Effect of Electroplating Current Density on Tensile Properties of Nanotwinned Copper Foils

In this study, nanotwinned copper (nt-Cu) foils were fabricated using a rotary electroplating system. Their microstructures (orientation, grain size, and twin spacing) and correlated tensile properties were substantially tuned by manipulating the electroplating current density. The nt-Cu foils were further heat-treated at 150 °C for 1 h and tensile-tested to characterize their thermal stability. We found that the mechanical properties of the nt-Cu foils are directly associated with the electroplating current density. The ultimate tensile strength (UTS) increases with increasing in the current density, reaching the maximum values at 25 ASD. The great enhancement can be attributed to the decrease in twin spacing and grain size. We also discovered that the UTS and ductility remain approximately intact under a high temperature, indicating the excellent thermal stability of such nt-Cu foils.