (SUS) stiffener (1 mm thick, 5 mm wide, 50 mm x 50 mm with a 25 mm x 25 mm opening in the center), were then obtained. The evaluation boards obtained above were placed in a thermal cycler that cycled temperatures between -65°C and 150°C, and a thermal cycle test (TCT) was performed. The surface of the cured film was observed after 500 cycles and 1000 cycles, and evaluated according to the following criteria. The results are shown in Table 1.

[0123] Evaluation criteria A: The number of cracks generated after 1000 cycles was less than 50. B: The number of cracks generated after 500 cycles was less than 50, or the number of cracks generated after 1000 cycles was 50 or more. C: 50 or more cracks occurred after 500 cycles.

[0124] Developability evaluation FR-4 (a copper-clad laminate with dimensions of 150 mm x 95 mm, thickness of 1.6 mm, and copper foil thickness of 35 μm) was subjected to a copper etching treatment equivalent to 1.0 μm using a microetching agent (CZ-8101B) manufactured by MEC Corporation. Each dry film obtained in the Examples and Comparative Examples was laminated onto the etched copper foil using a vacuum laminator (CVP-300, manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, followed by pressing under conditions of a pressure of 0.5 MPa and a pressing time of 30 seconds. Next, exposure was performed using an exposure device equipped with a high-pressure mercury lamp with each aperture pattern. The exposure dose was adjusted using a step tablet (Photec 41 step) to achieve a gloss sensitivity of 10 steps, and then the polyethylene terephthalate film was peeled off from the dry film to expose the exposed photosensitive resin layer. A 1% by mass aqueous sodium carbonate solution at 30°C was then sprayed at a pressure of 2 kg / cm. 2 The development was carried out by spraying for 60 seconds under the conditions of (1). After development, the substrate was observed and evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0125] Evaluation criteria A: Developable without residue. B: There was residue.

[0126] Resolution evaluation A copper-clad laminate with 1.6 mm thick FR-4 and 35 μm thick copper foil was subjected to a copper etching treatment equivalent to 1.0 μm using a microetching agent (CZ-8101B) manufactured by MEC Corporation. Each dry film obtained in the Examples and Comparative Examples was laminated onto the etched copper foil using a vacuum laminator (CVP-300, manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, followed by pressing under conditions of a pressure of 0.5 MPa and a pressing time of 30 seconds. The exposure dose was adjusted using a step tablet (Photec 41 step) to achieve a gloss sensitivity of 10 steps, after which the polyethylene terephthalate film was peeled off from the photosensitive dry film to expose the exposed photosensitive resin layer. Then, a 1% by mass aqueous sodium carbonate solution at 30°C was sprayed at a pressure of 2 kg / cm. 2The substrate having the resulting cured film pattern was then subjected to UV irradiation in a UV conveyor furnace at an integrated exposure dose of 2000 mJ / cm. 2 After irradiating with ultraviolet light under the conditions above, the composition was heat-cured at 150°C for 60 minutes. The openings in the resulting cured product were observed under a scanning electron microscope (SEM) at a magnification of 1500x, and the shape of the openings was evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0127] Evaluation criteria A: It was straight or tapered. B: The opening was undercut or had a protruding central part.

[0128] It can be seen from Table 1 that the photosensitive resin compositions according to the examples are capable of forming patterns with reduced development residues and suppressing the occurrence of cracks in the cured film.

Claims

1. a photosensitive resin composition containing an alkali-soluble resin, a thermosetting component, a polymerizable compound having an ethylenically unsaturated group, a photopolymerization initiator, and an inorganic filler; the alkali-soluble resin includes an alkali-soluble urethane resin, and the content of the alkali-soluble urethane resin relative to the total content of the alkali-soluble resin is 8% by mass or more and 75% by mass or less; The photosensitive resin composition has a linear expansion coefficient of more than 5 ppm / °C and not more than 35 ppm / °C at 0°C and more than 5 ppm / °C and not more than 30 ppm / °C at -30°C, when the linear expansion coefficient of a 25 μm-thick cured product obtained by curing the photosensitive resin composition is measured under a test load of 5 g, by heating from room temperature to 260°C at a rate of 10°C / min, then cooling from 260°C to -70°C at a rate of 5°C / min, and then increasing the temperature at a rate of 10°C / min.

2. The photosensitive resin composition according to claim 1 , wherein the inorganic filler comprises silica.

3. 3. The photosensitive resin composition according to claim 2, wherein the content of the silica is 15% by mass or more and 60% by mass or less based on the total solid content of the photosensitive resin composition.

4. 2. The photosensitive resin composition according to claim 1, wherein the content of the alkali-soluble urethane resin relative to the total content of the alkali-soluble resins is 8% by mass or more and 60% by mass or less.

5. The photosensitive resin composition according to claim 1, wherein the cured product has a glass transition temperature of 150°C or higher.

6. A dry film having a resin layer obtained by applying the photosensitive resin composition according to claim 1 to a first film and drying the applied composition.

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. An electronic part comprising the cured product according to claim 7.

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