JP2016079344A - Thermosetting epoxy resin composition for primary encapsulation of photocoupler, and optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting epoxy resin composition for primary encapsulation of a photocoupler excellent in handling ability, heat resistance, light resistance, and light transmissivity, and an optical semiconductor device using the same.SOLUTION: The epoxy resin composition includes: a prepolymer (A) obtained by reacting a triazine derivative epoxy resin (A-1) with an acid anhydride (A-2) by a ratio (an epoxy group equivalent/an acid anhydride equivalent) of 0.6-2.0; an inorganic filler (B); a curing accelerator (C); an antioxidant (D), where the average particle size of the inorganic filler (B) is 5-30 μm and the maximum particle size is not greater than 53 μm, and the light transmissivity of the cured product of the epoxy resin composition having a thickness of 0.35 mm after secondary curing is not less than 40% at 740 nm.SELECTED DRAWING: None

Description

  The present invention relates to a thermosetting epoxy resin composition for primary encapsulation of a photocoupler and an optical semiconductor device using the same.

  A photocoupler is a device that combines a light-emitting element and a light-receiving element that converts an input electrical signal into light by a light-emitting element and transmits the light by transmitting the light to the light-receiving element. For this reason, it is important to efficiently transmit light from the light emitting side to the light receiving side. Moreover, it often has a double structure in order to block light from the outside and impart moisture resistance reliability and flame retardancy. That is, the light emitting element is sealed with a primary sealing resin having light transmission ability, and subsequently sealed with a secondary sealing resin having a light shielding property. Conventionally, a silicone resin has been used for the primary sealing resin, and an epoxy resin has been used for the secondary sealing resin. On the other hand, in recent years, for the purpose of cost reduction, only the periphery of a light receiving element or a light emitting element is sealed with a silicone resin, and then an epoxy resin is applied as a primary sealing resin.

  The efficiency of the photocoupler is expressed by CTR (Current Transfer Ratio) and can be obtained by the ratio of the current on the light emitting side and the electromotive force on the light receiving side. In order to obtain a high CTR value, a high light transmittance with near infrared light in the vicinity of 700 nm to 1,000 nm is necessary.

  Patent Document 1 shows that an epoxy resin composition excellent in reliability and light transmittance is used for a photocoupler. In order to obtain a high CTR value, it has been shown that reduction of light absorption by a metal material and light scattering by fused spherical silica are important. With the improvement of the performance of the photocoupler, the fused spherical silica that has been conventionally used as an inorganic filler certainly increases the light transmittance of the resin composition by increasing the scattering of light. However, since the refractive indices of resin components such as fused silica and aromatic resin-rich epoxy resins and curing agents are greatly different, a resin composition using them cannot obtain sufficient light transmittance.

  Patent Document 2 discloses a material that uses a bisphenol A type epoxy resin and an alicyclic epoxy resin in combination as an epoxy resin composition and uses an acid anhydride as a curing agent in order to obtain high transmittance. According to this, there is a description that colorless transparency and high fluidity can be obtained, but it is composed of only a resin component, has a high water absorption rate, and is inferior in moisture resistance reliability. In addition, there is a problem that the amount of thermal expansion is large and defects due to imbalance of the thermal expansion coefficient with the secondary sealing resin are likely to occur, and it is difficult to solidify and tablet stably.

  Patent Document 3 discloses a material in which the refractive index of the resin component and the inorganic filler is made close to obtain high transmittance even if the inorganic filler is contained for moldability and low thermal expansion coefficient. . However, the curing agent used here is an aromatic one such as a phenol novolac or a cresol novolac curing agent. In recent years, due to higher output of light-emitting elements and higher temperature of use environment, such primary sealing resin is severely deteriorated, and CTR value is lowered due to coloring or the like, and satisfactory results cannot be obtained.

JP-A-62-108,583 Japanese Patent No. 2,970,214 JP-A-6-25,386

  The present invention has been made to solve the above problems, and provides a thermosetting epoxy resin composition for primary sealing of a photocoupler excellent in handling properties, heat resistance, light resistance and light transmittance. The purpose is to do. Another object of the present invention is to provide an optical semiconductor device using the composition.

