Thermosetting maleimide resin composition, adhesive, primer, chip code agent and semiconductor device

Abstract

To provide a thermosetting maleimide resin composition or the like, which does not employ an aprotic polar solvent such as NMP, can be cured at temperatures lower than 250°C, requires no thermosetting in a nitrogen atmosphere, exhibits superior storage stability and adhesion, and yields a cured product with a high glass transition temperature.SOLUTION: A thermosetting maleimide resin composition contains: (A) a maleimide compound having a bisphenol structure with a number average molecular weight of 5,000 to 50,000; (B) an epoxy resin with two or more epoxy groups in one molecule; and (C) a diaminotriazine ring-containing imidazole.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting maleimide resin composition, an adhesive, a primer, a chip coating agent, and a semiconductor device. [Background technology]

[0002] Power semiconductor modules are widely used in fields that require efficient power conversion. For example, their application range is expanding to power electronics fields such as industrial equipment, electric vehicles, and home appliances. These power semiconductor modules contain built-in switching elements and diodes, and the elements use Si (silicon) semiconductors or SiC (silicon carbide) semiconductors.

[0003] Conventionally, resin compositions using curable epoxy resins or cyanate resins have been widely used to protect semiconductor elements (Patent Documents 1 and 2). However, when semiconductor devices are operated at high temperatures, the semiconductor elements, the substrate, and the encapsulant have different linear expansion coefficients, which causes stress around the semiconductor device when subjected to heat cycles, making the encapsulant more susceptible to peeling. Furthermore, the cured resin components used in the encapsulant have low moisture resistance and the cured product has high hardness, so that adhesion may not occur during the encapsulation process of the semiconductor element, and peeling is often observed in subsequent processes, resulting in a problem of reduced reliability as a package.

[0004] To solve these problems, a method of providing a primer layer on a semiconductor element or lead frame is known (Patent Documents 3 and 4). Polyimide resin is mainly used for this primer layer. Polyimide resin is widely used as a varnish for an interlayer insulating film or a surface protective film of a semiconductor because of its excellent heat resistance, flame retardancy, mechanical properties, and electrical insulation properties. For example, it has been disclosed that a polyimide resin is applied in a varnish state to a semiconductor element or the like directly or via an insulating film, and then cured to form a protective film made of polyimide resin, which is then sealed with a molding material such as an epoxy resin (Patent Documents 5 and 6).

[0005] This polyimide varnish is generally produced by dissolving polyimide in N-methyl-2-pyrrolidone (NMP). NMP has long been used in many places as an aprotic polar solvent, but due to its high boiling point and toxicity, regulations on its use are becoming increasingly strict, particularly in Europe. Furthermore, polyimide requires extremely high temperatures of over 250°C for curing, and polyimide itself has issues such as being susceptible to moisture absorption, so alternative materials are desired.

[0006] To solve these problems, it has been proposed to use a thermosetting cyclic imide resin composition that can be cured at a relatively low temperature as a primer (Patent Document 7). The thermosetting cyclic imide resin composition described in Patent Document 7 must be cured in a nitrogen atmosphere in order to stably exhibit high adhesive strength, and when an organic peroxide with a short half-life temperature is used as a reaction initiator, the glass transition temperature of the resulting cured product does not increase very much.

[0007] Meanwhile, a resin composition containing a maleimide compound and a specific compound having a triazine skeleton has been reported (Patent Document 8). This is a resin composition intended primarily for use on substrates, and is said to have excellent adhesive strength to metals, but it has issues with long-term reliability, and furthermore, high-temperature, long-term curing conditions are required for curing, which places restrictions on manufacturing equipment. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-48434 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-93971 [Patent Document 3] Japanese Patent Application Publication No. 2019-176085 [Patent Document 4] Japanese Patent Publication No. 2022-148684 [Patent Document 5] Japanese Patent Application Laid-Open No. 2007-8977 [Patent Document 6] Japanese Patent Application Laid-Open No. 2010-70645 [Patent Document 7] Patent Publication No. 2021-25031 [Patent Document 8] International Publication No. 2020 / 111065 Summary of the Invention [Problem to be solved by the invention]

[0009] Accordingly, an object of the present invention is to provide a thermosetting maleimide resin composition that can provide a cured product having excellent storage stability and adhesiveness and a high glass transition temperature without using an aprotic polar solvent such as NMP and at a temperature lower than 250°C, the curing temperature of ordinary polyimides, even without thermal curing in a nitrogen atmosphere; an adhesive, a substrate material, a primer, a chip coating agent, and a semiconductor device having a cured product of the composition, all of which use the composition; [Means for solving the problem]

[0010] As a result of extensive research to solve the above problems, the present inventors have found that the following thermosetting maleimide resin composition can achieve the above object, and have thus completed the present invention.

