JP3310447B2 - Epoxy 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 resistance to soldering stress in surface mounting of semiconductor devices.

[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, an ortho-cresol novolac type epoxy resin having excellent heat resistance and moisture resistance is replaced with phenol. An epoxy resin composition cured with a novolak resin and blended with an inorganic filler such as fused silica or crystalline silica as a filler is used. However, in recent years, the chip has been gradually increased in size with the increase in the integration degree of the integrated circuit, and the package has been changed to the conventional DIP.
Small and thin QFP, SO surface mounted from type
P, SOJ, TSOP, TQFP, PLCC have been changed. That is, a large chip is sealed in a small and thin package, and cracks are generated due to thermal stress. Problems such as a decrease in moisture resistance due to these cracks are greatly highlighted. In particular, there has been a problem in that the device is suddenly exposed to a high temperature of 200 ° C. or more in the soldering process, and the moisture resistance is deteriorated due to cracking of the package or separation of the resin and the chip. Therefore,
The development of a highly reliable resin composition for semiconductor encapsulation suitable for encapsulating these large chips has been desired.

[0003]

The present invention solves such problems by using an epoxy resin represented by the formula (1) as an epoxy resin and a phenol resin represented by the formula (2) as a phenol resin curing agent. An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation in which the use of a curing agent has significantly improved the solder stress resistance of a semiconductor package during mounting.

[0004]

According to the present invention, there is provided an epoxy resin containing (A) an epoxy compound represented by the following formula (1) in an amount of 30 to 100% by weight based on the total epoxy resin amount:

[0005]

Embedded image (Wherein R ₁ to R ₄ are a methyl group, R _{5 to} R ₈ are a hydrogen atom,
₉ and R ₁₀ are tert-butyl groups )

(B) The phenolic resin curing agent represented by the following formula (2) is used in an amount of 30 to 30% based on the total amount of the phenolic resin curing agent.
A phenolic resin curing agent containing 100% by weight,

[0007]

Embedded image (R in the formula is the same or different atom or group selected from hydrogen, halogens, and alkyl groups having 1 to 5 carbon atoms)

An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components,
Compared with the conventional epoxy resin composition, it has solder crack resistance and moisture resistance after soldering as excellent reliability.

The epoxy compound represented by the molecular structure of the formula (1) can be obtained by subjecting a bifunctional bisphenol type compound to glycidyl etherification using epichlorohydrin. Compared with the conventional cresol novolak type epoxy resin, low viscosity is obtained at the time of melting, and the inorganic filler can be further compounded. Therefore, the cured product can have low moisture absorption, low thermal expansion, and high strength. By adjusting the amount of the epoxy compound used, solder crack resistance can be maximized. In order to bring out the effect of solder crack resistance, it is desirable to use the epoxy compound represented by the formula (1) in an amount of 30% by weight or more, preferably 50% by weight or more based on the total epoxy resin amount. If it is less than 30% by weight, the intended solder crack resistance is insufficient. Further, R ₁ to R ₄ in the formula are methyl
And R _{5 to} R _{8 are} hydrogen atoms. R ₉ and R ₁₀ are tertiary butyl groups in consideration of the hydrophobicity of the resin . N in the formula is from 0 to 20, and when it exceeds 20, the fluidity is poor. More preferably, n is 0-10.

When an epoxy resin other than the epoxy resin represented by the formula (1) is used in combination, it refers to a compound or polymer in general having two or more epoxy groups. For example, it refers to a biphenyl type epoxy compound, a bisphenol type epoxy compound, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a triphenolmethane type epoxy compound, an alkyl-modified triphenolmethane type epoxy compound and the like.

The phenol resin curing agent represented by the formula (2) is obtained by polymerizing meta-xylene and phenols by a Friedel-Crafts alkylation reaction. Compared to the conventional phenol novolak resin, the cured product has a lower elastic modulus in the rubber region, lower moisture absorption, and better adhesion to metals such as lead frames (42 alloy, copper alloy).
By adjusting the amount of the phenol resin curing agent used, solder crack resistance can be maximized. In order to bring out the effect of the solder crack resistance, the phenol resin curing agent represented by the formula (2) is used in an amount of 30% by weight or more, preferably 50% by weight, based on the total amount of the phenol resin curing agent.
It is desirable to use not less than weight%. If it is less than 30% by weight, the intended solder crack resistance is insufficient. Furthermore, R in the formula
Are the same or different atoms or groups selected from hydrogen, halogens, and alkyl groups having 1 to 5 carbon atoms;
Of these, a hydrogen atom is preferred. If the alkyl group has more than 5 carbon atoms, the curability will be poor. N in the formula is 0
When it exceeds 20, the fluidity is poor. More preferably, n is 0-10.

When other phenolic resin curing agents are used in addition to the phenolic resin curing agent represented by the formula (2), it generally refers to polymers having phenolic hydroxyl groups. For example,
Phenol novolak resin, cresol novolak resin, dicyclopentadiene-modified phenol resin, paraxylylene-modified phenol resin, terpene-modified phenol resin, triphenolmethane compound, etc. ,
Terpene-modified phenolic resins and mixtures thereof are preferred. The amount of these curing agents is preferably such that the number of epoxy groups in the epoxy compound and the number of hydroxyl groups in the curing agent match.

