Electric power conversion device and method for manufacturing the same

Abstract

To provide an electric power conversion device capable of reducing inductance of a current path of a three-phase inverter circuit and equalizing temperatures of a plurality of power semiconductor chips.SOLUTION: The electric power conversion device constitutes a three-phase inverter circuit. A power semiconductor module comprises: power semiconductor chips arranged separately in an upper arm and a lower arm of the three-phase inverter circuit; heat spreaders joined to lower electrodes of the power semiconductor chips and provided for the individual power semiconductor chips; a P lead connected to the heat spreaders joined to the power semiconductor chips arranged at an end of the upper arm and connected to a positive electrode side of a power source; an interphase lead connecting the heat spreaders joined to the plurality of power semiconductor chips arranged in the upper arm; and an N lead joined to upper surface electrodes of the plurality of power semiconductor chips arranged in the lower arm and connected to a negative electrode side of the power source.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present application relates to a power conversion device and a method for manufacturing a power conversion device. [Background technology]

[0002] A power conversion device that drives an in-vehicle motor is composed of a power semiconductor module that serves as a power conversion circuit composed of a combination of switchable power semiconductor chips, a control circuit that controls the power conversion circuit, and a heat sink for heat dissipation. A power conversion device converts DC power supplied from a DC power source such as a battery into AC power and supplies it to a rotating electric machine to drive the rotating electric machine. A control circuit sends a control signal to the power conversion circuit for switching the power semiconductor chip, and controls the power that drives the rotating electric machine by turning the power semiconductor chip on and off. The power semiconductor chip is mounted inside the power semiconductor module while being joined to the leads, and is connected to a heat sink for heat dissipation through an insulating member.

[0003] Power conversion devices installed in automobiles are required to have high output, small size, and light weight due to strict requirements for improved fuel efficiency against the backdrop of environmental regulations for automobiles. Among them, the size of power semiconductor modules determines the size of heat sinks and bus bar wiring, which use a large amount of metal, and therefore greatly affects the size and weight of the entire power conversion device. Therefore, miniaturization of power semiconductor modules is always required.

[0004] On the other hand, when power is applied to a power semiconductor chip to operate, heat is generated at a junction near the surface of the power semiconductor chip, causing the temperature of the power semiconductor chip to rise. The heat generated in the power semiconductor chip is released to a heat sink through the wiring members and insulating layers of the power semiconductor module. If the temperature of the power semiconductor chip rises excessively, it may cause the power semiconductor chip to break down and the junction between the power semiconductor chip and the wiring members that transmit power to the power semiconductor chip to deteriorate. Therefore, the power semiconductor chip must be operated at or below the allowable temperature determined at the design stage.

[0005] In addition, one way to reduce the area of ​​a power semiconductor module while suppressing the temperature is to reduce the amount of heat generated by the power semiconductor chip. Heat generation in a power semiconductor chip can be divided into conduction loss and switching loss. Conduction loss is mainly determined by the performance of the power semiconductor chip and the magnitude of the current passing through it. On the other hand, switching loss is mainly determined by the way the current and voltage change when the power semiconductor chip is turned on and off, and this loss is greatly affected by the switching speed of the power semiconductor chip. In order to increase the switching speed, it is necessary to reduce the surge voltage generated when the power semiconductor chip is turned on and off. In addition, this surge voltage can be reduced as the inductance of the current wiring path formed by the power semiconductor chip is smaller. As a result, in order to suppress the temperature of a power semiconductor module, it is important to reduce the inductance of the power semiconductor chip and the wiring path connected to it.

[0006] For these reasons, in order to obtain a small, lightweight, high-output power conversion device, it is necessary to reduce the inductance of the current path so as to reduce the amount of heat generated in the power semiconductor chips. Also, it is necessary to equalize the temperatures of the multiple power semiconductor chips that make up the power conversion circuit so that the power semiconductor chips that show high temperatures are not concentrated in a certain area. Various studies have been conducted on the structure of mounting a three-phase inverter circuit to reduce the size and weight of a power conversion device. Mounting a three-phase inverter circuit on one power semiconductor module makes it easier to reduce the size compared to a configuration in which the three-phase inverter circuit is mounted on a wiring board (for example, see Patent Document 1).

[0007] The power semiconductor module described in Patent Document 1 has six switchable power semiconductor chips mounted in one power semiconductor module, and the power semiconductor chips are mounted on the upper surfaces of four heat spreaders provided inside the power semiconductor module. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2012-89794 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the power semiconductor module shown in Patent Document 1, the shape of the heat spreader used as a heat dissipation member is determined by the constraints on the electric circuit, and the three power semiconductor chips on the upper arm side of the three-phase inverter circuit are mounted on one connected heat spreader, and the three power semiconductor chips on the lower arm side are mounted on three heat spreaders. Since the heat transfer areas of the heat spreaders are different, this causes the temperature of the power semiconductor chips to vary between the upper arm and the lower arm. In addition, due to constraints such as the arrangement of the leads for external output, the arrangement of the power semiconductor chips inside the power semiconductor module is asymmetrical vertically and horizontally, and the mounting positions are biased. As a result, in order to protect the power semiconductor chip that shows the highest temperature among the temperature variations, the output of the power conversion device is limited, and this causes the power semiconductor chips and the power semiconductor module to become larger in size when trying to accommodate a specified output.

