JP7549520B2 - Power module and power conversion device - Google Patents

Description

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

Power conversion devices that use switching power semiconductor elements have high conversion efficiency and are therefore widely used in consumer, automotive, railway and substation equipment. These power semiconductor elements generate heat when electricity is passed through them, so they require high heat dissipation properties. For example, for automotive applications, highly efficient devices that use water cooling are used to reduce size and weight.

A conductor plate is bonded to the power semiconductor element, and then the conductor plate and sheet member are sealed with a sealing material such as insulating resin by transfer molding. The conductor plate and sheet member are then bonded together using the pressure applied when the sealing material is injected.

Patent Document 1 discloses a technique in which an insulating sheet is placed in the cavity of a molding die, an electronic component is placed on top of the insulating sheet, and while removing air from an air vent in the molding die, molding resin is injected into the cavity to resin-seal the insulating sheet and electronic component.

JP 2008-16506 A

In the technology of Patent Document 1, if the conductive plate is not flat but has warping or tilt, the adhesion between the conductive plate and the sheet member is lost even when pressure is applied from the transfer mold, and heat dissipation is reduced.

The power module according to the present invention is a power module comprising: a power semiconductor element joined to one side of a conductor plate; a sheet member including an insulating layer joined to the other side of the conductor plate; and a sealing member that seals the conductor plate and the sheet member by transfer molding, wherein a low-rigidity portion is formed in the second region, extending continuously from a predetermined position within the second region to the outer edge of the conductor plate, the thickness of the conductor plate being thinner than other portions .

According to the present invention, even if the conductive plate is not flat, the conductive plate and the sheet member can be tightly attached to each other, providing a device with excellent heat dissipation properties.

FIG. XX line cross-sectional view of the electric circuit body. 4 is a cross-sectional view of the electric circuit body taken along line YY. FIG. 2 is a cross-sectional perspective view of a power module. 5A to 5C are cross-sectional views illustrating a method for manufacturing an electric circuit body. 5(d) to 5(f) are cross-sectional views illustrating a method for manufacturing an electric circuit body. 5(g) to 5(i) are cross-sectional views illustrating a method for manufacturing an electric circuit body. 1A and 1B are diagrams showing details of a transfer mold. 13A to 13C are graphs showing models A and B and the analysis results of each model. 4 is a cross-sectional view of the electric circuit taken along line YY, illustrating heat dissipation. FIG. 4A to 4C are plan views of a conductor plate. 13 is a cross-sectional view of an electric circuit body according to a modified example taken along line YY. FIG. FIG. 2 is a semi-transparent plan view of the power module. FIG. 2 is a circuit diagram of a power module. FIG. 1 is a circuit diagram of a power conversion device using a power module. FIG. 2 is an external perspective view of the power conversion device. 1 is a cross-sectional perspective view of the power conversion device taken along line XV-XV.

The following describes an embodiment of the present invention with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some parts have been omitted or simplified as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

When there are multiple components with the same or similar functions, they may be described using the same reference numerals with different subscripts. However, when there is no need to distinguish between these multiple components, the subscripts may be omitted.

Fig. 1 is a plan view of the electric circuit body 400, and Fig. 2 is a cross-sectional view of the electric circuit body 400 taken along line XX shown in Fig. 1. Fig. 3 is a cross-sectional view of the electric circuit body 400 taken along line YY shown in Fig. 1.
As shown in FIG. 1, the electric circuit body 400 is composed of three power modules 300 and a cooling member 340. The power module 300 has a function of converting DC current and AC current using power semiconductor elements, and generates heat when electricity is applied. For this reason, a cooling member 340 is configured to be cooled by circulating a coolant through it. The coolant used may be water or an antifreeze solution in which ethylene glycol is mixed with water. The cooling member 340 may have a pin-shaped fin standing on a base plate of the cooling member 340. The cooling member 340 is preferably made of aluminum, which has high thermal conductivity and is lightweight. The cooling member 340 is manufactured by extrusion molding, forging, brazing, or the like.

The power module 300 has a positive terminal 315B and a negative terminal 319B on one side that are connected to the capacitor module 500 of the DC circuit (see FIG. 14 described later). The other side of the positive terminal 315B and the negative terminal 319B has power terminals through which a large current flows, such as the AC terminal 320B that is connected to the motor generators 192, 194 of the AC circuit (see FIG. 15 described later). The other side also has signal terminals used to control the power module 300, such as the lower arm gate signal terminal 325L, the mirror emitter signal terminal 325M, the Kelvin emitter signal terminal 325K, and the upper arm gate signal terminal 325U.

