JPS5928173B2 - Plunger for transfer mold mold - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a plunger for a transfer mold mold.
In particular, the present invention provides a plunger structure to prevent molding agent from escaping.

For example, semiconductor devices, ICs, etc. whose envelopes are formed by transfer molding using synthetic resin such as epoxy resin,
There are electronic parts, etc.

A plunger used in such a transfer mold mold has conventionally been formed in the shape shown in a side view in FIG. 1a and in a top view in the same figure.

FIG. 2 is a sectional view showing a state in which the plunger 1 is attached to a transfer mold die and pressurized to the resin.

In the figure, 1 is a plunger, 2 is a mold pot, 3 is a mold base, 4 is an upper center block, 5 is a lower center block, and 10 is an example of an epoxy resin.

When pressurizing with the plunger, the clearance between the plunger and the pot adjacent to it (C1earance)
) Depending on the setting (design), there are drawbacks such as fixation or seizure of the plunger, or resin leakage as shown by the dotted arrow 10a in FIG.

Further, due to the above-mentioned problems, the operating rate and productivity of the device are lowered, and repair costs are increased.

The present invention provides a structure for improving the drawbacks of the conventional plunger for a transfer mold die.

The plunger for a transfer mold mold according to the present invention includes a cylindrical plunger body, a cap provided at one end of the plunger body so as to exert an axial displacement force, and a cap inserted between the cap and one end of the plunger body in the axial direction. It is characterized by comprising an elastic member disposed so that its outer diameter is expanded by compression of the elastic member.

Next, the present invention will be explained in detail with reference to the drawings regarding one embodiment of a plunger for a transfer mold die.

The plunger 11, which is shown in a side view in FIG. 11b, a plunger body 11c, a ring-shaped sealing member 11 made of an elastic material such as Teflon;
d. Consists of the plunger cap 11e of the terminal.

The state when this plunger 11 is attached to a transfer mold mold and pressurizing the resin is shown in FIG. 4 as a cross-sectional view. 5 is an upper mold center block, 5 is a lower mold center block, and 10 is an example of an epoxy resin.

As is clear from the figure, the present invention is significantly different from the conventional one in that the resin 10 does not leak from between the plunger and the molded pot.

This will be explained with reference to FIGS. 5 and 6, which show cross-sectional views of the plunger in detail.

Fig. 6 shows a state in which the resin is compressed (pressurized in the direction of the arrow) by the mouthpiece of the plunger, and Fig. 5 shows a state before pressurization.

In the figure, 12 is a set screw, 13 is a machine screw, and the sealing member 11d is formed into a ring shape with an outer diameter of 2, an inner diameter of d, and a thickness of T. Tighten the slope 14 with the screw 12 and machine screw 13.

At this time, depending on the degree of tightening of the second screw, the tip of the screw moves on the slope, displacing the slope, that is, the mouthpiece in the axial direction, and applying an appropriate preload to the sealing member 11d.

Note that the above-mentioned set screws and machine screws are provided at several locations on the circumference.

In addition, the plunger mouthpiece slides against the cylindrical inner wall of the plunger body, and by applying an axial load to the plunger mouthpiece, the gap L2 (t
2<tly tl is the gap when no load is applied in Fig. 5).

In other words, the inner diameter of the sealing material does not change, but the thickness changes to T2 (T1 at no load in Figure 5) and the outer diameter changes to D2 (D1 at no load) (D2>D), and the plunger and pot change. This will reduce the clearance C1.

Although the sealing member 11d is made of Teflon in the above embodiment, it may be made of elastic metal.
Alternatively, the shape may be formed of a thin metal plate into a concave ring shape that exhibits elasticity, and furthermore, the gap C1 may be formed by applying pressure.
If the effect of filling the space is insufficient, a sealing member 21d formed in a thick ring shape on the outer periphery may be used, as shown in a perspective view in FIG. 7a and a cross-sectional view in the same figure.

Also, the gap t1 between the top surface of the plunger mouthpiece and the pot is appropriately designed and selected to prevent excessive pressure from being applied to the sealing member 11d.

As described above, according to the present invention, there is no possibility that the resin in the pot leaks from between the plunger and the pot as shown in 10a in FIG. Since it is only a sealing material, there is no seizure between the plunger and the pot.

Furthermore, there are significant effects such as significantly extending the life of the plunger and pot molds.

Additionally, the above mentioned improvements have also improved operating rates and productivity.

[Brief explanation of the drawing]

1 is a side view of a conventional plunger, FIG. 2 is a sectional view showing the vicinity of the plunger in a conventional transfer molding device, and FIG. Figure a is a side view, Figure 4 is a top view, Figure 4 is a sectional view showing the vicinity of the plunger in a transfer molding apparatus according to an embodiment of the present invention, and Figures 5 and 6 are mechanisms of the plunger according to an embodiment of the present invention. FIG. 7 is a perspective view showing a sealing material according to another embodiment of the present invention, and FIG. 7 is a cross-sectional view. Note that the same reference numerals in the drawings indicate the same or corresponding parts, respectively. 11...Plunger, 11c...Plunger body, 11d, 21d...Plunger seal member, 11e...Plunger cap.

Claims (1)

[Claims] 1 A cylindrical plunger body, a cap provided at one end of the plunger body so as to be freely movable in the axial direction, and a cap inserted between the cap and one end of the plunger body whose outer diameter is reduced by compression in the axial direction. A plunger for a transfer mold mold, comprising a sealing member disposed so as to be enlarged.