[0010] The present application has been made to solve the above-mentioned problems of the conventional technology, and aims to obtain a power conversion device that is small and lightweight yet achieves high output by reducing the inductance of the current paths of a three-phase inverter circuit in a power semiconductor module, thereby reducing heat generated in the power semiconductor chips, and configuring the power semiconductor module to equalize the temperature of the power semiconductor chips. [Means for solving the problem]

[0011] The power conversion device according to the present application is a power conversion device equipped with a power semiconductor module, a heat sink, and a control board to form a three-phase inverter circuit, and the power semiconductor module includes power semiconductor chips arranged separately in an upper arm and a lower arm of the three-phase inverter circuit, a heat spreader joined to the lower electrodes of the power semiconductor chips and provided individually for each of the power semiconductor chips, a P lead connected to the heat spreader joined to the power semiconductor chip arranged at the end of the upper arm and connected to the positive side of a power source, an interphase lead connecting between the heat spreaders joined to the power semiconductor chips arranged in plurality on the upper arm, and an N lead joined to the upper electrodes of the power semiconductor chips arranged in plurality on the lower arm and connected to the negative side of a power source. Effect of the Invention

[0012] According to the present application, the inductance can be reduced by arranging the leads to reduce the loop of the current path of the three-phase inverter circuit in the power semiconductor module, which makes it possible to reduce heat generation due to switching loss generated in the power semiconductor chips. In addition, by providing a heat spreader for each power semiconductor chip, it is possible to reduce the difference in thermal resistance of the heat dissipation path for each power semiconductor chip, thereby reducing the temperature difference between each power semiconductor chip. These effects make it possible to realize a small, lightweight, yet high-output power conversion device. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing a configuration of a three-phase inverter circuit of a power conversion device according to a first embodiment. [Diagram 2] 1 is a schematic diagram showing a configuration of a power semiconductor module of a power conversion device according to a first embodiment. [Diagram 3] 1 is a schematic diagram showing a current path of a power semiconductor module of a power conversion device according to a first embodiment. FIG. [Figure 4] 3 is a schematic cross-sectional view showing the cross section AA in FIG. 2 of the power semiconductor module of the power converter according to the first embodiment. [Diagram 5] 3 is a schematic cross-sectional view showing the cross section BB in FIG. 2 of the power semiconductor module of the power converter according to the first embodiment. [Figure 6] 3 is a diagram showing a flow of a method for manufacturing the power conversion device according to the first embodiment. FIG. [Figure 7] FIG. 11 is a schematic diagram showing a configuration of a power semiconductor module of a power conversion device according to a second embodiment. [Figure 8] 8 is a schematic cross-sectional view showing a cross section taken along line CC in FIG. 7 of a power semiconductor module of a power converter according to a second embodiment. FIG. [Figure 9] FIG. 11 is a schematic diagram showing a configuration of a power semiconductor module of a power conversion device according to a third embodiment. [Figure 10] 10 is a schematic cross-sectional view showing a cross section taken along line DD in FIG. 9 of a power semiconductor module of a power converter according to a third embodiment. FIG. [Figure 11] 13 is a schematic cross-sectional view of a power semiconductor module of a power converter according to a fourth embodiment, on which a heat sink, a control board, and a case are mounted. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Embodiment 1 The power conversion device of the first embodiment has a transfer mold type power semiconductor module and a heat sink in which the mounting surface and leads of a heat spreader on which a power semiconductor chip is mounted are sealed with molding resin in order to meet the demands for high reliability such as earthquake resistance, durability, and insulation performance. Moreover, the power conversion device is composed of a power conversion circuit composed of a combination of switchable power semiconductor chips, a control circuit for controlling the power conversion circuit, a current sensor for detecting current, and the like. The power conversion device converts DC power supplied from a DC power source such as a battery into desired AC power and supplies it to a rotating electric machine to drive the rotating electric machine. The control circuit sends a control signal for switching the power semiconductor chip to the power conversion circuit, and controls the power to drive the rotating electric machine by turning the power semiconductor chip on and off. When power is applied to the power semiconductor chip and it operates, heat is generated at the junction near the surface of the power semiconductor chip, and the temperature of the power semiconductor chip rises. The heat generated by the power semiconductor chip is released to the heat sink through wiring members such as a heat spreader and leads, and insulating layers, etc.

