JPH10125899A - Gate turn-off thyristor - Google Patents

Abstract

(57) [Problem] To improve a controllable current in a large-capacity GTO by rapidly interrupting a large current without in-plane current concentration. To achieve the above object, a conductor having the same potential as a cathode electrode is provided between a gate lead and a gate lead header in a package. [Effect] It is possible to alleviate the current concentration at the time of turn-off, to prevent an excessive current from flowing to the unit element, to cut off the large current at a high speed, and to improve the controllable current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate turn-off thyristor (hereinafter referred to as "GTO"), and more particularly to a GTO suitable for a large-capacity power converter and a power converter using the same.

[0002]

2. Description of the Related Art Generally, a GTO is often used for controlling a vehicle, controlling a steelworks, and controlling large industrial power. The structure and the like of the center gate type GTO will be described as a conventional example.

FIG. 2 is a schematic sectional view of a conventional GTO.
FIG. 3 shows a state in which the components are separated along the pressing direction for convenience in order to make the components easy to see. The envelope comprises a bottom structure 1 and a top structure 2. The cathode electrode post 3 made of copper (hereinafter referred to as Cu) and the bottom surface of the ceramic insulator cylinder 4 are joined to each other using a silver braid via a ring-shaped metal plate 5. Metal plate 6
A gate pipe 7 for taking out a gate electrode and a pinch pipe 8 for enclosing nitrogen are respectively attached to the side surfaces of the ceramic cylinder 4 by silver brazing. The bottom structure 1 includes an electrode post 3, a ceramic cylinder 4, a ring-shaped metal plate 5, a welded ring-shaped metal plate 6, a gate pipe 7, and a pinch pipe 8. The electrode post 3 is provided with a cutout 9 for taking out the gate lead 16. The top structure 2 is composed of a Cu anode electrode post 10 and a welded ring-shaped metal plate 11 soldered to this. In this envelope, reference numeral 1
Enclose members indicated by 2 to 23. For sealing, the welded ring-shaped metal plate 6 and the welded ring-shaped metal plate 11 are joined by welding, the lead wire of the gate lead 16 is passed through the gate pipe 7, crimped, and welded in a state where the inside is filled with nitrogen gas and finally sealed. Stop. On the anode side of a silicon (hereinafter referred to as Si) pellet 20 of the GTO element, a molybdenum (hereinafter referred to as Mo) disk 22 is used as an internal buffer.
On the cathode side, a Mo ring 19 is also sandwiched between Teflon rings 23 as an internal buffer to form a sub-assembly. Here, a silicon rubber 21 for insulating the anode side and the cathode side of the Si pellet 20 is attached to the end face of the Si pellet 20. The gate electrode has a structure in which a gate lead 16 and a ceramic support 17 are sandwiched between Teflon rings 15. In order to insulate the gate lead 16 from the cathode electrode post 3, a Teflon tube 1 is connected to the gate lead 16.
Through 8. Below this gate electrode, mica 1
4, a washer 12 and a disc spring 13 are provided, and the gate electrode is pressed against the gate electrode portion of the Si pellet 20 by these members. The GTO having the above structure is used in a pressure-contact state by applying a pressure in the opposite direction to the anode electrode post and the cathode electrode post by an external pressing means.

In order to turn off in the operation of the GTO, it is necessary to apply a pulse-like reverse voltage between the gate and the cathode to instantaneously remove a part of the charge inside the device in the on state from the gate. is there. At this time, the GTO needs a sufficiently large off-gate current. G of the above structure
FIG. 4 shows the locus of the gate current when the TO is turned off. The gate driver consists of a gate pipe 7 and a ring-shaped metal plate 5
Is connected to the auxiliary cathode electrode 24 attached thereto. The current flowing from the auxiliary cathode electrode 24 spreads over the entire surface of the cathode electrode post 3 and thereafter flows toward the Si pellet 20 through the Mo ring 19. The current flowing over the entire surface of the cathode of the Si pellet 20 passes through the inside of the pellet and is collected at the gate electrode at the center of the pellet, and the gate lead header 2
5 flows through the gate lead 16 to the gate pipe 7. FIG. 5 shows current and voltage waveforms when the GTO is turned off. In order to cut off the large current of the GTO, the off-gate current must be sufficiently increased at the same time, and the area of the gate lead header must also be increased at the same time. For example, 6kA
In order to turn off the current, it is necessary to increase the peak off gate current to about 1500 A and to increase the gate lead header area to about φ40 mm.

