Epoxy resin curing agent, epoxy resin composition, semiconductor sealing material, semiconductor package, cured product, and electronic device

Abstract

Provided is an epoxy resin curing agent that satisfies <Condition 1>. <Condition 1> When an epoxy resin composition, containing 10 parts by mass of a BisA type epoxy resin, 9 parts by mass of methylnadic anhydride, 30 parts by mass of spherical silica having a particle diameter (D50) of 0.6 µm at a cumulative volume of 50% in a volume-based particle size distribution, and 1 part by mass of the epoxy resin curing agent, is cured for 60 minutes at a temperature of 150ºC, the areal ratio of filler voids having a circle equivalent diameter of 5-40 µm present in a cross section of the cured product is 0.1-10.0 area%.

Description

Epoxy resin curing agent, epoxy resin composition, semiconductor encapsulant, semiconductor package, cured product, and electronic device

[0001] The present invention relates to an epoxy resin curing agent, an epoxy resin composition, a semiconductor encapsulant, a semiconductor package, a cured product, and an electronic device.

[0002] Highly reliable epoxy resin compositions have been used as sealants, insulating materials, conductive adhesives, and heat dissipation pastes for semiconductor elements. In recent years, semiconductor elements have become larger, thinner, and more highly integrated, resulting in an increase in the amount of heat generated. This has made it increasingly important to alleviate stress and design heat dissipation for semiconductor elements.

[0003] Patent Document 1 discloses an epoxy resin sealant made of an epoxy resin composition that contains a large amount of inorganic filler, has fluidity at room temperature, and can reduce wafer warpage.

[0004] International Publication No. 2009 / 142065

[0005] Patent Document 1 discloses an epoxy resin sealant comprising an epoxy resin composition containing a large amount of filler and a solid-dispersion-type epoxy resin curing agent. However, the epoxy resin composition containing the solid-dispersion-type epoxy resin curing agent disclosed in Patent Document 1 has problems in that it has insufficient crack resistance and its physical properties change when stored in a high-temperature, high-humidity environment.

[0006] In view of the above-mentioned problems of the conventional art, the present invention aims to provide an epoxy resin curing agent that can give a cured product having high crack resistance and showing little change in physical properties before and after moisture absorption testing, an epoxy resin composition containing the epoxy resin curing agent, and a cured product thereof.

[0007] The present inventors have conducted extensive research to solve the problems of the prior art described above, and as a result have found that the problems of the prior art described above can be solved by specifying the area ratio of filler voids having a size within a specific numerical range present in a cross section of a cured product of an epoxy resin composition containing a BisA epoxy resin, methyl nadic anhydride, spherical silica having a particle size (D50) at 50% cumulative volume in the volume particle size distribution of 0.6 μm, and an epoxy resin curing agent, and have thus completed the present invention. That is, the present invention is as follows.

[0008] [1] An epoxy resin curing agent that satisfies the following <Condition 1>. <Condition 1> An epoxy resin composition containing 10 parts by mass of a BisA type epoxy resin, 9 parts by mass of methyl nadic anhydride, 30 parts by mass of spherical silica having a particle size (D50) value at 50% cumulative volume in the volume particle size distribution of 0.6 μm, and 1 part by mass of the epoxy resin curing agent, is cured at a temperature of 150°C for 60 minutes, and the area ratio of filler voids having a circle equivalent diameter of 5 μm to 40 μm in the cross section of the cured product is 0.1 area % to 10.0 area %. [2] The epoxy resin curing agent according to [1], wherein the particle size (D10) value at 10% cumulative volume in the volume particle size distribution is from 0.1 μm to 0.8 μm, the particle size (D99) value at 99% cumulative volume in the volume particle size distribution is from 3 μm to 7 μm, and the curing agent contains particles that are solid at 25° C. [3] The epoxy resin curing agent, wherein the particle size (D10) value at 10% cumulative volume in the volume particle size distribution is from 0.1 μm to 0.8 μm, the particle size (D99) value at 99% cumulative volume in the volume particle size distribution is from 3 μm to 7 μm, and the curing agent contains particles that are solid at 25° C. [4] An epoxy resin composition comprising the epoxy resin curing agent according to any one of [1] to [3], (B) an epoxy resin, and (C) a filler. [5] The epoxy resin composition according to [4], which contains at least one curing agent (D) selected from the group consisting of acid anhydride curing agents, phenolic curing agents, thiol curing agents, active ester curing agents, amine curing agents, and amide curing agents. [6] The epoxy resin composition according to [4], which contains the (C) filler at a volume ratio of 40% by volume to 90% by volume. [7] The epoxy resin composition according to [5], which contains the (C) filler at a volume ratio of 40% by volume to 90% by volume. [8] The epoxy resin composition according to [4], which contains the (C) filler in particles having a diameter of 20 μm to 50 μm. [9] The epoxy resin composition according to [5], which contains the (C) filler in particles having a diameter of 20 μm to 50 μm.

[10] The epoxy resin composition according to [6], which contains the (C) filler in particles having a diameter of 20 μm to 50 μm.

[11] The epoxy resin composition according to [7] above, wherein the filler (C) comprises particles having a diameter of 20 μm or more and 50 μm or less.

[12] A semiconductor encapsulant comprising the epoxy resin curing agent according to any one of [1] to [3] above.

[13] A semiconductor package comprising the semiconductor encapsulant according to

[12] above.

[14] A cured product of the epoxy resin composition according to any one of [4] to

[11] above.

[15] A cured product of an epoxy resin composition comprising an epoxy resin, an epoxy resin curing agent, and a filler, wherein the area ratio of filler voids having a circular equivalent diameter of 5 μm or more and 40 μm or less in a cross section of the cured product is 0.1 area % or more and 10.0 area % or less.

[16] A semiconductor package comprising the cured product according to

[14] or

[15] above.

[17] An electronic device comprising the cured product according to

[14] or

[15] above.

[0009] The present invention aims to provide an epoxy resin curing agent capable of producing a cured product having high crack resistance and little change in physical properties before and after a moisture absorption test; an epoxy resin composition containing the epoxy resin curing agent; a semiconductor encapsulant; a semiconductor package containing the semiconductor encapsulant; a cured product; and a semiconductor package containing the cured product.

[0010] 1 shows an example of an SEM image of a cross section of a cured product of an epoxy resin composition.

[0011] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0012] [Epoxy Resin Curing Agent] The epoxy resin curing agent of this embodiment satisfies the following <Condition 1>. <Condition 1> An epoxy resin composition containing 10 parts by mass of a BisA epoxy resin, 9 parts by mass of methyl nadic anhydride, 30 parts by mass of spherical silica having a particle size (D50) value at 50% cumulative volume in the volume particle size distribution of 0.6 μm, and 1 part by mass of the epoxy resin curing agent is cured at a temperature of 150°C for 60 minutes, and the area ratio of filler voids having a circle equivalent diameter of 5 μm to 40 μm present in the cross section of the cured product is 0.1 area % to 10.0 area %.

