JP7584079B2 - Epoxy resin composition and optical semiconductor device - Google Patents

Description

The present disclosure relates to an epoxy resin composition and an optical semiconductor device, and more particularly to an epoxy resin composition containing an epoxy resin, a curing agent, and a filler, and an optical semiconductor device including an encapsulant made from this epoxy resin composition.

A photocoupler is an optical semiconductor device that transmits an optical signal from a light-emitting element, which is an optical semiconductor element, to a light-receiving element, thereby enabling the transmission of an electrical signal while maintaining electrical insulation. Conventional photocouplers are of the opposed type, in which the light-emitting element and the light-receiving element face each other, and the material used to seal the light-emitting element and the light-receiving element is generally a composition containing an epoxy resin and fused silica as a filler (see Patent Document 1).

JP 2009-29926 A

Since such opposed photocouplers have a complex structure and are costly to manufacture, recently, side-type photocouplers in which the light-emitting element and the light-receiving element are arranged in parallel have been considered. However, when the above-mentioned conventional sealing materials are used, the level of transmittance for the light transmitted from the light-emitting element to the light-receiving element is low, which is problematic in that the characteristics of the optical semiconductor device cannot be fully satisfied.

Although it is possible to improve the transmittance by reducing the amount of filler in the encapsulating material, the difference in the linear expansion coefficient between the encapsulating material and the packaging components of the optical semiconductor device becomes large, which can cause peeling inside the package after molding. The peeled areas are prone to oxidation, leading to discoloration and a decrease in transmittance. Therefore, it is necessary to improve the transmittance of the encapsulating material while maintaining a low linear expansion coefficient that matches the packaging components.

The objective of the present disclosure is to provide an epoxy resin composition that maintains a low linear expansion coefficient while having high transmittance when cured, and an optical semiconductor device that includes an encapsulant made from this epoxy resin composition.

The epoxy resin composition according to one embodiment of the present disclosure is an epoxy resin composition containing an epoxy resin (A), a curing agent (B) and a filler (C). The filler (C) contains crystalline silica (c1) and titanium oxide (c2).

The optical semiconductor device according to one aspect of the present disclosure includes an optical semiconductor element and an encapsulant that encapsulates the optical semiconductor element. The encapsulant includes a cured product of the resin composition.

According to the present disclosure, it is possible to provide an epoxy resin composition that maintains a low linear expansion coefficient while having high transmittance when cured, and an optical semiconductor device that includes an encapsulant made from this epoxy resin composition.

FIG. 1 is a schematic cross-sectional view of an optical semiconductor device according to an embodiment of the present disclosure.

1. Overview The epoxy resin composition according to this embodiment (hereinafter also referred to as composition (X)) contains an epoxy resin (A), a curing agent (B) and a filler (C). The filler (C) contains crystalline silica (c1) and titanium oxide (c2).

According to this embodiment, composition (X) can reduce the linear expansion coefficient, and can reduce the difference in linear expansion coefficient between the optical semiconductor device and the package member. Therefore, peeling is unlikely to occur inside the package during molding of the optical semiconductor device, and the decrease in transmittance caused by peeling can be suppressed. Furthermore, composition (X) can increase the transmittance of the cured product. Therefore, this composition (X) can be used as an encapsulating material in, for example, a side-type photocoupler, and the characteristics of the optical semiconductor device can be made fully satisfactory.

According to this embodiment, by using crystalline silica (c1) and titanium oxide (c2) as the filler (C), the linear expansion coefficient of the composition (X) can be reduced while increasing the transmittance of the cured product. The reason for this is presumed to be as follows. When the filler (C) is added to the epoxy resin composition to reduce the linear expansion coefficient, the transmittance generally decreases. However, the present inventors have found that when crystalline silica (c1) is used as the filler (C), the decrease in the linear expansion coefficient is reduced, but the decrease in the transmittance can be suppressed to a small extent. Furthermore, they have found that the transmittance can be increased by adding titanium oxide (c2) in addition to crystalline silica (c1). As a result, it is believed that the composition (X) can increase the transmittance of the cured product while maintaining a low linear expansion coefficient by containing crystalline silica (c1) and titanium oxide (c2) as the filler (C).

