Patent ID: 6580491
Filing Date: 2003-06-17
Classification: G03F,H05K

Abstract:
Apparatus for compensating for distortions in the size of substrates of printed circuit workpieces having at least two alignment features, said apparatus comprising:a mask: (a) bearing an image composed of a functional circuit feature and at least two alignment features, and (b) rotatably movable about an axis extending perpendicular to said mask; a mask drive for moving said mask rotatably about said axis extending perpendicular to said mask; a table: (a) for holding a printed circuit workpiece having at least two alignment features, (b) movable horizontally, and (c) having two orthogonal axes; a table drive for moving said table horizontally; a lens movable vertically relative to said table; a lens drive for moving said lens vertically relative to said table; a light source for projecting light through said mask and said lens to project said mask alignment features onto said table; a sensor attached to said table for detecting projections of said mask alignment features; a camera for viewing said printed circuit workpiece alignment features; a controller for controlling said table drive to: (a) move said sensor to a position at least approximately at the projection of a first of said mask alignment features, (b) scan said sensor along both of said orthogonal axes through the projection of said first of said mask alignment features, (c) move said sensor to a position at least approximately at the projection of a second of said mask alignment features, (d) scan said sensor along both of said orthogonal axes through the projection of said second of said mask alignment features, (e) move said table to position a first of said printed circuit workpiece alignment features into alignment with said camera, and (f) move said table to position a second of said printed circuit workpiece alignment features into alignment with said camera; and control means responsive to: (a) movement of said table for developing and storing: (1) data of the movement of said sensor to a position at least approximately at the projection of said first of said mask alignment features, (2) data of the scan of said sensor along both of said orthogonal axes through the projection of said first of said mask alignment features, (3) data of the movement of said sensor to a position at least approximately at the projection of said second of said mask alignment features, (4) data of the scan of said sensor along both of said orthogonal axes through the projection of said second of said mask alignment features, (5) data of the movement of said table to move said first of said printed circuit workpiece alignment features into alignment with said camera, and (6) data of the movement of said table to move said second of said printed circuit workpiece alignment features into alignment with said camera, (b) said sensor for developing and storing: (1) data of the intensity of the light detected by said sensor as said sensor is scanned through the projection of said first of said mask alignment features, and (2) data of the intensity of the light detected by said sensor as said sensor is scanned through the projection of said second of said mask alignment features, (c) said camera for developing and storing: (1) data the of the alignment of said first of said printed circuit workpiece alignment features with said camera, and (2) data the of the alignment of said second of said printed circuit workpiece alignment features with said camera for controlling: (a) said mask drive to rotatably move said mask in response to said data of the scans of said sensor and data of the light intensities, so that projections of said mask alignment features are on a line parallel to one of said orthogonal axes, (b) said mask drive to rotatably move said mask in response to said data of the alignments of said printed circuit workpiece alignment features with said camera to adjust the orientation of said functional circuit feature, and (c) said lens drive to vertically move said lens in response to said data of the alignments of said printed circuit workpiece alignment features with said camera to adjust the magnification of said functional circuit feature.