JP2009032997A - Power module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power module capable of realizing miniaturization and improvement of radiation. <P>SOLUTION: Chips 1a-1c, 2a-2c, a heat sink 80 exposed to the outside of a casing 30, two pieces of terminal boards 40H, 40L which are parallel but different in height position, and a plurality of parallel bus bars 11u-11w which form intersecting part having lower gap between the terminal board 40H at a low position and upper gap between the terminal board 40L at high position respectively, are provided. In this case, each one chip is pinched between the bus bar and the terminal board while the heat sink is contacted thermally with at least one piece of the terminal board and the bus bar at at least one of the intersecting part while interposing a thermally conductive insulating layer 71. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power module with improved heat dissipation used to drive an electric motor such as a hybrid electric vehicle (HEV) or an electric vehicle (EV).

Electric vehicles, hybrid vehicles (HEV), and electric vehicles (EV) are attracting attention against the background of soaring fossil fuels and regulations on CO ₂ emissions to prevent global warming. In HEV, an electric motor is AC driven by switching DC power using an inverter circuit including a plurality of power switching elements. On / off of the power switching element is controlled by a control circuit.

  As a configuration example of a conventional power module, a power module in which a control circuit, an inverter circuit, and an electric motor are integrated is disclosed (Patent Document 1). In this power module, a printed circuit board is fixed to the outer peripheral surface of the peripheral wall of the motor housing, and a control circuit and an inverter circuit are mounted on the printed circuit board.

  In addition, a proposal for a structure for improving the manufacturing yield of an annular bus bar for power distribution to a stator of a three-phase thin DC brushless motor (Patent Document 2) and an insulating resin coating excellent in waterproofness and insulation resistance A proposal (Patent Document 3) of an insert molding method for a bus bar with a housing has been made.

  According to said bus bar, alternating current power can be supplied to the electric motor mounted in HEV etc. using the bus bar which implement | achieves cheap and reliable electrical connection as mentioned above. However, no proposal has been made for downsizing the power module or improving the space utilization efficiency. Moreover, although a large current flows through the power switching element arranged in the power module and generates a large amount of heat, the above-mentioned prior art documents do not suggest a thermal problem.

In general, there are finned heat dissipating parts for heat dissipating parts that efficiently dissipate heat from a semiconductor chip, and many proposals have been made for these finned heat dissipating parts. For example, in the cooling structure in which the gap between the mounting boards of the semiconductor elements of the computer is an air path of the refrigerant, in order to equalize the temperature of the semiconductor element on the inlet side of the air cooling path and the semiconductor element on the outlet side of the air cooling path, There has been proposed a structure in which the intervals on the inlet side of a plurality of mounting boards are arranged larger than the intervals on the outlet side (see Patent Document 4). According to this cooling structure, since the flow velocity of the air flow can be increased on the outlet side, the air temperature is high on the outlet side. Can be aligned to the same. In addition, a cooling structure has been proposed in which the width of the inlet side of the water channel is wider than the width of the outlet side in the structure in which the semiconductor element of the computer is water-cooled (see Patent Document 5). Also in this case, by increasing the flow rate of the cooling water on the outlet side from the inlet side, the temperature of the semiconductor elements can be made uniform by improving the heat radiation amount by increasing the flow rate, regardless of the increase in the water temperature on the outlet side.
JP 2003-324903 A JP 2003-134728 A JP 2003-134756 A Japanese Patent Laid-Open No. 03-085796 International Publication WO00 / 16397

  The miniaturization of the power module using the bus bar as described above and the improvement of the heat dissipation are difficult problems to satisfy both, but if the improvement of the heat dissipation cannot be obtained even if only the miniaturization can be realized. Can only be used in systems with low current capacity. For this reason, it is important for the power module to improve both miniaturization and heat dissipation, and it contributes to the prevention of global warming through improved fuel consumption such as HEV. An object of this invention is to provide the power module which can implement | achieve both size reduction and the improvement of heat dissipation.

