JPH056946A - Optical semiconductor device - Google Patents

Abstract

PURPOSE:To achieve the excellent light transmitting property and the small inner stress for a sealing resin by sealing an optical semiconductor element with the resin by using the epoxy resin composition containing silica-based particulates whose particle diameter is 0.5mum or less and refractive index is equal to that of hardened epoxy resin body. CONSTITUTION:The components of a transparent epoxy resin a hardening agent and a silica-based particulates whose average particle diameter is 0.5mum or less are contained. The difference between the refractive index of the silica- based particulate and particulate and the refractive index of the hardened epoxy resin body wherein a transparent epoxy resin and a hardening agent are main materials, is sent within the range of + or -0.01 in the epoxy resin composition. An optical semiconductor element is sealed by using this epoxy resin composition. The coefficient of variation of the particle diameter of the silica-based particulate is made to be 10% or less. In this way, the optical semiconductor device whose inner stress is less and transparency is excellent is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device resin-encapsulated with an encapsulating resin which is excellent in both light transmittance and low stress.

[0002]

2. Description of the Related Art A resin composition used for encapsulating an optical semiconductor element such as an LED (light emitting diode) is required to have a cured product having transparency. Generally, a bisphenol type epoxy resin, An epoxy resin composition comprising an epoxy resin such as an alicyclic epoxy resin and a curing agent is used.

However, when the above-mentioned epoxy resin composition is used as a sealing resin, internal contraction occurs due to curing shrinkage of the epoxy resin composition at the time of curing, or distortion caused by a difference in linear expansion coefficient between the epoxy resin and the optical semiconductor element. A stress is generated, and the optical semiconductor element is deteriorated due to the stress. For example, when the optical semiconductor element is an LED, there is a problem that the brightness thereof is lowered. In order to solve such a problem, it is necessary to reduce the internal stress of the epoxy resin, and as one of the methods, the epoxy resin is added by adding an inorganic powder having a small linear expansion coefficient such as silica particles to the epoxy resin. A method has been proposed in which the linear expansion coefficient of the cured product of the composition is reduced to approximate that of an optical semiconductor device.

[0004]

However, in the above method, the internal stress can be reduced, but the light transmittance of the resulting cured epoxy resin composition is remarkably reduced. As a product, it has a fatal drawback.

The present invention has been made in view of such circumstances, and relates to an optical semiconductor device having a small internal stress and excellent transparency.

[0006]

In order to achieve the above object, an optical semiconductor device of the present invention has the following (A) to (C).
The difference between the refractive index of the silica-based fine particles that are the component (C) and the cured epoxy resin mainly composed of the components (A) and (B) is set within a range of ± 0.01. The epoxy semiconductor composition described above is used to seal the optical semiconductor element. (A) Transparent epoxy resin. (B) Hardener. (C) Silica-based fine particles having an average particle diameter of 0.5 μm or less.

The term "mainly composed of" is intended to include the case where the whole is composed of the main constituents.

[0008]

In other words, the present inventors have a small internal stress,
Moreover, a series of studies were conducted in order to obtain a sealing resin having excellent light transmittance. In the course of the research, when silica particles are added to the epoxy resin, the light transmittance decreases because the particle size of the silica particles is large and the refractive index of the silica particles is different from that of the cured epoxy resin. I remembered that. Based on this idea, the following two methods are conceivable as a method for improving the light transmittance of the cured silica particle-filled epoxy resin composition. Make the particle size of silica particles very small. The refractive index of the silica particles and the refractive index of the cured epoxy resin are made equal. Then, as a result of examining the above, the average particle diameter of the silica particles is 0.1 μ
It has been found that when the thickness is m or less, it is transparent and the light transmittance is high. Furthermore, as a result of examining the above, the average particle diameter of the silica particles is 0.5 μm or less (for example, 0.1 to 0.
5 μm), the refractive index of the silica particles and the refractive index of the cured epoxy resin are substantially equal (the difference between them is ± 0.
The inventors have found that a transparent encapsulating resin having a light transmittance of 01 or less) and excellent in light transmittance can be obtained, and further, the internal stress can be reduced, and the present invention has been reached.

