JPH05175259A - Tablet manufacturing method of semiconductor sealing epoxy resin composition - Google Patents

Abstract

PURPOSE:To enable the tablet molding step to be performed stably without deteriorating the powder quality of the title epoxy resin composition by a method wherein specific amount of high grade fatty acid metallic salt is added to the powder of epoxy resin composition and after mixing the powder using a particulate mixer, the mixture is molded into tablet form using a metallic mold. CONSTITUTION:0.01-0.10wt.% of high grade fatty acid metallic salt is added to the powder of the title semiconductor sealing epoxy resin composition and after mixing the powder using a particulate mixer, the mixture is molded into tablet form using a metallic mold. For example, a low melting viscosity epoxy resin, phenol resin hardener, a hardening accelerator, an inorganic filler and the other additive are sufficiently and evenly mixed using a mixer etc. Furthermore, the mixture is molten-mixed by a hot roll and then 100wt.% of material powder crushed after cooling down step in grain size not exceeding 3mm is fed in a V type blender and then 0.03wt.% of stearic acid zinc is added to be blended at normal temperature and 15rpm for 20 minutes. Finally, the powder is continuously tabletted using multiple rotary tabletting machines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tablet of an epoxy resin composition for semiconductor encapsulation.

[0002]

2. Description of the Related Art In recent years, almost all tablets of a resin composition for semiconductor encapsulation have been used in an assembly line for encapsulating semiconductors. Conventionally, as a method for producing a tablet, it is general to put powder of an epoxy resin composition into a mold and use a tableting machine. However, when the powder of the epoxy resin composition is put into a mold and molded into a tablet using a tableting machine, the resin adheres to the inner surface of the mold and the tableting machine is often stopped and the mold is manually pressed. Production is performed by removing and cleaning deposits on the inner surface. If the removal / cleaning is not complete, there is a case in which it is difficult to obtain a good product because the tablet surface is dented due to the slightly adhering substances left on the inner surface of the mold.

Further, in recent years, there has been a remarkable tendency toward miniaturization and thinning of semiconductor packages, and the epoxy resin in the epoxy resin composition for semiconductor encapsulation tends to have a low melt viscosity, and the above-mentioned troubles increase, resulting in production. There is a decrease in sex. As a measure against this trouble, frequently clean the inner surface of the mold, bake the release agent on the inner surface of the mold, or apply it by spraying, plating for preventing adhesion on the inner surface of the mold, and significantly increasing the tableting speed during tableting. There are problems such as slowing down, etc. That is, the former often stops the tableting machine, which significantly impairs productivity and has a problem in quality. The latter release agent has problems that a large amount of the release agent partially adheres, stains on the mold during molding, uneven quality, and lack of reliability. In other words, in the conventional molding technology, it is extremely difficult to obtain a good product in a stable manner without sticking to the epoxy resin for semiconductor encapsulation.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to solve such problems, and an object thereof is an epoxy for semiconductor encapsulation using an epoxy resin. It is intended to provide a method for stably producing tableting without impairing the quality of powder of a resin composition.

[0005]

According to the present invention, a higher fatty acid metal salt is added to a powder of an epoxy resin composition for semiconductor encapsulation in an amount of 0.
01 to 0.10 parts by weight is added, and after mixing with a powder / granular mixer,
A method for producing a tablet of an epoxy resin composition for semiconductor encapsulation, which comprises molding the mixture into a tablet with a mold. Powder of the epoxy resin composition for semiconductor encapsulation before adding the higher fatty acid metal salt used in the present invention (hereinafter referred to as raw material powder)
Is an epoxy resin, curing agent, curing accelerator, inorganic filler,
After the other additives are sufficiently mixed with a mixer or the like, they are further melt-mixed with a hot roll or a kneader, cooled, and then pulverized. The particle size of the raw material powder is preferably 8 mm or less. If it exceeds this, filling failure will occur during tableting,
Variations in tablet weight increase.

Examples of the powdered wax of the higher fatty acid salt of the present invention (hereinafter referred to as wax) include zinc stearate, calcium stearate, magnesium stearate and the like. Of these, zinc stearate is particularly preferable. The particle size of the wax is preferably 300 μm or less. If it exceeds this, the volume of zinc stearate present as a simple substance increases, and the reliability such as moisture resistance tends to be poor. The amount of wax added to the raw material powder is 0.01 to 0.10 parts by weight. If it is less than 0.01 parts by weight, there is almost no effect of preventing adhesion,
If it exceeds 0.10% by weight, the releasability is further improved and the anti-adhesion effect is improved, but the mold stain and the reliability of the product sealed with the composition are deteriorated. Within this range, the amount of addition may be appropriately selected for each composition of the raw material powder, the mold stains during molding,
The product was evaluated for moisture resistance, solder crack resistance, other reliability, and various physical properties, but there was no problem at all. Further, it is preferable that the wax has a melting point that melts during molding. An attempt was made to form a tablet using only the raw material powder obtained by kneading the resin composition with zinc stearate increased to some extent, but the tablet was kneaded into the inside, and there was almost no effect of preventing adhesion.

