Low temperature heating - Import export

Constantan® is a copper-nickel alloy that contains specific minor amounts of additional elements to achieve precise values for the temperature coefficient of resistivity. Careful control of melting and conversion practices results in a very low level of pinholes at ultra-thin thicknesses. The alloy is used extensively for foil resistors and strain gauges. The TCR can be adjusted from the furnished cold rolled values by using a low temperature heat treatment to achieve compensation for all types of spring elements. The foil is normally supplied with 90% cold reduction and a smooth bright surface. The foil is reasonably flat at 4” wide and nearly free of pinholes. The cold rolled foil can be produced with a TCR between +10 to –35 PPM/°C. The heat treatment will shift the foil TCR to the desired value. A typical heat-treat curve for Constantan® shows decreasing resistivity but increasing TCR with increased heat-treating temperature.