Effect of Machining Limiting Factors on Drilling Progress during Spark Assisted Chemical Engraving (SACE): General Trends

Abstract

Spark Assisted Chemical Engraving (SACE) is a micro-machining technology for non-conductive materials, mainly glass, based on thermal assisted etching. Generally, during SACE, drilling proceeds at a fast rate reaching 100 µm/s for the first 100 µm and then it slows down for depths higher than 300 µm. While several techniques have been proposed to establish faster drilling, they mainly rely on tuning the machining parameters to enhance the machining performance. However, with this approach machining parameters need to be constantly tuned to achieve certain machining performance depending on the size of the tool and the features needed. Therefore, this necessitates further work to enhance understanding regarding the SACE machining process fundamentals in order to enhance machining speed and quality. Since SACE is a thermal assisted etching process, both local heating and flushing of electrolyte in the machining zone are required. However, to the authors’ knowledge there is not any study that attempts to analyze the effect of each of these machining limiting factors on the machining performance. This work attempts to clarify the effect of each flushing and heating on the drilling progress for hole depths higher than 100 microns. It therefore provides a deeper understanding of the fundamentals of the SACE machining process.