Temperature Coefficients of Resistance Materials
Comprehensive table of temperature coefficients for various materials used in electrical engineering
About Temperature Coefficients
Definition
The temperature coefficient (α) describes the change in resistance value when temperature changes relative to a reference temperature of 20°C.
Formula
Material Behavior
Practical Note
For copper and aluminum conductors, a rule of thumb is 0.4% per °C in the range 0°C to 50°C.
Temperature Coefficient Values at 20°C
| Material | Temperature Coefficient α (1/K) | Type |
|---|---|---|
| Pure Metals | ||
| Aluminum (99.5%) | +0.004 | PTC |
| Lead | +0.0042 | PTC |
| Iron (pure) | +0.00657 | PTC |
| Gold | +0.0037 | PTC |
| Copper (99.9%) | +0.00393 | PTC |
| Nickel | +0.006 | PTC |
| Platinum | +0.00392 | PTC |
| Mercury | +0.0009 | PTC |
| Silver | +0.0038 | PTC |
| Tantalum | +0.0033 | PTC |
| Tungsten | +0.0044 | PTC |
| Alloys | ||
| Aldrey (AlMgSi) | +0.0036 | PTC |
| Beryllium Bronze (SnBe4Pb) | +0.0005 | PTC |
| Manganin (Cu84Ni4Mn12) | ±0.00004 | Stable |
| Constantan (CuNi44) | ±0.00001 | Stable |
| Isaohm | ±0.000003 | Stable |
| Brass (CuZn37) | +0.0016 | PTC |
| Soft Iron (4% Si) | +0.0009 | PTC |
| Steel C15 | +0.0057 | PTC |
| Non-metals & Semiconductors | ||
| Carbon | -0.0005 | NTC |
| Graphite | -0.0002 | NTC |
| Arc Carbon | +0.0005 | PTC |
| Germanium | -0.048 | NTC |
| Silicon | -0.075 | NTC |
Additional Information
Practical Applications
- Copper & Aluminum: Power transmission lines
- Platinum: Pt100/Pt1000 temperature sensors
- Manganin/Constantan: Precision resistors
- Germanium/Silicon: NTC thermistors
Resistor Classifications
Standard Resistors
Commercial small-power resistors typically have temperature coefficients in the range of 0.0001 to 0.0002 (100ppm to 200ppm) per °C.
Precision Resistors
Precision resistors are in the range of 0.00005 (50ppm) per °C. Designated as TK50, TK100, etc. (Temperature Coefficient in ppm/°C).
Important Notes
Validity Range
- Linear coefficient valid for ΔT ≤ 200K
- Values may vary with material purity
- Reference temperature: 20°C
Design Considerations
- Use temperature-stable alloys for precision
- Consider thermal compensation circuits
- Account for self-heating in high-power applications
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Battery Capacity • Capacitor Capacitance • Decibel, votage, power converter • Decibel - factor converter • Electric Power • Electric Energy • Electric Charge • Electrostatic force, Coulombs Law • Internal resistance of a power source • Ohm's law and power • Table of temperature coefficients • Temperature drift of resistance • Voltage drop • Wire resistance •