  The power module of the present invention includes a plurality of power switching elements located in the casing, and one or more heat sinks exposed from the casing to the outside of the casing. In addition, two DC power supply conductors having a height at a height position, which is a distance from the first surface of the casing, which is inserted into the casing and extending in parallel with each other, are further provided at the same height position. Have all the height positions between the two DC power supply conductors, a lower gap with the lower DC power supply conductor, and an upper gap with the higher DC power supply conductor, A plurality of AC power supply conductors that pass through the casing in parallel with each other are formed while forming respective intersections. The plurality of power switching elements are positioned so as to be sandwiched between the DC power supply conductor and the AC power supply conductor, one at each intersection. One or two or more heat sinks interpose at least one of the two DC power supply conductors and the plurality of AC power supply conductors and at least one of the intersections with a heat conductive insulating layer. And is in thermal contact. Note that the lower gap or the upper gap is a gap located on the opposite side of the first surface when viewed from the AC power supply conductor at the intermediate height position is called an upper gap, and the gap located on the first surface side is This is called the lower gap. Further, the term “thermal contact” refers to a state where there is thermal conduction from the conductor to the heat sink via the DC power supply conductor or AC power supply conductor and the heat conductive insulating layer. The thermally conductive insulating layer is used in a mode (thermal conductivity, thickness, etc.) that does not hinder the heat conduction as much as possible while having electrical insulation.

  With the above configuration, the control unit can be separated and an inverter circuit can be formed without using a printed circuit board, so that significant downsizing can be realized. For this reason, it becomes easy to arrange | position with the form which raised space utilization efficiency in the member clearance gap of the outer surface of an electric motor. Also, because the heat generated by the power switching element is transmitted to the DC power source conductor or AC power source conductor and the heat sink in the region where the power switching element is located, while ensuring electrical insulation, Heat dissipation can be improved.

  Each of the plurality of power switching elements has a first current-carrying electrode on one surface and a second current-carrying electrode on the other surface that forms a front-back relationship with the one surface. In the intersection having the lower gap, the first current-carrying electrode is fixed to the low-position DC power supply conductor with a conductive fixing material, and the second current-carrying electrode is electrically connected to the AC power supply conductor. At the intersection having an upper gap, the first energization electrode is fixed to the AC power supply conductor with a conductive fixing material, and is electrically connected to the DC power supply conductor at a higher position. Yes. The heat sink can be in thermal contact with the DC power supply conductor or the AC power supply conductor at a low position, to which the power switching element is fixed, from the first surface side through a thermally conductive insulating layer. . With this configuration, the heat sink is in thermal contact with the conductor that conducts more heat of the power switching element, so that the heat can be efficiently radiated. Further, since the heat sink is disposed only on the first surface side, the space utilization efficiency is not impaired.

  The heat sink is composed of a first heat sink and a second heat sink. The first heat sink is located closer to the first surface than the low-position DC power supply conductor and overlaps the power switching element when seen in a plan view. Extending along the lower DC power source conductor and intersecting all of the AC power AC conductors, and is in thermal contact with the lower DC power source conductor from the first surface side. . In addition, the second heat sink is located closer to the first surface than the AC power supply conductor, and along the DC power supply conductor at a higher position in plan view, and on all of the plurality of AC power AC conductors. It extends so as to overlap the power switching element while intersecting, and can be in thermal contact with all of the AC power supply conductors from the first surface side. As a result, the heat sink is brought into thermal contact from the first surface of the casing to the first DC power supply conductor and the AC power supply conductor that are fixed in height and have different height positions. Heat can be dissipated from one side of the body. For this reason, the heat from all the power switching elements arrange | positioned at a power module can be dissipated outside efficiently efficiently. Further, for example, by disposing the power module with the opposed surface side that is in front-to-back relation with the first surface as a surface close to the electric motor, the space utilization efficiency can be maintained. The first surface side may be the bottom plate side of the housing, the upper surface or the upper lid side.

  The heat conductive insulating layer can have a heat conductivity of 3 W / (m · K) or more. Thereby, more heat can be guide | induced to a heat sink and heat dissipation, ensuring electrical insulation.

  The heat sink has a fin, and the fin can be disposed outside the housing. As a result, more heat can be dissipated from the heat sink to the outside.

  According to the power module of the present invention, both miniaturization and improvement in heat dissipation can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the element which attached | subjected the same or corresponding code | symbol in different drawing shall show the same or corresponding element.

