ceramicdisc

Ceramic disc capacitors, commonly called ceramic discs, are fixed-value capacitors that use a ceramic dielectric material and a pair of conductive electrodes on opposite faces of a disk-shaped ceramic substrate. The plates are typically silvered on the opposite faces to form the active terminals, and the assembly is finished with protective coating and radial or surface-mount terminations.

The dielectric material governs key characteristics. Class 1 dielectrics, such as NP0/C0G, offer exceptional stability and low losses, with minimal capacitance change over temperature and voltage. Class 2 dielectrics, including X7R, Z5U, and Y5V, provide larger capacitance in a small package but exhibit greater temperature and voltage dependence and aging effects.

Disc capacitors are manufactured in various sizes to support voltages from a few volts to several kilovolts. Common tolerance ranges are narrower for Class 1 parts (often a few percent) and wider for Class 2 parts (often 10–20% or more). Temperature coefficients, voltage coefficients, and aging must be considered when selecting a part for a given circuit.

Applications include decoupling and high-frequency filtering, timing and frequency-selective networks, and general purpose coupling in consumer electronics, automotive, and industrial equipment. They are favored for low cost and compact form factors but may be bulky for high capacitance values compared with multilayer ceramic capacitors or film capacitors.

Reliability concerns include microcracking from mechanical stress and moisture, which can alter capacitance or cause failure under high voltage. SMD disc variants exist but are less common than leaded radial types in many modern designs.