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Zulki's PCB Nuggets: Another Look at AOI

PCB inspection is taking on greater significance as boards and packaging become increasingly smaller, with greater functionality. Automated optical inspection (AOI) and its backup associate, X-ray, team up to catch a variety of board assembly problems. But it’s AOI that’s at the forefront of this process.

AOI takes on a variety of key assignments, such as checking out the numbers labeled on passive and active devices and matching them with the database to assure they’re legitimate components, as specified in the bill of materials (BOM). Also, if alternate parts are used, the AOI machine is trained to verify them, regardless of manufacturer, as long as the device has the same footprint, value, tolerance, voltage, package type, etc.

That’s only the beginning. AOI is excellent at detecting missing or wrong components and misalignments. If a component is misaligned, say at 30° or 45°, AOI catches it. It also catches opens and bridging, and it can check for skewed parts and tombstoning. AOI can detect anything as long as it’s written on the component. Read the full column here.Editor's Note: This column originally appeared in the October 2013 issue of SMT Magazine.