[0015] If the temperature of the power semiconductor chip rises excessively, it may cause the power semiconductor chip to break down and may cause deterioration of the joint between the power semiconductor chip and the wiring member that transmits power to the power semiconductor chip. Therefore, the power semiconductor chip must be operated at a temperature below the allowable temperature determined at the design stage. For this reason, it is important to improve the heat dissipation from the power semiconductor chip of the power conversion device in terms of miniaturization, weight reduction, high output, and failure prevention. From the viewpoint of heat transfer engineering, the heat dissipation is improved by increasing the heat transfer area, such as the size of the power semiconductor chip and the heat conductive member, but this contradicts the demand for miniaturization, weight reduction, and cost reduction. Therefore, it is necessary to suppress the temperature of the power semiconductor chip while reducing the area of ​​the power semiconductor chip.

[0016] Power semiconductor chips that require high reliability, such as those used in hybrid or electric vehicles, are equipped with a temperature sensor on the surface of the power semiconductor chip to keep the chip temperature below an allowable temperature at all times, or with a current sensor that serves as a basis for estimating the temperature. Power conversion devices use these sensors to limit output as a temperature protection function based on the highest temperature detection value among multiple power semiconductor chips that make up a power conversion circuit for driving a motor.

[0017] In order to reduce the area of ​​the power semiconductor chip while suppressing the temperature, it is possible to reduce the amount of heat generated by the power semiconductor chip. In order to suppress the heat generated by the switching loss of the power semiconductor chip, it is important to reduce the inductance of the power semiconductor module and the wiring path connected thereto. In order to obtain a small, lightweight, high-output power conversion device, it is necessary to equalize the temperature of the multiple power semiconductor chips that make up the power conversion circuit while reducing the inductance of the current path to reduce the loss generated in the power semiconductor chips.

[0018] Fig. 1 is a schematic diagram showing the configuration of a three-phase inverter circuit that is a power conversion circuit of a power conversion device according to embodiment 1. Fig. 2 is a schematic diagram showing the configuration of a power semiconductor module of the power conversion device according to embodiment 1. The power semiconductor module 1 of the power conversion device 100 has a transfer mold type structure in which a switchable power semiconductor chip 2, a heat spreader 3 on which the power semiconductor chip 2 is mounted, and leads 4 that supply power to the power semiconductor chip 2 are sealed with molding resin 5.

[0019] Furthermore, the power semiconductor module 1 constitutes a three-phase inverter circuit 10 that converts a DC power source 7 into three-phase AC power, and drives a motor 8, which serves as a load. The three-phase inverter circuit 10 is constituted by separating the power semiconductor chips 2 into three on an upper arm 11 and three on a lower arm 12, and arranging them for each phase. The power semiconductor chips 2 on the upper arm 11 and the power semiconductor chips 2 on the lower arm 12 are connected for each phase, and AC power is output between them.

[0020] In the power semiconductor module 1 in the power conversion device 100 of the present application, the mounting surface of the power semiconductor chip 2 is sealed with a mold resin 5 in order to meet high reliability requirements such as insulation, earthquake resistance, and long-term reliability. In addition, in order to meet high output performance, the power semiconductor chip 2 is connected via a bonding member onto a heat spreader 3 for diffusing heat generated by the power semiconductor chip 2. A plurality of power semiconductor chips 2 are mounted inside the power semiconductor module 1. In addition, the manufacturing process of the transfer mold type power semiconductor module 1 includes mounting the power semiconductor chip 2 on the heat spreader 3, connecting the wiring path by connecting a lead frame to which all the leads 4 are connected and at the same potential, sealing and integrating with mold resin 5, and then cutting off unnecessary parts of the lead frame to individually separate the leads 4, thereby forming the internal circuit of the power semiconductor module 1.

[0021] The power semiconductor chip 2 has an upper surface electrode and a lower surface electrode on the upper surface and the lower surface, respectively. A MOSFET, an RC-IGBT (reverse conducting IGBT), or an IGBT can be applied to the power semiconductor chip 2 of the first embodiment. The MOSFET and the RC-IGBT are switchable power semiconductor chips, and since the MOSFET has a parasitic diode inside, and the RC-IGBT has a diode region, a freewheel diode (FWD) that is separately connected in parallel to the power semiconductor chip is not required. The power semiconductor chip 2 also has a gate portion and a gate electrode on the chip upper surface, separate from the chip upper surface electrode.

[0022] The material of the power semiconductor chip 2 can be not only Si, but also compound semiconductors such as SiC, SiN, GaN, and GaAs. The top electrodes of the power semiconductor chip 2 are connected by leads 4, and are provided with specifications for soldering, such as a plating layer for joining with a conductive material such as solder. The multiple switchable power semiconductor chips 2 mounted on the power semiconductor module 1 are all mounted with the same type and size specifications. By standardizing the power semiconductor chips 2, the variation in heat generation is suppressed, the temperature between the chips is equalized, and mounting errors during manufacturing are prevented, improving productivity. A temperature sensor is mounted on the top electrode of the power semiconductor chip 2. This temperature sensor is a minute-sized diode formed in a semiconductor process in which the fine structure of the power semiconductor chip 2 is formed. When a constant current is passed through this diode, the voltage generated between the input and output of the diode decreases as the temperature of the diode increases. The temperature of the power semiconductor chip 2 is detected by utilizing this relationship between temperature and voltage.

