Design and characterization of a vision-assisted system for surface-mount component placement

The accurate placement of surface-mount components on their respective pads is an important problem in surface-mount technology. As the lead/pad pitch size decreases, the placement problem becomes more difficult and a vision system is required to provide error information necessary to implement an accurate placement. Most vision-based placement strategies described in the open literature use component-topad alignment techniques unable to compensate for local errors in the component or the pad. This paper describes the development of a lead-to-pad placement strategy able to compensate for global and local errors. Sharp images with good illumination techniques reduce the amount of image processing, and simulation results show that lead-to-pad matching performs significantly better than component-to-pad matching.