WO2022021379A1 - Power electronic device, and method for manufacturing the same - Google Patents

Power electronic device, and method for manufacturing the same Download PDF

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Publication number
WO2022021379A1
WO2022021379A1 PCT/CN2020/106338 CN2020106338W WO2022021379A1 WO 2022021379 A1 WO2022021379 A1 WO 2022021379A1 CN 2020106338 W CN2020106338 W CN 2020106338W WO 2022021379 A1 WO2022021379 A1 WO 2022021379A1
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WO
WIPO (PCT)
Prior art keywords
heat
electrically insulating
electronic device
power electronic
heat spreader
Prior art date
Application number
PCT/CN2020/106338
Other languages
French (fr)
Inventor
Xiuxiu LYU
Lennart Baruschka
Original Assignee
Siemens Aktiengesellschaft
Siemens Ltd., China
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Filing date
Publication date
Application filed by Siemens Aktiengesellschaft, Siemens Ltd., China filed Critical Siemens Aktiengesellschaft
Priority to PCT/CN2020/106338 priority Critical patent/WO2022021379A1/en
Publication of WO2022021379A1 publication Critical patent/WO2022021379A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K7/00—Constructional details common to different types of electric apparatus
    • H05K7/20—Modifications to facilitate cooling, ventilating, or heating
    • H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
    • H05K7/209—Heat transfer by conduction from internal heat source to heat radiating structure

Definitions

  • Embodiments of the present application relate to the field of power devices, and in particular to, a power electronic device, and a method for manufacturing the same.
  • a power electronic device As an efficient power energy transmission system, a power electronic device is widely applied to the fields, such as household appliances, communication devices, and energy transmission devices. In order to avoid system failure caused by thermal runaway and ensure that the power electronic device has high reliability, it is necessary to effectively cool the power electronic device. For some power electronic devices, in order to ensure their reliability, the power electronic device is placed in an enclosed casing. In this case, it is impossible to cool the power electronic device using an active cooling structure such as a blower, such that heat generated by the power electronic device is discharged mainly relying on passive cooling.
  • an active cooling structure such as a blower
  • junction temperature i.e., actual working temperature
  • junction temperature i.e., actual working temperature
  • a photovoltaic (PV) micro inverter is installed on the back of a photovoltaic panel (PV panel) , and is configured to convert DC power of an electrical appliance into AC power.
  • PV panel photovoltaic panel
  • the working temperature is relatively high and the heat dissipation is relatively difficult.
  • a very high working temperature easily leads to a very short service life.
  • embodiments of the present application provide a power electronic device and a method for manufacturing the same, to at least partially solve the above problems.
  • a power electronic device includes: a casing, the casing having an accommodating cavity; a circuit assembly, the circuit assembly including a circuit board and a heat-generating component, the circuit board being provided in the accommodating cavity, and the heat-generating component being provided on the circuit board; a heat spreader, the heat spreader being located in the accommodating cavity of the casing; and an electrically insulating material, the electrically insulating material surrounding the circuit board and the heat-generating component, at least a part of the electrically insulating material being located between the heat spreader and the heat-generating component, at least a part of the heat spreader being in contact with the electrically insulating material, a thermal conductivity of the heat spreader being greater than a thermal conductivity of the electrically insulating material, and the thermal conductivity of the electrically insulating material being greater than a thermal conductivity of air.
  • the electrically insulating material surrounds the heat spreader.
  • the casing is provided with a protrusion protruding toward inside of the accommodating cavity, and the heat spreader is disposed on a wall of the protrusion facing the heat-generating component.
  • the casing includes a body and a cover, the cover is detachably connected to the body, the accommodating cavity is enclosed by the cover and the body when the cover is connected to the body, and the protrusion is provided on the cover.
  • the cover is provided with a potting hole through which the electrically insulating material is potted into the accommodating cavity.
  • the heat-generating component includes a chip provided on the circuit board, and a projection of the heat spreader on a mounting surface of the circuit board covers a projection of the chip on the mounting surface.
  • the power electronic device further includes a fastening structure, and the fastening structure connects the heat spreader and the casing to fasten the heat spreader to the casing.
  • the heat spreader fits on a wall of the casing.
  • first gap there is a first gap between the heat spreader and a wall of the casing, and the electrically insulating material is filled in the first gap.
  • the power electronic device further includes an electrically insulating fastener, and the heat spreader is mounted on the circuit board through the electrically insulating fastener.
  • the circuit board includes a circuit board housing and an inner core of a heat-dissipating material
  • the circuit board housing has an inner cavity
  • the inner core of the heat-dissipating material is provided in the inner cavity
  • a thermal conductivity of the inner core of the heat-dissipating material is greater than a thermal conductivity of the circuit board housing.
  • the heat-dissipating structure includes a metal plate, and a thickness of the metal plate ranges from 0.3 mm to 3 mm.
  • the accommodating cavity includes a cooling region, a temperature of the cooling region is lower than a temperature of a region in which the heat-generating component is located, a difference between the temperature of the cooling region and the temperature of the region in which the heat-generating component is located is greater than or equal to a set threshold, the heat spreader further includes an extending portion, the extending portion is provided on the metal plate, and at least a part of the extending portion is located in the cooling region.
  • a distance between the metal plate in a thickness direction of the casing and the heat-generating component is greater than or equal to 0.3 mm.
  • a method for manufacturing a power electronic device is provided.
  • the method is used for manufacturing the above power electronic device.
  • the method includes: installing a circuit assembly and a heat spreader of the power electronic device into an accommodating cavity of a casing, and spacing the heat spreader away from a heat-generating component of the circuit assembly; and providing an electrically insulating material in the accommodating cavity of the casing, such that the electrically insulating material surrounds a circuit board and the heat-generating component of the circuit assembly, and at least a part of the electrically insulating material is located between the heat spreader and the heat-generating component.
  • the providing an electrically insulating material in the accommodating cavity of the casing includes: potting the electrically insulating material into the accommodating cavity through a potting hole on the casing.
  • the casing of the power electronic device is configured to bear and protect the circuit component, the heat spreader, the electrically insulating material, and the like.
  • Surrounding the circuit board and the heat-generating component in the circuit assembly with the electrically insulating material can not only protect the circuit board and the heat-generating component (e.g., waterproofing, dustproofing, and improving structural strength) , but also realize insulation between the heat spreader and the heat-generating component.
  • the electrically insulating material since the thermal conductivity of the electrically insulating material is greater than the thermal conductivity of air, the electrically insulating material also has a heat dissipation effect, and can quickly dissipate the heat generated by the heat-generating component elsewhere, thereby reducing the junction temperature of the heat-generating component.
  • the thermal conductivity of the heat spreader is greater than the thermal conductivity of the electrically insulating material, a thermal resistance in a process of transferring the heat generated by the heat-generating component to the casing is significantly decreased, compared with a thermal resistance when only the electrically insulating material is filled in the accommodating cavity, such that heat dissipation efficiency of the power electronic device having the heat spreader is significantly improved, which helps to reduce the junction temperature of the heat-generating component and to avoid the failure or service life reduction of the heat-generating component caused by a very high temperature in a working environment.
  • FIG. 1 shows a schematic diagram of a three-dimensional structure of a power electronic device according to an embodiment of the present application
  • FIG. 2 shows a schematic structural diagram of a top view of the power electronic device according to an embodiment of the present application
  • FIG. 3 shows a schematic structural diagram of a bottom view of a cover of the power electronic device according to an embodiment of the present application
  • FIG. 4 shows a schematic structural diagram of a section view which is taken along line I-I in FIG. 2.
  • FIG. 5 shows a schematic structural diagram of a section view which is taken along line II-II in FIG. 2;
  • FIG. 6 shows a schematic structural diagram of a section view, taken along line I-I in FIG. 2, of another power electronic device according to an embodiment of the present application;
  • FIG. 7 shows a schematic structural diagram of a section view, taken along line I-I in FIG. 2, of another power electronic device according to an embodiment of the present application.
  • FIG. 8 shows a schematic flowchart of a method for manufacturing a power electronic device according to an embodiment of the present application.
  • FIG. 1 shows a schematic diagram of a three-dimensional structure of a power electronic device according to an embodiment of the present application.
  • FIG. 2 shows a schematic structural diagram of a top view of the power electronic device according to an embodiment of the present application.
  • FIG. 3 shows a schematic structural diagram of a bottom view of a cover of the power electronic device according to an embodiment of the present application
  • FIG. 4 shows a schematic structural diagram of a section view which is taken along line I-I in FIG. 2.
  • the power electronic device includes: a casing 10, a circuit assembly, a heat spreader 40, and an electrically insulating material 30.
