JP2001247650A - Epoxy resin composition for encapsulation of optical semiconductor, and optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for encapsulating an optical semiconductor which composition is excellent in the transparency and the soldering resistance and to provide an optical semiconductor device encapsulated with a cured substance thereof. SOLUTION: The epoxy resin composition for encapsulating an optical semiconductor, is characterized by consisting essentially of an epoxy resin which has two or more epoxy groups in one molecule and comprises a product obtained by reacting (A) a compound having two or more phenolic groups in one molecule and not having any methylene hydrogen belonging to the aralkyl group substituted on a carbon of the phenolic nucleus, with an epihalohydrin; and a curing agent of a compound having two or more phenolic hydroxy groups in one molecule and not having any methylene hydrogen belonging to the aralkyl group substituted on a carbon of the phenolic nucleus.

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 optical semiconductor encapsulation 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 recent years, in order to reduce the size of communication information equipment, improve the integration density, and simplify the manufacturing process, the semiconductor industry has rapidly increased the demand for a surface mounting method instead of the conventional mounting method. Further focusing on the field of optoelectronics, transparency is a very important factor in addition to the function of the conventional semiconductor sealing resin. That is, in an opto-device such as a photosensor, an LED, and a light-emitting element, even if a mounting method such as IR reflow in surface mounting is performed, transparency is not impaired, and furthermore, package cracking due to thermal shock, There is a demand for a highly reliable sealing resin which does not cause separation between the resin and the chip or the lead frame.

[0003] Many resins have been shown so far for optical semiconductor encapsulation. For example, Japanese Patent No. 2970214
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses that heat resistance and transparency can be obtained by using an epoxy resin having a specific structure, but an acid anhydride is used as a curing agent to be combined. Certainly, when an acid anhydride is used as the curing agent, high transparency is obtained, and high transmittance is also obtained in the visible light region. However, the acid anhydride curing agent type epoxy resin composition has a high hydrophilicity of the acid anhydride group, so that the water absorption of the resin composition is high, and the surface mount type optical semiconductor package is mounted by IR reflow or the like. Then, there is a problem that package cracks due to thermal shock and peeling frequently occur between the chip or the lead frame and the resin.

On the other hand, there is a phenol novolak resin which is known as a curing agent for an epoxy resin composition. The epoxy resin composition using this phenol novolak curing agent has a methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus, although the water absorption can be reduced,
In other words, there is a disadvantage that benzyl hydrogen is present, and this hydrogen is easily oxidized by active radical species generated in the system, and is significantly colored by heat.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide 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. I do.

[0006]

SUMMARY OF THE INVENTION The present invention is characterized in that an epoxy resin having a specific structure, which has a reduced water absorption, improves heat resistance, and is excellent in transparency, and a curing agent are essential components. By using the resin composition, the above-mentioned target has been achieved.

That is, the present invention provides an epoxy resin (A) having two or more epoxy groups in one molecule, and an epoxy resin (A) having two or more phenolic hydroxyl groups in one molecule, and (C) comprising a compound (B) having no methylene hydrogen belonging to an aralkyl group substituted by
Wherein the epoxy resin (A) has two or more phenolic hydroxyl groups in one molecule, and has methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus. An epoxy resin composition for encapsulating an optical semiconductor, which is a product obtained by the reaction of a compound (D) having no epitaxy with epihalohydrin, and an optical semiconductor device encapsulated with a cured product thereof.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin (A) having two or more epoxy groups in one molecule used in the present invention has two or more phenolic hydroxyl groups in one molecule and has a phenol nucleus. Is a product obtained by reacting a compound (D) having no methylene hydrogen belonging to an aralkyl group substituted on the carbon with epihalohydrin, and a specific example thereof is the methylene oxidizable by an active radical species. There is no restriction if it does not have hydrogen.

A compound (D) 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 for producing the epoxy resin (A). Examples of the above) include dihydroxybenzenes such as resorcinol and catechol, bisphenol A, bisphenol S, biphenol, biphenol ether and their alkyl-substituted products, bisphenolfluorene, dihydroxynaphthalene, 4,4′-cyclohexylidenebisphenol,
4,4 ′-(1-phenylethylidene) bisphenol, 4,4′-oxybisphenol, 2- (4-hydroxyphenyl) -2- [4- [1,1-bis (4-hydroxyphenyl) ethyl] phenyl ] Propane, 1,
Examples thereof include 1,1-tris (4-hydroxyphenyl) ethane.

