JP2690662B2 - Mold for semiconductor device 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 semiconductor device encapsulation mold for encapsulating a semiconductor device with a resin to form a resin shell, and more particularly to a mold for molding the resin shell of the semiconductor device. The present invention relates to a semiconductor device sealing mold (hereinafter referred to as a mold at the end).

[0002]

2. Description of the Related Art FIGS. 2 and 3 are a sectional view of a mold for explaining an example of a conventional mold and a partial view of the mold shown in order of operation. Conventionally, this type of mold forms a cavity 8 by forming an upper mold 2 having a recess and a cull portion 10 on the surface and a recess facing the recess of the upper mold 2 as shown in FIG. 2, for example. It was composed of a pot 5 into which a solid resin was put, and a lower mold 3 having a runner portion 6 through which a molten resin flows. Further, the outer diameter of the solid resin inserted into the pot 5 is formed to be smaller than the inner diameter of the pot 5 by about 1 mm so that the solid resin can easily enter the pot 5. Further, the solid resin to be inserted is supported by the plunger 9 of the molding machine, is pressed by the plunger 9 during molding, is melted by the heat of the mold, and the cull portion 1
Cavity 8 from 0 to pot 5 through runner portion 6
Is injected into. Next, the operation of this mold will be described. First, the mold is opened, the solid resin 12 is put in the pot 5, and the lead frame 4 having the semiconductor chip mounted thereon is mounted on the lower mold 3. Next, as shown in FIG. 3A, the mold is closed and the lead frame 4 is sandwiched between the upper mold 2 and the lower mold 3. Next, FIG.
As shown in, the plunger 9 is raised. As a result, the solid resin 12 held on the plunger 9 in the pot 5 is melted into the gel resin 12a, and the runner portion 6,
It passes through the gate 7 and is injected into the plurality of cavities 8.

At this time, since the molds forming the pot 5, the cavity 8 and the runner portion 6 are kept at a high temperature of about 180 ° C., the injection of the gel-like resin 12a into all the cavities 8 is completed, When the inside of the cavity 8 is filled with the gel-like resin 12a, the heat from the mold 1 is received and the curing is accelerated. When this curing is completed, a resin outer shell that encloses the semiconductor chip and the lead frame 4 is formed.

As described above, in the conventional mold, the solid resin 12 charged in the pot 5 is melted to form a gel resin 12a,
The gel-like resin 12a was forcibly injected into the plurality of cavities 8 by the plunger 9.

[0005]

FIG. 4 is a partial plan view of the lower mold showing a state where resin is injected into each cavity.
In this conventional mold, as described above, when the solid resin 12 is inserted into the pot 5, it is often inserted to one side of the inner wall surface of the pot 5 while being offset. For this reason, the solid resin 12 near the inner wall surface of the pot 5 is melted and becomes a gel, and the gel-like resin supplied by the pressing of the plunger 9 is biased, as shown in FIG. It is injected first from the cavity 8 on the right side.

[0006] When the solid resin 12 thus charged is offset in the pot 5, the resin injection rate into each of the plurality of cavities 8 varies, and the cavity 8 having a slow injection rate is gel-like. The curing of the resin 12a is promoted,
Hard resin is injected. Therefore, there is a problem that the metal wire bonded to the semiconductor chip is deformed or broken.

An object of the present invention is to uniformly heat and melt a solid resin and then inject the solid resin into the cavities so as to make the degree of curing of the resin injected into each cavity uniform and to seal the resin without causing deformation or disconnection of the metal wire. It is to provide a die that can be stopped.

[0008]

In the mold of the present invention, an upper die having a plurality of depressions arranged side by side around a cull portion and a depression forming a cavity corresponding to the depression of the upper die are formed. And a lower mold in which a central hole and a runner portion communicating with this cavity are formed, and a cylindrical pot that slides in one direction in the central hole and has a sloping surface at the tip toward the inside, A spring member that applies a repulsive force to the one direction is provided at the rear end of the pot, and when the solid resin is put into the pot, the tip of the pot is pressed against the cull portion, and the plunger is melted after the solid resin is melted. The tip of the pot is separated from the cull portion by the pressing force, and the molten resin is injected into the runner and the cavity from the gap.

