Low stray inductance structure of plastic package module, SiC power supply module and electrical equipment

Abstract

The invention discloses a low stray inductance structure of a plastic package module, which comprises a silicon carbide chip, a negative terminal, a positive terminal, an AC terminal and a plastic package body which are arranged on a lining plate, the silicon carbide chip, the negative terminal, the positive terminal and the AC terminal are wrapped by the plastic package body, the negative terminal and the positive terminal are of a laminated arrangement structure, and the silicon carbide chip, the negative terminal, the positive terminal and the AC terminal are arranged on the lining plate. And the positive terminal is fixedly connected with the negative terminal through an insulating bonding sheet to form a power terminal. The positive terminal and the negative terminal are laminated, so that the distance between copper bars is reduced to the maximum extent, and the stray inductance of a module end is reduced; and the bus capacitor matched with the module also adopts a laminated structure, so that the stray inductance at the bus capacitor is reduced.

Description

Technical Field

[0001] The present application belongs to the field of electronic components, and in particular relates to a low stray inductance structure of a plastic-encapsulated module, a SiC power module and electrical equipment. Background Art

[0002] Power modules are widely used and play an extremely important role in industrial equipment, home appliances, public transportation, information terminals and other products. The third-generation semiconductor silicon carbide (SiC: Silicon Carbide) devices have lower on-resistance, higher switching speed and high temperature resistance. They are gradually being used to replace silicon-based devices in electric vehicles, wind power, photovoltaics, energy storage and rail transportation. The packaging modules of silicon carbide devices are also widely used.

[0003] The energy consumption of the power converter comes from conduction loss and switching loss, especially the switching loss of SiC devices. In electric vehicle applications, switching loss accounts for a large part of the overall loss. Optimizing switching loss is crucial to reducing the energy consumption of the power converter and improving efficiency. The presence of stray inductance in the power loop will not only increase the spike voltage during the device shutdown process, damaging the device, but will also greatly increase switching losses, thereby reducing the efficiency of the power converter. The application of silicon carbide devices will increase the switching frequency, resulting in higher voltage and current change rates dv / dt and di / dt, and the impact of stray inductance will be more significant. Usually, the power module is equipped with DC+, DC-, and AC power terminals, which usually account for half or more of the overall stray inductance of the module.

[0004] In the prior art, such as the power converter with publication number CN 110785842, the positive and negative input copper busbar terminals (DC+ DC-) of the power module cannot be stacked, or the stacking area is small, which makes the stray inductance generated by the power terminal high, usually occupying more than half of the entire module. For example, in the power module with publication number CN205212748, the positive and negative electrode stacking is achieved through a frame structure. However, due to the influence of the injection molding process, the distance between the positive and negative electrodes cannot be too close, usually 1.5mm-2mm. The stray inductance is very sensitive to the distance between the positive and negative electrodes, the closer the better, and the above-mentioned prior art is difficult to achieve an ideal state.

[0005] Therefore, there is an urgent need for a plastic-encapsulated SiC power module with low stray inductance that can solve the above problems. Summary of the invention

[0006] In order to address the deficiencies of the prior art, the present application provides a low stray inductance structure of a plastic-encapsulated module, a SiC power module and electrical equipment, which can maximize the reduction of the distance between the positive and negative electrodes, thereby reducing stray inductance, and optimize the structure of the entire plastic-encapsulated device, thereby improving the performance of the plastic-encapsulated device.

[0007] The technical effects to be achieved by this application are achieved through the following solutions: According to the first aspect of the present application, a low stray inductance structure of a plastic-encapsulated module is provided, comprising a silicon carbide chip, a negative terminal, a positive terminal, an AC terminal and a plastic-encapsulated body on a lining plate, wherein the plastic-encapsulated body wraps the silicon carbide chip, the negative terminal, the positive terminal and the AC terminal, wherein the negative terminal and the positive terminal are arranged in a stacked structure, and the positive terminal is fixedly connected to the negative terminal via an insulating adhesive sheet.

[0008] Preferably, the distance between the positive terminal and the negative terminal is 0.1-0.8 mm.

[0009] Preferably, the material of the positive terminal and the negative terminal is copper, aluminum or a copper-aluminum composite material, and is surface treated with silver, nickel or bare metal; the insulating adhesive sheet is made of one or more of NOMEX, NMN, DMD, PI, PVF or PET.

[0010] Preferably, an RC buffer capacitor is connected in parallel between the positive terminal and the negative terminal.

[0011] Preferably, a copper clip is used inside the module to conduct current, and the copper clip is connected at least between the upper tube and the AC terminal.

