Intrinsic Mechanisms of Multi-Layer Ceramic Capacitor Failure

摘要

Studies related to leakage currents and intrinsic degradation of multilayer ceramic capacitors and related materials were performed. For the X7R materials studied, the following results confirmed that the charge carrier for current is the electron: constant leakage current; negative thermoelectric voltage; negligible galvanic voltage; presence of space charge limited current. Thermal activation energies decreased with voltage for barrier layer, COG and Z5U types, but not for X7R. Such voltage dependence, accompanied by superohmic current, is indicative of grain boundary (GB) dominated transport. Complex impedance plots give evidence of several resistive contributions, which could be attributed to grains and GB. Modelling of GB impedance indicates the importance of grain size homogeneity and grain curvature. (RH).