JP2001207034A - Epoxy resin composition for sealing optical semiconductor, and optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition used for sealing an optical semiconductor and excellent in clarity and resistance to soldering and to provide an optical semiconductor device sealed with a cured item of the composition. SOLUTION: The epoxy resin composition essentially comprises a reaction product of a phenolic compound having a specified structure and triglycidyl isocyanurate in a specified ratio, an acid anhydride curative, and a cure accelerator. The optical semiconductor device is prepared by sealing with a cured item of the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for encapsulating an optical semiconductor having excellent transparency and solder resistance, and an optical semiconductor device encapsulated with a cured product thereof.

[0002]

2. Description of the Related Art In the field of optoelectronics, bisphenol A type epoxy resins and triglycidyl isocyanurate are commonly used epoxy resins for optical semiconductor encapsulation. However, epoxy resins having relatively low water absorption, such as bisphenol A type epoxy, have low heat resistance, and polyfunctional epoxy resins containing no aromatic ring, such as triglycidyl isocyanurate, which has high heat resistance and excellent transparency, have a high water absorption. Is high.
Therefore, when such a conventional optical surface mount type package using an epoxy resin is mounted by IR reflow or the like,
There has been a problem that cracks in the package due to thermal shock and separation between the element / lead frame and the resin occur.

On the other hand, in an epoxy resin composition using a phenol novolak resin as a curing agent, although the water absorption can be reduced, the methylene group in the molecular structure is easily oxidized by an active radical species and is markedly colored by heat. There were drawbacks.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin composition for optical semiconductor encapsulation which is excellent in transparency and solder resistance, and an optical semiconductor device encapsulated with a cured product thereof. I do.

[0005]

Means for Solving the Problems The present inventors have proposed transparency,
A compound obtained by reacting triglycidyl isocyanurate, a polyfunctional epoxy with excellent heat resistance, with a phenolic compound having a specific structure, which has a reduced water absorption, improves heat resistance, and is also excellent in transparency, an acid anhydride curing agent, By using a resin composition characterized by including a curing accelerator as an essential component, the above object has been achieved.

That is, the present invention relates to a compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group substituted on carbon of the phenol nucleus; A molar ratio of the triglycidyl isocyanurate (B) to the molar number (a) of the hydroxyl group of the component (A) and the molar number (b) of the epoxy group of the component (B),
(A): An epoxy for optical semiconductor encapsulation, comprising, as essential components, a compound (C) reacted at a ratio of 1: 1 to 6 and an acid anhydride curing agent and a curing accelerator. An optical semiconductor device sealed with a resin composition and a cured product thereof.

Compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus
Is preferably an alkyl-substituted or unsubstituted bisphenol A, an alkyl-substituted or unsubstituted bisphenol S,
Alkyl-substituted or unsubstituted biphenol, bisphenolfluorene, 2- (4-hydroxyphenyl) -2-
[4- [1,1-bis (4-hydroxyphenyl) ethyl] phenyl] propane.

In the compound (C), a compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus. ) And triglycidyl isocyanurate (B), the molar ratio of the number of moles of hydroxyl groups (a) of component (A) to the number of moles of epoxy groups (b) of component (B) is preferably (a) ): (B) = 1: 2-4
The reaction was carried out at the ratio of

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus used in the present invention. Specific examples are not limited as long as they do not have the methylene hydrogen which is easily oxidized by an active radical species. And alkyl substituted products thereof, bisphenolfluorene, dihydroxynaphthalene, 2- (4-hydroxyphenyl) -2- [4- [1,1-bis (4-hydroxyphenyl) ethyl] phenyl] propane and the like. , Alkyl-substituted or unsubstituted bisphenol A, alkyl-substituted Other unsubstituted bisphenol S, alkyl-substituted or unsubstituted biphenol, bisphenol fluorene, 2- (4-hydroxyphenyl) -2- [4
-[1,1-bis (4-hydroxyphenyl) ethyl]
[Phenyl] propane is preferred in terms of low water absorption, light transmission and heat resistance.

