Mechanical and structural properties of electrodeposited copper and their relation with the electrodeposition parameters

Thin copper-electrodeposited films have been prepared on steel substrates from an additive-free copper sulfate bath by applying different current signals such as rectangular and square wave pulses, triangular waveform and also by direct current with variation of its magnitude. Mechanical properties of these films have been studied by means of dynamic microindentation measurements known as the universal microhardness test. Values of the hardness, plastic component, Young's modulus and percent of elastic recovery have been measured. In order to obtain the preferential orientation and grain size of the electrodeposits, X-ray diffraction studies have been made as well as scanning electron microscopy to evaluate their morphology. All the deposits showed a preferential orientation but without a simple correlation with the mechanical features of the films. The influence of current density on microhardness through its effect on grain size has been found to obey the Hall-Petch relationship in the nanometer range. Finally, correlations between the mechanical properties of the electrodeposits and the electrodeposition parameters have been made. These kinds of studies raise the possibility of tailoring films with good mechanical performance for different technological applications just by selecting the appropriate electrodeposition conditions. (C) 2004 Elsevier B.V All rights reserved.