JP2501140B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

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 and moisture resistance reliability.

[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.

Recently, 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 that, the package is also the conventional DIP
(Dual in-line package) is shifting to 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 conventional package sealed with the sealing resin has a problem that the resin portion is cracked at the time of soldering, the reliability is lowered, and the package cannot be used as a product.

The occurrence of cracks in the soldering process is
It is said that the 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 studies have been made to improve sealing resins.
For example, a method using an epoxy resin having a biphenyl skeleton and a phenol novolac type curing agent (Japanese Patent Laid-Open No. Sho 63-63).
-251419, JP-A-1-87616)
Or a method using 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl as a curing agent (I) E
EE 1990 Conference Proceedings, page 625), etc. have been proposed.

[0008]

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

A method using an epoxy resin having a biphenyl skeleton and a phenol novolac type curing agent (Japanese Patent Laid-Open No. 63-251419 and Japanese Patent Laid-Open No. 1-87616).
In Japanese Patent Laid-Open Publication No. 2003-264, the effect of preventing cracks during soldering and the reliability of moisture resistance after soldering were not sufficient. In addition, the method of using 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl as a curing agent has poor reactivity, a low glass transition temperature, and poor moisture resistance reliability. It wasn't practical.

An object of the present invention is to provide a semiconductor encapsulating epoxy resin composition which solves the problem of cracks generated in the soldering process and has excellent moisture resistance reliability after soldering.

[0011]

Means for Solving the Problems The inventors of the present invention achieved the above-mentioned object by adding a curing agent having a specific structure to an epoxy resin having a biphenyl skeleton, and an epoxy resin composition meeting the purpose. They have found that a product can be obtained and have reached the present invention.

That is, the present invention is an epoxy resin composition containing an epoxy resin (A), a curing agent (B) and a filler (C), wherein the epoxy resin (A) has the following general formula: (I)

Embedded image (In the formula, R ^{1 to} R ⁸ represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.) 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 formula (II)

Embedded image An epoxy resin composition for semiconductor encapsulation , which contains the biphenyl compound (b) represented by the formula (1) as an essential component and the proportion of the filler (C) is 75 to 90% by weight of the whole.

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.

If the epoxy resin (a) is not contained, the effect of preventing the occurrence of cracks in the soldering process is not exerted.

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 Examples include ′, 5,5′-tetrabutylbiphenyl.

The epoxy resin (A) in the present invention may contain an epoxy resin other than the epoxy resin (a) in combination with the above epoxy resin (a). Other epoxy resins that can be used in combination include, for example,
Cresol novolac type epoxy resin, phenol novolac type epoxy resin, various novolac type epoxy resins synthesized from bisphenol A and resorcin, bisphenol A type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy Examples thereof include resins and halogenated epoxy resins.

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

In the present invention, the compounding amount of the epoxy resin (A) is usually 4 to 20% by weight, preferably 6 to 18% by weight.
Is.

The curing agent (B) in the present invention is represented by the above formula (II).
It is important to contain the biphenyl compound (b) represented by as an essential component.

When the biphenyl compound (b) is not contained, not only the effect of preventing the occurrence of cracks in the soldering process is small, but also the effect of improving the moisture resistance reliability after dipping the solder is small.

The curing agent (B) in the present invention is preferably used in combination with a polyfunctional curing agent other than the above biphenyl compound (b). Examples of curing agents that can be used in combination include phenol novolac resins, cresol novolac resins, various novolac resins synthesized from bisphenol A and resorcin, phenol compounds (b ') represented by the following general formula (III), and maleic anhydride. Acid anhydrides such as pyromellitic dianhydride and phthalic anhydride, and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone.

[0024]

[Chemical 6] (In the formula, R represents a hydrogen atom, an aryl group or an alkyl group.).

Of these, a phenol novolac resin and a phenol compound (b ') are preferably used from the viewpoint of moisture resistance reliability. Particularly preferred is a phenol compound (b ').

The proportion of the biphenyl compound (b) contained in the curing agent (B) is not particularly limited, but the effect of the present invention is exhibited if the biphenyl compound (b) is contained as an essential component. In order to exert a more sufficient effect, it is necessary that the curing agent (B) contains the biphenyl compound (b) in an amount of usually 5 to 90% by weight, preferably 15 to 50% by weight.

In the present invention, the content of the curing agent (B) is usually 1 to 20% by weight, preferably 2 to 15% by weight. Further, 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 from the viewpoint of mechanical properties and moisture resistance. .8-
It is preferably in the range of 1.2.

