JPH05222165A - Light-transmitting epoxy resin composition and optical semiconductor device - Google Patents

Abstract

PURPOSE:To prepare the title compsn. suitable for sealing an optical semiconductor device, which functions by the transfer of light signal, by compounding an epoxy compd., an acid anhydride curing agent, a cure accelerator comprising an imidazole compd., and a discoloration preventive comprising a reductive organophosphorus compd. CONSTITUTION:The title compsn. is prepd. by compounding a compd. having at least two epoxy groups in the molecule, an acid anhydride curing agent, a cure accelerator comprising an imidazole compd. of formula I (wherein R<1> and R<2> are each methyl, ethyl, phenyl, or benzyl), and a discoloration preventive comprising a reductive organophosphorus compd. of formula II. The compsn. has an excellent clarity, low stress properties, a high heat resistance, a high curability, and an improved workability, gives a cured article having high strengths at a high temp., and is suitable for sealing an optical semiconductor device. The device sealed with the compsn. functions effectively and is excellent in reliablity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-transmissive epoxy resin composition which is preferably used for sealing semiconductors such as LEDs, CCDs and photocouplers which function by transmitting and receiving optical signals, and the epoxy resin composition. The present invention relates to an optical semiconductor device sealed with a cured product.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
An epoxy resin composition containing an epoxy resin and a cured product thereof is known to give a cured product excellent in electrical characteristics, moisture resistance, heat resistance, etc., and an acid anhydride cured type epoxy resin composition is particularly transparent. Since it gives an excellent cured product, it is widely used as an optically transparent epoxy resin composition for encapsulating optical semiconductors. In addition, since many phenolic resins and amine compounds generally used as curing agents for epoxy resins are originally colored, epoxy resin compositions containing them are not colored even if they are initially colorless due to heating or aging. It tends to change to brown due to oxidative deterioration and has low transparency, which is inconvenient for optical semiconductor encapsulation.

In this case, a compound such as a tertiary amine, phosphine or imidazole is generally added to the above acid anhydride curing type epoxy resin composition as a curing accelerator.

However, when a tertiary amine or a phosphine compound is used, the glass transition temperature of the composition becomes lower than when an imidazole compound is used, so that the heat resistance of the cured product becomes low and the curing There is a problem that even if added in a general amount as an accelerator (about 1% of the resin component), many cured products cause remarkable coloring.

When benzyldimethylamine, which is one of the tertiary amines, is used among these curing accelerators, there is little coloring of the cured product, and since it is itself a liquid at room temperature, the composition is kneaded. It has good workability and can be made uniform. However, since there is a problem with the curability, the heat resistance of the cured product is low, and the strength during heating becomes low, which causes package cracks due to the impact of the injector pin during molding, and the runner portion during mold cleaning. There were drawbacks such as easy cutting when pulled and poor workability.

Further, when an imidazole compound is used as a curing accelerator, the glass transition temperature of the composition is increased, the heat resistance of the cured product is improved, and the strength upon heating is also increased. The problem shown in is solved. However, since imidazole compounds are generally solid at room temperature and melting points of 100 ° C. or higher are not uncommon, they are often used as dispersion-type curing accelerators, but light-transmissive epoxy resin compositions are transparent. The uniformity of the composition is important because the property is a required property,
Therefore, the use of an imidazole compound as a dispersion type curing accelerator is inconvenient.

Among the imidazole compounds, 2-ethyl-4-methylimidazole has a good workability because it is semi-solid at room temperature, but it has a drawback that it tends to discolor the cured product to brown.

Further, the light-transmissive epoxy resin composition contains
When the cured product is treated at a high temperature, a discoloration inhibitor is added to prevent the discoloration to brown gradually. As the discoloration inhibitor, an organic phosphorus-based, hindered phenol-based, Compounds such as thioethers are known.