The epoxy resin used in the present invention is obtained by reacting these compounds with an epihalohydrin such as epichlorohydrin by a method well known to those skilled in the art, and comprises two or more epoxy groups in one molecule. Any alkyl-substituted or unsubstituted bisphenol A, alkyl-substituted or unsubstituted bisphenol S, alkyl-substituted or unsubstituted biphenol, bisphenolfluorene, 4,4′-cyclohexylidenebisphenol, 4,4′- (1-phenylethylidene) bisphenol, 4,4′-oxybisphenol, 2- (4-hydroxyphenyl) -2- [4- [1,1-bis (4-
(Hydroxyphenyl) ethyl] phenyl] propane or a product obtained by reacting 1,1,1-tris (4-hydroxyphenyl) ethane with epihalohydrin, and an epoxy resin having two or more epoxy groups in one molecule Are preferred in terms of water absorption, light transmission and heat resistance.

Further, among them, epoxy resins selected from the group of alkyl-substituted or unsubstituted bisphenol A type epoxy resins, alkyl-substituted or unsubstituted bisphenol S-type epoxy resins, and alkyl-substituted or unsubstituted biphenol-type epoxy resins have excellent handling properties. Alkyl-substituted or unsubstituted bisphenol A type epoxy resin, alkyl-substituted or unsubstituted bisphenol S
It is more preferable to use a type epoxy resin or an alkyl-substituted or unsubstituted biphenol type epoxy resin having at least one or more alcoholic hydroxyl groups in one molecule in terms of improving transparency.

In the present invention, the epoxy resin used includes:
The reason why the transparency is improved when the alcoholic hydroxyl group is present in the molecule is unknown in detail, but the present inventors have found that when exposed to a high temperature such as curing and molding, active radicals are present in the resin composition. Although it is thought that seeds are generated and cause coloring, it was presumed that the alcoholic hydroxyl group captures the active radical species, suppresses coloring properties, and improves transparency.

When the epoxy resin has at least one epoxy group generated by a reaction between an alcoholic hydroxyl group and epihalohydrin, the obtained epoxy resin has three or more epoxy groups in one molecule, It is more preferable because it becomes polyfunctional, has a high glass transition temperature, and improves heat resistance. Further, an alkyl-substituted or unsubstituted bisphenol A-type epoxy resin is more preferable in that it is inexpensive and economical. When one molecule has at least one or more alcoholic hydroxyl groups and one molecule has at least one or more alcoholic hydroxyl groups and an epoxy group generated by the reaction of epihalohydrin, transparency and heat resistance are high. It is more preferable that compatibility can be obtained at a high level.

So far, the epoxy resin has been described. To improve the transparency, not only the epoxy resin but also a curing agent containing a compound having no methylene hydrogen belonging to the aralkyl group substituted on the carbon of the phenol nucleus. (B)
It is necessary to use

That is, the curing agent (C) used in the epoxy resin composition for encapsulating an optical semiconductor of the present invention has two or more phenolic hydroxyl groups in one molecule, and is substituted on the carbon of the phenol nucleus. (B) having no methylene hydrogen belonging to the aralkyl group described above.

As the curing agent (C), a compound (B) 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 is There is no limitation as long as the methylene hydrogen is not easily oxidized by the active radical species.

Compound (B) 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 as a curing agent used in the present invention. As a specific example,
Resorcinol, dihydroxybenzenes such as catechol, bisphenol A, bisphenol S, biphenol, biphenol ether and alkyl substituted products thereof, bisphenolfluorene, dihydroxynaphthalene, 4,4′-cyclohexylidenebisphenol,
4,4 ′-(1-phenylethylidene) bisphenol, 4,4′-oxybisphenol, 2- (4-hydroxyphenyl) -2- [4- [1,1-bis (4-hydroxyphenyl) ethyl] phenyl ] Propane, 1,
Examples thereof include 1,1-tris (4-hydroxyphenyl) ethane.

Further, it is more preferable to have three or more phenolic hydroxyl groups in one molecule from the viewpoint of quick-curing property, and in the case of having three or more phenolic hydroxyl groups in one molecule, the epoxy resin has two or more phenolic hydroxyl groups. Even if it is a functional epoxy resin, the epoxy resin composition is more preferable in terms of being capable of being cured and molded. Further, 2- (4-hydroxyphenyl) having three or more phenolic hydroxyl groups in one molecule
-2- [4- [1,1-bis (4-hydroxyphenyl) ethyl] phenyl] propane and 1,1,1-tris (4-hydroxyphenyl) ethane have good handling properties and are compatible with epoxy resins. Is more preferred in terms of goodness.

