JPH09260585A - Flat-type semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat-type semiconductor device which enables an electric power control device including a cooling device to be reduced in size and weight by reducing the thermal resistance between the semiconductor device and a coolant when a double-side cooling flat-type semiconductor is used in a circulating water cooling system. SOLUTION: A plate-like protrusion is provided to the one end of each of the electrode plates 4a and 4b of a flat-type semiconductor device 1 extending outwards beyond the periphery of an insulating ring 5 to serve as a current terminal 6. A usual current plate can be dispensed with, so that a thermal resistance between the current plate and a contact can be eliminated. As compared with a conventional one, a thermal resistance between the flat-type semiconductor device 1 and a coolant can be reduced by 25%. It is preferable that the current terminals 6 are set deviating from each other in position so as not to impede their connection with outer conductors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat semiconductor device for electric power, which is used in a main circuit conversion device for electric railway vehicles and which controls a large current.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a conventional double-sided cooling type flat semiconductor device for electric power. In the figure, the flat semiconductor element 1 has a heat transfer member 3 and an electrode plate 4 arranged on both sides of the semiconductor element chip 2 so as to come into pressure contact with each other. The periphery of the electrode plate 4 is fixed to an insulating ring 5 of alumina to form a semiconductor element case. Heat transfer member 3
Is molybdenum, which has a thermal expansion coefficient close to that of silicon, and the electrode plate 4 is copper, which has high electric and thermal conductivity. The heat loss generated in the semiconductor element chip 2 is transferred to the heat transfer member 3 and the electrode member 4 by heat conduction, and is radiated to the cooling bodies on both sides in contact with the surface of the electrode member 4. Instead of the semiconductor chip 2, a semiconductor element alloyed with a heat-resistant metal plate such as tungsten may be used. In the figure, details such as means for positioning the semiconductor chip 2 are omitted.

As a cooling method for a flat semiconductor element, there is a circulating water cooling method in which a cooling water (antifreeze liquid) is circulated by a circulation pump in an internal flow path of a cooling body mounted on a heating surface of the semiconductor element to cool the semiconductor element. is there. Cooling water (antifreeze) is used as the cooling water medium in the circulating water cooling system. As another cooling method, the semiconductor element and the cooling body are dipped in a liquid of an insulating refrigerant (for example, CFC liquid or fluorocarbon liquid),
There is an immersion boiling cooling method that cools the semiconductor element by the boiling phenomenon of the insulating refrigerant, but in consideration of environmental issues, it corresponds to the movement to regulate the use of insulating refrigerant (for example, CFC liquid or fluorocarbon liquid). Therefore, the circulating water cooling method is often used.

FIG. 4 is a diagram showing the structure of a circulating water cooling system using the flat semiconductor device of FIG. Flat semiconductor device 1
And a plurality of cooling bodies 8 are alternately arranged in series and pressurized to form the semiconductor stack 11. Reference numeral 14 is a disc spring for pressurization, and 15 is a steel ball for evenly weighting. At that time, since the flat semiconductor element 1 needs to be electrically insulated from the non-insulating cooling water (antifreeze liquid), it is between the flat semiconductor element 1 and the cooling body 8 through which the cooling water 21 flows. A sandwiched between an energizing plate 10 for energizing the flat semiconductor element 1 and an insulating plate 7 made of a highly heat conductive material. Reference numerals 12 and 13 are headers for distributing and collecting cooling water, respectively. The heat loss generated in the flat semiconductor element 1 is transferred by heat conduction from the flat semiconductor element 1 to the electrically insulated cooling body 8 through the current-carrying plate 10 and the insulating plate 7. This heat is removed by forced convection heat transfer by circulating the cooling water (antifreeze liquid) 21 by the circulation pump 19 in the flow path in the cooling body 8. And finally, the air-cooled radiator 1
6, heat is radiated to the outside air. Reference numeral 17 is an electric fan, 18 is cooling air, 20 is cooling water piping, and 22 is a tank.

