JPH0723424B2 - Flame-retardant epoxy resin composition for semiconductor encapsulation - Google Patents

Description

The present invention relates to a flame-retardant epoxy resin composition for semiconductor encapsulation, which has excellent heat resistance and mechanical properties.

<Prior art> Epoxy resin has excellent heat resistance, moisture resistance, electrical properties, adhesiveness, etc., and since various properties can be imparted by blending formulation, it is used as an industrial material such as paints, adhesives, and electrical insulation materials. Has been done.

For example, as a sealing method for electronic circuit parts such as semiconductor devices, hermetic seals made of metal or ceramics and resin seals made of phenolic resin or epoxy resin have been proposed so far. From the point of view, resin sealing with epoxy resin is the main focus.

These industrial materials are strongly required to have flame retardancy as well as general chemical and physical properties.

As a method for making an epoxy resin flame retardant, (i) a method using a halogenated epoxy resin, (ii) a method using a halogen-containing curing agent, (iii) a method using an addition type flame retardant such as a phosphorus compound or a halogen compound is known. CMC Technical Report No.35 Highly functional epoxy resin and application development P.187, (1983)
Disco Corporation}.

(I) and (ii) are methods of incorporating a halogen atom directly into the network structure of the epoxy resin by using a reactive flame retardant. According to this method, it is possible to make the epoxy resin flame-retardant without deteriorating the physical properties of the epoxy resin by using a flame-retardant agent having an appropriate structure. It is becoming mainstream.

The method (iii) is characterized in that flame retardation can be easily achieved and that the combination of flame retardants can be relatively easily performed.

<Problems to be Solved by the Invention> Although the conventional flame-retardant techniques for epoxy resins have the above-mentioned characteristics, they have insufficient heat resistance and mechanical properties.

For example, when exposed to a high temperature atmosphere in an automobile engine room for a long time, there is a problem that the flame retardant is thermally decomposed to generate gas, and the molded product swells and cracks. Further, it has been pointed out that it is necessary to improve the breaking strength and the elongation as well as to reduce the stress, because the molded product cracks when repeated rapid temperature changes.

The present invention has been made to solve the above problems and to provide a flame-retardant epoxy resin composition for encapsulating a semiconductor, which has excellent heat resistance and mechanical properties.

<Means for Solving Problems> As a result, the above object of the present invention is difficult to form the epoxy resin (A) by blending the curing agent (B), the halogenated phenol polycondensate (C) and the filler. It has been found that this can be achieved by using a fired epoxy resin composition for semiconductor encapsulation.

Hereinafter, the configuration of the present invention will be described in detail.

The epoxy resin (A) in the present invention is not particularly limited as long as it has two or more epoxy groups in one molecule.

Examples thereof include cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin and halogenated epoxy resin.

Depending on the application, two or more epoxy resins may be used in combination, but for semiconductor device encapsulation, the epoxy equivalent of cresol novolac type epoxy resin is 500 or less, especially 300 or less from the viewpoint of heat resistance and moisture resistance. It is preferable to contain the resin in an amount of 50% by weight or more based on the whole epoxy resin. Also Na,
Cl and other impurities are preferably removed as much as possible.

The curing agent (B) in the present invention is not particularly limited as long as it reacts with the epoxy resin (A) and is cured.

For example, novolac resins such as phenol novolac and cresol novolac, tetrabromobisphenol A
And acid anhydrides such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride, and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Phenol novolac and cresol novolac are preferably used for sealing a semiconductor device from the viewpoint of heat resistance and storability. Two or more curing agents may be used in combination depending on the application.

In the present invention, the compounding ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0.5 to 1.5, particularly 0.8 to 1.2 from the viewpoint of mechanical properties and moisture resistance. Is preferred. In the present invention, a curing catalyst may be used to accelerate the curing reaction between the epoxy resin (A) and the curing agent (B). The curing catalyst is not particularly limited as long as it accelerates the curing reaction. For example, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-
4-methylimidazole, 2-phenylimidazole,
Imidazoles such as 2-phenyl-4-methylimidazole and 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethyl) Aminomethyl) phenol, tertiary amines such as 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) )
Examples thereof include organic metals such as aluminum, triphenylphosphine, triethylphosphine, tributylphosphine, trimethylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine, and the like. Depending on the application, two or more curing catalysts may be used together. The addition amount of the curing catalyst is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin (A).

