Photocurable resin compositions, dry films, cured products, and printed circuit boards

Abstract

To provide a photocurable resin composition that yields a cured product with excellent resolution in thick films, even when incorporating inorganic fillers with a small average particle size, and with excellent long-term insulation reliability (BHAST resistance) and thermal cycling resistance (TCT resistance). [Solution] The photocurable resin composition of the present invention is a photocurable resin composition comprising (A) a carboxyl group-containing resin, (B) a thermosetting component, (C) an inorganic filler, and (D) a photopolymerization initiator, wherein the (C) inorganic filler comprises (C-1) a first inorganic filler and (C-2) a second inorganic filler. The average particle size of the first inorganic filler (C-1) is 30 nm or more and less than 300 nm, the average particle size of the second inorganic filler (C-2) is 300 nm or more and 800 nm or less, the content of the inorganic filler (C) is 90 parts by mass or more in terms of solid content per 100 parts by mass of the carboxyl group-containing resin (A) in terms of solid content, the content of the inorganic filler (C) is 30% by mass or more in terms of solid content relative to the total amount of the photocurable resin composition, and the total surface area, which is the sum of the specific surface areas of the inorganic filler (C) contained in 1 g of the photocurable resin composition in terms of solid content, is 23.0 m². 2 Over 60.0m 2 The following characteristics apply:

Description

[Technical Field]

[0001] The present invention relates to a photocurable resin composition, a dry film, a cured product, and a printed circuit board. [Background technology]

[0002] In recent years, with the miniaturization and increased functionality of electronic devices, there has been a growing need for finer patterns on printed circuit boards, reduced mounting area, and higher density component mounting. Therefore, high resolution is required for the photocurable resin compositions used to form solder resist on printed circuit boards. Furthermore, since high temperatures are applied at various stages during the manufacturing and use of printed circuit boards, the solder resist on the board also requires resistance to thermal stress. To improve this resistance to thermal stress, filling the photocurable resin composition with inorganic fillers to match the linear thermal expansion coefficients of the solder resist and the underlying wiring substrate as closely as possible has been widely investigated. Among inorganic fillers, silica, in particular, is widely used to improve solder resist properties such as crack resistance due to its excellent filling properties and low coefficient of thermal expansion (CTE).

[0003] Furthermore, with the increasing narrowing of wiring pitches, there is a strong demand for improved BHAST (Biased Highly Accelerated Temperature and Humidity Stress Test) resistance in cured products of photocurable resin compositions. However, conventional photocurable resin compositions still have room for improvement in BHAST resistance. In particular, the importance of insulation reliability between fine wiring is increasing, and resistance to BHAST tests, which have higher test temperatures and more stringent conditions such as 130°C and 85%RH compared to conventional tests, is required.

[0004] Patent Document 1 describes (A) a carboxyl group-containing resin, (B) Photopolymerization initiator, (C) Epoxy resin and A curable resin composition containing (D) silica, wherein the (D) silica does not contain silica having a particle size exceeding 300 nm, and a curable resin composition is disclosed, characterized in that the ratio of the epoxy groups of the (C) epoxy resin to the carboxyl groups of the (A) carboxyl group-containing resin is 1.9 to 2.9.

[0005] Further, Patent Document 2 discloses a photosensitive resin composition containing: (A) component: a novolak resin having a phenolic hydroxyl group, (B) component: a compound having two or more oxirane rings, [[ID=1l]] (C) component: a photo-sensitive acid generator containing at least one onium salt selected from the group consisting of onium borate salts and onium gallate salts, (D) component: a solvent, and the content of the (B) component is 40 to 300 parts by mass with respect to 100 parts by mass of the (A) component.

Prior Art Documents

Patent Documents

[0006] [[ID=Z7]]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, when forming a thick film resist pattern, if the inorganic filler increases in the photocurable resin composition, in pattern exposure by light irradiation on the coating film, the inorganic filler inhibits light transmission and reduces the curability of the photocurable resin composition in the deep part of the coating film. In subsequent development, there is a problem that the bottom of the coating film of the solder resist opening pattern is excessively dissolved (undercut), deteriorating the resolution.

[0008] On the other hand, as a means for suppressing undercut, there is a method of increasing the light transmittance by using an inorganic filler having a small average particle size. However, the inventors of the present invention have found a new problem that in the form of a solder resist having a large amount of an inorganic filler with a small average particle size, when using an inorganic filler with a small average particle size while maintaining the filling amount, the long-term insulation reliability decreases.

[0009] Therefore, an object of the present invention is to provide a photocurable resin composition that is excellent in resolution in a thick film even when an inorganic filler with a small average particle size is blended, and is excellent in the long-term insulation reliability (BHAST resistance) and thermal cycle (TCT resistance) of the cured product, a dry film comprising the composition, cured products thereof, and a printed wiring board having the cured product.

Means for Solving the Problems

[0010] As a result of intensive studies, the inventors of the present invention have found that a photocurable resin composition characterized in that the inorganic filler contains an inorganic filler having an average particle size within a specific numerical range, the content of the inorganic filler is within a specific numerical range, and the total surface area which is the sum of the specific surface areas of the inorganic filler is within a specific numerical range can solve the above problems, and have completed the present invention. That is, the present invention is as follows.

