Power device, power device assembly, and related apparatus

This disclosure provides a power device, a power device assembly, and a related apparatus. The power device includes a package body and a plurality of pins. The package body includes a substrate structure, a semiconductor die, and a molded package. The semiconductor die is disposed on the substrate structure. The substrate structure includes a heat dissipation surface connectable to a heat sink. A first end of each pin is connected to the substrate structure. The molded package covers the semiconductor die and the substrate structure excluding the heat dissipation surface. A second end of each pin and the heat dissipation surface are both uncovered from the molded package. The second end of each pin includes a mounting surface connectable to a circuit board through a surface-mount technology to form an electrical connection.

CROSS-REFERENCE TO RELATED APPLICATION

This disclosure claims priority to Chinese Patent Application No. 202110184232.7, filed on Feb. 10, 2021, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to the field of semiconductor technologies, and in particular, to a power device, a power device assembly, and a related apparatus.

BACKGROUND

Power devices, also known as power electronic devices, are mainly used as components in circuits that convert electrical energy. In the packaging of a power device, a wave soldering process is usually used to implement an electrical connection between pins of the power device and a circuit board. However, such a process is relatively complicated. For example, it is required to open component holes on the circuit board and insert the pins into the corresponding component holes, which affects the processing efficiency. Therefore, a surface-mount technology (SMT) is usually used to implement the electrical connection between the pins of the power device and the circuit board.

A power device produces considerable heat during use, and a heat sink needs to be provided for the power device to dissipate heat. However, due to factors such as a tolerance in the size of the power device itself and an assembly tolerance thereof, the heat sink is not in close contact with the power device in the SMT device, causing a higher thermal resistance. Therefore, the heat dissipation efficiency is poor. At present, it is usually required to fasten a circuit board and a heat sink externally, so that the power device can cling to the heat sink, and the power device is sandwiched between the circuit board and the heat sink. However, there are still large voids between the power device and the heat sink. Today, as increasingly stringent heat dissipation requirements are imposed on power devices, how to improve the heat dissipation efficiency has become an urgent problem to be resolved.

SUMMARY

Embodiments of this disclosure provide a power device, a power device assembly, and a related apparatus that can improve the processing efficiency and the heat dissipation efficiency.

According to a first aspect, this disclosure provides a power device, including a plurality of pins and a package body. The package body includes a substrate structure, a semiconductor die, and a molded package, the semiconductor die being on the substrate structure, the substrate structure including a heat dissipation surface connectable to a heat sink, the molded package covering the semiconductor die and the substrate structure excluding the heat dissipation surface, a through hole extending through the substrate structure and the molded package, and the molded package covering an inner wall of the through hole. A first end of each pin is connected to the substrate structure. A second end of each pin and the heat dissipation surface are each uncovered from the molded package, the second end of each pin including a mounting surface connectable to a circuit board.

According to the power device provided in the first aspect of this disclosure, the second end of each pin thereof includes a mounting surface, and the mounting surface is connectable to the circuit board. Because the mounting surface of the power device can be directly connected to the circuit board, steps of opening component holes on the circuit board and inserting the pins into the component holes are omitted, and a processing process is simplified, which can improve the processing efficiency in assembling the power device with the circuit board, and reduce costs.

In addition, the power device is provided with the through hole that extends through the substrate structure and the molded package and is configured to pass through a fastener to connect the circuit board, the power device, and the heat sink. In this way, the power device is directly crimped onto the heat sink, increasing an area of fitting between the heat dissipation surface of the power device and an assembling surface of the heat sink, and reducing voids on an interface between the heat dissipation surface of the power device and the heat sink, thereby reducing thermal resistance of the power device and the power device assembly, and improving heat dissipation efficiency of the power device.

According to the first aspect, in a first possible implementation, the substrate structure includes a first surface and a second surface that are disposed opposite each other, the semiconductor die is disposed on the first surface of the substrate structure, and the heat dissipation surface is disposed on the second surface of the substrate structure. The semiconductor die and the heat dissipation surface are respectively disposed on two opposite surfaces of the substrate structure and do not interfere with each other, facilitating device arrangement.

According to the first aspect or the first possible implementation of the first aspect of this disclosure, in a second possible implementation, the substrate structure includes a metal substrate having a thermally conductive insulation layer and one metal layer that are laminated to one another, and the semiconductor die is disposed on the surface of the metal layer opposed from the thermally conductive insulation layer. The through hole extends through the thermally conductive insulation layer and the metal layer, and the first end of each pin is connected to the metal layer. The metal substrate includes the thermally conductive insulation layer and the metal layer with good thermal conductivity, improving the heat dissipation performance of the power device and improving the reliability of the power device. The metal substrate can optionally be a single-sided metal substrate, which is beneficial to the reduction of the thickness of the power device, thereby reducing the size of the power device.

In a third possible implementation of the first aspect of this disclosure, the substrate structure includes a metal substrate that includes a thermally conductive insulation layer and two metal layers. The thermally conductive insulation layer is sandwiched between the two metal layers, and the semiconductor die is disposed on the side of one of the metal layers opposed from the thermally conductive insulation layer. Because there are two metal layers, that is, the metal substrate is a double-sided metal substrate, the two metal layers can effectively improve the thermal conductivity of the power device, further improving the heat dissipation performance and the reliability of the power device.

In a fourth possible implementation of the first aspect of this disclosure, the substrate structure includes a heat dissipation substrate connected to the surface of the metal substrate opposed from the semiconductor die. The heat dissipation surface is disposed on the surface of the heat dissipation substrate opposed from the metal substrate to enhance the heat dissipation performance of the power device and improve the heat dissipation efficiency of the power device.

In a fifth possible implementation of the first aspect of this disclosure, the heat dissipation surface is disposed on the surface of the metal substrate opposed from the semiconductor die. The heat dissipation surface is directly disposed on the metal substrate, that is, the metal substrate can be directly assembled with the heat sink, which is beneficial to the reduction of the thickness of the power device and the simplification of the structure of the power device.

In a sixth possible implementation of the first aspect of this disclosure, the package body further includes a top portion and a bottom portion that are disposed opposite each other, an orientation of the mounting surface is the same as an orientation of the bottom portion opposed from the top portion, and the heat dissipation surface is disposed on the surface of the top portion opposed from the bottom portion. With the orientation of the heat dissipation surface different from the orientation of the mounting surface, when the power device, the circuit board, and the heat sink are assembled together, the power device can be sandwiched between the circuit board and the heat sink, which improves the flexibility of device arrangement on the circuit board.

In a seventh possible implementation of the first aspect of this disclosure, the package body further includes a top portion and a bottom portion that are disposed opposite each other, an orientation of the mounting surface is the same as an orientation of the bottom portion opposed from the top portion, and the heat dissipation surface is disposed on the surface of the bottom portion opposed from the top portion. The orientation of the heat dissipation surface is the same as the orientation of the mounting surface, and when the power device, the circuit board, and the heat sink are assembled together, the heat sink can pass through the circuit board, which can effectively reduce the thickness of the assembly and enrich forms of the assembly.

