Phenolic resin mixture, curable resin composition, and cured product thereof

Abstract

A phenolic resin mixture containing a phenolic resin (A) represented by the following formula (1) or (2) and a crystalline alkyl-substituted biphenolic compound (B) having a melting point of 70 °C to 300 °C, in which a weight ratio of the component (A) to the component (B) is 95 / 5 to 85 / 15. (In formula (1), plural R1 and p are independent of each other, R1 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxy group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, or an amino group, or a phenyl group that may have the same substituent as described above, and p represents a real number of 0 to 3. n is a repetition number, and is a real number of 1 to 20.) (In formula (2), plural R1 and p are independent of each other, R1 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxy group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, or an amino group, or a phenyl group that may have the same substituent as described above, and p represents a real number of 0 to 3. n is a repetition number, and is a real number of 1 to 20.)

Description

Phenolic resin mixture, curable resin composition and cured product thereof

[0001] The present invention relates to a phenolic resin mixture, a curable resin composition, and a cured product thereof.

[0002] In the field of semiconductor encapsulation, phenolic resins are used as curing agents for epoxy resins. In recent years, with the development of these resins, there has been a demand for further improvements in various properties, including higher purity resin compositions, moisture resistance, adhesion, dielectric properties, lower viscosity for higher filler (inorganic or organic filler) loading, and increased reactivity for shorter molding cycles.

[0003] Furthermore, as semiconductor packages continue to evolve in shape, becoming thinner, stacked, systemized, and three-dimensional, they are becoming more complex, and as the wire wiring becomes increasingly narrower and thinner, poor fluidity of the resin composition can lead to wire sweep.Furthermore, this places a strain on the wire connections, which can have adverse effects.

[0004] Furthermore, for flip-chip type packages, a technique called mold underfill (hereinafter referred to as "MUF") has been attracting attention as a low-cost manufacturing method, in which the resin is sealed in one go without using underfill. In this method, miniaturization of the filler is important because the resin needs to pass through the very narrow gap between the chip and the package substrate. However, miniaturization of the filler increases the surface area, which increases the viscosity of the system and causes voids (air gaps).

[0005] Furthermore, sealing resins used in rewiring layers such as wafer-level packages, and interlayer insulating films used in build-up layers, need to be thin, and in order to reduce the linear expansion coefficient, they need to be filled with fine fillers, so there is also a demand for resin compositions with low viscosity.

[0006] "2008 STRJ Report, Semiconductor Roadmap Special Committee, FY2008 Report," Chapter 8, p. 1-1, [online], March 2009, JEITA (Japan Electronics and Information Technology Industries Association), Semiconductor Technology Roadmap Special Committee, [Retrieved May 30, 2012].<http: / / strj-jeita.elisasp.net / strj / nenjihoukoku-2008.cfm> Nobuyuki Takakura et al., Matsushita Electric Industrial Technical Report, Automotive Device Technology, High Temperature Operation IC for Automotive Use, No. 74, Japan, May 31, 2001, pp. 35-40

[0007] Japanese Patent Publication No. 2003-41096 Japanese Patent Publication No. 2013-87137

[0008] There are various methods for reducing viscosity, but a common method is to reduce the molecular weight of the epoxy resin or phenol resin. However, when the molecular weight of an epoxy resin or phenol resin is reduced, the resin tends to have fluidity at room temperature (which in this application refers to, for example, 20°C), making it difficult to handle at room temperature (from liquid to syrup to semi-solid, etc.), and furthermore, when made into a resin composition, it becomes sticky, making storage and handling difficult.

[0009] Specifically, materials must be transported frozen when delivered from resin manufacturers to composition manufacturers, resulting in a large amount of energy consumption. Furthermore, the temperature rise during transport causes blocking (forming clumps), making the material unmanageable. Even if there are no problems during the transportation process, the material must be returned to room temperature before use at the composition manufacturer. This can lead to problems such as condensation during this process, blocking when returned to room temperature, and clogging at the entrance of the hopper during charging. Furthermore, even if attempts are made to grind the resin composition homogeneously using a ball mill or the like, grinding is not possible, and the material solidifies in the kettle, causing damage to the equipment. Similar problems also occur with the finished composition.