  FIG. 1 is a plan view showing a power module 50 for a three-phase AC motor of the present invention. FIG. 2 is a plan view of the power module 50 shown in FIG. 1 with the top cover removed. As shown in FIG. 1, bus rings or bus bars 11u, 11v, and 11w, which are conductors for supplying power to the three-phase AC motor, are fitted in grooves in the bus bar casing 19, and extend along the periphery of an electric motor (not shown). Although the ring shape is circular, the straight line shape does not hinder the description of the present invention. Therefore, in order to avoid complication, the straight line shape is illustrated. The case where a straight line is illustrated in the subsequent drawings is also interpreted as described above. 3 is a cross-sectional view taken along line III-III in FIG. The present embodiment has one feature in that heat sinks 80A and 80B are used as shown in FIG. Both of the heat sinks 80A and 80B are exposed from the heat sink insertion hole 39 of the bottom plate 30b of the power module housing 30, and in particular, the fin portion 83 of the heat sink 80 protrudes out of the housing 30. As shown in FIG. 3, the heat sink 80A is in thermal contact with the positive side terminal plate 40H of the DC power supply conductor, which is the conductor closest to the bottom plate 30b, with the heat conductive insulating layer 81 having a high thermal conductivity interposed therebetween. is doing. The heat sink 80B is in thermal contact with the bus bars 11u, 11v, and 11w for supplying the three-phase AC power with the heat conductive insulating layer 81 having a high thermal conductivity interposed therebetween. The heat sink 80 includes a base portion 81 and a fin portion 83, both of which are made of aluminum or an aluminum alloy. In FIG. 3, the fin portion 83 is located outside the housing 30, and the inside of the housing 30 is the base portion 81. Accounted for. However, if the base portion 81 is excessively thick, even if the base portion 81 is formed of aluminum or the like having a high thermal conductivity, the heat dissipation is hindered, so that the fin portion 83 may enter the housing 30. Further, the tips of the fin portions 83 do not have to be on the same plane between the heat sinks 80A and 80B, and may have a step. For example, the tips of the fins 83 of the heat sink 80B may have a step so that they are closer to the housing 30 than the heat sink 80A. In addition, although an electric motor is not shown in FIG. 1, it is preferable that the position of the heat sink 80 is located farther from the electric motor in order to improve space utilization efficiency. Therefore, it is preferable that the electric motor be positioned in front of the sheet of FIG.

  The semiconductor chips 1a to 1c and 2a to 2c, which are power switching elements, include crossing portions of three lower gaps formed by the bus bars 11u, 11v, and 11w and the low-side plus-side terminal plate 40H, and the bus bar. A total of six are arranged, one at each of the intersections of the three upper gaps formed by 11u, 11v, 11w and the minus-side terminal plate 40L at the high height (see FIG. 2). . The semiconductor chips 1a to 1c are fixed to the plus terminal plate 40H at a low height by soldering or brazing, and the semiconductor chips 2a to 2c are similarly fixed to the bus bars 11u, 11v, and 11w. The heat sinks 80A and 80B are in thermal contact with the conductor to which the semiconductor chips 1a to 1c and 2a to 2c are fixed. Heat generated in the semiconductor chips 1 a to 1 c and 2 a to 2 c is dissipated to the outside through the base portion 81 of the heat sink 80 and the fin portion 83. In the case of FIG. 3, the heat medium that carries out heat exchange by the fins 83 is a liquid such as water. However, the heat medium is not limited to a liquid and may be air as shown in FIG. When the heat medium is liquid, a fluid-tight flow path is necessary, but when it is the atmosphere, no flow path is necessary. For the two heat sinks 80A and 80B, the flow paths may be connected in series or in parallel.

  As shown in FIG. 2, in the power module 50 according to the present embodiment, the intersections between the DC power supply conductors or terminal plates 40H and 40L and the bus bars 11u, 11v, and 11w are in the housing 30, and each intersection The power switching element is arranged in the lower gap or the upper gap in the section. The housing 30 is a rectangular parallelepiped, and includes a bottom plate 30b and side plates 30s, and an upper lid (not shown) (see FIG. 13). The structure provided for the DC power supply conductors 40H and 40L and the bus bars 11u, 11v, and 11w to pass through the side plate 30s of the housing 30 will be described in detail later. In FIG. 2, the outline of the heat sinks 80A and 80B that should be indicated by broken lines is omitted in order to avoid complication of the drawing.

  FIG. 5 is a circuit diagram showing the configuration of the power module according to the embodiment of the present invention. 2 and 5 show examples in which power MOSFETs 1a to 1c and 2a to 2c are used as power switching elements. The power module according to the present embodiment includes a three-phase (U-phase, V-phase, W-phase) electric motor 4, an inverter circuit 8 for driving the electric motor 4, and power MOSFETs 1a to 1c included in the inverter circuit 8. , 2a to 2c (see FIG. 3). Although not shown in the figure because it does not affect the essence of the present invention, there is a parasitic diode between the drain and source in each of the power MOSFETs 1a to 1c and 2a to 2c. It flows in this parasitic diode.