According to the knowledge of the present inventor, among these discoloration preventing agents, the organophosphorus discoloration preventing agent is most effective, and among the organophosphorus discoloration preventing agents, phosphorous triester is particularly effective. It has a high temperature and is liquid at room temperature, so it has good workability. However, this phosphite triester has a property of being hydrolyzed as a reaction with moisture in the air, and for example, triphenyl phosphite produces a phenol with a strong odor due to hydrolysis, so in terms of human health management, It was hard to say that it was suitable.

On the other hand, it is generally practiced to incorporate an inorganic filler such as silica into the epoxy resin composition as a means for lowering the linear expansion coefficient and lowering the stress.

However, a cured product obtained from an epoxy resin composition containing an inorganic filler such as silica in this way becomes opaque even if the epoxy resin itself is transparent and the filler is also transparent. .. This is because the epoxy resin cured product has a refractive index n _D at 25 ° C. of about 1.5 to 1.7, and the refractive index of the filler (for example, the refractive index n _D of SiO ₂ at 25 ° C. n _D ≈1.458). This is because the difference between the two causes light scattering. Therefore, the transparency of the cured product can be obtained by adding a filler having a refractive index close to that of the cured product of the epoxy resin component.

In this respect, silica-titania glass having a high refractive index is effective as the inorganic filler. That is, the sol-gel method has been conventionally known as a method for producing transparent glass having various refractive indexes. This sol-gel method starts from a solution of a metal organic and inorganic compound, and hydrolyzes and polymerizes the compound in the solution to form a solution in which fine particles of metal oxides or hydroxides are dissolved, and further promotes the reaction. The amorphous gel and polycrystal are produced by heating the porous gel formed by gelling, and it is possible to produce highly transparent silica-titania glass particles by the sol-gel method. (See Japanese Patent Laid-Open No. 3-232741).

When such silica-titania glass particles are used as a filler in an epoxy resin composition, it is expected that an epoxy resin cured product having excellent transparency and low linear expansion coefficient and low stress can be obtained.

However, when the present inventor actually used an organophosphorus discoloration inhibitor, which is most effective in preventing discoloration during high temperature treatment, and silica-titania glass particles in combination in an epoxy resin composition, A yellowing phenomenon occurs due to the interaction between the organophosphorus discoloration inhibitor and the silica-titania glass particles, which is different from the browning of the cured product due to the high temperature treatment described above, and violent coloration occurs when both coexist even at room temperature, The light transmittance of the cured product was greatly reduced.

When a filler is blended with the epoxy resin component, the wettability of the epoxy resin component with respect to the filler particles is usually insufficient, so that there are slight voids and peeling at the interface between the two, which causes As a result, light scattering is caused, which causes a problem that the transparency that should be originally obtained cannot be obtained.

Therefore, even if the silica-titania glass particles are surface-treated with a silane coupling agent or the like for the purpose of preventing color development due to the above-mentioned interaction and improving wettability, sufficient transparency cannot be obtained. Met.

Therefore, it has been desired to develop a high quality light-transmitting epoxy resin composition in which the above-mentioned various problems are solved.

The present invention has been made in view of the above circumstances,
A light-transmissive epoxy resin composition having excellent transparency, low stress, good heat resistance, and good curability, and also capable of giving a cured product having particularly high strength during heating, and improved workability, and this composition It is an object to provide an optical semiconductor device sealed with a cured product.

[0019]

Means and Actions for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a compound having two or more epoxy groups in one molecule, an acid anhydride type curing agent, and a curing accelerator. An imidazole compound represented by the following general formula (1) as an agent, a reducing organic phosphorus compound represented by the following general formula (2) as a discoloration inhibitor, and an epoxy resin containing these components in addition to these components The surface of the composition is substantially the same as that of the cured product and has a surface treatment agent composed of a compound having two or more epoxy groups in one molecule and / or an acid anhydride curing agent and an organic silicon compound. It has been found effective to incorporate treated fillers.

