JP6344981B2 - Manufacturing method of semiconductor module - Google Patents

Description

  The present invention relates to a semiconductor module, a method for manufacturing a semiconductor module, and an electronic control device.

  In recent years, electric vehicles such as electric vehicles and hybrid vehicles have been rapidly developed in order to promote energy saving and realize a low-carbon society. In particular, the role of the inverter, which is a basic component of the electrification system, is diversified more than ever, and it is required to simultaneously realize downsizing and high output. The inverter is mounted with a power semiconductor module in which a power semiconductor chip such as a transistor or a diode is sealed with resin as its main component. Power semiconductor modules for electric vehicles and hybrid vehicles generate heat by energization as the current capacity of devices increases and current density increases due to miniaturization, so cooling means are provided to suppress the temperature rise of power semiconductor modules. .

  A water cooling system is known as a cooling system for semiconductor devices such as power semiconductor modules (see Patent Document 1). Patent Document 1 describes that a space defined by a side surface of a semiconductor device and an inner wall of a case constitutes a flow path of a coolant for cooling the semiconductor device, and the semiconductor device is immersed in the coolant. Has been. Patent Document 1 describes that a metal film that covers the surface of a semiconductor device is formed by plating, soldering, or the like, thereby improving heat dissipation and waterproofing against a coolant.

JP 2004-119667 A

  In a semiconductor module, a heat radiating member such as a metal heat radiating plate or a heat radiating fin is exposed from a sealing resin and brought into contact with a refrigerant to improve heat radiating efficiency. As a method for manufacturing a semiconductor module, there is a transfer mold method. In the transfer molding method, a substrate on which a semiconductor element or the like is mounted is fixed in a preheated mold, and the mold resin is injected into the mold while being melted and sealed. However, since the heat dissipating member and the sealing resin are different materials, an extremely slight gap may occur at the boundary surface between the sealing resin and the heat dissipating member after molding.

  If there is a gap on the boundary surface, there is a problem that even if the plating process is performed, the metal film cannot be formed so as to cover the gap, and the refrigerant enters from this gap.

According to a first aspect of the present invention, there is provided a semiconductor module manufacturing method comprising: a semiconductor element; a conductor member to which the semiconductor element is bonded; a heat radiating member provided in the semiconductor element so as to be thermally conductive; A semiconductor structure made of different materials and including a sealing material that seals the semiconductor element by exposing one surface of the heat radiating member is prepared, and at least the heat radiating member and the sealing material in the contact region of the coolant A coating layer covering the boundary is formed by applying a coating solution having an inorganic element ratio of 2% by weight or less, and a waterproof layer made of a material different from the coating layer is formed on the surface of the coating layer.

  According to the present invention, the waterproof effect can be improved.

The figure which shows the control block of a hybrid vehicle. The figure explaining the structure of the electric circuit of an inverter circuit. The perspective view of a semiconductor module. The cross-sectional schematic diagram of the semiconductor module cut | disconnected by the IVa-IVa line | wire of Fig.3 (a). The circuit diagram which shows the circuit structure of a semiconductor module. The perspective view of the conductor board assembly which removed the sealing resin of the semiconductor module. The perspective view of the conductor board assembly which removed the 1st conductor board and the 3rd conductor board of FIG. The flowchart which shows the manufacture procedure of a semiconductor module. Explanatory drawing explaining the coating film formed with a coating solution. Explanatory drawing explaining formation of a coating layer. (A) is a partial cross-sectional schematic diagram showing the state after molding of the sealing resin, (b) is a partial cross-sectional schematic showing a comparative example in which a waterproof layer is provided directly on the surface of the semiconductor structure without providing a coating layer. Figure. The partial cross section schematic diagram which shows this Embodiment which provided the coating layer and the waterproof layer. The perspective view of the semiconductor module which concerns on 2nd Embodiment. The cross-sectional schematic diagram of the semiconductor module which concerns on 2nd Embodiment. The cross-sectional schematic diagram of the semiconductor module which concerns on 3rd Embodiment. The cross-sectional schematic diagram of the semiconductor module which concerns on 4th Embodiment. FIG. 10 is a partial enlarged schematic view of a semiconductor module according to Modification 1.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
-First embodiment-
FIG. 1 is a diagram showing a control block of a hybrid vehicle. Engine EGN and motor generator MG1 generate vehicle running torque. Motor generator MG1 not only generates rotational torque but also has a function of converting mechanical energy applied from the outside to motor generator MG1 into electric power.

  Motor generator MG1 is, for example, a synchronous machine or an induction machine, and operates as a motor or a generator depending on the operation method as described above. When motor generator MG1 is mounted on an automobile, it is desirable to obtain a small and high output, and a permanent magnet type synchronous motor using a magnet such as neodymium is suitable. The permanent magnet type synchronous motor generates less heat from the rotor than the induction motor, and is excellent for automobiles from this viewpoint.

  The output torque of the engine EGN is transmitted to the motor generator MG1 via the power distribution mechanism TSM, and the rotational torque from the power distribution mechanism TSM or the rotational torque generated by the motor generator MG1 is transmitted to the wheels via the transmission TM and the differential gear DIF. Communicated. On the other hand, during regenerative braking operation, rotational torque is transmitted from the wheels to motor generator MG1, and AC power is generated based on the supplied rotational torque. The generated AC power is converted to DC power by the power conversion device 200 as described later, and the high-voltage battery 136 is charged, and the charged power is used again as travel energy.

  Next, a power conversion device 200 that converts electric power from DC to AC and from AC to DC by switching operation of the semiconductor element will be described. The inverter circuit 140 is electrically connected to the battery 136 via the DC connector 138, and power is exchanged between the battery 136 and the inverter circuit 140. When motor generator MG1 is operated as a motor, inverter circuit 140 generates AC power based on DC power supplied from battery 136 via DC connector 138 and supplies it to motor generator MG1 via AC terminal 188. . The configuration including motor generator MG1 and inverter circuit 140 operates as a motor generator unit.