[0013] The area ratio of the filler voids is preferably 0.2 area% or more and 9.0 area% or less, more preferably 0.3 area% or more and 8.0 area% or less. An area ratio of filler voids with a circle equivalent diameter of 5 μm or more and 40 μm or less of 10.0 area% or less means that the cured product containing the filler is highly uniform, and the moisture absorption becomes uniform throughout the cured product, which tends to make the Tg and elastic modulus less likely to decrease overall. An area ratio of filler voids with a circle equivalent diameter of 5 μm or more and 40 μm or less of 0.1 area% or more means that there are many resin domains of a certain size, which makes it possible to stop crack propagation and tends to improve crack resistance.

[0014] The above <Condition 1> indicates the measurement conditions and measurement results for a cured product that specifies the physical properties of a predetermined epoxy resin composition using the epoxy resin curing agent of this embodiment, and the epoxy resin curing agent of this embodiment is not limited to the use of epoxy resin compositions and cured products containing the materials shown in <Condition 1>.

[0015] The "circle equivalent diameter" is the value obtained by dividing the perimeter of filler voids present in the cross section of a cured product by pi (π). The "filler voids" refer to areas where no filler is present when observing the cross section of a cured product of an epoxy resin composition containing a filler. Figure 1 shows an example of an SEM image of a cured product cross section. In Figure 1, the areas that are darker black than the surrounding area are "filler voids." The "filler void area ratio" is the average filler void area ratio over three fields of view calculated by binarizing an SEM image of the cross section of the cured product, using the filler void area of ​​a filler void with a circular equivalent diameter of 5 μm to 40 μm as the numerator and the area of ​​one field of view as the denominator. Specifically, it can be measured by the method described in the Examples below.

[0016] One method for controlling the area ratio of filler voids with a circular equivalent diameter of 5 μm to 40 μm in the cross section of a cured product of the above-described specified epoxy resin composition to within the above-described numerical range is to adjust the particle size distribution of the epoxy resin curing agent of this embodiment. Specifically, one method is to simultaneously control the particle size at 10% cumulative volume (D10) and the particle size at 99% cumulative volume (D99) of the volume particle size distribution. The D10 value is preferably 0.1 μm to 0.8 μm, and the D99 value is preferably 3 μm to 7 μm. The D10 value is more preferably 0.12 μm or more, and even more preferably 0.15 μm or more. It is also more preferably 0.7 μm or less, and even more preferably 0.6 μm or less. The D99 value is more preferably 3.1 μm or more, and even more preferably 3.2 μm or more. It is also more preferably 6 μm or less, and even more preferably 5 μm or less. D10 and D99 in the particle size distribution of the epoxy resin curing agent of this embodiment can be simultaneously controlled to fall within the above-mentioned numerical ranges by similarly pulverizing the pulverized product obtained using an airflow jet mill or the like two or three times in an environment at room temperature of 0 to 10°C and humidity of 30% RH or less.

[0017] The epoxy resin curing agent of this embodiment preferably has a particle size (D10) value at 10% cumulative volume in the volume particle size distribution of 0.1 μm or more and 0.8 μm or less, a particle size (D99) value at 99% cumulative volume in the volume particle size distribution of 3 μm or more and 7 μm or less, and contains particles that are solid at 25°C. By having such a configuration, the epoxy resin curing agent of this embodiment can control the area ratio of filler voids with a circle equivalent diameter of 5 μm or more and 40 μm or less in the cross section of a cured product of an epoxy resin composition using the epoxy resin curing agent of this embodiment to 0.1 area% or more and 10.0 area% or less. Note that particles that are solid at 25°C refer to substances that have a melting point or softening point higher than 25°C. Melting points and softening points are measured using a DSC device (e.g., Hitachi High-Tech DSC600) or a softening point tester (e.g., METTLER TOLEDO DP70). Furthermore, by containing particles that are solid at 25°C, an epoxy resin composition with high storage stability can be obtained.

[0018] The area ratio of filler voids having a circle equivalent diameter of 5 μm or more and 40 μm or less present in the cross section of the cured epoxy resin composition can be controlled by appropriately selecting the type of epoxy resin curing agent of this embodiment. The area ratio of filler voids having a circle equivalent diameter of 5 μm or more and 40 μm or less present in the cross section of the cured epoxy resin composition can be measured by the method described in the examples below.

[0019] The epoxy resin curing agent of the present embodiment is preferably a modified amine having a softening point or a curing agent having a core-shell structure.

[0020] The modified amine having a softening point is solid at 25°C and contains an amine compound. Examples of the amine compound include, but are not limited to, aliphatic primary amines, alicyclic primary amines, aromatic primary amines, aliphatic secondary amines, alicyclic secondary amines, aromatic secondary amines, aliphatic tertiary amines, alicyclic tertiary amines, aromatic tertiary amines, imidazole compounds, and imidazoline compounds. The amine compound is preferably selected from aliphatic tertiary amines, alicyclic tertiary amines, aromatic tertiary amines, imidazole compounds, and imidazoline compounds. The amine compound may be used in the form of a reaction product with a carboxylic acid, sulfonic acid, isocyanate, epoxide, or the like. These amine compounds may be used alone or in combination of two or more. For example, the amine compound may be used in combination with its reaction product with a carboxylic acid, sulfonic acid, isocyanate, or epoxide. In one embodiment, the modified amine compound having a softening point contains an imidazole compound and / or a tertiary amine compound.

[0021] The epoxy resin curing agent of this embodiment is preferably a latent curing agent, and preferably has, for example, a core-shell structure. The core-shell structure of the epoxy resin curing agent of this embodiment preferably has, for example, a core containing a curing agent and a shell consisting of a coating agent formed on the surface of the core. The shell preferably contains a resin and / or an inorganic oxide. From the viewpoints of ease of destruction upon heating and uniformity of the cured product, the shell preferably contains a resin. Resins contained in the shell include, but are not limited to, epoxy-based resins, phenol-based resins, polyester-based resins, polyethylene-based resins, nylon-based resins, polystyrene-based resins, urethane-based resins, etc. Among these, from the viewpoint of the balance between film stability and destruction upon heating, epoxy-based resins, phenol-based resins, and urethane-based resins are preferred as the resin contained in the shell.

[0022] Examples of epoxy resin curing agents having a core-shell structure include microcapsule-type curing agents. Microcapsule-type curing agents are curing agents for epoxy resins in which the curing action is reversibly blocked by microencapsulation. In these microcapsule-type curing agents, the curing action can be restored by heating or the like. The curing agent contained in the microcapsule-type curing agent is not particularly limited as long as it can cure the epoxy resin. Examples of curing agents contained in the microcapsule-type curing agent include amine compounds (including imidazole compounds).

