JPS6141515A - Plunger for transfer molding machine - Google Patents

Abstract

PURPOSE:To make it possible to produce a tough plunger with the sliding section thereof excellent in abrasion resistance, by making a plunger main body of a steel, making a section of a ceramic that will slide along a sleeve, and joining said section to the tip of the plunger main body. CONSTITUTION:A plunger has a sliding section 12 that will slide along the inner wall of a sleeve, is in the shape of a round rod having an outer diameter of 43mm. and a length of 27mm. and is made of Al2O3.ZrO2 ceramic. The sliding section 12 has a projection 15 that is fitted by shrink-fitting integrally to a fitting hole 14 formed in one end of the plunger main body 13 of SCM440 that has been hardened and tempered. Therefore, the sliding section 12 of the plunger is excellent in abrasion resistance and the main body 13 is tough. Pin holes 18 and 19 are formed in the plunger main body 13 and the projection 15 respectively and are aligned and a bolt 16 is inserted into the holes 18, 19 and is secured by a nut 17. As a result, a plunger that would become defective due to abrasion would be obviated, and the yield of the production can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention mainly relates to a plunger used in a transfer molding machine for resin sealing of semiconductors.

[Techniques for promoting rice]

FIG. 4 is a sectional view of a main part showing the state in which the transformer 17 is used.

In FIG. 4, the sleeve 1 is connected to an upper mold 6 and this upper mold 6.
It is inserted into a hot plate 5 for heating, and is positioned and fixed by a 7 flange 3 protruding from its outer periphery. The plunger 2 is slidably fitted into the sleeve 1, and pushes out the melted resin 4 inserted into the sleeve 1, filling it into the cavity 9 from the resin channel 8 on the lower mold 7 side, and fills the cavity 9. The semiconductor inserted inside is sealed with resin.

Since the plunger 2 continues to extrude the resin 2, it is subject to severe wear due to sliding against the inner wall of the sleeve 1. For this reason, plungers for transfer molding machines have traditionally been made of 5KD, which is mainly steel for cold molds.
-11 is hardened and tempered, and the surface is further plated with hard chrome.

[Problem that the invention seeks to solve]

In general, the resin used for sealing semiconductors contains a large amount of Wi-free fillers such as quartz lath powder and alumina powder. Even in jars, the sliding surface with the inner wall of the sleeve and the bottom part are subject to significant wear. Of course, the inner wall of the sleeve also wears out.

If the sleeve or plunger wears out, resin may leak from the gap between the sleeve and plunger during molding, making it impossible to apply sufficient pressure, or air may become trapped, causing air bubbles to be drawn into the semiconductor sealing area. This is the cause of product defects.

To improve the wear resistance of the plunger, Al2O3
” It is effective to use a plunger made of ceramics such as ZrO2, ALO3, SiC, or Si3N.However, a single ceramic plunger is expensive, and ceramics have poor toughness, so If the single plunger 2 shown in which the sliding portion 10 is integrally formed is improperly attached to the molding machine main body (not shown), the mounting screw 11 may be chipped.

An object of the present invention is to provide a strong plunger whose sliding portion has excellent wear resistance and contributes to an improvement in product yield.

[Means for solving problems]

As shown in FIGS. 1 to 3, the plunger of the present invention has a plunger body 13 made of steel and has a screw 11 for attaching it to a transfer molding machine, and a sliding part 1 with a sleeve.
2 is made of ceramics, and the sliding portion 12 is joined to the tip of the plunger body 13 to form an integral body.

[Example 1] A first embodiment will be explained with reference to FIG.

In the plunger of this embodiment, the sliding part 12 that slides on the inner wall of the sleeve is a round bar made of Al2O3 ZrO2 ceramics with an outer diameter of 431I1m and a length of 27mm, and the protruding part 15 on the right side is hardened. Tempered 80M4
A fitting hole 14 provided at one end of the plunger body 13 of 40
It is fitted by shrink fitting and integrally joined.

Therefore, the sliding portion of the plunger has excellent wear resistance, and the main body 13 is strong.

[Example 2] FIG. 2 shows a second embodiment of the invention.

, -3- In the plunger of this embodiment, after the sliding part 12 is integrally joined to the main body 13 by shrink fitting as in the first embodiment, the plunger is further fitted with the plunger main body 13 and protrudingly. Installation part 1
Pin holes 18 and 19 are provided in series at the fitting portion with 5, and a bolt 16 is inserted through these and fixed with a nut 17.

By doing so, it is possible to prevent the sliding portion 12 made of ceramic from being pulled out in the axial direction during operation of the plunger.

[Embodiment 3] The plunger of the embodiment shown in FIG. 3 is fixed by a screw 20 provided on the plunger body 13 instead of the bolt 16 explained in the second embodiment. This is what I did.

By doing so, the number of parts can be reduced and fixing can be facilitated.

In each of the above embodiments, the ceramic part is made of Al2O3・Z
-4- Although the explanation has been made regarding the use of r0z ceramics, other ceramics such as A1203.5iCSSi3N4 may be used.

In addition, although the description has been made regarding the main body made of 80M440, it is also possible to use other steel materials such as Ni-Cr-Mo structural steel or steel for cold-opening molds. Although the joining is shown as an example of joining using shrink fit or bolts, other joining mechanisms may be used, as long as it is a method that firmly joins. Any of these can produce the effects of the present invention.

〔Effect of the invention〕

As described above, the plunger of the present invention is made of a steel main body and a ceramic sliding part joined together, so it is strong and has excellent wear resistance.

Therefore, it greatly contributes to eliminating product defects caused by wear and improving product yield.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are partially sectional front views showing embodiments of the present invention, Figure 4 is a sectional view of essential parts showing how the transfer molding machine is used, and Figure 5 is It is a front view of a single plunger. 1 Ni-sleeve, 2 Ni-blunger, 4: Ceramics, 12: Sliding part, 13 Ni-blunger main body, 14: Fitting hole, 15: Protruding part Patent attorney Takashi Honma -7- Figure 7 Figure 2 Figure 3 iU / 4 Procedural amendment (1 button 1925, month 3v day

Claims (1)

[Claims] A plunger for a transfer molding machine that is slidably inserted into a sleeve, characterized in that a sliding part made of ceramic is bonded to the tip of the plunger body made of steel. Machine plunger.