Dielectric breakdown strength measurement of silicon nitride ceramics by McKewon electrode

Abstract

Dielectric breakdown strength (DBS) of silicon nitride substrates with thicknesses of 0.25, 0.15, and 0.07 mm was measured by four types of electrodes: 10 mm spherical, 6 mm circular column shape, and 10- and 15-mm gold-coated film. In addition, the DBS was determined by a McKewon electrode in which the gap between the above spherical electrode and substrate was filled with epoxy resin. The DBS increased with decreases in the electrode diameter and the substrate thickness owing to the decreased number of defects within the measurement volume. The DBS measured by the McKewon electrode was the highest because the epoxy resin prevents electrical discharge under high voltages. However, the thickness-independent, intrinsic DBS, which was estimated from the results obtained by the McKewon electrode, was still significantly low compared to the theoretical DBS, indicating that various internal defects such as pores and boundary phases lower the DBS.