Low Temperature Metal Additive Manufacturing with the Electrochemical Process
Authors: Kang Donghwa , Kim Sungbin , Ko Kunwoong , Kim Youngkuk , Yoo Bongyoung 
Published: December 2020

Additive manufacturing(AM) is a manufacturing technique that produces three-dimensional objects by sequentially stacking layer of material. Due to freedom of design, it is used in various industrial applications. There are many materials capable to use in AM. Among them, polymer-based AM is the most widely used, because the polymer is easy to sinter at low temperature. However, interests in metal-based AM have been increasing due to its advantages such as mechanical strength, electric conductivity and heat dissipation. Thus, many studies of metal-based AM method have been conducted. The most commonly methods for metal AM are selective laser melting(SLM), electron beam melting(EBM), direct metal deposition(DMD), and selective laser sintering(SLS). However, these methods need a high-temperature heat source to melt material. As a result, introducing the structural anisotropy and unfavorable microstructures are inevitable. Also, local defects caused by incomplete sintering, substrate delamination, and distortion are significant problems that degrades the quality of final products[1].
On the other hand, a new type of low-temperature electrochemical-based AM method has been developed. Localized electrochemical deposition(LECD) is a method utilizing electrochemical deposition on the specific area in the electrolyte. The electrochemical deposition has many advantages over other techniques because it is simple, damage-free from high temperature, and cost-effective . In LECD, instead of using conventional anode, wire type anode is used. This wire type anode with small area will produce strongly localized reduction reactions in the electrolyte. In this method, only the end of the tip of wire anode is involved in the electrochemical reaction. Theoretically, this technique can move micro anodes to produce flexible geometry features with a high aspect ratio. So far, the LECD has been used to fabricate a copper pillar, and not much research has been conducted on various structures[2-3]. Therefore, it is necessary to study the fabrication of other structures.
In this research, we fabricated copper and nickel 3D structures through Electrochemical Additive Manufacturing (ECAM). We studied that morphologies of a deposited metal wall shape structures which could be obtained by controlling the applied current, temperature, and distance between cathode and anode. Additionally, the effect of organic additives on metal structure profiles was investigated. Additionally, nine(3x3) copper pin array was fabricated on the polymeric substrate, which cannot be manufactured by high-temperature laser-based metal 3D printing. Also, we confirmed that its bendability was well maintained. The micro anode used in this study was made of a Platinum wire of 100μm. This platinum wire was insulated by a capillary glass tube, then filled with epoxy resin. The surface of the anode was polished using sandpaper. The cathode was a copper wafer (1cm × 1cm × 1μm). The cathode was placed horizontally in the electrolytic cell, while anode was arranged perpendicular to the cathode. The entire experimental process was controlled by micropositioner and appropriate computer software. The changes in voltage and current during the process were monitored. The surface and microstructure were characterized by scanning electron microscopy (SEM) and optical microscope (OM).

Reference

[1] Y.K. Kim, D.H Kang, H.R. Kim, S.B. Kim and B.Y Yoo, “The Characteristics of Selective 3D Metal Additive Process Using Electrochemical Deposition and Nozzle Fluid Dynamics”, Frontiers in Mechanical Engineering, 6 (2020).
[2] E. M. El-Giar, R. A. Said, G. E. Bridges and D. J. Thomson, “Localized Electrochemical Deposition of Copper Microstructures”, Journal of The Electrochemical Society, 147 (2000).
[3] S.k. Seol, A. R. Pyun, Y. Hwu, G. Margaritondo and J.h. Je, “Localized Electrochemical Deposition of Copper Monitored Using Real-Time X-ray Microradiography”, Advanced Functional Materials, 15, 934 (2005).