  • the casing 10 has an accommodating cavity; the circuit assembly includes a circuit board 21 and a heat-generating component 22, the circuit board 21 is provided in the accommodating cavity, and the heat-generating component 22 is provided on the circuit board 21; the heat spreader 40 is located in the accommodating cavity of the casing 10; and the electrically insulating material 30 surrounds the circuit board 21 and the heat-generating component 22, at least a part of the electrically insulating material 30 is located between the heat spreader 40 and the heat-generating component 22, at least a part of the heat spreader 40 is in contact with the electrically insulating material 30, a thermal conductivity of the heat spreader 40 is greater than a thermal conductivity of the electrically insulating material 30, and the thermal conductivity of the electrically insulating material 30 is greater than a thermal conductivity of air.
  • the casing 10 of the power electronic device is configured to support and protect the circuit component, the heat spreader 40, the electrically insulating material 30, and the like. Surrounding the circuit board 21 and the heat-generating component 22 in the circuit assembly with the electrically insulating material 30 not only protects the circuit board 21 and the heat-generating component 22 (e.g., waterproofing, dustproofing, and improving structural strength) , but also achieves insulation between the heat spreader 40 and the heat-generating component 22.
  • the electrically insulating material 30 since the thermal conductivity of the electrically insulating material 30 is greater than the thermal conductivity of air, the electrically insulating material 30 also has a heat dissipation effect, and, thus, can quickly dissipate the heat generated by the heat-generating component 22 elsewhere, thereby reducing the junction temperature of the heat-generating component 22.
  • the heat spreader 40 By providing the heat spreader 40 in the casing 10, and rendering at least a part of the heat spreader 40 in contact with the electrically insulating material 30, a contact area between the heat spreader 40 and the electrically insulating material 30 is ensured, and a sufficient heat transfer area is ensured as well.
  • the thermal conductivity of the heat spreader 40 is greater than the thermal conductivity of the electrically insulating material 30, a thermal resistance in a process of transferring the heat generated by the heat-generating component 22 to the casing 10 is significantly reduced, compared with a thermal resistance when only the electrically insulating material 30 is filled in the accommodating cavity. As a result, a heat dissipation efficiency of the power electronic device having the heat spreader 40 is significantly improved, which helps to reduce the junction temperature of the heat-generating component 22 and to avoid the failure or service life reduction of the heat-generating component 22 caused by a very high temperature in a working environment.
  • the power electronic device may be an inverter, a convertor, or other power electronic devices related to the power system, such as an outdoor power source, an outdoor LED, and an electric vehicle charger.
  • an inverter such as an outdoor power source, an outdoor LED, and an electric vehicle charger.
  • the description is provided by taking a micro inverter applied to a photovoltaic cell panel as an example, but those skilled in the art should understand that the power electronic device of this embodiment is not limited to this.
  • the electrically insulating material 30 filled in the power electronic device may be filled in the accommodating cavity of the casing 10, or be filled in only a part of the accommodating cavity.
  • the electrically insulating material is filled in a part of the accommodating cavity, it is only necessary to ensure that the electrically insulating material 30 surrounds the entire circuit assembly (i.e., surrounds the entire circuit board 21 and all components on the circuit board 21) , and is filled in a gap between the heat spreader 40 and the heat-generating component 22, such that at least a part of the surface of the heat spreader 40 is in contact with the electrically insulating material 30.
  • the electrically insulating material 30 may surround the heat spreader 40, i.e., the electrically insulating material 30 covers all outer surfaces of the heat spreader 40, such that a heat transfer area between the heat spreader 40 and the electrically insulating material 30 is maximized, and such that the heat dissipation effect is high.
  • the electrically insulating material 30 may be any appropriate material, as long as aninsulativity between the heat-generating component 22 and the heat spreader 40 can be ensured, and the thermal conductivity of the electrically insulating material 30 is greater than the thermal conductivity of air.
  • the electrically insulating material 30 may be an electrically insulating film (e.g., a heat-conducting glue or a thermal pad) , which is arranged between the heat spreader 40 and the heat-generating component 22, such that the heat generated by the heat-generating component 22 is transferred to the electrically insulating film, transferred to the heat spreader 40 through the electrically insulating film, and then transferred to the casing 10 and an external environment through the heat spreader 40, so as to prevent heat from accumulating at the heat-generating component 22.
  • an electrically insulating film e.g., a heat-conducting glue or a thermal pad
  • the electrically insulating material 30 may also be appropriate potting materials. This is not limited in this embodiment.
  • the potting material can protect the circuit board 21 and the heat-generating component 22 due to its good mechanical properties, and can ensure that the heat dissipation requirements are met due to the good heat-conducting properties of the potting material .
  • the casing 10 is provided with a protrusion 11 protruding toward inside of the accommodating cavity, and the heat spreader 40 is disposed on a wall of the protrusion 11 facing the heat-generating component 22.
  • a distance between the heat spreader 40 and the heat-generating component 22 may be minimized. The smaller the distance is, the more easily the heat generated by the heat-generating component 22 is transferred to the heat spreader 40, and the more easily the heat is quickly transferred by the heat spreader 40 to a region far away from the heat-generating component 22 and at a low temperature, such that the heat transfer efficiency is higher, to accelerate the heat dissipation.
  • the heat spreader 40 is disposed close to the heat-generating component 22 as much as possible, such that heat accumulation at the heat-generating component 22 can be fully avoided, thereby increasing the heat dissipation efficiency, and achieving the purpose of effectively controlling the working temperature of the heat-generating component 22.
  • the distance between the heat spreader 40 in a thickness direction of the casing 10 and the heat-generating component 22 is greater than or equal to 0.3 mm.
  • the distance between the heat spreader 40 and the heat-generating component 22 is less than 0.3 mm (millimeter) , the insulation reliability between the heat spreader 40 and the heat-generating component 22 will be reduced, thus reducing the safety of the power electronic device. Therefore, the distance between the heat spreader 40 and the heat-generating component 22 is at least 0.3 mm in order to ensure the insulativity. In the case where the distance is ensured to be greater than or equal to 0.3 mm, the heat spreader 40 may be close to the heat-generating component 22 as far as possible.
  • a position of the protrusion 11 on the casing 10 may be adaptively set. This is not limited in this embodiment.
  • the casing 10 in this embodiment includes a body 12 and a cover 13, the cover 13 is detachably connected to the body 12, the accommodating cavity is enclosed by the cover 13 and the body 12 when the cover 13 is connected to the body 12, and the protrusion 11 is provided on the cover 13.
  • the protrusion 11 is formed by a local part of the cover 13 that protrudes toward the inside of the accommodating cavity, which not only provides a mounting position close to the heat-generating component 22 for the heat spreader 40, but also will not affect thicknesses at other positions of the casing 10 and can accommodate other components of great heights on the circuit board 21.
  • the protrusion 11 compared with a casing provided with no protrusion 11, the protrusion 11 reduces the size of the accommodating cavity, thereby reducing the amount of the electrically insulating material 30 filled in the accommodating cavity, and reducing the costs of manufacturing the .
  • the cover 13 and the body 12 may be made of a plastic material or other appropriate materials. Taking the plastic material as an example, the protrusion 11 on the cover 13 may be integrally molded on the cover 13 when the cover 13 is molded, or the protrusion 11 may be processed on the cover 13 by machining after the cover 13 is molded. This is not limited in this embodiment.
  • a thickness of the cover 13 is consistent everywhere, and the protrusion 11 may be formed by protruding a part of the cover 13 toward the inside of the accommodating cavity.
  • the protrusion 11 is formed by protruding a part of the cover 13 corresponding to the heat-generating component 22 (e.g., the heat-generating component 22 is a chip in the power electronic device) inward.
  • the cover 13 protrudes inward, which will not affect heights at other positions of the accommodating cavity, such that the casing 10 can accommodate components (e.g., an inductor, and a capacitor) of great heights on the circuit board 21.
  • components e.g., an inductor, and a capacitor
  • the cover 13 may also form the protrusion 11 in other ways. This is not limited in this embodiment.
  • the cover 13 is also provided with a potting hole 131 through which the electrically insulating material 30 is potted into the accommodating cavity, such that the potting material can enter into the accommodating cavity.
  • a potting hole 131 may be one or more potting holes 131. This is not limited in this embodiment.
  • the heat-generating component 22 of the power electronic device not only includes the above chip (the chip may be surface mounted on the circuit board 21) , but also may include other components on the circuit board 21.
  • the description is provided by taking the heat-generating component 22 being two surface mounted chips on the circuit board 21 in a micro inverter as an example.
