Curable resin composition for solder resist

Abstract

To provide a curable resin composition for solder resist that has excellent printability, a high glass transition temperature and low coefficient of thermal expansion of the cured composition, excellent solder heat resistance and adhesion, and low relative permittivity and dielectric loss tangent. [Solution] (A) Bismaleimide compound represented by the following formula (1) TIFF2026106103000034.tif29151 A curable resin composition for solder resist comprising (B) a citraconimide compound, (C) an epoxy resin, (D) a curing accelerator, and (E) an inorganic filler. (In formula (1), A independently represents a tetravalent organic group containing a cyclic structure. B independently represents a divalent hydrocarbon group derived from a dimer acid skeleton. Q independently represents a hydrocarbon group having a divalent alicyclic structure or a hydrocarbon group having an aromatic ring. W is either B or Q. n is a number from 1 to 100, and m is a number from 1 to 100. The order of each repeating unit enclosed by n and m is arbitrary.) (B) a citraconimide compound, (C) an epoxy resin, (D) a curing accelerator, and (E) an inorganic filler.

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition for solder resist. [Background technology]

[0002] In recent years, mobile communication devices such as mobile phones, their base station equipment, network infrastructure equipment such as servers and routers, and electronic devices such as large computers have seen a continuous increase in the speed and capacity of signals used. Consequently, high-frequency bands are used in printed circuit boards mounted on these electronic devices, requiring insulating materials for printed circuit boards to have properties such as low dielectric constant and low dielectric loss tangent. Materials that may satisfy these properties include epoxy resins, modified polyphenylene ether resins, and maleimide resins (Patent Documents 1-4).

[0003] Solder resist is a resin layer formed on a printed circuit board with a completed conductor pattern. It is used to protect the wiring circuit by preventing solder from adhering to areas other than the soldering points when soldering electronic components. The resin composition used for solder resist requires printability, a high glass transition temperature, a low coefficient of thermal expansion, adhesion, and solder heat resistance. However, with the recent increase in high-speed communication, in addition to these properties, properties such as low dielectric constant and low dielectric loss tangent are also required.

[0004] Conventionally, solder resist resin compositions have often used epoxy resins and resins containing acrylate and carboxyl groups as their main components. In particular, photosensitive solder resists are generally developed with alkaline aqueous solutions, and it is necessary for the photosensitive solder resist composition to contain carboxyl groups (Patent Documents 5-8). After coating a substrate with a photosensitive solder resist, exposure, and development to form a pattern, a cured film can be obtained by thermally curing the carboxyl and epoxy groups in the resin. However, since carboxyl and hydroxyl groups remain in the solder resist even after this reaction, there is a problem of large dielectric loss in the high-frequency band, causing distortion of the signal waveform, and also generating heat during use. For these reasons, it is difficult to achieve low dielectric constant and low dielectric loss tangent in solder resist resin compositions using conventional materials, and the development of new materials is required.

[0005] As a new material to meet such demands, for example, Patent Document 9 describes a solder resist film made of a thermosetting resin composition containing a bismaleimide having a dimer acid skeleton and a trifunctional epoxy compound, which has a low dielectric constant and low dielectric loss tangent. However, the thermosetting resin composition described in Patent Document 9 tends to have a low glass transition temperature, and there was still room for improvement. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-1965 [Patent Document 2] Japanese Patent Publication No. 2018-28044 [Patent Document 3] Japanese Patent Publication No. 2020-176190 [Patent Document 4] Japanese Patent Publication No. 2021-181531 [Patent Document 5] Japanese Patent Publication No. 2007-199491 [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-136248 [Patent Document 7] Japanese Patent Application Laid-Open No. 2019-174788 [Patent Document 8] Japanese Patent Application Laid-Open No. 2021-91879 [Patent Document 9] Japanese Patent Application Laid-Open No. 2023-144570 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] Therefore, an object of the present invention is to provide a curable resin composition for solder resist that has excellent printability, a cured product of the composition has a high glass transition temperature, a low coefficient of thermal expansion, excellent solder heat resistance, excellent adhesion, and low relative permittivity and dielectric loss tangent. [Means for Solving the Problems]

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that the following curable resin composition can achieve the above object, and have completed the present invention. That is, the present invention provides the following curable resin composition for solder resist.

[0009] [1] (A) A bismaleimide compound represented by the following formula (1) [Chemical Formula] (In formula (1), A independently represents a tetravalent organic group containing a cyclic structure. B independently represents a divalent hydrocarbon group derived from a dimer acid skeleton. Q independently represents a hydrocarbon group having a divalent alicyclic structure or a hydrocarbon group having an aromatic ring. W is B or Q. n is a number from 1 to 100, and m is a number from 1 to 100. Also, the order of each repeating unit enclosed by n and m is arbitrary.), (B) A citraconimide compound, (C) An epoxy resin, (D) A curing accelerator, and (E) An inorganic filler A curable resin composition for solder resist containing [the specified ingredient]. [2] Furthermore, the curable resin composition for solder resist according to [1], further comprising (F) an organic solvent. [3] (F) The curable resin composition for solder resist according to [2], wherein the boiling point of the organic solvent is 200°C or higher. [4] A curable resin composition for solder resist according to any one of [1] to [3], wherein Q in formula (1) is a divalent group having an alicyclic skeleton, a fluorene skeleton, or an indene skeleton represented by any of the following formulas (2-1), (2-2), or (2-3). [ka] (In the formula, R 1 R is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, n1 is independently an integer from 0 to 4, and 2 and R 3 Each of these is independently a hydrogen atom, a C1-C5 alkyl group, a C4-C10 (hetero)aryl group, a hydroxyl group, an organooxy group, a halogeno group, a trifluoromethyl group, an amino group, or a sulfenyl group. [5] A curable resin composition for solder resist according to any of [1] to [4], wherein A in formula (1) is one of the tetravalent organic groups shown in the following formula. [ka] (The bonds in the above structural formula that are not bonded to substituents are bonded to the carbonyl carbon that forms the cyclic imide structure in formula (1).) [6] A curable resin composition for solder resist according to any one of [1] to [5], wherein the number average molecular weight of the bismaleimide compound of formula (1) is 3,000 to 50,000. [7] (B) A curable resin composition for solder resist according to any one of [1] to [6], wherein the citraconimide compound is a biscitraconimide compound represented by the following formula (3). [ka] (In equation (3), X is a divalent organic group.) [8] A curable resin composition for solder resist according to [7], wherein X in formula (3) is selected from a group represented by the following structure and a hydrocarbon group derived from a dimer acid skeleton. [ka] (* indicates a bond with the nitrogen atom in the citraconimide group. n is a number from 1 to 20.) [9] (B) A curable resin composition for solder resist according to any one of [1] to [8], wherein the number average molecular weight of the citraconimide compound is 100 to 5,000.

[10] (C) A curable resin composition for solder resist according to any one of [1] to [9], wherein the epoxy resin is liquid at 25°C. [Effects of the Invention]

[0010] The curable resin composition for solder resist of the present invention exhibits excellent screen printability. Furthermore, the cured product of this composition has a high glass transition temperature, a low coefficient of thermal expansion, excellent solder heat resistance, low dielectric constant and dielectric loss tangent, and excellent adhesion to copper foil. Therefore, the curable resin composition of the present invention can be suitably used in solder resist. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. The component (A) used in the present invention is a bismaleimide compound represented by the following formula (1). [ka]

[0012] In formula (1), A independently represents a tetravalent organic group containing a cyclic structure. B independently represents a divalent hydrocarbon group derived from a dimer acid skeleton. Q independently represents a hydrocarbon group having a divalent alicyclic structure or a hydrocarbon group having an aromatic ring. W is either B or Q. n is a number from 1 to 100, and m is a number from 1 to 100. Furthermore, the order of each repeating unit enclosed by n and m is arbitrary. That is, the order of each repeating unit is not limited, and the bonding pattern may be alternating, in blocks, or random.

