JPS5912016B2 - Glass mold type semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass mold type semiconductor device using a connecting conductor integrated with an electrode body that contacts electrodes provided on both sides of a semiconductor piece.

A conventional glass mold type semiconductor device, for example a diode, has a semiconductor piece 1 and an electrode body 2 attached to it covered with a glass layer 3, as shown in FIG. 1, and a lead wire 4 is connected to the electrode body 2. There is.

The electrode body 2 is made of a metal material whose coefficient of thermal expansion matches that of glass, for example a single metal such as tungsten or molybdenum, or an alloy such as Kovar. The metal material forming such an electrode body has low electrical conductivity, poor flexibility even when made into a wire, and is expensive, so it is welded to a lead wire 4 made of a good electrical conductor, for example, copper. However, there are drawbacks such as peeling of the welded parts, exposed contact parts of dissimilar metals, which may cause electrolytic corrosion, and high welding costs. Unlike such a semiconductor device, an object of the present invention is to provide a glass mold type semiconductor device having an electrode body and a lead wire that have low manufacturing cost and are mechanically and chemically stable.

The purpose of this is to attach a composite conductor made of a metal material, which is a good conductor of electricity, to each electrode of the semiconductor chip and covered with a metal material having a coefficient of thermal expansion approximately 15 similar to that of glass over the entire length of the outer surface. This is accomplished by contacting the connecting conductors.

The invention will now be described with reference to the embodiment shown in FIG. The composite 20 lead wire 5 is directly connected to the semiconductor 1 without using an electrode body.
are connected by methods such as brazing. Composite to composite lead wire 5
The center part 6 is made of a good electrical conductor, for example, copper, and the covering part 7 is made of W, Mo, which has a coefficient of thermal expansion similar to that of color.
It consists of a single metal such as or an alloy such as Kovar. The end 25 of the composite lead wire 5 is provided with a head 8, and if necessary, a protrusion 9 may be provided near the end to increase the adhesion strength of the molded glass layer 3. Since the head 8 and the protrusion 9 are formed by header processing, the cost is lower than the welding cost of conventional electrode bodies. center 30
The cross-sectional area of 6 can be changed depending on the current carrying capacity, but
Since the elastic modulus of copper is smaller than the elastic modulus of the metal material of the sheathing part 7, the thermal expansion coefficient of the lead wire 5 as a composite material will be lower than that of the sheathing material 7 unless its cross-sectional area is high in proportion to the total cross-sectional area. It is close to the thermal expansion coefficient of 35,
By approximating the coefficient of thermal expansion of the molded glass layer 3, it is possible to avoid cracking of the glass during molding or use.
Furthermore, since the difference between the coefficient of thermal expansion of the semiconductor piece 1 is much smaller than that in the case where copper is directly brazed, the stress exerted on the semiconductor piece 1 due to thermal fluctuations is also small. Note that the present invention is not limited to a single semiconductor board, and the present invention can be implemented in the same manner even in the case of a stacked semiconductor board such as a high-voltage diode. Furthermore, since the covering portion of the composite connecting conductor used in the present invention is less likely to corrode in air at room temperature than copper, composite conductors with copper as the surface,
For example, it is economical because there is no need to plate the surface for corrosion prevention as in the case of aluminum wire.

As described above, the present invention makes it possible to economically manufacture a highly reliable glass mold type semiconductor device without fear of peeling of lead wires or electrolytic corrosion.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a conventional glass molded diode, and FIG. 2 is a vertical sectional view of a glass molded diode according to an embodiment of the present invention. 1...Semiconductor piece, 3...Glass layer, 5...Composite connection conductor.

Claims (1)

[Claims] 1 In a device in which a connecting conductor contacts electrodes provided on both sides of a semiconductor piece, and a portion of the semiconductor piece and the connecting conductor are integrally covered with glass, the connecting conductor covers the entire outer surface in the longitudinal direction. 1. A glass mold type semiconductor device characterized in that it is a composite conductor made of a metal material that is a good conductor of electricity and covered with a metal material having a combustion expansion coefficient close to the expansion coefficient of .