Geometrical characterization of micro-holes drilled in glass by gravity-feed with spark assisted chemical engraving (SACE)

Spark assisted chemical engraving (SACE) is an unconventional micro-machining technology for glass processing based on electrochemical discharges. SACE gravity-feed drilling is discussed and the material removal rate, quality and geometrical dimensions of drilled micro-holes in glass as a function of the drilling depth are characterized optically. Depending on the machining voltage and drilling depth, four different kinds of micro-hole qualities are obtained from holes with well-defined sharp contours to holes affected by thermal cracks. Based on these results a qualitative model for SACE machining by gravity-feed is given.