JPS58128756A - Epoxy resin composition for photo semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain a quick hardening property as well as to control the discoloration of a hardened material by a method wherein a specified quantity of specific quarternary ammonium salt is used as a hardening accelerator. CONSTITUTION:A hardening accelerator consisting of quaternary ammonium salt as shown by the formula 1 is used together with an acid anhydride hardener for the sealing material of bisphenol type epoxy resin and/or alicyclic type epoxy resin for the photo semiconductor element. In this instance, the hardening accelerator of 5pts.wt. or less is used for acid anhydride hardener of 100pts.wt. When the hardener is used within above-mentioned range, hardening speed is accelerated the more the quantity of accelerator increases, the more the speed of hardening becomes faster and there generates no coloration on the hardened material, but if the above range of mixing ratio is exceeded, the coloration of the hardened material can not be prevented. Besides, R1-R4 consisting of alkyl radical are considered to be suitable for the above-mentioned purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin composition for encapsulating optical semiconductors.

Encapsulation materials for optical semiconductor devices are required to provide transparent cured products, and it is known that epoxy resin compositions using acid anhydride curing agents are suitable for this purpose. ing. In this type of composition, a curing accelerator such as a tertiary amine, imidazoles, or an organic metal complex salt is used together with an acid anhydride curing agent to improve the curing speed.

However, in such conventional epoxy resin compositions, when the curing temperature is increased or the amount of curing accelerator is increased to achieve rapid curing, the cured product turns yellow and becomes a encapsulating material for optical semiconductor devices. There was a problem that it could no longer be used as a standard.

As a result of intensive studies to avoid the above-mentioned problems, the inventors found that when a specific amount of a specific quaternary ammonium salt was used as a curing accelerator, it was possible to achieve rapid curing as well as discoloration of the cured product. It was discovered that it was possible to obtain a sealing material with suppressed oxidation, and this led to the completion of this invention.

That is, this invention provides a bisphenol type epoxy resin and/or an alicyclic epoxy resin together with an acid anhydride curing agent having the following general formula; monovalent organic group, X is a halogen] A curing accelerator consisting of a quaternary ammonium salt represented by: The present invention relates to a characteristic epoxy resin composition for encapsulating optical semiconductors.

As described above, the curing accelerator consisting of a quaternary ammonium salt used in this invention has aliphatic organic groups (R,
, R2, R3 and R,), which is colorless in itself and has the property of being well compatible with epoxy resins and acid anhydride curing agents. ing. The inventors have discovered that with such a curing accelerator, even when the curing temperature is raised or the amount of the accelerator is increased to achieve rapid curing, discoloration of the cured product can be effectively prevented. It has been discovered that the curing speed can also be substantially improved.

On the other hand, among quaternary ammonium salts, there are those in which at least one of R, R2, R, and R1 in the above general formula is an aromatic group, and quaternary ammonium salts other than hydrogen salts, such as hydrogen sulfate (H3O4). There are many known salts such as N-substituted pyridinium salts, N-substituted picolinium salts, N-substituted stilbazolium salts, and the like. However, such quaternary ammonium salts have problems such as poor compatibility with acid anhydride curing agents and epoxy resins, coloring themselves, or coloring of the cured product. Like conventional tertiary amines and imidazoles, it cannot be used as a suitable curing accelerator as a sealing material for semiconductor devices.

Among the quaternary ammonium halogen salts represented by the above general formula in this invention, particularly preferred ones are those in which R1+, R2, R, and electrons are all alkyl groups. The alkyl group desirably has 1 to 18 carbon atoms. Typical examples of such halogen salts include tetramethylammonium chloride, tetramethylammonium bromide, tetrabutylammonium bromide, and trioctylmethylammonium chloride.

In this invention, the above-mentioned curing accelerator is used in a proportion of 5 parts by weight or less per 100 parts by weight of the acid anhydride curing agent. This is because if the amount exceeds the above, coloring of the cured product cannot be prevented. Within the above range, the larger the amount used, the faster the curing will be, and the cured product will not be colored. Generally, the amount is preferably 0.4 to 5 parts by weight.
The amount is preferably 10 to 25 parts by weight.

The epoxy resin applied to this invention is either a bisphenol type epoxy resin or an alicyclic epoxy resin, and a mixture of both may be used. Further, it is permissible to use other epoxy resins in small amounts, but since other epoxy resins are often colored themselves, the proportions should be such that they do not impede the effects of the present invention.

As the acid anhydride curing agent used in this invention, colorless to pale yellow acid anhydrides such as hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride are used. can.

The amount of acid anhydride used is usually about 80 to 130 parts by weight per 100 parts by weight of the epoxy resin.

The epoxy resin composition for encapsulating optical semiconductors of the present invention contains, in addition to the above-mentioned epoxy resin, acid anhydride curing agent, and curing accelerator, a dye, a flexibility imparting agent, a modifier, and a deterioration inhibitor, if necessary. Conventionally known additives such as a mold release agent, a reactive or non-reactive diluent, and the like can be included.