[0009]

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

1 (a) to 1 (c) are partial sectional views showing an embodiment of the mold of the present invention in the order of operation. As shown in FIG. 1, this mold has a cull portion 10 of the upper mold 2 when the mold is closed.
The pot 5a slides into the sliding hole 13 so as to close the space between the lower mold 3 and the lower mold 3.
Slide in the pot 5a for this sliding
The spring 1 is provided on the flange 7 to give a repulsive force. That is, a valve mechanism for determining whether or not the gel-like resin can be injected into the runner and the cavity is provided.

First, the valve mechanism is eleventhly the pot 5a.
A sliding hole 13 for sliding the flange 7 is formed, the spring 1 is inserted into this sliding hole 13, and a taper portion is provided at the tip of the pot 5a in consideration of the spring constant of the spring 1.

Next, the operation of this mold will be described.
First, as described in the conventional example, the solid resin 12 is put into the pot 5a. At this time, the pot 5a is in the raised position due to the repulsive force of the spring 1. The tip of the pot 5a and the cull portion 10 have a gap (0.0
5 to 0.06 mm). This gap is inevitably formed by unevenness at the tip.

Next, when the plunger 9 is raised, the solid resin 12 pushed by the plunger 9 tries to flow out to the runner portion 6 from the portion where gelation is progressing due to the heat of the mold, but the pot 5a. Since the entrance to the runner portion 6 is blocked by, the gel resin 12a collects in the holes 6 formed by the pot 5a and the upper mold 2, as shown in FIG. 1 (b). At this time, the air in the holes flows out through the gap.

Next, when the plunger 9 is raised, a component force acts on the tapered portion of the pot 5a due to the pressure applied to the gel-like resin 12a, the spring 1 contracts, and the pot 5a descends. Then, the reaction force received by the taper portion causes the pot 5a.
2C, the gel-like resin 12a passes through the runner portion 6 and the gate 7 and the respective cavities 8 as shown in FIG.
Injected into

By performing the valve operation by the gel-like resin injection pressure of the pot 5 in this way, the solid resin 12 at the time of introduction is
The problem caused by the deviation of the position is solved, the filling rate of the gel resin 12a into each cavity 8 becomes uniform, and the deformation and disconnection of the metal wire and the variation in sealing quality in each cavity are eliminated.

[0016]

As described above, according to the present invention, a mechanism for lowering the pot by the injection pressure of the molten resin and opening the opening to the runner portion of the pot is provided, and after the solid resin is completely gelled, the runner and By injecting the solid resin into the pot, the uneven filling of the cavity due to the deviation of the position when pouring the solid resin is eliminated, the injection speed of the gel resin into each cavity is made uniform, and the metal wire is not deformed or deformed. There is an effect that each cavity is uniformly sealed without causing disconnection.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing the order of operations in an embodiment of a mold of the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional mold.

FIG. 3 is a partial cross-sectional view showing the order of operations in the mold of FIG.

FIG. 4 is a partial plan view of a lower mold showing a state where resin is injected into each cavity.

[Explanation of symbols]

 1 Spring 2 Upper Mold 3 Lower Mold 4 Lead Frame 5, 5a Pot 6 Runner Part 7 Gate 8 Cavity 9 Plunger 10 Cull Part 11 Units 12 Solid Resin 12a Gel Resin

Claims (1)

(57) [Claims] 1. An upper die having a plurality of depressions formed side by side around a cull portion, a depression forming a cavity corresponding to the depressions of the upper die, and a central hole and a runner communicating with the cavity. A lower mold in which a part is formed, a cylindrical pot that slides in the central hole in one direction and has a slanted surface at the tip toward the inside, and a rear end of the pot in the one direction. A spring member for giving a repulsive force is provided, and when the solid resin is put into the pot, the tip of the pot is pressed against the cull portion, and the solid resin is melted and then pressed by the plunger. A mold for sealing a semiconductor device, characterized in that a tip portion is separated from the cull portion, and molten resin is injected into the runner and the cavity from the gap.