  In the present embodiment, the vehicle can be driven only by the power of motor generator MG1 by operating the motor generator unit as an electric unit by the electric power of battery 136. Furthermore, in this embodiment, the battery 136 can be charged by operating the motor power generation unit as the power generation unit by the power of the engine EGN or the power from the wheels to generate power.

  The power conversion device 200 includes a capacitor module 500 for smoothing DC power supplied to the inverter circuit 140.

  The power conversion device 200 includes a communication connector 21 for receiving a command from a host control device or transmitting data representing a state to the host control device. Power conversion device 200 calculates a control amount of motor generator MG1 by control circuit 172 based on a command from connector 21, further calculates whether to operate as a motor or a generator, and controls based on the calculation result. A pulse is generated and the control pulse is supplied to the driver circuit 174. The driver circuit 174 generates a driving pulse for controlling the inverter circuit 140 based on the supplied control pulse.

  Next, the configuration of the electric circuit of the inverter circuit 140 will be described with reference to FIG. In the present embodiment, an insulated gate bipolar transistor is used as a semiconductor element, and is hereinafter abbreviated as IGBT.

  The upper arm IGBT 328 and the diode 156, and the lower arm IGBT 330 and the diode 166 constitute a series circuit 150 of the upper and lower arms. The inverter circuit 140 includes the series circuit 150 corresponding to three phases of the U phase, the V phase, and the W phase of the AC power to be output.

  In this embodiment, these three phases correspond to the three-phase windings of the armature winding of motor generator MG1. The series circuit 150 of the upper and lower arms of each of the three phases outputs an alternating current from the intermediate electrode 169 that is the midpoint portion of the series circuit. Intermediate electrode 169 is connected to AC bus bar 802 which is an AC power line to motor generator MG1 through AC terminal 159 and AC terminal 188.

  The collector electrode of the IGBT 328 of the upper arm is electrically connected to the capacitor terminal 506 on the positive electrode side of the capacitor module 500 via the DC positive electrode terminal 157. The emitter electrode of the IGBT 330 on the lower arm is electrically connected to the capacitor terminal 504 on the negative electrode side of the capacitor module 500 via the DC negative electrode terminal 158.

  As described above, the control circuit 172 receives a control command from the host control device via the connector 21, and based on this, the IGBT 328 that configures the upper arm or the lower arm of each phase series circuit 150 that constitutes the inverter circuit 140. And a control pulse that is a control signal for controlling the IGBT 330 is generated and supplied to the driver circuit 174.

  Based on the control pulse, the driver circuit 174 supplies a drive pulse for controlling the IGBT 328 and IGBT 330 constituting the upper arm or the lower arm of each phase series circuit 150 to the IGBT 328 and IGBT 330 of each phase. IGBT 328 and IGBT 330 perform conduction or cutoff operation based on the drive pulse from driver circuit 174, convert DC power supplied from battery 136 into three-phase AC power, and supply the converted power to motor generator MG1. Is done.

  The upper arm IGBT 328 and the lower arm IGBT 330 each include a collector electrode, a signal emitter electrode, and a gate electrode. An upper arm diode 156 is electrically connected between the collector electrode terminal 153 and the emitter electrode terminal 155. A diode 166 is electrically connected between the collector electrode terminal 163 and the emitter electrode terminal 165.

  As the switching power semiconductor element, a metal oxide semiconductor field effect transistor (hereinafter abbreviated as MOSFET) may be used. In this case, the diode 156 and the diode 166 are unnecessary. As a power semiconductor element for switching, IGBT is suitable when the DC voltage is relatively high, and MOSFET is suitable when the DC voltage is relatively low.

  The capacitor module 500 includes a capacitor terminal 506 on the positive electrode side, a capacitor terminal 504 on the negative electrode side, a power supply terminal 509 on the positive electrode side, and a power supply terminal 508 on the negative electrode side. The high-voltage DC power from the battery 136 is supplied to the positive-side power terminal 509 and the negative-side power terminal 508 via the DC connector 138, and the positive-side capacitor terminal 506 and the negative-side capacitor of the capacitor module 500. The voltage is supplied from the terminal 504 to the inverter circuit 140.

  On the other hand, the DC power converted from the AC power by the inverter circuit 140 is supplied to the capacitor module 500 from the positive capacitor terminal 506 and the negative capacitor terminal 504, and is connected to the positive power terminal 509 and the negative power terminal 508. Is supplied to the battery 136 via the DC connector 138 and accumulated in the battery 136.

  The control circuit 172 includes a microcomputer (hereinafter referred to as “microcomputer”) for performing arithmetic processing on switching timings of the IGBT 328 and the IGBT 330. The input information to the microcomputer includes a target torque value required for the motor generator MG1, a current value supplied from the series circuit 150 to the motor generator MG1, and a magnetic pole position of the rotor of the motor generator MG1.

  The target torque value is based on a command signal output from a host controller (not shown). The current value is detected based on a detection signal from the current sensor 180. The magnetic pole position is detected based on a detection signal output from a rotating magnetic pole sensor (not shown) such as a resolver provided in the motor generator MG1. In the present embodiment, the current sensor 180 detects the current value of the three phases as an example, but the current value for the two phases may be detected and the current for the three phases may be obtained by calculation. .

  The microcomputer in the control circuit 172 calculates the d-axis and q-axis current command values of the motor generator MG1 based on the target torque value, the calculated d-axis and q-axis current command values, and the detected d The voltage command values for the d-axis and the q-axis are calculated based on the difference between the current values of the axes and the q-axis, and the calculated voltage command values for the d-axis and the q-axis are calculated based on the detected magnetic pole position. It is converted into voltage command values for phase, V phase, and W phase. Then, the microcomputer generates a pulse-like modulated wave based on a 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 wave The wave is output to the driver circuit 174 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.

  Information on the temperature of the series circuit 150 is input to the microcomputer from a temperature sensor (not shown) provided in the series circuit 150. In addition, voltage information on the DC positive side of the series circuit 150 is input to the microcomputer. The microcomputer performs overtemperature detection and overvoltage detection based on the information, and stops switching operations of all the IGBTs 328 and IGBTs 330 when an overtemperature or overvoltage is detected.