  As shown in FIG. 5, the power MOSFETs 1a and 2a are connected in series via a node 6u between a terminal plate 40H having a positive DC power supply voltage VH and a terminal plate 40L having a negative DC power supply voltage VL. Yes. Specifically, the drain electrode of the power MOSFET 1a is connected to the terminal plate 40H of the positive DC power supply voltage VH, and the source electrode is connected to the node 6u. The drain electrode of the power MOSFET 2a is connected to the node 6u, and the source electrode is connected to the terminal plate 40L of the negative DC power supply voltage VL. Similarly, the power MOSFETs 1b and 2b are connected in series via a node 6v between a terminal plate 40H having a positive DC power supply voltage VH and a terminal plate 40L having a negative power supply voltage VL. The power MOSFETs 1c and 2c are connected in series via a node 6w between a terminal plate 40H having a positive DC power supply voltage VH and a terminal plate 40L having a negative DC power supply voltage VL.

  As shown in FIG. 2, the gate electrodes of the power MOSFETs 1a to 1c and 2a to 2c are connected to a terminal of the connector 60 by a signal line 61 and further connected to an external control circuit. The control circuit 7 drives the power MOSFETs 1a to 1c and 2a to 2c by applying voltage pulses to the gate electrodes of the power MOSFETs 1a to 1c and 2a to 2c, respectively (see FIG. 5).

  The nodes 6u, 6v, 6w are connected to the electrodes 5u, 5v, 5w of each phase of the electric motor 4, respectively. Depending on which of the power MOSFETs 1a to 1c and the power MOSFETs 2a to 2c is driven by the control circuit 7, the direction of the current flowing in the electromagnetic coil 3 provided in the electric motor 4 can be controlled. The magnitude of the current flowing through the electromagnetic coil 3 can be controlled by the pulse width of the voltage pulse applied from the control circuit 7 to the gate electrodes of the power MOSFETs 1a to 1c and 2a to 2c.

  Although FIG. 5 shows an example in which the power MOSFETs 1a to 1c and 2a to 2c are used as the power switching elements, other power switching elements such as IGBTs may be used instead of the power MOSFETs. In addition, since there is no parasitic diode in IGBT, it is necessary to connect a commutation diode in antiparallel. Alternatively, a transistor capable of controlling high power and operating at high temperature using a wide band gap semiconductor such as SiC, GaN, or C may be used. When a wide band gap device is used, an inverter circuit that can operate in a high-temperature environment can be realized like the electric motor 4.

FIG. 5 shows an example in which only one power MOSFET is used for the high side and the low side of each phase of U, V, and W. A power MOSFET may be used.

  FIG. 6 is a top view showing a part of the structure of the bus bar 11 of the three-phase AC power supply conductor provided in the power module according to the present embodiment. A ring-shaped bus bar 11 is disposed along the outer periphery of the electric motor 4. The bus bar 11 is separated into a bus bar 11u corresponding to the U phase of the electric motor 4, a bus bar 11v corresponding to the V phase, and a bus bar 11w corresponding to the W phase. Bus bar 11u connects between node 6u and electrode 5u shown in FIG. 5, bus bar 11v connects between node 6v and electrode 5v, and bus bar 11w connects between node 6w and electrode 5w. The bus bars 11u to 11w are formed by performing a plating process such as tin or nickel on the surface of the punched copper plate.

The bus bars 11u to 11w are housed in the bus bar casing 19. The bus bar housing 19 is made of a heat resistant resin such as PPS (polyphenylene sulfide). However, the bus bar housing 19 may be reinforced with a metal member in order to increase the strength. A groove defined by the inner wall is formed inside the bus bar casing 19, and the bus bars 11 u to 11 w are fitted into the groove portions. Moreover, the area | region 18 in which the bus-bar housing | casing 19 is not formed is provided partially, and the bus-bars 11u-11w are exposed in this area | region 18. As shown in FIG. 2, the region 18 forms a portion that intersects the DC power supply conductors 40H and 40L in the housing 30 of the power module 50.