[0023] The microcapsule-type curing agent preferably contains an amine compound. Examples of the amine compound include, but are not limited to, aliphatic primary amines, alicyclic primary amines, aromatic primary amines, aliphatic secondary amines, alicyclic secondary amines, aromatic secondary amines, aliphatic tertiary amines, alicyclic tertiary amines, aromatic tertiary amines, imidazole compounds, and imidazoline compounds. The amine compound is preferably selected from aliphatic tertiary amines, alicyclic tertiary amines, aromatic tertiary amines, imidazole compounds, and imidazoline compounds. The amine compound may also be used in the form of a reaction product with a carboxylic acid, sulfonic acid, isocyanate, epoxide, or the like. These compounds may be used alone or in combination of two or more. For example, the amine compound may be used in combination with its reaction product with a carboxylic acid, sulfonic acid, isocyanate, or epoxide.

[0024] When the epoxy resin curing agent of the present embodiment is a microcapsule-type curing agent, the microcapsule-type curing agent preferably contains an imidazole compound. Examples of the imidazole compound include, but are not limited to, 2-substituted imidazole compounds such as imidazole, 2-methylimidazole, 2-ethylimidazole, 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, and 1-cyanoethyl-2-phenylimidazole; 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole; trimellitic acid salts such as undecyl-2-phenylimidazolium trimellitate; triazine ring-containing compounds such as 2,4-diamino-6-[(2-methyl-1-imidazolyl)ethyl]s-triazine, 2,4-diamino-6-[(2-undecyl-1-imidazolyl)ethyl]s-triazine, and 2,4-diamino-6-[(2-ethyl-4-methyl-1-imidazolyl)ethyl]s-triazine; an isocyanuric acid adduct of 2,4-diamino-6-[(2-methyl-1-imidazolyl)ethyl]s-triazine, an isocyanuric acid adduct of 2-phenylimidazole, an isocyanuric acid adduct of 2-methylimidazole, an isocyanuric acid adduct of 2-phenyl-4,5-dihydroxymethylimidazole, and an isocyanuric acid adduct of 2-phenyl-4-methyl-5-hydroxymethylimidazole. Other examples include an adduct of the imidazole compound with an epoxy resin.

[0025] [Epoxy Resin Composition] The epoxy resin composition of the present embodiment contains the epoxy resin curing agent of the present embodiment (hereinafter, may be referred to as (A) epoxy resin curing agent, or component (A)), (B) epoxy resin (hereinafter, may be referred to as (B) component), and (C) filler (hereinafter, may be referred to as (C) component).

[0026] ((B) Epoxy Resin) The epoxy resin composition of the present embodiment contains (B) epoxy resin. The (B) epoxy resin is not particularly limited, and various known epoxy resins can be appropriately selected and used. As the (B) epoxy resin, one type may be used alone, or two or more types may be used in combination.

[0027] (B) Epoxy resins include, but are not limited to, bifunctional epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, tetrabromobisphenol A type epoxy resins, biphenyl type epoxy resins, tetramethylbiphenyl type epoxy resins, tetrabromobiphenyl type epoxy resins, diphenyl ether type epoxy resins, benzophenone type epoxy resins, phenylbenzoate type epoxy resins, diphenyl sulfide type epoxy resins, diphenyl sulfoxide type epoxy resins, diphenyl sulfone type epoxy resins, diphenyl disulfide type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins, hydroquinone type epoxy resins, methylhydroquinone type epoxy resins, dibutylhydroquinone type epoxy resins, resorcinol type epoxy resins, methylresorcinol type epoxy resins, catechol type epoxy resins, N,N-diglycidylaniline type epoxy resins, and N,N-diglycidyl-o-toluidine type epoxy resins.

[0028] Examples of the epoxy resin (B) include trifunctional epoxy resins such as triazine-type epoxy resins and aminophenol-type epoxy resins; tetrafunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane-type epoxy resins and diaminobenzene-type epoxy resins; polyfunctional epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, triphenylmethane-type epoxy resins, tetraphenylethane-type epoxy resins, dicyclopentadiene-type epoxy resins, naphthol aralkyl-type epoxy resins and brominated phenol novolac-type epoxy resins; (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, polytetramethylene ether glycol diglycidyl ether, diglycidyl acyclic aliphatic epoxy resins such as glycerin diglycidyl ether and neopentyl glycol diglycidyl ether; triglycidyl acyclic aliphatic epoxy resins such as trimethylolpropane triglycidyl ether and glycerin triglycidyl ether; alicyclic epoxy resins such as vinyl(3,4-cyclohexene) dioxide and 2-(3,4-epoxycyclohexyl)-5,1-spiro-(3,4-epoxycyclohexyl)-m-dioxane; cyclohexane-type diglycidyl ethers such as cyclohexanedimethanol diglycidyl ether, dicyclopentadiene-type diglycidyl ether, and cycloaliphatic epoxy resins such as tetraglycidyl bis(aminomethyl)cyclohexane; hydantoin-type epoxy resins such as 1,3-diglycidyl-5-methyl-5-ethylhydantoin; and epoxy resins having a silicone skeleton such as 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane.

[0029] Further, examples of the epoxy resin (B) include 2-ethylhexyl glycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, hydrogenated bisphenol A type epoxy resin, silicone-modified epoxy resin, (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane diglycidyl ether, and polytetramethylene ether. Terephthalic acid diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexane diglycidyl ether, dicyclopentadiene diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, vinyl(3,4-cyclohexene) dioxide, 2-(3,4-epoxycyclohexyl)-5,1-spiro-(3,4-epoxycyclohexyl)-m-dioxane, tetraglycidyl bis(aminomethyl)cyclohexyl Glycidylamine type epoxy resins such as hexane, 1,3-diglycidyl-5-methyl-5-ethylhydantoin type epoxy resins, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane type epoxy resins, phenyl glycidyl ether, cresyl glycidyl ether, p-s-butylphenyl glycidyl ether, styrene oxide, p-tert-butylphenyl glycidyl ether, o-phenylphenol glycidyl ether, p-phenylphenol glycidyl ether, N Examples of the epoxy resins include aliphatic epoxy resins and alicyclic epoxy resins that can also be used as reactive diluents, such as 1,2-dimethyl-4-(2-methyloxiranyl)-1-methylcyclohexane, 1,2-dimethyl-4-(2-methyloxiranyl)-1-methylcyclohexane, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, and neodecanoic acid glycidyl ester.