[0023] The leads 4 are composed of a lead frame made of a copper or aluminum alloy plate formed into a wiring pattern shape. After the lead frame is sealed with molding resin 5, unnecessary portions are cut off to become the leads 4 that form the wiring paths within the power semiconductor module 1. The leads 4 serve as paths for transmitting power and heat, and are made of materials with high electrical and thermal conductivity to suit the required performance.

[0024] As shown in FIG. 2, the leads 4 are connected to the upper electrodes or heat spreader 3 of the power semiconductor chip 2, or one or both ends are exposed to the outside from the molded resin 5, thereby forming a current path of the power semiconductor module 1. The power semiconductor module 1 includes the following types of leads 4: a P lead 41, an N lead 42, an AC lead 43, an interphase lead 411, and an inner lead 44. The P lead 41 is connected to the positive side of the power source, and the N lead is connected to the negative side of the power source via an inverter side bus bar or the like, which is a component of the power conversion device 100. The AC lead 43 is connected to the winding coil of the three-phase AC circuit of the motor 8 via a wiring member. The P lead 41 and the N lead 42 have their ends exposed to the outside from the same surface of the outer periphery of the molded resin 5 of the power semiconductor module 1, at the portions to be connected to the DC power source 7.

[0025] The mold resin 5 is arranged so as to enclose the power semiconductor chip 2, the heat spreader 3, the leads 4, the insulating layer 9, etc. inside. The mold resin 5 is installed by transfer molding after the components are mounted on the lead frame. As described above, after the power semiconductor chip 2, the heat spreader 3, the lead frame, and the insulating layer 9 are integrated with the mold resin 5, unnecessary parts of the lead frame are cut off to form the leads 4, and the extension parts of the leads 4 from the mold resin 5 are bent to form the power semiconductor module 1. The mold resin 5 contains an insulating heat dissipation filler, and has the effect of reducing the temperature by diffusing the heat generated by the power semiconductor chip 2 to the filler of the mold resin 5.

[0026] The insulating layer 9 is mainly composed of an insulating filler and an adhesive. The filler is made of fine ceramic particles. The adhesive is made of a thermosetting resin such as epoxy resin. The thickness of the insulating layer 9 is set to 100 um to several hundred um based on the required insulating performance and heat dissipation performance. The insulating layer 9 is brought into the transfer molding process in a coated state on the copper foil 9a.

[0027] 3 is a schematic diagram showing a current path I of the power semiconductor module 1 according to the first embodiment. The power semiconductor chips 2 of the upper arm 11 and the power semiconductor chips 2 of the lower arm 12 of the three-phase inverter circuit 10 are arranged in a line with a P lead 41 and an N lead 42 exposed from the same surface of the outer periphery of the molded resin 5 as a start point and an end point, respectively. The power semiconductor chips 2 of the upper arm 11 and the lower arm 12 are mounted in positions that are line-symmetrical with respect to the top and bottom and the left and right of the power semiconductor module 1. Furthermore, one N lead 42 is connected to the upper surface electrode of the power semiconductor chip 2 that constitutes the lower arm 12. With this configuration, the loop of the current path I shown by the dashed line in the figure can be made smaller, and the inductance of the wiring can be reduced. As a result, the power semiconductor module 1 can reduce the switching loss generated in the mounted power semiconductor chip 2, and can reduce the temperature rise due to heat generation in the power semiconductor chip 2.

[0028] FIG. 4 is a schematic cross-sectional view showing the AA cross section in FIG. 2 of the power semiconductor module 1 by the power conversion device 100 in the first embodiment. FIG. 5 is a schematic cross-sectional view showing the BB cross section in FIG. 2 of the power semiconductor module 1 according to the first embodiment. The power semiconductor chips 2 constituting the three-phase inverter circuit 10 are mounted on one heat spreader 3. The heat spreader 3 mounting the power semiconductor chips 2 constituting the upper arm is connected to the heat spreader 3 of the upper arm 11 of the other phase by an interphase lead 411. By connecting the heat spreaders 3 of the upper arms 11 to each other by the interphase lead 411, the heat spreaders 3 of the upper arms 11 can be provided for each individual power semiconductor chip 2. As with the lower arm 12, the heat spreaders 3 are formed for each power semiconductor chip 2, while the P lead 41 serving as the connection part of the positive electrode side of the power source of the power semiconductor module 1 can be consolidated in one place. Such an integrated configuration makes it easier to miniaturize the power semiconductor module 1 compared to a configuration in which a P lead 41, which serves as the positive terminal connection part of the power supply, is installed for each heat spreader 3 of the upper arm 11.