2. Details <Epoxy resin composition>
The composition (X) according to the present embodiment contains an epoxy resin (A), a curing agent (B), and a filler (C). The composition (X) may further contain additives other than the above components.

[Epoxy resin (A)]
The epoxy resin (A) is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule.

Examples of epoxy resins (A) include bisphenol-type epoxy resins, hydrogenated bisphenol-type epoxy resins, biphenyl-type epoxy resins, naphthalene ring-containing epoxy resins, alicyclic epoxy resins, dicyclopentadiene-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, triphenylmethane-type epoxy resins, aliphatic epoxy resins, triglycidyl isocyanurate, glycidyl group-containing silicone resins, and glycidylamine-type epoxy resins.

The ratio of epoxy resin (A) to the entire composition (X) is preferably 10% by mass or more and 50% by mass or less. In this case, the fluidity of composition (X) during molding and the physical properties of the produced encapsulant can be improved. This ratio is more preferably 20% by mass or more and 45% by mass or less.

[Curing agent (B)]
The curing agent (B) is not particularly limited as long as it is a compound capable of undergoing a curing reaction with the epoxy resin (A).

Examples of the curing agent (B) include phenol-based curing agents, acid anhydrides, amines, imidazoles, hydrazides, polymercaptans, Lewis acid-amine complexes, and the like. It is preferable that the curing agent (B) contains a phenol-based curing agent. Phenol-based curing agents have better curing properties than other curing agents, which can increase the strength of the produced sealing material.

Examples of phenol-based hardeners include novolac-type resins such as phenol novolac resin, cresol novolac resin, and naphthol novolac resin; aralkyl-type resins such as phenol aralkyl resins having a phenylene or biphenylene skeleton, and naphthol aralkyl resins having a phenylene or biphenylene skeleton; multifunctional phenol resins such as triphenol methane resin; dicyclopentadiene-type phenol resins such as dicyclopentadiene-type phenol novolac resin and dicyclopentadiene-type naphthol novolac resin; terpene-modified phenol resins; bisphenol-type resins such as bisphenol A and bisphenol F; and triazine-modified novolac resins.

The ratio of the curing agent (B) to the entire composition (X) is preferably 5% by mass or more and 30% by mass or less, and more preferably 10% by mass or more and 25% by mass or less.

The equivalent of the curing agent (B) to 1 equivalent of the epoxy resin (A) is, for example, 0.6 or more and 1.4 or less.

[Filler (C)]
The filler (C) contains crystalline silica (c1) and titanium oxide (c2). The filler (C) preferably further contains amorphous silica (c3). By including amorphous silica (c3) in the filler (C), the linear expansion coefficient of the composition (X) can be further reduced.

The average particle size of the filler (C) is the median diameter determined from the particle size distribution obtained from the measurement results by the laser diffraction/scattering method. The filler (C) may contain two or more components with different average particle sizes in order to adjust the physical properties of the composition (X).

The average ratio of the major axis to the minor axis of the filler (C) (hereinafter also referred to as the major axis/minor axis ratio) can be determined, for example, by observing the shapes of 50 random particles using a scanning electron microscope (SEM) and averaging the major axis/minor axis ratios of these particles. The filler (C) may contain two or more components with different major axis/minor axis ratios in order to adjust the physical properties of the composition (X).

(Crystalline Silica (c1))
The crystalline silica (c1) means crystalline _SiO2 , which has a maximum peak intensity at 2θ=30 to 32° in the XRD pattern, and commercially available crystalline silica can be used. The crystalline silica (c1) is usually in the form of particles.

The average particle size of the crystalline silica (c1) is preferably 5 μm or more and 40 μm or less, and more preferably 15 μm or more and 20 μm or less.