[0005]

A large-capacity GTO has a structure in which a large number of small unit elements are arranged concentrically on a disk-shaped semiconductor substrate in a concentric ring shape to form a plurality of element regions. Then, these unit elements are operated in parallel by supplying a signal current (gate current) from a common gate terminal provided on the Si pellet, and the current is turned on / off. Ideally, all the unit elements are simultaneously controlled on / off.

In the GTO using the above-described conventional structure, in the Si pellet near the gate lead 16, a current flowing toward the gate electrode at the center of the Si pellet and a gate flowing from the gate electrode located between the unit GTOs on the surface of the Si pellet are used. The effect that the inductance of the gate electrode between the unit GTOs on the surface of the Si pellet becomes smaller due to the mutual inductance with the current flowing toward the pipe,
The Mo disk having the same potential as the cathode potential served as a buffer material and prevented. However, center gate electrode and gate lead 1
Between 6, only the ceramic support 17 was provided, and the influence of the mutual inductance was affected. As a result, non-uniform operation of current interruption in a plane, such as interruption from a unit GTO close to a gate lead, has occurred.
This becomes more remarkable as the GTO has a larger current and a larger diameter.

An object of the present invention is to provide a GTO that solves the above-mentioned problems of the conventional structure.

[0008]

In order to achieve the above object, the present invention provides a gate turn-off thyristor in which pellets in which unit gate turn-off thyristors are arranged in parallel and radially in a semiconductor substrate are provided. And a first means for providing a conductor having the same potential as the cathode electrode between the header and the header of the gate lead.

According to the above-mentioned means, by providing a conductor having the same potential as the cathode electrode between the gate lead in the package and the header of the gate lead, this conductor causes the magnetic field induced by the current flowing through the gate lead and the gate Since each of the magnetic fields induced by the current flowing through the lead header disappears as a small eddy current, there is no need to be affected by the mutual inductance between the center gate electrode and the gate lead 16.

Therefore, the current does not concentrate locally when the current is interrupted, and a large current can be interrupted at a high speed.

In this means, when a metal such as molybdenum or tungsten (hereinafter referred to as W) having a coefficient of thermal expansion close to that of Si is provided in the conductor, sticking between the gate lead header and the gate electrode can be sufficiently suppressed. When a metal having a high thermal conductivity such as Cu is provided, it is effective for eliminating heat generation of Si.

In a GTO with a large current, that is, a large diameter, the off-gate current flowing through the gate lead must be sufficiently large, and the area of the gate lead header must be sufficiently large, so that the effect of the present invention appears more remarkably.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments.

FIG. 1 is a schematic sectional view of a GTO according to the present invention. The gate structure in the package connected to the gate driver is different from the conventional example.

FIG. 6 is an enlarged view of the conventional gate structure, and FIG. 7 is an enlarged view of the gate structure of the present invention. Instead of the ceramic support 17 provided in the conventional structure, Mo, W or Cu
And the like. As a result, the conventional washer 12
Is inserted between the gate lead header 25 and the conductor 27 to insulate between the gate and the cathode. At this time, for security, it is necessary to make the diameter of the mica slightly larger than the diameter of the gate lead header. A Teflon ring 26 and a Teflon tube 18 are provided for insulation between the gate lead 16 and the conductor 27.

FIG. 8 and FIG. 9 show an analysis model that calculates how the current distribution changes in the conventional package structure and the case where the inner diameter of the internal buffer Mo ring is reduced from φ45 to φ20. The gate Al electrode on the surface of the Si pellet is simplified as an Ag electrode on the entire surface. Using this model, A, B, C, D
Then, the relationship between time and current value was calculated for each region. The results are shown in FIGS. FIG. 10 shows the calculation results when the inner diameter of the internal buffer Mo ring is φ45, and FIG.
It is a calculation result when the inner diameter of the o-ring is φ20.
In the case of φ45, there is a large variation in each region, but in the case of φ20, there is considerable agreement in each region.
From this result, it can be seen that by inserting an internal buffer Mo ring between the gate wiring and the Ag electrode, it is possible to prevent the in-plane variation of the inductance between the currents of both. Ideally, the entire area between the gate wiring and the Ag electrode is covered with the internal buffer Mo. However, in the conventional GTO, the gate lead header is applied to the center gate electrode, which is the gate current outlet, through a coned disc spring. Since the pressure is different from that of the cathode pressure, the diameter of the internal buffer Mo ring is limited. In the present invention, the conductor having the same potential as the cathode potential is provided in the ceramic support portion of the conventional structure.
The magnetic field due to the current flowing through the Al electrode on the pellet surface can be completely shielded. Therefore, there is no in-plane variation in inductance at the time of current interruption, so that current does not locally concentrate, and a large current can be interrupted at high speed. For example, when a metal such as molybdenum or tungsten (hereinafter referred to as W) having a coefficient of thermal expansion close to that of Si is provided for the conductor, sticking between the gate lead header and the gate electrode can be sufficiently suppressed, and a material such as Cu can be used. When a metal having a high thermal conductivity is provided, it is effective for eliminating heat generation of Si.