[0005]

In the semiconductor stack having the above-mentioned structure using the conventional flat semiconductor device shown in FIG.
An insulating plate and a conducting plate exist between the semiconductor element and the cooling body. Therefore, between the semiconductor element and the cooling body, there are three contact portions, that is, the semiconductor element and the conducting plate, the conducting plate and the insulating plate, the insulating plate and the cooling body, and the contact thermal resistance is interposed at each of the contact portions.

When the thermal resistance was measured, the value of the contact thermal resistance at one contact portion was about 0.0014 K / W, which corresponds to 2 to 3 times the value of the thermal conductive resistance inside the electrode plate. ,
Overall thermal resistance between semiconductor element and cooling body 0.0057K /
It was found that it occupies about 25% of W. Such a large thermal resistance leads to an increase in size of the cooling body and the air-cooling radiator. That is, it is a major obstacle to the problems of size reduction and weight reduction in the main conversion device mounted on the electric railway vehicle.

In view of the above problems, it is an object of the present invention to provide a flat semiconductor element which can be reduced in outer shape in an assembled state including a cooling device.

[0008]

In order to solve the above problems, the present invention is a double-sided cooling type having two metal electrode plates fixed to a ceramic insulating ring and radiating heat from both sides of a semiconductor element housed therein. In the flat semiconductor element, at least one of the electrode plates has a plate-like protrusion extending outward from the outer periphery of the ceramic case, and the plate-like protrusion serves as a main current terminal.

Further, a part of the electrode plates on both sides may have a plate-like projection extending outward from the outer circumference of the ceramic case, and the plate-like projection may be used as a main current terminal. If the electrode plate of the flat type semiconductor element for electric power is configured as described above, the plate-shaped protrusion can also serve as the conventional energizing plate, so that the energizing plate is provided between the semiconductor element and the cooling body in the semiconductor element stack. Can be deleted.

In particular, the main current terminals of the extension portions of the electrode plates on both sides are symmetrically positioned or face each other at right angles.
It is preferable that the positions are shifted. By doing so, the main current terminals do not interfere with each other and the connection with the external conductor is easy. Furthermore, it is assumed that a hole is provided in the main current terminal in the extended portion of the electrode plate.

By doing so, the connection with the external conductor is easy.

[0012]

1 (a) is a cross-sectional view of a flat semiconductor device according to an embodiment of the present invention, and FIG. 1 (b) is a plan view of the flat semiconductor device of FIG. 1 (a) viewed from the left side of the drawing. FIG. FIG.
In (a), the flat semiconductor element 1 has a heat transfer member 3 and an electrode plate 4 arranged on both sides of the semiconductor element chip 2 so as to come into pressure contact with each other. A diaphragm plate 25a of iron-nickel alloy brazed around the electrode plate 4a on the left side of the drawing is brazed to the insulating ring 5 of alumina. Iron brazed around the electrode plate 4b on the right side of the figure-
The diaphragm plate 25b made of nickel alloy and the welding plate 26 made of iron-nickel alloy brazed to the insulating ring 5 made of alumina are arc-welded at their edges to form a semiconductor element case. The heat transfer member 3 is molybdenum having a thermal expansion coefficient close to that of silicon, and the electrode plate 4 is copper having high electric and thermal conductivity. Loss heat generated in the chip 2 is transferred to the heat transfer member 3 and the electrode plate 4 by heat conduction, and is radiated to the cooling body in contact with the surface of the electrode plate 4 by the conventional flat element shown in FIG. Is the same.

4 is different from the conventional flat type semiconductor device in that a plate-like projection is formed by extending a part of the electrode members 4 on both sides of the semiconductor device 1 from the outside of the semiconductor device case 5 to provide a current The point is that the terminal 6 is used. The width and thickness of the current terminal 6 are determined by the current capacity to be conducted and the bus to be connected. In this example, the current terminals 6 of the electrode plates 4 on both sides of the semiconductor element are provided at symmetrical positions.

