High Reliability Thin Layer BME X7R Dielectric with Only Few Core-Shell Grains

Typically, in the microstructure of X7R dielectrics, a certain amount of grains with core-shell structure are required to achieve acceptable temperature dependence of capacitance. However, as the thickness of the dielectric layers is reduced, it is increasingly difficult to maintain the core-shell structure in the thin dielectric layers while still achieving both, high capacitance and good reliability. A high reliability X7R dielectric material consisting of only a few core-shell structured grains was developed suitable for application in dielectric layers of about 3 mum thickness. Transmission electronic microscopy (TEM), impedance spectroscopy, and differential scanning calorimetry (DSC) were used to characterize the base metal electrode (BME) multilayer ceramic capacitors (MLCC) prepared from this dielectric material. The reliability was tested by highly accelerated life test (HALT) and compared with commercially available X7R parts consisting of predominantly core-shell structured grains.