JPH01236264A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition prevented from being cracked by a soldering stress and improved in heat resistance, by mixing an epoxy resin with a curing agent, a cure accelerator and a specified filler. CONSTITUTION:An epoxy resin (A) is mixed with a curing agent (B) (e.g., phenol novolak), a cure accelerator (C) (e.g., diazabicycloundecene) in such an amount that the equivalent ratio of the epoxy groups of component A to the hydroxyl groups of component B is 0.5-5, and the obtained mixture is mixed with 50-90wt.% filler containing 10-100wt.% porous silica powder having a partially vitrified surface, a mean particle diameter of 5-40mum, an apparent density of 0.1-0.6g/cc and a specific surface area of 5-10m<2>/g.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an epoxy resin composition for sealing electronic parts and the like, which has excellent solder stress resistance.

[Prior art]

Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with thermosetting resins, but especially for integrated circuits, 0-talesol novolac epoxy resin, which has excellent heat resistance and moisture resistance, is used as a novolac type phenolic resin. A hardened epoxy resin is used.

However, in recent years, as integrated circuits have become more highly integrated, chips have become larger and larger, and packages have changed from the conventional DIP type to surface-mounted small, thin flat packages.
It is changing to SOP, SOJ, and PLCC.

That is, a large chip is encapsulated 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 have been brought into focus.

Particularly in the soldering process, rapid exposure to high temperatures of 200° C. or higher has led to 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 sealing resin composition with high reliability that is suitable for sealing these large chips. on the other hand,
It is also desired to improve fluidity by making packages more complex in shape and making molds larger.

[Purpose of the invention]

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

[Structure of the invention]

The present invention is a filler in an epoxy resin composition for sealing electronic parts, etc., which 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.
The present invention relates to an epoxy resin composition characterized in that it uses a filler containing 10 to 100% by weight of porous silica powder whose surface is partially or entirely vitrified.

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

In other words, by vitrifying only the surface layer of porous silica, the internal porous structure remains and the surface condition approaches that of normal fused silica powder, improving fluidity while maintaining soldering heat stress resistance. That is.

The epoxy resin used in the present invention is not particularly limited in molecular structure or molecular weight 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. Examples include novolac epoxy resins, bisphenol-type aromatic resins, alicyclic cyclohexane derivatives, polyfunctional resins, and silicone-modified resins. These epoxy resins can be used singly or in combination of two or more. It will be done.

Curing agents include novolak type phenolic resins and modified resins thereof, such as phenol novolak, 0-talesol novolak, and alkyl-modified phenol novolac resins, which may be used alone or in combination of two or more. There is no problem in using it.

As for the compounding ratio of the epoxy resin and the curing agent, it is desirable that the equivalent ratio of the epoxy groups of the epoxy resin to the hydroxyl groups of the curing agent be within the range of 0.5 to 5.

If the equivalent ratio is less than 0.5 or more than 5, the moisture resistance, molding workability and electrical properties of the cured product will deteriorate, which is not preferred.

The curing accelerator used in the present invention may be any one as long as it promotes the reaction between the epoxy group and the phenolic hydroxyl group. Zabishikuroundesen (DBU),
) Rivenylphosphine (TPP), dimethylbenzylamine (BDMA) and 2methylimidazole (2MZ)
etc. may be used alone or in combination of two or more.

The filler used in the present invention has an average particle size of 5 to 4
0 μm, and the apparent density is 0.1 to 0.6 g/c
It is a porous silica powder with a specific surface area of c and a specific surface area of 5 to 10 r+f/g, with part or all of the surface vitrified, and is used in an amount of 10 to 100% by weight of the amount of filler used.

Porous silica powder with a vitrified surface cannot improve fluidity if its average particle size is less than 5 μm or exceeds 40 pm, which is undesirable in either case, and particularly preferably from 10 to 30 μm. It's fine, and the apparent density is 0.
If it exceeds 6 g/cc, cracks are likely to occur due to soldering heat stress, and moisture resistance decreases, which is undesirable.

