Effect of Cryogenic Treatment on Extruded Copper Structures

To improve the quality of electroplated copper anodes and reduce the amount of anode mud, it is necessary to further refine copper grains. In the electronics industry, this is typically accomplished by either extrusion or cryogenic treatment. In this study, samples were subjected to different cryogenic treatment periods, and SEM, EDS, XRD, and hardness tests were performed. It was confirmed that a sub-grain boundary was formed due to the disappearance of vacancies and an increase in dislocations after the cryogenic treatment of extruded copper, which improved the grain refinement and hardness. At longer treatment times, the combination and entanglement of dislocations reduced the strengthening effect, and the copper diffraction peaks changed. However, the distribution of trace phosphorus did not change with the grain refinement distribution. Therefore, the results confirm that cryogenic treatment can be used to refine the grains of extruded copper.