JPS6158707A - Plunger for multiplunger type resin molding device - Google Patents

Abstract

PURPOSE:To obtain a plunger suitable for a high durability, multiplunger type resin mold device by composing the tip section of the plunger of silicon nitride ceramics. CONSTITUTION:A plunger is composed of the tip section 8 of silicon nitride ceramics and the main section 9 of metal. The tip section 8 is composed of the head section 8A of large diameter of a plunger head and the insert section 8B of small diameter projected at the back, the insert section 8B is inserted into the hole 9A of the main body section 9 to combine them integrally. The wear resistance of the plunger becomes higher, necessary replacement frequency is lowered remarkably and the workability of the molding device increases.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention is a multi-plunge 1! The present invention relates to a plunger for a resin molding device, and particularly to a plunger that has much higher wear resistance than conventional products.

[Technical Background of the Invention] Transfer molding equipment used for resin-sealing electronic components such as semiconductor devices is usually of the single pot single plunger type, but recently a part of the runner between the pot and the cavity has been removed. Multi-pot, multi-plunger types are now being adopted.

The general structure and operation of a known multi-plunger type resin molding device related to the present invention will be described with reference to FIGS. 5 to 7. In Figures 5 to 7, Figure 5 is a perspective view of the upper mold, Figure 6 is a plan view of the lower mold, and Figure 7 is a perspective view of the upper mold.
The figure is a cross-sectional view of the upper mold and the lower mold during molding.

In the figure, 1 is an upper mold, and 2 is a lower mold, and a plurality of culls 3, a gate 4 communicating with the culls 3, and a gearability 5 are formed on opposing surfaces of both. Also,
The upper mold is provided with a plurality of cylindrical pots 6 that communicate with each cull 3, and a plunger 7 that moves up and down is inserted into each pot 6. The mold is for molding a resin envelope portion of a resin-sealed semiconductor device, and the shape of the cavity 5 is the shape of the envelope portion of a resin-sealed semiconductor device.

During molding, the curing temperature of the molding resin (for example, 180°C
While heating the upper and lower molds to a certain temperature, the lead frame F on which the semiconductor chip is mounted in advance is placed on the lower mold 2 as shown in Fig. 7, and the lower mold 2 is raised to open the mold. Perform tightening. Next, as shown in FIG. 5, a short cylindrical resin tablet T is inserted into each pot 6 from the upper opening of each pot 6, and the plunger 7 is inserted into each pot 6 while melting the resin tablet T. The pressure of the plunger 7 causes the molten resin to pass through the cull 3 and the gate 4 into the cavity 5.
Press fit inside. After filling the cavity 5 with the molten resin, the resin is kept under pressure for a certain period of time to harden, and then the plunger 7 is raised to remove the pressure, and then the mold is opened and integrated with the lead frame F. Remove the molded product from the mold.

In the multi-plunger type resin molding device as described above, the plunger is made of hardened die steel,
It was made of materials such as high-speed steel or powdered high-speed steel, and 1-Ya was used on its surface.

[Problems in the Background Art] The multi-plunger type resin mold described above has a cycle speed that is 4 to 5 times faster than the conventional single pot single plunger type resin mold machine (
Since molding is performed at a rate of about 60 seconds/cycle), conventional plungers such as those described above wear extremely quickly and have a short lifespan (for example, about 1 to 14 days).

This has caused the following problems.

(i) Since II wears quickly, the clearance between the inner peripheral surface of the pot and the outer peripheral surface of the plunger increases, resin enters this clearance, and the frictional resistance of the plunger rapidly increases, resulting in resin flowing into the cavity. The filling pressure decreases, leading to molding defects due to insufficient filling and molding defects due to the formation of cavities, which deteriorates the product yield of semiconductor devices.

(11) The resin that got into the clearance between the pot and the plunger peeled off, creating a large amount of [resin scum].
This "resin scum" may adhere to sensors installed inside the mold or equipment, interfering with the normal operation of the sensors, etc., and as a result, causing failure of the equipment and causing damage to the equipment. It was reducing the operating rate.

(iii) Since the plunger is frequently replaced, a large number of spare plungers must be manufactured in advance, resulting in high running costs for the device.
Furthermore, since the operation of the device is stopped every time the plunger is replaced, the operating rate of the device is low, which also causes high running costs of the device.

(1v) As mentioned above, multi-plunger type resin molding equipment equipped with conventional plungers has low productivity due to low operation rate and poor product yield, which hinders productivity improvement in semiconductor device manufacturing. This was one of the factors.

[Object of the invention] The object of the invention is to eliminate the above-mentioned problems.
An object of the present invention is to provide an improved plunger that is much more durable than conventional plungers.

[Summary of the Invention] The improved plunger according to the present invention is characterized in that its tip portion is made of silicon nitride ceramic material. The inventor of the present invention confirmed from the results of various experiments that silicon nitride ceramic has the best wear resistance, and utilized this fact to complete the plunger of the present invention. It has been revealed that the plunger of the present invention is most suitable for multi-plunger type resin molding equipment, and greatly improves the performance and operating rate of the equipment.

[Embodiments of the Invention] Examples of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows a plunger according to a first embodiment of the present invention, and the plunger of the present invention consists of a tip portion 8 made of silicon nitride ceramic and a main body portion 9 made of metal. As shown in the figure, the distal end portion 8 consists of a large-diameter head portion 8A that serves as a plunger head and a small-diameter insertion portion 8B protruding from the rear surface of the head portion 8A. It is fitted into a hole 9A drilled in the surface, and the distal end portion 8 and the main body portion 9 are integrally connected at this portion at J3.

