JPH05190732A - Leadframe for fully molded type transistor - Google Patents

Abstract

PURPOSE:To eliminate problems such as the occurrence of a void or non-filling at an area where it is difficult for a resin to enter by causing a flow of resin to be balanced on both surfaces when a leadframe is set in a cavity while it is displaced to one internal surface side of the cavity. CONSTITUTION:A leadframe for use with a fully molded type transistor is molded by pouring a resin through a gate 18 while a heat sink 10 is displaced to an internal wall within a cavity which is perpendicular to the direction of pouring of the resin from the gate 18. In such a leadframe, in order to forcedly introduce injected resin into the space between the heat sink 10 and the internal wall of the cavity by interrupting the flow of the resin injected from the gate 18, a wing 20 for changing the direction of pouring of the resin is disposed upright on the end of the heat sink 10 which is opposite to an inlet port of the gate 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for a full mold type transistor.

[0002]

2. Description of the Related Art FIGS. 2 and 4 show a conventional method of resin-sealing a lead frame used for manufacturing a full-mold type transistor. This transistor product is a product having a large heat dissipation plate 10, and is a product molded by resin so that the heat dissipation plate 10 is embedded in a resin molding portion. 12
After mounting the semiconductor element on the heat dissipation plate 10 with the connecting lead, is connected to the semiconductor element and resin-molded. The lead frame shown in FIG. 4 is a product having a top rail 14, and the lead frame shown in FIG. 2 is a product having no top rail. 2 (a) and 4 (a) are plan views and FIG.
4 (b) and 4 (b) are side views. These lead frame products are characterized in that the heat radiating plate 10 is resin-molded close to the outer surface of the molding resin as shown in FIGS. 2 (b) and 4 (b).

[0003]

When the above lead frame product is resin-molded, the gate 18 is arranged on the edge side of the heat sink 10 opposite to the side on which the leads 12 are arranged, as shown in FIGS. Then, resin is injected from the side surface in the thickness direction of the cavity to mold. By the way, in the above-mentioned lead frame product, since the heat dissipation plate 10 is resin-molded extremely close to the inner wall surface of the lower side of the cavity, the upper side of the heat dissipation plate 10 has a wide space with the inner wall of the cavity, and the resin is injected from the gate 18. Comparing the resin flows on the upper surface side and the lower surface side of the heat dissipation plate 10 at this time, the resin flow on the upper surface side of the heat dissipation plate 10 is good, while the resistance to the resin flow on the lower surface side of the heat dissipation plate 10 is greater. The resin flow is restricted.

In the product of the above-mentioned conventional example, the thickness of the lower surface of the heat sink 10 is 0.2 to 0.5 mm, which is very thin. As described above, the resin injection balance between the upper surface and the lower surface of the heat sink 10 is disturbed, so that the heat sink is dissipated. Problems such as unfilled resin, pinholes, voids, and weld marks occur in the thin portion of the lower surface of 10. Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to form a thin wall portion by offsetting the lead frame to one wall surface side in the cavity and performing resin molding. An object of the present invention is to provide a lead frame used for a resin-molded product, which is capable of suitably solving the problems that resin is not filled or pin poles are generated in a thin portion.

[0005]

The present invention has the following constitution in order to achieve the above object. That is, in a lead frame for a full-mold type transistor, in which a heat sink is eccentrically arranged on one inner wall surface of the cavity on the side orthogonal to the resin injection direction from the gate, and resin is injected from the gate and molded, a At the edge of the heat dissipation plate facing the inlet, the resin injection direction is set so as to forcibly introduce the injection resin between the heat dissipation plate and the cavity inner wall by blocking the flow of the resin injected from the gate. The feature is that the wings for changing are set up.

[0006]

The wing is provided upright on the edge of the heat dissipation plate so that the resin injected from the gate into the cavity disperses the flow direction of the resin when the wing is placed, and is arranged close to one inner wall of the cavity. It works so as to force the resin into the gap between the heat sink and the cavity. As a result, the flowability of the resin on the side close to the inner wall surface of the cavity can be improved, and it is possible to prevent unfilling of the resin and generation of voids.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing a state of resin-molding an embodiment of a lead frame for a full-mold type transistor according to the present invention. In the figure, 10 is a heat sink and 12 is a lead. The heat dissipation plate 10 is formed lower than the leads 12 as in the conventional example, and is disposed close to the inner wall surface below the cavity in a state of being set in the molding die. Reference numeral 18 is a gate, and 16 is a resin mold portion. The gate 18 is arranged on the edge side of the heat dissipation plate 10 opposite to the side on which the leads 12 are arranged, and the resin injection port opens toward the edge of the heat dissipation plate 10.

