Patent Application
20250105110
The present invention relates to a semiconductor device and a power conversion device.
A power conversion device that employs semiconductor element switching affords high conversion efficiency, and thus is widely used for consumer use, in-vehicle use, railway use, transformer facilities, and the like. Such power conversion devices include a semiconductor device. A semiconductor device includes a semiconductor element, a conductor plate to which the semiconductor element is joined, and an insulation sheet which is bonded to the surface of the conductor plate on the opposite side from the semiconductor element side. These components are sealed by means of a resin member. In particular, in vehicle-mounted applications, a semiconductor device is required to have high reliability.
PTL 1 discloses an electric circuit body in which a sheet-like member (insulation sheet) having a resin insulation layer, a conductor plate, and a semiconductor element are covered with a sealing resin by means of transfer molding.
The semiconductor device disclosed in PTL 1 is faced with the problem of the insulation properties provided by the insulation sheet.
A semiconductor device of the present invention includes: a plurality of semiconductor elements; a conductor plate to which the plurality of semiconductor elements are joined; an insulation sheet which is bonded to the face of the conductor plate on the opposite side from the side of the plurality of semiconductor elements; and a resin member that seals the plurality of semiconductor elements, the insulation sheet, and the conductor plate, wherein the conductor plate includes a plurality of element joining regions to which each of the plurality of semiconductor elements is joined, and a connection region provided between the plurality of element joining regions, wherein the insulation sheet-side surface of the conductor plate in the element joining regions protrudes from the insulation sheet-side surface of the connection region and is bonded to the insulation sheet, and wherein the resin member is added between the insulation sheet and the insulation sheet-side surface of the conductor plate in the connection region.
According to the present invention, it is possible to provide a highly reliable semiconductor device having enhanced insulation properties afforded by an insulation sheet.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the descriptions and drawings hereinbelow are examples to illustrate the present invention, and omissions and simplifications are made, as appropriate, to clarify the invention. The present invention can also be carried out in various other modes. Unless otherwise specified, each constituent element may be singular or plural.
In order to facilitate understanding of the invention, the position, size, shape, range, and the like of each constituent element illustrated in the drawings may not represent the actual position, size, shape, range, and the like. Therefore, the present invention is not necessarily limited to or by the position, size, shape, range, and the like disclosed in the drawings.
The electric circuit body 400 includes three semiconductor devices 300 and a cooling member 340 for cooling the semiconductor devices 300.
The semiconductor device 300 includes components the details of which will be provided further below, namely, a semiconductor element, a conductor plate to which the semiconductor element is joined, and an insulation sheet which is bonded to the surface of the conductor plate on the opposite side from the semiconductor element side. These components are sealed by means of a resin member 360. The semiconductor device 300 mutually converts DC power and AC power using a semiconductor element. Because the semiconductor device 300 generates heat by energization of the semiconductor element, the semiconductor device is cooled by the cooling member 340. Refrigerant flows inside the cooling member 340, and water, antifreeze liquid obtained by mixing ethylene glycol with water, or the like, is used as the refrigerant.
The semiconductor device 300 includes power terminals through which a large current flows, such as a positive electrode-side terminal 315B and a negative electrode-side terminal 319B connected to a capacitor module 500 (see
As first power semiconductor elements 155 and 156 forming the upper arm circuit, an active element 155 and a diode 156 are provided. Si, SiC, GaN, GaO, C, or the like can be used as the active element 155. In a case where the body diode of the active element 155 is used, the separate diode may be omitted. The collector side of the first power semiconductor elements 155 and 156 is joined to a second conductor plate 431. For this joining, solder or sintered metal may be used. A first conductor plate 430 is joined to the emitter side of the first power semiconductor elements 155 and 156. As second power semiconductor elements 157 and 158 forming the lower arm circuit, an active element 157 and a diode 158 are provided. The collector side of the second power semiconductor elements 157 and 158 is joined to a fourth conductor plate 433. A third conductor plate 432 is joined to the emitter side of the second power semiconductor elements 157 and 158.
The conductor plates 430, 431, 432, and 433 are not particularly limited as long as they are made of a material having high electrical conductivity and thermal conductivity, but a copper-based or aluminum-based material is desirable. These materials may be used alone, but may be plated with Ni, Ag, or the like in order to improve bondability to solder or to a sintered metal.
