JPH03153329A - Resin mold for semiconductor device - Google Patents

Abstract

PURPOSE:To realize the uniform and smooth injection of a resin into a cavity, and to prevent the generation of non-filling and a shrinkage void by tapering a dam block in approximately parallel with a gate angle. CONSTITUTION:A gate 14 in gate-port depth of 0.2-0.6mm and gate width of 0.4-1.2mm is shaped to a bottom force 12. The angle of the gate is inclined at 10-15 deg. to a mold mating surface L. The surface of the dam block 16 of a top force 11 oppositely faced to the gate 14 is tapered at 10-15 deg. in approximately parallel with the angle of the gate. Since the taper of the dam block is made parallel with the angle of the gate, a resin injected from the gate to a cavity gradually flows into a top-force cavity and a bottom-force cavity uniformly. Consequently, molding pressure is applied equally to the resin in the top force and the bottom force, the periphery of a frame is also filled uniformly, and molding pressure simultaneously reaches to the position 18 of a gas bent and a gas is discharged easily. Resistance in a gate port is lowered and the entrainment of air is also prevented, thus reducing the generation of non-filling and a shrinkage void.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a molding device used for molding an envelope of a resin-sealed semiconductor device with a resin molding material. .

(Prior art) In a resin-encapsulated semiconductor device, a frame with a large number of semiconductor chips mounted on a lead frame is set in upper and lower mold equipment, and preheated resin molding material is passed from a pot to a runner. The material is transferred and filled into the envelope cavity through a gate, and is then pressurized and heated to be molded.

FIG. 2 shows a cross-sectional structure of one cavity in a conventional resin molding device. In the figure, 1 is an upper mold, 2 is a lower mold, and 3 is a cavity in which a picture-shaped envelope is molded. Generally, a resin injection port (gate) for injecting resin into the cavity from a runner (not shown) is formed in either the upper mold or the lower mold, and in one or two places in the cavity. In the case of Fig. 2, 4 is a gate provided on the lower mold 2, and as shown in the figure, the mold surface of the gate tl is set at a predetermined angle with respect to the entire mold assembly surface. It is formed.

This angle is called the gate angle.

On the other hand, on the upper die surface facing the lower die gate 4, there is a mechanism 5 for holding down the tie bar of the lead frame along with a bottom mating surface.
is provided, and a dam block 6 is incorporated between the groove 5 and the yi1 portion of the cavity 3. In the conventional mold device, the gate facing surface of the dam block 6 is the mold mating surface. It was made parallel to the surface, that is, on a flat surface.

The above-mentioned conventional mold apparatus has the following problems in resin molding, which will be explained with reference to FIG. 3.

If the envelope is small, that is, the cavity 3 has a small volume,
The ratio of the volume occupied by the frame 7 accommodated within the cavity to the volume of the cavity 3 increases. For this reason, when the entire cavity is filled with the resin injected from the gate 4, the resin filling becomes poor at the closest point between the frame 7 and the cavity wall, resulting in the phenomenon of unfilling or voids.

The conventional method taken to prevent this unfilling and the occurrence of cavities was to increase the size of the gate 4, but when the gate size was increased, it was difficult to cut the gate part (gate break). In some cases, part of the gate remains on the product, necessitating a removal process, and when there is no remaining gate, serious defects such as chips and cracks occur on the product.

In addition, gate angles are attached to gates 1~ as mentioned above, but since the facing dam block surface is flat, the cross-sectional area of the gate just before entering the cavity becomes narrow, and the resin absorbs the air near the gate. The air is engulfed and injected into the cavity, and this air also remains in the product as an unfilled and void phenomenon.

Such defects in conventional mold equipment are promoted by non-uniformity of resin injection within the cavity, but in conventional mold equipment, the flow is mainly to the lower mold cavity shown by thick arrow B. , the flow of resin into the upper mold cavity indicated by thin arrow A was small, and the flow of resin within the cavity was non-uniform.

(Problems to be Solved by the Invention) An object of the present invention is to provide a resin molding device that uniformizes the flow of resin in a cavity in resin sealing of a semiconductor device equipped with a planar envelope. That's true. Another object of the present invention is to provide a molding apparatus for molding a resin-sealed semiconductor device without any unfilling or voids.

[Structure of the Invention] (Means and Effects for Solving the Problems) The resin mold device of the present invention is configured such that the resin injection port (gate) provided in the upper mold or the lower mold is parallel to the gate angle. The dam block facing the gate is also tapered. By tapering this dam block facing the gate, the flow of resin, which was conventionally guided by a flat dam block (for example in the upper mold) and mainly flowed into the lower mold cavity, is greatly changed. The flow becomes uniform within the upper and lower cavities.

Additionally, since the dam block is flat, resin injection resistance at the narrow gate opening is alleviated, resulting in smooth resin flow and no air entrainment.

As a result, problems such as unfilled resin and cavities in the resin mold could be solved.

(Example) Next, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a cross-sectional view showing the main parts of a mold device according to an embodiment.

In the figure, 11 is an upper mold, 12 is a lower mold, and 3 is a cavity.

The lower mold 12 has a gate opening depth of 0.2 li to 0.6 n.
n, gate width 0.4 nn to 1.2 nn gate 14
will be provided. The gate angle is 1 with respect to the mold mating surface.
It is inclined at 0° to 159°. The surface of the dam block 16 of the upper die 11 facing the gate 14 is tapered approximately parallel to the gate angle by 10° to 15°.

Since the taper of the dam block is parallel to the gate angle, the resin injected into the cavity from the gate flows evenly into the upper and lower mold cavities.As a result, the molding pressure is equal to the upper and lower mold cavities. Evenly spread over the resin,
It was confirmed that the surrounding area of the frame was evenly filled and that the gas vent position 18 was reached at the same time, making it easy to discharge the gas.

It was also confirmed that the resistance at the gate was alleviated, eliminating air entrainment, which resulted in fewer unfilled spaces and fewer cavities.

[Effects of the Invention] According to the mold device of the present invention, since the taper of the dam block is provided almost parallel to the gate angle, uniform and smooth injection of resin into the cavity is realized, and the occurrence of unfilled and voids is realized. This dramatically reduces the number of defects caused by molding, and improves the molding yield of resin-sealed semiconductor devices.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main part showing the mold device of the present invention, Fig. 2 is a cross-sectional view of the main part showing the conventional mold device, and Fig. 3 is a diagram explaining the problems of the conventional mold device. . 1.11...upper mold, 2,12...lower mold, 3...
・Cavity, 4.14...Resin injection port (gate)
, 6.16...Dam block, 7...Frame,
L: Mold mating surface.

Claims (1)

[Claims] 1. A resin molding device for molding an envelope of a resin-sealed semiconductor device, in which a resin injection port of the molding device is provided at a gate angle on the lower mold or the upper mold, and the resin A resin molding device for semiconductor devices, characterized in that a dam block of the mold facing the injection port has a tapered structure parallel to the gate angle.