Further, in the present invention, the epoxy resin (A)
A curing catalyst may be used to accelerate the curing reaction of the curing agent (B). The curing catalyst is not particularly limited as long as it accelerates the curing reaction, and for example, 2-methylimidazole,
Imidazole compounds such as 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyl Tertiary amine compounds such as dimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetra Organometallic compounds such as methoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum and triphenylphosphine, trimethylphosphine,
Examples thereof include organic phosphine compounds such as triethylphosphine, tributylphosphine, 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).

Examples of the filler (C) in the present invention include fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, asbestos and glass fiber. . Among them, fused silica has a large effect of lowering the linear expansion coefficient and is effective in lowering stress, and is therefore preferably used. Furthermore, the ratio of the filler (C) is 75 to 9
0% by weight, and the filler (C) has an average particle size of 10 μm
From the viewpoint of solder heat resistance, the following fused silica (c) consisting of 95 to 60% by weight of crushed fused silica (C ′) and 5 to 40% by weight of spherical fused silica (C ″) having an average particle size of 40 μm or less is included. Preferably, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%.

In the present invention, the surface treatment of the filler (C) with a coupling agent such as a silane coupling agent or a titanate coupling agent is preferable in terms of reliability. 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 halogen compounds such as halogenated epoxy resins, flame retardants such as phosphorus compounds, flame retardant aids such as antimony trioxide, colorants such as carbon black and iron oxide, and silicone rubber. , Styrene block copolymers, modified nitrile rubber, modified polybutadiene rubber, elastomers such as modified silicone oil, thermoplastic resins such as polyethylene, long chain fatty acids,
A metal salt of a long-chain fatty acid, an ester of a long-chain fatty acid, an amide of a long-chain fatty acid, a releasing agent such as paraffin wax, and a cross-linking agent such as an organic peroxide can be optionally added.

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

[0034]

The present invention will be described below in detail with reference to examples.

Examples 1 to 4 and Comparative Examples 1 to 5 The components shown in Table 1 were dry blended with a mixer in the composition ratios shown in Table 2. Roll surface temperature 90
The mixture was heated and kneaded for 5 minutes using a mixing roll at ℃, cooled and pulverized to produce an epoxy resin composition.

This composition was molded by a low pressure transfer molding method under the conditions of 175 ° C. × 2 minutes to obtain the following physical properties:
The physical properties and moldability of each composition were measured by the moldability measurement method.

Solder heat resistance: 80 pi equipped with a simulated element
n QFP 20 pieces were molded, post-cured at 180 ° C. for 5 hours, humidified at 85 ° C./85% RH for 72 hours, then heated to 245 ° C. for 10 seconds using an IR reflow furnace, and the ratio of the number of QFPs without cracks I asked.

PCBT after soldering: 80 after soldering
USP CBT was performed using pin QFP at 125 ° C., 85% RH, and a bias voltage of 10 V, and the time at which the cumulative failure rate was 50% was obtained.

The measurement results are shown in Table 2.

[0040]

[Table 1]

[Table 2] As seen in Table 2, the epoxy resin compositions of the present invention (Examples 1 to 4) are excellent in solder heat resistance and moisture resistance reliability after soldering. In particular, Example 4 using tris (3-hydroxyphenyl) methane as the curing agent showed excellent solder heat resistance and moisture resistance reliability.

On the other hand, Comparative Example 4 in which the epoxy resin (A) does not contain the epoxy resin (a) is inferior in solder heat resistance and moisture resistance reliability. Further, in Comparative Examples 1 to 3 in which the curing agent (B) does not contain the curing agent (b), the solder heat resistance and the moisture resistance reliability after the solder treatment are inferior to those of the corresponding Examples. Furthermore, Comparative Example 5 in which the proportion of fused silica (C) is less than 75% by weight of the whole is inferior in solder heat resistance and moisture resistance reliability after soldering.

[0042]

Industrial Applicability The epoxy resin composition of the present invention is an epoxy resin composition suitable for semiconductor encapsulation, which solves the problem of cracks generated in the soldering process, and has solder heat resistance and moisture resistance after soldering. It has excellent reliability.

Claims (2)

(57) [Claims] 1. 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 1] (In the formula, R ^{1 to} R ⁸ represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.) An epoxy resin (a) having a skeleton represented by The agent (B) is represented by the following formula (II): The epoxy resin composition for semiconductor encapsulation containing the biphenyl compound (b) represented by the above as an essential component, and the proportion of the filler (C) is 75 to 90% by weight of the whole. 2. The curing agent (B) is a biphenyl compound (b).
And the following general formula (III) (In formula, R represents a hydrogen atom, an aryl group, or an alkyl group.) The epoxy resin composition of Claim 1 containing the phenol compound (b ') represented by this.