[0030] The content of the epoxy resin (B) in the epoxy resin composition of this embodiment is preferably 2% by mass or more from the viewpoint of suppressing brittleness of the cured product of the epoxy resin composition of this embodiment, and is preferably 50% by mass or less from the viewpoint of suppressing the linear expansion coefficient of the cured product, more preferably 3 to 45% by mass, and even more preferably 4 to 40% by mass.

[0031] The content of the epoxy resin curing agent (A) in the epoxy resin composition of the present embodiment is preferably 0.01% by mass or more from the viewpoint of short-time curing, and is preferably 10% by mass or less, more preferably 0.02 to 9% by mass, and even more preferably 0.03 to 8% by mass, from the viewpoint of controlling the area ratio of filler voids in the cross section of the cured product to a desired numerical range.

[0032] (Filler (C)) The epoxy resin composition of the present embodiment contains a filler (C) (hereinafter, may be referred to as component (C)). Examples of the filler (C) include an organic filler and an inorganic filler.

[0033] The organic filler functions as an impact buffer, capable of mitigating stress generated by impact. By including the organic filler, the epoxy resin composition of the present embodiment can further improve adhesion to various connecting members. In addition, the occurrence and propagation of fillet cracks tends to be suppressed.

[0034] Examples of organic fillers include, but are not limited to, organic fine particles of acrylic resin, silicone resin, butadiene rubber, polyester, polyurethane, polyvinyl butyral, polyarylate, polymethyl methacrylate, acrylic rubber, polystyrene, NBR, SBR, silicone-modified resin, and copolymers containing these as components. From the viewpoint of improving adhesion, preferred organic fine particles include alkyl (meth)acrylate-butadiene-styrene copolymer, alkyl (meth)acrylate-silicone copolymer, silicone-(meth)acrylic copolymer, composite of silicone and (meth)acrylic acid, composite of alkyl (meth)acrylate-butadiene-styrene and silicone, and composite of alkyl (meth)acrylate and silicone. Furthermore, organic fine particles having a core-shell structure, in which the core layer and shell layer have different compositions, can also be used as the organic filler. Examples of core-shell organic fine particles include particles in which an acrylic resin is grafted onto a silicone-acrylic rubber core, and particles in which an acrylic resin is grafted onto an acrylic copolymer. These organic fillers may be used alone or in combination of two or more.

[0035] The epoxy resin composition of the present embodiment contains an inorganic filler, which allows the thermal expansion coefficient of the epoxy resin composition of the present embodiment to be adjusted. The inclusion of an inorganic filler in the epoxy resin composition of the present embodiment tends to contribute to improvements in heat resistance, moisture resistance, heat dissipation, and conductivity when used as a sealant or a conductive paste.

[0036] Examples of inorganic fillers include, but are not limited to, silicates such as talc, calcined clay, uncalcined clay, mica, and glass; oxides such as titanium oxide, aluminum oxide (alumina), fused silica (fused spherical silica, fused crushed silica), synthetic silica, and crystalline silica; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates such as barium sulfate and calcium sulfate; sulfites such as calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; nitrides such as aluminum nitride, boron nitride, and silicon nitride; and conductive particles such as gold, silver, nickel, copper, palladium, platinum, bismuth, tin, alloys thereof (particularly, bismuth-tin alloys, solder, etc.), aluminum, indium tin oxide, silver-coated copper, silver-coated aluminum, metal-coated glass spheres, silver-coated fibers, silver-coated resin antimony-doped tin, tin oxide, carbon fibers, graphite, and carbon black. Among these, from the viewpoint of improving heat resistance, moisture resistance, and strength, fused silica, crystalline silica, and synthetic silica powder are preferred, and any of silicon oxide, aluminum oxide, and boron nitride is also preferred. The use of these materials can suppress the coefficient of linear thermal expansion, which is expected to improve thermal cycling tests. The shape of the inorganic filler is not particularly limited, and may be, for example, amorphous, spherical, or flaky. From the viewpoint of the fluidity of the epoxy resin composition of this embodiment, spherical shapes are more preferred. These inorganic fillers may be used alone or in combination of two or more.

[0037] The filler (C) preferably contains particles having a diameter of 20 μm or more and 50 μm or less. By including particles having a diameter of 20 μm or more and 50 μm or less in the filler (C), it is possible to maintain a low viscosity of the epoxy resin composition of this embodiment even if the filler proportion is increased. The particle diameter is more preferably 25 μm or more and 45 μm or less, and even more preferably 30 μm or more and 40 μm or less. Furthermore, fillers with different particle diameters may be combined.

[0038] In the epoxy resin composition of this embodiment, the volume fraction of the filler (C) is preferably 40% by volume or more and 90% by volume or less, more preferably 50% by volume or more and 88% by volume or less, and even more preferably 55% by volume or more and 85% by volume or less. When the volume fraction of the filler (C) in the epoxy resin composition of this embodiment is 40% by volume or more, it tends to be possible to exhibit physical properties of the cured product, such as electrical conductivity, heat dissipation, and a low linear expansion coefficient, and when it is 90% by volume or less, the flowability of the epoxy resin composition of this embodiment tends to be good.

[0039] ((D) Curing Agent) The epoxy resin composition of this embodiment preferably contains a (D) curing agent (hereinafter, sometimes referred to as component (D)) other than the (A) epoxy resin curing agent. Examples of the (D) curing agent include, but are not limited to, amine-based curing agents, amide-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, active ester-based curing agents, and thiol-based curing agents. From the viewpoint of reducing the viscosity of the epoxy resin composition of this embodiment and thereby improving the filling rate of the filler, the (D) curing agent is preferably a phenol-based curing agent, an acid anhydride-based curing agent, or a thiol-based curing agent, with an acid anhydride-based curing agent being more preferred.

[0040] Examples of amine-based curing agents include, but are not limited to, aliphatic amines, aromatic amines, etc. Examples of aliphatic amines include, but are not limited to, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, etc. Examples of aromatic amines include, but are not limited to, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, diethyltoluenediamine, trimethylenebis(4-aminobenzoate), polytetramethyleneoxide-di-p-aminobenzoate, KAYAHARD AA (manufactured by Nippon Kayaku Co., Ltd.), and Ethacure 100 (manufactured by Mitsui Chemicals Fine Chemicals Co., Ltd.).

[0041] Examples of amide-based curing agents include, but are not limited to, dicyandiamide and its derivatives, such as guanidine-based compounds, or compounds obtained by adding an acid anhydride to an amine-based compound, and hydrazide-based compounds. Examples of hydrazide-based compounds include, but are not limited to, succinic acid dihydrazide, adipic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, p-oxybenzoic acid hydrazide, salicylic acid hydrazide, phenylaminopropionic acid hydrazide, and maleic acid dihydrazide. Examples of guanidine-based compounds include, but are not limited to, dicyandiamide, methylguanidine, ethylguanidine, propylguanidine, butylguanidine, dimethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, and toluylguanidine.

