JPH03201470A - Optical semiconductor device - Google Patents

Abstract

PURPOSE:To obtain sealing resin which is excellent in light transmittance and small in internal stress by a method wherein epoxy resin composition, which contains silica powder and a silane coupling agent, is used, where the refractive index difference between the silica powder and the cured body of the resin component is specified to stay in a specific range. CONSTITUTION:One part of gamma-glycidoxypropyltrimetoxylane as a silane coupling agent is added to 100 parts of silica powder, which is uniformly mixed in methanol and desolvated, and the desolvated substance is thermally treated to form surface treated silica powder. 82 parts of bisphenol A type epoxy resin (liquid resin) whose epoxy equivalent weight is 185, 12 parts of cycloaliphatic epoxy resin (liquid resin) whose epoxy equivalent weight is 252 and which is represented by the structural formula shown below, 100 parts of 4- methylhexahydrophthalic anhydride, 0.4 parts of 2-ethyl-4-methylimidazole, and 90 parts of the above surface treated silica powder are mixed together, and the mixed substance is thermally cured at a temperature of 120 deg.C to obtain an optical semiconductor element sealing resin. The cured body of the sealing resin concerned has such a high value as a light transmittance of 80% at a thickness of 4mm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical semiconductor device sealed with a sealing resin that is excellent in both light transmittance and low stress.

(Prior Art) Encapsulating resin compositions used for encapsulating optical semiconductor devices such as LEDs (light emitting diodes) are required to have transparency in their cured products, and are generally made of bisphenol A epoxy. BACKGROUND ART Epoxy resin compositions obtained by using an epoxy resin such as a resin or an alicyclic epoxy resin and an acid anhydride as a curing agent are widely used.

However, when the above epoxy resin m-acid is used as a sealing resin, internal stress is generated due to curing shrinkage of the epoxy resin composition or distortion caused by the difference in linear expansion coefficient between the epoxy resin and the optical semiconductor element. do. As a result, the optical semiconductor element deteriorates, and for example, when the optical semiconductor element is a light emitting element, a problem arises in that its brightness decreases. For this reason, conventionally, as a method of reducing the above-mentioned internal stress, there has been a method of adding an inorganic powder with a small linear expansion coefficient such as silica powder to reduce the linear expansion coefficient of the epoxy resin composition to approximate that of an optical semiconductor element. It has been proposed and implemented in some cases.

[Problem to be solved by the invention]

However, the above method has a fatal drawback as a resin composition for encapsulating optical semiconductors in that the light transmittance of the epoxy resin composition is significantly reduced. On the other hand, in order to solve the above-mentioned drawbacks, a method of reducing the difference in refractive index between the resin component and the silica powder has been proposed and implemented (Japanese Patent Application Laid-open No. 49-23847). For example, if the difference in refractive index of
The light transmittance of the cured epoxy resin composition is about 70%, which is insufficient as a resin composition for sealing high-performance optical semiconductor elements such as high-brightness LEDs.
In addition, there is a strong desire for a resin composition for encapsulating optical semiconductors that has excellent low stress properties.

The present invention was made in view of the above circumstances, and relates to an optical semiconductor device that has low internal stress and excellent light transmittance.

[Means to solve the problem]

In order to achieve the above object, the optical semiconductor device of the present invention contains the following components (A) to (E), and has the refractive index of the silica powder of the component (D) and the components (A) to (C). The optical semiconductor element is sealed using an epoxy resin composition whose refractive index difference from that of the cured epoxy resin is set within the range of ±0.01.

(A Transparent epoxy resin.

(B Acid anhydride curing agent.

(C curing catalyst.

(D Silica powder.

(E Silane coupling agent.

(Function) In other words, the present inventors conducted a series of studies in order to obtain a sealing resin with low internal stress and excellent light transmittance. Recalling that the adhesion between the resin component and silica powder may be low, they conducted further research to improve this adhesion.As a result, they combined a silane coupling agent to bond the silica powder to the surface. It has been shown that by improving the adhesion of the interface between the resin component and silica powder through treatment and making the refractive index of the silica powder approximate that of the cured epoxy resin, a transparent sealing resin with reduced internal stress can be obtained. Heading arrived at this invention.

The epoxy resin composition used in this invention includes a transparent epoxy resin (component A), an acid anhydride curing agent (component B),
It is obtained using a curing catalyst (component C), silica powder (component D), and a silane coupling agent (component E), and is usually in liquid, powder, or tablet form made by compressing this powder. It has become.

