Influence of the horizontal distance between electrodes on the conducting performance of ZnO-based adaptive composites

SiC IGBT has the advantages of high withstand voltage, high operating temperature, fast switching speed and low loss. However, these characteristics lead to its encapsulated insulation system withstanding more severe electrothermal stress, causing partial discharges. ZnO-based adaptive composites are expected to play a role in power electronics packaging due to their excellent nonlinear conductivity. In this paper, 40 vol% ZnO/Silicone Rubber adaptive composites were prepared with the horizontal distance between electrodes of 50 um, 100 um, 500 um, 1 mm and 2 mm. Keithley 2410 digital source meter was adopted to measure their I-U curves. Results show that only ZnO composites with the horizontal distance between electrodes of 2 mm can’t turn to the conducting state with increasing applied voltage. When the horizontal distance increases from 50 um to 1 mm, the I-U curves shift to the right, ILeakage decreases from 3.06×10^-8 A to 8.03×10^-9 A, and U_10uA increases from 908 V to beyond 1100 V. The results were compared and analyzed by mathematical and physical models. This work provides a pregnant reference for the practical application of ZnO-based composites in power electronic packing.