JPH11146656A - Inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of an inverter. SOLUTION: Switching elements 11a-11c which constitute the arms of an inverter are laid on top each other. Then, surface electrodes of the switching element 11a and rear electrodes of the switching element 11b are joined and surface electrodes of the switching element 11b of rear electrodes of the switching element 11c are joined by soldering to integrate them into a module.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter for converting a DC voltage into an AC voltage.

[0002]

2. Description of the Related Art Conventionally, in an inverter device of this type, as disclosed in Japanese Patent Application Laid-Open No.
A plurality of switching elements connected in series are arranged on a plane, and each terminal is electrically connected by a bus bar.

[0003]

However, when a plurality of switching elements are arranged in a plane as described above,
There is a problem that the physique must be large. The present invention has been made in view of the above problems, and has as its object to reduce the size of an inverter device.

[0004]

In order to achieve the above object, according to the present invention, at least two switching elements connected in series between a positive bus and a negative bus are connected to one switching element. And a stacked structure in which the back surface electrode of the second switching element and the front surface electrode of the other switching element are joined to each other.

[0005] With such a laminated structure,
The size of the inverter device can be reduced. In this case, according to the second aspect of the present invention, since the electrode pad is formed in a region on the surface side of the other switching element that is not laminated with the one switching element, even in the case of a laminated structure. Electrodes can be taken out on the lower switching element.

The back electrode of one switching element and the front electrode of the other switching element are connected to each other.
Can be joined by brazing as in the invention described in (1). Further, as in the fourth aspect of the invention, when the plate electrodes are joined to each other with the plate electrodes interposed therebetween, the switching elements can be radiated well.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows a partial electrical connection diagram when a four-level inverter is used as a multi-level power converter. In the figure, capacitors 2, 3, and 4 are connected in series in parallel with a DC voltage source 1. A U-phase inverter arm 10 is provided between the positive bus 5 and the negative bus 6 of the inverter. This inverter arm 1
0 denotes a plurality of semiconductor switching elements (vertical power MOS transistors in which current flows in the vertical direction) 11a to 11
f and anti-parallel diode (flywheel diode)
12a to 12f, and diodes 13a to 13d forming a current path when changing the output voltage level. Here, the switching elements 11a to 11c constitute an upper arm, and the switching elements 11d to 11f constitute a lower arm. Although not shown, the V phase,
The W-phase inverter arm has the same configuration as that of the U-phase, and is provided between the positive bus 5 and the negative bus 6 by using the capacitors 2 to 4 in common.

In such a configuration, U-phase, V-phase, W-phase
By turning on / off each switching element in the phase inverter arm, the DC voltage of the DC voltage source 1 is converted to an AC voltage, and a load (not shown), for example, a three-phase AC motor is driven. In the present embodiment, the switching elements 11a to 11c forming the upper arm and the switching elements 11d to 11f forming the lower arm are stacked to form one module. FIG.
Switching elements 11a to 11 forming an upper arm
3 shows a schematic external configuration of a structure in which c is laminated.

As shown in the figure, the switching element 11a
From the chip size to the switching element 11c, and when they are stacked, the gate electrode pads 101, 111, 121 and the source electrode pads 102, 1 of the switching elements 11a, 11b, 11c are stacked.
12 and 122 do not overlap each other. That is, the switching elements 11a, 11b, 11
The gate electrode pad and the source electrode pad are formed on the respective surfaces (for the switching elements 11a and 11b, the surface of the region not stacked with the upper switching element). I have.
These gate electrode pads and source electrode pads are electrically connected to the outside by wire bonding. A source electrode serving as a surface electrode is formed on the front surface side of each switching element, but the gate electrode pad and the source electrode pad are formed on a protective film (not shown) formed on the source electrode. .

FIG. 3 shows switching elements 11a to 11c.
2 shows a cross-sectional configuration of a portion where is laminated. Switching element 1
As shown in the figure, 1a, 11b, and 11c have source electrodes 103, 113, and 123 formed as front electrodes and drain electrodes 104, 114, and 124 formed as back electrodes, respectively, and each has a vertical direction. A well-known vertical MOS transistor through which a current flows. The source electrode 103 of the switching element 11a and the drain electrode 114 of the switching element 11b, and the source electrode 113 of the switching element 11b and the drain electrode 124 of the switching element 11c are joined by brazing.

With such a laminated structure,
A current can flow in the direction from the switching element 11a to the switching element 11c. The switching elements 11d to 11f forming the lower arm also include the switching elements 11a to 11f forming the upper arm.
1c, it has a laminated structure.

By forming a plurality of switching elements into a single layered structure with a laminated structure, a small inverter device with low loss and low noise can be obtained. In the embodiment described above, the switching element 1
1a between the source electrode 103 and the drain electrode 114 of the switching element 11b;
In FIG. 4, the source electrode 113 and the drain electrode 124 of the switching element 11c are directly joined by brazing. However, as shown in FIG. You may make it join by brazing. In this case, it is possible to improve the heat radiation of the switching element that is the power element.

Further, in the above-described embodiment, a configuration in which the present invention is applied to a four-level inverter has been described. However, a three-level inverter or an inverter having five or more levels may have the same laminated structure as described above. it can.

[Brief description of the drawings]

FIG. 1 is a partial electrical connection diagram of a four-level inverter.

FIG. 2 shows switching elements 11a to 11c constituting an upper arm.
It is a schematic external view of the structure which laminated | stacked 11c.

FIG. 3 is a diagram illustrating a cross-sectional configuration of a portion where switching elements 11a to 11c are stacked.

FIG. 4 is a diagram showing another embodiment.

[Explanation of symbols]

1: DC voltage source, 2-4: Capacitor, 5: Positive bus, 6
... Negative bus, 10 ... Inverter arm, 11a-11f ...
Switching elements, 12a to 12f: anti-parallel diodes, 13a to 13d: diodes, 101, 111, 1
21 ... gate electrode pads, 102, 112, 122 ... source electrode pads, 103, 113, 123 ... source electrodes as surface electrodes, 104, 114, 124 ... drain electrodes as back electrodes.

Claims (4)

[Claims] 1. A laminated structure comprising at least two switching elements connected in series between a positive bus and a negative bus, wherein a back electrode of one switching element and a front electrode of the other switching element are joined. An inverter device characterized in that: 2. The semiconductor device according to claim 1, further comprising a region on the front surface side of the other switching element that is not stacked with the one switching element, and wherein an electrode pad of the other switching element is formed in this region. The inverter device according to claim 1. 3. The device according to claim 1, wherein a back electrode of the one switching element and a front electrode of the other switching element are joined by brazing.
3. The inverter device according to claim 1. 4. The inverter device according to claim 1, wherein the back electrode of the one switching element and the front electrode of the other switching element are joined with a plate-shaped electrode interposed therebetween.