Semiconductor power module and method of manufacturing the same

Abstract

The application relates to the technical field of semiconductors, and particularly provides a semiconductor power module and a preparation method thereof. The semiconductor power module comprises a backing plate, an injection tube shell located around the backing plate, a busbar terminal, and a pin part. The pin part is connected with the backing plate, and the main body part is embedded in the injection tube shell. The pin part is provided with a slot on at least one side in the width direction of the pin part. The semiconductor power module can realize good mechanical protection and electrical connection, and can realize efficient heat dissipation, so that the temperature can be kept low during work, and the reliability of the semiconductor power module is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a semiconductor power module and its fabrication method. Background Technology

[0002] In the rapid development of modern industry and technology, IGBT (Insulated Gate Bipolar Transistor) modules, as core devices in the power semiconductor field, have an extremely wide range of applications and play an indispensable role in many key areas. In the field of new energy vehicles, IGBT modules, as the core component of the vehicle's electric drive system, are considered the heart of the system. Their performance directly affects the vehicle's power performance, driving range, and driving safety. IGBT modules can efficiently convert the battery's DC power to AC power, enabling the drive system to achieve strong power output, allowing the vehicle to accelerate from 0 to 100 km / h in just a few seconds, while also effectively reducing energy consumption and improving driving range. With the rapid expansion of the new energy vehicle market, more stringent requirements have been placed on the performance and reliability of IGBT modules. Their current carrying capacity, switching speed, and other indicators are directly related to the vehicle's energy efficiency and driving experience. This necessitates that IGBT modules continuously improve their power density and reliability to meet market demands. In the field of industrial frequency conversion, IGBT modules also play an indispensable role. In motor drive systems, IGBT modules achieve efficient speed regulation and stable operation of motors by precisely controlling current and voltage, thereby significantly improving production efficiency and reducing energy consumption. Statistics show that industrial frequency conversion systems using IGBT modules can reduce motor energy consumption by 20% to 30%, saving enterprises substantial energy costs. In the smart grid field, IGBT modules are used for power conversion, transmission, and distribution, enabling intelligent control and efficient operation of the grid. For example, in flexible DC transmission systems, IGBT modules can precisely control current and voltage, improving transmission efficiency, reducing transmission losses, and ensuring the stable and reliable operation of the grid. Furthermore, in the rail transit field, IGBT modules are widely used in train traction systems and auxiliary power systems; their performance directly determines the stability, reliability, and energy consumption level of train operation. In these application scenarios, IGBT modules need to possess efficient power conversion and control capabilities to meet the needs of different fields. To meet these ever-increasing demands, IGBT module design and manufacturing processes are not the only factors; packaging technology also plays a crucial role and has become a key research focus. As a bridge connecting IGBT modules to external circuits, packaging technology needs to undertake multiple important functions, including mechanical support, electrical interconnection, heat dissipation, and environmental protection. An excellent packaging design can effectively reduce parasitic parameters, such as parasitic inductance and capacitance, thereby reducing signal transmission losses and interference, and improving the switching speed and efficiency of the IGBT module. At the same time, good packaging technology can also ensure that the IGBT module can operate stably and reliably in complex working environments, such as high temperature, high humidity, and strong electromagnetic interference, extending its service life.

[0003] In traditional IGBT modules, the busbar terminals and the housing are separate. When the busbar terminals are subjected to pull-out forces, stress becomes highly concentrated on the pins. In practical applications, IGBT modules are subjected to various external forces during operation, such as vibration and impact. These forces are transmitted to the solder joints through the busbar terminals. Because traditional busbar terminals lack effective stress relief structures, the solder joints are easily pulled off under pull-out forces, leading to electrical open circuit failure. To improve the stress concentration problem of traditional busbar terminals, stress-relief terminals were developed. These terminals are positioned between the pins and the body of the busbar terminal. When subjected to pull-out forces, the stress is released through the deformation of the stress-relief terminal itself, thus protecting the solder joints. However, this also leads to a longer current flow path, increased Joule heat generation, and hinders heat dissipation from the busbar terminals.

[0004] Therefore, there is an urgent need to provide a solution that balances the reliability of the pins with the need to improve the heat dissipation of the busbar terminals, thereby enhancing the reliability of semiconductor power modules. Summary of the Invention

[0005] The purpose of this invention is to provide at least one semiconductor power module and its fabrication method, which can at least meet the requirements of pin reliability and improved heat dissipation of busbar terminals, thereby improving the reliability of the semiconductor power module.