  The configuration of the semiconductor modules 300a to 300c used in the inverter circuit 140 will be described with reference to FIGS. Since the semiconductor modules 300a to 300c (see FIG. 2) have the same structure, the structure of the semiconductor module 300a (hereinafter referred to as the semiconductor module 300A) will be described as a representative.

  FIG. 3 is a perspective view of the semiconductor module 300A. FIG. 4 is a schematic cross-sectional view of the semiconductor module 300A, which is a schematic cross-sectional view taken along line IVa-IVa in FIG. In addition, in FIG. 4, the code | symbol of the structural member represented in the cross section cut | disconnected by the IVb-IVb line is also appended. FIG. 5 is a circuit diagram showing a circuit configuration of the semiconductor module 300A. FIG. 6 is a perspective view of the conductor plate assembly 950 from which the sealing resin 348 of the semiconductor module 300A has been removed to facilitate understanding. FIG. 7 is a perspective view of the conductor plate assembly 950 from which the first conductor plate 315 and the third conductor plate 320 of FIG. 6 are removed.

  As shown in FIG. 4, the semiconductor module 300A includes power semiconductor elements (IGBT 328, IGBT 330, diode 156, and diode 166) that constitute the series circuit 150 shown in FIGS. 2 and 5, and these power semiconductor elements are It is sealed with a sealing resin 348 made of resin.

  The circuit configuration of the semiconductor module will be described with reference to FIG. As shown in FIG. 5, 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 connected via a first conductor plate 315. Similarly, 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 connected via the third conductor plate 320. 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 connected via the second conductor plate 318. Similarly, the emitter electrode of the IGBT 330 on the lower arm side and the anode electrode of the diode 166 on the lower arm side are connected via a fourth conductor plate 319. The second conductor plate 318 and the third conductor plate 320 are connected by an intermediate electrode 329. With such a circuit configuration, a series circuit 150 of upper and lower arms is formed.

  As shown in FIGS. 4 and 7, the power semiconductor elements (IGBT 328, IGBT 330, diode 156, diode 166) have a plate-like flat structure, and each electrode of the power semiconductor element is formed on the front and back surfaces.

  As shown in FIG. 4 and FIG. 6, each electrode of the power semiconductor element has a first conductor plate 315 and a second conductor plate 318, or a third conductor plate 320 and a fourth conductor, which are arranged to face the respective electrode surfaces. It is sandwiched between the conductor plates 319. That is, the first conductor plate 315 and the second conductor plate 318 are stacked so as to face each other substantially in parallel via the IGBT 328 and the diode 156. Similarly, the third conductor plate 320 and the fourth conductor plate 319 have a stacked arrangement facing each other substantially in parallel via the IGBT 330 and the diode 166. As shown in FIG. 6, the third conductor plate 320 and the second 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 first conductive plate 315 on the direct current side and the third conductive plate 320 on the alternating current side are arranged in substantially the same plane. To the first 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 third conductor plate 320, 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 second conductor plate 318 on the AC side and the fourth conductor plate 319 on the DC side are arranged in substantially the same plane. 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 to the second conductor plate 318. On the fourth 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.

  A DC positive terminal 157 extends from the first conductor plate 315, an AC terminal 159 extends from the second conductor plate 318, and a DC negative terminal 158 extends from the fourth conductor plate 319.

Each of the conductor plates 315, 318, 319, and 320 according to the present embodiment is a wiring for a large current circuit, and is made of a material having high thermal conductivity and low electrical resistance such as pure copper or copper alloy, and has a thickness of 0. .5 mm or more is preferable.

  As shown in FIG. 4, each power semiconductor element is bonded to each conductor plate 315, 318, 319, 320 via a metal bonding material 160. The metal bonding material 160 is, for example, a low-temperature sintered bonding material containing a silver sheet or fine metal particles, or lead-free solder having a high thermal conductivity and excellent environmental properties, such as Sn—Cu solder, Sn—Ag. -Cu solder, Sn-Ag-Cu-Bi solder and the like.

  The gate electrode terminals 154 and 164 and the emitter electrode terminals 155 and 165 for connection to the driver circuit 174 are connected to the gate electrode and the emitter electrode of the power semiconductor element by wire bonding, ribbon bonding or the like. It is preferable to use aluminum or gold for the wire or ribbon. Instead of wires or ribbons, connection may be made using solder or the like. The gate electrode terminals 154 and 164 and the emitter electrode terminals 155 and 165 are preferably made of pure copper or a copper alloy. The DC positive terminal 157, the DC negative terminal 158 and the AC terminal 159, the gate electrode terminals 154 and 164, the emitter electrode terminals 155 and 165, the current detection terminal, the temperature detection terminal, etc. are arranged in a line. These are connected by a tie bar 951 made of an insulating resin or the like at a predetermined interval and are integrally held.

  As shown in FIGS. 4 and 6, the semiconductor module 300 </ b> A is provided with heat radiation fins 371. As shown in FIG. 4, the radiation fin 371 includes a fin plate 371a and a reinforcing plate 371b that increases the rigidity of the fin plate 371a. The fin plate 371a has a rectangular flat base and a plurality of columnar fins protruding from one surface of the base. The reinforcing plate 371b has a rectangular flat plate shape, and the outer shape of the reinforcing plate 371b is substantially the same as the outer shape of the base portion of the fin plate 371a. The base portion of the fin plate 371a and the reinforcing plate 371b are positioned and joined so that the outer peripheral side surface of the base portion of the fin plate 371a and the outer peripheral side surface of the reinforcing plate 371b are flush with each other.

  The semiconductor module 300 </ b> A is disposed in the case 122, and the heat radiating fins 371 exchange heat with the refrigerant 121 in the case 122, and radiate heat generated in the semiconductor module to the refrigerant 121. The refrigerant 121 flows in a direction orthogonal to the fins and circulates in the case 122 by a circulation device (not shown).

