WO2024004024A1

WO2024004024A1 - Power module and power conversion device

Info

Publication number: WO2024004024A1
Application number: PCT/JP2022/025730
Authority: WO
Inventors: 悠策伊藤
Original assignee: 三菱電機株式会社
Priority date: 2022-06-28
Filing date: 2022-06-28
Publication date: 2024-01-04
Also published as: JP7334369B1

Abstract

A power module (100A, 100B, 100C, 100D) is provided with a circuit board (10), a first semiconductor element (20), a conductor block (40), and a conductor (30). The first semiconductor element is disposed on the circuit board. The conductive block has an upper end (40a) and a lower end (40b). The conductive block is disposed on the first semiconductor element so that the lower end is electrically connected to the first semiconductor element. Liquid is sealed inside the conductor block. The conductor electrically connects the circuit board and the upper end.

Description

Power module and power converter

The present disclosure relates to a power module and a power conversion device.

For example, Japanese Patent Laid-Open No. 6-104355 (Patent Document 1) describes a semiconductor device. The semiconductor device described in Patent Document 1 includes a lead frame, a semiconductor chip, a cooling module, and a mold resin. A semiconductor chip is placed on a lead frame. The cooling module is placed above the semiconductor chip. A liquid is sealed inside the cooling module. The lead frame, semiconductor chip, and cooling module are sealed with mold resin. The semiconductor device described in Patent Document 1 has improved cooling efficiency using a cooling module.

Japanese Patent Application Publication No. 6-104355

In the semiconductor device described in Patent Document 1, in order to increase the cooling efficiency by the cooling module, it is necessary to reduce the distance between the semiconductor chip and the cooling module. However, reducing the distance between the semiconductor chip and the cooling module becomes an obstacle when the cooling module makes electrical connection between the lead frame and the semiconductor chip. More specifically, the cross-sectional area of a member (such as a wire) for electrically connecting the lead frame and the semiconductor chip becomes smaller, and the current density in the member becomes larger. This increase in current density becomes a factor that reduces the reliability of the semiconductor device described in Patent Document 1.

The present disclosure has been made in view of the problems of the prior art as described above. More specifically, the present disclosure provides a power module that can reduce the current density in the current path from the semiconductor element while suppressing the generation of thermal stress around the semiconductor element.

The power module of the present disclosure includes a circuit board, a first semiconductor element, a conductor block, and a conductor. The first semiconductor element is arranged on the circuit board. The conductor block has an upper end and a lower end. The conductor block is arranged on the first semiconductor element such that the lower end thereof is electrically connected to the first semiconductor element. A liquid is sealed inside the conductor block. The conductor electrically connects the circuit board and the top end.

According to the power module of the present disclosure, it is possible to reduce the current density in the current path from the semiconductor element while suppressing the generation of thermal stress around the semiconductor element.

It is a sectional view of power module 100A. FIG. 2 is a partially enlarged sectional view of the power module 100A. It is a process diagram which shows the manufacturing method of 100 A of power modules. FIG. 3 is a partially enlarged sectional view of power module 100B. FIG. 7 is a partially enlarged sectional view of a power module 100B according to a modification. FIG. 3 is a partially enlarged sectional view of the power module 100C. It is a partially enlarged cross-sectional view of a power module 100C according to a modification. It is a partially enlarged sectional view of power module 100D. FIG. 7 is a partially enlarged sectional view of a power module 100D according to a modification. 2 is a block diagram showing the configuration of a power conversion system 200. FIG.

Details of embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or corresponding parts, and overlapping descriptions will not be repeated. The following embodiments may be applied in combination as appropriate.

Embodiment 1.
A power module according to Embodiment 1 will be described. The power module according to the first embodiment is referred to as a power module 100A.

(Configuration of power module 100A)
The configuration of the power module 100A will be explained below.

FIG. 1 is a cross-sectional view of the power module 100A. FIG. 2 is a partially enlarged sectional view of the power module 100A. As shown in FIGS. 1 and 2, the power module 100A includes a circuit board 10, a plurality of semiconductor elements 20, a conductor 30, a wire 31, a plurality of conductor blocks 40, a base plate 50, and a case 51. and a sealing material 52.