[0011] [1] A photocurable resin composition containing (A) a carboxyl group-containing resin, (B) a thermosetting component, (C) an inorganic filler, and (D) a photopolymerization initiator, wherein the (C) inorganic filler includes (C-1) a first inorganic filler and (C-2) a second inorganic filler, the average particle size of the (C-1) first inorganic filler is 30 nm or more and less than 300 nm, the average particle size of the (C-2) second inorganic filler is 300 nm or more and 800 nm or less, the content of the (C) inorganic filler is 90 parts by mass or more in terms of solid content with respect to 100 parts by mass of the (A) carboxyl group-containing resin in terms of solid content, The amount of the inorganic filler (C) is 30% by mass or more in terms of solid content relative to the total amount of the photocurable resin composition. The total surface area, which is the sum of the specific surface areas of the inorganic filler (C) contained in 1 g of the aforementioned photocurable resin composition on a solids basis, is 23.0 m². 2 Over 60.0m 2 A photocurable resin composition characterized by the following: [2] The photocurable resin composition according to [1], wherein the content of the first inorganic filler (C-1) is 20% by mass or more and 40% by mass or less in terms of solid content relative to the total amount of the photocurable resin composition. [3] The photocurable resin composition according to [1] or [2], wherein the content of the first inorganic filler (C-1) is 50% by mass or more and 80% by mass or less in terms of solid content relative to the total amount of the inorganic filler (C). [4] The photocurable resin composition according to any one of [1] to [3], wherein the content of the (C-2) second inorganic filler is 8% by mass or more and 25% by mass or less on a solid content basis with respect to the total amount of the photocurable resin composition. [5] The photocurable resin composition according to any one of [1] to [4], wherein the content of the (C-2) second inorganic filler is 20% by mass or more and 50% by mass or less in terms of solid content relative to the total amount of the (C) inorganic filler. [6] The photocurable resin composition according to any one of [1] to [5], wherein the (C) inorganic filler comprises an inorganic filler that has been surface-treated. [7] The photocurable resin composition according to any one of [1] to [6], wherein the content of the carboxyl group-containing resin (A) is 10% by mass or more and 50% by mass or less on a solid content basis with respect to the total amount of the photocurable resin composition. [8] The photocurable resin composition according to any one of [1] to [7], wherein the content of the thermosetting component (B) is 5% by mass or more and 20% by mass or less on a solid content basis with respect to the total amount of the photocurable resin composition. [9] A photocurable resin composition according to any one of [1] to [8], further comprising a curing agent.

[10] A dry film characterized by having a resin layer obtained from a photocurable resin composition described in any of [1] to [9].

[11] A cured product characterized by being obtained by curing a photocurable resin composition described in any of [1] to [9].

[12] A cured product characterized by being obtained by curing the resin layer of the dry film described in

[10] .

[13] A printed circuit board characterized by having the cured product described in

[11] .

[14] A printed circuit board characterized by having the cured product described in

[12] . [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an alkali-developable photocurable resin composition that achieves good resolution, crack resistance, and long-term insulation reliability (BHAST resistance) in thick films, a dry film having a resin layer obtained from the composition, a cured product of the resin layer of the composition or the dry film, and a printed circuit board having the cured product. [Modes for carrying out the invention]

[0013] [Photocurable resin composition] The photocurable resin composition of the present invention comprises (A) a carboxyl group-containing resin, (B) a thermosetting component, (C) an inorganic filler, and (D) a photopolymerization initiator. Furthermore, the photocurable resin composition of the present invention may contain a curing agent and other components. The following describes each component of the photocurable resin composition of the present invention.

[0014] ((A) Carboxyl group-containing resin) The photocurable resin composition of the present invention includes a carboxyl group-containing resin. As the carboxyl group-containing resin, various conventionally known resins having carboxyl groups in their molecules can be used. By including a carboxyl group-containing resin in the photocurable resin composition, alkali developability can be imparted to the photocurable resin composition. In particular, carboxyl group-containing photosensitive resins having an ethylenically unsaturated double bond in their molecules are preferred in terms of photocurability and developability. The ethylenically unsaturated double bond is preferably derived from acrylic acid, methacrylic acid, or their derivatives. When using only carboxyl group-containing resins that do not have an ethylenically unsaturated double bond, it is necessary to use a compound having multiple ethylenically unsaturated groups in its molecule, i.e., a photopolymerizable monomer, as described later, in order to make the composition photocurable. Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers):

[0015] (1) A carboxyl group-containing resin obtained by copolymerization of an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

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

[0017] (3) Diisocyanates and bifunctional epoxy resins 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, and biphenol type epoxy resin, and monocarboxylic acid compounds having ethylenically unsaturated double bonds such as (meth)acrylic acid, partially acid anhydride modified products, carboxyl group-containing dialcohol compounds and diol compounds obtained by polyaddition reactions.

[0018] (4) 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, during the synthesis of the resin of (2) or (3) above, and then (meth)acrylicating the terminal (meth)acrylic.

[0019] (5) A carboxyl group-containing photosensitive urethane resin in which a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule is added to the resin of (2) or (3) above during synthesis and (meth)acrylicated at the terminal.

[0020] (6) 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.

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

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

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

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

[0025] (11) A carboxyl group-containing photosensitive resin obtained by reacting a reaction product 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 with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0026] (12) A carboxyl group-containing photosensitive resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins of (1) to (11) above. In this specification, (meth)acrylate is a general term referring to acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions.

[0027] The acid value of the carboxyl group-containing resin is preferably in the range of 30 to 150 mg KOH / g, and more preferably in the range of 50 to 120 mg KOH / g. If the acid value of the carboxyl group-containing resin is less than 30 mg KOH / g, alkaline development becomes difficult. On the other hand, if it exceeds 150 mg KOH / g, the dissolution of the exposed areas by the developer progresses, causing the exposed and unexposed areas to dissolve and peel off indiscriminately, making it difficult to draw a normal resist pattern, which is undesirable.

[0028] The content of carboxyl group-containing resin is preferably 10% by mass or more and 50% by mass or less, relative to the total solid content of the photocurable resin composition. A content of 10% by mass or more improves the strength of the coating film. A content of 50% by mass or less results in appropriate viscosity and improved processability.

[0029] These carboxyl group-containing resins are not limited to those listed above and may be used individually or in mixtures of multiple types. Among them, carboxyl group-containing resins synthesized using compounds having phenolic hydroxyl groups, such as the carboxyl group-containing resins (10) and (11), as starting materials are preferable because they have excellent HAST resistance and PCT resistance.

[0030] ((B) Thermosetting component) The photocurable resin composition of the present invention contains a thermosetting component. Various conventionally known compounds and resins with thermosetting properties can be used as the thermosetting component. The inclusion of a thermosetting component in the photocurable resin composition is expected to improve its heat resistance. Examples of thermosetting components used in the present invention include isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy resins, oxetane compounds, and episulfide resins. The thermosetting component may be used alone or in combination of two or more. Among these, epoxy resins are preferred thermosetting components.

[0031] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol S type epoxy resin, novolac type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, glycidylamine type epoxy resin, alicyclic epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin, tetraphenyloleethane type epoxy resin, heterocyclic epoxy resin, diglycidyl phthalate resin, tetraglycidyl xylenoylethane resin, glycidyl methacrylate copolymer epoxy resin, cyclohexylmaleimide and glycidyl methacrylate copolymer epoxy resin, and CTBN-modified epoxy resin. These can be used individually or in combination of two or more types depending on the required properties.

