Copper greater strength than monocrystalline forms. The softness of copper partly explains its high electrical conductivity (59.6×10 S/m) and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature. This is because the resistivity to electron transport in metals at room temperature originates primarily from scattering of electrons on thermal vibrations of the lattice, which are relatively weak in a soft metal. The maximum permissible current density of copper in open air is approximately 3.1×10 A/m of cross-sectional area, above which it begins to heat excessively. Copper is one of a few metallic elements with a
Thermal conductivity measurement a heater or temperature sensor element. By having strong thermal insulation surrounding the diode, heat escapes only through an exposed cooling tab, which is used as the probe for the thermal interface material measurements. This method shares similarities with the ASTM D5470 standard, such as the measurement of the thermal resistance at different material thickness levels. The system is designed to measure high thermal conductivity thermal interface materials. Its applicability for the measurement of insulators is more limited. A thermal conductance tester, one of the instruments of gemology, determines if gems are genuine diamonds using diamond's uniquely high thermal conductivity.