In an eighth possible implementation of the first aspect of this disclosure, the heat dissipation surface includes at least two heat dissipation surface units, and a gap between adjacent heat dissipation surface units is filled with the molded package. The heat dissipation surface includes at least two separate heat dissipation surface units, which can effectively reduce a risk that the heat dissipation surface is easily damaged and fractured by force due to its excessively large area. For example, when the substrate structure includes the metal substrate and the heat dissipation substrate, the surface of the heat dissipation substrate opposed from the metal substrate is used as the heat dissipation surface, and the heat dissipation substrate may be divided into two or more independent units to alleviate a risk of fracture of the heat dissipation substrate by a mechanical stress due to its excessively large area. In some implementations, the substrate structure includes the metal substrate but omits the heat dissipation substrate. The surface of the metal substrate opposed from the semiconductor die provides the heat dissipation surface. The surface of the metal substrate opposed from the semiconductor die may be divided into two or more independent units to alleviate a risk that the heat dissipation surface is easily fractured by a mechanical stress due to its excessively large area.

In a ninth possible implementation of the first aspect of this disclosure, the package body includes a top portion, a bottom portion, and side portions. The top portion and the bottom portion are disposed opposite each other, the side portions are connected between the bottom portion and the top portion, and an orientation of the bottom portion is the same as an orientation of the mounting surface. The pin extends in SOP (small outline package), the first end of each pin is connected to the side portion, and the plurality of pins are distributed along the side portions. The package of the power device is flexible in the direction and number of the pins, which facilitates an electrical connection between the power device and the circuit board.

In a tenth possible implementation of the first aspect of this disclosure, the package body includes a top portion, a bottom portion, and side portions. The top portion and the bottom portion are disposed opposite each other, the side portions are connected between the bottom portion and the top portion, and an orientation of the bottom portion is the same as an orientation of the mounting surface. The pin extends in HSOP (small outline package with heat sink), the first end of each pin is connected to the bottom portion, and the plurality of pins are distributed along the side portions. The package of the power device is flexible in the direction and number of the pins, which facilitates an electrical connection between the power device and the circuit board.

In an eleventh possible implementation of the first aspect of this disclosure, the metal substrate includes at least two mounting units. At least two semiconductor dies are provided, and each mounting unit is provided with at least one semiconductor die. The number of mounting units may be set based on a type of the semiconductor die, which improves the flexibility in design of the power device.

According to a second aspect, this disclosure provides a power device assembly, including a power device according to the first aspect or the first to the eleventh possible implementations of the first aspect, a circuit board, a heat sink, and a fastener, where a mounting surface of a second end of a pin of the power device and the circuit board are connected together to form an electrical connection. The circuit board is provided with a cutout extending through the circuit board. The heat sink includes an assembling surface, and the assembling surface is provided with a connecting hole. The fastener passes through the cutout, a through hole of the power device, and the connecting hole, so that a heat dissipation surface of the power device is connected to the assembling surface.

According to the power device assembly provided in the second aspect of this disclosure, because the mounting surface of the power device is directly connected to the circuit board to form the electrical connection, steps of opening component holes on the circuit board and inserting the pins into the component holes are omitted, and a processing process is simplified, which can improve the processing efficiency in assembling the power device with the circuit board, and reduce costs.

In addition, the fastener directly passes through the through hole of the power device and is connected to the heat sink so that the heat dissipation surface is connected to the assembling surface. This increases an area of fitting between the heat dissipation surface of the power device and the assembling surface and reduces voids on an interface between the heat dissipation surface of the power device and the assembling surface, thereby reducing a thermal resistance of the power device and the power device assembly and improving the heat dissipation efficiency of the power device.

Pins of an existing power device and a circuit board are electrically connected by using a wave soldering process. When the power device, the circuit board, and a heat sink are assembled, the power device, the heat sink, and the circuit board are first connected to a fastener, and then the pins of the power device are inserted into corresponding component holes of the circuit board for subsequent soldering. If other electronic devices are required on the circuit board, a surface-mount technology (such as reflow soldering) is usually used to mount them onto the circuit board. As such, when the power device and other electronic devices are disposed on the circuit board, different processes are required, which makes the assembly process complicated. In this disclosure, the pins of the power device are directly connected to the circuit board, and the mounting manner is the same as that of other electronic devices, thereby simplifying the assembly process of the power device assembly and the related apparatus.

According to the second aspect, in a first possible implementation of the second aspect of this disclosure, a package body of the power device further includes a bottom portion and a top portion that are disposed opposite each other. An orientation of the mounting surface is the same as an orientation of the bottom portion opposed from the top portion, the heat dissipation surface is disposed on the surface of the top portion opposed from the bottom portion, the fastener successively passes through the cutout, the through hole, and the connecting hole, and the circuit board, the package body, and the heat sink are laminated to one another. With the orientation of the heat dissipation surface different from the orientation of the mounting surface, when the power device, the circuit board, and the heat sink are assembled together, the power device can be sandwiched between the circuit board and the heat sink, which improves the flexibility of device arrangement on the circuit board. In addition, the heat sink does not need to pass through the circuit board, and a diameter of the cutout of the circuit board does not need to be too large, provided that the fastener can pass therethrough.

In a third possible implementation of the second aspect of this disclosure, the fastener includes a rod and a cap connected to one end of the rod, the rod passes through and is connected to the cutout, the through hole, and the connecting hole. The circuit board is sandwiched between the cap and the surface of the package body opposed from the heat sink, and the cap is disposed on the side of the circuit board opposed from the package body. The cap can effectively prevent the circuit board and the power device from falling off the rod, and improve the reliability of the connection between the circuit board, the power device, and the heat sink, thereby improving the reliability of the power device assembly.

In a fourth possible implementation of the second aspect of this disclosure, a package body further includes a bottom portion and a top portion that are disposed opposite each other. An orientation of the mounting surface is the same as an orientation of the bottom portion opposed from the top portion. The heat dissipation surface is disposed on the surface of the bottom portion opposed from the top portion, with the heat sink passing through the cutout. The fastener successively passes through the through hole and the connecting hole, and the package body and the heat sink are laminated to one another. The heat sink can pass through the circuit board, which is beneficial to the reduction of dimensions of the power device assembly.

With reference to the second and the fourth possible implementations of the second aspect of this disclosure, depending on a position of the heat dissipation surface disposed on the power device, an assembly manner (example) of the power device, the circuit board, and the heat sink may be selected. For example, when the heat dissipation surface is disposed on the surface of the top portion of the power device opposed from the bottom portion of the power device, the pins may be connected to the bottom surface of the circuit board, and the heat sink does not need to pass through the circuit board, that is, the circuit board does not require an open window design corresponding to the heat sink. When the heat dissipation surface is disposed on the surface of the bottom portion of the power device opposed from the top portion, the heat sink may pass through the circuit board, and the pins may be connected to the top surface of the circuit board. In this way, different power devices are packaged together in a variety of forms, which improves the flexibility of device arrangement.

