AC and impulse breakdown of polluted surface on printed wiring board

Electronic equipment has been used in various environments indoors and outdoors. Electronic equipment has become more compact and has operated under higher electric fields. Therefore the design of suitable insulation has become extremely important. This paper describes the results that we obtained in investigation of AC creepage breakdown and impulse creepage flashover voltages on printed wiring boards in four different experimental environments. It was determined that creepage breakdown decreased significantly only in the specimen kept in a high humidity atmosphere after being sprayed with salt water. It was determined that the decrease of breakdown voltage caused by a background electrode was largest when creepage distance nearly equalled the insulation thickness. The influence of a background electrode on breakdown voltage was insignificant in the case where specimens had been kept in a high humidity atmosphere after being sprayed with salt water