JPH0582809A - High-voltage semiconductor rectifying element - Google Patents

Abstract

PURPOSE:To improve the forward overcurrent resistance of a high-voltage semiconductor commutator where a plurality of semiconductor rectifying pieces are connected in series through solder materials. CONSTITUTION:The expansion of the solder material at the time of an overcurrent flowing is gentled, by using solder material 2, which contains Au, as the solder material for soldering a semiconductor commutator segment 1, and the stress added to the commutator segment is weakened to prevent cracks from occurring, whereby the forward overcurrent resistance is improved.

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 rectifying device in which connecting conductors are fixed to both ends of a columnar laminated body in which a plurality of semiconductor rectifying pieces are connected in series via a brazing material.

[0002]

2. Description of the Related Art For example, a high-voltage semiconductor rectifying device used for rectifying an alternating current having a peak reverse voltage of 20 kV cannot obtain a required withstand voltage with a single diode substrate. Use those connected in series. Such a semiconductor element is, for example, Ni-plated on both sides of a wafer with a PN junction formed, then stacked through Pb / Sn binary solder plates, heated and brazed,
Cut into diced pieces to form a columnar laminated body, fix the connecting conductors to both ends of the laminated body, cover the side surface of the laminated body with the joint coating resin (JCR), expose most of the connecting conductors, and seal with resin. Manufactured by stopping.

[0003]

A conventional high-voltage semiconductor rectifying device manufactured by the above method, for example, a device 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 withstand capacity of 1.5 A or more.

An object of the present invention is to solve the above problems and to provide a high voltage semiconductor rectifying device having a sufficient forward overcurrent withstand capability.

[0005]

In order to achieve the above object, the present invention provides a high voltage system 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 laminated body. In the semiconductor rectifier, the brazing material is a solder containing Au. And. Au content is
It is effective that the content is 0.8% by weight or more. Further, it is effective that the side surface of the columnar laminated body is covered with a surface protective resin, and most of the connecting conductors are exposed and resin-sealed.

[0006]

The deterioration of the element due to the forward overcurrent is because the brazing material expands rapidly due to the rapid temperature rise due to the overcurrent, and the stress causes a crack in the semiconductor rectifying piece. Figure 2
Shows an example of the linear expansion coefficient with respect to the original size of the brazing filler metal that expands when the temperature rises. Line 21 is Pb 90%, Sn 10%
This is the solder of wire 22 with Au added Pb89.1%, Au1.0
% Solder. 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,
Swelling occurs more slowly than As a result, the influence on the semiconductor rectifying piece is weak, and the forward overcurrent withstand capability is improved.

[0007]

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

[0008]

According to the present invention, by using a solder containing Au as a brazing material between semiconductor rectifying pieces connected in series and having a reduced solidus, the expansion of the solder due to an overcurrent is moderated. A stress applied to the semiconductor rectifying piece is weakened, cracks are prevented from being formed in the rectifying piece, and a high-voltage semiconductor rectifying element with improved forward overcurrent withstand capability can be obtained.

[Brief description of drawings]

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

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

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

[Explanation of symbols]

 1 Diode Chip 2 Solder 3 Lead 5 JCR 6 Cast Resin 10 Columnar Stack

Claims (3)

[Claims] 1. A columnar laminated body in which a plurality of semiconductor rectifying pieces are connected in series via a brazing material, and connecting conductors are fixed to both ends thereof, wherein the brazing material is a solder containing gold. High voltage semiconductor rectifier. 2. The high-voltage semiconductor rectifier according to claim 1, wherein the content of gold is 0.8% by weight or more. 3. The high-voltage semiconductor rectifying device according to claim 1, wherein the columnar laminated body is covered on its side surface with a surface protective resin, and is further resin-sealed by exposing most of the connecting conductors.