[0012] Preferably, the positive terminal and the negative terminal are respectively connected to the positive and negative copper bars of the bus capacitor, the positive and negative copper bars adopt a stacked arrangement structure, and the positive and negative copper bars are connected by an insulating adhesive sheet.

[0013] Preferably, a temperature measuring hole is provided on the plastic package body above the silicon carbide chip, and the temperature measuring hole is a blind hole.

[0014] Preferably, the positive terminal on the lead frame of the plastic-encapsulated device is connected to the copper layer where the upper tube is located, the AC terminal is connected to the copper layer where the lower tube is located, the source of the upper tube and the source of the lower tube are both led out through the lead frame, and another copper clip is connected between the lower tube and the negative terminal, and the other copper clip and the negative terminal are an integrated structure.

[0015] According to a second aspect of the present application, a SiC power module is provided, which adopts the low stray inductance structure of the above-mentioned plastic package module.

[0016] According to a third aspect of the present application, there is provided an electrical device, which adopts the above-mentioned SiC power module.

[0017] According to the first embodiment of the present application, the beneficial effect of the low stray inductance structure of the plastic-encapsulated module of the present application is that the stray inductance at the module end is reduced by maximizing the reduction of the copper bar spacing by stacking the positive and negative terminals; Connect an RC buffer capacitor in parallel between the positive and negative terminals to further reduce the peak voltage generated during the chip shutdown process, protect the chip from overvoltage damage, and enable the module to work at a higher DC voltage; The bus capacitor matched with the module also uses a laminated structure to reduce the stray inductance at the bus capacitor; Clips are used internally to conduct current, replacing traditional wire bonding, increasing current transmission capacity and reliability; the internal structure of the module is optimized, the overall design is simple, and the artistry is strong; An external infrared temperature sensor is used for temperature measurement, and the NTC chip and two signal pins are removed, reducing the module size. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the existing technical solutions, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 An exploded view of a low stray inductance structure of a plastic-encapsulated module in one embodiment of the present application; Figure 2 for Figure 1 Schematic diagram of the position structure of the positive copper bar and the negative copper bar; Figure 3 for Figure 1 Schematic diagram of the connection structure between the plastic package device and the bus capacitor; Figure 4 for Figure 1 Schematic diagram of the top view structure of the plastic-encapsulated device. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0021] A low stray inductance structure of a plastic-encapsulated module is provided, comprising a silicon carbide chip 300, a negative terminal 220, a positive terminal 210, an AC terminal 240 and a plastic-encapsulated body 100 on a liner 200, wherein the plastic-encapsulated body 100 wraps the silicon carbide chip 300, the negative terminal 220, the positive terminal 210 and the AC terminal 240, wherein the negative terminal 220 and the positive terminal 210 are in a stacked arrangement structure, and the positive terminal 210 is fixedly connected to the negative terminal 220 via an insulating adhesive sheet 230 to form a power terminal.

[0022] The positive terminal 210 and the negative terminal 220 may be made of copper, aluminum or a copper-aluminum composite material, and may be surface treated with silver, nickel or bare metal; In this embodiment, the positive terminal 210 and the negative terminal 220 are both copper bars. After the positive copper bar and the negative copper bar are stacked inside the plastic package device, they are led out of the plastic package device to form the positive terminal 210 and the negative terminal 220. When manufacturing the lead frame 250, the positive terminal 210 and the negative terminal 220 are stacked and connected together using an adhesive insulating material to minimize the spacing between the copper bars, so that the distance between the positive terminal 210 and the negative terminal 220 is 0.1-0.8 mm, thereby reducing the stray inductance at the power terminal.

[0023] In this embodiment, the insulating adhesive sheet 230 is made of one or more of NOMEX, NMN, DMD, PI, PVF or PET; wherein: NOMEX is made of poly(m-phenylene isophthalamide) and has excellent heat resistance, dimensional stability and insulation properties; NMN is a composite material consisting of a layer of polyester film in the middle and Nomex paper on both sides. It has good mechanical properties and electrical strength and can maintain stable insulation performance in high temperature environments. DMD is an insulating composite material made of polyester film coated with adhesive and polyester fiber non-woven fabric on one side. It has good mechanical properties and electrical strength, is suitable for various high-voltage and low-voltage environments, and has stable insulation performance. PI (polyimide), a high-performance polymer with excellent temperature resistance, wear resistance and radiation resistance, high dielectric strength and good chemical stability; PVF (polyvinyl fluoride) has extremely high chemical stability, thermal stability and insulation, and can be used for a long time at above 250°C; PET (polyethylene terephthalate) has high mechanical strength and good electrical insulation and is used within the range of 60-80°C.

[0024] A suitable insulating adhesive sheet 230 may be selected according to different application scenarios to achieve better use effect and lower use cost.

