Pulsed high-voltage breakdown of thin film Parylene-C

Measurements of polymer dielectric high-voltage (HV) strength at thicknesses in the 1 to 10 μm range have always been difficult to validate and repeat. We report results of experiments done using Parylene-C films of 2-, 4-, and 6-μm thickness in a series of configurations intended to determine the high-voltage breakdown (HVB) of the material itself with a minimum of externally undefined parameters. The experiments used an alumina substrate coated with a conductive gold film with Parylene-C film deposited on top of the lower gold film. One edge of the lower gold film was exposed to provide electrical connection, and a triangular or circular gold electrode was deposited on the surface of the Parylene-C. The intent was to test the dielectric breakdown strength of bare Parylene-C as well as to evaluate the effects of field enhancements produced by the two electrode shapes.