KR100565421B1 - Epoxy molding composition for semiconductor encapsulant - Google Patents

Abstract

The present invention

(1) 3.5 to 7.0% by weight of a naphthalene epoxy resin of the following formula (2),

(2) 3.5-7.0% by weight of at least one novolac-based curing agent selected from the group consisting of conventional phenol noblock resins, xylox resins, dicyclopentadiene resins having two or more hydroxyl groups and a hydroxyl group equivalent of 100-200,

(3) 0.1-0.3% by weight curing accelerator and

(4) 88-92% by weight of inorganic filler

The present invention relates to an epoxy resin composition for sealing a semiconductor element, which is excellent in crack resistance against high temperature, low heat deformation at high temperature, and excellent adhesion to a lead frame, and thus is useful as an epoxy resin composition for semiconductor element sealing.

[Formula 2]

(Wherein R is hydrogen or CH ₃ )

Naphthalene type epoxy resin composition, novolak-type hardening | curing agent, a hardening accelerator, an inorganic filler, crack resistance, adhesiveness

Description

Epoxy resin composition for semiconductor element sealing {EPOXY MOLDING COMPOSITION FOR SEMICONDUCTOR ENCAPSULANT}

The present invention is an epoxy resin for sealing semiconductor elements excellent in high temperature crack resistance, low thermal deformation at high temperature, and excellent adhesion to a lead frame or a printed circuit board (PCB). The present invention relates to an epoxy resin composition for sealing semiconductor elements, which comprises a crystalline naphthalene epoxy resin, a novolac curing agent, a curing accelerator, and an inorganic filler in more detail.

Recently, as interest in environmental pollution has increased, attention has been focused on methods for minimizing environmental pollution in semiconductor assembly processes. Therefore, there is a demand for a semiconductor sealing material that does not contain halogen-based substances or antimony, which are harmful to human body, and a new leadframe plating technology using a plating solution containing no lead component is developed in the semiconductor plating process. In the semiconductor mounting process, a solder that is used to fuse a semiconductor package is being changed into a solder that does not use lead, such as a Sn-Ag-Bi system, instead of a Sn-Pb-based solder containing lead. However, if the lead component is not used, the melting point of the solder increases by 20-30 ° C. in the semiconductor mounting process, and the vapor pressure of moisture absorbed at the interface is much increased, resulting in pop-corn cracks in the semiconductor package. There is a problem. Furthermore, according to the trend of thinning of the semiconductor package, the thickness of the thin small outline package (TSOP), which is generally used as a package for DRAM, is only 1 mm, and thus the semiconductor sealing material is very weak against breakage shocks inside the package. There is an urgent need to improve the heat resistance, adhesive properties and hygroscopicity of the resin. In addition, the ball grid array (BGA) of the semiconductor package is easily bent at the mounting temperature because of its asymmetrical structure and difference in coefficient of thermal expansion between materials. The epoxy sealing material used for the BGA further requires a numerical stability at high temperatures.

In order to meet these demands, the elastic modulus is generally lowered to lower the stress, the thermal expansion coefficient is lowered, and the adhesion between the chip or lead frame and the sealing material of the semiconductor element is increased to prevent moisture from absorbing at the interface, and the inorganic filler It is conceivable to reduce the moisture absorption by increasing the content of. Among the above methods, there is a method of increasing the adhesion, using a low viscosity epoxy resin and other additives such as biphenyl epoxy of the formula (1).

Next, as a method of lowering an elastic modulus, there are a method of blending and modifying a butadiene-containing rubber modifier or a silicone polymer having excellent thermal stability (Japanese Patent Laid-Open Nos. 63-1894 and 5-291436). Since the silicone oil used in the method is incompatible with the epoxy resin and the curing agent, which are the base resins of the molding material, the silicone oil can be dispersed in the form of fine particles in the base resin to lower the elastic modulus while maintaining the heat resistance.

Finally, the method of lowering the coefficient of thermal expansion is to increase the amount of the inorganic filler having a low coefficient of thermal expansion. In this case, as the amount of the inorganic filler is increased, the fluidity and the elasticity of the epoxy molding material are decreased. Japanese Patent Laid-Open No. 64-11355 proposes a technique for using a spherical filler but blending a large amount of filler by controlling its particle size distribution and particle size. In this case, as the content of the inorganic filler increases, the effect of lowering the moisture absorption rate can be obtained.

