JP3004454B2 - Resin composition - 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 soldering stress resistance in surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. In particular, in an integrated circuit, ortho-cresol novolak epoxy resin having excellent heat resistance and moisture resistance is made of a novolak type. An epoxy resin composition cured with a phenol resin is used.
However, in recent years, chips have become larger and larger as integrated circuits have become more highly integrated, and packages have become smaller and thinner flat packages that are surface-mounted from conventional DIP types.
It is changing to SOP, SOJ, PLCC.

That is, a large chip is enclosed in a small and thin package, and cracks are generated due to stress, and problems such as a decrease in moisture resistance due to the cracks have been greatly highlighted. In particular, there has been a problem in that abrupt exposure to a high temperature of 200 ° C. or more in a soldering process causes a crack in a package and a peeling of a resin and a chip to deteriorate moisture resistance. Development of a highly reliable sealing resin composition suitable for sealing these large chips has been desired. In order to solve these problems, thermoplastic oligomers (Japanese Patent Application Laid-Open No. 62-15849) and various silicone compounds (Japanese Patent Application Laid-Open No. 62-1) have been added for the purpose of reducing thermal shock during soldering.
No. 1585, No. 62-116654, No. 62-1
No. 28162), and further modified with silicone (Japanese Unexamined Patent Publication No.
However, in any case, cracks occur in the package at the time of soldering, and it has not been possible to obtain a highly reliable epoxy resin composition for semiconductor encapsulation.

On the other hand, in order to obtain an epoxy resin composition for semiconductor encapsulation having excellent heat stress resistance during soldering, that is, excellent solder stress resistance, a biphenyl type epoxy resin is used as a resin system (Japanese Patent Application Laid-Open No. 65116/1988). Publication) has been studied, but the use of a biphenyl type epoxy resin improves the adhesion to the lead frame and low water absorption, and improves the solder stress resistance, and in particular, reduces the occurrence of cracks.
At a high temperature such as 250 ° C. or higher, the solder stress resistance is insufficient.

[0005]

The present invention solves such a problem by using an epoxy resin represented by the formula (1) to reduce water absorption and linear expansion. Epoxy resin composition for semiconductor encapsulation that uses the curing agent shown to achieve low water absorption and low elasticity during heat, and the synergistic effect significantly improves the solder stress resistance of the semiconductor package when mounted on a substrate. Is to provide.

[0006]

The resin composition of the present invention comprises:
(A) Epoxy resin 1,6- represented by the following formula (1)
Bis (2,3-epoxypropoxy) naphthalene

[0007]

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[0008] 30 to 100 with respect to the total amount of epoxy resin
(B) a phenolic resin represented by the following formula (2):

[0009]

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Of the total phenolic resin curing agent by 30
An epoxy resin composition for semiconductor encapsulation, comprising a curing agent containing up to 100% by weight, (C) an inorganic filler and (D) a curing accelerator, which has excellent solder stress resistance as compared with conventional resin compositions. It is.

The epoxy resin represented by the formula (1) used in the present invention is 1,6-bis (2,3-epoxypropoxy) naphthalene, which exhibits a semi-solid property at room temperature and a molding temperature (175 ° C.) In this case, the viscosity is very low, so that the amount of the filler added can be greatly increased. Thus, in addition to the characteristics of the resin body that is excellent in low water absorption, the coefficient of linear expansion of the resin is small, and the mold releasability during molding is excellent, the resin composition highly filled with a filler has a water absorption rate and a linear It has the characteristics that the coefficient of expansion is smaller and the impact strength is excellent, and shows good results in the resistance to soldering stress during soldering. The amount of 1,6-bis (2,3-epoxypropoxy) naphthalene used can be adjusted to maximize the solder stress resistance.

In order to obtain the effect of resistance to soldering stress,
1,6-bis (2,3-epoxypropoxy) naphthalene is used in an amount of 30% by weight or more, preferably 6% by weight of the total epoxy resin.
It is desirable to use 0% by weight or more. If it is less than 30% by weight,
Low water absorption and low coefficient of linear thermal expansion cannot be obtained sufficiently, and solder stress resistance is insufficient. When an epoxy resin other than 1,6-bis (2,3-epoxypropoxy) naphthalene is used in combination, the epoxy resin used generally refers to any polymer having an epoxy group. For example, trifunctional epoxy resins such as bisphenol type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, phenol novolak type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, and epoxy resin containing triazine nucleus And the like.

