Samsung Electro-Mechanics High Voltage MLCC for EV Powertrain

How is the structure of high voltage MLCC different from that of general MLCC?

MLCC applied for high voltage applications are exposed to the risk of Arc-over and a short-circuit can occur inside of the MLCC. Under high voltage, a strong electric field is formed around the MLCC, which ionizes the surrounding air.  Particularly, a strong electric field is concentrated on both terminals of the MLCC. If it exceeds the inception voltage of the ionized air, electrical arcs occur, ultimately leading to a short-circuit inside the MLCC. The structure that prevents this phenomenon is a shield pattern inside MLCC.

Floating design is a design that lowers the short-circuit risk when MLCC crack occurs, but it is also useful for high-voltage products. The floating structure distributes voltage so the voltage inside the MLCC is only half of the voltage applied to the end terminals. For example, when 1000V is applied to both ends of the MLCC, if the floating design is used only 500V is applied to the MLCC dielectric layer, which is half of 1000V. It’s definitely an advantage from the perspective of reliability because the electric field applied between dielectric layers decreases. Voltage along with temperature are key factors to determine MLCC lifetime.