JPS588586B2 - Sealing method for semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sealing a semiconductor device, and particularly to an improvement in a glass sealing method.

In the currently widely used flat package type or dual in-line type glass-sealed semiconductor devices, a ceramic envelope such as alumina porcelain and a lead frame are sealed with various types of glass, and a semiconductor pellet is placed in a hollow space formed inside. It is formed by attaching.

FIG. 1 is a plan view showing an example of a lead frame used in such a semiconductor device, and FIG. 2 is a vertical sectional view showing an example of a conventional dual in-line type glass-sealed semiconductor device.

In the figure, 1 is a lead frame, and 2 is a bonding part in which aluminum is attached to the lead frame 1 by vapor deposition or pressure bonding.

FIG. 2 will be explained below according to the assembly procedure.

A lead frame 1 is placed on an insulating ceramic substrate 4 coated with an insulating glass 3 in advance, and the lead frame 1 is fixed by heating.

After the die bonding of the semiconductor element 5 and the connection between the semiconductor element 5 and the bonding 2 on the lead frame 1 using the thin metal wire 6 are performed by a well-known method, the sealing glass 7 is
The sealing assembly is completed by placing an insulating ceramic lid 8 on which has been coated in advance and heating it to fix it.

By the way, in the semiconductor device manufactured by the conventional method, the lead frame 1 has only the bonding part 2 formed with a metal thin film such as gold or aluminum, and the rest is used as the frame material commonly called 42 alloy. There is.

That is, in the conventional device, the insulating glasses 3 and 7 take advantage of the fact that the material surface of the lead frame 1 is oxidized in various processes up to the glass sealing process.
He had gained close contact with the

However, due to variations in oxidation received during this process, variations in the adhesion between the lead frame 1 and the insulating glasses 3 and 7 occur, resulting in poor airtightness or, in extreme cases, the leads of the lead frame 1 falling off. This causes inconveniences such as

This invention has been made in view of the above points, and provides a method for sealing a semiconductor device that ensures oxidation of the surface of the sealing part of the lead frame and provides good adhesion between the insulating glass for sealing and the lead frame. This is what I am trying to do.

FIG. 3 is a longitudinal sectional view showing an example of a glass-sealed semiconductor device manufactured according to the present invention.

The method of the present invention is substantially the same as the conventional method described with reference to FIG. 2, except that the lead frame 1 is pretreated to facilitate oxidation, so only the pretreatment portion will be described.

A metal thin film 9 made of aluminum, iron, copper, nickel, silver, etc., which easily forms a dense oxide film at a relatively low temperature, is formed by vapor deposition or pressure bonding on the portion of the lead frame 1 that is fixed to the sealing insulating glasses 3 and 7. use something

Otherwise, the sealing is performed by the same process as described with reference to FIG. Since this oxide film 10 has a strong chemical bond with glass, the lead frame 1 and the insulating glasses 3 and 7 are strongly bonded to each other, and the occurrence of defects as in the conventional case can be prevented.

In the above description, the aluminum thin film of the bonding part 2 of the lead frame 1 and the metal thin film 9 of the sealing part are provided separately, but it is also possible to extend the aluminum thin film of the bonding part 2 to the sealing part and separate the thin aluminum film from the bonding part 2 to the sealing part. It may also be used as the metal thin film 9.

As described in detail above, in this invention, a metal thin film that forms a dense oxide film at low temperature is applied on the surface of the part of the lead frame to be sealed that comes into contact with the sealing glass. The oxide film formed by heating adheres well to the sealing glass, making it possible to completely seal the glass.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a lead frame used in the present invention, FIG. 2 is a longitudinal sectional view showing an example of a conventional dual in-line type glass-sealed semiconductor device, and FIG. 3 is a plan view showing an example of a lead frame used in the present invention. FIG. 2 is a longitudinal cross-sectional view showing an example of a glass-sealed semiconductor device. In the figure, 1 is a lead frame, 2 is a bonding part, 3 and 7 are sealing glasses, 4 and 8 are ceramic envelopes, 5 is a semiconductor element, 6 is a thin metal wire, 9 is a metal thin film, and 10 is an oxide film It is. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. After connecting the bonding portions of the plurality of lead wires provided on the lead frame to the semiconductor element via thin metal wires, the semiconductor element, the thin metal wires, and the bonding portions of the lead wires are placed in a predetermined envelope. A method for sealing a semiconductor device using a lead frame coated with a metal thin film that forms a dense oxide film at a low temperature on at least the surface of the portion in contact with the sealing glass. .