[0006] To solve the above-mentioned technical problems, the present invention provides a semiconductor power module, comprising: a substrate; an injection-molded housing located around the substrate; and a busbar terminal, the busbar terminal comprising a main body portion and a pin portion; wherein the pin portion is connected to the substrate, and the main body portion is embedded in the injection-molded housing; and the pin portion has a slot on at least one side along the width direction of the pin portion.

[0007] The semiconductor power module provided by this invention features a pin portion connected to a substrate. The main body is embedded in an injection-molded shell during the shell's formation process. All busbar terminals, except for the pin portions, are embedded within the shell. The injection-molded shell withstands external forces, enhancing the rigidity of the busbar terminals and protecting the pin portions. This prevents stress transmission to the busbar terminal pin portions, improving their reliability and thus increasing the reliability of the connection between the pin portions and the substrate. The pin portions have slots on at least one side along their width, buffering stress between the pin portions and the main body, further reducing stress transmission to the busbar terminal pin portions and improving the reliability of the connection between the pin portions and the substrate. During operation, the slots in the pin portions also improve heat dissipation from the busbar terminals, reducing their temperature and enhancing their current-carrying capacity. In summary, the semiconductor power module of this application achieves excellent mechanical protection and electrical connection while providing efficient heat dissipation, ensuring a low temperature during operation and improving the module's reliability.

[0008] Additionally, the pin portion includes a first pin portion and a second pin portion located between the main body portion and the first pin portion. The first pin portion is connected to the substrate, and the second pin portion has the slot on at least one side along the width direction. By avoiding the slot being located on the first pin portion, which would reduce the contact area between the first pin portion and the substrate, placing the slot on the side of the second pin portion improves the reliability of the connection between the first pin portion and the substrate, thus balancing the need to improve the reliability of the connection between the pin portion and the substrate with the need to enhance the heat dissipation of the busbar terminals.

[0009] Furthermore, there are multiple pin portions, each independently arranged along its width direction, with the slots of adjacent pin portions facing each other. This further improves the heat dissipation effect of the busbar terminals.

[0010] In addition, a coating layer is provided on the top surface of the main body, and the injection-molded shell exposes the top surface of the main body, which is connected to external conductive terminals; wherein, the coating layer includes a silver-plated film layer. This reduces the corrosion rate of the busbar terminals in humid, hot, and salt spray environments, making it suitable for harsh working conditions and improving the environmental adaptability of the semiconductor power module.

[0011] In addition, the busbar terminal also includes a transition portion located between the main body and the pin portion; the transition portion is embedded in the injection-molded shell. The transition portion being embedded in the injection-molded shell means that it is embedded during the formation of the injection-molded shell. The injection-molded shell withstands external forces, which helps to improve the rigidity of the busbar terminal, protect the pin portion, and thus prevent stress transmission to the pin portion of the busbar terminal, improving the reliability of the pin portion and consequently enhancing the reliability of the connection between the pin portion and the liner.

[0012] Furthermore, at temperatures between 20°C and 25°C, the tensile strength of the busbar terminals is greater than or equal to 450 MPa; at 150°C, the tensile strength of the busbar terminals is greater than or equal to 350 MPa. By setting tensile strength requirements at different temperatures, it can be ensured that the semiconductor power module maintains sufficient mechanical strength in the busbar terminals during long-term operation, whether at room temperature or in high-temperature environments. This guarantees the stability and reliability of the electrical connection between the pins and the substrate, eliminates the risk of loosening under vibration conditions, and meets service life requirements. Moreover, by setting tensile strength requirements at different temperatures, it can be ensured that the semiconductor power module can adapt to different application scenarios and meet the usage requirements under various operating conditions.

[0013] Furthermore, the main body and the pin portion are integrally formed; the material of the busbar terminal includes dispersion-strengthened copper alloy or oxygen-free copper. This improves the matching of the thermal expansion coefficients between the busbar terminal and the liner, enhances the resistance to thermal stress, and the metallurgical bonding of the welding interface between the pin portion of the busbar terminal and the liner improves the tensile strength.

[0014] In addition, the busbar terminal has a stepped structure, and the busbar terminal has one or more steps.

