JPH1012814A - Semiconductor stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fall of the energizable current by housing a semiconductor element of a different-diameter electrode in a semiconductor stack incorporated without deviated weight, for improved reliability of the semiconductor element. SOLUTION: Related to a semiconductor stack comprising different multiple pressure welding type semiconductor elements 2, 4 and 44 of electrode diameters 3, 5 and 45 arrayed in series, a water-cooling fin 1 for cooling the semiconductor elements 2, 4 and 44, and an electrode lead-out metal plate 6, among the multiple pressure welding type semiconductor elements 2, 4 and 44, the semiconductor element 2 having the electrode of largest diameter is, through the water-cooling fin 1, adjoined by the semiconductor element 4 having the electrode of the second largest diameter, for arraying. Thus, a deviated weight applied to a periphery part of the semiconductor elements having the electrode of largest diameter is reduced, so pressure welding at the electrode surface of largest diameter is made even, for even flow of current inside the semiconductor element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor stack in which a plurality of press-contact type semiconductor elements are arranged in series.

[0002]

2. Description of the Related Art Generally, a semiconductor element used in a power conversion device includes a switch element and a diode as shown in FIG. Here, when the power converter regenerates power from the load side, the same current as the current flowing through the gate tan-off thyristors 28 to 31 of the switch element flows through the freewheel diodes 32 to 35. However, the free-wheeling diodes 32 to 35 are
Since the current density is higher than that of the rectifier diodes 32 to 35, the electrode diameter of the return diodes 32 to 35 is
It becomes smaller than 31. In addition, snubber diodes 20 to 2
In No. 3, the same current as the current flowing through the gate tan-off thyristors 28 to 31 flows instantaneously, but since the average current is small, the electrode diameter becomes smaller than that of the freewheel diodes 32 to 35. Thus, at least three types of semiconductor elements having different electrode diameters are used in the power converter. Conventionally, when such semiconductor elements having different electrode diameters are accommodated in a stack having water-cooled fins, generally, semiconductor elements having the same electrode diameter have a structure in which the semiconductor elements having the same electrode diameter are sandwiched and pressed through water-cooled fins in the same stack. I have. However, with this configuration, a wiring is generated between the stacks, and the inductance of the wiring cannot be reduced. Therefore, there is a problem that a surge voltage, a high-frequency vibration voltage, a vibration current, and the like generated in the semiconductor element increase. Therefore, in order to avoid wiring between the stacks, semiconductor elements having different electrode diameters are accommodated in the stacks via water-cooled fins, and are pressed in a narrow pressure.

[0003]

However, even a semiconductor stack in which semiconductor elements having different electrode diameters are held in pressure contact with each other has the following problem. That is, in a portion where a semiconductor element having a large electrode diameter and a semiconductor element having a small electrode diameter are adjacent to each other via a water-cooled fin, the load decreases at the periphery of the electrode of the semiconductor element having a large electrode diameter and increases at the center. Looking at the contact portion between the electrode and the silicon wafer inside the semiconductor element in this state, the contact resistance is low in the central portion where the load is high, and conversely, the contact resistance is high in the peripheral portion. As a result, the current flowing through the semiconductor element flows intensively at the center. In addition, the thermal resistance between the silicon wafer and the electrode surface increases in the peripheral portion of the electrode where the load is low, and the temperature rise increases in the peripheral portion of the semiconductor. Such concentration of the current inside the semiconductor element and a local rise in temperature cause a decrease in the reliability of the semiconductor element and a current that can flow. Such a problem becomes more apparent as the semiconductor elements having a large difference in electrode diameter are pressed against each other via water-cooled fins.

[0004] It is an object of the present invention to accommodate semiconductor elements having different-diameter electrodes in an integrated semiconductor stack without biasing load.
An object of the present invention is to improve the reliability of a semiconductor element and prevent a decrease in a current that can flow.

