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

Abstract

The present invention provides a curable resin composition which is capable of providing a cured product that has excellent insulation reliability while securing a range of process management at the time of pattern formation. The curable resin composition contains (A) a carboxyl group-containing resin that has an ethylenically unsaturated double bond in each molecule, (B) an imidazole compound, and (C) a thermosetting resin. The carboxyl group-containing resin (A) that has an ethylenically unsaturated double bond in each molecule contains (A1) a resin in which a terminal is modified with a GMA structure, and (A2) a resin other than the (A1). The content of the resin (A1) in which a terminal is modified with a GMA structure in the whole carboxyl group-containing resin (A) that has an ethylenically unsaturated double bond in each molecule is 70 mass% to 90 mass% inclusive in terms of solid content.

Description

S硬化 resin composition, dry film, cured product, and printed wiring board

[0001] The present invention relates to a curable resin composition, a dry film, a cured product, and a printed wiring board. Related application

[0002] This application claims priority based on Japanese Patent Application No. 2024-208920 filed in Japan on November 29, 2024, and incorporates the content herein.

[0003] In recent years, in response to the increasing density of printed wiring boards accompanying the thinning, lightening, and miniaturization of electronic devices, high performance and improved workability have been required for curable resin compositions for resin insulation layers such as solder resists. Further, with the miniaturization, lightening, and high performance of electronic devices, the miniaturization and multi-pinning of semiconductor packages have been put into practical use and mass production has also progressed. In response to the increasing density of electronic devices, IC packages such as BGA (Ball Grid Array) and CSP (Chip Scale Package) have emerged in place of IC packages such as QFP (Quad Flat Pack Package) and SOP (Small Outline Package). Conventionally, various photosensitive resin compositions have been proposed as solder resists used for such package substrates and printed wiring boards for vehicle mounting (see, for example, Patent Documents 1 and 2).

[0004] In a printed wiring board having a fine pitch wiring pattern such as a package substrate, since the wiring patterns are formed in a high density and in close proximity to each other, the risk of short circuits and crosstalk noise occurring between the lines of the wiring patterns increases. Therefore, high insulation reliability is required for high performance solder resists used for package substrates.

[0005] In addition, as the electrification of the drive unit of automobiles, especially, progresses, printed wiring boards are often mounted in places with high environmental temperatures such as the engine room and its surroundings. Printed wiring boards for vehicle mounting will be exposed to high temperatures of 80°C to 150°C for a long time depending on the mounting location.

[0006] Therefore, high-performance solder resists used in automotive printed circuit boards require high insulation reliability at high temperatures. Furthermore, because automotive substrates have thick circuits, spray application of solder resist is appropriate.

[0007] Furthermore, before forming a resin insulating layer such as solder resist, a pretreatment is usually performed to roughen the substrate surface in order to improve the adhesion of the resin insulating layer to the substrate. However, substrate pretreatment methods vary depending on the application, and strong roughening treatment is not always performed, which may result in insufficient anchoring effect. Therefore, it is necessary to ensure sufficient adhesion to the substrate regardless of the pretreatment method for the resin insulating layer. Patent Document 1 discloses a curable resin composition that achieves both insulating reliability and adhesion to the substrate.

[0008] Patent No. 5615415

[0009] However, the technology disclosed in Patent Document 1 does not take into consideration the expansion of process control in actual manufacturing when forming solder resist patterns by exposure.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a curable resin composition that can obtain a cured product with excellent insulation reliability while ensuring a wide range of process control during pattern formation. Furthermore, the present invention aims to provide a dry film, a cured product, and a printed circuit board obtained from the above curable resin composition.

[0011] Through repeated investigations into the above-mentioned problems, the present inventors have found that (A) using a carboxyl group-containing resin having an ethylenically unsaturated double bond in the molecule as a photosensitive resin is extremely effective in improving the insulation reliability of the cured product, and that (A) using a mixture containing (A1) a resin modified with a GMA structure at the end and (A2) a resin other than (A1) as the carboxyl group-containing resin having an ethylenically unsaturated double bond in the molecule, and (B) using an imidazole compound as a curing catalyst, the range of process control can be greatly expanded while maintaining insulation reliability. The present invention is based on these findings.

[0012] In other words, the gist of the present invention is as follows: [1] A curable resin composition comprising (A) a carboxyl group-containing resin having an ethylenically unsaturated double bond in its molecule, (B) an imidazole compound, and (C) a thermosetting resin, wherein the (A) carboxyl group-containing resin having an ethylenically unsaturated double bond in its molecule comprises (A1) a resin modified by a GMA structure at its terminus and (A2) a resin other than (A1), and the content of the resin modified by a GMA structure at its terminus in the entire carboxyl group-containing resin having an ethylenically unsaturated double bond in its molecule is 70% by mass or more and 90% by mass or less on a solid content basis. [2] The curable resin composition according to [1], wherein the content of the (B) imidazole compound in the entire curable resin composition is 0.5% by mass or more and 1.5% by mass or less on a solid content basis. [3] The curable resin composition according to [1] or [2], wherein the (B) imidazole compound is solid or semi-solid at room temperature. [4] The curable resin composition according to any one of [1] to [3], wherein the (C) thermosetting resin comprises an epoxy resin. [5] The curable resin composition according to any one of [1] to [4], further comprising (D) a (meth)acrylate monomer. [6] The curable resin composition according to any one of [1] to [5], further comprising (E) a photopolymerization initiator. [7] The curable resin composition according to any one of [1] to [6], further comprising (F) a filler compound. [8] The curable resin composition according to any one of [1] to [7], having a viscosity of 1 to 5 Ps, and used for spray coating. [9] A dry film having a resin layer obtained by coating and drying the curable resin composition according to any one of [1] to [7] onto a first film.

[10] A cured product obtained by curing the resin layer of the curable resin composition according to any one of [1] to [8] or the dry film according to [9].

[11] The cured product described in

[10] , used in solder resist.

