Because of its excellent anodic bonding property and surface integrity, borosilicate glass is usually used as the substrate for micro-electro mechanical systems (MEMS). For building the communication interface, micro-holes need to be drilled on this substrate. However, a micro-hole with diameter below 200 µm is difficult to manufacture using traditional machining processes. To solve this problem, a machining method that combines micro electrical-discharge machining (MEDM) and micro ultrasonic vibration machining (MUSM) is proposed herein for producing precise micro-holes with high aspect ratios in borosilicate glass. In the investigations described in this paper, a circular micro-tool was produced using the MEDM process. This tool was then used to drill a hole in glass using the MUSM process. The experiments showed that using appropriate machining parameters; the diameter variations between the entrances and exits (DVEE) could reach a value of about 2 µm in micro-holes with diameters of about 150 µm and depths of 500 µm. DVEE could be improved if an appropriate slurry concentration; ultrasonic amplitude or rotational speed was utilized. In the roundness investigations, the machining tool rotation speed had a close relationship to the degree of micro-hole roundness. Micro-holes with a roundness value of about 2 µm (the max. radius minus the min. radius) could be obtained if the appropriate rotational speed was employed.
|Number of pages||8|
|Journal||International Journal of Machine Tools and Manufacture|
|State||Published - Aug 2002|
- Borosilicate glass
- High aspect ratio
- Micro electrical-discharge machining
- Micro ultrasonic vibration machining