JP3334998B2 - 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 moisture resistance and solder 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, an ortho-cresol novolac epoxy resin and a phenol having excellent heat resistance and moisture resistance are provided. An epoxy resin composition containing an inorganic filler such as a novolak resin, fused silica, or crystalline silica has been used. However, in recent years,
Chips have become larger and larger with the increasing integration of integrated circuits.
And the package is small and thin QFP, SOP, SOJ, TSOP, surface-mounted from the conventional DIP type,
It is changing to TQFP and PLCC. That is, a large chip is enclosed in a small and thin package, cracks are generated by thermal stress, and problems such as a decrease in moisture resistance due to these cracks have been 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, development of a highly reliable semiconductor sealing resin composition suitable for sealing these large chips is desired. To improve these,
Techniques such as low elastic modulus, low thermal expansion coefficient, high impact strength, and low water absorption are used. Among these, organopolysiloxanes containing an epoxy group and a polyether group, which are called low-stress agents (for example, JP-A-60-13841), are effective in lowering the modulus of elasticity, but at the same time, they have poor adhesion and strength. As a result, the solder heat resistance decreased, and a good resin composition for encapsulating a semiconductor could not be obtained.

[0003]

SUMMARY OF THE INVENTION In order to solve such problems, the present invention contains 70 to 90% by weight of an inorganic filler in the total epoxy resin composition to reduce the thermal expansion of molded articles and to reduce the thermal expansion of molded articles. By using the organopolysiloxane represented by the formula (1) to absorb water and reduce the stress by lowering the modulus of elasticity in high-temperature moisture absorption of the molded product without impairing the adhesion to the lead frame and the semiconductor chip, An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation in which the moisture resistance and solder stress resistance of a semiconductor package during mounting are significantly improved.

[0004]

The present invention relates to (A) an epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, and (D) 70 to 90% by weight of the total epoxy resin composition.
(E) an organopolysiloxane of the formula (1) containing 0.1 to 3.0% by weight of the total epoxy resin composition

[0004]

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An epoxy resin composition for semiconductor encapsulation comprising a solder stress resistance and a moisture resistance after soldering as superior reliability as compared with the conventional epoxy resin composition.

The organopolysiloxane used in the present invention is represented by the molecular structure represented by the formula (1), which has a polycaprolactone group in the molecule, and is different from a conventional organopolysiloxane containing an epoxy group and a polyether group. As a result of the polycaprolactone group, it has excellent heat resistance and excellent adhesion to metals such as lead frames. Therefore, it is possible to obtain an epoxy resin composition which can reduce thermal stress during soldering of the surface device, has excellent solder crack resistance, and has excellent moisture resistance. N in the formula is 10 ≦ N = 1 + n +
2 ≦ 50, but if it is less than 10, low elasticity and high strength are reduced, and if N exceeds 50, it bleeds during molding and the moldability is greatly impaired. Further, 0.05 ≦ n / N ≦
It is preferably 0.8. When n / N is less than 0.05, the compatibility with the epoxy resin or the phenol resin is deteriorated, so that the resin tends to bleed during molding. On the other hand, if n / N exceeds 0.8, the compatibility increases, so that the glass transition temperature is lowered and the low stress effect is not produced. R is carbon number 1
To 8 alkylene groups, preferably having 1 to 4 carbon atoms.
It is. a is 1 or more, and preferably 1 to 5. Further, R ₁ and R ₂ are as shown in the formula (1), and preferred R ₁ is a methyl group. By adjusting the amount of the organopolysiloxane used, moisture resistance and solder crack resistance can be maximized. In order to bring out this effect, 0.1 to 0.1%
It is preferred to contain 3.0% by weight. If it is less than 0.1% by weight, a low stress effect cannot be expected, and the solder crack resistance is reduced. On the other hand, if the content exceeds 3.0% by weight, the resin and the lead frame bleed at the time of molding to lower the adhesion and the solder crack resistance.

The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having an epoxy group.
For example, biphenyl type epoxy compound, naphthalene type epoxy compound, bisphenol type epoxy compound, phenol novolak type epoxy resin, cresol novolak type epoxy resin, triphenolmethane type epoxy compound, alkyl-modified triphenolmethane type epoxy compound and epoxy resin containing triazine nucleus And the like. As the phenolic resin curing agent used in the present invention, phenol novolak resin, cresol novolak resin,
Examples thereof include a dicyclopentadiene-modified phenol resin, a terpene-modified phenol resin, and a triphenolmethane compound. Particularly, a phenol novolak resin, a dicyclopentadiene-modified phenol resin, a paraxylylene-modified phenol resin, a terpene-modified phenol resin, and a mixture thereof are preferable. The amount of the curing agent is preferably such that the number of epoxy groups in the epoxy compound is equal to the number of hydroxyl groups in the curing agent.

