Cured product, photosensitive resin composition, dry film, and printed wiring board

Abstract

Provided is a cured product that has a surface onto which a marking ink can be easily applied, exhibits excellent adhesiveness with the marking ink after curing, and can form a marker having excellent visibility of characters and symbols on the surface. The cured product comprises a curable resin composition containing a curable resin and an inorganic filler and is characterized in that the inorganic filler contains an amorphous silica, and the average linear expansion coefficient when a cured product having a thickness of 20 µm is subjected to a temperature change from 0ºC to 180ºC is 70-100 ppm / ºC.

Description

Cured product, photosensitive resin composition, dry film and printed wiring board CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority based on Japanese Patent Application No. 2022-060840 filed in Japan on March 31, 2022, and Japanese Patent Application No. 2022-060828 filed in Japan on March 31, 2022, the contents of which are incorporated herein by reference.

[0002] The present invention relates to a cured product and a photosensitive resin composition, and more particularly to a curable resin composition, a cured product of a photosensitive resin composition and a dry film, and a printed wiring board provided with a coating made of the cured product.

[0003] In general, in printed wiring boards used in electronic devices, a solder resist layer is formed on the substrate on which a circuit pattern is formed, except for connection holes, to prevent solder from adhering to unnecessary portions of the printed wiring board during processes such as solder reflow when mounting electronic components on the printed wiring board. The solder resist layer is formed by applying a liquid curable resin composition to the substrate and then curing it, or by using a curable dry film without using a liquid curable resin composition. For example, Patent Document 1 discloses a curable resin composition containing a carboxyl group-containing resin having a specific acid value, an acrylic copolymer, an epoxy resin, etc., as a composition suitable for forming the solder resist layer. Patent Document 2 also discloses a photosensitive film laminate having a layer containing inorganic particles as a dry film for forming the solder resist layer.

[0004] Incidentally, in consideration of the subsequent electronic component mounting process, identification characters, symbols, etc. (markers) are sometimes printed on the surface of printed wiring boards using marking ink to indicate the mounting position of the electronic components. Marking inks are mainly heat-curable and UV-curable, which are formed by pattern printing, or alkaline-developable, which are formed by exposing the ink through a negative film and then removing the unexposed areas with an alkaline aqueous solution. Recently, a technology called laser marking has also been used, in which the color tone of the irradiated area is changed by irradiating it with laser light, thereby displaying characters, symbols, etc.

[0005] When a marker is formed using marking ink on a printed wiring board having a solder resist layer as described above, depending on the application and curing conditions of the marking ink, the marking ink may be difficult to print or may peel off easily, resulting in reduced visibility of the marker. This tendency is particularly pronounced when the curing conditions of the marking ink are severe (for example, when the marking ink is made of a photocurable and thermosetting resin composition and both photocuring and thermosetting are required to cure the ink).

[0006] On the other hand, various requirements for the solder resist layer, such as solder heat resistance, crack resistance, and insulation reliability, have been sought, and photosensitive resin compositions that satisfy these required properties have been studied. For example, Patent Document 3 proposes the combined use of a bisphenol-type carboxyl group-containing resin and a novolac-type carboxyl group-containing resin as a photosensitive resin composition that can suppress the occurrence of cracks without reducing heat resistance.

[0007] Furthermore, in the manufacturing process of printed wiring boards, after forming a solder resist layer, gold plating or tin plating is usually performed for surface treatment of conductor patterns, formation of terminals for printed contacts, formation of bonding pads, etc. These plating processes do not require current flow or plating leads, so electroless gold plating and electroless tin plating are now being used. Therefore, improvement in plating solution resistance is also required for photosensitive resin compositions. For example, Patent Document 4 proposes the combined use of a bisphenol-type carboxyl group-containing resin and a carboxyl group-containing resin that is a reaction product of an unsaturated basic acid copolymer resin and an alicyclic epoxy group-containing unsaturated compound as a photosensitive resin composition with excellent chemical resistance to plating solutions, etc.

[0008] When a photosensitive resin composition such as that described in Patent Document 3 is used, the plating solution is likely to become contaminated during electroless plating, which in some cases leads to plating defects and the plating solution needs to be replaced more frequently. Furthermore, when a photosensitive resin composition such as that described in Patent Document 4 is used, development residues are likely to re-adhere to the substrate during development after exposure, which in some cases leads to plating defects due to the influence of the adhered development residues.

[0009] Japanese Patent Application Publication No. 10-142793 Japanese Patent Application Publication No. 2018-169537 Japanese Patent Application Publication No. 2017-529551 International Application Publication No. WO2003 / 032089 Pamphlet

[0010] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a cured product that allows marking ink to be easily applied to its surface, has excellent adhesion to the marking ink after curing, and is capable of forming a marker on its surface with excellent visibility of letters and symbols. Another object of the present invention is to provide a photosensitive resin composition that satisfies the properties required of a solder resist, such as insulation reliability, while also being able to suppress contamination of the plating solution and suppress plating defects.

[0011] The inventors conducted extensive research to address the above-mentioned problems and found that the printability and adhesion of marking ink to the surface of a cured product are affected by the state of the cured coating film formed by the curable resin composition when the cured product is formed. Specifically, they found that if warping or surface cracks occur during the formation of the cured coating film, subsequent printing of the marking ink will fail, or even if printing is successful, the marking ink will peel off during post-curing processing. Furthermore, the inventors found that the above-mentioned problems can be solved by including a specific silica in the curable resin composition and providing a cured product obtained by curing the curable resin composition with an average linear expansion coefficient within a specific range to prevent warping and cracking. Furthermore, they found that the use of three specific carboxyl group-containing resins as photosensitive resin components can provide a photosensitive resin composition that satisfies the properties required for a solder resist, such as insulation reliability, while suppressing contamination of the plating solution and reducing plating defects. The present invention is based on these findings. The gist of the present invention is as follows.

[0012] [1] A cured product made from a curable resin composition containing a curable resin and an inorganic filler, wherein the inorganic filler contains amorphous silica, and wherein the cured product has an average linear expansion coefficient of 70 to 100 ppm / °C when the temperature changes from 0°C to 180°C. [2] The cured product according to [1], wherein the glass transition point (Tg) is within the range of 100 to 120°C. [3] The cured product according to [1], wherein the cured product has an average linear expansion coefficient of 70 to 85 ppm / °C when the temperature changes from 0°C to 180°C. [4] The cured product according to [1], wherein the curable resin contains a thermosetting resin and a photocurable resin. [5] The cured product according to [1], wherein the amorphous silica is contained in an amount of 2 to 30 mass% in terms of solid content relative to the total curable resin composition. [6] A photosensitive resin composition comprising (A) a carboxyl group-containing resin, (B) a photopolymerizable monomer, and (C) a thermosetting component, wherein the (A) carboxyl group-containing resin comprises: (A1) a carboxyl group-containing resin having a novolac skeleton, (A2) a carboxyl group-containing resin having a bisphenol skeleton, and (A3) an unsaturated basic acid copolymerized carboxyl group-containing resin, wherein the combined amount of the (A1) carboxyl group-containing resin and the (A2) carboxyl group-containing resin is 60 to 80 mass% based on the total amount of the (A) carboxyl group-containing resin, and the combined amount of the (A3) carboxyl group-containing resin is 40 to 20 mass% based on the total amount of the (A) carboxyl group-containing resin. [7] The photosensitive resin composition according to [6], wherein the (A3) carboxyl group-containing resin is a reaction product of an unsaturated basic acid copolymerized resin and an alicyclic epoxy group-containing unsaturated compound. [8] The photosensitive resin composition according to [6], wherein the blending amount of the (A1) carboxyl group-containing resin is 10 to 60 mass % based on the total mass of the (A) carboxyl group-containing resin. [9] The photosensitive resin composition according to [6], wherein the blending amount of the (A2) carboxyl group-containing resin is 20 to 50 mass % based on the total mass of the (A) carboxyl group-containing resin.

[10] The photosensitive resin composition according to [6], wherein the (C) thermosetting component contains an epoxy resin having an isocyanuric ring.

[11] The photosensitive resin composition according to [6], further comprising (D) an inorganic filler.

[12] The photosensitive resin composition according to

[11] , wherein the (D) inorganic filler comprises fused silica.

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

[14] A cured product obtained by curing the resin layer of the photosensitive resin composition according to [6] or the dry film according to

[13] .

[15] The cured product according to [1] or

[14] , used as a solder resist.

[16] A printed wiring board comprising the cured product according to [1] or

[14] on a substrate.

[0013] The cured product of the present invention allows for the easy application of marking ink to the surface, has excellent adhesion to the marking ink after curing, and can form a marker on the surface with excellent visibility of letters and symbols.The photosensitive resin composition of the present invention uses three specific carboxyl group-containing resins in specific proportions as the photosensitive resin component, thereby satisfying the properties required of a solder resist, such as insulation reliability, while suppressing contamination of the plating solution and suppressing plating defects.

[0014] [Definition] In the present invention, the "average coefficient of linear expansion" refers to the rate of expansion of the length of a test piece of a cured product due to an increase in temperature, expressed per 1°C. Furthermore, the cured product in the present invention refers to a product obtained by curing a curable resin composition, a photosensitive resin composition, or a resin layer in a dry film (hereinafter, sometimes referred to as a curable resin composition, etc.), and refers to a state in which, after placing a cloth impregnated with isopropyl alcohol on the surface of the cured curable resin composition, etc., and further placing a 500 g weight on top of it and leaving it to stand for 1 minute, the curable resin composition, etc. is no longer attached to the surface of the cloth.

[0015] [Cured Product] The cured product according to the present invention is obtained by curing a curable resin composition containing a curable resin and an inorganic filler, and is characterized in that the average linear expansion coefficient of the cured product in the length direction (perpendicular to the thickness direction) of the cured product in a film form with a thickness of 20 μm when the temperature is changed from 0°C to 180°C is 70 to 100 ppm / °C. According to the present invention, a cured product having an average linear expansion coefficient within the above range can be used to form a marker that is easy to apply marking ink to its surface, has excellent adhesion to the marking ink after curing, and also has excellent visibility of letters and symbols on its surface. The reason for this is unclear, but can be presumed as follows. That is, a cured product having an average linear expansion coefficient of 70 to 100 ppm / °C when heated from 0°C to 180°C is less likely to warp or crack on its surface when the curable resin composition is cured to form the cured product, and as a result, it is thought that marking ink can be easily applied to the surface of the cured product, resulting in the formation of a marker with high visibility. Furthermore, since the curable resin composition contains amorphous silica as an inorganic filler, and since this amorphous silica has lower surface smoothness than other silicas, the anchoring effect of this amorphous silica also increases the adhesion between the cured product and the marking ink, which is thought to prevent the marker from peeling off from the surface of the cured product.A more preferable average linear expansion coefficient is 70 to 85 ppm / °C.

[0016] The average linear expansion coefficient of the cured product can be measured by a standard method using a thermomechanical analyzer, but in the present invention, it refers to a value measured as follows. First, a curable resin composition is applied to copper foil, dried, and then heated or irradiated with light to obtain a flat film-like cured product with a thickness of 20 μm after curing. Next, the obtained cured product is cut into a width of 3 mm and a length of 30 mm to prepare a test piece, and the thermal expansion coefficient is measured in tensile mode using a thermomechanical analyzer (TMA / SS6000, manufactured by Seiko Instruments Inc.). The maximum tensile load is 50 N / m, the span (distance between chucks) is 10 mm, and the heating rate is 10°C / min. The test piece is mounted in the thermomechanical analyzer, heated from 30°C to 200°C, and left for 10 minutes. Thereafter, the specimen was cooled to -30°C at a temperature drop rate of -10°C / min, and then measured at a temperature increase rate of 10°C / min from -30°C to 250°C. The measured values ​​at 0°C and 180°C were read, and the average coefficient of linear expansion (α) was calculated using the following formula: α = (1 / LS) x [{L(180) - L(0)} / (T(180) - T(0)] (where LS: length of the test piece (cured product) before measurement (measured value); L(0): change in length of the test piece (cured product) at 0°C (measured value); L(180): change in length of the test piece (cured product) at 180°C (measured value); T(0): 0 (°C); T(180): 180 (°C).)

