JP3092176B2 - 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 having excellent solder heat resistance and moisture resistance reliability.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, adhesiveness, etc., and can be imparted with various properties by blending and prescription, so that they are used as industrial materials such as paints, adhesives, and electrical insulating materials. Have been.

For example, as a method for sealing electronic circuit components such as semiconductor devices, a hermetic seal made of metal or ceramic and a phenol resin, silicone resin,
Resin sealing using an epoxy resin or the like has been proposed. However, resin sealing with epoxy resin is mainly used in terms of balance between economy, productivity, and physical properties.

In recent years, the density and automation of component mounting on a printed circuit board have been advanced, and instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the board,
The “surface mounting method” of soldering components to the board surface has become popular. Along with that, the package is also a conventional DIP
(Dual Inline Package) is shifting to a thin FPP (Flat Plastic Package) suitable for high-density mounting and surface mounting.

[0005] With the shift to the surface mounting method, the soldering process, which has not been much of a problem in the past, has become a major 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. Soldering methods for surface mounting include solder bath immersion and heating with saturated vapor of inert gas (vapor phase method).
And an infrared reflow method are used. In any case, the entire package is heated to a high temperature of 210 to 270 ° C. Therefore, the package sealed with the conventional sealing resin has a problem that cracks occur in the resin portion at the time of soldering, the reliability is reduced, and the package cannot be used as a product.

[0006] The occurrence of cracks in the soldering process
It is said that the moisture absorbed between the post-curing and the mounting process explosively turns into steam and expands during soldering and heating, and as a countermeasure, the post-cured package is completely dried and sealed. The method of storing and shipping the products 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 novolak type curing agent (JP-A-63
-251419, JP-A-1-87616)
Or using 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl as a curing agent (I) E
Proceedings of the EE 1990 Conference, p. 625) have been proposed.

On the other hand, a method using an epoxy resin having a naphthalene skeleton and a phenol novolak type curing agent for the purpose of lowering the stress of the sealing resin (JP-A-2-88621, JP-A-2-110958) and the like are known. Proposed.

[0009]

However, the method of enclosing a dry package in a container has disadvantages in 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 novolak type curing agent (JP-A-63-251419, JP-A-1-87616)
Japanese Patent Application Laid-Open No. H11-146572 has an effect of improving solder heat resistance in a relatively thick package, but does not exhibit an effect of improving solder heat resistance in a thinner package such as a TSOP (Thin Small Outline Package), and furthermore, immerses solder. Thereafter, the moisture resistance reliability was not sufficient. In addition, the method using 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl as a curing agent has poor reactivity, low glass transition temperature, and poor moisture resistance reliability. It was not practical.

A method using an epoxy resin having a naphthalene skeleton and a phenol novolak type curing agent (JP-A-2-88621, JP-A-2-110958) is effective in improving the solder heat resistance even in a thin package such as TSOP. However, it was not sufficient, and the reliability of moisture resistance after immersion in solder was insufficient and not practical.

An object of the present invention is to solve the problem of cracks generated in the soldering step and to provide an epoxy resin composition for semiconductor encapsulation having excellent moisture resistance reliability after solder immersion.

[0013]

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

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

Embedded image ( Wherein two of R ^{1 to} R ⁸ are 2,3-epoxy
And represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. ) Is contained as an essential component, and the curing agent (B) is represented by the formula (II):

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

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

It is important that the epoxy resin (A) in the present invention contains an epoxy resin (a) having a skeleton represented by the above formula (I) as an essential component.

When the epoxy resin (a) is not contained, the effect of preventing cracks in the soldering step is not exhibited.

In the above formula (I), 2,3 of R ¹ to R ⁸
Preferred specific examples of the group other than the epoxypropoxy group include a hydrogen atom, a methyl group, an ethyl group, a propyl group,
-Propyl group, n-butyl group, sec-butyl group, te
Examples thereof include an rt-butyl group, a chlorine atom and a bromine atom.

Preferred specific examples of the epoxy resin (a) in the present invention include 1,5- bis (2,3-epoxy)
Propoxy) naphthalene, 1,5- bis (2,3-epoxy)
Xypropoxy) -7-methylnaphthalene, 1,6- bi
(2,3-epoxypropoxy) naphthalene, 1,6
-Bis (2,3-epoxypropoxy) -2-methylnaphthalene, 1,6- bis (2,3-epoxypropoxy )
B) -8-methylnaphthalene, 1,6- bis (2,3-
Epoxypropoxy) -4,8-dimethylnaphthalene,
2-bromo-1,6-bis (2,3-epoxypropoxy
B) naphthalene, 8-bromo-1,6- bis (2,3-
Epoxypropoxy) naphthalene and the like.

The epoxy resin (A) in the present invention can contain the above-mentioned epoxy resin (a) in combination with another epoxy resin other than the epoxy resin (a). Other epoxy resins that can be used in combination, for example,
Cresol novolak epoxy resin, phenol novolak epoxy resin, various novolak epoxy resins synthesized from bisphenol A, resorcin, etc., bisphenol A epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, 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, and if the epoxy resin (a) is contained as an essential component, the effect of the present invention is exhibited. In order to exert a sufficient effect, it is necessary that the epoxy resin (a) is usually contained in the epoxy resin (A) in an amount of 50% by weight or more, preferably 70% by weight or more.

