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

Abstract

To provide a curable 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, which is a curing temperature of regular polyimide, and can yield a cured product with outstanding adhesiveness to copper.SOLUTION: A curable 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) a reaction initiator; and (C) a diaminotriazine ring-containing imidazole.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable 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 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 a semiconductor device is operated at high temperatures, the semiconductor element, 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). In recent years, unplated copper has often been used as a lead frame material, and the invention described in Patent Document 7 proposes curing in a nitrogen atmosphere and using an organic peroxide with a low half-life temperature as a reaction initiator to ensure adhesion to copper. However, it has become clear that further improvement in adhesion is required for primers for semiconductor elements or lead frames.

[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 in substrates, and is said to have excellent adhesive strength to metals, but it has been found to have issues with long-term reliability. [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 curable maleimide resin composition that can be cured by light or at temperatures lower than 250°C, the curing temperature of ordinary polyimides, without using an aprotic polar solvent such as NMP, and that gives a cured product that has excellent adhesion, particularly to copper; an adhesive, a substrate material, a primer, and a chip coating agent that use the composition; and a semiconductor device that has a cured product of 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 curable maleimide resin composition can achieve the above object, and have thus completed the present invention.

[0011] That is, the present invention provides the following curable 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) a reaction initiator, and (C) Imidazole having a diaminotriazine ring 1. A curable 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 curable maleimide resin composition according to [1], wherein the blending amount of the component (B) is 0.05 to 10 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 component (A). [3] The curable maleimide resin composition according to [1] or [2], further comprising (D) an organic solvent. [4] An adhesive comprising the curable maleimide resin composition according to any one of [1] to [3]. [5] A primer comprising the curable maleimide resin composition according to any one of [1] to [3]. [6] A chip coating agent comprising the curable maleimide resin composition according to any one of [1] to [3]. [7] A semiconductor device comprising a cured product of the curable maleimide resin composition according to any one of [1] to [3]. [Effects of the Invention]

[0012] The curable maleimide resin composition of the present invention can be cured at low temperatures (e.g., temperatures below 250°C) without using an aprotic polar solvent such as NMP, and gives a cured product that has excellent adhesion, particularly to copper. Therefore, the curable 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) 1 Examples 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. 1From 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 although not particularly limited, 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 this specification 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 curable maleimide resin composition of the present invention (however, in the case where the curable maleimide resin composition contains an organic solvent (D) described below, the curable maleimide resin composition excluding the organic solvent (D)) preferably contains 70 to 99.9 mass %, more preferably 80 to 99.5 mass %, and even more preferably 85 to 99.0 mass % of component (A).

[0024] (B) Reaction initiator The reaction initiator, component (B), is added to initiate and promote the crosslinking reaction of the maleimide compound, component (A), and the reaction between the maleimide group in component (A) and a reactive group that can react with the maleimide group. Component (B) is not particularly limited as long as it promotes the crosslinking reaction, but a thermal radical polymerization initiator and / or a photopolymerization initiator, which are easily cured in a short time, are preferred to improve productivity. When a thermal radical polymerization initiator is used in component (B), the curable maleimide resin composition of the present invention cures at a relatively low temperature (for example, a temperature below 250°C). When a photopolymerization initiator is used in component (B), the curable maleimide resin composition cures by light irradiation. Note that component (B) does not include imidazole having a diaminotriazine ring (C), which will be described later.

[0025] Representative examples of the thermal radical polymerization initiator include organic peroxides, such as dicumyl peroxide, t-butyl peroxybenzoate, t-amyl peroxybenzoate, dibenzoyl peroxide, diuraloyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-di(t-butylperoxy)cyclohexane, di-t-butyl peroxide, dibenzoyl peroxide, and 1,6-bis(t-butylperoxycarbonyloxy)hexane.

