JPH07107122B2 - Epoxy resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an epoxy resin composition for sealing electronic parts and the like, which is excellent in solder stress resistance.

[Prior art]

Conventionally, electronic parts such as diodes, transistors, and integrated circuits are sealed with thermosetting resin. Especially in integrated circuits, o-cresol novolac epoxy resin, which has excellent heat resistance and moisture resistance, is cured with novolac type phenol resin. The used epoxy resin is used.

However, in recent years, as the integration of integrated circuits has increased, the size of the chip has gradually increased, and the package is a small, thin flat package that has been surface-mounted from the conventional DIP type.
It is changing to P, SOJ, PLCC.

That is, a large chip is to be enclosed in a small and thin package, and problems such as cracks due to stress and deterioration of moisture resistance due to these cracks have been greatly highlighted.

In particular, in the soldering process, when exposed to a high temperature of 200 ° C. or higher, moisture resistance is deteriorated due to cracking of the package and peeling of the chip from the resin.

It has been desired to develop a highly reliable encapsulating resin composition suitable for encapsulating these large chips.

[Object of the Invention]

An object of the present invention is to provide a highly reliable encapsulating resin composition that suppresses cracking due to solder heat stress and has excellent moisture resistance.

[Structure of Invention]

The present invention has an average particle size of 20 to 60 μm, an apparent density of 0.1 to 0.6 g / cc, and a specific surface area of 5 m ² / g or less as a filler in an epoxy resin composition for sealing electronic parts and the like. The present invention relates to an epoxy resin composition comprising a filler containing secondary agglomerated silica powder in an amount of 10 to 100% by weight of the total filler.

The epoxy resin composition of the present invention has very excellent solder heat stress resistance as compared with the conventional encapsulating resin composition.

The epoxy resin used in the present invention is not particularly limited in molecular structure and molecular weight as long as it is a compound having at least two epoxy groups in its molecule, and is generally used as a sealing material, Examples include novolac-based epoxy resins, bisphenol-type aromatic resins, cyclohexane derivative alicyclic resins, polyfunctional resins, and silicone-modified resin resins. These epoxy resins may be used alone or in combination of two or more. To be

Examples of the curing agent include novolac-type phenolic resins and modified resins thereof, such as phenol novolac, o-cresol novolac, and alkyl-modified phenol novolac resins. These are used alone or in combination of two or more. But it doesn't matter.

The compounding ratio of the epoxy resin and the curing agent is preferably such that the equivalent ratio of the epoxy group of the epoxy resin and the hydroxyl group of the curing agent is in the range of 0.5 to 5.

If the equivalence ratio is less than 0.5 or exceeds 5, moisture resistance, molding workability and electrical properties of the cured product deteriorate, which is not preferable.

The curing accelerator used in the present invention may be any one as long as it accelerates the reaction between the epoxy group and the phenolic hydroxyl group, and those generally used for the encapsulating material can be widely used. Bicycloundecene (DBU), triphenylphosphine (TPP), dimethylbenzylamine (BDMA), 2-methylimidazole (2MZ) and the like are used alone or in combination of two or more.

The filler used in the present invention has an average particle size of 20 to 60.
The secondary agglomerated silica powder having a particle size of μm, an apparent density of 0.1 to 0.6 g / cc, and a specific surface area of 5 m ² / g or less is used in the range of 10 to 100% by weight of the total amount of the filler used. .

If the average particle size of the secondary agglomerated silica powder is less than 20 μm, cracks due to solder heat stress are likely to occur, and if it exceeds 60 μm, the formability decreases and in any case,
It is not preferable or preferable that the average particle size is in the range of 20 to 40 μm. If the apparent density exceeds 0.6 g / cc, cracks are likely to occur due to solder heat stress, and the moisture resistance decreases, which is not preferable.

Further, if the specific surface area exceeds 5 m ² / g, cracks are likely to occur in the soldering process, moisture resistance is reduced, and fluidity is greatly reduced, which is not preferable.

Furthermore, if the secondary agglomerated silica powder is 10% by weight or less of the amount of the filler used, cracks are likely to occur in the soldering process, the moisture resistance is lowered, and the intended characteristics cannot be obtained.

These fillers account for 50 to 90% by weight of the resin composition as a whole.
It is desirable to mix them. If the content is less than 50%, the heat resistance, mechanical properties and moisture resistance will be poor, and if it is more than 90%, the fluidity will decrease and the moldability will deteriorate, making it unsuitable for practical use.