As a result of intensive studies to solve the above problems, the present inventors have found that the following thermosetting epoxy resin composition is a photocoupler primary sealing resin that can achieve the above-mentioned object, and completed.
That is, the present invention provides the following thermosetting epoxy resin composition for primary sealing of a photocoupler and a semiconductor device using the same.

[1] (A) (A-1) Triazine derivative epoxy resin and (A-2) acid anhydride are reacted at a ratio of epoxy group equivalent / acid anhydride group equivalent: 0.6 to 2.0. An epoxy resin composition comprising a prepolymer obtained by (B) an inorganic filler, (C) a curing accelerator, and (D) an antioxidant,
(B) The average particle size of the inorganic filler is 5 to 30 μm, and the maximum particle size is 53 μm or less,
A thermosetting epoxy resin composition for primary sealing of a photocoupler, in which a light transmittance at 740 nm of a 0.35 mm thick cured product after secondary curing of the epoxy resin composition is 40% or more.

[2] The thermosetting epoxy resin composition for primary encapsulation of a photocoupler according to [1], wherein the (A-1) triazine derivative epoxy resin is a 1,3,5-triazine derivative epoxy resin.

[3] The prepolymer of the component (A) is represented by the following general formula (1):

(In the formula, R represents an acid anhydride residue, and n is a number from 0 to 200.)

The thermosetting epoxy resin composition for primary sealing of a photocoupler according to [1] or [2], which comprises a compound represented by the formula:

[4] The thermosetting epoxy resin composition for primary sealing of a photocoupler according to any one of [1] to [3], wherein the inorganic filler (B) is spherical silica or glass particles.

[5] (D) The antioxidant is one or more selected from the group consisting of phenolic antioxidants, phosphorus antioxidants and sulfur antioxidants [1] to [4] The thermosetting epoxy resin composition for primary sealing of a photocoupler according to any one of the above.

[6] A photocoupler sealed with the thermosetting epoxy resin composition for primary sealing of a photocoupler according to any one of [1] to [5].

[7] An optical semiconductor device having the photocoupler according to [6].

  ADVANTAGE OF THE INVENTION According to this invention, the thermosetting epoxy resin composition for photocoupler primary sealing excellent in handling property, heat resistance, light resistance, and light transmittance can be provided. Moreover, the optical semiconductor device using the hardened | cured material of this composition can be provided.

  Hereinafter, the thermosetting epoxy resin composition for primary encapsulation of a photocoupler of the present invention and an optical semiconductor device using the same will be described in detail, but the present invention is not limited thereto.

<Thermosetting epoxy resin composition for primary sealing of photocoupler>
(A) Prepolymer The (A) component prepolymer comprises (A-1) a triazine derivative epoxy resin and (A-2) an acid anhydride, epoxy group equivalent / acid anhydride group equivalent: 0.6 to It is obtained by reacting at a ratio of 2.0.

(A-1) Triazine derivative epoxy resin The triazine derivative epoxy resin of the component (A-1) used in the present invention reacts with an acid anhydride at a specific ratio to suppress yellowing of the cured product. And a thermosetting epoxy resin composition with little deterioration over time. Moreover, when it becomes solid, handling of the thermosetting epoxy resin manufactured by kneading | mixing etc. becomes easy. As the (A-1) component triazine derivative epoxy resin, 1,3,5-triazine nucleus derivative epoxy resin is preferable. In particular, an epoxy resin having an isocyanurate ring is excellent in light resistance and electrical insulation, and preferably has a divalent, more preferably a trivalent epoxy group with respect to one isocyanurate ring. Specific examples include tris (2,3-epoxypropyl) isocyanurate, tris (α-methylglycidyl) isocyanurate, tris (α-methylglycidyl) isocyanurate, and the like.

  The softening point of the triazine derivative epoxy resin used in the present invention is preferably 40 to 125 ° C. In the present invention, the triazine derivative epoxy resin does not include a hydrogenated triazine ring.

(A-2) Acid anhydride The acid anhydride of the component (A-2) used in the present invention acts as a curing agent, is non-aromatic for improving heat resistance and light resistance, and Those having no carbon-carbon double bond are preferred, and examples thereof include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, and hydrogenated methylnadic anhydride. Among these, Preferred are hexahydrophthalic anhydride and / or methylhexahydrophthalic anhydride. These acid anhydride curing agents may be used alone or in combination of two or more.