2, the active element 155 and the diode 156 are provided as the first power semiconductor element forming the upper arm circuit. Examples of the semiconductor material constituting the active element 155 include Si, SiC, GaN, GaO, and C. When the body diode of the active element 155 is used, the diode 156 may be omitted. The collector side of the active element 155 and the cathode side of the diode 156 are joined to the second conductor plate 431. The emitter side of the active element 155 and the anode side of the diode 156 are joined to the first conductor plate 430. Solder or sintered metal may be used for these connections. The first conductor plate 430 and the second conductor plate 431 are not particularly limited as long as they have high electrical conductivity and thermal conductivity, but copper-based or aluminum-based materials are preferable. These may be used alone, or may be plated with Ni, Ag, or the like to improve the bonding with the solder or sintered metal.

The cooling member 340 is attached to the first conductive plate 430 via the first sheet member 440 and the thermally conductive member 453. The first sheet member 440 is formed by laminating a first resin insulating layer 442 and a metal foil 444, and the metal foil 444 side is attached to the thermally conductive member 453.

The cooling member 340 is adhered to the second conductive plate 431 via the second sheet member 441 and the thermally conductive member 453. The second sheet member 441 is formed by laminating a second resin insulating layer 443 and a metal foil 444, and the metal foil 444 side is adhered to the thermally conductive member 453.

As shown in FIG. 3, the second power semiconductor elements forming the lower arm circuit include an active element 157 and a diode 158 (see FIG. 13 and FIG. 14 described later). In FIG. 3, the diode 158 is disposed behind the active element 157 in the X-axis direction. The collector side of the active element 157 and the cathode side of the diode 158 are joined to the fourth conductor plate 433. The third conductor plate 432 is joined to the emitter side of the active element 157 and the anode side of the diode 158.

3, the first conductor plate 430, the second conductor plate 431, the third conductor plate 432, and the fourth conductor plate 433, in addition to carrying current, also serve as heat transfer members that transfer heat generated by the first power semiconductor elements 155, 156 and the second power semiconductor elements 157, 158 to the cooling member 340. Since the electric potentials of the conductor plates 430, 431, 432, and 433 are different from those of the cooling member 340, as shown in FIG. 2, a first sheet member 440 having a first resin insulating layer 442 is interposed between the conductor plates 430, 431, 432, and 433 and the cooling member 340, and a second sheet member 441 having a second resin insulating layer 443 is interposed between the conductor plates 430, 431, 432, and 433 and the cooling member 340. A heat conductive member 453 is provided between the sheet members 440 and 441 and the cooling member 340 to reduce contact thermal resistance. In addition, the first power semiconductor elements 155, 156 and the second power semiconductor elements 157, 158 may be simply referred to as power semiconductor element 159.

The thermal conductive member 453 is not particularly limited as long as it is a material with high thermal conductivity, but it is preferable to use a highly thermal conductive material such as a metal, ceramic, or carbon-based material in combination with a resin material. This is because the resin material fills the gap between the thermal conductive member 453 and the cooling member 340, and between the thermal conductive member 453 and each sheet member 440, 441, reducing contact thermal resistance.

The first power semiconductor elements 155, 156, the second power semiconductor elements 157, 158, the conductor plates 430, 431, 432, 433, and the sheet members 440, 441 are sealed with the sealing member 360 by transfer molding. The first resin insulating layer 442 and the second resin insulating layer 443 of each sheet member 440, 441 are not particularly limited as long as they have adhesive properties with the conductor plates 430, 431, 432, 433, but an epoxy resin-based resin insulating layer in which powdered inorganic filler is dispersed is preferable. This is because it has a good balance between adhesiveness and heat dissipation. Each sheet member 440, 441 may be a resin insulating layer alone, but it is preferable to provide a metal foil 444 on the side in contact with the heat conductive member 453. In the transfer molding process, when each sheet member 440, 441 is mounted on a mold, a release sheet or metal foil 444 is provided on the contact surface between each sheet member 440, 441 and the mold to prevent adhesion to the mold. Release sheets have poor thermal conductivity and require a process to peel them off after transfer molding, but in the case of metal foil 444, by selecting a copper-based or aluminum-based metal with high thermal conductivity, it can be used without peeling after transfer molding. By transfer molding including each sheet member 440, 441, the ends of each sheet member 440, 441 are covered with sealing member 360, which has the effect of improving product reliability.

