JPH01236263A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin 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 novolac) and a cure accelerator (C) (e.g., diazabicycloundecene) in an equivalent ratio of the epoxy groups of component A to the hydroxyl groups of component B of 0.5-5, and the obtained mixture is further mixed with 50-90wt.% filler (D) containing 10-100wt.% secondary agglomerates of silica powder of a mean particle diameter of 20-60mum, an apparent density of 0.1-0.6g/cc and a specific surface area <=5m<3>/g.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an epoxy resin composition for use with soil, such as electronic parts, 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 enclosed in a small and thin package, and problems such as the occurrence of cranks due to stress and a decrease in moisture resistance due to these cracks have been brought into focus.

In particular, problems have arisen in the soldering process where exposure to extremely high temperatures of 200"C or higher can cause cracks in 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.

[Purpose of the invention]

An object of the present invention is to provide a sealing resin composition that suppresses the occurrence of cracks due to soldering heat stress, has excellent moisture resistance, and has high reliability.

[Structure of the invention]

The present invention is used as a filler in an epoxy resin composition for soil use in electronic parts, etc., which has an average particle size of 20 to 60 μm, an apparent density of o,t to 0.6 g/cc, and a specific surface area of 3 The present invention relates to an epoxy resin composition characterized in that it uses a filler containing 10 to 100 weight percent of secondary agglomerated silica powder having a rd/g or less.

The epoxy resin composition of the present invention has extremely superior soldering heat stress resistance compared to conventional sealing resin compositions.

As long as the epoxy resin used in the present invention is a compound having at least two or more epoxy groups in its molecule, there are no particular restrictions on the molecular structure, molecular weight, etc., and the epoxy resin 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 novolac 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 one that promotes the reaction between the epoxy group and the phenolic hydroxyl group, and a wide variety of those commonly used in sealing materials can be used, such as diaphragm. Zabishikuroundesen (DBU),
Triphenylphosphine (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 20 to
60μ precision, and the apparent density is 0.1-0.6g/
cc and a specific surface area of 5 nf/g or less, 10 to 100% by weight of the amount of filler used.
Use within the range.

If the average particle size of the secondary agglomerated silica powder is less than 20 μm, cracks are likely to occur due to soldering heat stress, and if it exceeds 60 μm, the moldability decreases, and in either case, it is not preferable or preferably. , average particle size is 20-40
It is fine as long as it is in the μm range, and the apparent density is 0.6 g/
If it exceeds cc, cranking due to soldering heat stress tends to occur, and moisture resistance decreases, which is not preferable.

Furthermore, if the specific surface area exceeds 5n (7g), cracks are likely to occur during the soldering process, moisture resistance is reduced, and fluidity is significantly reduced, which is not preferable.

Further, if the secondary agglomerated 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 moisture resistance 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 secondary agglomerated 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 contains an epoxy resin, a curing agent, a curing accelerator, and a filler containing secondary agglomerated silica powder as essential components. Various additives such as flame retardants such as Epoquin resin, antimony dioxide, and hexaprombenzene, 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 even if the agent is appropriately blended.

In addition, in order to produce the epoxy resin composition for sealing 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 sudden 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 a product with very high credibility.

〔Example〕

Example 1 0-talesol 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 146% by weight, 1360) 10 parts by weight Triphenylphosphine II (1 part antimony dioxide powder 1) Part by weight Carnauba wax 2 Parts by weight Carbon black 2 parts by weight Fused silica powder
400 parts by weight of secondary agglomerated silica powder (average particle size 35μ, apparent density 0.3 g/cc, specific surface area 3 bo/g) 50 parts by weight γ-glycidomethoxysilane 3 parts by weight were mixed at room temperature in a Henschel mixer. Mix at 70~t o '
The mixture was kneaded using a twin-screw roll at step c, cooled, and then ground to obtain a molding material.

The obtained molding material was made into tablets and molded using a low-pressure transfer molding machine at 175°C, 70 kg/ca, 1)0
A 6 x 6 plate chip was sealed in a 52P package for a solder crank test under conditions of 10 seconds, and a 3 x 6 plate chip was sealed in a 16p SOP package for a solder ambidextrous test.

After post-curing the sealed test device at 175° C. for 18 hours, the following solder crack test and solder moisture resistance test were conducted.

Solder crank test: sealed test element at 85°C1
Treated for 24 hours and 48 hours in an environment of 85% RH,
Thereafter, the external crank was immersed in a solder bath at 260° C. for 10 seconds, and then observed under a microscope.

Solder moisture resistance test: sealed test element at 85°C18
72) 1r treatment in an environment of 5% RH, then 260
Pressure cool after immersing in 'C' solder bath for 10 seconds/h-
Test (1) (5°C, 100% RH) was conducted 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 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 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.

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 20 to
It is characterized by using a filler containing 10 to 100% by weight of secondary agglomerated silica powder having a diameter of 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. Epoxy resin composition.