[0015] The present invention also provides a method for fabricating a semiconductor power module, comprising: providing a substrate; forming a busbar terminal, the busbar terminal including a main body and a pin portion, the pin portion having a slot on at least one side along the width direction of the pin portion; forming an injection-molded shell around the substrate; embedding the main body portion into the injection-molded shell during the process of forming the injection-molded shell around the substrate; and connecting the pin portion and the substrate by ultrasonic welding. During the process of forming the injection-molded shell 2 around the liner, the main body is embedded in the injection-molded shell. The injection-molded shell can tightly wrap the main body during the molding process. After the main body is embedded in the injection-molded shell, the two form a tightly integrated whole, providing good mechanical protection and electrical connection for the semiconductor power module. Compared with traditional brazing and wire bonding processes, the ultrasonic welding process of this application enhances the connection reliability of the pin and the liner, and generates less heat during the welding process, reducing the risk of aging and failure of the solder joints of the pin and the liner. The semiconductor power module has a stronger current carrying capacity during operation, which is conducive to achieving more efficient heat dissipation and meeting the requirements of high power density and high reliability of semiconductor power modules.

[0016] In addition, it also includes: before connecting the pin portion and the substrate by ultrasonic welding, performing laser preheating treatment on the connection interface between the pin portion and the substrate. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 This is a schematic diagram of the structure of a semiconductor power module provided in an embodiment of the present invention; Figure 2 for Figure 1 A cross-sectional view of a semiconductor power module obtained by cutting along the cutting line AA'. Figure 3 for Figure 2 A magnified view of a portion of region B of the dashed coil; Figure 4 This is a three-dimensional structural diagram of a busbar terminal provided in an embodiment of the present invention; Figure 5 A side view of a busbar terminal provided in an embodiment of the present invention; Figure 6 A top view of a busbar terminal provided in an embodiment of the present invention; Figure 7 A three-dimensional structural schematic diagram of another busbar terminal provided in an embodiment of the present invention; Figure 8 A side view of another busbar terminal provided in an embodiment of the present invention; Figure 9 A top view of another busbar terminal provided in an embodiment of the present invention; Figure 10 A three-dimensional structural schematic diagram of another busbar terminal provided in an embodiment of the present invention; Figure 11 A side view of another busbar terminal provided in an embodiment of the present invention; Figure 12 This is a top view of another busbar terminal provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of the present invention to enable the reader to better understand the present invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0020] Reference Figures 1 to 3 ,in, Figure 1This is a schematic diagram of the structure of a semiconductor power module provided in an embodiment of the present invention; Figure 2 for Figure 1 A cross-sectional view of a semiconductor power module obtained by cutting along the cutting line AA'. Figure 3 for Figure 2 A partially enlarged schematic diagram of region B of the dotted coil. This invention provides a semiconductor power module, comprising: a substrate 1; an injection-molded housing 2 surrounding the substrate 1; and busbar terminals 3, each busbar terminal including a main body 31 and pin portions 32; wherein the pin portions 32 are connected to the substrate 1, and the main body 31 is embedded in the injection-molded housing 2; the pin portions 32 have a slot 4 on at least one side along their width direction.

[0021] In this embodiment, the pin portion 32 is connected to the liner plate 1. The main body portion 31 is embedded in the injection molded shell 2, meaning that the main body portion 31 is embedded in the injection molded shell 2 during the formation process of the injection molded shell 2. The busbar terminal 3, except for the pin portion 32, is entirely embedded in the injection molded shell 2. The injection molded shell 2 bears external forces, which helps to improve the rigidity of the busbar terminal 3, protect the pin portion 32, and thus prevent stress from being transmitted to the pin portion 32 of the busbar terminal 3, thereby improving the reliability of the pin portion 32 and improving the reliability of the connection between the pin portion 32 and the liner plate 1. The pin portion 32 has a slot 4 on at least one side along the width direction of the pin portion 32, which plays a certain buffering role on the stress between the pin portion 32 and the main body portion 31, further reducing the stress transmission to the pin portion 32 of the busbar terminal 3, and further improving the reliability of the connection between the pin portion 32 and the liner plate 1. During the operation of the semiconductor power module, the slot 4 of the pin portion 32 can also improve the heat dissipation of the busbar terminal 3, reduce the temperature of the busbar terminal 3, and enhance the current carrying capacity of the busbar terminal 3. In summary, the semiconductor power module of this application can achieve good mechanical protection and electrical connection, while achieving efficient heat dissipation, ensuring that it can maintain a low temperature during operation and improving the reliability of the semiconductor power module.

[0022] The enhanced current-carrying capacity of busbar terminal 3 reflects the low impedance and high current-carrying capacity of the semiconductor power module, which meets the requirements of high-power applications. In this embodiment, the semiconductor power module includes an insulated-gate bipolar transistor module. In other embodiments, the semiconductor power module includes other power modules.

[0023] In this embodiment, the liner 1 includes a first metal layer, an insulating layer, and a second metal layer stacked together. The structure and materials of the liner 1 are common knowledge in the art and will not be described in detail in this application.