The long axis/short axis ratio of the crystalline silica (c1) is preferably 1.6 or less, more preferably 1.5, and even more preferably 1.4 or less. The long axis/short axis ratio may be, for example, 1.0 or more, 1.1 or more, 1.2 or more, or 1.3 or more. It is believed that by setting the long axis/short axis ratio of the crystalline silica (c1) within the above range, the degree of filling in the composition (X) can be further increased. This can further increase the transmittance of the cured product of the composition (X).

The proportion of crystalline silica (c1) in the entire composition (X) is preferably 5% by mass or more and 40% by mass or less. In this case, the transmittance of the cured product of composition (X) can be further increased. The proportion of crystalline silica (c1) is more preferably 6% by mass or more and 30% by mass or less, even more preferably 7% by mass or more and 26% by mass or less, and particularly preferably 8% by mass or more and 24% by mass or less.

(Titanium oxide (c2))
Titanium oxide (c2) refers to an oxide of titanium and is represented by the general formula TiOx (x = 1.0 to 2.0). Titanium oxide (c2) is usually in the form of particles.

The average particle size of titanium oxide (c2) is preferably 2 μm or less, more preferably 1 μm or less, even more preferably 0.7 μm or less, and particularly preferably 0.4 μm or less. When the average particle size of titanium oxide (c2) is 1 μm or less, the transmittance of the cured product of composition (X) can be particularly increased. The lower limit of the average particle size of titanium oxide (c2) is not particularly limited, but is, for example, 0.1 μm.

The proportion of titanium oxide (c2) in the entire composition (X) is preferably 1 mass% or less, more preferably 0.2 mass% or less, even more preferably 0.1 mass% or less, and particularly preferably 0.01 mass% or less. When the proportion of titanium oxide (c2) is 0.1 mass% or less, the transmittance of the cured product of composition (X) can be particularly increased. The proportion of titanium oxide (c2) is preferably 0.001 mass% or more, and more preferably 0.005 mass% or more.

(Amorphous Silica (c3))
Amorphous silica (c3) is composed of a network structure of Si-O and does not have a fixed crystal structure, and commercially available amorphous silica can be used. Amorphous silica (c3) is usually in the form of particles. Examples of amorphous silica (c3) include fused silica, spherical silica, and spherical fused silica. It is preferable that amorphous silica (c3) contains fused silica.

The average particle size of the amorphous silica (c3) is preferably 0.1 μm or more and 30 μm or less, and more preferably 20 μm or more and 30 μm or less.

The long axis/short axis ratio of amorphous silica (c3) is preferably 1.6 or less, more preferably 1.5 or less, and even more preferably 1.4 or less. The long axis/short axis ratio may be, for example, 1.0 or more, 1.1 or more, 1.2 or more, or 1.3 or more. By setting the long axis/short axis ratio of amorphous silica (c3) within the above range, the transmittance of the cured product of composition (X) can be further increased.

The difference in the long axis/short axis ratio between crystalline silica (c1) and amorphous silica (c3) is preferably 0.4 or less, more preferably 0.2 or less, even more preferably 0.1 or less, and particularly preferably 0. In this case, the transmittance of the cured product of composition (X) can be further increased.

The proportion of amorphous silica (c3) in the entire composition (X) is preferably 10% by mass or more and 60% by mass or less. In this case, the linear expansion coefficient of composition (X) can be further reduced. The proportion of amorphous silica (c3) is more preferably 15% by mass or more and 50% by mass or less, even more preferably 28% by mass or more and 48% by mass or less, and particularly preferably 35% by mass or more and 45% by mass or less.

The proportion of crystalline silica (c1) relative to the total of crystalline silica (c1) and amorphous silica (c3) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 35% by mass or more. This proportion is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and particularly preferably 45% by mass or less. By setting the proportion of crystalline silica (c1) within the above range, the transmittance of the cured product of composition (X) can be further increased.

The total ratio of crystalline silica (c1) and amorphous silica (c3) to the entire composition (X) is preferably 30% by mass or more and 80% by mass or less. In this case, the permeability of the cured product of composition (X) can be further increased. This ratio is more preferably 35% by mass or more and 70% by mass or less, even more preferably 35% by mass or more and 60% by mass or less, and particularly preferably 35% by mass or more and 45% by mass or less.

