Electrical Conductivity

close-up of lead frame Photo Courtesy of IBM

When used for connectors or other electrical applications, the inherently high electrical conductivity of copper and copper alloys is very important. The conductivity of copper is expressed in units of a percentage of IACS (International Annealed Copper Standard). This standard is based on an annealed copper wire having a density of 8.89 g/cm3, 1 meter long, weighing 1 gram, with a resistance of 0.15328 ohms. This standard was assigned the value 100 at 200°C (392°F). The higher the %IACS, the more conductive the material is. It is not uncommon for commercially pure copper products to have IACS conductivity values greater than 100 because of improved processing techniques which have been developed since the adoption of the standard in 1913. Both temperature and alloying elements have an effect on conductivity and this property must be balanced against the need for strength, corrosion resistance and formability.