Exploration of metal 3-D printing technologies for the microfabrication of freeform, finely featured, mesoscaled structures

Abstract

This thesis investigates a mainstream metal 3-D printing technique (i.e., direct metal laser sintering of stainless steel {SS} 316L) and two relatively new metal additive manufacturing methods (i.e., lost-wax casting of sterling silver using stereolithography-printed wax masters, and binder inkjet printing of SS 316L) for the fabrication, using tens-of-microns sized voxels, of freeform, finely featured, mesoscaled metal structures part of compact systems. Characterization of the 3-D printing methods includes the assessment of dimensional accuracy and in-plane minimum feature size, measurement of vacuum outgassing and porosity, and estimation of thermal and electrical properties of the printed parts. The data demonstrate that binder inkjet printing of SS 316L has associated the smallest in-plane offset, out-of-plane offset, and eccentricity of nominally symmetric features, while showing ultra-high-vacuum compatibility and intrinsic electrical and thermal properties close to those of bulk metal. Characterization of binder inkjet-printed SS 316L MEMS cantilevers shows repeatable micron-level linear actuation and a near-isotropic Young's modulus of the printed material close to the bulk value. Also, current-voltage characteristics in air of binder inkjet-printed SS 316L MEMS corona discharge ionizers with high aspect-ratio tips are presented. In addition, high-resolution microscopy of binder inkjet-printed SS 316L electrodes part of a novel, compact, multi-electrode harmonized Kingdon mass trap estimates at -15 ptm the maximum height difference between the printed part and the digital model.