Characteristics of surface flashover between foil conductors on printed wiring board

Impulse flashover strength between foil conductors on printed wiring boards with and without backside electrode was measured in air at 20°C and 40-45%RH. The smallest gap distance between the conductors is 0.05 mm. The thicknesses of the board were 0.3 mm and 0.8 mm. The experimental results show that the flashover for the board without backside electrode occurs when the electric field strength on the foil conductor edge reaches to about 100 kV/mm, which is independent of the gap distance. For the board with backing electrode, the flashover occurs at the independent value of the field strength only in the positive flashover at 0.8 mm of board thickness. In the other cases, the field strength at the flashover increases with the gap distance.