Influence of BaTiO_3 Sources and Dopant Levels on Annealing of BME X7R Formulations

摘要

Several dielectric compositions for high capacitance BME multilayer ceramic capacitor (MLCC) applications have been examined. These formulations are based on BaTiO_3 precursors which were synthesized from both solid state and a precipitated oxalate technique, that contained different dopant levels. The intention of this study was to investigate the intrinsic relationship between the reoxidation conditions and the electrical properties (including HALT) of the final MLCC and then correlate this information with the BaTiO_3 synthesis technique. The reoxidation conditions investigated in this study were temperature (800 - 1000℃), PO_2 (7 - 53 PPM's) and soak time (3-9 hrs). Another intention of this study was to draw a correlation between annealing conditions and the amount of dopants used. It was concluded that the optimal annealing condition which resulted in the highest insulation resistance and reliability (while maintaining all other properties) was strongly dependent on the synthesis technique of the BaTiO_3 used as well as the dopant level.