One important marking for polarised capacitors is the polarity. These codes are typically used for ceramic and other film type capacitors. These capacitor codes are standardised by EIA, but also some other generally used industry codes may also be seen in common use. It is often necessary to mark a capacitor with a marking or code that indicates the temperature coefficient of the capacitor. There are a number of basic marking systems that are used and different capacitor types and different manufacturers use these as needed and best fits the particular product. Capacitors are marked in many different ways. Some of the marking systems have been standardised by the EIA - the Electronic Industry Alliance, and these provide commonality across the industry. Size also plays a major part in determining how the capacitor is marked - small components must use abbreviated coding systems, whereas larger capacitors such as aluminium electrolytic varieties may write the relevant parameters on the case in full. The capacitor marking codes vary in their format according to whether the component is a surface mount device or whether it is leaded device, as well as the capacitor dielectric. These capacitor colour codes are less common than in previous years, but some may still be seen. Today most capacitors are marked with alphanumeric codes but older capacitors may be seen that have colour codes. These markings and codes indicate various properties for the capacitors and it is essential to understand them in order to select the required type.

How to read ceramic capacitor values