Reference numeral 20 is a wing standing on the edge of the heat sink 10 facing the gate 18. Heat sink 10 of the embodiment
Is bent so as to be lifted up to the same height as the lead 12 on the side of the edge facing the gate 18, and the edge is formed as a narrow flat surface. The wing is provided at the edge of the flat surface portion of this edge portion, and is provided in a U-shape when viewed from the top so as to surround the protruding edge portion of the heat dissipation plate 10 and both side edges of the flat portion. The height of the wing 20 is such that the upper end surface and the inner wall surface above the cavity are slightly vacant.

The wing 20 is provided for the purpose of blocking the injected resin from directly entering the upper surface of the heat dissipation plate 10 when the resin is injected from the gate 18 into the cavity for resin molding. Is. As described above, the wing 20 faces the inlet of the gate 18.
Since the resin injected from the gate 18 once hits the wing 20 and the flow direction is dispersed,
The heat is dissipated into the upper surface side and the lower surface side of the heat dissipation plate 10 and gradually filled in the cavity. By providing the wings 20, the resin flow on the upper surface side of the heat dissipation plate 10 is suppressed, whereby the resin is forcibly guided to the lower surface of the heat dissipation plate 10, and the thin portion on the lower surface side of the heat dissipation plate 10 is also connected to the upper surface side. Equally resin filled. In this way, unfilled resin occurs in the thin part,
It is possible to eliminate the problem that a void is generated.

FIG. 3 shows an embodiment in which wings 20 are provided on the conventional lead frame shown in FIG. Also in the heat dissipation plate 10 of the lead frame of this embodiment, the edge side on the side where the gate 18 is arranged is bent in a raised shape, and the wings 20 are provided upright on the edge of the flat surface portion. Since the heat sink 10 and the top rail 14 are connected by the hanging pins 22, the wing 20 has a window portion between the hanging pins 22 and the top rail 14 and a flat surface portion of the edge of the heat sink 10. It is provided on the edge. The wing 20 can be formed, for example, in the form of a protrusion in the shape of a lead frame in plan view, and can be formed by bending this into a rising shape.

Also in the case of the lead frame of this embodiment, as in the case of the above-mentioned embodiment, the wing 20 is provided at the end portion of the heat dissipation plate 10 so that when the resin is injected from the gate 18, the resin injected into the wing 20 is injected. Therefore, the resin flow acts to disperse the resin flow, suppresses the resin flow on the upper surface of the heat dissipation plate 10, and forces the resin to enter the lower surface side of the heat dissipation plate 10. Problems such as filling and void generation can be solved.

As described above, in the lead frame of this embodiment, the radiating plate is provided with wings for suppressing the resin flow, and the resin flow to the radiating plate close to the inner wall of the cavity and the gap between the cavity is forced. Therefore, problems such as non-filling of resin and generation of voids in the thin portion can be effectively eliminated. Further, the lead frame is provided with wings on the heat radiating plate to balance the resin flow, and has an advantage that the structure of the lead frame is not particularly complicated and the lead frame can be easily manufactured. Although the present invention has been variously described with reference to the preferred embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the invention. Absent.

[0013]

According to the lead frame for a full-mold type transistor according to the present invention, as described above, in the case of a full-mold type transistor, the thin portion of the back surface portion of the heat radiating plate, which is particularly apt to be filled with resin and voids, is thin. It is possible to effectively fill the portion with resin, and it is possible to eliminate manufacturing problems such as defective molding. Further, since the wing is formed on the heat sink by a simple method, the lead frame can be manufactured easily and effectively and effectively.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment in which a lead frame for a full-mold type transistor is resin-molded.

FIG. 2 is an explanatory diagram showing a conventional example in which a lead frame for a full-mold type transistor is resin-molded.

FIG. 3 is an explanatory view showing another embodiment in which a lead frame for a full-mold type transistor is resin-molded.

FIG. 4 is an explanatory diagram showing a conventional example in which a lead frame for a full-mold type transistor is resin-molded.

[Explanation of symbols]

 10 Heat Sink 12 Lead 14 Top Rail 16 Resin Molding Part 18 Gate 20 Wing 22 Hanging Pin

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[Procedure amendment]

[Submission date] December 25, 1992

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[Figure 4]

Claims (1)

[Claims] 1. A lead frame for a full mold type transistor, wherein a heat radiating plate is eccentrically arranged on one inner wall surface of a cavity on a side orthogonal to a direction of resin injection from a gate, and resin is injected from the gate and molded. At the edge of the heat dissipation plate facing the injection port of the gate, a resin is injected to forcibly introduce the injection resin between the heat dissipation plate and the cavity inner wall by blocking the flow of the resin injected from the gate. A lead frame for a full-mold type transistor, in which a wing for changing the injection direction is provided upright.