JPH07107123B2 - 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. on the other hand,
It is also desired to improve fluidity by making the package complicated and increasing the size of the molding die.

[Object of the Invention]

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

[Structure of Invention]

The present invention has an average particle size of 5 to 40 μm, an apparent density of 0.1 to 0.6 g / cc, and a specific surface area of 5 to 10 m ² / g as a filler in an epoxy resin composition for sealing electronic parts and the like, The present invention also relates to an epoxy resin composition characterized by using a filler containing 10 to 100% by weight of the total filler of porous silica powder having a part or all of its surface vitrified.

The epoxy resin composition of the present invention has extremely excellent solder heat stress resistance as compared with the conventional sealing resin composition, and an epoxy resin using a filler containing 10 to 100% by weight of porous silica powder. The composition is improved and the fluidity is greatly improved.

That is, by vitrifying only the surface layer of porous silica, the surface state is approximated to that of ordinary fused silica powder while the internal porous structure is left, and the fluidity is improved while maintaining the solder thermal stress resistance. It is what

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 epoxy groups in its molecule, and it 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 5 to 40.
μm, an apparent density of 0.1 to 0.6 g / cc, a specific surface area of 5 to 10 m ² / g, a part or all of the surface of which is a vitrified porous silica powder, and all fillers to be used. Quantity of 10
Used in the range of up to 100% by weight.

If the average particle size of the surface vitrified porous silica powder is less than 5 μm or exceeds 40 μm, the fluidity cannot be improved, and in any case, it is not preferable. Particularly preferably
It should be 10 to 30 μm. On the other hand, if the apparent density exceeds 0.6 g / cc, cracks are more likely to occur due to solder thermal stress, and the moisture resistance decreases, which is not preferable.

Further, if the specific surface area is less than 5 m ² / g, cracks are likely to occur in the soldering process, and the moisture resistance will decrease. 10m ²
If it is / g or more, the fluidity cannot be improved, which is not preferable.

Furthermore, porous silica powder accounts for 10% by weight of the amount of filler used.
If it is below, 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.

Porous silica powder obtained by vitrifying a part or all of the surface used in the present invention is chemically or physically treated with powder of crystalline silica or fused silica, specifically, dipping with hydrofluoric acid. The surface of the porous silica obtained by performing treatment or plasma treatment is vitrified by melting with a flame, and the vitrification rate can be controlled by the flame atmosphere temperature and the flame treatment time.

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

The epoxy resin composition for encapsulation of the present invention contains an epoxy resin, a curing agent, a curing accelerator, and a filler containing a porous silica powder as essential components, but in addition to this, a silane coupling agent and brominated as necessary. Flame retardants such as epoxy resin, antimony trioxide, and hexabromene benzene, 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 in properly mixing the agent.
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 56 parts by weight brominated bisphenol A epoxy resin (Br content 46%, equivalent 360) 15 parts by weight triphenylphosphine 1 part by weight Antimony trioxide powder 10 parts by weight Carnauba wax 2 parts by weight Carbon black 2 parts by weight Fused silica powder 400 parts by weight Surface vitrified porous silica (average particle size 15 μm, apparent density 0.3 g / cc, specific surface area 6 m ² /
g) 50 parts by weight 3 parts by weight of γ-glycidmethoxysilane are mixed in a Henschel mixer at room temperature, and the mixture is 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 3 All the surface-vitrified porous silica of Example 2 were non-vitrified porous silica, and the rest was the same as in Example 2, and the test results are shown in Table 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09K 3/10 L H01L 23/29 23/31 (56) Reference 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, having an average particle size of 5 to 40 μm, an apparent density of 0.1 to 0.6 g / cc and a specific surface area of 5.
An epoxy resin composition characterized by using a filler containing 10 to 100 m ² / g and containing 10 to 100% by weight of the total amount of the porous silica powder having a part or all of its surface vitrified.