The conductor plates 430, 431, 432, 433 are preferably made of a material with high electrical conductivity and high thermal conductivity, and may be made of metal-based materials such as copper or aluminum, or composite materials of metal-based materials and high thermal conductivity materials such as diamond, carbon, or ceramic. The conductor plates 430, 431, 432, 433 are divided into a first region where the power semiconductor element 159 is bonded to one side, and a second region where the sealing member is in contact with the one side, as will be described in detail later, and a low-rigidity portion 460 (see FIG. 2) with lower rigidity than other portions is formed in the second region. The low-rigidity portion 460 is formed by forming a recess by pressing, or by cutting using mechanical processing or laser processing to reduce the plate thickness.

Figure 4 is a cross-sectional perspective view of the power module 300 taken along line X-X in Figure 1, showing the state in which the cooling member 340 has been removed from the electric circuit body 400. As shown in Figure 4, the end of the first sheet member 440 is covered by a sealing member 360. The first sheet member 440 that overlaps with the surface of the first conductive plate 430 is the heat dissipation surface. The cooling member 340 is tightly attached to the heat dissipation surface of the first sheet member 440 to ensure close contact with the cooling member 340 and to prevent loss of heat dissipation.

Figures 5(a)-(c), 6(d)-(f), and 7(g)-(i) are cross-sectional views showing a manufacturing method for the electric circuit body 400. The left side of each figure shows a cross-sectional view of one power module taken along line X-X in Figure 1, and the right side shows a cross-sectional view of one power module taken along line Y-Y in Figure 1.

Figure 5 (a) is a diagram showing the solder connection process and the wire bonding process. The collector side of the active element 155, which is the first power semiconductor element, and the cathode side of the diode 156 are connected to the second conductor plate 431, and the gate electrode of the active element 155 is connected by wire bonding. The emitter side of the active element 155 and the anode side of the diode 156 are connected to the first conductor plate 430. Similarly, the collector side of the active element 157, which is the second power semiconductor element, and the cathode side of the diode 158 are connected to the fourth conductor plate 433, and the gate electrode of the active element 157 is connected by wire bonding. The emitter side of the active element 157 and the anode side of the diode 158 are connected to the third conductor plate 432. In this way, the circuit body 310 is formed.

The conductive plates 430, 431, 432, and 433 each have a low-rigidity portion 460. The conductive plates 430, 431, 432, and 433 may be warped, and may become inclined after solder connection due to variations in solder thickness, etc.

Figure 5(b) shows the mold installation process. The transfer mold device 601 vacuum-adsorbs the spring 602 and the sheet members 440, 441 to the mold. A vacuum degassing mechanism for vacuum-adsorbing the sheet members 440, 441 to the mold is not shown. The sheet members 440, 441 are aligned using a jig and held by vacuum adsorption in a mold that has been heated to a constant temperature of 175°C. The circuit body 310, which has been preheated to 175°C, is then placed in the mold separated from the sheet members 440, 441.

Figure 5 (c) shows the pressurizing process. With the sheet members 440, 441 and the circuit body 310 separated, the upper and lower dies are brought close together, and only the packings installed around the upper and lower dies (not shown) come into contact. Next, the cavity of the die is evacuated. When the evacuation is completed to a predetermined air pressure or less, the upper and lower dies are pressurized and completely tightened so as to further crush the packing. At this time, the sheet members 440, 441 and the circuit body 310 come into contact.

If the first region of the conductor plates 430, 431, 432, and 433 where the power semiconductor element 159 is joined is warped or tilted, the pressure of the spring 602 will bring the sheet members 440 and 441 into close contact with the conductor plates 430, 431, 432, and 433. On the other hand, if the second region of the conductor plates 430, 431, 432, and 433 that contacts the sealing member is warped or tilted, the pressure of the spring 602 will not reach the conductor plates 430, 431, 432, and 433, and the sheet members 440 and 441 will be insufficient, and gaps may occur between the conductor plates 430, 431, 432, and 433 and the sheet members 440 and 441. However, in this embodiment, it is possible to increase the adhesion between the conductor plates 430, 431, 432, and 433 and the sheet members 440 and 441 as described below.

