Effect of Low Pressure and Magnetic Field on Dielectric Breakdown of Printed Circuit Board

Epoxy resin laminate on which two copper electrodes were printed as printed circuit board (PCB) had been employed to investigate the effect of low pressure and magnetic field on dielectric breakdown at dc voltage application. The sample was placed in an artificial atmospheric chamber, which was reduced by a rotary pump from 100 kPa to 5 kPa. The magnetic field was produced by a couple of permanent magnets which was fixed to make the E times B drift away, drift into and parallel to PCB. Magnetic flux density was made at 120 mT, 180 mT and 240 mT respectively. The time to dielectric breakdown was measured. The results showed that with reducing the pressure, the time to the breakdown increased. With E times B drift into PCB surface, the time to the breakdown was shortened; with E times B drift away from the surface, the time to the breakdown was delayed. Furthermore, effect of magnetic field on the breakdown increased with reducing the pressure. It indicates that the dielectric strength of PCB is changed by the application of magnetic field and low pressure