Metal film resistors are axial resistors with a thin metal film as resistive element. The thin film is deposited on usually a ceramic body. The appearance of metal film resistors is similar to carbon film resistors, but their properties for stability, accuracy and reliability are considerably better. Metal film resistors are amongst the most common types of axial resistors.



For a good reliability, metal film resistors are normally operated between 20 and 80 percent of their specified power rating.  Reliability is generally increased by derating 50%. However, in very specific situations, at lower than 20% of the power rating in a humid environment the reliability decreases. Compared to wirewound or carbon composition resistors, these resistors are easier damaged by voltage surges and power overloads.

 
Metal film resistors have good characteristics for stability, tolerance and TCR. Furthermore, the resistors feature low noise properties and a high linearity because of a low voltage coefficient. Therefore, in circuits where tight tolerance, low temperature coefficient and low noise properties are important, often metal film resistors are used. Examples of applications are active filters or bridge circuits.