What is the Difference Between Metal Film and Carbon Film Resistors?

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The main differences between metal film and carbon film resistors are their composition, noise, temperature and voltage coefficients, precision, and size. Here is a comparison of the two types of resistors:

  1. Composition: Carbon film resistors use carbon, while metal film resistors use a metal oxide film to reduce current flow.
  2. Noise: Metal oxide film resistors have a low noise design, keeping the minimum current and ensuring less noise compared to carbon film resistors.
  3. Temperature and Voltage Coefficients: Metal oxide film resistors have better voltage and temperature coefficients than carbon film resistors, making them more stable and less sensitive to changes in temperature and voltage.
  4. Precision: Metal film resistors typically have a precision of 1%, compared to 5% for carbon film resistors.
  5. Size: Metal oxide film resistors are generally smaller in size compared to carbon film resistors, making them a more suitable choice for compact circuits.

In summary, metal film resistors are generally considered superior to carbon film resistors due to their lower noise, better stability, higher precision, and smaller size. However, the choice between the two types of resistors depends on the specific requirements of your application.

Comparative Table: Metal Film vs Carbon Film Resistors

Here is a table comparing the differences between metal film and carbon film resistors:

Feature Carbon Film Resistors Metal Film Resistors
Definition Resistors that use a thin carbon film to limit the electric current flow. Resistors that use a thin metal film to limit the electric current flow.
Resistance Range 1 ohmm to 25 megaohms, with a power rating ranging between one-quarter and one watt. Typically available with tolerances of 2%, 1%, 0.5%, 0.25%, and 0.1%.
Material Carbon film on a ceramic substrate. Metal film ( nichrome or tantalum) on a ceramic substrate.
Tolerance Generally higher, around ±10%, ±5%, or ±2%. Generally lower, around ±2%.
Temperature Coefficient Negative temperature coefficient characteristic. Usually has a small positive temperature coefficient.
Noise Higher noise compared to metal film resistors. Lower noise compared to carbon film resistors.
High Voltage and High Temperature Applications More suitable for high voltage and high temperature applications. Less suitable for high voltage and high temperature applications.
Cost More expensive to produce than thin film resistors. Cheaper than carbon film resistors.
Size Larger in size compared to metal oxide film resistors. Smaller in size compared to carbon film resistors.

Carbon film resistors are made by depositing carbon film on a ceramic substrate, while metal film resistors are made by depositing a thin layer of nichrome or tantalum on a ceramic substrate. Carbon film resistors have a higher tolerance and are more suitable for high voltage and high temperature applications, but they produce more noise compared to metal film resistors. On the other hand, metal film resistors have lower tolerance, lower noise, and are cheaper than carbon film resistors, making them more commonly used in various applications.