Ceramic Capacitors

Ceramic capacitors offer a broad range of size vs. performance tradeoffs and are easily the most popular in numbers sold.  Ceramic capacitors are available from < 1 pF to 1000s of uF.

Pros: The main virtue of Ceramic capacitors are their relatively high dielectric constants.   This can vary from C0G with a K of up to 60, which has excellent electrical properties but is relatively large and expensive, to ceramics with Ks in the tens of thousands but with very poor electrical properties.  Large- value ceramics can replace electrolytic capacitors in high-frequency applications like switch-mode power supplies because of their lower ESR.  Ceramic capacitors are especially suitable for surface mounting due to their heat resistance, mechanical integrity, and the ability to make them in very small packages at low cost, for portable equipment.  This has greatly added to their usage.  To some extent ceramics are slowly displacing other types of capacitors. 

Cons: Low breakdown voltage means that the low-K ceramics (Class 1), the ones with the good electrical properties, have poor volumetric efficiency, and are usually found only in small values.  High-K ceramics (Class 2 and higher) have poor electrical properties, which are highly dependent on temperature, voltage, and frequency, plus a significant aging rate.  Unlike many other capacitors, ceramics have no self-healing mechanism.  This means that manufacturers must maintain a high level of quality control over the dielectric.  Ceramics are most cost affective in small sizes at present.  Very large ceramics are a bit of a challenge, especially in SMD. 

Tags: Ceramic Capacitors