In general, "silica" may mean pure quartz. However, since the silica particles having a controlled refractive index in the present invention include a metal oxide such as titanium oxide, the silica used in the present invention. Particles are "silica-based particles"
And

The epoxy resin composition used in the present invention is
Transparent epoxy resin (component A) and curing agent (component B)
And a specific silica-based fine particle (component C), which is usually in the form of a liquid, a powder, or a tablet obtained by tableting this powder.

As the transparent epoxy resin (component A), bisphenol type epoxy resin, alicyclic epoxy resin and the like are preferably used because they have transparency. However, in some cases, other epoxy resins may be used in combination without any problem. When another epoxy resin is used as described above, it is usually preferable to set the usage ratio to 50% by weight or less based on the whole epoxy resin. Such transparent epoxy resin and other epoxy resins used together therewith generally have an epoxy equivalent of 100 to 1000 and a softening point of 1.
The thing below 20 degreeC is used. As these epoxy resins, those which are liquid at room temperature or those which are solid at room temperature are appropriately selected and used. The transparency of the transparent epoxy resin includes the case of being colored and transparent, and corresponds to a thickness of 1 mm.
It has a light transmittance of 80 to 100% at a wavelength of 600 nm (measured by a spectrophotometer).

The curing agent (component B) used together with the transparent epoxy resin (component A) has a molecular weight of 140
Approximately 200 to 200 are preferably used. For example, colorless or pale yellow acid anhydrides such as hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride are used alone or in combination. Used. The amount of the curing agent is set in the range of 50 to 200 parts with respect to 100 parts by weight (hereinafter, abbreviated as "part") of 100 parts by weight of the transparent epoxy resin (including other epoxy resin when used in combination). It is preferable.

The specific silica-based fine particles (component C) used together with the transparent epoxy resin (component A) and the curing agent (component B) have an average particle diameter of 0.5 μm or less, particularly 0.1 μm. It is preferable to use those having a diameter of more than 0.5 μm and not more than 0.5 μm. Further, it is preferable that the variation coefficient of the particle diameter (a value relatively representing the variation of the particle diameter) is 10% or less. That is, when the particle size distribution of the silica-based fine particles is more sharp, an optically homogeneous cured product can be obtained. Such fine silica-based fine particles are produced by a special method developed by the present inventors, namely, a solvent, a liquid transparent epoxy resin, a solid transparent epoxy resin dissolved in an organic solvent or the like, and a solid transparent epoxy resin. It is synthesized by polymerizing alkoxysilane and alkoxytitanium as raw materials by a sol-gel method in a heat-meltable epoxy resin. The silica-based fine particles thus synthesized have a transparent epoxy resin as a matrix and do not cause secondary aggregation in a state of being uniformly dispersed in the matrix. More specifically, the silica-based fine particles can be synthesized, for example, by adding water, an alkoxysilane, and an alkoxytitanium to a solution of a transparent epoxy resin in an organic solvent and reacting them for a predetermined time. In the above synthesis, by increasing the content of alkoxy titanium,
The silica-based fine particles to be synthesized can have a high refractive index. Therefore, the difference between the refractive index of the silica-based fine particles and the refractive index of the epoxy resin cured product composed of the transparent epoxy resin, the curing agent and the curing catalyst can be set within a range of ± 0.01 or less.

Examples of the alkoxysilane include tetramethoxysilane, methyltrimethoxysilane, tetrapropoxysilane, methyltripropoxysilane, tetraethoxysilane, methyltriethoxysilane, n-propyltriethoxysilane, trimethylbutoxysilane, and dimethyldi. Examples thereof include ethoxysilane, which may be used alone or in combination.

Examples of the alkoxytitanium include tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium and tetrabutoxytitanium.
These may be used alone or in combination.

The mixing ratio of the alkoxysilane (X) and the alkoxytitanium (Y) is X: Y = 5: 9 in molar ratio.
It is preferably in the range of 5 to 50:50.

In the epoxy resin composition used in the present invention, in addition to the above-mentioned components A to C, a curing catalyst, a dye, a modifier, a discoloration preventing agent, an antiaging agent, a releasing agent, a reactive agent or a non-reactive agent, if necessary Conventionally known additives such as a reactive diluent can be appropriately added.

Examples of the curing catalyst include tertiary amines, imidazole compounds and organometallic complex salts.

Then, in the epoxy resin composition used in the present invention, the difference between the refractive index of the cured epoxy resin mainly composed of the components A and B and the refractive index of the silica-based fine particles which is the component C is Those within ± 0.01 are used. The refractive index is measured using an Atsube refractometer.