[0013] Here, in formula (1), Q is independently a hydrocarbon group having a divalent alicyclic structure or a hydrocarbon group having an aromatic ring, and is preferably a divalent group having an alicyclic skeleton, a fluorene skeleton, or an indene skeleton represented by any of the following formulas (2-1), (2-2), or (2-3). The bismaleimide compound of component (A) has a divalent hydrocarbon group derived from a dimer acid skeleton in its molecule, and also has an alicyclic skeleton, a fluorene skeleton, or an indene skeleton, so that the cured product of the resin composition containing it has excellent dielectric properties and heat resistance. [ka]

[0014] In the above formula, R 1 R is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, n1 is independently a number from 0 to 4, 2 and R 3 Each of these is independently a hydrogen atom, a C1-C5 alkyl group, a C4-C10 (hetero)aryl group, a hydroxyl group, an alkoxy group, a halogeno group, a trifluoromethyl group, an amino group, or a sulfenyl group. In Formula (2-1), (2-2) or (2-3), a bond to which no substituent in the above structural formula is attached may be directly bonded to the nitrogen atom forming the cyclic imide structure in Formula (1), or may be bonded via a divalent group. The hydrocarbon group represented by Q may contain a group containing a hetero atom, such as an ester group, an ether group, an amide group, or a halogen atom, as a substituent, an interrupting group, etc., as long as it is a hydrocarbon, particularly one having an alicyclic structure or an aromatic ring as a basic skeleton.

[0015] In Formula (2-1), R 1 is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n1 is independently a number from 0 to 4. In Formula (2-1), R 1 includes, independently, a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, etc. Among these, a hydrogen atom or a methyl group is preferable. Note that R 1 may all be the same or different. Further, the above n1 is independently a number from 0 to 4, preferably a number from 0 to 2. Note that n1 may all be the same or different.

[0016] Specific examples of Q having an alicyclic skeleton represented by Formula (2-1) are exemplified by the following structural formulas.

Chemical Formula

[0017] (The bond to which no substituent in the above structural formula is attached is bonded to the nitrogen atom forming the cyclic imide structure in Formula (1).)

[0018] In Formula (2-2), R 2 is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a (hetero)aryl group having 4 to 10 carbon atoms, a hydroxyl group, an organooxy group, a halogeno group, a trifluoromethyl group, an amino group or a sulfenyl group. Examples of the C1-C5 alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, and pentyl group. Examples of the (hetero)aryl groups having 4 to 10 carbon atoms include aryl groups having 6 to 10 carbon atoms such as phenyl, tolyl, xyl, and naphthyl groups, and heteroaryl groups having 4 to 10 carbon atoms such as furyl, thienyl, pyridyl, and indolyl groups. Examples of the organooxy groups include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, t-butyloxy group, n-pentyloxy group, isopentyloxy group, hexyloxy group, benzyloxy group, phenethyloxy group, allyloxy group, phenyloxy group, tolyloxy group, xylyloxy group, naphthyloxy group, furyloxy group, thienyloxy group, pyridyloxy group, and indolyloxy group. Examples of the aforementioned halogen group include a fluoro group, a chloro group, a bromo group, and an iodine group.

[0019] The aforementioned R 2 A hydrogen atom is preferred, and the following structural formula is an example of a Q having a fluorene skeleton represented by formula (2-2). [ka]

[0020] (The bonds in the above structural formula that are not bonded to substituents are bonded to the nitrogen atom that forms the cyclic imide structure in formula (1).)

[0021] As for Q having a fluorene skeleton represented by formula (2-2), the group shown in the following structural formula is particularly preferred. [ka]

[0022] In formula (2-3), R 3These are independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a (hetero)aryl group having 4 to 10 carbon atoms, a hydroxyl group, an alkoxy group, a halogen group, a trifluoromethyl group, an amino group, or a sulfenyl group. Examples of the C1-C5 alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, and pentyl group. Examples of the (hetero)aryl groups having 4 to 10 carbon atoms include aryl groups having 6 to 10 carbon atoms such as phenyl, tolyl, xyl, and naphthyl groups; and heteroaryl groups having 4 to 10 carbon atoms such as furyl, thienyl, pyridyl, and indolyl groups. Examples of the aforementioned alkoxy groups include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, t-butyloxy group, n-pentyloxy group, isopentyloxy group, hexyloxy group, benzyloxy group, phenethyloxy group, allyloxy group, phenyloxy group, tolyloxy group, xylyloxy group, naphthyloxy group, furyloxy group, thienyloxy group, pyridyloxy group, and indolyloxy group. Examples of the aforementioned halogen group include a fluoro group, a chloro group, a bromo group, and an iodine group.

[0023] R in equation (2-3) 3 Preferably, the indene group consists of a hydrogen atom and an alkyl group having 1 to 5 carbon atoms, and a hydrogen atom and a methyl group are particularly preferred. Furthermore, the following structural formula is an example of a specific Q having the indene skeleton represented by formula (2-3). [ka]

[0024] (The bonds in the above structural formula that are not bonded to substituents are bonded to the nitrogen atom that forms the cyclic imide structure in formula (1).)

[0025] The divalent group having an aromatic ring represented by Q is a group derived from a diamine having an aromatic ring in the manufacturing method described below. Examples of such diamines having an aromatic ring include 9,9-bis(4-aminophenyl)fluorene (hereinafter also referred to as FDA), 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino-3-fluorophenyl)fluorene (hereinafter also referred to as FFDA), 9,9-bis(4-amino-3-chlorophenyl)fluorene, 9,9-bis(4-amino-3-hydroxyphenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, Examples include 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine (hereinafter also referred to as PIDA), 3-(4-aminophenyl)-2,3-dihydro-3-methyl-1,1-diphenyl-1H-inden-5-amine, 2-(4-aminophenyl)-1-ethyl-2,3-dihydro-3-methyl-1H-inden-5-amine, and 1,3,3-tris(4-aminophenyl)-2,3-dihydro-1-methyl-1H-inden-5-amine. These diamines may be used individually or in combination of two or more, depending on the purpose and application. From the viewpoint of obtaining a resin composition containing a bismaleimide compound represented by formula (1) that has excellent dielectric properties, a high glass transition temperature, and a low coefficient of thermal expansion, the diamine having an aromatic ring is preferably FDA, FFDA, or PIDA.

[0026] In formula (1), A independently represents a tetravalent organic group containing a cyclic structure, and is a group derived from a tetracarboxylic dianhydride monomer, which may or may not have a fluorene skeleton. Examples of the tetracarboxylic dianhydride monomers are pyromellitic dianhydride, 4,4'-carbonyl diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, 3,4'-oxydiphthalic acid anhydride, 4,4'-biphthalic acid dianhydride, 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and 1,2,4,5-cyclobutanetetracarboxylic acid dianhydride. Crohexanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorenic acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic acid di Examples include anhydrides, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4'-(ethyn-1,2-diyl)diphthalic acid dianhydride, 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid 2,3:6,7-dianhydride, naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)1,4-phenylene, and 3,4,9,10-perylenetetracarboxylic acid dianhydride. These acid anhydrides may be used individually or in combination of two or more, depending on the purpose and application.

[0027] The following structural formula is an example of a specific tetravalent organic group A in formula (1). [ka]

[0028] (The bonds in the above structural formula that are not bonded to substituents are bonded to the carbonyl carbon that forms the cyclic imide structure in formula (1).)

[0029] From the viewpoint of having excellent dielectric properties and excellent solubility in solvents, the bismaleimide compound represented by formula (1) is preferably 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid dianhydride as the tetracarboxylic dianhydride monomer.

