A review: development of the maskless localized electrochemical deposition technology

Presented in 1996, maskless localized electrochemical deposition (LECD) is an emerging and unconventional manufacturing technology that originated from precision electroforming and electroplating. As a novel additive manufacturing technology, it forms a three-dimensional structure layer by layer at atomic scale. In this work, we present a review of the theoretical basis and key parameters of maskless LECD technology. LECD process, almost limited to linear structure-based depositions, is capable of creating structures with high aspect ratio up to 280. However, the degree of deposition accuracy is not satisfactory during the whole process. Besides, the deposition rate is rather slow and the highest deposition rate of 25 μm/s was reported in published literature. Moreover, not all metals can be deposited due to the limitations of the electrochemical discipline. For instance, the effects of interelectrode potential difference, interelectrode gap, scanning speed, electrolyte concentration, and energy field on the quality of maskless LECD were discussed. Although all parameters abovementioned have an effect on the deposition results, there is currently no optimization software that can calculate the optimal values in an effective manner. By combining different deposition structures, special tiny part systems can be generated or integrated into devices for tackling current and future challenges in some fields such as electronic circuits, microfluidics, communications, and biomedical aspect. Additionally, this work also introduces main hybrid variants of LECD. Possible future efforts to fully exploit LECD potential are also discussed.