[0005]

An object of the present invention is to provide, among a plurality of press-contact type semiconductor elements having different electrode diameters arranged in series, a semiconductor element having an electrode having the largest diameter via a water-cooled fin. The problem is solved by arranging adjacent semiconductor elements having diameter electrodes. When a semiconductor element having the largest diameter electrode among a plurality of pressure-contact type semiconductor elements having different electrode diameters arranged in series is a gate turn-off thyristor (GTO), a water-cooled fin is provided on the cathode electrode side of the GTO. The problem is solved by arranging adjacently the semiconductor elements having the second largest diameter electrodes. Further, when arranging a plurality of press-contact type semiconductor elements having different electrode diameters arranged in series, a high-rigidity metal conductor is disposed between the press-contact-type semiconductor elements having different electrode diameters via water-cooling fins. It is solved by.
Here, the plurality of press-contact type semiconductor elements having different electrode diameters arranged in series include a clamp diode, a cross current prevention diode, a snubber diode, and a gate turn-off thyristor (GTO) forming the upper arm circuit of the power converter and the upper arm circuit. ) And a return diode, and the upper arm circuit and the semiconductor element group forming the upper arm circuit of the power conversion device are divided into an upper arm semiconductor stack and a lower arm semiconductor stack, and are provided side by side. shorten.

The present invention alleviates the biasing load applied to the peripheral portion of the semiconductor element having the largest diameter electrode and makes the pressure contact of the largest diameter electrode surface uniform. As a result, the current flows uniformly inside the semiconductor element, thereby improving the reliability of the semiconductor element and preventing a decrease in the current that can be passed. In addition, since the semiconductor element is arranged so that the electrode surface on the cathode side of the gate turn-off thyristor (GTO) is uniformly weighted, current concentrated inside the semiconductor element is reduced. In addition, in order to supplement the rigidity of the water-cooled fins with a highly rigid metal conductor and to make the load on the electrode surface of the semiconductor element having a large electrode diameter uniform, a current is uniformly flowed inside the semiconductor element. Further, the wiring inductance of the power converter is reduced, and high-frequency vibration is suppressed. Thereby, low loss and high reliability of the power converter are achieved, and downsizing is possible.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings of embodiments. FIG. 1 is a plan view showing an embodiment of a semiconductor stack according to the present invention, in which semiconductor elements having electrodes having different diameters are incorporated in the same semiconductor stack. In FIG. 1, reference numeral 1 denotes a water-cooled fin, 2 denotes a semiconductor element having the largest diameter electrode among the pressure-contact type semiconductor elements in the integrated semiconductor stack, 3 denotes both electrodes of the semiconductor element 2, and 4 denotes an electrode in the integrated semiconductor stack. Among the press-contact type semiconductor elements, a semiconductor element having an electrode having the second largest diameter, 5 are both electrodes of the semiconductor element 4,
Reference numeral 4 denotes a semiconductor element having a third largest diameter electrode among the press-contact type semiconductor elements in the integrated semiconductor stack, 45 denotes both electrodes of the semiconductor element 44, and 6 denotes a metal plate for extracting an electrode.

In this embodiment, a semiconductor element 2 having one largest diameter electrode and a semiconductor element 4 having a second largest diameter electrode and a semiconductor element 2 having two third largest diameter electrodes are provided. 44 shows a case where the water-cooled fin 1 is attached to one of the semiconductor elements 2 having the electrode 3 having the largest diameter.
Element 4 having an electrode 5 of the second largest diameter via
Are arranged, and a semiconductor element 44 having an electrode 45 having the third largest diameter is arranged via the water-cooled fins 1. Further, the semiconductor element 44 having the third largest diameter electrode 45 is arranged on the other side of the semiconductor element 2 having the largest diameter electrode via the water-cooled fins 1, and a metal plate for taking out the electrode is provided. As described above, if each semiconductor element is arranged, the area where the electrode surface 3 of the semiconductor element 2 having the largest diameter and the electrode 5 of the semiconductor element having the second largest diameter are in contact with each other is equal to the semiconductor element 2 having the largest diameter.
Electrode surface 3 and the electrode surface 4 of the semiconductor element having the third largest diameter
5 is larger than the area in contact. Therefore, the water-cooled fin 1
When pressed against each other, the water-cooled fin 1 interposed between the electrode 3 having the largest diameter and the electrode 45 having the third largest diameter is greatly warped toward the electrode surface 45 having the smaller electrode surface, and the electrode 3 having the larger electrode diameter is formed. The water-cooled fin 1 interposed between the electrode 3 having the largest diameter and the electrode 5 having the second largest diameter,
In this case, the warp toward the electrode surface 45 is small, and the electrode 3 having a large electrode diameter is uniformly pressed.