In a fifth possible implementation of the second aspect of this disclosure, the fastener includes a rod and a cap connected to one end of the rod, the rod passing through and is connected to the through hole, the cutout, and the connecting hole. The package body is sandwiched between the cap and the heat dissipation surface. The cap is disposed on the side of the package body opposed from the heat sink, and the cap is disposed on the side of the circuit board opposed from the package body. Positioning of the cap in this manner can effectively prevent the circuit board and the power device from falling off the rod, and improve the reliability of the power device.

In a sixth possible implementation of the second aspect of this disclosure, the power device assembly includes a thermally conductive interface layer that is provided with a mounting hole extending through the thermally conductive interface layer. The thermally conductive interface layer is sandwiched between the heat dissipation surface and the heat sink, and the fastener passes through the mounting hole. The thermally conductive interface layer can improve the efficiency in heat transfer from the power device to the heat sink, thereby improving the heat dissipation efficiency of the power device assembly.

In a seventh possible implementation of the second aspect of this disclosure, the thermally conductive interface layer includes one of a graphite thermal pad, a nano copper hook-and-loop tape, a thermal grease layer, and a thermal gel.

In an eighth possible implementation of the second aspect of this disclosure, the power device assembly is provided with a washer, the washer being encircled on the rod and sandwiched between the cap and the circuit board. Alternatively, the washer can be sandwiched between the cap and the package body. The washer allows for enlarging a stress area of the circuit board and prevents stress on a local area of the circuit board from being excessively large and causing damages to the circuit board.

According to a third aspect, this disclosure provides an electric energy conversion apparatus, including a power device assembly according to the second aspect or the first to the eighth possible implementations of the second aspect of this disclosure.

According to a fourth aspect, this disclosure provides an electric energy conversion device, including an electric energy conversion apparatus according to the third aspect.

According to a fifth aspect, this disclosure provides an assembling method for a power device assembly according to the second aspect or the first to the eighth possible implementations of the second aspect of this disclosure, where the power device assembly includes a power device, a circuit board, and a heat sink, and the power device includes a plurality of pins and a package body. The package body includes a substrate structure, a semiconductor die, and a molded package, the semiconductor die is disposed on the substrate structure, the substrate structure includes a heat dissipation surface, the molded package covers the semiconductor die and the substrate structure excluding the heat dissipation surface, a through hole extends through the substrate structure and the molded package, and the molded package covers an inner wall of the through hole. A first end of each pin is connected to the substrate structure, a second end of each pin and the heat dissipation surface each are uncovered from the molded package, and the second end includes a mounting surface. The heat sink includes an assembling surface provided with a connecting hole. The assembling method includes the following steps: the mounting surface of the pin is connected to the circuit board, and a fastener passes through the through hole, a cutout formed in the circuit board, and the connecting hole so that the heat dissipation surface is connected to the assembling surface.

According to the fifth aspect, in a first possible implementation of the fifth aspect of this disclosure, the package body further includes a bottom portion and a top portion that are disposed opposite each other. An orientation of the mounting surface is the same as an orientation of the bottom portion opposed from the top portion, and the heat dissipation surface is disposed on the surface of the top portion opposed from the bottom portion. A fastener passes through the through hole, the cutout, and the connecting hole includes: the fastener successively passes through the cutout, the through hole, and the connecting hole, so that the circuit board, the package body, and the heat sink are laminated to one another.

In a second possible implementation of the fifth aspect of this disclosure, the fastener includes a rod and a cap connected to one end of the rod. The fastener successively passes through the cutout, the through hole, and the connecting hole so that the circuit board is sandwiched between the cap and the surface of the package body opposed from the heat sink. The cap is disposed on the side of the circuit board opposed from the package body.

In a third possible implementation of the fifth aspect of this disclosure, the package body includes a bottom portion and a top portion that are disposed opposite each other. The orientation of the mounting surface is the same as the orientation of the bottom portion opposed from the top portion. The heat dissipation surface is disposed on the surface of the bottom portion opposed from the top portion. A fastener passes through the through hole, the cutout, and the connecting hole. The heat sink passes through the cutout, and the fastener successively passes through the through hole and the connecting hole so that the package body and the heat sink are laminated to one another.

In a fourth possible implementation of the fifth aspect of this disclosure, the fastener includes a rod and a cap connected to one end of the rod. The fastener passes through the through hole, the cutout, and the connecting hole so that the package body is sandwiched between the cap and the heat dissipation surface, and the cap is disposed on the side of the package body opposed from the heat sink.

In a fifth possible implementation of the fifth aspect of this disclosure, before the mounting surface of the pin is connected to the circuit board, the assembling method includes a thermally conductive interface layer is provided between the heat dissipation surface and the assembling surface, where the thermally conductive interface layer is formed with a mounting hole extending through the thermally conductive interface layer. The fastener passes through the through hole, the cutout, the connecting hole and the mounting hole.

In a sixth possible implementation of the fifth aspect of this disclosure, before the thermally conductive interface layer is provided between the heat dissipation surface and the assembling surface, the assembling method includes providing a film layer on the assembling surface and deoxidizing the film layer. The film layer is a metal layer. Provision of the thermally conductive interface layer includes the nano copper hook-and-loop tape between the heat dissipation surface and the assembling surface, and the interface layer is cured to form the thermally conductive interface layer.

In a sixth possible implementation of the fifth aspect of this disclosure, before the thermally conductive interface layer is provided between the heat dissipation surface and the assembling surface, the assembling method includes providing a graphite thermal pad that is fabricated in advance to form the thermally conductive interface layer.

In a seventh possible implementation of the fifth aspect of this disclosure, before the thermally conductive interface layer is provided between the heat dissipation surface and the assembling surface, the assembling method includes: the coating the assembling surface with a thermal grease or a thermal gel to form the thermally conductive interface layer.

DESCRIPTION OF EMBODIMENTS

At present, many industrial-grade energy products and the like require a large number of densely arranged high-power devices, which generate considerable heat. Therefore, such products need to have a good heat dissipation performance.

In the packaging of a power device, a soldering process is usually used to implement an electrical connection between the power device and a circuit board. One of the commonly used soldering processes is wave soldering. In wave soldering, molten solder (such as lead-tin alloys) is sprayed by an electric pump or an electromagnetic pump into a solder wave as required by the design. The solder wave may also be formed by injecting nitrogen into a solder pool. A circuit board (which may be referred to as a printed circuit board, a printed board, a plug-in board, a wiring board, or the like) pre-loaded with components is passed through the solder wave, implementing soft soldering for mechanical and electrical connections between welding ends or pins (also referred to as prongs) of the components and pads of the circuit board. Wave soldering includes normal wave soldering and selective wave soldering. Regardless of whether it is normal wave soldering or selective wave soldering, component holes are required on the circuit board. When the power device is electrically connected to the circuit board, pins of the power device are first inserted into the component holes. Then, the pins are soldered into the component holes of the circuit board. After the soldering is completed, if the length of the pins in the direction perpendicular to the board surface is too long, the extra length of the pins further needs to be cut off. It can be learned that many steps are required to implement the electrical connection between the power device and the circuit board through soldering, resulting in a low efficiency and high manufacturing costs.