[0017] The cured product of the present invention preferably has a glass transition point (Tg) in the range of 100 to 120°C. By producing a cured product with a Tg in this range, the linear expansion coefficient is more likely to fall within the desired range, resulting in a stable cured product with improved marking adhesion. The Tg of the cured product of the present invention can be determined as follows using a TMA curve measured with a thermomechanical analyzer (TMA). That is, from a TMA curve measured under the same conditions as the average linear expansion coefficient, a line A passing through two points, 0°C and 30°C, and a line B passing through two points, 150°C and 180°C, are drawn, and the temperature at the point where line A and line B intersect (extrapolated point) is defined as the Tg of the cured product of the present invention.

[0018] The average linear expansion coefficient (α) of the cured product of the present invention can be appropriately adjusted by the blending ratio of the curable resin and the inorganic filler, the degree of main curing by heating or light irradiation, and the glass transition point described above. The glass transition point of the cured product of the present invention can also be appropriately adjusted by the combination (compatibility) of the curable resin and other resins contained in the curable resin composition.

[0019] [Curable Resin Composition] The cured product according to the present invention is obtained by curing a curable resin composition. The curable resin composition contains a curable resin and an inorganic filler. In addition to the curable resin and the inorganic filler, it goes without saying that any additives such as a curing agent or a curing accelerator that cures the curable component, and a colorant, may be included as needed. Each component constituting the curable resin composition will be described below.

[0020] <Curable Resin> Examples of the curable resin include photocurable or thermosetting resins having a photocurable or thermosetting functional group, such as acrylic resins, epoxy resins, epoxy acrylate resins, silicone resins, phenolic resins, polyimide resins, polyurethane resins, melamine resins, and urea resins. These resins may be used alone or in combination of two or more, but the combined use of both a photocurable resin and a thermosetting resin is preferred in that excellent adhesion can be exhibited even under severe curing conditions such as dual cure.

[0021] Examples of the photocurable resin include polymerizable monomers and oligomers. As the polymerizable monomer, a photopolymerizable monomer having an ethylenically unsaturated double bond can be preferably used. Examples of the photopolymerizable monomer include known and commonly used polyester (meth)acrylate, polyether (meth)acrylate, urethane (meth)acrylate, carbonate (meth)acrylate, and epoxy (meth)acrylate. Specifically, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol and propylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol and tris-hydroxyethyl isocyanurate, or ethylene oxide adducts, propylene oxide adducts or ε-caprolactone adducts thereof. Polyhydric acrylates such as polyhydric acrylates such as phenoxy acrylate, bisphenol A diacrylate, and ethylene oxide or propylene oxide adducts of these phenols; polyhydric acrylates of glycidyl ethers such as glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, in addition to the above, acrylates and melamine acrylates obtained by directly acridating polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrylates via diisocyanates, and at least one of the methacrylates corresponding to the above acrylates can be appropriately selected and used. Such photopolymerizable monomers can also be used as reactive diluents.

[0022] Examples of the polymerizable oligomer include unsaturated polyester oligomers and (meth)acrylate oligomers. Examples of the (meth)acrylate oligomer include epoxy (meth)acrylates such as phenol novolac epoxy (meth)acrylate, cresol novolac epoxy (meth)acrylate, and bisphenol-type epoxy (meth)acrylate, urethane (meth)acrylate, epoxy urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and polybutadiene-modified (meth)acrylate.

[0023] When the curable resin composition contains a carboxyl group-containing resin described later, the blending amount of the photocurable resin in the curable resin composition is preferably 1 to 40 parts by mass, and more preferably 5 to 35 parts by mass, relative to 100 parts by mass of the carboxyl group-containing resin, converted into solid content.

[0024] The curable resins contained in the curable resin composition may also contain a photosensitive resin that can be patterned by exposure and development. Such a photosensitive resin is preferred in that it can be patterned by exposure and development to form a cured resin film in a desired pattern on a substrate.

[0025] Any known thermosetting resin can be used as the curable resin. Examples of known compounds that can be used include 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. Compounds having multiple cyclic ether groups or cyclic thioether groups (hereinafter referred to as cyclic (thio)ether groups) in the molecule are particularly preferred. These thermosetting resins can be used alone or in combination of two or more. The inclusion of a thermosetting resin can improve the strength of the cured coating in subsequent processes.

[0026] The compound having a plurality of cyclic (thio)ether groups in the molecule is a compound having a plurality of 3-, 4-, or 5-membered cyclic (thio)ether groups in the molecule, and examples thereof include a compound having a plurality of epoxy groups in the molecule, i.e., a polyfunctional epoxy compound, a compound having a plurality of oxetanyl groups in the molecule, i.e., a polyfunctional oxetane compound, and a compound having a plurality of thioether groups in the molecule, i.e., an episulfide resin.

[0027] Examples of such polyfunctional 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, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, and triphenylmethane type epoxy resins.

[0028] Examples of commercially available polyfunctional epoxy compounds include jER 828, 806, 807, YX8000, YX8034, and 834 manufactured by Mitsubishi Chemical Corporation; YD-128, YDF-170, ZX-1059, and ST-3000 manufactured by Nippon Steel Chemical & Material Co., Ltd.; EPICLON 830, 835, 840, 850, N-730A, and N-695 manufactured by DIC Corporation; and RE-306 manufactured by Nippon Kayaku Co., Ltd.

[0029] 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 hydroxyl group-containing resins such as silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring with alkyl (meth)acrylates.

[0030] Examples of compounds having multiple cyclic thioether groups in the molecule include bisphenol A episulfide resins, etc. Also, episulfide resins in which the oxygen atoms of the epoxy groups of novolac epoxy resins are replaced with sulfur atoms using a similar synthesis method can be used.

[0031] When a carboxyl group-containing resin is included, the compound having multiple cyclic (thio)ether groups in the molecule preferably contains 0.8 to 2.5 mol, more preferably 1.0 to 2.0 mol, of functional groups in the compound having multiple cyclic (thio)ether groups in the molecule to be reacted per 1.0 mol of carboxyl groups in the resin. By using an amount of 0.8 mol or more, it is possible to prevent carboxyl groups from remaining in the cured coating, thereby achieving good heat resistance, alkali resistance, electrical insulation, and the like. Furthermore, by using an amount of 2.5 mol or less, it is possible to prevent low-molecular-weight cyclic (thio)ether groups from remaining in the dried coating, thereby ensuring good strength of the cured coating.

[0032] Furthermore, when the compound having multiple cyclic (thio)ether groups in the molecule is a polyfunctional epoxy compound and a carboxyl group-containing resin is contained, the amount of the polyfunctional epoxy compound is preferably 20 to 50 parts by mass, calculated as solid content, per 100 parts by mass of the carboxyl group-containing resin.

[0033] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylolmelamine compounds, methylolbenzoguanamine compounds, methylolglycoluril compounds, and methylolurea compounds.

[0034] 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.

[0035] 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.

[0036] In the present invention, the curable resin is preferably an alkali-soluble resin in that it can be developed when patterned. When the curable resin composition contains an alkali-soluble resin, it preferably contains a photopolymerizable monomer and a photopolymerization initiator as other components.

[0037] The alkali-soluble resin may be any resin that dissolves in an alkaline aqueous solution, and known and commonly used ones can be used. The alkali-soluble resin can be used alone or in combination of two or more. Examples include water-soluble resins such as carboxyl group-containing resins and phenolic hydroxyl group-containing resins. Among these, carboxyl group-containing resins and phenolic hydroxyl group-containing resins are preferred due to their excellent developability, and carboxyl group-containing resins are more preferred. By including a carboxyl group in the carboxyl group-containing resin, it can be made alkaline-developable. Furthermore, from the viewpoint of photosensitivity, it is preferable for the resin to have an ethylenically unsaturated double bond in the molecule in addition to the carboxyl group. However, it is also possible to use only a carboxyl group-containing resin without an ethylenically unsaturated double bond. The ethylenically unsaturated double bond is preferably derived from acrylic acid, methacrylic acid, or a derivative thereof. When using only a carboxyl group-containing resin without an ethylenically unsaturated double bond, a compound having multiple ethylenically unsaturated groups in the molecule, i.e., a photopolymerizable monomer, must be used in combination to make the composition photocurable. Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers): In this specification, (meth)acrylate is a general term for acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions.

[0038] (1) Carboxyl group-containing resins obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

[0039] (2) Carboxyl group-containing urethane resins obtained by the polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0040] (3) Carboxylic acid group-containing photosensitive urethane resins obtained by polyaddition reaction of diisocyanates with partially acid anhydride-modified products of reaction products of bifunctional epoxy resins such as bisphenol A epoxy resins, hydrogenated bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bixylenol epoxy resins, and biphenol epoxy resins with monocarboxylic acid compounds having ethylenically unsaturated double bonds such as (meth)acrylic acid, carboxyl group-containing dialcohol compounds, and diol compounds.

[0041] (4) A carboxyl group-containing photosensitive urethane resin having a terminal (meth)acrylate formed by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as a hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (3).

[0042] (5) A carboxyl group-containing photosensitive urethane resin that has been (meth)acrylated at its terminal by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (2) or (3).

[0043] (6) A carboxyl group-containing photosensitive resin obtained by reacting a difunctional or more polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl group present in the side chain.

[0044] (7) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0045] (8) Carboxyl group-containing polyester resins obtained by reacting a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid with a bifunctional oxetane resin, and then adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the resulting primary hydroxyl groups.

[0046] (9) A carboxyl group-containing photosensitive resin obtained by reacting an epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid, such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl groups of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

[0047] (10) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0048] (11) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0049] (12) A carboxyl group-containing photosensitive resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins (1) to (11). In this specification, the term "(meth)acrylate" is a general term for acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

[0050] Among the above-mentioned carboxyl group-containing photosensitive resins, (6) photosensitive resins using a novolac type epoxy resin as the epoxy resin, (7) photosensitive resins using a bisphenol type epoxy resin as the epoxy resin, and (12) photosensitive resins can be preferably used. In particular, photosensitive resins using at least two of the above-mentioned (6), (7), and (12) can be more preferably used, and photosensitive resins using three of them can be even more preferably used.

[0051] The aforementioned (6) is preferably contained in an amount of 10 to 80% by mass, more preferably 10 to 60% by mass, and even more preferably 10 to 40% by mass, based on the total carboxyl group-containing resin. The aforementioned (7) is preferably contained in an amount of 20 to 70% by mass, more preferably 30 to 60% by mass, and even more preferably 40 to 55% by mass, based on the total carboxyl group-containing resin. The aforementioned (12) is preferably contained in an amount of 20 to 40% by mass, and even more preferably 25 to 40% by mass, based on the total carboxyl group-containing resin.

[0052] These carboxyl group-containing resins are not limited to those listed above, and may be used alone or in combination of two or more types.

[0053] The acid value of the carboxyl group-containing resin is preferably 40 to 150 mgKOH / g. By making the acid value of the carboxyl group-containing resin 40 mgKOH / g or more, alkaline development becomes good. Furthermore, by making the acid value 150 mgKOH / g or less, it becomes easier to draw a good resist pattern. More preferably, it is 50 to 130 mgKOH / g.

