Numerical Optimization of Electrodeposition Thickness Uniformity with Respect to the Layout of Anode and Cathode

Abstract

Electrodeposition has been widely used in many fields due to its unique advantages, especially in the mold manufacturing of transfer printing by roll-to-roll. Electrodeposition thickness uniformity becomes prominent when surface areas to be electrodeposited are large and have strict geometrical accuracy requirements as well. For achieving uniformity of deposition thickness, the available methods range from adjusting anode-cathode spacing, the surface areas of anode and cathode, and partially shielded cathode. The three methods have been proved to be easy to implement and effective in practice. However, determining the optimized layouts of anode and cathode poses a challenge. This paper illustrates how to optimize the layout for thickness uniformity for solving a real electrodeposition problem encountered in electroplating nickel on a large copper mold with its length and width of 600 mm\u2009×\u2009600 mm. Combined application of the three methods to optimize the deposition thickness uniformity can achieve better results than the single method. The results of simulation and electrodeposition tests show that the ratio of sideline thickness to central line thickness decreased from 1.16 to less than about 1.05. The optimization was performed through solving mathematical equations of electric charge transport plus boundary conditions. This paper also explains the influences of the layout of anode and cathode on deposition thickness uniformity from the perspective of electric current distribution and electric field distribution, which would help designers of electrodeposition processes develop an intuitive feeling about the interplay among the layout parameters.