Inspection window guard banding

摘要

A technique for developing an inspection program for a circuit board to be run on an AOI system includes determining a characteristic, such as average gray level, of each window of the circuit board. The positions of the windows are varied slightly to simulate expected errors in the placement of the windows relative to the circuit board. After varying the positions of the windows, the characteristic of each window is determined again. Different values of the characteristic corresponding to slightly different positions are compared for each window. Values that substantially change for a window indicate a strong sensitivity to position. These windows may be reported to a programmer for corrective action.