Substrate-Less Power Semiconductor Packaging for the Potential of Recyclability

Recyclability is being pursued in power electronics. Power semiconductor devices and modules are some of the core components, featuring high material and energy costs in fabrication, but with limited service lifetime. This study explores a packaging structure that might improve their recyclability in the future. The study focuses on the cooling and electric insulation aspects of the substrate-less design. A customized three-sectional heat pipe is used to replace the ceramic-based direct bonded copper (DBC) or active metal brazed (AMB), which are difficult to recycle. It is assumed that the commonly used thermoset plastic casing and silicone gel can be replaced by recyclable polyetherimide (PEI) encapsulation. A design procedure is proposed to match the specifications of the heat pipe with the thermal dissipation and electric insulation requirements of the power device. The thermal resistance of junction heatsink is shown to be much lower than that of a typical substrate. The electric insulation strength is compared for different working fluids to identify a satisfactory solution.