JPH01101639A - Molding die - Google Patents

Abstract

PURPOSE:To prevent resin from exuding onto a frame and onto a metal die by improving the accuracy for each surface by coating the metal die partaing surface with the resin. CONSTITUTION:Resin (silicone) coating 5 is applied on a metal mold, whereby a metal die pertaing surface can accommodate the deformation of the metal die and the unevenness of a frame surface to some degree. Namely, the upper die 1, a lower die 2, and the frame 4 are completely brought into close contact with each other by a resin coated surface upon closing the die. In addition, when it is primarily desired to prevent the resin from exuding onto the frame surface, the resin (silicone) coating may be applied only on the lower die on which the frame is set and only the upper die with which the frame surface makes contact. Hereby, the accuracy of the surface contact between the dies 1, 2 and the frame 4 can be improved and the resin can be prevented from exuding onto the frame 4 and onto the dies 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molding die used in an IC assembly manufacturing process.

[Conventional technology]

Figure 2 Z shows a conventional mold of this type.
(a) shows the state when the mold is opened, and (b) shows the state when the mold is closed. In the figure, 1 is an upper mold, 2 is a lower mold, 3 is hard chrome plating applied to the parting surfaces of the upper and lower molds, and 4 is a frame.

Conventional molds are made of mold material (SKD) as described above.
-11 grade 1 is plated with hard chrome, the mold surface has a mirror finish, and the surface hardness is also high.

Next, the operation will be explained. First, the frame 4 is set on the lower mold 2. Next, the upper mold 1 and the lower mold 2, which are mutually rigid bodies whose mold parting surfaces are plated with hard chrome, are closed with an arbitrary mold closing force. In this mold-closed state, a resin tablet that has been preheated (pre-1-) is put into the mold, and is filled into the mold cavity by low-pressure transfer molding to perform package molding.

[Problem to be solved by the invention 3 As mentioned above, in conventional molds, the mold material is a rigid body and the mold parting surface is also hard chrome plating, so there is a gap between the frame and the mold. Gaps are likely to occur (,
This gap is great! There were problems such as resin flashing on the frame due to oil leakage and increased frequency of mold cleaning due to resin leakage onto the mold surface.

This invention was made to solve the above-mentioned problems, and aims to provide a mold that prevents resin flash from occurring on the frame and also prevents resin from seeping onto the mold surface. The purpose is to

[Means for solving problems]

In the mold according to the present invention, the mold parting surface is changed from the conventional hard chrome plating to a resin (silicon) coating in order to improve the surface contact accuracy between the mold and the frame.

[Effect]

In this invention, by coating the mold parting surface with resin, the surface contact accuracy is improved as the mold parting surface follows the frame surface, and the resin does not soak into the frame and mold. It acts to prevent leakage.

[Example] Figure 1 shows an example of this invention.
) is a cross-sectional view of the mold when the mold is opened, (b) is a cross-sectional view of the mold when the mold is closed, and (e) is a perspective view of the mold surface. This is the point on which a resin (silicon) coating 5 is applied. By doing so, the mold parting surface can cope with a certain degree of mold distortion and irregularities on the frame surface. That is, as shown in FIG. 2(b), the upper mold 1, lower mold 2, and frame 4 are made of resin
The silicone coated surface ensures complete contact when the mold is closed.

Next, the operation will be explained. The manufacturing process is the same as described above, but in the present invention, the mold press and mold were distorted and the frame surface was uneven due to the resin coating applied to the mold parting surface. Even in this case, the resin (silicon) coating surface deforms along the frame surface, which prevents the resin from seeping onto the frame and mold surface.

In addition, in the perspective view of the mold surface shown in FIG. 1(e),
Although resin coating has been applied to the entire surface of the mold material, if the main purpose is to prevent the resin from seeping out onto the frame surface, apply resin coating to the lower mold part where the frame is set, and to the frame surface when closing the mold. Apply resin (
A silicone coating may be applied.

Another possibility is to apply the resin when the mold is in use, and periodically apply it to the surface of the mold to achieve the same effect.

Application methods include a method of spraying and a method of directly applying liquid resin to the mold parting surface.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent the resin from seeping onto the frame and the mold, thereby improving the package quality, as well as preventing resin from adhering to the mold surface. For example, you can reduce the frequency of cleaning, etc.
This has the effect of greatly contributing to improving workability and productivity.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, (&) is a sectional view of the mold when the mold is opened, (b) is a sectional view of the mold when the mold is closed,
(c) is a perspective view of the mold surface, Figure 2 shows a conventional mold, (&) is a cross-sectional view of IQ when the mold is opened, and a 4-side view, and (b) is a cross-sectional view when the mold is closed. It is. In the figure, 1 is an upper mold, 2 is a lower mold, 4 is a frame, and 5 is a resin coating layer. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A mold for molding a package by resin-sealing a lead frame, characterized in that a resin (silicon) coating is applied to the parting surface of the mold.