In this embodiment, when the semiconductor elements having different diameter electrodes are incorporated into the same semiconductor stack, the second largest diameter electrode 5 is located adjacent to the semiconductor element 2 having the largest diameter electrode.
By arranging the semiconductor elements 4 having the same shape, the pressure contact of the electrode surface having the maximum diameter is made uniform, whereby the current flows uniformly inside the semiconductor element, and the current as in the conventional example concentrates inside the semiconductor element. In addition, it is possible to eliminate the adverse effect of causing a local temperature rise. As a result, it is possible to improve the reliability of the semiconductor element and prevent a decrease in the current that can flow. In the present embodiment, when two or more semiconductor elements 4 having the second largest diameter electrode 5 are used, it is needless to say that they are adjacent to both sides of the semiconductor element 2 having the largest diameter electrode.

Here, in the example of the semiconductor element used for the power converter shown in FIG. 8, the electrode diameter of the switch elements 28 to 31 is the largest, and then the freewheel diodes 32 to 3
5. The order of the snubber diodes 20 to 23 is as follows. In this case, if the snubber diodes are arranged on both sides of the switch element, the water-cooled fins provided above and below the switch element are respectively warped to the snubber diode side, and the load is reduced on both electrode sides of the switch element. Will be. In order to reduce such a problem, in the present embodiment,
The reflux diode having the second largest electrode diameter is arranged adjacent to the switch element having the largest electrode diameter.

FIG. 2 is a top view of the water-cooled fin 1, and FIG.
FIG. 3 is a cross-sectional view of the water cooling fin 1. In the figure, 42 is a water channel (pipe), 43 is a water inlet / outlet, 41 is a water-cooled fin 1 lid,
Reference numeral 49 denotes a brazing portion. The water-cooled fins 1 flow water from the water inlet / outlet 43 into the pipe 42 to cool the semiconductor element.

FIG. 4 shows another embodiment of the present invention. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals. In the present embodiment, the semiconductor element having the largest diameter electrode is a gate turn-off thyristor (GTO) 7, and the semiconductor element 4 having the second largest electrode is arranged on the cathode side of the GTO 7. Here, the flow of current when the GTO 7 is pressed is described with reference to FIGS. FIG. 5 shows a case where biased load occurs on the electrode on the cathode 9 side, and FIG. 6 shows a case where biased load occurs on the electrode on the anode 8 side. In the figure, 8 is the GTO anode electrode, 9 is the GTO cathode electrode, and 46 is the GTO electrode.
TO, 48 represents the unit GTO. As shown in FIG. 5, when a strongly pressurized portion 47 is formed on the cathode 9, one unit GTO 48 of the strongly pressurized portion 47 is formed.
, The current is concentrated (as indicated by the arrow) on the unit GTO 48 having the small contact resistance. Therefore, current concentration at the cathode-side electrode 9 is inevitable. On the other hand, as shown in FIG. 6, when a strongly pressurized portion 47 is formed on the anode 8, the contact resistance of one unit GTO 48 of the strongly pressurized portion 47 decreases, and the current is reduced by the contact resistance. Small unit GTO
However, if the weight of the electrode 9 on the cathode side is uniform, it is diffused (as indicated by an arrow) while flowing from the anode side to the cathode side, and is dispersed and flows to each unit GTO 48. From the above, it is important to arrange the semiconductor elements so that the cathode-side electrode surface 9 of the GTO is uniformly weighted. Therefore, in the present embodiment, as shown in FIG. 4, the semiconductor element 4 having an electrode having the next largest diameter after the GTO 7 is arranged on the cathode 9 of the GTO. Thereby, in the present embodiment, it is possible to reduce the concentration of the current inside the semiconductor element.

FIG. 7 shows another embodiment of the present invention. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals. In the drawing, reference numeral 10 denotes a high-rigidity metal conductor without annealing. The present embodiment has the semiconductor element 44 having the third largest diameter electrode and the semiconductor element having the largest diameter electrode, and has the semiconductor element 44 having the second largest diameter electrode and the largest diameter electrode. The metal conductors 10 are inserted between the semiconductor elements via the water cooling fins 1 respectively.

Here, as shown in FIG.
Has a brazing portion 49. The brazing portion 49 is for brazing the lid 41 for closing the water channel 42 to prevent water leakage. At the time of brazing, the water-cooled fins 1 are once brought to a high temperature state, and then slowly cooled to room temperature. Leads to.
In this step, the water-cooled fins 1 are subjected to annealing, and thus have reduced rigidity. For this reason, when a semiconductor element having a small electrode diameter and a semiconductor element having a large electrode diameter are adjacent to each other, the water-cooling fin 1 warps toward the semiconductor element having a small electrode diameter, and the peripheral surface of the electrode surface of the semiconductor element having a large electrode diameter is weighted. Is reduced.