Next, a compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group on carbon substituted on the phenol nucleus, and triglycidyl isocyanate A molar ratio of the number of moles (a) of the hydroxyl group of the component (A) to the number of moles (b) of the epoxy group of the component (B) when the compound (C) is obtained by reacting the compound with the nurate (B); ): Regarding (b),
If the ratio of (a) :( b) = 1: 1 to 6, transparency, heat resistance, and low water absorption, which are the objects of the present invention, can be achieved at the same time.
If (a) :( b) = 1: 2 to 4, unreacted components can be reduced, and control of the reaction is easy, so that it is more preferable. If the ratio is out of the above range, the reaction may not proceed well or various characteristics may be deteriorated.

The details of the reason why the transparency, heat resistance and low water absorption of the compound (C) used in the present invention can be made clear are unknown,
The component (A) of the present invention probably has two or more phenolic hydroxyl groups in one molecule between the molecules of triglycidyl isocyanurate and has a methylene hydrogen belonging to an aralkyl group on the carbon substituted on the phenol nucleus. It is conceivable that the presence of a compound that does not exist may behave differently from a system in which triglycidyl isocyanurate is simply mixed with the corresponding epoxidized component (A) when the compound enters into the system to some extent.

As the reaction between the compound (A) and the triglycidyl isocyanurate (B), a method for elongating an epoxy resin, which is generally used by those skilled in the art, can be used. For example, the compound (A) and the compound (B) are subjected to a heat reaction using a catalyst with little coloring in a tertiary amine, a quaternary ammonium salt, an organic phosphine, a quaternary phosphonium salt or the like without solvent or using a solvent. Just do it. The reaction rate between the phenolic hydroxyl group and the epoxy group in this case is not particularly limited, but belongs to an aralkyl group having two or more phenolic hydroxyl groups in one molecule and substituted on the carbon of the phenol nucleus. It is sufficient that the reaction has proceeded to such an extent that the unreacted portion of the compound (A) having no methylene hydrogen does not precipitate at least when cooled to room temperature.

The acid anhydride curing agent used in the present invention includes phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride and 4-methyl- Examples include hexahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, and the like, but are not particularly limited thereto, and may be used alone or in combination of two or more.

As the curing accelerator used in the present invention, any of those usually used for anionic curing of an epoxy resin can be used, but, for example, imidazoles, tertiary amines, quaternary ammonium salts, diaza, etc. Bicyclic amidines such as bicycloundecene and derivatives thereof, phosphines, phosphonium salts and the like are generally used, but are not limited as long as they have good curability and are not colored. The above may be used.

The epoxy resin composition for encapsulating an optical semiconductor of the present invention may contain, if necessary, another epoxy resin, an antioxidant,
Combination of additives and auxiliary materials known to those skilled in the art, such as a release agent and a coupling agent, can be used at all.

The epoxy resin composition for encapsulating an optical semiconductor of the present invention can be obtained, for example, by the following production method. The above components are appropriately blended and uniformly mixed, then melt-mixed by a kneader, and the obtained molten mixture is cooled and pulverized to obtain a mixture.

The encapsulation using the thus obtained epoxy resin composition for encapsulating an optical semiconductor can be performed by a general method. For example, the optical semiconductor element is encapsulated by a transfer molding method or the like. Thus, an optical semiconductor device sealed with a cured product of the epoxy resin composition can be obtained.

[0018]

The present invention is described below by way of examples, which should not be construed as limiting the present invention.

[Synthesis of Compound (C)] (Synthesis Example 1) Bisphenol A11 was placed in a 2 L flask.
4.2 g (1 mol of hydroxyl group), 346.8 g of triglycidyl isocyanurate (3.5 mol of epoxy group) and 0.3 g of tetrabutylphosphonium hydroxide were charged, and the oil bath was set at 140 ° C., and 2 hours while flowing nitrogen. The reaction was performed to obtain a product 1. The obtained product was cooled to room temperature, but no precipitation of bisphenol A was observed.

(Synthesis Examples 2 to 10) All the basic operations were carried out in the same manner as in Synthesis Example 1 to obtain a product. Table 1 shows the details.

