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

Schürch, Patrik

PhD Tesis (2020)

This thesis aims to investigate the electrodeposition into a 3D template and discuss the in- fluence 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 investiga- tion with the explicit regard of inspecting their properties and performance for future use in MEMS-devices. Simple pillars were investigated at first to inspect the mechanical 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 examined. Micromechanical shear test specimenwere 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 ofCopper Nickel alloys was investigated. A 3D time-dependent pulse electrodeposition simulation was created and the deposition of large 2D components were simulated and compared to experimental values