Such an epoxy resin composition can be manufactured, for example, as follows. That is, the above A to C components and other additives are appropriately blended,
After premixing, the mixture is kneaded in a kneader to melt and mix. Then, it can be manufactured by a series of steps in which it is cooled to room temperature, pulverized by a known means, and tableted if necessary. When the transparent epoxy resin used as the component A is liquid at room temperature, the component A itself becomes liquid, and therefore the target epoxy resin can be prepared by mixing only the other components with the component A. A composition can be obtained.

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. As a result, an optical semiconductor device is obtained in which an optical semiconductor element is encapsulated with an encapsulating resin layer made of the cured epoxy resin composition. In this case, silica-based fine particles having an average particle diameter of 0.5 μm or less are dispersedly contained in the encapsulating resin layer made of the cured transparent epoxy resin composition so as to account for 10 to 80% by weight of the entire cured body. Is preferred. That is, when the amount of silica-based fine particles is less than 10% by weight, the linear expansion coefficient of the cured product does not sufficiently decrease, and conversely 80
This is because if the content exceeds 10% by weight, the linear expansion coefficient decreases, but the viscosity of the resin increases and the moldability tends to deteriorate. The content of the silica-based fine particles can be calculated from the weight of the silica-based fine particles remaining as ash by burning the cured product of the transparent epoxy resin composition.

[0022]

As described above, the optical semiconductor device of the present invention uses an epoxy resin composition containing silica-based fine particles having a particle diameter of 0.5 μm or less and a refractive index equal to that of the epoxy resin cured product. It is obtained by resin-sealing a semiconductor element. Therefore, this encapsulating resin is excellent in light transmittance and has a small internal stress.
In that case, the luminance deterioration is effectively suppressed and the reliability is extremely increased.

Next, examples will be described together with comparative examples.

[0024]

Example 1 100 parts of a bisphenol A type epoxy resin (liquid resin) having an epoxy equivalent of 185 was added to 300 parts of ethanol.
Part and dissolved in the solution, tetraethoxysilane 89
Parts, 11 parts of tetraethoxy titanium, 90 parts of water, and 0.42 parts of 1,8-diazabicyclo (5,4,0) -7-undecene as a catalyst were added and reacted at 60 ° C. for 1 hour. Then, ethanol and water were removed under reduced pressure to obtain a liquid transparent epoxy resin containing silica-based fine particles. In this case, the particle diameter of the silica-based fine particles was about 0.2 μm, and the coefficient of variation of the particle diameter was 5%.

Next, to 200 parts of the above silica-based fine particle-containing transparent epoxy resin, 100 parts of 4-methylhexahydrophthalic anhydride, 0.4 part of 2-ethyl-4-methylimidazole, and 2.5 parts of antioxidant. Were mixed to obtain a liquid silica-based fine particle-containing epoxy resin composition. This is 12
The light transmittance of the cured product obtained by heat curing at 0 ° C. was as high as 83% at a thickness of 4 mm. In addition, in this cured product, the silica-based fine particles and the cured product of the epoxy resin composition excluding the silica-based fine particles each had a refractive index of 1.541.

[0026]

Example 2 A silica-based fine particle-containing cured epoxy resin composition was obtained in the same manner as in Example 1 except that tetraethoxysilane was replaced with methyltriethoxysilane. In this case, the particle diameter of the silica-based fine particles is about 0.2 μm, the coefficient of variation is 5%, and the light transmittance of the cured product is 8 mm at a thickness of 4 mm.
It was a high value of 1%. In addition, in this cured product, the silica-based fine particles and the cured product of the epoxy resin composition excluding the silica-based fine particles each had a refractive index of 1.541.

[0027]

Example 3 80 parts of a bisphenol A type epoxy resin having an epoxy equivalent of 650 (solid resin) was dissolved in 300 parts of an acetone / methyl ethyl ketone [50/50 (weight ratio)] mixed solvent, and 74 parts of tetraethoxysilane was added to the solution. ,
26 parts of tetraethoxy titanium, 90 parts of water, and 0.42 part of 1,8-diazabicyclo (5,4,0) -7-undecene as a catalyst were added and reacted at 60 ° C. for 1 hour.
Then, acetone, methyl ethyl ketone, and water were removed under reduced pressure to obtain a liquid transparent epoxy resin containing silica fine particles. In this case, the particle size of the silica-based fine particles was about 0.2 μm, and the coefficient of variation of the particle size was 6%.