  (A-2) As a compounding quantity of an acid anhydride, the total epoxy groups in (A-1) triazine derivative epoxy resin are 0.6-2 with respect to 1 mol of above-mentioned (A-2) acid anhydride groups. 0.0 mol, preferably 0.8 to 2.0 mol, more preferably 1.0 to 1.8 mol. If (the total number of moles of epoxy groups) / (the number of moles of acid anhydride) is less than 0.6, the unreacted curing agent may remain in the cured product, which may deteriorate the moisture resistance of the resulting cured product. On the other hand, if it is 2.0 or more, poor curing may occur and reliability may be lowered.

The (A) component prepolymer comprises (A-1) a triazine derivative epoxy resin and (A-2) an acid anhydride [(A-1) component has an epoxy group] / [(A-2) component is It is obtained by blending at a molar ratio of 0.6 to 2.0, and heating and mixing. The prepolymer of the component (A) is a solid product obtained by reacting the components (A-1) and (A-2) as components (C) in the presence of the same curing accelerator as described later. (Prepolymer) may be used.
The obtained solid product is preferably used in a fine powder state by pulverization or the like. The particle diameter of the fine powder is preferably in the range of 5 μm to 3 mm. The molar ratio is preferably 1.0 to 1.8. If this molar ratio is less than 0.6, an unreacted curing agent may remain in the cured product and deteriorate the moisture resistance of the resulting cured product. On the other hand, if it is 2.0 or more, poor curing may occur and reliability may be lowered.

  When synthesizing the prepolymer, an epoxy resin other than the component (A-1) can be used in combination with a certain amount or less as long as the effects of the present invention are not impaired. Examples of this epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, 3,3 ′, 5,5′-tetramethyl-4,4′-biphenol type epoxy resin, and 4,4′-biphenol type epoxy. Biphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin, naphthalenediol type epoxy resin, trisphenylol methane type epoxy resin, tetrakisphenylol ethane type epoxy resin, And an epoxy resin obtained by hydrogenating an aromatic ring of a phenol dicyclopentadiene novolac type epoxy resin, an alicyclic epoxy resin, and the like. Among these epoxy resins, bisphenol A type epoxy resin, bisphenol F type epoxy resin, epoxy resin with hydrogenated aromatic ring, alicyclic epoxy resin, and silicone-modified epoxy resin are desirable from the viewpoint of heat resistance and light resistance. Further, the softening point of other epoxy resins is preferably 50 to 100 ° C. in order to facilitate prepolymerization or from the viewpoint of handling.

  The prepolymer is obtained by reacting the component (A-1) and the component (A-2) at 60 to 120 ° C., preferably 70 to 110 ° C. for 4 to 20 hours, preferably 6 to 15 hours. can get. Alternatively, the curing accelerators of the component (A-1), the component (A-2) and the component (C) are previously added at 30 to 80 ° C., preferably 40 to 70 ° C. for 2 to 12 hours, preferably 3 to 8 hours. You may make it react for hours. Thus, the prepolymer is obtained as a solid product having a softening point of 40 to 100 ° C., preferably 45 to 70 ° C. In order to mix this with the composition of the present invention, it is preferable to make it fine powder by pulverization or the like. If the softening point of the substance obtained by the reaction is less than 40 ° C., it does not become a solid, and if it exceeds 100 ° C., the fluidity required at the time of molding as a composition may not be obtained.

  As said prepolymer, the compound shown by following formula (1) is mentioned, for example.

(In the formula, R represents an acid anhydride residue, and n is a number from 0 to 200.)

  The component (A) is preferably contained in the composition of the present invention in an amount of 10 to 40% by mass, more preferably 12 to 35% by mass, and particularly preferably 15 to 30% by mass.

