JP2970214B2 - Epoxy resin composition for optical semiconductor encapsulation - Google Patents

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, which provides a cured product having high transparency, excellent heat resistance and free from optical unevenness.

[0002]

2. Description of the Related Art An acid anhydride-cured epoxy resin is generally used as a sealing material for transfer molding of an optical semiconductor device such as a light-emitting device and a light-receiving device from the viewpoint of excellent electrical properties, heat resistance, moisture resistance and the like. I have. At this time, a high molecular weight bisphenol A type epoxy resin is often used as the epoxy resin because of its excellent transparency and moldability.

[0003]

However, when a bisphenol A type epoxy resin is used alone as the epoxy resin, the heat resistance of the cured product is insufficient. Also,
There has been a problem that optical unevenness occurs as a material flow trace during transfer molding. The method disclosed in JP-A-2-189958 for the above-mentioned problem is a method in which the epoxy resin composition is dispersed in an organic solvent, mixed, B-staged, and then the organic solvent is removed. And the moldability (void) and reliability due to the residual solvent. Also, a method of ultra-fine pulverization and mixing of molding materials described in JP-A-3-3258,
There were problems in the manufacturing process, such as the addition of an ultra-fine pulverizing process or measures against moisture absorption of ultra-fine powder. Further, in the above two methods, bisphenol A is used as a main component of the epoxy resin.
A type epoxy resin is used, but the number of repetitions n in the molecular structure is not specified. An object of the present invention is to provide an epoxy resin composition for encapsulating an optical semiconductor that provides a cured product having excellent transparency and heat resistance and having no optical unevenness.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and has a structure comprising an epoxy for encapsulating an optical semiconductor containing an epoxy resin, a curing agent, and a curing accelerator. The first feature of the resin composition is that the epoxy resin is mainly composed of a bisphenol A type epoxy resin represented by the following general formula.

[0005]

Embedded image (However, n = 1 to 5 in the above general formula.) Further, the epoxy resin is a mixture of the above bisphenol A type epoxy resin and an alicyclic epoxy resin and / or a heterocyclic epoxy resin, and the mixture thereof The second feature is that the ratio (weight ratio) is in the range of 90:10 to 50:50. That is, the present inventors have conducted a series of studies to obtain an epoxy resin composition for optical semiconductor encapsulation in which the above-mentioned object has been achieved. As the resin exists and the number of repetitions n in the molecular structure increases, it is easy to orient at the time of flow, and the idea was conceived that optical unevenness might occur.

As a result, the critical point is such that the number of repetitions n in the molecular structure of the bisphenol A type epoxy resin is substantially 5;
If a material exceeding this is used, a trace of resin flow will be remarkably generated in the cured product.
The inventors have found that almost no optical unevenness occurs in the cured product, and have reached the present invention. Therefore, the bisphenol A type epoxy resin used in the present invention has a molecular structure in which the repeating number n is in the range of 1 to 5.
If n is less than 1, it becomes difficult to form a molding material, and the subsequent tablet moldability also deteriorates. In the present invention, the resin used in combination with the bisphenol A type epoxy resin is an alicyclic epoxy resin and / or a heterocyclic epoxy resin. These resins are used to improve the heat resistance and transparency of the cured product, and it is necessary to select a resin having a glass transition temperature of 150 ° C. or more when each is cured alone.

Examples of the alicyclic epoxy resin include CY175, CY179 (above, manufactured by Ciba-Geigy) EHPE3150, Celloxide 2021P, Eporide GT300 (above, manufactured by Daicel Chemical), and heterocyclic epoxy resin. Is TEPIC
(Manufactured by Nissan Chemical Industries, Ltd.). Bisphenol A
The mixing ratio of the epoxy resin to the alicyclic epoxy resin and / or the heterocyclic epoxy resin is 90:10 to 50:
50 (% by weight) is preferable, and when the amount of bisphenol A type epoxy resin is large, the heat resistance and the transparency are greatly reduced. When the amount of the alicyclic epoxy resin and / or the heterocyclic epoxy resin is large, the heat resistance and the transparency are improved, but the mechanical strength of the cured product is significantly reduced.