[0020]

[Chemical 3] (However, in the formula, R ¹ and R ² are each a methyl group, an ethyl group,
It is a phenyl group or a benzyl group. )

[0021]

[Chemical 4]

In this case, 1, 2 shown by the above equation (1)
The imidazole compound having a substituent at the position is generally in a liquid or semi-solid state at room temperature, and by using this imidazole compound as a curing accelerator for an acid anhydride-curing type epoxy resin composition, the composition has good workability during kneading. It is possible to obtain a cured product having high transparency, which is capable of homogenizing the product, does not color the cured product, improves the curability, improves the glass transition temperature, and has excellent molding hardness and heat resistance. Therefore, it is possible to prevent the occurrence of cracks at the time of molding, and the workability at the time of subsequent die cleaning is also improved.

Further, the reducing organophosphorus compound represented by the above formula (2) can effectively prevent discoloration when the cured product of the epoxy resin composition is subjected to high temperature treatment and is not hydrolyzed. However, by-products are hardly generated, and the incorporation of this reducing organophosphorus compound as a discoloration-preventing agent makes it possible to suppress coloring of the cured product and achieve higher transparency.

In the light-transmitting epoxy resin composition of the present invention, a filler having a refractive index similar to that of the cured product of the epoxy resin component described above is prepared from an epoxy compound and / or an acid anhydride-based curing agent and an organosilicon compound. When a filler treated with a surface treating agent is added, even if silica-titania glass particles are used as the filler, sufficient coloring is produced by the interaction between the reducing organic phosphorus compound and the silica-titania glass particles. Suppressed, and the wettability between the above-mentioned epoxy resin component and the surface-treated filler is remarkably improved, the adhesion of the interface is increased, and since there is substantially no difference in the refractive index between the two, light scattering It is possible to obtain a cured product which is significantly reduced, has high transparency, low stress and good crack resistance.

Therefore, the light-transmissive epoxy resin composition of the present invention is excellent in transparency, has low stress, good heat resistance and curability, and gives a cured product having particularly improved strength during heating.
It has improved workability and is excellent in optical functionality and reliability as described above, and thus can be suitably used for encapsulating optical semiconductors such as LEDs, CCDs and photocouplers. Further, it has been found that an optical semiconductor device encapsulated with a cured product of such an epoxy resin composition exerts its function much more effectively than that encapsulated with a conventional light-transmissive epoxy resin. It was the invention.

Therefore, the present invention is represented by the following general formula (1) as (A) a compound having two or more epoxy groups in one molecule, (B) an acid anhydride curing agent, and (C) a curing accelerator. And a light-transmitting epoxy resin composition comprising the reducing organic phosphorus compound represented by the following general formula (2) as a discoloration inhibitor (D), and the above epoxy resin composition. Of which the surface is treated with a compound which has substantially the same refractive index as that of the cured product and which has two or more epoxy groups in one molecule and / or a surface treatment agent which comprises an acid anhydride type curing agent and an organosilicon compound. Provided are a light-transmissive epoxy resin composition containing the above filler, and an optical semiconductor device sealed with a cured product of the light-transmissive epoxy resin composition.

[0027]

[Chemical 5] (However, in the formula, R ¹ and R ² are each a methyl group, an ethyl group,
It is a phenyl group or a benzyl group. )

[0028]

[Chemical 6]

The present invention will be described in more detail below. Conventionally, a compound having two or more epoxy groups in one molecule of the component (A) which constitutes the light-transmitting epoxy resin composition of the present invention has been conventionally known. The various epoxy resins mentioned above can be used in liquid or solid form. Specific examples thereof include epoxy resins synthesized from various novolac resins such as epichlorohydrin and bisphenol, alicyclic epoxy resins, and epoxy resins having halogen atoms such as chlorine and bromine atoms introduced therein. The seeds may be used alone or in combination of two or more.

Of these, a bisphenol type epoxy resin that is particularly less colored is preferable. Specific products include, for example, Epicoat 828, Epicoat 1001, Epicoat 1004 (trade names of Yuka Shell Epoxy Co., Ltd., RE310S, RE304S). As above, manufactured by Nippon Kayaku Co., Ltd.), DER332, DER661, DER6
64 (above, product name of Dow Chemical Co., Ltd.) and the like.