  An insulating plate 389 having an insulating property is bonded to the outer surfaces of the second conductor plate 318 and the fourth conductor plate 319 (the surface opposite to the bonding surface of the semiconductor element), and the reinforcing plate 371b is connected to the outer surface of the insulating plate 389. Are joined, and the fin plate 371a is joined to the exposed surface of the reinforcing plate 371b after transfer molding, which will be described later. That is, the surface of the fin plate 371a where the fins are formed is exposed from the sealing resin 348. The insulating plate 389 is made of an inorganic compound such as insulating ceramics or an organic compound such as insulating resin, and is disposed between the heat radiation fins 371 and the conductor plates 318 and 319 to insulate them. The material of the insulating plate 389 is preferably selected to have a high thermal conductivity. In the case where the insulating plate 389 is formed of resin, it is preferable that the insulating plate 389 is connected to the conductor plates 318 and 319 and the reinforcing plate 371b in a state before the resin component is completely cured, that is, in a state having adhesiveness. Note that the insulating plate 389 can be omitted when the reinforcing plate 371b and the fin plate 371a constituting the heat radiation fin 371 are formed of an insulating material.

  The reinforcing plate 371b and the fin plate 371a are made of a metal material having a higher thermal conductivity than a material used for the sealing resin 348, such as aluminum, copper, or magnesium, or a ceramic material such as alumina. As the material of the reinforcing plate 371b, it is preferable to select a material having higher rigidity than the material of the fin plate 371a. In the present embodiment, different materials are selected for the reinforcing plate 371b and the fin plate 371a.

  The second conductor plate 318 or the fourth conductor plate 319, the insulating plate 389, the reinforcing plate 371b, and the fin plate 371a are joined by welding, soldering, friction stir welding (FSW: Friction Stir Welding) or the like. If the strength of the fin plate 371a is sufficient, the reinforcing plate 371b can be omitted.

  As described above, the second conductor plate 318 and the fourth conductor plate 319 are coupled to the heat radiating fins 371 through the insulating plate 389 so as to be able to conduct heat. The heat generated in the semiconductor elements 156, 166, 328, and 330 is transmitted to the second conductor plate 318 or the fourth conductor plate 319, is transmitted to the radiation fins 371 through the insulating plate 389, and the coating layer 601 described later from the radiation fins 371. The heat is radiated to the refrigerant 121 through the waterproof layer 602.

  The semiconductor structure 302 is formed by molding the conductor plate assembly 950 with an insulating sealing resin 348 by a transfer molding method or the like. In the transfer molding method, a conductive plate assembly 950 is fixed in a preheated mold, and a power semiconductor is formed by injecting pressure into the mold while melting a thermosetting resin such as an epoxy resin. The conductor plate assembly 950 including the elements is sealed with a sealing resin 348 to form a semiconductor structure (module sealing body) 302. When performing transfer molding, the outer surface of the reinforcing plate 371b (the surface opposite to the joint surface with the insulating plate 389) is exposed from the sealing resin 348. As shown in FIGS. 3 and 4, the sealing resin 348 has a terminal surface 348 a on which the terminals 157, 158, 159, 154, 155, 164, 165 are arranged in a state of being insulated from each other. .

  When the conductor plate assembly 950 is molded as described above, a very slight gap (dent) may be formed at the boundary between the sealing resin 348 and the conductor plate assembly 950 on the surface of the semiconductor structure 302. The gaps (dents) are often in the range of 1 to 500 μm in width and 1 to 500 μm in depth, and may be elongated along the boundary surface in the depth direction. When a gap is generated at the boundary surface, there arises a problem that the refrigerant enters from the gap.

  Therefore, in the present embodiment, the coating layer 601 that covers the gap and the waterproof layer 602 that is formed on the surface of the coating layer 601 are formed on the outer surface of the semiconductor structure 302. The region where the coating layer 601 is formed is a region including the entire contact region of the coolant 121 in the semiconductor structure 302.

  A method for manufacturing the semiconductor module 300A according to the first embodiment will be described. FIG. 8 is a flowchart showing a manufacturing procedure of the semiconductor module 300A. As shown in FIG. 8A, the semiconductor module 300A includes a preparation step S100 for preparing the semiconductor structure 302, a covering layer forming step S110 for forming the covering layer 601, and a waterproof layer forming step S120 for forming the waterproof layer 602. It is made after.

A method for forming the covering layer 601 and the waterproof layer 602 will be described in detail.
-Coating layer formation process-
As shown in FIG. 8B, the coating layer forming step S110 includes a coating solution preparation step S112, an immersion step S115, and a heat curing step S118.

-Coating solution preparation process S112-
A coating solution prepared by diluting and adjusting a commercially available polyamideimide at 6% by weight with N-methyl-2-pyrrolidone so that the viscosity becomes 0.3 Pa · s is prepared.

-Immersion step S115-
After covering portions other than the coating area, for example, the terminal surface 348a and each terminal in the vicinity of the terminal surface with a curing member (not shown) such as a curing tape, a curing sheet, and a curing jig, a semiconductor structure is formed by dipping. The body 302 is immersed in the coating solution and coated. At this time, the amount of the coating solution and the height of immersion are adjusted so that the terminal surface 348a is not immersed.

-Heat curing step S118-
After the dip coating, the solvent (N-methyl-2-pyrrolidone) is removed by heating at 100 ° C. and 170 ° C. for 1 hour, respectively, and the resin (polyamideimide) is cured. The coating layer 601 to be formed is formed.

  FIG. 9 is an explanatory diagram for explaining the coating film F formed by the coating solution L. For convenience of explanation, an example in which the coating film F is formed in a horizontal state with the opening surface of the depression S0 facing upward is shown. ing. A depression S0 is formed on the surface of the sealing resin 348 due to voids generated during molding. As shown in FIG. 9A, when the semiconductor structure 302 is immersed in the coating solution L with the terminal side facing up, and then the semiconductor structure 302 is pulled up, as shown in FIG. The coating solution L flows down from the ceiling surface (upper surface) of the film, and the thickness of the coating film F adhering to the bottom surface (lower surface) becomes thicker than the ceiling surface of the depression S0.

