JP5119741B2 - Switching module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce conduction noise and radiation noise by further reducing stray capacitance leading to common mode current. <P>SOLUTION: An insulating substrate 11 is mounted on a copper base 10 for cooling. Copper patterns 12, 13, and 18, which are separated from one another, are formed on the insulating substrate 11. A convex part 19 is formed corresponding to the arrangement position of the copper pattern 18 in the insulating substrate 11. The thickness in the insulating substrate 11 of the region, in which the copper pattern 18 is formed, is constructed so as to be thicker than the thickness in the insulating substrate 11 of the region, in which the copper patterns 12 and 13 are formed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a switching module, and is particularly suitable for application to a mounting method of an upper and lower two-arm series circuit configured with a switching element and a diode connected in reverse parallel thereto as one arm.

In order to convert input power obtained from a commercial AC power source into power of a predetermined frequency by a semiconductor switching element and output the power, a power conversion device such as an inverter is used.
FIG. 6 is a diagram illustrating an example of a power converter using an inverter.
In FIG. 6, a three-phase AC power supply 41 is connected to an inverter 43 via a rectifier 42 and a smoothing capacitor C4, and the inverter 43 is connected to a motor 44. Each phase of the three-phase AC power supply 41 is grounded via grounding capacitors C1 to C3 in order to reduce common mode noise. Here, the rectifier 42 is provided with rectifier diodes D1 to D6, and the inverter 43 is provided with switching elements M11 to M16 and feedback diodes D11 to D16 connected in reverse parallel to the switching elements M11 to M16, respectively. Yes.

As the switching elements M11 to M16, for example, an IGBT (Insulated Gate Bipolar Transistor) or a power MOSFET can be used.
The AC voltage generated by the three-phase AC power supply 41 is converted into a DC voltage by the rectifier 42 and the smoothing capacitor C4, and the DC voltage is converted into an AC voltage by the inverter 43 and supplied to the motor 44.

  Here, a basic circuit (arm) is configured by a set of the switching elements M11 to M16 and the feedback diodes D11 to D16, and the inverter 43 can be configured by using six arms. Then, assuming that each switching element M11 to M16 and each feedback diode D11 to D16 connected in antiparallel to one arm are one arm, the switching elements M11 and M14 constitute an upper and lower two-arm series circuit, and the switching element M12, The upper and lower two-arm series circuit can be configured by M15, and the upper and lower two-arm series circuit can be configured by the switching elements M13 and M16. The inverter 43 can be configured by connecting these three sets of upper and lower two-arm series circuits in parallel.

Note that the inverter module can be configured as one pair (2 in 1 type) for the upper and lower two arms, or one group (6 in 1 type) for six arms. It can be connected in parallel or a 6-arm set can be used as it is.
The inverter module is installed on a heat sink 45 for cooling, and the heat sink 45 is connected to a ground potential for safety.

FIG. 7 is a perspective view showing an external configuration of a switching module on which upper and lower two-arm series circuits are mounted.
7, a sealing resin 102 is provided on a cooling copper base 101, and an output electrode 103 connected to the load side, a DC negative output electrode 104, a DC positive output electrode 105, an upper arm side The gate / emitter terminal 106 of the IGBT on the lower arm side is taken out from the sealing resin 102. Here, the copper base 101 is disposed so as to be in contact with the heat sink 45 of FIG. 4 and can be set to the same potential as the heat sink 45.

FIG. 8 is a plan view showing the mounting state of the IGBT mounted on the switching module of FIG. 7, and FIG. 9 is a cross-sectional view showing the mounting state of the IGBT mounted on the switching module of FIG.
8 and 9, each semiconductor chip 114, 115 can be formed with a switching element and a feedback diode connected in antiparallel thereto. In the following description, a method using an IGBT as a switching element will be described.

The upper arm side semiconductor chip 114 is mounted on the copper pattern 112 by soldering so that the IGBT emitter is on the upper side and the collector is on the lower side, and the lower arm side semiconductor chip 115 is the IGBT emitter. Is mounted on the copper pattern 113 by soldering so that the collector faces the upper side. Then, the upper terminal of the semiconductor chip 114 and the copper pattern 113 are connected by the bonding wire 116, thereby connecting the emitter of the IGBT mounted on the semiconductor chip 114 and the collector of the IGBT mounted on the semiconductor chip 115. An upper and lower two-arm series circuit can be formed.
Here, since the copper patterns 112 and 113 face the copper base 101 through the ceramic substrate 111, a stray capacitance is formed between the copper patterns 112 and 113 and the copper base 101. That is, stray capacitances are formed between the collector of the IGBT on the upper arm side and the copper base 101 and between the collector of the IGBT on the lower arm side and the copper base 101.