[0042] Examples of phenol-based curing agents include, but are not limited to, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, cresol aralkyl resin, naphthol aralkyl resin, biphenyl-modified phenol resin, biphenyl-modified phenol aralkyl resin, dicyclopentadiene-modified phenol resin, aminotriazine-modified phenol resin, naphthol novolac resin, naphthol-phenol co-condensed novolac resin, naphthol-cresol co-condensed novolac resin, and allyl acrylic phenol resin.

[0043] Examples of acid anhydride curing agents include, but are not limited to, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0044] The active ester curing agent is not particularly limited as long as it functions as a curing agent for epoxy resins and has an active ester, but a compound having two or more active ester groups per molecule is preferred. From the viewpoint of heat resistance, etc., an active ester compound obtained by reacting a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound is more preferred, and an active ester compound obtained by reacting a carboxylic acid compound with one or more selected from a phenol compound, a naphthol compound, and a thiol compound is even more preferred. The active ester compounds constituting the active ester curing agent may be used alone or in combination of two or more. As the active ester compound, the active ester compounds disclosed in JP-A-2004-277460 may be used, or commercially available compounds may also be used. As commercially available active ester compounds, for example, those containing a dicyclopentadienyl diphenol structure, acetylated phenol novolac, and benzoylated phenol novolac are preferred, with those containing a dicyclopentadienyl diphenol structure being particularly preferred. Examples of compounds containing a dicyclopentadienyldiphenol structure include EXB9451, EXB9460, EXB9460S, and HPC-8000-65T (manufactured by DIC Corporation), DC808 (manufactured by Japan Epoxy Resins Co., Ltd.) as an acetylated product of phenol novolac, and YLH1026 (manufactured by Japan Epoxy Resins Co., Ltd.) as a benzoylated product of phenol novolac.

[0045] Examples of thiol-based curing agents include, but are not limited to, trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, pentaerythritol tetrakis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), and tetraethylene glycol bis(3-mercaptopropionate). 1,3,4,6-Tri(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol trippropanethiol, pentaerythritol tetrapropanethiol, 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)glycoluril, 1,3,4,6-tetrakis(mercaptoethyl)glycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a-methylglycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl)-3a-methylglycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)-3a-methylglycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a,6a-dimethylglycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl)-3 1,3,4,6-tetrakis(3-mercaptopropyl)-3a,6a-dimethylglycoluril, 1,3,4,6-tetrakis(mercaptomethyl)-3a,6a-diphenylglycoluril, 1,3,4,6-tetrakis(2-mercaptoethyl)-3a,6a-diphenylglycoluril, 1,3,4,6-tetrakis(3-mercaptopropyl)-3a,6a-diphenylglycoluril, and the like.

[0046] With regard to the content of component (D) in the epoxy resin composition of this embodiment, from the viewpoints of the viscosity, Tg of the cured product, and adhesive properties of the epoxy resin composition of this embodiment, the ratio of the epoxy equivalent of component (B) to the active group equivalent of component (D): ((B) / (D)) is preferably 0.5 or more and 2.0 or less, more preferably 0.6 or more and 1.8 or less, even more preferably 0.7 or more and 1.6 or less, and still more preferably 0.8 or more and 1.4 or less.

[0047] (Other Additives) In addition to the components described above, the epoxy resin composition of the present embodiment may further contain additives such as pigments, dyes, flow modifiers, thickeners, release agents, wetting agents, flame retardants, and surfactants, as necessary. These additives may be used alone or in combination of two or more.

[0048] Examples of pigments include, but are not limited to, kaolin, chalk powder, gypsum, antimony trioxide, pentone, aerosol, lithopone, barite, and the like.

[0049] Examples of dyes include, but are not limited to, natural dyes such as plant-derived dyes such as madder and indigo, and mineral-derived dyes such as yellow ochre and red clay, synthetic dyes such as alizarin and indigo, and fluorescent dyes.

[0050] Examples of flow control agents include, but are not limited to, organic silane compounds such as silane coupling agents, silicone oils, and silicone gels; organic titanium compounds such as titanium tetraisopropoxide and titanium diisopropoxybis(acetylacetonate); and organic zirconium compounds such as zirconium tetra-n-butoxide and zirconium tetraacetylacetonate.

[0051] Examples of thickeners include, but are not limited to, animal-based thickeners such as gelatin; plant-based thickeners such as polysaccharides and cellulose; and chemically synthesized thickeners such as polyacrylic thickeners, modified polyacrylic thickeners, polyether thickeners, urethane-modified polyether thickeners, and carboxymethyl cellulose.

[0052] Examples of the release agent include, but are not limited to, fluorine-based release agents, silicone-based release agents, and acrylic release agents made of a copolymer of glycidyl (meth)acrylate and a linear alkyl (meth)acrylate having 16 to 22 carbon atoms.

[0053] Examples of wetting agents include, but are not limited to, unsaturated polyester copolymer wetting agents having acidic groups, such as acrylic polyphosphate esters.

[0054] Examples of flame retardants include, but are not limited to, halogen-based flame retardants such as chlorine compounds and bromine compounds, phosphorus-based flame retardants such as condensed phosphate esters, and antimony-based flame retardants such as antimony trioxide and antimony pentoxide.

[0055] Examples of surfactants include, but are not limited to, anionic surfactants such as alkylbenzene sulfonates and alkyl polyoxyethylene sulfates, cationic surfactants such as alkyl dimethyl ammonium salts, amphoteric surfactants such as alkyl dimethyl amine oxides and alkyl carboxy betaines, and nonionic surfactants such as linear alcohols and fatty acid esters having 25 or more carbon atoms.

[0056] The other additives described above can be used alone or in combination of two or more types depending on the desired properties of the epoxy resin composition of this embodiment, and the amount of each additive added can also be selected appropriately.

[0057] [Method for Producing Epoxy Resin Composition] The epoxy resin composition of this embodiment can be produced by mixing and kneading the above-described components. The mixing and kneading method is not particularly limited, and examples include methods using a reactor with an agitator blade, a planetary mixer, a kneader, a roll, a homodisper, an extruder, or the like. The mixing and kneading process may be performed in a cooled state, at room temperature, or under heating. The kneading temperature varies depending on the viscosity and melting temperature of the epoxy resin, but is typically 5 to 250°C, preferably 10 to 150°C, and more preferably 15 to 120°C. A kneading temperature of 250°C or less tends to prevent the curing reaction from progressing during kneading and to suppress an increase in viscosity. A kneading temperature of 5°C or higher tends to prevent the viscosity of the epoxy resin or curing agent from increasing, facilitating kneading, and inhibiting moisture from adhering to the epoxy resin composition, which tends to prevent the moisture from evaporating during curing and creating voids in the cured product.