[12] A printed circuit board having the cured product described in

[10] or

[11] on a substrate.

[0013] The curable resin composition of the present invention allows for the production of a cured product with excellent insulation reliability while ensuring a wide range of process control during pattern formation. Furthermore, the dry film of the present invention allows for the production of a cured product with excellent insulation reliability while ensuring a wide range of process control during pattern formation. In addition, the cured product and printed circuit board of the present invention exhibit excellent insulation reliability.

[0014] In this specification, a numerical range represented by "~" includes the numbers at both ends of that range.

[0015] [Definition] Photosensitivity is the property of a substance to undergo a chemical change when exposed to light. In this specification, "having photosensitivity" means that the resin components contained in a photosensitive resin composition polymerize and harden when exposed to light of a specific wavelength.

[0016] In this specification, "pattern formation possible" means that a pattern of a predetermined shape can be transferred to a resin layer made of a photosensitive resin composition by a photolithography process.

[0017] In this specification, "solid or semi-solid at room temperature" means "solid or semi-solid at 15°C." The determination of whether a substance is solid or semi-solid can be made in accordance with the "Method for Confirming Liquidity" in Appendix 2 of the Ministerial Ordinance Concerning the Testing and Properties of Hazardous Materials (Ministry of Home Affairs Ordinance No. 1 of 1989).

[0018] In this specification, "(meth)acrylate" is used as a general term for acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions. Similarly, "(meth)acryloyl group" is used as a general term for acryloyl groups, methacryloyl groups, and both thereof, and the same applies to other similar expressions.

[0019] [Curable Resin Composition] The curable resin composition of this disclosure comprises (A) a carboxyl group-containing resin having an ethylenically unsaturated double bond in the molecule (hereinafter also simply referred to as "component (A)"), (B) an imidazole compound, and (C) a thermosetting resin, wherein component (A) comprises (A1) a resin whose terminal is modified by a GMA structure (hereinafter also simply referred to as "component (A1)") and (A2) a resin other than component (A1) (hereinafter also simply referred to as "component (A2)"). The components constituting the curable resin composition will be described below.

[0020] <(A) Carboxyl group-containing resin having an ethylenically unsaturated double bond in the molecule> The curable resin composition of this disclosure contains component (A). As a result, the curable resin composition of this disclosure has excellent photocurability and developability. Component (A) can be any conventionally known carboxyl group-containing resin having a carboxyl group in the molecule, and a carboxyl group-containing photosensitive resin having an ethylenically unsaturated double bond in the molecule can be used. The ethylenically unsaturated double bond is preferably derived from acrylic acid or methacrylic acid or a derivative thereof. Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers).

[0021] (1) A carboxyl group-containing photosensitive urethane resin obtained by polyaddition reaction of diisocyanate with (meth)acrylate or partially acid anhydride-modified product thereof of a bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, or biphenol type epoxy resin, a carboxyl group-containing dialcohol compound, and a diol compound.

[0022] (2) A carboxyl group-containing photosensitive urethane resin obtained by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, to the synthesis of the resin described in (1) above, and then (meth)acrylizing the terminal.

[0023] (3) A carboxyl group-containing photosensitive urethane resin obtained by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in its molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, to the synthesis of the resin in (1) above, and then (meth)acrylicating the terminal.

[0024] (4) A carboxyl group-containing photosensitive resin obtained by reacting a bifunctional or polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chain.

[0025] (5) 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.

[0026] (6) A carboxyl group-containing polyester resin 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 group.

[0027] (7) A carboxyl group-containing 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 group of the resulting reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic anhydride.

[0028] (8) 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 reaction product obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0029] (9) 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 reaction product obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0030] (10) A carboxyl group-containing photosensitive resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins of (1) to (9) above.

[0031] The acid value of the carboxyl group-containing resin is preferably 30 mg KOH / g or more, more preferably 50 mg KOH / g or more, and preferably 150 mg KOH / g or less, or 120 mg KOH / g or less. The acid value of the carboxyl group-containing resin is, for example, in the range of 30 to 150 mg KOH / g. An acid value of 30 mg KOH / g or more facilitates alkaline development, while an acid value of 150 mg KOH / g or less is preferable because it provides sufficient resistance to the developer in the exposed area, allowing for reliable drawing of a normal resist pattern.

[0032] Furthermore, the weight-average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferred to be in the range of 2,000 to 150,000, and more preferably in the range of 5,000 to 100,000. When the weight-average molecular weight is 2,000 or higher, the developability of the film in the exposed area is improved, and the resolution is excellent. On the other hand, when the weight-average molecular weight is 150,000 or lower, the solubility of the unexposed area is good, the resolution is excellent, and storage stability may also be improved. Note that the weight-average molecular weight refers to the standard polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0033] The curable resin composition of this disclosure uses a mixture of component (A1) and component (A2) as component (A).

[0034] <(A1) Resin modified with a GMA structure at the end> ​​Component (A1) is a resin in which the ends of the molecular chains of the above-mentioned component (A) are modified with a glycidyl (meth)acrylate (GMA) structure. Component (A1) is a highly hydrophobic resin. Therefore, since the curable resin composition of this disclosure contains component (A1) as component (A), the deterioration of the coating film after curing of the resin composition by water is slowed down, and the effect of improved insulation reliability is obtained.

