What is a Cermet Resistor?
A cermet resistor is a type of resistor that is made by depositing a conductive paste of ceramic and metal onto an ceramic substrate. They get their name from the ceramic ‘cer’ and metal ‘met’ in their composition.
Cermet resistors are a type of film resistor, similar to metal, carbon, or metal oxide film resistors. They have excellent properties including tight tolerances and low noise. Cermet resistors are available in a wide range of resistances, including very high resistance values that are difficult to achieve with other methods of resistor construction.
A cermet resistor is designed to combine the best properties of both ceramic and metal film resistors. Ceramics have attributes like hardness and high temperature resistance. Metals have the ability to undergo plastic deformation, meaning that their internal structure is damaged less with the stresses that come from repeated use, including stress from thermal expansion or contraction.
Types of Cermet Resistors
Cermet resistors can be made as either a thick film or thin film. The difference is the width of the resistive path. A thin film cermet resistor has a resistive path that is only a few micrometers wide, while a thick film cermet resistor’s path is about 20 micrometers wide.
Advantages of Cermet Resistors
Cermet resistors have many advantages. They can be produced with very tight tolerances of less than 1%. They have low noise, are stable at higher temperatures, and have a low thermal coefficient of resistance.
- Tight / high tolerance (< 1%)
- Low noise
- Stable at high temperatures
- Very high resistances available
- Low temperature coefficient of resistance (TCR)
- Highly linear response
- Compact size
Cermet Resistor Applications
Cermet resistors excel in applications where tight tolerance, low noise, and high precision are required. Since they can be made with very high resistance values, cermet resistors are perfect in applications requiring both high resistance (up to teraohm values) and tight tolerance.
Cermet resistors are available in small surface mount packages (SMD) as well as through-hole, making them suitable for many PCB applications.