The filler (C) may contain components other than those mentioned above. Examples of the filler (C) other than those mentioned above include crushed silica, spherical alumina, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, talc, barium sulfate, calcium carbonate, mica powder, etc. The ratio of the filler (C) other than those mentioned above to the entire composition (X) is, for example, 0.01% by mass or more and 10% by mass or less.

The proportion of filler (C) in the entire composition (X) is preferably 30% by mass or more and 85% by mass or less. In this case, the transmittance of the cured product of composition (X) can be further increased. The proportion of filler (C) is more preferably 35% by mass or more and 70% by mass or less.

[Additives]
Composition (X) may contain additives other than the above components within the range that does not impair the effects of this embodiment. Examples of additives include a curing accelerator, a coupling agent, a release agent, a flame retardant, a flame retardant assistant, an ion trapping agent, a pigment such as carbon black, a colorant, a stress reducing agent, a tackifier, and a silicone flexibilizer.

Examples of the curing accelerator include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole; cycloamidines such as 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, and 5,6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene-7; tertiary amines such as 2-(dimethylaminomethyl)phenol, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; tributylphosphine, methyldiphenylphosphine, and the like. Examples of the curing accelerator include organic phosphines such as phenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, diphenylphosphine, an addition reaction product of triphenylphosphine and parabenzoquinone, and phenylphosphine; tetra-substituted phosphonium and tetra-substituted borates such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate; quaternary phosphonium salts having a counter anion other than borate; and tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate. The ratio of the curing accelerator to the entire composition (X) is, for example, 0.1% by mass or more and 2% by mass or less.

The coupling agent can improve the affinity of the filler (C) with the epoxy resin (A) and the curing agent (B). Examples of the coupling agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, and aluminum/zirconium coupling agents. Examples of the silane coupling agent include glycidoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; aminosilanes such as N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; alkylsilanes; ureidosilanes; and vinylsilanes. The ratio of the coupling agent to the total amount of the filler (C) and the coupling agent is, for example, 0.01% by mass or more and 1% by mass or less.

Examples of the release agent include carnauba wax, stearic acid, montanic acid, carboxyl group-containing polyolefin, ester wax, polyethylene oxide, metal soap, etc. The ratio of the release agent to the entire composition (X) is, for example, 0.01% by mass or more and 1% by mass or less.

Examples of flame retardants include magnesium hydroxide, aluminum hydroxide, red phosphorus, etc.

Colorants include, for example, carbon black, red iron oxide, titanium oxide, phthalocyanine, perylene black, etc.

Examples of stress reducing agents include silicone elastomers, silicone resins, silicone oils, butadiene-based rubbers, etc. Examples of butadiene-based rubbers include methyl acrylate-butadiene-styrene copolymers, methyl methacrylate-butadiene-styrene copolymers, etc.

Composition (X) can be suitably used for sealing semiconductor devices, and is particularly suitable for sealing optical semiconductor elements in optical semiconductor devices.

<Production method of composition>
The composition (X) can be prepared, for example, by mixing the components of the composition (X). More specifically, for example, raw materials including the epoxy resin (A), the curing agent (B) and the filler (C) are mixed in a mixer, blender or the like until they are sufficiently uniform, and then melt-mixed in a heated state using a kneading machine such as a heat roll or a kneader, and then cooled to room temperature. The mixture thus obtained is pulverized by a known means to produce the powdered composition (X). The composition (X) does not have to be in a powder form, and may be, for example, in a tablet form. When the composition (X) is in a tablet form, it is preferable that the size and mass of the composition (X) are suitable for the molding conditions.

<Characteristics>
The composition (X) is preferably solid at 25° C. In this case, the composition (X) can be molded by a pressure molding method such as injection molding, transfer molding, or compression molding to produce an encapsulant. It is more preferable that the composition (X) is solid at any temperature in the range of 15° C. to 25° C., and further more preferable that the composition (X) is solid at any temperature in the range of 5° C. to 35° C.