[0035] (A1) Component is, for example, a carboxyl group-containing photosensitive resin (A1a) obtained by reacting a polyfunctional epoxy resin such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A cresol novolac type epoxy resin, or dicyclopentadiene cresol novolac type epoxy resin with (meth)acrylic acid, and adding dibasic acid anhydrides such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chain, and the hydroxyl groups of the above polyfunctional epoxy resin Furthermore, a carboxyl group-containing photosensitive resin (A1b) is obtained by reacting a polyfunctional epoxy resin epoxidized with epichlorohydrin with (meth)acrylic acid, and adding a polybasic acid anhydride to the resulting hydroxyl groups; or a carboxyl group-containing photosensitive resin (A1c) is obtained by adding a cyclic ether such as ethylene oxide or a cyclic carbonate such as propylene carbonate to a polyfunctional phenol compound such as novolac resin, partially esterifying the resulting hydroxyl groups with (meth)acrylic acid, and reacting the remaining hydroxyl groups with a polybasic acid anhydride. Carboxyl group-containing photosensitive resin obtained by adding compounds having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate and α-methylglycidyl (meth)acrylate, to a lipid; Carboxyl group-containing photosensitive resin obtained by reacting a difunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin with (meth)acrylic acid, and adding a polybasic acid anhydride to the resulting hydroxyl group. Examples include a photosensitive resin containing a carboxyl group, obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in its molecule, such as glycidyl (meth)acrylate or α-methylglycidyl (meth)acrylate, to either a photosensitive resin (A1d), a polyfunctional epoxy resin in which the hydroxyl groups of the above-mentioned bifunctional epoxy resin are further epoxidized with epichlorohydrin, and a carboxyl group-containing photosensitive resin (A1e) obtained by reacting (meth)acrylic acid with the resulting hydroxyl groups and adding a polybasic acid anhydride to the hydroxyl groups; among these, (A1a) is preferred as (A1).

[0036] <(A2) Resins other than the above component (A1)> Component (A2) is a carboxyl group-containing resin other than the above component (A1) among the above components (A).

[0037] Components (A1) and (A2) are not limited to the carboxyl group-containing resins listed above. Furthermore, component (A) may be used individually as component (A1) and component (A2), or multiple types may be used in mixture form.

[0038] The curable resin composition of this disclosure has a content of (A1) of 70% by mass or more and 90% by mass or less in the total (A) component. When the above content is 70% by mass or more, the insulation reliability of the cured product is improved. When the above content is 90% by mass or less, the developability is improved. The content of (A1) of 75% by mass or more in the total (A) component is preferably 85% by mass or less.

[0039] <(B) Imidazole Compound> The curable resin composition of this disclosure contains (B) an imidazole compound (hereinafter also simply referred to as "component (B)"). Component (B) functions as a curing catalyst.

[0040] Examples of component (B) 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. Among these, those that are solid or semi-solid (powder) at room temperature are preferred, and specifically, 2-phenyl-4,5-dihydroxymethylimidazole is an example.

[0041] Component (B) can be used alone or in combination of two or more thereof selected from these. The content of component (B) in the entire curable resin composition is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and preferably 1.5% by mass or less, more preferably 1.2% by mass or less in terms of solid content. When the above content is 0.5% by mass or more, the cured product formed from the curable resin composition has excellent heat resistance. When the above content is 1.5% by mass or less, it leads to an improvement in the storage stability of the curable resin composition. The content of component (B) in the entire curable resin composition is, for example, 0.5% by mass or more and 1.5% by mass or less.

[0042] <(C) Thermosetting resin> The curable resin composition of the present disclosure contains (C) a thermosetting resin (hereinafter, also simply referred to as “component (C)”). As component (C), any known thermosetting resin can be used. Examples of the thermosetting resin include amino resins such as melamine resin, benzoguanamine resin, melamine derivatives, and benzoguanamine derivatives; isocyanate compounds; blocked isocyanate compounds; cyclo carbonate compounds; epoxy compounds; oxetane compounds; episulfide resins; bismaleimide; carbodiimide resins; and other known compounds. Among these, as the thermosetting resin, it is preferable to use a compound having a plurality of cyclic ether groups or cyclic thioether groups (hereinafter, abbreviated as cyclic (thio)ether groups) in the molecule, and it is particularly preferable to use an epoxy resin. These thermosetting resins can be used alone or in combination of two or more. By including component (C), the curable resin composition of the present disclosure can improve the strength of the cured product in the subsequent process.

[0043] The compound having a plurality of cyclic (thio)ether groups in the above 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, that is, a polyfunctional epoxy compound, a compound having a plurality of oxetanyl groups in the molecule, that is, a polyfunctional oxetane compound, and a compound having a plurality of thioether groups in the molecule, that is, an episulfide resin.

[0044] Examples of such epoxy compounds include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, novolac type epoxy resin of bisphenol A, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, and the like.

[0045] Examples of the 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, (3-ethyl-3-oxetanyl)methyl acrylate, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and other polyfunctional oxetanes such as their oligomers or copolymers. In addition, etherified products of oxetane alcohol with resins having hydroxyl groups such as novolac resin, poly(p-hydroxystyrene), cardo type bisphenols, calixarenes, calixresorcinarenes, or silsesquioxane can be used. Other examples include copolymers of unsaturated monomers having an oxetane ring and alkyl (meth)acrylate.

[0046] Examples of the compounds having a plurality of cyclic thioether groups in the molecule include bisphenol A type episulfide resin. In addition, episulfide resins obtained by replacing the oxygen atom of the epoxy group of novolac type epoxy resin with a sulfur atom using a similar synthesis method can also be used.

[0047] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylol melamine compounds, methylol benzoguanamine compounds, methylol glycoluril compounds, and methylol urea compounds.

[0048] Polyisocyanate compounds can be incorporated as isocyanate compounds. Examples of polyisocyanate compounds include 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 isocyanate compounds mentioned above.

[0049] As the blocked isocyanate compound, the addition reaction product of an isocyanate compound and an isocyanate blocking agent can be used. Examples of isocyanate compounds that can react with an isocyanate blocking agent include the polyisocyanate compounds mentioned above. Examples of isocyanate blocking agents include phenol-based blocking agents, lactam-based blocking agents, activated 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.

