Experimental results on the influence of fluxes on partial discharge onset in PCB solder joints

This work concerns the development of an experimental set-up for assessing the influence of fluxes on Partial Discharge (PD) onset in High Voltage (HV) devices soldered on Printed Circuit Boards (PCBs). In particular, the work considered the effects of three types of fluxes chosen in agreement with the directions of the Materials and Processes Division at ESA/ESTEC. Contaminated samples are formed by a standard FR-4 PCB board with a pair of copper electrodes and a protocol of contamination has been applied for all samples. The measuring system is placed inside a shielded chamber and provides measurements of Corona Inception Voltage (CIV), Corona Extinction Voltage (CEV) and PD amplitudes collected in a vacuum chamber with controlled temperature fixture. The results shows that flux Alpha 850-33 has the mean CIV smaller than other types of fluxes and the same results is observed for the mean CEV. Also the PD amplitudes are greater for samples contaminated with flux Alpha 850-33 than the other two types and similar in value for samples without flux.