[0058] [Cured Product] The cured product of this embodiment is a cured product of the epoxy resin composition of this embodiment, and can be produced by curing the epoxy resin composition of this embodiment. The curing conditions are not particularly limited, but a method of curing by heating to a constant temperature is preferred. Methods for producing the cured product include, but are not limited to, methods of curing using a hot air drying oven, a hot plate, a heated mold, or the like. The curing temperature is preferably 80°C or higher and 220°C or lower, more preferably 100°C or higher and 200°C or lower, and even more preferably 110°C or higher and 190°C or lower.

[0059] The cured product of this embodiment is a cured product of an epoxy resin composition containing an epoxy resin, the epoxy resin curing agent of this embodiment, and a filler, and is preferably a cured product in which the area ratio of filler voids having a circle equivalent diameter of 5 μm to 40 μm in the cross section of the cured product is 0.1 area% to 20 area%. More preferably, it is 0.2 area% to 18 area%, even more preferably 0.3 area% to 15 area%, and even more preferably 0.4 area% to 12 area%. One method for controlling the area ratio of filler voids having a circle equivalent diameter of 5 μm to 40 μm in the cured product within the above range is to adjust the particle sizes (D10) and (D99) of the epoxy resin curing agent of this embodiment. A method for controlling the area ratio of filler voids having a circular equivalent diameter of 5 μm or more and 40 μm or less present in the cross section of the cured product of this embodiment to 0.1 area % or more and 10.0 area % or less can be exemplified by a method in which the diameter of the filler is 20 μm or more and less than 50 μm, the volume ratio of the filler is 40 volume % or more and 90 volume % or less, and the particle sizes (D10) and (D99) of the epoxy resin curing agent of this embodiment are controlled as described above.

[0060] [Uses of Epoxy Resin Curing Agent, Epoxy Resin Composition, and Cured Product] The epoxy resin composition and cured product of this embodiment are useful as semiconductor encapsulants, adhesives, filler materials, insulating materials, sealing materials, prepregs, etc. As adhesives, they are useful as liquid adhesives, film adhesives, die bonding materials, etc. As semiconductor encapsulants, they are useful as solid encapsulants, liquid encapsulants, film encapsulants, etc., and as liquid encapsulants, they are useful as underfill materials, potting materials, dam materials, etc. As insulating materials, they are useful as insulating adhesive films, insulating adhesive pastes, solder resists, etc. The cured product of this embodiment, for example, a semiconductor encapsulant, can be used in semiconductor packages.

[0061] [Electronic Device] The electronic device of this embodiment preferably includes the cured product of this embodiment and has the semiconductor package of this embodiment. By including the semiconductor package of this embodiment, an electronic device with excellent crack resistance and little change in elastic modulus before and after moisture absorption tends to be obtained.

[0062] The electronic device may be any device that functions by incorporating electronic components, and includes, but is not limited to, various electronic devices used in electrical appliances such as personal computers, smartphones, game consoles, digital cameras and televisions, vehicles such as motorcycles, automobiles, trains, ships and aircraft, and high-speed communication antennas and servers.

[0063] The electronic device of this embodiment is not particularly limited, but can be manufactured, for example, by using a semiconductor package in which various semiconductor chips are mounted at locations on a wiring board where circuit connections are made, thereby ensuring electrical continuity.

[0064] Hereinafter, the present embodiment will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[0065] First, the measurement and evaluation methods for each physical property are described below. [Physical Properties and Characteristics of Cured Products and Epoxy Resin Compositions] (Change in Elastic Modulus Before and After Moisture Absorption Test) Cured products prepared using the method described below were cut into pieces measuring 2 mm (thickness) × 10 mm × 40 mm, and dynamic viscoelasticity measurements were performed using an RSA-G2 (manufactured by TA Instruments) at a frequency of 1 Hz while the temperature was raised from 25°C to 250°C at a rate of 4°C / min, to measure the elastic modulus at 200°C. Cured products measuring 2 mm (thickness) × 10 mm × 40 mm obtained in the same manner were stored for 7 days in a thermo-hygrostat PR-1KT (manufactured by Espec Corporation) maintained at 85°C and 85% RH, and the elastic modulus at 200°C after storage was measured under the same measurement conditions. The elastic modulus after storage relative to the initial elastic modulus was calculated, and the change in elastic modulus before and after the moisture absorption test was evaluated as follows. <Evaluation criteria> ◎: 0.9 or more ◯: 0.75 or more and less than 0.9 △: 0.5 or more and less than 0.75 ×: Less than 0.5

[0066] (Crack Resistance) A cured product prepared by the method described below was cut into a size of 2 mm x 4 mm x 40 mm. With the 2 mm x 40 mm surface facing up, a razor blade was placed at the center of the 40 mm side parallel to the 2 mm side, and the cured product was struck from above with a hammer, creating a crack of 1.8 to 2.2 mm. A load was applied from above at a rate of 0.5 mm / min with a support distance of 20 mm, with the cracked side facing downward, and the maximum point test force P was measured. The value of K1c was calculated using the following equation, where a is the crack depth, W is the test specimen height, and B is the test specimen thickness. Note that because the crack was created in the same direction as the height W of the test specimen, the crack depth was 1.8 to 2.2 mm. Note that the unit of test force here is MPa, and the units of crack depths a, W, and B are m.

[0067]

[0068] The determined K1c values ​​were evaluated according to the following criteria: <Evaluation criteria> ⊚: 1.5 or more ◯: 1.2 or more and less than 1.5 Δ: 1.0 or more and less than 1.2 ×: Less than 1.0

[0069] (Measurement of Linear Expansion Coefficient) The cured product prepared by the method described below was cut into test pieces measuring 2 mm (thickness) x 5 mm x 5 mm, and measurements were carried out in thermal expansion measurement mode using a thermomechanical analyzer TMA Q400 (manufactured by TA Instruments). After mounting the test pieces in the apparatus, measurements were carried out twice consecutively under the measurement conditions of a load of 1 g, a temperature rise rate of 5°C / min, and a temperature range of 25 to 200°C. In the second measurement, the average linear thermal expansion coefficient (ppm / °C) from 25 to 80°C was evaluated according to the following criteria. <Evaluation Criteria> ◎: Less than 30 ppm ◯: 30 ppm or more but less than 40 ppm △: 40 ppm or more but less than 50 ppm ×: 50 ppm or more

[0070] (Evaluation of storage stability) The viscosity of the epoxy resin compositions prepared by the method described below was measured at 40°C for about 7 days using an E-type viscometer (25°C). The ratio of the viscosity of the epoxy resin composition after storage to the viscosity of the epoxy resin composition before storage (viscosity ratio after storage) = (viscosity after storage / viscosity before storage) was calculated, and the storage stability was evaluated as follows. <Evaluation criteria> ◎: Less than 1.5 times; ○: 1.5 times or more but less than 2.0 times; △: 2.0 times or more but less than 4.0 times; ×: 4.0 times or more; XX: Cured and unable to be measured.

