JPH05278077A - Mold for transfer molding - Google Patents

Abstract

PURPOSE:To prevent the opening peripheral part of a guide port from being abraded through hard filling materials in a casting resin by mounting guide sleeves made of an abrasion resistive material on the guide holes of knockout pins of a mold for transfer molding for the use of resin sealing a semiconductor element. CONSTITUTION:Guide sleeves 10 are fittingly mounted as telescopic ones on guide holes of knockout pins 8 made on a cavity block so as to enable the knockout pins to be moved impulsively. It is preferable that the guide sleeves 10 are made of sintered hard alloy with high abrasion resistivity. Besides, it is also preferable that a flange 10a is formed on its lower end to be engaged and fastened on the rear surface of the cavity block. In this way, even in the case of repeating molding by sealing resin blended with hard filling materials, abrasion around the opening peripheral parts of the guide holes can be prevented to thereby also preventing the appearance of a molding from being spoiled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer mold die used in a resin encapsulation process of a resin encapsulation type semiconductor element.

[0002]

2. Description of the Related Art A transfer molding method is generally adopted for resin encapsulation of a resin encapsulation type semiconductor element. The transfer mold die used here is well known,
The semiconductor element assembly is inserted into the mold, and a casting resin is injected into the cavity of the mold for molding. Further, a knockout pin for ejecting a molded product is incorporated in the mold, and after molding, the mold is opened and the knockout pin is operated to take out the molded product.

FIGS. 3 and 4 show the conventional structure of such a transfer mold, in which 1 is a cavity block which is a split mold, 2 is a chase for fastening the split mold of the cavity block 1, and 3 is a cavity. The cavity formed in the block 1, 4 is a runner pulled out from the transfer pot 5, 6 is a gate, 7 is a runner 4, guide holes for knockout pins drilled in the bottom surface of the cavity 3, 8 is a knockout pin inserted in the guide hole 7, 9 is a knockout pin plate, and 8 knockout pins
Is operated via an ejector rod and an ejection ram (not shown).

[0004]

By the way, a thermosetting resin is generally used as a sealing resin for the above-mentioned semiconductor element, and a hard filler such as silica is usually used in the molding resin material of about 70-80. %include. Therefore, if the mold is used for a long period of time, the periphery of the guide hole 7 of the knockout pin 8 punched in the mold runner and the cavity is cast by repeating the resin injection into the cavity and the protruding operation of the molded product. The hard filler contained in the resin abrades and abrades the edge of the guide hole 7, which originally had an edge as shown in FIG. 5, and was abraded as shown in FIG. A phenomenon occurs in which the casting resin enters the space P caused by the wear and hardens. Moreover, if the periphery of the guide hole 7 is worn and the casting resin enters,
In addition to the formation of protrusions on the surface of the molded product (semiconductor element package) to impair the external appearance, the slidability of the knockout pin 8 may be deteriorated and the knockout pin 8 may protrude and break during operation.
It is practically impossible to repair the worn part of the cavity block itself.

The present invention has been made in view of the above points, and an object thereof is to solve the above-mentioned problems and to improve the wear resistance of the knockout pin to the guide hole, thereby providing a highly durable and reliable transfer mold die. To provide.

[0006]

In order to achieve the above object, in the mold of the present invention, a guide sleeve made of a wear resistant material is mounted in a guide hole of a knockout pin formed in a cavity block. Shall be configured.
Here, it is preferable to use cemented carbide as the material of the guide sleeve. In addition, in order to prevent the guide sleeve from being accidentally dropped, there is a configuration in which a retaining collar that engages with the cavity block is formed at one end of the guide sleeve.

[0007]

[Function] As described above, by providing the guide hole of the knockout pin with the guide sleeve made of cemented carbide which is a wear resistant material, it is repeatedly rubbed by the hard filler mixed in the casting resin. However, the edge of the guide hole is hardly worn. In addition, by engaging and attaching the flange portion formed at the end portion of the guide sleeve to the back surface side of the cavity block, there is no possibility that the guide sleeve may accidentally drop from the cavity block due to sliding of the knockout pin.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. In the drawings of the embodiments, the same members corresponding to FIGS. 3 and 4 are designated by the same reference numerals. That is, the guide sleeve 10 is fitted and attached as a nest into the guide hole of the knockout pin which is formed by penetrating the cavity block 1 and opening to the bottom surface of the cavity 3 and the runner 4. The guide sleeve 10 is made of a cemented carbide having high wear resistance, and has a collar portion 10a at the lower end of the sleeve as shown in FIG. 2, and the collar portion 10a is provided on the rear surface side of the cavity block 1. It is locked and fixed to. Then, the knockout pin 9 is operated so as to slide in the guide sleeve 10 and to be retracted in the cavity 3.

If the guide sleeve is worn out for a long period of time, it can be easily repaired by removing the guide sleeve 10 from the cavity block 1 and replacing it with a new one. Although the lower mold of the mold is shown in the drawing, a similar guide sleeve 10 is attached to the guide hole of the knockout pin which is punched in the upper mold.

[0010]

The transfer mold die of the present invention is
Since it is configured as described above, the following effects can be obtained. (1) Since the wear resistance of the guide hole portion of the knockout pin drilled in the cavity block is improved, the guide hole generated by repeated molding based on the polishing action of the hard filler mixed in the sealing resin of the semiconductor element. It is possible to satisfactorily prevent the wear of the peripheral edge of the opening and the intrusion of the casting resin into the worn portion, thereby preventing the appearance defect of the molded product and improving the reliability of the operation of the knockout pin.

(2) Even if the guide hole is worn due to the use of the mold for a long period of time, it can be easily repaired by replacing the guide sleeve.

[Brief description of drawings]

FIG. 1 is a sectional view of a mold according to an embodiment of the present invention.

FIG. 2 is an external perspective view of the guide sleeve in FIG.

FIG. 3 is a plan view of a transfer molding die which is an object of the present invention.

FIG. 4 is a block diagram of a conventional mold.

5 is an enlarged cross-sectional view of the guide hole portion of the knockout pin in FIG.

FIG. 6 is a view showing a state where the guide hole portion of the knockout pin shown in FIG. 5 is worn.

[Explanation of symbols]

 1 Cavity Block 3 Cavity 4 Runner 8 Knockout Pin 10 Guide Sleeve 10a Collar

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B29K 105: 20 B29L 31:34 4F

Claims (3)

[Claims] 1. A transfer molding die used for resin sealing of a semiconductor element, wherein a guide sleeve made of a highly wear-resistant material is mounted in a guide hole of a knockout pin formed in a cavity block. Transfer mold die. 2. The transfer mold die according to claim 1, wherein the guide sleeve is made of cemented carbide. 3. The transfer mold die according to claim 1, wherein a retaining sleeve is formed at one end of the guide sleeve to engage with the cavity block.