In addition to the role of passing current, the conductor plates 430, 431, 432, and 433 fulfill the role of heat transfer members for transferring heat generated by the power semiconductor elements 155, 156, 157, and 158 to the cooling member 340. Because the conductor plates 430, 431, 432, and 433 and the cooling member 340 have different potentials, insulation sheets 440 and 441 are arranged therebetween. A heat conduction member 453 is disposed between the insulation sheets 440 and 441 and the cooling member 340 in order to reduce contact thermal resistance. The power semiconductor elements 155, 156, 157, and 158, the conductor plates 430, 431, 432, and 433, and the insulation sheets 440 and 441 are sealed with the resin member 360 by means of transfer molding.
The insulation sheet 440 has a laminated structure of a resin insulation layer 442 and a metal foil 444, and the insulation sheet 441 has a laminated structure of a resin insulation layer 443 and the metal foil 444. However, the insulation sheets 440 and 441 may be the resin insulation layers 442 and 443 alone, respectively. In a case where the insulation sheets 440 and 441 have a laminated structure of the resin insulation layers 442 and 443 and the metal foil 444, the metal foil 444 is disposed on the side in contact with the heat conduction member 453. The resin insulation layers 442 and 443 of the insulation sheets 440 and 441 are not particularly limited as long as they have adhesiveness with the conductor plates 430, 431, 432, and 433, but epoxy resin-based resin insulation layers 442 and 443 in which a powdery inorganic filler is dispersed are desirable. This is because the balance between adhesiveness and heat dissipation is good. In the transfer molding process, when the insulation sheets 440 and 441 are mounted on a mold, a metal foil 444 is provided on a contact surface between the insulation sheets 440 and 441 and the mold in order to prevent adhesion to the mold. In a case where a release sheet is used to prevent adhesion to the mold, a step of peeling off the release sheet after transfer molding is required because the release sheet has poor thermal conductivity, but in the case of the metal foil 444, the step of peeling off the release sheet after transfer molding is rendered unnecessary by selecting a copper-based or aluminum-based metal having high thermal conductivity. By performing transfer molding including the insulation sheets 440 and 441, the end portions of the insulation sheets 440 and 441 are covered with the resin member 360, and thus there is the advantageous effect of improving reliability.
As illustrated in
The projection 461 adheres to the insulation sheet 440 in a close contact region 464. In the connection region 463, a resin filling space 460 is formed between the insulation sheet 440 and the first conductor plate 430. The resin filling space 460 is filled with a resin member 360 in a transfer molding process to be described below, and is connected to the resin member 360 that seals the power semiconductor elements 155, 156, 157, and 158, the insulation sheet 440, and the conductor plates 430, 431, 432, and 433. Because the resin insulation layer 442 of the insulation sheet 440 and the resin member 360 are simultaneously cured in the transfer molding process, the resin components of the resin insulation layer 442 and the resin member 360 penetrate each other and have high adherence in comparison with a case where the resin insulation layer 442 and the resin member 360 are bonded to each other after curing. The resin filling space 460 desirably has a thickness of 300 μm or more enabling sufficient filling with the resin member 360. From the viewpoint of insulating properties, the thickness of the resin insulation layer 442 of the insulation sheet 440 is preferably greater.
The conductor plates 430, 431, 432, and 433 are desirably made of a material having high electrical conductivity and high thermal conductivity, and it is also possible to use a metal-based material such as copper or aluminum, or a composite material of a metal-based material and highly thermally conductive diamond, carbon, ceramic, or the like. The connection region 463 of the conductor plates 430, 431, 432, and 433 is produced by, for example, a recess formed by press working, cutting by machining or laser machining, or a connection of a low rigidity member.
The cooling member 340 is desirably made of a highly thermally conductive and lightweight aluminum. The cooling member 340 is prepared by extrusion molding, forging, brazing, or the like.
The heat conduction member 453 is not particularly limited as long as they is made of a material having high thermal conductivity, but it is preferable to use a high thermal conduction material such as a metal, a ceramic, or a carbon-based material in combination with a resin material. This is because a resin material compensates between a high thermal conductivity material and a high thermal conductivity material, between a high thermal conductivity and the cooling member 340, and between a highly thermally conductive member and the insulation sheets 440 and 441, and thus the contact thermal resistance is reduced.