(B) Inorganic filler An inorganic filler is mix | blended with the thermosetting epoxy resin composition of this invention. As such an inorganic filler, what is normally mix | blended with an epoxy resin composition is mentioned. For example, silicas such as fused silica and crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, antimony trioxide, glass particles and the like can be mentioned. From the viewpoint of close refractive index and fluidity, spherical silica and Glass particles are desirable. In particular, fused spherical silica and spherical glass particles are suitably used as the inorganic filler, and fused spherical silica is preferred from the viewpoints of moldability, fluidity, burrs, and transmittance.
The average particle size of the inorganic filler is preferably 5 to 30 μm, particularly preferably 7 to 25 μm. When the average particle size is less than 5 μm, the viscosity is greatly increased, not only the fluidity is decreased, but also the transmittance is decreased. If the average particle size is larger than 30 μm or the maximum particle size is larger than 53 μm, very many burrs are generated. Those having an average particle size of 5 to 30 μm and a maximum particle size of less than 53 μm are commercially available or can be produced by known methods. The maximum particle size is 53 μm or less, more preferably 48 μm or less, and particularly preferably 43 μm or less. Furthermore, in order to make the resin composition highly fluid, it is preferable to use a combination of a fine region of 0.1 to 3 μm, a medium particle size region of 4 to 8 μm, and a coarse region of 10 to 50 μm. The average particle size is one calculated as a cumulative weight average value D _{50 (or} median diameter) in particle size distribution measurement by laser diffraction method.

  The inorganic filler of the component (B) increases the bond strength with the resin component of the component (A), improves the adhesion between the inorganic filler and the resin component, increases the strength of the molded product, You may use what was surface-treated beforehand with coupling agents, such as a silane coupling agent and a titanate coupling agent, in order to prevent attenuation | damping.

  Examples of such a coupling agent include epoxy functions such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. Functional alkoxysilanes such as N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercapto Suitable examples include mercapto-functional alkoxysilanes such as propyltrimethoxysilane. In addition, the usage-amount of the coupling agent used for surface treatment and the surface treatment method should just follow a conventional method. The coupling agent is preferably one in which the treated filler does not discolor when left at 150 ° C. or higher.

  (B) The compounding quantity of the inorganic filler which is a component is 80-800 mass parts with respect to 100 mass parts of (A) component, It is preferable to set it as 200-600 mass parts especially. If it is less than 80 parts by mass, sufficient strength may not be obtained. If it exceeds 800 parts by mass, unfilled defects due to thickening and flexibility will be lost, resulting in defects such as peeling in the element. There is a case.

(C) Curing accelerator The curing accelerator of component (C) is blended to cure the thermosetting epoxy resin. As the curing accelerator, those known as curing catalysts for epoxy resin compositions can be used, and are not particularly limited, but include tertiary amines, imidazoles, their organic carboxylates, organic carboxylic acid metal salts, metal- Examples thereof include phosphorus-based curing catalysts such as organic chelate compounds, aromatic sulfonium salts, organic phosphine compounds and phosphonium compounds, and one or more of these salts. Among these, imidazoles, phosphorus-based curing catalysts such as 2-ethyl-4-methylimidazole or methyltributylphosphonium dimethyl phosphate, octylates of tertiary amines, and quaternary phosphonium bromides are preferably used.

  The amount of the curing accelerator used is preferably in the range of 0.05 to 5% by mass, particularly 0.1 to 2.0% by mass with respect to the total of component (A). If it is out of the above range, the balance of heat resistance and moisture resistance of the cured product of the epoxy resin composition may be deteriorated, or curing at the time of molding may be very slow or fast.

(D) Antioxidant The thermosetting epoxy resin composition of this invention mix | blends (D) antioxidant for the initial stage transmittance | permeability improvement and long-term transmittance | permeability maintenance. (D) As an antioxidant of a component, a phenolic antioxidant, phosphorus antioxidant, and sulfur type antioxidant are mentioned, The following are mentioned as a specific example of antioxidant.

  Examples of phenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-p-ethylphenol, stearyl-β- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] 2,4,8,10-tetraoxaspiro [ 5,5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-t-butyl-4-hydroxybenzyl) benzene and the like.

  Phosphorus antioxidants include triphenyl phosphite, diphenylalkyl phosphite, phenyl dialkyl phosphite, tri (nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, triphenyl phosphite , Distearyl pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol diphosphite, di (2,4-di-tert-butylphenyl) pentaerythritol diphosphite , Tristearyl sorbitol triphosphite, tetrakis (2,4-di-tert-butylphenyl) -4,4′-biphenyl diphosphonate and the like.