  If the viscosity of the coating solution L is less than 0.1 Pa · s, the coating solution L applied to the depression S0 flows down, and a part of the inner surface of the depression S0 is exposed. On the other hand, when the viscosity of the coating solution L exceeds 100 Pa · s, the coating solution L cannot be put into the depression S0, and the embedding effect is lost. For this reason, it is preferable that the viscosity of the coating solution L is 0.1 Pa · s or more and 100 Pa · s or less.

  FIG. 10 is an explanatory diagram for explaining the formation of the coating layer 601. As shown in FIG. 10A, a coating film F is formed with the coating solution L (see FIG. 9), and the depression S0 is covered with the coating film F. Then, the coating layer F 601 is formed by heating and curing the coating film F for a predetermined time, as shown in FIG.

Here, when the thickness of the coating film F is Y and the resin content is C wt%, the thickness of the coating layer 601 is C · Y, and the thickness of the coating layer 601 in the depression S0 is C · (Y + Z0). When the depth of the depression S0 is Z0, the depth Z1 of the depression S1 of the coating layer 601 is expressed by the following formula (1).
Z1 = Z0 + C · Y-C (Y + Z0)
= Z0 + C ・ Y-C ・ Y-C ・ Z0
= Z0-C · Z0
= Z0 (1-C) (1)

  The coating solution L can be composed of various components, but as represented by the formula (1), the greater the resin content C, the higher the effect of filling the depression S0. In the case of less than 5% by weight, since the effect of filling the depression S0 is small, the resin content C is desirably 5% by weight or more and 100% by weight or less. Thus, since the effect of reducing the height of the dent is obtained by the coating layer 601, the coating layer 601 functions as a planarization layer that flattens the surface of the sealing resin 348.

-Waterproof layer formation process-
As shown in FIG. 8C, the waterproof layer forming step S120 includes an electroless copper plating step S122 and an electroless nickel plating step S125.
-Electroless copper plating step S122-
A 0.5 μm-thick copper film is formed as a base film by electroless copper plating.
-Electroless nickel plating process S125-
A nickel film having a thickness of 20 μm is formed on the base film by electroless nickel plating, and a waterproof layer 602 made of a copper film and a nickel film is formed as shown in the enlarged view of part A in FIG. Although the base film can be omitted, it is preferable to form the base film because the base film can improve adhesion with the coating layer 601 made of an organic compound. After the formation of the waterproof layer 602, the curing member is removed to complete the semiconductor module 300A.

  In addition, when the thickness of the waterproof layer 602 exceeds 500 μm, it takes time for the plating process, and the manufacture becomes difficult. Therefore, the thickness of the waterproof layer 602 is preferably 500 μm or less.

According to the first embodiment described above, the following operational effects are obtained.
(1) The semiconductor module 300A can conduct heat through the semiconductor elements 328, 330, 156, and 166, the conductor plates 318 and 319 to which the semiconductor elements are joined, and the semiconductor elements through the conductor plates 318 and 319 and the insulating plate 389. The semiconductor structure 302 including the heat radiation fin 371 fixed to the heat radiation fin 371 and the sealing resin 348 that is made of a different material from the heat radiation fin 371 and exposes one surface of the heat radiation fin 371 to seal the semiconductor element, and at least the refrigerant 121. The coating layer 601 that covers the boundary between the heat radiation fin 371 and the sealing resin 348 in the contact area of the contact layer 601 and a waterproof layer 602 that is made of a material different from the coating layer 601 and is formed on the surface of the coating layer 601.
By forming the covering layer 601, a gap (dent) formed along the boundary between the sealing resin 348 and the heat radiation fin 371 is covered.
By forming the waterproof layer 602, the refrigerant 121 can be prevented from entering the sealing resin 348, so that the life of the semiconductor module 300A can be extended.

  FIG. 11A is a partial cross-sectional schematic view showing a state after molding of the sealing resin 348, and FIG. 11B directly waterproofs the surface of the semiconductor structure 302 without providing the covering layer 601. FIG. 6 is a partial cross-sectional schematic diagram showing an example in which a layer 602 is provided (hereinafter referred to as a comparative example). FIG. 12 is a partial cross-sectional schematic diagram showing this embodiment in which a covering layer 601 and a waterproof layer 602 are provided. FIGS. 11A, 11B, and 12 schematically show a cross section of a portion corresponding to the portion A of FIG.

  As shown in FIG. 11A, after molding of the sealing resin 348, an extremely slight gap G is formed on the boundary surface between the sealing resin 348 and the reinforcing plate 371 b of the radiating fin 371 due to thermal contraction of the sealing resin 348. May occur. As shown in FIG. 11 (b), in the comparative example, the covering layer 601 is not formed, and the waterproof layer is composed of a 0.5 μm copper film and a 20 μm nickel film by electroless copper plating and electroless nickel plating. 602 is formed. However, in the comparative example, as shown in FIG. 11B, the gap G is not sufficiently covered, and the refrigerant 121 enters along the boundary surface between the radiating fin 371 and the sealing resin 348, and the leakage current of the semiconductor element is reduced. The verification result that it increased and cannot start normally was obtained. Even if the gap G is covered with a waterproof layer 602 formed by plating, it is difficult to ensure waterproofness for a long period of time because stress tends to concentrate at the boundary between different members.

  On the other hand, in this embodiment, as shown in FIG. 12, the covering layer 601 is covered with the covering layer 601 so as to fill the gap (dent) G, and the waterproof layer 602 is formed on the surface of the covering layer 601. Therefore, the infiltration of the refrigerant 121 can be prevented, and the semiconductor module 300A can be normally operated over a long period of time. Since the coating layer 601 that fills the depressions S0 and G existing on the surface is provided, the adhesiveness of the waterproof layer 602 is improved and the reliability is improved as compared with the comparative example.

(2) After the molding of the sealing resin 348, a void due to a void occurs on the surface of the sealing resin 348. In the present embodiment, the covering layer 601 is formed on the entire contact area of the refrigerant 121 including the boundary between the heat radiation fin 371 and the sealing resin 348, and the waterproof layer 602 is formed on the surface of the covering layer 601. Yes. Accordingly, direct contact of the coolant 121 with the sealing resin 348 can be prevented over the entire contact area of the coolant 121, and the life of the semiconductor module 300A can be extended.