[0029] Furthermore, in the power semiconductor module 1 according to this embodiment, the power semiconductor chips 2 mounted on one heat spreader 3 are only the chips for one arm of one phase, so the configurations of the power semiconductor chips 2 and the heat spreader 3 can be made the same for the upper and lower arms. This allows the power semiconductor module 1 to uniformly dissipate heat from the power semiconductor chips 2, reducing temperature variations between the chips. Furthermore, in the power semiconductor module 1, the shape of the heat spreader 3 can be made common, so the number of types of parts can be reduced, and the common structure improves productivity. The heat spreader 3 is made of copper or an alloy mainly made of copper. The power semiconductor chip 2 is mounted on one side of the heat spreader 3 via a bonding member. The heat spreader 3 also functions as a wiring path for the three-phase inverter circuit 10, but since the interphase lead 411 is connected to the heat spreader 3 of the upper arm 11, the combination of the power semiconductor chip 2 and the heat spreader 3 of the power semiconductor module 1 can be configured in the same manner for each power semiconductor chip 2 on both the upper arm 11 and the lower arm 12.

[0030] In the present embodiment, the inside of one power semiconductor module 1 is shown as an example of a three-phase inverter circuit 10, but the power semiconductor chips 2 constituting at least one phase of the three-phase inverter circuit 10 are mounted, and as shown in FIG. 2, the power semiconductor module 1 is characterized in that the power semiconductor chips 2 are arranged in vertically and horizontally symmetrical positions with respect to the center of the layout plane of the power semiconductor module 1. This makes the distances between the power semiconductor chips 2 the same, and the layout is regular, including the connecting members, and the heat dissipation is uniformed, which has the effect of reducing the temperature difference between the power semiconductor chips 2. In other words, when the three-phase inverter circuit 10 is composed of a plurality of power semiconductor modules 1, the power semiconductor module 1 can reduce the inductance of the current path and can equalize the heat dissipation for each of the plurality of power semiconductor chips 2 constituting the circuit.

[0031] The interphase leads 411 or P leads 41 mounted on the heat spreader 3 for the upper arm 11 of the three-phase inverter circuit 10 are arranged on both sides of the heat spreader 3 for all of the upper arms 11, and the interphase leads 411 that are not connected to the heat spreader 3 on one side function as the P leads 41. By providing the interphase leads 411 or P leads 41 on both sides of the heat spreader 3, the power semiconductor module 1 reduces the variation in heat dissipation in the directions on both sides of the heat spreader 3, and can reduce the temperature distribution within the chip and the temperature distribution between the chips.

[0032] Both sides of the N-lead 42 connected to the upper electrode of the power semiconductor chip 2 mounted on the heat spreader 3 for the lower arm 12 of the three-phase inverter circuit 10 are formed to protrude outward from opposing side surfaces of the molded resin 5 of the power semiconductor chip 2, and one end of the protruding lead is used to connect to the negative electrode side of the power supply. In the power semiconductor module 1, by arranging both sides of the N-lead 42 connected to the top of the power semiconductor chip 2 of the lower arm 12 to protrude outward from the molded resin 5, the variation in heat dissipation in the left-right direction is reduced, and the temperature distribution within the chip and the temperature distribution between the chips can be reduced.

[0033] As shown in the configuration of the power semiconductor module 1 in Fig. 2, a P lead 41 and an N lead 42 exposed from the mold resin 5 are provided on both sides of the power semiconductor module 1. A power supply is connected to one end of the leads, but it is also possible to connect a power supply to the other end. In addition, by providing the same structure to the side not connected to the power supply, the power semiconductor module 1 can equalize the heat dissipation of the power semiconductor chips 2 that make up the circuit.

[0034] FIG. 6 is a diagram showing a main flow of the manufacturing method of the power converter 100 according to the first embodiment. First, in step S1, a required number of combinations are prepared in which the heat spreader 3 is joined to the lower electrodes of the power semiconductor chips 2. Next, in step S2, the combined power semiconductor chips 2 and the heat spreader 3 are arranged in the form of a three-phase inverter circuit 10, and the power semiconductor chips 2 and the heat spreader 3 are joined by a lead frame having a P lead 41, an N lead 42, an interphase lead 411, an AC lead 43, and an inner lead 44, while these leads 4 are connected to the lead frame. In step S3, signal wiring required for the circuit, such as control signals and sensor signals, is performed, and in step S4, the power semiconductor chips 2, the heat spreader 3, the leads 4, and the signal wiring are resin-molded by transfer molding to manufacture the power semiconductor module 1. Next, in step S5, the shape of the leads 4 exposed from the power semiconductor module 1 is formed, and unnecessary connection parts of the lead frame are cut off. In step S6, a heat sink is joined to the power semiconductor module 1. Finally, in step S7, a control board is connected to the power semiconductor module 1, and the module is then housed in a case to complete the assembly.

[0035] In the power semiconductor module 1 of the power conversion device according to the first embodiment, various leads 4 are integrated with a lead frame, and the leads 4 are formed by cutting off unnecessary parts of the lead frame, so that productivity is good. Furthermore, by forming the leads 4 with a lead frame whose shape is formed with high precision, the variation of parts in the manufacturing process is reduced, and the resulting variation in temperature during use can be reduced.