[0021]

[Table 1]

(Examples 1 to 7, Comparative Examples 1 to 3) The resin compositions of the present invention were mixed by heating at the mixing ratios shown in Table 2,
After cooling, the mixture was pulverized to obtain a resin composition. The resin composition was cooled to a mold temperature of 17 using a low-pressure transfer molding machine.
5 ° C., injection pressure 6.86 × 10 ⁶ Pa, curing time 2 minutes,
Test pieces used in each test were produced under the conditions of post cure at 150 ° C. for 2 hours. The evaluation method is as follows. The results are summarized in Table 2.

(Measurement of Light Transmittance) A test piece of 10 × 30 × 1 mm was prepared, and a test piece having a thickness of 1 mm and a thickness of 4 mm was measured using a spectrophotometer (Shimadzu Corporation UV-3100).
The light transmittance at 00 nm was measured. (Measurement of Moisture Absorption Rate) A disk-shaped test piece having a diameter of 50 mm and a thickness of 3 mm was prepared and left in a high-temperature and high-humidity bath set at 85 ° C. and a humidity of 85%. It was measured. (Measurement of glass transition temperature) A test piece of 10 × 5 × 5 mm was prepared and measured by using TMA at a heating rate of 5 ° C./min, and measured. The temperature at which the elongation of the test piece rapidly changed was measured. And (Evaluation of solder resistance) Surface mount package (12 pins,
4 × 5mm, thickness 1.2mm, chip size 1.5m
mx 2.0mm, lead frame made of 42 alloy),
Transfer molding was performed at a mold temperature of 175 ° C., an injection pressure of 6.86 × 10 ⁶ Pa, and a curing time of 2 minutes, and post-curing was performed at 150 ° C. for 2 hours. 85 obtained optical semiconductor package
It was left for 168 hours in an environment of 85 ° C. and a relative humidity of 85%, and then subjected to an IR reflow treatment at 240 ° C. The processed package was examined with a microscope and an ultrasonic flaw detector to check for cracks and separation between the chip and the resin.

[0024]

[Table 2]

As is clear from the results shown in Table 2, the resin composition of the present invention has transparency, heat resistance and low water absorption at the same time.
It turns out that it has good soldering resistance.

[0026]

The epoxy resin composition for encapsulating an optical semiconductor of the present invention and the optical semiconductor device encapsulated with the cured product thereof are excellent in transparency and solder resistance and have high reliability. Can be provided.

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Claims (4)

[Claims] 1. A compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group substituted on carbon of the phenol nucleus, and triglycidyl isocyanurate (B) a molar ratio of the number of moles of hydroxyl groups (a) of the component (A) to the number of moles (b) of epoxy groups of the component (B);
(A): An epoxy for optical semiconductor encapsulation, comprising, as essential components, a compound (C) reacted at a ratio of 1: 1 to 6 and an acid anhydride curing agent and a curing accelerator. Resin composition. 2. A compound (A) having two or more phenolic hydroxyl groups in one molecule and having no methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus is alkyl-substituted or non-alkyl-substituted. Substituted bisphenol A, alkyl-substituted or unsubstituted bisphenol S, alkyl-substituted or unsubstituted biphenol, bisphenolfluorene, 2- (4-hydroxyphenyl) -2- [4
-[1,1-bis (4-hydroxyphenyl) ethyl]
The epoxy resin composition for optical semiconductor encapsulation according to claim 1, which is selected from the group of [phenyl] propane. 3. The compound (A) which has two or more phenolic hydroxyl groups in one molecule and has no methylene hydrogen belonging to an aralkyl group substituted on carbon of the phenol nucleus. ) And triglycidyl isocyanurate (B) in the molar ratio of the number of moles of hydroxyl groups (a) of component (A) to the number of moles of epoxy groups (b) of component (B), (a): ( The epoxy resin composition for optical semiconductor encapsulation according to claim 1, characterized in that b) = 1: 2 to 4 are reacted. 4. An optical semiconductor device encapsulated with a cured product of the epoxy resin composition for optical semiconductor encapsulation according to claim 1.