JPS5841771B2 - semiconductor equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and more particularly to an improvement in the structure of the semiconductor device in order to improve its resistance to explosion due to short-circuit current.

Recently, semiconductor devices, especially power semiconductor devices, are becoming more powerful and smaller.

However, as the rated current capacity increases, it becomes difficult to coordinate with the protective fuse, and if the protective fuse is not suitable, the semiconductor device may be A short-circuit current several tens of times higher than the rated current flows, and there is a risk that the semiconductor device may explode and be destroyed by this short-circuit current.

This will be explained below using the drawings.

FIG. 1 is a fragmented front view of the main parts of a conventional power semiconductor rectifier.

In the figure, 1 is a semiconductor rectifying element, 2 is a silicon substrate on which a PNN+ junction (not shown) of the semiconductor rectifying element 1 is formed, and 3 is a molybdenum plate having almost the same coefficient of thermal expansion as the silicon substrate 2. 4 is an aluminum aluminum silicon (Al-AlSi) eutectic layer for brazing the silicon substrate 2 and the support plate 3; 5 is an aluminum A7 layer on the main surface of the silicon substrate 1;
6 is made of copper; T is the first main electrode that is pressed into contact with the A7 electrode layer 5 of the semiconductor rectifying element 1; T is made of copper and serves as a support for the semiconductor rectifying element 1; The second main electrode 8, which is pressed into contact with the plate 3, is made of an insulating material such as ceramic, and is connected to the semiconductor rectifying element 1 and the first main electrode 8. A cylindrical insulator 9 provided surrounding the second main electrodes 6 and 7 is made of a copper thin plate, and the inner circumference is brazed to the first main electrode 6 and the outer circumference is the first insulator 8. 10 is an iron plate or an iron-nickel alloy plate and is a collar-shaped flat plate brazed to the second end face of the insulator 8; 11 is an iron plate or iron plate; - An annular flat plate made of a nickel alloy plate, the inner circumference of which is brazed to the second main electrode T and the outer circumference welded to the collar-shaped flat plate 10; 12 is connected to the first Q main electrode 6 and the second main electrode 7, respectively; Shows brazed heat dissipation fins.

Next, an example of a state of destruction due to a short circuit current in the power semiconductor rectifier configured as described above will be explained with reference to a waveform diagram of the short circuit current shown in FIG. 2 and a fragmented front view of the main part shown in FIG. 3.

When an AC voltage that allows a forward current larger than the rated surge forward current to flow is applied between the bidirectional electrodes 6 and 7 of this power semiconductor rectifier, as shown in FIG. Although the temperature of the silicon substrate 2 rises to 250 to 500'Ct due to the forward current flowing through the silicon substrate 2 shown in FIG. 1, the PNN+ junction is not destroyed and the reverse current is blocked.

However, in the second cycle, the temperature of the silicon substrate 2 further increases to 1200 to 2000'C4, and due to this temperature increase, the silicon substrate 20PNN+ junction loses its rectifying function, and a reverse current begins to flow.

When this reverse current starts to flow, the temperature of the silicon substrate 2 increases more and more, and a short circuit current starts to flow after the second cycle.

In this way, when a short circuit current starts to flow, the temperature of the silicon substrate 2 becomes higher than the melting point of the Al-AlSi eutectic layer 4 and the AA electrode layer 5 formed on its main surface, and these layers 4 and 5 become silicon It evaporates from the periphery of the substrate 2.

Along with this evaporation, high-temperature arcs are generated around the silicon substrate 2, between the silicon substrate 2 and the first main electrode 6, and between the silicon substrate 2 and the support plate 3.

This high-temperature arc melts the periphery of the silicon substrate 2 and the first main electrode 6 and support plate 3 near this periphery to form molten pieces, which form the first main electrode 6 and the second main electrode 7. It scatters into the space created by the insulator 8, and the gas sealed in this space becomes a plasma and rapidly expands.

By the way, in the structure of a conventional power semiconductor device, a thin metal plate such as a flexible metal plate 9 and an annular flat plate 11 is placed in the space created by the first main electrode 6, the second main electrode 7, and the insulator 8. Since the plates are exposed, the plasma of the sealed gas comes in contact with these metal plates, raising their temperature. Furthermore, since the molten pieces collide with these metal plates, the energy of the molten pieces causes the above-mentioned The temperature of the metal plate reaches its melting point, and a hole is created where the molten piece collides with the metal plate.

From this hole, the rapidly expanded filled gas is explosively ejected to the outside, accompanied by the molten pieces.

This state of destruction is shown in FIG.

Therefore, the conventional structure has the disadvantage that the molten pieces explosively ejected to the outside may cause a serious disaster depending on the location where the semiconductor device is installed.

The semiconductor device used in the above experiment has a surge forward current (
IFsM)33. oooA, current squared time product (I2t
) 5X10A S, and as a result of conducting experiments under the conditions of applied voltage 1.0OOV, short circuit current 170KA, and current squared time product 20XI06A2S, all samples were destroyed.

The present invention has been made in view of the above-mentioned drawbacks, and includes first and second main electrodes each facing an insulator in their opposing directions, and a portion where the first and second main electrodes and the insulator face each other. By providing an elastic shield between the
The purpose is to provide a semiconductor device with explosion resistance.

FIG. 4 is a fragmented front view of essential parts showing an embodiment of a power semiconductor rectifying device according to the present invention.