[0030] In formula (1), B is independently one or more divalent hydrocarbon groups derived from the dimer acid skeleton. Dimer acids are liquid dibasic acids mainly composed of a 36-carbon dicarboxylic acid, produced by the dimerization of 18-carbon unsaturated fatty acids derived from natural products such as vegetable oils. The dimer acid skeleton is not a single skeleton but has multiple structures, and several isomers exist. Representative dimer acids are classified as linear (a), monocyclic (b), aromatic cyclic (c), and polycyclic (d). In this specification, a dimer acid skeleton refers to a group derived from a dimer amine having a structure in which the carboxyl group of such a dimer acid is replaced with a primary aminomethyl group. In other words, as a divalent hydrocarbon group derived from the dimer acid skeleton of B in formula (1), examples of branched divalent hydrocarbon groups in which two carboxyl groups are substituted with methylene groups can be found in each of the dimer acids shown in (a) to (d) below, but are not limited to these. Furthermore, it is more preferable from the viewpoint of heat resistance and reliability of the cured product if the hydrocarbon group derived from the dimer acid skeleton has a structure in which the carbon-carbon double bond in the hydrocarbon group derived from the dimer acid skeleton is reduced by the hydrogenation reaction. [ka]

[0031] As mentioned above, the dimer acid skeleton has multiple structures; therefore, in this specification, the divalent hydrocarbon group derived from the dimer acid skeleton is referred to as its average structure -C 36 H 70It is sometimes written as -.

[0032] In equation (1), W is either B or Q. Whether W is B or Q depends on the manufacturing method, which will be described later.

[0033] In formula (1), n ​​is between 1 and 100, preferably between 1 and 50, and more preferably between 1 and 10. Also, m is between 1 and 100, preferably between 1 and 50, and more preferably between 1 and 10. If n or m is too small, the cured product will be brittle and prone to cracking, and if n or m is too large, the fluidity will decrease, which may result in poor moldability.

[0034] There are no particular restrictions on the number-average molecular weight (Mn) of the bismaleimide compound of the present invention, but it is preferably 3,000 to 50,000, more preferably 3,500 to 20,000, and even more preferably 4,000 to 10,000. Within this range, the viscosity of the bismaleimide compound of the present invention when incorporated into a resin composition does not become excessively high, and the cured product of the resin composition has high strength.

[0035] In this specification, the number-average molecular weight (Mn) refers to the number-average molecular weight measured by GPC with polystyrene as the standard substance under the following conditions. [GPC measurement conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35mL / min column: TSKgel guardcolumn SuperHZ-L(4.6mmI.D.×2cm×1) TSKgel SuperH-RC(6.0mmI.D.×15cm×2) TSKgel SuperHZ4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ2000 (4.6mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 10 μL (Sample concentration: 0.2% by mass - tetrahydrofuran solution) Detector: Differential refractometer (RI)

[0036] In the bismaleimide compound represented by formula (1) of the present invention, the order of each repeating unit enclosed by n and m in the formula is arbitrary. That is, the order of each repeating unit is not limited, and the bonding mode may be alternating, block, or random, but block bonding is preferred.

[0037] There are no particular restrictions on the method for producing the bismaleimide compound of component (A), but it can be efficiently produced by, for example, the following two methods.

[0038] Manufacturing method 1 One method is the following formula (4) [ka]

[0039] (In equation (4), A is the same as that shown in equation (1) above.) The acid anhydride shown, The following formula (5) H2N-Q-NH2(5)

[0040] (In equation (5), Q is the same as that shown in equation (1) above.) Step A involves synthesizing an amical acid with a diamine having an alicyclic structure or aromatic ring as shown, and then performing ring-closing dehydration. Following step A, the reactant obtained in step A, The following formula (6) H2N-B-NH2(6) (In equation (6), B is the same as that shown in equation (1) above.) Step B involves synthesizing an amic acid with a diamine derived from the dimer acid skeleton shown, and then performing ring-closing dehydration. The method for producing a bismaleimide compound comprises step B, followed by step C, in which maleamic acid is synthesized from the reaction product obtained in step B and maleic anhydride, and the molecular chain ends are sealed with maleimide groups by ring-closing dehydration.

[0041] Manufacturing method 2 Another method is the following formula (4) [ka]

[0042] (In equation (4), A is the same as that shown in equation (1) above.) The acid anhydride shown, The following formula (6) H2N-B-NH2(6)

[0043] (In equation (6), B is the same as that shown in equation (1) above.) Step A' involves synthesizing an amical with a diamine derived from the dimer acid skeleton shown, and then performing ring-closing dehydration. Following step A', the reactant obtained in step A' is used, The following formula (5) H2N-Q-NH2(5) (In equation (5), Q is the same as that shown in equation (1) above.) This method for producing a bismaleimide compound comprises step B' of synthesizing amicalcium with a diamine having an alicyclic structure or aromatic ring as shown, and then dehydrating the ring, and step C' of synthesizing maleamic acid with the reaction product obtained in step B' and maleic anhydride, and then sealing the molecular chain ends with maleimide groups by dehydrating the ring.

[0044] Although the two manufacturing methods described above are shown, the basic procedure involves synthesizing amic acid with a tetracarboxylic dianhydride and a diamine, then proceeding through step A (or step A') of ring-closing dehydration, adding a different diamine after step A (or step A') to synthesize amic acid, proceeding through further ring-closing dehydration in step B (or step B'), reacting with maleic anhydride after step B (or B') to synthesize maleamic acid, and finally proceeding through step C (or step C') of ring-closing dehydration to seal the molecular chain ends with maleimide groups, thereby obtaining a bismaleimide compound. The main difference between the two manufacturing methods described above is the order in which the types of diamines added.

[0045] In the two manufacturing methods described above, each step can be broadly divided into two parts: the synthesis reaction of amic acid or maleamic acid and the ring-closing dehydration reaction, which will be described in detail below.

[0046] In step A (or step A'), an amical is first synthesized by reacting a specific tetracarboxylic dianhydride with a specific diamine. This reaction generally proceeds in an organic solvent (e.g., a nonpolar solvent or a high-boiling point aprotic polar solvent) at room temperature (25°C) to 100°C. The subsequent ring-closing dehydration reaction of amic acid proceeds under conditions of 100-160°C, while removing the by-product water from the system via condensation. Organic solvents (e.g., nonpolar solvents, high-boiling point aprotic polar solvents, etc.) or acid catalysts can be added to accelerate the ring-closing dehydration reaction.

[0047] Examples of organic solvents include toluene, xylene, anisole, biphenyl, naphthalene, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dimethylacetamide (DMAC). These may be used individually or in combination of two or more. Among these, aromatic solvents such as toluene, xylene, anisole, biphenyl, and naphthalene are preferred from the viewpoint of solubility, with toluene, xylene, or anisole being particularly preferred.

[0048] Examples of acid catalysts include sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid. These may be used individually or in combination of two or more. The amount of acid catalyst used is preferably 0.1 moles or more and 2.0 moles or less per mole of diamine, the raw material, and more preferably 0.2 moles or more and 1.0 mole or less.

[0049] The molar ratio of tetracarboxylic dianhydride to diamine is preferably tetracarboxylic dianhydride / diamine = 1.01 to 1.99 / 1.0, more preferably tetracarboxylic dianhydride / diamine = 1.01 to 1.80 / 1.0, and even more preferably tetracarboxylic dianhydride / diamine = 1.10 to 1.60 / 1.0. By blending in this ratio, a copolymer containing imide groups at both ends can be synthesized.