[0032] Examples of commercially available epoxy resins include jER(registered trademark) 828, 806, 807, YX8000, YX8034, 834, and YX4000 from Mitsubishi Chemical Corporation; YD-128, YDF-170, ZX-1059, and ST-3000 from Nippon Steel Chemical & Material Corporation; EPICLON(registered trademark) 830, 835, 840, 850, N-730A, N-695, N-860, and N-870 from DIC Corporation; and RE-306 from Nippon Kayaku Co., Ltd. These epoxy compounds may be used individually or in combination of two or more.

[0033] 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, (3-ethyl-3-oxetanyl)methyl Examples include polyfunctional oxetanes such as acrylates, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and their oligomers or copolymers, as well as ethers of oxetane alcohols with resins having hydroxyl groups such as novolac resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring with alkyl (meth)acrylates.

[0034] The content of the thermosetting component is preferably 5% by mass or more and 20% by mass or less, relative to the total solid content of the photocurable resin composition. When the content of the thermosetting component is within the above numerical range, a cured product with superior developability and superior flexibility, adhesion, and heat resistance can be obtained.

[0035] ((C) Inorganic filler) The photocurable resin composition of the present invention comprises (C) an inorganic filler. The inorganic filler used in the present invention (C) comprises (C-1) a first inorganic filler and (C-2) a second inorganic filler. The average particle size of the first inorganic filler (C-1) is 30 nm or more and less than 300 nm. The average particle size of the second inorganic filler (C-2) is between 300 nm and 800 nm. The content of the inorganic filler (C) is 90 parts by mass or more in terms of solid content, relative to 100 parts by mass of the carboxyl group-containing resin (A) in terms of solid content. The amount of the inorganic filler (C) is 30% by mass or more in terms of solid content relative to the total amount of the photocurable resin composition. The total surface area, which is the sum of the specific surface areas of the inorganic filler (C) contained in 1 g of the aforementioned photocurable resin composition on a solids basis, is 23.0 m². 2 Over 60.0m 2 The following characteristics apply: (C) When the average particle size, content, and total surface area of ​​the inorganic filler are within the above numerical range, the thick film resolution of the photocurable resin composition of the present invention, as well as the insulation reliability and crack resistance of the cured product of the present invention, are favorable.

[0036] ((C-1) First inorganic filler) (C-1) The average particle size of the first inorganic filler is 30 nm or more and less than 300 nm, preferably 35 nm or more and 250 nm or less, and more preferably 40 nm or more and 200 nm or less. The photocurable resin composition of the present invention may contain only one type of (C-1) first inorganic filler, or it may contain two or more types of (C-1) first inorganic fillers with different average particle sizes.

[0037] ((C-2) Second inorganic filler) (C-2) The average particle size of the second inorganic filler is 300 nm or more and 800 nm or less, preferably 350 nm or more and 750 nm or less, more preferably 350 nm or more and 700 nm or less, and even more preferably 400 nm or more and 700 nm or less. The photocurable resin composition of the present invention may contain only one type of (C-2) second inorganic filler, or it may contain two or more types of (C-2) second inorganic fillers with different average particle sizes.

[0038] [Average particle size of inorganic fillers] In this specification, the average particle diameter of the inorganic filler refers to the average particle diameter (D50) including not only the particle diameter of the primary particles but also the particle diameter of the secondary particles (aggregates), and is the value of D50 measured by the laser diffraction method. Examples of the measuring apparatus using the laser diffraction method include Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd. Also, the average particle diameter of the inorganic filler contained in the photocurable resin composition in the present invention refers to the value measured as described above for the inorganic filler before adjusting (preliminary stirring, kneading) the photocurable resin composition.

[0039] [Content of inorganic filler] (C) The content of the inorganic filler is 90 parts by mass or more, preferably 120 parts by mass or more, and more preferably 150 parts by mass or more in terms of solid content, based on 100 parts by mass of the carboxyl group-containing resin in terms of solid content. Also, as the upper limit, it is preferably 350 parts by mass or less, more preferably 300 parts by mass or less, and even more preferably 250 parts by mass or less. (C) The content of the inorganic filler is 30% by mass or more in terms of solid content per total amount of the photocurable resin composition, preferably 30% by mass or more and 65% by mass or less, more preferably 30% by mass or more and 60% by mass or less, even more preferably 35% by mass or more and 55% by mass or less, and even more preferably 40% by mass or more and 50% by mass or less. (C) By the content of the inorganic filler being within the above numerical range, the cured product can be made to have high strength and high rigidity, and the coefficient of linear expansion (CTE) can be lowered.

[0040] [Total surface area of inorganic filler] The total surface area (hereinafter, also referred to as the “total surface area of (C) inorganic filler”), which is the sum of the specific surface areas of the (C) inorganic filler contained in 1 g of the photocurable resin composition in terms of solid content, is 23.0 m 2 or more and 60.0 m 2 or less, preferably 25.0 m <00000 {07}>or more and 57.5 m 2 or less, more preferably 26.0 m 2 or more and 55.0 m 2The following applies: By ensuring that the total surface area of ​​the inorganic filler (C) of the present invention falls within the above numerical range, crack resistance and other properties can be enhanced.

[0041] The total surface area of ​​the inorganic filler (C) in this application is calculated by the following formula. (C) Total surface area of ​​inorganic filler =Σ(G) Mass of (C) inorganic filler in 1g (solid content basis) of the photocurable resin composition of the present invention × (C) Specific surface area of ​​inorganic filler (m²) 2 / g) The method for determining the specific surface area of ​​the above inorganic filler will be explained later in the section on [Specific Surface Area of ​​Inorganic Filler].

[0042] If (C) inorganic filler contains two or more types of inorganic fillers, the specific surface area of ​​each inorganic filler is measured separately. If two or more types of inorganic fillers are included, the total surface area of ​​(C) inorganic filler is calculated by summing the values ​​obtained by multiplying the mass of each inorganic filler contained in 1 g (on a solid content basis) of the photocurable resin composition of the present invention by the specific surface area of ​​each inorganic filler.

[0043] Methods for adjusting the total surface area of ​​the inorganic filler (C) of the present invention to the above numerical range include using a mixture of an inorganic filler with a small specific surface area and an inorganic filler with a large specific surface area.