[0010] To address these issues, the use of crystalline epoxy resins has been considered (see Patent Document 1). However, there are issues such as limitations on the reduction in fluidity during molding, and difficulty in maintaining handling characteristics due to the breakdown of crystallinity after composition when mixed with phenolic resin. Furthermore, when using crystalline epoxy resins, the epoxy resin must be melted and mixed in a kneader at temperatures above the melting point of the crystalline epoxy resin; otherwise, the epoxy resin will not melt sufficiently and will not disperse uniformly. As a result, molded articles made from epoxy resin molding materials using this molten mixture will be non-uniform, resulting in varying strength at different locations and reduced semiconductor device performance. However, if the temperature of the molten mixture is too high during melt mixing, the curing reaction may proceed in the kneader, resulting in reduced fluidity and the formation of gelled materials that can cause incomplete filling during molding. Furthermore, due to the high crystallinity, recrystallization occurs, resulting in residual crystallinity even after heat mixing. These residual crystals only melt during molding, potentially resulting in poor moldability, such as poor curability, the formation of flash and voids, and the tendency for stains to form on the surface of the resulting semiconductor device.

[0011] On the other hand, there have been attempts to introduce crystallinity into phenolic resins, but due to their high crystallinity, localized crystallization occurs, making it difficult to obtain a homogeneous resin composition. In response to this, Patent Document 2 discloses that, in order to solve the problem of residual phenolic compounds when used, a molten quaternary phosphonium compound is used as a solvent, and the crystalline phenolic compound is completely dissolved in the solvent, thereby obtaining a molten mixture with excellent storage stability and no residual phenolic compounds. However, since this involves heating and melting at approximately 100°C, there is a possibility that a stable, homogeneous resin composition will not be obtained upon cooling to room temperature.

[0012] In view of the above-mentioned circumstances, the present inventors have conducted extensive research and have discovered a phenolic resin mixture that is semicrystalline at 20°C and has both flowability and handleability, thereby completing the present invention.

[0013] That is, the present invention relates to the following [1] to [5]: [1] A phenolic resin mixture containing a phenolic resin (A) represented by the following formula (1) or (2) and a crystalline alkyl-substituted biphenol compound (B) having a melting point of 70 to 300°C, wherein the weight ratio of component (A) to component (B) is 95 / 5 to 85 / 15.

[0014]

[0015] (In formula (1), there are multiple R １ , p each independently exist, R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, an amino group, or a phenyl group which may have the same substituents as those described above, and p is a real number from 0 to 3. n is the number of repetitions and is a real number from 1 to 20.

[0016]

[0017] (In formula (2), there are multiple R １ , p each independently exist, R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, an amino group, or a phenyl group which may have the same substituents as those described above, and p is a real number from 0 to 3. n is the number of repetitions and is a real number from 1 to 20.) [2] The phenolic resin mixture according to the above item [1], which is semicrystalline at 20°C and has a hydroxyl group equivalent of 130 to 200 g / eq. [3] The phenolic resin mixture according to the above item [1] or [2], which has an ICI melt viscosity (cone and plate method) at 150°C of 0.001 to 0.20 Pa s. [4] A curable resin composition containing the phenolic resin mixture according to any one of the above items [1] to [3] and an epoxy resin. [5] A cured product obtained by curing the curable resin composition according to the above item [4].

[0018] The phenolic resin mixture of the present invention has very high fluidity and excellent handling properties, which contributes to productivity and is useful for insulating materials for electric and electronic components, various composite materials including laminates (printed wiring boards, build-up boards, etc.), and carbon fiber reinforced composite materials (hereinafter also referred to as "CFRP"), adhesives, paints, etc. It is particularly useful as a semiconductor encapsulation material for protecting semiconductor elements.

[0019] The phenolic resin mixture of the present invention contains a phenolic resin represented by the following formula (1) or (2) (hereinafter also referred to as component (A)) and a crystalline alkyl-substituted biphenol compound (B) (hereinafter also referred to as component (B)) having a melting point of 70 to 300°C.

[0020]

[0021] (In formula (1), there are multiple R １ , p each independently exist, R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, an amino group, or a phenyl group which may have the same substituents as those described above, and p is a real number from 0 to 3. n is the number of repetitions and is a real number from 1 to 20.

[0022]

[0023] (In formula (2), there are multiple R １ , p each independently exist, R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, an amino group, or a phenyl group which may have the same substituents as those described above, and p is a real number from 0 to 3. n is the number of repetitions and is a real number from 1 to 20.

