Guoyou Liu

Reliability enhancement by integrated liquid cooling in power IGBT modules for hybrid and electric vehicles

Abstract Insulated Gate Bipolar Transistor (IGBT) modules in power train system of Hybrid and Electric Vehicles (HEV/EV) are working in harsh environment and high reliability and long lifetime are required. In this work, reliability enhancement by integrated liquid cooling structure in HEV/EV IGBT module is investigated. The thermal resistance of junction to heat sink can be reduced more than 50% by direct liquid cooling as eliminating thermal grease layer, so both active and passive temperature swings decrease significantly which will enhance module reliability and lifetime. The lifetime of modules with conventional and integrated liquid cooling structures are estimated under mission of standard driving cycles. We found that lifetime is prolonged obviously by direct cooling pin–fin base plate, and the compact module also makes the application power system simple and reliable.

Status and Trend of SiC Power Semiconductor Packaging

With the superior electrical and thermal properties of wide band gap materials, Silicon Carbide (SiC) devices are capable of working at high power density, high temperature, high frequency, high voltage and high efficiency. Although the substantial investigation on SiC material, device and packaging technologies have been done, there are a series of problems needed to be solved, such as the material quality, cost and packaging for high power density and high temperature. In this work, the status and trend of SiC power device packaging are addressed. A brief review of hybrid and full SiC power module in terms of market prospect, module structure, material and technologies are discussed. Then, the performance and reliability of Si and SiC modules are compared, including the thermal resistance, power loss and power cycling capability etc. finally, the packaging trend of SiC module for high thermal performance, high temperature and high reliability are proposed.

Mitigation of challenges in automotive power module packaging by dual sided cooling

Packaging of power semiconductor modules is facing huge challenges from automotive customers in terms of performance, temperature, reliability, weight, volume and cost etc. It is believed that choice of the power module structure, material and assembly technology are key factors for mitigating the challenges. Among them, the cooling structure and of the module is of most importance to address these issues. In this paper, the dual sided cooling module for Hybrid and Electric Vehicles (HEV/EV) is proposed as an effective methodology for addressing these automotive level challenges. It is found that the thermal performance is improved significantly by cooling the module on both sides, which enhances the electrical performance at high power, high switching speed and improves thermal stability. The electrical performance and reliability are further improved by wire bondless interconnection and ultrasonic welding of power terminals. By eliminating the baseplate in the module, the weight, volume and cost are reduced accordingly.

Applications of low temperature sintering technology as die attach for high temperature power modules

Silver-based low temperature sintering technology (LTST) is becoming a promising alternative to bond or joint the large area joints as die attach for high temperature power modules. A review of the silver-sintered die attach technologies will be presented in this paper, as well as a roadmap of challenge of the state-of-the-art silver sintering. Then, highlighted are the methodology of sintering process, the different types and application of sintered Ag paste, the effects of the process parameters on the sintering layer, and the quality evaluations of sintered joints by means of destructive or non-destructive tests. Finally, the applications as well as challenges of silver sintering for high temperature power modules are proposed.

Status and Trend of Power Semiconductor Module Packaging for Electric Vehicles

Power semiconductor modules are the core components in power-train system of hybrid and electric vehicles (HEV/EV). With the global interests and efforts to popularize HEV/EV, automotive module has become one of the fast growing sectors of power semiconductor industry. However, the comprehensive requirements in power, frequency, efficiency, robustness, reliability, weight, volume, and cost of automotive module are stringent than industrial products due to extremely high standards of vehicle safety and harsh environment. The development of automotive power module is facing comprehensive challenges in designing of structure, material, and assembly technology. In this chapter, the status and trend of power semiconductor module packaging for HEV/EV are investigated. Firstly, the functionality of power electronics and module in HEV/EV power-train system, as well as the performance requirements by automotive industry, is addressed. A general overview of HEV/EV module design and manufacturing is discussed. Then, the typical state-of-the-art commercial and custom HEV/EV power modules are reviewed and evaluated. Lastly, the packaging trends of automotive module are investigated. The advanced assembly concept and technology are beneficial to thermal management, minimized parasitic parameters, enhancement of thermal and mechanical reliability, and the reduction of weight, volume, and cost.