[0036] Embodiment 2 The power conversion device 100 of the second embodiment is configured by combining three phases of the three-phase inverter circuit 10 of the power conversion device 100 of the first embodiment with power semiconductor modules 1 each having a circuit for one phase mounted therein. Fig. 7 is a schematic diagram showing the configuration of the power semiconductor module 1 of the power conversion device 100 according to the second embodiment. Fig. 8 is a schematic cross-sectional view showing the CC cross section of the power semiconductor module 1 of the power conversion device 100 according to the second embodiment in Fig. 7. Note that parts corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0037] The power semiconductor module of the second embodiment is characterized in that the power semiconductor module 1 is configured to mount one phase of a three-phase inverter circuit 10 therein, and the three-phase inverter circuit 10 is configured by joining the P leads 41 and the N leads 42 protruding from the opposing surfaces of the molded resin 5 of the power semiconductor module 1 to each other at the welded portion 4a. The combined power semiconductor module 1 is configured of three power semiconductor modules 1 divided for each phase, and the P leads 41 exposed from both sides of the power semiconductor module 1 of each phase are joined to the P leads 41 of the other phase to configure interphase leads 411, and the N leads 42 exposed from both sides of the power semiconductor module 1 of each phase are joined to the N leads 42 of the other phase to configure the connected N leads 42. By connecting them in this way, a function equivalent to that of the power semiconductor module 1 shown in the first embodiment is realized.

[0038] In a structure in which the three-phase inverter circuit 10 is built into one power semiconductor module 1, the power semiconductor module 1 becomes larger than in a structure in which a part of the three-phase inverter circuit 10 is built into one. In a mold-sealed power semiconductor module 1, warping occurs due to the difference in the linear expansion coefficient between the mold resin 5 and the leads 4 of the wiring member and the heat spreader 3, and if the warping is large, the thermal resistance between the connected heat sink increases. The power semiconductor chip 2 mounted in a portion that is far from the heat sink due to the warping becomes poorly cooled, so the temperature increases, which further restricts the increase in output. In addition, as the power semiconductor module 1 becomes larger, if even one of the power semiconductor chips 2 constituting the three-phase inverter circuit 10 has a defective characteristic, the power semiconductor module 1 will have to be scrapped, and this may increase losses in the production process.

[0039] The power semiconductor module 1 in the power conversion device 100 of the second embodiment is configured such that the power semiconductor module 1 is formed into a plurality of separate pieces and connected by the P lead 41 and the N lead 42, thereby making it possible to reduce the size of each power semiconductor module 1. In addition, it is possible to reduce warping of the module caused by differences in the linear expansion coefficient between the components of the module, and to prevent an increase in contact thermal resistance at the connection portion with the heat sink. In addition, by arranging a plurality of identical power semiconductor modules 1 having a shape in which the P lead 41 and the N lead 42 protrude from both sides of the power semiconductor module 1, the leads 4 can be easily connected to each other, and the three-phase inverter circuit 10 can be easily configured.

[0040] Embodiment 3 The power converter 100 of the third embodiment is obtained by replacing the heat spreader 3, the insulating layer 9, and the copper foil 9a of the power semiconductor module 1 of the power converter 100 of the second embodiment with a ceramic substrate. Fig. 9 is a schematic diagram showing a configuration of the power semiconductor module 1 of the power converter 100 according to the third embodiment. Fig. 10 is a schematic cross-sectional view showing the DD cross section of the power semiconductor module 1 of the power converter 100 according to the third embodiment in Fig. 9. Note that parts corresponding to the components of the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0041] The ceramic substrate 20 is formed by connecting copper alloy or aluminum alloy plates to both sides of a ceramic plate 21 to integrate the upper arm 11 and the lower arm 12 for one phase. Note that the ceramic plate 21 of the ceramic substrate 20 may be separated for each power semiconductor chip 2. In the power semiconductor module 1 in the third embodiment, since the ceramic plate is an insulating material having extremely high reliability, high insulation between the power semiconductor chip 2 and the outside can be ensured. Moreover, since the ceramic plate 21 is made of a material having high thermal conductivity, it is possible to realize a configuration that reduces the thermal resistance of the heat dissipation path from the power semiconductor chip 2 to the heat sink.

[0042] In the power semiconductor module 1 in the third embodiment, the ceramic substrate 20 is disposed inside the power semiconductor module 1, and the heat spreader 3 is formed by a metal pattern on one side of the ceramic plate 21. Also, a copper plate 21a can be formed on the back side. This ensures high insulation performance and improves heat dissipation. Even if the power semiconductor module 1 is configured with the ceramic substrate 20, it is possible to provide a configuration in which the heat spreader 3 is separately installed for each upper arm or each lower arm of one phase of the three-phase inverter circuit 10, as in the first and second embodiments. Also, it is possible to realize the arrangement of various leads for reducing the inductance of the current path, and it is possible to reduce the temperature difference between the power semiconductor chips 2. Also, it is possible to reduce the amount of heat generated by the power semiconductor chips 2 by reducing the inductance. Furthermore, it is possible to realize the miniaturization of the power semiconductor module 1 by exposing the mold resin 5 of the P lead 41 and the N lead 42 connected to the power source from the same side.

