JPH0680763A - Epoxy resin composition for semiconductor encapsulation - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an epoxy resin composition which prevents generation of package cracks in the surface mounting process of a semiconductor device and is excellent in moisture resistance reliability and moldability. An epoxy resin composition comprising an epoxy resin, a curing agent, and a filler, wherein the epoxy resin contains an epoxy resin having a formula biphenyl skeleton as an essential component, and the curing agent has a melt viscosity of 150 ° C. 2 An epoxy resin composition for encapsulating a semiconductor, which comprises a phenol aralkyl resin having a poise or less as an essential component, and the proportion of the filler is 86 to 95% by weight of the whole. [Effect] Excellent solder heat resistance, moisture resistance reliability, and fluidity.

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 solder heat resistance, moisture resistance reliability and fluidity.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical characteristics, adhesiveness, etc., and can be given various characteristics by blending formulation, so they are used as industrial materials such as paints, adhesives and electrical insulation materials. Has been done.

For example, as a method of sealing electronic circuit parts such as semiconductor devices, hermetic seals made of metal or ceramics and phenol resin, silicone resin, etc. have hitherto been used.
Resin encapsulation with an epoxy resin or the like has been proposed. However, resin sealing with an epoxy resin is mainly used from the viewpoint of the balance of economy, productivity and physical properties.

In recent years, densification and automation have also been promoted in mounting components on a printed circuit board. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the substrate, components are soldered to the surface of the substrate. "Surface mounting method" has become popular. Along with this, the package is shifting from the conventional DIP (dual in-line package) to a thin FPP (flat plastic package) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting system, the soldering process, which has not been a problem so far, has become a big problem. In the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. As the soldering method in the surface mounting method, immersion in a solder bath, heating with saturated vapor of inert gas (vapor phase method)
Although an infrared reflow method or the like is used, the whole package is heated to a high temperature of 210 to 270 ° C. by either method. Therefore, the package sealed with the conventional sealing resin has a problem that the resin part is cracked during soldering or peeling occurs between the chip and the resin, which reduces reliability and cannot be used as a product. Occurs.

The occurrence of cracks in the soldering process is
It is said that moisture absorbed between the post-curing and the mounting process explosively vaporizes and expands during soldering heating.As a countermeasure against this, the post-cured package is completely dried and sealed. The method of storing and shipping is used.

Various improvements have been made to the sealing resin. For example, a method of blending a novolac type epoxy resin and a phenol aralkyl resin with a matrix resin (Japanese Patent Laid-Open No. Sho 5 (1999) -58138).
3-299, JP-A-59-67660), a method of blending a matrix resin with a biphenyl type epoxy resin and a phenol aralkyl resin, and a filler of 60 to 85% by weight (JP-A-3-207714 and JP-A-4). -48
No. 759 and Japanese Patent Laid-Open No. 4-55423) are proposed.

[0008]

However, the method of enclosing the dry package in the container has a drawback that the manufacturing process and the handling work of the product are complicated and the product price is high.

Further, resins improved by various methods have been gradually effective, but they are still not sufficient. A method of blending a novolac type epoxy resin and a phenol aralkyl resin with a matrix resin (Japanese Patent Laid-Open No. Sho 53-53).
-299, JP-A-59-67660), and a method of blending a matrix resin with a biphenyl-type epoxy resin and an ordinary phenol aralkyl resin in an amount of 60 to 85% by weight of a crushable filler (JP-A-3-207714). JP-A-4-48759 and JP-A-4-55523) not only have a high melt viscosity of the matrix resin and have a problem in filling property, but also are not at a sufficient level in preventing cracks in the resin portion during soldering. It was

An object of the present invention is to solve the problem of resin cracks that occur during the soldering process, to prevent deterioration of reliability, and to have good flow, that is, semiconductor encapsulation excellent in solder heat resistance, moisture resistance reliability and fluidity. An epoxy resin composition for use.

[0011]

Means for Solving the Problems The inventors of the present invention used an epoxy resin having a biphenyl skeleton as a matrix resin and a curing agent having a low viscosity and a specific structure, and a filler of 86 to
By adding 95% by weight, the above problems can be achieved.
The present invention has been completed by finding that an epoxy resin composition that meets the purpose can be obtained.

That is, the present invention provides an epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and a filler (C), wherein the epoxy resin (A) is represented by the following general formula (I) )

[Chemical 3] (In the formula, R ^{1 to} R ⁸ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a halogen atom.) An epoxy resin (a) having a skeleton represented by the formula is contained as an essential component, and the curing is performed. The agent (B) has the following general formula (II)

[Chemical 4] (In the formula, R may be the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. M represents an integer of 0 or more.) Phenol having a skeleton A phenol compound (b) having a melt viscosity of 2 poise or less at 150 ° C as a compound, and the proportion of the filler (C) is 86 to 95% by weight based on the whole amount. It is an epoxy resin composition for semiconductor encapsulation.

The structure of the present invention will be described in detail below.