  • the heat-generating component 22 may also be other surface mounted devices on the circuit board 21.
  • FIG. 5 shows a schematic structural diagram of a section view which is taken along line II-II in FIG. 2, and omits the electrically insulating material 30 in the accommodating cavity.
  • the heat-generating component 22 includes a chip provided on the circuit board 21
  • a projection of the heat spreader 40 on a mounting surface of the circuit board 21 covers a projection of the chip on the mounting surface.
  • the heat spreader 40 is provided corresponding to the heat-generating component 22, and the projection of the heat spreader 40 on the mounting surface covers the projection of the chip on the mounting surface, such that the heat spreader 40 has an enough area to fully absorb the heat generated by each heat-generating component 22 and quickly transfer the heat to an environment outside the casing 10.
  • a shape, a size, a material, and the like of the heat spreader 40 may be determined as required, e.g., determined based on at least one of a size of the heat-generating component 22, power consumption of the power electronic device, a circuit layout and a size of a PCB, or a size of the casing 10.
  • the heat spreader 40 may be, for example, a metal plate.
  • the heat spreader may also be an insulating material with a thermal conductivity greater than that of the electrically insulating material 30. This is not limited in this embodiment.
  • the heat spreader may also be made of a thermal interface material, which is cheaper than the metal material and can satisfy the heat dissipation requirements.
  • a thickness of the metal plate ranges from 0.3 mm to 3 mm.
  • the thickness of the metal plate within this range not only ensures the light weight of the metal plate but also reduces the production costs of the metal plate.
  • the thickness of the metal plate is less than 0.3mm, the heat dissipation performance of the metal plate will be affected because of the limited thickness of the metal plate. If the thickness of the heat metal plate is greater than 3 mm, then the weight of the heat metal plate will greatly increase the overall weight of the power electronic device, which is adverse to the light weight of the power electronic device.
  • the heat spreader 40 may be a polygonal plate or a plate of a complex shape.
  • the heat spreader 40 not only includes a metal plate, but also includes an extending portion (not shown in the figures) .
  • the extending portion is connected to the metal plate or is an integral part of the metal plate, and at least a part of the extending portion is located in a cooling region of the accommodating cavity.
  • a temperature of the cooling region is lower than a temperature of the region in which the heat-generating component 22 is located, a difference between the temperature of the cooling region and the temperature of the region in which the heat-generating component 22 is located is greater than or equal to a preset threshold.
  • the heat generated by the heat-generating component 22 can be quickly transferred to the cooling region at a low temperature through the extending portion, thereby further decreasing the temperature of the region in which the heat-generating component 22 is located.
  • a shape, a material, and a size of the extending portion may be determined as required.
  • the extending portion may be integrally formed with the metal plate or the extending portion and the metal plate may be separately machined and then connected while molding.
  • the heat spreader 40 may be mounted on the casing 10 or on the circuit board 21.
  • the power electronic device further includes a fastening structure, and the fastening structure connects the heat spreader 40 and the casing 10 to fasten the heat spreader 40 to the casing 10.
  • the heat spreader 40 may be fastened to the casing 10 through the fastening structure.
  • the fastening structure includes a holding slot (not shown in the figures) provided on the casing 10, and the heat spreader 40 is embedded in the holding slot.
  • the holding slot not only can the heat spreader 40 be fastened to the casing 10, but also the installation is convenient, fast and labor-saving.
  • the holding slot may be adapted to a shape of the heat spreader 40, at least a part of the heat spreader 40 is embedded in the holding slot, and the heat spreader 40 may be limited through a holding hook provided on the holding slot to prevent the heat spreader 40 from separation from the holding slot.
  • the fastening structure includes a threaded fastener 41, and a mounting hole is provided on the heat spreader 40.
  • the threaded fastener 41 passes through the mounting hole and is in threaded connection with the casing 10 to fasten the heat spreader 40 on the casing 10.
  • the threaded fastener 41 enables the heat spreader 40 to be connected to the casing 10 firmly and reliably.
  • the threaded fastener 41 may be a screw, a bolt, or the like, one or more mounting holes may be provided on the heat spreader 40, and each mounting hole can allow a threaded fastener 41 to pass through.
  • 4 mounting holes are provided on the heat spreader 40.4 threaded fasteners 41 are arranged through the mounting holes each to each and are threaded with the casing 10 to fasten the heat spreader 40 on the casing 10.
  • the heat spreader 40 may also be glued to the casing 10. This is not limited in this embodiment.
  • the heat spreader 40 fits on a wall of the casing 10.
  • the heat spreader 40 is closely screwed on the casing 10 to ensure that the heat spreader 40 fits on the casing 10.
  • FIG. 7 shows a schematic structural diagram of a section view, taken along line I-I in FIG. 2, of another power electronic device according to an embodiment of the present application.
  • a first gap 51 is provided between the heat spreader 40 and an inner wall of the casing 10, and the electrically insulating material 30 is filled in the first gap 51.
  • the heat spreader 40 when the heat spreader 40 is provided on the circuit board 21, if the heat spreader 40 includes a metal heat plate, then the power electronic device further includes an electrically insulating fastener 42, and the heat spreader 40 is mounted on the circuit board 21 through the electrically insulating fastener 42.
  • the heat spreader 40 can be ensured to be connected to the circuit board 21, and the insulativity can be ensured.
  • the electrically insulating fastener 42 may be a bolt, a screw, or the like made of an electrically insulating material.
  • the metal heat plate is connected to the circuit board 21 through the electrically insulating fastener 42.
  • the metal heat plate is located above the heat-generating component 22 and is spaced from the heat-generating component 22 by a second gap, such that the electrically insulating material 30 can be filled into the second gap to achieve electrical insulation and heat transfer.
  • the circuit board 21 includes a circuit board housing and an inner core of a heat-dissipating material, the circuit board housing has an inner cavity, the inner core of the heat-dissipating material is provided in the inner cavity, and a thermal conductivity of the inner core of the heat-dissipating material is greater than a thermal conductivity of the circuit board housing.
  • the heat dissipation capacity of the circuit board 21 can be improved, such that the heat generated by the heat-generating component 22 can not only be transferred to the casing 10 through the electrically insulating material 30 and the heat spreader 40, but also be transferred to the electrically insulating material 30 through the inner core of the heat-dissipating material in the circuit board 21 and the circuit board housing, and then be transferred to the casing 10 through the electrically insulating material 30, thereby improving the heat dissipation effect.
  • the circuit board housing may be a circuit board housing formed by a PCB.
  • the inner core of the heat-dissipating material may be an inner core made of a metal or an inner core made of the electrically insulating material. This is not limited in this embodiment.
  • thermal resistance changes of a heat transfer path are analyzed below, to illustrate the principle of increasing the heat dissipation efficiency through the heat spreader.
  • the first heat transfer path is: the heat-generating component 22 ⁇ the electrically insulating material ⁇ the cover ⁇ an external environment.
  • the heat spreader 40 is provided and the heat spreader 40 fits on a wall of the cover, the heat generated by the heat-generating component 22 is transferred along a second heat transfer path.
  • the second heat transfer path is: the heat-generating component 22 ⁇ the electrically insulating material between the heat-generating component 22 and the heat spreader 40 ⁇ the heat spreader 40 ⁇ the cover ⁇ the environment of the power electronic device, where if the electrically insulating material is filled between the heat spreader 40 and the cover, then the heat is transferred to the cover 13 through the heat spreader 40, and then through the electrically insulating material between the heat spreader 40 and the cover.
  • the second heat transfer path is additionally provided with two thermal resistances, which are a thermal resistance of the heat spreader (denoted as R spreader ) and a thermal resistance from the heat spreader to the cover (denoted as R spreader-housing ) , respectively.
  • R spreader is small because the thermal conductivity of the heat spreader is generally higher, especially higher than that of the electrically insulating material 30, and a thickness of the heat spreader is smaller.
  • the thermal resistance R spreader-housing between the heat spreader 40 and the cover 13 is also smaller.
  • a distance between the casing and the heat-generating component 22 is decreased, a heat transfer area in the electrically insulating material is increased, and the heat spreader 40 has a higher thermal conductivity, such that a total thermal resistance from the heat-generating component 22 to the casing is decreased, thereby further improving the heat dissipation efficiency.
  • the heat transfer efficiency in the electrically insulating material is improved, and then the heat dissipation efficiency is higher. It is validated through thermal simulation experiments that by additionally providing an aluminum heat plate with a thickness of 0.5 mm in the electrically insulating material 30, a junction temperature rise of the heat-generating component 22 will be decreased by 10%to 20%, and a junction temperature of the heat-generating component 22 will be kept at an optimal working temperature, thereby improving the overall reliability of the power electronic device.