[0011] That is, the present invention provides the following thermosetting maleimide resin composition, etc. [1] (A) a maleimide compound represented by the following formula (1) or (2) and having a number average molecular weight of 5,000 to 50,000: (B) an epoxy resin having two or more epoxy groups in one molecule, and (C) Imidazole having a diaminotriazine ring A thermosetting maleimide resin composition comprising: [ka] (In formula (1), X 1 are independently expressed by the following formula: [ka] and l is a number from 1 to 40. [ka] (In formula (2), X 2 are independently expressed by the following formula: [ka] where m is a number from 1 to 50, n is a number from 1 to 50, and A 1 and A 2 are each independently represented by the following formula (3) or the following formula (4): [ka] [ka] (In formula (3) and formula (4), X 3 is expressed as follows: [ka] In formula (3), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms. ) [2] The thermosetting maleimide resin composition according to [1], wherein the blending amount of the component (B) is 0.05 to 25 parts by mass and the blending amount of the component (C) is 0.05 to 5 parts by mass, relative to 100 parts by mass of the total of the components (A) and (B). [3] The thermosetting maleimide resin composition according to [1] or [2], wherein component (B) is an epoxy resin having a glycidyl group. [4] The thermosetting maleimide resin composition according to any one of [1] to [3], further comprising an organic solvent. [5] An adhesive comprising the thermosetting maleimide resin composition according to any one of [1] to [4]. [6] A primer comprising the thermosetting maleimide resin composition according to any one of [1] to [4]. [7] A chip coating agent comprising the thermosetting maleimide resin composition according to any one of [1] to [4]. [8] A semiconductor device comprising a cured product of the thermosetting maleimide resin composition according to any one of [1] to [4]. [Effects of the Invention]

[0012] The thermosetting maleimide resin composition of the present invention does not require the use of an aprotic polar solvent such as NMP, does not require thermal curing in a nitrogen atmosphere, which is generally required for curing maleimides, and provides a cured product with excellent storage stability and adhesiveness, and a high glass transition temperature even under curing conditions lower than the 250° C. curing temperature of ordinary polyimides. Therefore, the thermosetting maleimide resin composition of the present invention is useful as an adhesive, a primer, or a chip coating agent using the composition, and as a semiconductor device having a cured product of the composition. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in more detail below.

[0014] (A) Specific maleimide compounds The component (A) is a maleimide compound represented by the following formula (1) or (2) and has a number average molecular weight of 5,000 to 50,000.

[0015] [ka] In formula (1), X 1 are independently divalent groups selected from the following formulae: [ka] X in formula (1) 1 As the alkyl group, -CH2- and -C(CH3)2- are preferred from the viewpoint of easy availability of raw materials. In formula (1), l is a number from 1 to 40, and preferably a number from 5 to 30.

[0016] [ka] In formula (2), X 2 are independently divalent groups selected from the following formulae: [ka] X in equation (2) 2 As the alkyl group, -CH2- and -C(CH3)2- are preferred from the viewpoint of easy availability of raw materials. In formula (2), m is a number of 1 to 50, and preferably a number of 1 to 40. In formula (2), n is a number from 1 to 50, and preferably a number from 1 to 40. In formula (2), A 1 and A 2 are each independently a group represented by the following formula (3) or (4): [ka] [ka] In formula (3) and formula (4), X 3 is a divalent group selected from the following formulas: [ka] X in formula (3) and formula (4) 1 As the alkyl group, -CH2- and -C(CH3)2- are preferred from the viewpoint of easy availability of raw materials. In formula (3), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms. R in equation (3) 1Examples of the unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, and a cyclohexyl group, and also include groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as F, Cl, and Br, such as a trifluoromethyl group. 1 From the viewpoint of availability of raw materials, it is preferable that the alkyl group is a hydrogen atom or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 3 carbon atoms.