As the acid anhydride-based curing agent as the component (B), any of those generally used for curing epoxy resins can be used. For example, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydro. Examples thereof include phthalic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, etc. Among them, those not containing an aromatic ring such as hexahydrophthalic anhydride and tetrahydrophthalic anhydride are preferable. The amount of the acid anhydride-based curing agent can be a normal amount, and the amount of the component (A) and the amount of the component (B) are determined by their equivalent ratios, but the former 45 to 95 can be used. Parts (parts by weight; the same applies hereinafter) and the latter 55 to 5 parts are preferable.

Next, in the present invention, as the component (C), a 1,2-position-substituted imidazole compound represented by the following general formula (1) is blended, which acts as a curing accelerator.

[0033]

[Chemical 7] (However, in the formula, R ¹ and R ² are each a methyl group, an ethyl group,
It is a phenyl group or a benzyl group, and R ¹ and R ² may be the same or different. )

Specific examples of the imidazole compound represented by the formula (1) include 1-methyl-2-ethylimidazole (trade name: Cureazole 1M2EZ, manufactured by Shikoku Chemicals Co., Ltd.), 1-benzyl-2-phenylimidazole ( Trade name: Curesol 1B2PZ, manufactured by Shikoku Chemicals Co., Ltd.) and the like. These compounds are usually liquid or semi-solid at room temperature, have good workability and dispersibility, and give little coloring of the cured product.

The compounding amount of the imidazole compound of the formula (1) is preferably 0.1 to 5 parts with respect to 100 parts of the total amount of the components (A) and (B), and is less than 0.1 part. If it does not, the action as a curing accelerator may not be fully exerted, and if it exceeds 5 parts, a sharp increase in viscosity will occur, for example, when kneading with a mixer, and if it is excessive, gelation will occur and workability during manufacturing will be significantly reduced. In some cases, the cured product may be strongly colored.

Further, the discoloration preventing agent as the component (D) is a reducing organophosphorus compound represented by the following general formula (2).

[0037]

[Chemical 8]

This reducing organophosphorus compound has a special structure as shown in the above formula and is hard to undergo hydrolysis, and its chemical name is 9,10-dihydro-9-oxa-10-phosphaphenanthrene. It is -10-oxide, and specifically, HCA, SANKO-Epoclean (all manufactured by Sanko Chemical Co., Ltd.) and the like are used.

The amount of the reducing organophosphorus compound of the formula (2) to be blended is preferably 0.1 to 5 parts, and 0.1 part to 100 parts by weight of the total amount of the components (A) and (B). If the amount is less than 5, the discoloration preventive effect may not be exhibited and the coloring of the cured product may become severe. If it exceeds 5 parts, the curing reaction rate may slow down, resulting in curing failure or lowering of glass transition temperature and heat resistance. It may fall.

The composition of the present invention comprises, in addition to the above-mentioned components (A) to (D), a compound having two or more epoxy groups in one molecule and / or an acid anhydride type curing agent and an organosilicon compound. It is preferable to incorporate a filler treated with a surface treatment agent.

Here, as the filler, for example, silica,
Alumina, aluminum nitride, boron nitride, silica-titania glass, silica-alumina glass, etc. can be used,
In particular, silica-titania glass has a refractive index n at 25 ° C. of the filler by changing the composition of SiO ₂ / TiO _2.
It is effective and preferable because _D can be adjusted.

Further, as the silica-titania glass particles, from 900 nm to 6 according to the linear transmittance measuring method M described below.
Linear transmittance of 70% or more in the wavelength range of 00 nm, especially 8
Those of 0% or more can be preferably used.

Linear transmittance measuring method: M A bisphenol type epoxy resin represented by the following general formula (3) or a novolac type epoxy resin represented by the following general formula (4) and phenylglycidyl ether are mixed to obtain silica- Refractive index difference with titania glass particles is ± 0.
Prepare a solution that is within 002. This solution and silica-titania glass particles crushed to an average particle size of 5 to 30 μm were mixed at a weight ratio of 1: 1 and the mixture was 1
The linear transmittance is measured with an optical path length of mm.

