JP3133108B2 - High voltage semiconductor rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage semiconductor rectifier in which a plurality of semiconductor rectifier pieces are connected in series via a brazing material and connection conductors are fixed to both ends of a columnar laminate.

[0002]

2. Description of the Related Art For example, a high voltage semiconductor rectifier used for rectifying an alternating current having a peak reverse voltage of 20 kV cannot provide a required withstand voltage with a single diode substrate. Use those connected in series. Such a semiconductor element is, for example, subjected to Ni plating on both sides of a wafer having a PN junction formed thereon, stacked through a Pb / Sn binary solder plate, heated, and brazed.
The laminate is cut into dice to form a columnar laminate, connection conductors are fixed to both ends of the laminate, and the side surfaces of the laminate are covered with a junction coating resin (JCR), and most of the connection conductors are exposed and sealed with resin. Manufactured by stopping.

[0003]

A conventional high-voltage semiconductor rectifier manufactured by the above-described method, for example, an element having an average forward current of 5 mA is desirable in a forward overcurrent withstand test.
There is a problem that it is difficult to obtain a resistance of 1.5 A or more.

An object of the present invention is to solve the above-mentioned problems and to provide a high-voltage semiconductor rectifier having a sufficient forward withstand current.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a columnar laminated body in which a plurality of semiconductor rectifying pieces are connected in series via a brazing material, and connection conductors are fixed to both ends of the columnar laminated body. In the above, the brazing material is a solder containing lead and tin and containing gold in an amount of 0.8% by weight or more. Then, it is effective that the side surface of the columnar laminate is covered with a surface protection resin, and furthermore, most of the connection conductors are exposed and sealed with resin.

[0006]

The device is deteriorated due to the forward overcurrent because the brazing material expands rapidly due to a rapid temperature rise due to the overcurrent, and the stress causes a crack in the semiconductor rectifying piece. FIG.
Shows an example of the linear expansion rate for the original dimensions of the brazing material that expands when the temperature rises, and the line 21 is Pb 90%, Sn 10%
The wire 22 is Pb 89.1% with Au added, Au 1.0
% Of the solder. The addition of 1.0% Au lowers the solidus temperature of the solder by about 35 °. Therefore, it begins to melt at a lower temperature, as shown by line 22,
Inflation occurs more slowly than in the past. As a result, the effect on the semiconductor rectifying piece is weak, and the forward overcurrent withstand capability is improved.

[0007]

FIG. 1 shows a high-voltage semiconductor rectifying device according to an embodiment of the present invention. A diode chip (semiconductor rectifying piece) 1 having a pn junction with a thickness of about 280 .mu.m is connected to a solder 2 with a thickness of 45 .mu.m.
A lead 3 having a head 31 at both ends of a columnar laminated body 10 connected in series via a wire is brazed by solder 4. Further, the side surface of the columnar laminate is covered with a JCR 5 such as a polyimide resin and sealed with a casting resin 6 such as an epoxy resin. Pb / Sn /
Au ternary solder was used. Figure 3 shows the ternary solder
The figure shows the forward overcurrent withstand capability of the rectifying device completed when a binary solder containing 90% Pb and 10% Sn and 0.1% by weight, 0.5% by weight, 1.0% by weight and 2.0% by weight of Au is used. As apparent from FIG. 2, the forward overcurrent withstand capability is improved when the Au content is 0.8% or more, and a withstand capability of 1.5 A or more is obtained.

[0008]

According to the present invention, as a brazing material between semiconductor rectifier pieces connected in series, a solder made of lead and tin and containing 0.8% by weight or more of gold and having a reduced solidus line is used. Accordingly, the expansion of the solder due to the overcurrent becomes slow, the stress applied to the semiconductor rectifying piece is reduced, the crack is prevented from being formed in the rectifying piece, and a high-voltage semiconductor rectifying element having improved withstand current in the forward direction is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a high-voltage semiconductor rectifier according to one embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the linear expansion coefficient and the temperature showing the effect of Au content.

FIG. 3 is a diagram showing the relationship between the forward overcurrent withstand voltage and the Au content in the solder showing the effect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diode chip 2 Solder 3 Lead 5 JCR 6 Cast resin 10 Columnar laminate

Claims (2)

(57) [Claims] 1. A columnar laminate in which a plurality of semiconductor rectifying pieces are connected in series via a brazing material, and a connecting conductor is fixed to each end of the columnar laminate. A high-voltage semiconductor rectifier, characterized in that the rectifier contains at least 10% by weight. 2. The high-voltage semiconductor rectifier according to claim 1, wherein the columnar laminate is covered with a surface protection resin on its side surface, and is further resin-sealed by exposing most of the connection conductor.