Therefore, in this embodiment, a metal conductor 10 is inserted between a semiconductor element having a small electrode diameter and a semiconductor element having a large electrode diameter via a water-cooling fin 1, and the metal conductor 10 having high rigidity is The rigidity is compensated and the load on the electrode surface of the semiconductor element having a large electrode diameter is made uniform. Thereby, in the present embodiment, the current flows uniformly inside the semiconductor element, and the current as in the conventional example concentrates inside the semiconductor element.
The adverse effect of causing a local temperature rise can be eliminated, and as a result, the reliability of the semiconductor element can be improved and a decrease in the current that can be conducted can be prevented.

FIG. 9 shows another embodiment in which the present invention is applied to a semiconductor element used in the power converter shown in FIG. Here, the power converter of FIG. 8 shows a circuit configuration 37 for one phase, which has the same configuration in three phases and supplies three-phase outputs to a load (not shown). The circuit configuration 37 for one phase includes a DC power supply 11, power supply capacitors 12 and 13, clamp capacitors 14 and 15, clamp diodes 16 and 17, cross current prevention diodes 18 and 19, a snubber diode 20,
21, 22, 23, snubber capacitors 24, 25, 2
6, 27, GTOs 28, 29, 30, 31, reflux diodes 32, 33, 34, 35, anode reactor 36
Consists of The semiconductor element group 38 is an upper arm circuit, and the semiconductor element group 39 is a lower arm circuit.

In FIG. 9, the same parts as those in the circuit diagram of FIG. In the figure, reference numeral 40 denotes an insulating spacer.
The left side of FIG. 9 shows a semiconductor stack of the upper arm circuit 38. The semiconductor elements are arranged from the top to the bottom in the figure, and the anti-cross current diode 18, the snubber diode 20, the GTO 28,
The freewheeling diodes 32 are arranged in this order, and the clamp diode 16 and the insulating spacer 4 are interposed via the insulating spacer 40.
The freewheeling diode 33, the GTO 31, and the snubber diode 22 are arranged in this order via 0. Further, the water-cooled fins 1 are arranged between the respective semiconductor elements, and insulating spacers 40 are inserted between the respective water-cooled fins 1 of the freewheel diode 32 and the clamp diode 16 and between the freewheel diode 33 and the clamp diode 16. The right side of FIG. 9 is a semiconductor stack of the lower arm circuit 39. The semiconductor elements are arranged in the order of the crossflow prevention diode 19, the snubber diode 21, the GTO 29, and the freewheel diode 35 from the top to the bottom of the figure. The clamp diode 17 is arranged via the spacer 40, and the freewheel diode 34, the GTO 28, and the snubber diode 23 are arranged in this order via the insulating spacer 40. Further, the water-cooled fins 1 are arranged between the respective semiconductor elements, and the insulating spacers 40 are inserted between the free-wheel diodes 35 and the clamp diodes 17 and between the free-wheel diodes 34 and the clamp diodes 17.

Normally, the semiconductor stack of the upper arm circuit 38 and the semiconductor stack of the lower arm circuit 39 are vertically stacked and integrally formed. For this reason, the semiconductor stack becomes longer and shorter, which increases the size of the semiconductor stack. In addition, the wiring between the upper and lower arm circuits becomes longer, and the inductance due to this wiring increases. On the other hand, in the embodiment of FIG. 9, the semiconductor stack is connected to the semiconductor stack of the upper arm circuit 38 and the lower arm circuit 3.
By dividing the semiconductor stack into nine semiconductor stacks and providing them side by side as shown in the figure, the semiconductor stack is reduced in size, and at the same time, the wiring between the upper and lower arm circuits is shortened, and the inductance due to the wiring is reduced. As described above, in the embodiment of FIG. 9, the power conversion device uses a semiconductor stack in which the pressure contact force of the semiconductor element is improved, and is further divided into the semiconductor stack of the upper arm circuit and the semiconductor stack of the lower arm circuit, and is provided in parallel. By doing so, it is possible to reduce the wiring inductance and suppress high-frequency vibrations, thereby achieving low loss and high reliability of the power converter, and also enabling downsizing. It goes without saying that the embodiments of FIGS. 4 and 7 can be applied to the power converter of FIG.