[0044] (C-1) The content of the first inorganic filler can be 10% by mass or more and 50% by mass or less in terms of solid content relative to the total amount of the photocurable resin composition, but is preferably 20% by mass or more and 40% by mass or less, more preferably 25% by mass or more and 40% by mass or less, and even more preferably 30% by mass or more and 40% by mass or less. Furthermore, the content of (C-1) the first inorganic filler can be 30% by mass or more and 85% by mass or less in terms of solid content relative to the total amount of (C) inorganic filler, but is preferably 50% by mass or more and 80% by mass or less, more preferably 55% by mass or more and 80% by mass or less, and even more preferably 60% by mass or more and 75% by mass or less. (C-1) When the content of the first inorganic filler is within the above numerical range, the thick film resolution of the photocurable resin composition of the present invention, as well as the insulation reliability and crack resistance of the cured product of the present invention, are favorable.

[0045] (C-2) The content of the second inorganic filler can be 5% by mass or more and 30% by mass or less in terms of solid content relative to the total amount of the photocurable resin composition, but is preferably 8% by mass or more and 25% by mass or less, more preferably 8% by mass or more and 20% by mass or less, and even more preferably 10% by mass or more and 15% by mass or less. Furthermore, the content of (C-2) the second inorganic filler can be 15% by mass or more and 70% by mass or less in terms of solid content relative to the total amount of the inorganic filler (C), but is preferably 20% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 45% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less. (C-2) When the content of the second inorganic filler is within the above numerical range, the thick film resolution of the photocurable resin composition of the present invention, as well as the insulation reliability and crack resistance of the cured product of the present invention, are favorable.

[0046] [Specific surface area of ​​inorganic fillers] (C-1) The specific surface area of ​​the first inorganic filler is preferably 10 m². 2 / g or more 500m 2 / g or less, more preferably 20m 2 / g or more 400m 2 / g or less, and more preferably 30m 2 / g or more 300m 2 It is less than / g. More preferably 30m 2 / g or more 250m 2 It is less than or equal to / g, and particularly preferably 30m 2 / g or more 200m 2 It is less than / g. (C-2) The specific surface area of ​​the second inorganic filler is preferably 1 m². 2 / g or more 10m 2 Less than / g, more preferably 2m 2 / g or more 8m 2 It is less than / g, and more preferably 4m2 / g or more 7m 2 It is less than / g. When the specific surface areas of (C-1) the first inorganic filler and (C-2) the second inorganic filler are within the above numerical range, the thick film resolution of the photocurable resin composition of the present invention, as well as the insulation reliability and crack resistance of the cured product of the present invention, are favorable.

[0047] In this specification, the specific surface area of ​​an inorganic filler refers to the value of the specific surface area measured by the BET specific surface area measurement method in accordance with JIS Z 8830:2013. An example of a specific surface area measuring device is the Macsorb210 (product name) manufactured by Mountec Co., Ltd. Furthermore, the specific surface area of ​​the inorganic filler contained in the photocurable resin composition in the present invention refers to the value measured as described above for the inorganic filler before preparing the photocurable resin composition (pre-stirring, kneading).

[0048] [Types of inorganic fillers] The inorganic filler is not particularly limited as long as it satisfies the above particle size and specific surface area requirements. Known and conventional fillers can be used, such as amorphous silica, crystalline silica, fused silica, spherical silica, Neuburg siliceous earth, aluminum hydroxide, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, aluminum oxide, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, zinc oxide, and other inorganic fillers. Among these, silica is preferred, and spherical silica is more preferred because its small surface area and even distribution of stress make it less likely to become a crack initiation point.

[0049] [Surface treatment of inorganic fillers] Whether or not the inorganic filler is surface-treated is not particularly limited, but the inorganic filler may be surface-treated to improve its dispersibility. There are no particular restrictions on the inorganic filler that is surface-treated; (C-1) the first inorganic filler may be surface-treated, or (C-2) the second inorganic filler may be surface-treated. Alternatively, both (C-1) the first inorganic filler and (C-2) the second inorganic filler may be surface-treated, or another inorganic filler different from both (C-1) the first inorganic filler and (C-2) the second inorganic filler may be surface-treated. Aggregation can be suppressed by using inorganic fillers that have undergone surface treatment.

[0050] When surface-treating an inorganic filler, the method is not particularly limited, and any known and conventional 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. As a coupling agent, 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. These silane-based coupling agents are preferably pre-immobilized on the surface of spherical silica 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. In this invention, reactive functional groups derived from coupling agents applied to inorganic fillers are not included in compounds having photocurable reactive groups or thermosetting functional groups.

[0051] Examples of photocurable reactive groups include ethylenically unsaturated groups such as vinyl groups, styryl groups, methacrylic groups, and acrylic groups. Among these, vinyl groups and at least one of (meth)acrylic groups are preferred. Examples of thermosetting reactive groups include hydroxyl groups, carboxyl groups, isocyanate groups, amino groups, imino groups, epoxy groups, oxetanyl groups, mercapto groups, methoxymethyl groups, methoxyethyl groups, ethoxymethyl groups, ethoxyethyl groups, and oxazoline groups. Among these, at least one of amino groups and epoxy groups is preferred.

[0052] ((D) Photopolymerization initiator) Photopolymerization initiators are used to react photosensitive carboxyl group-containing resins or photopolymerizable monomers upon exposure. Any known photopolymerization initiator can be used. A single photopolymerization initiator may be used, or two or more may be used in combination.

[0053] Examples of photopolymerization initiators 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-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 cy-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, Michlar'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-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, 2- Anthraquinones such as minoanthraquinone; 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)phenyl]-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyloxime)] Examples include oxime esters such as s(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, and other titanosenes; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc.

[0054] Commercially available α-aminoacetophenone-based photopolymerization initiators include Omnirad 907, 369, 369E, and 379 from IGM Resins. Commercially available acylphosphine oxide-based photopolymerization initiators include Omnirad 819 from IGM Resins. Commercially available oxime ester-based photopolymerization initiators include Irgacure OXE01 and OXE02 from BASF Japan Ltd., N-1919 from ADEKA Corporation, ADEKA Arclus NCI-831 and NCI-831E, and TR-PBG-304 from Changzhou Strong Electronic New Materials Co., Ltd.

[0055] Other examples include carbazole oxime ester compounds described in Japanese Patent Publication No. 2004-359639, Japanese Patent Publication No. 2005-097141, Japanese Patent Publication No. 2005-220097, Japanese Patent Publication No. 2006-160634, Japanese Patent Publication No. 2008-094770, Japanese Patent Publication No. 2008-509967, Japanese Patent Publication No. 2009-040762, and Japanese Patent Publication No. 2011-80036.

