JIS C2522-1999 describes this as "Copper Manganese Wire, Bar, and Plate for Electric Resistance". This widely used material is known as precision resistance wire CMW, "Manganin".
In order improve electromotive force against copper, resistance temperature coefficient, and corrosion resistance, we have developed a CMW Manganin alloy for use as precision resistance wire with additions of Ni and other elements to Cu-Mn alloy.

1. α₂₃, the resistance temperature coefficient at 23 ˚C, is small, - 5 ~ + 10 X 10^-6/K, as demanded of precision resistance wire.
2. Electromotive force against copper is also small, 2 μV/K.
3. The stability of resistance over a period of years has proven to be excellent.
4. Due to the above features, this material is used for standard resistance resistors.

Temperature and resistance features of Manganin Wire, CMW

As the temperature dependence of resistance of Manganin wire is not linear, we describe it with a parabolic temperature/resistance curve within the temperature range of actual use, 5 ~ 45 ˚C, expressed by the following quadratic equation.

Resistance - temperature graph            Graph 2

We apply heat treatment at the maximum resistance temperature in the above quadratic equation (temperature where resistance temperature coefficient α is 0) approach room temperature.
To use this material as precision resistance wire, it is critical that the surrounding temperature or temperature caused by self-heating be kept within the suitable usage range, from 5 to 45 ˚C.