JP2796187B2 - Optical semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device resin-sealed with a locking resin having excellent light transmittance and low stress.

[Conventional technology]

As a sealing resin composition used for sealing an optical semiconductor element such as an LED (light emitting diode), it is required that the cured product has transparency, and in general, bisphenol A type epoxy resin, An epoxy resin composition obtained by using an epoxy resin such as a cyclic epoxy resin and an acid anhydride as a curing agent is widely used.

However, when the epoxy resin composition is used as a sealing resin, curing shrinkage during curing of the epoxy resin composition, or cooling shrinkage when cooling from the curing temperature to room temperature,
At the adhesive interface between the epoxy resin composition and the optical semiconductor element,
Strain occurs due to the difference in linear expansion coefficient between the epoxy resin composition and the optical semiconductor element, and internal stress is generated. as a result,
When the optical semiconductor element is deteriorated, for example, when the optical semiconductor element is a light emitting element, there arises a problem that its luminance is reduced. For this reason, conventionally, as a method of reducing the internal stress, a method of adding an inorganic powder having 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 Has been proposed and implemented in part.

[Problems to be solved by the invention]

However, the above method has a fatal defect as a resin composition for encapsulating an optical semiconductor 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 for reducing the difference in the refractive index between the resin component and the silica powder has been proposed and implemented (Japanese Patent Application Laid-Open No. 49-23847). By simply reducing the difference in the refractive index of, for example, the light transmittance of a cured epoxy resin composition having a thickness of 2 mm is about 70%,
As a resin composition for encapsulating high-performance optical semiconductor devices such as high-brightness diodes (LEDs), the resin composition for optical semiconductor encapsulation having a higher light transmittance and an excellent low stress property has been developed. Coveted.

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

[Means for solving the problem]

In order to achieve the above object, an optical semiconductor device of the present invention includes the following components (A) to (D), wherein the refractive index of the silica powder (D) and the components (A) to (C) are The optical semiconductor element is sealed using an epoxy resin composition in which the difference from the refractive index of the epoxy resin cured product is set within a range of ± 0.01.

(A) Transparent epoxy resin.

(B) an acid anhydride-based curing agent.

(C) a curing catalyst.

(D) Crack-free spherical silica powder.

[Action]

That is, the present inventors have repeated a series of studies in order to obtain a sealing resin having small internal stress and excellent light transmittance. In the course of the study, the crushed silica powder was first used, but the cured product obtained had low light transmittance. Therefore, the low light transmittance is caused by cracks formed in the crushed silica powder, and it is supposed that this crack is for irregularly reflecting light, and in order to prevent irregular reflection and increase light transmittance. , Further research. As a result, using spherical silica powder without cracks,
Further, the inventors have found that when the refractive index of the special spherical silica powder is made to be close to that of the cured epoxy resin, a sealing resin having a transparent and reduced internal stress can be obtained.

The epoxy resin composition used in the present invention comprises a transparent epoxy resin (component A) and an acid anhydride-based curing agent (component B).
, A curing catalyst (C component), and a special spherical silica powder (D
Component), and is usually a liquid,
It is in the form of a powder or a tablet obtained by compressing this powder.

As the transparent epoxy resin (component A), a bisphenol-type epoxy resin and an alicyclic epoxy resin are preferable because of their transparency, but other epoxy resins may be used in some cases. When the other epoxy resin is used, it is generally preferable to set the usage ratio to 50% by weight or less (hereinafter abbreviated as “%”) of the entire epoxy resin. As such an epoxy resin, generally,
Those having an epoxy equivalent of 100 to 1000 and a softening point of 120 ° C. or less are used. Incidentally, the transparency of the transparent epoxy resin,
Including the case of colored and transparent, it is equivalent to a thickness of 1 mm and has a light transmittance of 80 to 100% at a wavelength of 600 nm (measured by a spectrophotometer).

