Dynamic Conductivity Processes in Glass-Filled Polyimide Circuit Boards

Assessments of the risk of electrostatic discharge(ESD) due to spacecraft charging require knowledge of materials’conductivity in flight-like conditions. Due to the difficulty inmeasuring and modeling conductivity in space conditions, it iscommon to conservatively assume the minimum steady-state darkconductivity. This study investigates impacts of charging rate,temperature, electric field, and time on the dynamic conductivityof glass-filled polyimide circuit board materials. The chargestoragemethod of measuring conductivity was used on samplesmounted on a cold plate in vacuum. Charging was performedincrementally with conductivity measured between electronexposures. Beam ramp down conditions were varied to investigatethe impact of charging rate on the observed charge decay.Observed conductivity does not appear to depend on the rate ofbeam shut off. Conductivity does depend strongly on electric field,time, and temperature. These effects typically are studiedseparately.