In a GTO with a large current, that is, a large diameter, the off-gate current flowing through the gate lead is sufficiently large, and the area of the gate lead header needs to be sufficiently large, so that the effect of the present invention appears more remarkably.

Embodiment 2 FIG. 12 shows a GTO according to the present invention.
1 shows an example of a power conversion device using a main circuit of an inverter device. Compared with the case where the conventional GTO is used, the GTO according to the present invention has a larger controllable current, so that the number of GTOs required for a desired inverter power capacity can be reduced. Therefore, it is effective in reducing the size of the device and improving the reliability. The GTO according to the present invention is not limited to an inverter device, but includes various types of power including a forward converter (rectifier), a cycloconverter, a chopper device, a semiconductor circuit breaker, and a device combining a plurality of these devices. It can be used for conversion devices.

[0019]

According to the present invention, current concentration occurring at the time of turn-off in a large-capacity GTO can be reduced, so that a controllable current corresponding to the size of the element can be obtained, and a large-capacity GTO can be obtained. GTO can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a GTO showing a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a GTO showing a conventional structure.

FIG. 3 shows a state in which the components of the conventional structure are separated from each other along the pressing direction for the sake of simplicity.

FIG. 4 is a schematic cross-sectional view of a conventional GTO for explaining a locus of a gate current when the GTO is turned off.

FIG. 5 shows the current at the time of turning off the conventional structure GTO,
It is a voltage waveform.

FIG. 6 is an enlarged cross-sectional view of a gate current extraction portion of a conventional GTO.

FIG. 7 is an enlarged cross-sectional view of a GTO gate current extraction portion for explaining the first embodiment of the present invention.

FIG. 8 is an analysis model for explaining the first embodiment of the present invention, in which a current distribution is calculated when the inner diameter of the conventional package structure and the Mo ring is changed.

FIG. 9 is an analysis model for explaining the first embodiment of the present invention, in which a current distribution is calculated when the inner diameter of the conventional package structure and the Mo ring are changed.

10 is a calculation result when the inner diameter of the Mo ring is φ45 in the analysis models of FIGS. 8 and 9;

FIG. 11 is a calculation result when the inner diameter of the Mo ring is φ20 in the analysis models of FIGS. 8 and 9;

FIG. 12 is a circuit diagram showing an example of an inverter device using a GTO according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... bottom structure, 2 ... top structure, 3 ... cathode electrode post, 4 ... ceramic cylinder, 5 ... ring-shaped metal plate, 6, 11 ...
Welding wheel type metal plate, 7 gate pipe, 8 pinch pipe, 9 notch, 10 anode electrode post, 12 washer, 13 disc spring, 14 mica, 15, 23, 26 ...
Teflon ring, 16 gate lead, 17 ceramic support, 18 Teflon tube, 19 Mo ring, 20 Si pellet, 21 silicon rubber, 22
Mo disk, 24: auxiliary cathode electrode, 25: gate lead header, 27: conductor.

Claims (2)

[Claims] 1. A gate turn-off thyristor in which pellets in which unit gate turn-off thyristors are arranged in parallel and radially in a semiconductor substrate are mounted. A gate turn-off thyristor characterized by comprising: 2. A low-impedance metal such as molybdenum or tungsten having a coefficient of thermal expansion close to that of silicon, such as molybdenum or tungsten, is used for a conductor having the same potential as a cathode electrode inserted between the gate lead and the header of the gate lead according to claim 1. A gate turn-off thyristor characterized by being provided.