[0043] Moreover, in the power semiconductor module 1 in the present embodiment 3, the thickness of the heat spreader 3 formed by the wiring pattern of the ceramic substrate 20 is configured to be the same as the thickness of the leads 4. By making the thickness of the leads 4 joined to the upper electrodes of the power semiconductor chip 2 the same as the thickness of the heat spreader 3 joined to the lower electrodes of the power semiconductor chip 2, the heat generation per unit volume of the wiring itself due to the current flowing through the wiring can be equalized, and the temperature difference between the chips in the upper arm and the lower arm can be reduced.

[0044] Embodiment 4 The power conversion device 100 of the fourth embodiment is obtained by connecting the power semiconductor module 1 of the power conversion device 100 shown in the second and third embodiments to a heat sink, a control board, and a case. Fig. 11 is a schematic cross-sectional view (corresponding to the CC cross section in Fig. 7) in which the heat sink, the control board, and the case are mounted on the power semiconductor module 1 of the power conversion device 100 according to the fourth embodiment. Note that parts corresponding to the components of the first to third embodiments are denoted by the same reference numerals, and detailed explanations will be omitted.

[0045] In the power conversion device 100 of the fourth embodiment, the power semiconductor module 1 is configured to mount one phase of a three-phase inverter circuit 10 in which the upper arm 11 and the lower arm 12 are integrated, the P leads 41 protruding from opposing surfaces of the molded resin 5 of the power semiconductor module 1 are joined to each other at a welded portion 4a, the power semiconductor module 1 is mounted on a heat sink 30, and a control board 31 is disposed on the upper portion of the power semiconductor module 1. In addition, a case 32 is disposed around the power semiconductor module 1, which prevents intrusion of foreign matter from the outside and has a function of fixing external bus bars 33a, 33b, etc. of the power semiconductor module 1.

[0046] The control board 31 is provided with a heat dissipation hole 31a for dissipating the heat dissipated from the lead 4 of the power semiconductor module 1 to the outside. The heat of the power semiconductor module 1 is dissipated to the surroundings of the power semiconductor module 1 from the exposed parts of the P lead 41 and the N lead 42 from the mold resin 5. At this time, since the heat sink 30, which has a lower temperature than the power semiconductor module 1, is arranged on the lower surface of the power semiconductor module 1, the heated air rises to the control board side on the upper side of the power semiconductor module 1. By providing the heat dissipation hole 31a in the control board 31, the discharge W of the heated air to the outside is promoted, and the temperature rise of the power semiconductor module 1 is suppressed. Note that the installation position of the heat dissipation hole 31a is preferably at a position overlapping the P lead 41, the N lead 42, the inner lead 44, the interphase lead 411, the AC lead 43, or the heat spreader 3 as viewed from FIGS. 2, 7, and 9, but is not limited thereto. 2, 7 and 9, the shape of the heat dissipation hole 31a may be circular, elliptical or polygonal, or may be a shape cut out from an end face of the control board 31.

[0047] Moreover, in the power conversion device 100 of the fourth embodiment, the power semiconductor module 1 is configured to mount one phase of the three-phase inverter circuit 10 therein, and the P leads 41 protruding out from opposing surfaces of the molded resin 5 of the power semiconductor module 1 are connected to each other, and the N leads 42 protruding out from opposing surfaces of the molded resin 5 of the power semiconductor module 1 are connected to each other. Among the leads 4 exposed to the outside of the molded resin 5 of the power semiconductor module 1, there are leads 4 that are not in a current path with other members. These leads 4 are connected to a case-side bus bar 33a (the case-side bus bar 33a in FIG. 11, and a case-side bus bar (not shown) connected to the same left P lead as the case-side bus bar 33a in FIG. 11) mounted on the case 32 arranged on the outer periphery of the portion on which the power semiconductor module 1 is mounted.

[0048] By configuring in this manner, the power conversion device 100 of the fourth embodiment can suppress a change in the heat dissipation path of heat generated in the power semiconductor chip 2 depending on whether the lead 4 of the power semiconductor module 1 is connected to a component or the like outside the three-phase inverter circuit 10. In order to avoid a difference in temperature of the power semiconductor chip 2, the lead 4 that does not become a current path is connected to the bus bar 33a on the case side, thereby equalizing the heat dissipation of the three-phase inverter circuit 10. This makes it possible to prevent an increase in the temperature difference between the power semiconductor chip 2 on the side of the P lead 41 and N lead 42 connected to the inverter side bus bar 33b for inputting and outputting power and the power semiconductor chip 2 installed on the opposite side.