To improve the processing efficiency of a power device assembly and reduce manufacturing costs, SMT (surface-mount technology) may be used to implement an electrical connection between pins of a power device and a circuit board.

The power device is usually equipped with a heat sink to dissipate a lot of heat produced when the power device is in operation. Due to factors such as a tolerance in the size of the power device itself and an assembly tolerance thereof, the heat sink is not in close contact with the power device in the SMT, causing a higher thermal resistance and affecting the heat dissipation efficiency of the assembly. To resolve the problem that the heat sink is not in close contact with the power device, a fastener is usually required to fasten a circuit board and a heat sink, so that the power device is sandwiched between the circuit board and the heat sink, and the power device can cling to the heat sink. However, there are still large voids between the power device and the heat sink, resulting in a large thermal resistance of the power device and the assembly thereof, and it is difficult to meet increasingly stringent heat dissipation requirements on power devices.

This disclosure provides a power device and a corresponding power device assembly (including a heat sink) thereof, which facilitate the reduction of voids on an interface between the power device and the heat sink, thereby improving the heat dissipation efficiency.

The power device and assembly provided in this disclosure can be applied to various electric energy conversion apparatuses that require high-power devices, and the electric energy conversion apparatuses can further be connected to an electric energy conversion device to complete various power functions of the device. For example, the power device assembly of this disclosure can be applied in the field of electric vehicle power systems, that is, the electric energy conversion device may be included in an electric vehicle. The electric energy conversion apparatus may be a motor controller, and the power device may be a power conversion unit assembled in the motor controller. The electric energy conversion apparatus may also be an on-board charger (OBC), and the power device may be an energy conversion unit. The electric energy conversion apparatus may also be a low-voltage control power supply, and the power device may be a DC-DC conversion unit therein, or the like. In addition, the power device assembly of this disclosure is not limited to the field of electric vehicles, but can also be widely used in the field of conventional industrial control, for example, can be applied to an uninterruptible power supply (UPS) in a data center, an inverter of a photovoltaic power generation device, a power supply of a server, and the like.

The following further describes in detail this disclosure with reference to the accompanying drawings.

Referring toFIG.1, a first implementation provides a power device assembly100, including a power device20, a circuit board (printed circuit board, PCB)40, a heat sink60, and a fastener70.

The power device20is electrically connected to the circuit board40, and the power device20is sandwiched between the circuit board40and the heat sink60. The heat sink60dissipates heat for the power device20and the circuit board40. The heat sink60may use a heat dissipation method such as air cooling, water cooling, or the like, which is not limited in this disclosure. The circuit board40is a board-level structure used to provide the power device20, another chip package structure, and the like.

The power device20is provided with a through hole21, and the circuit board40is provided with a cutout41. The heat sink60includes an assembling surface62, and the assembling surface62is provided with a connecting hole64. The fastener70passes through the through hole21, the cutout41, and the connecting hole64, so that the power device20and the heat sink60are connected. Because the fastener70directly passes through the power device20and crimps the power device20onto the heat sink60, the power device20closely fits the heat sink60, increasing an area of fitting between the power device20and the heat sink60, and effectively reducing voids on an interface between the power device20and the heat sink60, thereby reducing a thermal resistance of the power device20and the power device assembly100, and improving the heat dissipation efficiency of the power device20and the power device assembly100.

The following describes various parts of the foregoing power device assembly100in detail.

Referring toFIG.1andFIG.2, the power device20includes a package body201and pins203. The package body201includes a bottom portion2011, a top portion2013, and side portions2015. The top portion2013and the bottom portion2011are disposed opposite each other. The surface of the top portion2013opposed from the bottom portion2011faces the heat sink60. The surface of the bottom portion2011opposed from the top portion2013faces the circuit board40. In this implementation, the pins203may extend in a small outline package (SOP), that is, the pins203extend from the side portions2015of the package body201and have a wing-like structure (for example, an L- or J-shape). A first end of each pin203is connected to the side portion2015, and a second end of each pin203protrudes from the side portion2015. The second end of each pin203includes a mounting surface2031, and the mounting surface2031of the pin203is connected to the circuit board40to form an electrical connection between the power device20and the circuit board40. The mounting surface2031is connected to the circuit board40through a surface-mount technology (SMT). SMT is a circuit assembly technology in which no-pin or short-lead surface assembly devices are connected to the surface of a circuit board or another substrate, and then soldered and assembled by using methods such as reflow soldering or dip soldering. In this implementation, an orientation of the mounting surface2031is the same as an orientation of the bottom portion2011opposed from the top portion2013.

In the power device assembly100provided in the first implementation of this disclosure, to form the electrical connection between the power device20and the circuit board40, the mounting surface2031is directly connected to the circuit board40. For example, a reflow soldering process is used in which air or nitrogen is heated to a high enough temperature and then blown to the circuit board onto which the components are already bonded, so that solder on both sides of the components is molten and bonded to the circuit board. There is no need to cut off excessively long pins, which simplifies the steps of assembly between the power device20and the circuit board40, and facilitates reduction of manufacturing costs of the power device assembly100. In addition, the pins203of the power device20may be first soldered to the circuit board40, and then the power device20is crimped onto the circuit board40, which improves the assembling efficiency.

With reference toFIG.3, from the top view, the package body201may be roughly square, that is, there are four side portions2015. The plurality of pins203is distributed along the four side portions2015of the package body201so that the plurality of pins203extend from the four side portions2015(that is, toward four directions) of the package body201. It can be understood that this disclosure does not limit the distribution of the plurality of pins203along the four side portions2015of the package body201. In other implementations, the package of the power device20may have the pins extending toward at least two directions, that is, the plurality of pins203is distributed along at least two side portions2015of the package body201. This disclosure does not limit the shape of the package body201either, and the package body201may also be of a circular, triangular, polygonal, or irregular shape, or the like.

It can be understood that this disclosure does not limit how the pins203extend, either. The pins203may be configured based on an internal topology and functional requirements of the power device20. The pin spacing and shape can be freely allocated on the premise that a distance between the pins203meets the requirements. For example, the pins203may extend in a heat sink small outline package (small outline package with heat sink, HSOP), and the pins203extend from the side portions2015. The pins203extend from the side portions2015of the package body201, so that the package of the power device20is flexible in the direction and number of the pins.

Referring toFIG.4, the package body201includes a substrate structure22, a semiconductor die24, and a molded package26. The semiconductor die24is disposed on the substrate structure22, and the substrate structure22further includes a heat dissipation surface29connectable to the heat sink60. The molded package26covers the semiconductor die24and the substrate structure22excluding the heat dissipation surface29. The through hole21extends through the substrate structure22and the molded package26, and is configured to pass through the fastener70. The inner wall of the through hole21is covered with the molded package26to have insulating properties. The first end of each pin203is connected to the substrate structure22and the second end of each pin203is uncovered from the molded package26to form an electrical connection to the circuit board40. The heat dissipation surface29is uncovered from the molded package26and is configured to conduct heat produced by the power device20to the heat sink60.

