Manufacturing of complex micro metallic structures via discretized voxel-based femtosecond laser-assisted localized electrochemical deposition

Metallic microstructures serve as critical components for advanced applications such as micro-electromechanical systems, aerospace, and flexible electronics. However, their three-dimensional fabrication is hindered by extreme geometric complexity and the inherent difficulty in achieving efficient forming processes. To address this challenge, a discretized voxel-based process strategy is proposed to describe the formation of metal structures during femtosecond laser-assisted localized electrochemical deposition (FsLA-LECD). At a deposition potential of −0.5 V and a single pulse energy of 8 μJ, the copper ion reduction and growth proceeded sequentially through four stages: aggregation into nanoclusters (point), formation of a continuous dense layer (surface), oriented accumulation into 3D voxels, and fusion into solid structures (body). The transition between adjacent voxels is primarily achieved through epitaxial grain growth as subsequent voxels deposit onto the interface of an existing one. Based on the above strategy, complex 3D metal structures such as vertical columns, helices, and small-angle overhangs were fabricated with high precision via a non-contact process. This was achieved through a design strategy involving layer-by-layer control of voxel height, resulting in components with high densification and excellent mechanical properties. This work introduces a discretized voxel-based manufacturing paradigm into FsLA-LECD, in which a continuous electrochemical deposition process is deliberately discretized into individual deposition voxels. The discretized voxel-based FsLA-LECD strategy proposed in this study lays the technical foundation for efficient and controllable manufacturing of 3D metallic microstructures.