Improvement of performance stability of electrolytic copper foils by bi-component additives

Surface roughness and mechanical strength are significant properties of copper foils for printed circuit boards. Stable performance is highly required for the copper foils across the whole roll (length of ~ 7000 m) in industrial manufacture. In this work, the main attention is focused on the performance stability of the obtained 18-μm copper foils by different additives. The available concentration range of saccharin sodium was expanded and the performance stability of copper foils was improved by the co-addition of hydroxyethyl cellulose or bis-(3-sulfopropyl)-disulfide. The copper foils prepared under the condition of bi-component additives remained low roughness and high tensile strength, due to the uniform surface microtopography related to the continuous high relative intensity of (220) crystal face varying with additive concentration. It is found that the change of the electrochemical reaction caused by the variation of the saccharin sodium concentration was weakened by the different adsorption behaviors of those introduced additives. The bi-component additives expanded the concentration of each additive and the stability of the copper foil products was improved as a result. It is advantageous to industrial applications for higher production efficiency, higher product quality, and lower production cost, brought by bi-component additives. Graphical abstract