JPH1093085A - Package of semiconductor device and power converter using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the concentration of currents and heat-generating parts and to reduce the inductance and the size of cooling facilities by arranging IGBT chips and diode chips, scattering them in a package under, specific conditions. SOLUTION: Arrangement patterns 1991 and 1992 for IGBTs 11 and diodes 14 in an IGBT package 1 are so chosen that four chips may form a quadrangle around one corner of an arbitrary chip, and they are the cases in which one diode chip 14 and two diode chips 14 are contained respectively. In either case, the number of diode chips 14 are three or less. Accordingly, in the IGBT package 1 the welding pressure of the chips becomes uniform, since the IGBT chips 11 and diode chips 14 are arranged being scattered. Further, it becomes possible to realize an IGBT stack having a superior cooling characteristic, and to reduce the size of cooling facilities for stacks, since currents are scattered and flow in the IGBT package, and heat-generating parts are not concentrated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IGBT package formed by connecting a diode in antiparallel with a high-speed switching element IGBT, and an inverter device using the IGBT package.

[0002]

2. Description of the Related Art With the expansion of the application range of power converters, high performance, low noise and miniaturization of the devices have become increasingly important. Power MOS-FE as a control element to realize this
IGBT (Insulated Gate Bipola) that combines high-speed switching characteristics of T and high power controllability of bipolar transistors
r Transistor) has been developed and widely used as a key device for power converters.

[0003] Since IGBTs have a saturation characteristic, M
A large current capacity can be obtained by connecting a plurality of elements in parallel like an OS-FET. Therefore, multiple
By mounting the IGBT chip together with a plurality of diodes on a common base, an IGBT module having a large current capacity has been realized. Here, since the diode in the IGBT module is used as a freewheel diode, it is connected in anti-parallel to the IGBT chip.

[0004]

However, the conventional IGB
The T module has a structure in which one main electrode of an IGBT or a diode is mounted on a common base electrode by solder or the like, and the other main electrode is wired by wire bonding. Therefore, there has been a reliability problem that the wire is disconnected due to repeated temperature rise of the chip due to power loss during operation and partial temperature rise at the connection point of the wire due to overcurrent. Further, the conventional IGBT module has a problem in that heat generated in the chip cannot be removed from the other main electrode wired with a wire, and the thermal cooling effect is poor.

On the other hand, the conventional GTO (Gate Turn Off T
Attempts have been made to commercialize a new type of IGBT package (hereinafter referred to as a press-contact IGBT package) that solves the problems of heat dissipation and disconnection by pressing the main electrodes on both sides of the semiconductor element with metal like a hyristor). ing. These are described, for example, in JP-A-8-88240 and reference EPE '95, Vo.
l.1, p.1051 (1995).

In the press-contact IGBT package, usually, a plurality of chips of 1 to 2 cm square are simultaneously pressed. The number of chips that need to be simultaneously pressed depends on the withstand voltage, current capacity, and chip size. However, to realize an IGBT package with a withstand voltage of several kV and a current of about several hundreds of A, about 10 to 30 IGBTs and about 5 to 15 IGBTs Diode is required.

[0007] IGBTs are usually used in power converters such as inverters and converter circuits, and perform power conversion by repeating switching operations. In this case, the IGBT and the diode incorporated in the IGBT package do not repeat the switching operation at the same time. For example, when the fundamental frequency of the inverter output is 10 Hz, only the IGBT performs the switching operation for 50 ms, and only the diode performs the switching operation for the remaining 50 ms. Therefore, only the IGBT chip generates a loss during the operation of the IGBT, and only the diode chip generates a loss during the operation of the diode. As is clear from the above description of the operation, IG
In the BT package, the period during which current flows through the IGBT and loss occurs differs from the period during which current flows through the diode and loss occurs. For this reason, in a press-contact IGBT package in which a plurality of IGBTs and diode chips are connected in parallel, if only the IGBT chips are concentrated in a part of the package, heat is intensively generated, so that heat radiation characteristics deteriorate. In addition, since current partially flows, current concentration is likely to occur. In addition, the IGBT package
It is necessary to pressurize the BT chip and the diode chip at the same time. However, since the thicknesses of the IGBT and the diode chip tend to be different, non-uniformity of the pressing force of the chip is likely to occur.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem, and is realized by arranging IGBT chips and diode chips not uniformly but scattered uniformly.

As a specific means, for example, in the case of a package in which square chips are arranged uniformly,
When four chips are selected to form a square around one corner of any chip from the placed chip group,
Arrange so that the number of diode chips is three or less. Therefore, since the IGBT chip and the diode chip are arranged in a distributed manner, the heat generating portion is dispersed, and the cooling efficiency is improved. In addition, since two types of chips having different thicknesses are dispersed and arranged, uniform pressing can be performed. The IGBT stack of the present invention presses a plurality of the above-mentioned press-contact IGBT packages simultaneously in series. The above pressure welding I
Since the GBT package has no bias in the pressing force and has excellent heat radiation characteristics, it is possible to provide an IGBT stack free from bias in the pressing force and partial concentration of current and heat even when the number of press-contact packages is increased. .

The power conversion circuit according to the present invention has the above-mentioned IGB
Since the number of press-fit IGBT packages included in each T-stack is increased, the number of stacks connected in series is reduced, so that the power conversion circuit can be downsized.

[0011]

FIG. 1 is a sectional view and a plan view of a press-contact IGBT package showing an embodiment of the present invention. FIG.
FIG. 3A is a cross-sectional view of the embodiment of the present invention, in which 14 is a diode chip, and 11 is an IGBT chip. The collector electrode of the IGBT and the cathode electrode of the diode are in contact with the collector electrode plate 15 through a metal 12 such as molybdenum. The emitter electrode of the IGBT and the anode electrode of the diode are in contact with the emitter electrode plate 16 through the metal 13. Here, the metals 12 and 13 are preferably made of a material having the same thermal expansion coefficient as the substrate material of the IGBT and the diode. For example, when the IGBT and the diode are silicon, it is preferable to use a metal such as molybdenum. The collector metal plate 15 and the emitter electrode plate 16 are preferably made of a metal having excellent electric resistance and thermal conductivity, such as copper. In the embodiment of FIG. 1, current flows from the collector electrode plate 15 to the emitter electrode plate 16 when the IGBT is operating, and from the emitter electrode plate 16 to the collector electrode plate 15 when the diode is operating.

FIG. 1B shows an example of an arrangement pattern of IGBTs and diodes in the IGBT package of the present invention. 1991 and 1992 show an example in which four chips are selected so as to form a square around one corner of an arbitrary chip. 1991 is for one diode chip, and 1992 is for two diode chips. In any case, the number of diode chips is three or less, which satisfies the scope of the present invention. Here, one diode chip and two diode chips are shown, but an arrangement including three diode chips may be used. Further, the present invention is directed to selecting four chips and including three or less diodes therein, and is directed to an IGBT package including at least four or more diode chips. For example, if the total number of diode chips is three IGBT packages, and four chips are selected to form a square around one corner of any chip, and three diode chips are included, the other The area is only IGBT chip, diode chip and I
The GBT chips are arranged in a concentrated manner. This is contrary to the gist of the present invention, and the present invention is directed to an IGBT package including four or more diode chips.

Further, the loss of the diode is usually about half that of the IGBT, and the IGBT package is manufactured by conducting a current twice as large as that of the IGBT in the diode.
By doing so, the heat generated by the IGBT chip and that of the diode chip are equalized, and the IGBT package can be configured with the smallest number of chips. That is,
It is best to use an IGBT package in which the number of diode chips is half the number of IGBT chips. Therefore, when four sets as shown in 1991 and 1992 are selected at an arbitrary place, it is preferable that the arrangement of the diodes is such that one or two diode chips are included therein.

FIG. 2 is a plan view showing another embodiment of the present invention. In FIG. 1B, a diode chip is included in each of the vertical and horizontal lines, but in FIG. 2, a line including a diode and a line including the diode are alternately arranged. In the arrangement shown in FIG. 2, the current paths and the heat generating portions are distributed best because there is no portion adjacent to the diode chip.

FIG. 3 is a plan view showing another embodiment of the present invention. In this example, the columns have diode chips in every column, but the horizontal column has a distribution in which columns with and without diode chips are alternately arranged. Also in this case, the number of diode chips included in 1991 is three or less, which satisfies the scope of the present invention.

FIGS. 1 to 3 assume that the IGBT package is a square, but the shape of the package is not limited to a square. FIG. 4 shows an example in which a circular IGBT package is realized by the diode arrangement of FIG. Also in this case, the number of diode chips is three or less, which satisfies the present invention. In the case of a package in which a chip is fixed by applying pressure from both sides, if the package shape is a quadrangle, the pressure at the corners tends to increase, and it is difficult to uniformly pressurize the entire package. In contrast,
Circular package is easy to pressurize uniformly, and press-fit type IG
This is a desirable shape for a BT package.

FIG. 5 shows an embodiment in which a circular package is realized by the diode arrangement method shown in FIG. Also in this case, the number of diode chips included in 1991 is three or less, which satisfies the scope of the present invention.

FIG. 6 shows a circular package realized by the arrangement shown in FIG. 3, which also satisfies the scope of the present invention.

The method of arranging the IGBT chip and the diode chip according to the present invention is effective in a package of a type in which pressure is applied from the collector electrode plate 15 and the emitter electrode plate 16 side. However, the present invention is not limited to this. For example, a package in which the emitter electrode side is wired with a wire may be used.

FIGS. 7 to 9 show an embodiment of an inverter circuit using the press-contact IGBT package of the present invention. FIG. 7 is an example of an inverter circuit for driving a three-phase induction motor using the diode of the present invention. 8 and 9 are arrangement diagrams of specific components of the inverter circuit of FIG. Two switching elements (eg IG
BT11 and IGBT12) are connected in series. A flywheel diode DF is connected to each switching element in parallel. Furthermore, a so-called snubber circuit S is connected to each switching element in parallel in order to protect the switching element from a sudden increase in voltage during switching. This snubber circuit has a resistor RS and a capacitor CS connected in series.
The connection points of the two switching elements in each phase are connected to AC terminals T3, T4, and T5, respectively. A three-phase induction motor is connected to each AC terminal. The anode terminal of the switching element on the upper arm side is common to all three, and is connected to the high potential side of the DC voltage source at the DC terminal T1. The cathode electrode of the switching element on the lower arm side is 3
Each of them is common and is connected to the low potential side of the DC voltage source at the DC terminal T2. In the device having such a configuration, the three-phase induction motor is driven by converting DC into AC by switching of each switching element.
Note that the snubber circuit may be a circuit having a configuration in which a capacitor is arranged in series with a parallel circuit of a diode and a resistor.

The present invention is based on the fact that the IGBT and the diode do not operate simultaneously in the IGBT package. Hereinafter, this description will be made using the three-phase inverter circuit of FIG. Although FIG. 7 shows a three-phase inverter, the case of three phases can be easily understood from consideration of one phase.

FIG. 7 (b) shows the voltage V1 and the current I1 at the points shown in the inverter circuit diagram of FIG. 7 (a). I
1 defines the current flowing toward the output terminal T3 as positive, and the reverse as negative. The period A in FIG. 7 is a case where the current is positive, and the period B is a case where the current is negative. Voltage V1 at the connection point between IGBT11 and IGBT12
Fluctuates periodically due to the switching operation of IGBT11 and IGBT12, and becomes DC voltage Vcc when IGBT11 is on and IGBT12 is off and vice versa. When the ON period of the IGBT 11 is long and the OFF period of the IGBT 12 is short, the average voltage of V1 increases and vice versa. FIG.
(B) shows this state, and is a waveform of the average value of the voltage V1.

First, the case where the current I1 is a positive current (flows toward the output terminal T3) will be described. IGBT
When 11 is on and IGBT 12 is off, current flows through IGBT 11 and is supplied to the output. Next, when the IGBT 11 is turned off and the IGBT 12 is turned on, the output current flows through the diode DF12 and is supplied. At this time, even if the gate signal of IGBT12 is on,
Since the IGBT 12 has a structure in which no current flows from the emitter electrode to the collector, no current flows through the IGBT 12. Again, when IGBT11 turns on and IGBT12 turns off, the current
Supplied from the IGBT 11, the diode DF12 is turned off. Thereafter, this is repeated. That is, when the current I1 is positive, the IGBT 11 and the DF 12 repeat the ON state and the OFF state.

Next, a case where the output current is a negative current will be described. When the IGBT 11 is on and the IGBT 12 is off, the current flows through the diode DF11, so that even if the gate signal of the IGBT 11 is on, no current flows through the IGBT 11 and the IGBT 11 is inactive. Next, when the IGBT 11 is turned off and the IGBT 12 is turned on, the current flows through the IGBT 12, and the diode DF11 is turned off. Next, when the IGBT 11 is turned on again and the IGBT 12 is turned off, the current flows through the diode DF11, and thereafter, the above state is repeated. That is, when the current I1 is negative, the IGBT12
And the diode DF12 operates. In the actual operation of the inverter, if the IGBT11 and IGBT12 are turned on at the same time, the DC terminals T1 and T2 are short-circuited and a large current flows. Therefore, a time is provided to turn off both the IGBT11 and IGBT12. doing.

As is apparent from the above description, in the inverter device, the upper arm IGBT and the lower arm diode or the upper arm diode and the lower arm IGB
T may work as a pair, but I
The GBT and the diode or the lower arm IGBT and the diode do not operate at the same time. Then, the pair of the IGBT and the diode that are operating at the same time switches every half of the basic period of the output. Therefore, IGB
IGBT with T and diode in the same package
In the package, the period during which the IGBT and the diode operate to cause a loss is switched every half cycle of the basic cycle of the inverter output. Therefore, these chips are distributed and arranged so that heat is not concentrated and the cooling effect is excellent. Package.

FIG. 8 shows an embodiment of the present invention.
The package of FIG. 7 realizes the inverter device of FIG. 7 and is called an IGBT stack. 1 is an IGBT package of the present invention shown in FIG.
It has a structure in which a large number are arranged with 2 interposed therebetween. 81 indicates an upper arm of the inverter of FIG. 7, and 82 indicates a lower arm. The upper arm is, in order from the top, a metal plate 891, an insulator 8
3, metal plate 892, IGBT package 1, metal plate 89
3, which is a structure in which many IGBT packages are connected in series. The number of series can be adjusted as needed. For example, the number of series of IGBT packages may be one. 831 is an IGBT
It usually covers the periphery of the package and is preferably made of an insulator such as ceramic. Reference numeral 84 denotes a screw for fixing the IGBT stack. The metal rod 88 is fixed to fix the entire stack 87.

A snubber resistor 86 and a snubber capacitor 85 are connected in series between metal plates at both ends of one IGBT package to form a snubber circuit. The configuration of the snubber circuit is not limited to the configuration of FIG. For example,
A snubber circuit having a configuration in which a snubber diode is inserted in parallel with the snubber resistor may be used. In the case of the snubber circuit configuration described above, the time constant, which is the product of the snubber capacitor and the snubber resistance, has a value appropriate for the withstand voltage class of the IGBT used. For example, withstand pressure of 1000 or more and 2
000 V or less, 0.1 to 1 μs, and 2,000 V to 4000 V, 0.5 μs to 2 μs, 4000 V
0.8 to 4 μs, 6000 V for 6000 V or more
From above to below 10000V, 1.5 to 6 μs
It is better to set to about. By setting such a value, the IGBT generated when the IGBT is turned off is
The surge voltage which leads to the destruction of the circuit can be effectively prevented, and the snubber loss generated by the snubber circuit is minimized.
From the center of the stack 87, the inverter output is output to the outside as T3 through a metal plate. In the case of three-phase output, three of these stacks 87 are provided.
The current of the stack in FIG. 8 flows from top to bottom during IGBT operation, and from bottom to top during diode operation.