The epoxy resin composition for encapsulating an optical semiconductor of the present invention may contain, if necessary, a curing accelerator, an antioxidant, a coupling agent, a release agent, and other epoxy resins within a range that does not affect the properties. The combination of additives, auxiliary materials, and fillers known to those skilled in the art, such as agents and the like, 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, for example, the equivalent ratio of the epoxy resin to the curing agent, that is, the molar ratio of the epoxy group of the epoxy resin to the phenolic hydroxyl group of the phenol curing agent is preferably 0.8 to 1.4, more preferably. When the total weight of the epoxy resin and the curing agent is 100, the addition amount of the curing accelerator is preferably 0.5 to 2 parts by weight. After uniformly mixing each component, melt-mix with a kneader,
The obtained molten mixture is obtained by cooling and pulverizing.

The optical semiconductor encapsulating epoxy resin composition thus obtained can be encapsulated 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.

[0022]

EXAMPLES The present invention will be described in detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

[Synthesis of Epoxy Resin (A)] (Synthesis Example 1) 1300 g (1 mol) of a bisphenol A type epoxy resin having an alcoholic hydroxyl equivalent of 394 and an epoxy equivalent of 650 was dissolved in 1 L of methyl isobutyl ketone in a 6 L flask. 834 g of epichlorohydrin
(9 mol), heated to 50 ° C. in an oil bath and stirred. Under stirring, 66 g of 40% by weight caustic soda (0.
(66 mol) is added to the flask over 2 hours. After setting the temperature of the oil bath at 50 to 55 ° C. and reacting for 2 hours while flowing nitrogen, the flask is immersed in an ice bath, and 1 L of the flask is stirred.
Of pure water over 1 hour, and the mixture is further stirred for 1 hour. Thereafter, the stirring is stopped, and after standing for 1 hour, the aqueous layer separated into two phases is removed by decantation. The organic layer is repeatedly purified and washed three times with boiling water, and then reduced to 100 ° C. under reduced pressure.
To remove methyl isobutyl ketone and excess epichlorohydrin to obtain a product (compound a1). The product obtained has an epoxy equivalent of 325.

(Synthesis Example 2) 1,1,1
306 g of tris (4-hydroxyphenyl) ethane
(1 mol) and 834 g (9 mol) of epichlorohydrin, and the mixture was heated and stirred at 120 ° C. for 1 hour. Then, the mixture is heated and refluxed at 120 ° C., and 600 g (6 mol) of 40% by weight of caustic soda is added dropwise over 2 hours. After the addition, the mixture is stirred for 1 hour. Thereafter, water and excess epichlorohydrin are removed by distillation to obtain a crude product. To remove salts, the crude product is added with 100 g of toluene, dissolved, filtered to remove salts, and then washed three times with 200 ml of pure water. After washing, water is removed, and the remaining toluene is removed by distillation to obtain a product (compound a2). The product obtained has an epoxy equivalent of 160.

(Examples 1 to 5, Comparative Examples 1 to 5) The resin compositions of the present invention were mixed by heating at the mixing ratios shown in Tables 1 and 2, cooled, and ground to obtain a resin composition. Was. Using a low-pressure transfer molding machine, a test piece used in each test was prepared by using a low-pressure transfer molding machine under the conditions of a mold temperature of 175 ° C., an injection pressure of 6.86 × 10 ⁶ Pa, a curing time of 2 minutes, and a post cure of 150 ° C. for 2 hours. Produced. The evaluation method is as follows. The results are summarized in Tables 1 and 2.

(Measurement of Light Transmittance) A test piece having a size 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 UV-3100).
The light transmittance at 00 nm was measured.

(Measurement of moisture absorption) Diameter 50 mm, thickness 3 m
A disc-shaped test piece of 85 m and 85% humidity
, And the rate of weight increase after 168 hours was measured as a moisture absorption rate.

(Measurement of glass transition temperature) 10 × 5 × 5 m
m test piece, 5 ° C / mi using TMA
The temperature was measured at a temperature rising rate of n, and the temperature was set to a temperature at which the elongation of the test piece rapidly changed.