It is important that the epoxy resin (A) in the present invention contains the epoxy resin (a) having the skeleton represented by the above formula (I) as an essential component. Epoxy resin
If (a) is not contained, the effect of preventing the occurrence of cracks in the soldering process will not be exhibited.

In the above formula (I), preferred examples of R ^{1 to} R ⁸ are hydrogen atom, methyl group, ethyl group, propyl group, i-propyl group, n-butyl group, sec-butyl group and tert. -Butyl group, chlorine atom, bromine atom and the like.

Preferred specific examples of the epoxy resin (a) in the present invention include 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-epoxypropoxy) -3. , 3 ', 5,5'-Tetramethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethyl-2-chlorobiphenyl, 4,4 ' -Bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-2-
Bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetraethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3' , 5,5′-tetrabutylbiphenyl and the like, 4,4′-bis (2,3-epoxypropoxy) biphenyl, 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5'-Tetramethylbiphenyl is particularly preferred.

The epoxy resin (A) in the present invention may contain the above epoxy resin (a) in combination with an epoxy resin other than the epoxy resin (a).

Other epoxy resins that can be used in combination include, for example, cresol novolac type epoxy resins, phenol novolac type epoxy resins, various novolac type epoxy resins synthesized from bisphenol A and resorcin, bisphenol A type epoxy resins, and linear fats. Examples thereof include group epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, halogenated epoxy resins and the like.

The ratio of the epoxy resin (a) contained in the epoxy resin (A) is not particularly limited, but in order to exert a more sufficient effect, the epoxy resin (a) is replaced with the epoxy resin (A). Usually 50% by weight or more, preferably 70%
It is necessary to contain at least wt%.

In the present invention, the compounding amount of the epoxy resin (A) is usually 2 to 7% by weight, preferably 2 to 5% by weight. When the compounding amount of the epoxy resin (A) is less than 2% by weight, the moldability is insufficient, which is not preferable.

The curing agent (B) in the present invention has the above formula (II)
It is important that the phenol compound has a skeleton represented by the formula (1) and that the phenol compound (b) has a melt viscosity at 150 ° C. of 2 poise or less as an essential component. When the phenol compound (b) is not contained, the effect of improving solder heat resistance and the effect of improving moisture resistance reliability are not sufficiently exerted.

In the above formula (II), preferred specific examples of R are hydrogen atom, methyl group, ethyl group, propyl group, i-propyl group, n-butyl group, sec-butyl group, tert-butyl group, Examples thereof include chlorine atom and bromine atom.

The melt viscosity of the phenol compound (b) at 150 ° C. is 2 poises or less, preferably 1.7 poises or less. When the melt viscosity of the phenol compound (b) at 150 ° C. is higher than 2 poise, it is difficult to improve the solder heat resistance by increasing the filling amount of the filler, and sufficient flow characteristics cannot be obtained.

The melt viscosity as referred to herein is the viscosity measured using a B type viscometer.

The amount of unreacted phenol contained in the phenol compound (b) is usually less than 1% by weight, preferably less than 0.5% by weight, more preferably 0.1% by weight.
Is less than. If the content of unreacted phenol is 1% by weight or more, it may cause deterioration of curing characteristics during transfer molding and deterioration of moisture resistance reliability.

Further, the curing agent (B) in the present invention includes the above-mentioned phenol compound (b) and the phenol compound.
A curing agent other than (b) may be used in combination. Examples of other curing agents that can be used in combination include phenol novolac resins, cresol novolac resins, various novolac resins synthesized from bisphenol A and resorcin, various polyhydric phenol compounds, maleic anhydride,
Examples thereof include acid anhydrides such as phthalic anhydride and pyromellitic anhydride, and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone. Of these, phenol novolac resin is preferable from the viewpoint of moisture resistance reliability.

The ratio of the phenol compound (b) contained in the curing agent (B) is not particularly limited, and the effect of the present invention is exhibited if the phenol compound (b) is contained as an essential component. In order to exert a sufficient effect, the phenol compound (b) must be contained in the curing agent (B) in an amount of usually 50% by weight or more, preferably 70% by weight or more.

In the present invention, the content of the curing agent (B) is usually 2 to 7% by weight, preferably 2 to 5% by weight. Furthermore, the blending 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, especially from the viewpoint of mechanical properties and moisture resistance reliability. It is preferably in the range of 0.8 to 1.2.

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, and for example, 2-methylimidazole, 2,4
-Dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-
Imidazole compounds such as 4-methylimidazole and 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,
4,6-tris (dimethylaminomethyl) phenol,
1,8-diazabicyclo (5,4,0) undecene-7
Such as tertiary amine compounds, zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum and other organometallic compounds, and triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine , Organic phosphine compounds such as tri (p-methylphenyl) phosphine and tri (nonylphenyl) phosphine. Among them, organic phosphine compounds are preferable, and triphenylphosphine is particularly preferably used, from the viewpoint of moisture resistance. Two or more kinds of these curing catalysts may be used in combination depending on the intended use, and the addition amount thereof is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin (A).

