Abstract

This thesis presents a study of the variability in spark assisted chemical engraving (SACE) gravity feed drilling in glass. SACE gravity feed drilling is a novel micromachining technology for use on non-conducting materials that has yet to move beyond academic investigation. However, SACE is a promising technology. It can be used to create high quality structures, at low cost, using a machine that could be installed into any laboratory. One problem SACE faces is it has issues with reproducibility. This is why the variability of the process is studied here. The goal of this thesis is to quantify and reduce the variability in SACE gravity feed drilling. This goal is accomplished through three steps. First, the process is modeled to provide an efficient way to quantify variability. Two new stochastic models are presented that relate the depth evolution of SACE gravity feed drilling to the voltage. Statistical tests are used to validate the models. Second, experimental studies of the variability of the depth evolution are discussed. The effect on the variability of having poorly regulated bulk electrolyte temperature and level is studied. Finally, experimental results from two feedback controllers that are capable of reducing the variability in SACE gravity feed drilling are discussed. The results from these controllers are compared with the predictions of one of the models developed.