DC Electric Field-Induced Aging Effects of Electrical Characteristics on X7R Multilayer Ceramic Capacitors for Switching Mode Power Supplies

Power circuits such as switching mode power supplies use various passive parts. One of the passive components, multilayer ceramic capacitors (MLCCs) are used for coupling, decoupling, smoothing, and filtering. The MLCCs have various operating temperature ranges and, currently, the X7R MLCCs are widely used in power electronics. However, DC-bias aging of the MLCCs needs to be investigated because the MLCCs that experienced DC bias in the circuits show changes in capacitance and other electrical parameters. In this paper, we fabricated X7R 25 V 22 mu F MLCCs and studied the aging effects caused by a DC electric field (Estress). The changes in the capacitance are -29.6, -27.2, -25.7, -25.0, and -23.4% due to DC stress with the Estress of 43.2, 36.0, 22.5, 20.0, and 17.5 V/mu m, respectively. The reduction in the capacitance due to the 90 degrees domain switching in MLCCs remains active even when Estress is as high as 43.2 V/mu m. The ESR increased after DC stress, whereas the dielectric loss decreased. After DC stress was applied to the MLCCs, the decrease in the dissipation factor was mainly determined by decreasing in capacitance.