[0017] In addition, in the maleimide compound represented by formula (2), A 1 and A 2 For example, in formula (2), A 1 When A is a group represented by the formula (3), 2 is a group represented by the formula (4), and for example, A 1 When A is a group represented by the formula (4), 2 is preferably a group represented by the formula (3). The bonding pattern of the repeating units m and repeating units n in the maleimide compound represented by formula (2) may be random or block, but is preferably block from the viewpoint of the mechanical strength of the cured product.

[0018] As represented by formula (1) or (2), component (A) has a bisphenol structure in its molecule, which allows it to be produced without using NMP and provides excellent solvent solubility, being soluble in solvents other than NMP. Maleimide compounds having a bisphenol structure are also suitable from the standpoint of ease of raw material availability. Examples of the bisphenol structure contained in component (A) include bisphenol A, bisphenol F, bisphenol E, and bisphenol AF, and are not particularly limited, but bisphenol A is preferred. Furthermore, when l, m, and n are each within the above ranges, the maleimide compound represented by formula (1) or (2) exhibits a good balance between solubility in solvents and film-forming ability in the uncured state and the toughness and heat resistance of the resulting cured product.

[0019] The number-average molecular weight of the maleimide compound of component (A) is 5,000 to 50,000, preferably 7,000 to 40,000, and more preferably 10,000 to 20,000. When the number-average molecular weight is within this range, the maleimide compound of component (A) dissolves stably in a solvent and exhibits good film-forming ability, particularly before curing. The number average molecular weight referred to in the present invention refers to the number average molecular weight measured by gel permeation chromatography (GPC) under the following conditions using polystyrene as a standard substance. [GPC measurement conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK-GEL H type (manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass THF solution)

[0020] The maleimide compound of component (A) preferably satisfies the following formula (5): Number of aromatic atoms / total number of atoms excluding hydrogen atoms>0.5 (5) A compound satisfying formula (5) indicates that it has many aromatic rings within the compound. The maleimide compound of component (A) is preferably a compound that satisfies the relationship: number of aromatic atoms / total number of atoms excluding hydrogen atoms > 0.55.

[0021] The number of aromatic atoms refers to the number of atoms constituting the aromatic partial structure in component (A). Examples of aromatic partial structures include benzene rings, pyridine rings, pyrrole rings, furan rings, thiophene rings, imidazole rings, and oxazole rings. The number of aromatic atoms does not include the number of hydrogen atoms bonded to the atoms constituting the aromatic partial structure, and the number of atoms of substituents such as alkyl groups, alkoxy groups, and halogen atoms. The total number of atoms excluding hydrogen atoms refers to the number of atoms other than hydrogen atoms in component (A), including carbon atoms, nitrogen atoms, oxygen atoms, sulfur atoms, halogen atoms, and the like. The closer the ratio of the number of aromatic atoms / total number of atoms excluding hydrogen atoms is to 1, the higher the proportion of aromatics.

[0022] Component (A) satisfies formula (5) and has many aromatic rings, especially benzene rings, in the molecule, which can improve many mechanical properties such as low moisture absorption, film strength, and voltage resistance.

[0023] The maleimide compound represented by formula (1) or (2) of component (A) can be produced, for example, by the method described in JP-A-2021-017485. The maleimide compound of the component (A) may be used alone or in combination of two or more. Furthermore, the thermosetting maleimide resin composition of the present invention (however, in the case where the thermosetting maleimide resin composition contains an organic solvent (D) described below, the thermosetting maleimide resin composition excluding the organic solvent (D)) preferably contains 50 to 99 mass %, more preferably 60 to 98.5 mass %, and even more preferably 70 to 98 mass % of component (A).

[0024] (B) Epoxy resin with two or more epoxy groups in one molecule Component (B) is an epoxy resin with two or more epoxy groups per molecule. The epoxy groups in the epoxy resin react with component (C), described below, to generate active species, which then react with the maleimide groups in component (A), initiating anionic polymerization. Unlike radical polymerization, which proceeds using organic peroxides, this anionic polymerization proceeds without the influence of oxygen radicals and is therefore independent of the reaction atmosphere.

[0025] Taking into consideration the reactivity with component (C), component (B) is preferably an epoxy resin having a glycidyl group.

