Copper in the trace impurities on the copper conductivity, thermal conductivity has a serious impact. Among them, titanium, phosphorus, iron, silicon, etc. significantly reduce the conductivity, while cadmium, zinc, etc. has little effect. Oxygen, sulfur, selenium, tellurium and other solid solubility in copper is very small, can be generated with the copper brittle compounds, the conductivity of the impact is not significant, but can reduce the processing plasticity.
Ordinary copper in a reducing atmosphere containing hydrogen or carbon monoxide when heated, hydrogen or carbon monoxide and easy to grain boundaries of cuprous oxide (Cu2O), resulting in high-pressure water vapor or carbon dioxide gas, can make the copper rupture. This phenomenon is often called copper “hydrogen disease”.
Oxygen is harmful to the solderability of copper. Bismuth or lead and copper to generate a low melting point eutectic, so that the copper produces hot brittle; and brittle bismuth is a thin film distributed in the grain boundaries, but also make the copper produce cold brittle.
Phosphorus can significantly reduce the electrical conductivity of copper, but can improve the liquidity of copper, improve solderability. Moderate amounts of lead, tellurium, sulfur, etc. can improve the machinability. Copper annealed sheet room temperature tensile strength of 22 ~ 25 kg force / mm 2, elongation of 45 ~ 50%, Brinell hardness (HB) of 35 ~ 45.
