The electrical properties of thin film SiNx that has been deposited with PECVD method at 150°C and 250°C are investigated on evaporated and electroplated Au substrates. The aim is to extract the parameters that can be introduced in modeling and simulation tools for MEMS design. The present work provides information on the dielectric charging and its dependence on the film thickness, the deposition conditions, the substrate roughness and metallic contacts.