The projection 461 of the conductor plate 430 adheres to the insulation sheet 440 in the close contact region 464. Further, the resin filling space 460 is formed between the insulation sheet 440 and the first conductor plate 430, and the resin filling space 460 is filled with the resin member 360.
As shown in
In addition, a conductor plate (upper arm circuit emitter side) 430 and a conductor plate (upper arm circuit collector side) 431 are arranged above and below the active element 155 and the diode 156 of the power semiconductor element (upper arm circuit). A conductor plate (lower arm circuit emitter side) 432 and a conductor plate (lower arm circuit collector side) 433 are arranged above and below the active element 157 and the diode 158 of the power semiconductor element (lower arm circuit).
The semiconductor device 300 according to the present embodiment has a 2 in 1 structure in which two arm circuits, namely, an upper arm circuit and a lower arm circuit, are integrated into one module. In addition, a structure in which a plurality of upper arm circuits and lower arm circuits are integrated into one module may be used. In this case, the number of output terminals from the semiconductor device 300 can be reduced and downsized.
As shown in
Thereafter, as shown in
The resin insulation layer 442 of the insulation sheet 440 is filled with a large number of fillers (not illustrated) in a resin component such as an epoxy resin in order to afford high thermal conductivity. Therefore, as shown in
In addition, as illustrated in
When the resin member 360 is injected in the transfer molding process, the molding pressure acts in all directions as a hydrostatic pressure while the resin member 360 is in a liquid state. Among the hydrostatic pressures, a force acting upward in
The insulation sheet 440 is filled with a large number of fillers (not illustrated) in a resin component such as an epoxy resin in order to provide high thermal conductivity. Therefore, as shown in
Meanwhile, on the outside of the 45-degree line M, the voids 465 in the resin insulation layer 442 remain without being compressed. In this comparative example, because the resin filling space 460 is not provided, the close contact region 464 is also further outside the 45-degree line M than the element joining region 462. For this reason, immediately above the close contact region 464 having high electric field strength, there is a region in which voids are not compressed, and thus the insulation properties are then low. In addition, as illustrated in
When the resin member 360 is injected in the transfer molding process, the molding pressure acts in all directions as a hydrostatic pressure while the resin member 360 is in a liquid state. Among the hydrostatic pressures, a force acting upward in
As illustrated in
In a case where a power conversion device 200 is configured using the semiconductor device 300′, the power conversion device 200 may be required to have a higher output corresponding to a large current or a higher function such as failure diagnosis. However, because there is a limit to the current with which the power semiconductor elements 155 and 157 can be energized, it is effective to use the power semiconductor elements 155 and 157 in multi-parallel as illustrated in
In addition, a gate resistor is required for the gate wiring in order to apply the charge required to drive the gates of the power semiconductor elements 155 and 157. Such a gate drive circuit is usually provided with a wiring substrate outside the semiconductor device and mounted on the wiring substrate, but in a case where the power semiconductor elements 155 and 157 are used in multi-parallel, it is desirable to provide a gate resistor for each element in order to prevent a malfunction. For this reason, the wiring substrate 372 on which the gate resistor is mounted as a chip resistor is built into the semiconductor device 300′. In a case where such a wiring substrate 372 is mounted, the total surface area of the close contact region between the conductor plates 430 and 431 and the insulation sheets 440 and 441 is greater than the total surface area of the element joining region 462 of the power semiconductor elements 155 and 157, and the pressure applied to the close contact region between the conductor plates 430 and 431 and the insulation sheets 440 and 441 is significantly reduced. Therefore, providing the resin filling space 460 described above is effective in reducing the total surface area of the close contact region to improve the insulation properties.
In
The projection 461 adheres to the insulation sheet 440 in the close contact region 464. In the connection region 463, a resin filling space 460 is formed between the insulation sheet 440 and the first conductor plate 430, and the resin filling space 460 is filled with the resin member 360 in the transfer molding process.