[0019]

As described above, according to the present invention,
When semiconductor elements with different diameter electrodes are integrated into the same semiconductor stack, the bias load applied to the periphery of the semiconductor element having the largest diameter electrode can be reduced, thereby making the pressure contact of the largest diameter electrode surface uniform. As a result, it is possible to eliminate the disadvantage that the current flows uniformly inside the semiconductor element and that the current is concentrated inside the semiconductor element and causes a local temperature rise as in the conventional example. It is possible to improve the reliability of the element and prevent a decrease in current that can flow. Gate turn-off thyristor (GTO)
By arranging the semiconductor element such that the electrode surface on the cathode side is uniformly weighted, it is possible to reduce the concentration of the current inside the semiconductor element. In addition, the rigidity of the water-cooled fins can be supplemented by a highly rigid metal conductor,
The load on the electrode surface of the semiconductor element having a large electrode diameter can be made uniform, and the current can flow uniformly inside the semiconductor element. In addition, the wiring inductance of the power converter can be reduced and high-frequency vibration can be suppressed, so that the power converter can have low loss and high reliability, and can be downsized.

[Brief description of the drawings]

FIG. 1 shows one embodiment of a semiconductor stack according to the present invention.

FIG. 2 is a top view of a water-cooled fin.

FIG. 3 is a sectional view of a water-cooled fin.

FIG. 4 shows another embodiment of the present invention.

FIG. 5 is a sectional view of a gate turn-off thyristor (GTO).

FIG. 6 is a sectional view of a gate turn-off thyristor (GTO).

FIG. 7 shows another embodiment of the present invention.

FIG. 8 is a circuit diagram of a power converter.

FIG. 9 is another embodiment in which the present invention is applied to a power converter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Water-cooled fin 2 Semiconductor element with the largest diameter electrode 3 Both electrodes of the semiconductor element 4 4 Semiconductor element with the second largest diameter electrode 5 Both electrodes of the semiconductor element 4 44 Semiconductor element with the third largest diameter electrode 45 Both electrodes of the semiconductor element 44 6 Metal plate for extracting electrodes 7 Gate turn-off thyristor (GTO) 8 Internal electrode on the anode side of the gate turn-off thyristor 9 Internal electrode on the cathode side of the gate turn-off thyristor 10 Metal conductor 16, 17 Clamp diode 18 , 19 Cross current prevention diode 20-23 Snubber diode 28-31 Gate turn-off thyristor (GTO) 32-35 Freewheeling diode 40 Insulating spacer

Claims (5)

[Claims] 1. A semiconductor stack comprising a plurality of press-contact type semiconductor elements having different electrode diameters arranged in series, water-cooling fins for cooling the semiconductor elements, and a metal plate for extracting electrodes, wherein the plurality of press-contact type semiconductor elements are provided. A semiconductor stack, wherein a semiconductor element having a second largest diameter electrode is arranged adjacent to a semiconductor element having a largest diameter electrode among the semiconductor elements having a maximum diameter through the water cooling fin. 2. In a semiconductor stack comprising a plurality of pressure-contact type semiconductor elements having different electrode diameters arranged in series, water-cooling fins for cooling the semiconductor elements, and a metal plate for extracting electrodes, the plurality of pressure-contact-type semiconductor elements are provided. When the semiconductor element having the largest diameter electrode among the semiconductor elements of the type is a gate turn-off thyristor (GTO), the semiconductor element having the second largest diameter electrode on the cathode electrode side of the GTO via the water-cooled fins Are arranged adjacent to each other. 3. A semiconductor stack comprising a plurality of press-contact type semiconductor elements having different electrode diameters arranged in series, water-cooling fins for cooling the semiconductor elements, and an electrode extraction metal plate, wherein A semiconductor stack, wherein a high-rigidity metal conductor is disposed between different press-contact type semiconductor elements via the water-cooled fin. 4. The pressure-contact type semiconductor element according to claim 1, wherein the plurality of pressure-contact type semiconductor elements having different electrode diameters are arranged in series, and the clamp forms an upper arm circuit and an upper arm circuit of the power converter. A semiconductor stack comprising a diode, a cross-flow prevention diode, a snubber diode, a gate turn-off thyristor (GTO) and a freewheeling diode. 5. The power conversion device according to claim 4, wherein an upper arm circuit of the power converter and a semiconductor element group forming the upper arm circuit are divided into an upper arm semiconductor stack and a lower arm semiconductor stack and are provided side by side, and wiring between the upper and lower arm circuits is provided. A semiconductor stack characterized by shortening the length of the semiconductor stack.