[0056] The content of the photopolymerization initiator is preferably 0.1 to 10% by mass, and more preferably 1 to 7% by mass, relative to the total solid content of the photocurable resin composition. When the content of the photopolymerization initiator is 0.1% by mass or more, the photocurability of the photocurable resin composition is good, and the properties of the cured product, such as chemical resistance, are also good. On the other hand, when the content is 10% by mass or less, light absorption at the surface of the resist film (cured product) is good, and the deep curing properties do not tend to decrease.

[0057] In combination with the above-mentioned photopolymerization initiator, a photoinitiator, sensitizer, or catalyst may be used. Examples of photoinitiators, sensitizers, or catalysts 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. These compounds can sometimes be used as photopolymerization initiators, but it is preferable to use them in combination with a photopolymerization initiator. Furthermore, one type of photoinitiator, sensitizer, or catalyst may be used alone, or two or more types may be used in combination.

[0058] These photopolymerization initiators, photoinitiation aids, sensitizers, and catalysts absorb specific wavelengths, which can sometimes lead to reduced sensitivity and cause them to function as UV absorbers. However, they are not used solely for the purpose of improving the sensitivity of photocurable resin compositions. By absorbing light of specific wavelengths as needed, the photoreactivity of the surface can be increased, changing the line shape and aperture of the resist pattern to vertical, tapered, or reverse tapered shapes, while also improving the accuracy of line width and aperture diameter.

[0059] (Photopolymerizable monomer) The photocurable resin composition of the present invention may contain a photopolymerizable monomer. In the present invention, a photopolymerizable monomer is a photopolymerizable monomer having one or more ethylenically unsaturated double bonds in one molecule. By including a photopolymerizable monomer, the crosslinking density during photopolymerization of the photocurable resin composition is increased, and the heat resistance of the photocurable resin composition and the chemical resistance of the cured product can be improved. Examples of such photopolymerizable monomers include conventionally known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, 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; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, trishydroxyethyl isocyanurate, etc. Polyhydric acrylates derived from polyhydric alcohols or their alkylene oxide adducts or ε-caprolactone adducts; polyhydric acrylates derived from phenols such as phenoxyacrylate and bisphenol A diacrylate or their alkylene oxide adducts; acrylates derived from glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, 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 acrylates, can be appropriately selected and used. Such photopolymerizable monomers can also be used as reactive diluents. Photopolymerizable monomers can be used individually or in combination of two or more.

[0060] The content of photopolymerizable monomers, if present, is preferably 10% by mass or less relative to the total solid content of the photocurable resin composition. When the content of photopolymerizable monomers is within the above numerical range, the developability and resolution of the photocurable resin composition tend to improve more easily.

[0061] (Hardening agent) Examples of curing agents 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 sebacate dihydrazide; and phosphorus compounds such as triphenylphosphine. Furthermore, commercially available examples include 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all trade names for imidazole compounds) manufactured by Shikoku Chemicals, Inc., and U-CAT 3513N (trade name for a dimethylamine compound), DBU, DBN, and U-CAT SA 102 (all bicyclic amidine compounds and their salts) manufactured by Sunapro Co., Ltd. In particular, it is not limited to these, and any curing agent for epoxy resins or oxetane compounds, or an agent that promotes the reaction between at least one of an epoxy group and an oxetanyl group and a carboxyl group is acceptable, and it may be used alone or in combination of two or more.

[0062] Furthermore, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine isocyanuric acid adduct can also be used, and preferably these compounds that also function as adhesion imparters are used in combination with the curing agent. The curing agent may be used alone or in combination of two or more types.

[0063] The curing agent content is preferably 0.1 to 8% by mass, and more preferably 0.3 to 7% by mass, relative to the total solid content of the photocurable resin composition.

[0064] (Coloring agent) The photocurable resin composition of the present invention may contain a coloring agent. The coloring agent is not particularly limited, and known coloring agents such as red, blue, green, and yellow can be used. It may be a pigment, dye, or colorant, but from the viewpoint of reducing environmental impact and minimizing effects on the human body, a halogen-free coloring agent is preferred.

[0065] Red colorants include monoazo, disazo, azolake, benzimidazolon, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone, and specifically those that are assigned a color index (CI; issued by The Society of Dyers and Colorists) number, as follows:

[0066] Examples of monoazo-based red colorants include Pigment Red 1, 2, 3, 4, 5, 6, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 112, 114, 146, 147, 151, 170, 184, 187, 188, 193, 210, 245, 253, 258, 266, 267, 268, and 269. Examples of disazo-based red colorants include Pigment Red 37, 38, and 41. Examples of monoazolake-based red colorants include Pigment Red 48:1, 48:2, 48:3, 48:4, 49:1, 49:2, 50:1, 52:1, 52:2, 53:1, 53:2, 57:1, 58:4, 63:1, 63:2, 64:1, and 68. Examples of benzimidazolone-based red colorants include Pigment Red 171, 175, 176, 185, and 208. Examples of perylene-based red colorants include Solvent Red 135, 179, Pigment Red 123, 149, 166, 178, 179, 190, 194, and 224. Examples of diketopyrrolopyrrole-based red colorants include Pigment Red 254, 255, 264, 270, and 272. Examples of condensed azo-based red colorants include Pigment Red 220, 144, 166, 214, 220, 221, and 242. Examples of anthraquinone-based red colorants include Pigment Red 168, 177, 216, Solvent Red 52, 149, 150, and 207. Examples of quinacridone-based red colorants include Pigment Red 122, 202, 206, 207, and 209.

[0067] Blue colorants include phthalocyanine and anthraquinone compounds, while pigments include compounds classified as pigments, such as Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, and 60. Dyes such as Solvent Blue 35, 63, 67, 68, 70, 83, 87, 94, 97, 122, and 136 can be used. In addition to the above, metal-substituted or unsubstituted phthalocyanine compounds can also be used.

[0068] Examples of yellow colorants include monoazo, disazo, condensed azo, benzimidazolon, isoindolinone, and anthraquinone. For example, anthraquinone yellow colorants include Solvent Yellow 163, Pigment Yellow 24, 108, 193, 147, 199, and 202. Isoindolinone yellow colorants include Pigment Yellow 110, 109, 139, 179, and 185. Condensed azo yellow colorants include Pigment Yellow 93, 94, 95, 128, 155, 166, and 180. Benzimidazolon yellow colorants include Pigment Yellow 120, 151, 154, 156, 175, and 181. Examples of monoazo-based yellow colorants include Pigment Yellow 1, 2, 3, 4, 5, 6, 9, 10, 12, 61, 62, 62:1, 65, 73, 74, 75, 97, 100, 104, 105, 111, 116, 167, 168, 169, 182, 183, etc. Examples of disazo-based yellow colorants include Pigment Yellow 12, 13, 14, 16, 17, 55, 63, 81, 83, 87, 126, 127, 152, 170, 172, 174, 176, 188, 198, etc.