FIG. 10 is a diagram showing a common mode current path when the inverter having the two-element configuration of FIG. 6 is used.
In FIG. 10, the inverter module is mounted on a heat sink 45 having the same potential as the ground potential, and is between the collector of the IGBT on the upper arm side and the copper base 101 and between the collector of the IGBT on the lower arm side and the copper base 101. The stray capacitances C5 and C6 formed in the circuit are also connected to the ground potential. The common mode current mainly flows through the common mode current path RC passing through the stray capacitances C5 and C6.

  However, when the IGBT actually performs a switching operation, there is no potential fluctuation in the stray capacitance C5, and therefore no charge / discharge current flows, and the charge / discharge current that flows mainly in the stray capacitance C6 becomes the common mode current. If the potential fluctuation caused by the common mode current is transmitted to other devices as conduction noise, it causes a malfunction. In addition, since this common mode current is usually a high frequency current, when this common mode current flows, the common mode current path RC becomes a loop antenna and unnecessary electromagnetic waves are radiated as radiated noise, causing malfunction of other devices. Cause.

Here, conduction noise and radiation noise depend on the magnitude of the common mode current, and the magnitude of the common mode current is proportional to the stray capacitance of the IGBT. Therefore, as the stray capacitance of the IGBT increases, the conduction noise and radiation noise are increased. Also grows.
As countermeasures against such conduction noise and radiation noise caused by the common mode current, methods such as laminating wiring and ground electrodes and providing grounding capacitors C1 to C3 are taken for the part outside the inverter module. A method of reducing radiation noise by reducing the common mode current has also been proposed (Patent Document 1).
Further, in the prior application (Japanese Patent Application No. 2005-378743) by the present applicant, the common mode current is reduced by reducing the area of the mounting pattern connecting the low potential side terminal of the upper arm and the high potential side terminal of the lower arm. A method for reducing the amount of conduction noise and radiation noise has been proposed.

4 is a cross-sectional view showing a schematic configuration of the switching module of the prior application, and FIG. 5 is a plan view showing a schematic configuration of the switching module of FIG.
4 and 5, an insulating substrate 31 is mounted on a copper base 30, and copper patterns 32, 33, and 38 that are separated from each other are formed on the insulating substrate 31. The semiconductor chips 34 and 35 are each formed with an IBGT and a feedback diode connected in antiparallel thereto.

  The semiconductor chip 34 on the upper arm side is mounted on the copper pattern 32 by soldering so that the emitter of the IGBT faces the upper side and the collector faces the lower side, and the semiconductor chip 35 on the lower arm side is the collector of the IGBT. Is mounted on the copper pattern 33 by soldering so that the emitter faces upward and the emitter faces downward. The upper terminal of the semiconductor chip 34 and the copper pattern 38 are connected by the bonding wire 36, and the upper terminal of the semiconductor chip 35 and the copper pattern 38 are connected by the bonding wire 37. By connecting the emitter of the IGBT mounted on and the collector of the IGBT mounted on the semiconductor chip 35, an upper and lower two-arm series circuit can be formed.

Here, by setting the copper pattern 38 to the minimum area for connecting the bonding wires 36 and 37, the stray capacitance C6 in FIG. 10 can be reduced, and the amount of common mode current can be reduced. it can.
In Patent Document 2, in order to reduce the parasitic capacitance generated between the ground electrode formed on the mounting substrate and the high-frequency circuit and to obtain good high-frequency characteristics, the ground potential is applied to the die pad portion. In a high-frequency switch IC package to which is applied, a method of mounting the high-frequency switch IC on a die pad portion via a spacer made of an epoxy resin is disclosed.
JP 2004-7888 A JP 2006-237450 A

However, in the switching module of the prior application shown in FIGS. 4 and 5, the copper patterns 32, 33 and 38 are formed on the same surface of the insulating substrate 31, so that it is not possible to reduce the stray capacitance C6 shown in FIG. There was a limit to reducing the amount of common mode current.
Therefore, an object of the present invention is to provide a switching module capable of reducing conduction noise and radiation noise by further reducing stray capacitance that causes a common mode current.

