Preparation of Nano twin copper foil with high elongation and excellent suppression self-annealing via pulse superposition direct current method

Abstract

Pulse electroplated copper has recently received a great deal of attention from the copper foil and microelectronics industries, as its remarkable microstructure is closely linked to several key properties, including the availability of metallic materials with reduced porosity, fine deposited grains and low electrical resistance. The effects of pulse superimposed direct current (DC) on the microstructure and properties of copper foils were investigated by taking advantage of the high deposition rate of pulse current and the long-term stability and easy control of DC current. Further, tests such as scanning electron microscopy (SEM) and confocal laser microscopy (CLM) were used to characterize the surface micromorphology of the copper foils, and the influence of the self-annealing effect at ambient temperature was explored using electron backscattering diffraction (EBSD). The results show that pulsed superimposed DC can obtain copper foils with a small profile and high tensile strength with a Sz of only 0.670 μm, σust 538.67 MPa and an elongation of 4.90%. Further, the specific additive MESS effectively suppresses the mechanical property degradation caused by self-annealing of copper foils, with a tensile strength reduction of only 0.39%.