JPS60244512A - Molding method - Google Patents

Abstract

PURPOSE:To prevent the lowering of the quality of a molded product caused by the mixing of air by exhausting air in a molding material, by applying ultrasonic treatment to the molding material in a runner prior to feeding the same to a cavity under pressure. CONSTITUTION:When a molding material 5 is thrown in a pot 4, it receives preparatory pressurization by a plunger 6. Subsequently, the plunger 6 is energized by an ultrasonic vibration generator 7 to apply ultrasonic vibration to the molding material 5 compressed to a proper degree. This ultrasonic vibration is propagated into the molding material 5 and air confined in the molding material is forcibly exhausted. After deaeration treatment by ultrasonic vibration, the molding material 5 is finally pressurized by the plunger 6. The molding material 5 is heated and melted by this pressurization and introduced into each cavity 3 under pressure from a gate 10 through a runner 9 to mold a non-airtight sealed package.

Description

[Detailed Description of the Invention] [Technical Field] The present invention is a technology that is effective when used in molding technology, particularly in transfer molding technology in which sealing resin is press-fitted into a mold cavity in the manufacture of semiconductor devices. Regarding.

[Background technology]

In the manufacturing of semiconductor devices, a non-hermetically sealed puff cage is formed by force-feeding synthetic resin (resin), which is used as a sealing resin, into a cavity using a plunger. A possible method is transfer molding.

However, in this transfer molding method, the air in the resin becomes bubbles and remains inside or on the surface of the non-hermetically sealed package, resulting in poor moisture resistance and poor appearance. revealed by.

A document that describes the molding process is Electronic Materials March 1982 issue, pages 124 to 128, ``Mold Industrial Robot'' (published by Kogyo Kenkyukai, March 1, 1982).

[Purpose of the invention]

An object of the present invention is to provide a molding technique that can suppress the occurrence of defects in molded products due to air bubbles inside the sealing resin.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

(Summary of the Invention) A brief overview of typical inventions disclosed in this application is as follows.

That is, by applying ultrasonic vibration to the sealing resin before press-fitting to discharge air bubbles inside the molding material, it is possible to reduce the trapping of air bubbles in the molded product.

〔Example〕

FIG. 1 is a longitudinal sectional view showing a transfer molding machine used in a molding method according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation.

In this embodiment, this transfer molding machine is equipped with an upper mold 1 and a lower mold 2 as molds that are joined to each other, and a plurality of cavities 3 are formed on the joining surface of the upper mold 1 and the lower mold 2. ing. A bot 4 is opened in a substantially vertical direction approximately in the center of the upper mold 1, and the bot 4 is designed to allow a preformed resin as a sealing resin to be preformed into a substantially cylindrical shape, that is, a tablet 5 to be inserted therein. It is formed. A plunger 6 driven by a suitable press device (not shown) is inserted into the bot 4, and the plunger 6 is supplied with ultrasonic vibrations by an ultrasonic vibration generator 7 at a desired time. It is now possible to be influenced.

A cull 8 is formed in the lower mold 2 at a position facing the bot 4, and a runner 9 is connected to the cull 8, which communicates with each cavity 3 through each gate 10.

Next, the operation of the transfer molding machine having the above configuration will be explained, and a method for molding a non-hermetically sealed pancake according to an embodiment of the present invention will be explained.

First, the objects 11 to be sealed are respectively accommodated in the cavities 3 of a transfer molding machine. This object to be sealed 11 is constructed by bonding a pellet 12 on which an integrated circuit of a semiconductor device is formed onto a lead frame 13, and electrically connecting the portion of the pellet 12 and lead frame 13 to be bonded using a bonding wire 14. The lead frame 13 is sandwiched between the upper mold 1 and the lower mold 2 at the joint surface of the upper mold 1 and the lower mold 2, and the pellet 12 is placed approximately in the center of the cavity 3. It is set to come.

When the object to be sealed 11 is inserted and the upper mold 1 and the lower mold 2 are joined, the tablet 5 is put into the bot 4. Normally, when the tablet 5 is inserted, the plunger 6 starts pressure feeding, and the resin formed by heating and melting the tablet 5 is forced into the cavity 3.