The circuit board 10 has an insulating layer 11, a conductor pattern 12, and a conductor pattern 13. Insulating layer 11 has an upper surface 11a and a lower surface 11b. The upper surface 11a and the lower surface 11b are end surfaces of the insulating layer 11 in the thickness direction. The lower surface 11b is the opposite surface to the upper surface 11a. The insulating layer 11 is made of an electrically insulating material. The insulating layer 11 is made of, for example, alumina (Al ₂ O ₃ ), aluminum nitride (AlN), or the like.

The conductor pattern 12 is arranged on the upper surface 11a. The conductor pattern 13 is arranged on the lower surface 11b. The conductor pattern 12 and the conductor pattern 13 are made of a conductive material. The conductor pattern 12 is made of copper (Cu), for example. The conductor pattern 12 and the conductor pattern 13 may be composed of multiple layers. The conductor pattern 12 and the conductor pattern 13 may be composed of an aluminum (Al) layer on the insulating layer 11 side and a copper layer disposed on the aluminum layer.

The semiconductor element 20 is a power semiconductor element. The semiconductor element 20 is, for example, an IGBT (Insulated Gate Bipolar Transistor). However, the semiconductor element 20 is not limited to this. The semiconductor element 20 may be a MOSFET (Metal Oxide Field Effect Transistor). The semiconductor element 20 may be a Schottky barrier diode. The semiconductor element 20 is formed using, for example, a silicon (Si) substrate. The semiconductor element 20 may be formed using a substrate made of a wide bandgap semiconductor material such as a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, or a diamond substrate.

The semiconductor element 20 has an upper surface and a lower surface. The upper surface and the lower surface are end surfaces of the semiconductor element 20 in the thickness direction. The lower surface is the opposite surface to the upper surface. Although not shown, the semiconductor element 20 has electrodes on the upper and lower surfaces. When the semiconductor element 20 is an IGBT, the semiconductor element 20 has an emitter electrode and a gate electrode on the upper surface, and a collector electrode on the lower surface. When the semiconductor element 20 is a MOSFET, it has a source electrode and a gate electrode on the upper surface, and a drain electrode on the lower surface. The upper and lower electrodes of the semiconductor element 20 are made of, for example, aluminum or an aluminum alloy in which silicon is added to aluminum. Although not shown, a covering layer made of, for example, nickel (Ni), gold (Au), etc. may be disposed on the surfaces of the upper and lower electrodes of the semiconductor element 20.

The semiconductor element 20 is arranged on the circuit board 10. More specifically, the semiconductor element 20 is arranged on the conductor pattern 12. The electrodes on the lower surface of the semiconductor element 20 are bonded to the conductor pattern 12 with a bonding material 60 . Thereby, the semiconductor element 20 is electrically connected to the circuit board 10. The bonding material 60 is made of, for example, sintered silver particles, solder alloy, or the like.

The conductor 30 has one end 30a and the other end 30b. The conductor 30 is electrically connected to the circuit board 10 at one end 30a. More specifically, one end 30 a is bonded to the conductor pattern 12 with a bonding material 61 . The bonding material 61 is made of, for example, sintered silver particles, solder alloy, or the like. Thereby, the conductor 30 is electrically connected to the circuit board 10. Note that the one end portion 30a may be directly bonded to the conductive pattern 12 by ultrasonic bonding or the like. Further, the one end portion 30a may be connected to the conductor pattern 12 by screw fastening. The conductor 30 is made of copper, for example.

The wire 31 is connected to the conductor pattern 12 at one end, and to the electrode on the upper surface of the semiconductor element 20 (or the gate electrode if the semiconductor element 20 is an IGBT or MOSFET) at the other end. Thereby, the semiconductor element 20 is electrically connected to the circuit board 10. The bonding between the wire 31 and the electrode on the upper surface of the semiconductor element 20 and the bonding between the wire 31 and the conductor pattern 12 are performed, for example, by wire bonding. The wire 31 is made of, for example, gold, aluminum, copper, or the like. Note that, for example, a control signal for the semiconductor element 20 flows through the wire 31. The power module 100A may include a conductive member for electrically connecting the conductor pattern 12 and the semiconductor element 20 instead of the wire 31.

The conductor block 40 has an upper end 40a and a lower end 40b. The conductor block 40 is arranged on the semiconductor element 20. The lower end 40b is bonded to an electrode on the surface of the semiconductor element 20 (an emitter electrode when the semiconductor element 20 is an IGBT, and a source electrode when the semiconductor element 20 is a MOSFET) by a bonding material 62. Thereby, the conductor block 40 is electrically connected to the semiconductor element 20 at the lower end 40b.