Examples of the halogenated phenol polycondensate (C) used as the flame retardant in the present invention include the following general formula (I).
The one obtained by polycondensing one or more of the halogenated phenols shown in 1) in the presence of a caustic alkali and a metal catalyst (eg, iron catalyst, copper catalyst, etc.) in a solvent or without solvent.

(In the formula (I), R represents a lower alkyl group or hydrogen, X represents bromine or chlorine, m represents an integer of 0 to 4,
n represents an integer of 1 to 5, respectively. ) Preferred specific examples of the halogenated phenol of the above formula (I) include monobromophenol, dibromophenol,
Tribromphenol, tetrabromophenol, pentabromophenol, dibromocresol, monochlorophenol, dichlorophenol, trichlorophenol, tetrachlorophenol, pentachlorophenol, etc. and mixtures thereof, with tribromophenol being most preferred.

The aggregation degree of the halogenated phenol polycondensate (C) is 3 to 10
The range of 0 is preferable, and the range of 5 to 50 is particularly preferable. The halogen content in the halogenated phenol polycondensate (C) is preferably 30% by weight or more, and particularly preferably 50% by weight or more.
If it is less than 30%, it becomes necessary to add a large amount of the halogenated phenol polycondensate (C) in order to make it flame-retardant, resulting in insufficient moldability.

The halogenated phenol polycondensate (C) may be one having a terminal hydroxyl group, or one having a terminal functional group blocked with a bifunctional or higher functional metal compound capable of reacting with the terminal hydroxyl group or a monofunctional or higher functional organic compound.

Examples of such metal compounds include aluminum, magnesium, calcium, strontium, barium,
Examples thereof include halides such as antimony and tin, and specific examples include aluminum bromide, magnesium chloride, calcium chloride, strontium chloride, barium chloride, antimony chloride, stannous chloride and the like.

Examples of the organic compound include an alkyl dihalide, an acyl halide, an acyl dihalide, a haloacyl halide, a haloacyl dihalide, a dihalodate phosphate, an organic compound having a cyanuric halide or other active haloene, and a polyepoxy compound. , More specifically dibromethylene, dichloroethylene, dichlorodiethyl ether, maleic acid dichloride, benzoic acid chloride, toluic acid chloride, terephthalic acid dichloride, tetrabromophthalic acid dichloride, phenylphosphoric acid dichloride, phenylphosphonic acid dichloride. , Digromcresyl phosphoric acid dichloride, chlorophenylphosphonic acid dichloride, cyanuric chloride and the following general formulas (II) to (VIII)
And the like.

BrCH ₂ CH ₂ O-Ar-OlCH ₂ CH ₂ Br ...... (II) ClCH ₂ CH ₂ OCH ₂ CH ₂ O-Ar-OlCl ...... (III) (In the formulas (II) to (VIII), l is an integer of 1 to 50,
R ^{1 to} R ⁵ each represent hydrogen, chlorine or bromine. Ar is a compound represented by the following general formulas (IX) and (X). ) (In the formulas (IX) and (X), R ^{1 to} R ⁴ each represent hydrogen, chlorine or bromine. Y is a lower alkylene group, alkylidene group, —SO ₂ —, —SO—, —S—, -O-, -CO
-Or indicates a chemical bond. Among these, benzoic acid chloride, terephthalic acid dichloride, isophthalic acid dichloride and the compound of the formula (VI) can be preferably used.

The reaction when the terminal hydroxyl group of the polycondensation product of halogenated phenol is blocked with the above-mentioned metal compound or organic compound is carried out by adding one or more of the above compounds to the polycondensation product of halogenated phenol. There may be mentioned below a method of reacting in a solvent or without solvent, or (b) a reaction using a Lewis acid (eg BF ₃ etc.) in a non-polar solvent.

The amount of the halogenated phenol polycondensate (C) added is 3 to 60 parts by weight, and particularly 7 to 100 parts by weight of the epoxy resin (A).
-40 parts by weight is preferred. If it is less than 3 parts by weight, the flame retardancy is insufficient, and if it exceeds 60 parts by weight, the moldability is significantly deteriorated, which is not preferable.

Two or more of these halogenated phenol polycondensates (C) may be used in combination.