FIG. 7 is a perspective view specifically showing the structure of the bus bars 11 u to 11 w in the region 18. In FIG. 7, the ring-shaped bus bars 11u to 11w are illustrated in a straight line. On the surface of the bus bar 11u, a semiconductor chip (hereinafter, the same reference numeral as that of the power MOSFET) 2a of the power MOSFET 2a shown in FIGS. A semiconductor chip 2a can be mounted at a predetermined location on the surface of the bus bar 11u by marking a mark indicating a position where the chip is to be mounted. Similarly, semiconductor chips 2b and 2c of power MOSFETs 2b and 2c are mounted at predetermined locations on the surfaces of the bus bars 11v and 11w, respectively. Further, positioning notches 20u, 20v, and 20w are formed at predetermined positions on the bus bars 11u, 11v, and 11w, respectively. The semiconductor chips 2a to 2c located on the bus bars 11u, 11v, and 11w shown in FIG. 7 are all arranged at the intersections having an upper gap.

FIG. 8 is a top view showing the structure of the semiconductor chip 2a, and FIG. 9 is a cross-sectional view taken along line IX-IX shown in FIG. 6 and 7, semiconductor chip 2a is a so-called vertical power MOS chip, and a gate electrode (control electrode) G and a source electrode (current outflow electrode) S are formed on the surface of semiconductor chip 2a. A drain electrode (current inflow electrode) D is formed on the back surface. An elastic conductor 10 is joined on the source electrode S. The elastic conductor 10 is bonded onto the source electrode S by soldering or brazing. The elastic conductor 10 is formed by using phosphor bronze and plating the surface thereof with tin or nickel. The illustrated elastic conductor 10 is a U-shaped leaf spring, but may be a string spring or the like.

  The semiconductor chips 2b and 2c have the same structure as the semiconductor chip 2a. That is, the gate electrode G and the source electrode S are formed on each surface of the semiconductor chips 2b and 2c, and the drain electrode D is formed on each back surface. The springs of the elastic conductors 10 are joined to the source electrodes S of the semiconductor chips 2a to 2c, and the drain electrodes D are directly connected to the surfaces of the bus bars 11u to 11w by soldering or brazing, which is a conductive fixing material, respectively. It is joined to.

FIG. 10 is a perspective view showing the structure of the housing 30 included in the power module according to the present embodiment. The housing 30 is made of a heat resistant resin such as PPS. The bottom plate 30b of the housing 30 is provided with a heat sink insertion hole 39 for mounting the heat sinks 80A and 80B. In addition, a plurality of rectangular cutouts 31u, 31v, 31w, 32H, and 32L are formed in the side plate 30s of the housing 30 as a positioning structure. The bottom Kb of each of the grooves 31u, 31v, 31w, 32H, and 32L is in contact with the bus bars 11u to 11w and the terminal plates 40H and 40L, and has a height position that is the distance from the bottom plate 30b of each housing of these conductors. To decide. The groove 32H is formed deeper than the grooves 31u to 31w. Therefore, the bottom Kb of the groove 32H is closer to the bottom plate 30b of the housing than the bottom Kb of the grooves 31u to 31w. Further, the groove 32L is formed shallower than the grooves 31u to 31w, and therefore the bottom Kb of the groove 32L is located farther from the bottom plate 30b of the housing than the bottom Kb of the grooves 31u to 31w. Since each groove is a rectangular cutout, two opposing wall sides Ks are parallel and orthogonal to the bottom side Kb. An opening 33 for inserting a connector is formed between the groove 32H and the groove 32L.

7 and 10, the interval between adjacent grooves 31u to 31w determines the interval between adjacent bus bars 11u to 11w at the location where notches 20u to 20w are formed. Are equal. Moreover, the space | interval of the opposing side plates 30s in which the grooves 31u-31w are formed is equal to the space | interval of the notches 20u mutually adjacent in the direction where the bus-bars 11u-11w extend. The positioning notches 20u, 20v, and 20w of each bus bar shown in FIG. 7 are fitted to engage with the grooves 31u, 31v, and 31w of FIG. 10, and each bus bar is supported by the bottom Kb of the groove.

11 and 12 are perspective views sequentially showing the assembly process of the power module according to the present embodiment. First, referring to FIG. 11, terminal plate 40H as a DC power source conductor is fitted into groove 32H of housing 30 shown in FIG. The terminal board 40H is fitted in the groove 32H of the housing so as to be along one of the heat sink insertion holes 39. The terminal board 40H is for supplying the positive DC power supply voltage VH shown in FIG. 5, and is formed by performing a plating process such as tin or nickel on the surface of the copper board. Similarly to the bus bars 11u to 11w, the terminal plate 40H is formed with a notch 20H at a predetermined location. By fitting the notch 20H into the wall side Ks of the groove 32H, the terminal 30 and the terminal 30H are connected. Positioning with the plate 40H is performed. Further, the height position (distance from the bottom plate 30b of the housing) is determined by the bottom side Kb of the groove 32H.