The raw material powder and the wax are mixed by a powder / granular mixer, and the wax is adhered to the raw material powder in a small amount and evenly, so that the wax covers the surface of the raw material powder during tablet forming and easily adheres to the mold. Even with the raw material powder, a tablet having a good appearance can be continuously molded without sticking to the mold at all.

The present inventors have completed the present invention by paying attention to the action of wax described below. That is, the surface temperature of the tablet when taken out from the mold immediately after tableting is found to be higher by about 5 to 15 ° C. than the powder temperature before molding. This is the surface temperature, and when calculated at the moment of tableting, due to heat generation for rapidly compressing the air trapped in the mold, friction heat generation due to rubbing between powders, etc., It is considered that the extremely short time reaches several hundred degrees. Due to this heat generation, the wax melts rapidly and coats the raw material powder surface. It is presumed that the melted wax intervenes between the tablet surface and the inner surface of the mold, exerts a releasing effect, and this is repeated, so that adhesion does not occur.

As the powder / granular mixer, there is a V-type blender, a tumbler blender, etc., and it is not particularly limited as long as it can uniformly mix the raw material powder and the wax in a short time. Mix at room temperature. For example, when using a V type blender, mixing at 10 to 30 rpm for about 5 to 30 minutes is sufficient.

A tableting machine used when a material obtained by uniformly mixing raw material powder and wax is molded into a tablet into a tablet is a single-shot type or rotary type tablet machine. The tableting speed may be the same as that of a conventional epoxy resin composition for semiconductor encapsulation. However, especially in the state of the raw material powder, a mixture in which a wax is added to the resin composition of the type with strong adhesion,
When tableting continuously, the temperature of the machine rises and the temperature of the tablet rises, which may deteriorate the quality. Therefore, cool the material to about 5-10 ° C in advance, and the tablet temperature after tableting is 20 ° C or less. Is desirable. Although there are various tablet shapes, the shape is not particularly limited, but a column shape is preferable.

[0011]

The present invention will be specifically described with reference to the following examples. Example 1 A low melt viscosity epoxy resin, a phenol resin curing agent, a curing accelerator, an inorganic filler, and other additives were sufficiently and uniformly mixed by a mixer or the like, further melt-mixed with a hot roll, and cooled and ground to a particle size. 100 parts by weight of raw material powder having a size of 3 mm or less is put into a V-type blender, 0.03 parts by weight of zinc stearate is added, mixed at room temperature for 15 minutes at 15 rpm, and a powdery epoxy resin in which zinc stearate is uniformly dispersed. A composition was obtained. The powder was continuously tableted for 4 hours on a rotary tablet machine with multiple stands. As a result, no resin composition adhered to the inner surface of the mold.

Comparative Example 1 The raw material powder of Example 1 before the addition of zinc stearate was molded by a rotary tablet machine having a plurality of stands. After about 5 minutes, the resin composition began to adhere to the inner surface of the mold, The molded tablet surface was scrubbed, and after that, the machine was stopped every 10 minutes and the mold surface was cleaned to produce the tablet surface, but only the tablet surface scooped to a depth of 0, 5 to 10 mm was obtained. There wasn't. Although the raw material powder was also cooled in advance, the result was the same.

Comparative Example 2 Zinc stearate was added in an amount of 1% by weight to a resin composition comprising a low melt viscosity epoxy resin, a phenol resin curing agent, a curing accelerator, an inorganic filler, and other additives, and the mixture was sufficiently mixed with a mixer. After uniformly mixing, the raw material powder having a particle size of 3 mm or less, which was melt-mixed with a hot roll and cooled and pulverized, was continuously tableted in the same manner as in Example 1. As a result, it was similar to Comparative Example 1. Comparative Example 3 Using the raw material powder before adding the zinc stearate of Example 1, various metal coatings for preventing adhesion on the inner surface of the mold,
Attempts were made to make a plated metal mold, the tableting speed of the machine extremely slow, and to apply a liquid mold release agent to the metal mold, but none of them had an effect of preventing adhesion.

[0014]

According to the present invention, non-defective tablets can be continuously obtained by a very simple method without sticking to the mold. Further, since there is no decrease in productivity due to frequent stoppage of the machine for cleaning, which is a problem of the prior art, and a good tablet can be obtained, an epoxy resin composition for semiconductor encapsulation that easily adheres to a mold Is most suitable as a tablet manufacturing method.

Claims (1)

[Claims] 1. To a powder of an epoxy resin composition for semiconductor encapsulation, 0.01 to 0.10 part by weight of a higher fatty acid metal salt is added, and the mixture is mixed with a powder / granular mixer, and then the mixture is tableted with a mold. 1. A method for producing a tablet of an epoxy resin composition for semiconductor encapsulation, the method comprising molding into a shape.