[0050] In step B (or step B'), the amic acid is first synthesized by reacting the biterminal imide group-containing copolymer obtained in step A (or step A') with a specific diamine. This reaction also generally proceeds in an organic solvent (e.g., a nonpolar solvent or a high-boiling point aprotic polar solvent) at room temperature (25°C) to 100°C. Similarly, the subsequent ring-closing dehydration reaction of amic acid proceeds under conditions of 100-160°C, while removing the water produced as a by-product by the condensation reaction. Organic solvents (e.g., nonpolar solvents, high-boiling point aprotic polar solvents, etc.) or acid catalysts can be added to accelerate the ring-closing dehydration reaction.

[0051] Examples of organic solvents include toluene, xylene, anisole, biphenyl, naphthalene, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dimethylacetamide (DMAC). These may be used individually or in combination of two or more. Among these, aromatic solvents such as toluene, xylene, anisole, biphenyl, and naphthalene are preferred from the viewpoint of solubility, with toluene, xylene, or anisole being particularly preferred.

[0052] Examples of acid catalysts include sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid. These may be used individually or in combination of two or more. The amount of acid catalyst used is preferably 0.1 moles or more and 2.0 moles or less per mole of diamine, the raw material, and more preferably 0.2 moles or more and 1.0 mole or less.

[0053] The molar ratio of the copolymer containing both terminal imide groups to the diamine is preferably 1.0:0.01 to 1.0, and more preferably 1.0:0.1 to 1.0.

[0054] In step C (or step C'), maleamic acid is synthesized by reacting the diamine having amino groups at both ends obtained in step B (or step B') with maleic anhydride at room temperature (25°C) to 100°C. Finally, the molecular chain ends are sealed with maleimide groups by ring-closing dehydration while removing the by-product water in the system under conditions of 100 to 160°C, thereby obtaining the desired bismaleimide compound. With this manufacturing method, the resulting bismaleimide compound has a block copolymer structure, which allows for uniform and improved compatibility of the synthesized resin.

[0055] The molar ratio of the diamine having amino groups at both ends to maleic anhydride is preferably 1.0:1.6 to 2.5, and more preferably 1.0:1.8 to 2.2.

[0056] The solution of the bismaleimide compound obtained by the above manufacturing method can be used to wash catalysts and the like by known methods (for example, by adding water, alcohol, etc., stirring, and allowing it to stand to separate the organic solvent from the aqueous solution).

[0057] The bismaleimide compound obtained by the above manufacturing method can be extracted in varnish form, and can also be purified and isolated as a solid powder by reprecipitation or other means by adding a poor solvent. From the viewpoint of manufacturing cost, it is preferable to extract the bismaleimide compound obtained by the above manufacturing method in varnish form. In this case, a resin varnish containing the bismaleimide compound and the organic solvent used in its manufacturing method is obtained. The solvents used for the resin varnish are similar to those used in the manufacturing process, with aromatic solvents such as toluene, xylene, anisole, biphenyl, and naphthalene being preferred, and toluene, xylene, or anisole being particularly preferred.

[0058] The amount of component (A) is preferably 20 to 95% by mass, and more preferably 30 to 70% by mass, based on 100% by mass of the curable resin composition. When the blending ratio is within this range, a cured product with a high glass transition temperature and desirable mechanical strength is obtained, and when used as a solder resist, it exhibits excellent solder heat resistance, low dielectric constant, and low dielectric loss tangent.

[0059] (B) Citraconimide compound Component (B) used in this invention is a citraconimide compound. The citraconimide group is formed by substituting one hydrogen atom in the maleimide group with a methyl group. Due to the effect of this methyl group, compared to maleimide compounds with the same skeleton, it exhibits not only a low dielectric constant and low dielectric loss tangent, but also a low melting point, low viscosity, and improved compatibility with other components. When used in combination with components (A) and (C), the cured product of the composition has a high glass transition temperature and a low coefficient of thermal expansion.

[0060] The properties of the citracomimide compound of component (B) at room temperature and the number-average molecular weight are not particularly limited, but the number-average molecular weight is preferably 100 to 5,000, more preferably 200 to 3,000, and even more preferably 200 to 2,000. Within this range, the viscosity when the citracomimide compound of component (B) is incorporated will not become too high, resulting in a resin composition with excellent printability.

[0061] The citracomide compound of component (B) is preferably a biscitraconimide compound having two citracomide groups in one molecule, from the viewpoint of ease of obtaining the raw material amine compound, solubility of the citracomide compound in solvents, and ease of synthesis, and is particularly preferred to be a biscitraconimide compound represented by the following formula (3). [ka]

[0062] (In formula (3), X represents a divalent organic group.)

[0063] Furthermore, in order to obtain low elasticity and excellent dielectric properties after curing (low relative permittivity and low dielectric loss tangent), the divalent organic group represented by X in the citraconimide compound is more preferably selected from the group shown in the following structure. [ka]

[0064] (* indicates a bond with the nitrogen atom in the citraconimide group. n is a number from 1 to 20.)

[0065] Among the divalent organic groups represented by X, the divalent groups derived from 2-methyl-1,5-diaminopentane, 2,2,4-trimethylhexamethylenediamine, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis[2-(4-aminophenyl)-2-propyl)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane are particularly preferred from the viewpoint of viscosity of the resin composition and flexibility and dielectric properties of the cured product.

[0066] (B) The citraconimide compound of component (B) may be used alone or in combination of two or more types.

[0067] The amount of component (B) is preferably 10 to 100 parts by mass, and more preferably 20 to 80 parts by mass, per 100 parts by mass of component (A). When the blending ratio is within this range, the viscosity of the resin composition is low, and when used as a solder resist, it exhibits excellent printability, low dielectric constant, and low dielectric loss tangent.

[0068] (C) Epoxy resin The component (C) used in this invention is an epoxy resin. The epoxy resin can be cured by an anionic polymerization reaction with the bismaleimide compound (component (A)) and the citraconimide compound (component (B)). The epoxy resin preferably has two or more epoxy groups in one molecule, and conventionally known epoxy resins can be used. From the viewpoint of handling, it is preferable that it is liquid at 25°C.

[0069] Examples of epoxy resins include bisphenol-type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolac-type epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and bisphenol F novolac type epoxy resin; alicyclic epoxy resins such as dicyclopentadiene type epoxy resin and 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexene carboxylate; polyfunctional phenol-type epoxy resins such as resorcinol type epoxy resin and resorcinol novolac type epoxy resin; stilbene type epoxy resin, triazine bone Examples include bisphenol-containing epoxy resins, fluorene-backed epoxy resins, triphenolalkane-type epoxy resins, biphenyl-type epoxy resins, xylylene-type epoxy resins, biphenylaralkyl-type epoxy resins, naphthalene-type epoxy resins, and diglycidyl ether compounds of polycyclic aromatics such as anthracene; alicyclic epoxy compounds such as 1,2-cyclohexanedicarboxylic acid diglycidyl and 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate; aliphatic epoxy resins such as 1,2-propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,4-butanediol diglycidyl ether; and aminophenol-type epoxy resins. Among these, bisphenol-type epoxy resins, aliphatic epoxy resins, and aminophenol-type epoxy resins are preferred. These may be used individually or in combination of two or more.

[0070] The amount of component (C) is preferably 1 to 30 parts by mass, and more preferably 5 to 20 parts by mass, relative to 100 parts by mass of component (A). When the blending ratio is within this range, excellent adhesion is achieved when it is used as a solder resist, and a low dielectric constant and low dielectric loss tangent are achieved.

[0071] (D) Curing accelerator Component (D) used in the present invention is a curing accelerator. The curing accelerator can be any agent that promotes the curing of the (A) bismaleimide compound, (B) citraconimide compound, and (C) epoxy resin, and generally known agents such as imidazole-based curing accelerators, organophosphorus-based curing accelerators, and tertiary amine-based curing accelerators can be used.

