JPS59140019A - Mold release device for resin molding die - Google Patents

Abstract

PURPOSE:To obtain the titled device putting no concentrated load on a molded piece by providing means to supply high pressure gas through gas supplying holes connected to molding chambers to the molding chambers and means to project pins installed in the supplying holes toward the molding chamber directions. CONSTITUTION:A gas chamber 12 is the cylinder chamber of an air pressure cylinder 17 and shutterpins 20 open and shut gas supplying holes 7b, 8b with the tips of piston rods 21. In a molding process, the gas supplying holes 7b, 8b are closed by the compression of a spring 15 through the shutter pins 20. In time of mold releasing, an electromagnetic valve 14 is opened to supply high pressure gas from a high pressure gas reservoir 13 to the gas chamber 12 and the shutter pins 20 are opened and driven to supply high pressure gas to the molding chamber 4. This device is suitable for a transfer mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold release device for a mold for resin molding.

Conventionally, for example, during transfer molding of molded semiconductor devices, in order to release the molded product from the mold, a small hole was made in one of a pair of molds that constitute the mold chamber, and this hole was normally closed with an ejector pin. When releasing the mold, it is common to push out an ejector pin to push the molded product while releasing it from the mold. The disadvantage of this mold release method is that especially when the mold release property is poor, the pressing force of the ejector pin acts as a concentrated load on the molded product, which may cause cracks in the molded resin body or cause damage to the internal molded body, e.g. It may have an adverse effect on semiconductor pellets. Furthermore, high precision is required for manufacturing the ejector pin and the small hole in the mold into which it is inserted, resulting in high manufacturing costs for the entire mold system.Especially in molds for transfer molding semiconductor devices. Since each set includes up to several hundred ejector pins, the equipment cost is extremely high.

An object of the present invention is to provide a mold release device for resin molding molds, which eliminates the above-mentioned drawbacks, does not apply concentrated loads to molded products, can be manufactured at low cost, and is particularly suitable for transfer molding. It is to be.

According to the present invention, this object is achieved by providing a gas supply hole that communicates with a molding chamber formed by a pair of molds that are movable toward and away from each other, and supplying high-pressure gas from the gas supply hole toward the molding chamber. This is achieved by performing mold release using a combination of a supplying means and a means for projecting a pin provided in the gas supply hole toward the molding chamber.

FIG. 1 shows a mold release device for transfer molding molds proposed by the present inventor.

In the figure, numerals 2 and 3 are an upper mold and a lower mold which are arranged so as to be movable toward and away from each other by a drive device (not shown). The figure shows a state in which both molds 2 and 3 are in contact with each other, and a molding chamber 4 is formed by both molds 2 and 3. Molten molding resin is injected into the molding chamber 4 from a runner 5 through a gate 6. The molds 2 and 3 have gas supply holes 7a and 8 that communicate with the mold chamber 4.
a are provided at positions facing each other.

The molds 2 and 3 are provided with shutter bins 10 that can open and close gas supply holes 7a and 8a, respectively. The shutter bin 10 is driven to open and close by a hydraulic cylinder (not shown) via a rod 11 that moves up and down as shown by the arrow. When the shutter bin 10 is driven to open, the molding chamber 4 communicates with the gas chamber 12 airtightly attached to the molds 2 and 3 through the gas supply holes 7a and 8a, and a solenoid valve is connected to the high-pressure gas stop 13. 14 and gas chamber 12, high pressure gas can be supplied. Here, the gas may be air, and other inert gases may be used as necessary. A spring 15 is attached to the rod 11 and acts in a direction in which the shutter bin 10 closes the gas supply holes 7a and 8a, and the hydraulic opening operation of the shutter bin 10 is performed against the pressing force of the spring 15.

In the apparatus shown in FIG. 1, during the molding process, the shutter bin 1o is moved through the gas supply hole 7a by the pressing force of the spring 15.
Blocking 8a. Both molds 2 and 3 are butted together as shown in the figure, and molten mold resin is injected into the molding chamber 4 through the runner 5 and gate 6. After the resin hardens, the rod is removed by a hydraulic cylinder just before the mold is opened. 11 to open the shutter bin 10, and at the same time open the solenoid valve 14 to send high pressure gas from the high pressure gas stopper 13 into the molding chamber 4 through the gas chamber 12 and gas supply holes 7a and 8a. Thereafter, an operation of opening the molds 2 and 3, ie, mold opening, is performed.

At this time, if a minute gap is first generated between the mold and the molded product near the gas supply holes 7a and 8a due to the high pressure gas, uniform gas pressure is applied to the entire surface of the gap, which further reduces the gap. Progress is encouraged, and eventually the entire surface peels off. In this case, the mold release force is applied to the gas supply hole 7.
It is not only the parts a and 8a, but the entire part where the gas has entered, and therefore no local concentrated load is applied to the molded product, so it does not cause cracks in the molded product or adversely affect the internal elements of the molded product. There is nothing to do. However, a problem was found in this device as well, in that the mold release of the transfer molding die was not sufficient.

The present invention relates to a mold release device for a transfer mold mold that can perform more complete mold release.

FIG. 2 shows an embodiment of the invention. Identical or corresponding components are designated by the same reference numerals as in FIG. In this embodiment, the gas chamber 12 is a pneumatic cylinder 17
The distal end of the piston rod 21 constitutes a shutter bin 20 that opens and closes the gas supply holes 7b and 8b.

In this device, during the molding process, the shutter bin 20 is moved through the gas supply hole 7b by the pressing force of the nokune 15.
Blocking 8b. At the time of separation, by opening the electromagnetic valve 14 and supplying high pressure gas from the high pressure gas stopper 13 to the gas chamber 12, the shutter bin 20 is driven to open against the pressing force of the spring 15, and the gas chamber 12 is opened through the gas supply hole. It communicates with the molding chamber 4 via 7b and 8b, and high pressure gas is supplied thereto.

The other configuration and operation are exactly the same as the device shown in FIG.
Exactly the same effects as the device of FIG. 1 can be achieved.

The mold release device of the present invention described above works effectively even when used alone, but in some cases it may be used in combination with a conventional ejection pin type device. In addition to transfer molding using resin, it can be generally applied to mold release of molded products in compression molding, injection molding, and other molding equipment.

This is particularly effective in cases where mold releasability affects the quality of the molded product.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a mold release device proposed by the present inventor, and FIG. 2 is a sectional view showing an embodiment of the mold release device according to the present invention. 2... Upper mold, 3... Lower mold, 4... Mold forming chamber, 7a. 8a, 7b, 8b = gas supply hole, 10.20... shutter bin, 11, 21... rod, 12... gas chamber, 13... high pressure gas stop, 14... solenoid valve, 1
5...Spring. Figure 1

Claims (1)

[Claims] 1. A means for providing a gas supply hole that communicates with a molding chamber formed by a pair of molds that are movable toward and away from each other, and supplying high-pressure gas from the gas supply hole toward the molding chamber; A mold release device for a resin mold mold, characterized in that mold release is performed by using a pin provided in a supply hole in combination with a means for protruding toward the molding chamber.