The semiconductor chips 1a to 1c of the power MOSFETs 1a to 1c shown in FIG. 5 are mounted in advance at predetermined locations on the surface of the terminal board 40H. The semiconductor chips 1a to 1c can be mounted at the predetermined locations by marking the positions indicating the positions where the chips are to be mounted at predetermined locations on the surface of the terminal board 40H.

The semiconductor chips 1a to 1c have the same structure as the semiconductor chips 2a to 2c shown in FIGS. That is, the gate electrode G and the source electrode S are formed on each surface of the semiconductor chips 1a to 1c, and the drain electrode D is formed on each back surface. The elastic conductor 10 is joined to the source electrodes S of the semiconductor chips 1a to 1c by soldering or brazing, and the drain electrodes D of the semiconductor chips 1a to 1c are connected to the surface of the terminal plate 40H by soldering or brazing. Are directly joined to each other. The semiconductor chips 1a to 1c shown in FIG. 11 are all arranged at intersections having a downward gap.

One end of a high-voltage cable for power supply is connected to the end of the terminal board 40H that protrudes from the housing 30 to the outside. The other end of the high voltage cable is connected to a battery or a boost converter.

Next, referring to FIG. 12, the bus bars 11 u to 11 w are fitted into the grooves 31 u to 31 w of the housing 30, respectively. Specifically, after the structure shown in FIG. 11 is positioned below the bus bars 11u, 11v, and 11w shown in FIG. 7, the grooves 31u to 31w and the notches 20u to 20w are fitted, respectively. The structure shown in FIG. 11 is lifted upward. Thereby, as shown in FIG. 12, the U-shaped elastic conductors 10 on the source electrodes S of the semiconductor chips 1a to 1c come into contact with the back surfaces of the bus bars 11u to 11w, respectively.

In short, the semiconductor chips 1a to 1c are arranged one by one at intersections with a height gap formed by the terminal plate 40H and the bus bars 11u to 11w. The height gap corresponds to the mounting height of the semiconductor chips 1 a to 1 c including the U-shaped elastic conductor 10. At this time, since one end of the U-shaped elastic conductor is not fixed, the elastic conductor 10 bonded onto each source electrode S of the semiconductor chips 1a to 1c is pressed and bent by the bus bars 11u to 11w. Due to this pressed deflection, each of the back surfaces of the bus bars 11u to 11w is pressed and brought into an electrically connected state. By interposing the elastic conductor 10, it is possible to join each source electrode S and the back surfaces of the bus bars 11u to 11w more simply than soldering or brazing. According to FIG. 12, the conductor chips 1a to 1c are located at the intersections having the lower gap and the semiconductor chips 2a to 2c are located at the intersections having the upper gap with reference to the height positions of the bus bars 11u to 11w. Is obvious.

Next, a terminal plate 40L as a DC power source conductor is fitted into the groove 32L of the housing 30 (see FIGS. 2 and 12). The terminal board 40L is for supplying the negative DC power supply voltage VL shown in FIG. 3, and is formed by plating the surface of the copper board with tin or nickel. The terminal plate 40L is formed with a notch 20L at a predetermined location, and the housing 30 and the terminal plate 40L are positioned by fitting the notch 20L into the wall side Ks of the groove 32L. Needless to say, the terminal plate 40H is a terminal plate at a low height as viewed from the bottom plate 30b, and the terminal plate 40L is a terminal plate at a high height.

Thereby, the elastic conductor 10 joined on each source electrode S of the semiconductor chips 2a to 2c is pressed and bent by the terminal plate 40L. By the press contact due to the bending of the elastic conductor 10, the source electrodes S of the semiconductor chips 2a to 2c and the back surface of the terminal plate 40L are electrically connected.

One end of a high-voltage cable for power supply is connected to the end of the terminal board 40 </ b> L that protrudes outward from the housing 30. The other end of the high voltage cable is connected to a battery or a boost converter.