  Examples of sulfur-based antioxidants include diuraryl thiopropionate, distearyl thiopropionate, dibenzyl disulfide, and trisnonylphenyl phosphite.

  These antioxidants can be used alone or in combination of two or more. The blending amount of the antioxidant is preferably 0.01 to 10% by mass, particularly preferably 0.1 to 8% by mass with respect to the component (A). If the amount is too small, sufficient heat resistance may not be obtained and discoloration may occur, while if too large, curing inhibition may occur, and sufficient curability and strength may not be obtained.

  In addition to the above components (A) to (D), the composition of the present invention may further contain the following components.

(E) Release agent A release agent can be mix | blended with the thermosetting epoxy resin composition of this invention. (E) The mold release agent of a component is mix | blended in order to improve the mold release property at the time of shaping | molding.

  Mold release agents include natural waxes such as carnauba wax, synthetic waxes such as acid wax, polyethylene wax, and fatty acid ester. Generally, yellowing easily occurs under high temperature conditions or under light irradiation. In many cases, glycerin derivatives and fatty acid esters with little discoloration or carnauba wax with little discoloration over time, although having little color change, are preferred. Particularly preferred is glycerin monostearate from the viewpoint of not reducing transparency.

  The amount of the release agent (E) added is preferably 0.05 to 7.0% by mass, particularly 0.1 to 5.0% by mass, based on the total amount of the component (A). When the addition amount is less than 0.05% by mass, sufficient releasability may not be obtained. When the addition amount exceeds 7.0% by mass, a squeeze out defect or poor adhesion may occur.

(F) Coupling agent The thermosetting epoxy resin composition of the present invention is blended with a coupling agent such as a silane coupling agent or a titanate coupling agent in order to increase the bond strength between the resin and the inorganic filler. be able to.

  Examples of such a coupling agent include epoxy functions such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. It is preferable to use a mercapto functional alkoxysilane such as a functional alkoxysilane or γ-mercaptopropyltrimethoxysilane. The amount of the coupling agent used for the surface treatment and the surface treatment method are not particularly limited, but the resin discolors when left at 150 ° C. or more like an amine-based silane coupling agent. Is less preferred.

  The blending amount of the component (F) is preferably 0.1 to 8.0% by weight, and particularly preferably 0.5 to 6.0% by weight with respect to the component (A). If it is less than 0.1% by weight, the adhesion effect to the substrate is not sufficient, and if it exceeds 8.0% by weight, the viscosity is extremely lowered, which may cause voids.

Other Additives Various additives can be further blended in the thermosetting epoxy resin composition of the present invention as necessary. For example, for the purpose of improving the properties of the resin, additives such as glass fiber and potassium titanate, reinforcing materials such as silicone powder, silicone oil, thermoplastic resin, thermoplastic elastomer, organic synthetic rubber, and light stabilizer are used in the present invention. It can be added and blended as long as the effect is not impaired.

  In the thermosetting epoxy composition of the present invention, an epoxy resin, an inorganic filler, a curing catalyst, an antioxidant and other additives are blended at a predetermined composition ratio, and after mixing this sufficiently uniformly by a mixer or the like, a heat roll Then, the mixture can be melt-mixed by a kneader, an extruder, etc., then cooled and solidified, and pulverized to an appropriate size to obtain a molding material for a thermosetting epoxy resin composition. At this time, it is desirable that the epoxy resin is prepolymerized as a solid product from the viewpoint of handling.

  When not used for the preparation of the solid (reactant), the curing accelerator of component (C) and other additives as necessary are blended in a predetermined composition ratio, and after mixing this sufficiently with a mixer, etc., heat It can be melt-mixed with a roll, kneader, extruder, etc., then cooled and solidified, and pulverized to an appropriate size to form a molding material for the epoxy resin composition.

