Degrading effect of high-altitude corona on electronic circuit boards

A printed circuit board with attached components has been subjected to corona discharges for 200 h at a pressure of 8.66 Pa. The preliminary investigations indicate that: (1) High altitude corona discharges produce visible surface degradation on electronic circuit boards and mounted components. (2) The deterioration is most pronounced in the regions where the electric field is greatest. (3) The solder coating has been removed in localized areas of the interconnecting paths and the underlying copper is now exposed. (4) The circuit board becomes covered with a white dust, the composition of which is still unknown. (5) The deterioration increases with increased exposure up to 200 h, the maximum exposure time considered here.>