[0054] The weight-average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. By making the weight-average molecular weight 2,000 or more, tack-free performance and resolution can be improved. Furthermore, by making the weight-average molecular weight 150,000 or less, developability and storage stability can be improved. A weight-average molecular weight of 5,000 to 30,000 is more preferable. The weight-average molecular weight can be measured by gel permeation chromatography (GPC).

[0055] The amount of the carboxyl group-containing resin in the curable resin composition is preferably 20 to 60% by mass, calculated as solid content. By making it 20% by mass or more, the coating strength can be improved. By making it 60% by mass or less, the viscosity becomes appropriate and printability is improved. More preferably, it is 25 to 50% by mass.

[0056] From the viewpoint of printability and adhesion of the marking ink, the total amount of the curable resin in the curable resin composition is preferably 20 to 80 mass %, and more preferably 30 to 70 mass %, converted into solid content, relative to the total amount of the curable resin composition.

[0057] When the curable resin composition for forming the cured product of the present invention contains a carboxyl group-containing resin, a photopolymerizable monomer, or an oligomer, it may contain a photopolymerization initiator to cause a reaction by exposure to light. Any known photopolymerization initiator can be used.

[0058] 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. Sphingoic acid, bisacylphosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide and 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, pivaloylphenyl Monoacylphosphine oxides such as isopropyl phosphinate and 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 hydroxyacetophenones such as 2-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;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 acetophenones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; thioxanthones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone anthraquinones such as acetophenone dimethyl ketal 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; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime) oxime esters such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and titanocenes such as bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc. These photopolymerization initiators may be used alone or in combination of two or more.

[0059] Commercially available α-aminoacetophenone photopolymerization initiators include Omnirad 907, 369, 369E, and 379 manufactured by IGM Resins. Commercially available acylphosphine oxide photopolymerization initiators include Omnirad 819 manufactured by IGM Resins. Commercially available oxime ester photopolymerization initiators include Irgacure OXE01 and OXE02 manufactured by BASF Japan Ltd., N-1919, ADEKA Arcles NCI-831 and NCI-831E manufactured by ADEKA Corporation, and TR-PBG-304 manufactured by Changzhou New Advanced Electronic Materials Co., Ltd.

[0060] Other examples include carbazole oxime ester compounds described in JP-A-2004-359639, JP-A-2005-097141, JP-A-2005-220097, JP-A-2006-160634, JP-A-2008-094770, JP-T-2008-509967, JP-T-2009-040762, and JP-A-2011-80036.

[0061] When the curable resin composition contains a carboxyl group-containing resin, the amount of photopolymerization initiator is preferably 1 to 30 parts by mass, calculated as solid content, per 100 parts by mass of the carboxyl group-containing resin. When the amount is 1 part by mass or more, the photocurability of the curable resin composition is good, and coating properties such as chemical resistance are also good. When the amount is 30 parts by mass or less, the effect of reducing outgassing is obtained, and further, light absorption at the surface of the cured coating is good, making it less likely that deep curing will decrease. A more preferred amount is 2 to 25 parts by mass.

[0062] In the present invention, a photoinitiator aid or sensitizer may be used 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. In particular, it is preferable to use thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The inclusion of a thioxanthone compound can improve deep curing properties. While these compounds may be used as photopolymerization initiators, it is preferable to use them in combination with a photopolymerization initiator. Furthermore, one type of photoinitiator aid or sensitizer may be used alone, or two or more types may be used in combination.

[0063] These photopolymerization initiators, photoinitiator assistants, and sensitizers absorb light of specific wavelengths, which can reduce sensitivity in some cases and function as ultraviolet absorbers. However, they are not used solely for the purpose of improving the sensitivity of the curable resin composition. They can absorb light of specific wavelengths as needed to 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.

[0064] Furthermore, when the curable resin composition for forming the cured product of the present invention contains a thermosetting resin, it may contain a thermosetting catalyst for accelerating the curing of the thermosetting resin. Examples of the thermosetting catalyst include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; and phosphorus compounds such as triphenylphosphine. Commercially available compounds include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all of which are trade names of imidazole-based compounds) manufactured by Shikoku Chemicals Corporation, and U-CAT 3513N (a trade name of a dimethylamine-based compound), DBU, DBN, and U-CAT SA 102 (all of which are bicyclic amidine compounds and salts thereof) manufactured by San-Apro Co., Ltd.

[0065] The compounds are not limited to those mentioned above, and any compound that acts as a heat curing catalyst for an epoxy resin or an oxetane compound, or that promotes the reaction between at least one of an epoxy group and an oxetanyl group and a carboxyl group, may be used alone or in combination of two or more. Also usable are S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine-isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine-isocyanuric acid adduct. These compounds that also function as adhesion promoters are preferably used in combination with the heat curing catalyst.

[0066] The above-mentioned thermosetting catalysts can be used alone or in combination of two or more. When a carboxyl group-containing resin is contained in the curable resin composition, the amount of the thermosetting catalyst is preferably 0.01 to 8 parts by mass, and more preferably 0.05 to 5 parts by mass, calculated as solid content, per 100 parts by mass of the carboxyl group-containing resin, from the viewpoint of the storage stability of the photosensitive resin composition and the heat resistance of the cured coating.

[0067] <Inorganic Filler> The cured product of the present invention is obtained by curing a curable resin composition containing amorphous silica as an inorganic filler. The inclusion of amorphous silica significantly improves the printability when printing marking ink on the surface of the cured product, as well as the adhesion and visibility of the marker after printing. The reason for this is unclear, but is thought to be as follows. That is, amorphous silica has lower surface smoothness than crystalline silica, and its anchoring effect is thought to improve printability and adhesion. Note that, in the present invention, amorphous silica refers to silica other than crystalline silica (including fine crystalline silica), which does not have the long-range order of crystalline silica but has short-range order. This is a thermodynamically non-equilibrium metastable state. Known and commonly used amorphous silica can be used, including silica gel and diatomaceous earth. Furthermore, the amorphous silica may be synthetic silica as long as it is amorphous.

[0068] From the viewpoint of the applicability of the marking ink and the adhesion of the marking ink when cured, it is preferable that the amorphous silica have an oil absorption of 180 to 350 ml / 100 g. Such amorphous silica is porous, and it is presumed that the absorption of oil from organic solvents and the like during curing and drying causes the amorphous silica and other extender pigments to become denser, thereby improving the applicability and adhesion of the marking ink. An oil absorption of 200 to 300 ml / 100 g is more preferable. In the present invention, the oil absorption refers to the value measured in accordance with "JIS K5101-13-1:2004 Pigment Testing Methods - Part 13: Oil Absorption - Section 1: Refined Linseed Oil Method."

[0069] The amorphous silica may be any known or commonly used material, either synthetic or natural. It may be surface-treated or untreated. The type of surface treatment is the same as that for the extender pigment. Examples of such products include ACEMATT 82, ACEMATT 790, ACEMATT OK 412, and ACEMATT OK 500 (all manufactured by EVONIK DEGUSSA).

[0070] The amorphous silica may be surface-treated to enhance dispersibility in the curable resin composition. By using surface-treated amorphous silica, aggregation can be suppressed. The surface treatment method is not particularly limited, and a known, commonly used method may be used. However, it is preferable to treat the surface of the amorphous silica with a surface treatment agent having a curable reactive group, for example, a coupling agent having a curable reactive group as an organic group.

[0071] Examples of coupling agents that can be used include silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents. Among these, silane-based coupling agents are preferred. Examples of such silane-based 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. It is preferred that these silane-based coupling agents are immobilized on the surface of the filler in advance by adsorption or reaction.

[0072] The average particle size (D50) of amorphous silica is preferably 0.1 to 10 μm, and more preferably 1 to 5 μm. The average particle size refers to the particle size at 50% cumulative volume obtained using a laser diffraction / scattering particle size distribution measurement method. The average particle size of amorphous silica refers to the value measured as described above for silica before preparing (pre-stirring, kneading) the curable resin composition.

[0073] From the viewpoint of printability and adhesion of the marking ink, the amount of amorphous silica blended in the curable resin composition is preferably 2 to 30 mass %, and more preferably 5 to 20 mass %, converted into solid content, relative to the entire curable resin composition.

[0074] In addition to the amorphous silica described above, other inorganic fillers can be blended into the curable resin composition as necessary to increase the physical strength of the cured product, etc. Known inorganic fillers can be used, and in particular, talc, mica, aluminum oxide, calcium oxide, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, fly ash, dewatered sludge, kaolin, clay, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, potassium titanate, magnesium sulfate, calcium sulfate, magnesium phosphate, sepiolite, zonolite, boron nitride, aluminum borate, silica balloons, glass flakes, glass balloons, steelmaking slag, copper, iron, iron oxide, sendust, alnico magnets, magnetic powders such as various ferrites, cement, glass powder, Neuburg silica, antimony trioxide, magnesium oxysulfate, aluminum hydrate, hydrated gypsum, alum, barium sulfate, etc. The other inorganic fillers may be used alone or in combination of two or more.

[0075] The inorganic filler described above also preferably has an average particle size (D50) of 0.1 to 200 μm, more preferably 1 to 10 μm, from the viewpoint of dispersibility, etc. Furthermore, similar to amorphous silica, the filler may be surface-treated from the viewpoint of dispersibility.

[0076] The total amount of inorganic filler combined with amorphous silica is preferably 20 to 70 mass %, and more preferably 40 to 60 mass %, calculated as solid content, relative to the total curable resin composition, which improves the ability of the curable resin composition to prevent a decrease in adhesion strength and improves its resistance to thermal cycling, thereby further improving adhesion to marking ink.

[0077] <Other Components> In addition to the components described above, the curable resin composition according to the present invention may contain, as necessary, components such as colorants, elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, at least one of silicone-based, fluorine-based, and polymer-based antifoaming agents and leveling agents, and flame retardants such as phosphinates, phosphate ester derivatives, and phosphorus compounds such as phosphazene compounds. These components may be known in the field of electronic materials.

[0078] The curable resin composition may contain an organic solvent from the viewpoint of ease of preparation and coating properties. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used alone or in combination of two or more.

[0079] The amount of the organic solvent in the curable resin composition can be changed as appropriate depending on the materials constituting the curable resin composition. For example, when a carboxyl group-containing resin is contained in the curable resin composition, the amount can be 20 to 300 parts by mass per 100 parts by mass of the carboxyl group-containing resin (solid content).

[0080] The curable resin composition may be used in the form of a dry film or in a liquid form. When used in a liquid form, the curable resin composition may be one-component or two or more-component.

[0081] [Photosensitive Resin Composition] The photosensitive resin composition of the present invention contains, as essential components, (A) a carboxyl group-containing resin, (B) a photopolymerizable monomer, and (C) a thermosetting component. Each component constituting the photosensitive resin composition of the present invention will be described below.

[0082] <(A) Carboxyl Group-Containing Resin> The photosensitive resin composition according to the present invention contains, as the (A) carboxyl group-containing resin, three types of carboxyl group-containing resins in specific proportions: (A1) a carboxyl group-containing resin having a novolac skeleton, (A2) a carboxyl group-containing resin having a bisphenol skeleton, and (A3) an unsaturated basic acid copolymerization type carboxyl group-containing resin. In the present invention, by containing the above-mentioned three specific photosensitive resins in specific proportions as the carboxyl group-containing resin, a photosensitive resin composition can be obtained that satisfies the properties required of a solder resist, such as heat resistance and insulation reliability, while suppressing contamination of the plating solution and suppressing plating defects. The reason for this is not clear, but can be presumed as follows.