The through hole21and an electrical structure (not shown) of the substrate structure22are insulated from each other to improve the reliability of the power device20.FIG.1toFIG.4only show one through hole21as an example. It can be understood that the number of through holes21is not limited in this disclosure. In other implementations, there may be two or more through holes21, and the number of the through holes is set based on different requirements of the power device20.

The substrate structure22includes a first surface220and a second surface221that are disposed opposite each other. The semiconductor die24is disposed on the first surface220, and the heat dissipation surface29is disposed on the second surface221.

More specifically, the substrate structure22includes a metal substrate222and a heat dissipation substrate226that are laminated. The through hole21extends through the metal substrate222and the heat dissipation substrate226. The first surface220is the surface of the bottom layer of the metal substrate222opposed from the heat dissipation substrate226. The second surface221is the surface of the heat dissipation substrate226opposed from the metal substrate222. The heat dissipation surface29is the surface of the heat dissipation substrate226opposed from the metal substrate222, and the molded package26covers the metal substrate222and the remaining surfaces of the heat dissipation substrate226other than the heat dissipation surface29.

The metal substrate222includes a thermally conductive insulation layer2222and a metal layer2224that are laminated, and the semiconductor die24is disposed on the surface of the metal layer2224opposed from the thermally conductive insulation layer2222. The through hole21extends through the thermally conductive insulation layer2222and the metal layer2224, and the first end of each pin203is connected to the metal layer2224provided with the semiconductor die24.

In this implementation, the metal substrate222is a substrate prepared by using a direct bonded copper (DBC) process, that is, the metal layer2224is a copper layer. DBC refers to a process in which one or both sides of a ceramic substrate is/are clad with copper, and the copper and a ceramic layer are bonded together at high temperature. The metal substrate222may also be prepared by using other processes, for example, a direct plate copper (DPC) process. DPC refers to a method in which a ceramic substrate is plated with a copper layer by vacuum sputtering, and then a development process is used to manufacture electrical circuits. For another example, active metal brazing (AMB) may be used, and AMB refers to a method that relies on active brazing filler metal for high-temperature metallurgical bonding of aluminum nitride and oxygen-free copper. It can be understood that the metal substrate222is not limited to a copper-clad ceramic substrate, but may also be a copper-clad metal substrate, or the like. The copper-clad metal substrate uses metal (such as aluminum, copper, iron, or molybdenum) as a substrate that is covered with a thermally conductive insulation layer, and then a copper layer is covered on the side surface of the thermally conductive insulation layer opposed from the metal substrate. It can be understood that the metal layer2224is not limited to a copper layer, but may alternatively be another metal layer, for example, a gold layer. The thermally conductive insulation layer2222includes aluminum nitride. Alternatively, the thermally conductive insulation layer2222may include another insulating material, such as aluminum oxide.

FIG.5is a schematic diagram of a structure in which the metal substrate222is clad with copper on both sides, where there are two metal layers2224. The thermally conductive insulation layer2222includes a first surface2225and a second surface2226that are disposed opposite each other. One metal layer2224is connected to the first surface2225of the thermally conductive insulation layer2222, and the other metal layer2224is connected to the second surface2226of the thermally conductive insulation layer2222. The semiconductor die24is disposed on the side of the metal layer2224on the first surface2225and opposed from the thermally conductive insulation layer2222. That is, the two metal layers2224are respectively disposed on the two opposite surfaces of the thermally conductive insulation layer2222. In other words, the metal substrate222is a double-sided copper-clad metal substrate, and the through hole21extends through the thermally conductive insulation layer2222and the metal layers2224of the metal substrate222. The metal layers2224are made of a copper material with good thermal conductivity, so that the metal substrate222has good thermal conductivity. The double-sided copper-clad metal substrate has two metal layers2224so that the thermal conductivity and reliability of the power device20are improved.

The heat dissipation substrate226is connected to the surface of the metal substrate222opposed from the semiconductor die24. In this implementation, the heat dissipation substrate226is connected to the metal layer2224that is not provided with the semiconductor die24to enhance the heat dissipation performance of the power device20and improve the heat dissipation efficiency of the power device20. In this implementation, the heat dissipation substrate226may be connected to the surface of the metal substrate222opposed from the semiconductor die24by using a bonding layer224. The bonding layer224may be a welding layer. The welding layer has a good bonding performance and thermal conductivity, so that the welding layer can not only firmly connect the heat dissipation substrate226and the metal substrate222, but can also well conduct heat produced by the metal substrate222to the heat dissipation substrate226for heat dissipation.

It can be understood that this disclosure does not limit the metal substrate222to be a double-sided metal substrate. In other implementations, there may be one metal layer2224in the metal substrate222, that is, the metal substrate222is single-sided.FIG.6is a schematic diagram of a structure when the metal substrate222is clad with copper on a single side. The heat dissipation substrate226is disposed on the side of the thermally conductive insulation layer2222opposed from the metal layer2224.

It can be understood that the bonding layer224may alternatively be omitted in the foregoing solution, and the heat dissipation substrate226and the metal substrate222are directly molded together by using the molded package26.

The semiconductor die24includes electronic components, such as electronic components having a power conversion function: a high-power transistor, a thyristor, a bidirectional thyristor, a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), a diode, a silicon controlled rectifier (SCR), SiC, GaN, and the like. A connection manner of internal devices of the semiconductor die24is not limited. The devices may be connected in series or parallel to form a functional circuit, or the devices may be independent cells. In this way, the number of devices can be effectively reduced, and copper wiring connection forms required for the use of discrete devices on the circuit board can be reduced, optimizing the design of dimensions of the circuit board, thereby reducing the volume of the power device. A topology of the semiconductor die24may be single-tube, half-bridge, H-bridge, three-phase full-bridge, three-level, or the like. For example, the semiconductor die24includes an IGBT (as shown inFIG.7a) half-bridge topology and a MOSFET (as shown inFIG.7b) half-bridge topology. The semiconductor die24may further integrate device drive protection control and junction temperature protection. It can be understood that this disclosure does not limit the type, the topological structure, and the number of semiconductor dies24. The letters inFIG.7aandFIG.7brepresent symbols of the pins. For example, P1, P2, and P3refer to power pin numbers, T1and T2refer to temperature sampling pin numbers, G1and S1refer to switching tube drive pin numbers, Isense1and Isense2refer to current sampling pin numbers, and so on, which are not listed herein.

Referring back toFIG.4, the power device20includes a bonding wire27disposed on the molded package26. The bonding wire27is connected between the semiconductor die24and the metal layer2224provided with the semiconductor die24, and is configured to connect the semiconductor die24and an internal electrical structure in the metal substrate222.