[0024] In one embodiment, the semiconductor power module further includes a packaging substrate 5, which is located on the side of the substrate 1 opposite to the pin portion 32, and a portion of the injection-molded shell 2 is fixedly connected to the packaging substrate 5. The connection between the pin portion 32 and the substrate 1 can be that the pin portion 32 is connected to the first metal layer and the packaging substrate 5 is connected to the second metal layer, or the pin portion 32 is connected to the second metal layer and the packaging substrate 5 is connected to the first metal layer.

[0025] In one embodiment, the semiconductor power module further includes a chip (not shown) located on the side of the substrate 1 facing away from the packaging substrate 5 and connected to the substrate 1; wherein the chip is embedded inside the injection-molded housing 2. Specifically, the packaging substrate 5 is connected to the second metal layer, and the chip is connected to the substrate 1 by connecting the chip to the first metal layer; or the packaging substrate 5 and the first metal layer are connected, and the chip is connected to the substrate 1 by connecting the chip to the second metal layer. Since the chip is made of semiconductor material, the chip can be connected to the substrate 1 by soldering, silver sintering, or copper sintering, wherein the electrodes of the chip can be connected to the substrate 1 by wire bonding to achieve electrical connection between the chip and the surface metal layer of the substrate 1. The chip includes, but is not limited to, silicon chips, silicon carbide chips, or gallium nitride chips.

[0026] In one embodiment, the pin portion 32 includes a first pin portion and a second pin portion located between the main body portion 31 and the first pin portion. The first pin portion is connected to the substrate 1, and the second pin portion has a slot 4 on at least one side along its width direction. By avoiding the slot 4 being located on the first pin portion, which would reduce the contact area between the first pin portion and the substrate 1, and by placing the slot 4 on the side of the second pin portion, the reliability of the connection between the first pin portion and the substrate 1 can be improved, thus balancing the need to improve the reliability of the connection between the pin portion 32 and the substrate 1 with the need to improve the heat dissipation of the busbar terminal 3.

[0027] The fact that the pin portion 32 has a slot on at least one side along the width direction of the pin portion 32 means that the pin portion 32 has a slot on one side along the width direction of the pin portion 32, or that the pin portion 32 has slots on both sides along the width direction of the pin portion 32.

[0028] In one embodiment, there are multiple pin portions 32, which are independently arranged along the width direction of the pin portions 32. The slot 4 is located at the same position or different positions of the multiple pin portions 32. This further improves the heat dissipation effect of the busbar terminal 3.

[0029] In this embodiment, slots are provided on both sides of the pin portion 32 along its width direction as an illustration. The slots on the same pin portion 32 are arranged back-to-back. When slots 4 are located at the same position on multiple pin portions 32, adjacent slots 4 on adjacent pin portions 32 are arranged opposite each other. This improves the consistency of the slots 4 and increases production efficiency.

[0030] In other embodiments, the position of the slot 4 at each pin portion 32 can be selected according to actual needs and is not limited.

[0031] In other embodiments, the number of pins 32 is one.

[0032] In one embodiment, a coating layer (not shown) is provided on the top surface of the main body 31, and the injection-molded shell 2 exposes the top surface of the main body 31. The main body 31 is connected to external conductive terminals. The coating layer includes a silver plating layer. In this embodiment, the silver plating layer is produced using a cyanide silver plating process, which requires adhesion testing (cross-cut test, grade ≥5B) and corrosion resistance testing (neutral salt spray test, no corrosion after 48 hours) to ensure the reliability of the coating layer and improve the connection performance between the main body 31 and the external conductive terminals. At the same time, it reduces the corrosion rate of the busbar terminals 3 in humid and hot environments and salt spray environments, making it suitable for harsh working conditions and improving the environmental adaptability of the semiconductor power module.

[0033] The top surface of the main body 31 is exposed in the injection molded tube shell 2. The main body 31 is embedded in the injection molded tube shell 2, which means that the sides and bottom of the main body are embedded in the injection molded tube shell 2.

[0034] In one embodiment, the busbar terminal 3 further includes a transition portion 33 located between the main body portion 31 and the pin portion 32; the transition portion 33 is embedded in the injection-molded housing 2. The transition portion 33 being embedded in the injection-molded housing 2 means that the transition portion 33 is embedded in the injection-molded housing 2 during its formation process. The injection-molded housing 2 withstands external forces, which helps to improve the rigidity of the busbar terminal 3, protects the pin portion 32, and thus prevents stress transmission to the pin portion 32 of the busbar terminal 3, improving the reliability of the pin portion 32, thereby increasing the reliability of the connection between the pin portion 32 and the liner 1.