[0071] (Flexural Strength Before and After Moisture Absorption) A cured product prepared by the method described below was cut into a size of 2 mm (thickness) × 4 mm × 40 mm. A load was applied from above the 2 mm × 40 mm surface at a rate of 0.5 mm / min with a support distance of 20 mm, and the maximum point test force P was measured. A 2 mm (thickness) × 4 mm × 40 mm cured product obtained by the same method was stored for 7 days in a constant temperature and humidity device PR-1KT (manufactured by Espec Corporation) maintained at 85°C and 85% RH, and the maximum point test force P' after storage was measured under the same measurement conditions. The ratio (P' / P) of the maximum point test force P' after storage to the initial maximum point test force P was calculated, and the flexural strength before and after the moisture absorption test was evaluated as follows. <Evaluation Criteria> ⊚: 0.9 or more ◯: 0.75 or more but less than 0.9 △: 0.5 or more but less than 0.75 ×: less than 0.5

[0072] [Components of Epoxy Resin Composition] ((A) Epoxy Resin Curing Agent) <Production Example 1> One equivalent of bisphenol A epoxy resin (jER828 manufactured by Mitsubishi Chemical Corporation) and one equivalent of 2-methylimidazole (converted to active hydrogen) were reacted at 80°C in a 1:1 mixed solvent of n-butanol and toluene. Thereafter, excess amine was distilled off together with the solvent under reduced pressure, yielding a block curing agent 1 that was solid at 25°C.

[0073] <Production Example 2-1: Epoxy Resin Curing Agent A-1> The block curing agent 1 obtained in Production Example 1 was roughly crushed to approximately 0.1 to 2 mm using a crusher "Rotoplex" (manufactured by Hosokawa Micron Corporation), and the resulting crushed material was crushed three times using an airflow jet mill (manufactured by Nisshin Engineering, CJ25 model) to obtain curing agent particles. The crushing was carried out at room temperature of 5°C and a humidity of 10% RH. The obtained curing agent particles were analyzed using a laser diffraction dry particle size distribution analyzer HELOS & RODOS, and the results are shown in Table 1 below. 100 parts by mass of the obtained curing agent particles were mixed with 200 parts by mass of bisphenol A-type epoxy resin (BE-186EL, manufactured by Chang Chun Synthetic Resin Co., Ltd.) and 20 parts by mass of tolylene diisocyanate (reagent), and the mixture was reacted at 40°C for 5 hours to microencapsulate the surface of the curing agent, thereby obtaining epoxy resin curing agent A-1.

[0074] <Production Example 2-2: Epoxy resin curing agent A-2> 100 parts by mass of the curing agent particles obtained in <Production Example 2-1> were mixed with 200 parts by mass of bisphenol F type epoxy resin (BFE-170 manufactured by Chang Chun Synthetic Resin Co., Ltd.) and 15 parts by mass of methylene diisocyanate (reagent), and the mixture was reacted at 45°C for 4 hours to microencapsulate the surface, thereby obtaining epoxy resin curing agent A-2.

[0075] <Production Example 2-3: Epoxy resin curing agent A-3> The block curing agent 1 obtained in <Production Example 1> above was roughly crushed to about 0.1 to 2 mm using a crusher "Rotoplex" (manufactured by Hosokawa Micron Corporation), and the obtained roughly crushed product was crushed once using an air jet mill (manufactured by Nisshin Engineering Inc., CJ25 model) to obtain a powdered epoxy resin curing agent. The room temperature during crushing was 5°C and the humidity was 10% RH. The obtained powdered epoxy resin curing agent was microencapsulated using the same procedure as in <Production Example 2-2> above to obtain epoxy resin curing agent A-3.

[0076] <Production Example 2-4: Epoxy resin curing agent A-4> The powder epoxy resin curing agent obtained by pulverizing, spheroidizing, and classifying in the same manner as in Example 7 of Japanese Patent No. 6283568 was microencapsulated in the same manner as in <Production Example 2-1> to obtain epoxy resin curing agent A-4. The room temperature during pulverization was 22°C and the humidity was 45% RH.

[0077] <Production Example 2-5: Epoxy resin curing agent A-5> The curing agent obtained by the method described in Production Example 4-4 of WO 2007 / 088889 was microencapsulated in the same manner as in <Production Example 2-1> to obtain epoxy resin curing agent A-5. The room temperature during pulverization was 22°C and the humidity was 45% RH.

[0078] <Production Example 2-6: Epoxy resin curing agent A-6> The block curing agent 1 obtained in <Production Example 1> above was roughly crushed to about 0.1 to 2 mm using a crusher "Rotoplex" (manufactured by Hosokawa Micron Corporation), and the obtained roughly crushed product was crushed three times using an air jet mill (manufactured by Nisshin Engineering, CJ25 model) to obtain a powdered epoxy resin curing agent. The room temperature during crushing was 22°C and the humidity was 45% RH. The obtained powdered epoxy resin curing agent was microencapsulated using the same procedure as in <Production Example 2-2> above to obtain epoxy resin curing agent A-6.

[0079]

[0080] <Epoxy resin curing agent A-7> 2-ethyl-4-methylimidazole (reagent)

[0081] (Method for measuring the area proportion of filler voids with a circle equivalent diameter of 5 μm or more and 40 μm or less in the cross section of a cured product containing epoxy resin curing agents A-1 to A-7) BisA type epoxy resin (jER828 manufactured by Mitsubishi Chemical Corporation), acid anhydride (methyl nadic anhydride, MHAC-P manufactured by Resonac Corporation), and spherical silica (SO-E2 manufactured by Admatechs Co., Ltd., D50 = 0.6 μm) were weighed out in the proportions shown in Table 2 below and stirred using a planetary centrifugal mixer (Thinky Corporation's Awatori Rentaro). After stirring, the epoxy resin curing agents (A-1 to A-6) manufactured in Production Examples 2-1 to 2-6 or epoxy resin curing agent (A-7) were added, and the mixture was again stirred using the planetary centrifugal mixer to obtain an epoxy resin composition. The resulting epoxy resin composition was poured into an aluminum cup with a handle (manufactured by AS ONE Corporation) and heated and cured for 60 minutes in a hot air drying oven heated to 150°C to produce a 5 mm thick cured product. The resulting cured product was cut with a diamond cutter, and the cut surface was polished under running water using waterproof abrasive paper (manufactured by Sankyo Rikagaku Co., Ltd.) with grit size 1000 and grit size 2000, in that order. The polished surface was then polished under running water using lapping film sheet #8000 (manufactured by 3M Corporation), and finally polished under running water using lapping film sheet #15000 (manufactured by 3M Corporation). With the polished surface facing up, the surface was gold-deposited and observed using an SEM at an applied voltage of 4.0 kV and a magnification of 1,000x. The resulting SEM image was binarized, and the filler void area ratio was calculated by averaging the filler void area ratio over three fields of view, using the filler void area ratio as the numerator and the area of ​​one field of view as the denominator. The circle equivalent diameter is the value obtained by dividing the circumference of the filler voids by the ratio of the circumference of the circle to its circumference (π).