[0050] The content of component (C) is preferably such that the number of functional groups of component (C) that react is 0.8 to 2.5 mol, and more preferably 1.0 to 2.0 mol, per 1.0 mol of carboxyl groups contained in component (A). By setting the amount to 1 mol or more, the residual carboxyl groups in the cured product are prevented, and good heat resistance, alkali resistance, electrical insulation, etc., can be obtained. Furthermore, by setting the above blending amount to 2 mol or less, the residual low molecular weight components in the resin layer are prevented, and good strength, etc., of the cured product can be ensured.

[0051] The content of component (C) in the curable resin composition of this disclosure is preferably 5% by mass or more, more preferably 10% by mass or more, preferably 25% by mass or less, and more preferably 20% by mass or less, based on solid content, relative to the entire curable resin composition, from the viewpoint of adhesion to the substrate. For example, the content of component (C) in the entire curable resin composition is 5% by mass or more and 25% by mass or less.

[0052] <(D)(meth)acrylate monomer> The curable resin composition of this disclosure may contain (D)(meth)acrylate monomer (hereinafter also simply referred to as "component (D)"). The (meth)acrylate monomer is a monomer having an ethylenically unsaturated double bond. Examples of such (meth)acrylate monomers include conventionally known polyester (meth)acrylate, polyether (meth)acrylate, urethane (meth)acrylate, carbonate (meth)acrylate, epoxy (meth)acrylate, etc. Specifically, alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or diacrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; polyacrylates such as hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and trishydroxyethyl isocyanurate. Polyvalent acrylates derived from hydrogenic alcohols or their alkylene oxide adducts or ε-caprolactone adducts, etc.; polyvalent acrylates such as phenoxyacrylate, bisphenol A diacrylate, and other phenols or their alkylene oxide adducts; acrylates derived from glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, not limited to the above, acrylates obtained by directly acrylateting polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrylate obtained via diisocyanate, as well as melamine acrylate, and at least one of each methacrylate corresponding to the acrylate can be appropriately selected and used.Such (meth)acrylate monomers can also be used as reactive diluents.

[0053] Component (D) can be any one of the (meth)acrylate monomers listed above, either alone or in combination of two or more. The content of component (D) is preferably 0.5 to 50 parts by mass in terms of solid content per 100 parts by mass of component (A). When the content is 0.5 parts by mass or more, the photocurability is good and pattern formation is easy during alkaline development after irradiation with active energy rays. When the content is 50 parts by mass or less, halation is less likely to occur and good resolution can be obtained.

[0054] <(E) Photopolymerization Initiator> The curable resin composition of this disclosure may contain (E) a photopolymerization initiator (hereinafter also simply referred to as "component (E)"). Component (E) is not particularly limited, and any known photopolymerization initiator can be used. Furthermore, component (E) may be any one of the photopolymerization initiators listed below used alone, or two or more may be used in combination.

[0055] Examples of photopolymerization initiators include, specifically, 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-trimethylpentyl phenylphosphine oxide. Sphingoxides, bisacylphosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphine methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphine Monoacylphosphine oxides such as sopropyl esters and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-hydroxy Hydroxyacetophenones such as C-2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzyl, 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, Michla's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bis-diethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl 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 N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, Anthraquinones such as 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoate ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)], etanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyloxy Examples include oxime esters such as bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1H-pyrrole-1-yl)ethyl)phenyl]titanium, phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc.

[0056] Among the above-mentioned photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, such as monoacylphosphine oxide-based photopolymerization initiators and bisacylphosphine oxide-based photopolymerization initiators, are preferred because they possess photobleaching properties. Here, photobleaching, also known as photodecolorization or photodecolorization, is a reaction that occurs when a fluorescent substance in an excited state becomes chemically activated and unstable compared to its ground state. Specifically, when a compound acting as a photopolymerization initiator absorbs light in a specific wavelength range and generates radicals, the generation of radicals changes the structure of the compound, causing it to no longer absorb light in that wavelength range. As a result, it becomes easier for light in that wavelength range to pass through, making it easier for photocuring to occur to deeper layers.

[0057] The amount of component (E), excluding the oxime ester-based photopolymerization initiator, is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, preferably 30 parts by mass or less, and more preferably 15 parts by mass or less, based on solid content, per 100 parts by mass of component (A). When the above amount is 0.1 parts by mass or more, the photocurability of the curable resin composition of this disclosure is good, the cured product is less likely to peel off, and the properties of the cured product, such as chemical resistance, are also good. On the other hand, when the above amount is 30 parts by mass or less, an outgassing effect is obtained, light absorption on the surface of the cured product is good, and the deep curing performance is less likely to decrease. For example, the amount of component (E) per 100 parts by mass of component (A) is 0.1% by mass or more and 30% by mass or less.

[0058] Furthermore, the amount of oxime ester-based photopolymerization initiator blended is preferably 0.01% by mass or more, more preferably 0.5% by mass or more, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, based on solid content per 100 parts by mass of component (A). When the blending amount is 0.01 parts by mass or more, the photocurability of the curable resin composition of this disclosure is good, and the properties of the cured product, such as heat resistance and chemical resistance, are also good. On the other hand, when the blending amount is 5 parts by mass or less, light absorption on the surface of the cured product is good, and the deep curing properties are less likely to decrease. The blending amount of oxime ester-based photopolymerization initiator per 100 parts by mass of component (A) is, for example, 0.01% by mass or more and 5% by mass or less.

[0059] <(F) Filler Compound> The curable resin composition of this disclosure may contain a (F) filler compound (hereinafter also simply referred to as "component (F)"). By containing component (F), the curable resin composition of this disclosure can increase the physical strength of the cured product. Component (F) can be a known inorganic filler or an organic filler. Examples of inorganic fillers include 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, hydrated aluminum, hydrated gypsum, alum, and barium sulfate. Examples of organic fillers include silicone powder, nylon powder, fluororesin powder, and urethane beads. (F) Component may be any one of the inorganic fillers and organic fillers listed above, either alone or in combination of two or more.

[0060] Component (F) is preferably an inorganic filler, and among the inorganic fillers listed above, silica, talc, and barium sulfate are more preferred. The silica may be amorphous or crystalline, or a mixture thereof. Amorphous (fused) silica is particularly preferred.