[0035] When the pin portion 32 includes a first pin portion and a second pin portion located between the main body portion 31 and the first pin portion, the transition portion 33 is located between the main body portion 31 and the second pin portion.

[0036] In one embodiment, the tensile strength of busbar terminal 3 is greater than or equal to 450 MPa at a temperature of 20°C to 25°C, and greater than or equal to 350 MPa at a temperature of 150°C. By setting tensile strength requirements at different temperatures, it can be ensured that the semiconductor power module maintains sufficient mechanical strength of busbar terminal 3 during long-term operation, whether at room temperature or in high-temperature environments. This ensures the stability and reliability of the electrical connection between pin portion 32 and substrate 1, eliminates the risk of loosening under vibration conditions, and meets service life requirements. Furthermore, by setting tensile strength requirements at different temperatures, it can be ensured that the semiconductor power module can adapt to different application scenarios and meet the usage requirements under various operating conditions.

[0037] In one embodiment, the main body 31 and the pin portion 32 are integrally formed; the material of the busbar terminal 3 includes a dispersion-strengthened copper alloy or oxygen-free copper. Further, the busbar terminal 3 also includes a transition portion 33, with the main body 31, pin portion 32, and transition portion 33 integrally formed. The busbar terminal 3 is manufactured using an integral stamping and bending process. Specifically, in one embodiment, the manufacturing process of the busbar terminal 3 includes: powder preparation → pressing → sintering → hot extrusion → precision machining.

[0038] When the material of busbar terminal 3 is a dispersion-strengthened copper alloy, it meets the following performance indicators:

[0039] When the material of busbar terminal 3 is dispersion-strengthened copper alloy, it can improve the matching of the thermal expansion coefficients of dispersion-strengthened copper alloy and liner 1, enhance the resistance to thermal stress, and improve the tensile strength of the metallurgical bonding of the lead portion 32 of busbar terminal 3 and the welding interface of liner 1. Under vibration conditions, there is no risk of loosening, which can meet the requirements of long service life. When the material of busbar terminal 3 is oxygen-free copper, compared with dispersion-strengthened copper alloy, the cost of oxygen-free copper is only 60% of the cost of dispersion-strengthened copper alloy. In order to make up for its lack of high-temperature strength, oxygen-free copper improves the hardness of busbar terminal 3 through cold rolling process, which meets the needs of medium-power semiconductor power module scenarios, such as scenarios with slightly lower current carrying capacity requirements (such as semiconductor power modules with rated current below 500A). The material of busbar terminal 3 is oxygen-free copper, which can take into account the requirements of high performance and low cost of semiconductor power modules.

[0040] In one embodiment, the busbar terminal 3 has a stepped structure, with one or more steps. When the busbar terminal 3 has multiple steps, it is preferable that the busbar terminal 3 has two steps, i.e., a two-stage stepped design. This effectively shortens the current path, reduces the parasitic inductance and parasitic resistance of the busbar terminal 3, and reduces the generation of Joule heat in the busbar terminal 3. At the same time, shortening the heat dissipation path of the busbar terminal 3 is beneficial to reducing the temperature of the busbar terminal 3. To simplify the stepped structure of the busbar terminal 3, a single-stage stepped design can be adopted, i.e., the busbar terminal 3 has one step. This helps to reduce the processing cost of the busbar terminal 3 while taking into account the high performance of the semiconductor power module, making it suitable for scenarios with slightly lower current carrying capacity requirements (such as semiconductor power modules with a rated current of less than 500A).

[0041] Continue to refer to Figure 1 and Figure 2 The busbar terminal 3 includes a DC busbar terminal and an AC busbar terminal 3C disposed opposite to each other at both ends of the liner plate 1. The DC busbar terminal includes a positive DC busbar terminal 3A and a negative DC busbar terminal 3B.

[0042] Specifically, refer to Figures 4 to 6 , Figure 4 This is a three-dimensional structural diagram of the positive DC bus terminal 3A. Figure 5 This is a side view of the positive DC bus terminal 3A; Figure 6 This is a top view of the positive DC bus terminal 3A. In this embodiment, the positive DC bus terminal 3A includes a main body 31, a pin portion 32, and a transition portion 33 located between the main body 31 and the pin portion 32, wherein the main body 31, the transition portion 33, and the pin portion 32 are integrally formed; the positive DC bus terminal 3A has two steps, and the side of the positive DC bus terminal 3A is "Z" shaped; the pin portion 32 includes a first pin portion and a second pin portion located between the main body 31 and the first pin portion, and the second pin portion has slots 4 on both sides along the width direction; there are multiple pin portions 32, and the multiple pin portions 32 are independently arranged along the width direction of the pin portion 32, and the slots of adjacent pin portions 32 are arranged opposite each other.