6(d) to 6(f) are diagrams showing the injection process of injecting the sealing member 360 by transfer molding. As shown in FIG. 6(d), the sealing member 360 is injected into the mold from an injection port not shown. As shown by the arrows in FIG. 6(e), the molding pressure caused by the injection of the sealing member 360 is applied evenly inside the mold as hydrostatic pressure. At this time, as shown by the arrows in FIG. 6(f), since the low-rigidity portion 460 is formed in the second region of the conductor plates 430, 431, 432, and 433, the second region of the conductor plates 430, 431, 432, and 433 is pressed against the sheet members 440 and 441 by the molding pressure. As a result, even if the conductor plates 430, 431, 432, and 433 are warped or tilted, the sheet members 440 and 441 can be tightly attached to the ends of the conductor plates 430, 431, 432, and 433. If the low rigidity portion 460 is not formed in the second region of the conductor plates 430, 431, 432, 433, if the second region of the conductor plates 430, 431, 432, 433 is warped or tilted, the bending rigidity of the second region remains high, and the bending reaction force of the conductor plates 430, 431, 432, 433 cannot press the conductor plates 430, 431, 432, 433 against the sheet members 440, 441. However, in this embodiment, since the low rigidity portion 460 is provided, the bending reaction force of the conductor plates 430, 431, 432, 433 is reduced, and the adhesion between the conductor plates 430, 431, 432, 433 and the sheet members 440, 441 can be improved.

Figure 7 (g) shows the curing process. The power module 300 sealed with the sealing member 360 is removed from the transfer molding device 601, cooled to room temperature, and cured for at least two hours.

Figure 7 (h) is a diagram showing the installation process of the cooling member 340. The cooling member 340 is pressed against both sides of the power module 300 via the thermal conductive member 453. This causes the cooling member 340 to be in close contact with the first sheet member 440 and the second sheet member 441 via the thermal conductive member 453.

Figure 7(i) shows the electric circuit body 400 manufactured by the above process. In this way, the cooling members 340 are installed on both sides of the power module 300, and the electric circuit body 400 is manufactured.

Figures 8(a) and 8(b) are diagrams showing the details of the transfer mold. With reference to these figures, the adhesion between the conductive plates 430, 431, 432, and 433 and the sheet members 440 and 441 will be explained. In both cases, the cross-sectional view of one power module taken along line Y-Y in Figure 1 will be used as an example.

8(a) shows a state in which the mold is closed and pressure 461 is applied by spring 602. Conductor plates 430, 431, 432, 433 are divided into a first region D1 where power semiconductor element 159 is bonded to one side, and a second region D2 where the sealing member 360 is in contact with the one side. The first region D1 of conductor plates 430, 431, 432, 433 is bonded to the power semiconductor element 159 on the upper surface of the convex portion formed toward the power semiconductor element 159. Pressure by spring 602 is applied to the first region D1. This pressure spreads at an angle of 45° inside conductor plates 430, 431, 432, 433 from the bottom end d of the convex portion of conductor plates 430, 431, 432, 433 toward sheet members 440, 441. Hereinafter, the pressure contour line that spreads from the bottom end of the convex portion of the conductor plates 430, 431, 432, 433 toward the sheet members 440, 441 within the conductor plates 430, 431, 432, 433 is referred to as the pressure contour line p. In this embodiment, the pressure contour line p spreads at an angle of 45° from the bottom end d, but it does not necessarily have to be 45°. The low rigidity portion 460 is formed outside the pressure contour line p. Therefore, even when pressure 461 is applied by the spring 602, excessive pressure on the low rigidity portion 460 can be reduced.

In FIG. 8(a), vertical lines are drawn on the sheet members 440 and 441 to show region 462 where the pressure exerted by the spring 602 on the conductor plates 430, 431, 432, and 433 is high. Vertical lines are not drawn on region 463 where the pressure exerted by the spring 602 on the conductor plates 430, 431, 432, and 433 is low. Since the adhesion between the conductor plates 430, 431, 432, and 433 and the sheet members 440 and 441 requires a surface pressure necessary to exert an adhesive force, even if the adhesion is achieved in region 462, peeling may occur in region 463.

Figure 8 (b) shows the state in which the sealing member 360 is injected from the injection port 603. Since the sealing member 360 becomes liquid once, the molding pressure is applied to the entire sealing member 360 as hydrostatic pressure. This pressure is also applied to the second region D2 of the conductor plates 430, 431, 432, and 433. Since the low-rigidity portion 460 is provided in the second region D2, the bending reaction force of the conductor plates 430, 431, 432, and 433 is reduced. Therefore, the conductor plates 430, 431, 432, and 433 are pressed against the sheet members 440 and 441 by the pressure 464. As a result, the surface pressure can be improved even in the region 463 where the pressure due to the pressure of the spring 602 is low, and the adhesion between the conductor plates 430, 431, 432, and 433 and the sheet members 440 and 441 can be improved.