The transmittance of light having a wavelength of 800 nm or more and 980 nm or less in the cured product of composition (X) is preferably 20% or more. In this case, even if the cured product of composition (X) is used as an encapsulant for a side-type photocoupler or the like, the characteristics of the optical semiconductor device can be fully satisfactory. The transmittance is more preferably 30% or more, even more preferably 35% or more, particularly preferably 40% or more, and most preferably 45% or more. The upper limit of the transmittance is not particularly limited, but is, for example, 60%. The transmittance of composition (X) is the value when the thickness of the cured product obtained by curing is 1 mm.

The linear expansion coefficient of the cured product of composition (X) is preferably 40 ppm/°C or less. In this case, the difference in linear expansion coefficient between the lead frame member of the optical semiconductor device, which usually has a linear expansion coefficient of 15 to 20 ppm/°C, and the cured product can be made smaller. This makes it possible to suppress the occurrence of peeling inside the package during molding of the optical semiconductor device, and to suppress discoloration due to oxidation caused by peeling, thereby increasing the transmittance. The linear expansion coefficient is more preferably 30 ppm/°C or less, and even more preferably 25 ppm/°C or less. In addition, the linear expansion coefficient is preferably 15 ppm/°C or more.

The spiral flow length of composition (X) is preferably 90 cm or more. In this case, composition (X) is likely to have particularly good moldability. The spiral flow length is more preferably 100 cm or more, and even more preferably 120 cm or more. The upper limit of the spiral flow length is not particularly limited, but is, for example, 200 cm.

The gel time of composition (X) is preferably 40 seconds or less. In this case, the molding cycle for producing the encapsulant can be shortened, and the productivity of the optical semiconductor device can be increased. The lower limit of the gel time is not particularly limited, but is, for example, 20 seconds.

Details of the methods for measuring the transmittance, linear expansion coefficient, spiral flow length, and gel time will be explained in the Examples section below.

<Optical semiconductor device>
The optical semiconductor device according to the present embodiment includes an optical semiconductor element and an encapsulant that encapsulates the optical semiconductor element. The encapsulant includes a cured product of a composition (X).

Figure 1 shows a cross-sectional view of an example of a side-type photocoupler, which is an optical semiconductor device 1. This optical semiconductor device 1 includes a light-emitting element 4 and a light-receiving element 5 as optical semiconductor elements 3, 3, an encapsulant 2 that encapsulates the optical semiconductor elements 3, 3, two lead frames 6, 6 that are conductors connected to the optical semiconductor elements 3, 3, and a highly reflective resin layer 7 that covers the encapsulant 2.

The encapsulant 2 includes a cured product of the composition (X). The light-emitting element 4 may be, for example, a light-emitting diode. The light-receiving element 5 may be, for example, a photodiode. The highly reflective resin layer 7 is formed from a resin having a reflectance of, for example, 70% or more. The optical semiconductor elements 3, 3 in the optical semiconductor device 1 can be encapsulated, for example, by injecting the composition (X) into a predetermined mold and curing it by heating under predetermined conditions. This provides an optical semiconductor device 1 in which the optical semiconductor elements 3, 3 are encapsulated by the cured product of the composition (X).

The structure of the optical semiconductor device 1 is not limited to that shown in FIG. 1, and the optical semiconductor device 1 may include an optical semiconductor element 3 and an encapsulant 2 that encapsulates the optical semiconductor element 3. The optical semiconductor device 1 may not include, for example, a highly reflective resin layer 7. In addition, the light-emitting element 4 and the light-receiving element 5 do not need to be arranged in parallel, and may be, for example, in a face-to-face structure.

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited to these examples.