The acid anhydride-based curing agent (component B) used together with the transparent epoxy resin (component A) includes a molecular weight of 140 to 2
Those having about 00 are preferably used, and examples thereof include colorless to pale yellow acid anhydrides such as hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride. The compounding amount of the acid anhydride-based curing agent is the above-mentioned transparent epoxy resin.
It is preferable to set the amount in the range of 50 to 200 parts with respect to 100 parts by weight (hereinafter abbreviated as "part").

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

As a method for setting the difference between the refractive index of the special spherical silica powder (D component) and the refractive index of the cured epoxy resin composition composed of the above A to C components in a range of ± 0.01, the following methods (1) to (4) are used. Is raised.

A method of adjusting the refractive index of only the cured epoxy resin composition comprising the components A to C (for example, selection of the type of the component A, use of two or more types of the component A or selection of the type of the component B, 2 or more types).

A method of adjusting the refractive index of the D component (special spherical silica powder).

 A method using the above and in combination.

As the special spherical silica powder (D component) used together with the A component (transparent epoxy resin), the B component (acid anhydride curing agent), and the C component (curing catalyst), a fusible one is used. Preferably, the refractive index of the spherical silica powder itself is adjusted according to the above method. Specifically, the refractive index (usually about 1.46) of the silica powder itself is adjusted by mixing a small amount of a metal oxide such as lead oxide and titanium oxide into the spherical silica powder to adjust the refractive index of the epoxy resin (usually about 1.54). ) Is generally approximated.

And it is necessary to use such a spherical silica powder having no crack. That is, in the crushed silica powder, there are many cracks generated in the crushing step at the time of manufacturing, and the crack causes light scattering, and even if the epoxy resin composition and the silica powder are used as described above. This is because a satisfactory light transmittance cannot be obtained even if the refractive index is approximated. In addition, it is preferable that the particle shape of the silica powder is spherical in order not to damage the optical semiconductor element. Such spherical silica powder without cracks is produced, for example, as follows. That is, it is produced by heating the crushed silica to near its melting point to change the particles from crushed to spherical, and at the same time, to eliminate the cracks by fusion. Alternatively, it is produced by polymerizing an alkoxysilane in a solvent containing water (sol-gel method).

Although such a spherical silica powder is not particularly limited, it is usually preferable to use a powder having an average particle diameter of 1 to 60 μm. However, the transparent epoxy resin (A
When the component (a) is liquid, precipitation of silica powder occurs at the time of compounding. Therefore, it is preferable to use one having an average particle size of 3 μm or less. When the average particle size is 3 μm or less, the viscosity of the epoxy resin composition becomes high, and there is a concern that the moldability may be reduced. In this regard, heating the epoxy resin and silica powder at the time of mixing is devised. That can be avoided. Further, the content (D component) of the special spherical silica powder is preferably set in the range of 10 to 70% of the entire epoxy resin composition.

Further, a silane coupling agent may be used together with the component A (transparent epoxy resin), component B (acid anhydride curing agent), component C (curing catalyst) and component D (silica powder). By using the silane coupling agent, the adhesion between the epoxy resin and the spherical silica powder (D component) is increased, and the transparency of the cured product can be improved.
As such a silane coupling agent, those having an epoxy group or an amino group are preferable, and specifically,
Examples of those having an epoxy group include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and the like. As those having, N-β-aminoethyl-γ
-Aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane,
γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like. The amount of the silane coupling agent used is preferably set in the range of 0.5 to 3% based on the spherical silica powder (D component).

The epoxy resin composition used in the present invention may contain, in addition to the components A to D, a dye, a modifier, a discoloration inhibitor, an antioxidant, a release agent, a reactive or non-reactive diluent, if necessary. Conventionally known additives such as an agent can be appropriately compounded.

In the epoxy resin composition used in the present invention, the difference between the refractive index of the cured epoxy resin composed of the components A, B and C and the refractive index of the component D (spherical silica powder) is ± 0.01. Must be used. The refractive index is measured using an Atsube refractometer.