[0026] Examples of component (B) include phenol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenol type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins, naphthol type epoxy resins, xylylene type epoxy resins, biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, triphenylmethane type epoxy resins, alicyclic type epoxy resins, glycidylamine type epoxy resins, dicyclopentadiene type epoxy resins, stilbene type epoxy resins, sulfur atom-containing epoxy resins, and phosphorus atom-containing epoxy resins. It is preferable to use component (B) that is liquid at room temperature (25°C) from the viewpoints of compatibility and wettability with the substrate.

[0027] The amount of component (B) blended is preferably 0.05 to 25 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the total of components (A) and (B). Outside this range, curing may be too slow or too fast during molding, which is undesirable. Furthermore, the balance between heat resistance and moisture resistance of the resulting cured product may be poor. The epoxy resin of component (B) may be used alone or in combination of two or more.

[0028] (C) Imidazole having a diaminotriazine ring In the present invention, an imidazole having a diaminotriazine ring is further blended as component (C). As described above, the imidazole in component (C) reacts with the epoxy group in component (B) to generate an active species, which then reacts with the maleimide group in component (A) to initiate anionic polymerization. The diaminotriazine ring is not only effective in improving adhesion to metals, particularly copper, but also effectively enhances the storage stability of the resin composition of the present invention. Furthermore, the presence of imidazole promotes the polymerization of maleimide, effectively imparting heat resistance. Component (C) is not particularly limited as long as it is an imidazole having a diaminotriazine ring.

[0029] Specific examples include 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name 2MZ-A, manufactured by Shikoku Chemical Industry Co., Ltd.), 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine (trade name C11Z-A, manufactured by Shikoku Chemical Industry Co., Ltd.), 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name 2E4MZ-A, manufactured by Shikoku Chemical Industry Co., Ltd.), and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (trade name 2MA-OK, manufactured by Shikoku Chemical Industry Co., Ltd.).

[0030] The blending amount of component (C) is preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the combined total of components (A) and (B). If the blending amount of component (C) per 100 parts by mass of the combined total of components (A) and (B) is less than 0.05 parts by mass, the adhesive strength improving effect cannot be obtained, whereas if it exceeds 5 parts by mass, poor dispersibility may result in poor appearance or reduced reliability.

[0031] organic solvents The composition of the present invention can further contain an organic solvent. There are no limitations on the type of organic solvent as long as it dissolves components (A) and (B), but N-methyl-2-pyrrolidone (NMP) is excluded from the scope of this specification from the standpoint of environmental impact. In this context, "the organic solvent can dissolve component (A)" means that when 25% by mass of component (A) is added to the organic solvent, no residual component (A) is visually observed at 25°C. Examples of the organic solvent that can be used include common organic solvents such as methyl ethyl ketone (MEK), cyclohexanone, ethyl acetate, tetrahydrofuran (THF), isopropanol (IPA), xylene, toluene, anisole, etc. These may be used alone or in combination of two or more. When the composition of the present invention is used as a primer, preferred organic solvents include cyclohexanone, xylene, and anisole. From the viewpoint of the solubility of the above-mentioned component (A), organic solvents such as anisole, xylene, toluene, and cyclohexanone are preferred. On the other hand, from the viewpoint of their high boiling points and toxicity, it is preferable not to use aprotic polar solvents such as the above-mentioned NMP, dimethyl sulfoxide (DMSO), and dimethylformamide (DMF). Unlike conventional compositions containing polyimide compounds that are soluble only in aprotic polar solvents, the composition of the present invention has the advantage of not requiring the use of these aprotic polar solvents. The amount of component (D) blended is preferably 100 to 800 parts by mass, and more preferably 150 to 700 parts by mass, per 100 parts by mass of component (A).

[0032] <Other additives> The thermosetting maleimide resin composition of the present invention can be blended with various additives within the scope of the present invention, provided that the effects of the present invention are not impaired. For example, to improve resin properties, curable resins such as acrylic resins, organopolysiloxanes, silicone oils, thermoplastic resins, thermoplastic elastomers, organic synthetic rubbers, light stabilizers, polymerization inhibitors, flame retardants, pigments, dyes, adhesive aids, and the like may be blended. Furthermore, to improve electrical properties, ion trapping agents and the like may be blended. Furthermore, to improve dielectric properties, fluorine-containing materials and the like may be blended. Inorganic fillers such as silica may be added to adjust the coefficient of thermal expansion (CTE). However, it is not preferable to add organic peroxides or photopolymerization initiators since they affect the curing speed and curing characteristics.