1. Preparation of Composition The raw materials shown in Table 1 were mixed and uniformly dispersed in a mixer, and then heated and kneaded at a material temperature of 120°C using a twin-screw kneader to obtain a mixture. The mixture was then cooled and pulverized. The obtained powder was then tableted to obtain a tablet-shaped composition. The details of the raw materials are as follows.
- Epoxy resin: cresol novolac type epoxy resin. Epoxy equivalent: 195 g/eq.
- Hardener: Phenol-based hardener. Phenol novolac resin. OH equivalent: 105 g/eq.
- Filling material:
- Crystalline silica 1 (major axis/minor axis ratio = 1.3): average particle size 18 μm.
- Crystalline silica 2 (major axis/minor axis ratio = 1.5): average particle size 15 μm.
- Amorphous silica 1 (major axis/minor axis ratio = 1.1): average particle size 20 μm.
- Amorphous silica 2 (major axis/minor axis ratio = 1.3): average particle size 20 μm.
- Amorphous silica 3 (major axis/minor axis ratio = 1.5): average particle size 30 μm.
Titanium oxide: average particle size 0.3 μm.
- Curing accelerator: triphenylphosphine.
- Release agent: natural carnauba.
Coupling agent: Silane coupling agent. 3-glycidoxypropylmethyldiethoxysilane.

2. Evaluation (1) Transmittance Using a transfer molding machine (manufactured by Shinto Metal Industries Co., Ltd.), the composition was molded by transfer molding under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and then post-cured by heating at 175°C for 6 hours to produce a disk-shaped cured product with a diameter of 50 mm and a thickness of 1 mm. The light transmittance of this cured product at a wavelength of 940 nm was measured using a spectrophotometer (MPC-3100 manufactured by Shimadzu Corporation).

(2) Linear expansion coefficient Using a transfer molding machine (manufactured by Shinto Metal Industries Co., Ltd.), the composition was molded by transfer molding under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and then post-cured by heating at 175°C for 6 hours to prepare a test piece having a dimension of 5 mmΦ x 30 mm. Using a horizontal thermal dilatometer (DLY-9000 manufactured by Advance Riko Co., Ltd.), the test piece was heated from 20°C to 280°C at a rate of 5°C per minute, and the average linear expansion coefficient of the test piece in the length direction from 80°C to 100°C was measured.

(3) Spiral Flow Length Using a transfer molding machine (manufactured by Shinto Metal Works, Ltd.), the composition was injected into a dedicated spiral flow mold produced based on ASRM D 3123 under conditions of a mold temperature of 175° C., an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and the length of the composition that flowed was measured.

(4) Gel Time Using a Curastometer (Curastometer III PS type manufactured by JSR Corporation), the torque value of the composition was measured while heating it at 175° C. The time until the torque value reached 4.9 N/m (0.5 kgf cm) was defined as the gel time.

The results of the above evaluation are shown in Table 1.

Claims (7)

An epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and a filler (C),
The filler (C) contains crystalline silica (c1) and titanium oxide (c2),
The average particle size of the titanium oxide (c2) is 1 μm or less,
The ratio of the titanium oxide (c2) is 0.1 mass% or less,
The average ratio of the major axis to the minor axis of the crystalline silica (c1) is 1.2 or more and 1.6 or less;
The epoxy resin composition, wherein the proportion of the filler (C) is 35% by mass or more and 70% by mass or less. The epoxy resin composition according to claim 1, wherein the filler (C) further contains amorphous silica (c3). The epoxy resin composition according to claim 2, wherein the average ratio of the long axis to the short axis of the amorphous silica (c3) is 1.0 or more and 1.5 or less. The epoxy resin composition according to claim 2 or 3, wherein the proportion of the crystalline silica (c1) is 10% by mass or more and 70% by mass or less based on the total of the crystalline silica (c1) and the amorphous silica (c3). 5. The epoxy resin composition according to claim 2, wherein a total proportion of the crystalline silica (c1) and the amorphous silica (c3) is 30% by mass or more and 60 % by mass or less. An epoxy resin composition according to any one of claims 1 to 5, in which the transmittance of light having a wavelength of 800 nm or more and 980 nm or less is 30% or more when the thickness of the cured product obtained by curing is 1 mm. An optical semiconductor element;
and a sealing material that seals the optical semiconductor element,
An optical semiconductor device, wherein the encapsulant comprises a cured product of the epoxy resin composition according to claim 1 .

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