  • the junction temperature rise of the heat-generating component 22 refers to a difference between a temperature of the heat-generating component 22 with the junction temperature in a stable state after the heat-generating component runs for a period of time and a temperature of the power electronic device at startup. For example, at a moment when the power electronic device is started, the junction temperature of the heat-generating component 22 is a first temperature. In 10 minutes after the power electronic device is started, the junction temperature of the heat-generating component 22 is in a stable state, and the junction temperature at this time is a second temperature. The junction temperature rise is a difference between the second temperature and the first temperature. It is validated through experiments that in the case where the heat plate is provided, the junction temperature rise is decreased by 10%to 20%, compared with that in the case where no heat plate is provided.
  • a method for manufacturing a power electronic device is provided.
  • the method is used for manufacturing the power electronic device.
  • the method includes the following steps:
  • Step S102 installing a circuit assembly and a heat spreader 40 of the power electronic device into an accommodating cavity of a casing 10, and spacing the heat spreader 40 from the heat-generating component 22 of the circuit assembly.
  • the circuit assembly may be mounted by bolting a circuit board 21 of the circuit assembly on the casing 10, and of course, may also be mounted by any other appropriate approach.
  • the heat spreader 40 may be mounted on the casing 10, or may be mounted on the circuit board 21. This is not limited in this embodiment, as long as there being a gap (i.e., a second gap) between the heat spreader 40 and the heat-generating component 22 can be ensured after the heat spreader 40 is mounted in the accommodating cavity.
  • the heat spreader 40 may be connected to the protrusion 11 in the cover 13 of the casing 10 through a threaded fastener.
  • the heat spreader 40 is connected to the circuit board 21 through an electrically insulating fastener 42 (e.g., a bolt made of an electrically insulating material) .
  • Step S104 providing an electrically insulating material 30 in the accommodating cavity of the casing 10, such that the circuit board 21 is surrounded by the electrically insulating material 30 and the heat-generating component 22 of the circuit assembly, and at least a part of the electrically insulating material 30 is located between the heat spreader 40 and the heat-generating component 22.
  • the electrically insulating material 30 may be provided in the accommodating cavity by potting the electrically insulating material 30 into the accommodating cavity through a potting hole 131 on the casing 10.
  • the electrically insulating material 30 being an epoxy as an example
  • a fluid epoxy is potted into the accommodating cavity through the potting hole 131 on the cover 13, such that the epoxy is filled in a gap in the accommodating cavity, thereby discharging air.
  • the epoxy cures and surrounds the circuit board 21 and components on the circuit board 21 to protect and insulate the circuit board 21 and the components on the circuit board 21.
  • the epoxy can further transfer the heat to the casing 10, thereby cooling the heat-generating components 22, and preventing the heat accumulation at the heat-generating component 22 from resulting in a very high junction temperature.
  • a thermal conductivity of the heat spreader 40 is greater than that of the epoxy, such that the heat spreader can improve the efficiency of heat transfer to the casing 10, thereby further improving the heat dissipation effect.
  • the power electronic device has the following beneficial effects:
  • a heat spreader with a higher thermal conductivity is additionally provided in the electrically insulating material in the casing, to achieve the purpose of reducing the thermal resistance of the heat transfer path from the heat-generating component to the casing, thereby improving the heat dissipation efficiency.
  • At least a part of the cover is recessed toward inside of the accommodating cavity to form a protrusion, such that a distance between a wall of the protrusion facing the heat-generating component and the heat-generating component is reduced.
  • the protrusion can be used to install the heat spreader made of the metal material, and the heat generated by the heat-generating component can be dissipated using the heat spreader and the entire electrically insulating material, thus reducing the junction temperature of the heat-generating component.
  • the heat spreader may be a rectangular heat plate.
  • the heat plate may be equipped with threaded fasteners (e.g., screws) at four top corners, and is coupled to the casing through the threaded fasteners.
  • the heat plate may fit on a wall of the cover, or there may also be a first gap between the heat plate and the cover, and the electrically insulating material may be filled in the first gap to ensure the efficiency of heat transfer from the heat plate to the cover.
  • the heat plate may also be provided with a potting hole for the electrically insulating material to enter the first gap.

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  • Engineering & Computer Science (AREA)
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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Cooling Or The Like Of Electrical Apparatus (AREA)

Abstract

A power electronic device and a method for manufacturing the same are provided. The device includes: a casing having an accommodating cavity; a circuit assembly including a circuit board and a heat-generating component, the circuit board being provided within the accommodating cavity, and the heat-generating component being provided on the circuit board; a heat spreader being located within the accommodating cavity of the casing; and an electrically insulating material, the electrically insulating material surrounding the circuit board and the heat-generating component, at least a part of the electrically insulating material being located between the heat spreader and the heat-generating component, at least a part of the heat spreader being in contact with the electrically insulating material, a thermal conductivity of the heat spreader being greater than a thermal conductivity of the electrically insulating material, the thermal conductivity of the electrically insulating material being greater than a thermal conductivity of air.

Description

POWER ELECTRONIC DEVICE, AND METHOD FOR MANUFACTURING THE SAME TECHNICAL FIELD
Embodiments of the present application relate to the field of power devices, and in particular to, a power electronic device, and a method for manufacturing the same.
BACKGROUND
As an efficient power energy transmission system, a power electronic device is widely applied to the fields, such as household appliances, communication devices, and energy transmission devices. In order to avoid system failure caused by thermal runaway and ensure that the power electronic device has high reliability, it is necessary to effectively cool the power electronic device. For some power electronic devices, in order to ensure their reliability, the power electronic device is placed in an enclosed casing. In this case, it is impossible to cool the power electronic device using an active cooling structure such as a blower, such that heat generated by the power electronic device is discharged mainly relying on passive cooling.
With the miniaturization and compactness of the power electronic device and the high switching frequency during working, power density of the power electronic device is increased, and junction temperature (i.e., actual working temperature) of the power electronic device is also greatly increased. However, limited to the working environment and service space, it is more difficult to cool the power electronic device. For example, a photovoltaic (PV) micro inverter is installed on the back of a photovoltaic panel (PV panel) , and is configured to convert DC power of an electrical appliance into AC power. As the photovoltaic micro inverter works under strong sunlight, the working temperature is relatively high and the heat dissipation is relatively difficult. A very high working temperature easily leads to a very short service life.
In conclusion, how to achieve effective heat dissipation of the power electronic device has become a problem to be urgently solved.
SUMMARY
In order to solve the above problems, embodiments of the present application provide a power electronic device and a method for manufacturing the same, to at least partially solve the  above problems.
According to a first aspect of an embodiment of the present application, a power electronic device is provided. The power electronic device includes: a casing, the casing having an accommodating cavity; a circuit assembly, the circuit assembly including a circuit board and a heat-generating component, the circuit board being provided in the accommodating cavity, and the heat-generating component being provided on the circuit board; a heat spreader, the heat spreader being located in the accommodating cavity of the casing; and an electrically insulating material, the electrically insulating material surrounding the circuit board and the heat-generating component, at least a part of the electrically insulating material being located between the heat spreader and the heat-generating component, at least a part of the heat spreader being in contact with the electrically insulating material, a thermal conductivity of the heat spreader being greater than a thermal conductivity of the electrically insulating material, and the thermal conductivity of the electrically insulating material being greater than a thermal conductivity of air.
Alternatively, the electrically insulating material surrounds the heat spreader.
Alternatively, the casing is provided with a protrusion protruding toward inside of the accommodating cavity, and the heat spreader is disposed on a wall of the protrusion facing the heat-generating component.
Alternatively, the casing includes a body and a cover, the cover is detachably connected to the body, the accommodating cavity is enclosed by the cover and the body when the cover is connected to the body, and the protrusion is provided on the cover.
Alternatively, the cover is provided with a potting hole through which the electrically insulating material is potted into the accommodating cavity.
Alternatively, the heat-generating component includes a chip provided on the circuit board, and a projection of the heat spreader on a mounting surface of the circuit board covers a projection of the chip on the mounting surface.
Alternatively, the power electronic device further includes a fastening structure, and the fastening structure connects the heat spreader and the casing to fasten the heat spreader to the casing.
Alternatively, the heat spreader fits on a wall of the casing.
Alternatively, there is a first gap between the heat spreader and a wall of the casing, and the electrically insulating material is filled in the first gap.
Alternatively, the power electronic device further includes an electrically insulating fastener, and the heat spreader is mounted on the circuit board through the electrically insulating fastener.
