Achieving high-efficiency electrically insulating ceramic layer formed on SiCp/Al composite by bipolar pulsed PEO for novel integrated strategy

Abstract

Thermal conductive insulating ceramic materials are urgently needed in the packaging applications for modern electronic devices owing to their multi-functionality. The electrically insulating Al2O3 ceramics with large thickness and high compactness is designed on SiCp/Al baseplate via plasma electrolytic oxidation (PEO) technique, which provides a new idea for the package structure of the IGBT power module. However, porous characteristics of PEO inorganic ceramics hinder effective electrical insulation and heat conduction in practical applications. Herein, the bipolar pulsed (BP) and unipolar pulsed (UP) PEO are tailored to obtain the ceramics respectively. In contrast, the BP mode enables the ceramic layer significantly thickened and densified due to the soft sparking discharge. Combined with outstanding electrical resistivity over 1012 Ω·cm, high breakdown voltage of 716 ± 38 V, high dielectric strength of 15.9 ± 0.8 V/μm, the BP ceramic layer exhibits superior performance in electrical insulation. Moreover, the BP shows excellent thermal cycling stability (>200 cycles), quite good thermal stability, and dielectric stability in the temperature range of 25 °C to 300 °C to realize high-temperature electrical insulation. This work paves a novel way to design and optimize power electronic module package materials and structures.