In the IGBT package of the present invention, since the IGBT chip and the diode chip are arranged in a distributed manner, the pressing force of the chip becomes uniform, and even if a stack in which a large number of IGBT packages are arranged in series is simultaneously pressed, the stack is distorted. Does not occur, and the current in the IGBT package is dispersed and flows, so that the inductance of the stack portion is reduced. Furthermore, since the heat generating portions are not concentrated, an IGBT stack having excellent cooling characteristics can be realized, and the cooling equipment for the stack can be reduced in size. FIG.
It is an embodiment of an inverter device having a structure in which an upper arm and a lower arm are separated. Such a configuration has the advantage that the number of IGBT packages per stack can be reduced, so that uniform pressing can be performed. This structure is shown in FIG.
, The detailed description is omitted. The package of the present invention is effective even in the inverter device having such a structure, and provides a stack in which distortion of the stack at the time of pressurization is eliminated and current and heat are not concentrated.

The stack of the upper arm and the lower arm may be divided into a plurality of stacks. For example,
If the number of series of one IGBT package is about 20, it is preferable to divide each IGBT package into four stacks of five.

Although the IGBT has been described in the above embodiments, the present invention is not limited to the IGBT chip, and the switching element may be any element. For example, the switching element is a MOSFET, GTO, M
It may be a CT (MOS Controlled Thyristor) or the like. The present invention is effective when a plurality of switching element chips and diode chips are incorporated in the same package.

[0031]

According to the present invention, the package in which the IGBT chip and the diode chip are arranged in a dispersed manner can avoid the concentration of the current and the heat generating portion. Therefore, the inductance can be reduced and the size of the cooling equipment can be reduced. In addition, since the IGBTs and the diode chips having different heights are arranged in a distributed manner, the distortion generated when a large number of packages such as a stack are simultaneously pressed can be reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an arrangement method of an IGBT and a diode chip according to the present invention.

FIG. 2 shows another embodiment of the chip arrangement method of the present invention.

FIG. 3 shows another embodiment of the chip arrangement method of the present invention.

FIG. 4 shows an embodiment of a chip arrangement method when a circular package is realized by the present invention.

FIG. 5 shows another embodiment of a chip arrangement method when a circular package is realized by the present invention.

FIG. 6 shows another embodiment of a chip arrangement method when a circular package is realized by the present invention.

FIG. 7 is a diagram illustrating an operation of the inverter circuit of the present invention.

FIG. 8 shows a specific embodiment of the inverter circuit of the present invention.

FIG. 9 shows another specific embodiment of the inverter circuit of the present invention.

[Explanation of symbols]

1 IGBT package of the present invention, 11 IGBT chip, 14 diode chip, 12 metal such as molybdenum, 15 collector electrode plate, 16 emitter electrode plate
IGBT11: switching element, DF11: freewheel diode, 81: upper arm, 82: lower arm.

Claims (3)

[Claims] 1. A package including a plurality of self-excited switching element chips and at least four or more diode chips connected in anti-parallel to the switching element chips, wherein the chip is continuous around any chip corner in the package. A package characterized in that switching elements and diodes are arranged such that the number of diode chips included therein is three or less even when four chips are selected. 2. The switching element package according to claim 1, wherein the switching element is an element having an insulated gate structure. 3. The switching device according to claim 1, wherein
A switching element package, which is a GBT.