Parts mounting inspection method

• US 5,329,359 A
• Filed: 05/15/1992
• Issued: 07/12/1994
• Est. Priority Date: 05/17/1991
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tachikawa, Jin
• Primary Examiner(s): Johnston, Jill A.
• Assistant Examiner(s): Cano, Milton I.
• Application Number:
  US07/883,699
• Time in Patent Office: 788 Days
• Field of Search: 356/394, 356/398
• US Class Current: 356/398
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: H05K 13/0815 Controlling of component placement on the substrate during or after manufacturing

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.

Claims

1. An inspection method for inspecting posture of parts mounted on a circuit board, said method comprising the steps of:

providing moving means 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 from the light source, a signal output path for outputting a reference signal by the laser beam from the light source, and processing means for processing a signal from each of the optical system path and the signal output path;

obtaining reference signals A and B at first and second positions, respectively, of the parts;

holding the parts in the first position and irradiating the optical system path and the signal output path with the laser beam to detect a signal from each path, and outputting from the processing means a first phase difference signal, corresponding to the first position, of output from each path;

moving the parts to the second position by the moving means;

holding the parts in the second position and irradiating the optical system path and the signal output path with the laser beam to detect a signal from each path, and outputting from the processing means a second phase difference signal, corresponding to the second position, of output from each path; and

determining the posture of the parts by comparison of the reference signals A and B, and the first phase difference signal in the first position and the second phase difference signal in the second position, the determination being made using a comparison signal which is a phase difference of the reference signals A and B in the first and second positions and a difference between the first and second phase difference signals in the first and second positions.

2. An inspection method for inspecting the existence or non-existence of parts mounted on a circuit board, said method comprising the steps of:

providing a light source for irradiating the parts with a laser beam, an optical system path for irradiating the parts with the laser beam from the light source, a signal output path for outputting a reference signal by the laser beam from the light source, and processing means for processing a signal from each of the optical system path and the signal output path;

holding the parts in a predetermined position to detect a reference signal by irradiating the parts with the laser beam;

holding the parts in a first position and irradiating the optical system path and the signal output path with the laser beam to detect a signal from each path, and outputting by the processing means a phase difference signal, corresponding to the first position, of output from each path; and

determining the existence or non-existence of the parts on the basis of the reference signal and the phase difference signal.

3. An inspection method for inspecting a height posture of parts mounted on a circuit board, said method comprising the steps of:

providing moving means 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 from the light source, a signal output path for outputting a reference signal by the laser beam from the light source, and processing means for processing a signal from each of the optical system path and the signal output path;

obtaining reference signals A'"'"' and B'"'"' at first and second positions, respectively, of the parts;

holding the parts in the first position and irradiating the optical system path and the signal output path with the laser beam to detect a signal from each path, and outputting from the processing means a phase difference signal, corresponding to the first position, of output from each path to detect a signal representing the height of the parts in the first position;

moving the parts to the second position by the moving means;

holding the parts in the second position and irradiating the optical system path and the signal output path with the laser beam to detect a signal from each path, and outputting from the processing means a phase difference signal, corresponding to the second position, of output from each path to detect a signal representing the height of the parts in the second position; and

determining an inclined posture of the parts by comparison of the reference signals A'"'"' and B'"'"' and the signals representing the height of the parts in the first and second positions.