(Evaluation of Solder Resistance) A surface mounting package (12 pins, 4 × 5 mm, thickness 1.2 mm, chip size 1.5 mm × 2.0 mm, lead frame made of 42 alloy) was subjected to mold temperature. 175 ° C, injection pressure 6.86x1
Transfer molding at 0 ⁶ Pa, curing time 2 minutes, 15
It was post-cured at 0 ° C. for 2 hours. The obtained optical semiconductor package was left in an environment of 85 ° C. and a relative humidity of 60% for 168 hours, 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.

[0030]

[Table 1]

[0031]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the resin composition of the present invention has transparency, heat resistance and low water absorption, and has good solder resistance. .

[0033]

The epoxy resin composition for encapsulating an optical semiconductor of the present invention is excellent in transparency and solder resistance, and can provide an optical device having high reliability.

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Claims (9)

[Claims] 1. An epoxy resin (A) having two or more epoxy groups in one molecule, and an aralkyl having two or more phenolic hydroxyl groups in one molecule and substituted on the carbon of the phenol nucleus. In an epoxy resin composition comprising a curing agent (C) comprising a compound (B) having no methylene hydrogen belonging to the group as an essential component, the epoxy resin (A) is
A product obtained by reacting a compound (D) having two or more phenolic hydroxyl groups in the molecule and having no methylene hydrogen belonging to an aralkyl group substituted on the carbon of the phenol nucleus with epihalohydrin An epoxy resin composition for encapsulating an optical semiconductor, comprising: 2. A compound (D) having two or more phenolic hydroxyl groups in one molecule for forming an epoxy resin and having no methylene hydrogen belonging to an aralkyl group substituted on carbon of the phenol nucleus. , Alkyl-substituted or unsubstituted bisphenol A, alkyl-substituted or unsubstituted bisphenol S, alkyl-substituted or unsubstituted biphenol, bisphenolfluorene, 4,4'-cyclohexylidenebisphenol, 4,4 '-(1-phenylethylidene)
Bisphenol, 4,4'-oxybisphenol, 2
-(4-hydroxyphenyl) -2- [4- [1,1-
The epoxy resin composition for optical semiconductor encapsulation according to claim 1, which is selected from the group consisting of bis (4-hydroxyphenyl) ethyl] phenyl] propane and 1,1,1-tris (4-hydroxyphenyl) ethane. 3. The epoxy resin (A) is selected from the group consisting of an alkyl-substituted or unsubstituted bisphenol A epoxy resin, an alkyl-substituted or unsubstituted bisphenol S-type epoxy resin, and an alkyl-substituted or unsubstituted biphenol-type epoxy resin. The epoxy resin composition for optical semiconductor encapsulation according to claim 1, which is an epoxy resin and has at least one or more alcoholic hydroxyl groups in one molecule. 4. The epoxy resin composition for optical semiconductor encapsulation according to claim 3, wherein the epoxy resin (A) has at least one epoxy group generated by a reaction between an alcoholic hydroxyl group and epihalohydrin. . 5. The epoxy resin (A) having at least one or more alcoholic hydroxyl groups and at least one or more alcoholic hydroxyl groups and an epoxy group formed by a reaction of epihalohydrin with epihalohydrin. 3
The epoxy resin composition for optical semiconductor encapsulation according to the above. 6. The epoxy resin (A) is an alkyl-substituted or unsubstituted bisphenol A-type epoxy resin,
4. The light according to claim 3, wherein the molecule has at least one or more alcoholic hydroxyl group and one molecule has at least one or more epoxy group formed by a reaction between the alcoholic hydroxyl group and epihalohydrin. Epoxy resin composition for semiconductor encapsulation. 7. The method according to claim 1, wherein the curing agent (C) has three or more phenolic hydroxyl groups in one molecule.
The epoxy resin composition for optical semiconductor encapsulation according to the above. 8. The method according to claim 1, wherein the curing agent (C) is 2- (4-hydroxyphenyl) -2- [4- [1,1-bis (4-hydroxyphenyl) ethyl] phenyl] propane and 1,
The epoxy resin composition for optical semiconductor encapsulation according to claim 7, which is selected from the group consisting of 1,1-tris (4-hydroxyphenyl) ethane. 9. An optical semiconductor device encapsulated with a cured product of the epoxy resin composition for optical semiconductor encapsulation according to claim 1. Description: