JP2006351934A - Semiconductor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor module, which can configure many types of semiconductor power converters by a small number of types of semiconductor modules, and which can miniaturize the power converters. <P>SOLUTION: In the semiconductor module, where a plurality of semiconductor chips are placed on a metal base plate via a heat-conducting insulating material, the base plate is exposed partially, and the periphery is sealed by an insulator, the semiconductor chip has a connection terminal taken to the outside independently in units of one chip or a plurality of chips, and the insulating material has an insulation breakdown voltage withstanding voltage that is equal to or more than the rated voltage of a series of two chips. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor module in which a plurality of semiconductor elements connected in series and parallel, which are used to reduce the size of a power conversion device composed of semiconductor elements, are integrated.

    Semiconductor power converters such as inverters have a wide range of voltage ratings from high voltage to low voltage, and current ratings are also selected from large to small currents. Currently, products with current ratings are being produced and used. Furthermore, the type is still in an expanding trend because of the demand for higher capacity and higher voltage of the device.

  For this reason, elements having various voltages and current capacities are also required for the power semiconductor elements that are the main part of the semiconductor power converter. When using a semiconductor element that does not satisfy the high voltage and large current specifications required for the semiconductor power conversion device, it is necessary to connect a plurality of elements in series and parallel.

  Patent Document 1 discloses a conventional example of an IGBT module that meets the above requirements and a high-voltage inverter that is configured by connecting them in series.

  FIG. 5 shows a configuration of a conventional IGBT module disclosed in Patent Document 1. In FIG.

  In FIG. 5, 101a is a collector external electrode terminal, and 101b is an emitter external electrode terminal. 102 is a housing made of insulating resin, 103 is an insulating member made of insulating resin, and 104 is a metal base plate to be attached to the cooling body. 105a is a collector side conductive member, 105b is an emitter side conductive member, 106a is a collector side relay substrate, and 106b is an emitter side relay substrate. 107 is an IGBT chip, 108a is a collector internal electrode, 109 is a ceramic insulating plate having high thermal conductivity, and 110 is a bonding wire.

  In such an IGBT module, the IGBT chip 107 generates heat when energized. If this is left unattended, a failure such as burning of the chip occurs, and cooling is necessary. Therefore, in the semiconductor module used in this conventional example, the metal base plate 104 is coupled to a cooling body (not shown) to actively cool the semiconductor chip.

  From the viewpoint of electrical insulation technology, the cooling body placed at the ground potential and the IGBT chip 107 at the main circuit potential need to be electrically insulated. In this conventional semiconductor module, a ceramic insulating plate 106 having high thermal conductivity is sandwiched between an IGBT (semiconductor) chip 107 and a base plate 104 to insulate the two, and the base plate 107 and the cooling body have the same potential. It is possible to leave.

  FIG. 6 shows a configuration of one phase of a two-level inverter circuit configured by connecting two IGBT modules configured as described above in series. A broken line frame 100 indicates an IGBT module. 104 in the broken line frame is a metal base plate, 109 is a ceramic insulating plate that conducts heat between the base plate 104 and the IGBT chip 107, and 220 is The cooling body is coupled to the base plate 104 and dissipates heat generated by the IGBT chip 107 and the like to the atmosphere.

  In general, in an inverter circuit, a connected semiconductor circuit connected between a P terminal and an output terminal R is called an upper arm, and a semiconductor circuit connected between an N terminal and the output terminal R is called a lower arm. . In the example of FIG. 6, two IGBT module groups connected in series with each other are used for the upper and lower arms. Further, since the E4 terminal connected to the N terminal of the lower arm and the cooling body 220 are grounded, the N terminal and the cooling body 220 are fixed to the ground potential. Further, although not shown, a DC power supply for supplying DC power is connected between the P terminal and the N terminal, and a DC voltage Ed is applied. An AC load device is connected to each output terminal R.

  The rated voltage of the DC power supply voltage Ed is 1.2 × 2 = 2.4 kV when using an IGBT module group in which two IGBT modules with a rated voltage of 1.2 kV are connected in series.

  As apparent from FIG. 6, the same voltage as the rated voltage Ed (eg, 2.4 kV) of the DC power supply is applied between the C1 terminal and the cooling body 220, but the rated voltage of one IGBT module 100 is applied. In this case, no measures for enhancing the withstand voltage are taken in spite of being ½ of the rated voltage of the DC power supply (for example, 1.2 kV). For this reason, in such a conventional semiconductor power conversion device, even if the configuration is such that two semiconductor modules are connected in series, the withstand voltage cannot be increased, and there is a disadvantage in that one semiconductor module is insufficient in withstand voltage.

  In order to solve such inconvenience, a means as shown in FIG. 7 has been proposed.

  In FIG. 7, four IGBT modules 100 each have the same structure as the IGBT module shown in FIG. 5, and two IGBT modules 100 are connected in series to form the same circuit as the inverter circuit shown in FIG. Then, an insulating sheet 230 is added and coupled to the cooling body 220 via the insulating sheet. This insulating sheet 230 is also made of an insulating material having high thermal conductivity, like the ceramic insulating plate used in the IGBT module. In addition, the insulating sheet 230 is provided with a withstand voltage higher than the shortage (1.2 kV) in order to compensate for the shortage (1.2 kV) of the withstand voltage of one IGBT module in the circuit of FIG. .

Therefore, the apparatus of FIG. 7 is the same as the apparatus shown in FIG. 6 in which a new insulating sheet 230 is interposed between the base plate 104 and the cooling body 220 of each IGBT module. The newly added insulation sheet 230 can compensate for the insulation breakdown voltage of 1.2 kV that is insufficient in the apparatus shown in FIG. 6, and eliminates the need to lower the DC power supply voltage rating.
JP 2003-174882 A

  In the conventional apparatus shown in FIG. 7, the insufficient insulation withstand voltage of the IGBT module can be solved, but there are the following problems.

  First, since a new insulating sheet is required, the cost increases due to the increase in the number of parts, and the thermal resistance between the IGBT module and the heat sink increases, so that the cooling performance is reduced and the rating of the device is reduced. The capacity is reduced.

  Secondly, in the conventional apparatus, the semiconductor chips are housed one by one to form a module. Therefore, in the case of multi-series connection, it is necessary to arrange a large number of semiconductor modules, which increases the installation space and increases the size of the apparatus. Is to become.

  In order to solve such a problem, the present invention provides a semiconductor module in which a large number of types of semiconductor power conversion devices can be configured with a small number of types of semiconductor modules, and the size of the device can be reduced. Is an issue.

  In order to solve the above-mentioned problems, the present invention is configured such that a plurality of semiconductor chips are placed on a metal base plate via a heat conductive insulating material, a part of the base plate is exposed, and the periphery is made of an insulator. In a sealed semiconductor module, the semiconductor chip has a connection terminal that is independently pulled out for each chip or a plurality of chips, and the insulating material has a voltage higher than the rated voltage for two chips in series. It is characterized by having a withstand voltage that can withstand.

  According to the present invention, since a plurality of semiconductor chips are incorporated in one module and the respective connection terminals are drawn to the outside, the number of series-parallel connections can be freely changed according to a desired circuit configuration. For this reason, one module can be applied to many types of power conversion devices having different rated voltages and currents, and the ground space of the module can be reduced as compared with the case where a plurality of modules are combined. Effects such as miniaturization become possible.

  In the present invention, the withstand voltage is enhanced so that the insulating material in the module has a withstand voltage higher than the rated voltage of the two chips combined. There is no shortage and no additional insulation is required.

  Embodiments of the present invention will be described with reference to embodiments shown in the drawings.

  FIG. 1 shows a first embodiment of the present invention.

  In FIG. 1, 10 is a semiconductor module, and 20 is a cooling body attached to this module. The semiconductor module 10 is obtained by incorporating four semiconductor chips 13-1 to 13-4 into one module. The semiconductor chips 13-1 to 13-4 are electrically insulating plates 16 made of a highly thermally conductive ceramic plate or the like on a base plate 18 made of a highly thermally conductive metal such as copper for bonding to the cooling body 20. Are placed at predetermined intervals. These chips are surrounded by an insulating case 15 and sealed with an insulating sealing material 11 such as a gel-like silicone resin filled therein. The external connection terminals 14c-1, 14e-1 to 14c-4, and 14e-4 of each chip are drawn out to the outside of the case 15 and can be connected to an external circuit. The base plate 18 is fastened to the cooling body 20 with the mounting screw 17 to couple the semiconductor module 10 to the cooling body 20.

  The insulating plate 16 inserted between each of the semiconductor chips and the base plate 18 has a rated voltage equivalent to four when four semiconductor chips are connected in series, for example, by increasing its thickness. It is configured to have a withstand voltage that can withstand the above voltages.

  When the semiconductor module configured in this manner is used in an actual semiconductor power conversion device, the rated voltage can be changed by changing the connection as shown in FIG. 2 or FIG.

  First, FIG. 2 shows an example in which four semiconductor chips are used in series connection. Adjacent external connection terminals in the middle of each semiconductor chip are connected to each other by an external connection conductor 19, and a DC power supply voltage is applied between terminals 14c-1 and 14e-4 at both ends. As a result, the rated voltage as a module is 4 kV for four chips if the rated voltage of one chip is 1 kV, and can be used under a DC power source of 4 kV. At this time, if the cooling body 20 is grounded, a DC power supply voltage of 4 kV is applied between the external terminal 14c-1 of the chip 13-1 to which a positive power supply voltage is applied and the cooling body 20. However, since the insulating plate 16 is configured to have a withstand voltage that can withstand a voltage equal to or higher than the rated voltage corresponding to the series connection of the chips 4, the chip 13-1 can bear the voltage of 4 kV.