In order to solve the above-described problem, according to the switching module of claim 1, a plurality of switching elements constituting the upper arm and the lower arm,
An insulating substrate for mounting the plurality of switching elements;
A switching module comprising a conductive base plate for cooling the plurality of switching elements mounted on the insulating substrate ;
The plurality of switching elements respectively include a pair of electrodes through which a main current flows, on both sides,
The plurality of switching elements and the conductive base plate are disposed on one side and the other side of the insulating substrate, respectively.
The electrodes of the switching elements connecting the low potential side of the upper arm and the high potential side of the lower arm are respectively connected to copper patterns to which an alternating voltage is applied;
A copper to which a DC voltage is applied, wherein a high potential side electrode of the switching element constituting the upper arm and a low potential side electrode of the switching element constituting the lower arm are formed on one surface side of the insulating substrate Connected to each pattern,
The distance between the copper pattern where the AC voltage is applied to the conductive base plate, wherein longer than the distance between the copper pattern where the DC voltage is applied to the conductive base plate.

Further, according to the switching module of claim 2, a plurality of switching elements constituting the upper arm and the lower arm,
An insulating substrate for mounting the plurality of switching elements;
A switching module with a conductive base plate for cooling the plurality of switching elements mounted on the insulating base plate,
The plurality of switching elements respectively include a pair of electrodes through which a main current flows, on both sides,
The plurality of switching elements and the conductive base plate are disposed on one side and the other side of the insulating substrate, respectively.
Electrode a DC voltage of the switching elements constituting the upper arm is applied is connected to the first mounting pattern formed on one surface of the insulating substrate,
Electrode a DC voltage of the switching elements constituting the lower arm is applied is connected to the second mounting pattern formed on one surface of the insulating substrate,
Electrode an AC voltage is applied to the switching elements constituting the upper arm contact good beauty before Symbol lower arm is connected respectively to the third mounting pattern provided for each phase of the plurality of switching elements,
The distance between the third mounting pattern and the conductive base plate is longer than the distance between the first mounting pattern and the second mounting pattern and the conductive base plate .

According to the switching module of claim 3, the switching module includes an insulating substrate on which the first to third mounting patterns are formed, and a thickness of the region in which the third mounting pattern is formed on the insulating substrate. Is thicker than the thickness of the insulating substrate in the region where the first and second mounting patterns are formed.
According to the switching module of claim 4, the insulating substrate on which the first and second mounting patterns are formed, and the third mounting pattern formed on the surface, disposed on the insulating substrate. And an insulating spacer.
According to the switching module of claim 5, the insulating spacer has a relative dielectric constant smaller than that of the insulating substrate.

As described above, according to the present invention, the distance between a terminal having a potential variation when the switching element is operated , that is , a copper pattern (third mounting pattern) to which an AC voltage is applied, and the conductive base plate. Are switched so as to be longer than the distance between a conductive base plate and a terminal having no potential fluctuation , that is, a copper pattern (first mounting pattern and second mounting pattern) to which a DC voltage is applied. The element can be mounted, and it is possible to further reduce the stray capacitance causing the common mode current while ensuring the heat dissipation of the switching element. For this reason, it is possible to reduce conduction noise and radiation noise generated from the switching module while stably operating the switching element, it is possible to reduce malfunction of the external device, and conduction noise and radiation noise. Therefore, the switching module can be efficiently designed.

Hereinafter, switching modules according to embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a schematic configuration of the switching module according to the first embodiment of the present invention, and FIG. 2 is a perspective view showing a schematic configuration of an insulating substrate provided with the convex portion of FIG.
1 and 2, an insulating substrate 11 is mounted on a cooling copper base 10, and copper patterns 12, 13, and 18 separated from each other are formed on the insulating substrate 11. Here, convex portions 19 are formed on the insulating substrate 11 corresponding to the positions where the copper patterns 18 are arranged, and the thickness of the region in which the copper pattern 18 is formed in the insulating substrate 11 is the copper patterns 12 and 13. The formed region is configured to be thicker than the thickness of the insulating substrate 11.

