What Is a Metal Film Resistor?
A metal film resistor is a precise and stable resistor made by coating a ceramic body with a thin metal alloy film. It's the standard choice for measurement and precision analog circuits.
Difference From Carbon Film
| Property | Carbon film | Metal film |
|---|---|---|
| Tolerance | ±5% | ±1% (or better) |
| Noise | High | Low |
| Stability | Medium | High |
Advantages
Thanks to tight tolerance, a low temperature coefficient and low noise, its value changes very little with time and temperature; it gives repeatable results.
Where Is It Used?
Precision voltage dividers, measurement instruments, reference circuits and analog stages that need low noise.
Temperature Coefficient (TCR)
A metal film resistor's strongest point is its low temperature coefficient (TCR, ppm/°C): its value drifts very little even when the temperature changes. This is the key to getting consistent, temperature-independent results in precision measurement and reference circuits.
Common Mistakes
- Using it where it isn't needed: where carbon film would do, metal film raises the cost.
- Exceeding the power limit: trusting its precision while ignoring the wattage ruins the value.
- Assuming the wrong tolerance: not every metal film is ±1%; check the label.
Frequently Asked Questions
Why is metal film more expensive?+
Is the color code different?+
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