[0044]

[Chemical 9]

The method for producing such highly transparent silica-titania glass particles can be carried out in accordance with the sol-gel method described in Japanese Patent Application No. 2-028077 previously proposed by the present applicant.

In the present invention, the above-mentioned fillers such as silica-titania glass particles require the components (A) to (D) in order to minimize light scattering when blended with the epoxy resin. It is necessary that the refractive index of the cured product of the epoxy resin component is substantially the same. Specifically, the refractive index difference is within ± 0.01, preferably within ± 0.005, and more preferably within ± 0.002.

Further, the compound having two or more epoxy groups in one molecule and the acid anhydride-based curing agent used as the surface treatment agent for the above-mentioned filler are the components (A) and (B) in the composition of the present invention, respectively. Although a compound that can be blended as the component) can be used, the same compounds as the components (A) and (B) or different compounds can be used.

Further, examples of the organosilicon compound as the surface treatment agent include silanes and organopolysiloxanes represented by the following formulas, one of which may be used alone or two or more of which may be used. It can be used in combination.

[0049]

[Chemical 10]

In the present invention, the compounding ratio of the above three components as the surface treating agent is such that the compound having two or more epoxy groups in one molecule is (a), the acid anhydride curing agent is (b), and the organosilicon is When the compound is (c), (i) when a mixture of (a) and (c) is used as a treating agent (a) / (c) = 50/50 to 99/1 (ii) As a treating agent (b) ) And (c) are used (b) / (c) = 50/50 to 99/1 (iii) When a mixture of (a), (b) and (c) is used as a treating agent (a) / (B) = 50/50 to 85/15 and [(a) + (b)] / (c) = 50/50 to 99/1
(Both are weight ratios).

In the present invention, it is preferable that the surface treatment agent comprising the above three components and the filler have similar refractive indices, and the difference in the refractive index between them is within ± 0.1, particularly within ± 0.05. It is desirable to adjust the refractive index to such a value.

The surface treatment of the filler with the above surface treatment agent can be carried out by a dry method or a wet method. As a dry method, known means can be adopted, for example, a filler is put in a high-speed mixer having a high-speed rotation and a large shearing force and a heating device, and a surface treatment agent diluted with a solvent is added by spraying or the like and mixed and stirred. Any industrially generalized method of carrying out may be employed. On the other hand, as the wet method, an ordinary method in which a filler, a surface treatment agent and a solvent are mixed and stirred and then the solvent is removed can be adopted.

In this case, although the kind of the solvent is not particularly limited, it is desirable to appropriately select it because the adsorption property of the surface treatment agent to the filler may be different, but specifically, toluene, methyl ethyl ketone, methyl isobutyl. A ketone or the like can be preferably used. Also, after removing the solvent,
It is also effective to heat at 100 to 600 ° C.

The compounding amount (adhesion amount) of the surface treatment agent with respect to the filler is 0.1 to 5 with respect to 100 parts of the filler.
Parts, and particularly preferably 0.5 to 2 parts.

The amount of the filler thus surface-treated is preferably 10 to 500 parts, particularly 50 to 200 parts, relative to 100 parts of the resin component containing the components (A) to (D) as essential components. If it is less than 10 parts, the low stress property due to the reduction in the thermal expansion coefficient of the cured product due to the filler content may not be exhibited, and if it exceeds 500 parts, the melt viscosity of the composition becomes high and the workability deteriorates. The light transmittance of the cured product may decrease.

In addition to the above-mentioned components, various additives can be added to the composition of the present invention as optional components within a range that does not impair the effects of the present invention. An agent, a stress reducing agent, a release agent, a visible light blocking agent, a flame retardant and the like can be appropriately added.