[0083] As described in Patent Document 4, when a carboxyl group-containing resin having a bisphenol skeleton and an unsaturated basic acid copolymerized carboxyl group-containing resin are used as a photosensitive resin, the resins have high hydrophobicity and a large molecular weight, resulting in excellent insulation reliability and heat resistance for PCBs and other substrates. However, the copolymerized resin component among the uncured resin components dissolved in the developer precipitates in the water bath during the cleaning process after development and re-adheres to the conductor portion (copper) of the substrate. This deposit is thought to be the cause of plating defects in the subsequent plating process. On the other hand, when a photosensitive resin with excellent heat resistance and crack resistance (a carboxyl group-containing resin having a bisphenol skeleton or a novolac skeleton) as described in Patent Document 3 is used as the photosensitive resin, the above-mentioned development residue hardly precipitates in the water bath, but uncured resin components and unreacted photopolymerizable monomers contained in the cured coating of the photosensitive resin composition leach into the electroless plating bath, contaminating the plating bath. Therefore, by using the above three types of carboxyl group-containing resins in combination in specific ratios, it is possible to achieve a high level of both hydrophobicity of the photosensitive resin as a whole (prevention of deposition in the water tank) and prevention of elution into the plating bath. As a result, it is believed that it is possible to suppress both the occurrence of plating defects and contamination of the plating solution while satisfying the properties required of a solder resist, such as heat resistance and insulation reliability.

[0084] Examples of the carboxyl group-containing resin (A1) having a novolac skeleton include a carboxyl group-containing photosensitive resin (A1a) obtained by reacting a polyfunctional epoxy resin such as a phenol novolac epoxy resin, a cresol novolac epoxy resin, a bisphenol A cresol novolac epoxy resin, or a dicyclopentadiene cresol novolac epoxy resin with (meth)acrylic acid, and then adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chain; a polyfunctional epoxy resin (A1a) obtained by further epoxidizing the hydroxyl groups of the above polyfunctional epoxy resin with epichlorohydrin, and then reacting the resulting polybasic acid with (meth)acrylic acid; Examples of suitable photosensitive resins include carboxyl group-containing photosensitive resins (A1b) prepared by adding a basic acid anhydride to a polyfunctional phenolic compound such as a novolac resin, followed by partial esterification of the resulting hydroxyl groups with (meth)acrylic acid and reaction of the remaining hydroxyl groups with a polybasic acid anhydride. Examples of suitable photosensitive resins include carboxyl group-containing photosensitive resins prepared by adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate or α-methylglycidyl (meth)acrylate, to any of the resins A1a to A1c. In the present invention, cresol novolac-type carboxyl group-containing resins are preferred because they have superior solder heat resistance compared to phenol novolac-type carboxyl group-containing resins. In this specification, the term "(meth)acrylate" is used collectively to refer to acrylates, methacrylates, and mixtures thereof, and the same applies to other similar terms. Furthermore, the term "(meth)acryloyl group" is used as a general term for an acryloyl group, a methacryloyl group, or both, and the same applies to other similar expressions.

[0085] Examples of the carboxyl group-containing resin having a bisphenol skeleton (A2) include a carboxyl group-containing photosensitive resin (A2a) obtained by reacting a bifunctional epoxy resin such as a bisphenol A epoxy resin, a hydrogenated bisphenol A epoxy resin, a bisphenol F epoxy resin, or a bisphenol S epoxy resin with (meth)acrylic acid, and then adding a polybasic acid anhydride to the resulting hydroxyl groups; a carboxyl group-containing photosensitive resin (A2b) obtained by reacting a polyfunctional epoxy resin in which the hydroxyl groups of the above bifunctional epoxy resin have been further epoxidized with epichlorohydrin with (meth)acrylic acid, and then adding a polybasic acid anhydride to the resulting hydroxyl groups; and a carboxyl group-containing photosensitive resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate or α-methylglycidyl (meth)acrylate, to the above resin A2a or A2b.

[0086] The above-mentioned carboxyl group-containing resins (A1) and (A2) each have a large number of free carboxyl groups in the side chains of the backbone polymer, making them suitable for development with an alkaline aqueous solution. The acid value of these carboxyl group-containing resins (A1) and (A2) is preferably 40 to 200 mgKOH / g. When the acid value of the carboxyl group-containing resins A1 and A2 is 40 to 200 mgKOH / g, alkaline development is facilitated, dissolution of exposed areas in the developer is suppressed, and fine resist patterns can be easily drawn. An acid value of 45 to 120 mgKOH / g is more preferred.

[0087] The weight-average molecular weight of the carboxyl group-containing resins (A1) and (A2) described above varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000, more preferably 5,000 to 100,000, from the viewpoints of moisture resistance (solubility in water), resolution, developability, etc. of the coating film after exposure. The weight-average molecular weight means a value calculated as a standard polystyrene equivalent measured by gel permeation chromatography (GPC).

[0088] Next, the unsaturated basic acid copolymerized carboxyl group-containing resin (A3) will be described. The carboxyl group-containing resin (A3) is obtained by copolymerizing a (meth)acrylic acid ester with a compound having one unsaturated group and at least one carboxyl group in one molecule. Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, and hexyl (meth)acrylate, hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and caprolactone-modified 2-hydroxyethyl (meth)acrylate, and glycol-modified (meth)acrylates such as methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, isooctyloxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate. These may be used alone or in combination of two or more.

[0089] Examples of compounds having one unsaturated group and at least one carboxyl group in one molecule include acrylic acid, methacrylic acid, modified unsaturated monocarboxylic acids in which the unsaturated group and the carboxylic acid are chain-extended, such as β-carboxyethyl (meth)acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, unsaturated monocarboxylic acids having an ester bond due to lactone modification or the like, modified unsaturated monocarboxylic acids having an ether bond, and compounds containing two or more carboxyl groups in the molecule, such as maleic acid. These may be used alone or in combination of two or more.

[0090] In the present invention, the unsaturated basic acid copolymerized carboxyl group-containing resin (A3) can preferably be a resin obtained by reacting some of the acid groups of the above-mentioned unsaturated basic acid copolymerized resin (i.e., a copolymerized resin obtained by copolymerizing a (meth)acrylic acid ester with a compound having one unsaturated group and at least one carboxyl group per molecule) with the epoxy groups of an alicyclic epoxy group-containing unsaturated compound to introduce unsaturated groups into the resin. By using the unsaturated basic acid copolymerized carboxyl group-containing resin in combination with the above-mentioned carboxyl group-containing resins (A1) and (A2) in a specific ratio, the PCBT properties can be further improved.

[0091] The alicyclic epoxy group-containing unsaturated compound that reacts with a portion of the acid groups of the unsaturated basic acid copolymer resin is preferably a compound having one radically polymerizable unsaturated group and an alicyclic epoxy group in one molecule, for example, a compound having both an alicyclic epoxy group and an acrylic group, such as 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylethyl acrylate, 3,4-epoxycyclohexylbutyl acrylate, etc. These may be used alone or in combination of two or more.

[0092] In addition to the above-mentioned compounds having both an alicyclic epoxy group and an acrylic group, aliphatic epoxy group-containing unsaturated compounds such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, and allyl glycidyl ether may also be used in combination.

[0093] The weight-average molecular weight of the carboxyl group-containing resin (A3) varies depending on the resin skeleton, but from the viewpoints of the moisture resistance (solubility in water), resolution, developability, etc. of the coating film after exposure, it is generally preferably 3,000 to 100,000, more preferably 5,000 to 50,000.

[0094] In the photosensitive resin composition of the present invention, the total amount of the carboxyl group-containing resin (A1) and the carboxyl group-containing resin (A2) is 60 to 80 mass% based on the total amount of the carboxyl group-containing resin (A). The amount of the carboxyl group-containing resin (A3) is 40 to 20 mass% based on the total amount of the carboxyl group-containing resin (A). By including these three types of carboxyl group-containing resins in specific proportions, it is possible to suppress both contamination of the plating solution and plating defects while still satisfying the properties required of a solder resist, such as insulation reliability. The amount of each carboxyl group-containing resin is the amount calculated as a solid content (the same applies hereinafter).

[0095] From the viewpoint of gold plating resistance, the total amount of the carboxyl group-containing resin (A1) and the carboxyl group-containing resin (A2) is preferably 65 to 75% by mass based on the total amount of the carboxyl group-containing resin (A).

[0096] With regard to the blending ratios of the above carboxyl group-containing resins (A1) to (A3), the blending amount of the carboxyl group-containing resin (A1) is preferably 10 to 60 mass %, and more preferably 10 to 40 mass %, based on the total amount of the carboxyl group-containing resin (A), from the viewpoint of preventing non-adhesion of gold plating.

[0097] Furthermore, from the viewpoint of suppressing redeposition of development residues onto the substrate, the blending amount of the carboxyl group-containing resin (A2) is preferably 20 to 60 mass %, and more preferably 40 to 60 mass %, based on the total mass of the carboxyl group-containing resin (A).

[0098] The amount of the carboxyl group-containing resin (A3) added is preferably 40 to 20% by mass based on the total amount of the carboxyl group-containing resin (A) from the viewpoints of PCT resistance and suppressing abnormalities in gold plating.

[0099] The blending amount of (A) carboxyl group-containing resin is preferably 20 to 60% by mass based on the total photosensitive resin composition. By making it 20% by mass or more, the coating strength can be improved. Furthermore, by making it 60% by mass or less, the viscosity becomes appropriate and processability is improved. More preferably, it is 25 to 50% by mass.

[0100] <(B) Photopolymerizable Monomer> The (B) photopolymerizable monomer contained in the photosensitive resin composition is a monomer having an ethylenically unsaturated double bond. As the (B) photopolymerizable monomer, those shown in the above-mentioned curable resin composition can be used.

[0101] The blending amount of the photopolymerizable monomer (B) in the photosensitive resin composition is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, based on 100 parts by mass of the carboxyl group-containing resin, calculated as solid content.

[0102] <Photopolymerization initiator> The photosensitive resin composition according to the present invention may contain a photopolymerization initiator for reacting the above-mentioned (A) carboxyl group-containing resin and (B) photopolymerizable monomer by exposure to light. As the photopolymerization initiator, those shown in the above-mentioned curable resin composition can be used.

[0103] The amount of photopolymerization initiator, calculated as solid content, is preferably 1 to 20 parts by mass per 100 parts by mass of the carboxyl group-containing resin (A). When the amount is 1 part by mass or more, the photocurability of the photosensitive resin composition is good, and coating properties such as chemical resistance are also good. When the amount is 20 parts by mass or less, the effect of reducing outgassing is obtained, and further, light absorption at the surface of the cured coating is good, and deep curing is less likely to decrease. A more preferred amount is 2 to 15 parts by mass.

[0104] In the present invention, a photoinitiator assistant or a sensitizer may be used in combination with the photopolymerization initiator. As the photoinitiator assistant or sensitizer, those shown in the above-mentioned curable resin composition can be used.

[0105] <(C) Thermosetting Component> The photosensitive resin composition according to the present invention contains (C) a thermosetting component in addition to (A) a carboxyl group-containing resin and (B) a photopolymerizable monomer. By including the thermosetting component, the barrier properties (e.g., etching resistance) of the cured coating in a subsequent process are improved, and both resolution and removability can be achieved at a high level. As the (C) thermosetting component, those shown as "curable resins" in the above-mentioned curable resin composition can be used.