By the way, the tablet 5 is made of a curing agent and a prepolymer (
The sealing resin is made into powder by reacting it with epoxy resin (epoxy resin, etc.) until it can be heated and molded, and then mixed with a filler and a mold release agent.
It is preformed into a roughly cylindrical shape by cold forming using a tablet molding machine, and is so dense that it can be held in the hand, and the surface is melted by induction heating to prevent unevenness.

In this way, since the tablet 5 is formed by compacting powder and granular material and wrapping it with a molten surface, air is trapped inside the tablet 5. Therefore, if the tablet 5 is compressed as it is and the resin is pumped into the cavity 3, the trapped air will remain inside or on the surface of the non-hermetically sealed package, causing air bubbles inside the non-hermetically sealed puff cage. I will make it.

Therefore, it is necessary to discharge the air trapped inside the tablet 5 before the resin is press-fitted into the cavity 3. Therefore, in this embodiment, before the resin is pumped into the cavity 3, the air inside the tablet 5 is discharged by applying ultrasonic vibrations.

That is, in this embodiment, when the tablet 5 is put into the bot 4, the plunger 6 pre-pressurizes it to an appropriate pressure, as shown in FIG. continue,
The plunger 6 uses an ultrasonic vibration generator 7 to apply ultrasonic vibrations to the appropriately compressed tablet 5. This ultrasonic vibration propagates inside the tablet 5, thereby forcibly discharging the air trapped inside.

After an appropriate amount of time has elapsed for the air purification caused by ultrasonic vibration to end,
The plunger 6 starts main pressurization. Due to this pressurization, the resin formed by heating and melting the tablet 5 is forced into each cavity 3 through the runner 9 and the gate 10, thereby forming a non-hermetically sealed package. This non-hermetically sealed package contains 12 pellets. Lead frame 13
and bonding wire 14 are sealed. Since the air inside the tablet is evacuated before pumping the resin, this non-hermetically sealed pancage reduces air bubbles caused by the air inside the tablet, and therefore semiconductor devices with this non-hermetically sealed package are The molding can be done without deteriorating moisture resistance or appearance due to air bubbles.

〔effect〕

ill By applying ultrasonic vibrations to the molding material and discharging the air inside the molding material, it is possible to suppress the generation of air bubbles inside and on the surface of the molded product, improving the quality and reliability of the molded product. etc. can be improved.

(2) When molding a non-hermetically sealed package for a semiconductor device, by energizing the tablet with ultrasonic vibration and expelling the air inside the tablet, the inside or surface of the non-hermetically sealed package can be molded. Since the generation of air bubbles can be suppressed, it is possible to suppress the occurrence of poor moisture resistance and poor appearance of a semiconductor device provided with a non-hermetically sealed package.

(3) By applying ultrasonic vibration to the molding material through the plunger, the structure for applying ultrasonic vibration can be extremely simplified, and the application of ultrasonic vibration can be applied extremely effectively. It can be done.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the application of ultrasonic vibrations to the molding material is not limited to the use of a plunger, and a dedicated application means or process may be incorporated.

[Application field]

In the above description, the invention made by the present inventor has mainly been explained in the case where it is applied to molding a non-hermetically sealed package in the field of application of semiconductor devices, which is the background of the invention, but the invention is not limited to this. It can be applied to all molding techniques for other molded products.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a transfer molding machine used in a molding method according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation. ■... Upper mold, 2... Lower mold, 3... Cavity, 4
... Pot, 5... Tablet (molding material), 6.
...Plunger, 7...Ultrasonic vibration generator, 8...
・Cal, 9...Runner, 10...Gate, 11...
- Object to be sealed, 12...Bellet, 13...Lead frame, 14...Bonding wire. Part 1: Ginbatsu

Claims (1)

[Scope of Claims] 1. A resin sealing method in which a molded product is housed in a cavity of a mold, and a sealing resin is injected into the cavity for resin sealing, the plunger and the injection path A molding method characterized by applying ultrasonic vibration to remove air bubbles from the sealing resin. 2. Claim 1, characterized in that the ultrasonic vibration is provided by a plunger that pumps the sealing resin.
Molding method described in section.