High precision batch mode micro-electro-discharge machining of metal alloys using DRIE silicon as a cutting tool

This paper reports recent advances in batch mode micro-electro-discharge machining (μEDM) for high precision micromachining of metal alloys such as stainless steel. High-aspect-ratio silicon microstructures with fine feature sizes formed by deep reactive ion etching are used as cutting tools. To machine workpiece features with widths 10 μm, a silicon dioxide coating is necessary to passivate the sidewalls of the silicon tools from spurious discharges. In the machined workpieces, a minimum feature size of ≈7 μm and an aspect ratio up to 3.2 are demonstrated by the batch mode μEDM of stainless steel 304 and titanium (Grade 1) substrates. Machining rates up to ≈5 μm min−1 in feature depth are achieved in batch mode micromachining of typical microfluidic structures, including arrays of channels and cavities of different sizes. The machined features are uniform across a die-scale area of 5 × 5 mm2. Other machining characteristics are also discussed. (Some figures may appear in colour only in the online journal)