[0069] Other colorants such as purple, orange, brown, black, and white may be added. Specifically, examples include Pigment Black 1, 6, 7, 8, 9, 10, 11, 12, 13, 18, 20, 25, 26, 28, 29, 30, 31, 32, Pigment Violet 19, 23, 29, 32, 36, 38, 42, Solvent Violet 13, 36, CIPigment Orange 1, 5, 13, 14, 16, 17, 24, 34, 36, 38, 40, 43, 46, 49, 51, 61, 63, 64, 71, 73, Pigment Brown 23, 25, carbon black, titanium dioxide, etc.

[0070] The amount of colorant added to the photocurable resin composition is not particularly limited, but it can be 0.1% by mass or more and 2.0% by mass or less, preferably 0.2% by mass or more and 1.5% by mass or less, relative to the total solid content of the photocurable resin composition.

[0071] [Organic solvents] The photocurable resin composition of the present invention may contain organic solvents for purposes such as preparing the composition or adjusting its viscosity when applying it to a substrate or film. As organic solvents, known and commonly used organic solvents can be used, such as ketones like methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons like toluene, xylene, and tetramethylbenzene; glycol ethers like 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 like 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 like octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used individually or in combination of two or more.

[0072] The content of the organic solvent is not particularly limited and can be appropriately set according to the desired viscosity to facilitate the preparation of the photocurable resin composition.

[0073] [Other additives] The photocurable resin composition of the present invention may optionally further contain components such as ion scavengers, cyanate compounds, mercapto compounds, urethane catalysts, thixonating agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper damage inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, defoaming agents and 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 be those known in the field of electronic materials.

[0074] [Method for producing a photocurable resin composition] The photocurable resin composition of the present invention can be prepared by weighing and blending each component, followed by pre-mixing with a stirrer. Subsequently, the components are dispersed in a kneader and kneaded.

[0075] Examples of the above-mentioned kneaders include bead mills, ball mills, sand mills, three-roll mills, and two-roll mills. Among these, a bead mill is preferable for improving dispersibility. The dispersion conditions, such as the type and particle size of the beads in the bead mill, can be appropriately set according to the desired viscosity.

[0076] [Application] The photocurable resin composition of the present invention is useful for forming pattern layers as permanent coatings on printed circuit boards, and is also useful for forming solder resists, coverlays, interlayer insulating layers, redistribution layers, and the like. Furthermore, since the photocurable resin composition of the present invention can form cured products with excellent film strength even in thin films, it can be suitably used for forming pattern layers in printed circuit boards where thinness is required, such as package substrates (printed circuit boards used in semiconductor packages). Furthermore, the photocurable resin composition of the present invention can be used not only for applications that form a patterned layer, but also for applications that do not form a patterned layer, such as molding applications (sealing applications).

[0077] [Dry film] The photocurable resin composition of the present invention can also be in the form of a dry film comprising a first film and a resin layer consisting of a dried coating of the photocurable resin composition formed on the first film. In the present invention, the first film refers to a film that is at least adhered to the resin layer when laminated onto a substrate so 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 the present invention, it is preferable to peel it off from the resin layer in a process after exposure. When forming a dry film, the photocurable resin composition of the present invention is diluted with the above organic solvent to adjust to an appropriate viscosity, and applied to 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, etc., and the film is usually dried at a temperature of 50 to 130°C for 1 to 30 minutes to obtain the film. There are no particular restrictions on the coating 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.

[0078] 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.

[0079] Furthermore, from the viewpoint of improving mechanical strength, the thermoplastic resin film described above is preferably a film stretched in one or two axes.

[0080] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0081] After forming a resin layer consisting of a dried coating of the photocurable resin composition of the present invention 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 present invention, the second film refers to a film that is peeled off from the resin layer before lamination when laminating the dry film onto the substrate so that the resin layer side of the dry film is in contact with it. 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.

[0082] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0083] [Cured product] The cured product of the present invention is obtained by curing the photocurable resin composition of the present invention described above, or the resin layer of the dry film of the present invention described above. Manufacturing conditions such as curing conditions will be described later in [Method for Manufacturing Printed Wiring Boards]. The cured product of the present invention can be suitably used in printed wiring boards, electronic components, and the like.

[0084] [Printed wiring board] The printed circuit board of the present invention comprises a circuit board and a cured product obtained from a resin layer of the photocurable resin composition or dry film of the present invention.

[0085] 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 (PEN) films, glass substrates, ceramic substrates, wafers, etc.

[0086] [Manufacturing method for printed circuit boards] As a method for manufacturing printed circuit boards according to the present invention, for example, the photocurable resin composition of the present invention is adjusted to a viscosity suitable for the coating method using the above-mentioned organic solvent, and then coated onto a substrate by methods such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating. After that, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C for 15 to 90 minutes to form a tack-free resin layer. There are no particular restrictions on the coating 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. In the case of a dry film, 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] The dry film is preferably laminated onto the substrate under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, even if the circuit-formed substrate has irregularities on its surface, 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.

[0088] The volatilization drying process performed after applying the photocurable resin composition of the present invention to a substrate can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like. An example of such equipment is the DF610 manufactured by Yamato Scientific Co., Ltd., which can be used as a hot air circulation drying oven.

[0089] After forming a resin layer on the 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 (for example, a 0.3-3.0% by mass sodium carbonate aqueous solution) to form the pattern of 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. However, within the limits that do not impair the properties, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed.

[0090] 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 writing 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 writing 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 / cm². 2 Preferably 20-800 mJ / cm² 2 It can be within the range of

[0091] 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.

[0092] Furthermore, the cured material may be irradiated with active energy rays and then heat-cured (for example, at a temperature of 100-220°C for 30-90 minutes), or irradiated with active energy rays after heat curing (for example, 1000-2000 mJ / cm²). 2 Alternatively, by performing final finishing curing (main curing) solely through heat curing, a cured product with excellent properties such as adhesion and hardness is formed. Examples of equipment include the QRM-2082 manufactured by Oak Manufacturing Co., Ltd., which is a UV conveyor using a high-pressure mercury lamp. [Examples]

[0093] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" all refer to mass on a solid content basis unless otherwise specified.

