Key technology of microelectrode array fabrication by ultrasonic enhanced micro-EDM

Micro electrical discharge machining (EDM), enhanced with ultrasonic vibration, is explored and assessed as a new technology for developing microelectrode array, for microelectrode array fabricated by LIGA has shortcomings such as complex technology and high price. Based on the mechanism of micro-EDM, micro-hole array discharges to fabricate microelectrode array by reverse copying. In the process of reverse copying, the thicker rod electrode can't rotate, resulting in electric arc and short-circuit easily, so it is necessary to add ultrasonic vibration on the plane plate electrode. According to the technology, a set of micro-EDM system is designed and developed. On the machining system, influence of ultrasonic vibration is analysed from the way of vibration mechanics through theoretical analysis and experimental observation. Compared with machining without ultrasonic vibration, single discharging energy decreases 1/2, discharge frequency improves three times, machining efficiency increases two times and better surface quality is achieved. Finally, 5 × 5 arrays of microelectrode and microhole made by these microelectrode arrays are got, the diameter of single electrode is less than 30μm and height-towidth aspect ratio is more than 8, moreover these arrays of microelectrode and micro-hole have very good surface quality.