[0026] The photopolymerization initiator is not particularly limited as long as it initiates a reaction by light. Examples of the photopolymerization initiator include aromatic ketones such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropanone-1,2,4-diethylthioxanthone, 2-ethylanthraquinone, and phenanthrenequinone; benzyl dimethyl ketal; Benzyl derivatives; 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-phenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole 2,4,5-triarylimidazole dimers such as 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer; acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; bisacylphosphine oxides such as bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. Examples of the side include alkylphenone compounds such as 1-hydroxy-cyclohexyl-phenyl-ketone and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide; and benzophenone compounds.

[0027] The reaction initiator is preferably blended in an amount of 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of component (A). When other thermosetting resins, as described below, are blended in the composition, the amount is preferably 0.05 to 10 parts by mass, particularly 0.1 to 5 parts by mass, per 100 parts by mass of the total of component (A) and other thermosetting resin components. Amounts outside the above range of 0.05 to 10 parts by mass per 100 parts by mass of component (A) are undesirable because curing may be very slow or fast during molding. Furthermore, the balance between heat resistance and moisture resistance of the resulting cured product may be poor. The reaction initiator may be used alone or in combination of two or more kinds.

[0028] (C) Imidazole having a diaminotriazine ring In the present invention, an imidazole having a diaminotriazine ring is further blended as component (C). The diaminotriazine ring is particularly effective in improving adhesion to metals such as copper. In addition, the presence of imidazole also promotes the polymerization of maleimide, making it effective in 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.). The blend 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 component (A). If the blend amount of component (C) is less than 0.05 parts by mass per 100 parts by mass of component (A), the adhesive strength improving effect cannot be obtained, while if it exceeds 5 parts by mass, poor dispersibility may result in poor appearance or reduced reliability.

[0030] (D) Organic solvent The composition of the present invention may further contain an organic solvent as component (D). There are no limitations on the type of organic solvent as long as it is capable of dissolving component (A), although N-methyl-2-pyrrolidone (NMP) is excluded from considerations of environmental impact. In this context, "component (D) can dissolve component (A)" means that when 25% by mass of component (A) is added to component (D), no residual component (A) is visually observed at 25°C. As component (D), for example, 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 for copper substrates, the organic solvent of component (D) is preferably cyclohexanone, xylene, anisole, or the like. From the viewpoint of the solubility of the above-mentioned component (A), organic solvents such as anisole, xylene, toluene, and cyclohexanone are preferred as the organic solvent for component (D). 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).

[0031] <Other additives> The curable maleimide resin composition of the present invention may contain various additives within the range that does not impair the effects of the present invention. 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, etc. may be added. Furthermore, to improve electrical properties, ion trapping agents, etc. may be added. Furthermore, to improve dielectric properties, fluorine-containing materials, etc. may be added. Inorganic fillers such as silica may be added to adjust the coefficient of thermal expansion (CTE).

[0032] The curable maleimide resin composition of the present invention can be produced by mixing the components (A), (B), (C), and (D) and other additives. The curable 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.

[0033] For example, after applying a curable maleimide resin composition containing components (A), (B), and (C), and further component (D), to a substrate, the organic solvent is removed by heating the composition at a temperature typically above 80°C, preferably above 100°C, for 0.5 to 5 hours. Furthermore, if the composition is a thermosetting type, a flat and strong maleimide coating can be formed by heating the substrate at a temperature above 130°C, preferably above 150°C, for 0.5 to 10 hours, or by irradiating the substrate with 365 nm UV light if the composition is a photocurable type. While polyimides generally require temperatures above 150°C for drying and above 220°C for thermal curing, the curable maleimide resin composition of the present invention does not require such high-temperature conditions. 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 stepwise, or heating may be performed after photocuring. 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] When an easily oxidizable metal such as copper is used as the substrate, the environment in which the curable maleimide resin composition or the epoxy resin molding material for semiconductor encapsulation is cured is preferably a nitrogen atmosphere to prevent oxidation. The curable maleimide resin composition of the present invention is also preferably cured in a nitrogen atmosphere, but the adhesive strength can be improved to a certain level even when cured in an oxygen atmosphere. [Example]

[0038] 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.