As the component A (transparent epoxy resin), bisphenol type epoxy resins and alicyclic epoxy resins are preferred because they have transparency, but other epoxy resins may be used in combination depending on the case. When the other epoxy resins mentioned above are used, it is usually preferable to set the proportion thereof to 50% by weight (hereinafter abbreviated as "%") of the entire epoxy resin. Generally, such epoxy resins include:
Epoxy equivalent: 100-1000. The one used is one with a softening point of 120''C or less.The transparency of the transparent epoxy resin mentioned above includes the case of colored transparent epoxy resin, which is equivalent to a thickness of 1 mm, and has a light transmittance of 80 to 10 at a wavelength of 600 nm. “Luu (
(measured by spectrophotometer). Component B (acid anhydride curing agent) used together with Component A (transparent epoxy resin) is preferably one having a molecular weight of about 140 to 200, such as hexahydrophthalic anhydride and tetrahydrophthalic anhydride. Examples include colorless to pale yellow acid anhydrides such as methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride. The blending amount of the above B component (acid anhydride curing agent) is 50 to 2 parts by weight per 100 parts by weight (hereinafter abbreviated as "parts") of the above A component (transparent epoxy resin).
It is preferable to set the amount in the range of 0.00 parts.

Examples of component C (curing catalyst) used together with component A (transparent epoxy resin) and component B (acid anhydride curing agent) include tertiary amines, imidazole compounds, and organic metal complex salts.

Note that the difference between the refractive index of the above component (silica powder) and the cured epoxy resin composition consisting of the above components A to C is ±0.
．． Examples of methods for setting the value in the range of 01 include methods ① to ② below.

■ A method of adjusting the refractive index of only the cured epoxy resin composition consisting of the above A-C components (for example, selection of the type of A component, combination of two or more types of A component, selection of the type of B component, combination of two or more types, etc.).

■ Method of adjusting the refractive index of component D (silica powder).

■ Method of using the above and ■ together.

and the above-mentioned component A (transparent epoxy resin).

As component D (silica powder) used together with component B (acid anhydride curing agent) and component C (curing catalyst), a meltable component is used, and preferably the refractive index of the silica powder itself is set to Examples include those adjusted according to the method. Specifically, by mixing small amounts of metal oxides such as lead oxide and titanium oxide into silica powder, the refractive index of the silica powder itself (usually about 1.40) is adjusted, and the refractive index of the epoxy resin (usually about 1.40) is adjusted. 1.50).

Such silica powder has an average particle size of 3 to 60 μm.
It is preferable to use That is, the average particle size is 3
This is because if it is less than 60 μm, the viscosity becomes high and the moldability of the epoxy resin composition deteriorates, and if it exceeds 60 μm, there is a high possibility of damaging the optical semiconductor element. Furthermore, the content of silica powder is 10-7% of the total epoxy resin composition.
It is preferable to set it in the range of 0%.

The Ery and Min (silane coupling agent) used together with the above A component (transparent epoxy resin), B component (acid anhydride curing agent), C component (curing catalyst) and D component (silica powder) are epoxy groups. or those having an amino group are preferred. Specifically, those having an epoxy group include β-(3゜4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, T-glycidoxypropyltrimethoxysilane, Examples include sidoxypropylmethyljethoxysilane, and those having an amino group include N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-T-aminopropylmethyldimethoxysilane, Examples include T-acnopropyltriethoxysilane, N-phenyl-γ-a≧nopropyltrimethoxysilane, and the like. The amount of the Ed component (silane coupling agent) used is preferably set within the range of 0.5 to 3% based on the D component (silica powder).

In addition, the epoxy resin composition used in this invention may contain dyes, if necessary, in addition to the above-mentioned A-E prescriptive salts.

Conventionally known additives such as a modifier, an anti-discoloration agent, an anti-aging agent, a mold release agent, a reactive or non-reactive diluent, and the like can be appropriately blended.

And, as an epoxy resin composition used in this invention,
It is necessary to use one in which the difference between the refractive index of the cured epoxy resin consisting of the above A component, B component and C component and the refractive index of the above component (silica powder) is within ±0.01. Refractive index is measured using an Atsuh refractometer.

The epoxy resin composition used in this invention can be produced, for example, as follows.