A hole 41 is formed in the upper end 40a. The hole 41 extends toward the lower end 40b. The upper end 40a side of the hole 41 is a screw hole 42 (female thread). The conductor 30 is fastened to the upper end 40a by screwing the screw 43 into the screw hole 42. Thereby, the conductor block 40 is electrically connected to the conductor 30. The screw 43 is made of copper, for example. A liquid 44 is sealed in the hole 41 . That is, a liquid 44 is sealed inside the conductor block 40. The liquid 44 is, for example, water, fluorocarbon, halofluorocarbon, hexachloroethane, fluorinate, fluorine-based inert liquid, or the like. Although not illustrated, the inner wall surface of the hole 41 that comes into contact with the liquid 44 may be subjected to surface treatment such as metal plating.

The circuit board 10 is arranged on the upper surface of the base plate 50. More specifically, the circuit board 10 is arranged on the base plate 50 by bonding the conductive pattern 13 to the upper surface of the base plate 50 using the bonding material 63. The bonding material 63 is made of, for example, sintered silver particles, solder alloy, or the like. The base plate 50 is made of, for example, copper, silicon carbide particle reinforced aluminum composite material (AlSiC), or the like. The power module 100A does not need to have the base plate 50 and the bonding material 63. In this case, conductive pattern 13 is used instead of base plate 50. Further, in this case, the insulating layer 11 may be formed of an electrically insulating resin material.

The case 51 is attached to the outer peripheral edge of the base plate 50. Case 51 extends along a direction intersecting the upper surface of base plate 50. Case 51 is made of electrically insulating material.

The space defined by the upper surface of the base plate 50 and the inner wall surface of the case 51 is filled with a sealing material 52. Thereby, the circuit board 10, the semiconductor element 20, the conductor 30, the wire 31, and the conductor block 40 are sealed. The sealing material 52 is made of a thermosetting resin material. Examples of the thermosetting resin material include silicone and epoxy. In order to suppress softening and deterioration when exposed to high temperatures, the resin material constituting the sealing material 52 preferably contains a metal or filler that does not easily deteriorate at high temperatures.

Although not shown, a plurality of unevenness may be formed on the surface of the conductive pattern 12 opposite to the insulating layer 11. This improves the adhesion between the sealing material 52 and the conductor pattern 12. Further, in order to improve the adhesion between the sealing material 52 and the conductor pattern 12, the surface of the conductor pattern 12 may be coated.

(Manufacturing method of power module 100A)
A method of manufacturing the power module 100A will be described below.

FIG. 3 is a process diagram showing a method for manufacturing the power module 100A. As shown in FIG. 3, the method for manufacturing the power module 100A includes a first bonding step S1, a second bonding step S2, a third bonding step S3, a fourth bonding step S4, a conductor connection step S5, and a sealing step S6.

In the first bonding step S1, the electrode on the lower surface of the semiconductor element 20 and the conductor pattern 12 are bonded using the bonding material 60. The second bonding step S2 is performed after the first bonding step S1. In the second bonding step S2, the conductor block 40 (lower end 40b) and the semiconductor element 20 (electrode on the upper surface of the semiconductor element 20) are bonded using the bonding material 62. The third bonding step S3 is performed after the second bonding step S2. In the third bonding step S3, the conductor 30 (the other end 30b) and the conductor pattern 12 are bonded using the bonding material 61. The fourth bonding step S4 is performed after the third bonding step S3. In the fourth bonding step S4, the conductive pattern 13 is bonded to the base plate 50 using the bonding material 63.

The order in which the first bonding step S1, second bonding step S2, third bonding step S3, and fourth bonding step S4 are performed may be changed as appropriate. All or part of the first bonding step S1, the second bonding step S2, the third bonding step S3, and the fourth bonding step S4 may be performed simultaneously.

The conductor connection step S5 is performed after the first bonding step S1, the second bonding step S2, the third bonding step S3, and the fourth bonding step S4. In the conductor connection step S5, the conductor 30 is screwed to the upper end 40a by screwing the screw 43 into the screw hole 42, and the conductor 30 and the conductor block 40 are electrically connected.

The sealing step S6 is performed after the conductor connecting step S5. In the sealing step S6, the space defined by the upper surface of the base plate 50 and the inner wall surface of the case 51 is filled with the sealant 52. Filling with the sealant 52 is performed by, for example, supplying the sealant 52 from above using a dispenser or the like. Filling with the sealing material 52 may be performed in a first step and a second step.