9A shows model A of conductive plates 430, 431, 432, and 433, FIG. 9B shows model B of conductive plates 430, 431, 432, and 433, and FIG. 9C is a graph showing the analysis results of each model.
Model A has recesses as low-rigidity parts 460 in conductive plates 430, 431, 432, 433, and model B has a reduced plate thickness as low-rigidity part 460. In both cases, conductive plates 430, 431, 432, 433 have a plate thickness T0, and low-rigidity part 460 has a plate thickness T1 (T0>T1). In addition, length L of conductive plates 430, 431, 432, 433 in the reduced-rigidity area is four times or more longer than length O of conductive plates 430, 431, 432, 433 in the non-reduced-rigidity area. The left ends of conductive plates 430, 431, 432, 433 are fixed, and pressure P is applied from above.

9(c), the horizontal axis is the thickness ratio, which is the value obtained by dividing the plate thickness T1 of the portion with reduced rigidity by the plate thickness T0 of the portion without reduced rigidity, and the vertical axis is the deformation rate, which is the value obtained by dividing the deformation amount of the right end portion when the low rigidity portion 460 is provided by the deformation amount of the right end portion when the low rigidity portion 460 is not provided. As shown in FIG. 9(c), in both Model A and Model B, the deformation rate increases exponentially by reducing the rigidity compared to the thickness ratio of 1 without reduced rigidity. This indicates that the bending rigidity of the conductor plates 430, 431, 432, and 433 is significantly reduced by reducing the rigidity. By reducing the bending rigidity of the conductor plates 430, 431, 432, and 433 in this way, the reaction force of the conductor plates 430, 431, 432, and 433 is reduced. For this reason, as described above, the molding pressure of the sealing member 360 presses the conductive plates 430, 431, 432, and 433 against the sheet members 440 and 441, improving the surface pressure when the conductive plates 430, 431, 432, and 433 are in close contact with the sheet members 440 and 441. By improving the surface pressure when in close contact in this way, the conductor plates 430, 431, 432, and 433 can be bonded to the sheet members 440 and 441, improving the insulation.

FIG. 10 is a cross-sectional view of one power module taken along line YY shown in FIG.
The low rigidity portion 460 and the heat dissipation path of the conductor plates 430, 431, 432, and 433 will be described with reference to FIG. 8A. As described with reference to FIG. 8A, the conductor plates 430, 431, 432, and 433 are divided into a first region D1 where the power semiconductor element 159 is bonded to one surface, and a second region D2 where the one surface is in contact with the sealing member. The heat of the power semiconductor element 159 spreads at an angle of 45° inside the conductor plates 430, 431, 432, and 433 from the bottom end d of the convex portion of the conductor plates 430, 431, 432, and 433 toward the sheet members 440 and 441. The heat of the power semiconductor element 159 is then transferred to the cooling member 340 via the sheet members 440 and 441 and the heat conductive member 453. In this way, the angle of about 45 degrees with respect to the plate thickness of the conductor plates 430, 431, 432, and 433, i.e., the pressurized outer boundary line p, becomes the main heat conduction path, so if there is a low-rigidity portion 460 such as a recess inside the pressurized outer boundary line p, the heat dissipation performance will be significantly reduced. For this reason, when the low-rigidity portion 460 is provided, it is preferable to provide it outside the pressurized outer boundary line p. Note that the low-rigidity portion 460 may be provided only on one of the first conductor plate 430 and the second conductor plate 431, and on one of the third conductor plate 432 and the fourth conductor plate 433, respectively. In that case, it is preferable to provide it at least on the second conductor plate (upper arm circuit collector side) 431 and the fourth conductor plate (lower arm circuit collector side) 433, i.e., the conductor plates 431 and 433 connected to the collector electrode of the power semiconductor element 159. The reason for this is that a large current flows through the collector electrode of the power semiconductor element 159, causing it to become hot, and therefore it is necessary to improve the adhesion between the conductive plates 431, 433 connected to the collector electrode and the sheet members 440, 441 to improve heat dissipation.

Figures 11(a), 11(b), and 11(c) are plan views of the second conductor plate (upper arm circuit collector side) 431. Figure 11(a) shows the plan view of this embodiment, Figure 11(b) shows modified example 1, and Figure 11(c) shows modified example 2. In each figure, the plan view shows the surface where the power semiconductor elements 155 and 156 are joined.

In this embodiment shown in FIG. 11(a), a low-rigidity portion 460 is provided in the conductor plate 431 at a position surrounding the power semiconductor elements 155, 156. This increases the adhesion between the conductor plate 431 and the sheet members 440, 441 around the power semiconductor elements 155, 156. In addition, the conductor plate 431 is wide, which has the effect of providing excellent heat dissipation.