Referring back toFIG.1, the circuit board40includes a top surface (T surface)43and a bottom surface (B surface)44. The cutout41extends through the top surface43and the bottom surface44of the circuit board40. When the power device20is connected to the circuit board40, the surface of the bottom portion2011opposed from the top portion2013is disposed facing the circuit board40, and the heat dissipation surface29of the power device20is on the side of the top portion2013opposed from the circuit board40. In this implementation, an orientation of the heat dissipation surface29is opposite an orientation of the mounting surface2031, that is, the heat dissipation surface29is disposed on the surface of the top portion2013opposed from the bottom portion2011. The mounting surface2031of the pin203extends from the side to the bottom portion2011of the power device20, and the mounting surface2031of the pin203is connected to the bottom surface44of the circuit board40.

The fastener70passes through the cutout41, the through hole21, and the connecting hole64, so that the power device20, the circuit board40, and the heat sink60are connected together. Because the power device20is provided with the through hole21, and the fastener70passes through the through hole21and the connecting hole64to directly crimp the power device20onto the heat sink60, the heat dissipation surface29of the power device20closely fits the assembling surface62of the heat sink60, effectively reducing voids on an interface between the power device20and the heat sink60, thereby reducing a thermal resistance of the power device20and the power device assembly100, and improving the heat dissipation efficiency of the power device20and the power device assembly100.

The fastener70includes a rod72and a cap74connected to one end of the rod72. The rod72passes through and is connected to the cutout41, the through hole21, and the connecting hole64, and the circuit board40is sandwiched between the cap74and the surface of the package body201opposed from the heat sink60. The cap74is disposed on the side of the circuit board40opposed from the heat sink60to prevent the fastener70from falling off the circuit board40. This disclosure does not limit a connection manner of the fastener70and the heat sink60. For example, the fastener70may be a screw, an outer wall of the rod72is provided with a thread, the connecting hole64is a screw hole, and the fastener70is connected to the connecting hole64in a screwed manner. Alternatively, the fastener70may be a stud, a pin, a rivet, or the like.

The power device assembly100includes a washer80encircled on the rod72. The washer80is sandwiched between the cap74and the circuit board40. The cap74is disposed on the side of the washer80opposed from the circuit board40. A surface area of the washer80is greater than a size of the through hole21, to enlarge a stressed area of the circuit board40and prevent a stress on a local area of the circuit board40from being excessively large and causing damages (for example, a risk of fracture) to the circuit board40. The washer80may be integrated with or provided separately from the fastener70.

The power device assembly100includes a thermally conductive interface layer90, and the thermally conductive interface layer90is sandwiched between the power device20and the heat sink60. The thermally conductive interface layer90is configured to conduct heat produced by the power device20to the heat sink60for heat dissipation. The thermally conductive interface layer90is formed with a mounting hole91, and the rod72of the fastener70also passes through the mounting hole91.

The thermally conductive interface layer90is sandwiched between the heat dissipation surface29of the power device20and the assembling surface62of the heat sink60. Because the heat dissipation surface29of the power devices20is in direct contact with the assembling surface62of the heat sink60through the thermally conductive interface layer90for heat dissipation, a heat dissipation path is short, which can effectively improve the heat dissipation efficiency of the power device20and the power device assembly100, thereby improving power density of the power device20and the power device assembly100.

In this implementation, the thermally conductive interface layer90includes a nano copper hook-and-loop tape. When the power device assembly100is assembled, the assembling surface62of the heat sink60is coated with a film layer (not shown) and deoxidized. The film layer is a metal layer to improve the degree of fitting between the thermally conductive interface layer90and the assembling surface62. The metal layer may include at least one of nickel, copper, silver, gold, and palladium. It can be understood that the material of the metal layer is not limited in this disclosure. Then, the heat dissipation surface29of the power device20is deoxidized to improve the degree of fitting between the thermally conductive interface layer90and the heat dissipation surface29. Next, the nano copper hook-and-loop tape is provided between the heat dissipation surface29of the power device20and the assembling surface62of the heat sink60, and is cured to form the thermally conductive interface layer90after a specific time at a specific temperature and pressure (for example, the pressure is 2 MPa, the temperature is 100° C., and the length of time is 10 min). The fastener70passes through the cutout41of the circuit board40, the through hole21, and the mounting hole91, connectable to the connecting hole64of the heat sink60.

It can be understood that the thermally conductive interface layer90is not limited to the nano copper hook-and-loop tape. Alternatively, the thermally conductive interface layer90may be made of another material. For example, the thermally conductive interface layer90may be a graphite thermal pad, a thermal grease, a thermal gel, or the like.

In an implementation, when the thermally conductive interface layer90includes a graphite thermal pad, during preparation, a graphite thermal pad is fabricated in advance to form the thermally conductive interface layer90based on the area of the power device20, and the thermally conductive interface layer90is formed with the mounting hole91. When the power device assembly100is assembled, the thermally conductive interface layer90is placed between the heat dissipation surface29and the heat sink60, and the fastener70passes through the cutout41of the circuit board40, the through hole21, the mounting hole91of the thermally conductive interface layer90and is connected to the connecting hole64of the heat sink60.

In an implementation, when the thermally conductive interface layer90includes a thermal grease or a thermal gel, during preparation, the assembling surface62of the heat sink60is coated with the thermal grease or the thermal gel to form the thermally conductive interface layer90, and then the fastener70passes through the cutout41of the circuit board40and the through hole21, and is connected to the connecting hole64of the heat sink60.

When the power device assembly100is assembled, the circuit board40is soldered to the power device20and then is placed on the heat sink60and positioned, and the fastener70passes through the washer80, the circuit board40, and the through hole21of the package body201of the power device20to be directly into the connecting hole64of the heat sink60. The fastener70applies pressure on the washer80, and the washer80presses the circuit board40as a whole to implement close fitting between the heat dissipation surface29of the power device20, the thermally conductive interface layer90, and the heat sink60, thereby reducing voids between the assembling surface62of the heat sink60and the heat dissipation surface29of the power device20, reducing a thermal resistance of the power device20and the power device assembly100, and improving the heat dissipation performance of the power device20and the heat dissipation efficiency of the power device assembly100.

In the power device20and the power device assembly100provided in this disclosure, the mounting surface2031of the pin203directly fits the circuit board40through the surface-mount technology, implementing an electrical connection between the power device20and the circuit board40. Because there is no need to insert the pins into the component holes of the circuit board, steps of assembling the circuit board40with the power device20are simplified, and a process of the power device assembly100is simplified, thereby improving the processing efficiency of the power device assembly100and reducing manufacturing costs of the power device assembly100.

In addition to the electrical connection between the power device20and the circuit board40using the surface-mount technology, the power device20is provided with the through hole21extending through the molded package26and the substrate structure22, so that the fastener70can directly pass through the through hole21to assemble the power device20, the circuit board40, and the heat sink60together and directly crimp the power device20onto the heat sink60. In this way, the power device20can closely fit the heat sink60, effectively reducing voids on an interface between the power device20and the heat sink60, thereby reducing a thermal resistance of the power device20and the power device assembly100, and improving the heat dissipation efficiency of the power device20and the power device assembly100.