[0072] Examples of imidazole-based curing accelerators include imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, and 2-phenyl-4-methylimidazole. Examples of organophosphorus-based curing accelerators include phosphines such as triphenylphosphine, tributylphosphine, tri(p-methylphenyl)phosphine, and tri(nonylphenyl)phosphine; phosphine-borane complexes such as triphenylphosphine-triphenylborane; phosphonium borate salts such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tri-tert-butylphosphonium tetraphenylborate; and bis(tetrabutylphosphonium)dihydrogenpyromellitate. Examples of tertiary amine curing accelerators include tertiary amine compounds such as triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, and 1,8-diazabicyclo[5.4.0]undecene-7; and salts of tertiary amine compounds such as 1,8-diazabicyclo[5.4.0]undecene-7. Among these, imidazole curing accelerators are preferred. These may be used individually or in combination of two or more.

[0073] The amount of component (D) is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the total of components (A), (B), and (C) in the curable resin composition of the present invention. Within this range, the resin composition can be sufficiently cured without adversely affecting the physical properties of the resin composition.

[0074] (E) Inorganic fillers Component (E) used in the present invention is an inorganic filler. The inorganic filler is added to the curable resin composition of the present invention for the purpose of improving the resin strength, solder heat resistance, and reducing thermal expansion. Examples of inorganic fillers include silicas (e.g., fused silica, crystalline silica, cristobalite, etc.), barium sulfate, alumina, talc, mica, silicon nitride, aluminum nitride, boron nitride, titanium dioxide, glass fiber, calcium carbonate, magnesium carbonate, magnesium oxide, etc. These may be used individually or in combination of two or more.

[0075] There are no particular restrictions on the shape of the inorganic filler, and examples include spherical, flaky, needle-shaped, rod-shaped, and elliptical shapes. Among these, spherical, flaky, flake-shaped, elliptical, and rod-shaped are preferred, and spherical, flaky, flake-shaped, and elliptical are even more preferred.

[0076] There are no particular restrictions on the primary particle size of the inorganic filler, but the median diameter measured by a laser diffraction particle size distribution analyzer is preferably 0.05 to 500 μm, more preferably 0.1 to 300 μm, and even more preferably 1 to 100 μm. Within this range, it is easy to uniformly disperse the inorganic filler in the curable resin composition of the present invention, and the inorganic filler will not settle, separate, or become unevenly distributed over time.

[0077] There are no particular restrictions on the amount of component (E) that can be added, but it is preferably 10 to 500 parts by mass, more preferably 30 to 400 parts by mass, and even more preferably 50 to 300 parts by mass, based on 100 parts by mass of the total of components (A), (B), and (C) in the curable resin composition of the present invention. Within this range, the inorganic filler can fully exhibit its function while maintaining the strength of the curable resin composition of the present invention.

[0078] In order to strengthen the bond between the resin and the inorganic filler, the inorganic filler may be pre-surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent. Examples of such coupling agents include epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; aminosilanes such as N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, a reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; and silane coupling agents such as γ-mercaptosilane and γ-episulfidoxypropyltrimethoxysilane. There are no particular restrictions on the amount of coupling agent used for surface treatment or the surface treatment method.

[0079] (F) Organic solvents The component (F) used in this invention is an organic solvent. The organic solvent is formulated for the purpose of adjusting viscosity and improving printability, and can be one that can partially or completely dissolve the resin of component (A). In this invention, component (F) is an optional component, but from the above viewpoint, it is a preferred component to include.

[0080] Examples of component (F) include ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, ethyl diglycol acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, methyl ethyl ketone, cyclohexanone, toluene, xylene, anisole, methanol, isopropanol, cyclohexanol, cyclohexane, cyclopentanone, cyclohexanone, methylcyclohexane, γ-butyrolactone, tetrahydrofuran, 1,4-dioxane, N-methylpyrrolidone, N-vinylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, petroleum ether, petroleum naphtha, cellosolve, butyl cellosolve, carbitol, butyl carbitol, etc. These may be used individually or in combination of two or more types.

[0081] When screen printing the curable resin composition of the present invention, it is preferable to use an organic solvent with a boiling point of 200°C or higher at atmospheric pressure (1013 hPa) from the viewpoint of continuous printability. Examples of organic solvents with a boiling point of 200°C or higher include diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate.

[0082] (F) There are no particular restrictions on the amount of organic solvent blended, but it is preferably 10 to 300 parts by mass, more preferably 30 to 200 parts by mass, and even more preferably 50 to 100 parts by mass, per 100 parts by mass of the total of components (A), (B), and (C) in the curable resin composition of the present invention. Within this range, it is suitable in terms of printability (especially continuous printability) because it prevents film bleeding when printing with the curable resin composition of the present invention and moderately suppresses the drying rate to prevent the plate from drying too quickly.

[0083] Other additives In addition to the components (A) to (F) above, the curable resin composition of the present invention may contain other additives as needed, within a range that does not impair the purpose and effects of the present invention. Examples of such additives include colorants, defoamers, flame retardants, ion trappers, antioxidants, adhesion promoters, and stress reducers. These additives may be used individually or in combination of two or more. Furthermore, each of the additives may be used individually or in combination of two or more.

[0084] The coloring agent is added to products using the solder resist curable resin composition of the present invention from the viewpoint of visibility during inspection. The coloring agent is not particularly limited and all known ones can be used, for example, titanium dioxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, surene pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, etc. As colorants, carbon black, phthalocyanine pigments, and azo pigments are preferred due to their ability to color with relatively small amounts and their visibility during inspection.

[0085] The defoaming agent is used to eliminate foam generated during printing, coating, and curing of the solder resist curable resin composition of the present invention. Examples include silicone-based defoaming agents, acrylic-based defoaming agents, fluorine-based defoaming agents, polymer-based defoaming agents, and the like.

[0086] A flame retardant is added to the curable resin composition for solder resist of the present invention for the purpose of imparting flame retardancy. The flame retardant is not particularly limited and all known ones can be used, for example, phosphazene compounds, silicone compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, molybdenum oxide, etc.

[0087] Ion trapping agents are added to resin compositions to capture ionic impurities and prevent thermal and hygroscopic degradation. There are no particular limitations on the ion trapping agent; all known agents can be used, such as hydrotalcites, bismuth hydroxide compounds, and rare earth oxides.

[0088] There are no particular restrictions on the antioxidants used, but examples include n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)acetate, neododecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, dodecyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and ethyl acetate. α-(4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α-(4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α-(4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2-(n-octylthio)ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2-(n-octadecylthio)ethyl-3, 5-di-t-butyl-4-hydroxyphenyl acetate, 2-(n-octadecylthio)ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-(2-stearoyloxyethylthio)ethyl-7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate, 2-hydroxyethyl-7-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionate, pentae Phenolic antioxidants such as lysritol tetrakiss [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]; sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, and pentaerythrityl tetrakiss (3-laurylthiopropionate);Examples of phosphorus-based antioxidants include tridecyl phosphite, triphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, 2-ethylhexyl diphenyl phosphite, diphenyltridecyl phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, distearyl pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, and 2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosfepin-6-yl]oxy]-N,N-bis[2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosfepin-6-yl]oxy]-ethyl]ethanamine.

[0089] The adhesion promoter is not particularly limited as long as it is a known adhesion promoter that imparts adhesion or tackiness (pressure-sensitive adhesion), and examples include urethane resins, phenolic resins, terpene resins, and silane coupling agents. Among these, silane coupling agents are preferred for imparting adhesion. There are no particular restrictions on the silane coupling agent, but examples include n-propyltrimethoxysilane, n-propyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane, methoxytri(ethyleneoxy)propyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-isocyanatopropyltrimethoxysilane.

[0090] The amounts of other additives vary depending on the purpose of the composition, but are usually 5% by mass or less of the total curable resin composition of the present invention, excluding (E) inorganic fillers and (F) organic solvents.