The flame retardant effect of the halogenated phenol polycondensate (C) is significantly enhanced by the combined addition of antimony trioxide. The addition amount thereof is preferably 1 to 30 parts by weight, more preferably 2 to 30 parts by weight, based on the epoxy resin (A). If it is less than 1 part by weight, the flame retardancy-improving effect by the combined addition of antimony trioxide is not sufficient, and if it exceeds 30 parts by weight, the mechanical properties are significantly deteriorated. More preferably, it is added at a ratio of 1 antimony atom in antimony trioxide to 0.2 to 5 halogen atoms in the added halogenated phenol polycondensate (C).
At the same time, other flame retardant auxiliary agents such as boron oxide, zirconium oxide and iron oxide may be used in combination.

A filler is added to the flame-retardant epoxy resin composition for semiconductor encapsulation of the present invention. As the filler, for example, fused silica, crystalline silica, quartz glass, calcium carbonate, magnesium carbonate, alumina, clay, talc, calcium silicate, titanium oxide, asbestos, glass fiber, carbon fiber, Kevlar, etc. can be blended. . In addition, carbon black, coloring agents such as iron oxide, elastomers such as silicone rubber, silicone oil, modified nitrile rubber, modified polybutadiene rubber, silane coupling agents, coupling agents such as titanate coupling agents, long chain fatty acids. A release agent such as a long-chain fatty acid metal salt, a long-chain fatty acid ester, a bisamide wax, or a paraffin wax can be optionally added.

The flame-retarded epoxy resin composition for semiconductor encapsulation of the present invention is preferably melt-kneaded, and a known method can be used for melt-kneading. For example, a Banbury mixer,
A resin composition can be prepared usually at a temperature of 50 to 150 ° C. using a kneader, roll, uniaxial or biaxial extruder, cokneader and the like.

<Examples> Hereinafter, the present invention will be specifically described with reference to Examples.

The number of parts in the examples means parts by weight.

Examples 1 to 5, Comparative Examples 1 to 3 Using the reagents shown in Table 1, dry blending the reagents with a mixer at the composition ratio of the formulation shown in Table 2,
The mixture was heated and kneaded for 5 minutes using a mixing roll having a roll surface temperature of 90 ° C., cooled and pulverized to produce an epoxy resin composition.

Using this composition, a low-pressure transfer molding method was used.
Combustion test piece (5 "x 1/2" x
1/16 ″), disk (2 ″ φ × 1/8 ″ t), bending test piece (5 ″ × 1/2 ″ × 1/4 ″) and ASTM No. 1 dumbbell, and then 5 at 175 ℃ Time post-cure. After post-cure, the physical properties of each composition were measured by the following physical property measuring methods.

Physical Property Measuring Method The physical property measuring method in Examples and Comparative Examples is as follows.

Flammability: A vertical burning test was performed according to UL94 standard using a burning test piece.

Glass transition temperature: A part of the combustion test piece was measured by DSC at a temperature rising rate of 40 ° C./min.

Water absorption rate: A pressure cooker test was performed under the conditions of 121 ° C. and 100% RH using a disk, and the water absorption rate after 1,000 hours was obtained.

Flexural modulus: Measured according to ASTM D-790 standard using a bending test piece.

Breaking strength: Measured according to ASTM D-638 standard using ASTM No. 1 dumbbell.

Heat loss: Using a combustion test piece, the weight loss rate after heat treatment at 250 ° C. for 100 hours was measured.

The results are shown in Table 2.

As seen in Examples 1 to 5, the epoxy resin composition of the present invention using a halogenated phenol polycondensate as a flame retardant is imparted with flame retardancy, has a small heating loss and is excellent in heat resistance, and It can be seen that the breaking strength is large and the mechanical properties are excellent.

As seen in Comparative Example 1, flame retardancy is not imparted unless a flame retardant is used.

As seen in Comparative Examples 2 and 3, when a brominated epoxy resin is used as a flame retardant, flame retardancy is imparted but heat loss is large, rupture strength is low, and heat resistance and mechanical properties are inferior. .

<Effects of the Invention> The present invention provides a flame-retardant epoxy resin composition for semiconductor encapsulation excellent in heat resistance and mechanical properties by blending a curing agent and a halogenated phenol polycondensate with an epoxy resin. .

Claims (1)

[Claims] 1. A flame-retardant epoxy resin composition for semiconductor encapsulation, which comprises an epoxy resin (A) mixed with a curing agent (B), a halogenated phenol polycondensate (C) and a filler.