Patent ID: 6446948
Filing Date: 2002-09-10
Classification: B25B,H01L

Abstract:
An apparatus for overcoming distortions in a workpiece, comprising:a vacuum chuck having a surface, a perimeter, and an array of ports extending through the surface inside the perimeter, the surface being adapted to support a workpiece thereon; a vacuum source for drawing a vacuum through the array of ports such that the workpiece is adapted to adhere to the surface of the vacuum chuck; control means for selectively evacuating the array of ports in the vacuum chuck via the vacuum source in a timed sequence so as to overcome asymmetrical distortion in the workpiece; and wherein the ports are arranged in multiple, symmetrical, concentric square rings centered on a central port located at an intersection of perpendicular surface axes, with at least some of the ports aligned with each of the axes, and a plurality of outlying ports aligned with the axes and located radially beyond an outermost square ring adjacent to a perimeter of the chuck.