The insertion portion 8B and the main body portion 9 can be coupled by means such as bottom-of-the-furnace or press-fitting, or the hole wall of the main body portion 9 and the insertion portion 8B may be connected in a radial direction with respect to @lla of the plunger. The main body portion 9 and the distal end portion 8 may be connected by providing a set screw hole therethrough and screwing the set screw into the set screw hole.

FIG. 2 shows a plunger according to a second embodiment of the present invention, and the plunger of this embodiment also consists of a tip 10 made of silicon nitride ceramic and a main body 11 made of metal. The distal end portion 10 consists of a large-diameter head portion 10A serving as a plunger head and a threaded portion 10B protruding from the rear end surface. is screwed into. With this joining method, the distal end 10 can be removed from the main body 11, but if the distal end 10 is to be irremovably integrated, apply a thermosetting resin to the inner surface of the screw hole 11A of the main body 11 before joining. Then, after screwing the threaded portion 10B into the screw hole 11A, the resin may be cured by heating.

FIG. 3 shows a plunger according to a third embodiment of the present invention, and the plunger of this embodiment also includes a tip portion 12 made of silicon nitride ceramic and a main body portion 13 made of metal. The tip portion 12 has a large diameter head 12A serving as a plunger head, and a small diameter shaft portion 12B protruding from the rear end surface of the head 12A. A collar portion 12G for preventing removal is provided.

On the other hand, the main body part 13 has a hole on the tip side that fits into the shaft part 12B and the collar part 12C, and is divided into two parts along the axial line. A bolt insertion hole passing through the two parts in a direction perpendicular to the axis is formed in the part, and the two parts are integrated by a bolt 13Δ inserted into the bolt insertion hole. In addition, the head of the bolt 13A and the bolt 13
In order to prevent the nut 13B fitted into A from protruding from the outer circumferential surface of the main body 13, a counterbore portion 13G into which the head of the bolt 13A and the nut B are sunk is provided on the outer circumferential surface of the two portions.
is formed.

In the plunger having the structure shown in FIG. 3, the main body 13 is split and has a fastening assembly structure using bolts 13A, so the tip 12 and the main body 13 can be removed, and the tip Troublesome work such as shrink fitting is not required when joining the part 12 and the main body part 13.

A plunger according to a fourth embodiment of the present invention shown in FIG. 4 is the same as the other embodiments in that it has a tip 14 made of silicon nitride ceramic and a main body 15 made of metal. Part 1
The structure of No. 4 and the connection structure between the main body portion and the like are different from those of the other embodiments.

That is, the distal end portion 14 of this embodiment is configured as a cylindrical member having a stepped hole, with a large diameter first hole 14A opening at the distal end surface and a large diameter opening n'iJ opening at the rear end surface. It has a second hole 14B and a third hole 14C having a small diameter extending between the first and second holes, and the first hole 14A.
A first step is formed at the connection between the second hole 14B and the third hole 14C, and a second step is formed at the connection between the second hole 14B and the third hole 14G.

On the other hand, the main body portion 15 is provided with a small-diameter insertion portion 15A on its distal end side to be fitted into the second hole portion 14B, and a screw hole (not shown) is formed in the insertion portion 15A. Further, the distal end portion 1 is connected to the rear end surface of the insertion portion 15A.
A large-diameter collar portion 15B is formed that comes into contact with the rear end surface of 4.

The tip portion 14 and the main body portion 15 are connected to the first hole portion 14A of the tip portion.
A bolt 16 screwed into the screw hole of the insertion portion 15A from
The head of the bolt 16 and the insert
15A is integrated by pressing the distal end surface of the distal end portion 15A against the second and second step portions in the distal end portion 14, respectively.
After the tip 14 and the main body 15 are integrated with the bolt 16 as described above, a filler 17 made of ceramic filler and thermosetting resin is placed in the first hole 14'A of the tip 14.
After filling and heating and curing, the tip surface is polished flat to complete the plunge JP.

The plunger as shown in FIG. 4 is constructed in consideration of the fact that the wear portion is mainly the outer circumferential surface of the tip.

[Effects of the Invention] Table 1 shows the results of using the plunger of the present invention and the conventional plunger.

Table 1 *2 Indicates that all of the plungers that were used are no longer usable.

It can be seen that the required replacement frequency of the plunger is significantly reduced, the operation rate of the molding device is improved, and the molding yield of the product is also improved, and as a result, the running cost of the molding device is significantly reduced.

[Brief explanation of the drawing]

1 to 4 are partially cutaway side views showing an embodiment of the plunger of the present invention, and FIG. 5 is a schematic diagram of the upper mold part of a multi-plunger type resin molding device that can be equipped with the plunger of the present invention. A perspective view, FIG. 6 is a schematic plan view of the lower mold of the multi-plunger type resin mold device, and FIG. 7 is a state where the upper and lower molds of the multi-plunger type resin mold device are cut along lines vi-vi a in FIG. 6. FIG. 1... Upper mold, 2... Lower mold, 3... Cal,
4...Gate, 5...Cavity, 6...
Pot, 7... Plunger, T... Resin tablet, F... Lead frame, 8, 10, 12.
14... Tip part, 9.11, 13.15... Main body part. 11th! ! Figure 2 Figure 3 Figure 45A Figure 5 Figure 7

Claims (1)

[Claims] 1. A plunger for a multi-plunger type resin molding device, characterized in that the tip portion that contacts the resin is made of a silicon nitride ceramic material.