[0094] [Preparation of photocurable resin compositions] The preparation procedures for each photocurable resin composition (Compositions of Examples 1-14 and Comparative Examples 1-3) are described below.

[0095] [Synthesis example (carboxyl group-containing resin)] In a flask equipped with a condenser and stirrer, 456 parts bisphenol A, 228 parts water, and 649 parts 37% formalin were charged. The temperature was maintained below 40°C, and 228 parts of 25% sodium hydroxide aqueous solution were added. After the addition was complete, the mixture was reacted at 50°C for 10 hours. After the reaction was complete, the mixture was cooled to 40°C and neutralized to pH 4 with 37.5% phosphoric acid aqueous solution while maintaining the temperature below 40°C. The mixture was then allowed to stand, and the aqueous layer was separated. After separation, 300 parts methyl isobutyl ketone was added and dissolved uniformly. The mixture was then washed three times with 500 parts distilled water, and water, solvent, etc., were removed under reduced pressure at a temperature below 50°C. The obtained polymethylol compound was dissolved in 550 parts methanol to obtain 1230 parts methanol solution of the polymethylol compound. A portion of the obtained methanol solution of the polymethylol compound was dried in a vacuum dryer at room temperature, and the solid content was 55.2%. 500 parts methanol solution of the obtained polymethylol compound and 440 parts 2,6-xylenol were charged and uniformly dissolved at 50°C. After uniform dissolution, methanol was removed under reduced pressure at a temperature below 50°C. Then 8 parts oxalic acid was added and the mixture was reacted at 100°C for 10 hours. After the reaction was complete, the distillate was removed under reduced pressure at 180°C and 50 mmHg to obtain 550 parts novolac resin A. Furthermore, 130 parts of the above novolac resin A, 2.6 parts 50% sodium hydroxide aqueous solution, and 100 parts toluene / methyl isobutyl ketone (mass ratio = 2 / 1) were charged into an autoclave equipped with a thermometer, a nitrogen introduction device / alkylene oxide introduction device, and a stirring device. The system was purged with nitrogen while stirring, and then heated to 150°C and 8 kg / cm³. 2 Then, 45 parts of ethylene oxide were gradually introduced and the reaction was carried out. The reaction was carried out at a gauge pressure of 0.0 kg / cm². 2The reaction was continued for approximately 4 hours until the reaction reached a certain point, after which it was cooled to room temperature. 3.3 parts of 36% hydrochloric acid aqueous solution were added to this reaction solution and mixed to neutralize the sodium hydroxide. The neutralization reaction product was diluted with toluene, washed three times with water, and desolvented using an evaporator to obtain an ethylene oxide adduct of novolac resin A with a hydroxyl value of 175 g / eq. This adduct contained an average of 1 mole of ethylene oxide per equivalent of phenolic hydroxyl groups. 175 parts of the ethylene oxide adduct of novolac resin A obtained in this way, 50 parts of acrylic acid, 3.0 parts of p-toluenesulfonic acid, 0.1 parts of hydroquinone monomethyl ether, and 130 parts of toluene were charged into a reactor equipped with a stirrer, thermometer, and air blowing tube. The mixture was stirred while blowing air into it, the temperature was raised to 115°C, and the reaction was continued for another 4 hours while distilling off the water produced by the reaction as an azeotropic mixture with toluene, after which it was cooled to room temperature. The resulting reaction solution was washed with a 5% NaCl aqueous solution, and toluene was removed by vacuum distillation. Diethylene glycol monoethyl ether acetate was then added to obtain an acrylate resin solution with a solid content of 68%. Next, 312 parts of the obtained acrylate resin solution, 0.1 parts of hydroquinone monomethyl ether, and 0.3 parts of triphenylphosphine were charged into a four-necked flask equipped with a stirrer and reflux condenser. This mixture was heated to 110°C, 45 parts of tetrahydrophthalic anhydride were added, and the mixture was reacted for 4 hours. After cooling, a carboxyl group-containing resin solution with a solid content of 70% and a solid content acid value of 65 mg KOH / g was obtained.

[0096] [(C) Measurement of the specific surface area of ​​inorganic fillers] (C) For inorganic fillers, the specific surface area was measured using a specific surface area measuring device (manufactured by Mountec Co., Ltd., product name: Macsorb210) in accordance with JIS Z 8830:2013 and the BET specific surface area measurement method.

[0097] [Method for preparing a photocurable resin composition] For each example and comparative example of the photocurable resin composition, the various components listed in Table 1 were blended in the proportions (parts by mass) shown in the table. After pre-mixing with a stirrer, the mixture was kneaded in a bead mill to prepare the photocurable resin composition. The amounts of each component in Table 1 are listed in terms of solid content mass, excluding the solvent.

[0098] [Table 1]

[0099] The details of each component in Table 1 are as follows: *1: Carboxyl group-containing resin synthesized in the synthesis example. *2: EPICLON N-730-A (phenol / modified novolac type epoxy resin, manufactured by DIC Corporation) *3: QSG-30 (Nano Silica, manufactured by Shin-Etsu Chemical Co., Ltd.; average particle size 30 nm, specific surface area 150 m²) 2 / g) *4: YA050C (Nano Silica, manufactured by Admatex Co., Ltd.; average particle size 50 nm, specific surface area 65 m²) 2 / g) *5: YA100C (Nano Silica, manufactured by Admatex Co., Ltd.; average particle size 100 nm, specific surface area 30 m²) 2 / g) *6: SO-C2 (Silica, manufactured by Admatex Co., Ltd.; average particle size 400-600 nm, specific surface area 5 m²) 2 / g) *7: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide *8: NeoMar DA-600 (Dipentaerythritol hexaacrylate, manufactured by Sanyo Chemical Industries, Ltd.) *9: Chromophthal Yellow (yellow pigment, manufactured by Dainichi Seika Kogyo Co., Ltd.) *10: Phthalocyanine blue (blue pigment, manufactured by Dainichi Seika Kogyo Co., Ltd.) *11: Melamine (manufactured by Nikko Bigs Co., Ltd.) *12: Propylene glycol monomethyl ether acetate

[0100] [Method for fabricating evaluation boards] As shown in Table 1, immediately after preparing each photocurable resin composition, it was applied to the surface of a polyethylene terephthalate film (thickness 42 μm, first film) using an applicator to a dry film thickness of 30 μm, and dried at 80°C for 10 minutes to produce a dry film. The dry film was heat-laminated onto a substrate using a vacuum laminator. After exposing this substrate using a DI exposure machine via a step tablet (Photec 41 step), the first film was peeled off and sprayed with a 1% by mass Na2CO3 aqueous solution at 30°C at a spray pressure of 2 kg / cm². 2 The substrate was developed for 60 seconds under the following conditions. This substrate was then subjected to an integrated exposure of 2000 mJ / cm² in a UV conveyor oven. 2 The material was irradiated with ultraviolet light under these conditions and then heated and cured in a constant temperature bath at 170°C for 60 minutes.