[0025] In this embodiment, an RC snubber capacitor (RC snubber) (not shown in the figure) is connected in parallel between the positive terminal 210 and the negative terminal 220 to further reduce the peak voltage generated during the chip shutdown process, protect the chip from overvoltage damage, and enable the module to operate at a higher DC voltage.

[0026] One or more capacitors in the RC buffer capacitor are connected to the liner 200 by welding, sintering, or silver glue, and are functionally connected in parallel to the positive copper bus and the negative copper bus. The RC buffer capacitor is, for example, between 0.1 μF and 10 μF, or a larger capacitor can be selected as needed.

[0027] In this embodiment, a copper clip 330 (clip) is used inside the module to conduct current, replacing traditional wire bonding, thereby increasing the current transmission capacity and reliability. The copper clip 330 can also optimize the internal structure of the module, and the overall design is simple and has strong processability.

[0028] In this embodiment, the positive and negative electrodes of the plastic-encapsulated device are connected to a bus capacitor 400, and the positive and negative copper bars 410 of the bus capacitor 400 adopt a laminated arrangement structure, and the positive and negative copper bars 410 are connected by an insulating adhesive sheet 230. After the positive and negative electrodes of the bus capacitor 400 are stacked and extended, they are separated until the power module, and are respectively connected to the positive and negative electrodes of the power module. The insulating adhesive sheet 230 extends all the way to the module terminal to ensure that there is no insulation risk. The bus capacitor 400 is connected to the module by laser welding. Since the bus capacitor 400 is laminated when it is extended and connected to the module, the stray inductance introduced by the bus capacitor 400 is greatly reduced.

[0029] In a traditional plastic-encapsulated power module, an NTC chip and a signal pin are required to detect the internal temperature, which causes the size of the module to be too large. In addition, the added chip and internal pins will also cause a certain amount of stray inductance. Therefore, in this embodiment, the NTC chip and its two signal pins are directly removed, and a temperature measuring hole 101 is opened directly on the plastic encapsulation body 100 above the silicon carbide chip 300. The temperature measuring hole 101 is a blind hole, that is, a concave structure is made at the position corresponding to the chip until it reaches the SiC chip. At the same time, a corresponding infrared induction temperature sensor is added to the corresponding control board, and the infrared induction temperature sensor is directed toward the temperature measuring hole 101 for temperature measurement, so that there is no need to arrange the NTC chip and the corresponding pins inside the module. While reducing the size of the module, the internal structure of the chip is simplified. Without the complicated pin structure, stray inductance can also be reduced.

[0030] In this embodiment, the positive terminal 210 in the lead frame 250 is connected to the copper layer where the upper tube 310 in the silicon carbide chip 300 is located, the upper layer of the upper tube 310 is connected to the AC terminal 240 through the copper clip 330, the AC terminal 240 is connected to the copper layer where the lower tube 320 in the silicon carbide chip 300 is located, and the source of the upper and lower tubes are both led out from the lead frame 250. The gate poles of the upper and lower tube chips are connected to the copper layer where the corresponding upper and lower tube gate pins are located through binding wires. Another copper clip 330 is connected between the lower tube 320 and the negative terminal 220, and the other copper clip 330 and the negative terminal 220 are an integrated structure, which not only improves the reliability of conductivity, but also reduces the number of parts and simplifies the assembly process, thereby avoiding the problem of reduced qualified rate caused by assembly errors.

[0031] The above-mentioned low stray inductance plastic-encapsulated module is mainly used in SiC power modules, which can reduce the stray inductance generated by the positive and negative terminals 220, reduce the switching loss and shutdown voltage of the power module, and use RC snubber capacitors to further absorb the shutdown voltage; reduce the chip stress generated by the voltage, and also allow the chip to be used at a higher voltage.

[0032] At the same time, the connection method of the matching bus capacitor 400 is considered, and the positive and negative terminals 220 of the bus capacitor 400 are connected, fixed and insulated using an insulating adhesive sheet 230, which can reduce stray inductance and take into account insulation, thereby reducing the stray inductance of the entire power circuit.

[0033] The positive and negative terminals 220 of the bus capacitor 400 are extended and separated to the upper and lower sides of the positive terminal 210 and the negative terminal 220 to complete welding. The insulating adhesive sheet 230 between the positive and negative terminals 220 extends all the way to the positive terminal 210 and the negative terminal 220 to ensure insulation and avoid breakdown due to the presence of gaps under high voltage conditions.

[0034] By optimizing the layout of the liner 200 and using clip (copper clip 330) for connection, the difficulty of the production process is reduced and the reliability is improved. The chip can be compatible with SiC chips of different sizes, making the SiC power module have a very high power density.