Similarly to the conductor plate 430 on the emitter side, the conductor plate 441 on the collector side is also formed having the projection 461 and the resin filling space 460. Because the resin filling space 460 is also provided on the collector side, the terminal is clamped, in the metal mold clamping of the transfer molding process, by the metal mold clamp, and thus there is no design restriction in pressing the conductor plate on the collector side against the insulation sheet 441, thereby improving the degree of design freedom.
In a case where the glass transition temperatures at and γt are lower than Tmold, the resin members α and γ shown in
The principle behind forming the protrusions 466 on the insulation sheets 440 and 441 on the projections 461 and in the resin filling spaces 460 will be described with reference to
The resin member 360 is cured and shrunk by the progress of the curing reaction after the resin member 360 is injected into the transfer mold. The curing shrinkage amount varies depending on the composition of the resin member 360. The curing shrinkage amount varies depending on the ratio of the epoxy resin component that undergoes a curing reaction and the ratio of the other filler that does not undergo a curing reaction, and the greater the ratio of the epoxy resin component, the greater the curing shrinkage amount. Even when the ratio of the epoxy resin component is the same, the greater the ratio of the epoxy group as a reactive component in the epoxy resin component, the greater the curing shrinkage amount. The semiconductor device 300′ extracted from the metal mold of the transfer mold is cooled to room temperature. In a case where the glass transition temperature is lower than Tmold, shrinkage occurs at a high shrinkage ratio up to the glass transition temperature, and when the glass transition temperature is lower than the glass transition temperature, shrinkage occurs at a shrinkage ratio lower than the glass transition temperature. In a case where the glass transition temperature is higher than Tmold, shrinkage occurs at a constant shrinkage ratio. T1 is the minimum value of the usage environment temperature of the semiconductor device 300′, T2 is the maximum value of the usage environment temperature, where T1 is −40° C. and T2 is 125° C., for example. In this temperature range, in a case where the amount of shrinkage is greater than Cu, that is, in a case where the amount of shrinkage of the resin member 360 falls within the hatched region H, the resin member 360 shrinks more than Cu in the operating temperature range, and thus protrusions 466 are formed on the insulation sheets 440 and 441. In the modification of the present embodiment, by using the resin members β and γ illustrated in
By providing the protrusions 466 on the insulation sheets 440 and 441, the projection 461 serving as a main heat dissipating portion easily abuts on the cooling member 340 via the heat conduction member 453 and the insulation sheets 440 and 441, and the cooling performance can be improved. Furthermore, because the protrusions 466 are provided, the heat conduction member 453 can be thickened locally in the region where the protrusions 466 are formed, and in the case of using the adhesion-type heat conduction member 453, the stress can be reduced and the adhesion can be maintained for a long period of time, thus affording the advantageous effect of improving reliability. In addition, in a case where a non-adhesive-type heat conduction member 453 is to be used, the protrusions 466 hold the heat conduction member 453 and suppress the reduction in heat resistance caused by pump-out, thus affording the advantageous effect of improving reliability.
The power conversion device 200 includes inverter circuits 140 and 142, an auxiliary inverter circuit 43, and a capacitor module 500. The inverter circuits 140 and 142 include a plurality of semiconductor devices 300 and 300′, and a three-phase bridge circuit is configured by connecting the plurality of semiconductor devices 300 and 300′. In a case where the current capacity is large, the semiconductor devices 300 and 300′ are further connected in parallel, and the parallel connection is performed corresponding to each phase of the three-phase inverter circuit, thus making it possible to handle an increase in current capacity. In addition, by connecting in parallel the active elements 155 and 157 and the diodes 156 and 158, which are power semiconductor elements built into the semiconductor devices 300 and 300′, it is also possible to handle an increase in current capacity.
The inverter circuit 140 and the inverter circuit 142 have the same basic circuit configuration, and basically the same control method and operation. Because an outline of the circuit operation of the inverter circuit 140 and the like is well known, a detailed description thereof will be omitted here.
The upper arm circuits of the inverter circuits 140 and 142 include an upper-arm active element 155 and an upper-arm diode 156 as power semiconductor elements for switching, and the lower arm circuit includes a lower-arm active element 157 and a lower-arm diode 158 as power semiconductor elements for switching. The active elements 155 and 157 perform switching operations in response to a drive signal outputted from one or the other of the two driver circuits constituting the driver circuit 174, and convert the DC power supplied from the battery 136 into three-phase AC power.
