Machine vision processing/selection in printed circuit board manufacturing

Machine vision applications are common in the manufacturing of PWBs. Machine vision systems are used in the placement of surface mount devices with lead pitch of 0.025 inch or less. There are two steps in the successful placement of surface mount devices, as follows: (a) The location of the device on the vacuum tip which picks and places the device must be determined. Translation and rotational offsets are the difference between the device and the vacuum tip center and rotation. The part orientation (translational offset) and orientation angle (rotational offset) must be known for accurate placement. (b) The location offiducials (reference marks incorporated into the circuit pattern) must also be determined