Template-assisted electrodeposition of nickel and nickel copper 3D microcomponents

New types of metamaterials and architectured material require metallic materials with precise structural design in the microscale. However, additivemanufacturing of metallic structures in themicroscale has proven difficult, as the demand for the material quality and accuracy of the 3D structure is high. Of themultitude of techniques available, template-assisted electrodeposition (TAE), also known by its German abbreviation, LIGA, has shown excellent results for the production of 2D components. With new lithography techniques, especially two-photon lithography (TPL), TAE shows promise of microscale additive manufacturing for 3D metal structures. This thesis aims to investigate the electrodeposition into a 3D template and discuss the influence of the template on the local current density and the resulting microstructure of the deposit. 3D finite element simulations were used to understand the process of template filling. The electrodeposited structures were investigated towards their shape accuracy as well as their microstructure. Various deposited structures were used for micromechanical investigation with the explicit regard to inspect their properties and performance for future use in MEMS-devices. Simple pillars were investigated at first to inspect themechanical properties and arrangement of the templates in arrays. In this work, subsequently, 3D micro springs were produced and their properties compared with theoretical mechanical simulations. These springs exhibited significant strength, unprecedented in microsprings of this size. Following simple templates, more complex templates with multiple ongoing growth fronts were investigated. Micromechanical shear test specimen were produced and the template design was investigated. These templates were also used to investigate the effectiveness of pulse electrodeposition was investigated to fill corners. Furthermore, the microstructure showed elongated grains along the growth direction allowing insight into the deposits growth. Where to growth fronts meet an accumulation of grain boundaries was visible in the microstructure, but showed no porosity. Building on these results, microlattices with a body center cubic structure were designed and tested. The microlattices showed remarkably high strength as well as excellent promise for energy absorption. Building on the success of the technique and the previous structures, the electrodeposition of Copper Nickel alloys was investigated. A 3D time-dependent pulse electrodeposition simulation was created and the deposition of large 2D components was simulated and compared to experimental values. Overall, trough these specific case studies, it was shown that TAE combined with TPL produces microcomponents with excellent accuracy, homogenous microstructures with no significant defects and excellent mechanical properties. The method has shown reproducibility. The insight gained by the electrodeposition simulation can be used in the future for others to emulate the process or create their electrodeposition simulation.