In the first modification shown in FIG. 11(b), the length of the conductor plate 431 in the X direction is reduced so that the conductor plate 431 fits inside the pressurized outer contour line p. This means that the low-rigidity portion 460 is provided only in the Y-axis direction with respect to the power semiconductor elements 155 and 156. By omitting the low-rigidity portion 460, the processing cost can be reduced.

In the second modification shown in FIG. 11(c), the length of the conductor plate 431 in the X direction is reduced so that the conductor plate 431 fits inside the pressurized outer contour line p, and low rigidity sections 460 are provided intermittently. Specifically, low rigidity sections 460 such as recesses are arranged at predetermined intervals along the X direction of the conductor plate 431. In addition to being able to reduce processing costs by omitting the low rigidity sections 460, the low rigidity sections 460 are provided intermittently, so that heat spreads easily in the conductor plate 431, resulting in excellent heat dissipation.

FIG. 12 is a cross-sectional view of one power module taken along line YY in FIG.
As shown in FIG. 12, model B shown in FIG. 9B is applied as a low-rigidity portion 460 of a first conductive plate (upper arm circuit emitter side) 430.
In model B, the cross-sectional area of the conductor plate 430 is smaller than that of model A, but there is an advantage that the conductor plate 430 can be easily manufactured by press working. In terms of heat dissipation, model A, in which the cross-sectional area of the conductor plate 430 is larger, is superior.

According to the present embodiment described above, even if the conductive plates 430, 431, 432, and 433 are warped or tilted after solder connection, the warping and tilting of the conductive plates 430, 431, 432, and 433 can be corrected in the transfer molding process, and the sheet members 440 and 441 and the conductive plates 430, 431, 432, and 433 can be bonded to the ends, resulting in excellent insulation and heat dissipation properties.

Figure 13 is a semi-transparent plan view of the power module 300 in this embodiment. Figure 14 is a circuit diagram of the power module 300 in this embodiment.

As shown in Figures 13 and 14, the positive terminal 315B is output from the collector side of the upper arm circuit and is connected to the positive side of a battery or a capacitor. The upper arm gate signal terminal 325U is output from the gate and emitter sense of the active element 155 of the upper arm circuit. The negative terminal 319B is output from the emitter side of the lower arm circuit and is connected to the negative side of a battery or a capacitor, or GND. The lower arm gate signal terminal 325L is output from the gate and emitter sense of the active element 157 of the lower arm circuit. The AC side terminal 320B is output from the collector side of the lower arm circuit and is connected to the motor. When the neutral point is grounded, the lower arm circuit is connected to the negative side of the capacitor instead of GND.

A first conductor plate (upper arm circuit emitter side) 430 and a second conductor plate (upper arm circuit collector side) 431 are arranged above and below the active element 155 and diode 156 of the first power semiconductor element (upper arm circuit). A third conductor plate (lower arm circuit emitter side) 432 and a fourth conductor plate (lower arm circuit collector side) 433 are arranged above and below the active element 157 and diode 158 of the second power semiconductor element (lower arm circuit). Note that the low rigidity portions 460 formed on the conductor plates 430, 431, 432, and 433 are omitted from the illustration.

The power module 300 of this embodiment has a 2-in-1 structure in which two arm circuits, an upper arm circuit and a lower arm circuit, are integrated into one module. Alternatively, a structure in which multiple upper arm circuits and lower arm circuits are integrated into one module may be used. In this case, the number of output terminals from the power module 300 can be reduced, resulting in a smaller size.

FIG. 15 is a circuit diagram of a power conversion device 200 using the electric circuit body 400.
The power conversion device 200 includes inverter circuits 140 and 142, an inverter circuit 43 for auxiliary equipment, and a capacitor module 500. The inverter circuits 140 and 142 are configured with an electric circuit body 400 (not shown) including a plurality of power modules 300, which are connected to form a three-phase bridge circuit. When the current capacity is large, the current capacity can be increased by connecting further power modules 300 in parallel and making these parallel connections corresponding to each phase of the three-phase inverter circuit. In addition, the current capacity can be increased by connecting active elements 155 and 157 and diodes 156 and 158, which are power semiconductor elements built into the power module 300, in parallel.

The inverter circuit 140 and the inverter circuit 142 have the same basic circuit configuration, and the control method and operation are also basically the same. Since the outline of the circuit operation of the inverter circuit 140 and the like is well known, a detailed explanation will be omitted here.