The epoxy resin composition used in the present invention can be produced, for example, as follows. That is, it can be manufactured by blending the above-mentioned components A to D and a conventionally known additive, melt-mixing, cooling the mixture to room temperature, pulverizing by a known means, and tableting as necessary. When the epoxy resin composition is a liquid, it is only necessary to mix the above components.

The sealing of the 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 and casting.

The optical semiconductor device obtained in this manner has excellent transparency, extremely low internal stress, and high reliability.
This is presumably because light scattering is suppressed by adding spherical silica powder having no crack, and the difference in refractive index between the cured product of the resin component and the spherical silica powder is very small.

〔The invention's effect〕

As described above, the optical semiconductor device of the present invention includes an epoxy resin composition containing a spherical silica powder having no crack, and a difference in refractive index between the spherical silica powder and the cured product of the resin component within a specific range. Since the optical semiconductor element is formed by resin sealing, the sealing resin is excellent in light transmittance and has a small internal stress. It is expensive.

 Next, examples will be described together with comparative examples.

Example 1 65 parts of a bisphenol A type epoxy resin (liquid resin) having an epoxy equivalent of 185, 35 parts of an alicyclic epoxy resin (liquid resin) having an epoxy equivalent of 252 represented by the following structural formula, 4-methylhexahydrophthalic anhydride (100 parts), 2-ethyl-4-methylimidazole (0.4 parts) (the cured resin of the above-mentioned resin composition has a refractive index of 1.528) and a refractive index of 1.528.
Then, 90 parts of a crack-free spherical silica powder (mixed with a metal oxide) having an average particle size of 2.5 μm, and a mixture obtained by adding and mixing are thermally cured at 120 ° C. to obtain a cured epoxy resin composition containing the spherical silica powder. Was. The light transmittance of this cured product is 4m thick
It was as high as 81% at m.

[Example 2] 77 parts of a bisphenol A type epoxy resin (liquid resin) having an epoxy equivalent of 185, 23 parts of a bisphenol AF type epoxy resin (liquid resin) having an epoxy equivalent of 240 represented by the following structural formula, 4-methylhexahydrophthalic anhydride (100 parts), 2-ethyl-4-methylimidazole (0.4 parts) (the cured product of the above-mentioned resin composition has a refractive index of 1.534) and a refractive index of 1.534.
A mixture of 90 parts of a crack-free spherical silica powder (containing a metal oxide) having an average particle size of 2.5 μm, and heat-cured at 120 ° C. to form a cured epoxy resin composition containing the spherical silica powder. I got The light transmittance of this cured product was as high as 80% at a thickness of 4 mm.

Example 3 80 parts of bisphenol A type epoxy resin (solid resin) having an epoxy equivalent of 650, triglycidyl isocyanate 20
Parts, tetrahydrophthalic anhydride 50 parts, 2-ethyl-4-
Crack-free spherical silica powder (metal oxide mixed with 0.461 parts of methylimidazole (refractive index of the cured product of the above-mentioned resin composition is 1.561) and refractive index of 1.561 and average particle size of 25 μm) ) Was added, melt-mixed, cooled and solidified, and then pulverized to obtain a powdery epoxy resin composition. This composition was thermally cured at 150 ° C. by transfer molding to obtain a cured epoxy resin composition containing spherical silica powder. The light transmittance of this cured product was as high as 80% at a thickness of 4 mm.

[Example 4] A spherical silica powder (containing a metal oxide) having a refractive index of 1.528 and an average particle size of 2.5 µm and having no cracks was used as a catalyst.
Parts used. Otherwise in the same manner as in Example 1, a spherical silica-containing epoxy resin composition cured product was obtained. The light transmittance of this cured product was as high as 80% at a thickness of 4 mm.

Example 5 23 parts of a crack-free spherical silica powder (containing a metal oxide) having a refractive index of 1.534 and an average particle size of 2.5 μm were used. Otherwise in the same manner as in Example 2, a spherical silica-containing epoxy resin composition cured product was obtained. The light transmittance of this cured product was as high as 82% at a thickness of 4 mm.

