Abrasive Blasting Apparatus

Author:  Bowling Jr., J. E. et al
Source:  US Patent 3,270,464
Doc ID:  1966000
Year of Publication:  1966
Abstract:  
This invention relates to abrasive blasting apparatus for machining work pieces, particularly, silicon wafers. Silicon wafers used in the electronics industry must be made with precise dimensions. As a result, the faces of the saw-cut slices are lapped to a uniform thickness and surface finish. These slices are then machined into a number of smaller wafers. Although abrasive airblast machines are sometimes used in accomplishing this, it is difficult to uniformly feed the very fine abrasive particles because of their high repose angles and their tendency to pack or dump in the abrasive supply hopper from which the abrasive is returned to the blasting nozzles. A object of this invention is to provide an apparatus for efficiently machining object, such as silicon slices, wherein the abrasive does not pack in the hopper so that the abrasive can be constantly recirculated through the apparatus.