Role of PbO and Ag on Insulation Resistance Degradation in Relaxor-Based MLCs


  • W. Heubner—contributing editor


The relationship between the grain boundary phase and insulation resistance of dielectric layers in multilayer ceramic capacitors (MLCs) was clarified, leading to a proposal for the mechanism of insulation resistance degradation. A Pb-rich secondary phase was present at grain boundaries, and a small amount of Ag was detected from the secondary phase, while no secondary phase existed in dielectric layers with normal insulation resistance. These results suggest that diffusion from an internal electrode into the secondary phase in dielectric layers is responsible for the extremely low insulation resistance: oxygen vacancies, formed as a result of substitution of Ag for Pb, may play a role in lowering insulation resistance.