However, since the method of increasing the inorganic filler content in the biphenyl epoxy resin and incorporating the silicone polymer as described above lowers the glass transition temperature of the biphenyl epoxy resin itself, the difference in the high temperature thermal expansion coefficient between the various materials in the semiconductor package becomes very large. There is a problem that it is difficult to satisfy the moldability and reliability characteristics, such as bending according to the type of. In addition, due to the slow curing speed of the biphenyl epoxy resin, the productivity and workability of the semiconductor package molding process may be deteriorated.

Therefore, it is necessary to develop an epoxy resin composition for semiconductor element sealing that can solve the problems as described above.

An object of the present invention is to provide an epoxy resin composition for sealing semiconductor elements comprising a crystalline naphthalene epoxy resin, a novolac curing agent, a curing accelerator and an inorganic filler.

That is, the present invention

(1) 3.5 to 7.0% by weight of a naphthalene epoxy resin of the following formula (2),

(2) 3.5-7.0% by weight of at least one novolac-based curing agent selected from the group consisting of conventional phenol noblock resins, xylox resins, dicyclopentadiene resins having two or more hydroxyl groups and a hydroxyl group equivalent of 100-200,

(3) 0.1-0.3% by weight curing accelerator and

(4) 88-92% by weight of inorganic filler

It is to provide an epoxy resin composition for sealing a semiconductor device comprising a.

(Wherein R is hydrogen or CH ₃ )

The epoxy resin composition for sealing a semiconductor device of the present invention includes a naphthalene-based epoxy resin, a novolac-based curing agent, a curing accelerator, and an inorganic filler, which will be described in detail below.

The naphthalene epoxy resin (hereinafter referred to as component (1)) used in the present invention is a low viscosity crystalline material and has a structure as shown in the following formula (2).

[Formula 2]

(Wherein R is hydrogen or CH ₃ )

Since the component (1) has a symmetrical molecular structure compared to the conventional liquid naphthalene epoxy resin of the following general formula (3), it is a crystalline state of solid at room temperature and the viscosity is very low upon melting so that an inorganic filler can be added at least 88% by weight. do.

In the present invention, the melting point of component (1) can be adjusted by adjusting the intramolecular substituent. The content of component (1) is preferably 3.5-7.0% by weight based on the total composition. If the content is less than 3.5% by weight can not be obtained because the physical properties of the degree required in the present invention is not good, and if the content is more than 7.0% by weight is not economical because it is not good.

As the novolak-based curing agent (hereinafter referred to as component (2)) used in the present invention, a group consisting of ordinary phenol noblock resins, xylox resins, and dicyclopentadiene resins having two or more hydroxyl groups and a hydroxyl equivalent of 100-200 One or more resins selected from can be used alone or together. The content of component (2) is determined so that the composition ratio of epoxy equivalent to hydroxyl equivalent falls within the range of 0.9-1.1. At this time, it corresponds to 3.5-7.0 wt% with respect to the total composition ratio. If the composition ratio is out of the above range, a large amount of unreacted epoxy and phenol groups are generated, which results in poor reliability.

The curing accelerator used in the present invention (hereinafter referred to as component (3)) is a component used to accelerate the curing reaction of the component (1) and component (2), benzyldimethylamine, triethanolamine, triethylenediamine, Tertiary amines such as dimethylaminoethanol and tri (dimethylaminomethyl) phenol; Imidazoles such as 2-methylimidazole and 2-phenylimidazole; Organic phosphines such as triphenylphosphine, diphenylphosphine and phenylphosphine; One or two or more compounds selected from the group consisting of tetraphenylboron salts such as tetraphenylphosphium tetrabenylborate, triphenylphosphine tetraphenylborate and the like can be used alone or in combination. The content of component (3) is preferably 0.1 to 0.3% by weight based on the total composition. If the content is less than 0.1% by weight, the curing rate is slow and the productivity is not good, and if the content is more than 0.3% by weight, the desired curing properties are not obtained, and storage stability is not good.