[0106] In addition, among epoxy resins, an epoxy resin having an isocyanuric ring can be preferably used in the photosensitive resin composition of the present invention from the viewpoint of achieving both resolution and releasability. Examples of epoxy resins having an isocyanuric ring include bifunctional epoxy isocyanurate ester compounds such as 1,3-bis(2,3-epoxypropyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; trifunctional epoxy isomers such as 1,3,5-tris(2,3-epoxy-2-methylpropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3,4-epoxybutyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 1,3,5-tris(4,5-epoxypentyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; An anurate ester compound; tetrafunctional or higher polyfunctional epoxy isocyanurate ester compounds such as 1,3,5-tris{2-[2,2-bis(2,3-epoxypropyloxymethyl)butyloxycarbonyl]ethyl}-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, etc. are exemplified. A trifunctional epoxy isocyanurate ester compound is preferred, and a compound containing 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3,4-epoxybutyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, or 1,3,5-tris(4,5-epoxypentyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is particularly preferred.

[0107] Commercially available epoxy resins having an isocyanuric ring include, for example, TEPIC-PAS B26L, TEPIC-PAS B22, TEPIC-VL, TEPIC-UC, TEPIC-G, TEPIC-S, TEPIC-SP, and TEPIC-SS, manufactured by Nissan Chemical Industries, Ltd.

[0108] The amount of the thermosetting component (C) to be reacted is preferably 0.8 to 2.5 mol, more preferably 1.0 to 2.0 mol, of functional groups in the thermosetting component (C) to react with 1.0 mol of carboxyl groups contained in the carboxyl group-containing resin (A).

[0109] In particular, when an epoxy resin is used as the thermosetting component (C), the epoxy resin preferably contains 1.0 to 2.0 mol of epoxy groups per 1.0 mol of carboxyl groups in the carboxyl group-containing resin (A). By using 1 mol or more, it is possible to prevent carboxyl groups from remaining in the cured coating, thereby achieving good heat resistance, alkali resistance, electrical insulation, and the like. Furthermore, by using an amount of 2 mol or less, it is possible to prevent low-molecular-weight cyclic (thio)ether groups from remaining in the dried coating, thereby ensuring good strength of the cured coating.

[0110] <Thermosetting Catalyst> The photosensitive resin composition may contain a thermosetting catalyst for accelerating the curing of the thermosetting component (C). As the thermosetting catalyst, those exemplified for the curable resin composition described above can be used.

[0111] The above-mentioned thermosetting catalysts can be used alone or in combination of two or more. From the viewpoint of the storage stability of the photosensitive resin composition and the heat resistance of the cured coating, the amount of the thermosetting catalyst is preferably 0.01 to 8 parts by mass, and more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the carboxyl group-containing resin (A) in terms of solid content.

[0112] <(D) Inorganic Filler> The photosensitive resin composition according to the present invention may optionally contain an inorganic filler (D) in order to increase the physical strength of the cured coating. Examples of inorganic fillers that can be used include known fillers, such as silica, talc, mica, aluminum oxide, calcium oxide, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, fly ash, dewatered sludge, kaolin, clay, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, potassium titanate, magnesium sulfate, calcium sulfate, magnesium phosphate, sepiolite, zonolite, boron nitride, aluminum borate, silica balloons, glass flakes, glass balloons, steelmaking slag, copper, iron, iron oxide, sendust, alnico magnets, various ferrites and other magnetic powders, cement, glass powder, Neuburg silica, diatomaceous earth, antimony trioxide, magnesium oxysulfate, aluminum hydrate, hydrated gypsum, alum, and barium sulfate. The other inorganic fillers may be used alone or in combination of two or more.

[0113] Among these, silica, talc, and barium sulfate are preferred. Silica may be amorphous, crystalline, or a mixture of these. Amorphous (fused) silica is particularly preferred.

[0114] From the viewpoint of dispersibility, etc., the inorganic filler used preferably has an average particle size (D50) of 0.1 to 100 μm, more preferably 0.1 to 50 μm. The average particle size refers to the particle size at 50% cumulative volume obtained using a laser diffraction / scattering particle size distribution measurement method. The average particle size of the filler refers to the value measured as described above for the filler before preparing (pre-stirring, kneading) the photosensitive resin composition.

[0115] The amount of inorganic filler in the photosensitive resin composition is preferably 1 to 500 parts by mass, and more preferably 10 to 300 parts by mass, based on 100 parts by mass of the carboxyl group-containing resin, calculated as solid content, which can further improve the ability of the photosensitive resin composition to prevent a decrease in adhesion strength and its thermal cycle resistance.

[0116] The inorganic filler described above may be surface-treated to enhance dispersibility in the photosensitive resin composition. By using a surface-treated inorganic filler, aggregation can be suppressed. The surface treatment method is not particularly limited, and any known or commonly used method may be used. However, 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.

[0117] The coupling agent may be any of those listed above for the curable resin composition. These silane coupling agents are preferably immobilized on the surface of the inorganic filler by adsorption or reaction in advance. The amount of the coupling agent to be used per 100 parts by mass of the inorganic filler is preferably 0.5 to 10 parts by mass.

[0118] <Other Components> In addition to the components described above, the photosensitive resin composition according to the present invention may contain, if necessary, the components shown as "other components" in the above-described curable resin composition.

[0119] The photosensitive resin composition of the present invention may contain an organic solvent from the viewpoint of ease of preparation and coating property. As the organic solvent, those exemplified for the curable resin composition described above can be used.

[0120] The amount of organic solvent in the photosensitive resin composition can be appropriately changed depending on the materials constituting the photosensitive resin composition, and can be, for example, 30 to 300 parts by mass per 100 parts by mass of (A) carboxyl group-containing resin (solid content). Note that the amount of organic solvent in this case also includes the organic solvent contained in the varnish when the resin, such as (A) carboxyl group-containing resin, is used as a varnish.

[0121] The photosensitive resin composition of the present invention may be used in the form of a dry film or in the form of a liquid. When used in the form of a liquid, the composition may be one-component or two or more-component.

[0122] <Dry Film> The above-described curable resin composition and the photosensitive resin composition of the present invention can also be in the form of a dry film comprising a first film and a resin layer formed on the first film, the resin layer being made of the curable resin composition or the photosensitive resin composition. The first film in the dry film of the present invention refers to a film that is adhered to at least the resin layer when the dry film is integrally formed by laminating the dry film onto a substrate or other base material by heating or the like so that the resin layer formed on the dry film is in contact with the curable resin composition or the photosensitive resin composition. The first film may be peeled from the resin layer in a step after lamination. In particular, in the present invention, peeling from the resin layer in a step after exposure is preferred.

[0123] To prepare a dry film, the curable resin composition or the photosensitive resin composition is diluted with an organic solvent to adjust the viscosity to an appropriate level, and then coated onto the first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like, and typically dried for 1 to 30 minutes at a temperature of 50 to 130° C. to obtain a film. There are no particular restrictions on the coating film thickness, but the thickness after drying is generally selected appropriately from the range of 1 to 150 μm, preferably 10 to 60 μm.

[0124] The first film can be any known film without particular limitation, and examples thereof include films made of thermoplastic resins such as polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamideimide films, polypropylene films, and polystyrene films. Among these, polyester films are preferred from the viewpoints of heat resistance, mechanical strength, handleability, etc. A laminate of these films can also be used as the first film.

[0125] Moreover, from the viewpoint of improving mechanical strength, the above-mentioned thermoplastic resin film is preferably a film stretched in a uniaxial or biaxial direction.

[0126] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0127] After forming a resin layer of the curable resin composition or the photosensitive resin composition on the first film, it is preferable to further laminate a peelable second film on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer, etc. The second film in the dry film according to the present invention refers to a film that is peeled from the resin layer before lamination when the dry film is laminated by heating or the like so that the resin layer side of the dry film is in contact with a base material such as a substrate to form an integral mold.

[0128] The second film that can be peeled off from the resin layer can be, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, or surface-treated paper, and it is sufficient that 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.

[0129] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0130] <Method for Producing Cured Product> The cured product of the present invention can be obtained by curing the resin layer of the curable resin composition or dry film described above. For example, the curable resin composition is adjusted to a viscosity suitable for the coating method using the organic solvent described above, and applied to the surface of a substrate or the like by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating. The organic solvent contained in the composition is then evaporated and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer. In the case of a dry film, the resin layer is formed on the substrate by laminating it to the substrate using a laminator or the like so that the resin layer is in contact with the substrate, and then the carrier film is peeled off.

[0131] Examples of the substrate include printed wiring boards and flexible printed wiring boards on which circuits have been formed in advance using copper or the like, as well as copper-clad laminates for high-frequency circuits made from materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, and the like, including copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc.

[0132] When the film is in the form of a dry film, it is preferable to apply pressure and heat to the substrate using a vacuum laminator or the like. By using such a vacuum laminator, even if a circuit-formed substrate is used, the dry film adheres tightly to the circuit substrate, even if the circuit substrate surface is uneven, preventing the inclusion of air bubbles and improving the filling of recesses in the substrate surface. The pressure condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 120°C.

[0133] When the cured resin composition contains an organic solvent, it is preferable to apply the cured resin composition to the surface of a substrate and then perform volatilization drying. The volatilization drying can be performed using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air in a dryer equipped with a heat source of an air heating method using steam is brought into countercurrent contact with the substrate, or a method in which hot air is blown onto the substrate from a nozzle).

[0134] After forming a resin layer on a substrate, the resin layer is selectively exposed to active energy rays through a photomask having a predetermined pattern formed thereon, and the unexposed areas are developed with a dilute alkaline aqueous solution (e.g., a 0.3 to 3 mass % aqueous sodium carbonate solution) to form a patterned cured product. In the case of a dry film, after exposure, the first film is peeled from the dry film and development is carried out, thereby forming a patterned cured product on the substrate. In the case of a dry film form, the first film may be peeled from the dry film before exposure, and the exposed resin layer may be exposed and developed, as long as the properties are not impaired.

[0135] The exposure device used for the active energy ray irradiation may be any device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, or the like, and capable of irradiating ultraviolet rays in the range of 350 to 450 nm. Furthermore, a direct imaging device (for example, a laser direct imaging device that draws an image directly with a laser based on CAD data from a computer) may also be used. The lamp or laser light source of the direct imaging device may have a maximum wavelength in the range of 350 to 450 nm. The exposure dose for image formation varies depending on factors such as the film thickness, but is generally 10 to 1,000 mJ / cm. ２ , preferably 20 to 800 mJ / cm ２ The range may be:

[0136] The developing method may be a dipping method, a shower method, a spray method, a brush method, or the like, and the developing solution may be an aqueous alkali solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, or an amine.

[0137] The cured product of the present invention can be obtained by heat curing (for example, at 100 to 220°C) after the above-mentioned exposure and development (main curing). In this case, it is preferable to irradiate the cured product with active energy rays after heat curing in order to adjust the average linear expansion coefficient to a range of 70 to 100 ppm / °C. By irradiating with active energy rays again after heat curing, the photopolymerizable monomers and the like can be further cured depending on the composition of the curable resin composition, making it possible to adjust the average linear expansion coefficient to the desired value, and as a result, the marking ink also has excellent adhesion after curing.

[0138] The irradiation of active energy rays after heat curing depends on the composition of the curable resin composition, but is preferably 500 to 2000 mJ / cm ２ As the exposure device, a high-pressure mercury lamp (80 W / cm ３ (3 lights) etc.

[0139] The cured product of the present invention is used, for example, to form a solder resist, coverlay, or interlayer insulating layer for electronic components such as printed wiring boards. It may also be used to form solder dams on printed wiring boards. Among these, it is preferably used to form a solder resist. When the cured product of the present invention is formed on a printed wiring board described below, marking ink can be easily applied to the surface, and a marker with excellent adhesion to the marking ink after curing and excellent visibility of letters and symbols can be formed on the surface.