  FIG. 3 shows an example in which two circuits of four semiconductor chips connected in series are connected in parallel. By connecting the terminals 14e-1 and 14c-2 and 14e-3 and 14c-4 with external connection conductors, the chips 13-1 and 13-2 and 13-3 and 13-4 are respectively connected in series. Then, by connecting the terminals 14c-1 and 14c-3 and 14e-2 and 14e-4 respectively with external connection conductors, a circuit in which two chips are connected in series is connected in parallel.

  By connecting in this way, the rated voltage and rated current of the module are 2 kV and 200 A, respectively, when the rated voltage of one semiconductor chip is 1 kV and the rated current is 100 A. A voltage of 2 kV is applied between the semiconductor chips 13-1 and 13-3 to which the positive voltage of the DC power supply is applied, and the cooling body 20, but the insulating plate 16 has a withstand voltage that can withstand a voltage corresponding to the chip 4 in series. Since it is configured in this way, this can be fully handled.

  FIG. 4 shows a second embodiment of the present invention. In this embodiment, four semiconductor chips housed in an insulating case 15 are connected in series two by two in the case. Connection terminals 14c-1, 14e-2 and 14c-3, 14e-4 are drawn out from both ends of the two sets of two-chip series connection circuits, respectively. Other configurations are the same as those in the first embodiment.

  In such a semiconductor module, one 4-chip series connection circuit is formed by connecting in series using the external connection terminals of two sets of two-chip series connection circuits. As a result, the rated voltage of the module can be increased to a voltage corresponding to four series connections of the rated voltage of one chip. In this case, since the insulating plate 16 interposed between each semiconductor chip and the base plate 18 is configured to have a withstand voltage that can withstand a voltage equal to or higher than the voltage for four series connections, the withstand voltage is insufficient. There is nothing.

  When the external terminals of the 2-chip series connection circuit are connected in parallel, the 2-chip series circuit is connected in parallel, so that the operating voltage can be increased up to the voltage for 2 series, Can be increased to twice the current of one chip. The voltage applied to the insulating plate 16 in this case has no problem because the withstand voltage is as follows.

  As is clear from the description of the above embodiment, according to the present invention, the plurality of semiconductor chips arranged in the insulating case 15 are sealed with the insulating sealing material 11, so that the intervals are narrowed. In addition, it is possible to maintain sufficient insulation, and when the conventional one-chip unit is used, it is possible to eliminate most of the insulating case 15 and the mounting portion for each chip that are required. Compared to the case of using the module, the installation space of the module can be reduced.

  In addition, since the high thermal conductivity insulating plate provided in the module has a dielectric strength that can withstand a voltage equal to or higher than the number of serially connected semiconductor chips accommodated in the module, the cooling body to which the module is attached is grounded. In this case, since the withstand voltage is not insufficient, it is not necessary to add an insulating member, and the structure can be configured at low cost.

  Furthermore, since the semiconductor module according to the present invention can be changed considerably freely by the terminals that are connected to the outside in the series-parallel connection of a plurality of built-in semiconductor chips, more types of semiconductor power conversion devices can be obtained with fewer types of semiconductor modules. The effect which can comprise is acquired.

  In the above description, h is an embodiment using four semiconductor chips. However, the present invention is not limited to this, and any number of semiconductor chips can be used.

It is a longitudinal cross-sectional view which shows the structure of Example 1 of this invention. It is a longitudinal cross-sectional view which shows the usage example of the semiconductor module of Example 1 of this invention. It is a longitudinal cross-sectional view which shows the other usage example of a semiconductor module in Example 1 of this invention. It is a longitudinal cross-sectional view which shows the structure of Example 2 of this invention. It is a longitudinal cross-sectional view which shows the structure of the conventional semiconductor module. It is a block diagram which shows the usage example of the conventional semiconductor module. It is a longitudinal cross-sectional view which shows the usage example of the conventional semiconductor module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Semiconductor module 11: Insulation sealing material 13-1 to 13-4: Semiconductor chip 14: External connection terminal 15: Insulation case 16: High heat conductive insulating board 18: Base board 20: Heat radiator

Claims (1)

  In a semiconductor module in which a plurality of semiconductor chips are placed on a metal base plate via a heat conductive insulating material, and the base plate is partially exposed to be sealed with an insulator. The semiconductor chip is provided with a connection terminal that is pulled out to the outside independently for each chip or a plurality of chips, and the insulating material has a withstand voltage that can withstand a voltage higher than the rated voltage for all the chips in series. A featured semiconductor module.

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