[0024] R in the formula (1) and formula (2) １ is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom. p is preferably a real number of 0 or 1, and particularly preferably 0.

[0025] The value of n in the formula (1) and formula (2) can be calculated from the number average molecular weight determined by measuring the phenolic resin by gel permeation chromatography (GPC, detector: RI) or from the area ratio of each separated peak.

[0026] The value of n in the formulas (1) and (2) is usually 1 to 20, preferably 1.1 to 20, and more preferably 1.1 to 10. When n is less than 1, the crystallinity is so high that a homogeneous resin mixture cannot be obtained even by mechanical kneading. On the other hand, when n is greater than 20, the melt viscosity is high, making it difficult to use from the viewpoints of flowability and high filler loading.

[0027] The phenolic resins represented by the formulas (1) and (2) can be synthesized by publicly known synthesis methods, but are also readily available commercially. For example, the phenolic resin represented by the formula (1) is available as KAYAHARD GPH-65 (manufactured by Nippon Kayaku Co., Ltd., softening point 65°C), and the phenolic resin represented by the formula (2) is available as MEHC-7840-4S (manufactured by Meiwa Kasei Co., Ltd., softening point 58-65°C).

[0028] Component (B) is a biphenol compound with improved compatibility with component (A) due to the introduction of an alkyl group. The crystalline phenolic compound is semi-melted and mixed uniformly with component (A) while maintaining a certain degree of crystallinity, resulting in a semi-crystalline phenolic resin mixture. In this application, "semi-crystalline" refers to a state in which the resin is cloudy and opaque, with microcrystals uniformly dispersed throughout the resin. In this application, the crystalline alkyl-substituted phenolic resin is not completely melted, but is dispersed while maintaining its crystalline state to form a homogeneous semi-crystalline resin composition. This homogeneous semi-crystalline resin composition is then used as an organic filler, achieving both good fluidity and handling properties for the phenolic resin mixture. In other words, it can be used as a phenolic resin mixture with component (A) containing component (B) as an organic filler as a matrix.

[0029] Therefore, in the present invention, it is important to knead the component (B) at a temperature below its melting point to ensure uniform dispersion in the resin matrix. Whether the phenolic resin mixture maintains its crystalline state and is uniformly dispersed after kneading can be determined by visually inspecting the appearance of the prepared phenolic resin mixture. For example, if the mixture contains non-uniform resin and crystalline clumps, the biphenol compound is not uniformly dispersed. If the mixture simply appears as an opaque resin plate, it can be determined that the biphenol compound is uniformly dispersed.

[0030] The melting point of component (B) is usually 70 to 300°C, preferably 100 to 250°C. If it is lower than 70°C, it will completely melt due to the heat during kneading, making it difficult to maintain crystallinity. If it is higher than 300°C, the crystals will not melt and disperse uniformly during curing and molding, making it difficult to produce a homogeneous cured product from this molding material. The melting point can be determined, for example, from the endothermic peak temperature using a commercially available differential scanning calorimeter (DSC).

[0031] To improve flowability, the molecular weight of component (B) is preferably small, and is preferably 190 to 400, more preferably 210 to 350, and particularly preferably 240 to 300. The hydroxyl equivalent of component (B) is preferably 95 to 200 g / eq., more preferably 105 to 175 g / eq., and particularly preferably 120 to 150 g / eq.

[0032] Furthermore, in component (B), the number of substituted alkyl groups is preferably 2 to 6. From the viewpoint of crystallinity, the number of substituted alkyl groups is preferably an even number such as 2, 4, or 6. The substituted alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, phenyl, or allyl. Specific examples include dimethylbiphenol, tetramethylbiphenol, diallylbiphenol, diethylbiphenol, tetraethylbiphenol, and diphenylbiphenol. In the present invention, when the substituted alkyl group is a methyl or ethyl group, a 4- to 6-substituted biphenol compound is preferred, and when the substituted alkyl group is a phenyl or allyl group, a 2-substituted biphenol compound is preferred. Di-substituted alkyl groups such as methyl or ethyl groups, which have small alkyl groups, are highly reactive, and therefore, even when the molecular weight is small and the initial viscosity is low, the reactivity may be high, resulting in a decrease in fluidity. On the other hand, large substituents such as phenyl or allyl groups have a significant effect, while tetra-substituted alkyl groups may actually make the reaction more difficult. The total number of carbon atoms in the substituents is preferably 2 to 12, and more preferably 4 to 10.