[0140] The method for forming a cured product from the photosensitive resin composition of the present invention or the resin layer of the dry film thereof can also be the same as the above-mentioned method for producing the cured product of the present invention.

[0141] Furthermore, the cured product obtained from the photosensitive resin composition of the present invention or the resin layer of the dry film thereof can be exposed to light and developed to form a pattern of the cured product on a substrate, and then the cured product can be irradiated with active energy rays and then heat-cured (for example, at 100 to 220°C), or can be irradiated with active energy rays after heat-curing, or can be subjected to final finish curing (main curing) by heat-curing alone, thereby forming a coating (cured coating) made of the cured product that is excellent in various properties such as adhesion and hardness.

[0142] [Printed Wiring Board] The printed wiring board of the present invention comprises the cured product of the present invention, or a cured product obtained from the photosensitive resin composition of the present invention or a dry film thereof. The method for producing the cured product is as described above. Examples of substrates for forming the printed wiring board include printed wiring boards and flexible printed wiring boards on which circuits have been formed in advance using copper or the like, as well as copper-clad laminates for high-frequency circuits made from materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, and the like, including copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, and the like.

[0143] In the printed wiring board of the present invention, after the cured coating is formed on the substrate as described above, components such as electronic elements are mounted on the substrate by solder reflow processing. The solder reflow processing can be performed by a conventionally known method. Furthermore, solder reflow is generally performed under processing conditions such as 245 to 260°C for 5 to 10 seconds.

[0144] The photosensitive resin composition or dry film of the present invention is preferably used for producing electronic components such as printed wiring boards, and more preferably for forming a permanent coating. In this case, the photosensitive resin composition or dry film of the present invention is used to form a cured product by the method described above or the like. When the resin layer of the photosensitive resin composition or dry film of the present invention is insulating, it is preferably used to form a solder resist, a coverlay, or an interlayer insulating layer. The photosensitive resin composition of the present invention may also be used to form a solder dam.

[0145] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all by mass unless otherwise specified.

[0146] Synthesis Example 1 (Synthesis of Carboxyl Group-Containing Resin Varnish A1-1) 220 parts of orthocresol novolac epoxy resin (EPICLON N-695, manufactured by DIC Corporation, epoxy equivalent: 214, average functionality: 7.6) was placed in a four-neck flask equipped with a stirrer and reflux condenser, and 214 parts of carbitol acetate was added and dissolved by heating. Next, 0.1 parts of hydroquinone as a polymerization inhibitor and 2.0 parts of dimethylbenzylamine as a reaction catalyst were added. This mixture was heated to 95-105°C, and 72 parts of acrylic acid was slowly added dropwise, allowing the reaction to proceed for 16 hours. The reaction product was cooled to 80-90°C, and 106 parts of tetrahydrophthalic anhydride was added. The reaction was allowed to proceed for 8 hours, cooled, and then discharged. The carboxyl group-containing resin solution thus obtained had a solids content of 65%, an acid value of the solids of 85 mgKOH / g, and a weight-average molecular weight of 10,000. Hereinafter, this resin solution will be referred to as varnish A1-1.

[0147] Synthesis Example 2 (Synthesis of Carboxyl Group-Containing Resin A1-2) 200 parts of a phenol novolac epoxy resin (P-201, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent = 200) and 96.4 parts of carbitol acetate as a solvent were added to a flask equipped with a thermometer, a stirrer, a dropping funnel, and a reflux condenser, and the mixture was heated to dissolve. Subsequently, 0.1 parts of hydroquinone as a polymerization inhibitor and 2.0 parts of triphenylphosphine as a reaction catalyst were added. This mixture was heated to 95 to 105°C, and 72 parts of acrylic acid were gradually added dropwise. The mixture was reacted for approximately 16 hours until the acid value reached 3.0 mgKOH / g or less. After cooling the reaction product to 80 to 90°C, 76.1 parts of tetrahydrophthalic anhydride were added. Infrared absorption analysis revealed an absorption peak of the acid anhydride (1780 cm). －１The reaction was continued for approximately 6 hours until all the solvent had disappeared. 96.4 parts of Ipsol #150 aromatic solvent, manufactured by Idemitsu Petrochemical Co., Ltd., was added to the reaction solution, which was then diluted and removed. The carboxyl group-containing resin solution thus obtained had a solids content of 65%, an acid value of the solids of 78 mgKOH / g, and a weight-average molecular weight of 8,000. Hereinafter, this resin solution will be referred to as Varnish A1-2.

[0148] Synthesis Example 3 (Synthesis of Carboxyl Group-Containing Resin Varnish A2-1) 371 parts of bisphenol A epoxy resin (epoxy equivalent: 650 g / eq, softening point: 81.1°C) having an average degree of polymerization n of 3.3 and 925 parts of epichlorohydrin were dissolved in 462.5 parts of dimethyl sulfoxide, and then 52.8 parts of 98.5% sodium hydroxide was added over 100 minutes at 70°C with stirring. After the addition, the reaction was continued for another 3 hours at 70°C. After completion of the reaction, 250 parts of water was added and the mixture was washed with water. After oil-water separation, most of the dimethyl sulfoxide and excess unreacted epichlorohydrin were recovered from the oil layer by distillation under reduced pressure, and the remaining reaction product containing by-product salts and dimethyl sulfoxide was dissolved in 750 parts of methyl isobutyl ketone, to which 10 parts of 30% sodium hydroxide was added, followed by reaction at 70°C for 1 hour. After completion of the reaction, the mixture was washed twice with 200 parts of water. After oil-water separation, methyl isobutyl ketone was recovered by distillation from the oil layer, yielding an epoxy resin with an epoxy equivalent of 287 g / eq and a softening point of 64.2°C. Based on the epoxy equivalent, the resulting epoxy resin was found to have approximately 3.1 of the 3.3 alcoholic hydroxyl groups in the starting bisphenol A epoxy resin epoxidized. 310 parts of the resulting epoxy resin and 282 parts of carbitol acetate were charged into a flask, heated to 90°C, stirred, and dissolved. The resulting solution was cooled to 60°C, and then 72 parts (1 mol) of acrylic acid, 0.5 parts of methylhydroquinone, and 2 parts of triphenylphosphine were added. The mixture was heated to 100°C and reacted for approximately 60 hours, yielding a reaction product with an acid value of 0.2 mgKOH / g. 140 parts (0.92 mol) of tetrahydrophthalic anhydride was added and heated to 90°C to obtain a carboxyl group-containing resin solution. The carboxyl group-containing resin solution thus obtained had a solids content of 64.0%, an acid value of the solids content of 100 mg KOH / g, and a weight average molecular weight of 15,000. Hereinafter, this resin solution will be referred to as varnish A2-1.

[0149] Synthesis Example 4 (Synthesis of Carboxyl Group-Containing Resin Varnish A2-2) 380 parts of bisphenol F epoxy resin (epoxy equivalent: 950 g / eq, softening point: 85°C) having an average degree of polymerization n of 6.2 and 925 parts of epichlorohydrin were dissolved in 462.5 parts of dimethyl sulfoxide, and then 60.9 parts (1.5 mol) of 98.5% sodium hydroxide was added over 100 minutes at 70°C with stirring. After the addition, the reaction was continued for another 3 hours at 70°C. After completion of the reaction, 250 parts of water was added and the mixture was washed with water. After oil-water separation, most of the dimethyl sulfoxide and excess unreacted epichlorohydrin were recovered from the oil layer by distillation under reduced pressure, and the remaining reaction product containing by-product salts and dimethyl sulfoxide was dissolved in 750 parts of methyl isobutyl ketone, to which 10 parts of 30% sodium hydroxide was added, followed by reaction at 70°C for 1 hour. After completion of the reaction, the mixture was washed twice with 200 parts of water. After oil-water separation, methyl isobutyl ketone was recovered by distillation from the oil layer, yielding an epoxy resin with an epoxy equivalent of 310 g / eq and a softening point of 69°C. Based on the epoxy equivalent, the resulting epoxy resin was found to have approximately 5 of the 6.2 alcoholic hydroxyl groups in the starting bisphenol F epoxy resin epoxidized. 310 parts of the resulting epoxy resin and 282 parts of carbitol acetate were charged into a flask, heated to 90°C, stirred, and dissolved. The resulting solution was cooled to 60°C, and then 72 parts (1 mol) of acrylic acid, 0.5 parts of methylhydroquinone, and 2 parts of triphenylphosphine were added. The mixture was heated to 100°C and reacted for approximately 60 hours, yielding a reaction product with an acid value of 0.2 mgKOH / g. 140 parts (0.92 mol) of tetrahydrophthalic anhydride was added and heated to 90°C to obtain a carboxyl group-containing resin solution. The carboxyl group-containing resin solution thus obtained had a solids content of 65.0%, an acid value of the solids content of 100 mg KOH / g, and a weight average molecular weight of 15,000. Hereinafter, this resin solution is referred to as varnish A2-2.

[0150] Synthesis Example 5 (Synthesis of Carboxyl Group-Containing Resin Varnish A3-1) 900 parts of diethylene glycol dimethyl ether as a solvent was added to a 2-L separable flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel, and nitrogen inlet tube, and heated to 90°C. After heating, 309.9 parts of methacrylic acid, 116.4 parts of methyl methacrylate, and 109.8 parts of lactone-modified 2-hydroxyethyl methacrylate (Daicel Corporation, PLACCEL FM1) were added dropwise over 3 hours along with 21.4 parts of a polymerization initiator, bis(4-t-butylcyclohexyl)peroxydicarbonate (NOF Corporation, PERLOYL TCP), and the mixture was further aged for 6 hours to obtain a product. The reaction was carried out under a nitrogen atmosphere. Next, 363.9 parts of 3,4-epoxycyclohexylmethyl acrylate (Cyclomer A200, manufactured by Daicel Corporation), 3.6 parts of dimethylbenzylamine as a ring-opening catalyst, and 1.80 parts of hydroquinone monomethyl ether as a polymerization inhibitor were added to the resulting product, and the mixture was heated to 100°C and stirred to carry out an epoxy ring-opening addition reaction. After 16 hours, a carboxyl group-containing resin was obtained with a solids content of 53.8%, an acid value of the solids content of 108.9 mgKOH / g, and a weight-average molecular weight of 25,000. Hereinafter, this resin solution is referred to as Varnish A3-1.

[0151] Synthesis Example 6 (Synthesis of Carboxyl Group-Containing Resin A3-2) 42 parts of methacrylic acid, 43 parts of methyl methacrylate, 35 parts of styrene, 100 parts of carbitol acetate, 0.5 parts of lauryl mercaptan, and 4 parts of azobisisobutyronitrile were added to a four-neck flask equipped with a reflux condenser, a thermometer, a glass tube for nitrogen substitution, and a stirrer. The mixture was heated at 75°C for 5 hours under a nitrogen stream to allow the polymerization reaction to proceed, yielding a carboxyl group-containing resin solution having a solids content of 50%, an acid value of the solids content of 120 mgKOH / g, and a weight average molecular weight of 25,000. Hereinafter, this resin solution will be referred to as varnish A3-2.