That is, it can be produced by blending and melt-mixing the above-mentioned A-E components and conventionally known additives, cooling the mixture to room temperature, pulverizing it by known means, and tableting as necessary. Moreover, when the said epoxy resin composition is a liquid material, it is sufficient to just mix each said component. In the above manufacturing method, it is effective to previously treat the surface of the silica powder with a silane coupling agent before mixing each component from the viewpoint of improving light transmittance and low stress properties. In this case, the surface treatment method includes, for example, a method of uniformly mixing the silane coupling agent and silica powder in methanol, removing the solvent, and then heat-treating the mixture at about 100° C. for about 2 hours.

The encapsulation of an optical semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding or casting.

The optical semiconductor device thus obtained has excellent transparency, extremely low internal stress, and high reliability. This is because the silica powder is surface-treated by adding a silane coupling agent, which improves the adhesion at the interface between the resin component and the silica powder. This is thought to be because it is relatively small.

[Effects of the Invention] As described above, the optical semiconductor device of the present invention contains silica powder and a silane coupling agent, and the difference in refractive index between the silica powder and the cured product of the resin component is within a specific range. Since the optical semiconductor element is resin-sealed using an epoxy resin composition, the sealing resin has excellent light transmittance,
Moreover, the internal stress is small, and the reliability is extremely high because, for example, deterioration in brightness of the light emitting element is suppressed.

Next, examples will be described together with comparative examples.

(Example 1) T-glycidoxypropyltrimethoxysilane as a silane coupling agent was added to 100 parts of silica powder (containing metal oxide) having a refractive index of 1.536 and an average particle size of 25 μm. After uniformly mixing 1 part of silica powder in methanol and removing the solvent,
Surface-treated silica powder was obtained by heat treatment at 0°C for about 2 hours.

Therefore, 82 parts of bisphenol A type epoxy resin (liquid resin) with an epoxy equivalent weight of 185, 12 parts of an alicyclic epoxy resin (liquid resin) with an epoxy equivalent weight of W252 represented by the structural formula below, and 12 parts of a bisphenol A type epoxy resin (liquid resin) with an epoxy equivalent weight of 185. 0 1 100 parts of 4-methylhexahydrophthalic anhydride, 0.4 parts of 2-ethyl-4-methylimidazole (the refractive index of the cured product of the blended resin composition is 1.536), and the surface-treated silica 120 parts of powder mixed with 90 parts
The mixture was thermally cured at C to obtain a cured acid product containing silica powder-containing epoxy resin. The light transmittance of this cured product is 8 at a thickness of 4 mm.
It was a high value of 0%.

(Example 2) 100 parts of silica powder (containing metal oxide) with a refractive index of 1.510 and an average particle size of 25 μm was used as a silane coupling agent, β-(3,4 epoxycyclohexyl)ethyltri One part of methoxysilane was added to the above silica powder, mixed uniformly in methanol, solvent removed, and then heat treated at about 100'C for about 2 hours to obtain surface-treated silica powder.

Next, 17 parts of bisphenol A type epoxy resin (liquid resin) with an epoxy equivalent of 185, 83 parts of an alicyclic epoxy resin with an epoxy equivalent of 252 represented by the structural formula below, and 100 parts of 4-methylhexahydrophthalic anhydride. , 0.4 parts of 2-ethyl-4-methylimidazole (the refractive index of the cured product of the above blended resin composition is 1.510) was mixed with 90 parts of the above surface-treated silica powder.
It was thermally cured at °C to obtain a cured epoxy resin composition containing silica powder. The light transmittance of this cured product is 85 at a thickness of 4 mm.
It was a high value of %.

(Example 3) T-aminopropyltriethoxysilane was added as a silane coupling agent to 100 parts of silica powder (containing a metal oxide) having a refractive index of 1.531 and an average particle size of 20 μm, and the above silica powder was added. After uniformly mixing in methanol and removing the solvent, heat at approximately 100°C.
A surface-treated silica powder was obtained by heat treatment for about 2 hours.

Next, 67 parts of bisphenol A type epoxy resin with an epoxy equivalent of 185, 33 parts of bisphenol AF type epoxy resin (liquid resin) with an epoxy equivalent of 240, 100 parts of 4-methylhexahydrophthalic anhydride, and 2-ethyl-4
- Add and mix 90 parts of the above surface-treated silica powder to 0.4 parts of methylimidazole (the refractive index of the cured product of the above blended resin composition is 1.536), and heat cure the mixture at 120'C to powder the silica powder. A cured product of the containing epoxy resin composition was obtained. The light transmittance of this cured product was as high as 80% at a thickness of 4 ribs.

