Parts mounting inspection method

Abstract

An inspection method for inspecting the posture of parts mounted on a circuit board. This method consists of providing a moving unit for moving a stage holding the circuit board, a light source for irradiating the parts with a laser beam, an optical system path for irradiating the parts with the laser beam, a signal output path for outputting a reference signal by the laser beam, and a processing unit to process a signal from the optical system and signal output paths. In this method, reference signals A and B are obtained at first and second positions of the parts. This method further involves holding the parts at a first position, irradiating the optical system and signal output paths with the laser beam to detect a signal from each path, and outputting from the processing unit a first phase difference signal, corresponding to the first position, of output from each path. The parts are moved to the second position by the moving unit, and there the optical system and signal output paths are irradiated by the laser beam, with signals detected from each path, and the processing unit outputs a second phase difference signal, corresponding to the second position, of output from each path. The method further consists of judging the posture of the parts by comparison of the A and B reference signals and the first and second phase difference signals.