When the light-transmitting epoxy resin composition of the present invention is produced, it can be obtained by uniformly stirring and mixing the predetermined amounts of the above-mentioned components. At this time, various mixers, kneaders, rolls, and extruders are used. It can be performed using a ruder or the like. There is no particular limitation on the order of mixing the components.

The composition of the present invention can be suitably used for encapsulation of optical semiconductors regardless of the properties of the resin component. If it is liquid at room temperature, it can be molded by a potting method, casting method or the like. If it is solid at room temperature, it can be transferred. Molding and injection molding can be adopted. In this case, the molding temperature is 80 to 160 ° C., and the post cure is 140 to 16
It is preferred to carry out at 0 ° C. for 2 to 16 hours. When using the composition of the present invention, in order to exhibit high transparency,
When a part or all of the epoxy resin composition is solid, it is effective to heat and melt it with the necessary all components or a part thereof in advance, or to mix them after dissolving them in a solvent. It is also possible to employ a method in which the mixture is mixed with the solvent and the solvent is stripped.

As an example of an optical semiconductor encapsulated with the light transmissive epoxy resin composition of the present invention, a photocoupler as shown in FIG. 1 is exemplified. FIG. 1 is a vertical sectional view of the photocoupler, in which 1 is a light emitting element (gallium arsenide light emitting diode), 2 is a light receiving element (silicon phototransistor), 3 is an inner resin, and a light-transmitting material formed by molding an epoxy resin. Resin, 4 is an outer resin, and a light-shielding resin containing carbon is molded, and 5 is a lead wire.

[0060]

The light-transmissive epoxy resin composition of the present invention is excellent in transparency, low stress, heat resistance, and curability. Is improved and can be suitably used for sealing an optical semiconductor device. Further, the optical semiconductor device sealed with the cured product of the composition of the present invention effectively exhibits optical functionality and is excellent in reliability.

[0061]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight. Prior to each example, a production example of the surface-treated filler used in each example will be shown.

[Production Example] (Production of Filler) Japanese Patent Application No. 2-8 previously proposed by the present applicant
According to the sol-gel method described in No. 077, highly transparent silica-titania glass particles were produced by the following method.

Silica-titania glass particles Tetramethoxysilane (trade name KBM04, manufactured by Shin-Etsu Chemical Co., Ltd.) 1522.2 g and methanol (Wako Pure Chemical Industries, special grade) 320.4 g were added to a solution of 0.2N hydrochloric acid aqueous solution 180 ml. Was added dropwise at 30 ° C over 15 minutes, then at 30 ° C
It was stirred for 1 hour. Next, 675.0 g of tetranormal butyl titanate (manufactured by Nippon Soda Co., Ltd.) and methanol 16
0.2g of solution was added dropwise at 30 ° C over 1 hour,
After stirring for 1 hour at room temperature, 682.8 g of pure water was added at 30 ° C for 15 hours.
The mixture was added dropwise over a period of minutes, and the mixture was further stirred at 30 ° C. for 10 minutes.

When the obtained silica-titania sol was placed in a polypropylene container and sealed at 90 ° C., the sol gelled after about 30 minutes. The gel was aged at 60 ° C. for 12 hours as it was, and then the container lid was removed, followed by drying in a dryer at 90 ° C. for 3 days to obtain a dried gel body. This was crushed with a ball mill made of alumina, and the dried gel body after crushing was put into a box-type electric furnace, and N ₂ 1.4 m ³ / h, 50 up to 500 ° C.
From 0 ° C, dry air 14m ³ / h 1100
When the temperature was raised to 13 ° C over 13 hours and the temperature was maintained at 1100 ° C for 30 minutes, silica-titania glass particles having the refractive index, the light transmittance and the average particle diameter shown in Table 1 were obtained.

[0065]

[Table 1]

In this case, the refractive index, light transmittance and average particle diameter were measured by the following methods.

Measuring Method of Refractive Index The refractive index was measured with an Abbe refractometer 3T manufactured by Atago.

