JP3003887B2 - 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 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 have been 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 cured with a phenol resin is used.
However, in recent years, with the increase in the degree of integration of integrated circuits, the size of chips has been increased, the size and size of packages have been reduced, and the surface mounting of mounting methods has been advanced.

In other words, a large chip is enclosed in a small and thin package, and problems such as crack generation due to stress and a decrease in moisture resistance accompanying the stress have been greatly highlighted. Especially in the soldering process, 200
Exposure to a high temperature of not less than ℃ causes a problem that the moisture resistance is deteriorated due to cracking of the package and separation of the resin and the chip. Therefore, development of a sealing resin composition having excellent solder stress resistance and moisture resistance has been desired. In order to alleviate these problems, thermoplastic oligomers (Japanese Patent Application Laid-Open No. 62-15849) and various silicone compounds (Japanese Patent Application Laid-Open No. 62-115850) have been added for the purpose of reducing thermal shock during soldering. , 62-11
Nos. 6654 and 62-128162) and silicone modification (Japanese Patent Application Laid-Open No. 62-136860). However, cracks occur in the package at the time of soldering, resulting in excellent reliability. It did not reach to obtain a semiconductor resin composition.

On the other hand, in order to obtain a heat-resistant epoxy resin composition having excellent solder stress resistance, the use of a polyfunctional epoxy resin as a resin system (Japanese Patent Laid-Open No. 62-168620) has improved heat resistance. It has been considered, but especially 2
When exposed to a high temperature such as 00 to 300 ° C., the solder stress resistance was insufficient.

[0005]

An object of the present invention is to provide a resin composition for semiconductor encapsulation which has excellent solder stress resistance and moisture resistance against such problems.

[0006]

Means for Solving the Problems The present inventors have intensively studied to solve these problems and found a resin composition having the following composition. That is, the present invention relates to (A) 3,3 ′, 5,5′-tetramethyl-
The weight ratio of 4,4′-dihydroxybiphenyl glycidyl ether and 4,4′-dihydroxybiphenyl glycidyl ether represented by the formula (2) is expressed by the formula (1) / formula (2) =
An epoxy resin containing 50 to 100% by weight of an epoxy resin of 1/3 to 3/1 with respect to the total epoxy resin amount,

[0007]

Embedded image

[0008]

Embedded image

(B) As the phenolic resin curing agent, an α-naphthol resin curing agent represented by the formula (3) and / or a β-naphthol resin curing agent represented by the formula (4) are added in an amount of 30 to the total amount of the phenolic resin curing agent. Phenol resin curing agent containing ~ 100% by weight,

[0010]

Embedded image (N = 1-6)

[0011]

Embedded image (N = 1-6)

An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components.

Formula (1) used in the present invention,
The biphenyl type epoxy compound having the structure represented by (2) has a much lower viscosity than conventional epoxy resins.
Therefore, it is possible to greatly increase the content of the filler, improve the impact strength of the resin composition, and show characteristics excellent in solder resistance. The compound of the formula (2) has a higher reactivity with the phenolic hydroxyl group than the compound of the formula (1), but has a drawback of increasing the water absorption, and the formula (1)
/ (2) weight ratio of 1/3 to 3/1, preferably 1 /
By setting the ratio to 1.2 to 1.2 / 1, the characteristics of both compounds can be maximized. If it is out of this range, the characteristics of the two cannot be utilized and the balance is lost. The amount of the epoxy resin used in the formulas (1) and (2) can be adjusted so as to maximize the soldering resistance. Equations (1) and (2) must be used to bring out the effect of soldering stress resistance.
Of the epoxy resin represented by
It is desirable to use 0% by weight or more, more preferably 70% by weight or more. If the amount is less than 50% by weight, the effect of resistance to solder stress cannot be sufficiently brought out. The compound of the formula (1) and the compound of the formula (2) may be used by being mixed in advance by melting or the like, or may be separately added during the production of the resin composition. As the epoxy resin used in combination, general polymers having an epoxy group can be used. For example, a cresol novolak epoxy resin, a phenol novolak epoxy resin, a naphthalene epoxy resin, a trifunctional epoxy resin and the like can be mentioned. These may be used alone or in combination of two or more.

The curing agent represented by the molecular structure of the formula (3) is α
-Naphthol, β-naphthol is used as a curing agent represented by the molecular structure of the formula (4), and aralkyl ethers (α, α '
-Dimethoxyparaxylene) and Friedel-Crafts reaction. This use reduces the elastic modulus around the soldering temperature and improves the adhesion to the lead frame and chip as compared to the conventional phenol novolak resin curing agent, and the naphthalene structure is introduced in the molecule. Thus, low thermal expansion and low water absorption can be obtained. Therefore, it is effective in preventing a reduction in stress generated due to a thermal shock at the time of soldering and a resulting poor adhesion to a chip.

By adjusting the amount of the naphthol resin curing agent used, the solder stress resistance can be maximized. In order to bring out the effect of solder stress resistance, the naphthol resin curing agent represented by the formula (3) and / or (4) is used in an amount of 30% by weight or more, more preferably 50% by weight or more based on the total amount of the curing agent. Is desirable. When the amount is less than 30% by weight, low water absorption, low elasticity, and insufficient adhesion to the lead frame and chip cannot be expected to improve solder stress resistance. Further, n in the equations (3) and (4)
Is desirably from 1 to 6, and if it exceeds 6, the fluidity during transfer molding decreases.