[0101] [Resolution evaluation (30 μm on substrate)] Of the obtained cured films, those with a design aperture diameter of Φ60 that showed sensitivity of 8 to 10 steps on the step tablet were observed by SEM, and the resolution was evaluated according to the following criteria. The evaluation results are shown in Table 2. ◎, ○, and △ were considered to be passing grades. <Evaluation Criteria> ◎: ±10% or less of the design value ○: More than ±10% but less than ±15% of the design value △: ±15% or more and less than ±20% of the design value ×: More than ±20% of the design value

[0102] [Evaluation of insulation reliability (B-HAST)] A dry film, prepared using the same method except that the film thickness after drying was set to 23 μm, was heat-laminated onto a substrate pre-treated with a MEC CZ8101 using a vacuum laminator, and then exposed using a DI exposure machine. The first film on this substrate was peeled off, and a 1% by mass Na2CO3 aqueous solution at 30°C was sprayed at a pressure of 2 kg / cm². 2 The substrate was developed for 60 seconds under the following conditions. This substrate was then subjected to an integrated exposure of 2000 mJ / cm² in a UV conveyor oven. 2After UV irradiation under the specified conditions, the substrates were heat-cured in a 170°C constant temperature chamber for 60 minutes. The fabricated substrates were subjected to a voltage of 13.2V in an environment of 130°C and 85% humidity, and their resistance was measured and evaluated according to the following criteria. The evaluation results are shown in Table 2. ◎, ○, and △ were considered acceptable. <Evaluation Criteria> ◎: Time from migration to short circuit is 450 hours or more ○: The time from migration to short is between 400 hours and 450 hours. △: The time from migration to short-circuit is between 350 hours and 400 hours. ×: Time from migration to short circuit is less than 350 hours.

[0103] [Evaluation of crack resistance (TCT)] Except for replacing the φ60μm micro-pore pattern with a Si chip mounting pattern, a substrate with a cured material having a Si chip mounting pattern was obtained using the same procedure as for the evaluation substrate used in the resolution evaluation described above. Next, Au plating and solder bump formation were performed, and Si chips were mounted to obtain sample substrates for temperature cycling tests (TCT). The obtained evaluation substrates were placed in a cold cycling machine that cycles between -55°C and 150°C, and the TCT was performed. During the TCT, the surface of the cured material on each sample substrate was observed at 1000 cycles, 1500 cycles, and 2000 cycles, and the crack resistance was evaluated according to the evaluation criteria below. The evaluation results are shown in Table 2. ◎, ○, and △ were considered to be passing grades. <Evaluation Criteria> ◎: No cracks were observed even after 2000 cycles. ○: No cracks were observed at 1500 cycles, but cracks were observed at 2000 cycles. △: No cracks are observed after 1000 cycles, but cracks are observed after 1500 cycles. ×: Crack formation is observed after 1000 cycles.

[0104] [Table 2]

[0105] As shown in Table 2, the photocurable resin compositions in each example demonstrated excellent thick-film resolution, insulation reliability, and crack resistance. In contrast, Comparative Example 1 had an inorganic filler content of less than 30% by mass, while Comparative Examples 2 and 3 had a total surface area of ​​(C) inorganic filler of 23.0 m². 2 Less than 60.0m 2 Because it was extremely high, it is thought that the above characteristics were not superior compared to each embodiment. Therefore, the photocurable resin composition of the present invention can exhibit excellent thick-film resolution, insulation reliability, and crack resistance by using a predetermined amount of inorganic filler having a predetermined particle size and adjusting the total surface area of ​​the inorganic filler to a predetermined value.

Claims

1. A photocurable resin composition comprising (A) a carboxyl group-containing resin, (B) a thermosetting component, (C) an inorganic filler, and (D) a photopolymerization initiator, The (C) inorganic filler comprises (C-1) a first inorganic filler and (C-2) a second inorganic filler. The average particle size of the first inorganic filler (C-1) is 30 nm or more and less than 300 nm. The average particle size of the second inorganic filler (C-2) is 300 nm or more and 800 nm or less. The content of the inorganic filler (C) is 90 parts by mass or more on a solid content basis, relative to 100 parts by mass on a solid content basis of the carboxyl group-containing resin (A). The content of the inorganic filler (C) is 30% by mass or more in terms of solid content relative to the total amount of the photocurable resin composition. The total surface area, which is the sum of the specific surface areas of the inorganic filler (C) contained in 1 g of the aforementioned photocurable resin composition on a solids basis, is 23.0 m². ２ 60.0m ２ A photocurable resin composition characterized by the following:

2. The photocurable resin composition according to claim 1, wherein the content of the (C-1) first inorganic filler is 20% by mass or more and 40% by mass or less in terms of solid content, relative to the total amount of the photocurable resin composition.

3. The photocurable resin composition according to claim 1, wherein the content of the first inorganic filler (C-1) is 50% by mass or more and 80% by mass or less in terms of solid content relative to the total amount of the inorganic filler (C).

4. The photocurable resin composition according to claim 1, wherein the content of the (C-2) second inorganic filler is 8% by mass or more and 25% by mass or less in terms of solid content relative to the total amount of the photocurable resin composition.

5. The photocurable resin composition according to claim 1, wherein the content of the (C-2) second inorganic filler is 20% by mass or more and 50% by mass or less in terms of solid content relative to the total amount of the (C) inorganic filler.

6. The photocurable resin composition according to claim 1, wherein the (C) inorganic filler includes an inorganic filler that has been surface-treated.

7. A dry film characterized by having a resin layer obtained from a photocurable resin composition according to any one of claims 1 to 6.

8. A cured product characterized by being obtained by curing a photocurable resin composition according to any one of claims 1 to 6.

9. A cured product characterized by being obtained by curing the resin layer of the dry film described in claim 7.

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