Design rules for 3D micro-extrusion of Cu

Purpose This study aims to investigate the manufacturing limitations of copper paste-based 3D micro-extrusion, an indirect additive manufacturing (AM) approach. The focus is on evaluating the feasibility of producing complex geometrical features and identifying sensitivity to specific process parameters. Design/methodology/approach The research explores various complex features such as thin walls, internal channels, pins, and overhang structures using highly viscous pure copper pastes. Key parameters of printing and process were systematically varied to evaluate their influence on feature formation. Computed tomography (CT) analysis was used to assess the structural integrity and openness of features. Findings This study demonstrates the feasibility of manufacturing intricate features with a minimum wall thickness of 250 µm, and channel and pin feature dimensions as small as 0.43 mm and 0.32 mm, respectively. CT scans confirm the openness of fine channels throughout the part height. Overhang structures with inclinations up to 50° exhibit integrity without requiring support structures. However, single-track walls with a 10° inclination deform during high-temperature sintering but remain stable at slightly lower sintering temperatures. Overhang bridging gaps up to 1.2 mm were achievable. Originality/value This work highlights the potential of copper paste-based 3D micro-extrusion for fabricating complex geometries. It provides critical insights into the capabilities and limitations of the process and defines key constraints, offering valuable guidance for advancing the application of this AM technology in advanced manufacturing.