As described above, the upper arm circuit includes an upper arm active element 155 and an upper arm diode 156 as power semiconductor elements for switching, and the lower arm circuit includes a lower arm active element 157 and a lower arm diode 158 as power semiconductor elements for switching. The active elements 155 and 157 receive a drive signal output from one or the other of the two driver circuits that make up the driver circuit 174 and perform a switching operation to convert the DC power supplied from the battery 136 into three-phase AC power.

As described above, the upper arm active element 155 and the lower arm active element 157 have a collector electrode, an emitter electrode, and a gate electrode. The upper arm diode 156 and the lower arm diode 158 have two electrodes, a cathode electrode and an anode electrode. As shown in FIG. 13, the cathode electrodes of the diodes 156 and 158 are electrically connected to the collector electrodes of the active elements 155 and 157, and the anode electrodes are electrically connected to the emitter electrodes of the active elements 155 and 157, respectively. This causes the current flow from the emitter electrode of the upper arm active element 155 and the lower arm active element 157 to the collector electrode in the forward direction.

Note that a MOSFET (metal-oxide semiconductor field-effect transistor) may be used as the active element, in which case the upper arm diode 156 and the lower arm diode 158 are not required.

The positive terminal 315B and negative terminal 319B of each upper and lower arm series circuit are connected to DC terminals 362A and 362B for connecting capacitors of the capacitor module 500, respectively. AC power is generated at the connection between the upper arm circuit and the lower arm circuit, and the connection between the upper arm circuit and the lower arm circuit of each upper and lower arm series circuit is connected to the AC side terminal 320B of each power module 300. The AC side terminal 320B of each power module 300 of each phase is connected to the AC output terminal of the power conversion device 200, and the generated AC power is supplied to the stator winding of the motor generator 192 or 194.

The control circuit 172 generates a timing signal for controlling the switching timing of the upper arm active element 155 and the lower arm active element 157 based on input information from the vehicle's control device and sensors (e.g., current sensor 180). The driver circuit 174 generates a drive signal for switching the upper arm active element 155 and the lower arm active element 157 based on the timing signal output from the control circuit 172. Note that 181, 182, and 188 are connectors.

The upper and lower arm series circuits include a temperature sensor (not shown), and temperature information of the upper and lower arm series circuits is input to the control circuit 172. In addition, voltage information of the DC positive pole side of the upper and lower arm series circuits is input to the control circuit 172. The control circuit 172 performs over-temperature detection and over-voltage detection based on this information, and if over-temperature or over-voltage is detected, it stops the switching operation of all upper arm active elements 155 and lower arm active elements 157, protecting the upper and lower arm series circuits from over-temperature or over-voltage.

16 is an external perspective view of the power conversion device 200 shown in FIG. 15, and FIG. 17 is a cross-sectional perspective view of the power conversion device 200 shown in FIG. 16 taken along line XV-XV.
As shown in FIG. 16, the power conversion device 200 includes a housing 12 formed of a lower case 11 and an upper case 10 and having a substantially rectangular parallelepiped shape. An electric circuit body 400, a capacitor module 500, and the like are housed inside the housing 12. The electric circuit body 400 has a cooling flow path, and a cooling water inlet pipe 13 and a cooling water outlet pipe 14 communicating with the cooling flow path protrude from one side of the housing 12. The lower case 11 has an opening on the upper side (Z direction), and the upper case 10 is attached to the lower case 11 by closing the opening of the lower case 11. The upper case 10 and the lower case 11 are formed of an aluminum alloy or the like, and are fixed in a sealed manner against the outside. The upper case 10 and the lower case 11 may be integrally configured. By forming the housing 12 into a simple rectangular parallelepiped shape, it becomes easy to attach it to a vehicle or the like, and also improves productivity.

A connector 17 is attached to one longitudinal side of the housing 12, and an AC terminal 18 is connected to this connector 17. In addition, a connector 21 is provided on the surface from which the cooling water inlet pipe 13 and the cooling water outlet pipe 14 are led out.

As shown in FIG. 17, the electric circuit body 400 is housed in the housing 12. The control circuit 172 and the driver circuit 174 are arranged above the electric circuit body 400, and the capacitor module 500 is housed on the DC terminal side of the electric circuit body 400. By arranging the capacitor module at the same height as the electric circuit body 400, the power conversion device 200 can be made thinner, improving the degree of freedom of installation in the vehicle. The AC side terminal 320B of the electric circuit body 400 is connected to the bus bar through the current sensor 180. In addition, the positive side terminal 315B and the negative side terminal 319B, which are DC terminals of the electric circuit body 400, are respectively connected to the positive and negative terminals of the capacitor module 500 (DC terminals 362A and 362B in FIG. 13).