The curing agent is not particularly limited, but is preferably an acid anhydride in consideration of the optical properties of the cured product. For example, phthalic anhydride, tetraphthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, polyazeleic anhydride and the like can be mentioned, and these are used alone or in combination. It is necessary to add the acid anhydride in an amount of 0.7 to 1.2 equivalents, preferably 0.8 to 1.1 equivalents, based on the epoxy resin. If it exceeds this range, the reaction will be insufficient and the physical properties of the cured product will be reduced. Conventionally known curing accelerators may be used,
For example, imidazoles, DBU and salts thereof, tertiary amines, quaternary ammonium salts, quaternary phosphonium salts and the like are exemplified, and this amount is 0.05 to 10% based on the total amount of the epoxy resin and the acid anhydride. %, More preferably 0.1 to
What is necessary is just to make it 5%. The epoxy resin composition for encapsulating an optical semiconductor may further include a releasing agent, an antioxidant, a coloring agent, an ultraviolet absorber, a visible light absorber, an infrared absorber, a modifier, in addition to the above components, as required. Conventionally known additives such as inorganic fillers are used.

[0009]

EXAMPLES The present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition,
The test method in the following examples is shown below . (1) Light transmittance Using a spectrophotometer (Hitachi U-2000 type), thickness 2
The light transmittance at a wavelength of 570 nm was measured for the molded product of mm. (2) Glass transition temperature For a molded product having a diameter of 4 mm and a length of 20 mm, TMA (PTC-10A type manufactured by Rigaku Corp.) was used as the temperature at which the elongation of the molded product suddenly changes when the temperature is increased at 5 ° C./min. . (3) Optical Unevenness A molded product having a diameter of 50 mm and a thickness of 2 mm was observed with an optical microscope (magnification: 100 times) for the presence of resin flow traces inside the molded product. Those with no resin flow trace were indicated by Δ, and those with resin flow were indicated by X.

Examples 1 to 3 and Comparative Examples 1 to 3 Each raw material was blended in accordance with the formulation shown in Table 1 and
After kneading with a hot roll at 0 ° C. for 10 to 15 minutes, the mixture was cooled and pulverized to obtain a desired powdery epoxy resin composition. Next, these resin compositions were subjected to transfer molding (molding time: 4 minutes) at a molding temperature of 150 ° C. using each test die, and further after-cured at 150 ° C. for 4 hours. Table 1 also shows the characteristic results of the obtained molded products.

[0011]

[Table 1] * 1: Bisphenol A type epoxy resin manufactured by Yuka Shell Co., Ltd. * 2: Bisphenol A type epoxy resin manufactured by Mitsui Petrochemical Co., Ltd. * 3: Alicyclic epoxy resin manufactured by Ciba Geigy Co., Ltd. * 4: Nissan Heterocyclic epoxy resin manufactured by Chemical Co., Ltd. * 5: Acid anhydride TH, manufactured by Shin Nippon Rika Co., Ltd.
(Trade name) * 6: Imidazole 2E4MZ (trade name) manufactured by Shikoku Chemicals Co., Ltd.

[0012]

As is evident from the results shown in Table 1, according to the present invention, an epoxy resin composition for encapsulating an optical semiconductor which is excellent in transparency and heat resistance and gives a cured product without optical unevenness is obtained. It is particularly suitable as a sealing material for light-receiving elements such as solid-state image elements.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 23/28-23/30 H01L 21/56 C08G 59/24 H01L 33/00

Claims (2)

(57) [Claims] 1. An epoxy resin composition for encapsulating an optical semiconductor comprising an epoxy resin, a curing agent, and a curing accelerator, wherein the epoxy resin is mainly a bisphenol A type epoxy resin represented by the following general formula. An epoxy resin composition for encapsulating an optical semiconductor, comprising: Embedded image (However, in the above general formula, n = 1 to 5.) 2. An epoxy resin comprising a mixture of the above-mentioned bisphenol A type epoxy resin and an alicyclic epoxy resin and / or a heterocyclic epoxy resin, and the mixing ratio (weight ratio) thereof is 90:10 to 50:50. The epoxy resin composition for optical semiconductor encapsulation according to claim 1, wherein