In the first step, the power module 100A that has been subjected to the conductor connection step S5 is immersed in the sealing material 52 stored in the container and then pulled up. In the second step, the sealing material 52 is further supplied to the space defined by the upper surface of the base plate 50 and the inner wall surface of the case 51 in the power module 100A that has undergone the first step. Note that the sealing material 52 used in the first step and the sealing material 52 used in the second step may be different materials or may be the same material. Through the above steps, the power module 100A having the structure shown in FIGS. 1 and 2 is formed.

(Effect of power module 100A)
The effects of the power module 100A will be explained below.

When the power module 100A operates, the semiconductor element 20 generates heat. As a result, in the power module 100A, the semiconductor element 20 and the joints with the members connected to the semiconductor element 20 become high in temperature during operation. On the other hand, when cooling the power module 100A, the heat generated in the semiconductor element 20 is transmitted in this order to the bonding material 60, the conductive pattern 12, the insulating layer 11, the conductive pattern 13, the bonding material 63, and the base plate 50, and is transferred from the base plate 50 to the outside. The temperature of the semiconductor element 20 decreases by dissipating the heat.

When such temperature fluctuations occur, the bonding material may deteriorate due to the difference in the coefficient of thermal expansion between the semiconductor element 20 and the conductor block 40 and the difference in the coefficient of thermal expansion between the conductor pattern 12 and the semiconductor element 20. Thermal stress is generated in the bonding material 60 and the bonding material 62. This thermal stress concentrates on the ends of the bonding material 60 and the bonding material 62, causing the bonding material 60, the bonding material 62, the interface between the bonding material 60 and the conductive pattern 12 or the semiconductor element 20, Cracks may occur at the interface between the semiconductor element 62 and the semiconductor element 20 or the conductor block 40. When the above temperature fluctuations are repeated, cracks develop and eventually lead to electrical connections between the conductor pattern 12 and the semiconductor element 20 and between the semiconductor element 20 and the conductor block 40. will be resolved.

In the power module 100A, a liquid 44 is sealed inside the conductor block 40. Therefore, even if the semiconductor element 20 generates heat during the operation of the power module 100A, the heat generated in the semiconductor element 20 will be consumed by increasing the temperature of the liquid 44 and changing the phase of the liquid 44. Fluctuations in temperature between operation and cooling can be reduced. Since the liquid 44 has almost no rigidity, even if there is a difference in coefficient of thermal expansion between the liquid 44 and its surroundings, it does not cause thermal stress. In this way, according to the power module 100A, it is possible to reduce thermal stress around the semiconductor element 20.

Furthermore, the conductor block 40 functions not only as a member for enclosing the liquid 44 but also as a member for electrically connecting the semiconductor element 20 and the conductor 30. Therefore, in the power module 100A, there is no need to separately provide a current path from the semiconductor element 20, and even if the conductor block 40 and the semiconductor element 20 are placed close to each other, it is possible to reduce the current density in the current path from the semiconductor element 20. It is. Furthermore, in the power module 100A, since one conductor block 40 is arranged on one semiconductor element 20, positioning of the conductor block 40 in the first bonding step S1 is facilitated.

Embodiment 2.
A power module according to Embodiment 2 will be explained. The power module according to the second embodiment is referred to as a power module 100B. Here, differences from the power module 100A will be mainly explained, and overlapping explanations will not be repeated.

(Configuration of power module 100B)
The configuration of the power module 100B will be explained below.

FIG. 4 is a partially enlarged sectional view of the power module 100B. As shown in FIG. 4, the power module 100B includes a circuit board 10, a plurality of semiconductor elements 20, a conductor 30, a wire 31, a plurality of conductor blocks 40, a base plate 50, a case 51, and a seal. It has a stopper 52. In this regard, the configuration of power module 100B is common to the configuration of power module 100A. Note that in FIG. 4, illustration of the base plate 50 and the case 51 is omitted.

In the power module 100B, the hole 41 has an enlarged diameter portion 45 on the lower end 40b side. The enlarged diameter portion 45 has a larger inner diameter than the screw hole 42 . In this regard, the configuration of power module 100B is different from the configuration of power module 100A.

(Effects of power module 100B)
The effects of the power module 100B will be explained below.