Alternatively, the circuit board includes a circuit board housing and an inner core of a heat-dissipating material, the circuit board housing has an inner cavity, the inner core of the heat-dissipating material is provided in the inner cavity, and a thermal conductivity of the inner core of the heat-dissipating material is greater than a thermal conductivity of the circuit board housing.
Alternatively, the heat-dissipating structure includes a metal plate, and a thickness of the metal plate ranges from 0.3 mm to 3 mm.
Alternatively, the accommodating cavity includes a cooling region, a temperature of the cooling region is lower than a temperature of a region in which the heat-generating component is located, a difference between the temperature of the cooling region and the temperature of the region in which the heat-generating component is located is greater than or equal to a set threshold, the heat spreader further includes an extending portion, the extending portion is provided on the metal plate, and at least a part of the extending portion is located in the cooling region.
Alternatively, a distance between the metal plate in a thickness direction of the casing and the heat-generating component is greater than or equal to 0.3 mm.
According to another aspect of the present invention, a method for manufacturing a power electronic device is provided. The method is used for manufacturing the above power electronic device. The method includes: installing a circuit assembly and a heat spreader of the power electronic device into an accommodating cavity of a casing, and spacing the heat spreader away from a heat-generating component of the circuit assembly; and providing an electrically insulating material in the accommodating cavity of the casing, such that the electrically insulating material surrounds a circuit board and the heat-generating component of the circuit assembly, and at least a part of the electrically insulating material is located between the heat spreader and the heat-generating component.
Alternatively, the providing an electrically insulating material in the accommodating cavity of the casing includes: potting the electrically insulating material into the accommodating cavity through a potting hole on the casing.
The casing of the power electronic device provided according to the embodiments of the  present application is configured to bear and protect the circuit component, the heat spreader, the electrically insulating material, and the like. Surrounding the circuit board and the heat-generating component in the circuit assembly with the electrically insulating material can not only protect the circuit board and the heat-generating component (e.g., waterproofing, dustproofing, and improving structural strength) , but also realize insulation between the heat spreader and the heat-generating component. In addition, since the thermal conductivity of the electrically insulating material is greater than the thermal conductivity of air, the electrically insulating material also has a heat dissipation effect, and can quickly dissipate the heat generated by the heat-generating component elsewhere, thereby reducing the junction temperature of the heat-generating component. By providing the heat spreader in the casing, and rendering at least a part of the heat spreader be in contact with the electrically insulating material, a contact area between the heat spreader and the electrically insulating material is ensured, and a sufficient heat transfer area is ensured as well. Further, since the thermal conductivity of the heat spreader is greater than the thermal conductivity of the electrically insulating material, a thermal resistance in a process of transferring the heat generated by the heat-generating component to the casing is significantly decreased, compared with a thermal resistance when only the electrically insulating material is filled in the accommodating cavity, such that heat dissipation efficiency of the power electronic device having the heat spreader is significantly improved, which helps to reduce the junction temperature of the heat-generating component and to avoid the failure or service life reduction of the heat-generating component caused by a very high temperature in a working environment.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings below are only intended to schematically illustrate and explain the present application, and do not limit the scope of the present application. In the figures,
FIG. 1 shows a schematic diagram of a three-dimensional structure of a power electronic device according to an embodiment of the present application;
FIG. 2 shows a schematic structural diagram of a top view of the power electronic device according to an embodiment of the present application;
FIG. 3 shows a schematic structural diagram of a bottom view of a cover of the power electronic device according to an embodiment of the present application;
FIG. 4 shows a schematic structural diagram of a section view which is taken along line I-I in FIG. 2.
FIG. 5 shows a schematic structural diagram of a section view which is taken along line II-II in FIG. 2;
FIG. 6 shows a schematic structural diagram of a section view, taken along line I-I in FIG. 2, of another power electronic device according to an embodiment of the present application;
FIG. 7 shows a schematic structural diagram of a section view, taken along line I-I in FIG. 2, of another power electronic device according to an embodiment of the present application; and
FIG. 8 shows a schematic flowchart of a method for manufacturing a power electronic device according to an embodiment of the present application.
Description of reference numerals in the figures:
10. Casing; 11. Protrusion; 12. Body; 13. Cover; 131. Potting hole; 21. Circuit board; 22. Heat-generating component; 30. Electrically insulating material; 40. Heat spreader; 41. Threaded fastener; 42. Electrically insulating fastener; 51. First gap.
DETAILED DESCRIPTION
In order to have clearer understanding of the technical features, objectives, and effects of embodiments of the present application, specific implementations of embodiments of the present application are now described with reference to the accompanying drawings.
Referring to FIGS. 1-4, FIG. 1 shows a schematic diagram of a three-dimensional structure of a power electronic device according to an embodiment of the present application. FIG. 2 shows a schematic structural diagram of a top view of the power electronic device according to an embodiment of the present application. FIG. 3 shows a schematic structural diagram of a bottom view of a cover of the power electronic device according to an embodiment of the present application FIG. 4 shows a schematic structural diagram of a section view which is taken along line I-I in FIG. 2. This embodiment provides a power electronic device. The power electronic device includes: a casing 10, a circuit assembly, a heat spreader 40, and an electrically insulating material 30. The casing 10 has an accommodating cavity; the circuit assembly includes a circuit board 21 and a heat-generating component 22, the circuit board 21 is provided in the accommodating cavity, and the heat-generating component 22 is  provided on the circuit board 21; the heat spreader 40 is located in the accommodating cavity of the casing 10; and the electrically insulating material 30 surrounds the circuit board 21 and the heat-generating component 22, at least a part of the electrically insulating material 30 is located between the heat spreader 40 and the heat-generating component 22, at least a part of the heat spreader 40 is in contact with the electrically insulating material 30, a thermal conductivity of the heat spreader 40 is greater than a thermal conductivity of the electrically insulating material 30, and the thermal conductivity of the electrically insulating material 30 is greater than a thermal conductivity of air.
The casing 10 of the power electronic device is configured to support and protect the circuit component, the heat spreader 40, the electrically insulating material 30, and the like. Surrounding the circuit board 21 and the heat-generating component 22 in the circuit assembly with the electrically insulating material 30 not only protects the circuit board 21 and the heat-generating component 22 (e.g., waterproofing, dustproofing, and improving structural strength) , but also achieves insulation between the heat spreader 40 and the heat-generating component 22. In addition, since the thermal conductivity of the electrically insulating material 30 is greater than the thermal conductivity of air, the electrically insulating material 30 also has a heat dissipation effect, and, thus, can quickly dissipate the heat generated by the heat-generating component 22 elsewhere, thereby reducing the junction temperature of the heat-generating component 22. By providing the heat spreader 40 in the casing 10, and rendering at least a part of the heat spreader 40 in contact with the electrically insulating material 30, a contact area between the heat spreader 40 and the electrically insulating material 30 is ensured, and a sufficient heat transfer area is ensured as well. Further, since the thermal conductivity of the heat spreader 40 is greater than the thermal conductivity of the electrically insulating material 30, a thermal resistance in a process of transferring the heat generated by the heat-generating component 22 to the casing 10 is significantly reduced, compared with a thermal resistance when only the electrically insulating material 30 is filled in the accommodating cavity. As a result, a heat dissipation efficiency of the power electronic device having the heat spreader 40 is significantly improved, which helps to reduce the junction temperature of the heat-generating component 22 and to avoid the failure or service life reduction of the heat-generating component 22 caused by a very high temperature in a working environment.
The power electronic device may be an inverter, a convertor, or other power electronic  devices related to the power system, such as an outdoor power source, an outdoor LED, and an electric vehicle charger. In this embodiment, the description is provided by taking a micro inverter applied to a photovoltaic cell panel as an example, but those skilled in the art should understand that the power electronic device of this embodiment is not limited to this.
The electrically insulating material 30 filled in the power electronic device may be filled in the accommodating cavity of the casing 10, or be filled in only a part of the accommodating cavity. When the electrically insulating material is filled in a part of the accommodating cavity, it is only necessary to ensure that the electrically insulating material 30 surrounds the entire circuit assembly (i.e., surrounds the entire circuit board 21 and all components on the circuit board 21) , and is filled in a gap between the heat spreader 40 and the heat-generating component 22, such that at least a part of the surface of the heat spreader 40 is in contact with the electrically insulating material 30.
In a preferred implementation, in order to ensure the heat dissipation effect, the electrically insulating material 30 may surround the heat spreader 40, i.e., the electrically insulating material 30 covers all outer surfaces of the heat spreader 40, such that a heat transfer area between the heat spreader 40 and the electrically insulating material 30 is maximized, and such that the heat dissipation effect is high.
