Highly accelerated resistance degradation and thermally stimulated relaxation in BaTiO3-based multilayer ceramic capacitors with Y5V specification

Correlation between resistance degradation and thermally stimulated relaxation in commercial BaTiO3-based multilayer ceramic capacitors (MLCCs) with Y5V specification were analyzed. The temperature dependence of dielectric behavior shows that the polarization response is activated by increasing AC electric field, especially the dielectric permittivity peak value. Highly accelerated degradation test and thermally stimulated depolarization current (TSDC) measurements were performed. It has been found that the reliability of capacitors greatly depends on temperature and electric field. TSDC of capacitor dielectrics before and after degradation were also investigated for a fundamental understanding of the resistance degradation mechanism. Two TSDC relaxation peaks were detected, and were correspondingly assigned to in-grain and across-grain boundary migration of oxygen vacancies. Contrary to our predictions, the degraded sample shows an evident decrease in TSDC density and activation energy of the across-grain boundary relaxation compared with the ceramic capacitor without degradation. It is demonstrated that the insulation resistance degradation is associated with the migration of oxygen vacancy defects. The strong degradation indicates that more oxygen vacancies may jump out of potential well and probably form defect clusters. Such clusters will not have the mobility to relax back, subsequently causing the decrease in the measured relaxation current.