The most common molding method for the sealing material includes a transfer molding method and a compression molding method. In the transfer molding method, using a transfer molding machine, a molding pressure of 5 to 20 N / mm ² , a molding temperature of 120 to 190 ° C., a molding time of 30 to 500 seconds, particularly a molding temperature of 150 to 185 ° C. and a molding time of 30 to 180 seconds. Preferably it is done. In the compression molding method, a compression molding machine is used, and the molding temperature is preferably 120 to 190 ° C., the molding time is 30 to 600 seconds, and the molding temperature is preferably 130 to 160 ° C. and the molding time is 120 to 300 seconds. Further, in any molding method, post-curing may be performed at 150 to 185 ° C. for 0.5 to 20 hours.

  In order to improve the light transmission efficiency of the photocoupler, it is necessary that the primary sealing resin having light transmission ability has good light transmittance. In the present invention, the light transmittance at 740 nm of a 0.35 mm thick cured product of the thermosetting epoxy resin composition needs to be 40% or more. The light transmittance is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more. The measurement of the light transmittance is not limited as long as it can measure the light transmittance of a spectrophotometer or the like. When a photocoupler package is assembled using an epoxy resin composition having a light transmittance lower than the lower limit, the light transmission ability of the photocoupler decreases, and sufficient optical characteristics of the photocoupler cannot be obtained. In order to set the light transmittance to 40% or more, from the viewpoint of refractive index, the prepolymer is not used with a compound having an aromatic ring, and only a triazine derivative epoxy resin and an acid anhydride are used as much as possible. From the viewpoint of uniformity of properties, it is preferable to melt and mix a premixed component such as a prepolymer whose particles have been finely divided before the melt mixing so as to be as uniform as possible.

  The thermosetting epoxy resin composition of the present invention can also be used for sealing a normal semiconductor sealing material, various on-vehicle modules, and the like. In that case, carbon black or the like is used as a colorant. Any carbon black may be used as long as it is commercially available, but it is desirable that the carbon black has good purity and does not contain much alkali metal or halogen.

  EXAMPLES Hereinafter, although the Example and comparative example of the thermosetting epoxy resin composition of this invention are shown and this invention is demonstrated in detail, this invention is not limited to these.

  The materials and methods used in the examples and comparative examples are shown below.

(A) Prepolymer (A-1) Triazine derivative epoxy resin (A-1-1): Tris (2,3-epoxypropyl) isocyanurate (trade name TEPIC-S: manufactured by Nissan Chemical Co., Ltd.)
(A-2) Acid anhydride (A-2-1): Methylhexahydrophthalic anhydride (trade name Ricacid MH: manufactured by Shin Nippon Rika Co., Ltd.)
(A-2-2): Hexahydrophthalic anhydride (trade name: Ricacid HH: manufactured by Shin Nippon Rika Co., Ltd.)
(A-3) Epoxy resins other than triazine derivative epoxy resin (A-3-1): Orthocresol novolac type epoxy resin (trade name: EOCN-1020-55, manufactured by Nippon Kayaku Co., Ltd.)
(A-3-2): Bisphenol A type epoxy resin (trade name: jER-1001, manufactured by Mitsubishi Chemical Corporation)
(A-4) Phenol curing agent (A-4-1): Novolac type phenol resin (trade name: TD-2131, manufactured by DIC Corporation)
(A-4-2): Aralkyl type phenol resin (trade name: XLC-4L, manufactured by Mitsui Chemicals, Inc.)

(B) Inorganic filler (B-1): Fused spherical silica (trade name: RS-8225 / 53C, average 10 μm, manufactured by Tatsumori)

(C) Curing accelerator (C-1): Phosphorus curing catalyst; quaternary phosphonium bromide (trade name: U-CAT5003, manufactured by San Apro Co., Ltd.)
(C-2): 2-ethyl-4-methylimidazole (trade name: 2E4MZ, Shikoku Kasei Kogyo Co., Ltd.)

(D) Antioxidant (D-1): Phosphite type antioxidant (trade name: PEP-8, manufactured by ADEKA Corporation)

(E) Release agent (E-1): Carnauba wax (trade name: TOWAX-131, manufactured by Toa Kasei Co., Ltd.)
(E-2): Glycerol monostearate (trade name: S-100A, manufactured by Riken Vitamin Co., Ltd.)

(F) Coupling agent (F-1): 3-mercaptopropyltrimethoxysilane (trade name: KBM-803, trade name manufactured by Shin-Etsu Chemical Co., Ltd.)