The electrically insulating material 30 may be any appropriate material, as long as aninsulativity between the heat-generating component 22 and the heat spreader 40 can be ensured, and the thermal conductivity of the electrically insulating material 30 is greater than the thermal conductivity of air. For example, the electrically insulating material 30 may be an electrically insulating film (e.g., a heat-conducting glue or a thermal pad) , which is arranged between the heat spreader 40 and the heat-generating component 22, such that the heat generated by the heat-generating component 22 is transferred to the electrically insulating film, transferred to the heat spreader 40 through the electrically insulating film, and then transferred to the casing 10 and an external environment through the heat spreader 40, so as to prevent heat from accumulating at the heat-generating component 22. The electrically insulating material 30 may also be appropriate potting materials. This is not limited in this embodiment. The potting material can protect the circuit board 21 and the heat-generating component 22 due to its good mechanical properties, and can ensure that the heat dissipation requirements are met due to the good heat-conducting properties of the potting material .
As shown in FIG. 1 to FIG. 3, in this embodiment, the casing 10 is provided with a protrusion 11 protruding toward inside of the accommodating cavity, and the heat spreader 40 is disposed on a wall of the protrusion 11 facing the heat-generating component 22. Thus, a distance between the heat spreader 40 and the heat-generating component 22 may be minimized. The smaller the distance is, the more easily the heat generated by the heat-generating component 22 is transferred to the heat spreader 40, and the more easily the heat is quickly transferred by the heat spreader 40 to a region far away from the heat-generating component 22 and at a low temperature, such that the heat transfer efficiency is higher, to accelerate the heat dissipation. Therefore, the heat spreader 40 is disposed close to the heat-generating component 22 as much as possible, such that heat accumulation at the heat-generating component 22 can be fully avoided, thereby increasing the heat dissipation efficiency, and achieving the purpose of effectively controlling the working temperature of the heat-generating component 22.
Preferably, the distance between the heat spreader 40 in a thickness direction of the casing 10 and the heat-generating component 22 is greater than or equal to 0.3 mm. Thus, not only the insulativity can be ensured, but also the heat dissipation effect can meet the needs. When the distance between the heat spreader 40 and the heat-generating component 22 is less than 0.3 mm (millimeter) , the insulation reliability between the heat spreader 40 and the heat-generating component 22 will be reduced, thus reducing the safety of the power electronic device. Therefore, the distance between the heat spreader 40 and the heat-generating component 22 is at least 0.3 mm in order to ensure the insulativity. In the case where the distance is ensured to be greater than or equal to 0.3 mm, the heat spreader 40 may be close to the heat-generating component 22 as far as possible.
A position of the protrusion 11 on the casing 10 may be adaptively set. This is not limited in this embodiment.
Alternatively, the casing 10 in this embodiment includes a body 12 and a cover 13, the cover 13 is detachably connected to the body 12, the accommodating cavity is enclosed by the cover 13 and the body 12 when the cover 13 is connected to the body 12, and the protrusion 11 is provided on the cover 13. Thus, the protrusion 11 is formed by a local part of the cover 13 that protrudes toward the inside of the accommodating cavity, which not only provides a mounting position close to the heat-generating component 22 for the heat spreader 40, but also will not affect thicknesses at other positions of the casing 10 and can accommodate other components of great  heights on the circuit board 21. In addition, compared with a casing provided with no protrusion 11, the protrusion 11 reduces the size of the accommodating cavity, thereby reducing the amount of the electrically insulating material 30 filled in the accommodating cavity, and reducing the costs of manufacturing the .
In this embodiment, the cover 13 and the body 12 may be made of a plastic material or other appropriate materials. Taking the plastic material as an example, the protrusion 11 on the cover 13 may be integrally molded on the cover 13 when the cover 13 is molded, or the protrusion 11 may be processed on the cover 13 by machining after the cover 13 is molded. This is not limited in this embodiment.
Alternatively, in this embodiment, a thickness of the cover 13 is consistent everywhere, and the protrusion 11 may be formed by protruding a part of the cover 13 toward the inside of the accommodating cavity. For example, the protrusion 11 is formed by protruding a part of the cover 13 corresponding to the heat-generating component 22 (e.g., the heat-generating component 22 is a chip in the power electronic device) inward. Thus, after the heat spreader 40 is mounted on the protrusion 11, the distance between the heat spreader 40 and the heat-generating component 22 is minimized. In addition, only a local part of the cover 13 protrudes inward, which will not affect heights at other positions of the accommodating cavity, such that the casing 10 can accommodate components (e.g., an inductor, and a capacitor) of great heights on the circuit board 21.
Of course, in other embodiments, the cover 13 may also form the protrusion 11 in other ways. This is not limited in this embodiment.
Besides providing the cover 13 with the protrusion 11, the cover 13 is also provided with a potting hole 131 through which the electrically insulating material 30 is potted into the accommodating cavity, such that the potting material can enter into the accommodating cavity. There may be one or more potting holes 131. This is not limited in this embodiment.
The heat-generating component 22 of the power electronic device not only includes the above chip (the chip may be surface mounted on the circuit board 21) , but also may include other components on the circuit board 21. In this embodiment, the description is provided by taking the heat-generating component 22 being two surface mounted chips on the circuit board 21 in a micro inverter as an example. Of course, in other embodiments, the heat-generating component 22 may also be other surface mounted devices on the circuit board 21.
Referring to FIG. 3 and FIG. 5, FIG. 5 shows a schematic structural diagram of a section view which is taken along line II-II in FIG. 2, and omits the electrically insulating material 30 in the accommodating cavity. In the case where the heat-generating component 22 includes a chip provided on the circuit board 21, a projection of the heat spreader 40 on a mounting surface of the circuit board 21 covers a projection of the chip on the mounting surface. Thus, the heat spreader 40 is provided corresponding to the heat-generating component 22, and the projection of the heat spreader 40 on the mounting surface covers the projection of the chip on the mounting surface, such that the heat spreader 40 has an enough area to fully absorb the heat generated by each heat-generating component 22 and quickly transfer the heat to an environment outside the casing 10.
A shape, a size, a material, and the like of the heat spreader 40 may be determined as required, e.g., determined based on at least one of a size of the heat-generating component 22, power consumption of the power electronic device, a circuit layout and a size of a PCB, or a size of the casing 10.
In a specific implementation, the heat spreader 40 may be, for example, a metal plate. The heat spreader may also be an insulating material with a thermal conductivity greater than that of the electrically insulating material 30. This is not limited in this embodiment. For example, the heat spreader may also be made of a thermal interface material, which is cheaper than the metal material and can satisfy the heat dissipation requirements.
A thickness of the metal plate ranges from 0.3 mm to 3 mm. The thickness of the metal plate within this range not only ensures the light weight of the metal plate but also reduces the production costs of the metal plate. When the thickness of the metal plate is less than 0.3mm, the heat dissipation performance of the metal plate will be affected because of the limited thickness of the metal plate. If the thickness of the heat metal plate is greater than 3 mm, then the weight of the heat metal plate will greatly increase the overall weight of the power electronic device, which is adverse to the light weight of the power electronic device.
Alternatively, in order to transfer the heat to a region far from the heat-generating component 22 as quickly as possible, such that a region in which the heat-generating component 22 is located is at a low temperature. The heat spreader 40 may be a polygonal plate or a plate of a complex shape.
In an embodiment, the heat spreader 40 not only includes a metal plate, but also includes an  extending portion (not shown in the figures) . The extending portion is connected to the metal plate or is an integral part of the metal plate, and at least a part of the extending portion is located in a cooling region of the accommodating cavity. A temperature of the cooling region is lower than a temperature of the region in which the heat-generating component 22 is located, a difference between the temperature of the cooling region and the temperature of the region in which the heat-generating component 22 is located is greater than or equal to a preset threshold.. Thus, the heat generated by the heat-generating component 22 can be quickly transferred to the cooling region at a low temperature through the extending portion, thereby further decreasing the temperature of the region in which the heat-generating component 22 is located.
A shape, a material, and a size of the extending portion may be determined as required. The extending portion may be integrally formed with the metal plate or the extending portion and the metal plate may be separately machined and then connected while molding.
The heat spreader 40 may be mounted on the casing 10 or on the circuit board 21.
For example, the power electronic device further includes a fastening structure, and the fastening structure connects the heat spreader 40 and the casing 10 to fasten the heat spreader 40 to the casing 10. The heat spreader 40 may be fastened to the casing 10 through the fastening structure.
In one feasible manner, the fastening structure includes a holding slot (not shown in the figures) provided on the casing 10, and the heat spreader 40 is embedded in the holding slot. With the holding slot, not only can the heat spreader 40 be fastened to the casing 10, but also the installation is convenient, fast and labor-saving.
