JP2011217546A - Power module and power converter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power module having improved reliability.SOLUTION: The power module includes a conductor plate which forms a connection surface connected to one electrode surface of a power semiconductor element via a solder and forms a heat dissipation surface on the side opposite to the connection surface and a sealing material which seals the power semiconductor element and the conductor plate. The heat dissipation surface of the conductor plate is exposed from the sealing material, and the heat dissipation surface of the conductor plate exposed from the sealing material is covered with a thermosetting heat conductive sheet.

Description

  The present invention relates to a power module and a power conversion device using the same, and more particularly to a power conversion device mounted on a hybrid vehicle or an electric vehicle.

  From the viewpoint of energy saving, automobiles are required to have high fuel efficiency, and electric cars driven by motors and hybrid cars combining motor driving and engine driving are attracting attention. A large-capacity on-vehicle motor used in an automobile is difficult to drive or control with a DC voltage of a battery, and a power conversion device that uses switching of a power semiconductor is indispensable for boosting and AC control. In addition, a cooling structure is important because power semiconductors generate heat when energized.

  Patent Document 1 is disclosed as a semiconductor device that can be cooled from both sides.

  As shown in Patent Document 1, a semiconductor device is configured to include a pair of heat radiating plates for radiating heat from both sides of the heat generating element, resin-molding almost the entire device, and exposing each surface of the pair of heat radiating plates In addition, by compressing and molding the transfer mold die 371 with an insulating sheet made of a compressible material on each surface of the pair of heat sinks, the dimensional error of the member is absorbed and the element is destroyed. In addition, a semiconductor device that prevents the resin from entering the heat dissipation surface is known.

  However, from the viewpoint of ensuring withstand voltage or relaxing thermal stress, ensuring reliability has been insufficient.

JP 2002-324816 A

  The subject of this invention is providing the power module which improved reliability.

  In order to solve the problems of the present invention, a power module according to the present invention forms a connection surface connected to one electrode surface of a power semiconductor element via solder, and a surface opposite to the connection surface is formed. A conductive plate that forms a heat radiating surface, and a sealing material for sealing the power semiconductor element and the conductive plate, wherein the heat radiating surface of the conductive plate is exposed from the sealing material, and is sealed. The heat radiating surface of the conductor plate exposed from the stopper is configured to be covered with a thermosetting heat conductive sheet.

  Thereby, since the inclination of a power semiconductor element and a conductor board can be absorbed with a thermosetting heat conductive sheet, the reliability for insulation of a conductor board can be improved, maintaining high heat dissipation.

  According to the present invention, the reliability of the power module can be improved.

It is a figure which shows the control block of a hybrid vehicle. It is the control block diagram and circuit block diagram at the time of applying to a hybrid vehicle. The disassembled perspective view for demonstrating the installation place of the power converter device 200 which concerns on this embodiment is shown. It is the perspective view which decomposed | disassembled the whole structure of the power converter device which concerns on this embodiment into each component. 4 is a bottom view of the cooling jacket 12 having a flow path 19. FIG. (A) is a perspective view of the power module 300a of this embodiment. (B) is sectional drawing of the power module 300a of this embodiment. (A) is internal sectional drawing which removed the module case 304, the insulating sheet 333, the 1st sealing resin 348, and the 2nd sealing resin 351, in order to help an understanding. (B) is an internal perspective view. FIG. 7A is an exploded view for helping understanding of the structure of FIG. FIG. 4B is a circuit diagram of the power semiconductor module 300. FIG. FIG. 5 is a diagram showing a manufacturing process of a power module 300. FIG. 5 is a diagram showing a manufacturing process of a power module 300. FIG. 5 is a diagram showing a manufacturing process of a power module 300. FIG. 5 is a diagram showing a manufacturing process of a power module 300. FIG. 5 is a diagram showing a manufacturing process of a power module 300. FIG. 5 is a diagram showing a manufacturing process of a power module 300. It is a cross-sectional schematic diagram of the power module 300 which concerns on 2nd Example. It is sectional drawing of the power module which concerns on a comparative example.

  Hereinafter, embodiments according to the present invention will be described with reference to examples and comparative examples.

  The power conversion device 200 according to the present embodiment can be applied to a hybrid vehicle or a pure electric vehicle. As a representative example, a control configuration and a circuit configuration when applied to a hybrid vehicle are illustrated in FIGS. 1 and 2. Will be described.

FIG. 1 is a diagram showing a control block of a hybrid vehicle.
The power conversion device according to the present embodiment will be described by taking, as an example, an inverter device for driving a vehicle that is used in an electric vehicle driving system and that has a very severe mounting environment and operational environment. The configuration of the present embodiment is optimal as a power conversion device for driving a vehicle such as an automobile or a truck. However, other power conversion devices such as a power conversion device such as a train, a ship, and an aircraft, and a factory facility are also included. Applicable to industrial power converters used as drive motor control devices, or household power conversion devices used in home solar power generation systems and motor control devices that drive household appliances It is.

  In FIG. 1, a hybrid electric vehicle (hereinafter referred to as “HEV”) 110 is one electric vehicle and includes two vehicle drive systems. One of them is an engine system that uses an engine 120 that is an internal combustion engine as a power source. The engine system is mainly used as a drive source for HEV. The other is an in-vehicle electric system using motor generators 192 and 194 as a power source. The in-vehicle electric system is mainly used as an HEV drive source and an HEV power generation source. The motor generators 192 and 194 are, for example, synchronous machines or induction machines, and operate as both a motor and a generator depending on the operation method.

  A front wheel axle 114 is rotatably supported at the front portion of the vehicle body, and a pair of front wheels 112 are provided at both ends of the front wheel axle 114. A rear wheel axle is rotatably supported at the rear portion of the vehicle body, and a pair of rear wheels are provided at both ends of the rear wheel axle (not shown). In the HEV of the present embodiment, a so-called front wheel drive system is employed, but the reverse, that is, a rear wheel drive system may be employed. A front wheel side differential gear (hereinafter referred to as “front wheel side DEF”) 116 is provided at the center of the front wheel axle 114. The output shaft of the transmission 118 is mechanically connected to the input side of the front wheel side DEF 116. The output side of the motor generator 192 is mechanically connected to the input side of the transmission 118. The output side of the engine 120 and the output side of the motor generator 194 are mechanically connected to the input side of the motor generator 192 via the power distribution mechanism 122.

