Effect of Temperature on Electrical Tree and Partial Discharge Characteristics of Double Layer PCB

The core chip of the power device generates significant heat during operation, which requires sufficient heat dissipation through leads and packaging materials. Printed circuit board (PCB) is a common packaging material for power devices. Its multi-layer structure can not only produce partial discharge when subjected to intensive electric field and elevated temperature, but also grow electrical trees, which eventually leads to breakdown over extended service age. This paper employs a double-layer V-shaped electrode setup to simulate the packaging environment of power devices, with samples heated in an oil bath. Images of electrical tree growth and partial discharge information were recorded at temperatures of 40 °C 50 °C, 60 °C and 70 °C. The impact of temperature on electrical tree initiation was analyzed by phase-resolved diagram of partial discharge (PRPD) and partial discharge (PD) magnitude. It was found that during the growth of the electrical tree, there is a sudden reduction on PD magnitude for a period of time (growth stage) when temperature is low, and this growth stage gradually shortened and disappeared when the test temperature increased. Combined with the discharge sequence analysis and voltage difference (dV) plots, the characteristics of discharge voltage difference during the transition from non-conductive to conductive tree were analyzed. Studying the relationship between electrical tree propagation and PD magnitude at various temperatures, it is found that the growth rate of the electrical tree is positively correlated with the number of discharges.