Example 6 80 parts of a bisphenol A type epoxy resin (solid resin) having an epoxy equivalent of 650 and triglycidyl isocyanate 20
Parts, tetrahydrophthalic anhydride 50 parts, 2-ethyl-4-
Crack-free spherical silica powder (metal oxide mixed with 0.461 parts of methyl imidazole (refractive index of cured product of the above-mentioned resin composition is 1.561) and refractive index of 1.561 and average particle size of 70 μm ) Was added, melt-mixed, cooled and solidified, and then pulverized to obtain a powdery epoxy resin composition. This composition was thermally cured at 150 ° C. by transfer molding to obtain a cured epoxy resin composition containing spherical silica powder. The light transmittance of this cured product was as high as 83% at a thickness of 4 mm.

Comparative Example 1 80 parts of a bisphenol A type epoxy resin (solid resin) having an epoxy equivalent of 650 and triglycidyl isocyanate 20
Parts, tetrahydrophthalic anhydride 50 parts, 2-ethyl-4-
To 0.4 part of methylimidazole (refractive index of the cured product of the above-mentioned resin composition is 1.561), crushed silica powder having a refractive index of 1.561 and a crack having an average particle size of 25 μm is formed.
110 parts were added, melt-mixed, cooled and solidified, and pulverized to obtain a powdery epoxy resin composition. This composition was thermally cured at 150 ° C. by transfer molding to obtain a cured epoxy resin composition. Although the refractive index of the cured epoxy resin composition was equal to that of the crushed silica powder, the obtained cured product had a light transmittance of 50% at a thickness of 4 mm.

Comparative Example 2 Without using silica powder, 100 parts of a bisphenol A type epoxy resin (liquid resin) having an epoxy equivalent of 185, 100 parts of 4-methylhexahydrophthalic anhydride, 2-ethyl-4-
0.4 parts of methylimidazole was mixed to obtain an epoxy resin composition.

Next, using the epoxy resin compositions obtained in Examples 1 to 6 and Comparative Example 2, a light emitting diode was resin-sealed to produce an optical semiconductor device. Then, the current-carrying luminance degradation of this optical semiconductor device was measured. The results are shown in the table below. The method for measuring the current-carrying luminance degradation was performed as follows. That is, a constant current was applied to the optical semiconductor device (LED device), and as a luminance, an output current value of the light receiving element after 5 seconds from the current application was obtained, and the deterioration rate was measured.

Package: Pilot lamp with a diameter of 5mm.

Evaluation element: GaAs, 0.5 mm x 0.5 mm.

Evaluation conditions: The luminance degradation rate was measured after 1000 hours of 20 mA conduction at −30 ° C.

From the results in the above table, it can be seen that the luminance of the example product is suppressed as compared with the comparative example product, and the low stress property as well as the light transmittance is improved.

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Claims (4)

(57) [Claims] Claims: 1. A composition comprising the following components (A) to (D):
An optical semiconductor device is prepared by using an epoxy resin composition in which the difference between the refractive index of the silica powder as the component and the refractive index of the epoxy resin cured product of the components (A) to (C) is set within a range of ± 0.01. An optical semiconductor device formed by sealing. (A) Transparent epoxy resin. (B) an acid anhydride-based curing agent; (C) a curing catalyst. (D) Crack-free spherical silica powder. 2. The optical semiconductor device according to claim 1, wherein the transparent epoxy resin as the component (A) is at least one of a bisphenol type epoxy resin and an alicyclic epoxy resin. 3. The content of the silica powder (D) is 10 to 70% by weight of the whole epoxy resin composition.
Or the optical semiconductor device according to (2). 4. A composition comprising the following components (A) to (D):
An epoxy resin composition for encapsulating an optical semiconductor, wherein the difference between the refractive index of the silica powder as the component and the refractive index of the epoxy resin cured product composed of the components (A) to (C) is set within a range of ± 0.01. (A) Transparent epoxy resin. (B) an acid anhydride-based curing agent; (C) a curing catalyst. (D) Crack-free spherical silica powder.