  Inverter units 140 and 142 are electrically connected to battery 136 via DC connector 138. Electric power can be exchanged between the battery 136 and the inverter units 140 and 142. In the present embodiment, the first motor generator unit including the motor generator 192 and the inverter unit 140 and the second motor generator unit including the motor generator 194 and the inverter unit 142 are provided, and they are selectively used according to the operation state. ing. In this embodiment, the vehicle can be driven only by the power of the motor generator 192 by operating the first motor generator unit as an electric unit by the electric power of the battery 136. Furthermore, in the present embodiment, the battery 136 can be charged by generating power by operating the first motor generator unit or the second motor generator unit as the power generation unit by the power of the engine 120 or the power from the wheels.

The battery 136 is also used as a power source for driving an auxiliary motor 195. The auxiliary machine is, for example, a motor for driving a compressor of an air conditioner or a motor for driving a control hydraulic pump. DC power is supplied from the battery 136 to the inverter unit 43, converted into AC power by the inverter unit 43, and supplied to the motor 195. The inverter unit 43 has the same function as the inverter units 140 and 142, and controls the phase, frequency, and power of alternating current supplied to the motor 195. Since the capacity of the motor 195 is smaller than the capacity of the motor generators 192 and 194, the maximum conversion power of the inverter unit 43 is smaller than that of the inverter units 140 and 142, but the circuit configuration of the inverter unit 43 is basically the circuit of the inverter units 140 and 142. Same as the configuration. The power conversion device 200 includes a capacitor module 500 for smoothing a direct current supplied to the inverter unit 140, the inverter unit 142, and the inverter unit 43.
Next, the electric circuit configuration of the inverter unit 140, the inverter unit 142, or the inverter unit 43 will be described with reference to FIG. In FIG. 2, the inverter unit 140 will be described as a representative example.

The inverter circuit 144 includes an upper and lower arm series circuit 150 that includes an IGBT 328 (insulated gate bipolar transistor) and a diode 156 that operate as an upper arm, and an IGBT 330 and a diode 166 that operate as a lower arm. Three phases (U phase, V phase, W phase) are provided corresponding to each phase winding. Each of the upper and lower arm series circuits 150 is connected to an AC power line (AC bus bar) 186 from the middle point (intermediate electrode 169) to the motor generator 192 through the AC terminal 159 and the AC connector 188.
The collector electrode 153 of the IGBT 328 of the upper arm is connected to the capacitor electrode on the positive side of the capacitor module 500 via the positive terminal (P terminal) 157, and the emitter electrode of the IGBT 330 of the lower arm is connected to the capacitor via the negative terminal (N terminal) 158. The negative electrode side of the module 500 is electrically connected to the capacitor electrode.

  The control unit 170 includes a driver circuit 174 that drives and controls the inverter circuit 144, and a control circuit 172 that supplies a control signal to the driver circuit 174 via the signal line 176. The IGBT 328 and the IGBT 330 operate in response to the drive signal output from the control unit 170, and convert DC power supplied from the battery 136 into three-phase AC power. The converted electric power is supplied to the armature winding of the motor generator 192.

The IGBT 328 includes a collector electrode 153, a signal emitter electrode 155, and a gate electrode 154. The IGBT 330 includes a collector electrode 163, a signal emitter electrode 165, and a gate electrode 164. A diode 156 is electrically connected between the collector electrode 153 and the emitter electrode. A diode 166 is electrically connected between the collector electrode 163 and the emitter electrode. A MOSFET (metal oxide semiconductor field effect transistor) may be used as the switching power semiconductor element, but in this case, the diode 156 and the diode 166 are not necessary. The capacitor module 500 is electrically connected to the positive capacitor terminal 506, the negative capacitor terminal 504, and the DC connector 138. Note that the inverter unit 140 is connected to the positive capacitor terminal 506 via the DC positive terminal 314 and is connected to the negative capacitor terminal 504 via the DC negative terminal 316.
The control circuit 172 includes a microcomputer (hereinafter referred to as “microcomputer”) for calculating the switching timing of the IGBT 328 and the IGBT 330. The microcomputer receives as input information a target torque value required for the motor generator 192, a current value supplied to the armature winding of the motor generator 192 from the upper and lower arm series circuit 150, and a magnetic pole of the rotor of the motor generator 192. The position has been entered. The target torque value is based on a command signal output from a host controller (not shown). The current value is detected based on the detection signal output from the current sensor 180 via the signal line 182. The magnetic pole position is detected based on a detection signal output from a rotating magnetic pole sensor (not shown) provided in the motor generator 192. In the present embodiment, the case where the current values of three phases are detected will be described as an example, but the current values for two phases may be detected.

The microcomputer in the control circuit 172 calculates the d and q axis current command values of the motor generator 192 based on the target torque value, and the calculated d and q axis current command values and the detected d and q The voltage command values for the d and q axes are calculated based on the difference from the current value of the shaft, and the calculated voltage command values for the d and q axes are calculated based on the detected magnetic pole position. Convert to W phase voltage command value. Then, the microcomputer generates a pulse-like modulated wave based on the comparison between the fundamental wave (sine wave) and the carrier wave (triangular wave) based on the voltage command values of the U-phase, V-phase, and W-phase, and the generated modulation The wave is output to the driver circuit 174 via the signal line 176 as a PWM (pulse width modulation) signal.
When driving the lower arm, the driver circuit 174 outputs a drive signal obtained by amplifying the PWM signal to the gate electrode of the corresponding IGBT 330 of the lower arm. Further, when driving the upper arm, the driver circuit 174 amplifies the PWM signal after shifting the level of the reference potential of the PWM signal to the level of the reference potential of the upper arm, and uses this as a drive signal as a corresponding upper arm. Are output to the gate electrodes of the IGBTs 328 respectively.