Next, referring to FIG. 2, the connector 60 is fitted into the opening 33 of the housing 30 and fixed by screwing or the like. The connector 60 has a plurality of terminals (not shown), and the terminals protrude into the housing 30. One end of the signal line 61 electrically connected to the terminal is connected to the connector 60, and the other end is connected to the gate electrode G of each power switching element. As described above, the signal line 61 coming out of the connector is connected to the control circuit 7 shown in FIG.

  FIG. 13 is a diagram illustrating a state in which the heat sinks 80 </ b> A and 80 </ b> B are mounted from the heat sink insertion holes 39 of the housing 30 after the upper lid 30 t is fixed to the housing 30. The heat sinks 80A and 80B are more convenient after fixing the upper lid 30t, the bus bars 11u to 11w, the terminal boards 40H and 40L, etc. while taking thermal contact with the conductor. Referring to FIG. 3 and FIG. 4, the heat sink has the upper surface of base 81 connected to terminal plate 40 </ b> H and bus bars 11 u, 11 v, 11 w through a heat conductive insulating layer 71 having a high heat conductivity. . An adhesive is applied to both surfaces of the heat conductive insulating layer 71 for use. The heat conductivity of the heat conductive insulating layer 71 is 3 W / (m · K) or more, which is convenient for efficiently transferring the heat generated in the semiconductor chip to the heat sink 80. An epoxy insulating sheet or the like can be used for the heat conductive insulating layer 81. Various commercially available adhesives can be used for the adhesive applied to both surfaces of the heat conductive insulating layer 71. Among these, for example, an adhesive using an epoxy resin as a main agent and an amine resin as a curing agent is preferable. The above heat dissipation path has a very simple structure and can be miniaturized. The heat sink 80 can be pressed into and fixed to the resin casing 30 so that the interface of the epoxy resin sheet 71 is not peeled even when vibration is applied.

  According to the above embodiment of the present invention, without using a printed board, the current-carrying electrodes located on the upper and lower surfaces of the semiconductor chip and the bus bar and the terminal plate on the DC power source side are directly connected to make an electrical connection. Since it is mechanically connected without interposing other conductors, a reduction in size can be realized. Further, the heat generation problem in the semiconductor chip can be effectively overcome by bringing the heat sink into thermal contact with the conductor to which the semiconductor chip is connected via a heat conductive insulating layer.

Regarding the power module according to the embodiment of the present invention described above, attention should be paid to the following effects and other power module examples.
(1) In the present embodiment, the configuration in which the heat sink is mounted from the bottom plate side is shown, but a structure in which the heat sink is mounted from the upper lid side may be adopted. In the case of this configuration, the semiconductor chip has a drain electrode side fixed to a DC power source conductor at a high position at an intersection having an upper gap, and an elastic conductor is disposed between the bus bar and the source electrode. At the intersection having a lower gap, the semiconductor chip has the drain electrode side fixed to the bus bar, and an elastic conductor is disposed between the DC power source conductor and the source electrode at a low height. Accordingly, the first surface may be on the bottom plate side or on the upper lid side.
(2) In the above-described embodiment, the configuration in which the heat sink is divided into two parts is shown. However, the heat sink may be composed of one heat sink having a step at the base. In addition, the fin portion is positioned only outside the housing. However, as described above, the fin portion may be formed in a range inside the housing in order to improve heat dissipation.
(3) In order to reduce the thickness of the power module, for example, the heat sink base 81 may be extended to the outside of the circumference of the bus ring, and the fin 83 may stand on the upper lid side of the extended portion. With this structure, the thickness of the power module can be reduced. This structure can be applied to either a water cooling system or an air cooling system.
(4) In the above embodiment, the manufacturing method for mounting the heat sink from the heat sink insertion hole after assembling the main body of the power module has been described. First, the heat sink is mounted on the power module housing. Then, a manufacturing method in which the terminal board and the bus bar are incorporated later may be used. The same applies to the case where the heat sink is disposed on the upper lid side in the above (1).
(5) The heat sink may be anything as long as it has a portion that is in thermal contact with the terminal board or bus bar and is exposed to the outside of the housing, and the number and shape are not limited.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples of the present invention disclosed above are merely examples, and the scope of the present invention is the implementation of these inventions. It is not limited to the form. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  In the power module of the present invention, it is possible to overcome the high space utilization efficiency and the thermal problem, which are increasingly important in the power modules of electric motors such as HEV and EV.