In the figure, 13a and 13b are protrusions provided over the entire circumference of the first and second main electrodes 6 and 7, respectively; 14 is a protrusion provided on the inner surface of the insulator 8 over the entire circumference; and the protrusion 1 of the second main electrodes 6, 7
3a, 13b and the protruding portion 14 of the insulator 8, and the cross section U is made of metal and is provided so as to close the passage from the semiconductor rectifying element 1 to the flexible metal plate 9 and the annular flat plate 11. It is a letter-shaped annular shield.

In the power semiconductor rectifying device configured in this way, melted pieces of the member melted by the high temperature arc generated around the semiconductor rectifying element 1 due to the short circuit current are scattered at each protrusion, as shown by the solid line arrows in the figure. 13a, 13b, 14,
It is possible to prevent the flexible metal plate 9 and the annular flat plate 11 from touching the flexible metal plate 9 and the annular flat plate 11, and also to prevent the plasma of the sealed gas turned into plasma by the high temperature arc from directly touching the flexible metal plate 9 and the annular flat plate 11. can do.

The insulator 8 has a large heat capacity, and each protrusion 13a of the first and second main electrodes 6, 7.

If the thickness of 13b is 1 m or more, the energy of the melted pieces is absorbed inside each main electrode 6, 7 and insulator 8, and the melted pieces are fixed thereto, as shown by the dotted arrows in the figure. .

Projections 13a, 13b. If the molten pieces hit 14 intensively, it will be melted with a large amount of energy,
This consumes a large amount of energy, and since the accelerated melting pieces temporarily stop, they do not have enough energy to melt and break the flexible metal plate 9 and the annular flat plate 11.

Furthermore, each protrusion 13a, 13b. There are a large number of melted pieces trying to pass through the space between the shield 1 and the shield 1.
5, it adheres to the surface of this shield without passing through it.

Therefore, as in the conventional device shown in FIG.
Also, the temperature of the annular flat plate 11 rapidly reaches its melting point, and it is possible to suppress the formation of holes due to melting, so that it is possible to prevent the molten pieces from becoming explosive and scattering around the installation location of the device.

The gap between the inner wall of the insulator 8 and the end face of each main electrode 6, 7 is determined by their thermal expansion difference and processing accuracy.If the main electrode is made of copper and has a diameter of 70 mm, one side Q, 6
All you need is MAIL.

In addition, the protrusions 13a and 13b of each main electrode 6 and 7 and the insulator 8
The gap between the opposing surfaces of the protrusion 14 is the width of the shield 15 to be inserted.
However, it is desirable that the elastic force of the inserted shield 15 be smaller than the elastic force of the flexible metal plate 9 and the annular flat plate 11 attached to the main electrodes 6 and 7, respectively.

In the above embodiment, the main electrodes 6 and 7 and the insulator 8 have protrusions 13a and 13b, respectively.

14, and a protrusion 13a of each main electrode 6,7.

Although the elastic shield 15 is inserted between the facing portion of the insulator 13b and the protrusion 14 of the insulator 8, as shown in FIG. Electrodes 6, 7
The same effect can be obtained by inserting, for example, an annular shield 15 having a circular cross section between the opposing portions so that the protruding portions 13a and 13b face both end surfaces of the insulator 8.

FIGS. 6a to 6e are sectional views showing a diametrical cross section of the annular shield 15, which is a feature of the present invention.

Figure 6 a, b, and e are each made of a metal spring material such as nickel silver, stainless steel, cupronickel, etc., and have a thickness of 0.1~
Q. It is formed by processing a 3 ytm ring plate to have elasticity, and a has an inclined rectangular cross section, b has a U-shaped cross section, and e has a hollow circular cross section.

In addition, FIGS. 6c and d show elastic insulators such as silicon, respectively.
It is formed by processing fluororubber, and C has a circular cross section, and d has a square cross section.

According to experiments, when the thickness is 0.2 mm (IJfr surface U-shaped shield 15 is used, the current squared time product is 8 × 10
It was found that a value of 7A2S or less does not cause destruction.

As described above, according to the present invention, the first and second main electrodes each face the insulator in their opposing directions, and there is an elastic force between the facing portions of the first and second main electrodes and the insulator. Since a shield having a shielding structure is inserted, the current squared time product value can be made larger than that of the conventional one, and a semiconductor device with explosion resistance can be realized.

Although the above description has been made using a power semiconductor rectifier as an example, the present invention is not limited to this and can be applied to other semiconductor devices.

[Brief explanation of the drawing]

Fig. 1 is a fragmented front view of main parts showing a conventional power semiconductor rectifier, Fig. 2 is a current waveform diagram showing an example of short circuit current of a conventional power semiconductor rectifier, and Fig. 3 is shown in Fig. 1. FIG. 4 is a fragmented front view of the main part showing an example of a state of destruction due to short-circuit current of a conventional device. FIG. 4 is a front view of the main part broken, showing one embodiment of the present invention. FIG. A partially exploded front view and FIGS. 6a to 6e are sectional views showing a shielding body that is a feature of the present invention, respectively. In the figure, 1 is a semiconductor rectifier, 6 is a first main electrode,
7 is a second main electrode, 8 is an insulator, 9 is a flexible metal plate, 10
11 is an annular flat plate, 13a, 13b, 14
is a protrusion, and 15 is an annular shield. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 semiconductor element, a first semiconductor element provided with this semiconductor element in between. The second main electrode, the semiconductor element and the first. Second
An insulator is disposed so as to surround the outer periphery of the contact portion of the main electrode to the semiconductor element, and outer peripheral portions are attached to both end faces of the insulator, respectively. The first main electrode has an inner circumference attached to the second main electrode. The first button is pressed on the semiconductor device including the second flexible metal plate. A semiconductor device characterized in that the second main electrode has a portion facing the insulator in the opposing direction, and an elastic shield is inserted between the facing portion and the insulator.