[0061] From the viewpoint of dispersibility and other factors, the inorganic filler preferably has an average particle size (D50) of 0.1 to 100 μm, and more preferably 0.1 to 50 μm. The average particle size refers to the particle size at 50% volume cumulative, obtained using the laser diffraction scattering particle size distribution method. Furthermore, the average particle size of the inorganic filler refers to the value measured as described above for the filler before preparing the curable resin composition (pre-stirring, kneading).

[0062] The amount of component (F) in the curable resin composition of this disclosure is preferably 1 part by mass or more, more preferably 10 parts by mass or more, preferably 500 parts by mass or less, and more preferably 300 parts by mass or less, based on solid content, per 100 parts by mass of component (A). The above amount is, for example, 1 part by mass or more and 500 parts by mass or less. By having the amount of component (F) within the above range, the ability to prevent a decrease in adhesion and the resistance to thermal cycling of the curable resin composition can be further improved.

[0063] The inorganic filler described above may be surface-treated to improve its dispersibility in the curable resin composition. Using a surface-treated inorganic filler can suppress aggregation. The surface treatment method is not particularly limited, and any known and conventional method may be used, but it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a curable reactive group, for example, a coupling agent having a curable reactive group as an organic group.

[0064] As coupling agents, silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents can be used. 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, which can be used alone or in combination. It is preferable that these silane-based coupling agents are pre-immobilized on the surface of the inorganic filler by adsorption or reaction. Here, the amount of coupling agent treated per 100 parts by mass of inorganic filler is preferably 0.5 to 10 parts by mass.

[0065] The curable resin composition of this disclosure may contain colorants, organic solvents, and other optional components, within the range that provides the effects of the present invention.

[0066] <Colorants> The curable resin compositions of this disclosure may contain colorants. Commonly known colorants such as red, blue, green, yellow, white, and black can be used as colorants. The colorants may also be pigments, dyes, or pigments.

[0067] Specifically, examples of colorants include those that have a Color Index (C.I.; issued by The Society of Dyers and Colorists) number.

[0068] Examples of red colorants include monoazo, disazo, azolake, benzimidazolon, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone. Examples of blue colorants include phthalocyanine and anthraquinone, and compounds classified as pigments can be used. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Similarly, examples of green colorants include phthalocyanine, anthraquinone, and perylene. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Examples of yellow colorants include monoazo, disazo, condensed azo, benzimidazolon, isoindolinone, and anthraquinone. Examples of white colorants include rutile or anatase titanium dioxide. Examples of black colorants include carbon black, graphite, iron oxide, titanium black, anthraquinone, cobalt oxide, copper oxide, manganese, antimony oxide, nickel oxide, perylene, aniline, molybdenum sulfide, and bismuth sulfide. Other colorants such as purple, orange, and brown may be added to adjust the color tone.

[0069] From the viewpoint of improving the opacity of the cured product, the content of the coloring agent is preferably 0.18% by mass or more, more preferably 0.20% by mass or more, preferably 0.50% by mass or less, and more preferably 0.40% by mass, based on the total amount of the curable resin composition in terms of solid content. When the content of the coloring agent is 0.18% by mass or more in terms of solid content, the cured product formed from the curable resin composition has excellent circuit opacity, and when it is 0.50% by mass or less, the curable resin composition is used as a solder resist and exhibits superior resolution when patterned. For example, the content of the coloring agent is 0.18% by mass or more and 0.50% by mass or less.

[0070] <Organic Solvents> The curable resin compositions of this disclosure may contain organic solvents for purposes such as preparing the composition or adjusting the viscosity when applying it to a substrate or film. The organic solvents are not particularly limited, and known and commonly used organic solvents may be used. Examples of organic solvents 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. Organic solvents can be used individually or in combination of two or more of these.

[0071] <Other Optional Components> The curable resin composition of this disclosure may further contain, as needed, components such as photoinitiators, cyanate compounds, elastomers, mercapto compounds, urethane catalysts, thixonating agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper damage inhibitors, antioxidants, rust inhibitors, thickeners such as fine silica, organic bentonite, and montmorillonite, defoaming agents and / or leveling agents such as silicone-based, fluorine-based, and polymer-based agents, silane coupling agents such as imidazole-based, thiazole-based, and triazole-based agents, and flame retardants such as phosphinates, phosphate ester derivatives, and phosphazene compounds. These components may include those known in the field of electronic materials.

[0072] The curable resin composition of this disclosure is useful for forming pattern layers as permanent coatings for printed circuit boards, such as solder resists, coverlays, and interlayer insulating layers, and is particularly useful for forming solder resists. Furthermore, since the curable resin composition of this disclosure can form cured products with excellent insulating reliability while ensuring a wide range of process control during pattern formation, it can be suitably used for forming solder resists in printed circuit boards where high insulating reliability is required, such as semiconductor package substrates (printed circuit boards used in semiconductor packages) and automotive printed circuit boards.

[0073] The curable resin composition of this disclosure may be used as a liquid resin composition or as a dry film. Furthermore, when used as a liquid resin composition, it may be a one-component or two-component or more-component composition.

[0074] When the curable resin composition of this disclosure is used as a liquid resin composition, it is preferable to adjust the viscosity to a range of 1 to 5 Ps by appropriately adjusting, for example, the content of components (A) to (F) and the amount of organic solvent blended. By adjusting the viscosity to the above range, a curable resin composition that can be spray-applied can be provided.

[0075] By using a spray-applied curable resin composition for solder resist formation, it is possible to reliably form cured material from the curable resin composition between lines of wiring patterns that are formed in close proximity to each other, even on printed circuit boards with fine-pitch wiring patterns such as package substrates. As a result, the curable resin composition of this disclosure can achieve high insulation reliability.