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

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

When the biphenyl compound (b) is not contained, not only is the effect of preventing the occurrence of cracks in the soldering step small, but also the effect of improving the humidity resistance after solder immersion is small.

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

[0026]

Embedded image (In the formula, R represents a hydrogen atom, an aryl group or an alkyl group.)

Among them, phenol novolak resins and phenol compounds (b ') are preferably used from the viewpoint of moisture resistance reliability. Particularly preferably, a phenol compound (b ')
It is.

The ratio of the biphenyl compound (b) contained in the curing agent (B) is not particularly limited, and the effect of the present invention is exhibited if the biphenyl compound (b) is contained as an essential component. In order to exert a sufficient effect, the biphenyl compound (b) is usually added to the curing agent (B) in an amount of 5%.
７０70% by weight, preferably 15-50% by weight.

In the present invention, the amount of the curing agent (B) is usually 1 to 20% by weight, preferably 2 to 15% by weight. Furthermore, the mixing 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.

In the present invention, the epoxy resin (A)
A curing catalyst may be used for accelerating the curing reaction between the curing agent and the curing agent (B). The curing catalyst is not particularly limited as long as it promotes the curing reaction. 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;
Organic phosphine compounds such as triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, and tri (nonylphenyl) phosphine are exemplified. Of these, organic phosphine compounds are preferred from the viewpoint of moisture resistance, and triphenylphosphine is particularly preferably used.

Depending on the application, two or more of these curing catalysts may be used in combination, and the amount added is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin (A).

The filler (C) in the present invention includes fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, asbestos, glass fiber and the like. . Among them, fused silica is preferably used because it has a large effect of lowering the coefficient of linear expansion and is effective in reducing stress. 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 composition contains fused silica (c) comprising the following crushed fused silica (C ′) 95 to 60% by weight and spherical fused silica (C ″) having an average particle size of 40 μm or less 5 to 40% by weight. Here, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%.

In the present invention, it is preferable from the standpoint of reliability that the filler (C) be surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, a silane coupling agent such as epoxy silane, amino silane, and mercapto silane is preferably used.

The epoxy resin composition of the present invention contains a halogen compound such as a halogenated epoxy resin, a flame retardant such as a phosphorus compound, a flame retardant auxiliary such as antimony trioxide, a colorant such as carbon black and iron oxide, a silicone rubber. Styrene-based block copolymers, modified nitrile rubber, modified polybutadiene rubber, modified silicone oil and other elastomers, polyethylene and other thermoplastic resins, long-chain fatty acids,
A releasing agent such as 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, paraffin wax and a crosslinking 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 a Banbury mixer, a kneader, a roll, a single or twin screw extruder and a co-kneader. Manufactured.

[0036]

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

Examples 1 to 4 and Comparative Examples 1 to 4 The components shown in Table 1 were dry-blended by a mixer at the composition ratios shown in Table 2 . This is adjusted to a roll surface temperature of 90.
The mixture was heated and kneaded for 5 minutes using a mixing roll at a temperature of 5.degree. C., then cooled and pulverized to produce an epoxy resin composition.

Using this composition, low-pressure transfer molding was carried out at 175 ° C. for 2 minutes to obtain the following physical properties.
The physical properties and moldability of each composition were measured by a moldability measurement method. Solder heat resistance: 28 pins with simulated element
16 TSOPs were molded, post-cured at 180 ° C. for 5 hours, humidified at 85 ° C./85% RH for 16 hours, and then heated to 245 ° C. for 10 seconds using an IR reflow furnace. I asked.

PCBT after solder immersion: TSOP after solder heat resistance evaluation was 125 ° C., 85% RH, bias voltage 10
USPCBT was performed at V and the time at which the cumulative failure rate reached 50% was determined.

Table 2 shows the measurement results.

[0041]

[Table 1]

[0042]

[Table 2]

As shown in Table 2, the epoxy resin compositions of the present invention (Examples 1 to 3) are excellent in solder heat resistance and moisture resistance reliability after solder immersion. In particular, Example 4 using tris (3-hydroxyphenyl) methane as a crosslinking agent
Showed excellent solder heat resistance and moisture resistance reliability.

On the other hand, in Comparative Examples 1 to 4 in which the epoxy resin (A) does not contain the epoxy resin (a) of the present invention and the biphenyl compound (b), the solder heat resistance and the moisture resistance reliability after solder immersion are poor. ing. Comparative Example 5, in which the proportion of the filler (C) was less than 75% by weight, was inferior in solder heat resistance and moisture resistance reliability after soldering.

[0045]

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 step, and has solder heat resistance and moisture resistance after solder immersion. Excellent reliability.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H01L 23/31 (56) References JP-A-2-88621 (JP, A) JP-A-63-251419 (JP, A) Kaihei 1-87616 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 59 / 24,59 / 62

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) has the following general formula (I): 1) ( Wherein two of R ^{1 to} R ⁸ are 2,3-epoxy
And represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. ) Is contained as an essential component, and the curing agent (B) is represented by the formula (II): An epoxy resin composition for semiconductor encapsulation , comprising a biphenyl compound (b) represented by the following formula as an essential component, wherein the proportion of the filler (C) is 75 to 90% by weight of the whole. 2. A curing agent (B) comprising the following general formula (III) together with the biphenyl compound (b): The epoxy resin composition according to claim 1, comprising a phenol compound (b ') represented by the formula (wherein R represents a hydrogen atom, an aryl group or an alkyl group).