Carbon film resistors are a type of fixed form resistors that use a carbon film to limit the flow of current. Their construction includes a thin carbon film that acts as the resistive element which is housed on a ceramic substrate. Read More
Carbon film resistors are a big improvement when compared to carbon composition resistors as they are smaller and provide better performance. However, metal oxide and metal film resistors have taken over from carbon film resistors in recent times.
The ceramic substrate is a very good insulator of electricity and heat, thus allowing the resistors to withstand high temperatures and high voltage without any damage. Operating temperatures are up to 15kV with a nominal temperature of 350°C.
Carbon film resistors are manufactured by depositing crystalline form of carbon on the ceramic substrate at high temperature and pressure conditions. Then they are epoxy coated for protection. Metallic end caps are fitted at both ends and attached to copper leads.
To enable the carbon film resistor to have the correct resistance, a helical cut is normally made into the film. The resistance offered is proportional to the thickness of the carbon film layer and width of helical carbon film cut.
Carbon film resistors offer key advantages such as low noise, low cost and a wide operating range. However, they also have a major disadvantage. They have high negative temperature coefficient of resistance, which means the resistance value decreases rapidly with increase in temperature.
Key applications areas are:
KWK makes color coded carbon film resistors with axial style mounting. The KWK miniature series of Carbon Film resistors are ideal for compact installations. The resistors work in the power range of 1/6W to 5W and the resistance range of R10 to 10M.Read Less
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