[0091] [Method for producing the composition] The curable resin composition of the present invention can be manufactured by the following method. For example, a mixture of components (A) to (E) or (A) to (F) is obtained by mixing components (A) to (E) or (A) to (F) simultaneously or separately, subjecting them to heat treatment as necessary, and then stirring, dissolving, and / or dispersing them. Preferably, a mixture of components (A) to (E) or (A) to (F) is obtained by adding the curing accelerator (D) to a mixture of components (A) to (C) and (E) or (A) to (C), (E), and (F), and then stirring, dissolving, and / or dispersing them. Depending on the intended use, at least one of the following additives may be added to the mixture of components (A) to (E) or (A) to (F) and mixed: a colorant, an antifoaming agent, a flame retardant, an ion trapping agent, an antioxidant, an adhesion promoter, and a stress-reducing agent. Each component of components (A) to (F) and the other additives may be used individually or in combination of two or more.

[0092] In the method for producing the curable resin composition of the present invention, the apparatus for mixing, stirring, and dispersion is not particularly limited. Specifically, for example, a mixing machine equipped with stirring and heating devices, a two-roll mill, a three-roll mill, a ball mill, a planetary mixer, or a mass colloider can be used, and these devices may be used in appropriate combinations.

[0093] [Film formation method] The present invention provides a method for forming a film, which includes the step of printing, for example, screen printing, onto a substrate using the curable resin composition of the present invention to form a resist film with a desired pattern.

[0094] Screen printing is a method in which a pattern is formed on a woven fabric (screen) such as nylon, Tetron (registered trademark), or stainless steel using a resist, and a resin composition is extruded through the openings of the screen to print onto a substrate.

[0095] A method for applying the curable resin composition of the present invention to the surface of a substrate by screen printing will be described. First, the surface of the substrate is covered with a screen mask having openings of a desired pattern, and the curable resin composition is placed in the squeegee. Next, the squeegee is moved to pressurize the curable resin composition and move it over the screen mask, thereby filling the openings of the masking member with the curable resin composition (filling step). Next, the screen mask is removed. In this way, a pattern of the curable resin composition can be formed on the surface of the substrate.

[0096] The substrate is not particularly limited, but preferably it is a laminated substrate in which a metal film of a conductive metal such as copper, gold, silver, aluminum, or chromium is coated onto a resin surface substrate such as a phenolic resin, epoxy resin, polyamide resin, polyimide resin, or a reinforced resin in which these resins are reinforced with glass fibers, or a glass substrate, by lamination, vapor deposition, or the like. The substrate or metal film of these substrates may consist of one layer or multiple layers. The substrate may also have through-holes or non-through-holes. The thickness and shape of these substrates are also not particularly limited.

[0097] The thickness of the dried film using the curable resin composition of the present invention is preferably 5 to 100 μm, more preferably 10 to 30 μm, from the viewpoint of protecting against peeling due to external impacts during the work process, solder heat resistance, solvent evaporation from the coating film, and preventing air bubbles from being trapped during coating.

[0098] In screen printing, it is preferable to use a screen with a fine mesh, particularly one with a mesh of about 100 to 400 mesh, in order to accommodate the high resolution of circuit patterns. In this case, the open area of ​​the screen is preferably about 20 to 50%.

[0099] Types of screens include polyester screens, combination screens, metal screens, and nylon screens. Furthermore, high-tensile stainless steel screens can be used when printing highly viscous paste-like materials.

[0100] The squeegee for screen printing can be round, rectangular, or square in shape, and a polished squeegee can also be used to reduce the attack angle (the angle between the printing plate and the squeegee during printing). Other printing conditions can be determined as appropriate from conventionally known conditions.

[0101] The printed curable resin composition of the present invention can be heat-dried. The drying conditions can be appropriately determined depending on the type of organic solvent used, for example, but typically the drying temperature is in the range of 80 to 200°C, preferably 120 to 190°C, and the drying time is 1 to 100 minutes, preferably 20 to 80 minutes. The heating device is not particularly limited, and for example, a hot air furnace or an electric furnace can be used.

[0102] [Application] The patterns formed by screen printing using the curable resin composition of the present invention have high resolution and uniform film thickness without causing mesh residue, bleeding, or deterioration of bubble release properties. Furthermore, the resin composition of the present invention has excellent continuous moldability, and its cured product has excellent heat resistance and dielectric properties. For this reason, the curable resin composition of the present invention is particularly suitable for solder resist applications. Moreover, the curable resin composition of the present invention can be used in a wide range of applications as a screen printing resin composition suitable for forming interlayer insulating materials, passivation films on semiconductor device surfaces at the wafer level, protective films, pigment resists for diodes and tra-color filters, junction protective films for junctions of transistors and other components, liquid crystal color filter protective films, glass fiber protective films, solar cell surface protective films, and conductive films containing conductive fillers. [Examples]

[0103] The following presents synthesis examples, examples, and comparative examples to illustrate the present invention more specifically. However, the present invention is not limited to the following examples. In the synthesis examples, examples, and comparative examples, "room temperature" means 25°C. Also, in Tables 1 and 2, the compounding amounts are shown in parts by mass.

[0104] The respective components used in the examples and comparative examples are shown below. In the following, the number-average molecular weight (Mn) is measured by gel permeation chromatography (GPC) under the following measurement conditions based on polystyrene. [GPC Measurement Conditions] Developing solvent: Tetrahydrofuran Flow rate: 0.35 mL / min Column: TSKgel guardcolumn SuperHZ-L (4.6 mm I.D. × 2 cm × 1) TSKgel SuperH-RC (6.0 mm I.D. × 15 cm × 2) TSKgel SuperHZ4000 (4.6 mm I.D. × 15 cm × 1) TSKgel SuperHZ3000 (4.6 mm I.D. × 15 cm × 1) TSKgel SuperHZ2000 (4.6 mm I.D. × 15 cm × 2) (All are manufactured by Tosoh Corporation) Column temperature: 40°C Sample injection volume: 10 μL (sample concentration: 0.2 mass% - tetrahydrofuran solution) Detector: Differential refractive index meter (RI)

[0105] <Component A: Bismaleimide compound> [Synthesis Example 1] Synthesis of bismaleimide compound A-1 In a 1 L four-necked glass flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer, 28.38 g (0.167 mol) of isophoronediamine, 104.10 g (0.200 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 250 g of toluene, 250 g of N-methyl-2-pyrrolidone, and 9.61 g (0.100 mol) of methanesulfonic acid were added, and the mixture was stirred at 80°C for 3 hours to synthesize amicoic acid. The mixture was then heated to 120°C and stirred for 8 hours while removing the by-product water to synthesize the block copolymer. Finally, in a flask containing the block copolymer solution cooled to 80°C, Priamine-1075 (manufactured by CRODA, average composition formula H2N-C) was added. 36 H 70 Amic acid was synthesized by adding 44.53 g (0.083 mol) of dimeramine (represented by -NH2) and stirring at 80°C for 2 hours. The temperature was then increased to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize the two-terminated diamine compounds. The flask containing the solution of the two-terminated diamine compounds was cooled to room temperature, and then 10.79 g (0.110 mol) of maleic anhydride was added and the mixture was stirred at room temperature for 2 hours to synthesize maleamic acid. The temperature was then increased to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize bismaleimide. The resulting solution was washed 10 times with a mixed aqueous solution of water and isopropyl alcohol to remove impurities such as catalysts. The water in the system was then azeotropically distilled with toluene by vacuum distillation to obtain a 50% solids brown varnish solution containing a bismaleimide compound having the structure shown in formula (A-1) dissolved in toluene. The number-average molecular weight of the obtained bismaleimide compound was 5,200. [ka] m ≈ 3, n ≈ 6 (both mean values) -C 36 H 70 - indicates a hydrocarbon group derived from the dimer acid skeleton derived from dimer amine (Priamine-1075).