(3) Since the coating layer 601 is formed of an organic compound, a depression of several μm to several hundred μm can be covered. For this reason, even if there are variations in the width (depth) of the gaps (dents) formed at the boundary between the radiation fins 371 and the sealing resin 348 and the widths and depths of the plurality of depressions formed on the surface of the sealing resin 348, Can be covered with a covering layer 601.

(4) Since the waterproof layer 602 is made of metal, the refrigerant 121 can be blocked and the refrigerant 121 can be prevented from coming into direct contact with the coating layer 601.

In this way, by adopting a multilayer structure (laminated structure) of the covering layer 601 and the waterproof layer 602, even if the depressions S0 and G that are not intended at the time of molding are formed, the intrusion of the refrigerant 121 is blocked, and the semiconductor chip or Water absorption around an element such as a chip component can be prevented, and deterioration in insulation performance such as an increase in leakage current of a semiconductor chip due to water absorption and a decrease in insulation resistance due to migration between a plurality of elements can be prevented.
This is because when the coating is formed on the surface composed of a plurality of different members, the adhesion is different for each member, so that the coating layer 601 is formed at the boundary between different members. This is because the surface becomes a single material and the waterproof layer 602 can be uniformly adhered. Thereby, it is possible to provide the highly reliable semiconductor module 300A and the power conversion device 200 that operate normally over a long period of time.

-Second Embodiment-
A semiconductor module 300B according to the second embodiment will be described with reference to FIG. 13 and FIG. FIG. 13 is a perspective view of the semiconductor module 300B according to the second embodiment, which is the same diagram as FIG. FIG. 14 is a view similar to FIG. 4 and is a schematic cross-sectional view of a semiconductor module 300B according to the second embodiment. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, differences from the first embodiment will be described in detail.

  In the first embodiment, the example in which the radiating fins 371 are provided only on one surface of the semiconductor module 300A has been described. However, in the second embodiment, the radiating fins 371 are provided on both surfaces of the semiconductor module 300B. Is provided.

  As shown in FIG. 14, an insulating plate 389 having insulating properties is joined to the outer surfaces of the first conductor plate 315 and the third conductor plate 320, and a reinforcing plate 371b is joined to the outer surface of the insulating plate 389. After molding, the fin plate 371a is joined to the exposed surface of the reinforcing plate 371b. The insulating plate 389 is made of an inorganic compound such as insulating ceramics or an organic compound such as insulating resin, and is disposed between the heat radiation fins 371 and the conductor plates 315 and 320 to insulate them. The material of the insulating plate 389 is preferably selected to have a high thermal conductivity. In the case where the insulating plate 389 is formed of resin, it is preferable that the insulating plate 389 is connected to the conductor plates 315 and 320 and the reinforcing plate 371b in a state before the resin component is completely cured, that is, in a state having adhesiveness. Note that the insulating plate 389 can be omitted when the reinforcing plate 371b and the fin plate 371a constituting the heat radiation fin 371 are formed of an insulating material.

  The reinforcing plate 371b and the fin plate 371a are made of a metal material having a higher thermal conductivity than a material used for the sealing resin 348, such as aluminum, copper, or magnesium, or a ceramic material such as alumina. As the material of the reinforcing plate 371b, it is preferable to select a material having higher rigidity than the material of the fin plate 371a.

  The first conductor plate 315 or the third conductor plate 320, the insulating plate 389, the reinforcing plate 371b, and the fin plate 371a are joined by welding, soldering, friction stir welding, or the like. If the strength of the fin plate 371a is sufficient, the reinforcing plate 371b can be omitted.

  According to such 2nd Embodiment, there exists an effect similar to 1st Embodiment. In addition, since the heat radiation area of the radiation fin 371 is increased as compared with the first embodiment, the cooling performance can be improved as compared with the first embodiment.

-Third embodiment-
A semiconductor module 300C according to the third embodiment will be described with reference to FIG. FIG. 15 is a view similar to FIG. 4 and is a schematic cross-sectional view of a semiconductor module 300C according to the third embodiment. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, differences from the first embodiment will be described in detail.

  In the first embodiment, each terminal is arranged on one terminal surface 348a. However, in the third embodiment, a surface opposite to the one terminal surface 348a (hereinafter, another terminal surface 348b). There are also terminals. In the third embodiment, a DC negative terminal 158, a DC positive terminal 157 and an AC terminal 159, gate electrode terminals 154 and 164, and emitter electrode terminals 155 and 165 shown in FIG. 5 extend from one terminal surface 348a. The current detection terminal 190 extends from the other terminal surface 348b.

  In the third embodiment, as shown in FIG. 15, since the two terminal surfaces 348a and 348b are exposed, that is, the covering layer 601 and the waterproof layer 602 are formed on the two terminal surfaces 348a and 348b. Therefore, the area where the covering layer 601 and the waterproof layer 602 are not formed is increased as compared with the first embodiment. In the third embodiment, the two terminal surfaces 348a and 348b and the terminals are covered with a curing member, and the coating layer 601 is formed with a coating solution. Thereafter, the waterproof layer 602 is formed, and the curing member is removed.

  According to such 3rd Embodiment, there can exist an effect similar to 1st Embodiment. Since the area where the covering layer 601 and the waterproof layer 602 are formed is smaller than that in the first embodiment, the weight and cost can be reduced as compared with the first embodiment.

-Fourth embodiment-
A semiconductor module 300D according to the fourth embodiment will be described with reference to FIG. FIG. 16 is a view similar to FIG. 4 and is a schematic cross-sectional view of a semiconductor module 300D according to the fourth embodiment. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, differences from the first embodiment will be described in detail.

  In the first embodiment, the covering layer 601 and the waterproof layer 602 are formed over the entire contact area of the coolant 121 in the semiconductor structure 302. In the fourth embodiment, the peripheral edge portion of the heat dissipating fins 371 is used. Except for the above, the covering layer 601 and the waterproof layer 602 are not formed on the radiation fin 371.