Next, 180 parts of the transparent epoxy resin containing fine silica particles was added to 20 parts of triglycidyl isocyanurate (solid epoxy resin), 44 parts of tetrahydrophthalic anhydride, and 2-ethyl-4-methylimidazole.
4 parts and 2.5 parts of an antioxidant were mixed to obtain a silica-based fine particle-containing epoxy resin composition. The cured product obtained by thermosetting this at 150 ° C. has a light transmittance of 4
The value was as high as 83% in mm. Further, in this cured product, the silica-based fine particles and the cured product of the epoxy resin composition excluding the silica-based fine particles each have a refractive index of 1.566.
It was.

[0029]

Example 4 A cured product of an epoxy resin composition containing fine silica particles was obtained in the same manner as in Example 3 except that tetraethoxysilane was replaced with methyltriethoxysilane. In this case, the silica-based fine particles have a particle diameter of about 0.2 μm, a coefficient of variation of 6%, and a cured product having a light transmittance of 8 mm at a thickness of 4 mm.
It was a high value of 2%. In addition, in this cured product, the refractive index of the silica-based fine particles and the cured product of the epoxy resin composition excluding the silica-based fine particles were both 1.566.

[0030]

Comparative Example 1 100 parts of bisphenol A type epoxy resin (liquid resin) having an epoxy equivalent of 185, 100 parts of 4-methylhexahydrophthalic anhydride, 0.4 parts of 2-ethyl-4-methylimidazole, antioxidant 2 0.5 part was mixed to obtain an epoxy resin composition.

[0031]

Comparative Example 2 80 parts of bisphenol A type epoxy resin (solid resin) having an epoxy equivalent of 650, 20 parts of triglycidyl isocyanurate (solid epoxy resin), 44 parts of tetrahydrophthalic anhydride, 2-ethyl-4-methylimidazole 0 An epoxy resin composition was obtained by mixing 4 parts and 2.5 parts of an antioxidant.

Next, Examples 1 to 4 and Comparative Examples 1 and 2
A light emitting diode (LED) was resin-sealed with the epoxy resin composition obtained in (1) to produce an optical semiconductor device. Then, the deterioration of energization luminance of this optical semiconductor device was measured. The results are shown in Table 1 below. The method for measuring the deterioration of the energized luminance was performed as follows. That is, a constant current was applied to the above-mentioned optical semiconductor device (LED device), and the output current value of the light-receiving element 5 seconds after applying the current was calculated as the luminance to measure the deterioration rate.

Package: A pyro lamp with a diameter of 5 mm. Evaluation element: GaAs, 0.5 mm × 0.5 mm. Evaluation conditions: The luminance deterioration rate was measured after leaving for 20 hours at -30 ° C for 1000 hours after energization.

[0034]

[Table 1]

From the results shown in Table 1 above, it can be seen that the product of the example is suppressed in the deterioration of luminance and the light stress and the low stress property are improved as compared with the product of the comparative example.

Claims (4)

[Claims] 1. The following components (A) to (C) are included:
An epoxy resin in which the difference between the refractive index of the silica-based fine particles as the component (C) and the refractive index of the cured epoxy resin mainly composed of the components (A) and (B) is set within ± 0.01. An optical semiconductor device obtained by encapsulating an optical semiconductor element with a composition. (A) Transparent epoxy resin. (B) Hardener. (C) Silica-based fine particles having an average particle diameter of 0.5 μm or less. 2. The optical semiconductor device according to claim 1, wherein the variation coefficient of the particle diameter of the silica-based fine particles as the component (C) is 10% or less. 3. The following components (A) to (C) are included:
An optical semiconductor in which the difference between the refractive index of the silica-based fine particles which is the component (C) and the refractive index of the cured epoxy resin mainly composed of the components (A) and (B) is set within ± 0.01. Epoxy resin composition for encapsulation. (A) Transparent epoxy resin. (B) Hardener. (C) Silica-based fine particles having an average particle diameter of 0.5 μm or less. 4. The epoxy resin composition for optical-semiconductor encapsulation according to claim 3, wherein the variation coefficient of the particle diameter of the silica-based fine particles as the component (C) is 10% or less.