[Comparative Example 1] Surface treatment of silica powder with a silane coupling agent was not performed. A cured epoxy resin composition containing silica powder was obtained in the same manner as in Example 1 except for the above. The light transmittance of this cured product was about 50% at a thickness of 4 mm.

[Comparative Example 2] Surface treatment of silica powder with a silane coupling agent was not performed. A cured epoxy resin composition containing silica powder was obtained in the same manner as in Example 2 except for the above. The light transmittance of this cured product was about 50% at a thickness of 4M.

(Comparative Example 3) Surface treatment of silica powder with a silane coupling agent was not performed.Other than that, a cured product of an epoxy resin composition containing silica powder was obtained in the same manner as in Example 2.Light transmittance of this cured product was about 50% at a thickness of 4 mm.

[Example 4] The amount of surface-treated silica powder was changed from 90 parts to 200 parts. A cured epoxy resin composition containing silica powder was obtained in the same manner as in Example 1 except for the above. The light transmittance of this cured product was about 70% at a thickness of 4 mm.

[Example 5] The amount of surface-treated silica powder was changed from 90 parts to 60 parts. A cured epoxy resin composition containing silica powder was obtained in the same manner as in Example 2 except for the above.

The light transmittance of this cured product was about 85% at a thickness of 4 mm.

[Example 6] The amount of surface-treated silica powder was changed from 90 parts to 370 parts. A cured epoxy resin composition containing silica powder was obtained in the same manner as in Example 3 except for the above. The light transmittance of this cured product was approximately 70% at a thickness of 4 mm.

[Comparative Example 4] Using 100 parts of bisphenol A type epoxy resin (liquid resin), 100 parts of 4-methylhexafluhydrophthalic anhydride, and 0.4 parts of 2-ethyl-4-methylimidazole without using silica powder. They were added and mixed to obtain an epoxy resin composition.

Next, a light emitting diode was resin-sealed by casting using the epoxy resin compositions obtained in Examples 1 to 6 and Comparative Example 4 to produce an optical semiconductor device. Then, the deterioration of the energized brightness of this optical semiconductor device was measured. The results are shown in the table below. Note that the above-mentioned method for measuring the deterioration in energization brightness was performed as follows. That is, the above optical semiconductor device (
A constant current was applied to the LED device (LED device), and the output current value of the light-receiving element 5 seconds after the current application was determined as the brightness, and the deterioration rate was measured.

Package: 5mm diameter pilot lamp.

Evaluation element: GaAs, 0.5mm x 0.5mm.

Evaluation conditions: -30"C, 20mA current, 1000
The brightness deterioration rate after time was measured.

(The following is a margin.) From the results in the above table, it can be seen that the actual height measurement has suppressed brightness deterioration and has improved light transmittance and low stress property compared to the comparative product.

Claims (6)

[Claims] (1) Contains the following components (A) to (E), and the difference between the refractive index of the silica powder of component (D) and the refractive index of the cured epoxy resin body consisting of components (A) to (C) is ± An optical semiconductor device in which an optical semiconductor element is sealed using an epoxy resin composition set in a range of 0.01. (A) Transparent epoxy resin. (B) Acid anhydride curing agent. (C) Curing catalyst. (D) Silica powder. (E) Silane coupling agent. (2) The optical semiconductor device according to claim (1), wherein the silane coupling agent as component (E) has an epoxy group or an amino group. (3) The optical semiconductor device according to claim 1 or 2, wherein the content of the silica powder as component (D) is 10 to 70% by weight of the entire epoxy resin composition. (4) The optical semiconductor device according to any one of claims (1) to (3), wherein the transparent epoxy resin of component (A) is at least one of a bisphenol type epoxy resin and an alicyclic epoxy resin. (5) The silica powder of component (D) has an average particle size of 3 to 60μ
The optical semiconductor device according to any one of claims (1) to (4), wherein the optical semiconductor device has a range of m. (6) Contains the following components (A) to (E), and the difference between the refractive index of the silica powder of component (D) and the refractive index of the cured epoxy resin body consisting of components (A) to (C) is ± An epoxy resin composition for encapsulating optical semiconductors set in a range of 0.01. (A) Transparent epoxy resin. (B) Acid anhydride curing agent. (C) Curing catalyst. (D) Silica powder. (E) Silane coupling agent.