As the inorganic filler used in the present invention (hereinafter referred to as component (4)), it is preferable to use fused or synthetic silica having an average particle size of 0.1-35.0 µm. The content of component (4) is preferably 85-92% by weight based on the total composition. If the content is less than 85% by weight, sufficient strength and numerical stability against high temperature may not be obtained, and the penetration of moisture may be facilitated, resulting in poor pop-corn cracks in the high temperature solder process. If the content is more than 92% by weight, the flow characteristics are deteriorated and the moldability may deteriorate, which is not good.

The upper limit of the filling amount of the component (4) should not only be selected in consideration of moldability, but also preferably mixed with crushed and spherical silica in a constituent composition ratio of crushed and spherical 3/7-0/10. It should be a product of high purity.

Further, the molding material of the present invention includes flame retardants such as brominated epoxy flame retardant, antimony trioxide, alumina hydroxide and antimony pentoxide; Mold release agents such as higher fatty acids, higher fatty acid metal salts, and ester waxes; Coloring agents such as carbon black, organic and inorganic dyes; Coupling agents, such as an epoxy silane, an amino silane, and an alkyl silane, can also be added as needed.

These ingredients are blended in a predetermined amount, uniformly mixed using a Hanssel mixer or Loedige mixer, melt-kneaded with a roll mill or kneader, and then cooled and pulverized. Through the process, the final powder product can be obtained.

Hereinafter, the present invention will be more specifically described with reference to the following examples. The following examples are only described for the purpose of illustrating the present invention and are not intended to limit the protection scope of the present invention.

Example 1-3

The components shown in Table 1 were weighed and uniformly mixed with a Henschel mixer to prepare an epoxy resin composition in powder form. After melt kneading at 100 ℃ using a kneader, and then cooled and pulverized to prepare an epoxy resin composition for sealing a semiconductor device of the present invention. The spiral flow of the resulting epoxy resin composition was measured, and after the specimen was prepared and cured after 175 ° C. for 6 hours, flexural strength, elastic modulus, adhesion force, glass transition temperature, moisture absorption rate, and thermal expansion rate were measured. In addition, 44-TSOP and 48-FBGA were formed and post-cured, and then absorbed for 48 hours and 168 hours under constant temperature and humidity conditions of 85 ° C / 65% RH, and three times of IR reflow for 10 seconds at 265 ° C. The crack of the package was measured by passing. The measurement results are shown in Table 1.

Comparative Example 1-3

Using the components shown in Table 2 was carried out in the same manner as in Example 1-3, the results are shown in Table 2.

(Unit: weight%)

(Unit: weight%)

 As confirmed through the results of Examples and Table 1, the epoxy resin composition for sealing a semiconductor device of the present invention has excellent crack resistance against high temperature, less heat deformation at high temperature, and improved adhesion to lead frames. Has an advantage.

Claims (5)

(1) 3.5 to 7.0% by weight of a naphthalene epoxy resin of the following formula (2), (2) 3.5-7.0% by weight of at least one novolac-based curing agent selected from the group consisting of conventional phenol noblock resins, xylox resins, dicyclopentadiene resins having two or more hydroxyl groups and a hydroxyl group equivalent of 100-200, (3) 0.1-0.3% by weight curing accelerator and (4) 88-92% by weight of inorganic filler Epoxy resin composition for sealing semiconductor elements comprising a. [Formula 2]

(Wherein R is hydrogen or CH ₃ ) delete A tertiary amine such as benzyldimethylamine, triethanolamine, triethylenediamine, dimethylaminoethanol, tri (dimethylaminomethyl) phenol, etc. according to claim 1; Imidazoles such as 2-methylimidazole and 2-phenylimidazole; Organic phosphines such as triphenylphosphine, diphenylphosphine and phenylphosphine; An epoxy resin composition for semiconductor element sealing, comprising at least one compound selected from the group consisting of tetraphenylboron salts such as tetraphenylphosphium tetrabenyl borate, triphenylphosphine tetraphenyl borate and the like. The epoxy resin composition for semiconductor element sealing according to claim 1, wherein the inorganic filler is fused or synthetic silica having an average particle size of 0.1-35.0 µm. The epoxy resin composition for semiconductor element sealing according to claim 1 or 4, wherein the silica is used in a constituent composition ratio 3/7-0/10 of the pulverized and spherical silica.