| 摘要 |
<p>The chuck (180) comprises an upper chuck face (110), which may be glass of 10-20 mm thick, and has through holes or passages (120) of diameters between approx. 50 mu m and approx. 75 mu m connected to a cavity (130) in a base (140). The base has an opening (150) for connection to a vacuum source (160), which imparts a negative pressure to the passages in the chuck face. - Beads (170) having an average diameter less than approx. 3 mm poured onto the chuck face are held by the negative pressure, through the application of a vacuum, onto a selected configuration of through holes. The beads may alternatively be attracted electrostatically to the chuck.</p> |
