JPH01318257A - Lead frame for resin-molded electronic component - Google Patents

Abstract

PURPOSE:To prevent an air bent section from being clogged with a filler by forming tapers or curved surfaces on upper and lower opposite edges of an inside cross section of the air bent section, and mounting an electric parts element on the same and molding the same with resin. CONSTITUTION:Upper and lower edges of an air bent section 1e positioned inside the same are tapered, the air bent section 1e being located between dotted lines 21, 22 and constituting part of a lead frame 1 fraction provided along a side of a resin-sealed section 20 of the lead frame 1, the side being located opposite to the resin injection side. In a resin-sealing process, air involved in a cavity 6 and air involved in the resin are vented through a gap between an air vent section 9 of a die and the air vent section 1e of the lead frame 1. Hereby, when molten resin is injected into the cavity 6 in the die, the air is satisfactorily vented without permitting an inlet of the air vent section 1e to be filled with a filler 12. Thus, the filler can be prevented from being not filled.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the shape of the air pent part of the lead frame, the present invention provides a resin-sealed lead frame for electronic components with an improved cross-sectional shape that can be easily and easily implemented. A lead frame on which an electronic component element is mounted and sealed with a resin together with the electronic component element, wherein both upper and lower edges of the inner cross section of the air pent part of the lead frame are
It is configured to have a tapered or curved surface that is effective for removing air in the cavity of the mold for forming the resin and air contained in the resin.

[Industrial application field]

The present invention relates to a resin-sealed lead frame for electronic components, and particularly to an improvement in the shape of an air pent portion of the lead frame.

2. Description of the Related Art Lead frames for electronic components such as resin-sealed semiconductor devices are provided with an air pent portion to facilitate the flow of air within a mold to the outside of the mold during a resin-sealing process.

However, due to obstacles caused by the cross-sectional shape of the air pent portion of the lead frame, the air does not flow out of the mold smoothly, resulting in insufficient resin filling into the mold.

Under the above circumstances, there is a need for a lead frame for resin-sealed electronic components that can ensure that air inside the mold flows out of the mold during the resin-sealing process.

[Conventional technology]

A conventional lead frame for a resin-sealed electronic component will be described with reference to FIGS. 4 to 7 for a lead frame for a resin-sealed semiconductor device.

As shown in FIG. 4, the planar shape of the lead frame 1 of the resin-sealed semiconductor device is such that a die stage la is supported by a pinch bar IM at the center, and a tie bar 1d connects the die stage la to a position surrounding the die stage la, and a die stage la is connected to a tie bar 1c at a position surrounding the die stage la. The air pent portion 1e has a cross section as shown in FIG.

There are two types of molding methods for lead frames for resin-molded semiconductor devices: the etching method, in which the lead frame is formed by etching, and the stamping method, in which the lead frame is formed by punching with a mold. As shown in FIGS. 6( and 11), sharp edges are formed on both the front and back surfaces, and in the stamping method, sharp edges are formed on either side depending on the punching direction, as shown in FIG. 6(b).

In the resin sealing process, the lead frame 1 is set on a lower mold 5 as shown in FIG. 5, and the lead frame 1 is clamped between the upper mold 4 and the lower mold 5. In this state, the molten resin is injected into the runner 7 under high pressure, and is injected into the cavity 6 in the mold through the gate 8.

The upper mold 4 and the lower mold 5 of the mold are each provided with an air pent part 9 in which a groove is formed on the side opposite to the resin injection side on opposing surfaces, and when the resin is injected, this air pent part The air in the cavity 6 and the air contained in the resin are discharged from the gap formed by the groove 9.

At this time, as shown in FIG. 7, if a sharp edge is formed in the air pent part 1e of the lead frame 1 corresponding to the groove of the air pent part 9 of the mold, the filler made of silicon oxide contained in the resin will be removed. No. 12 etc. are clogged at the inlet of the air pent part and the air cannot be completely discharged, causing a defect called "unfilled".

[Problem to be solved by the invention]

In the conventional resin-sealing process for lead frames for resin-sealed electronic components as described above, molten resin is injected into the mold at high pressure, so the air in the mold cavity is exhausted to the outside of the mold. Must.

However, during the resin sealing process, the air in the mold through the air pent part cannot be smoothly discharged to the outside of the mold due to obstacles caused by the sharp-edged cross-sectional shape of the air pent part of the lead frame. There is a problem in that insufficient flow of resin into the mold causes a defect called "unfilling" and also causes a sealing defect in the subsequent stamping step.