  In addition, the control unit 170 performs abnormality detection (overcurrent, overvoltage, overtemperature, etc.) to protect the upper and lower arm series circuit 150. For this reason, sensing information is input to the control unit 170. For example, information on the current flowing through the emitter electrodes of the IGBTs 328 and IGBTs 330 is input from the signal emitter electrode 155 and the signal emitter electrode 165 of each arm to the corresponding drive unit (IC). Thereby, each drive part (IC) detects an overcurrent, and when an overcurrent is detected, the switching operation of the corresponding IGBT 328 and IGBT 330 is stopped, and the corresponding IGBT 328 and IGBT 330 are protected from the overcurrent. Information on the temperature of the upper and lower arm series circuit 150 is input to the microcomputer from a temperature sensor (not shown) provided in the upper and lower arm series circuit 150. In addition, voltage information on the DC positive side of the upper and lower arm series circuit 150 is input to the microcomputer. The microcomputer performs over-temperature detection and over-voltage detection based on the information, and stops switching operations of all the IGBTs 328 and IGBTs 330 when an over-temperature or over-voltage is detected.

FIG. 3 is an exploded perspective view for explaining an installation place of the power conversion device 200 according to the present embodiment.
The power conversion apparatus 200 according to the present embodiment is fixed to an aluminum casing 119 for housing the transmission 118. Since the power converter 200 has a substantially rectangular shape on the bottom and top surfaces, it can be easily attached to the vehicle and can be easily produced. The cooling jacket 12 holds a power module 300 and a capacitor module 500, which will be described later, and is cooled by a cooling medium. In addition, the cooling jacket 12 is fixed to the housing 119, and an inlet pipe 13 and an outlet pipe 14 are formed on a surface facing the housing 119. By connecting the inlet pipe 13 and the outlet pipe 14 with the pipe formed in the housing 119, a cooling medium for cooling the transmission 118 flows into and out of the cooling jacket 12.
The case 10 covers the power conversion device 200 and is fixed to the housing 119 side. The bottom of the case 10 is configured to face the control circuit board 20 on which the control circuit 172 is mounted. The case 10 also has a first opening 202 and a second opening 204 that are connected to the outside from the bottom of the case 10 on the bottom surface of the case 10. The connector 21 is connected to the control circuit board 20 and transmits various signals from the outside to the control circuit board 20. Battery negative electrode side connection terminal portion 510 and battery positive electrode side connection terminal portion 512 electrically connect battery 136 and capacitor module 500.
Connector 21, battery negative electrode side connection terminal portion 510 and battery positive electrode side connection terminal portion 512 are extended toward the bottom surface of case 10, connector 21 protrudes from first opening 202, and battery negative electrode side connection terminal portion 510 and The battery positive electrode side connection terminal portion 512 protrudes from the second opening 204. The case 10 is provided with a seal member (not shown) around the first opening 202 and the second opening 204 on the inner wall thereof.
The direction of the mating surface of the terminal of the connector 21 and the like varies depending on the vehicle type. However, especially when trying to mount on a small vehicle, the mating surface is directed upward from the viewpoint of the size restriction in the engine room and the assembling property. It is preferable to take out. In particular, when the power conversion device 200 is disposed above the transmission 118 as in the present embodiment, the workability is improved by projecting toward the opposite side of the transmission 118. In addition, the connector 21 needs to be sealed from the outside atmosphere, but the case 10 is assembled to the connector 21 from above so that when the case 10 is assembled to the housing 119, the case 10 The seal member in contact with 10 can press the connector 21 and the airtightness is improved.