The secondary agglomerated silica powder used in the present invention is a particle in which a plurality of primary silica particles are agglomerated and combined, and specifically, for the polymerization reaction of synthetic silica by the so-called sol-gel method by hydrolysis of alkoxysilane. In this case, it can be obtained by adjusting the reaction temperature and the silane monomer concentration. By selecting these conditions, the average particle size and surface area of the secondary agglomerated silica powder can be controlled.

Examples of the filler other than the secondary agglomerated silica powder include ordinary silica powder and alumina, and fused silica powder is particularly preferable.

The encapsulating epoxy resin composition of the present invention contains an epoxy resin, a curing agent, a curing accelerator, and a filler containing a secondary agglomerated silica powder as essential components. Flame retardants such as epoxidized epoxy resin, antimony trioxide and hexabromene, coloring agents such as carbon black and red iron oxide, mold release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber. There is no problem even if additives are properly mixed.
Further, in order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator,
After the filler and other additives are sufficiently and uniformly mixed with a mixer or the like, the mixture can be melt-kneaded with a hot roll or a kneader, cooled, and then pulverized to obtain a molding material. These molding materials can be applied to electronic components or sealing, coating, insulation, etc. of electronic components.

〔The invention's effect〕

Epoxy resin composition of the present invention is very excellent in crack resistance when subjected to thermal stress due to a rapid temperature change in the soldering process, a good moisture resistance composition, electronic, for sealing electronic components, When used for coating, insulation, etc., it is possible to obtain a highly reliable product, especially in a highly integrated large chip IC mounted in a surface mount package.

〔Example〕

Example 1 o-cresol novolac epoxy resin (softening point 65 ° C., epoxy equivalent 200) 100 parts by weight phenol novolac resin 55 parts by weight Br-bisphenol A epoxy (Br content 46% by weight, equivalent 360) 10 parts by weight triphenylphosphine 1 Parts by weight antimony trioxide powder 12 parts by weight carnauba wax 2 parts by weight carbon black 2 parts by weight fused silica powder 400 parts by weight secondary agglomerated silica powder (average particle size 35 μm, apparent density 0.3 g
/ cc, specific surface area 3 m ² / g) 50 parts by weight 3 parts by weight of γ-glycidmethoxysilane are mixed with a Henschel mixer at room temperature, and then mixed at 70-100 ° C for 2 hours.
The mixture was kneaded with a shaft roll, cooled, and then ground to obtain a molding material.

The obtained molding material is made into a tablet, and a 6 x 6 mm chip is sealed in a 52p package for solder crack testing under conditions of 175 ° C, 70 kg / cm ² and 120 seconds using a low-pressure transfer molding machine, and solder moisture resistance. 16p 3x6mm chip for testing
Sealed in SOP package.

The sealed test element was post-cured at 175 ° C. for 8 hours and then subjected to the following solder crack test and solder moisture resistance test.

Solder crack test: sealed test element at 85 ℃, 85%
After 24 hours and 48 hours of treatment in an RH environment, after immersing in a solder bath at 260 ° C for 10 seconds, external cracks were observed with a microscope.

Solder moisture resistance test: sealed test element at 85 ℃, 85% RH
72Hr treatment under the environment of, and then immersed in a solder bath at 260 ° C for 10 seconds, and then subjected to a pressure cooker test (125 ° C, 100% RH) to measure the open circuit failure.

The test results are shown in Table 1.

Examples 2 to 4 Compounding was carried out according to the formulation shown in Table 1, a molding material was obtained in the same manner as in Example 1, and a molding material for testing was 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 performed.

The test results are shown in Table 1.

Comparative Example 1 Table 1 shows the results of tests conducted in the same manner as in Example 1 except that the filler in Example 1 was all fused silica.

Comparative Example 2 All the fillers in Example 4 were fused silica, and the rest was the same as in Example 4, and the results of the tests were shown in Table 1.

Comparative Example 2 All the fillers in Example 4 were fused silica, and the rest was the same as in Example 4, and the results of the tests were shown in Table 1.

Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI Technical location C09K 3/10 L H01L 23/29 23/31 (56) References JP-A-63-159422 (JP, A) JP 62-149743 (JP, A) JP 62-153337 (JP, A) JP 62-161851 (JP, A) JP 61-283615 (JP, A) JP 61-143466 (JP, A) JP-A-53-21298 (JP, A) JP-A-52-130852 (JP, A)

Claims (1)

[Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent, a curing accelerator and a filler, wherein the average particle size is
It is characterized by using a filler containing 20 to 60 μm, an apparent density of 0.1 to 0.6 g / cc, and a secondary agglomerated silica powder having a specific surface area of 5 m ² / g or less, in an amount of 10 to 100% by weight of the total filler. And an epoxy resin composition.