Shaping of micro mould tools manufactured by UV LIGA and Selective Laser Melting (SLM)

Abstract

Polymeric micro and nano surface structures are used widely in microfluidics, micro-optics and functional surfaces. Replication processes for these structures, e.g. micro injection moulding, hot embossing, are critical, but constricted by demoulding. Demoulding defects caused by friction, adhesion and thermal stresses, can cause microstructure distortion or, damage, and thus influence the final product performance. Forming and shaping of micro-tools will facilitate demoulding. In this research, two fabrication processes i.e., UV LIGA and SLM have been used to manufacture micro moulds of Ni and 316L SS. A highly precise process, UV LIGA, is used to make micro features of nickel having a low surface roughness Sa (<50nm). A faster but less precise microfabrication process is also used, SLM 3D printing, to manufacture stainless steel micro features having a high surface roughness Sa (>1μm). Moulds manufactured using these two processes are subjected to electropolishing to examine changes in geometry and surface roughness. Electropolishing is used for shaping and polishing of the micro features to bring a design change and address demoulding challenges. To ensure a green environment and human safety, nickel sulfamate solution is also used for electropolishing. EP has the potential to shape and polish micro features, thus enhancing mould release performance.