The active element 155 of the upper arm circuit and the active element 157 of the lower arm circuit include a collector electrode, an emitter electrode, and a gate electrode. The diode 156 of the upper arm circuit and the diode 158 of the lower arm circuit include two electrodes, namely, a cathode electrode and an anode electrode. As shown in
Note that a metal oxide semiconductor field effect transistor (MOSFET) may be used as the active element, and in this case, the diode 156 for the upper arm and the diode 158 for the lower arm are unnecessary.
The positive electrode-side terminal 315B and the negative electrode-side terminal 319B of each of the upper and lower arm series circuits are connected to a capacitor-connection DC terminal of the capacitor module 500. AC power is generated in each of the connecting parts of the upper arm circuit and the lower arm circuit, and the connecting parts are connected to the AC-side terminals 320B of the semiconductor devices 300 and 300′. The AC-side terminals 320B of the semiconductor devices 300 and 300′ of the respective phases are connected to the AC output terminals of the power conversion device 200, and the generated AC power is supplied to the stator winding of the motor generator 192 or 194.
The control circuit 172 generates a timing signal for controlling switching timing of the upper-arm active element 155 and the lower-arm active element 157 on the basis of input information from a control device, a sensor (for example, a current sensor 180), or the like on the vehicle side. The driver circuit 174 generates a drive signal for switching the upper-arm active element 155 and the lower-arm active element 157 on the basis of the timing signal outputted from the control circuit 172. Note that reference sign 181 denotes a connector.
The upper-arm and lower-arm series circuits include a temperature sensor (not illustrated), and temperature information of the upper-arm and lower-arm series circuits is inputted to the control circuit 172. Voltage information on the DC positive electrode side of the upper-arm and lower-arm series circuits is inputted to the control circuit 172. The control circuit 172 performs over-temperature detection and overvoltage detection on the basis of these pieces of information, and in a case where over-temperature or overvoltage is detected, stops the switching operation of all the upper-arm active elements 155 and lower-arm active elements 157 and protects the upper-arm and lower-arm series circuits from over-temperature or overvoltage.
The power conversion device 200 includes a housing 12 that includes a lower case 11 and an upper case 10 and that is formed in a substantially rectangular parallelepiped shape. An electric circuit body 400, a capacitor module 500, and the like are accommodated inside the housing 12. The electric circuit body 400 has a cooling flow path, and a cooling water inflow pipe 13 and a cooling water outflow pipe 14 that communicate with the cooling flow path protrude from one lateral surface of the housing 12. As illustrated in
A connector 17 is attached to one lateral surface of the housing 12 in the longitudinal direction, and an AC terminal 18 is connected to the connector 17. A connector 21 is provided on the surface from which the cooling water inflow pipe 13 and the cooling water outflow pipe 14 are led out.
As illustrated in
The embodiments described above afford the following actions and effects.
(1) Semiconductor devices 300 and 300′ include a plurality of power semiconductor elements 155, 156, 157, and 158, conductor plates 430, 431, 432, and 433 to which the plurality of power semiconductor elements 155, 156, 157, and 158 are joined, insulation sheets 440 and 441 bonded to the surface of conductor plates 430, 431, 432, and 433 on the opposite side from the side of the plurality of semiconductor elements, and a resin member 360 sealing the plurality of power semiconductor elements 155, 156, 157, and 158, the insulation sheets 440 and 441, and the conductor plates 430, 431, 432, and 433. The conductor plates 430, 431, 432, and 433 each have a plurality of element joining regions 462 to which the plurality of power semiconductor elements 155, 156, 157, and 158 are joined, respectively, and a connection region 463 provided between the plurality of element joining regions 462, wherein the insulation sheet-side surface of the conductor plates 430, 431, 432, and 433 in the element joining regions 462 protrudes from the insulation sheet-side surface of the connection region 463 and is bonded to the insulation sheets 440 and 441, and
The present invention is not limited to or by the above-described embodiments, and various modes conceivable within the scope of the technical ideas of the present invention are also included within the scope of the present invention as long as the features of the present invention are not impaired. Moreover, the above-described embodiments and modifications may be combined.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-028605 | Feb 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/048680 | 12/28/2022 | WO |
