JP2862777B2 - 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 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 and phenol novolak having excellent heat resistance and moisture resistance are provided. An epoxy resin composition containing an inorganic filler such as a 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 sealed in a small and thin package, cracks are generated by thermal 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 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 and 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, an organopolysiloxane containing an epoxy group and a polyether group, which is called a low-stress agent (for example, JP-A-60-13841), is effective for lowering the modulus of elasticity, but at the same time, it has 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 of the molded product at a high temperature 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 resistance to soldering stress of a semiconductor package during mounting is significantly improved.

[0004]

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

[0005]

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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 of the formula (1), and has an epoxy group (glycidyl group or alicyclic epoxy group) and a polycaprolactone group in the molecule. Compared to polyorganosiloxane containing a polyether group, the polycaprolactone group has an excellent heat resistance as an effect and an excellent adhesion to metals such as a lead frame. Therefore, it is possible to obtain an epoxy resin composition which can reduce the thermal stress at the time of soldering the surface device and has excellent solder crack resistance.
When N = l + m + n + 2 is less than 10, the low elasticity and the high strength are reduced, and when N exceeds 200, bleeding occurs during molding and the moldability is greatly impaired. Further, m / N is 0.02
When the m / N is less than 0.02, the reactivity between the organopolysiloxane and the phenol resin is poor, so that the strength particularly when heated is reduced. On the other hand, if it exceeds 0.5, the epoxy group is rich in reactivity, so that the preservability decreases. Further, it is desirable that 0.05 ≦ n / N ≦ 0.4.
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 0.4, the compatibility increases, so that the glass transition temperature is lowered and the low stress effect does not occur. By controlling the amount of the organopolysiloxane used, the solder crack resistance can be maximized. In order to bring out this effect, it is desirable to contain 0.1 to 3.0% by weight in the total epoxy resin composition. 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, dimethylbenzylamine, 2-methylimidazole and the like are used alone or in combination of two or more. As the inorganic filler used in the present invention, fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, alumina and the like,
In particular, spherical silica powder or a mixture of fused silica powder and spherical silica powder is preferable. 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. Additives such as flame-retardant epoxy resins, antimony trioxide, hexabromobenzene, etc., colorants such as carbon black and red bean, and release agents 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, melt-kneading with a hot roll or a kneader, and the like,
After cooling, it can be pulverized into a sealing material. These molding materials can be applied to coating, insulation, sealing, and the like 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 Organopolysiloxane represented by the formula (2)
0.5 parts by weight

[0011]

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3,3 ′, 5,5′-tetramethylbiphenol 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.) 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) 50 parts by weight Part Triphenylphosphine 0.2 part by weight Carbon black 0.5 part by weight Carnauba wax 0.5 part by weight is mixed at room temperature with a mixer, kneaded at 70 to 100 ° C. with a biaxial roll, cooled and ground to form a molding material. And The molding material obtained by the pulverization was used in a test mold for 175 minutes.
The spiral flow was measured at 70 ° C., 70 kg / cm ² and 120 seconds. Further, the obtained molding material is tableted, and 175 ° C., 70 kg by a low pressure transfer molding machine.
/ Cm ² , 120 seconds, a 6 mm × 6 mm chip for solder crack test is sealed in 52pQFP, and a 3 mm × 6 mm chip for solder moisture resistance test is 16
Sealed in pSOP. 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: The sealed test element was treated in an environment of 85 ° C. and 85% RH for 72 hours, and then immersed in a solder bath at 260 ° C. for 10 seconds.
Pressure cooker test (125 ° C, 100% RH)
Was performed, and the open failure of the circuit was measured. The test number was 10 packages, and the time during which half of the packages were defective was defined as the solder moisture resistance average life.

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. Table 1 shows the evaluation results.

Comparative Examples 1 to 7 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 evaluation results. Comparative Example 8 Instead of the organopolysiloxane represented by the formula (2),
Using the following formula (3), the composition was blended according to the formulation in Table 2, and a molding material was obtained in the same manner as in Example 1.

[0016]

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[0017]

[Table 1]

[0018]

[Table 2]

[0019]

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

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ identification symbol FI // (C08L 63/00 83:04) (58) Investigated field (Int.Cl. ⁶ , DB name) C08L 63/00- 63/10 C08G 59/24 H01L 23/29 C08L 83/04-83/08

Claims (2)

(57) [Claims] 1. An epoxy resin, (B) a phenolic 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) a total epoxy resin composition. 0.1-3.0% by weight in the material
Containing an organopolysiloxane of the formula (1) An epoxy resin composition for semiconductor encapsulation, comprising: 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin is 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether.