JPH07268073A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition improved in storage stability at ordinary temperatures without detriment to electrical properties by mixing a specified epoxy resin with a specified phenolic compound curing agent and a specified trisubstituted phosphine-trisubstituted borane compound and an inorganic filler. CONSTITUTION:An epoxy resin having at least two epoxy groups is mixed with a curing agent comprising a phenolic compound having at least two hydroxyl groups and used in such an amount that the ratio of the epoxy equivalent of the epoxy resin to the hydroxyl equivalent of the phenolic compound is nearly 1; 1, 0.1-1.5wt.% trisubstituted phosphine-trisubstituted borane compound represented by the formula [wherein R1 to R8 are a 1-8C alkyl or a(substituted) phenyl] and 60-90wt.% inorganic filler.

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 semiconductor encapsulation which is excellent in storage stability at room temperature.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical characteristics, adhesiveness and the like, and are used in a wide variety of fields such as electrical insulating materials, paints and adhesives. Thermosetting resins are also used for electronic parts such as diodes, transistors, and integrated circuits. Especially in integrated circuits such as ICs and LSIs, orthocresol novolac epoxy resin, which has excellent heat resistance and moisture resistance, is used as a curing agent for novolac phenols. An epoxy resin composition in which a resin is blended and a large amount of an inorganic filler is further added thereto is generally used. A method of molding a semiconductor device with a transfer molding machine using the epoxy resin composition is a mainstream technique for resin-sealing a semiconductor device because of its excellent productivity.

In this epoxy resin composition, amines, nitrogen-containing heterocyclic compounds such as imidazole compounds and diazabicycloundecene, organophosphine compounds and quaternary compounds are used as curing accelerators to accelerate curing during molding. Ammonium or phosphonium compounds are used. Since commonly used curing accelerators have an accelerating effect even at relatively low temperatures, for example, curing of the resin can be promoted by heating or heat generation when the resin and other components are mixed, and during storage at room temperature after mixing. However, since the curing reaction progresses, variations in curability due to an increase in melt viscosity and a decrease in fluidity are likely to occur, which causes obstacles in molding and deterioration of mechanical and electrical characteristics of a molded product. Therefore, when using such a curing accelerator, strict quality control is required when mixing with other components, and the temperature is kept low during storage and transportation, and the complexity of strict control of molding conditions is required. I couldn't avoid it.

Therefore, in recent years, a latent curing accelerator has been developed, which does not accelerate the curing reaction of the resin at a relatively low temperature but significantly accelerates the curing reaction when heated in a mold during molding. However, even in this case, the potential is low and the above-mentioned problems occur. Conversely, the potential is too high, so that it takes a long time to cure under normal molding conditions or the curing temperature must be increased. Therefore, there is an urgent need to develop a curing accelerator that satisfies the requirements.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in view of such a situation, and its object is excellent in storage stability at room temperature without deteriorating electrical characteristics and the like. Another object is to provide an epoxy resin composition for semiconductor encapsulation.

[0006]

The present invention provides (A) an epoxy resin having at least two epoxy groups,
(B) a phenol compound curing agent having at least two hydroxyl groups, (C) a tri-substituted phosphine / tri-substituted borane compound represented by the formula (1),

[0007]

[Chemical 2] (R _{1 to} R ₆ in the formula are the same or different groups selected from an alkyl group having 1 to 8 carbon atoms, a phenyl group or a substituted phenyl group)

(D) An epoxy resin composition for semiconductor encapsulation containing an inorganic filler as an essential component.

The present invention will be described in detail below. The tri-substituted phosphine / tri-substituted borane compound used in the present invention is a curing accelerator. In the formula, R _{1 to} R ₆ are each a carbon number of 1 to
8 are the same or different groups selected from an alkyl group, a phenyl group and a substituted phenyl group. Specifically, triphenylphosphine / triphenylborane, triphenylphosphine / ethyldiphenylborane, triphenylphosphine / triethylborane, triphenylphosphine / tributylborane, tributylphosphine / tributylborane, tributylphosphine / triethylborane, tributylphosphine / tributylphosphine / tributylborane Examples thereof include triphenylborane, tritolylphosphine and triphenylborane, and these may be used alone or in combination. Among these, triphenylphosphine / triphenylborane and triphenylphosphine / tributylborane are preferable. Since these curing accelerators exert an extremely large curing acceleration effect at high temperatures, the content of the curing accelerator is 0.1 to 1.5% by weight based on the total resin composition. If it is less than 0.1% by weight, there is a problem that the releasability is poor due to insufficient curing, and if it exceeds 1.5% by weight, there is a problem that storage stability is deteriorated.

Next, the epoxy resin used in the present invention is not particularly limited as long as it is an epoxy resin having at least two epoxy groups. For example, phenols such as phenol novolac, cresol novolac, bisphenol A and bisphenol F. Glycidyl ethers, glycidyl ethers of alcohols such as polyethylene glycol and polypropylene glycol, glycidyl esters of carboxylic acids such as isophthalic acid, phthalic acid and tetrahydrophthalic acid, aniline and isocyanuric acid. Among the glycidyl type epoxy resins such as those substituted with a group, and the alicyclic epoxies obtained by epoxidizing the olefinic bond in the molecule with peracid or the like, the solid epoxy resin at room temperature is used. Among these solid epoxy resins, glycidyl ethers such as cresol novolac and phenol novolac are particularly preferable. Further, these solid epoxy resins may be used in combination with a liquid epoxy resin.

