Since the conformal coating process on the PCB substrate is performed by solution spraying, bubbles may be generated in the substrate. The presence of bubbles has a critical impact on the life of the PCB, so a rigorous bubble inspection is essential b...
Since the conformal coating process on the PCB substrate is performed by solution spraying, bubbles may be generated in the substrate. The presence of bubbles has a critical impact on the life of the PCB, so a rigorous bubble inspection is essential before mounting the PCB. In this paper, we studied a method to improve the performance of bubble inspection by generating binary images suitable for bubble detection through pre-processing using two target images taken under different exposure conditions and a master image without bubbles.