[0033] The thermosetting maleimide resin composition of the present invention can be produced by mixing the components (A), (B), and (C) with an organic solvent and other additives. The thermosetting maleimide resin composition of the present invention can be used as an adhesive, a primer, a chip coating agent, a coating material for semiconductor devices, etc. There are no particular limitations on the method and form of use. Examples of use are given below, but are not limited to these.

[0034] For example, a thermosetting maleimide resin composition containing components (A), (B), and (C) and an organic solvent can be applied to a substrate, followed by heating for 0.5 to 5 hours at a temperature typically above 80°C, preferably above 100°C. A strong maleimide coating can be formed by further heating the substrate for 0.5 to 10 hours at a temperature above 130°C, preferably above 150°C. While polyimides typically require temperatures above 150°C for drying and above 220°C for thermal curing, the thermosetting maleimide resin composition of the present invention does not require such high temperatures. Specifically, the organic solvent can be removed at 150°C or below, and thermal curing (film formation) can be performed at 200°C or below. In order to efficiently remove the organic solvent in the composition and effectively promote the resin reaction, the curing temperature may be increased in stages in some cases. The cured product (film) obtained by curing the composition of the present invention has excellent mechanical properties, heat resistance, dielectric constant, dielectric loss tangent, moisture resistance, and adhesion. Therefore, the cured product of the present invention can be used, for example, as an adhesive between a semiconductor element and a lead frame; a primer used between a semiconductor encapsulant and a lead frame; a chip coating agent (passivation film) for the surface of a semiconductor element; a junction protection film for junctions of diodes, transistors, etc.; an alpha-ray shielding film for VLSI; an interlayer insulating film; and a conformal coating for printed circuit boards.

[0035] Examples of the application method include, but are not limited to, a spin coater, a slit coater, a spray, a dip coater, a bar coater, and the like.

[0036] After forming the cured product (film), the epoxy resin molding material for semiconductor encapsulation can be molded onto the cured product (film), thereby improving the adhesion between the epoxy resin molding material for semiconductor encapsulation and the substrate. The semiconductor device obtained in this manner exhibits high reliability, with no cracks or peeling of the epoxy resin molding material for semiconductor encapsulation from the substrate observed during solder reflow after moisture absorption.

[0037] In this case, as the epoxy resin molding material for semiconductor encapsulation, a known epoxy resin composition for semiconductor encapsulation containing an epoxy resin having two or more epoxy groups in one molecule; a phenolic resin; an epoxy resin curing agent such as an acid anhydride; and / or an inorganic filler, etc., can be used, and commercially available products can also be used.

[0038] When an easily oxidizable metal such as copper is used as the substrate, the environment in which the thermosetting maleimide resin composition or the epoxy resin molding material for semiconductor encapsulation is fully cured is preferably a nitrogen atmosphere to prevent oxidation. However, the adhesive strength can also be improved by curing the thermosetting maleimide resin composition of the present invention in an air atmosphere at a temperature that does not cause oxidation. [Example]

[0039] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the examples and comparative examples, "room temperature" means 25°C.

[0040] The components used in the examples and comparative examples are shown below. Note that the number average molecular weight (Mn) below is measured by gel permeation chromatography (GPC) under the following measurement conditions using polystyrene as the standard substance. [GPC measurement conditions] Developing solvent: tetrahydrofuran Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK-GEL H type (manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass THF solution)

[0041] (A) Maleimide compound [Synthesis Example 1] A 1 L glass four-neck flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer was charged with 65.06 g (0.125 mol) of 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride, 61.59 g (0.150 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 250 g of anisole, and the amic acid was synthesized by stirring at 80°C for 3 hours. The temperature was then raised to 150°C and the mixture was stirred for 2 hours while distilling off the by-product water, producing a diamine-terminated product. The flask containing the resulting solution of diamines at both ends was cooled to room temperature, and then 4.39 g (0.055 mol) of maleic anhydride was added. The mixture was stirred at 80°C for 3 hours to synthesize maleamic acid. The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water, yielding a varnish of an aromatic bismaleimide compound represented by the following formula (A-1). The number-average molecular weight (Mn) of the aromatic bismaleimide compound was 12,000. Anisole was added so that the nonvolatile components of the varnish reached 17% by mass. [ka] l≒8 (average value) (Number of aromatic atoms / Number of constituent atoms≒0.70)