[0035] The production of this SiC power module mainly includes the following steps: Connect the positive copper bar to the entire frame through the insulating adhesive sheet 230, so that the distance between the positive and negative copper bars 410 is 0.1-0.8mm; Connect 2 or 4 SIC chips and RC snubber capacitors to the liner 200 by welding, silver sintering, copper sintering, or silver glue bonding; After the lead frame 250 and the liner 200 are fixedly connected by welding, the gate bonding wires are connected; Finally, the plastic sealing process is used to complete the plastic sealing, and the ribs are cut and formed.

[0036] In other embodiments, an electrical device is disclosed, which uses the above SiC power module. The electrical device is, for example: a motor drive system, an onboard charger and a DC / CD converter of an electric vehicle; a charging pile of an electric vehicle; an inverter of a photovoltaic device; a UPS power supply and a network and server power supply.

[0037] The electrical equipment is manufactured by adopting the above technical solution. Since it includes SiC power modules, it has the following beneficial effects: by stacking the positive and negative terminals, the spacing between the copper bars is minimized to the maximum extent, thereby reducing the stray inductance at the module end; Connect an RC snubber circuit in parallel between the positive and negative terminals to further reduce the peak voltage generated during the chip shutdown process, protect the chip from overvoltage damage, and enable the module to operate at a higher DC voltage; The bus capacitor matched with the module also uses a laminated structure to reduce the stray inductance at the bus capacitor; Clips are used internally to conduct current, replacing traditional wire bonding, increasing current transmission capacity and reliability; the internal structure of the module is optimized, the overall design is simple, and the artistry is strong; An external infrared temperature sensor is used for temperature measurement, the NTC chip and two new pins are removed, and the module size is reduced.

[0038] It should be noted that the above detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present application belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0041] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0042] For ease of description, spatially relative terms, such as "above", "above", "on the upper surface of", "above", etc., may be used herein to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways, such as rotated 90 degrees or in other orientations, and the spatially relative descriptions used herein are interpreted accordingly.

[0043] In the above detailed description, reference is made to the accompanying drawings, which form a part of this document. In the accompanying drawings, similar symbols typically identify similar components unless the context indicates otherwise. The illustrated embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low stray inductance structure of a plastic-encapsulated module, comprising a silicon carbide chip, a negative terminal, a positive terminal, an AC terminal and a plastic-encapsulated body on a liner, wherein the plastic-encapsulated body wraps the silicon carbide chip, the negative terminal, the positive terminal and the AC terminal, and is characterized in that: The negative terminal and the positive terminal are in a stacked arrangement structure, and the positive terminal is fixedly connected to the negative terminal via an insulating adhesive sheet.

2. The low stray inductance structure of the plastic-encapsulated module according to claim 1, characterized in that: The distance between the positive terminal and the negative terminal is 0.1-0.8 mm.

3. The low stray inductance structure of the plastic-encapsulated module according to claim 1, characterized in that: The material of the positive terminal and the negative terminal is copper, aluminum or a copper-aluminum composite material, and is surface treated with silver, nickel or bare metal; the insulating adhesive sheet is made of one or more of NOMEX, NMN, DMD, PI, PVF or PET.

4. The low stray inductance structure of the plastic-encapsulated module according to claim 1, characterized in that: An RC buffer capacitor is connected in parallel between the positive terminal and the negative terminal.

5. The low stray inductance structure of the plastic-encapsulated module according to claim 1, characterized in that: A copper clip is used inside the module to conduct current, and the copper clip is connected at least between the upper tube and the AC terminal.

6. The low stray inductance structure of the plastic-encapsulated module according to claim 1, characterized in that: The positive terminal and the negative terminal are respectively connected to the positive and negative copper bars of the bus capacitor, the positive and negative copper bars adopt a stacked arrangement structure, and the positive and negative copper bars are connected by an insulating adhesive sheet.

7. The low stray inductance structure of the plastic-encapsulated module according to claim 1, characterized in that: A temperature measuring hole is provided on the plastic package body above the silicon carbide chip, and the temperature measuring hole is a blind hole.

8. The low stray inductance structure of the plastic-encapsulated module according to claim 5, characterized in that: The positive terminal on the lead frame of the plastic-encapsulated device is connected to the copper layer where the upper tube is located, the AC terminal is connected to the copper layer where the lower tube is located, the source of the upper tube and the source of the lower tube are both led out through the lead frame, and another copper clip is connected between the lower tube and the negative terminal, and the other copper clip and the negative terminal are an integrated structure.

9. A SiC power module, characterized in that: A low stray inductance structure of a plastic-encapsulated module according to any one of claims 1 to 8 is adopted.

10. An electrical device, characterized in that: The SiC power module according to claim 9 is adopted.

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