[0082]

[0083] The area ratio of filler voids with a circle equivalent diameter of 5 μm or more and 40 μm or less, measured by the above-mentioned method, using each epoxy resin curing agent, is shown in the following Table 3. When curing agent A-7 was used, no filler voids with a circle equivalent diameter of 5 μm or more and 40 μm or less were observed.

[0084]

[0085] [Components of Epoxy Resin Composition] ((B) Epoxy Resin) B-1 jER828 (bisphenol A type epoxy resin manufactured by Mitsubishi Chemical Corporation) B-2 HP4032D (naphthalene type epoxy resin manufactured by DIC Corporation) B-3 Celloxide 2021P (alicyclic epoxy resin manufactured by Daicel Corporation)

[0086] ((C) Filler) C-1: SO-E2 (manufactured by Admatechs Co., Ltd., D10=0.2 μm, D50=0.5 μm, D90=1.1 μm) C-2: FB-40R (manufactured by Denka Co., Ltd., D10=16.3 μm, D50=40.4 μm, D90=75 μm) C-3: FB-20D (manufactured by Denka Co., Ltd., D10=3.8 μm, D50=19.4 μm, D90=45.2 μm)

[0087] ((D) Curing agent) D-1 HN-2200 (Acid anhydride manufactured by Rezoc Co., Ltd.) D-2 MHAC-P (Acid anhydride manufactured by Resonac Co., Ltd.)

[0088] ((E) Other Components) E-1 KBM-403 (silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd.) E-2 #2300 (carbon black manufactured by Mitsubishi Carbon Black Co., Ltd.)

[0089] [Preparation of Epoxy Resin Compositions] [Examples 1 to 5], [Comparative Examples 1 to 7] The components were weighed out in the proportions (parts by mass) shown in Table 4 below, and stirred using a Thinky Mixer to prepare epoxy resin compositions.

[0090] (Method for producing epoxy resin composition) The epoxy resin composition was produced by mixing and kneading the components. Mixing and kneading were carried out using an ARE-312 Awatori Rentaro (trade name, manufactured by Thinky Corporation). The kneading temperature varied depending on the viscosity of the epoxy resin composition and the filler concentration, but was generally between 10°C and 70°C.

[0091] (Method for producing a cured product) A 2 mm thick U-shaped Teflon mold was sandwiched between two aluminum plates, and the epoxy resin composition was poured into the mold. The mold was then kept in an oven at 150° C. for 1 hour to produce a cured product.

[0092] The evaluation results of the epoxy resin compositions and cured products of the examples and comparative examples are shown below.

[0093]

[0094] This application is based on a Japanese patent application (Patent Application No. 2024-123648) filed with the Japan Patent Office on July 30, 2024, the contents of which are incorporated herein by reference.

[0095] The epoxy resin curing agent of the present invention has industrial applicability as a curing agent for epoxy resin compositions used in semiconductor encapsulants and semiconductor packages.

Claims

1. An epoxy resin curing agent that satisfies the following <Condition 1>. <Condition 1> An epoxy resin composition containing 10 parts by mass of BisA epoxy resin, 9 parts by mass of methyl nadic anhydride, 30 parts by mass of spherical silica having a particle size (D50) value at 50% cumulative volume in the volume particle size distribution of 0.6 μm, and 1 part by mass of the epoxy resin curing agent, is cured at a temperature of 150°C for 60 minutes, and the area ratio of filler voids with a circular equivalent diameter of 5 μm to 40 μm present in the cross section of the cured product is 0.1 area % to 10.0 area %.

2. The epoxy resin curing agent according to claim 1, wherein the particle size (D10) at 10% cumulative volume in the volume particle size distribution is 0.1 μm or more and 0.8 μm or less, the particle size (D99) at 99% cumulative volume in the volume particle size distribution is 3 μm or more and 7 μm or less, and the curing agent contains particles that are solid at 25°C.

3. An epoxy resin curing agent containing particles that are solid at 25°C, with a particle size (D10) value at 10% cumulative volume in the volume particle size distribution of 0.1 μm or more and 0.8 μm or less, and a particle size (D99) value at 99% cumulative volume in the volume particle size distribution of 3 μm or more and 7 μm or less.

4. An epoxy resin composition comprising: (A) the epoxy resin curing agent according to any one of claims 1 to 3; (B) an epoxy resin; and (C) a filler.

5. The epoxy resin composition according to claim 4, comprising at least one curing agent (D) selected from the group consisting of acid anhydride curing agents, phenolic curing agents, thiol curing agents, active ester curing agents, amine curing agents, and amide curing agents.

6. The epoxy resin composition according to claim 4, wherein the volume ratio of the filler (C) is 40% by volume or more and 90% by volume or less.

7. The epoxy resin composition according to claim 5, wherein the volume ratio of the filler (C) is 40% by volume or more and 90% by volume or less.

8. The epoxy resin composition according to claim 4, wherein the filler (C) comprises particles having a diameter of 20 μm or more and 50 μm or less.

9. The epoxy resin composition according to claim 5, wherein the filler (C) comprises particles having a diameter of 20 μm or more and 50 μm or less.

10. The epoxy resin composition according to claim 6, wherein the filler (C) comprises particles having a diameter of 20 μm or more and 50 μm or less.

11. The epoxy resin composition according to claim 7, wherein the filler (C) comprises particles having a diameter of 20 μm or more and 50 μm or less.

12. A semiconductor encapsulant comprising the epoxy resin curing agent according to any one of claims 1 to 3.

13. A semiconductor package comprising the semiconductor encapsulant of claim 12.

14. A cured product of the epoxy resin composition according to claim 4.

15. A cured product of an epoxy resin composition containing an epoxy resin, an epoxy resin curing agent, and a filler, wherein the area ratio of filler voids with a circular equivalent diameter of 5 μm to 40 μm present in the cross section of the cured product is 0.1 area % to 10.0 area %.

16. A semiconductor package comprising the cured product according to claim 14.

17. An electronic device comprising the cured product of claim 14.

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