[0042] [Synthesis Example 2] A 1 L glass four-neck flask equipped with a stirrer, Dean-Stark tube, cooling condenser, and thermometer was charged with 65.06 g (0.125 mol) of 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride, 35.26 g (0.115 mol) of 4,4-methylenebis(2,6-diethylaniline), and 250 g of anisole, and the mixture was stirred at 80°C for 3 hours to synthesize an amic acid. The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water to synthesize a copolymer. After that, 7.05 g (0.015 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane was added to the flask containing the copolymer solution, which had been cooled to room temperature, and the mixture was stirred at 80°C for 3 hours to synthesize an amic acid.The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water, synthesizing a diamine-terminated product. The flask containing the resulting solution of diamine compounds at both ends was cooled to room temperature, and then 1.45 g (0.015 mol) of maleic anhydride was added. The mixture was stirred at 80°C for 3 hours to synthesize maleamic acid. The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water, yielding a varnish of an aromatic bismaleimide compound represented by the following formula (A-2). The number-average molecular weight (Mn) of the aromatic bismaleimide compound was 15,500. Anisole was added so that the nonvolatile content of the varnish reached 17% by mass. [ka] m≒8, n≒1 (average values) (Number of aromatic atoms / Number of constituent atoms≒0.60)

[0043] Other maleimide compounds (A-3): A bismaleimide compound represented by the following formula (trade name: BMI-5000, Mn: 8000, manufactured by Designer Molecules Inc.) [ka] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton. n≒8 (average value) (Number of aromatic atoms / Number of constituent atoms≒0.10) (A-4): 4,4'-diphenylmethane bismaleimide (trade name: BMI-1000, Mn: 410, manufactured by Daiwa Chemical Industry Co., Ltd.) (Number of aromatic atoms / Number of constituent atoms≒0.44)

[0044] (B) Epoxy resin with two or more epoxy groups in one molecule (B-1): Bisphenol A epoxy resin that is liquid at room temperature (trade name: jER-828, manufactured by Mitsubishi Chemical Corporation, containing glycidyl groups) (B-2): Biphenyl-type epoxy resin that is solid at room temperature (trade name: YX-4000, manufactured by Mitsubishi Chemical Corporation, containing glycidyl groups) (B-3): alicyclic epoxy resin that is liquid at room temperature (product name: CEL-2021P, manufactured by Daicel Corporation, glycidyl group-free)

[0045] (C) Imidazole having a diaminotriazine ring (C-1) 2,4-Diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine (trade name: 2E4MZ-A, manufactured by Shikoku Chemicals Corporation) (C-2) 2-Ethyl-4-methylimidazole (trade name: 2E4MZ, manufactured by Shikoku Chemicals Corporation, for comparative example)

[0046] (D) Components for comparative example (D-1) Silane coupling agent having a diaminotriazine skeleton (trade name: VD-5, Shikoku Chemicals Corporation, for comparative example) (D-2) Dicumyl peroxide (trade name: Perkadox BC-FF, manufactured by Kayaku Nouryon Co., Ltd., for comparative example)

[0047] (Examples 1 to 7, Comparative Examples 1 to 11) Varnishes of thermosetting maleimide resin compositions were prepared by mixing the components according to the formulations shown in Tables 1 and 2. In all formulations, anisole was added so that component (A) was 16.7 mass % and all of component (A) was dissolved.

[0048] <Storage stability> The kinematic viscosity of the varnish of the composition obtained in each example was measured in accordance with JIS Z8803:2011. These varnishes were left to stand for 168 hours at 25°C, and then the kinematic viscosity was measured in the same manner. In this case, those whose kinematic viscosity increased by less than 20% from the initial kinematic viscosity were rated as ◯, those whose kinematic viscosity increased by 20% or more but less than 100% were rated as △, and those whose kinematic viscosity increased by 100% or more were rated as ×.