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, and alumina. Mixtures of powder and spherical silica powder are preferred. The amount of the inorganic filler is preferably 80 to 90% by weight based on the total amount of the epoxy resin composition from the viewpoint of solder crack resistance. If the amount of the inorganic filler is less than 80% by weight, low thermal expansion and low water absorption cannot be obtained, and solder crack resistance is insufficient. On the other hand, if the amount of the inorganic filler exceeds 90% by weight, problems such as displacement of a die pad and a gold wire in a semiconductor package due to an increase in viscosity occur.

The curing accelerator used in the present invention may be any one which promotes a curing reaction between an epoxy group and a hydroxyl group, and those generally used for a sealing material can be widely used. For example, 1,8-diazabicycloundecene, triphenylphosphine, dimethylbenzylamine, 2-methylimidazole and the like are used alone or as a mixture of two or more.

The epoxy resin composition of the present invention comprises an epoxy resin, a phenolic resin curing agent, an inorganic filler and a curing accelerator as essential components. In addition to this, a silane coupling agent, a brominated epoxy resin, Various additives such as flame retardants such as antimony trioxide 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 used. It is safe to mix.
In addition, in order to manufacture the epoxy resin composition for encapsulation of the present invention as a molding material, epoxy resin, phenol resin curing agent, curing accelerator, inorganic filler, and other additives are sufficiently and uniformly mixed by a mixer or the like. After that, the mixture is further melt-kneaded with a hot roll or a kneader, cooled and pulverized to obtain a sealing material. These molding materials are used for coating electric or electronic components such as transistors and integrated circuits,
It can be applied to insulation, sealing, and the like.

Hereinafter, the present invention will be described specifically with reference to Examples. Example 1 The following composition: an epoxy compound represented by the formula (3) (melting point: 85 ° C., epoxy equivalent: 240 ° C.) 6.68 parts by weight

[0017]

Embedded image

Orthocresol novolak type epoxy resin (softening point: 58 ° C., epoxy equivalent: 200 g / eq) 1.67 parts by weight A phenol resin curing agent represented by the formula (4) (softening point: 63 ° C., hydroxyl equivalent: 170 g / eq) 4.36 parts by weight

[0019]

Embedded image (The value of n is a mixture showing a value of 0 to 3, and the weight ratio is 0.65 for n = 1, 0.65 for n = 1, and 0.1 for n = 2.
41, n = 3 is 0.28. )

Phenol novolak resin curing agent (softening point 65 ° C., hydroxyl equivalent 105 g / eq) 1.09 parts by weight Fused silica powder (average particle diameter 10 μm, specific surface area 2.0 m ² / g) 35 parts by weight Spherical silica powder ( Average particle size 30 μm, specific surface area 2.5 m ² / g) 50 parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.5 parts by weight Carnauba wax 0.5 parts by weight was mixed at room temperature with a mixer, and mixed at 70-100. The mixture was kneaded with a biaxial roll at ℃, cooled and pulverized to obtain a molding material. The spiral flow of the molding material obtained by pulverization was measured at 175 ° C., 70 kg / cm ² , and 120 seconds using a mold conforming to EMMI-I-66. Further, the obtained molding material is tableted, and a 6 × 6 mm chip is used for a solder crack test at 175 ° C., 70 kg / cm ² , and 120 seconds by a low pressure transfer molding machine.
And a 3 × 6 mm chip was sealed in 16 pSOP for solder moisture resistance test. The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Solder crack test: The sealed test element was subjected to an environment of 85 ° C. and 85% RH for 24 hours and 48 hours.
The treatment was carried out for 72 hours and 120 hours, 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 at 85 ° C, 85
% RH environment for 72 hours, and then immersed in a solder bath at 260 ° C. for 10 seconds, followed by a pressure cooker test (1
(25 ° C., 100% RH), and the open failure of the circuit was measured. Table 1 shows the test results.

Examples 2 to 6 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.

Comparative Examples 1 to 4 Compounded according to the formulation shown in Table 2, 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 2 shows the test results.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

By using the resin composition of the present invention, it is possible to obtain a semiconductor package having excellent solder crack resistance at the time of surface mounting of the semiconductor package and excellent moisture resistance after the solder processing.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI H01L 23/31 (58) Investigated field (Int.Cl. ⁷ , DB name) C08G 59/24 C08G 59/62 C08K 3/00 C08L 63/00-63/10 H01L 23/29

Claims (2)

(57) [Claims] (A) an epoxy resin containing an epoxy compound represented by the following formula (1) in an amount of 30 to 100% by weight based on the total epoxy resin amount: (Wherein R ₁ to R ₄ are a methyl group, R _{5 to} R ₈ are a hydrogen atom,
_9, R ₁₀ is tert-butyl group) (B) phenolic resin curing agent comprising 30-100% by weight based on the total phenolic resin curing agent a phenolic resin curing agent represented by the following formula (2), ## STR2 ## (R in the formula is the same or different atom or group selected from hydrogen, halogens, and alkyl groups having 1 to 5 carbon atoms) (C) Inorganic filler, (D) Hardening accelerator as an essential component Epoxy resin composition for semiconductor encapsulation. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein R in the formula (2) is hydrogen.