JPH0691704A - Resin mold for transistor - Google Patents

Abstract

PURPOSE:To provide the title mold capable of forming a through-hole to a resin molding part so as to make it unnecessary to remove a thin-walled part in a post-process, having a simple structure and capable of enhancing the releasability of a resin molded product from an upper mold. CONSTITUTION:In a resin mold for a transistor having a movable mold and a fixed mold and provided with a pin-shaped member 20 whose tip part protrudes into the cavity of one mold in order to form a through-hole to the resin molding part of a resin sealed transistor device, the pin-shaped member 20 is inserted in one mold 10 so as to be reciprocally movable within a predetermined range to be energized toward the other mold 30 by an elastic member 25 and, when the mold is closed, the tip of the pin-shaped member 20 is brought into contact with the surface of the cavity 14 of the other mold 30 and the pin-shaped member 20 is moved against the energizing force of the elastic member 25 to be closely brought into contact with the other mold by energizing force of a predetermined value or more by the elastic member 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin mold for a transistor, and more particularly, it has a movable mold and a fixed mold, and a through hole is formed in a resin molding portion of a resin-sealed transistor device. Therefore, the present invention relates to a resin mold for a transistor, in which one of the molds is provided with a pin-shaped member having a tip portion protruding into the cavity.

[0002]

2. Description of the Related Art Conventionally, some transistor devices formed by resin sealing have a through hole into which a screw can be inserted, because the resin molded portion is attached to a substrate by a screw. Note that this type of transistor device is often used in power transistors. Conventionally, a resin mold for a transistor as shown in FIG. 3 has been used for resin molding a transistor device having such a through hole. As shown in FIG. 3, in the upper die 50, a pin-shaped member called a core pin 60 having a tip portion protruding into the cavity 54 is fixed. The core pin 60 is not integrally formed with the upper mold 10 but is formed into a pin shape having a flange portion on the upper portion, and is sandwiched and fixed by the flange member between the upper mold component members 51 and 52 having two layers. This is because it is difficult to form the pin-shaped portion protruding into the cavity 54 in terms of processing.

In this molding die, when the die is closed, the core pin 60 does not come into contact with the upper surface of the lower die, and a small amount is provided between the tip surface of the core pin 60 and the upper surface of the lower die 70. It is formed to have a gap. This is because if the tip of the core pin 60 abuts the upper surface of the lower mold 70 before the mold is completely closed, the upper and lower molds cannot be completely closed, and there is a gap between the upper and lower molds. Since there is a risk of resin leakage, the core pin 60
This is because is set to be slightly shorter. For this reason, the molten resin enters into the above-mentioned slight gap during resin molding, and an unnecessary thin portion or a burr portion is formed when the resin does not completely go around. Conventionally, the thin portion and the burr portion are
It was removed by a post process.

On the other hand, as shown in FIG. 4, a lower mold movable pin 82, which is biased by an elastic member 84 (spring) so as to be able to project upward, is fitted into the lower mold 80, and the upper mold. There is a molding die in which 50 is formed similarly to the upper die 50 in FIG. According to this molding die, when the die is closed, the core pin 60 abuts the upper surface of the lower die movable pin 82 at its tip, and the lower die movable pin 82 is urged by the elastic member 84. It will be in a state of being pushed downward against. As a result, there is no problem in closing the mold, and the core pin 60 and the lower mold movable pin 82 are brought into close contact with each other by a biasing force of a predetermined amount or more. In this state, if a molten resin is introduced into the cavity 54 to seal the transistor with a resin, the through hole can be preferably formed in the resin molding portion of the transistor device. That is, FIG.
The thin-walled portion and the burr portion that are generated in the molding die of No. 1 are not generated, and the removal step can be omitted. Further, since the lower mold movable pin 60 moves upward when the mold is opened, it is possible to assist the release of the resin molded product from the lower mold.

