JPH0588904B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to an epoxy resin composition for sealing electronic components and the like, which has excellent solder stress resistance. (Prior art) Conventionally, electronic components such as diodes, transistors, and integrated circuits have been encapsulated with thermosetting resin, but especially for integrated circuits, o-cresol novolac epoxy resin, which has excellent heat resistance and moisture resistance, has been encapsulated. Epoxy resin cured with type phenolic resin is used. However, in recent years, as integrated circuits have become more highly integrated, chips have become larger and larger, and packages have become smaller than conventional ones.
The DIP type has been replaced by small, thin, surface-mounted flat packages, SOP, SOJ, and PLCC. That is, a large chip is enclosed in a small and thin package, and problems such as the occurrence of cracks due to stress and a decrease in moisture resistance due to these cracks are becoming more and more important. Particularly in the soldering process, rapid exposure to high temperatures of 200°C or higher has caused problems such as cracking of the package and deterioration of moisture resistance due to peeling of the resin and chip. It has been desired to develop a highly reliable encapsulating resin composition suitable for encapsulating these large chips. (Objective of the Invention) An object of the present invention is to provide a highly reliable sealing resin composition which suppresses the occurrence of cracks due to soldering heat stress and has excellent moisture resistance. (Structure of the Invention) The present invention provides an epoxy resin composition comprising an epoxy resin, a curing agent, a curing accelerator, and a filler.
The total composition contains 50 to 90% by weight of filler, and the filling has an average particle size of 5 to 40 μm and an apparent density of 0.1 to 0.6.
The present invention relates to an epoxy resin composition characterized by containing 10 to 100% by weight of porous silica powder having a specific surface area of 5 to 20 m ² /g. The epoxy resin composition of the present invention has extremely superior solder heat stress resistance compared to conventional sealing resin compositions. The epoxy resin used in the present invention is not particularly limited in molecular structure, molecular weight, etc. as long as it is a compound having at least two or more epoxy groups in its molecule, and is generally used as a sealing material. For example, novolak epoxy resin,
Examples include bisphenol type aromatic type, alicyclic type of cyclohexane derivative, polyfunctional type, and silicone modified resin type, and these epoxy resins may be used alone or in combination of two or more types. The curing agent may be a novolak type phenolic resin or a modified resin thereof, such as phenol novolak, o-cresol novolak, or alkyl-modified phenol novolak resin, which may be used alone or in combination of two or more. There is no problem in using it. The compounding ratio of the epoxy resin and the curing agent is that the equivalent ratio of the epoxy group of the epoxy resin to the hydroxyl group of the curing agent is 0.5.
It is desirable that it be within the range of ~5. If the equivalence ratio is less than 0.5 or more than 5, it is moisture resistant.
This is not preferable because it deteriorates molding workability and the electrical properties of the cured product. The curing accelerator used in the present invention may be one that promotes the reaction between epoxy groups and phenolic hydroxyl groups, and a wide variety of those commonly used in sealing materials can be used, such as diaza. Bicycloudecene (DBU), triphenylphosphine (TPP), dimethylbenzylamine (BDMA), 2methylimidazole (2MZ), etc. are used alone or in combination of two or more. The filler used in the present invention has an average particle size of 5 to 40 μm and an apparent density of 0.1 to 0.6 g/cc.
A porous silica powder having a specific surface area of 5 to 20 m ² /g is used in an amount of 10 to 100% by weight of the filler used. If the average particle size of the porous silica powder is less than 5 μm or more than 40 μm, the fluidity will decrease, and either case is not preferable. Moreover, if the apparent density exceeds 0.6 g/cc, cracks due to soldering heat stress are likely to occur, and moisture resistance will decrease, which is undesirable. Further, if the specific surface area is less than 5 m ² /g, cracks are likely to occur during the soldering process and moisture resistance will be reduced. Moreover, if it exceeds 20 m ² /g, the fluidity will drop significantly, which is not preferable. In addition, porous silica powder can reduce the amount of filler used.
