Discharge inception on printed circuit board in an artificial fog

The process leading to surface discharge inception on a printed circuit board (PCB) in artificial fog was investigated, with particular attention to the discharge inception time. We employed a fog environment formed by an ultrasonic vibration saline fog generator at room temperature, and the conductance was set at 2.0 mS/cm, 2.5 mS/cm and then up to 5.0 mS/cm. The experiment was carried out under dc power. An epoxy resin laminate PCB was employed to investigate the effects of test voltage and saline fog conductance on the surface discharge inception. The relation between the inception time of the discharge and the test voltage was examined. The inception voltage and the capacitance of the PCB were measured. The study revealed that the discharge inception time decreases with increasing test voltage and conductance. The inception voltage decreases with increasing the conductance. The inception time and capacitance increase with increasing exposure time.