[0049] Although various exemplary embodiments and examples are described in this application, various features, aspects, and functions described in one or more embodiments are not limited to the application of a specific embodiment, but can be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are expected within the scope of the technology disclosed in this specification. For example, the following are included: when at least one component is modified, added, or omitted, and further, when at least one component is extracted and combined with a component of another embodiment. [Explanation of symbols]

[0050] 1 power semiconductor module, 2 power semiconductor chip, 3 heat spreader, 4 lead, 4a welded part, 41 P lead, 411 interphase lead, 42 N lead, 43 AC lead, 44 inner lead, 5 molded resin, 7 DC power supply, 8 motor, 9 insulating layer, 9a copper foil, 10 three-phase inverter circuit, 11 upper arm, 12 lower arm, 20 ceramic substrate, 21 ceramic plate, 21a copper plate, 30 heat sink, 31 control substrate, 31a heat dissipation hole, 32 case, 33a, 33b bus bar, 100 power conversion device.

Claims

1. A power conversion device including a power semiconductor module, a heat sink, and a control board to configure a three-phase inverter circuit, The power semiconductor module includes: power semiconductor chips arranged separately in an upper arm and a lower arm of the three-phase inverter circuit; a heat spreader joined to a lower electrode of the power semiconductor chip and provided for each of the power semiconductor chips; a P lead connected to the heat spreader joined to the power semiconductor chip disposed at the end of the upper arm and connected to a positive electrode of a power source; an interphase lead connecting the heat spreaders joined to the power semiconductor chips arranged on the upper arm; An N lead that is joined to an upper surface electrode of the power semiconductor chip arranged in a plurality of the lower arms and is connected to a negative electrode side of a power source; A power conversion device comprising:

2. 2. The power conversion device according to claim 1, wherein the power semiconductor chips are all of the same type and shape, and the power semiconductor chips and the heat spreader are combined and configured in a common shape.

3. 3. The power conversion device according to claim 1, wherein the power semiconductor chips are arranged symmetrically in the vertical and horizontal directions on a plane in which the power semiconductor module is arranged.

4. 2. The power conversion device according to claim 1, wherein the power semiconductor module includes, in addition to the P lead, the interphase lead, and the N lead, as leads connected to the power semiconductor chip or the heat spreader, an AC lead for outputting AC power from the heat spreader of the power semiconductor chip of the lower arm in each phase, and an inner lead joined to an upper surface electrode of the power semiconductor chip of the upper arm and connected to the heat spreader of the lower arm of the same phase.

5. 5. The power conversion device according to claim 4, wherein the power semiconductor module is sealed with a molding resin.

6. 6. The power conversion device according to claim 5, wherein the P lead, the N lead and the AC lead have ends exposed outside the molding resin.

7. 7. The power conversion device according to claim 6, wherein the P lead and the N lead have ends exposed outside a molding resin from both sides of the power semiconductor module, and have a structure that allows connection to a power source from either side.

8. 8. The power conversion device according to claim 7, wherein the heat spreader joined to the power semiconductor chip constituting the upper arm has the interphase lead or the P lead on both sides.

9. 6. The power conversion device according to claim 5, wherein the power semiconductor module is composed of three power semiconductor modules divided for each phase, the P leads exposed from both sides of the power semiconductor module of each phase are joined to the P leads of the other phase to form the inter-phase leads, and the N leads exposed from both sides of the power semiconductor module of each phase are joined to the N leads of the other phase to form the connected N leads.

10. 10. The power conversion device according to claim 9, wherein the heat spreader of the power semiconductor module is formed on a ceramic substrate.

11. 11. The power converter according to claim 10, wherein the thickness of the heat spreader is the same as the thickness of the leads.

12. 6. The power conversion device according to claim 5, wherein the power semiconductor module is mounted on the heat sink, a control board for controlling the power semiconductor module is disposed on top of the power semiconductor module, and the control board is provided with a heat dissipation hole for dissipating heat emitted from the leads of the power semiconductor module to the outside.

13. 13. The power conversion device according to claim 12, further comprising a case for housing the power semiconductor module and the control board, wherein a case-side bus bar for dissipating heat is connected to a lead exposed from the power semiconductor module and not forming a current path.

14. A method for manufacturing a power conversion device in which a three-phase inverter circuit is configured by mounting a power semiconductor module, a heat sink, and a control board, comprising the steps of: bonding the power semiconductor chip to a heat spreader; The joined power semiconductor chip and the heat spreader are arranged, joining leads to the power semiconductor chip and the heat spreader; providing signal wiring on a circuit of the power semiconductor chip; a step of resin-molding the power semiconductor chip, the heat spreader, the leads, and the signal wiring by transfer molding to manufacture a power semiconductor module; forming a shape of the lead exposed from a molding resin of the power semiconductor module; bonding a heat sink to the power semiconductor module; housing the power semiconductor module and a control board for controlling the power semiconductor module in a case; A method for manufacturing a power conversion device comprising:

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