Special Issue Explores Breakthroughs in High-Reliability Power Device Packaging for Electric Vehicles
The rapid evolution of electric vehicles (EVs) has placed unprecedented demands on the core components that drive their performance, efficiency, and reliability. Among these, power semiconductor devices stand as the technological backbone of motor drives, battery systems, and onboard chargers. As the automotive industry accelerates toward electrification, the limitations of traditional silicon (Si)-based power devices have become increasingly apparent. With decades of refinement, Si technology is nearing its physical performance ceiling, particularly in terms of switching speed, thermal tolerance, and energy efficiency. This bottleneck has catalyzed a global shift toward wide-bandgap semiconductors, primarily silicon carbide (SiC) and gallium nitride (GaN), which offer superior electrical and thermal properties essential for next-generation EVs.
Recognizing the critical role of advanced power electronics in shaping the future of transportation, Journal of Power Supply has released a landmark special issue titled High Reliability Power Device Packaging and Assistant Technology in EV Application. Edited by a consortium of leading researchers—Yunhui Mei from Tiangong University, Puqi Ning from the Institute of Electrical Engineering at the Chinese Academy of Sciences, Guangyin Lei from Fudan University, and Zheng Zeng from Chongqing University—the collection presents 30 peer-reviewed papers that collectively chart the cutting edge of power device research, with a laser focus on packaging, modeling, thermal management, reliability, and intelligent monitoring systems tailored for automotive environments.
The transition from silicon to SiC and GaN is not merely a material upgrade; it represents a fundamental rethinking of power electronics architecture. Wide-bandgap materials boast higher breakdown electric fields, wider bandgaps, greater thermal conductivity, and higher electron saturation velocities. These attributes enable power devices to operate at higher voltages, frequencies, and temperatures, leading to smaller, lighter, and more efficient power conversion systems. For EVs, this translates into extended driving range, faster charging, improved powertrain responsiveness, and reduced system footprint. However, these performance gains come with new engineering challenges, particularly in packaging, where mechanical, thermal, and electrical stresses are amplified under the harsh operating conditions of automotive applications.
One of the most pressing challenges in leveraging wide-bandgap devices is accurate modeling. The high-speed switching transients of SiC MOSFETs generate complex electromagnetic interference (EMI) spectra that traditional idealized models fail to capture. To address this, researchers from North China Electric Power University, led by Zhibin Zhao, developed a frequency-domain analytical model derived from time-domain equations using Fourier transform theory. Their work provides a more realistic representation of switching behavior, enabling better prediction of EMI and system-level performance. Accurate thermal modeling is equally critical, as junction temperature directly influences device reliability and lifetime. A team from Tianjin University of Technology, including Zhaoping Wang and Mingxing Du, introduced a hybrid thermal network model that integrates the strengths of both Cauer and Foster networks. By accounting for solder layer aging, their model achieves higher accuracy in junction temperature estimation, a vital input for thermal management and reliability assessment.
Thermal management remains a cornerstone of power module design. As power density increases, so does heat flux, making efficient heat dissipation paramount. Researchers from Fudan University, including Shuhua Liao, designed a double-sided water-cooled SiC power module and systematically evaluated the impact of chip layout spacing on temperature uniformity and switching characteristics. Their findings offer quantitative guidance for optimizing thermal performance while minimizing parasitic inductance. Meanwhile, a group from Tiangong University, led by Gaojia Zhu, proposed a novel topology optimization method for heat sinks using nested neural networks with synchronous learning. This approach significantly accelerates the iterative design process compared to conventional topology optimization methods, enabling faster development of high-performance cooling solutions.
Active thermal control is emerging as a sophisticated strategy to manage temperature dynamics in real time. A comprehensive review by Yigeng Huangfu and colleagues from Northwestern Polytechnical University outlines various active thermal management techniques, categorized by control level—device-level, system-level, and multi-parameter integrated methods. The review highlights trends such as dynamic cooling control, adaptive fan speed regulation, and predictive thermal management based on load forecasting, all aimed at maintaining optimal junction temperatures under variable driving conditions.