FIG. 4 is a perspective view in which the entire configuration of the power conversion device according to the present embodiment is disassembled into components.
The cooling jacket 12 is provided with a flow path 19. On the upper surface of the flow path 19, openings 400 a to 400 c are formed along the refrigerant flow direction 418, and the openings 402 a to 402 c are in the refrigerant flow direction. 422 is formed. The openings 400a to 400c are closed by the power modules 300a to 300c, and the openings 402a to 402c are closed by the power modules 301a to 301c.
In addition, a storage space 405 for storing the capacitor module 500 is formed in the cooling jacket 12. By storing the capacitor module 500 in the storage space 405, the capacitor module 500 is cooled by the refrigerant flowing in the flow path 19. Since the capacitor module 500 is sandwiched between the flow path 19 for forming the refrigerant flow direction 418 and the flow path 19 for forming the refrigerant flow direction 422, the capacitor module 500 can be efficiently cooled.
A protrusion 407 is formed in the cooling jacket 12 at a position facing the inlet pipe 13 and the outlet pipe 14. The protrusion 407 is formed integrally with the cooling jacket 12. The auxiliary power module 350 is fixed to the protruding portion 407 and is cooled by the refrigerant flowing in the flow path 19. A bus bar module 800 is disposed on the side of the auxiliary power module 350. The bus bar module 800 includes an AC bus bar 186, a current sensor 180, and the like, details of which will be described later.
As described above, the storage space 405 of the capacitor module 500 is provided in the center of the cooling jacket 12, the flow paths 19 are provided so as to sandwich the storage space 405, and the power modules 300a to 300c for driving the vehicle are provided in the flow paths 19, respectively. By disposing the power modules 301a to 301c and further disposing the auxiliary power module 350 on the upper surface of the cooling jacket 12, cooling can be efficiently performed in a small space, and the entire power conversion device can be downsized. Further, by making the main structure of the flow path 19 of the cooling jacket 12 integrally with the cooling jacket 12 by casting an aluminum material, the flow path 19 has the effect of increasing the mechanical strength in addition to the cooling effect. Moreover, the cooling jacket 12 and the flow path 19 become an integral structure by making it by aluminum casting, heat conduction improves, and cooling efficiency improves.
The power modules 300a to 300c and the power modules 301a to 301c are fixed to the flow path 19 to complete the flow path 19, and a water leak test is performed on the water channel. When the water leakage test is passed, the work of attaching the capacitor module 500, the auxiliary power module 350, and the substrate can be performed next. As described above, the cooling jacket 12 is disposed at the bottom of the power conversion device 200, and then the work of fixing necessary components such as the capacitor module 500, the auxiliary power module 350, the bus bar module 800, and the board can be sequentially performed from the top. As a result, productivity and reliability are improved.
The driver circuit board 22 is disposed above the auxiliary power module 350 and the bus bar module 800. The metal base plate 11 is disposed between the driver circuit board 22 and the control circuit board 20. The metal base plate 11 functions as an electromagnetic shield for a circuit group mounted on the driver circuit board 22 and the control circuit board 20, and also releases and cools heat generated by the driver circuit board 22 and the control circuit board 20. Have.
FIG. 5 is a bottom view of the cooling jacket 12 having the flow path 19.
The cooling jacket 12 and the flow path 19 provided inside the cooling jacket 12 are integrally cast. An opening 404 connected to one is formed on the lower surface of the cooling jacket 12. The opening 404 is closed by a lower cover 420 having an opening at the center. A seal member 409a and a seal member 409b are provided between the lower cover 420 and the cooling jacket 12 to maintain airtightness.
In the lower cover 420, an inlet hole 401 for inserting the inlet pipe 13 and an outlet hole 403 for inserting the outlet pipe 14 are formed in the vicinity of one end side and along the side edge. . Further, the lower cover 420 is formed with a convex portion 406 that protrudes in the arrangement direction of the transmission 118. The convex portion 406 is provided for each of the power modules 300a to 300c and the power modules 301a to 301c.
The refrigerant flows through the inlet hole 401 toward the first flow path portion 19 a formed along the short side of the cooling jacket 12 as in the flow direction 417. Then, the refrigerant flows through the second flow path portion 19b formed along the longitudinal side of the cooling jacket 12 as in the flow direction 418. Further, the refrigerant flows through the third flow path portion 19 c formed along the short side of the cooling jacket 12 as in the flow direction 421. The third flow path portion 19c forms a folded flow path. Further, the refrigerant flows through the fourth flow path portion 19d formed along the longitudinal side of the cooling jacket 12 as in the flow direction 422. The fourth flow path portion 19d is provided at a position facing the second flow path portion 19b with the capacitor module 500 interposed therebetween. Further, the refrigerant flows out to the outlet pipe 14 through the fifth flow path portion 19 e and the outlet hole 403 formed along the short side of the cooling jacket 12 as in the flow direction 423.
The first flow path part 19a, the second flow path part 19b, the third flow path part 19c, the fourth flow path part 19d, and the fifth flow path part 19e are all formed larger in the depth direction than in the width direction. The power modules 300a to 300c are inserted from openings 400a to 400c formed on the upper surface side of the cooling jacket 12 (see FIG. 4), and are stored in the storage space in the second flow path portion 19b. An intermediate member 408a is formed between the storage space of the power module 300a and the storage space of the power module 300b so as not to stagnate the refrigerant flow. Similarly, an intermediate member 408b is formed between the storage space of the power module 300b and the storage space of the power module 300c so as not to stagnate the refrigerant flow. The intermediate member 408a and the intermediate member 408b are formed such that their main surfaces are along the flow direction of the refrigerant. Similarly to the second flow path portion 19b, the fourth flow path portion 19d forms a storage space and an intermediate member for the power modules 301a to 301c. Moreover, since the cooling jacket 12 is formed so that the opening 404 and the openings 400a to 400c and 402a to 402c face each other, the cooling jacket 12 is configured to be easily manufactured by aluminum casting.
The lower cover 420 is provided with a support portion 410 a and a support portion 410 b that are in contact with the housing 119 and support the power conversion device 200. The support portion 410 a is provided close to one end side of the lower cover 420, and the support portion 410 b is provided close to the other end side of the lower cover 420. Thereby, power conversion device 200 can be firmly fixed to the side wall of casing 119 formed in accordance with the cylindrical shape of transmission 118 or motor generator 192.
Further, the support portion 410b is configured to support the resistor 450. The resistor 450 is for discharging electric charges charged in the capacitor cell in consideration of occupant protection and safety during maintenance. The resistor 450 is configured to continuously discharge high-voltage electricity. However, in the unlikely event that there is any abnormality in the resistor or discharge mechanism, consideration was given to minimize damage to the vehicle. Must be configured. In other words, when the resistor 450 is arranged around the power module, the capacitor module, the driver circuit board, etc., there is a possibility that the resistor 450 may spread near the main component in the event that the resistor 450 has a problem such as heat generation or ignition. Conceivable.
Therefore, in this embodiment, the power modules 300a to 300c, the power modules 301a to 301c, and the capacitor module 500 are disposed on the opposite side of the casing 119 that houses the transmission 118 with the cooling jacket 12 interposed therebetween, and the resistor 450 Is disposed in a space between the cooling jacket 12 and the housing 119. Accordingly, the resistor 450 is disposed in a closed space surrounded by the cooling jacket 12 and the casing 119 formed of metal. Note that the electric charge stored in the capacitor cell in the capacitor module 500 is a resistor through a wiring passing through the side of the cooling jacket 12 by the switching operation of the switching means mounted on the driver circuit board 22 shown in FIG. The discharge is controlled to 450. In the present embodiment, the switching is controlled so as to discharge at high speed. Since the cooling jacket 12 is provided between the driver circuit board 22 for controlling the discharge and the resistor 450, the driver circuit board 22 can be protected from the resistor 450. In addition, since the resistor 450 is fixed to the lower cover 420, the resistor 450 is provided at a position very close to the flow path 19 thermally, so that abnormal heat generation of the resistor 450 can be suppressed.