In addition, the power device200uses the surface-mount technology. The pins203of the power device20may be first connected to the circuit board40, and then the power device20and the heat sink60are assembled together. No soldering is required, which helps simplify the assembly process of the power device assembly100and the related apparatus.

Referring now toFIG.8, a power device20is provided in a second implementation that is substantially the same as the power device20provided in the first implementation, excluding that a heat dissipation substrate is omitted from a substrate structure. A metal substrate222of the substrate structure includes a thermally conductive insulation layer2222and two metal layers2224. The two metal layers2224are respectively disposed on two opposite sides of the thermally conductive insulation layer2222. A semiconductor die24is disposed on the side of one metal layer2224opposed from the thermally conductive insulation layer2222. A molded package26covers the semiconductor die24and the metal substrate222excluding a heat dissipation surface to form a package body201. The side surface of the other metal layer2224that is not provided with a semiconductor die24and that is opposed from the thermally conductive insulation layer2222is used as the heat dissipation surface of the power device20. In other words, one surface of the metal substrate222can be directly used as the heat dissipation surface, that is, the surface of the metal substrate222provided with the semiconductor die24is a first surface of the substrate structure, and the surface of the metal substrate222opposed from the semiconductor die24is a second surface of the substrate structure. Pins203may extend in SOP.

Referring toFIG.9, a power device20provided in a third implementation that is substantially the same as the power device20provided in the first implementation, excluding that pins203may extend in HSOP. A second end of each pin203is uncovered from the surface of a bottom portion2011of a package body201opposed from a top portion2013, and extends in the stacking direction of a thermally conductive insulation layer2222and metal layers2224of a metal substrate222opposed from the power device20, and an orthographic projection of the pin203along the stacking direction is completely disposed on the metal substrate222.

Referring toFIG.10, a power device assembly100provided in a fourth implementation that is substantially the same as the power device provided in the first implementation. Compared toFIG.11, a difference is as follows: an orientation of a mounting surface2031of a pin203is the same as an orientation of a bottom portion2011of a package body201opposed from a top portion2013, and a heat dissipation surface29of the power device20is disposed on the surface of the bottom portion2011of the package body201opposed from the top portion2013. A circuit board40is provided with a cutout41extending through a top surface43and a bottom surface44, that is, the circuit board40has an open window design. A mounting surface2031of the pin203is connected to the top surface43together. A heat sink60passes through the cutout41. A rod72of a fastener70passes through the through hole21and a mounting hole91of a thermally conductive interface layer90, and is directly connected to a connecting hole64of the heat sink60together. A cap74is disposed on the surface of the package body201opposed from the heat sink60, that is, the cap74is disposed on the side of the surface of a top portion2013opposed from a bottom portion2011. It can be understood that the heat sink60may be provided with a boss passing through the cutout41of the circuit board40, to implement direct-contact heat dissipation between the heat sink60and the heat dissipation surface29of the power device20.

In this implementation, the thermally conductive interface layer90may also be omitted, the fastener70passes through the through hole21and is directly connected to the connecting hole64. The fastener70may be a screw, a pin, a rivet, or the like.

With reference to the first and the fourth implementations, depending on a position of the heat dissipation surface disposed on the power device, an assembly manner of the power device, the circuit board, and the heat sink may be selected. For example, when the heat dissipation surface is disposed on the surface of the top portion of the power device opposed from the bottom portion of the power device, the pins may be soldered to the bottom surface of the circuit board by using reflow soldering, and the circuit board does not require an open window design corresponding to the heat sink (that is, the assembly manner exemplified in the first implementation). When the heat dissipation surface is disposed on the surface of the bottom portion of the power device opposed from the top portion of the power device, the circuit board is provided with a cutout, and the pins may be soldered to the top surface of the circuit board by using reflow soldering. In this way, different power devices are packaged together in a variety of forms, which improves the flexibility of device arrangement.

Refer toFIG.12. A power device20provided in a fifth implementation of this disclosure differs from the power device20provided in the first implementation in that a heat dissipation surface29includes two heat dissipation surface units290, and a gap2901between adjacent heat dissipation surface units290is filled with a molded package26. For example, when the surface of a heat dissipation substrate226opposed from a metal substrate222is used as the heat dissipation surface29, the heat dissipation substrate may be divided into two independent heat dissipation surface units290, that is, the heat dissipation surface29is divided into two independent heat dissipation surface units290. It can be understood that the number of heat dissipation surface units290is not limited, and there may be two or more heat dissipation surface units290. That is, the heat dissipation surface29includes at least two heat dissipation surface units290, and a gap2901between adjacent heat dissipation surface units290is filled with the molded package26. The heat dissipation surface29includes at least two heat dissipation surface units290, which can effectively reduce a risk that the heat dissipation surface29is easily damaged and fractured by force due to its excessively large area. In an implementation, the substrate structure includes the metal substrate but omits the heat dissipation substrate. The surface of the metal substrate opposed from the semiconductor die provides the heat dissipation surface. The surface of the metal substrate opposed from the semiconductor die may be divided into at least two heat dissipation surface units, to alleviate a risk that the heat dissipation surface is easily fractured by a mechanical stress due to its excessively large area.

Refer toFIG.13. A power device provided in a sixth implementation of this disclosure differs from the power device provided in the first implementation in that a metal substrate222includes two mounting units2220, a gap is provided between the two mounting units2220, and the gap may be filled with a molded package26. In this implementation, in each mounting unit2220, there are two metal layers2224, and a thermally conductive insulation layer2222is sandwiched between the two metal layers2224. The surface of one of the metal layers2224in each mounting unit2220opposed from the thermally conductive insulation layer2222is provided with a semiconductor die24. The adjacent mounting units2220are insulated from each other by the molded package26, which helps improve the reliability of the power device. It can be understood that the number of mounting units2220may be set based on a function of the semiconductor die24and the like. The metal substrate222includes at least two mounting units2220and at least two semiconductor dies24, each mounting unit2220being provided with at least one semiconductor die24.

This disclosure further provides an assembling method for a power device assembly100described above (in the first to the sixth implementations). The power device assembly100includes a power device20, a circuit board40, and a heat sink60. The power device20includes a package body201and a plurality of pins203. The package body201includes a substrate structure22, a semiconductor die24, and a molded package26. The substrate structure22includes a heat dissipation surface29. The molded package26covers the semiconductor die24and the substrate structure22excluding the heat dissipation surface29. A first end of each pin203is connected to the substrate structure22, a second end of each pin203and the heat dissipation surface29are uncovered from the molded package26. The second end of each pin203includes a mounting surface2031. The package body201is further provided with a through hole21extending through the substrate structure22and the molded package26, and an inner wall of the through hole21is covered with the molded package26. The circuit board40is provided with a cutout41. The heat sink60includes an assembling surface62provided with a connecting hole64. Referring toFIG.14, the assembling method includes the following steps:

Step103: The mounting surface2031of the pin203is connected to the circuit board40. In this implementation, the mounting surface2031is connected to the circuit board40by using a reflow soldering process.