The physical packaging of power modules is undergoing radical innovation to meet the demands of high power density and long-term reliability. Traditional wire bonding is being challenged by advanced interconnection technologies. A review by Hu’an Hu and team from Beijing University of Technology examines the state of Cu-Sn full intermetallic compound (IMC) joints, which offer superior thermal and mechanical stability compared to conventional solder joints. These IMC joints are formed through solid-state reactions and are particularly suited for high-temperature operation, making them ideal for EV applications. However, the authors also identify challenges in process control and reliability validation that must be addressed for widespread adoption.
In parallel, structural innovations are pushing the boundaries of electrical performance. Researchers from Chongqing University, including Rongyao Ma and Peng Sun, optimized the layout of multi-chip SiC modules and integrated pin-fin heat sinks to reduce both parasitic inductance and junction-to-case thermal resistance. Their work demonstrates a holistic electro-thermal co-design approach that balances electrical efficiency with thermal management. Another team from the same institution, led by Siyuan Wang, developed a 3D stacked packaging technique for bidirectional switch SiC modules. By vertically stacking chips and optimizing the geometric structure, they achieved significant inductance reduction, which is crucial for minimizing voltage overshoot and electromagnetic noise during fast switching.
The use of large-die SiC MOSFETs is another pathway to higher power density. Dongrun Li and colleagues from the Chinese Academy of Sciences designed a high-power-density SiC module using large-area chips. Their results show improved current conduction capability and reduced temperature gradients across the die, leading to enhanced electrical performance and reliability. Similarly, Xiaoshuang Hui and Puqi Ning’s team developed a 1200 A IGBT module in the EconoDUAL package with an 800 V bus voltage. By employing a layered direct bonded copper (DBC) layout, they optimized the three-dimensional structure to improve both electrical and thermal performance, showcasing the potential of advanced packaging techniques even for established silicon technologies.
Gate driving and application circuits are critical interfaces that determine how power devices are utilized in real systems. The high dV/dt and dI/dt associated with SiC devices require robust gate drivers to prevent false triggering and ensure reliable operation. Changzhi Yao and colleagues from the Beijing Institute of Space Launch Technology analyzed the impact of gate-source voltage on the turn-on time of SiC MOSFETs and evaluated the performance of domestically produced devices after localization. Their work is particularly relevant given the strategic importance of supply chain independence in the semiconductor industry.
For multi-level converters, precise gate drive design is essential to prevent shoot-through and manage dynamic current sharing. Langlang Yu and team from Hefei University of Technology designed a driver circuit for NPC (Neutral Point Clamped) three-level IGBT modules, incorporating enhanced drive current, anti-shoot-through protection, and adjustable dead-time functionality. Their experimental validation confirms the effectiveness of the design in improving switching behavior and system reliability.
In the realm of power conversion topologies, innovative circuit designs are being developed to improve efficiency and fault tolerance. Zhengge Chen and colleagues from Southwest Jiaotong University proposed a bridgeless Buck-type PFC (Power Factor Correction) converter with hybrid operation modes. By operating in Buck mode during the positive half-cycle and Buck-Boost mode during the negative half-cycle, their converter achieves high power factor and reduced conduction losses. Similarly, Qinghua Chen’s team from Hefei University of Technology introduced a modified LLC resonant converter with high fault-tolerant capability. Their topology ensures stable output voltage even when a switch fails, enhancing system reliability for critical EV applications.
Electromagnetic interference (EMI) remains a persistent challenge in high-frequency power electronics. Pan Wang and colleagues from Hubei University of Technology designed a DC EMI filter with a soft-start function to mitigate inrush current and noise during power-up. Their design methodology, based on noise source analysis and impedance matching, ensures effective insertion loss while preventing filter saturation.