[0152] Synthesis Example 7 (Synthesis of Carboxyl Group-Containing Resin Varnish B1) Into an autoclave equipped with a thermometer, a nitrogen introducing device / alkylene oxide introducing device, and a stirrer, 119.4 parts of a novolac cresol resin (Shonol CRG951 manufactured by Aica Kogyo Co., Ltd., OH equivalent: 119.4), 1.19 parts of potassium hydroxide, and 119.4 parts of toluene were charged, and the system was purged with nitrogen while stirring, and heated to an elevated temperature. Next, 63.8 parts of propylene oxide was slowly added dropwise, and the temperature was raised to 125 to 132°C and 0 to 4.8 kg / cm. ２ The mixture was reacted at 100°C for 16 hours. The mixture was then cooled to room temperature, and 1.56 parts of 89% phosphoric acid was added to and mixed with the reaction solution to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac cresol resin with a solids content of 62.1% and a hydroxyl value of 182.2 g / eq. This solution had an average of 1.08 moles of alkylene oxide added per equivalent of phenolic hydroxyl group. Next, 293.0 parts of the resulting alkylene oxide reaction solution of novolac cresol resin, 43.2 parts of acrylic acid, 11.53 g of methanesulfonic acid, 0.18 parts of methylhydroquinone, and 252.9 parts of toluene were charged into a reactor equipped with a stirrer, thermometer, and air inlet tube, and the mixture was reacted at 110°C for 12 hours while stirring and blowing air at a rate of 10 ml / min. The water produced by the reaction was distilled as an azeotrope with toluene, and 12.6 parts of water were distilled. After that, the mixture was cooled to room temperature, and the resulting reaction solution was neutralized with 35.35 parts of 15% aqueous sodium hydroxide solution and then washed with water. Then, the toluene was distilled off using an evaporator while being replaced with 118.1 parts of carbitol acetate, resulting in a novolac acrylate resin solution. Subsequently, 332.5 parts of the resulting novolac acrylate resin solution and 1.22 parts of triphenylphosphine were charged into a reactor equipped with a stirrer, thermometer, and air inlet tube, and 60.8 parts of tetrahydrophthalic anhydride were gradually added while blowing air at a rate of 10 ml / min and stirring. The mixture was allowed to react at 95 to 101 °C for 6 hours. In this way, a resin solution of a carboxyl group-containing photosensitive resin with a solids content of 71%, an acid value of the solids content of 88 mg KOH / g, and a weight-average molecular weight of 2,500 was obtained. Hereinafter, this resin solution will be referred to as varnish B1.

[0153] Synthesis Example 8 (Synthesis of Carboxyl Group-Containing Resin Varnish B2) 220 parts of a cresol novolac epoxy resin (EOCN-104S, manufactured by Nippon Kayaku Co., Ltd., softening point 92°C, epoxy equivalent 220) and 40.2 parts of dimethylolpropionic acid were placed in a flask equipped with a stirrer, a condenser, and a thermometer, and 260 parts of carbitol acetate was added and dissolved by heating at 90°C. Next, this resin solution was cooled to 60°C, and 0.7 parts of triphenylphosphine was added, heated to 100°C, and reacted for approximately 32 hours to obtain a resin solution with a solids content of 50% and an epoxy equivalent of 371 g / equivalent. Next, 203 parts of 1,5-dihydroxynaphthalene (hydroxyl group equivalent weight 80 g / equivalent) and 1,097 parts of bisphenol A epoxy resin Epiclon-840 (manufactured by DIC Corporation, epoxy equivalent weight 180) were charged into a reaction vessel equipped with a gas inlet tube, a stirrer, a condenser, a thermometer, and a dropping funnel for continuous dropwise addition of an alkali metal hydroxide aqueous solution, and dissolved at 120°C with stirring under a nitrogen atmosphere. Thereafter, 0.65 parts of triphenylphosphine was added, and the temperature inside the flask was raised to 150°C. The reaction was allowed to proceed for approximately 90 minutes while maintaining the temperature at 150°C, yielding an epoxy compound with an epoxy equivalent weight of 365 g / equivalent. The temperature inside the flask was then cooled to below 70°C, and 2,058 parts of epichlorohydrin and 1,690 parts of dimethyl sulfoxide were added, followed by stirring and maintaining the temperature at 70°C. Thereafter, 244 parts of 48% sodium hydroxide was continuously added dropwise over 90 minutes, and the mixture was then allowed to react for an additional 3 hours. After completion of the reaction, most of the excess epichlorohydrin and dimethyl sulfoxide were recovered by distillation under reduced pressure, and the reaction product containing by-product salts and dimethyl sulfoxide was dissolved in methyl isobutyl ketone and washed with water. After separating the organic solvent layer and the aqueous layer, the methyl isobutyl ketone was distilled off from the organic solvent layer by distillation under reduced pressure, yielding a polynuclear epoxy compound with an epoxy equivalent weight of 275 g / equivalent (epoxidation rate of alcoholic hydroxyl groups: approximately 48%). Next, 371 parts of the resin solution prepared as described above and 137.5 parts of a polynuclear epoxy compound were placed in a flask equipped with a stirrer, a condenser, and a thermometer, 137 parts of carbitol acetate was added, and the mixture was heated to dissolve. 0.46 parts of methylhydroquinone and 1.38 parts of triphenylphosphine were added, and the mixture was heated to 95 to 105°C. 72 parts of acrylic acid was gradually added dropwise, and the mixture was allowed to react for 16 hours.The reaction product was cooled to 80-90°C, and 146 parts of tetrahydrophthalic anhydride was added and allowed to react for 8 hours. The reaction was monitored by measuring the oxidation and total oxidation of the reaction solution by potentiometric titration, and the reaction was terminated when the reaction rate reached 95% or higher. In this way, a resin solution containing a carboxyl group-containing resin was obtained with a solids content of 62%, an acid value of the solids content of 102 mgKOH / g, and a weight-average molecular weight of 10,000. Hereinafter, this resin solution will be referred to as Varnish B2.

[0154] Synthesis Example 9 (Synthesis of Carboxyl Group-Containing Resin Varnish B3) To 650 parts of carbitol acetate, 1,070 parts of orthocresol novolac epoxy resin (DIC Corporation, EPICLON N-695, softening point 95 ° C., epoxy equivalent 214, average functionality 7.6), 360 parts of acrylic acid, and 1.5 parts of hydroquinone were charged, heated to 100 ° C., and stirred to obtain a uniform solution. Next, 4.3 parts of triphenylphosphine were charged, heated to 110 ° C., and reacted for 2 hours. After that, 1.6 parts of triphenylphosphine was added, and the temperature was raised to 120 ° C. and the reaction was continued for another 12 hours. To the resulting reaction solution, 525 parts of an aromatic hydrocarbon (Standard Oil Corporation, Osaka Sales Co., Ltd., Teesol 150) and 608 parts (4.0 mol) of tetrahydrophthalic anhydride were charged, and the reaction was continued for 4 hours at 110 ° C. Furthermore, 142.0 g of glycidyl methacrylate was added to the resulting reaction solution, and the reaction was carried out at 115°C for 4 hours. In this way, a resin solution of a carboxyl group-containing resin was obtained with a solid content of 65%, an acid value of the solid content of 77 mgKOH / g, and a weight-average molecular weight of 11,000 to 12,000. Hereinafter, this resin solution will be referred to as Varnish B3.

[0155] <Preparation of Curable Resin Compositions> The components shown in Table 1 below were blended and mixed at room temperature using a three-roll mill to obtain the curable resin compositions shown in the table. Each value in the table indicates parts by mass. The blended amount (value) of each component indicates the blended amount of solids (the organic solvent (carbitol acetate) shown in the table is the actual blended amount).

[0156] The components *1 to *18 in Table 1 below are as follows: *1: Dipentaerythritol penta- and hexaacrylate, photopolymerizable monomer (DPHA, manufactured by Kyoeisha Chemical Co., Ltd.) *2: Urethane acrylate, oligomer (CN9178, manufactured by Arkema (Sartomer)) *3: Cresol novolac epoxy resin (RN-695, manufactured by DIC Corporation) *4: Triepoxy resin having an isocyanuric ring (TEPIC-S, manufactured by Nissan Chemical Industries, Ltd.) *5: Bisphenol A epoxy resin (jER 828, manufactured by Mitsubishi Chemical Corporation) *6: Dicyclopentadiene skeleton-containing multifunctional solid epoxy resin (HP-7200, manufactured by DIC Corporation) *7: Biphenyl aralkyl epoxy resin (YX-4000, manufactured by Nippon Kayaku Co., Ltd.) *8: Biphenyl aralkyl epoxy resin (NC3000H, manufactured by Mitsubishi Chemical Corporation) *9: α-aminoacetophenone-based photopolymerization initiator (Omnirad 907, manufactured by IGM Resins) *10: Acylphosphine oxide-based photopolymerization initiator (Omnirad 819, manufactured by IGM Resins) *11: α-aminoacetophenone-based photopolymerization initiator (Omnirad 369, manufactured by IGM Resins) *12: Titanocene-based photopolymerization initiator (JMT-784, manufactured by Yueyang Kimoutain Sci-tech Co., Ltd.) *13: Amorphous silica (FS-3DC, manufactured by Denka Company, Ltd., D50 = 2.9 μm) *14: Amorphous silica (HS-311, manufactured by Nippon Steel Chemical & Material Co., Ltd., D50 = 2.2 μm) * 15: Talc (LMP-100, manufactured by Fuji Talc Industry Co., Ltd.) * 16: Barium sulfate (B-100, manufactured by Sakai Chemical Industry Co., Ltd.) * 17: 2,4-diethylthioxanthone (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.) * 18: 2-isopropylthioxanthone (KAYACURE ITX, manufactured by Nippon Kayaku Co., Ltd.) * 19: Melamine (manufactured by Nissan Chemical Co., Ltd., D50 = 0.5 μm)

[0157] <Preparation of Cured Product> The curable resin compositions of the Examples and Comparative Examples were solid-printed by screen printing onto a copper-clad laminate for printed wiring boards (FR-4, thickness 1.6 mm, size 150 × 95 mm) so that the dry coating film was 20 μm thick, and then dried at 80°C for 30 minutes to form a coating film. Next, the coating film was exposed to light in a pattern that left the entire surface, and then cured at 30°C with 1 wt% Na ２ CO ３ The exposure was carried out for 60 seconds in a solution. After drying, the film was exposed through a step tablet (Kodak No. 2) using an exposure device equipped with a metal halide lamp, and developed (30°C, 0.2 MPa, 30°C, 1 wt% Na ２ CO ３ The optimum exposure dose was determined when the remaining step tablet pattern was 7 steps when the solution was applied for 60 seconds. After exposure and development, the resin was cured at 150°C for 30 minutes. After curing, Examples 1 and 2 and Comparative Example 2 were further irradiated with a high-pressure mercury lamp (80 W / cm ３ 3 lamps 1000mJ / cm ２ ) to irradiate the surface of the coating film, thereby obtaining a test substrate 1 on which a cured product (cured coating) was formed.

[0158] <Evaluation of Physical Properties of Cured Products> The average coefficient of linear expansion from 0 to 180°C and glass transition temperature (Tg) of the resulting cured products were measured as follows. The cured products obtained as described above were cut into test pieces 3 mm wide and 30 mm long, and the thermal expansion coefficient was measured in tension mode using a thermomechanical analyzer (TMA / SS6000, manufactured by Seiko Instruments Inc.). The maximum tensile load was 50 N / m, the span (distance between chucks) was 10 mm, and the heating rate was 10°C / min. The test pieces were mounted in the thermomechanical analyzer, heated from 30°C to 200°C, allowed to stand for 10 minutes, cooled to -30°C at a cooling rate of -10°C / min, and then measured from -30°C to 250°C at a heating rate of 10°C / min. The measured values ​​at 0°C and 180°C were read, and the average coefficient of linear expansion (α) was calculated using the following formula: α=(1 / LS)×[{L(180)-L(0)} / (T(180)-T(0)] (In the formula, LS: length of test piece (cured product) before measurement (measured value) L(0): change in length of test piece (cured product) at 0°C (measured value) L(180): change in length of test piece (cured product) at 180°C (measured value) T(0): 0 (°C) T(180): 180 (°C).) From the obtained TMA curve, a line A passing through two points, 0°C and 30°C, and a line B passing through two points, 150°C and 180°C, were drawn, and the temperature at the point where line A and line B intersect (extrapolated point) was taken as the Tg of the cured product of the present invention. The measurement results are shown in Table 1 below.