In the power module 100B, the hole 41 has an enlarged diameter portion 45 on the lower end 40b side. Therefore, in the power module 100B, the volume of the sealed liquid 44, that is, the heat capacity of the sealed liquid 44, can be increased on the side closer to the semiconductor element 20, and temperature fluctuations between operation and cooling can be further reduced. Can be made smaller. As a result, according to the power module 100B, it is possible to further reduce thermal stress around the semiconductor element 20. Further, in the power module 100B, since the hole 41 has the enlarged diameter portion 45, the volume of the portion of the hole 41 in which the liquid 44 is not sealed can be increased, so that the pressure inside the hole 41 is increased. It is possible to reduce the

(Modified example)
A power module 100B according to a modified example will be described below.

FIG. 5 is a partially enlarged sectional view of a power module 100B according to a modification. As shown in FIG. 5, the semiconductor element 20 located at the center of the plurality of semiconductor elements 20 is referred to as a semiconductor element 20A. The semiconductor element 20 located outside the semiconductor element 20A among the plurality of semiconductor elements 20 is referred to as a semiconductor element 20B. The conductor block 40 placed on the semiconductor element 20A is referred to as a conductor block 40A, and the conductor block 40 placed on the semiconductor element 20A is referred to as a conductor block 40B.

The temperature rise around the semiconductor element 20A tends to be larger during operation than around the semiconductor element 20B. However, since the hole 41 of the conductor block 40A has the enlarged diameter part 45, but the hole 41 of the conductor block 40B does not have the enlarged diameter part 45, there is a gap between the periphery of the semiconductor element 20A and the periphery of the semiconductor element 20B. It is possible to reduce the imbalance in temperature rise. As a result, it is possible to reduce variations in the degree of crack growth from place to place due to thermal stress.

Embodiment 3.
A power module according to Embodiment 3 will be explained. The power module according to the third embodiment is referred to as a power module 100C. Here, the points that are different from the power module 100A will be mainly explained, and duplicate explanations will not be repeated.

(Configuration of power module 100C)
The configuration of the power module 100C will be explained below.

FIG. 6 is a partially enlarged sectional view of the power module 100C. As shown in FIG. 6, the power module 100C includes a circuit board 10, a plurality of semiconductor elements 20, a conductor 30, a wire 31, a conductor block 40, a base plate 50, a case 51, and a sealing material. 52. In this regard, the configuration of the power module 100C is common to the configuration of the power module 100A. Note that in FIG. 6, illustration of the base plate 50 and the case 51 is omitted.

In the power module 100C, the conductor block 40 is arranged over the plurality of semiconductor elements 20. To put this from another perspective, the conductor blocks 40 on each of the plurality of semiconductor elements 20 are integrated. Accordingly, the holes 41 of the plurality of integrated conductor blocks 40 are connected to each other. In this regard, the configuration of power module 100C is different from the configuration of power module 100A.

(Effects of power module 100C)
The effects of the power module 100C will be explained below.

In the power module 100C, since the holes 41 of the plurality of integrated conductor blocks 40 are connected to each other, the total volume of the holes 41, that is, the total volume of the liquid 44 sealed therein is increased. Therefore, according to the power module 100C, it is possible to further reduce thermal stress around the semiconductor element 20.

(Modified example)
A power module 100C according to a modified example will be described below.

FIG. 7 is a partially enlarged sectional view of a power module 100C according to a modification. As shown in FIG. 7, in the power module 100C, only some of the plurality of conductor blocks 40 may be integrated. In this case as well, since the total volume of the liquid 44 sealed is increased, it is possible to further reduce the thermal stress around the semiconductor element 20.

Embodiment 4.
A power module according to Embodiment 4 will be explained. The power module according to the fourth embodiment is referred to as a power module 100D. Here, differences from the power module 100A will be mainly explained, and overlapping explanations will not be repeated.

(Configuration of power module 100D)
The configuration of the power module 100D will be explained below.

FIG. 8 is a partially enlarged sectional view of the power module 100D. As shown in FIG. 8, the power module 100D includes a circuit board 10, a plurality of semiconductor elements 20, a conductor 30, a wire 31, a conductor block 40, a base plate 50, a case 51, and a sealing material. 52. In this regard, the configuration of power module 100D is common to the configuration of power module 100A. Note that in FIG. 8, illustration of the base plate 50 and the case 51 is omitted.