[0043] refer to Figures 7 to 9 , Figure 7 This is a three-dimensional structural diagram of negative DC bus terminal 3B. Figure 8 This is a side view of the negative DC bus terminal 3B; Figure 9 This is a top view of the negative DC bus terminal 3B. In this embodiment, the negative DC bus terminal 3B includes a main body 31, a pin portion 32, and a transition portion 33 located between the main body 31 and the pin portion 32, wherein the main body 31, the transition portion 33, and the pin portion 32 are integrally formed; the negative DC bus terminal 3B has two steps, and the side of the negative DC bus terminal 3B is "Z" shaped; the pin portion 32 includes a first pin portion and a second pin portion located between the main body 31 and the first pin portion, and the second pin portion has slots 4 on both sides along the width direction; there are multiple pin portions 32, and the multiple pin portions 32 are independently arranged along the width direction of the pin portion 32, and the slots of adjacent pin portions 32 are arranged opposite to each other.

[0044] refer to Figures 10 to 12 , Figure 10 This is a three-dimensional structural diagram of AC busbar terminal 3C. Figure 11 Side view of AC busbar terminal 3C; Figure 12This is a top view of the AC busbar terminal 3C. In this embodiment, the AC busbar terminal 3C includes a main body 31, a pin portion 32, and a transition portion 33 located between the main body 31 and the pin portion 32, wherein the main body 31, the transition portion 33, and the pin portion 32 are integrally formed; the AC busbar terminal 3C has two steps, and the side of the AC busbar terminal 3C is "Z" shaped; the pin portion 32 includes a first pin portion and a second pin portion located between the main body 31 and the first pin portion, and the second pin portion has slots 4 on both sides along the width direction; there are multiple pin portions 32, and the multiple pin portions 32 are independently arranged along the width direction of the pin portion 32, and the slots of adjacent pin portions 32 are arranged opposite each other.

[0045] The materials, tensile strengths, and other membrane layer configurations of the AC busbar terminal 3C, positive DC busbar terminal 3A, and negative DC busbar terminal 3B are as described in the foregoing embodiments.

[0046] The present invention also provides a method for manufacturing a semiconductor power module, comprising: providing a substrate 1; forming a busbar terminal 3, the busbar terminal 3 including a main body portion 31 and a pin portion 32, the pin portion 32 having a slot 4 on at least one side along the width direction of the pin portion 32; forming an injection molded shell 2 around the substrate 1; embedding the main body portion 31 into the injection molded shell 2 during the process of forming the injection molded shell 2 around the substrate 1; and connecting the pin portion 32 and the substrate 1 by ultrasonic welding.

[0047] During the process of forming the injection-molded shell 2 around the liner 1, the main body 31 is embedded in the injection-molded shell 2. The injection-molded shell 2 can tightly wrap the main body 31 during the molding process. After the main body 31 is embedded in the injection-molded shell 2, the two form a tightly integrated whole. The injection-molded shell 2 provides external support and protective frame for the main body 31. The injection-molded shell 2 withstands external forces, which helps to improve the rigidity of the busbar terminal 3 and avoid stress transmission to the pin portion 32 of the busbar terminal 3, thus providing good mechanical protection and electrical connection for the semiconductor power module.

[0048] Ultrasonic welding is a solid-state welding technology. Under the combined action of local ultrasonic energy and pressure, the interface between the lead portion 32 and the backing plate 1 of the busbar terminal 3 generates heat due to high-frequency friction, causing severe plastic and shear deformation in the local area. The connection is ultimately achieved through intermolecular forces or mechanical interlocking. Ultrasonic welding does not supply current to the lead portion 32 and the backing plate 1, nor does it apply a high-temperature heat source. It simply converts vibrational energy into frictional work, deformation energy, and a limited temperature rise between the lead portion 32 and the backing plate 1 under static pressure. Therefore, ultrasonic welding eliminates the need for solder and flux, thus eliminating volatile organic compound emissions, complying with RoHS environmental standards, enhancing process feasibility, and improving economic costs. It also helps improve production efficiency and yield. Furthermore, compared to traditional brazing and wire bonding processes, the ultrasonic welding process of this application enhances the connection reliability between the pin portion 32 and the substrate 1, generates less heat during welding, reducing the risk of aging and failure of the solder joints between the pin portion 32 and the substrate 1. This results in stronger current carrying capacity of the semiconductor power module during operation, facilitating more efficient heat dissipation and meeting the requirements of high power density and high reliability for semiconductor power modules.