The phenol resin curing agent represented by the formula (2) is a polycondensate of phenol and P-xylene glycol dimethyl ether, and has characteristics of low water absorption and excellent flexibility. In particular, it has excellent flexibility at high temperatures during soldering, and has a remarkable effect on solder heat resistance during soldering at 250 to 260 ° C. By adjusting the amount of the polycondensed phenol resin curing agent of phenol and P-xylene glycol dimethyl ether, the solder heat resistance can be maximized by adjusting the amount. In order to bring out the effect of solder heat resistance, the phenol resin curing agent represented by the formula (2) is used in an amount of 30% by weight or more, preferably 60% by weight of the total curing agent.
The above use is desirable. If the amount is less than 30% by weight, the flexibility becomes insufficient, and the soldering heat resistance at the time of soldering cannot be sufficiently obtained. The value of n is from 1 to 6, and when it exceeds 6, the fluidity is reduced and the moldability is deteriorated.

When other than the phenolic resin curing agent represented by the formula (2) is used in combination, the term mainly refers to all polymers having a phenolic hydroxyl group. For example, a phenol novolak resin, a cresol novolak resin, a dicyclopentadiene-modified phenol resin, a copolymer of a dicyclopentadiene-modified phenol resin with a phenol novolak and a cresol novolak resin,
A naphthalene-modified phenol resin or the like can be used. Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, silica powder obtained by pulverizing secondary aggregated silica powder or porous silica powder, alumina And the like, and a fused silica powder is particularly preferred.

The curing accelerator used in the present invention may be any one that promotes the reaction between an epoxy group and a phenolic hydroxyl group, and those commonly used for sealing materials can be widely used. For example, diazabicycloundecene (DBU), triphenylphosphine (TPP), dimethylbenzylamine (BDMA), 2-methylimidazole (2MZ), or the like is used alone or in combination of two or more. The epoxy resin composition for encapsulation of the present invention contains an epoxy resin, a curing agent, an inorganic filler and a curing accelerator as essential components, but may optionally further comprise a silane coupling agent, a brominated epoxy resin, and trioxide. Various additives such as flame retardants such as antimony and hexabromobenzene, coloring agents such as carbon black and red iron oxide, release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber are appropriately mixed. No problem.

In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent,
After a curing accelerator, a filler, and other additives are sufficiently and uniformly mixed by a mixer or the like, the mixture is further melt-kneaded by a hot roll or a kneader, cooled, and pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating and the like of electronic parts or electric parts.

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

Example 1 4.4 parts by weight of an epoxy resin represented by the following formula (1) (epoxy equivalent: 150)

[0018]

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Orthocresol novolak epoxy resin (softening point 65 ° C., epoxy equivalent 200) 8.8 parts by weight Phenolic resin curing agent represented by the formula (3) (softening point 80 ° C., hydroxyl equivalent 170) 3.6 parts by weight

[0020]

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(A mixture in which n = 1 is 20% by weight, n = 2 is 60% by weight, and n = 3 is 20% by weight) 7.2 parts by weight of a phenol novolak resin curing agent (softening point: 105 ° C., hydroxyl equivalent: 100) 75.0 parts by weight of fused silica powder 0.2 parts by weight of triphenylphosphine 0.3 parts by weight of carbon black 0.5 parts by weight of carnauba wax are mixed at room temperature with a mixer, and kneaded at 70-100 ° C. with a biaxial roll, After cooling, it was pulverized to obtain a molding material. The obtained molding material is tableted, and a low pressure transfer molding machine is used to seal a 6 × 6 mm chip in a 52p package at 175 ° C., 70 kg / cm ² , for 120 seconds for solder cracking test. A 3 × 6 mm chip was sealed in a 16 pSOP package for a sex test. The sealed test element was subjected to the following solder crack test and solder moisture resistance test. Table 1 shows the test results. It was excellent together with solder stress property and solder moisture resistance.

Solder stress test: The sealed test element was treated for 72 hours in an environment of 85 ° C. and 85% RH, then immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element was tested at 85 ° C for 8
After treating for 72 hours in an environment of 5% RH and then immersing in a solder bath at 240 ° C. for 10 seconds, a pressure cooker test (125 ° C., 100% RH) was performed to measure the open failure of the circuit.

Examples 2 to 5 Compounded according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. A sealed molded product for a test was obtained from this molding material, and a solder crack test and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results. All were excellent in solder stress property and solder moisture resistance.

Comparative Examples 1 to 5 Compounded according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. A sealed molded product for a test was obtained from this molding material, and a solder crack test and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results. All were poor in solder stress property and solder moisture resistance.

[0025]

[Table 1]

[0026]

The epoxy resin composition for encapsulating a semiconductor according to the present invention is extremely excellent in solder stress resistance and moisture resistance, and thus is suitable as a resin composition for encapsulating a surface mount package.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁷ Identification code FI H01L 23/31

Claims (1)

(57) [Claims] (A) An epoxy resin represented by the following formula (1): 1,6-bis (2,3-epoxypropoxy) naphthalene (B) a phenolic resin represented by the following formula (2): An epoxy resin composition for semiconductor encapsulation comprising, as essential components, a curing agent containing from 30 to 100% by weight based on the total amount of the phenol resin curing agent, (C) an inorganic filler and (D) a curing accelerator.