The holding slot may be adapted to a shape of the heat spreader 40, at least a part of the heat spreader 40 is embedded in the holding slot, and the heat spreader 40 may be limited through a holding hook provided on the holding slot to prevent the heat spreader 40 from separation from the holding slot.
In another feasible manner, the fastening structure includes a threaded fastener 41, and a mounting hole is provided on the heat spreader 40. The threaded fastener 41 passes through the mounting hole and is in threaded connection with the casing 10 to fasten the heat spreader 40 on the casing 10. The threaded fastener 41 enables the heat spreader 40 to be connected to the casing 10 firmly and reliably.
The threaded fastener 41 may be a screw, a bolt, or the like, one or more mounting holes  may be provided on the heat spreader 40, and each mounting hole can allow a threaded fastener 41 to pass through. For example, as show in FIG. 3, 4 mounting holes are provided on the heat spreader 40.4 threaded fasteners 41 are arranged through the mounting holes each to each and are threaded with the casing 10 to fasten the heat spreader 40 on the casing 10.
Of course, in other embodiments, the heat spreader 40 may also be glued to the casing 10. This is not limited in this embodiment.
In order to ensure the heat dissipation effect and avoid the decrease of heat dissipation efficiency caused by a low thermal conductivity of air, in one case, the heat spreader 40 fits on a wall of the casing 10. Thus, there is no air gap between the heat spreader 40 and the casing 10, such that the heat dissipation efficiency will not be decreased because of air impact. For example, the heat spreader 40 is closely screwed on the casing 10 to ensure that the heat spreader 40 fits on the casing 10.
FIG. 7 shows a schematic structural diagram of a section view, taken along line I-I in FIG. 2, of another power electronic device according to an embodiment of the present application. A first gap 51 is provided between the heat spreader 40 and an inner wall of the casing 10, and the electrically insulating material 30 is filled in the first gap 51. Thus, it is ensured there is no air between the heat spreader 40 and the casing 10, thereby ensuring the heat dissipation efficiency.
As show in FIG. 6, when the heat spreader 40 is provided on the circuit board 21, if the heat spreader 40 includes a metal heat plate, then the power electronic device further includes an electrically insulating fastener 42, and the heat spreader 40 is mounted on the circuit board 21 through the electrically insulating fastener 42. Thus, the heat spreader 40 can be ensured to be connected to the circuit board 21, and the insulativity can be ensured.
The electrically insulating fastener 42 may be a bolt, a screw, or the like made of an electrically insulating material. The metal heat plate is connected to the circuit board 21 through the electrically insulating fastener 42. The metal heat plate is located above the heat-generating component 22 and is spaced from the heat-generating component 22 by a second gap, such that the electrically insulating material 30 can be filled into the second gap to achieve electrical insulation and heat transfer.
In order to further enhance the heat dissipation effect, the circuit board 21 includes a circuit board housing and an inner core of a heat-dissipating material, the circuit board housing has an inner cavity, the inner core of the heat-dissipating material is provided in the inner cavity, and a  thermal conductivity of the inner core of the heat-dissipating material is greater than a thermal conductivity of the circuit board housing. Thus, the heat dissipation capacity of the circuit board 21 can be improved, such that the heat generated by the heat-generating component 22 can not only be transferred to the casing 10 through the electrically insulating material 30 and the heat spreader 40, but also be transferred to the electrically insulating material 30 through the inner core of the heat-dissipating material in the circuit board 21 and the circuit board housing, and then be transferred to the casing 10 through the electrically insulating material 30, thereby improving the heat dissipation effect.
The circuit board housing may be a circuit board housing formed by a PCB. The inner core of the heat-dissipating material may be an inner core made of a metal or an inner core made of the electrically insulating material. This is not limited in this embodiment.
With reference to FIG. 4, when the heat spreader is not provided and when the heat spreader is provided, thermal resistance changes of a heat transfer path are analyzed below, to illustrate the principle of increasing the heat dissipation efficiency through the heat spreader.
When the heat spreader is not provided, the heat generated by the heat-generating component 22 is transferred along a first heat transfer path. The first heat transfer path is: the heat-generating component 22 → the electrically insulating material → the cover → an external environment. When the heat spreader 40 is provided and the heat spreader 40 fits on a wall of the cover, the heat generated by the heat-generating component 22 is transferred along a second heat transfer path. The second heat transfer path is: the heat-generating component 22 → the electrically insulating material between the heat-generating component 22 and the heat spreader 40 → the heat spreader 40 → the cover → the environment of the power electronic device, where if the electrically insulating material is filled between the heat spreader 40 and the cover, then the heat is transferred to the cover 13 through the heat spreader 40, and then through the electrically insulating material between the heat spreader 40 and the cover.
Compared with the first heat transfer path, the second heat transfer path is additionally provided with two thermal resistances, which are a thermal resistance of the heat spreader (denoted as R spreader) and a thermal resistance from the heat spreader to the cover (denoted as R spreader-housing) , respectively. R spreader is small because the thermal conductivity of the heat spreader is generally higher, especially higher than that of the electrically insulating material 30, and a thickness of the heat spreader is smaller. In addition, since a heat transfer area between the  heat spreader 40 and the cover 13 is increased, the thermal resistance R spreader-housing between the heat spreader 40 and the cover 13 is also smaller. Compared with the case where the heat spreader 40 is not provided, a distance between the casing and the heat-generating component 22 is decreased, a heat transfer area in the electrically insulating material is increased, and the heat spreader 40 has a higher thermal conductivity, such that a total thermal resistance from the heat-generating component 22 to the casing is decreased, thereby further improving the heat dissipation efficiency.
In conclusion, by additionally providing the heat spreader 40 inside the casing 10, the heat transfer efficiency in the electrically insulating material is improved, and then the heat dissipation efficiency is higher. It is validated through thermal simulation experiments that by additionally providing an aluminum heat plate with a thickness of 0.5 mm in the electrically insulating material 30, a junction temperature rise of the heat-generating component 22 will be decreased by 10%to 20%, and a junction temperature of the heat-generating component 22 will be kept at an optimal working temperature, thereby improving the overall reliability of the power electronic device. The junction temperature rise of the heat-generating component 22 refers to a difference between a temperature of the heat-generating component 22 with the junction temperature in a stable state after the heat-generating component runs for a period of time and a temperature of the power electronic device at startup. For example, at a moment when the power electronic device is started, the junction temperature of the heat-generating component 22 is a first temperature. In 10 minutes after the power electronic device is started, the junction temperature of the heat-generating component 22 is in a stable state, and the junction temperature at this time is a second temperature. The junction temperature rise is a difference between the second temperature and the first temperature. It is validated through experiments that in the case where the heat plate is provided, the junction temperature rise is decreased by 10%to 20%, compared with that in the case where no heat plate is provided.
As shown in FIG. 8, according to another aspect of the present invention, a method for manufacturing a power electronic device is provided. The method is used for manufacturing the power electronic device. The method includes the following steps:
Step S102: installing a circuit assembly and a heat spreader 40 of the power electronic device into an accommodating cavity of a casing 10, and spacing the heat spreader 40 from the heat-generating component 22 of the circuit assembly.
The circuit assembly may be mounted by bolting a circuit board 21 of the circuit assembly on the casing 10, and of course, may also be mounted by any other appropriate approach.
The heat spreader 40 may be mounted on the casing 10, or may be mounted on the circuit board 21. This is not limited in this embodiment, as long as there being a gap (i.e., a second gap) between the heat spreader 40 and the heat-generating component 22 can be ensured after the heat spreader 40 is mounted in the accommodating cavity.
Specifically, the heat spreader 40 may be connected to the protrusion 11 in the cover 13 of the casing 10 through a threaded fastener. Alternatively, the heat spreader 40 is connected to the circuit board 21 through an electrically insulating fastener 42 (e.g., a bolt made of an electrically insulating material) .
Step S104: providing an electrically insulating material 30 in the accommodating cavity of the casing 10, such that the circuit board 21 is surrounded by the electrically insulating material 30 and the heat-generating component 22 of the circuit assembly, and at least a part of the electrically insulating material 30 is located between the heat spreader 40 and the heat-generating component 22.
In a specific implementation, the electrically insulating material 30 may be provided in the accommodating cavity by potting the electrically insulating material 30 into the accommodating cavity through a potting hole 131 on the casing 10.
