ROLE OF PBO AND AG ON INSULATION RESISTANCE DEGRADATION IN RELAXOR-BASED MLCS

The relationship between the grain boundary phase and insulation resis tance of dielectric layers in multilayer ceramic capacitors (MLCs) was clarified, leading to a proposal for the mechanism of insulation resi stance degradation. A Pb-rich secondary phase was present at grain bou ndaries, and a small amount of Ag was detected from the secondary phas e, while no secondary phase existed in dielectric layers with normal i nsulation resistance. These results suggest that diffusion from an int ernal electrode into the secondary phase in dielectric layers is respo nsible for the extremely low insulation resistance: oxygen vacancies, formed as a result of substitution of Ag for Pb, may play a role in lo wering insulation resistance,