In the power module 100D, the hole 41 reaches the lower end 40b. That is, in the power module 100D, the hole 41 penetrates the conductor block 40. As a result, in the power module 100D, the liquid 44 sealed in the hole 41 is in contact with the semiconductor element 20. In this regard, the configuration of power module 100D is different from the configuration of power module 100A.

(Effects of power module 100D)
The effects of the power module 100D will be explained below.

In the power module 100D, since the liquid 44 sealed in the hole 41 is in contact with the semiconductor element 20, heat generated in the semiconductor element 20 is easily transferred to the liquid 44. Therefore, in the power module 100D, the temperature fluctuation between the operation time and the cooling time can be further reduced. As a result, according to the power module 100D, it is possible to further reduce thermal stress around the semiconductor element 20.

(Modified example)
A power module 100D according to a modified example will be described below.

The temperature rise around the semiconductor element 20A tends to be larger during operation than around the semiconductor element 20B. FIG. 9 is a partially enlarged sectional view of a power module 100D according to a modification. As shown in FIG. 9, in the conductor block 40A, the holes 41 reach the lower end 40b (liquid 44 is in contact with the semiconductor element 20), while in the conductor block 40B, the holes 41 do not reach the lower end 40b. (Liquid 44 is not in contact with semiconductor element 20). As a result, it is possible to reduce the imbalance in temperature rise between the surroundings of the semiconductor element 20A and the surroundings of the semiconductor element 20B. As a result, it is possible to reduce variations in the degree of crack growth from place to place due to thermal stress.

Embodiment 5.
In this embodiment, the power modules according to the first to fourth embodiments described above are applied to a power conversion device. Although the present disclosure is not limited to a specific power conversion device, a case will be described below as Embodiment 5 in which the present disclosure is applied to a three-phase inverter. The power conversion system according to the fifth embodiment is referred to as a power conversion system 200.

FIG. 10 is a block diagram showing the configuration of the power conversion system 200. As shown in FIG. 10, the power conversion system includes a power source 300, a power conversion device 400, and a load 500. Power supply 300 is a DC power supply and supplies DC power to power conversion device 400. The power source 300 can be composed of various things, for example, it can be composed of a DC system, a solar battery, a storage battery, or it can be composed of a rectifier circuit or an AC/DC converter connected to an AC system. Good too. Moreover, the power supply 300 may be configured with a DC/DC converter that converts DC power output from a DC system into predetermined power.

The power conversion device 400 is a three-phase inverter connected between the power source 300 and the load 500, converts the DC power supplied from the power source 300 into AC power, and supplies the AC power to the load 500. As shown in FIG. 10, the power conversion device 400 includes a main conversion circuit 401 that converts DC power into AC power and outputs it, and a control circuit that outputs a control signal for controlling the main conversion circuit 401 to the main conversion circuit 401. 403.

The load 500 is a three-phase electric motor driven by AC power supplied from the power converter 400. Note that the load 500 is not limited to a specific application, but is a motor installed in various electrical devices, and is used, for example, as a motor for a hybrid vehicle, an electric vehicle, a railway vehicle, an elevator, or an air conditioner.

Hereinafter, details of the power conversion device 400 will be explained. The main conversion circuit 401 includes a switching element and a freewheeling diode (not shown), and when the switching element switches, it converts the DC power supplied from the power supply 300 into AC power, and supplies the AC power to the load 500. Although there are various specific circuit configurations of the main conversion circuit 401, the main conversion circuit 401 according to the present embodiment is a two-level three-phase full bridge circuit, and includes six switching elements and each switching element. It can be composed of six freewheeling diodes connected in antiparallel to each other. At least one of each switching element and each freewheeling diode of the main conversion circuit 401 is a switching element or a freewheeling diode included in the semiconductor module 402 corresponding to the power module according to any of the first to fourth embodiments described above. be. The six switching elements are connected in series every two switching elements to constitute upper and lower arms, and each upper and lower arm constitutes each phase (U phase, V phase, W phase) of the full bridge circuit. The output terminals of the upper and lower arms, that is, the three output terminals of the main conversion circuit 401, are connected to the load 500.

