Electrodeposited copper foil was prepared by direct current electrodeposited method

and effects of different RE additions

including 0

0.0015%

0.003% and 0.0045%

on microstructure and properties of the copper foil were investigated by SEM （scanning electron microscope）

micro-computer control electronic universal testing machine and high temperature tensile machine.The results show that RE element can obviously improve mechanical properties of the copper foil by refining and uniformly distributing grain size in the foil

where ideal grain size in the copper foil with maximum value of mechanical properties can be obtained with approximately 0.003% RE addition.