[0159]

[0160] <Marking Evaluation> (1) Printability A marking ink (PMR-6000 W30, manufactured by Taiyo Ink Mfg. Co., Ltd.) was used to print a rectangle measuring 10 x 20 mm onto the surface of the cured coating film of the test substrate obtained as described above, so that the film thickness after curing would be 20 μm. This was dried at 80°C for 30 minutes to form a marker. The printed state of the marker portion was visually confirmed, and the marking printability was evaluated according to the following evaluation criteria. ○: No bleeding or fading was observed ×: Bleeding or fading was observed The evaluation results are shown in Table 2 below.

[0161] (2) Adhesion: A marking ink (PMR-6000 W30, manufactured by Taiyo Ink Mfg. Co., Ltd.) was used to print a rectangle of 10 x 20 mm on the surface of the cured coating of the test substrate obtained as described above, so that the film thickness after curing would be 20 μm. After drying at 80°C for 30 minutes, the printed area was exposed to light in a pattern that would leave letters and symbols of approximately 10 to 20 μm in thickness. This was then heated at 30°C with 1 wt% Na ２ CO ３ After drying, the film was exposed through a step tablet (Kodak No. 2) using an exposure device equipped with a metal halide lamp, and developed (30°C, 0.2 MPa, 30°C, 1 wt% Na ２ CO ３ The optimum exposure was determined to be the amount of exposure when the remaining step tablet pattern had eight steps when the developed solution was applied for 60 seconds. The developed coating film was then washed with 10°C water for 60 seconds and cured at 180°C for 45 minutes to form a marker. Next, adhesive tape was applied to the marker portion, and a peeling test was carried out. The evaluation criteria were as follows: ⊚: No peeling; ∘: Slight peeling observed in some areas; ×: Peeling observed over the entire surface. The evaluation results are shown in Table 2 below.

[0162] (3) Visibility of Marker For the evaluation samples that had been subjected to the adhesion evaluation in (2) above, it was visually confirmed whether the letters and symbols on the marker portion were legible. The evaluation criteria for marker visibility were as follows: ⊚: All letters and symbols were legible. ◯: Some letters and symbols were difficult to read. ×: Letters and symbols were difficult to read throughout. The evaluation results are shown in Table 2 below.

[0163]

[0164] As is clear from Table 1, cured products (Examples 1 to 3) having an average linear expansion coefficient within the range of 70 to 100 ppm / °C upon a temperature change from 0 to 180°C exhibited good printability with marking ink, excellent adhesion to the marking ink, and enabled the formation of markers with excellent visibility of letters and symbols. In contrast, cured products having an average linear expansion coefficient of less than 70 ppm / °C or greater than 100 ppm / °C (Comparative Examples 2 and 3) exhibited poor printability with marking ink and insufficient adhesion to the marking ink. Furthermore, cured products formed using curable resin compositions that did not contain amorphous silica, even when having an average linear expansion coefficient within the range of 70 to 100 ppm / °C upon a temperature change from 0 to 180°C, exhibited poor printability with marking ink and insufficient adhesion to the marking ink, similar to the other comparative examples.

[0165] <Preparation of Photosensitive Resin Compositions> The components shown in Table 3 below were blended and mixed at room temperature using a three-roll mill to obtain the photosensitive resin compositions shown in the table. Note that each value in the table indicates parts by mass. The blend amount of each carboxyl group-containing resin in the table represents the blend amount in the varnish obtained as described above. Note that each component *1 to *19 in Table 3 below is as described above.

[0166] <Evaluation of Photosensitive Resin Compositions> (1) Evaluation of Redeposition of Development Residue This evaluation was carried out to evaluate the suppression of plating defects. Specifically, each photosensitive resin composition obtained as described above was used to form a coating film by double-sided screen printing on a substrate having a buffed pad area of ​​0.5 m x 0.5 m x 1.6 mm and a comb-shaped L / S = 100 μm / 100 μm pattern so that the film thickness after development would be 20 μm. Next, the substrate with the coating film formed was held for 10 minutes, and then dried at 80°C for 40 minutes in a hot air circulation drying oven. The substrate with the dried coating film was left at room temperature for 30 minutes, and then 1% Na ２ CO ３One hundred sheets were developed using a developing machine (solder resist developing device (150 L tank) manufactured by Tokyo Kakoki Co., Ltd.) containing an aqueous solution (liquid temperature 30°C), and the number of redeposited development residues was visually confirmed. The evaluation criteria were as follows: ○: 0 redeposited particles △: 1 to 9 redeposited particles ×: 10 or more redeposited particles The evaluation results are shown in Table 3 below.

[0167] (2) PCBT (Pressure Cooker Bias Test) This test was conducted to evaluate the characteristics (insulation reliability) required for solder resist. Specifically, each photosensitive resin composition was used to form a coating film by double-sided screen printing on a substrate having a comb-shaped L / S = 100 μm / 100 μm pattern with pads, so that the film thickness after development would be 20 μm. Next, the substrate with the coating film formed thereon was dried in a hot air circulation drying oven at 80°C for 40 minutes. After leaving the substrate with the dried coating film at room temperature for 30 minutes, a 400 mJ / cm ２ and 1% Na ２ CO ３ Development was carried out for 60 seconds using a developing machine (solder resist developing device (150 L tank) manufactured by Tokyo Kakoki Co., Ltd.) containing an aqueous solution (liquid temperature 30°C). Subsequently, a post-cure treatment was carried out at 150°C for 60 minutes to harden the coating film, and a substrate (hereinafter referred to as "test substrate") with a cured coating was produced. The insulation reliability of the obtained test substrate was continuously measured in the tank using an insulation degradation evaluation tester (MIG-8600B manufactured by IMV Corporation) at 121°C, 97% humidity, and an applied voltage of 30 V. The resistance value was 10 ６ The time until the resistance dropped below Ω and insulation was lost was measured. The evaluation criteria were as follows: ◎: 150 hours or more ○: 100 to 149 hours △: 50 to 99 hours ×: 49 hours or less The evaluation results are shown in Table 3 below.

[0168] (3) Plating Evaluation The following evaluation was performed to evaluate the suppression of plating defects. Specifically, the above test substrate was degreased by immersion in an acidic degreasing solution (20 vol% aqueous solution of Metex L-5B, manufactured by Nippon MacDermid Co., Ltd.) at 30°C for 3 minutes, and then immersed in running water for 3 minutes and rinsed with water. Next, the test substrate was immersed in a 14.3 wt% aqueous solution of ammonium persulfate at room temperature for 3 minutes to perform soft etching, and then immersed in running water for 3 minutes and rinsed with water. The test substrate was immersed in a 10 vol% aqueous solution of sulfuric acid at room temperature for 1 minute, and then immersed in running water for 30 seconds to 1 minute and rinsed with water. Next, the test substrate was immersed in a catalyst solution (10 vol% aqueous solution of Metal Plate Activator 350, manufactured by Meltex Co., Ltd.) at 30°C for 7 minutes to apply a catalyst, and then immersed in running water for 3 minutes and rinsed with water. The test substrate to which the catalyst had been applied was immersed in an 85°C nickel plating solution (a 20 vol% aqueous solution of Melplate Ni-865M, manufactured by Meltex Co., Ltd., pH 4.6) for 30 minutes to perform electroless nickel plating. The test substrate was then immersed in a 10 vol% aqueous sulfuric acid solution at room temperature for 1 minute, and then rinsed in running water for 30 seconds to 1 minute. The test substrate was then immersed in a 95°C gold plating solution (a 15 vol% aqueous solution of Aurolectroless UP and 3 vol% potassium gold cyanide, manufactured by Meltex Co., Ltd., pH 6) for 30 minutes to perform electroless gold plating to a thickness of 5 μm Ni and 0.05 μm Au. The test substrate was then rinsed in running water for 3 minutes and then immersed in warm water at 60°C for 3 minutes to perform hot water rinse. After thorough rinsing, the substrate was drained thoroughly and dried to obtain an electroless gold-plated test substrate.

[0169] The pad portions of the test substrates that had been electrolessly gold plated as described above were visually inspected for plating, and the presence or absence of undeposited plating was evaluated according to the following criteria: ○: No undeposited plating was observed △: Undeposited plating was observed in one location ×: Undeposited plating was observed in many locations The evaluation results are shown in Table 3 below.

[0170] The following evaluation was also made to assess the inhibition of contamination of the plating solution. Specifically, the pad portion of the test substrate was visually inspected for any abnormalities on the plated surface, and the presence or absence of abnormalities on the plated surface was evaluated according to the following criteria: ○: 0 abnormal locations △: 1 abnormal location ×: Many abnormal locations The evaluation results are shown in Table 3 below.

[0171]

[0172] As is clear from Table 3, photosensitive resin compositions (Examples 4 to 8) using a combination of three specific carboxyl group-containing resins in specific ratios satisfy the properties required for solder resists, such as insulation reliability, while suppressing plating solution contamination and plating defects. On the other hand, a photosensitive resin composition (Comparative Example 4) using only a carboxyl group-containing resin having a novolac skeleton as the carboxyl group-containing resin can suppress plating solution contamination and plating defects, but is insufficient in the properties required for solder resists, such as insulation reliability. Furthermore, a photosensitive resin composition (Comparative Example 5) using a combination of two carboxyl group-containing resins, a carboxyl group-containing resin having a novolac skeleton and a carboxyl group-containing resin having a bisphenol skeleton, and a photosensitive resin composition (Comparative Example 6) using a combination of two carboxyl group-containing resins, a carboxyl group-containing resin having a bisphenol skeleton and an unsaturated basic acid copolymerized carboxyl group-containing resin, likely caused abnormalities on the plating surface and contamination of the plating solution. In addition, it is found that a photosensitive resin composition (Comparative Example 7) that uses two types of carboxyl group-containing resins in combination, a carboxyl group-containing resin having a novolac skeleton and an unsaturated basic acid copolymer type carboxyl group-containing resin, causes defects such as plating non-adhesion due to the influence of residues in the developer.Furthermore, even when three specific types of carboxyl group-containing resins are combined, a photosensitive resin composition (Comparative Example 8) in which each component is outside the specified ratio range satisfies the properties required of a solder resist, such as insulation reliability, but causes defects such as plating non-adhesion due to the influence of residues in the developer, and also causes abnormalities in the plating surface and contamination of the plating solution.

Claims

1. A cured product comprising a curable resin composition containing a curable resin and an inorganic filler, The curable resin includes a thermosetting resin and a photocurable resin. The inorganic filler contains amorphous silica, A cured product characterized in that the average coefficient of linear expansion of the cured product when the temperature is changed from 0°C to 180°C is 70 to 100 ppm / °C.

2. The cured product according to claim 1, wherein the glass transition temperature (Tg) is in the range of 100 to 120°C.

3. The cured product according to claim 1, wherein the average coefficient of linear expansion of the cured product when the temperature is changed from 0°C to 180°C is 70 to 85 ppm / °C.

4. The cured product according to claim 1, wherein the amorphous silica is contained in an amount of 2 to 30% by mass relative to the entire curable resin composition on a solid content basis.

5. A cured product according to claim 1, used in solder resist.

6. A printed circuit board comprising a cured material according to claim 1 on a substrate.