A detailed configuration of the power module 300a used in the inverter unit 140 and the inverter unit 142 will be described with reference to FIGS. FIG. 6A is a perspective view of the power module 300a of the present embodiment. FIG. 6B is a cross-sectional view of the power module 300a of the present embodiment.
The power semiconductor elements (IGBT 328, IGBT 330, diode 156, and diode 166) constituting the upper and lower arm series circuit are connected by the conductor plate 315 and the conductor plate 318, or by the conductor plate 316 and the conductor plate 319, as shown in FIGS. It is fixed by being sandwiched from both sides. These conductor plates are assembled with an auxiliary molded body 600 formed by integrally molding signal wirings that are the signal terminals 325U and 325L. The conductor plate 315 and the like are sealed with the first sealing resin 348 with the heat dissipation surface exposed, and the insulating sheet 333 is thermocompression bonded to the heat dissipation surface. The module primary sealing body 302 sealed with the first sealing resin 348 is inserted into the module case 304 and sandwiched with the insulating sheet 333, and is thermocompression bonded to the inner surface of the module case 304 that is a CAN type cooler. The Here, the CAN-type cooler is a cylindrical cooler having an insertion port 306 on one surface and a bottom on the other surface.
The module case 304 is made of an aluminum alloy material such as Al, AlSi, AlSiC, Al—C, and the like, and is integrally formed without a joint. The module case 304 has a structure in which no opening other than the insertion port 306 is provided. The insertion port 306 is surrounded by a flange 304B. Further, as shown in FIG. 6 (a), the first heat radiating surface 307A and the second heat radiating surface 307B, which are wider than the other surfaces, are arranged facing each other, and the opposing first heat radiating surface 307A and The three surfaces connected to the second heat radiating surface 307B constitute a surface sealed with a narrower width than the first heat radiating surface 307A and the second heat radiating surface 307B, and the insertion port 306 is formed on the other side surface. The shape of the module case 304 does not need to be an accurate rectangular parallelepiped, and the corner may form a curved surface as shown in FIG.
By using the metallic case having such a shape, even when the module case 304 is inserted into the flow path 19 through which a coolant such as water or oil flows, a seal against the coolant can be secured by the flange 304B. Can be prevented from entering the inside of the module case 304 with a simple configuration. Further, the fins 305 are uniformly formed on the first heat radiation surface 307A and the second heat radiation surface 307B facing each other. Further, a curved portion 304A having an extremely thin thickness is formed on the outer periphery of the first heat radiating surface 307A and the second heat radiating surface 307B. Since the curved portion 304A is extremely thin to such an extent that it can be easily deformed by pressurizing the fin 305, the productivity after the module primary sealing body 302 is inserted is improved.

The gap remaining inside the module case 304 is filled with the second sealing resin 351. Further, as shown in FIG. 8, a DC positive electrode wiring 315A and a DC negative electrode wiring 319A for electrical connection with the capacitor module 500 are provided, and a DC positive electrode terminal 315B and a DC negative electrode terminal 319B are provided at the tips. Is formed. An AC wiring 320 for supplying AC power to the motor generator 192 or 194 is provided, and an AC terminal 321 is formed at the tip thereof. In the present embodiment, the DC positive electrode wiring 315A is integrally formed with the conductor plate 315, the DC negative electrode wiring 319A is integrally formed with the conductor plate 319, and the AC wiring 320 is integrally formed with the conductor plate 316.
As described above, by thermally pressing the conductor plate 315 or the like to the inner wall of the module case 304 via the insulating sheet 333, the gap between the conductor plate and the inner wall of the module case 304 can be reduced, and the power semiconductor element The generated heat can be efficiently transmitted to the fins 305. Further, by providing the insulating sheet 333 with a certain degree of thickness and flexibility, the generation of thermal stress can be absorbed by the insulating sheet 333, which is favorable for use in a power conversion device for a vehicle having a large temperature change. .

  FIG. 7A is an internal cross-sectional view in which the module case 304, the insulating sheet 333, the first sealing resin 348, and the second sealing resin 351 are removed in order to help understanding. FIG. 7B is an internal perspective view. FIG. 8A is an exploded view for helping understanding of the structure of FIG. FIG. 8B is a circuit diagram of the power semiconductor module 300.

First, the arrangement of the power semiconductor elements (IGBT 328, IGBT 330, diode 156, diode 166) and the conductor plate will be described in association with the electric circuit shown in FIG. As shown in FIG. 7B, the direct current positive electrode side conductor plate 315 and the alternating current output side conductor plate 316 are arranged in substantially the same plane. To the conductor plate 315, the collector electrode of the IGBT 328 on the upper arm side and the cathode electrode of the diode 156 on the upper arm side are fixed. On the conductor plate 316, the collector electrode of the IGBT 330 on the lower arm side and the cathode electrode of the diode 166 on the lower arm side are fixed. Similarly, the AC conductor plate 318 and the conductor plate 319 are arranged in substantially the same plane. On the AC conductor plate 318, the emitter electrode of the IGBT 328 on the upper arm side and the anode electrode of the diode 156 on the upper arm side are fixed. On the conductor plate 319, an emitter electrode of the IGBT 330 on the lower arm side and an anode electrode of the diode 166 on the lower arm side are fixed. Each power semiconductor element is fixed to an element fixing portion 322 provided on each conductor plate via a metal bonding material 160. The metal bonding material 160 is, for example, a low-temperature sintered bonding material including a solder material, a silver sheet, and fine metal particles.
Each power semiconductor element has a flat plate-like structure, and each electrode of the power semiconductor element is formed on the front and back surfaces. As shown in FIG. 7A, each electrode of the power semiconductor element is sandwiched between the conductor plate 315 and the conductor plate 318, or the conductor plate 316 and the conductor plate 319. In other words, the conductor plate 315 and the conductor plate 318 are stacked so as to face each other substantially in parallel via the IGBT 328 and the diode 156. Similarly, the conductor plate 316 and the conductor plate 319 have a stacked arrangement facing each other substantially in parallel via the IGBT 330 and the diode 166. Further, the conductor plate 316 and the conductor plate 318 are connected via an intermediate electrode 329. By this connection, the upper arm circuit and the lower arm circuit are electrically connected to form an upper and lower arm series circuit.