[0033] The component (B) used in the present invention may be a commercially available product or may be produced by a known method. Specific examples of commercially available compounds include, but are not limited to, 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl (manufactured by Tokyo Chemical Industry Co., Ltd., melting point 223-225°C, molecular weight 242.32, total number of carbon atoms in the substituents: 4), 3,3'-dimethyl-4,4'-biphenol (manufactured by Songwon International Japan Co., Ltd., melting point 162°C, molecular weight 214.26, total number of carbon atoms in the substituents: 2), 4,4'-dihydroxy-3,3'-diphenyldiphenyl (manufactured by Sanko Kagaku Co., Ltd., melting point 147.7°C, molecular weight 338.41, total number of carbon atoms in the substituents: 12), and 3,3'-diallylbiphenyl-4,4'-diol (manufactured by Mitsui Fine Chemicals, Inc., melting point 76°C, molecular weight 266.34, total number of carbon atoms in the substituents: 6).

[0034] The phenolic resin mixture of the present invention is obtained by uniformly mixing component (A) and component (B). However, it is preferable to mix at a temperature below the melting point of component (B) and knead to disperse the crystals. Specifically, it is preferable to knead at a temperature below the melting point of a crystalline alkyl-substituted biphenyl compound and use it as an organic filler. If the crystals are not uniformly dispersed, the ratio of the blended components (A) and (B) will change, resulting in partial curing failure, which is undesirable. Specifically, it is preferable to knead at a temperature below 100°C. If the temperature exceeds 100°C, aggregation of the crystalline phenolic resin will progress during the cooling process to room temperature, preventing uniform dispersion of the crystals. Furthermore, if the phenolic resin mixture is heated and melted, it will become sticky, making it difficult to remove. It may also cause blocking during the production process, causing the components to stick together, making accurate weight measurement difficult, and even making it difficult to charge the mixture into the charging port, which may result in productivity problems. Therefore, in the present invention, kneading and mixing at a temperature below the melting point is preferable.

[0035] The resulting mixture in tablet, powder, sheet or granular form is characterized by not being sticky even when stored at 20° C. In the kneading and mixing, the phenolic resin mixture can be obtained by thorough mixing using an extruder, kneader, roll or the like.

[0036] The phenolic resin mixture of the present invention typically has a weight ratio of component (A) to component (B) of 95 / 5 to 85 / 15, preferably 90 / 10 to 85 / 15. If the weight ratio of component (A) is greater than 95, the fluidity is poor. On the other hand, if the weight ratio of component (A) is less than 85, a portion of the phenolic resin mixture will crystallize non-uniformly at 20°C. That is, by having a weight ratio of component (A) to component (B) of 95 / 5 to 85 / 15, the mixture has fluidity at high temperatures and becomes a non-sticky, uniform semi-crystalline state at 20°C, thereby achieving both fluidity and ease of handling.

[0037] The hydroxyl equivalent of the phenolic resin mixture of the present invention is preferably 130 to 200 g / eq, more preferably 163 to 200 g / eq, and particularly preferably 186 to 200 g / eq. If the hydroxyl equivalent is less than 130 g / eq, the large amount of functional groups contained therein may cause the curing rate to be too fast and sufficient fluidity may not be obtained. On the other hand, if the hydroxyl equivalent is greater than 200 g / eq, curability may be poor and sufficient hardness may not be obtained.

[0038] In the present invention, the ICI melt viscosity (cone and plate method) at 150°C is preferably 0.001 to 0.20 Pa·s, more preferably 0.005 to 0.15 Pa·s, and particularly preferably 0.01 to 0.1 Pa·s. If the ICI melt viscosity is lower than 0.001 Pa·s, the melt viscosity is too low, making it difficult to maintain the filler in a dispersed state, and if it is higher than 0.20 Pa·s, it is not possible to fill a sufficient amount of filler, resulting in a high shrinkage rate of the encapsulant.

