Capacitor Dielectrics

The dielectric matters more than the capacitance value. Class 2 ceramics (X7R, Y5V) lose a large fraction of their rated capacitance under DC bias and with temperature — never use them where the value must be accurate.

Dielectric	Class	Temp range	Tolerance / drift	Use
C0G / NP0	Class 1	−55 … +125 °C	±30 ppm/°C	Very stable, no DC bias loss — timing, filters, oscillators
X7R	Class 2	−55 … +125 °C	±15%	General decoupling; loses capacitance under DC bias
X5R	Class 2	−55 … +85 °C	±15%	Bulk decoupling in small packages
Y5V	Class 2	−30 … +85 °C	+22 / −82%	Avoid for anything accurate — huge drift
Electrolytic	Polarised	−40 … +105 °C	±20%	Bulk energy storage; ESR matters; has a lifetime
Film	—	−40 … +105 °C	±5%	High voltage/current, snubbers, audio
Tantalum	Polarised	−55 … +125 °C	±10%	Stable, compact; fails short — derate voltage 2×

Standard values

Ceramics follow the E-series: 1.0, 1.5, 2.2, 3.3, 4.7, 6.8 × 10ⁿ (pF → µF). Common decoupling: 100 nF at every IC pin plus 1–10 µF bulk per rail.

See the E-series values for the full preferred-number set.

Print / save PDF