The direct current positive electrode wiring 315A and the direct current negative electrode wiring 319A have a shape extending substantially in parallel with the auxiliary mold body 600 formed of a resin material facing each other. The signal terminal 325U and the signal terminal 325L are formed integrally with the auxiliary mold body 600 and extend in the same direction as the DC positive electrode wiring 315A and the DC negative electrode wiring 319A. As the resin material used for the auxiliary mold body 600, a thermosetting resin having an insulating property or a thermoplastic resin is suitable. As a result, it is possible to ensure insulation between the DC positive electrode wiring 315A, the DC negative electrode wiring 319A, the signal terminal 325U, and the signal terminal 325L, thereby enabling high-density wiring. Furthermore, the direct current positive electrode wiring 315A and the direct current negative electrode wiring 319A are arranged so as to face each other substantially in parallel, so that currents that instantaneously flow during the switching operation of the power semiconductor element face each other in the opposite direction. As a result, the magnetic fields produced by the currents cancel each other out, and this action can reduce the inductance.
FIG. 9 is a diagram illustrating a manufacturing process of the power module 300.

  As shown in FIG. 9A, the conductor plate 315 disposed on the collector side of the IGBT 155 is disposed on the base 370. Then, the metal bonding material 160 such as a solder sheet, the IGBT 155 or the diode 156, the metal bonding material 160, and the conductive plate 318 are arranged on the conductive plate 315 in this order. Next, these are collectively reflowed to be electrically and mechanically connected. At this time, since the conductor plate 318 on the emitter side of the IGBT 155 is not fixed on the base 370, there is a possibility that the conductor plate 315 may be inclined about 100 μm with respect to the parallel plane of the conductor plate 315.

  As shown in FIG. 9B, the auxiliary mold body 600 made of a thermoplastic resin in which the signal terminal 325L is insert-molded is inserted between the DC positive electrode wiring 315A and the DC negative electrode wiring 319A, and the DC positive electrode wiring 315A is inserted. And DC negative electrode wiring 319A are held. The signal terminal 325L and the gate terminal of the IGBT 155 are connected by wire bonding 327.

  As shown in FIG. 9C, a heat conductive sheet 380 is disposed on the upper surface of the conductor plate 318. The heat conductive sheet 380 is processed to be about 3 mm larger than the outer periphery of the upper surface of the conductor plate 318 and has a thickness of about 100 μm. The heat conductive sheet 380 is thermosetting and has high heat conductivity. Further, the heat conductive sheet 380 is supported by the heat resistant sheet 381 on the upper surface side of the heat conductive sheet 380. This heat-resistant sheet 381 has a thickness of about 50 μm and has releasability from the heat conductive sheet 380. Since it is supported by the releasable heat-resistant sheet 381, the handling of the thermosetting high thermal conductive sheet becomes easy and the productivity is improved. Then, the auxiliary mold body 600, the conductor plate 315, the conductor plate 318 and the like are sandwiched by the mold 371, and transfer molded at 175 ° C. for 180 seconds under a molding condition of 10 MPa. At this time, the thermosetting heat conductive sheet 380 flows in the mold 371 and the heat conductive sheet 380 melted between the heat resistant sheet 381 and the conductor plate 318 is filled. That is, the conductor plate 318 side of the heat conductive sheet 380 is deformed according to the inclination of the conductor plate 318, and the mold 371 side of the heat conductive sheet 380 is flattened according to the shape of the mold 371. As a result, the thinnest portion 382 (see FIG. 9c) of the thermosetting heat conductive sheet 380 may be about several μm, or the thickness of the heat conductive sheet 380 becomes 0 μm and the end of the conductor plate 318 May be exposed from the heat conductive sheet 380. However, the end portion of the conductor plate 318 comes into contact with the releasable heat-resistant sheet 381, and there is no problem in manufacturing.

  Further, it was found that the thermosetting heat conductive sheet 380 flows in the mold 371 so that the thickness of the heat conductive sheet 380 becomes 100 μm, so that the inclination of the conductor plate 318 becomes 100 μm. . For this reason, it is possible to use a thin sheet for the heat conductive sheet 380, which is effective in improving heat dissipation.

  In FIG. 9C, the heat conductive sheet 380 is supported by the heat-resistant sheet 381, but the heat-resistant sheet 381 is necessary if the heat-conductive sheet 380 can maintain a certain viscosity or higher under the above molding conditions. Absent. Thus, when the metal mold 371 is clamped on the conductive plate 318 to the heat conductive sheet 380, the thermosetting resin component in the heat conductive sheet 380 is flowed by the temperature transmitted from the metal mold 371, and the mold The space between 371 and the conductive plate 318 is filled, and the heat conductive sheet 380 becomes flat according to the shape of the mold 371.

  Next, as shown in FIG. 9D, the mold 371 is removed, and the heat-resistant sheet 381 having releasability is peeled off with an adhesive tape.

  Next, as shown in FIG. 9E, after the insulating sheet 333 made of an insulating member is disposed on the upper and lower surfaces of the module primary sealing body 302, the module primary sealing body 302 is placed in the module case 304. Inserted into.

  Next, as shown in FIG. 9F, in the vacuum chamber at 140 ° C., the first heat radiating surface 307A of the module case 304 is pressurized to plastically deform the curved portion 304A and the curved portion 304B formed to be thin. Thus, the inner wall of the module case 304 and the insulating sheet 333 are bonded. Further, a second sealing resin for potting is injected into the gap between the module case 304 and the module primary sealing body 302, and is cured by heating.

  The lead frame of the power module 300 showed an inclination of 100 μm, but the exposed surface of the thermosetting high thermal conductive sheet became flat following the transfer mold 371, so a 200 μm insulating sheet was used. An insulation distance of 150 μm could be secured even at the part.

  As shown in FIG. 9C, the auxiliary mold body 600 supports the DC positive electrode wiring 315A and the DC negative electrode wiring 319A, and is in close contact with the mold 371, so that the first sealing material 348 is transferred. It becomes easy to mold and positioning becomes easy.