[0076] Furthermore, although thick circuits are formed on automotive printed circuit boards, the curable resin composition of this disclosure allows for the application of solder resist by spraying, and since the steps in the wiring pattern can be reliably filled, high insulation reliability can be achieved even at high temperatures.

[0077] [Dry Film] The curable resin composition of this disclosure may also be in the form of a dry film comprising a first film and a resin layer formed from the curable resin composition laminated on the first film. In the dry film of this disclosure, the first film refers to a film that is at least adhered to the resin layer when laminated onto a substrate such that the resin layer side of the dry film is in contact with the substrate. The first film may be peeled off from the resin layer in a process after lamination. In particular, in this disclosure, it is preferable to peel it off from the resin layer in a process after exposure.

[0078] To produce a dry film, the curable resin composition of this disclosure is diluted with an organic solvent to an appropriate viscosity, and then applied to a first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, etc. The film is usually dried at a temperature of 50 to 130°C for 1 to 30 minutes. There are no particular restrictions on the coated film thickness, but generally, the film thickness after drying is appropriately selected in the range of 1 to 150 μm, preferably 5 to 60 μm.

[0079] The first film can be any known film without particular limitations, and for example, films made of thermoplastic resins such as polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyimide films, polyamide-imide films, polypropylene films, and polystyrene films can be suitably used. Among these, polyester films are preferred from the viewpoint of heat resistance, mechanical strength, and ease of handling. Laminates of these films can also be used as the first film.

[0080] Furthermore, from the viewpoint of improving mechanical strength, the thermoplastic resin film described above is preferably a film stretched in one or two axes.

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

[0082] After forming a resin layer of the curable resin composition of this disclosure on the first film, it is preferable to further laminate a peelable second film onto the surface of the resin layer for purposes such as preventing dust from adhering to the surface of the resin layer. In the dry film of this disclosure, the second film refers to a film that is peeled off from the resin layer before lamination when the dry film is laminated onto a substrate so that the resin layer side of the dry film is in contact with the substrate.

[0083] As the second film, for example, polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc., it is sufficient that the adhesive force between the resin layer and the second film is less than the adhesive force between the resin layer and the first film when the second film is peeled off.

[0084] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0085] [Cured product] The cured product of this disclosure is obtained by curing the curable resin composition described above or the resin layer of the dry film described above.

[0086] [Printed Wiring Boards] The printed wiring boards of this disclosure have a cured product obtained from the curable resin composition of this disclosure or a resin layer of a dry film. As a method for manufacturing the printed wiring boards of this disclosure, for example, the curable resin composition of this disclosure is adjusted to a viscosity suitable for the coating method using the above-mentioned organic solvent, and applied to a substrate by methods such as dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, inkjet, dispensing, or spray coating. Then, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer. In the case of dry films, the resin layer is bonded to the substrate using a laminator or the like so that the resin layer is in contact with the substrate, thereby forming a resin layer on the substrate.

[0087] Examples of the above-mentioned substrates include printed circuit boards and flexible printed circuit boards with circuits pre-formed using copper, etc., copper-clad laminates using materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / nonwoven fabric epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate films, glass substrates, ceramic substrates, wafers, etc.

[0088] When the film is in the form of a dry film, it is preferable to laminate it onto the substrate under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, even if the surface of the circuit board is uneven when a circuit-formed substrate is used, the dry film adheres closely to the circuit board, preventing the inclusion of air bubbles and improving the ability to fill in depressions on the substrate surface. The pressure is preferably around 0.1 to 2.0 MPa, and the heating is preferably around 40 to 120°C.

[0089] When the curable resin composition of this disclosure contains an organic solvent, it is preferable to apply the curable resin composition to the surface of the substrate and then perform volatilization drying. Volatilization drying can be performed using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like.

[0090] After forming a resin layer on a substrate, it is selectively exposed with active energy rays through a photomask with a predetermined pattern, and the unexposed areas are developed with a dilute alkaline aqueous solution (e.g., 0.3 to 3% by mass sodium carbonate aqueous solution) to form a pattern on the cured product. In the case of a dry film, after exposure, the first film is peeled off from the dry film and developed to form a patterned cured product on the substrate. In the case of a dry film, if the properties are not impaired, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed. Furthermore, by irradiating the cured product with active energy rays and then heat-curing it (e.g., 100 to 220°C), or irradiating it with active energy rays after heat-curing, or by performing final finishing curing (main curing) with heat-curing alone, a cured product with excellent properties such as adhesion and hardness can be formed.

[0091] The exposure machine used for the above-mentioned active energy ray irradiation can be any device equipped with a high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, mercury short-arc lamp, etc., that irradiates ultraviolet light in the range of 350 to 450 nm. Furthermore, a direct drawing device (for example, a laser direct imaging device that directly draws images with a laser using CAD data from a computer) can also be used. The lamp light source or laser light source of the direct drawing device can have a maximum wavelength in the range of 350 to 450 nm. The exposure amount for image formation varies depending on the film thickness, etc., but is generally 10 to 1000 mJ / cm ２ Preferably 20 to 800 mJ / cm² ２ It can be within the range of

[0092] The above-mentioned development method can be the dipping method, shower method, spray method, brush method, etc., and alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines can be used as the developing solution.

[0093] After forming a cured material on the substrate as described above, components such as electronic elements are mounted on the substrate by solder reflow. Solder reflow can be carried out by conventionally known methods. Solder reflow is generally performed under processing conditions such as 245 to 260°C for 5 to 10 seconds.

[0094] The curable resin composition or dry film of this disclosure is suitably used for manufacturing electronic components such as printed circuit boards, and more preferably for forming permanent coatings. In this case, a cured product is formed using the curable resin composition or dry film of this disclosure by the method described above. When the resin layer of the curable resin composition or dry film of this disclosure is insulating, it is suitably used to form a solder resist, coverlay, or interlayer insulating layer. It can be particularly suitably used for forming permanent coatings such as solder resist used on package substrates. The curable resin composition of this disclosure may also be used to form a solder dam.