[0049] A reliable connection between the pin portion 32 and the backing plate 1 can be achieved by optimizing the ultrasonic welding process parameters. Specifically, a reliable connection between the pin portion 32 and the backing plate 1 can be achieved by increasing the welding pressure, increasing the ultrasonic amplitude, and increasing the welding energy. The ultrasonic welding process parameter values ​​can be adjusted according to actual needs, as specifically limited in this application.

[0050] In one embodiment, the ultrasonic welding equipment includes an ultrasonic welding unit, which includes an ultrasonic generator and a welding head, the welding head being fixed below the ultrasonic generator. The end face shape of the welding head matches the shape of the pin portion of the busbar terminal; the material of the welding head includes titanium alloy.

[0051] In one embodiment, the ultrasonic welding equipment further includes: a motion system comprising an X-axis drive device, a Y-axis drive device, and a Z-axis drive device; a laser preheating unit fixed in front of the Z-axis drive device and moving along the XY direction; a detection unit fixed to the side of the Z-axis drive device and moving along the XY direction; and a control system connected to the detection unit, the laser preheating unit, and the ultrasonic welding unit, respectively.

[0052] In one embodiment, the detection unit includes a 3D camera, which is used to perform multi-angle scanning of the solder joints of the pin portion 32 and the substrate 1 after welding under the control of the control system to obtain three-dimensional point cloud data, and send it to the control system. The control system is used to identify and detect defects in the solder joints by comparing the three-dimensional point cloud data with a standard model.

[0053] In one embodiment, the motion system further includes a position sensor to monitor the movement positions of the detection unit, the laser preheating unit, and the ultrasonic welding unit in real time.

[0054] In one embodiment, the control system includes a programmable logic controller (PLC controller) that integrates a pressure sensor and an energy monitoring module to achieve closed-loop control of the welding process.

[0055] In one embodiment, the step of connecting the pin and the substrate using ultrasonic welding includes: driving the ultrasonic welding assembly with a Z-axis drive device until the welding head contacts the surface where the pin and the substrate are connected and applies pressure; then, turning on the ultrasonic generator and increasing the pressure applied by the welding head to the surface where the pin and the substrate are connected. The energy monitoring module of the control system monitors the energy of the ultrasonic generator; when the energy reaches a certain value, the ultrasonic generator stops working, and the welding head welds the pin and the substrate under pressure.

[0056] In one embodiment, the method for fabricating a semiconductor power module further includes: connecting the pin portion 32 and the substrate 1 by ultrasonic welding, and then using a detection unit to detect the welding quality.

[0057] The method for fabricating a semiconductor power module further includes: connecting the pin portion 32 and the substrate 1 by ultrasonic welding, and then cooling the semiconductor power module. The cooling process includes natural cooling to room temperature.

[0058] In one embodiment, the method for fabricating a semiconductor power module further includes: before connecting the pin portion 32 and the substrate 1 by ultrasonic welding, performing laser preheating treatment on the connection interface between the pin portion 32 and the substrate 1. The preheating temperature of the laser preheating treatment can be selected according to actual needs, and the preheating temperature of the laser preheating treatment can be monitored in real time by an infrared thermometer.

[0059] In one embodiment, the equipment used for laser preheating includes a fiber laser, which includes a focusing lens to adjust the spot diameter.

[0060] In other embodiments, laser preheating may not be required.

[0061] In one embodiment, the method for fabricating a semiconductor power module further includes: before performing laser preheating treatment on the connection interface between the pin portion 32 and the substrate 1, fixing the substrate 1 onto the packaging substrate 5, aligning the pin portion 32 of the busbar terminal 3 with the substrate 1, and fixing the injection molded shell 2 to the packaging substrate 5. This achieves the positioning and installation of the busbar terminal 3, the substrate 1, and the injection molded shell 2.

[0062] In one embodiment, the method for fabricating a semiconductor power module further includes cleaning the pin portion 32 and the substrate 1 respectively before performing laser preheating treatment on the connection interface between the pin portion 32 and the substrate 1. The purpose is to remove oil and oxide film from the surfaces of the pin portion 32 and the substrate 1. It should be noted that the soldering of the pin portion 32 and the substrate 1 is performed within 10 minutes after the cleaning process.