Taking the electrically insulating material 30 being an epoxy as an example, a fluid epoxy is potted into the accommodating cavity through the potting hole 131 on the cover 13, such that the epoxy is filled in a gap in the accommodating cavity, thereby discharging air. After a period of time after the epoxy is filled, the epoxy cures and surrounds the circuit board 21 and components on the circuit board 21 to protect and insulate the circuit board 21 and the components on the circuit board 21.
In addition, when the power electronic device is in operation, at least some of the components on the circuit board 21 generate heat (these components are the heat-generating components 22) , and the epoxy can further transfer the heat to the casing 10, thereby cooling the heat-generating components 22, and preventing the heat accumulation at the heat-generating component 22 from resulting in a very high junction temperature. A thermal conductivity of the heat spreader 40 is greater than that of the epoxy, such that the heat spreader can improve the efficiency of heat transfer to the casing 10, thereby further improving the heat dissipation effect.
According to an embodiment of the present application, the power electronic device has the following beneficial effects:
A heat spreader with a higher thermal conductivity is additionally provided in the electrically insulating material in the casing, to achieve the purpose of reducing the thermal resistance of the heat transfer path from the heat-generating component to the casing, thereby improving the heat dissipation efficiency.
At least a part of the cover is recessed toward inside of the accommodating cavity to form a protrusion, such that a distance between a wall of the protrusion facing the heat-generating component and the heat-generating component is reduced. Thus, compared with a casing without the protrusion, not only can the use amount of the electrically insulating material be reduced, but also the protrusion can be used to install the heat spreader made of the metal material, and the heat generated by the heat-generating component can be dissipated using the heat spreader and the entire electrically insulating material, thus reducing the junction temperature of the heat-generating component.
The heat spreader may be a rectangular heat plate. The heat plate may be equipped with threaded fasteners (e.g., screws) at four top corners, and is coupled to the casing through the threaded fasteners. The heat plate may fit on a wall of the cover, or there may also be a first gap between the heat plate and the cover, and the electrically insulating material may be filled in the first gap to ensure the efficiency of heat transfer from the heat plate to the cover. The heat plate may also be provided with a potting hole for the electrically insulating material to enter the first gap.
It should be understood that although the present specification is described in accordance with various embodiments, each embodiment does not only contain one independent technical solution, this narration in the specification is only for clearness. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment may also be appropriately combined to form other implementations that can be understood by those skilled in the art.
The above description is merely schematic specific implementations of embodiments of the present application, and is not intended to limit the scope of the embodiments of the present application. Any equivalent alterations, modifications, and combinations made by any person skilled in the art without departing from the concept and principle of the embodiments of the  present application shall fall within the protection scope of the embodiments of the present application.

Claims (16)

  1. A power electronic device, comprising:
    a casing (10) , the casing (10) having an accommodating cavity;
    a circuit assembly, the circuit assembly comprising a circuit board (21) and a heat-generating component (22) , the circuit board (21) being provided in the accommodating cavity, and the heat-generating component (22) being provided on the circuit board (21 ) ;
    a heat spreader (40) , the heat spreader (40) being located in the accommodating cavity of the casing (10) ; and
    an electrically insulating material (30) , the electrically insulating material (30) surrounding the circuit board (21) and the heat-generating component (22) , at least a part of the electrically insulating material (30) being located between the heat spreader (40) and the heat-generating component (22) , at least a part of the heat spreader (40) being in contact with the electrically insulating material (30) , a thermal conductivity of the heat spreader (40) being greater than a thermal conductivity of the electrically insulating material (30) , and the thermal conductivity of the electrically insulating material (30) being greater than a thermal conductivity of air.
  2. The power electronic device according to claim 1, wherein the heat spreader (40) is surrounded by the electrically insulating material (30) .
  3. The power electronic device according to claim 1, wherein the casing (10) is provided with a protrusion (11) protruding toward inside of the accommodating cavity, and the heat spreader (40) is disposed on the protrusion (11) facing the heat-generating component (22) .
  4. The power electronic device according to claim 3, wherein the casing (10) comprises a body (12) and a cover (13) , the accommodating cavity is enclosed by the cover (13) and the body (12) when the cover (13) is connected to the body (12) , and the protrusion (11) is provided on the cover (13) .
  5. The power electronic device according to claim 4, wherein the cover (13) is provided with a potting hole (131) through which the electrically insulating material (30) is potted into the accommodating cavity.
  6. The power electronic device according to claim 1, wherein the heat-generating component (22) comprises a chip provided on the circuit board (21) , and a projection of the heat spreader (40) on a mounting surface of the circuit board (21) covers a projection of the chip on  the mounting surface.
  7. The power electronic device according to claim 6, wherein the power electronic device further comprises a fastening structure, and the fastening structure connects the heat spreader (40) and the casing (10) to fasten the heat spreader (40) to the casing (10) .
  8. The power electronic device according to claim 1, wherein the heat spreader (40) fits on a wall of the casing (10) .
  9. The power electronic device according to claim 1, wherein there is a first gap between the heat spreader (40) and a wall of the casing (10) , and the electrically insulating material (30) is filled in the first gap.
  10. The power electronic device according to claim 1, wherein the power electronic device further comprises an electrically insulating fastener (42) , and the heat spreader (40) is mounted on the circuit board (21) through the electrically insulating fastener (42) .
  11. The power electronic device according to claim 1, wherein the circuit board (21) comprises a circuit board housing and an inner core of a heat-dissipating material, the circuit board housing has an inner cavity, the inner core of the heat-dissipating material is provided in the inner cavity, and a thermal conductivity of the inner core of the heat-dissipating material is greater than a thermal conductivity of the circuit board housing.
  12. The power electronic device according to any one of claims 1-11, wherein the heat spreader (40) comprises a metal plate, and a thickness of the metal plate ranges from 0.3 mm to 3 mm.
  13. The power electronic device according to claim 12, wherein the accommodating cavity comprises a cooling region, a temperature of the cooling region is lower than a temperature of a region in which the heat-generating component (22) is located, a difference between the temperature of the cooling region and the temperature of the region in which the heat-generating component (22) is located is greater than or equal to a preset threshold, the heat spreader (40) further comprises an extending portion, the extending portion is connected to the metal plate, and at least a part of the extending portion is located in the cooling region.
  14. The power electronic device according to claim 12, wherein a distance between the metal plate and the heat-generating component (22) in a thickness direction of the casing (10) is greater than or equal to 0.3 mm.
  15. A method for manufacturing a power electronic device, the method being used for  manufacturing the power electronic device according to any one of claims 1-4 and 6-14, the method comprising:
    installing a circuit assembly and a heat spreader (40) of the power electronic device into an accommodating cavity of the casing (10) , and spacing the heat spreader (40) from a heat-generating component (22) of the circuit assembly; and
    providing the electrically insulating material (30) in the accommodating cavity of the casing (10) , such that the electrically insulating material (30) surrounds a circuit board (21) and the heat-generating component (22) of the circuit assembly, and at least a part of the electrically insulating material (30) is located between the heat spreader (40) and the heat-generating component (22) .
  16. The method for manufacturing a power electronic device according to claim 15, the cover (13) is provided with a potting hole (131) , wherein the providing the electrically insulating material (30) in the accommodating cavity of the casing (10) comprises:
    potting the electrically insulating material (30) into the accommodating cavity through the potting hole (131) .
PCT/CN2020/106338 2020-07-31 2020-07-31 Power electronic device, and method for manufacturing the same WO2022021379A1 (en)

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US20030161132A1 (en) * 2002-02-05 2003-08-28 Mitsubishi Denki Kabushiki Kaisha Communication device
WO2013024038A1 (en) * 2011-08-16 2013-02-21 Osram Ag Electronic module, lighting device and manufacturing method of the electronic module
US20170273218A1 (en) * 2016-03-15 2017-09-21 Delphi International Operations Luxembourg S.A.R.L. Electronic device and method of assembling such a device
CN111050468A (en) * 2020-01-02 2020-04-21 台达电子企业管理（上海）有限公司 Electronic device and assembling method thereof

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Publication number Priority date Publication date Assignee Title
US20030161132A1 (en) * 2002-02-05 2003-08-28 Mitsubishi Denki Kabushiki Kaisha Communication device
WO2013024038A1 (en) * 2011-08-16 2013-02-21 Osram Ag Electronic module, lighting device and manufacturing method of the electronic module
US20170273218A1 (en) * 2016-03-15 2017-09-21 Delphi International Operations Luxembourg S.A.R.L. Electronic device and method of assembling such a device
CN111050468A (en) * 2020-01-02 2020-04-21 台达电子企业管理（上海）有限公司 Electronic device and assembling method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
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CN115066144A (en) * 2022-05-31 2022-09-16 华为数字能源技术有限公司 Packaging structure and photovoltaic optimizer

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