The semiconductor chips 14 and 15 are each formed with an IBGT and a feedback diode connected in antiparallel thereto.
The semiconductor chip 14 on the upper arm side is mounted on the copper pattern 12 by soldering so that the emitter of the IGBT faces the upper side and the collector faces the lower side. The semiconductor chip 15 on the lower arm side is the collector of the IGBT. Is mounted on the copper pattern 13 by soldering so that the emitter faces upward and the emitter faces downward. The upper terminal of the semiconductor chip 14 and the copper pattern 18 are connected by the bonding wire 16, and the upper terminal of the semiconductor chip 15 and the copper pattern 18 are connected by the bonding wire 17. The IGBT emitter mounted on the semiconductor chip and the IGBT collector mounted on the semiconductor chip 15 are connected to form an upper and lower two-arm series circuit.

Here, the stray capacitance C5 of FIG. 10 is formed between the IGBT collector and the copper base 10 of the semiconductor chip 14 on the upper arm side, and the IGBT collector and copper base 10 of the semiconductor chip 15 on the lower arm side are formed. In the meantime, the stray capacitance C6 of FIG. 10 is formed.
However, when the IGBTs of the semiconductor chips 14 and 15 actually perform the switching operation, the charge / discharge current does not flow because the potential does not fluctuate ideally in the stray capacitance C5, and the charge / discharge current mainly flowing in the stray capacitance C6 is common. It becomes the mode current.

The copper pattern 18 constituting the stray capacitance C6 with the copper base 10 is set to a minimum area for connecting the bonding wires 16 and 17, thereby reducing the stray capacitance C6 in FIG. The amount of common mode current can be reduced.
Further, the IGBT is operated by configuring the insulating substrate 11 in the region where the copper pattern 18 is formed to be thicker than the insulating substrate 11 in the region where the copper patterns 12 and 13 are formed. In this case, the distance between the copper pattern 18 and the copper base 10 having the potential fluctuation when being made can be made larger than the distance between the copper patterns 12 and 13 and the copper base 10 having almost no potential fluctuation.

  For this reason, the distance between the copper pattern 18 and the base plate 10 can be increased to further reduce the stray capacitance C6 that causes the common mode current, and the amount of the common mode current is hardly increased. By reducing the distance between the copper patterns 12 and 13 and the base plate 10, the heat generated from the semiconductor chips 14 and 15 can be efficiently released to the copper base 10. For this reason, it is possible to reduce conduction noise and radiation noise generated from the switching module while ensuring heat dissipation of the semiconductor chips 14 and 15, thereby reducing malfunction of the external device, and conduction noise. And radiation noise standards can be easily satisfied, and the switching module can be designed efficiently.

FIG. 3 is a cross-sectional view showing a schematic configuration of a switching module according to the second embodiment of the present invention.
In FIG. 3, an insulating substrate 21 is mounted on a cooling copper base 20, and copper patterns 22 and 23 separated from each other are formed on the insulating substrate 21. An insulating spacer 29 is disposed on the insulating substrate 21, and a copper pattern 28 is formed on the insulating spacer 29. The insulating spacer 29 can be fixed on the insulating substrate 21 with an adhesive or the like. The insulating spacer 29 may be made of a material having the same relative dielectric constant as that of the insulating substrate 21, or may be made of a material having a relative dielectric constant smaller than that of the insulating substrate 21.

The semiconductor chips 24 and 25 are each formed with an IBGT and a feedback diode connected in antiparallel thereto.
The semiconductor chip 24 on the upper arm side is mounted on the copper pattern 22 by soldering so that the emitter of the IGBT faces the upper side and the collector faces the lower side, and the semiconductor chip 25 on the lower arm side is the collector of the IGBT. Is mounted on the copper pattern 23 by soldering so that the emitter faces upward and the emitter faces downward. Then, the upper terminal of the semiconductor chip 24 and the copper pattern 28 are connected by the bonding wire 26, and the upper terminal of the semiconductor chip 25 and the copper pattern 28 are connected by the bonding wire 27, whereby the semiconductor chip 24. The IGBT emitter mounted on the semiconductor chip and the IGBT collector mounted on the semiconductor chip 25 are connected to form an upper and lower two-arm series circuit.

  As a result, the distance between the copper pattern 28 and the copper base 20 having a potential fluctuation when the IGBT of the semiconductor chips 24 and 25 is operated is ideally determined as the distance between the copper patterns 22 and 23 and the copper base 20 having no potential fluctuation. The semiconductor chips 24 and 25 can be mounted to be larger than the distance, and it is possible to further reduce the stray capacitance C6 that causes the common mode current while ensuring the heat dissipation of the semiconductor chips 24 and 25. It becomes. For this reason, it is possible to reduce conduction noise and radiation noise generated from the switching module while stably operating the IGBT, and it is possible to reduce malfunction of an external device and to reduce conduction noise and radiation noise. The standard can be easily satisfied, and the switching module can be designed efficiently.

