JPS6140353A - Method and apparatus for producing resin tablet for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain a tablet having high specific gravity and excellnt quality, in high efficiency, effectively removing the heat generated by compression and friction, by filling resin powder for semiconductor sealing in a tablet-forming mold furnished wih a cooling means, and compression molding the resin powder with the upper and the lower punches. CONSTITUTION:The resin powder 2 for the sealing of a semiconductor is charged to the tablet-forming mold 1 from the inlet 3, and pressed with the upper punch 4 and the lower punch 5. The upper punch is pulled up, and then the lower punch is pushed up to take off the formed tablet. In the above process, the refrigerant supplied from the refrigerant cooler 8 is supplied to the spiral groove 7 of the holer 6 with the circulation pump 9 to remove the heat generated by the compression with the upper and the lower punches and the frictional heat caused by the extraction of the tablet from the mold. Dehumidified dry gas is blasted from the dehumidifier 11 to prevent moisture-condensation caused by cooling.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method and apparatus for manufacturing a resin tablet for encapsulating semiconductors, particularly for manufacturing a resin tablet for semiconductor encapsulation with stable quality with high productivity. The present invention relates to a method and an apparatus capable of doing so.

(Prior Art) Semiconductor elements are usually encapsulated with resin by transfer molding of synthetic resin such as epoxy resin, and the resin used for this molding is supplied in the form of tablets obtained by compression molding the powder.

These tablets are made using a compression molding method in which a resin composition is kneaded with a roll or mixer, cooled, and then pulverized. A predetermined amount of the resulting powder is placed in a mold and pressurized. Due to the air bubbles that are incorporated into the tablet, its specific gravity is lower than that of a molded product. Compared to using a tablet whose specific gravity is 90% or less of the molded product, using a tablet with a specific gravity of 90% or more improves the transfer molding efficiency and the humidity-resistant life of the resulting resin-encapsulated semiconductor element by several steps. Since it has been confirmed that the pressure during tablet molding is increased, the specific gravity of the tablet is increased to over 90% or even 95% of that of the molded product. If the size is too large, the energy applied to the powder will change to heat during compression molding, and when the tablet is removed from the mold, heat will be generated due to friction between the tablet and the mold. If this continues, the heat generated by the mold will cause the resin powder to melt and adhere to the mold, and if you continue to work in this state, it will rub against the surface of the tablet, causing defects such as chips, or cracks on the tablet. This disadvantage arises when a resin with a low viscosity is used, and in order to avoid this disadvantage, the molding operation must be frequently interrupted to cool the mold. This has the disadvantage that workability is extremely poor since the work must be restarted later.

(Structure of the Invention) The present invention relates to a method and apparatus for manufacturing a resin tablet for semiconductor encapsulation that can solve the above-mentioned disadvantages. Fill the attached tablet mold,
A method for manufacturing a resin tablet for semiconductor encapsulation, characterized in that it is compressed into a shape by an upper punch and a lower bunch, and a second invention provides a tablet molding mold provided with a spiral groove for circulating a refrigerant in a mold holder; The present invention relates to an apparatus for manufacturing a resin tablet for semiconductor encapsulation, which is characterized by comprising a punch and a lower punch.

That is, the present inventors determined the specific gravity (
As a result of various studies on methods for stably manufacturing tablets with a high quality and a specific gravity of 90% or more of the true specific gravity (hereinafter referred to as true specific gravity), we have developed a mold for tablet molding in a manufacturing device that uses compression molding of resin powder for semiconductor encapsulation. Providing a cooling mechanism, especially if this cooling mechanism is a structure in which two spiral grooves are provided in the mold holder and a refrigerant is fed into these, the heat generated by pressurization during tablet molding and the time when tablets are removed are reduced. It was discovered that the above-mentioned disadvantages were eliminated because the frictional heat of This effect will be further increased if a cooling mechanism is installed for the
Since there is a risk that the tablet may contain water, it has been found that it is effective to blow a tablet molding mold (two-line moist air, etc.). The present invention was completed after confirming that it is possible to obtain a tablet with high quality and efficiency.