[0049] <Glass transition temperature> The varnish-like thermosetting maleimide resin composition was applied to a 38 μm-thick PET film using a roller coater to a dry thickness of 30 μm, and then dried at 110°C for 20 minutes to obtain an uncured resin film. The uncured resin film and the PET film were then cured in an air atmosphere at 150°C for 4 hours to obtain a cured resin film. The glass transition temperature of the cured resin film was measured using a TA Instruments DMA-800.

[0050] <Adhesion> (Adhesion test before moisture absorption) The varnish-like thermosetting maleimide resin composition was spray-coated onto a 20 mm × 20 mm copper frame substrate and a Ni-plated copper frame substrate, dried at 110°C for 20 minutes, and further cured in an air atmosphere at 150°C for 4 hours to form a cured film (primer layer). On the cured film, a semiconductor encapsulation epoxy resin molding material KMC-2284 manufactured by Shin-Etsu Chemical Co., Ltd. was applied to a base area of ​​10 mm 2 The adhesive was molded into a 3 mm high cylindrical shape (cured for 120 seconds under conditions of a pressure of 6.9 MPa and a temperature of 175°C). The test pieces were then post-cured at 180°C for 4 hours, and the adhesive strength at 25°C before moisture absorption was measured using a universal bond tester (DAGE SERIES 4000, manufactured by Nordson DAGE) at a speed of 0.2 mm / sec.

[0051] <Adhesion test after moisture absorption> To measure the adhesive strength after moisture absorption, test pieces were prepared in the same manner as in the adhesive strength test before moisture absorption. The test pieces were left in an 85°C / 85%RH atmosphere for 168 hours, then subjected to IR reflow at 260°C three times, and the adhesive strength after moisture absorption was measured at 25°C at a speed of 0.2 mm / s using a universal bond tester (DAGE SERIES 4000, manufactured by Nordson DAGE).

[0052] <Adhesion test after heat treatment> To measure the adhesive strength after heat treatment, test pieces were prepared in the same manner as in the adhesive strength test before moisture absorption. The test pieces were left in an atmosphere at 180°C for 500 hours, and then the adhesive strength was measured at 25°C at a speed of 0.2 mm / s using a universal bond tester (DAGE SERIES 4000, manufactured by Nordson DAGE).

[0053] In Comparative Example 1, the adhesive strength was measured without using a primer (varnish of the composition), and therefore the values ​​of storage stability and glass transition temperature are not shown. [Table 1] [Table 2] *When the epoxy resin molding material for semiconductor encapsulation was molded, peeling easily occurred, so only the initial adhesive strength was measured.

[0054] From the above, it was found that the composition of the present invention can give a cured product with excellent adhesion and a high glass transition temperature when cured in an air atmosphere at a low temperature of 150° C. Furthermore, the composition of the present invention has excellent stability over time and storage stability as a varnish compared to the compositions of the comparative examples, and therefore can be suitably used as a primer, particularly as a primer for copper substrates or as a primer to be used between a semiconductor encapsulant and a lead frame.

Claims

1. (A) a maleimide compound represented by the following formula (1) or (2), having a number average molecular weight of 5,000 to 50,000 and having a bisphenol structure in the molecule: (B) an epoxy resin that is liquid at 25°C and has two or more epoxy groups in one molecule: 0.05 to 20 parts by mass per 100 parts by mass of the total of the components (A) and (B), (C) Imidazole having a diaminotriazine ring: 0.05 to 5 parts by mass per 100 parts by mass of the total of the components (A) and (B). , and (D) Organic solvent: 100 to 800 parts by mass per 100 parts by mass of component (A) A primer comprising a thermosetting maleimide resin composition comprising: 【Chemistry 1】 (In formula (1), X 1 are independently expressed by the following formula: 【Chemistry 2】 and l is a number from 1 to 40. 【Transformation 3】 (In formula (2), X 2 are independently expressed by the following formula: 【Chemistry 4】 m is a number from 1 to 50, n is a number from 1 to 50, and A 1 and A 2 are each independently represented by the following formula (3) or the following formula (4): 【Transformation 5】 【Transformation 6】 (In formula (3) and formula (4), X 3 is expressed as follows: 【Transformation 7】 wherein A 1 and A 2 are different groups, and in formula (3), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms. is a group represented by the following formula:

2. 2. A primer comprising the thermosetting maleimide resin composition according to claim 1, wherein component (B) is an epoxy resin having a glycidyl group.

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