[0106] [Synthesis Example 2] Synthesis of Bismaleimide Compound A-2 In a 1 L four-necked glass flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer, 52.27 g (0.150 mol) of 9,9-bis(4-aminophenyl)fluorene, 104.10 g (0.200 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 250 g of toluene, 250 g of N-methyl-2-pyrrolidone, and 9.61 g (0.100 mol) of methanesulfonic acid were added, and the mixture was stirred at 80°C for 3 hours to synthesize amicoic acid. The mixture was then heated to 120°C and stirred for 8 hours while removing the by-product water to synthesize the block copolymer. Finally, in a flask containing the block copolymer solution cooled to 80°C, Priamine-1075 (manufactured by CRODA, average composition formula H2N-C) was added. 36 H 70 Amic acid was synthesized by adding 53.44 g (0.100 mol) of dimeramine (represented by -NH2) and stirring at 80°C for 2 hours. The temperature was then raised to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize the two-terminated diamine compounds. The flask containing the solution of the two-terminated diamine compounds was cooled to room temperature, and then 10.79 g (0.110 mol) of maleic anhydride was added and the mixture was stirred at room temperature for 2 hours to synthesize maleamic acid. The temperature was then raised to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize bismaleimide. The resulting solution was washed 10 times with a mixed aqueous solution of water and isopropyl alcohol to remove impurities such as catalysts. The water in the system was then azeotropically distilled with toluene by vacuum distillation to obtain a 50% solids brown varnish solution containing a bismaleimide compound having the structure shown in formula (A-2) dissolved in toluene. The number-average molecular weight of the obtained bismaleimide compound was 6,200.

[0107] [ka] m ≈ 3, n ≈ 4 (both mean values) -C 36 H 70- indicates a hydrocarbon group derived from the dimer acid skeleton derived from dimer amine (Priamine-1075).

[0108] [Synthesis Example 3] Synthesis of Bismaleimide Compound A-3 In a 1 L four-necked glass flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer, 44.40 g (0.167 mol) of 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, 104.10 g (0.20 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 250 g of toluene, 250 g of N-methyl-2-pyrrolidone, and 9.61 g (0.10 mol) of methanesulfonic acid were added, and the mixture was stirred at 80°C for 3 hours to synthesize amicoic acid. Subsequently, the temperature was raised to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize the block copolymer. Then, in a flask containing the block copolymer solution cooled to 80°C, Priamine-1075 (manufactured by CRODA, average composition formula H2N-C) was added. 36 H 70 Amic acid was synthesized by adding 44.53 g (0.083 mol) of dimeramine (represented by -NH2) and stirring at 80°C for 2 hours. The temperature was then raised to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize the two-terminated diamine compounds. The flask containing the solution of the two-terminated diamine compounds was cooled to room temperature, and then 10.79 g (0.110 mol) of maleic anhydride was added and the mixture was stirred at room temperature for 2 hours to synthesize maleamic acid. The temperature was then raised to 120°C, and the mixture was stirred for 8 hours while removing the by-product water to synthesize bismaleimide. The resulting solution was washed 10 times with a mixed aqueous solution of water and isopropyl alcohol to remove impurities such as catalysts. The water in the system was then azeotropically distilled with toluene by vacuum distillation to obtain a 50% solids brown varnish solution containing a bismaleimide compound having the structure shown in formula (A-3) dissolved in toluene. The number-average molecular weight of the obtained bismaleimide compound was 7,700. [ka] m ≈ 3, n ≈ 6 (both mean values) -C 36 H 70 - indicates a hydrocarbon group derived from the dimer acid skeleton derived from dimer amine (Priamine-1075).

[0109] Maleimide compounds for comparative examples (A'-1): Bismaleimide compound represented by the following formula (A'-1) (SLK-3000, number average molecular weight: 7,500, manufactured by Shin-Etsu Chemical Co., Ltd.) [ka] n ≈ 10 (mean value) -C 36 H 70 - indicates a hydrocarbon group derived from the dimer acid skeleton derived from dimer amine (Priamine-1075).

[0110] (A'-2): Bismaleimide compound represented by the following formula (A'-2) (SLK-1500, number average molecular weight: 2,400, manufactured by Shin-Etsu Chemical Co., Ltd.) [ka] n ≈ 2 (mean value) -C 36 H 70 - indicates a hydrocarbon group derived from the dimer acid skeleton derived from dimer amine (Priamine-1075).

[0111] (A'-3): Bismaleimide compound represented by the following formula (A'-3) (BMI-TMH, number average molecular weight: 500, manufactured by Yamato Chemical Industries, Ltd.) [ka]

[0112] (A'-4): Bismaleimide compound represented by the following formula (A'-4) (BMI-2300, number average molecular weight: 400, manufactured by Yamato Chemical Industries, Ltd.) [ka] n ≈ 2 (mean value)

[0113] <(B) Citraconimide compound> [Synthesis Example 4] Synthesis of Citraconimide Compound B-1 In a 1 L four-necked glass flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer, 71.2 g (0.45 mol) of 2,2,4-trimethylhexanediamine, 111.0 g (0.99 mol) of citraconic anhydride, and 150 g of toluene were added to prepare the reaction mixture, and amicoin was synthesized by stirring at 80°C for 3 hours. Subsequently, 40 g of methanesulfonic acid was added to the reaction mixture, and the temperature was raised to 110°C. The mixture was stirred for 16 hours while removing the by-product water by distillation, and then the reaction mixture was washed five times with 200 g of deionized water. The target product, indicated by (B-1), was then obtained as a brown liquid at room temperature by vacuum stripping at 60°C. The number-average molecular weight of the obtained citracomimide compound was 590. [ka]

[0114] [Synthesis Example 5] Synthesis of Citraconimide Compound B-2 In a 1 L four-necked glass flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer, 155.0 g (0.45 mol) of bisaniline M, 111.0 g (0.99 mol) of citraconic anhydride, and 150 g of toluene were added to prepare the reaction solution, and amicoin was synthesized by stirring at 80°C for 3 hours. Subsequently, 40 g of methanesulfonic acid was added to the reaction solution, and the temperature was raised to 110°C. The mixture was stirred for 16 hours while removing the by-product water by distillation, and then the reaction solution was washed five times with 200 g of deionized water. The target product, shown as (B-2), was then obtained as a yellow liquid at room temperature by vacuum stripping at 60°C. The number-average molecular weight of the obtained citracomimide compound was 530. [ka]

[0115] <(C) Epoxy resin> (C-1) A mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin (ZX-1059: manufactured by Nippon Steel Chemical & Material Co., Ltd., liquid at 25°C) (C-2) Aminophenol-type trifunctional epoxy resin (jER630: manufactured by Mitsubishi Chemical Corporation, liquid at 25°C) (C-3) Neopentyl glycol diglycidyl ether (ED-523L: manufactured by ADEKA Corporation, liquid at 25°C)

[0116] <(D) Curing accelerator> (D-1) 2-Ethyl-4-methylimidazole (2E4MZ: Manufactured by Shikoku Chemicals Holdings Co., Ltd.)

[0117] <(E) Inorganic fillers> (E-1) Molten spherical silica with an average particle size of 0.6 μm (manufactured by Ryusen Co., Ltd.)

[0118] <(F) Organic Solvents> (F-1) Diethylene glycol monoethyl ether acetate (boiling point 218°C)

[0119] <Other ingredients> Coloring agent 1: Phthalocyanine blue Coloring agent 2: Pigment Yellow 147

[0120] [Examples 1-14, Comparative Examples 1-8] Various components were blended in the proportions (parts by mass) shown in Tables 1 and 2, uniformly mixed, and then kneaded in a three-roll mill to obtain a resin composition. The printability of the obtained resin composition was evaluated by the method described below. The obtained resin composition was cured at a temperature of 180°C for 1 hour to obtain cured products of Examples 1 to 14 and Comparative Examples 1 to 8. Various properties of the obtained cured products were measured by the method described below. The results are shown in Tables 1 and 2.