[0039] The curable resin composition of the present invention contains an epoxy resin. Specific examples of the epoxy resin that can be used include novolac epoxy resins, bisphenol A epoxy resins, biphenyl epoxy resins, triphenylmethane epoxy resins, and phenol aralkyl epoxy resins. Specifically, bisphenol A, bisphenol S, thiodiphenol, fluorene bisphenol, terpene diphenol, 4,4'-biphenol, 2,2'-biphenol, 3,3',5,5'-tetramethyl-[1,1'-biphenyl]-4,4'-diol, hydroquinone, resorcinol, naphthalenediol, tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenols (phenol, alkyl-substituted phenol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, dihydroxynaphthalene, etc.), formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, o-hydroxybenzaldehyde, p-hydroxyacetophenone, o-hydroxyacetophenone, dicyclopentadiene, methyl ... Examples of suitable epoxy resins include, but are not limited to, solid or liquid epoxy resins such as polycondensates of tetrabromobisphenol A, ...

[0040] The curable resin composition of the present invention may contain an inorganic filler. Examples of inorganic fillers include, but are not limited to, powders such as crystalline silica, fused silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride, boron nitride, zirconia, fosterite, steatite, spinel, titania, and talc, as well as spherical beads of these fillers. These fillers may be used alone or in combination of two or more. In the present invention, when intended for use in semiconductor encapsulation, crystalline silica, fused silica, and alumina are preferred from the perspective of balance of properties. The content of these inorganic fillers is preferably 70 to 96% by mass relative to 100% by mass of the curable resin composition of the present invention. 70 to 93% by mass is particularly preferred. Because the present invention has particularly high fluidity, if the inorganic filler is too small, the balance between the inorganic filler and the resin will be off, resulting in areas with high and low inorganic filler content in the molded resin composition, which is undesirable in terms of properties. Furthermore, if the inorganic filler content exceeds 96%, fluidity will be impaired and this is undesirable.

[0041] In the curable resin composition of the present invention, the phenolic resin mixture acts as a curing agent for the epoxy resin. In the present invention, the phenolic resin mixture of the present invention may be used in combination with other curing agents as the curing agent. Examples of other curing agents that can be used include phenolic compounds other than the phenolic resin of the present invention, amine compounds, acid anhydride compounds, amide compounds, and carboxylic acid compounds. Examples of phenolic resins and phenolic compounds include bisphenol A, bisphenol F, 3,3'-dimethyl-4,4'-bisphenol A, 3,3'-dimethyl-4,4'-bisphenol F, 3,3',5,5'-tetramethyl-4,4'-bisphenol A, 3,3',5,5'-tetramethyl-4,4'-bisphenol F, bisphenol S, fluorene bisphenol, terpene diphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, naphthalenediol, tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenols (phenol, alkyl-substituted phenol, naphthol, alkyl-substituted naphthol), Examples of the polyphenol include, but are not limited to, polycondensates of 4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, 1,4'-bis(chloromethyl)benzene, 1,4'-bis(methoxymethyl)benzene, and the like with 4,4'-bis(chloromethyl)-1,1'-biphenyl, dihydroxybenzene, dihydroxynaphthalene, and the like, and formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, o-hydroxybenzaldehyde, p-hydroxyacetophenone, o-hydroxyacetophenone, dicyclopentadiene, furfural, 4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, 1,4'-bis(chloromethyl)benzene, 1,4'-bis(methoxymethyl)benzene, and the like, and modified products thereof, halogenated bisphenols such as tetrabromobisphenol A, and polyphenols such as condensates of terpenes and phenols. These may be used alone, or two or more types may be used.Preferred phenol resins include phenol aralkyl resins (resins having an aromatic alkylene structure), and particularly preferred are resins characterized in that the structure has at least one selected from phenol, naphthol, and cresol, and the alkylene portion serving as a linker is at least one selected from a benzene structure, a biphenyl structure, and a naphthalene structure (specific examples include Xylok, naphthol Xylok, phenol biphenylene novolac resin, cresol-biphenylene novolac resin, and phenol-naphthalene novolac resin).