The main conversion circuit 401 includes a drive circuit (not shown) that drives each switching element, but the drive circuit may be built into the semiconductor module 402 or may include a drive circuit separately from the semiconductor module 402. It may be. The drive circuit generates a drive signal for driving the switching element of the main conversion circuit 401 and supplies it to the control electrode of the switching element of the main conversion circuit 401. Specifically, according to a control signal from a control circuit 403, which will be described later, a drive signal that turns the switching element on and a drive signal that turns the switching element off are output to the control electrode of each switching element. When keeping the switching element in the on state, the drive signal is a voltage signal (on signal) that is greater than or equal to the threshold voltage of the switching element, and when the switching element is kept in the off state, the drive signal is a voltage signal that is less than or equal to the threshold voltage of the switching element. signal (off signal).

The control circuit 403 controls the switching elements of the main conversion circuit 401 so that the desired power is supplied to the load 500. Specifically, based on the power to be supplied to the load 500, the time during which each switching element of the main conversion circuit 401 should be in the on state (on time) is calculated. For example, the main conversion circuit 401 can be controlled by PWM control that modulates the on-time of the switching element according to the voltage to be output. Then, a control command (control signal) is sent to the drive circuit included in the main conversion circuit 401 so that an on signal is output to the switching element that should be in the on state at each time, and an off signal is output to the switching element that should be in the off state. Output. The drive circuit outputs an on signal or an off signal as a drive signal to the control electrode of each switching element according to this control signal.

In the power conversion device 400, since the power modules according to the first to fourth embodiments described above are applied as the semiconductor module 402 constituting the main conversion circuit 401, the generation of thermal stress around the semiconductor element 20 is suppressed. At the same time, it is possible to reduce the current density in the current path from the semiconductor element 20.

In the present embodiment, an example in which the present disclosure is applied to a two-level three-phase inverter has been described, but the present disclosure is not limited to this and can be applied to various power conversion devices. In this embodiment, a two-level power converter is used, but a three-level or multi-level power converter may be used, and when supplying power to a single-phase load, the present disclosure may be applied to a single-phase inverter. May be applied. Further, when power is supplied to a DC load or the like, the present disclosure can also be applied to a DC/DC converter or an AC/DC converter.

Furthermore, the power conversion device to which the present disclosure is applied is not limited to cases where the above-mentioned load is an electric motor. It can also be used as a power conditioner for solar power generation systems, power storage systems, etc.

The embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The basic scope of the present disclosure is indicated by the claims rather than the above-described embodiments, and it is intended that all changes within the meaning and range equivalent to the claims are included.

10 circuit board, 11 insulating layer, 11a top surface, 11b bottom surface, 12 conductor pattern, 13 conductor pattern, 20 semiconductor element, 20A, 20B semiconductor element, 30 conductor, 30a one end, 30b other end, 31 wire, 40, 40A, 40B conductor block, 40a upper end, 40b lower end, 41 hole, 42 screw hole, 43 screw, 44 liquid, 45 expanded diameter section, 50 base plate, 51 case, 52 sealing material, 60, 61, 62, 63 joint material, 100A, 100B, 100C, 100D power module, 200 power conversion system, 300 power supply, 400 power conversion device, 401 main conversion circuit, 402 semiconductor module, 403 control circuit, 500 load, S1 first bonding process, S2 second Bonding process, S3 third bonding process, S4 fourth bonding process, S5 conductor connection process, S6 sealing process.

Claims

a circuit board;
a first semiconductor element;
conductor block,
and a conductor,
the first semiconductor element is arranged on the circuit board,
The conductor block has an upper end and a lower end,
The conductor block is arranged on the first semiconductor element such that the lower end is electrically connected to the first semiconductor element,
A liquid is sealed inside the conductor block,
In the power module, the conductor electrically connects the circuit board and the upper end.
further comprising a screw;
A hole is formed in the upper end and extends toward the lower end,
The upper end side of the hole is a screw hole,
The liquid is sealed in the hole,
The power module according to claim 1, wherein the conductor is fastened to the upper end by screwing the screw into the screw hole.
The power module according to claim 2, wherein the hole has an enlarged diameter portion on the lower end side, the inner diameter of which is larger than that of the screw hole.
The hole extends to reach the lower end,
The power module according to claim 2 or 3, wherein the liquid is in contact with the first semiconductor element.
further comprising a second semiconductor element,
the second semiconductor element is arranged on the circuit board,
The conductor block is disposed over the first semiconductor element and the second semiconductor element such that the lower end thereof is electrically connected to the first semiconductor element and the second semiconductor element. , the power module according to any one of claims 1 to 4.
A main conversion circuit that includes the power module according to any one of claims 1 to 5 and converts and outputs input power,
A power conversion device comprising: a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit.