JPH01152151A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a sealing epoxy resin composition being resistant to cracking by a stress of soldering heat and having excellent humidity resistance and high reliability, by using a filler containing porous silica powder. CONSTITUTION:This epoxy resin composition comprises an epoxy resin, a curing agent, a cure accelerator and a filler, wherein the filler contains 10-100wt.% silica powder having a means particle diameter of 5-40mu, an apparent density of 0.1-0.6g/cc and a specific surface area of 5-20m<2>/g. This composition is one very excellent in cracking resistance upon being subjected to a thermal stress due to an abrupt change in the temperature of soldering and good in humidity resistance, and it can give a product of a very high reliability when used for sealing, coating, insulation, etc., of an electronic or electrical component, especially, in a high-integration large-scale IC mounted on a surface mounting package.

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 resins. Especially for integrated circuits, O-cresol novolac epoxy resin, which has excellent heat resistance and moisture resistance, is used as a novolac type. Epoxy resin cured with 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 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 compact 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.

In particular, problems have arisen in that moisture resistance deteriorates due to cracking of the package and peeling of the resin and chip due to sudden exposure to high temperatures of 200° C. or higher during the soldering process.

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

(Objective of the Invention) An object of the present invention is to provide a highly reliable sealing resin composition that suppresses the occurrence of cracks due to solder heat stress, has excellent moisture resistance, and has excellent moisture resistance.

(Structure of the Invention) The present invention provides an epoxy resin composition for sealing electronic parts etc. as a filler having an average particle size of 5 to 40 μm and an apparent density of 0.1 to 0.6 g/cc, The present invention also relates to an epoxy resin composition characterized in that porous silica powder having a specific surface area of 5 to 20 m27 g is used in an amount of 10 to 100% by weight of the filler.

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

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.

Further, curing agents include novolak type phenolic resins and modified resins thereof, such as phenol novolak, 0-cresol novolak, and alkyl-modified phenol novolak resins, which may be used alone or in combination of two or more. There is no harm in doing so.

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 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 Diazabicycloundecene (DBU), triphenylphosphine (TPP), dimethylbenzylamine (BDMA), 2methylimidazole (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 4
Porous silica powder having a diameter of 0 μm, an apparent density of 0.1 to 0.6 g/cc, and a specific surface area of 5 to 20 m2/g is used in an amount of 10 to 100% by weight of the amount of filler used. Use within range.

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 are likely to occur due to soldering heat stress, and moisture resistance will decrease, which is undesirable.

Furthermore, if the specific surface area is less than 5 m2/g, cracks are likely to occur during the soldering process, resulting in a decrease in moisture resistance.

Moreover, if it exceeds 20 m2/g, the fluidity will drop significantly, which is not preferable.

Furthermore, if the porous silica powder is less than 10% by weight of the amount of filler used, cracks are 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 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 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 hexabromobenzene, 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.

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 in a mixer or the like, the mixture is further melted and kneaded in a hot roll or kneader, cooled, and then pulverized 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. When used for sealing, 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-cresol novolac epoxy resin (softening point 65°C
, epoxy equivalent 200) 100 parts by weight Phenol novolac resin 50 parts by weight Triphenylphosphine 1 part by weight Antimony trioxide powder 18 parts by weight Carnauba wax
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
B7cc, specific surface area 7 m2/g) 43 parts by weight 3 parts by weight of γ-glycidomethoxysilane were mixed at room temperature with a ribbon blender, kneaded with a twin-screw roll at 70 to 100°C, and after cooling, pulverized to obtain a molding material. .

The obtained molding material was made into tablets, and a 6x6mm chip was sealed in a 52p package for a solder crack test using a low-pressure transfer molding machine at 175°C, 170kg/cm, and 2.120 seconds, and a 3x6mm chip was sealed for a solder moisture resistance test. encapsulate the chip in a 16p SOP package.

The following solder crack test and solder moisture resistance test were conducted on the sealed test device.

Solder crack test: sealed test element at 85℃, 8
24tlr and 48Hr treatment under 51RH 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
Processed for 72 hours in an environment of 5% RH, then immersed in a solder bath at 260°C for 10 seconds, and then subjected to Rescher-Kutsker test (1).
25° C. and 100 $R) 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 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.

Claims (1)

[Claims] 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 40 μm.
, characterized by using a filler containing 10 to 100% by weight of porous silica powder having an apparent density of 0.1 to 0.6 g/cc and a specific surface area of 5 to 20 m^2/g. Epoxy resin composition.