[0121] <Evaluation of printability> Each resin composition from the examples and comparative examples was printed onto a substrate using a screen printing machine (manufactured by CWPRICE CO.INC., product name: MODEL M C212) and a screen mask (325 mesh, emulsion thickness: 15 μm, mesh thickness: 35 μm). The process of setting the mask, filling the composition with a squeegee, and removing the mask was considered one molding step. Continuous molding was performed 10 times, and the continuity was evaluated by checking the pattern shape. Furthermore, the printed substrates were cured in an oven at 100°C for 20 minutes, followed by 180°C for 1 hour, and foaming and bleeding at the pattern edges were observed for the resulting patterns. The results are shown in Tables 1 and 2.

[0122] <Glass transition temperature> The storage modulus (MPa) of the cured material was measured in the range of 0°C to 300°C using a dynamic viscoelasticity analyzer (device name: DMA Q800, manufactured by TA Instruments Co., Ltd.). The temperature at the peak of the graph obtained by plotting the Tanδ value derived from the obtained storage modulus and loss modulus values ​​was defined as the glass transition temperature (Tg). The measurement conditions were a sample thickness of 20 mm × 5 mm × 50 μm, heating rate of 5°C / min, multi-frequency mode, tensile mode, and amplitude of 15 μm. The results are shown in Tables 1 and 2.

[0123] <Coefficient of thermal expansion> The coefficient of thermal expansion (CTE) of the cured material was measured in the range of -50°C to 300°C using a thermomechanical analyzer (device name: TMA Q400, manufactured by TA Instruments Co., Ltd.), and the coefficient of thermal expansion in the range of 0°C to 40°C was calculated. The measurement conditions were a sample of 30 mm × 3 mm × 80 μm thickness, a heating rate of 5°C / min, and a test load of 0.075 N. The results are shown in Tables 1 and 2.

[0124] <Relative permittivity, dielectric loss tangent> A network analyzer (Keysight E5063-2D5) and a stripline (Keycom Corporation) were connected, and the relative permittivity and dielectric loss tangent of the cured material at a frequency of 10 GHz were measured. The results are shown in Tables 1 and 2.

[0125] <Adhesion (copper foil peel strength)> A resin film was prepared by coating a PET film with the prepared curable resin composition to a thickness of 25 μm. Using a vacuum laminator V-130 (manufactured by Nikko Materials Co., Ltd.), the PET film and the SUS plate were overlapped so that the opposite side was in contact, and laminated at 100°C, a vacuum of 0.6 hPa, and a pressure of 0.3 MPa for 60 seconds. After cooling to room temperature, the PET film was peeled off, and an 18 μm thick copper foil (product name: TQ-M4-VSP, manufactured by Mitsui Metals Co., Ltd.) was placed on top. Lamination was performed again at 80°C, a vacuum of 0.6 hPa, and a pressure of 0.3 MPa for 60 seconds, and then heated at 180°C for 1 hour to cure. In accordance with the JIS-C-6481:1996 standard for testing copper-clad laminates for printed circuit boards, the adhesion strength (peel strength) when peeling copper foil from a resin film at a speed of 50 mm / min in a 90° direction over a width of 10 mm was determined using an Autograph (AGS-500NS, Shimadzu Corporation). The results are shown in Tables 1 and 2.

[0126] <Solder heat resistance> The prepared curable resin composition was printed onto a substrate, which was then coated with flux, immersed in a 260°C solder bath for 10 seconds, and rinsed with water. This process was repeated three times, and the appearance of the coating film was observed and evaluated according to the following criteria. The results are shown in Tables 1 and 2. ○: No change was observed in the appearance of the hardened layer. ×: Changes such as peeling, blistering, and discoloration were observed in the cured film within the cured layer.

[0127] [Table 1]

[0128] [Table 2]

[0129] From the above results, the curable resin composition for solder resist of the present invention exhibits good printability, and the cured product of the composition has a high glass transition temperature, a low coefficient of thermal expansion, excellent solder heat resistance, excellent adhesion, and low relative permittivity and dielectric loss tangent. In particular, compared to the resin composition of Comparative Example 1, which uses a bismaleimide compound that does not have a hydrocarbon group having a divalent alicyclic structure or a hydrocarbon group having an aromatic ring in component (A) of the present invention, it was found to have a higher glass transition temperature, a lower coefficient of thermal expansion, and excellent solder heat resistance. [Industrial applicability]

[0130] The present invention provides a solder resist curable resin composition that offers good printability, a high glass transition temperature, a low coefficient of thermal expansion, excellent solder heat resistance, excellent adhesion, and low dielectric constant and dielectric loss tangent, thus providing a highly reliable cured product. Specifically, the solder resist curable resin composition of the present invention can be suitably used as a technique for forming an insulating coating on printed circuit boards and the like used in the high-frequency band.

Claims

1. (A) Bismaleimide compound represented by the following formula (1) 【Chemistry 1】 (In formula (1), A independently represents a tetravalent organic group containing a cyclic structure. B independently represents a divalent hydrocarbon group derived from a dimer acid skeleton. Q independently represents a hydrocarbon group having a divalent alicyclic structure or a hydrocarbon group having an aromatic ring. W is either B or Q. n is a number from 1 to 100, and m is a number from 1 to 100. The order of each repeating unit enclosed by n and m is arbitrary.) (B) Citraconimide compounds, (C) Epoxy resin, (D) Curing accelerator, and (E) Inorganic fillers A curable resin composition for solder resist containing [the specified ingredient].

2. Furthermore, the curable resin composition for solder resist according to claim 1, further comprising (F) an organic solvent.

3. (F) The curable resin composition for solder resist according to claim 2, wherein the boiling point of the organic solvent is 200°C or higher.

4. The curable resin composition for solder resist according to claim 1, wherein Q in formula (1) is a divalent group having an alicyclic skeleton, a fluorene skeleton, or an indene skeleton represented by any of the following formulas (2-1), (2-2), or (2-3). 【Chemistry 2】 (In the formula, R 1 R is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, n1 is independently an integer from 0 to 4, and 2 and R 3 Each of these is independently a hydrogen atom, a C1-C5 alkyl group, a C4-C10 (hetero)aryl group, a hydroxyl group, an organooxy group, a halogeno group, a trifluoromethyl group, an amino group, or a sulfenyl group.

5. The curable resin composition for solder resist according to claim 1, wherein A in formula (1) is any of the tetravalent organic groups shown in the following formula. 【Transformation 3】 (The bonds in the above structural formula that are not bonded to substituents are bonded to the carbonyl carbon that forms the cyclic imide structure in formula (1).)

6. The curable resin composition for solder resist according to claim 1, wherein the number average molecular weight of the bismaleimide compound of formula (1) is 3,000 to 50,000.

7. (B) The curable resin composition for solder resist according to claim 1, wherein the citraconimide compound is a biscitraconimide compound represented by the following formula (3). 【Chemistry 4】 (In equation (3), X is a divalent organic group.)

8. The curable resin composition for solder resist according to claim 7, wherein X in formula (3) is selected from a group represented by the following structure and a hydrocarbon group derived from a dimer acid skeleton. 【Transformation 5】 (* indicates a bond with the nitrogen atom in the citraconimide group. n is a number from 1 to 20.)

9. (B) The curable resin composition for solder resist according to claim 1, wherein the number average molecular weight of the citraconimide compound is 100 to 5,000.

10. (C) The curable resin composition for solder resist according to claim 1, wherein the epoxy resin is liquid at 25°C.

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