Automated Optical Inspection (AOI) machines detect failures in Printed Circuit Boards (PCBs) through vision tests using high-definition cameras and numerous sources of lighting such as LED, fluorescent, infra-red or ultra-violet. The detectable defects include tombstones, misaligned parts, scratches, open circuits, incorrect polarity of components, uneven soldering etc. For utmost performance, it is necessary for the PCBs to be free from any defects as they may cause a significant loss in performance.
AOI machines detect two major types of failures in PCBs:
1. Calamitous failures such as absent components.
2. Standard failures such as asymmetrical fillets or skewed components.
The AOI mechanism is best suited for production environments with high volume production, as its implementation is complex and time-consuming. With small component variability in high volume production, it is reasonable to inspect finished products which are of a particular design or part configuration.
It must be noted that Automated Optical Inspection machines are not meant for problem-solving or for improving the manufacturing process, it is just a monitoring tool that inspects PCB in production that is placed after solder reflow.