According to the embodiment described above, the following advantageous effects can be obtained.
(1) The power module 300 includes a power semiconductor element 159 bonded to one side of the conductor plates 430, 431, 432, 433, sheet members 440, 441 including an insulating layer bonded to the other side of the conductor plates 430, 431, 432, 433, and a sealing member 360 that seals the conductor plates 430, 431, 432, 433 and the sheet members 440, 441 by transfer molding, and the conductor plates 430, 431, 432, 433 are divided into a first region D1 where the power semiconductor element 159 is bonded to one side and a second region D2 that contacts the sealing member 360 on one side, and a low-rigidity portion 460 with low rigidity is formed in the second region D2. As a result, even if the conductor plate is not flat, the conductor plate and the sheet member can be tightly attached to each other, and a device with excellent heat dissipation properties can be provided.

The present invention is not limited to the above-described embodiment, and other forms that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention, so long as they do not impair the characteristics of the present invention. In addition, the above-described embodiment may be combined with multiple modified examples.

10: upper case, 11: lower case, 13: cooling water inlet pipe, 14: cooling water outlet pipe, 17: connector, 18: AC terminal, 21: connector, 43, 140, 142: inverter circuit, 155: first power semiconductor element (upper arm circuit active element), 156: first power semiconductor element (upper arm circuit diode), 157: second power semiconductor element (lower arm circuit active element), 158: second power semiconductor element (lower arm circuit diode), 159 . . Power semiconductor element, 172... Control circuit, 174... Driver circuit, 180... Current sensor, 181, 182, 188... Connector, 192, 194... Motor generator, 200... Power conversion device, 300... Power module, 310... Circuit body, 315B... Positive terminal, 319B... Negative terminal, 320B... AC terminal, 325... Signal terminal, 325K... Kelvin emitter signal terminal, 325L... Lower arm gate signal terminal, 325M... a first resin insulating layer (emitter side), a second resin insulating layer (collector side), a third resin insulating layer (emitter side), a fourth resin insulating layer (collector side), a fourth resin insulating layer (collector side), a second resin insulating layer (emitter side), a third resin insulating layer (collector side), a fourth resin insulating layer (collector side), a fourth resin insulating layer (emitter side), a fifth resin insulating layer (collector side), a sixth resin insulating layer (emitter side), a sixth resin insulating layer (collector side), a sixth resin insulating layer (collector side), a sixth resin insulating layer (collector side), a sixth resin insulating layer (collector side), a sixth resin insulating layer (collector side), a sixth resin insulating layer (collector side), a seventh resin insulating layer (emitter side), a seventh resin insulating layer (collector ... 443: second resin insulating layer (collector side), 444: metal foil, 453: heat conductive member, 460: low rigidity section, 461: pressure from spring, 462: high surface pressure area due to pressure from spring, 463: low surface pressure area due to pressure from spring, 464: pressure from molding pressure, 500: capacitor module, 601: transfer molding device, 602: spring, D1: first area, D2: second area, p: pressure outer contour line.

Claims (6)

A power module comprising: a power semiconductor element bonded to one surface of a conductor plate; a sheet member including an insulating layer bonded to the other surface of the conductor plate; and a sealing member that seals the conductor plate and the sheet member by transfer molding,
the conductor plate is divided into a first region to which the power semiconductor element is bonded on the one surface, and a second region in contact with the sealing member on the one surface,
A power module in which a low-rigidity portion is formed in the second region, extending continuously from a predetermined position within the second region to the outer edge of the conductor plate, the thickness of the conductor plate being thinner than other portions . 2. The power module according to claim 1,
the first region of the conductor plate is joined to the power semiconductor element at an upper surface portion of a protrusion formed toward the power semiconductor element,
The low rigidity portion is a power module formed outside a pressure contour line of pressure spreading from a bottom end of the convex portion of the conductor plate toward the sheet member. 3. The power module according to claim 2 ,
The pressurized contour line extends at an angle of 45° from the bottom end of the convex portion toward the sheet member. 2. The power module according to claim 1,
The conductor plate having the low rigidity portion formed therein is connected to a collector electrode of the power semiconductor element. The power module according to any one of claims 1 to 4 ,
the conductor plates are disposed on both sides of the power semiconductor element, and one side of each of the conductor plates is joined to the power semiconductor element;
The sheet member is a power module joined to the other surface of each of the conductor plates. A power module according to any one of claims 1 to 4 ;
A power conversion device comprising: a cooling member bonded to the power module via a thermally conductive member; the power conversion device converts DC power into AC power.

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