If it is less than 10% by weight, cracks tend to occur during the soldering process, moisture resistance decreases, and the desired characteristics cannot be obtained. These fillers collectively account for 50 to 50% of the resin composition.
It is desirable to mix 90% by weight. Its blending amount is 50
If it is less than 90%, the heat resistance, mechanical properties and moisture resistance will be poor, and if it is more than 90%, the fluidity will be reduced and the moldability will be poor, making it unsuitable for practical use. In addition, examples of fillers other than porous silica powder include ordinary silica powder and alumina, with fused silica powder being particularly preferred. The epoxy resin composition for sealing of the present invention contains an epoxy resin, a curing agent, a curing accelerator, and a porous silica powder filler as essential components. , flame retardants such as antimony trioxide and hexabrombenzene, colorants such as carbon black and red iron, mold release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber. There is no problem in appropriately blending them. Furthermore, in order to produce the epoxy resin composition for sealing of the present invention as a molding material, the epoxy resin, curing agent, curing accelerator, filler, and other additives are thoroughly and uniformly mixed using a mixer or the like. Thereafter, the mixture is further melt-kneaded using a hot roll or a kneader, cooled, and then crushed to obtain a molding material. These molding materials can be applied to sealing, covering, insulating, etc. electronic or electrical components. (Effects of the Invention) The epoxy resin composition of the present invention has excellent crack resistance when subjected to heat stress due to sudden temperature changes during the soldering process, and is a composition with good moisture resistance. For sealing, coating,
When used for insulation purposes, products with extremely high reliability can be obtained, especially in highly integrated large chip ICs mounted on surface mount packages. (Example) Example 1 o-Cresol novolak epoxy resin (softening point 65°C, epoxy equivalent 200) 100 parts by weight Phenol novolak resin 50 parts by weight Triphenylphosphine 1 part by weight Antimony trioxide powder 18 parts by weight Carnauba wax Tuxus 2 parts by weight Carbon black 2 parts by weight Fused silica powder 328 parts by weight Porous silica powder (average particle size 15 μm, apparent density 0.3 g/cc, specific surface area 7 m ² /g) 43 parts by weight γ-glycidomethoxysilane 3 parts by weight Mix the parts with a ribbon blender at room temperature and heat to 70-100℃.
The mixture was kneaded using twin-screw rolls, cooled, and then ground to obtain a molding material. The obtained molding material was made into a tablet, and a 6 x 6 mm chip was sealed in a 52p package for a solder crack test using a low-pressure transfer molding machine at 175°C, 70 kg/cm ² and 120 seconds, and solder moisture resistant. A 3 x 6 mm chip was sealed in a 16 pSOP package for performance testing. After post-curing the sealed test device at 175° C. for 8 hours, the following solder crack test and solder moisture resistance test were conducted. Solder crack test: 85 times the sealed test element
℃, 24Hr and 48Hr treatment under 85%RH environment,
After that, it was immersed in a solder bath at 260°C for 10 seconds, and external cracks were observed using a microscope. Solder moisture resistance test: 85 times the sealed test element
℃, 72Hr treatment under 85%RH environment, then 260℃
After being immersed in a solder bath at ℃ for 10 seconds, a pressure vacuum test (125℃, 100% RH) was performed to measure open defects in the circuit. The test results are shown in Table 1. Examples 2 to 4 Molding materials were obtained in the same manner as in Example 1 by blending according to the formulations in Table 1, and sealed products for testing were obtained with this molding material. Using this molding material, a test element was sealed in the same manner as in Example 1, and a solder crack test and a solder moisture resistance test were conducted. The test results are shown in Table 1. Comparative Example 1 In Example 1, all the fillers were fused silica.

【table】

[Table] Table 1 shows the results of a test conducted in the same manner as in Example 1 except for the following. Comparative Example 2 The filler in Example 4 was all fused silica, the rest was carried out in the same manner as in Example 4, and the results of the test were shown in the first example.
Shown in the table.

Claims (1)

[Claims] 1. In an epoxy resin composition consisting of an epoxy resin, a curing agent, a curing accelerator, and a filler, the total composition contains 50 to 90% by weight of the filler, and the filler has an average particle size of 5 to 40 μm and an apparent Density 0.1~0.6g/cc
An epoxy resin composition comprising 10 to 100% by weight of porous silica powder having a specific surface area of 5 to 20 m ² /g.