Further, by using a material having a relative dielectric constant smaller than that of the insulating substrate 21 as the insulating spacer 29, it becomes possible to further reduce the stray capacitance C6 that causes the common mode current. The generated conduction noise and radiation noise can be further reduced.
In the above-described embodiment, the inverter module on which the 2-in-1 type IGBT is mounted has been described as an example. However, the present invention is not limited to the above-described embodiment, and the number of arms and the type of the switching element are not limited. Can be applied.

It is sectional drawing which shows schematic structure of the switching module which concerns on 1st Embodiment of this invention. It is a perspective view which shows schematic structure of the insulating board | substrate provided with the convex part of FIG. It is sectional drawing which shows schematic structure of the switching module which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows schematic structure of the switching module of a prior application. It is a top view which shows schematic structure of the switching module of FIG. It is a figure which shows an example of the power converter device using the inverter carrying an upper and lower 2 arm series circuit. It is a perspective view which shows the external appearance structure of a switching module. It is a top view which shows the mounting state of IGBT mounted in the switching module of FIG. It is sectional drawing which shows the mounting state of IGBT mounted in the switching module of FIG. It is a figure which shows the common mode electric current path | route at the time of using the inverter of 2 element structure of FIG.

Explanation of symbols

10, 20 Copper base 11, 21 Insulating substrate 12, 13, 18, 22, 23, 28 Copper pattern 14, 15, 24, 25 Semiconductor chip 16, 17, 26, 27 Bonding wire 19 Protrusion 29 Insulating spacer

Claims (5)

A plurality of switching elements constituting the upper arm and the lower arm;
An insulating substrate for mounting the plurality of switching elements;
A switching module comprising a conductive base plate for cooling the plurality of switching elements mounted on the insulating substrate ;
The plurality of switching elements respectively include a pair of electrodes through which a main current flows, on both sides,
The plurality of switching elements and the conductive base plate are disposed on one side and the other side of the insulating substrate, respectively.
The electrodes of the switching element connecting the low potential side of the upper arm and the high potential side of the lower arm are respectively connected to copper patterns to which an alternating voltage is applied on the insulating substrate;
A copper to which a DC voltage is applied, wherein a high potential side electrode of the switching element constituting the upper arm and a low potential side electrode of the switching element constituting the lower arm are formed on one surface side of the insulating substrate Connected to each pattern,
Switching module wherein a distance between the copper pattern and the conductive base plate which AC voltage is applied, characterized in that longer than the distance between the copper pattern where the DC voltage is applied to the conductive base plate . A plurality of switching elements constituting the upper arm and the lower arm;
An insulating substrate for mounting the plurality of switching elements;
A switching module with a conductive base plate for cooling the plurality of switching elements mounted on the insulating base plate,
The plurality of switching elements respectively include a pair of electrodes through which a main current flows, on both sides,
The plurality of switching elements and the conductive base plate are disposed on one side and the other side of the insulating substrate, respectively.
Electrode a DC voltage of the switching elements constituting the upper arm is applied is connected to the first mounting pattern formed on one surface of the insulating substrate,
Electrode a DC voltage of the switching elements constituting the lower arm is applied is connected to the second mounting pattern formed on one surface of the insulating substrate,
Electrode an AC voltage is applied to the switching elements constituting the upper arm contact good beauty before Symbol lower arm is connected respectively to the third mounting pattern provided for each phase of the plurality of switching elements,
Switching characterized in that a distance between the third mounting pattern and the conductive base plate is longer than a distance between the first mounting pattern and the second mounting pattern and the conductive base plate. module. An insulating substrate on which the first to third mounting patterns are formed;
The thickness of the insulating substrate in the region where the third mounting pattern is formed is thicker than the thickness of the insulating substrate in the region where the first and second mounting patterns are formed. Item 3. A switching module according to item 2. It said first and second mounting pattern is disposed in front Symbol insulating substrate formed of claim 2, wherein said third mounting pattern is characterized in that it comprises an insulating space Sa formed on the surface Switching module.   The switching module according to claim 4, wherein the insulating spacer has a relative dielectric constant smaller than that of the insulating substrate.

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