A resin tablet for semiconductor encapsulation according to the method of the present invention is obtained by charging resin powder for semiconductor encapsulation into a tablet molding die,
Obtained by compression molding. This compression molding is performed by compressing the resin powder in the mold with upper and lower punches, but in the method of the present invention, the tablet molding mold is equipped with a cooling mechanism, in particular a mold holder for molding. It is said that the refrigerant is fed into the spiral groove provided in the inside, and the heat generated during compression molding by the upper and lower punches is quickly removed, so this compression molding can be carried out at a rate of, for example, 3 tons per hour. The advantage is that even if the temperature is increased to d, there will be no rubbing or chipping on the surface of the tablet, and tablets with a specific gravity that is 95% or more of the molded product can be manufactured easily and continuously over a long period of time. is given.

As mentioned above, the method of the present invention is to provide a cooling mechanism in the tablet molding die, but in this case, the heat generated during compression molding is further improved by circulating refrigerant in the upper and lower punches as well. removed.

In addition, manufacturing tablets using a mold with such a cooling mechanism improves workability by several steps, but in this case, moisture condenses inside the mold due to the working atmosphere, and this moisture enters the tablet. When transfer molding is performed using tablets containing moisture, voids and cracks occur in the molded product, and condensation occurs around the molded product, so it is necessary to prevent this condensation.

To prevent this condensation, it is preferable to blow dehumidified dry air into the tablet molding mold. For this dehumidification, air at a temperature of 10 to 20°C with a relative temperature of 20 to 50%,
Nitrogen, carbon dioxide, etc. at a wind pressure of 5 to 10 Aq, air volume of 1 to
It is best to blow the air directly onto the tablet mold, especially the inside surface of the mold, at a rate of 27+1"/min. By doing this, the inside surface of the mold is always kept in a low-humidity, low-temperature state, thereby preventing dew condensation inside the mold. The advantage is that completely protected and water-free tablets are reliably obtained.

The method and apparatus of the present invention will now be described with reference to the accompanying drawings, in which FIG. 1 shows a longitudinal section of the apparatus of the present invention. The tablet molding mold 1 shown in the figure is formed into a cylindrical shape, and a filling port 8 for filling the resin powder 2 for semiconductor encapsulation is provided in the center of the mold.
This resin powder 2 is compressed with appropriate pressure by an upper punch 4 and a lower punch 5 to form a tablet. This pressure varies depending on the type and particle size of the powder, but is usually 1 ton/cl.
When the specific gravity of the tablet is 90% or more of the true specific gravity, it is 2 tons/d or more, and the compression-molded tablet is taken out by lifting the upper bunch 4 and then lifting the lower punch 5. This mold II- is provided with a holder 6, this holder 6 is provided with a spiral groove 7, and the spiral groove 7C: is where the refrigerant from the refrigerant cooler 8 is fed from the circulation pump 9. According to the company, the heat associated with the compression of the upper and lower punches 4.5 is effectively removed, as well as the frictional heat when removing the tablet from the mold, resulting in a high-quality product with no scratches or chips on the surface. It has the advantage of being able to produce tablets continuously and efficiently.

In addition, if the mold i is provided with a cooling mechanism as described above, even if semiconductor encapsulation resin powder with low melt viscosity is used, the resin powder will not adhere to the upper and lower punches 4.5, and therefore the upper and lower surfaces of the tablet will be Although the smoothness is not impaired, in this case, it is optional to coat the surfaces of the upper and lower punches with a resin or to increase the smoothness of the surfaces of the upper and lower punches.

Regarding this cooling mechanism, we have shown a method in which a spiral groove is provided in the mold holder and the coolant is passed through it. The same effect can be obtained by providing a cooling jacket on the outside, or by embedding a rod-shaped heat pipe in the mold holder and passing a refrigerant through the heat pipe. The cooling effect is inferior to that using a spiral groove, and there is a risk that the pipe may be distorted or the tablet mold may be deformed during compression molding, so it is advantageous to provide the spiral groove as described above. be done.

In addition, in the method and apparatus of the present invention, as described above, it is preferable to provide a refrigerant circulation mechanism in the upper and lower punches, and to blow dehumidified dry gas onto the surface of the tablet molding die. , the figure shows upper and lower punches 4.5
A cooling groove 10 and a dehumidifying device 11 for blowing dehumidified dry gas onto the tablet molding die are shown.