[0042] Examples of amine compounds and amide compounds include nitrogen-containing compounds such as diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, and polyamide resins synthesized from a dimer of linolenic acid and ethylenediamine. Examples of acid anhydride compounds and carboxylic acid compounds include acid anhydrides such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, butanetetracarboxylic anhydride, bicyclo[2,2,1]heptane-2,3-dicarboxylic anhydride, methylbicyclo[2,2,1]heptane-2,3-dicarboxylic anhydride, and cyclohexane-1,3,4-tricarboxylic-3,4-anhydride; and carboxylic acid resins obtained by the addition reaction of various alcohols, carbinol-modified silicones, and the aforementioned acid anhydrides. Other examples include imidazole, trifluoroborane-amine complexes, and guanidine derivative compounds. The other curing agents mentioned above are not limited to these. These may be used alone or in combination of two or more. In the present invention, the use of phenolic compounds is preferred, particularly from the standpoint of reliability.

[0043] In the curable resin composition of the present invention, the amount of epoxy resin and curing agent used is preferably 0.7 to 1.2 equivalents relative to 1 equivalent of epoxy groups in the total epoxy resin. If the amount is less than 0.7 equivalents or more than 1.2 equivalents relative to 1 equivalent of epoxy groups, curing may be incomplete and good cured physical properties may not be obtained.

[0044] The curable resin composition of the present invention may further contain a curing accelerator. Specific examples of curing accelerators that can be used include imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole; tertiary amines such as 2-(dimethylaminomethyl)phenol and 1,8-diaza-bicyclo(5,4,0)undecene-7; phosphines such as triphenylphosphine; quaternary ammonium salts such as tetrabutylammonium salt, triisopropylmethylammonium salt, trimethyldecanylammonium salt, and cetyltrimethylammonium salt; and quaternary phosphonium salts such as triphenylbenzylphosphonium salt, triphenylethylphosphonium salt, and tetrabutylphosphonium salt. The counter ion of the quaternary salt may be a halogen, an organic acid ion, or a hydroxide ion; although there is no particular restriction, organic acid ions and hydroxide ions are particularly preferred. Metal compounds such as tin octoate are also included. The curing accelerator is used in an amount of 0.01 to 5.0 parts by mass per 100 parts by mass of the epoxy resin, if necessary.

[0045] Furthermore, the curable resin composition of the present invention may contain various additives such as a silane coupling agent, a release agent such as stearic acid, palmitic acid, zinc stearate, or calcium stearate, a surfactant, a dye, a pigment, or an ultraviolet absorber, and various thermosetting resins.

[0046] Furthermore, a binder resin can be blended into the curable resin composition of the present invention as needed. Examples of binder resins include, but are not limited to, butyral resins, acetal resins, acrylic resins, epoxy-nylon resins, NBR-phenol resins, epoxy-NBR resins, polyamide resins, polyimide resins, and silicone resins. The amount of binder resin blended is preferably within a range that does not impair the flame retardancy and heat resistance of the cured product, and is typically 0.05 to 50 parts by mass, preferably 0.05 to 20 parts by mass, per 100 parts by mass of the resin component, as needed.

[0047] The curable resin composition of the present invention may contain a known maleimide compound as needed. Specific examples of usable maleimide compounds include 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene, and biphenylaralkyl maleimide, but are not limited to these. These compounds may be used alone or in combination of two or more. When a maleimide compound is blended, a curing accelerator is blended as necessary. The above-mentioned curing accelerators, as well as radical polymerization initiators such as organic peroxides and azo compounds can be used.

[0048] The curable resin composition of the present invention can be obtained by uniformly mixing the above components in a predetermined ratio, and is usually pre-cured at 130 to 180°C for 30 to 500 seconds, and then post-cured at 150 to 200°C for 2 to 15 hours, thereby allowing the curing reaction to proceed sufficiently and producing the cured product of the present invention. Alternatively, the components of the curable resin composition can be uniformly dispersed or dissolved in a solvent or the like, and then cured after removing the solvent.

[0049] The curable resin composition of the present invention thus obtained has moisture resistance, heat resistance, high adhesion, low dielectric constant, and low dielectric dissipation factor. Therefore, the curable resin composition of the present invention can be used in a wide range of fields requiring moisture resistance, heat resistance, high adhesion, low dielectric constant, and low dielectric dissipation factor. Specifically, the curable resin composition of the present invention is useful as a material for all electrical and electronic components, such as insulating materials, laminates (printed wiring boards, BGA substrates, build-up substrates, etc.), encapsulating materials, and resists. It can also be used in molding materials, composite materials, paint materials, adhesives, 3D printing, and other fields. In particular, solder reflow resistance is beneficial in semiconductor encapsulation.