The epoxy resin composition of the present invention obtained in this way provides a cured product with excellent transparency with almost no discoloration at a curing temperature of 150°C or less when sealing an optical semiconductor element with resin, and Even in the low temperature range of 1209C, by increasing the amount of curing accelerator added,
It hardens in a short time of about 0 minutes and can be released from the mold.
A transparent cured product with no discoloration was obtained, and this was further cured for 15 minutes.
(Even if post-curing is performed at a temperature below 7'C, it will not change color and will have excellent transparency.

Next, examples of this invention will be described. In the following,
Parts shall mean parts by weight.

Example 1 To 100 parts of EP-828C Bisphenol A type epoxy resin (manufactured by Yuka Silk Epoxy Co., Ltd.), 90 parts of 4-methylhexahydrophthalic anhydride and tetrabutylammonium bromide (in the amount shown in Table 1 below) were added. TBAB (trade name, manufactured by Koei Kagaku Co., Ltd.) was blended and mixed uniformly to obtain an epoxy resin composition for encapsulating optical semiconductors of the present invention.

Comparative Example 1 An epoxy resin composition for encapsulating an optical semiconductor was obtained in the same manner as in Example 1, except that 2-ethyl-4-methylimidazole was used in the amount shown in Table 1 below.

Comparative Example 2 Instead of tetrabutylammonium bromide, 2.
4-6-) Lisdimethylphenol
An epoxy resin composition for encapsulating optical semiconductors was obtained in the same manner as in Example 1, except that DMP-30 (trade name: DMP-30) manufactured by Japan Co., Ltd. was used in the proportions shown in Table 1 below. .

Each of the compositions of the above Examples and Comparative Examples had a diameter of 5 mm.

Cast into a case with a height of 8III and 100
Mold releasable time when cured at ~150°C (quality of curing speed and cure when cured for 1 hour at each temperature using the above method and then post-cured at 120°C for 16 hours) The results of examining the discoloration of the material were as shown in Table IJ1 below.

The discoloration property was evaluated as × if the product turned yellow and became unusable, Δ if it changed color slightly but was usable, and ○ if it did not change color at all.

Table 1 Example 2 The procedure was carried out except that EP828 (950 parts as mentioned above) and ERL-4221 (950 parts of alicyclic epoxy resin manufactured by Union Carbide) were used in combination, and the amount of curing accelerator was set at 2 parts. In the same manner as in Example 1, an epoxy resin composition for encapsulating optical semiconductors of the present invention was obtained.

Example 3 The same procedure as in Example 1 was carried out, except that 2 parts of trioctylmethylammonium chloride (trade name: TOMAC, manufactured by Koei Chemical Co., Ltd.) was used instead of tetrabutylammonium bromide. An epoxy resin composition was obtained.

Comparative Examples 3 to 6 1 piece of tetrabutylammonium bromide, N
-Cetyl-1,4-picolinium chloride (Comparative Example 3
), tetrabutylammonium hydrogen sulfate (Comparative Example 4), benzyltributylammonium bromide (Comparative Example 5), and benzyltriethylammonium chloride (Comparative Example 6) were used in the same manner as in Example 1, except that 2 parts each were used. Four types of epoxy resin compositions for encapsulating optical semiconductors were prepared.

The compositions of Example 2.3 and Comparative Examples 3 to 6 were prepared in the same manner as in Example 1, except that the curing temperature in the mold was set at 150°C and 100°C. ,
The release time and discoloration were investigated. The results were as shown in Table 2 below.

Table 2 (*s) Cured at 120"C for 16 hours. Which glass transition temperature was lower than the others.

(x) The curing accelerator was not compatible with the epoxy resin and the acid anhydride, and a uniform composition that could be used for property tests could not be obtained.

As is clear from the results in Tables 1 and 2 above,
Even when the temperature of the epoxy resin for encapsulating optical semiconductors of this invention is increased, no discoloration of the cured product is observed, indicating that the curing speed can be substantially improved.

Patent applicant: Nitto Electric Industry Co., Ltd.

Claims (1)

[Scope of Claims] is) a general formula consisting of a bisphenol-type epoxy resin and/or an alicyclic epoxy resin together with an acid anhydride curing agent; A curing accelerator consisting of a quaternary ammonium salt represented by a monovalent organic group (X is a halogen) is contained in a ratio of 5 parts by weight or less per 100 parts by weight of an acid anhydride curing agent. An epoxy resin composition for encapsulating optical semiconductors. (2) The curing accelerator comprising a quaternary ammonium salt is a curing accelerator according to claim (1), in which R, , R, , R, and R in the general formula are each an alkyl group. Epoxy resin composition for encapsulating optical semiconductors.