JP3313018B2 - Method for producing tablet of molding material for semiconductor encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for tablet-forming a molding material for semiconductor encapsulation, and more particularly to a method for improving the releasability of taking out a tablet after tableting. It is about.

[0002]

2. Description of the Related Art In molding materials for semiconductor encapsulation, it is required to improve adhesion strength to metal in order to increase adhesion to a frame. Further, in order to prevent voids in the package after semiconductor encapsulation, it is desired to increase the density of the tablet, and it is necessary to increase the molding pressure at the time of tablet compression. Along with these demands, a problem has arisen in that a part of the molding material adheres to the punch surface after molding during tablet production and a part of the tablet surface is missing. Various methods such as tableting with a small amount of a release agent such as a higher fatty acid metal salt added to prevent adhesion and baking and coating the release agent on the punch surface have been studied in various ways. Not yet obtained. Therefore, when the adhesion occurs, a measure is taken to stop the tablet press, clean the punch surface, and remove the adhesion, but the productivity is remarkably reduced.

[0003]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to solve the problem of the molding material adhering to the punch surface. The object is to improve productivity by eliminating adhesion to the punch surface.

[0004]

In order to solve such a problem, as a study to prevent the molding material from adhering to the punch surface, tableting is performed while cooling the punch below the softening temperature of the material. Adhesion occurs at about 2,000 shots, and conversely, when the punch is heated to about 40 ° C. and tableting is performed, not only does adhesion occur at about 100 shots, but also melting of the material The viscosity in the state increased, and a problem in quality occurred. Next, an attempt was made to bake and apply a fluorine-based release agent to the punch surface.
Adhesion occurred at about the shot. JP-A-7-11704
No. 8 discloses a method of preventing air sticking by injecting air onto upper and lower punch surfaces. However, when tableting is performed with a continuous tablet molding machine, 2,0 is used.
At about 00 shots, adhesion occurred, and the effect was insufficient. In addition, when a method of adding a mold release agent such as a higher fatty acid metal salt to the material in advance by about several weight% has a large effect of preventing adhesion, the result is that the reliability of the material is reduced.

[0005] As a result of these investigations, as a result of intensive studies on a method in which a very small amount of release agent that does not affect the quality of the material is always coated on the punch surface during tableting, carboxyl-modified dimethylpolysiloxane was found. It has been found that it is very effective to coat and tablet with 0.5 to 50 μm, preferably 1 to 20 μm while coating. That is, in the present invention, when the molding material for semiconductor encapsulation is tablet-formed by a continuous tablet molding machine, the upper and lower punch surfaces are coated with a carboxyl-modified dimethylpolysiloxane so that the layer thickness becomes 0.5 to 50 μm. And tableting a tablet made of a molding material for semiconductor encapsulation.

As for the release agent, experiments were conducted on various release agents. The carboxyl-modified dimethylpolysiloxane shown below is excellent in that it has an effect of preventing the adhesion of the molding material and hardly affecting the quality. The result was obtained. The thickness of the coating layer at this time is 0.5 to
It is 50 μm, preferably 1 to 20 μm. When the coating layer is thinner than 0.5 μm, there is no effect of preventing the adhesion, and when the coating layer is thicker than 50 μm, the quality of the material itself is adversely affected, for example, the adhesion strength to the frame after semiconductor sealing is reduced. * Carboxyl-modified dimethylpolysiloxane (CH ₃ ) ₃ SiO-[(CH ₃ ) ₂ SiO] _l- [CH ₃ SiOC _n H _2n COOH] _m -Si (CH
₃ ) ₃ (However, l = 3 to 5, m = 150 to 170, n = 8 to 12)

[0007]

【Example】

<< Example 1 >> 3 parts by weight of carboxyl-modified dimethylpolysiloxane and 97 parts by weight of n-pentane were mixed and stirred to prepare a uniform solution. While this solution was spray-coated on the upper and lower punch surfaces with an average thickness of 3 μm, 100,000 tablets were tableted with a continuous tablet tableting machine. As a result, no sticking to the punch surfaces occurred. Also, there was no problem in the practical test, and no adverse effect on quality was observed by spray coating.

Comparative Example 1 3 parts by weight of an alkyl silicone oil and 97 parts by weight of n-pentane were mixed and stirred to prepare a uniform solution. Tableting was performed while spray-coating this solution in the same manner as in Example 1;
At 0 shot, the molding material adhered to the punch surface, and some tablets were missing. << Comparative Example 2 >> The surface of the upper and lower punches was baked and coated with a fluorine release agent, and tableting was performed in the same manner as in Example 1 except that spraying was not performed using this punch. At 10,000 shots, the molding material adhered to the punch surface, and some tablets were missing.

Comparative Example 3 Tableting was performed in the same manner as in Example 1 while spray coating the solution used in Example 1 with an average thickness of 0.3 μm. The molding material adhered, and some tablets were missing. << Comparative Example 4 >> The solution used in Example 1 was coated with an average thickness of 70 μm.
As a result of tableting 100,000 tablets in the same manner as in Example 1 while spray coating was performed, no adhesion to the punch surface occurred. However, in a practical test, the adhesion strength to the frame was weak, and peeling occurred. Was.

[0010]

According to the method of the present invention, when a molding material for semiconductor encapsulation is tableted into a tablet, adhesion of the molding material to the punch surface can be eliminated, and the productivity of the tablet can be greatly improved. Since a product equivalent to the conventional product can be obtained in terms of quality, it is suitable as an industrial method for manufacturing a tablet of a molding material for semiconductor encapsulation.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 43/00-43/58 B29B 9/00-11/14 B29C 33/56-33/66 H01L 21/56 C08G 77 / 00-77/62 C10M 101/00-177/00

Claims (1)

(57) [Claims] 1. A method for tableting a molding material for semiconductor encapsulation with a continuous tablet molding machine, wherein upper and lower punch surfaces are coated with a carboxyl-modified dimethylpolysiloxane so that the thickness of the layer is 0.5 to 50 μm. And tableting, wherein a tablet of a molding material for semiconductor encapsulation is produced.