  In the fourth embodiment, in the coating layer forming step, the coating layer 601 is formed by immersing the coating film 601 in a state where the surface of the radiation fin 371 is covered with a curing member. Thereafter, the waterproof layer 602 is formed, and the curing member is removed. In the fourth embodiment, a coating layer 601 and a waterproof layer 602 are formed on the peripheral portion of the fin plate 371 a, that is, on the radiation fin 371 in the vicinity of the boundary between the radiation fin 371 and the sealing resin 348.

  In the fourth embodiment, the covering layer 601 and the waterproof layer 602 are formed over the entire contact area of the refrigerant 121 in the sealing resin 348, but the covering layer 601 and the waterproof layer 602 are formed on the heat radiation fin 371. Is exposed. For this reason, in addition to the effect similar to 1st Embodiment, since the heat radiation fin 371 can be directly contacted with a refrigerant | coolant and heat exchange can be performed, there exists an effect that the heat dissipation effect can be heightened more. Further, the weight and cost can be reduced as compared with the first embodiment. Similarly, in the second embodiment and the third embodiment, a configuration in which the radiating fins 371 are in contact with the refrigerant can be employed.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
(Modification 1)
The positional relationship among the fin plate 371a, the reinforcing plate 371b, and the insulating plate 389 is not limited to the above-described embodiment. For example, as shown in FIG. 17A, the outer shape of the reinforcing plate 371b may be made slightly larger than the outer shape of the fin plate 371a. In the above-described embodiment, at the boundary between the sealing resin 348 and the reinforcing plate 371b, a portion where four constituent members made of four different materials of the sealing resin 348, the reinforcing plate 371b, the fin plate 371a, and the covering layer 601 intersect. (Refer to the enlarged view of part A in FIG. 4). On the other hand, in this modification, the size of the reinforcing plate 371b is made larger than that of the fin plate 371a, so that the sealing resin 348 and the reinforcing plate at the boundary (B1 portion) between the sealing resin 348 and the reinforcing plate 371b. It can be a portion where three different members 371b and the covering layer 601 intersect. Thereby, compared with the first embodiment in which four different members intersect, stress concentration at the intersection (B1 portion) can be relaxed.

(Modification 2)
The present invention is not limited to the case where the fin plate 371a, the reinforcing plate 371b, and the insulating plate 389 are made of different materials. For example, as shown in FIG. 17B, by forming the reinforcing plate 371b and the fin plate 371a with the same material, there are three different members at the boundary (B1 portion) between the sealing resin 348 and the reinforcing plate 371b. Will be crossed. For this reason, compared with the structure where four different members cross, stress concentration can be eased. In addition, as shown in FIG.17 (c), when the reinforcement board 371b is abbreviate | omitted, the stress concentration in B1 part can be relieved similarly.

(Modification 3)
In the above-described embodiment, the example in which the coating layer 601 is formed from polyamideimide has been described. However, the present invention is not limited to this. Instead of polyamide imide, the coating layer 601 can be formed of various thermosetting resins such as polyimide, polyimidazole, phenol resin, epoxy resin, and melamine resin. The coating solution is composed of at least a solvent and a resin component. In addition, you may mix | blend an inorganic filler. In view of forming the waterproof layer 602 from a metal, it is preferable to select a material having excellent chemical resistance and heat resistance.

  For example, a methyl ethyl ketone solution having a viscosity of 30 Pa · s with 20 wt% epoxy resin is prepared, and then the surface of the semiconductor structure 302 is coated using this coating solution. The coating layer 601 is formed by heat-curing at 150 ° C. for 1 hour.

(Modification 4)
In the above-described embodiment, the example in which the coating layer 601 is formed by the dipping method immersed in the coating solution has been described, but the present invention is not limited to this. The method of applying the coating solution is not limited to immersion, and the coating layer 601 may be formed by applying the coating solution to the semiconductor structure 302 by spraying or brushing. Dip (dipping), spraying, brushing, or combinations thereof can also be used. If the embeddability is insufficient, it can be improved by overcoating.

(Modification 5)
In the above-described embodiment, the example in which N-methyl-2-pyrrolidone is employed as the solvent has been described, but the present invention is not limited to this. Various solvents excellent in compatibility with the resin constituting the coating layer 601 at room temperature can be employed. For example, polar solvents such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, diethylene glycol dimethyl ether, and methyl ethyl ketone can be used.

(Modification 6)
In the above-described embodiment, an example in which the coating layer 601 is formed using an organic compound has been described, but the present invention is not limited to this. The covering layer 601 may be formed of an inorganic compound. When the widths and depths of the recesses S0 and G are small, the coating layer 601 can be formed without waste by forming the thin coating layer 601 with an inorganic compound. For example, the coating layer 601 can be formed of an inorganic compound such as silicon oxide, titanium oxide, or zirconium oxide. These are thermally cured using tetraethoxysilane, tetrabutoxytitanium, zirconium (IV) propoxide, or the like to form an oxide film. Since heating to the boiling point of the solvent used is sufficient for thermosetting, it can be formed without damaging the semiconductor chip or the sealing resin 348 unlike the glass coating.

  The solvent is selected according to the inorganic compound. For example, alcohol solvents such as ethanol, propanol, butanol, hexanol, pentanol, toluene, xylene, cyclohexansan, and the like can be selected as the solvent. Acetic acid may be added to obtain the stability of the diluted solution.

  When the coating layer 601 is formed of an inorganic compound, if the ratio of the inorganic element to the coating solution exceeds 2% by weight, self-condensation starts in a few seconds to several hours and solidifies, resulting in poor workability. For this reason, it is preferable that an inorganic element ratio shall be 2 weight% or less with respect to the whole coating solution. When the inorganic element ratio is 2% by weight or less with respect to the entire coating solution, no chemical change occurs and the coating solution can be used as a stable coating solution. In addition, as a coating layer formation method with an inorganic compound, dipping (dipping), spraying, brushing, or a combination thereof can be used. If the embeddability is insufficient, it can be improved by overcoating.