The curing accelerator used in the present invention may be any one which promotes the curing reaction between an epoxy group and a hydroxyl group, and those generally used for a sealing material can be widely used. For example, diazabicycloundecene, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like are used alone or in combination of two or more. Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, alumina and the like, particularly spherical silica powder, or fused silica powder and spherical silica powder. Mixtures with silica powder are preferred. The amount of the inorganic filler is preferably 70 to 90% by weight, more preferably 78 to 88% by weight in the total epoxy resin composition in view of the balance between solder crack resistance, moldability and fluidity. When the amount of the inorganic filler is less than 70% 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 epoxy resin composition of the present invention contains an epoxy resin, a phenolic resin curing agent, a curing accelerator, an inorganic filler and an organopolysiloxane as essential components. Various additives such as a flame retardant such as fluorinated epoxy resin, antimony trioxide and hexabromobenzene, a colorant such as carbon black and red iron oxide, and a release agent such as natural wax and synthetic wax can be appropriately compounded. . Further, in order to produce the sealing epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator, an inorganic filler,
After sufficiently mixing other additives with a mixer or the like, the mixture is further melt-kneaded with a hot roll or a kneader, cooled, and pulverized to obtain a molding material. These molding materials can be applied to covering, insulating, sealing, etc. of transistors and integrated circuits, which are electric or electronic components.

Hereinafter, the present invention will be described specifically with reference to examples. Example 1 0.5 parts by weight of an organopolysiloxane represented by the formula (2)

[0011]

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3,3 ′, 5,5′-tetramethylbisphenol diglycidyl ether (melting point: 104 ° C., epoxy equivalent: 191 g / eq) 10.2 parts by weight Phenol novolak resin curing agent (softening point: 94 ° C., hydroxyl equivalent: 105 g) / Eq) 5.6 parts by weight Fused silica powder (average particle size 10 μm, specific surface area 2.0 m ² / g) 34.5 parts by weight Spherical silica powder (average particle size 30 μm, specific surface area 2.0 m ² / g) 48 Parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.5 parts by weight Carnauba wax 0.5 parts by weight is mixed at room temperature with a mixer, kneaded at 70-100 ° C with a biaxial roll, cooled and ground to form. 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 chip of 6 mm × 6 mm is used for a solder crack test at 175 ° C., 70 kg / cm ₂ and 120 seconds by a low-pressure transfer molding machine at 52 pQ.
Sealed in FP and 3mm x 6 for solder moisture resistance test
mm chips were sealed in 16pSOP. The sealed test element was subjected to the following solder crack test and solder moisture resistance test. Table 1 shows the evaluation results.

Solder crack test: The sealed test element was treated in an environment of 85 ° C. and 85 RH for 24 hours and 48 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.

Examples 2 to 4 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. The evaluation results are shown in Table 1.

Comparative Examples 1 to 8 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. The following formula was used as the organopolysiloxane used in Comparative Example 8. Table 2 shows the evaluation results.

[0016]

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[0017]

[Table 1]

[0018]

[Table 2]

[0019]

According to the present invention, the moldability and moisture resistance of a semiconductor package during mounting on a substrate are significantly improved, and the semiconductor package is excellent in solder stress resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // (C08L 63/00 H01L 23/30 R 83:06) (56) References JP-A-7-126490 (JP, A) JP-A-2-173155 (JP, A) JP-A-3-97719 (JP, A) JP-A-7-258312 (JP, A) JP-A-5-339511 (JP, A) JP-A-6-228275 (JP, A) JP-A-3-174744 (JP, A) JP-A-4-363316 (JP, A) JP-A-4-372660 (JP, A) JP-A-6-287306 (JP, A) Kaihei 4-145129 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 63/00-63/10 C08K 9/06 H01L 23/29 C08L 83/06

Claims (3)

(57) [Claims] 1. An epoxy resin, (B) a phenol resin curing agent, (C) a curing accelerator, (D) an inorganic filler containing 70 to 90% by weight of the total epoxy resin composition, and (E)
Organopolysiloxane of the formula (1) containing 0.1 to 3.0% by weight in the total epoxy resin composition An epoxy resin composition for semiconductor encapsulation, comprising: 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein R ₁ is a methyl group. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin is 3,3 ′, 5,5′-tetramethylbisphenol diglycidyl ether.