Fabrication of various micropatterns by maskless micro-electrochemical texturing

Abstract

In this paper, an innovative and alternative concept of maskless micro-electrochemical texturing is exploited for the fabrication of simple and complex micropatterns. In this process, the tool is masked incorporated with the textured patterns and the workpiece has no mask. This research study concentrates on generation of simple micropattern, i.e. linear micropattern, and complex micropattern, i.e. cascade micropattern using maskless micro-electrochemical texturing method without repeated use of photolithography process. A single masked patterned tool with SU-8 2150 mask can produce many high-quality simple and complex micropatterns economically using this method. A well-planned experimental set-up consisting of electrochemical micromachining (EMM) cell, electrode fixtures, electrical connections and constricted vertical cross-flow electrolyte system has been designed and developed indigenously for carrying out the experiments. Influences of major influencing parameters, i.e. machining voltage, interelectrode gap, flow rate and machining time, are investigated on width overcut and machining depth of micropatterns. For higher machining accuracy, controlled depth and lower standard deviations, machining with lower machining time, lower voltage, lower interelectrode gap and higher flow rate is recommended. From the detailed experimental investigation, the best parametric combination are voltage of 8 V, duty ratio of 30%, pulse frequency of 15 kHz, electrolyte of NaCl (0.34 M) + NaNO3 (0.23 M), flow rate of 5.35 m3/h, interelectrode gap of 50 µm and machining time of 40 s.