[0095] According to the curable resin composition of this disclosure, by combining component (A), which includes two different components, component (A1) and component (A2), with component (C), various properties necessary for resin insulating layers such as solder resist (e.g., plating resistance, durability, and insulation) can be obtained. Furthermore, insulation reliability can be obtained while maintaining the formation characteristics of solder resist patterns by exposure (photocurability and resolution). In addition, according to the curable resin composition of this disclosure, by using an imidazole compound (B) as a curing catalyst, insulation reliability can be further enhanced while maintaining a broader range of process control.

[0096] 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 "%" all refer to mass unless otherwise specified.

[0097] (Synthesis of Carboxyl Group-Containing Resin 1) 650 parts by mass of diethylene glycol monoethyl ether acetate was charged with 1070 g of orthocresol novolac type epoxy resin (DIC Corporation, EPICLON N-695, softening point 95°C, epoxy equivalent 214, average number of functional groups 7.6), 360 g of acrylic acid, and 1.5 g of hydroquinone. The mixture was heated to 100°C and stirred until uniformly dissolved. Next, 4.3 parts by mass of triphenylphosphine was charged, and the mixture was heated to 110°C and reacted for 2 hours. Then, 1.6 parts by mass of triphenylphosphine was added, and the temperature was raised to 120°C and the reaction was carried out for a further 12 hours. 525 g of aromatic hydrocarbon (Standard Petroleum Osaka Sales Office, T-Sol 150) and 608 g (4.0 mol) of tetrahydrophthalic anhydride were charged into the resulting reaction solution and the mixture was reacted at 110°C for 4 hours. 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 containing carboxyl groups was obtained, with a solid content of 65% and an acid value of 77 mg KOH / g of the solid content.

[0098] (Synthesis of Carboxyl Group-Containing Resin 2) 650 parts by mass of diethylene glycol monoethyl ether acetate was charged with 1070 g of orthocresol novolac type epoxy resin (DIC Corporation, EPICLON N-695, softening point 95°C, epoxy equivalent 214, average number of functional groups 7.6), 360 g of acrylic acid, and 1.5 g of hydroquinone. The mixture was heated to 100°C and stirred until uniformly dissolved. Next, 4.3 parts by mass of triphenylphosphine was charged, and the mixture was heated to 110°C and reacted for 2 hours. Then, 1.6 parts by mass of triphenylphosphine was added, and the temperature was raised to 120°C and the reaction was carried out for a further 12 hours. 525 g of aromatic hydrocarbon (Standard Petroleum Osaka Sales Office, T-Sol 150) and 608 g (4.0 mol) of tetrahydrophthalic anhydride were charged into the resulting reaction solution and the mixture was reacted at 110°C for 4 hours. In this way, a resin solution containing carboxyl groups was obtained, with a solid content of 60% and an acid value of 77 mgKOH / g of the solid content.

[0099] <Preparation of Curable Resin Compositions> Each component was blended according to the formulations shown in Table 1 below, pre-mixed in a stirrer, dispersed in a three-roll mill, and kneaded to prepare the respective curable resin compositions. The amounts in the table are in parts by mass. The curable resin compositions of the obtained examples and comparative examples were evaluated as follows.

[0100] The components *1 to *13 in Table 1 below are as follows: *1: Carboxyl group-containing resin 1 synthesized above (65% solid content) *2: Carboxyl group-containing resin 2 synthesized above (65% solid content) *3: 2PHZ-PW (manufactured by Shikoku Chemicals, Inc., solid at room temperature (powder)) *4: 2E4MZ (manufactured by Shikoku Chemicals, Inc., liquid at room temperature) *5: N-770-75EA (manufactured by DIC Corporation, 75% solid content) *6: N-870-75EA (manufactured by DIC Corporation, 75% solid content) *7: YX-4000 (manufactured by Mitsubishi Chemical Corporation) *8: NC-3000H-CA75 (manufactured by Nippon Kayaku Co., Ltd., 75% solid content) *9: DPHA (manufactured by Nippon Kayaku Co., Ltd., dipentaerythritol pentaacrylate) *10: Omnirad 379 (manufactured by IGM Resins) *11: Omnirad 907 (manufactured by IGM Resins) *12: B-30 (manufactured by Sakai Chemical Industry Co., Ltd.) *13: Methoxypropanol (manufactured by Daicel Corporation)

[0101] <Crack Resistance (Evaluation of Insulation Reliability)> A comb-shaped electrode pattern with a line / space of 30 / 30 μm, measuring 150 mm in length, 95 mm in width, and 1.6 mm in thickness, was screen-printed with each curable resin composition from the examples and comparative examples to obtain a resin layer with a drying thickness of 20 μm. The resin layer was dried at a drying temperature of 80°C for 60 minutes. This resin layer was subjected to full-surface contact exposure with a metal halide lamp at an exposure dose of 200 mJ, and then developed with a 1 wt% sodium carbonate aqueous solution at 30°C under a spray pressure of 0.2 MPa for 60 seconds to prepare an evaluation substrate. Crack resistance was evaluated by applying a DC 5V bias voltage to the comb-shaped electrode under heated and humidified conditions of 85°C and 85% R.H., and checking the time until cracks occurred at the circuit ends of the substrate cross-section. The evaluation was performed according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: Time until cracks occur is 1000 hours or more. ×: The time until cracks appear is 0 to 1000 hours.

