MLCC Selection Guide: Dielectric, Voltage Derating and DC Bias

Multilayer ceramic capacitors look interchangeable on a BOM and behave very differently in a circuit. Three parameters decide whether the design works in production or only on the bench.

Dielectric class. C0G/NP0 is stable across temperature and voltage — use it for timing, filters and oscillators. X7R holds ±15% over −55 to +125 °C and suits decoupling. Y5V and Z5U lose most of their capacitance at temperature extremes and should never be used where the value matters.

DC bias. A 10 µF X5R 0603 part can lose 60–80% of its capacitance at rated voltage. The datasheet curve is the only reliable source. If the design needs 10 µF at 12 V, specify a larger case size or a higher voltage rating rather than trusting the headline value.

Voltage derating. For industrial and automotive use, derate to 50% of rated voltage for X7R and 80% for C0G. This reduces crack risk from board flex and improves long-term reliability.

Placement and flex. Ceramic capacitors crack when the board bends. Keep them away from break-off edges, use soft-termination parts on large case sizes, and avoid 1206 or larger in high-flex areas.

Sourcing note. The same part number from different manufacturers is not always the same part. Specify the dielectric and the case size explicitly, and ask for the manufacturer's series name, not just the generic value.