However, in the conventional example shown in FIG. 4, the lower die movable pin 82 is fitted in the lower die 80,
The structure is complicated. Further, in the case of a normal power transistor, the mold releasability of the resin molded product from the mold is worse for the upper mold 50, and for the lower mold movable pin 82 provided in the lower mold 80, the upper mold is The mold releasability of the resin molded product in the mold cannot be improved. Therefore, the object of the present invention is to form a through hole in the resin molded portion so that it is not necessary to remove the thin portion and the like in a later step, the structure is simple,
An object of the present invention is to provide a resin mold for a transistor, which can improve the releasability of the resin molded product from the upper mold.

[0006]

In order to achieve the above object, the present invention has the following constitution. That is, a pin-shaped member having a movable mold and a fixed mold, and a tip of which protrudes into the cavity is provided in one mold so as to form a through hole in the resin molding portion of the resin-sealed transistor device. In the resin mold for transistor, the pin-shaped member is
When the mold is closed, the tip of the pin-shaped member is fitted into the one mold so as to be reciprocally movable within a predetermined range and is urged by the elastic member toward the other mold. And is moved against the urging force of the elastic member so that the pin-shaped member and the other die are brought into close contact with each other with a predetermined or more urging force by the elastic member.

[0007]

According to the resin mold for a transistor of the present invention, when the mold is closed, the pin-shaped member is urged by the elastic member in one mold toward the other mold when the mold is closed. Then, it abuts against the cavity surface of the other mold and is moved against the biasing force of the elastic member, and the elastic member brings the pin-shaped member and the other mold into close contact with each other with a biasing force of a predetermined value or more. In this state, if the molten resin is introduced into the cavity to seal the transistor with the resin, the through hole can be preferably formed in the resin molding portion of the transistor device.
That is, since the pin-shaped member and the other mold are in close contact with each other, a thin portion and a burr portion do not occur, and the removing step thereof can be omitted. Further, when the mold is opened, the pin-shaped member moves toward the other mold, so that it is possible to assist the mold release of the resin molded product from the mold on the pin-shaped member side.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view for explaining an embodiment of a resin mold for a transistor according to the present invention, and FIGS. 2A and 2B are sectional views for explaining the operating state of FIG. Reference numeral 10 denotes an upper die, which is also a movable die movable in the vertical direction. 1 and 2, the upper mold 10 includes a first upper mold member 11 and a second upper mold member 1.
2. It is composed of a movable pin 20 and a spring 25. The first upper mold member 11 is a plate-shaped member that constitutes the lower part of the upper mold 10, has a cavity 14 formed therein, and has a through hole through which the movable pin 20 is reciprocally slidably movable in the vertical direction. Portion 16 is provided. The second upper mold member 12 is a plate-shaped member that constitutes the upper part of the upper mold 10, and contacts the upper surface of the movable pin 20 to make contact with the movable pin 20.
A recess 18 is formed to receive the spring 25 that urges the spring downward.

The movable pin 20 has a tapered front end portion and a flange-shaped upper end portion 21 corresponding to a rear end portion. The rear end surface (upper end surface) of the movable pin 20 is in contact with the lower end of the spring 25. It is touched. Further, the flange-shaped upper end portion 21 is formed to have a larger diameter than the through hole 16,
Thereby, the movable pin 20 is regulated so as not to move below a predetermined range. Reference numeral 30 denotes a lower mold, which has a cavity surface with which the tip of the movable pin 20 contacts, on its upper surface. By the way, as shown in FIG. 1, when the mold is closed, the movable pin 20 moves its uppermost end against the urging force of the spring 25 by contacting the tip surface of the movable pin 20 with the cavity surface of the lower mold 30. Even in the
The tapered portion is formed so as not to enter the through hole 16. In this embodiment, the spring 25 is a spiral spring, but the elastic member for urging the movable pin 20 downward is not limited to this, and an elastic member such as a leaf spring or elasticity of compressed air may be used. May be used.

The operation of the present invention having the above construction will be described with reference to FIG.
It will be described below based on. As shown in FIG. 2 (A),
When the mold is opened, the movable pin 20 is urged downward by the spring 25 so that its tip projects beyond the parting line, and is locked to the upper mold by the flange-shaped upper end 21. ing.