It is a figure which shows the power module in embodiment of this invention. It is a top view of the state which removed the upper cover of the power module of FIG. It is sectional drawing which follows the III-III line | wire of FIG. 2 (when a heat medium is a liquid). It is sectional drawing which shows the modification of the power module shown in FIG. 3 (when a heat medium is air). It is a wiring diagram of the power module of FIGS. It is a figure which shows a bus bar and a bus-bar housing | casing. It is a figure which shows the power switching element mounted in the bus bar and the bus bar. It is a top view which shows a power switching element. It is sectional drawing which follows the IX-IX line of FIG. It is a figure which shows the housing | casing of a power module. It is a figure which shows the state which inserted the positive | plus side terminal board of the conductor for DC power supplies in the groove | channel of the housing | casing. It is a figure which shows the state which inserted the bus bar in the groove | channel of the housing | casing. It is a figure which shows the state which mounted | wore the heat sink, after fixing the upper cover of the housing | casing of a power module.

Explanation of symbols

1a to 1c, 2a to 2c Power MOSFET (semiconductor chip), 3 Electric motor coil, 4 Electrical motor, 5u to 5w Electric motor phase electrode, 6u to 6w node, 7 Control circuit, 8 Inverter circuit, 10 Elasticity Conductor, 11u, 11v, 11w Busbar (AC power supply conductor), 18 Busbar exposed area, 19 Busbar housing, 20H, 20L Positioning notch provided on terminal plate, 20u-20w Positioning notch provided on busbar, 30 Housing, 30b Housing bottom plate, 30s Housing side plate, 30t Top lid, 31u to 31w Housing bus bar groove (rectangular cutout), 32H, 32L Housing terminal board groove (rectangular cutout) 33 Opening (connector insertion slot), 39 Heat sink insertion hole, 40H Positive side terminal board (DC power supply conductor), 40L Negative side end Plate (DC power supply conductor), 50 power module, 60 connector, 61 signal line, 71 heat conductive insulating layer, 80, 80A, 80B heat sink, 81 heat sink base, 83 fin, Kb groove bottom, Ks groove wall Side, D drain electrode, G gate electrode, S source electrode.

Claims (5)

A plurality of power switching elements located in the housing;
One or more heat sinks exposed outside the housing from within the housing;
Two DC power supply conductors having a height at a height position that is a distance from the first surface of the housing, which is inserted into the housing and extends in parallel,
All the same height positions, a height position intermediate between the height positions of the two DC power source conductors, a lower gap from the lower DC power source conductor, and the higher DC power source A conductor for use is provided with a plurality of AC power supply conductors that pass through the casing in parallel with each other while forming an intersection having an upper gap, respectively,
The plurality of power switching elements are positioned so as to be sandwiched between the DC power supply conductor and the AC power supply conductor, one at each intersection.
The one or more heat sinks interpose at least one of the two DC power supply conductors and the plurality of AC power supply conductors and at least one of the intersections with a heat conductive insulating layer. A power module characterized by being in contact with heat.   Each of the power switching elements has a first current-carrying electrode on one surface and a second current-carrying electrode on the other surface that forms a front-back relationship with the one surface, and has an intersection with the lower gap. The first energizing electrode is fixed to the lower position DC power source conductor with a conductive fixing material, and the second energizing electrode is electrically connected to the AC power supply conductor. In the intersection having the upper gap, the first current-carrying electrode is fixed to the AC power supply conductor with a conductive fixing material, and is electrically connected to the DC power supply conductor at the high position. The heat sink is in thermal contact with a low-position DC power supply conductor or AC power supply conductor, to which the power switching element is fixed, from the first surface side through the thermally conductive insulating layer. It is characterized by The power module of claim 1.   The heat sink is composed of a first heat sink and a second heat sink, and the first heat sink is located closer to the first surface than the low-position DC power supply conductor, and in plan view, the power switching element. A DC power supply conductor at the lower position from the first surface side, extending along the conductor for the DC power supply at the lower position so as to overlap and intersecting all of the plurality of AC power AC conductors. The second heat sink is positioned closer to the first surface than the AC power supply conductor, along the DC power supply conductor at a higher position in plan view, and the plurality of heat sinks Extending over the power switching element while intersecting all the AC power AC conductors, and being in thermal contact with all of the AC power supply conductors from the first surface side. Do Power module according to claim 1 or 2.   The power module according to claim 1, wherein the thermally conductive insulating layer has a thermal conductivity of 3 W / (m · K) or more. The power module according to any one of claims 1 to 4, wherein the heat sink has fins, and the fins protrude from the casing.

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