Synthesis example 1
Preparation of epoxy resin prepolymer (component A) Prepolymers A to E which are components (A) are blended at the component ratios shown in Table 1 below, and heated under a predetermined reaction condition using a gate mixer, and then epoxy resin (A-1) and acid anhydride (A-2) were reacted to synthesize.

Examples 1-8 and Comparative Examples 1-10
Preparation of Thermosetting Epoxy Resin Composition In the component formulation (parts by mass) shown in Tables 2 and 3, the thermosetting epoxy resin composition was obtained by cooling with a two-roll hot roll and pulverizing. The following properties were measured for these compositions. The results are shown in Table 2 (Examples) and Table 3 (Comparative Examples).

Handling property of composition The workability at the time of melt-mixing with the above-mentioned two heat rolls was evaluated according to the following criteria.
(Circle): After mixing each component uniformly, the composition which can be tableted easily was able to be obtained.
X: After mixing each component uniformly, only the composition which was difficult to tablet was obtained.

Spiral flow value A mold conforming to the EMMI standard was used under the conditions of a molding temperature of 175 ° C., a molding pressure of 6.9 N / mm ² , and a molding time of 90 seconds.

Bending strength and flexural modulus Using a mold conforming to JIS-K6911 standard, molding is performed under conditions of a molding temperature of 175 ° C., a molding pressure of 6.9 N / mm ² , a molding time of 90 seconds, and 180 ° C. for 2 hours. Cure. The post-cured test piece was measured for bending strength and bending elastic modulus at room temperature (25 ° C.).

Light transmittance Under the conditions of a molding temperature of 175 ° C., a molding pressure of 6.9 N / mm ² , and a molding time of 90 seconds, a cured resin having a side of 50 mm × thickness of 0.35 mm is produced, and the secondary resin is 180 ° C. for 2 hours Curing was performed. Then, the light transmittance of 740 nm was measured using SDG Co., Ltd. X-rite8200. In order to examine the heat resistance of the cured resin, after further heat treatment at 175 ° C. for 100 hours, the light transmittance of 740 nm was similarly obtained using X-lite 8200 manufactured by SDG Co., Ltd. It was measured.

From Tables 2 and 3, it was confirmed that handling properties were improved by prepolymerization, and heat resistance was improved by using a triazine derivative epoxy resin and an acid anhydride curing agent in combination. Moreover, it has also confirmed that the resin cured material of an Example was effective as sealing resin which has high light transmittance and can respond to high output.

Claims (7)

(A) (A-1) a triazine derivative epoxy resin;
(A-2) an acid anhydride,
Epoxy group equivalent / acid anhydride group equivalent: a prepolymer obtained by reacting at a ratio of 0.6 to 2.0,
(B) inorganic filler,
(C) a curing accelerator, and
(D) An epoxy resin composition containing an antioxidant,
(B) The average particle size of the inorganic filler is 5 to 30 μm, and the maximum particle size is 53 μm or less,
A thermosetting epoxy resin composition for primary sealing of a photocoupler, in which a light transmittance at 740 nm of a 0.35 mm thick cured product after secondary curing of the epoxy resin composition is 40% or more.   The thermosetting epoxy resin composition for primary encapsulation of a photocoupler according to claim 1, wherein the (A-1) triazine derivative epoxy resin is a 1,3,5-triazine derivative epoxy resin. The prepolymer of the component (A) is represented by the following general formula (1):

(In the formula, R represents an acid anhydride residue, and n is a number from 0 to 200.)
The thermosetting epoxy resin composition for primary sealing of photocouplers according to claim 1 or 2, which comprises a compound represented by the formula:   (B) The thermosetting epoxy resin composition for primary sealing of a photocoupler according to any one of claims 1 to 3, wherein the inorganic filler is spherical silica or glass particles.   (D) Antioxidant is 1 type, or 2 or more types selected from the group which consists of a phenolic antioxidant, phosphorus antioxidant, and sulfur type antioxidant, The any one of Claims 1-4 The thermosetting epoxy resin composition for primary sealing of photocouplers described in 1.   A photocoupler encapsulated with the thermosetting epoxy resin composition for primary encapsulation of a photocoupler according to any one of claims 1 to 5. An optical semiconductor device comprising the photocoupler according to claim 6.