Method of Measuring Light Transmittance TiO ₂ —SiO ₂ particles having an average particle size of 5 to 30 μm were mixed with Ti
Mixture of Epicoat 828 (Epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) and phenylglycidyl ether (dipping liquid) adjusted to have a mixing ratio of ± 0.002 in the refractive index calculated from the content of O _2. ) Was mixed at a weight ratio of 1: 1. After the particles were sufficiently dispersed, degassing under reduced pressure was performed until no bubbles were visually observed. This mixture was put into a cell having an optical path length of 1 mm, and a transmittance spectrum was measured in a wavelength range of 900 nm to 400 nm using a spectrophotometer. In this case, the reference is blank. The refractive index n _D = 1.570 at 25 ° C. for each of the silica-titania glass particles.
A mixed solution of 5 was prepared and used as an immersion liquid for measurement.

Measurement method of particle size distribution A 0.2% by weight aqueous solution of sodium hexametaphosphate was used as a dispersion medium of the sample, and the particle size distribution measured by a centrifugal sedimentation type particle size distribution analyzer SA-CP3L manufactured by Shimadzu Corporation was measured. ,
The average particle size was determined.

(Surface treatment of filler) 200 g of silica-titania glass particles and 50 parts of toluene were placed in a four-necked flask having an internal volume of 1 liter equipped with a reflux condenser, a thermometer, a stirrer, an ester adapter and a dropping funnel.
0 g was added, and azeotropic dehydration was carried out for 1 hour while stirring at the reflux temperature. Epoxidized bisphenol A (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.)
97 g, γ-glycidoxypropyltrimethoxysilane (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.03
After a surface treatment agent solution consisting of 20 g of toluene and 20 g of toluene was added dropwise for 5 minutes, stirring was continued for 4 hours at the reflux temperature. The solvent in this reaction mixture was distilled off under reduced pressure to a temperature of 1
It was dried at 20 ° C. for 12 hours to obtain a surface-treated filler.

Examples 1 and 2 Bisphenol A type epoxy resin (trade name: Epicoat 1001, epoxy equivalent 475, softening point 64 ° C., manufactured by Yuka Shell Epoxy Co., Ltd.) 7
5.5 parts, hexahydrophthalic anhydride (trade name: RIKACID HH, melting point 36 ° C., manufactured by Shin Nippon Rika Co., Ltd.) 24.5 parts,
0.6 part of γ-glycidoxypropyltrimethoxysilane (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) and 2.0 parts of a reducing organic phosphorus compound HCA (trade name: HCA, manufactured by Sanko Chemical Co., Ltd.) are mixed. After melt-mixing at 70 ° C. for 15 minutes while performing degassing under reduced pressure using a mixer, 1-methyl-2-ethylimidazole (trade name: Curezol 1M2EZ, liquid at room temperature, manufactured by Shikoku Chemicals Co., Ltd.) 1.0 Parts were added and mixed again under reduced pressure at 60 ° C. for 3 minutes to prepare a light-transmissive epoxy resin composition (Example 1).

A light-transmissive epoxy resin composition was prepared in the same manner as in Example 1 except that 103.6 g of the surface-treated filler obtained in Production Example was added to the above composition (Example 2). ..

[Examples 3 and 4] 1-benzyl-2-phenylimidazole (trade name: Cureazole 1B2PZ, melting point 4 instead of 1-methyl-2-ethylimidazole)
A light-transmitting epoxy resin composition was prepared in the same manner as in Example 1 except that 1.2 parts of 3 ° C., manufactured by Shikoku Chemicals Co., Ltd.) was added (Example 3).

The surface-treated filler 10 obtained in the production example
A light transmissive epoxy resin composition was prepared in the same manner as in Example 3 except that 3.8 g was added (Example 4).

Comparative Examples 1, 2 2-ethyl-4-methylimidazole (trade name: Cureazole 2E4MZ, semi-solid at room temperature, manufactured by Shikoku Chemicals Co., Ltd.) 1.0 instead of 1-methyl-2-ethylimidazole 1.0 Light-transmissive epoxy resin compositions were prepared in the same manner as in Example 1 or 2 except that parts were mixed (Comparative Examples 1 and 2).