[0063] In summary, this application achieves significant performance improvements and functional optimizations compared to existing technologies through synergistic innovation in the material and structure of the busbar terminal 3 and the welding process between the busbar terminal 3 and the substrate 1. Specifically, the lead portion 32 of the busbar terminal 3 has a slot 4 on at least one side along its width direction. During the operation of the semiconductor power module, the slot 4 of the lead portion 32 can improve the heat dissipation of the busbar terminal 3, reduce its temperature, and enhance its current carrying capacity, thereby giving the semiconductor power module low impedance characteristics and high current carrying capacity, meeting the requirements of high-power applications. The material of the busbar terminal 3 includes dispersion-strengthened copper alloy or oxygen-free copper. The materials of the busbar terminal 3 and the substrate 1 are matched in terms of thermal expansion coefficient, tensile strength, and other properties, enhancing the thermal stability and structural reliability of the semiconductor power module. This invention uses a "laser preheating + ultrasonic welding" process to connect the lead portion 32 of the busbar terminal 3 and the substrate 1, enhancing the feasibility of the process and improving economic costs. At the same time, it improves production efficiency and yield, meeting the requirements of semiconductor power modules for high power density and high reliability.

[0064] In practical applications, the ever-increasing performance requirements of semiconductor power modules across various fields have made power density and reliability key technical indicators, leading to a focus on packaging technology and soldering processes. Higher power density means that semiconductor power modules can achieve greater power output within a smaller volume, which is significant for equipment miniaturization and weight reduction. Improved reliability ensures stable operation of semiconductor power modules in complex working environments, reducing the probability of failure and lowering maintenance costs. The semiconductor power module of this application includes an IGBT (Insulated Gate Bipolar Transistor) module. The improved reliability of this semiconductor power module enables it to withstand frequent vibrations, shocks, and harsh operating environments such as high humidity and strong electromagnetic interference in the rail transit field; in new energy vehicles, it can withstand frequent current changes and drastic temperature fluctuations; and in smart grids, it can handle high voltage, high current, and complex grid conditions. Therefore, the semiconductor power module of this application can be applied to various fields with different operating characteristics, which has significant practical value and application value for promoting the development of these fields, enabling the efficient and reliable application of semiconductor power modules in various sectors.

[0065] It should be understood that the terms "mechanism," "device," "component," etc., used in this application are merely one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they can be replaced by other expressions.

[0066] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention. In practical applications, the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification, and various changes can be made to them in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A semiconductor power module, characterized in that, include: Liner; Injection-molded tubular shell, located around the liner; Busbar terminal, the busbar terminal comprising a main body and a pin portion; The pin portion is connected to the liner, and the main body portion is embedded in the injection-molded tube shell; the pin portion has a slot on at least one side along the width direction of the pin portion.

2. The semiconductor power module according to claim 1, characterized in that, The pin portion includes a first pin portion and a second pin portion located between the main body portion and the first pin portion. The first pin portion is connected to the liner, and the second pin portion has the slot on at least one side along the width direction.

3. The semiconductor power module according to claim 1, characterized in that, The number of pins is multiple, and the multiple pins are independently arranged along the width direction of the pins. The slot is located at the same position or different positions of the multiple pins.

4. The semiconductor power module according to claim 1, characterized in that, The top surface of the main body is provided with a coating layer, the injection-molded tube shell exposes the top surface of the main body, and the main body is connected to an external conductive terminal; wherein, the coating layer includes a silver-plated film layer.

5. The semiconductor power module according to claim 1, characterized in that, The busbar terminal also includes a transition portion located between the main body portion and the pin portion; the transition portion is embedded in the injection-molded tube shell.

6. The semiconductor power module according to claim 1, characterized in that, At a temperature of 20℃ to 25℃, the tensile strength of the busbar terminal is greater than or equal to 450MPa; at a temperature of 150℃, the tensile strength of the busbar terminal is greater than or equal to 350MPa.

7. The semiconductor power module according to any one of claims 1 to 6, characterized in that, The main body and the pins are integrally formed; the material of the busbar terminals includes dispersion-strengthened copper alloy or oxygen-free copper.

8. The semiconductor power module according to any one of claims 1 to 6, characterized in that, The busbar terminals have a stepped structure, and the busbar terminals have one or more steps.

9. A method for fabricating a semiconductor power module, characterized in that, include: Provide lining plates; A busbar terminal is formed, the busbar terminal including a main body and a pin portion, and the pin portion having a slot on at least one side along the width direction of the pin portion; An injection-molded tube shell is formed around the liner; during the process of forming the injection-molded tube shell around the liner, the main body is embedded in the injection-molded tube shell; The pin portion and the substrate are connected by ultrasonic welding.

10. The method for fabricating a semiconductor power module according to claim 9, characterized in that, Also includes: Before connecting the pin portion and the substrate using ultrasonic welding, the connection interface between the pin portion and the substrate is subjected to laser preheating treatment.

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