[0050] The semiconductor device includes one encapsulated with the curable resin composition of the present invention, and examples of the semiconductor device include a DIP (dual in-line package), a QFP (quad flat package), a BGA (ball grid array), a CSP (chip size package), a SOP (small outline package), a TSOP (thin small outline package), and a TQFP (thin quad flat package).

[0051] The method for preparing the curable resin composition of the present invention is not particularly limited, but may be prepared by dispersing or dissolving each component in a solvent or the like, mixing them uniformly, and optionally removing the solvent by distillation, or by forming a prepolymer. For example, the phenolic resin mixture of the present invention may be prepolymerized by adding a curing agent such as an amine compound, a maleimide compound, a cyanate ester compound, a phenolic resin, or an acid anhydride compound, and other additives, by heating in the presence or absence of a solvent. The components may be mixed or prepolymerized using, for example, an extruder, kneader, or rolls in the absence of a solvent, or using a reaction vessel equipped with a stirrer in the presence of a solvent.

[0052] A method for uniformly mixing without using a solvent or the like involves kneading the components using a device such as a kneader, roll, or planetary mixer at a temperature within the range of 50 to 100°C to obtain a uniform curable resin composition. The resulting curable resin composition can be pulverized and then molded into cylindrical tablets using a molding machine such as a tablet machine, or into granular powder or powder-like molded bodies. Alternatively, these compositions can be melted on a surface support and molded into sheets with a thickness of 0.05 mm to 10 mm to obtain molded curable resin compositions. The resulting molded bodies are non-sticky at 0 to 20°C, and their fluidity and curability are hardly reduced even when stored at -25 to 0°C for one week or more. The resulting molded bodies can be molded into cured products using a transfer molding machine or compression molding machine.

[0053] An organic solvent can also be added to the curable resin composition of the present invention to form a varnish-like composition (hereinafter simply referred to as varnish). The curable resin composition of the present invention can be dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone, as needed, to form a varnish. This varnish can then be impregnated into a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper, and heated and dried to obtain a prepreg. This prepreg can then be hot-press molded to form a cured product of the curable resin composition of the present invention. The solvent used in this process typically accounts for 10 to 70 wt %, preferably 15 to 70 wt %, of the mixture of the curable resin composition of the present invention and the solvent. If the amount of solvent is less than this range, the viscosity of the varnish increases, resulting in poor workability, while if the amount of solvent is too high, it can cause voids to form in the cured product. Furthermore, if the composition is in liquid form, a cured curable resin containing carbon fiber can be obtained directly, for example, by the RTM method.

[0054] The cured product of the present invention can be used in a variety of applications. Examples include adhesives, paints, coatings, molding materials (including sheets, films, FRP, etc.), insulating materials (including printed circuit boards, wire coatings, etc.), sealants, and additives for other resins. Examples of adhesives include adhesives for civil engineering, construction, automotive, general office, and medical applications, as well as adhesives for electronic materials. Examples of adhesives for electronic materials include interlayer adhesives for multilayer substrates such as build-up substrates, die bonding agents, semiconductor adhesives such as underfills, BGA reinforcing underfills, and mounting adhesives such as anisotropic conductive films (ACFs) and anisotropic conductive pastes (ACPs). In particular, in the present invention, the composition is primarily used as a semiconductor sealant, but it can also be used in a technique in which the composition is used as a substrate or as a mold underfill (MUF).

[0055] Specifically, the main applications of currently used sealants include potting, dipping, and transfer mold sealing for capacitors, transistors, diodes, light-emitting diodes, ICs, LSIs, etc., and sealing (including reinforcing underfill) when mounting IC packages such as QFP, BGA, and CSP.

[0056] Next, the present invention will be explained in more detail with reference to examples. In the following, parts are by mass unless otherwise specified. However, the present invention is not limited to these examples. Various analytical methods used in the examples are described below. ICI melt viscosity: Based on JIS K 7117-2 (ISO 3219)

[0057] Examples 1 to 4, Comparative Examples 1 to 3 Kayahard GPH-65 (phenolic resin represented by formula (1) above, manufactured by Nippon Kayaku Co., Ltd., melting point 65°C), MEHC-7840-4S (phenolic resin represented by formula (2) above, manufactured by Meiwa Kasei Co., Ltd., melting point 58-65°C), and 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl (abbreviated as TMBP, manufactured by Tokyo Chemical Industry Co., Ltd., melting point 223-225°C, molecular weight 242.32, total number of carbon atoms in substituents 4) were kneaded and mixed in the proportions shown in Table 1 using a mixing roll at 80°C for 15 minutes to prepare a phenolic resin mixture.

