JPH03169521A - Molding device for resin sealing - Google Patents

Abstract

PURPOSE:To constitute the title device so that a cull is removed reliably from a plunger, a foreign matter is not left behind within a mold and trouble is not generated, by a method wherein a tip surface of the plunger coming into contact with resin is made into roughened surface finish having specific surface roughness. CONSTITUTION:A tip surface of a plunger coming into contact with resin is made into roughened surface finish whose surface roughness Hmax falls within a range of 5-15mum. The tip surface 5a of the plunger 5 is made into roughened finish with, for example, discharge processing or a sand blaster and the tip surface 5a possesses appropriate unevenness. Consequently, the air is intruded into a space between thermally-cured resin 4 and the tip surface of the plunger 5 and a cull 13 is removed reliably and easily without being stuck vacuously to the tip surface 5a of the plunger 5, in a molding process. Therefore, though a trouble with the residual cull is generated conventionally at the rate of one time to about thousand times of molding processes, it becomes that the trouble is not generated at all and productivity is improved drastically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molding device for resin encapsulation used for resin encapsulation of semiconductors.

[Prior Art] FIG. 1 is a sectional view showing an example of a transfer molding apparatus. In FIG. 1, preformed resin is preheated and put into a pot 2 of a lower mold 1, where it receives heat from an upper mold 3 and a lower mold 1 and melts. The molten resin 4 is transferred by the plunger 5 and fills the cavity 8 through the gate 7. Note that a lead frame king O is inserted between the upper mold 3 and the lower mold 1.

The upper mold 3 and the lower mold 1 are held in a closed state until the resin 4 is cured, and after the resin 4 is cured, the lower mold 1 is closed as shown in FIG.
is moved downward.

After the lower mold 1 is lowered, as shown in FIG.
On the upper surface, the surface of the plunger 5 is filled with resin 3 that remains without being filled into the gate 7 during resin injection.
remains.

When the precept-shaped product 9 is taken out from the lower mold 1 in the state shown in Fig. 3,
As shown in FIG. 4, a pair of opposing semiconductor bodies 1l on a lead frame 10 are integrally connected to a cull 13 via a hardened resin 12 at a gate 7 portion.

In the above-described molding process, when taking out the shaped article 9 from the lower mold 1, it is necessary that the cull 13 on the tip surface 5a of the plunger 5 be completely removed from the plunger 5.

However, since the tip surface 5a of the plunger 5 was conventionally finished with a mirror finish, the cull 13
When the plunger 5 is pushed up and the resin is pressed in the next semi-finished product molding process, the residual cal may act as foreign matter, causing trouble.

By the way, it is thought that the reason why the mold releasability of the mirror-finished plunger 5 deteriorates is as follows.

That is, in FIG. 1, when the plunger 5 is pushed up and the resin 4 fills the cavity 8 and the gate 7, the mirror-finished tip surface 5a of the plunger 5 and the resin 4 are brought into complete contact. When the resin 4 is thermally cured, its volume shrinks by about 3%, but pressure is continuously applied to the plunger 5 to transfer the resin 4, and the surface 5a of the plunger 5
also moves while remaining in close contact with the resin 4 as the resin 4 contracts.
Therefore, in FIG. 2, when the upper mold 3 is moved upward to take out the molded product 9 from the lower mold 1, the cull 13 and the tip surface 5a of the plunger 5 remain in complete contact with each other. . Therefore, when trying to separate the cull 13 from the plunger 5, outside air cannot enter between the cull 13 and the plunger 5, and the cull 13 may be vacuum-adsorbed to the plunger 5.

[Problems to be Solved by the Invention] This invention solves the above-mentioned conventional problems, and ensures that the cull is removed from the plunger, so that no foreign matter remains in the mold, and no trouble occurs. The purpose of the present invention is to provide a molding device for resin sealing that is suitable for process automation.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a molding for resin sealing that includes a molding die and a plunger for moving resin under pressure and injecting it into the molding die. In the device, the tip surface of the plunger that comes into contact with the resin has a surface roughness Hmax of 5 to 15.
It is characterized by a rough surface finish in the μ range.

[Function] In the above structure, since the surface of the plunger has moderate unevenness, a gap is created between the cull and the plunger,
There is no possibility that the cull and the plunger will be vacuum-adsorbed.

[Example] According to the present invention, the tip surface 5a of the plunger 5 is roughened with a surface roughness Hmax of 6μ by, for example, electrical discharge machining, sandblaster, etc.
has moderate unevenness. As a result, in the molding process as shown in the engineering drawings to FIG. Cal 13 is reliably and easily removed without vacuum adsorption.

Therefore, when a conventional plunger is used, troubles due to residual cal occur at a rate of approximately 1 out of 1000 molding processes, but with the plunger of the present invention, there is no residual cal, so no trouble occurs at all. Productivity improves significantly.

In addition, the surface roughness H m of the tip surface 5a of the plunger 5
If a x is 15 μ or more, the surface has deep pores and the resin will enter these pores, so on the contrary, the cal 13
As a result, the mold releasability of the plunger 5 deteriorates.

In addition, the surface roughness Hmax of the tip surface 5a of the plunger 5
If it is less than 5μ, the difference from the mirror finish becomes small, and the mold releasability of the curve 3 and the plunger 5 deteriorates as in the prior art.

[Effects] According to this invention, the tip surface of the plunger has a surface roughness of Hm.
By providing a rough surface finish with ax in the range of 5 to 15μ, the mold releasability between the cull and the plunger is improved, the amount of cull remaining in the mold is significantly reduced, and troubles such as foreign matter pressing are eliminated, and productivity is significantly improved. do.

[Brief explanation of the drawings] Fig. 1 is a cross-sectional view of the transfer molding device showing the state in which resin is injected, Fig. 2 is a cross-sectional view showing the state in which the upper mold is moved upward, and Fig. 3 is a cross-sectional view showing the state in which the upper mold is moved upward. FIG. 2 is a top view showing the inner surface of the lower mold, and FIG. 4 is a top view showing the molded product taken out from the mold. E...Lower mold, 3...Upper mold, 13...Cull, 5...Plunger, 5a...
・Plunger tip surface.

Claims (1)

[Claims] (1) In a resin sealing molding device having a molding die and a plunger for moving resin under pressure and injecting it into the molding die, the tip surface of the plunger that comes into contact with the resin has a surface roughness Hmax of 5. A molding device for resin sealing characterized by having a rough surface finish in the range of ~15μ.