Abstract
A new pneumatic non-contact handling method is discussed in this paper, in which swirling flow is employed. Air flows into a vortex cup tangentially through a nozzle, and swirls along the wall to make a vacuum at the central area. Then, air is discharged to the atmosphere through a thin gap between the cup and a wafer under the cup. Analysis is conducted by dividing air flow into three parts. They are flow rate characteristics of the nozzle, swirling flow inside the cup and flow through the gap. Pressure distributions inside the cup and the gap are discussed and their analytical results are validated experimentally. It is clear that the vacuum is caused by the swirling air inside the cup, and it depends on the gap and the supply pressure. Furthermore, it is found that the wafer can be handled and kept in a balanced state automatically during a certain range of a considerably thin gap depending on the weight of the wafer. However, the wafer will fall down over this range.
