Low Temperature Sintering Temperature Stable Barium Titanate Dielectric Material

Lately, in accordance with increasing demands for high-performance electronic equipment, multilayer ceramic capacitors (MLCC) have encountered marketplace demand for smaller size, higher capacitance, lower cost, and higher reliability.It is desired that the temperature characteristics be as smooth as possible even under harsh conditions, such as the modules of engine electronic controlunit (ECU) and anti-lock brake system (ABS), which are subjected to high temperature approximately150℃in some case. Subsequently, MLCCs which meet the electronics industry association (EIA) X8R standard (△C/C25℃(-55℃～150℃)≤±15%) have been widely researched and developed. Barium titanate is a very important material of MLCC on account of its high temperature-stability and high dielectric constant properties. Therefore, BaTiO3-based dielectric material with high temperature-stability sintering at low-temperature is under wildly investigating.This study is based on the summary of the latest research both domestic and international. A new BaTiO3-based system free of lead and cadmium was chosen to be investigated. BaTiO3ceramics was prepared by conventional mixed-oxide method, and a few compounds have been doped into the system to obtain the X8R materials.The influence of CeO2and Bi2O3dopants upon dielectric properties of BaTiO3system was investigated. The CeO2additives is effective on improvement of the temperature characteristics.With the doping of Bi2O3, the BaTiO3system was able to be sintered under a lower temperature. AgO has the effect of decrease the sintering temperature and improve the sintered density and dielectric constant of the system. The addition of silver could not influence the temperature characteristics directly and did not affect the dielectric loss obviously. Synthetically considering, experimental best value of AgO is about0.4wt%. Meanwhile, the addition of MnCO3and CuO improved the dielectric properties of the BaTiO3system effectively.The uniform design was introduced to arrange the experiment. In this way, we have prepared BaTiO3-based X8R ceramics sintered at low temperature at last. Its main parameters were as follows:sintering temperature950℃, ε≥1700, tanδ≤1%,-15%＜ △C/C25℃<15%in the region of-55～150℃; sintering temperature970℃, ε≥1900, tanδ≤1%,-15%<△C/C25℃<15%in the region of-55～150℃.Finally, the dielectric properties between laboratory sample and factory MLCC products were compared, a inspection reports was given to show that the properties of the ceramic powders was developed to meet the X8R standard and actual needs.