The object of the present invention is to provide a resin-sealed lead frame for electronic components with an improved cross-sectional shape, which can be implemented simply and easily in view of the above-mentioned circumstances.

[Means to solve the problem]

The above problem is a lead frame that is mounted with an electronic component element and sealed with resin together with the electronic component element. This problem is solved by the lead frame for a resin-sealed electronic component according to the present invention, which is formed into a tapered or curved surface that is effective for removing the air in the cavity of the mold to be formed and the air contained in the resin.

[Effect]

That is, the present invention provides a lead for a resin-sealed electronic component in which a tapered or curved surface is formed on both the upper and lower edges of the inner cross section of the air pent part of the lead frame for a resin-sealed electronic component to improve the cross-sectional shape. Since electronic components are mounted on the frame and sealed with resin, fillers made of silicon oxide contained in the resin are prevented from clogging the entrance of the engineering bend, and air can be completely released. Therefore, it is possible to prevent unfilled areas from being formed in the formed resin.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5 regarding a lead frame of a resin-sealed semiconductor device.

The planar shape of the lead frame of the present invention is the same as the conventional one as shown in FIG.

In the present invention, for example, the inside of the air pent part 1e between the dotted lines 21 and 22 of the lead frame 1 portion along the side opposite to the resin injection side of the resin sealing part 20 of the lead frame 1 in FIG. Taper the upper and lower edges as shown in Figure 1.

To mold the edge of the front side of the air pent part 1e, the lead frame 1 is placed on the lower molding mold 11 as shown in the second threshold, and the coining part 10b of the upper molding mold 10 is used to form the lead frame 1. It can be performed at the same time as a process called coining in which the surface of the die stage 1a is lower than the surface of other parts of the lead frame 1. It can be formed by applying pressure to the sharp edge of the portion 1d to eliminate this edge.

In the resin sealing process, the lead frame 1 is set on a lower mold 5 as shown in FIG. 5, and the lead frame 1 is clamped between the upper mold 4 and the lower mold 5. In this state, the molten resin is injected into the runner 7 under high pressure, and is injected into the cavity 6 in the mold through the gate 8. At this time, the air in the cavity 6 and the air contained in the resin are discharged through the gap between the air pent part 9 of the mold and the air pent part 1e of the lead frame 1.

When the air pent portion 1d of the lead frame 1 is processed in this way and a taper is formed in its cross section, the lead frame 1
When pouring the resin into the mold and injecting the molten resin into the cavity 6 in the mold, the filler 12 does not clog the inlet of the air pent part 1e and the air is sufficiently discharged, as shown in FIG. , it becomes possible to prevent the formation of unfilled areas.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, by adding an extremely simple process to the air pent part of the lead frame, it is possible to prevent the filler from clogging the air pent part, and to completely exhaust the air in the mold. It becomes possible to
It has advantages such as being able to prevent the formation of unfilled areas, and can be expected to have significant economical and reliability-improving effects, making it extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an air pent part of a lead frame according to an embodiment of the present invention, FIG. 2 is a side sectional view schematically showing the structure of a mold forming the air pent part of the present invention, and FIG. 3 is a lead frame according to an embodiment of the present invention. Fig. 4 is a plan view of the lead frame; Fig. 5 is a side sectional view showing the lead frame set in the mold; Fig. 6 is a conventional lead frame. FIG. 7 is a side sectional view showing details of the air pent portion of a conventional lead frame. In the figure, 1a is a lead frame, 1a is a die stage, 1b is a pinch bar, 1c is a lead, 1d is a tie bar, 1e is an air pent part, 2 is a semiconductor chip, 3 is a wire, 4 is an upper die, 5 is a lower die, 6 is a cavity, 7 is a runner, 8 is a gate, 9 is an air pent part, 10 is a molding upper mold, 10a is a taper part, 10b is a coining part, 11 is a molding lower mold, 12 is a filler. FIG. 1 is a cross-sectional view showing the air pent portion of a lead frame according to an embodiment of the present invention. FIG. Side sectional view Figure 3 Plan view of the lead frame Figure 4 Side sectional view showing the lead frame set in the mold Figure 5 Fat etching method (1)) Stamping method Cross section showing the air pent part of a conventional lead frame m36
figure

Claims (1)

[Claims] A lead frame on which an electronic component element is mounted and sealed with a resin together with the electronic component element, wherein both upper and lower edges of the inner cross section of the air pent part (1e) of the lead frame (1) are sealed with the resin. A resin-sealed electronic device characterized by being formed into a tapered or curved surface that is effective in removing the air in the cavity (6) of the mold (4, 5) forming the mold and the air contained in the resin. Lead frame for parts.