As the curing agent used in combination, any polymer having a phenolic hydroxyl group can be used. For example, phenol novolak resins, cresol novolak resins, dicyclopentadiene-modified phenol resins, copolymers of dicyclopentadiene-modified phenol resins with phenol novolak and cresol novolak resins, para-xylene-modified phenol resins, and the like can be used. These can be used alone or in combination of two or more.

The inorganic filler used in the present invention includes fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, secondary aggregated silica powder or silica obtained by grinding porous silica powder. Powders, alumina and the like can be mentioned, and particularly preferred are fused silica powder, spherical silica powder, and a mixture of fused silica powder and spherical silica powder. In addition, the amount of the inorganic filler is preferably 70 to the total amount of the composition in consideration of the balance between solder stress resistance and moldability.
To 90% by weight.

The curing accelerator used in the present invention may be any as long as it promotes the reaction between the epoxy group and the phenolic hydroxyl group, and those commonly used for sealing materials can be widely used. For example, organic phosphine compounds such as triphenylphosphine (TPP), tributylphosphine and tri (4-methylphenyl) phosphine, tributylamine, triethylamine, dimethylbenzylamine (BDMA), trisdimethylaminomethylphenol, and diazabicycloundecene (DBU) ) And imidazole compounds such as 2-methylimidazole, 2-phenylimidazole and 2-ethyl-4-methylimidazole. These may be used alone or in combination of two or more.

The epoxy resin composition for encapsulation of the present invention comprises an epoxy resin, a curing agent, an inorganic filler and a curing accelerator as essential components. In addition to this, a silane coupling agent and a brominated epoxy resin may be used if necessary. Various additives such as flame retardants such as antimony trioxide and hexabromobenzene, coloring agents such as carbon black and red iron oxide, silicone oils such as natural wax and synthetic wax, and low stress agents such as rubber are appropriately blended. May be. In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, an inorganic filler, a curing accelerator, and other additives are uniformly mixed by a mixer or the like, and then further heated. Alternatively, it can be melt-kneaded in a kneader or the like, 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.

[0020]

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

Example 1 The following composition: An epoxy resin melt mixture represented by the formulas (1) and (2) [formula (1) / formula (2) = 50/50 (weight ratio)] 24.8 parts by weight orthocresol 9. Novolak epoxy resin (softening point 65 ° C., epoxy equivalent 200) 24.8 parts by weight α-naphthol resin curing agent represented by the formula (3) (n is a mixture of 1 to 6, softening point 90 ° C., hydroxyl equivalent 243) 0 parts by weight Phenol novolak resin curing agent (softening point 100 ° C., hydroxyl equivalent: 104) 23.4 parts by weight Fused silica powder 332 parts by weight Triphenylphosphine 0.8 parts by weight Carbon black 2.1 parts by weight Carnauba wax 2.1 parts by weight The parts were mixed at room temperature with a mixer, kneaded at 70 to 100 ° C. with a biaxial roll, cooled and pulverized to obtain a molding material. The resulting molding material was tableted, and a low pressure transfer molding machine was used to test a chip of 6 × 6 mm for solder crack test at 175 ° C., 70 kg / cm ² and 120 seconds for 13.9.
X 13.9 x 2.0 mm package, and a 3 x 6 mm chip for solder moisture resistance test at 7.2 x 11.5
× 2.0 mm. 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 treated in an environment of 85 ° C. and 85% RH for 24 hours and 72 hours, and then immersed in a solder bath at 260 ° C. for 10 seconds. After immersion,
The appearance was observed with a microscope to confirm cracks. Solder moisture resistance test: Sealed test element at 85 ° C, 85
After a treatment for 72 hours in an environment of% RH, it was immersed in a solder bath at 260 ° C. for 10 seconds. After immersion, a pressure cooker test (125 ° C., 100% RH) was performed to measure the open failure of the circuit. Table 1 shows the test results.

Examples 2 to 5 Compounded according to the formulation shown in Table 1, a molding material was obtained in the same manner as in Example 1, and evaluated similarly. Example 6 In place of the α-naphthol resin curing agent represented by the formula (3) in Example 1, a β-naphthol resin curing agent represented by the formula (4) (mixture of n = 1 to 6, softening point 109 ° C., hydroxyl group) Equivalent 2
Using 41), the composition was blended according to the formulation in Table 1, and a molding material was obtained in the same manner as in Example 1 and evaluated in the same manner. Examples 7 to 11 Compounded according to the formulation shown in Table 1, a molding material was obtained in the same manner as in Example 1, and evaluated similarly.

Comparative Examples 1 to 7 Compounded according to the formulation shown in Table 2, a molding material was obtained in the same manner as in Example 1, and evaluated in the same manner.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

According to the present invention, an epoxy resin composition having solder stress resistance, which cannot be obtained by the prior art, can be obtained. When used for encapsulation, coating, and insulation of electronic and electrical components, especially for highly integrated large chip ICs mounted on surface mount packages, because of their excellent crack resistance and excellent moisture resistance Ideal for products with particularly stringent reliability requirements.

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

Claims (1)

(57) [Claims] (A) 3, 3 ', 5;
5′-tetramethyl-4,4′-dihydroxybiphenyl glycidyl ether and 4,4′-
An epoxy resin containing 50 to 100% by weight of an epoxy resin having a weight ratio of dihydroxybiphenyl glycidyl ether of formula (1) / formula (2) = 1/3 to 3/1, based on the total epoxy resin amount; Embedded image (B) As a phenolic resin curing agent, an α-naphthol resin curing agent represented by the formula (3) and / or a β-naphthol resin curing agent represented by the formula (4) are added in an amount of 30 to 100 wt. % Phenolic resin curing agent, embedded image (N = 1 to 6) (N = 1 to 6) An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components.