Impact of the Printed Circuit Board Geometrical Design on the AC Breakdown and Partial Discharge Activity in Air
Résumé
The main objective of this paper is to study the voltage withstand characterization of Printed Circuit Board (PCB) substrates for the development of three-dimension (3D) power modules. Classical power electronics gel encapsulation is substituted by air encapsulation in order to benefit of dielectric and thermal cooling aspects. Breakdown voltage (BDV) and Partial Discharge (PD) measurements are studied for the voltage withstand characterization with different geometrical designs of the two-side metallization of PCBs. BDV measurements are performed with classical alternative (AC) voltage constraints. Next, PD Inception Voltage (PDIV) is assessed for each PCB design with an AC constraint and a classical power electronics square voltage constraint, i.e. high switching frequency and dV/dt. Experimental results showed no PCB material degradation during BDV events and underlined a breakdown path across PCB surface into the air. The increase of two-side metallization creepage distance allowed a linear increase of BDV, while geometrical PCB design is less sensitive for PDIV values.
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