In short, when a resin tablet for semiconductor encapsulation is manufactured using the manufacturing apparatus of the present invention and the method of the present invention, the heat generated during tablet molding can be effectively removed, and the cooling Since dew condensation is completely prevented, high-quality tablets with a specific gravity of 90% or more of the true specific gravity can be manufactured continuously and efficiently for a long time. It is particularly effective for producing tablets with a specific gravity of 9, but with a true specific gravity of 9.
It goes without saying that this method is superior in workability to the production of tablets with a specific gravity of 0% or less compared to conventional methods, and is advantageous in terms of process control.

Next, examples of the present invention will be given.

Example Two types of tablet mold holders with inner diameters of 30 mm and 60 mm have a depth of 10 mm, a groove width of 201 μll, and a pitch of 15 mm.
Create a spiral groove of 11 m1 to allow the refrigerant to pass through, and in this mold, 60 parts of cresol novolak resin with an epoxy equivalent of 220, 10 parts of a brominated epoxy novolac resin with an epoxy equivalent of 280, and a phenol novolak with a molecular weight of 500 are placed in the mold. Epoxy resin composition consisting of 30 parts of resin, 220 parts of quartz powder, 5 parts of antimony trioxide, 1 part of carnauba wax, 1 part of carbon black, 1 part of 2-phenylimidazole, and 1 part of T-glycidoxyprobyltrimethoxysilane. filled with powder.

Next, attach the upper and lower batches to this mold, and cool the mold by sending refrigerant into the spiral groove of the mold holder! =, Nitrogen gas at a humidity of 40% and a temperature of 15°C was blown into this mold, and compression molding was performed by setting the pressure of the upper punch to 2 tons/cd so that the specific gravity of the tablet was 1.60. This was carried out continuously and 2,000 tablets were made.

In addition, for comparison, we performed the same process without the mold cooling mechanism as described above, and in this case, the work was interrupted every 30 pieces due to heat generation in the mold, and work was restarted after cooling. I needed to do it.

Next, we measured the specific gravity, height, and weight of 2,000 tapelets (obtained in ζ~) and compared their dispersion, and the results shown in Table 1 were obtained, and the device of the present invention was used. It was confirmed that there was less variation in the results compared to the conventional method.

Table 1

[Brief explanation of the drawing]

Figure s1 shows the factors in the longitudinal section of the semiconductor encapsulation resin tablet manufacturing apparatus of the present invention. 1... Molding mold, 2... Resin powder for semiconductor encapsulation,
8... Filling port, 4... Upper punch, 5... Lower punch, 6... Holder, 7... Spiral groove. 8... Refrigerant cooler, 9... Circulation pump-10.
...Cooling groove, 11...Dehumidifier i. Patent applicant Shin-Etsu Chemical Co., Ltd. Figure 1 B

Claims (1)

[Claims] 1. A resin tablet for semiconductor encapsulation, characterized in that resin powder for semiconductor encapsulation is filled into a tablet molding die equipped with a cooling mechanism, and compression molded using an upper punch and a lower punch. manufacturing method. 2. The method for manufacturing a resin tablet for semiconductor encapsulation according to claim 1, wherein the cooling mechanism is a structure that feeds a coolant into a spiral groove provided in a tablet mold holder. 3. The method for manufacturing a resin tablet for semiconductor encapsulation according to claim 1 or 2, wherein the upper punch and the lower punch are provided with a cooling mechanism. 4. The method for manufacturing a resin tablet for semiconductor encapsulation according to claim 1, wherein the tablet molding die is equipped with a dehumidifying device. 5. A resin tablet manufacturing device for semiconductor encapsulation consisting of a tablet molding die provided with a spiral groove for circulating a coolant in the mold holder, an upper punch, and a lower punch. 6. The apparatus for manufacturing a resin tablet for semiconductor encapsulation according to claim 5, wherein the upper punch and the lower punch are provided with a cooling mechanism. 7. The apparatus for manufacturing a resin tablet for semiconductor encapsulation according to claim 5, wherein the tablet molding mold is equipped with a dehumidifying device.