[0102] <HAST Resistance (Evaluation of Insulation Reliability)> A comb-type electrode pattern with dimensions of 150 mm (length), 95 mm (width), 1.6 mm (thickness), and a circuit thickness of 35 μm, with a line / space ratio of 130 / 130 μm, was screen-printed onto its chemically polished surface. Each curable resin composition from the examples and comparative examples was coated to a substrate film thickness of 35 μm after drying. The resin layer was dried at a drying temperature of 80°C for 60 minutes. This resin layer was subjected to full-surface contact exposure with a metal halide lamp at an exposure dose of 200 mJ, and then developed with a 1 wt% sodium carbonate aqueous solution at 30°C under a spray pressure of 0.2 MPa for 60 seconds to prepare an evaluation substrate. For the evaluation of insulation performance, the comb-type electrode was subjected to a DC 12V bias voltage under heated and humidified conditions of 130°C and 85% R.H., and the electrical resistance was 1.0 × 10⁻⁶. －６ The time until the short circuit was exceeded was checked and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: Short circuit time is 1000 hours or more from the start of the test ×: Short circuit time is less than 1000 hours from the start of the test

[0103] <Developability (Evaluation of process control range)> A single-sided printed circuit board with a 15 μm thick copper circuit was prepared, and pretreatment (surface treatment) was performed using CZ8100 manufactured by MEC Corporation. Each curable resin composition from the examples and comparative examples was formed on this board by screen printing, and dried in an 80°C drying oven for 60 minutes to obtain a tack-free resin layer. Next, this resin layer was developed with a 1 wt% sodium carbonate aqueous solution at 30°C under a spray pressure of 0.2 MPa for 60 seconds, and the developability was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation criteria) ○: No residue. ×: Residue present.

[0104] <Drying Control Range (Evaluation of Process Control Range)> An FR-4 substrate with a circuit pattern formed on it, measuring 150 mm in length, 95 mm in width, and 1.6 mm in thickness, was buffed and polished. Each curable resin composition from the examples and comparative examples was screen printed and coated to a film thickness of 20 μm after drying. The substrates were then dried at three different temperatures: 80°C for 60 minutes, 65 minutes, and 70 minutes, to produce evaluation substrates with resin layers. Next, these resin layers were developed with a 1 wt% sodium carbonate aqueous solution at 30°C under a spray pressure of 0.2 MPa for 60 seconds. The evaluation substrates after development were visually inspected to check for the presence or absence of resin layer (development residue), and the drying control range for each curable resin composition was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: No development residue was observed in any of the evaluation substrates with drying times of 60 minutes, 65 minutes, or 70 minutes. △: Of the evaluation substrates with drying times of 60 minutes, 65 minutes, and 70 minutes, one evaluation substrate had residual development.

[0105] <Storage Stability> The viscosity of each curable resin composition of the examples and comparative examples, prepared by blending and stirring the constituent components, was measured immediately after preparation and 24 hours after preparation, and storage stability was evaluated from the increase in viscosity. Specifically, the viscosity of the curable resin composition at 25°C immediately after preparation was measured using a cone-plate viscometer, and the remaining curable resin composition was placed in a black plastic bucket and stored at 25°C for 24 hours under light-shielding conditions. The viscosity of the curable resin composition after storage was measured and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ○: Viscosity increase of 20 Ps or less. △: Viscosity increase of 20 Ps or more.

[0106]

[0107] As is clear from Table 1, Examples 1 to 8 are curable resin compositions comprising (A) a carboxyl group-containing resin having an ethylenically unsaturated double bond in the molecule (hereinafter also simply referred to as "component (A)"), (B) an imidazole compound, and (C) a thermosetting resin, wherein component (A) comprises (A1) a resin whose terminals are modified by a GMA structure (hereinafter also simply referred to as "component (A1)") and (A2) a resin other than the above-mentioned component (A1) (hereinafter also simply referred to as "component (A2)"). Therefore, they exhibit excellent storage stability, developability, and drying control range, and it was confirmed that cured products with excellent crack resistance and HAST resistance can be obtained while ensuring a wide range of process control during pattern formation.

[0108] Comparative Example 1 had insufficient crack resistance and HAST resistance because the curable resin composition did not contain component (A1) as component (A). Comparative Example 2 had poor developability and could not secure a range of process control because the curable resin composition contained only component (A1) as component (A) and did not contain component (A2). Comparative Example 3 had insufficient crack resistance and a somewhat insufficient range of drying control (range of process control) because the curable resin composition did not contain component (B). Comparative Example 4 had insufficient HAST resistance and somewhat insufficient crack resistance because the curable resin composition had a low content of component (A1) as component (A). Comparative Example 5 had poor developability and could not secure a range of process control because the curable resin composition had a low content of component (A2) as component (A).

Claims

1. A curable resin composition comprising (A) a carboxyl group-containing resin having an ethylenically unsaturated double bond in its molecule, (B) an imidazole compound, and (C) a thermosetting resin, wherein the (A) carboxyl group-containing resin having an ethylenically unsaturated double bond in its molecule comprises (A1) a resin modified by a GMA structure at its terminus and (A2) a resin other than (A1), and the content of the resin modified by a GMA structure at its terminus in the (A) carboxyl group-containing resin is 70% by mass or more and 90% by mass or less on a solid content basis.

2. The curable resin composition according to claim 1, wherein the content of the (B) imidazole compound in the entire curable resin composition is 0.5% by mass or more and 1.5% by mass or less on a solid content basis.

3. The curable resin composition according to claim 1, wherein the (B) imidazole compound is solid or semi-solid at room temperature.

4. The curable resin composition according to claim 1, wherein the (C) thermosetting resin comprises an epoxy resin.

5. (D) The curable resin composition according to claim 1, further comprising a (meth)acrylate monomer.

6. (E) The curable resin composition according to claim 1, further comprising a photopolymerization initiator.

7. (F) The curable resin composition according to claim 1, further comprising a filler compound.

8. A curable resin composition according to any one of claims 1 to 7, having a viscosity of 1 to 5 Ps and used for spray coating.

9. A dry film having a resin layer obtained by applying and drying the curable resin composition described in claim 1 onto a first film.

10. A cured product obtained by curing the resin layer of the curable resin composition described in claim 1 or the dry film described in claim 9.

11. The cured product according to claim 10, used in solder resist.

12. A printed circuit board comprising the cured material described in claim 11 on a substrate.

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