  As an example of forming the coating layer 601 with an inorganic compound, an ethanol solution of 1 wt% tetraethoxysilane is prepared, and then the coating solution is sprayed onto the semiconductor structure 302 by spraying to form a coating film. A silicon oxide film is formed by heat curing at 100 ° C. for 1 hour. By repeating this process about two or three times, the covering layer 601 is formed to cover the depressions S0 and G.

  As another example of forming the coating layer 601 with an inorganic compound, a toluene solution of 1% by weight tetrabutoxytitanium is prepared, and then the semiconductor structure 302 is immersed in this coating solution (dip method) to form a coating film. . After the dip coating, the coating is cured by heating at 80 ° C. and 120 ° C. for 1 hour to form a titanium oxide film. By repeating this process about two or three times, the covering layer 601 is formed to cover the depressions S0 and G.

(Modification 7)
In the above-described embodiment, the example in which the coating layer 601 is formed from a nonmetal has been described, but the present invention is not limited to this. The covering layer 601 may be formed of a metal such as chromium, titanium, copper, and alloys thereof. The coating layer (metal film) made of metal can be formed by sputtering, vapor deposition, electroless plating, or the like. The metal film not only has a function of covering the recesses S0 and G so as to fill the recesses S0 and G, but also has a function of improving adhesion to the waterproof layer 602 made of metal.

  As an example of forming the coating layer 601 with a metal, a chromium film having a thickness of 0.1 μm was formed as a base film by a sputtering method, and then a copper film having a thickness of 1 μm was formed. Sputtering is performed on each surface of the semiconductor structure 302 that forms the coating layer 601, for example, so that the distance from the target metal is constant and a uniform metal film can be obtained.

(Modification 8)
In the above-described embodiment, the example in which the nickel film is formed on the copper film (underlying film) and the waterproof layer 602 including the copper film and the nickel film is formed has been described, but the present invention is not limited to this. Without forming the base film, electroless nickel plating may be applied to form the waterproof layer 602 using only the nickel film. The material is not limited to copper (Cu) or nickel (Ni), but includes tin (Sn), zinc (Zn), and an alloy containing copper, nickel, tin, and zinc (for example, nickel phosphorus (Ni-P) alloy) , Nickel boron (Ni-B) alloy, nickel phosphorus boron (Ni-P-B) multi-component alloy) can be used. Nickel is particularly excellent in corrosion resistance, and copper is particularly excellent in thermal conductivity. Therefore, it is preferable to select according to the application.

(Modification 9)
In the embodiment described above, the example in which the waterproof layer 602 is formed by electroless plating has been described, but the present invention is not limited to this. The waterproof layer 602 may be formed by electroplating or a combination of electroless plating and electroplating. This is because electroless plating and electroplating are not only suitable for mass production, but also cause less damage to the semiconductor structure 302 than methods such as cold spraying and thermal spraying.

(Modification 10)
In the above-described embodiment, the example in which the covering layer 601 and the waterproof layer 602 are formed in the entire contact region of the coolant 121 in the sealing resin 348 has been described, but the present invention is not limited to this. The covering layer 601 is provided so as to cover at least the boundary between the sealing resin 348 and the heat radiation fin 371, and the waterproof layer 602 may be provided so as to cover the covering layer 601.

(Modification 11)
In the above-described embodiment, the example in which the radiating fins 371 and the insulating plate 389 are configured as heat transfer members that transmit the heat of the conductor plates 318, 319, 315, and 320 has been described, but the present invention is not limited thereto. . Instead of the insulating plate 389, a sheet-like insulating sheet may be provided. As described above, the reinforcing plate 371b of the radiating fin 371 may be formed of an insulating material and the insulating plate 389 may be omitted. The fin shape of the heat radiation fin 371 is not limited to a cylindrical shape, and various fin shapes can be employed. Furthermore, instead of the heat radiating fins 371, a flat heat radiating plate having no fins may be employed.

(Modification 12)
In the above-described embodiment, the power conversion device (inverter) has been described as an example of the electronic control device, but the present invention is not limited to this. The present invention can be applied to various electronic control devices including a semiconductor module.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

21 connector, 121 refrigerant, 122 case, 136 battery, 138 DC connector, 140 inverter circuit, 150 series circuit, 153 collector electrode terminal, 154 gate electrode terminal, 155 emitter electrode terminal, 156 diode, 157 DC positive terminal, 158 DC negative Terminal, 159 AC terminal, 160 Metal bonding material, 163 Collector electrode terminal, 165 Emitter electrode terminal, 166 Diode, 169 Intermediate electrode, 172 Control circuit, 174 Driver circuit, 180 Current sensor, 188 AC terminal, 190 Current detection terminal, 200 Power converter, 300A, 300B, 300C, 300D semiconductor module, 302 semiconductor structure, 315 first conductor plate, 318 second conductor plate, 319 fourth conductor plate, 320 third conductor plate, 329 Interelectrode, 348 Sealing resin, 348a, 348b Terminal surface, 371 Radiation fin, 371a Fin plate, 371b Reinforcement plate, 389 Insulation plate, 500 Capacitor module, 504 Capacitor terminal, 506 Capacitor terminal, 508 Power terminal, 509 Power terminal, 601 Cover layer, 602 waterproof layer, 802 AC bus bar, 950 conductor plate assembly, 951 tie bar

Claims (2)

The semiconductor element, a conductor member to which the semiconductor element is bonded, a heat dissipating member provided in the semiconductor element so as to be capable of heat conduction, and the heat dissipating member are made of different materials, and exposes one surface of the heat dissipating member. Preparing a semiconductor structure including a sealing material for sealing a semiconductor element;
Forming a coating layer covering at least the boundary between the heat dissipation member and the sealing material in the contact area of the refrigerant by applying a coating solution having an inorganic element ratio of 2 wt% or less ;
A method for manufacturing a semiconductor module, comprising forming a waterproof layer made of a material different from the coating layer on a surface of the coating layer. In the manufacturing method of the semiconductor module of Claim 1 ,
A method for manufacturing a semiconductor module, wherein the coating layer is formed over the entire contact area of the coolant in the sealing material when the coating layer is formed.

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