Comparative Examples 3 and 4 Example 3 or 4 except that 1.2 parts of benzyldimethylamine (liquid at room temperature, manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of 1-methyl-2-ethylimidazole. Light-transmissive epoxy resin compositions were prepared in the same manner as in (Comparative Examples 3 and 4).

Next, each of the obtained light-transmissive epoxy resin compositions was molded at a molding temperature of 150 ° C. and a molding pressure of 70 kg /
After transfer molding with cm ² and molding time of 3 minutes,
After-curing was performed at 150 ° C. for 4 hours to prepare a test piece, and the following test was performed. The results are shown in Table 2.

Light transmittance: A test piece having a size of 10 × 50 × 1 mm was prepared, and a light having a wavelength of 589 nm was transmitted through the absorptiometer at 25 ° C. in the thickness direction of 1 mm to obtain an initial light transmittance (T
%) Was measured. Then, the test piece was aged at 120 ° C. for 100 hours, and then the light transmittance (T%) was similarly measured.

Glass transition temperature, linear expansion coefficient: 5 × 5 × 1
A 5 mm test piece was prepared, and the temperature was raised by a dilatometer at a rate of 5 ° C./min for measurement.

Molding hardness: When a test piece of 4 × 10 × 120 mm was molded, it was measured by pressing a JIS-A hardness meter in the thickness direction of 4 mm immediately after the mold was opened at 150 ° C. for 3 minutes.

Bending strength under heat: A 4 × 10 × 120 mm test piece prepared when measuring the molding hardness was subjected to a bending test in the 4 mm thickness direction under a high temperature environment of 150 ° C. without after-curing.

[0082]

[Table 2]

From the results shown in Table 2, the light-transmitting epoxy resin compositions (Examples 1 to 4) of the present invention showed almost no discoloration not only at the initial stage but also after high temperature aging, and the light transmittance was hardly reduced. In addition, it was found that the glass transition temperature and the molding hardness were high, and the curability and heat resistance were excellent.
Particularly, the compositions of the present invention (Examples 2 and 4) in which the filler having a special surface treatment was blended showed a slight decrease in light transmittance as compared with the composition in which the filler was not added, but it was extremely decreased. It was also found that the expansion coefficient is reduced, the stress is reduced, the bending strength at the time of heating is improved, the prevention of defective molding at the time of sealing molding, and the improvement of workability can be expected.

On the other hand, the light-transmitting compositions (Comparative Examples 1 to 4) in which a compound other than the imidazole compound portion of the above formula (1) was blended as a curing accelerator, the remarkable discoloration occurred and the light transmittance was increased. There was a decrease in the glass transition temperature.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a photocoupler used in an example.

[Explanation of symbols]

 1 Light emitting element 2 Light receiving element 3 Inner resin 4 Outer resin 5 Lead wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08L 63/00 H01L 23/29 23/31 33/00 N 8934-4M (72) Inventor Kazuhiro Arai Gunma Prefecture, Usui-gun, Matsuida-cho, Hitomi 1-10, Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (3)

[Claims] 1. (A) a compound having two or more epoxy groups in one molecule, (B) an acid anhydride-based curing agent, (C) an imidazole compound represented by the following general formula (1) as a curing accelerator, [Chemical 1] (However, in the formula, R ¹ and R ² are each a methyl group, an ethyl group,
It is a phenyl group or a benzyl group. (D) A reducing organic phosphorus compound represented by the following general formula (2) as a discoloration inhibitor: A light-transmissive epoxy resin composition comprising: 2. A compound and / or acid anhydride-based curing agent which has substantially the same refractive index as the cured product of the epoxy resin composition according to claim 1 and has two or more epoxy groups in one molecule. The light-transmissive epoxy resin composition according to claim 1, further comprising a filler surface-treated with a surface-treating agent composed of: and an organic silicon compound. 3. An optical semiconductor device encapsulated with a cured product of the light transmissive epoxy resin composition according to claim 1.