Next, when the mold is closed, as shown in FIG.
As shown in (B), the movable pin 20 provided on the upper mold 10 abuts the upper surface, which is the cavity surface of the lower mold 30, with its tip end surface and moves upward against the biasing force of the spring 25. The movable pin 2 is moved by the urging force of the spring 25.
0 and the lower mold 30 are in close contact with each other with a predetermined biasing force or more. In this state, the molten resin is filled with the cavity 1
When the transistor is resin-sealed by being introduced into the through-hole 4, the through hole can be preferably formed in the resin molding portion of the transistor device. That is, since the movable pin 20 and the lower mold 30 are preferably in close contact with each other, there is no gap between them and a thin portion and a burr portion do not occur. Therefore, the step of removing the thin portion can be omitted.

Further, since the movable pin 20 moves toward the lower mold by the urging force of the spring 25 when the mold is opened,
The ejector pin can be assisted in order to release the resin molded product from the upper mold 10. In particular, since the transistor device having the cross-sectional shape as shown in FIGS. 1 and 2 has a large area in contact with the cavity surface of the upper mold, the mold releasing from the upper mold separates from the lower mold. Harder than. Therefore, the movable pin 20 of the present invention is very effective as compared with the case of assisting the mold release from the lower mold as in the prior art of FIG.

Further, in order to form a suitable through hole without resin burrs in the resin-sealed transistor device, only the movable pin 20 and the spring 25 need be set in the upper mold 10. Therefore, the structure of the mold can be simplified as compared with the conventional technique shown in FIG. Further, when resin molding of a transistor device having a through hole is carried out by the molding die according to the present invention, the parting line of the die over the through hole is the upper surface of the lower die, and the lower die movable pin is It does not leave behind a movable pin as it does when used. In the embodiment described above, the movable mold is the upper mold and the fixed mold is the lower mold, but they may be opposite, and it is needless to say that the directionality of the mold can be variously selected. That is. Although various preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. That is.

[0014]

According to the resin mold for transistors of the present invention, when the mold is closed, the elastic member brings the pin-shaped member and the lower mold into close contact with each other with a biasing force of a predetermined value or more. . If molten resin is introduced into the cavity in this state, it is possible to form a through hole having no thin portion in the resin molded portion of the transistor device. Since the pin-shaped member can move toward the other mold when the mold is opened, it is possible to assist the mold release of the resin molded product from the mold on the pin-shaped member side. Therefore, according to the present invention, the resin molding portion of the transistor device can be provided with a suitable through hole that does not need to remove a thin portion or the like in a later step, and the resin molding product can be molded from the die on the pin member side. It has a remarkable effect that the mold releasability of can be improved. Further, since only the elastic member for urging the pin-shaped member in the other mold direction is added, there is an advantage that the structure of the mold is simple.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a resin mold for a transistor according to the present invention.

FIG. 2 is a cross-sectional view illustrating a working state of the embodiment of FIG.

FIG. 3 is a sectional view showing a conventional technique.

FIG. 4 is a sectional view showing another conventional technique.

[Explanation of symbols]

 10 Upper Mold 11 First Upper Mold Member 12 Second Upper Mold Member 14 Cavity 16 Through Hole 18 Recess 20 Movable Pin 21 Flanged Upper End 25 Spring 30 Lower Mold

Claims (1)

[Claims] 1. A pin-shaped member having a movable mold and a fixed mold, wherein one mold has a tip protruding into a cavity so as to form a through hole in a resin molded part of a resin-sealed transistor device. In the resin mold for a transistor provided with, the pin-shaped member is reciprocally fitted in the one mold within a predetermined range, and is urged toward the other mold by an elastic member, When the mold is closed, the tip of the pin-shaped member contacts the cavity surface of the other mold and is moved against the biasing force of the elastic member, and the elastic member causes the pin-shaped member and the other mold to move. A resin mold die for a transistor, wherein the die and the die come into close contact with each other with a predetermined urging force.