  Further, as shown in FIG. 9D, a concave portion 383 is formed on the surface of the module primary sealing body 302 on the side where the heat radiation surface of the conductor plate 318 is disposed. The heat dissipation surface of the conductor plate 318 is exposed from the bottom of the recess 383, and the heat dissipation surface of the conductor plate 318 exposed from the bottom is covered with the heat conductive sheet 380. Thereby, even when the conductor plate 318 is inclined, a sufficient insulation distance can be secured.

  Further, as shown in FIG. 9D, the control signal terminal 325L formed in a lead shape has a connection surface with the wire bonding 327 facing the same direction as the surface on which the gate electrode of the IGBT 155 is formed. Placed in. Thereby, the direction of the operation | work which assembles the wire bonding 327 and the direction of the operation | work which arrange | positions the heat conductive sheet 380 and the heat resistant sheet 381 become the same, and assembly workability | operativity improves.

  9D, the heat conductive sheet 380 includes a first portion 384 that faces the heat radiation surface of the conductor plate 318 and a second portion 385 that faces the first sealing material 348. Is done. A mixed portion of the heat conductive sheet 380 and the first sealing material 348 is formed at the interface between the second portion 385 and the first sealing material 348 by heat flow. Thereby, the adhesive force of the 1st sealing material 348 and the heat conductive sheet 380 improves by heat flow.

As shown in FIG. 9F, the module case 304 is configured such that the first heat radiating surface 307A and the second heat radiating surface 307B are integrated. Thereby, the thermal stress applied to the insulating sheet 333 tends to increase. Therefore, it is possible to relieve the thermal stress from the module case 304 by using a soft sheet such as 1-60 (Asker C) as the insulating sheet 333. In addition, since the insulating sheet 333 is desired to be used in a thickness of 50 μm to 300 μm from the insulation distance and thermal stress, the thermal conductivity is 1 W / mK or more, the insulation strength is 10 kV / mm or more, and the volume low efficiency is 10 ¹¹ Ω · cm. The above is desirable.

  Further, when the module case 304 shown in FIG. 9F is made of a conductive metal and a large current is passed through the conductor plate 318, the module case 304 and the conductor plate 318 have a sufficient space. It is necessary to secure an insulation distance. Therefore, the heat conductive sheet 380 can be maintained in a good insulating state by being made of an electrically insulating material. In particular, as in this embodiment, even when a plurality of conductor plates 318 and conductor plates 319 having different potentials are arranged on the same surface, productivity can be improved because they can be covered with a single heat conductive sheet 380.

  In addition, since the conductor plate 318 shown in FIG. 9F is formed thinner than the opposing conductor plate 315, if the current balance or the heat balance becomes unbalanced, the heat conduction sheet 380 It can be made of a conductive material.

  Further, when the conductor plate 318 and the module case 304 shown in FIG. 9F are made of a copper material or an aluminum material, the thermal conductive sheet 380 has a coefficient of thermal expansion of 12 ppm / ° C. or more and 40 ppm / ° C. or less. It is preferable. Thereby, since it is close to the thermal expansion coefficient of a copper material or an aluminum material, temperature cycle reliability can be improved.

  Further, by using a thermosetting material having a thermal glass transition temperature of 150 ° C. or higher for the heat conductive sheet 380 shown in FIG. 9 (f), the glass state having excellent sheet physical properties even near the maximum temperature of the IGBT 155. Therefore, reliability is improved.

  Further, the heat conductive sheet 380 is composed of a thermosetting resin composition having a gel fraction of less than 50% and a heat conductivity of 1 W / mK or more before transfer molding, and The thermosetting resin component is configured to be thermoset until the gel fraction becomes 50% or more by heating. Thereby, after flowing at the time of transfer molding and following the lead frame or the mold 371, there is an effect that the heat conductive sheet 380 can be firmly fixed to the first sealing material 348 or the conductor plate 318 by the progress of the curing reaction.

  In addition, although it is desirable to use the solder mainly composed of tin as the metal joined body 160 of the present embodiment, it is also possible to use a solder mainly composed of gold, silver or copper, a brazing material or a paste. .

  Moreover, it is preferable to use what consists of a thermosetting resin component and a filler component whose heat conductivity is 1 W / mK or more for the thermosetting heat conductive sheet 380 of this embodiment. The thermosetting resin component once flows in a temperature range of 160 ° C. or more and 200 ° C. or less, which is a general transfer mold temperature, and a curing reaction proceeds during a general mold time of 60 seconds to 180 seconds. Thus, it is preferable to use one that does not flow.

  As the filler component, an insulating inorganic filler or a conductive metal filler can be used as long as the thermal conductivity is 1 W / mK or more. Although it can be used in a single layer sheet, a plurality of sheets may be laminated to form a multilayer. When using multiple layers, at least the thickest sheet needs to have a thermal conductivity of 1 W / mK or more.

  In the present embodiment, a plurality of conductor plates 318 and conductor plates 319 are provided in the same plane, but only one arm circuit is mounted in one power module 300, and the emitter of the IGBT 155 is provided. Even if only one conductor plate is provided on each of the side and the collector side, the heat conductive sheet 380 according to this embodiment can be used.

  In order to explain the effect of this embodiment, FIG. 11 shows a cross-sectional view of a power module according to a comparative example. A silicone rubber sheet 390 was used instead of the heat conductive sheet 380 of this embodiment, and the transfer mold was similarly manufactured. In order to absorb the 100 μm inclination of the conductor plate 318 and the conductor plate 319 during transfer molding, a 330 μm silicone rubber sheet 390 was required. Since the silicone rubber sheet 390 is thick, the heat dissipation of the power module deteriorated. Further, the power module was bonded to the metal casing 391 with an adhesive sheet having a thickness of 10 μm, and then the metal casing 391 was sealed with the welding material 392. Since the thermal expansion coefficient of the silicone rubber sheet 390 was as large as 300 ppm / ° C., peeling occurred in the adhesive layer of the adhesive sheet in the temperature cycle, and the withstand voltage was lowered.

