A Study of Low Leakage Failure Mechanism of X7R Multiple Layer Ceramic Capacitor (MLCC)

This paper presents the result of a study of a particular failure mechanism of BaTiO3 MLCC (multiple layer ceramic capacitor). A unique technique of cross-section alternating with emission microscope analysis is developed to precisely locate the failure site for capacitors exhibiting low leakage current in mu A range. Thermal Imaging Microscope, Photon Emission Microscope, SEM, STEM/EDS and TEM electron diffraction pattern are employed for the characterization of these low leakage failures. Evidence of high concentration impurities are detected in the dielectric layer of BaTiO3 grain boundaries as well as inside certain grains. TEM diffraction imaging at the failure site shows distinguishingly different diffraction patterns within the matrix of BaTiO3 crystal structure. The evidences point to a combination of impurities at grain boundaries and BaTiO3 crystal change induced by impurity as the failure mechanism.