Mass transfer enhancement through trapezoidal anode in dynamic mask electrodeposition of metal micropillar

In the conventional mask electrodeposition process, the planar nature of the anode leads to a rapid flow of a large amount of deposition solution over the confined microzone, resulting in difficulties in mass transfer within the microzone and poor quality of microstructure formation. To fabricate high-quality metal microstructures, this study proposes a dynamic electrodeposition method that utilizes a trapezoidal anode to enhance the mass transfer capability within the confined microzone, based on the concept of moving masks. Under the influence of the trapezoidal anode, there is a sudden change in the velocity of the deposition solution above the confined microzone, inducing turbulence within the microzone and enhancing internal mass transfer capability. Both simulation and experimental results validate the feasibility of this method. With the trapezoidal anode, the flatness of the cross-sectional profile of the metal microstructure is improved by 45.2%, and the deposition rate is increased by 44%. Subsequently, process parameters were optimized through orthogonal experiments. Utilizing the optimized parameters, high-quality metal microstructures with a diameter of 200 μm and a height of 360 μm were dynamically deposited. These results demonstrate that the use of a trapezoidal anode to enhance mass transfer within the microzone effectively improves the deposition quality and rate of metal microstructures, providing a practical solution to the difficulties associated with mass transfer in confined microzones.