JPH01200929A - Method for detecting gaps between mold mating surfaces in transfer molding molds - Google Patents

Abstract

PURPOSE:To certainly detect a degree of hermetical sealing, by a method wherein air is discharged from or supplied to a clamped hermetically sealed mold to measure the flow rate of said air. CONSTITUTION:A lead frame R is placed on a lower mold 2 and, after an upper mold 1 and the lower mold 2 are clamped, a resin tablet A is placed in a pot 6 and a plunger 7 is allowed to fall. The plunger 7 is allowed to fall to close the opening of the pot 6 and the air in a cavity 5 is reduced in pressure and sucked through an air pipe 9(contrarily, compressed air may be supplied to the cavity 5 from the air pipe 9). When a gap is present between mold registering surfaces, air is penetrated in the cavity 5 from the outside through the gap when the air in the cavity 5 is reduced in pressure and sucked (contrarily, compressed air may be supplied) and, therefore, the internal pressure of the cavity 5 does not change. This pressure change is observed by a pressure gauge 10 to accurately detect the presence of the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the presence or absence of a gap in a transfer mold mold in a clamped state.

[Conventional technology]

Transfer molding, in which a thermosetting resin such as an epoxy resin is placed in a pot and heated and pressurized to feed the molten molding material into the cavity through a runner and a gate, improves the dimensional accuracy of the molded product (1); Because it has the advantage of being able to mold insert parts with complex shapes, it is widely used for insert molding of electronic parts such as IC1 diodes and transistors.

When insert molding electronic components as described above, it is necessary to accurately insert lead frames and terminals into the mold, but there are cases where a lead frame is forgotten or two lead frames are inserted. In addition, the lead frame may be misaligned, or a defective lead frame with a part missing may be set.Furthermore, mold scum or part of the frame may remain on the mold mating surface of the mold. Sometimes there are.

If the mold is clamped in the above state, a gap will be formed between the mating surfaces of the molds, and during molding, resin will flow out from the gap, resulting in unfilled or defective molded products. In addition, the resin flows onto the fitting surface of the mold and the sides of the mold, making subsequent cleaning time-consuming.

(Problem to be Solved by the Invention) In order to prevent troubles caused by the resin flowing out as described above, in the past, an operator had to visually check the correct cent state.
Although we tried to carry out verification, it was not reliable and it was not possible to reliably prevent the resin from flowing out.

Another method is to attach a highly accurate position sensor to the mold or mold press machine to detect the presence or absence of a gap between the mold mating surfaces. If you forget to insert it, this cannot be detected.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a gap detection method capable of reliably detecting the presence or absence of a gap in the mating surfaces of a mold, thereby eliminating the above-mentioned disadvantages.

(Means for Solving the Problems) In order to achieve the above object, in the gap detection method of the present invention, after the bottom part of the clamped transfer mold mold is sealed with a plunger, the inside of the mold is The structure is such that the air inside the formed cavity is reduced or sucked, or compressed air is forced into the cavity, and the pressure inside the cavity or the air flow to the cavity is detected.

[Effect]

With the above configuration, if there is a gap between the mold mating surfaces of the mold, the inside and outside of the cavity will communicate through that gap, so when air is sucked into the cavity or compressed air is supplied, The pressure change within the cavity is extremely small, and the amount of air sucked into or supplied to the cavity is increased. For this purpose, the pressure inside the cavity can be detected or the air flow 1" relative to the cavity can be detected.
By detecting l, it is possible to detect whether there is a gap between the molding surfaces.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in the figure, the transfer mold mold consists of an upper mold 1 and a lower mold 2. When both molds 1.2 are clamped, a runner 3, a gate 4, and a cavity are formed between the mating surfaces of the upper mold 1 and lower mold 2. 5 is formed.

The upper mold 1 is formed with a pot 6 that communicates with the runner 3, and the resin tablet 8 placed in the pot 6 is moved through the runner 3 and the gate 4 into the cavity 5 by the downward movement of a plunger 7 that can move up and down. is press-fitted into the

Further, a passage 8 communicating with the runner 3 is formed in the upper mold 1, and a pressure gauge 10 is attached in the middle of an air pipe 9 connected to the passage 8.

To perform insert molding using the mold configured as described above, the lead frame R is placed on the lower mold 2, the upper mold 1 and the lower mold 2 are clamped, and then the resin tablet A is placed in the bot 6. position, and then lower the plunger 7.

In the above molding process, if there is a gap between the mating surfaces of the upper mold 1 and lower mold 2, the molten resin will flow out through the gap and cause various problems. Therefore, the presence or absence of the gap is detected before molding. do.

When detecting this, the plunger 7 is lowered to close the opening of the pot 6 as shown in FIG. Compressed air is supplied from 9 into the cavity 5.

If a gap exists in the mold mating surface, when the air inside the cavity 5 is decompressed and sucked, air will enter the cavity 5 from the outside through the gap, and when compressed air is supplied, the compressed air will Since it leaks to the outside through the above-mentioned gap, the change in pressure inside the cavity 5 is extremely small.

Therefore, by looking at the pressure displayed on the pressure gauge 10, the presence or absence of a gap can be detected.

In addition, in the gap detection method described above, if there is a gap in the mold mating surface, the flow rate of air flowing inside the air pipe 9 will increase, so a flow meter is installed in place of the pressure gauge 10, and The presence or absence of a gap may be detected by detecting the air flow (■) flowing through.

After detecting the presence or absence of a gap as described above, if there is no gap, the plunger 7 is directly lowered to perform the molding operation.

During molding, the molten resin enters the passage 8 of the upper mold 1 and blocks the passage 8, making it impossible to carry out the next detection operation.As a means of closing the passage 8, the passage 8 is closed only during molding. A rod insertion hole 11 communicating with the passage 8 is formed in the upper die 1, a piston rod 13 of the cylinder 12 is inserted into the rod insertion hole 11, and a pin 14 attached to the tip of the piston rod 13 is inserted into the piston rod 13. There is a method of moving the tube in and out of the passage 8 by moving it in the axial direction.

〔Effect of the invention〕

As described above, the present invention closes the pot of a clamped mold with a plunger, reduces the pressure of the air inside the cavity of the mold, suctions it, or supplies compressed air to reduce the pressure inside the cavity at that time. Since the air flow rate is formed, it is possible to reliably detect the presence or absence of a gap in the mold mating surfaces.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a gap detection device implemented in the method according to the present invention, and FIG. 2 is a sectional view showing the molding state of the same. 1...Top mold, 2...Bottom mold,
5... Cavity, 6... Pot, 7... Plunger, 8... Passage, 9... Air pipe, 10...・・・
・Pressure gauge. Patent applicant: Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] After the transfer mold mold is clamped and the pot of the mold is sealed with a plunger, the air in the cavity formed inside the mold is decompressed and suctioned, or compressed air is pumped into the cavity. A method for detecting a gap between mold mating surfaces in a transfer mold die for detecting pressure within a cavity or air flow rate to the cavity.