As the filler (C) in the present invention, fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber, etc. Among them, fused silica is particularly preferably used because it has a large effect of lowering the linear expansion coefficient and is effective in reducing stress.

The shape of the filler (C) is not particularly limited,
From the viewpoint of fluidity and solder heat resistance, it is preferable to contain spherical fused silica in the filler (C) in an amount of 40% by weight or more, preferably 60% by weight or more, and more preferably 90% by weight or more.

The fused silica referred to herein means an amorphous silica having a true specific gravity of 2.3 or less. The production does not necessarily have to go through the molten state, and any production method can be used. For example, a method of melting crystalline silica, a method of synthesizing from various raw materials, and the like can be mentioned.

In the present invention, the proportion of the filler (C) is 86 to 9 based on the solder heat resistance, moldability and low stress.
It is 5% by weight, preferably 88 to 95% by weight.

In the present invention, it is preferable in terms of reliability that the filler is surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, mercaptosilane and the like are preferably used.

The epoxy resin composition of the present invention includes a halogen compound such as a halogenated epoxy resin, a flame retardant such as a phosphorus compound, a flame retardant aid such as antimony trioxide, a colorant such as carbon black and iron oxide, and a silicone rubber. , Olefin copolymers, modified nitrile rubber, modified polybutadiene rubber, modified silicone oil and other elastomers,
Thermoplastic resins such as polyethylene, long-chain fatty acids, metal salts of long-chain fatty acids, esters of long-chain fatty acids, amides of long-chain fatty acids, mold release agents such as paraffin wax, and crosslinking agents such as organic peroxides are added arbitrarily. can do.

The epoxy resin composition of the present invention is preferably melt-kneaded, for example, by melt-kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single-screw or twin-screw extruder and a cokneader. Manufactured.

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition,% in an Example shows weight%.

Examples 1 to 6 and Comparative Examples 1 to 4 The components shown in Tables 1, 2 and 3 were dry blended with a mixer in the composition ratios shown in Table 4. 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 for semiconductor encapsulation.

[0039]

[Table 1]

[Chemical 5]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

This composition was molded by a low pressure transfer molding method under the conditions of 175 ° C. × 2 minutes and 180 ° C. ×
Post cure was carried out under the condition of 5 hours, and the physical properties of the respective compositions were measured by the following physical property measuring methods.

Solder heat resistance: 160-pin QF with a chip size of 12 × 12 mm equipped with a simulated element with Al vapor deposition on the surface
P 20 pieces are molded and post-cured, 85 ° C / 85% R
After moistening for 72 hours with H, heat treatment was performed in an IR reflow furnace having a maximum temperature of 245 ° C., and the number of external cracks and internal cracks was examined.

Moisture resistance reliability: Using QFP after solder heat resistance evaluation, under PCT conditions of 121 ° C./100% RH, the time at which the cumulative failure rate becomes 63% when the disconnection of the Al wiring becomes a failure was obtained and defined as the characteristic life.

Fillability: 160pin used for solder heat resistance test
QFP is visually and microscopically observed after molding,
The presence or absence of unfilled was examined.

Water absorption rate: 160pin used for solder heat resistance test
The water absorption rate in QFP was measured.

Table 5 shows the results of these evaluations.

[0049]

[Table 5]

As shown in Table 5, the epoxy resin compositions (Examples 1 to 6) of the present invention are excellent in solder heat resistance, moisture resistance reliability and filling property. On the other hand, epoxy resin
Comparative Example 1 which does not contain the epoxy resin (a) of the present invention in (A), Comparative Examples 2 and 3 which does not contain the curing agent (b) of the present invention in the curing agent (B) are solder heat resistance and moisture resistance reliability. Inferior in filling property and filling property.

Comparative Example 4, in which the amount of the filler added was less than 86% by weight, was inferior in solder heat resistance and moisture resistance reliability even though the epoxy resin and the curing agent of the present invention were used.

[0052]

The epoxy resin composition for semiconductor encapsulation of the present invention comprises a bifunctional epoxy resin having a specific structure in the epoxy resin, and a low viscosity curing agent having a specific structure in the curing agent.
Since the filler filling amount is as high as 86 to 95% by weight,
Excellent solder heat resistance, moisture resistance reliability, and fluidity.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 23/29 23/31

Claims (1)

[Claims] 1. Epoxy resin (A), curing agent (B), filler
An epoxy resin composition comprising (C), wherein the epoxy resin (A) has the following general formula (I): (In the formula, R ^{1 to} R ⁸ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a halogen atom.) An epoxy resin (a) having a skeleton represented by the formula is contained as an essential component, and the curing is performed. The agent (B) has the following general formula (II): (In the formula, R may be the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. M represents an integer of 0 or more.) Phenol having a skeleton A phenol compound (b) having a melt viscosity of 2 poise or less at 150 ° C. of the compound as a compound, and the filler (C)
Is 86 to 95% by weight of the whole, an epoxy resin composition for semiconductor encapsulation.