Step105: The fastener70passes through the through hole21, the cutout41, and the connecting hole64, so that the heat dissipation surface29and the assembling surface62are connected.

The package body201includes a bottom portion2011and a top portion2013that are disposed opposite each other, an orientation of the mounting surface2031is the same as an orientation of the bottom portion2011opposed from the top portion2013, and the heat dissipation surface29is disposed on the surface of the top portion2013opposed from the bottom portion2011. The fastener70passes through the through hole21, the cutout41, and the connecting hole64and successively passes through the cutout41, the through hole21, and the connecting hole64so that the circuit board40, the package body201, and the heat sink60are laminated to one another.

The fastener70includes a rod72and a cap74connected to one end of the rod72. The fastener70successively passes through the cutout41, the through hole21, and the connecting hole64. The rod72passes through the cutout41, the through hole21, and the connecting hole64so that the circuit board40is sandwiched between the cap74and the surface of the package body201opposed from the heat sink60, and the cap74is disposed on the side of the circuit board40opposed from the package body201.

Before the mounting surface2031of the pin203of the power device20is connected to the circuit board40, the assembling method further includes: providing a thermally conductive interface layer90between the heat dissipation surface29and the assembling surface62, where the thermally conductive interface layer90is formed with a mounting hole91extending through the thermally conductive interface layer90. The fastener70passes through the through hole21, the cutout41, and the connecting hole64passes through the mounting hole91. The thermally conductive interface layer90includes one of a nano copper hook-and-loop tape, a graphite thermal pad, a thermal grease layer, or a thermal gel.

In an implementation, an orientation of the mounting surface2031is the same as an orientation of the bottom portion2011opposed from the top portion2013, and the heat dissipation surface29is disposed on the surface of the bottom portion2011opposed from the top portion2013. The fastener70passes through the through hole21, the cutout41, and the connecting hole64further includes: the heat sink60passes through the cutout41, and the fastener70successively passes through the through hole21and the connecting hole64, so that the package body201and the heat sink60are laminated.

Referring toFIG.15, another assembling method is described for a power device assembly100. The assembling method includes the following steps:

Step201: A thermally conductive interface layer90is provided between the heat dissipation surface29and the assembling surface62.

Step203: The mounting surface2031of the pin203is connected to the circuit board40.

Step205: The fastener70passes through and is connected to a washer80, the cutout41, the through hole21, a mounting hole91, and the connecting hole64successively, so that the washer80, the circuit board40, the package body201, the thermally conductive interface layer90, and the heat sink60are laminated to one another. The package body201includes a bottom portion2011and a top portion2013that are disposed opposite each other, an orientation of the mounting surface2031is the same as an orientation of the bottom portion2011opposed from the top portion2013, and the heat dissipation surface29is disposed on the surface of the top portion2013opposed from the bottom portion2011.

The fastener70includes a rod72and a cap74connected to one end of the rod72. The diameter of the cutout41is adapted to the rod72. The washer80is sandwiched between the circuit board40and the cap74, and the cap74is disposed on the side of the washer80opposed from the circuit board40.

In an implementation, the cutout41of the circuit board40has a relatively large diameter, the heat sink60passes through the cutout41, an orientation of the mounting surface2031is the same as an orientation of the bottom portion2011opposed from the top portion2013, and the heat dissipation surface29is disposed on the surface of the bottom portion2011opposed from the top portion2013. The washer80is sandwiched between the surface of the package body201opposed from the heat sink60and the cap74, and the cap74is disposed on the side of the washer80opposed from the package body201. The cap74, the washer80, the package body201, the thermally conductive interface layer90, and the heat sink60are laminated to one another.

In an implementation, the thermally conductive interface layer90includes a nano copper hook-and-loop tape. Referring toFIG.16, the assembling method for the power device assembly100includes the following steps:

Step301: A film layer is plated on the assembling surface62and where the film layer is a metal layer, the film layer is deoxidized. The metal layer includes at least one of nickel, copper, silver, gold, and palladium, and the material of the metal layer is not limited in this implementation of this disclosure.

Step305: The thermally conductive interface layer90is provided between the heat dissipation surface29and the assembling surface62, which includes: the nano copper hook-and-loop tape is provided between the heat dissipation surface29and the assembling surface62, and is cured to form the thermally conductive interface layer90, where the thermally conductive interface layer90is provided with a mounting hole91extending through the thermally conductive interface layer90.

Step307: The mounting surface2031of the pin203is connected to the circuit board40.

Step309: The fastener70passes through and is connected to the through hole21, the cutout41, the mounting hole91, and the connecting hole64, so that the power device20, the circuit board40, and the heat sink60are connected.

In an implementation, the thermally conductive interface layer includes a graphite thermal pad. Referring toFIG.17, the assembling method for a power device assembly100includes the following steps:

Step401: The graphite thermal pad is fabricated in advance to form the thermally conductive interface layer90, where the thermally conductive interface layer90is formed with a mounting hole91extending through the thermally conductive interface layer90.

Step403: The thermally conductive interface layer90is provided between the heat dissipation surface29and the assembling surface62.

Step405: The mounting surface2031of the pin203is connected to the circuit board40.

Step407: The fastener70passes through and is connected to the through hole21, the cutout41, the mounting hole91, and the connecting hole64, so that the power device20, the circuit board40, and the heat sink60are connected.

In an implementation, that the thermally conductive interface layer90is provided between the heat dissipation surface29and the assembling surface62includes: the assembling surface62is coated with a thermal grease or a thermal gel to form the thermally conductive interface layer90.

It should be understood that the expressions that can be used in this disclosure, such as “include” and “may include”, indicate the existence of the disclosed functions, operations, or constituent elements, without limiting one or more additional functions, operations, and constituent elements. In this disclosure, the terms such as “include” and/or “have” can be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but cannot be interpreted as excluding the existence of one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof, or a possibility of addition.

In addition, in this disclosure, the expression “and/or” includes any and all combinations of the associated terms listed. For example, the expression “A and/or B” may include A, or may include B, or may include both A and B.

In this disclosure, the expressions including ordinal numbers such as “first” and “second” may modify various elements. However, the elements are not limited by the expressions. For example, the expressions do not limit the order and/or importance of the elements. The expressions are only used to distinguish an element from another element. For example, first user equipment and second user equipment represent different user equipment, although both the first user equipment and the second user equipment are user equipment. Similarly, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

When a component is described as “connected to” or “access” another component, it should be understood that the component may be directly connected to or access another component, but still another component may exist between the component and the other component. In addition, when a component is described as “directly connected to” or “directly access” another component, it should be understood that no other component exists between them.

The foregoing descriptions are merely specific implementations of this disclosure, but the protection scope of this disclosure is not limited thereto. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this disclosure shall fall within the protection scope of the claims. Therefore, the protection scope of this disclosure shall be subject to the protection scope of the claims.