Degradation Behavior of BaTiO_3 Dielectrics for MLCCs by an Accelerated Life Test With Voltage and Temperature Stress Factors

摘要

An accelerated life test (ALT) was designed under voltage and temperature stresses using 1005 type multilayer ceramic capacitors (MLCCs) based Ni-BaTiO_3, and failure analysis was also conducted to compare the individual stress. The inverse power and Arrhenius models were applied to the voltage and temperature accelerated tests, respectively, and times to failure (TTF) of MLCCs under individual stress were measured. The stress-life relation was plotted from obtained life data, and characteristic life (B_(63.5)) was calculated at the same condition of 130℃ and 3 times rated voltage. B_(63.5) under the voltage stress was 15.91 min and that of the temperature stress was 17.23 min. It was determined that the voltage stress had more influence on the degradation of insulation resistance for MLCCs. As a result of an analysis of the chemical bonding state from the dielectric ceramic and inner electrodes, according to increase in the stresses, the binding energy of Ti 2p_(3/2) and Ni 2p_(3/2) peak changed, which generated oxygen vacancies. These oxygen vacancies accelerated the degradation under the high-voltage stress, caused the reduction of the BaTiO_3 ceramic and oxidation of the Ni electrode, and consequently decreased the insulation resistance.