[0058] [Appearance Observation] The appearance of the obtained phenolic resin mixture was visually observed at room temperature (20° C.) The appearance was evaluated as ◯ when there were no crystal agglomerates, i.e., when component (B) was uniformly dispersed while maintaining its crystalline state, and × when there were crystal agglomerates.

[0059] [Sticky Feeling] The sticky feeling on the surface of the obtained tablet was evaluated. The evaluation method was to press a finger against the obtained tablet for 10 seconds to evaluate the stickiness of the coating film. ○: The surface is smooth and not sticky. △: Sticky, but does not stick to the finger. ×: Very sticky, sticks to the finger.

[0060]

[0061] [Examples 5 and 6, Comparative Example 4] [Spiral flow test] Epoxy resin, phenolic resin mixture (Examples 3 and 4 and Comparative Example 3), silica filler, and curing accelerator were kneaded and mixed in the proportions shown in Table 2 using a mixing roll at 80°C for 25 minutes. Subsequently, a spiral flow test was carried out using an Archimedes spiral mold and a transfer molding machine under the following conditions: Mold: conforming to EMMI-1-66 Mold temperature: 175°C Transfer pressure: 70 kgf / cm ２ Press: 5t press, pot diameter: 30mm, injection time: 1 second, molding time: 120 seconds

[0062] [Gel Time] An appropriate amount of the curable resin composition shown in Table 2 was placed on a hot plate at 175°C with a metal spatula, and stirred with the metal spatula. The time when the sample lost its stickiness and could be peeled off from the hot plate or the time when the stickiness disappeared was measured.

[0063] In the spiral flow test, a higher value indicates better fluidity. Gel time is the time it takes for the sealing material to lose its fluidity when heated at a constant temperature, and can be selected appropriately in relation to the curing characteristics.

[0064]

[0065] NC-3000: biphenylaralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 277 g / eq) MSR-2102: high-purity spherical silica filler (manufactured by Tatsumori Co., Ltd.) TPP: triphenylphosphine (manufactured by Junsei Chemical Co., Ltd.)

[0066] From Tables 1 and 2, it was confirmed that the phenolic resin mixture of the present invention has excellent handling properties and flowability.

[0067] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2021-048212) filed on March 23, 2021, the entire contents of which are incorporated by reference. All references cited herein are incorporated in their entirety.

[0068] From the above, it can be seen that the phenolic resin mixture of the present invention has high fluidity and handleability, and is also excellent in productivity and moldability. Therefore, the curable resin composition of the present invention is useful for various composite materials, adhesives, paints, etc., including insulating materials for electric and electronic components, laminates (printed wiring boards, build-up boards, etc.), and carbon fiber reinforced composite materials (hereinafter also referred to as "CFRP"). In particular, it is useful as a semiconductor encapsulation material for protecting semiconductor elements.

Claims

1. A phenolic resin mixture containing a phenolic resin (A) represented by the following formula (1) or the following formula (2) and a crystalline alkyl-substituted biphenyl compound (B) having a melting point of 70 to 300 °C, wherein the weight ratio of component (A) to component (B) is 95 / 5 to 85 / 15. (In formula (2), when there are a plurality of R １ , p each independently exists, and R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, a methoxy group, an ethoxy group, a nitro group, a nitrile group, an amino group, or a phenyl group which may have a substituent similar to the foregoing, and p is a real number of 0 to 3. n is the number of repetitions and is a real number of 1 to 20.) 2. The phenolic resin mixture according to claim 1, which shows a semi-crystalline state at 20 °C and has a hydroxyl equivalent of 130 to 200 g / eq.

3. The phenolic resin mixture according to claim 1 or 2, having an ICI melt viscosity (cone plate method) at 150 °C of 0.001 to 0.20 Pa·s.

4. A curable resin composition containing the phenolic resin mixture according to any one of claims 1 to 3 and an epoxy resin.

5. A cured product obtained by curing the curable resin composition according to claim 4.