[0039] 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)

[0040] (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)

[0041] [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)

[0042] 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 (BMI-1000, Mn: 410, manufactured by Daiwa Chemical Industry Co., Ltd.) (Number of aromatic atoms / Number of constituent atoms≒0.44)

[0043] (B) Reaction initiator (B-1): Dicumyl peroxide (trade name: Perkadox BC-FF, manufactured by Kayaku Nouryon Co., Ltd.) (B-2): 1,6-bis(t-butylperoxycarbonyloxy)hexane (trade name: Kayalene 6-70, manufactured by Kayaku Nouryon Co., Ltd., 1-hour half-life temperature 117°C)

[0044] (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) (C-3) Silane coupling agent having a diaminotriazine skeleton (product name: VD-5, Shikoku Chemicals Corporation, for comparative example)

[0045] Comparative polyimide Polyamic acid varnish (KJR-655, manufactured by Shin-Etsu Chemical Co., Ltd., NMP-based varnish, non-volatile content 15% by mass) was used as is.

[0046] (Composition Examples 1 to 12, Examples 1 to 6, Comparative Examples 1 to 14) A varnish of a curable maleimide resin composition was prepared by mixing the components according to the formulation shown in Table 1. In all formulations, anisole was added so that component (A) was 16.7 mass % and all of component (A) was dissolved.

[0047] <Adhesion> (Adhesion test before moisture absorption) The varnishes of the compositions obtained in Formulation Examples 1 to 12 were spray-coated onto a 20 mm x 20 mm copper frame substrate and cured under the curing conditions shown in Table 2 or 3 to form cured films (primers). On the cured film, a semiconductor encapsulation epoxy resin molding material KMC-2284 (Shin-Etsu Chemical Co., Ltd.) was applied to a substrate with a base area of ​​10 mm 2 The test pieces were then cured for 120 seconds at a pressure of 6.9 MPa and a temperature of 175°C into a 3 mm high cylindrical shape. The test pieces were then post-cured at 180°C for 4 hours, and the adhesive strength before moisture absorption was measured at 25°C using a universal bond tester (DAGE SERIES 4000, manufactured by Nordson DAGE) at a speed of 0.2 mm / s.

[0048] <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).

[0049] <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).

[0050] The results of these measurements are shown in Tables 2 and 3. The detailed conditions for curing conditions A to C are as follows: Curing condition A: 110℃ 30 minutes + 180℃ 2 hours Curing condition B: 110℃ 30 minutes + 130℃ 2 hours Curing condition C: 150°C 1 hour + 200°C 1 hour + 250°C 4 hours In Comparative Example 1, the adhesive strength was measured without using a primer (varnish of the composition), and therefore the columns for curing conditions and curing atmosphere are not shown. [Table 1] [Table 2] [Table 3]

[0051] From the above, it was found that the composition of the present invention had higher adhesive strength to copper than the comparative examples, regardless of the curing atmosphere, whether initially, after moisture absorption, or after heat treatment, and was therefore excellent in adhesiveness. Furthermore, the composition of the present invention also had superior stability over time as a varnish compared to the comparative compositions. Therefore, the composition of the present invention can be suitably used as a primer, particularly as a primer for copper substrates or as a primer used between a semiconductor encapsulant and a lead frame.

Claims

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) a reaction initiator, and (C) Imidazole having a diaminotriazine ring 1. A curable 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】 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. The curable maleimide resin composition according to claim 1, wherein the blending amount of the component (B) is 0.05 to 10 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 component (A).

3. The curable maleimide resin composition according to claim 1 , further comprising (D) an organic solvent.

4. An adhesive comprising the curable maleimide resin composition according to any one of claims 1 to 3.

5. A primer comprising the curable maleimide resin composition according to any one of claims 1 to 3.

6. A chip coating agent comprising the curable maleimide resin composition according to any one of claims 1 to 3.

7. A semiconductor device comprising a cured product of the curable maleimide resin composition according to any one of claims 1 to 3.

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