Electrochemical Formation of Free-Standing 3D Structures Using Injection of Additives

A new method of electrochemical formation of free-standing 3D structures based on the injection of additives that controls the deposition rate was demonstrated using copper-chloride-polyethylene glycol as an example. A densely-packed defect-free pillar was formed upon the injection of chloride-free electrolyte into a chloride-containing electrolyte, where copper deposition was fully suppressed. The effects of diffusion coefficient, injection rate and the distance between injection nozzle and pillar top were evaluated with numerical simulation. A fast diffusion species, a moderate injection rate and a small gap between injection and pillar were found beneficial to obtaining the best contrast in the growth rates between pillar and background. The demonstration of free-standing copper structure in this paper provides an alternative path for electrochemical 3D printing of various metallic materials. (C) The Author(s) 2017. Published by ECS. All rights reserved.