In the external view of FIG. 1B, it can be seen that the current terminal 6 is provided on a part of the electrode plate 4a. A hole 61 is formed in the current terminal 6. Electrode plate 4
A diaphragm plate 25a can be seen around a, and the insulating ring 5 can be seen outside thereof. FIG. 2 is a partial configuration diagram of a semiconductor stack using the flat semiconductor device of the present invention. Semiconductor element 1
And the cooling body 8 are in close contact with each other with the aluminum nitride insulating plate 7 interposed therebetween. At the end of the stack 11, there are disc springs for pressurization and steel balls for uniform pressurization as shown in FIG. 4, but they are not shown in this figure. The current terminal 6 extending from the electrode plate of the semiconductor element 1 and the energizing outer conductor 23 are connected by a bolt nut 24. 9 is cooling water.

In this example, a current-carrying plate is not required as compared with the conventional semiconductor stack structure, and one contact portion between the semiconductor element 1 and the cooling body 8 is deleted. Therefore, the thermal resistance between the semiconductor element 1 and the cooling body 8 decreased by 25%. As a result, the energizing current could be increased by about 10% under the same cooling conditions. On the contrary, if the same energizing current is applied, the cooling device of the circulating water cooling system can be downsized.

As the direction of the current terminals on both sides of the semiconductor element, in addition to the embodiment of FIG. 1, various methods such as a method of providing them so as to face each other at right angles or a method of shifting the positions in the same direction can be considered. Further, although an example of the flat semiconductor element having a rectangular insulating ring has been shown, it is needless to say that the present invention is not limited to the square semiconductor element, and can be applied to a circular flat semiconductor element that is usually found.

[0017]

As described above, in the flat semiconductor device of the present invention, the plate-shaped projection in which a part of the electrode plate is extended to the outside of the outer circumference of the insulating ring serves as the main current terminal. In the structure of the semiconductor element stack by the circulating water cooling method using (antifreeze liquid), compared with the case of the semiconductor element stack structure using the conventional flat semiconductor element, the contact point on the heat path between the semiconductor element and the cooling body is It can be reduced in one place, and the thermal resistance between the semiconductor element and the cooling body can be reduced.

As a result, the shapes of the cooling body and the air-cooling radiator can be reduced, which contributes to the reduction in size and weight of the main conversion device mounted on the electric railway vehicle.

[Brief description of drawings]

1A is a cross-sectional view of a flat semiconductor device according to an embodiment of the present invention, and FIG. 1B is an outline drawing thereof.

FIG. 2 is a partial configuration diagram of a semiconductor stack using a flat semiconductor device of the present invention.

FIG. 3 is a sectional view of a conventional flat semiconductor device.

4 is a configuration diagram of a circulating water cooling system using the flat semiconductor device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat semiconductor element 2 Semiconductor chip 3 Heat transfer member 4 Electrode plate 5 Insulating ring 6 Current terminal 61 Hole 7 Insulating plate 8 Cooling body 9 Cooling water flow 10 Current-carrying plate 11 Stack 12 Cooling water distribution header 13 Cooling water collecting header 14 Belleville spring 15 Steel ball 16 Air-cooled radiator 17 Electric fan 18 Cooling air 19 Circulation pump 20 Liquid piping 21 Cooling water 22 Tank 23 Outer conductor 24 Bolt nut

Claims (6)

[Claims] 1. A double-sided cooling type flat semiconductor device having two metal electrode plates fixed to a ceramic insulating ring and radiating heat from both sides of a housed semiconductor chip, at least a part of one of the electrode plates. Has a plate-like protrusion extending outward from the outer circumference of the insulating ring, and the plate-like protrusion serves as a main current terminal. 2. A plate-shaped projection formed by extending a part of the electrode plates on both sides to the outside of the outer circumference of a ceramic insulating ring, and the plate-shaped projection is used as a main current terminal. Flat semiconductor device. 3. The flat semiconductor device according to claim 2, wherein the positions of the main current terminals of the extended portions of the electrode plates on both sides are displaced from each other. 4. The main current terminals on the extended portions of the electrode plates on both sides,
The flat semiconductor device according to claim 3, wherein the flat semiconductor device is provided at symmetrical positions. 5. The main current terminals of the extension parts of the electrode plates on both sides are
4. The flat semiconductor device according to claim 3, wherein the flat semiconductor devices are provided so as to face each other at right angles. 6. The flat semiconductor device according to claim 1, wherein a hole is provided in the main current terminal of the extended portion of the electrode plate.