JP2570157B2 - Mold for resin sealing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin sealing mold for sealing a semiconductor chip such as an IC with a resin.

[0002]

2. Description of the Related Art A conventional resin molding die is composed of an upper die and a lower die which are divided into two parts.

FIG. 4 is a partial view of a lead frame with tie bars, and FIG. 2 is a partial view of a lead frame without tie bars. Each one is shown, but several of them are connected in a strip shape.

Here, a method of resin sealing will be described. The lead frame 20 on which a semiconductor chip such as an IC is mounted is placed on the lower mold 11, and the upper mold 10 is covered so that the lead frame 20 is clamped. FIG. 3 shows a mold clamping state. Next, a resin (not shown) previously charged into the pot 12 of the lower mold 11 is melted by a heating means, and is extruded by applying pressure by an injection means (not shown), and the culls 14 in the upper and lower molds 10 and 11 are removed.
The fluid flows into the cavity 1 through the runner gate 13. The cavity 1 corresponds to the semiconductor chip mounting portion of the lead frame 20, and is sealed with the resin flowing into the cavity 1. At this time, the resin leaks between the leads 21 by the thickness of the lead frame 20. This surplus resin is punched and removed in a later step. Also,
The tie bar 22 is cut. In order to omit the step of cutting the tie bar 22, a lead frame without a tie bar is used.

[0005] In the resin sealing, the depth of the engraving a for mounting the lead frame 20 provided on the lower mold 11 is made smaller than the thickness of the lead frame 20, and FIG. Thus, a gap b is formed by the difference between the thickness of the lead frame 20 and the depth a.

In this manner, the mold clamping pressure of the upper and lower dies 10, 11 is applied to the lead frame 20 as a surface pressure, and the lead frame 20 is strongly clamped.
The flowed-in resin leaks out beyond the thickness of the lead frame 20, and it is possible to prevent the resin from leaking onto the mold. Furthermore, in order to increase the surface pressure applied to the lead frame 20, a portion of the lead frame 20 which does not cause any trouble without clamping is provided with the surface pressure relief 4, so that this portion is not clamped. Is used as the lead frame clamp surface 2 to increase the surface pressure per unit area, and the lead frame 20 is more firmly clamped.

However, in the case of a lead frame without a tie bar, many parts need to be clamped, so that the surface pressure per unit area is low, so that there is a problem of insufficient press capability and resin leakage onto the mold. was there.

In order to eliminate this resin leakage, Japanese Patent Laid-Open No.
No. 137237 discloses a method in which all the internal leads of a lead frame without a tie bar are fixed with a heat-resistant insulating tape, and the upper die and the lower die are tightly fitted outside the position of the tape except for a lead through hole. Resin molding is performed using a mold.

[0009]

The structure of the conventional resin-sealing mold is disadvantageous in that it is not suitable for resin-sealing with a lead frame without a tie bar, and increases the cost due to press remodeling. JP-A-2-137237
However, there was a drawback in that the work was complicated.

An object of the present invention is to provide a resin sealing mold suitable for resin sealing of a lead frame without a tie bar.

[0011]

According to the present invention, there is provided a resin molding die, which extends to an end surface of a lead outside a clamp surface of a lead frame and is 0.005 m from the clamp surface of the lead frame.
A sub-clamp surface about m to 0.01 mm lower is provided.

[0012]

The sealed resin flows between the leads, but does not leak beyond the end faces of the leads, so that a product having no problem in terms of product quality can be obtained. Furthermore, the sub-clamp surface is 0.005 mm to 0.01 mm larger than the lead frame clamp surface.
Since the surface pressure applied to the lead frame can be increased by reducing the degree, the resin can be prevented from leaking onto the mold.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are a plan view and a cross-sectional view of a resin sealing mold according to an embodiment of the present invention. FIG.
FIG. 4 is a partial view showing one lead frame without tie bars.

The resin encapsulation is the same as the conventional example in which the upper mold 10 is covered with the lower mold 11 as shown in FIG. 3, but the lead frame clamping surface 2 is located at the position of the conventional tie bar 22. The sub-clamp surface 3 lower than the lead frame clamp surface 2 extends to the end surface of the lead 21, and the other is a surface pressure relief 4. At this time, the difference c between the lead frame clamp surface 2 and the sub clamp surface 3 is about 0.005 mm to 0.01 mm.

In this way, the sealed resin flows between the leads 21, but does not leak beyond the end faces of the leads 21, so that there is no problem in terms of product quality. Further, by making the sub clamp surface 3 lower than the lead frame clamp surface 2 by about 0.005 mm to 0.01 mm, the surface pressure applied to the lead frame 20 can be increased, so that the resin leaks onto the mold. Can be prevented.

[0017]

As described above, according to the present invention, the distance from the lead frame clamp surface is 0.005 mm to 0.01 mm.
By providing a lower degree sub clamping surfaces on the outside of the lead frame clamping surfaces, it is possible to reliably perform resin sealing without tie bar lead frame, by further lead frame clamping surface of the conventional tie bar position, the tie bar Yes The resin sealing of the lead frame has the effect of obtaining the same quality as the conventional one.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view of a resin sealing mold according to an embodiment of the present invention.

FIG. 2 is a partial view of a lead frame without a tie bar.

FIG. 3 is a cross-sectional view of a conventional resin sealing mold.

FIG. 4 is a partial view of a lead frame having a tie bar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cavity 2 Lead frame clamp surface 3 Sub clamp surface 4 Surface pressure relief 10 Upper die 11 Lower die 12 Pot 13 Runner gate 14 Cull 20 Lead frame 21 Lead 22 Tie bar

Claims (1)

(57) [Claims] 1. A resin sealing mold for sealing a semiconductor chip with a resin, wherein the mold extends outside the lead frame clamp surface to an end surface of the lead and is about 0.005 mm to 0.01 mm from the lead frame clamp surface. A resin-sealing mold having a low sub-clamp surface.