Rapid manufacturing of large diameter Cu micropillars by micro-electrical discharge machining and focused ion beam

Abstract

A hybrid manufacturing method consisting of micro-electrical discharge machining and focused ion beam milling to fabricate single-crystal Cu micropillars with a diameter of several tens of microns or more was proposed. The method first utilized micro-electrical discharge machining, which adopted a micro-tool made of WC-Co material, to fabricate the coarse micropillars, one by one. It took approximately 70 s to fabricate each coarse micropillar. Seventy-six coarse micropillars were fabricated in the process of exploring optimum input parameters of supply voltage and capacitance value. Energy dispersive spectroscopy and electron backscatter diffraction analyses revealed that pristine Cu material could be obtained by removing only 1.2 μm of surface layer. The micropillar was finished using a focused ion beam to form a 15 μm diameter smooth micropillar with an aspect ratio of 3. The desired micropillar was produced by removing a surface layer of 6 μm or more from the side surface to avoid the micro-electrical discharge machining effect. It took approximately 2.5 h to complete the fabrication of a micropillar by stepwise annular milling. In the case of the hybrid method, it was possible to fabricate a high-quality micropillar 17 times faster than the focused ion beam only method.