  FIG. 10 is a schematic cross-sectional view of the power module 300 according to the present embodiment. The difference from the first embodiment is that a metal sheet 386 is disposed on the upper surface of the heat dissipation sheet 380. Thereby, the handleability of the heat conductive sheet 380 is improved, and not only the productivity can be improved, but also the metal sheet 386 has an effect of improving heat dissipation. Moreover, when the heat conductive sheet 380 has electroconductivity, there exists an effect which can be used for the place where an electrical connection is required.

Claims (16)

A power semiconductor element;
A first conductor plate that forms a connection surface that is connected to one electrode surface of the power semiconductor element via solder, and a surface opposite to the connection surface forms a heat dissipation surface;
A second conductor plate that forms a joint surface that is connected to the other electrode surface of the power semiconductor element via solder, and a surface opposite to the connection surface forms a heat dissipation surface;
A sealing material for sealing the power semiconductor element, the first conductor plate, and the second conductor plate;
A heat dissipation surface of the first conductor plate is exposed from the sealing material;
The heat radiation surface of the second conductor plate is exposed from the sealing material, and the heat radiation surface of the second conductor plate exposed from the sealing material is covered with a thermosetting heat conductive sheet. The power module according to claim 1,
The sealing material forms a recess in the surface on the side where the heat dissipation surface of the second conductor plate is disposed,
The heat dissipation surface of the second conductor plate is exposed from the bottom of the recess of the sealing material, and the heat dissipation surface of the second conductor plate exposed from the bottom of the recess of the sealing material is covered with the heat conductive sheet. Power module. The power module according to claim 1 or 2,
A control conductor for transmitting a gate signal to the gate electrode of the power semiconductor element;
A wire bonding material for electrically connecting the gate electrode and the control conductor;
An emitter electrode is formed on one electrode surface of the power semiconductor element,
A collector electrode and the gate electrode are formed on the other electrode surface of the power semiconductor element,
The control conductor is a power module arranged such that a connection surface with the wire bonding material faces the same direction as a surface on which the gate electrode of the power semiconductor element is formed. The power module according to any one of claims 1 to 3,
A first wiring conductor formed integrally with the first conductor plate and forming a DC terminal at an end; and
A second wiring conductor formed integrally with the second conductor plate and forming a DC terminal at an end;
A power module comprising: an auxiliary sealing material that supports the first wiring conductor and the second wiring conductor and has a melting point different from that of the sealing material. The power module according to claim 1,
The heat conductive sheet is composed of a first portion facing the heat radiation surface of the second conductor plate, and a second portion facing the sealing material,
The power module which forms the mixing part of the said heat conductive sheet and the said sealing material by the heat flow in the interface of the 2nd part of the said heat conductive sheet, and the said sealing material. The power module according to any one of claims 1 to 5,
A first heat dissipating member disposed opposite to the heat dissipating surface of the first conductor plate via a first insulating member;
A second heat dissipating member disposed opposite to the heat dissipating surface of the second conductor plate via a second insulating member,
The second insulating member is a power module that contacts the heat conductive sheet and transmits heat transmitted from the heat conductive sheet to the second heat radiating member. The power module according to claim 6, wherein
A power module case configured to connect the first heat dissipating member and the second heat dissipating member and storing the sealing material;
The first insulating member and the second insulating member are power modules configured of a resin sheet having a predetermined elasticity or more. The power module according to claim 6, wherein
A power module case configured by connecting the first heat radiating member and the second heat radiating member, and housing the sealing material;
A power module comprising a potting resin for sealing a gap between the sealing material and the inner wall of the power module case. The power module according to claim 6, wherein
The second heat radiating member is made of a conductive metal,
The heat conductive sheet is a power module made of an electrically insulating material. The power module according to claim 1 or 6,
The heat conductive sheet is a power module made of a conductive material, and current flows into and out of the second conductive plate. The power module according to any one of claims 1 to 10,
The second conductor plate is made of a copper material or an aluminum material,
The heat conductive sheet is a power module in which a coefficient of thermal expansion of the heat conductive sheet is 12 ppm / ° C. or more and 40 ppm / ° C. or less. The power module according to any one of claims 1 to 11,
The said heat conductive sheet is a power module whose glass transition temperature of the said heat conductive sheet is 150 degreeC or more. The power module according to claim 1,
The thermal conductive sheet is a thermosetting resin composition comprising a thermosetting resin component having a gel fraction of less than 50% and a thermal conductivity of 1 W / mK or more before transfer molding using the sealing material,
The power module in which the thermosetting resin component flows by an increase in temperature in the transfer mold and is thermoset by heating after the flow until the gel fraction reaches 50% or more. A first conductor plate that forms a connection surface that is connected to one of the electrode surfaces of the power semiconductor element via solder, and a surface opposite to the connection surface forms a heat dissipation surface; and the other of the power semiconductor element A second conductor plate that forms a joint surface that is connected to the electrode surface via solder, and a surface opposite to the connection surface forms a heat dissipation surface; the power semiconductor element; the first conductor plate; A sealing material for sealing two conductor plates, and a manufacturing method of a power module comprising:
A first step in which a thermosetting heat conductive sheet is disposed between the mold used for the transfer mold and the heat radiation surface of the second conductor plate exposed from the sealing material;
When the sealing material is transfer molded, the mold clamps the heat conductive sheet and the second conductive plate, and the thermosetting resin composition in the heat conductive sheet is transmitted from the mold. A second step of filling a space between the mold and the second conductor plate by flowing according to temperature;
And a third step in which the curing reaction of the heat conductive sheet proceeds with the progress of the curing reaction of the sealing material. It is a manufacturing method of the power module according to claim 14,
The first step is to fix the heat conductive sheet by disposing a heat-resistant sheet disposed between the heat conductive sheet and the mold and having releasability on an upper surface of the heat conductive sheet. Including
The method for producing a power module, wherein the heat-resistant sheet is peeled off by an adhesive tape after the third step. It is a manufacturing method of the power module according to claim 14,
The first step includes fixing a heat conductive sheet by disposing a metal sheet disposed between the heat conductive sheet and the mold on an upper surface of the heat conductive sheet. Production method.

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