Furthermore, the specific surface area is 5n'? If it is less than /g, cranks are likely to occur during the soldering process and moisture resistance will decrease.
Moreover, if it exceeds 10 mm2/g, no improvement in fluidity can be obtained, which is not preferable.

Further, if the porous silica powder is less than 10% by weight of the amount of filler used, cranking is likely to occur during the soldering process, moisture resistance is reduced, and the desired characteristics cannot be obtained.

It is desirable that these fillers be blended in an amount of 50 to 90% by weight of the resin composition as a whole.If the blending amount is less than 50%, heat resistance, mechanical properties, and humidity will be poor;
If it is more than that, the fluidity will decrease and the moldability will deteriorate, 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 soil use of the present invention has an epoxy resin, a curing agent, a curing accelerator, and a filler containing porous silica powder as essential components, but in addition to these, if necessary, a silane coupling agent, a bromine, etc. Flame retardants such as chemically modified epoxy resins, antimony dioxide and hexabromobenzene, colorants such as carbon black and red iron, mold release agents such as natural waxes and synthetic waxes, and low stress additives such as silicone oil and rubber. There is no problem in adding appropriate additives.

In addition, in order to produce the epoxy resin composition for soil use of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator,
After the filler and other additives are thoroughly and uniformly mixed using a mixer or the like, the mixture can be further melt-kneaded using a heated roll or kneader, cooled, and then ground to obtain a molding material. These molding materials can be applied to electronic parts or for sealing, covering, insulating, etc. of electronic parts.

〔Effect of the invention〕

The epoxy resin composition of the present invention has excellent crack resistance when subjected to heat stress due to rapid temperature changes during the soldering process, and has good moisture resistance. When used for coating, insulation, etc., especially for highly integrated large chip ICs mounted on surface mount packages.
It is possible to obtain products with extremely high reliability.

〔Example〕

Example 1 0-talesol novolac epoxy resin (softening point 65°C
, epoxy equivalent 200) 100 parts by weight phenol novolac resin 56 heavy precious brominated bisphenol A epoxy resin (Br content 46%,
1360) 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 15μ theory, apparent density 0.3 g/cc, specific surface area 6 po/g 50 parts by weight T-glycidomethoxysilane 3 parts by weight 1 part at room temperature with a Henschel mixer, and 2 parts at 70-100°C.
The mixture was kneaded using an axial roll, cooled, and then ground to obtain a molding material.

The obtained molding material was made into tablets and heated at 175°C and 70 kg/eta using a low-pressure transfer molding machine.

A 6×6m chip was sealed in a 52p package for a solder crank test under conditions of 120 seconds, and a 3×6m chip was sealed in a 16p SOP package for a solder moisture resistance test.

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: sealed test element at 85℃, 8
2411r and 48Hr treatment under 5% RH environment,
Thereafter, 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: sealed test element at 85°C18
Treated for 72 hours in an environment of 5%R)l, then heated at 260°
After being immersed in a solder bath of C for 10 seconds, a pressure puller test (125°C, 100% RH) was conducted to measure open circuit defects.

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 crank test and a solder moisture resistance test were conducted.

The test results are shown in Table 1.

Comparative Example 1 Table 1 shows the results of a test conducted in the same manner as in Example 1 except that all the fillers were replaced with fused silica.

Comparative Example 2 A test was conducted in the same manner as in Example 4 except that all the fillers in Example 4 were fused silica. Table 1 shows the results.

Comparative Example 3 Example 20 All of the surface vitrified porous silica was replaced with non-vitrified porous silica, and the rest was carried out in the same manner as in Example 2. Table 1 shows the results of the test.

Claims (1)

[Claims] (1) In an epoxy resin composition consisting of an epoxy resin, a curing agent, a curing accelerator, and a filler, the average particle size is 5 to 4.
0 μm, an apparent density of 0.1 to 0.6 g/cc, a specific surface area of 5 to 10 mm^2/g, and contains 10 to 100% by weight of porous silica powder whose surface is partially or entirely vitrified. An epoxy resin composition characterized by using a filler.