The phenol compound curing agent used in the present invention is not particularly limited as long as it is a phenol compound having at least two hydroxyl groups. For example, a bifunctional phenol compound such as bisphenol A or bisphenol F, phenol, cresol, Examples thereof include novolaks obtained by condensing phenols such as xylenol and aldehydes such as formaldehyde with an acidic catalyst, and alkenylphenol polymers. The above-mentioned epoxy resin and phenol compound are preferably blended so that the ratio of the epoxy equivalent of the epoxy resin to the hydroxyl equivalent of the phenol compound is approximately 1: 1.

As the inorganic filler used in the present invention, fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, secondary agglomerated silica powder or silica obtained by crushing porous silica powder is used. Silica powder such as powder, alumina and the like are generally used, and in addition, there are calcium carbonate, calcium silicate, talc, clay, mica, glass fiber powder and the like. These inorganic fillers may be used alone or as a mixture, and the compounding amount is preferably in the range of 60 to 90% by weight based on the whole composition. If it is less than 60% by weight, the performance such as solder cracking and moisture resistance is deteriorated, and if it exceeds 90% by weight, the fluidity is deteriorated.
Problems such as poor filling properties occur.

The epoxy resin composition of the present invention may optionally contain various halogenated compounds such as brominated epoxy resin as a flame retardant, antimony trioxide, an inorganic hydrate, and carnauba wax and montanic acid as a release agent. As the coupling agent, various silane compounds, titanium compounds, aluminum chelate compounds, etc. are used such as wax and polyalkylene wax. Further, as a colorant, carbon black, red iron oxide, titanium oxide, red lead, ultramarine blue, various oil dyes and the like can be used. Further, in order to produce the encapsulating epoxy resin composition of the present invention as a molding material,
Epoxy resin, phenolic resin curing agent, inorganic filler, and other additives are sufficiently and uniformly mixed by a mixer or the like, and then melt-kneaded with a hot roll or a kneader, and after cooling, crushed to obtain a molding material. it can. These molding materials can be applied to sealing, coating, insulating, etc. of electronic parts or electric parts.

The present invention will be specifically described below with reference to examples. Example 1 O-cresol novolac type epoxy resin (epoxy equivalent: 200 g / eq, softening point: 70 ° C.) 100 parts by weight Phenol novolac resin curing agent (hydroxyl group equivalent: 106 g / eq, softening point: 85 ° C.) 57 parts by weight Triphenylphosphine / triphenylborane 1.5 parts by weight Brominated bisphenol A type epoxy resin (epoxy equivalent: 400 g / eq, softening point: 85 ° C.) 16 parts by weight Antimony trioxide 3.5 parts by weight Fused silica powder 465 parts by weight Coupling agent (epoxysilane) 2 parts by weight Carnauba wax 1 part by weight Carbon black 1 part by weight was mixed with a mixer at room temperature, kneaded with a biaxial roll at 70 to 100 ° C., cooled and pulverized to obtain a molding material. The obtained molding material was tabletted, 16 pDIP was molded at 175 ° C. and 70 kg / cm ² with a low-pressure transfer molding machine, and Bacol hardness was measured 10 seconds after the mold was opened. The obtained molded product was subjected to burr (vent), releasability, and appearance check.

Spiral flow residual rate: The spiral flow immediately after forming a molding material is measured using a mold according to EMMI-I-66 under the conditions of 175 ° C., 70 kg / cm ² , 120 seconds, and the measured value A The same molding material obtained was stored at 25 ° C. for 2 weeks, and the spiral flow was measured in the same manner. The spiral flow residual rate is calculated by the following formula. Spiral flow residual rate (%) = [(measured value B) / (measured value A)] × 100 Gel time: Measured on a hot plate at 175 ° C. The evaluation results are shown in Table 1. Examples 2 and 3 Compounding was performed according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. An evaluation test was conducted on this molding material in the same manner as in Example 1. The evaluation results are shown in Table 1. Comparative Examples 1 to 3 Compounding was performed according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. An evaluation test was conducted on this molding material in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0016]

[Table 1]

[0017]

The epoxy resin composition of the present invention can be stored at room temperature, which could not be obtained by the prior art.
The management during storage and transportation can be simplified.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 23/29 23/31

Claims (3)

[Claims] 1. An epoxy resin having (A) at least two epoxy groups, (B) a phenol compound curing agent having at least two hydroxyl groups, and (C) a formula (1).
A tri-substituted phosphine / tri-substituted borane compound represented by: (Wherein R _{1 to} R ₆ are the same or different groups selected from an alkyl group having 1 to 8 carbon atoms, a phenyl group or a substituted phenyl group) (D) An inorganic filler is an essential component The epoxy resin composition for semiconductor encapsulation. 2. A tri-substituted phosphine.
The epoxy resin composition according to claim 1, which contains 0.1 to 1.5% by weight of a tri-substituted borane compound. 3. R _{1 to} R ₆ of the formula (1) are phenyl groups or substituted phenyl groups, or R _{1 to} R ₃ are phenyl groups or substituted phenyl groups, and R _{4 to} R ₆ are butyl groups. The epoxy resin composition for semiconductor encapsulation according to claim 1 or claim 2.