A printed circuit board inspection system with defect classification capability

Abstract

An automated visual printed circuit board (PCB) inspection is an approach used to counter difficulties occurred in human’s manual inspection that can elimin ates subjective aspects and then provides fast, quantitative, and dimens ional assessments. In this study, referentia l approach has been implemented on template and defective PCB images to detectnumerous defects on bare PCBs before etching process, since etching usually contributes most destructive defects found on PCBs. The PCB inspection system is then improved by incorporating a geometrical image registration, minimum thresholding technique and median filtering in order to solve alignment and uneven illumination problem. Finally, defect classification operation is employed in order to identify the source for six types of defects namely, missing hole, pin hole, underetch, short -circuit, mousebite, and open- circuit.