Study of Hole-Machining on Pyrex Wafer by Electrochemical Discharge Machining (ECDM)

Abstract

The gap control problem in hole-machining of Pyrex® wafer by electrochemical discharge machining (ECDM) to obtain a smooth quality and acceptable material removal rate is studied. Analysis of the pulse signals shows that the average current pulse interval is constant, and it is mainly related to the ion translation conditions, such as the electrolyte concentration and the flushing strategy. The most steady and intense average current density can be obtained if the voltage on-time is around 3 times the average current pulse interval and the voltage off-time is 1/4 of the on-time for bubble film dissipation. The utmost allowable feed rate at each depth is recorded as the reference of the feed rate in real continuous machining to avoid the damage to the wafer. By applying 80% of the extreme allowable feed rate, 99.9% quality-proved holes can be acquired. The diametric error at the entrance or exit is within 6%. Besides, there is no crater-like problem around the hole that facilitates the succeeding bonding process. This study contributes to the successful production of reusable optical biological chips with integrated micro fluidic channels.

Characterization and modeling of 2D-glass micro-machining by spark-assisted chemical engraving (SACE) with constant velocity

“…In voltages less than 28 V which results in a different electrochemical discharge regime, perfect edge and surface quality are obtained even at tool speeds less than 5 µm s −1 . This effect has also been reported for micro-hole drilling by gravity feed [7] and constant feed [16].…”

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

“…Some pioneering work about the material removal rate was done by Cook et al [8] and completed later by other research groups [9][10][11][12][13][14][15]. In [16], it was mentioned that micro-holes with a depth of 450 µm in glass are drilled typically in 30 s. Liao et al [17] reported that the maximal allowable feeding rate in hole-drilling at constant feed is typically around 15 µm s −1 . Characterization of the micro-hole quality and achieved geometrical tolerances has so far never been reported in the literature.…”

Electrophoretic deposition grinding (EPDG) for improving the precision of microholes drilled via ECDM

“…Accordingly, how to reduce HAZ and improve the microhole quality is a key question for widening ECDM applications. Liao and Peng [15] also reached this finding and used the stable spark condition to drill holes with diameter φ2 mm by adjusting the feeding rate and applying voltage. The smallest average taper angle is around 8 • .…”