As power modules become more compact and operate under higher stress, reliability analysis has become a central focus of research. The high-frequency switching inherent in EV powertrains induces thermal cycling, which can lead to fatigue failure in solder joints, bond wires, and other interconnects. Lezhou Li and team from Shandong University conducted a detailed study on wire bonding parameters for SiC power modules, analyzing the influence of bonding force, time, and material on reliability. Their findings provide valuable insights for optimizing the wire bonding process to enhance mechanical robustness.
Press-pack IGBTs, commonly used in high-power applications such as traction inverters and HVDC systems, require specialized health management strategies. Kai Xiao and colleagues from China Southern Power Grid have made significant contributions in this area. They reviewed existing health monitoring methods for press-pack IGBTs, classified them based on sensing techniques and data analysis approaches, and summarized the principles and characteristics of various lifetime prediction models. In a follow-up study, they developed dedicated software for lifetime assessment, integrating multi-physics models that account for thermal, mechanical, and electrical aging factors. Their work enables predictive maintenance and condition-based monitoring, reducing unplanned downtime and improving system availability.
Degradation mechanisms in SiC MOSFETs under dynamic stress conditions are another critical area of investigation. Luwei Zuo and Zhen Xin from Hebei University of Technology developed a test platform to study device degradation under dynamic high-temperature reverse bias (DHRB) stress. Their experiments revealed that the gate oxide above the JFET region and the body diode are particularly vulnerable to degradation, providing crucial data for improving device design and qualification standards.
Failure detection in auxiliary systems, such as valve base electronics (VBE) in HVDC converters, is also gaining attention. Longchen Liu and team from State Grid Sichuan Electric Power Research Institute applied deep learning techniques to detect component failures on VBE circuit boards. By enhancing the SqueezeNet algorithm, they achieved high accuracy in identifying defective components while minimizing computational overhead, making the method suitable for real-time monitoring applications. In another study, the same team proposed a point pattern matching method for automated visual inspection of PCB defects, addressing the limitations of manual inspection in terms of speed and consistency.
Online monitoring is increasingly recognized as a key enabler of smart power electronics. Real-time monitoring of parameters such as threshold voltage, gate oxide health, and junction temperature allows for adaptive control and early fault detection. Shengxu Yu and colleagues from Huazhong University of Technology introduced an online monitoring method for SiC MOSFET gate oxide health based on gate reference voltage. By extracting a reference signal from the gate circuit, their method enables continuous assessment of oxide degradation without interrupting normal operation.
Accurate measurement of threshold voltage is essential for monitoring device aging. Bojun Yao and team from Beijing University of Technology investigated the influence of drain-source voltage on threshold voltage measurement using the transient current method. They found that the electric field across the gate oxide affects trap charge states, which in turn impacts the measured threshold voltage. Their findings underscore the need for standardized measurement conditions to ensure data consistency.
Current sensing accuracy is vital for control and protection functions. Yu Yao and colleagues from Hebei University of Technology addressed the integration drift issue in PCB Rogowski coils by implementing a reset-type integrator circuit. They also proposed a digital compensation strategy to eliminate droop error, significantly improving measurement accuracy over long durations.
The special issue underscores a clear trend: the future of automotive power electronics lies in the integration of advanced materials, innovative packaging, intelligent control, and data-driven reliability management. While significant progress has been made, challenges remain in achieving fully intelligent design, high-quality manufacturing, and accurate health prognostics. The editors emphasize the need for interdisciplinary collaboration between power electronics, materials science, thermal engineering, and data analytics to overcome these hurdles.
As the automotive industry continues its electrification journey, the research presented in this special issue provides a comprehensive roadmap for developing next-generation power modules that are not only more efficient and compact but also more reliable and intelligent. The work of Mei Yunhui, Ning Puqi, Lei Guangyin, and Zeng Zheng, along with their co-authors, represents a significant step forward in enabling the widespread adoption of electric vehicles through technological innovation at the component level.
Yunhui Mei, Puqi Ning, Guangyin Lei, Zheng Zeng, Journal of Power Supply, DOI: 10.13234/j.issn.2095-2805.2024.3.15