Automated Optical Inspection, known as AOI, is an automated visual inspection used on printed circuit boards during the manufacturing process.
The purpose of the Automated Optical Inspection is to ensure the quality of the circuit board at various steps in the process. There are elements of inspection that can be missed by the human eye that can be caught faster and more efficiently using the optical inspection process.
AOI is used after the copper panels have been exposed, developed and etched, leaving the final traces of the internal layers of the board, prior to laminating the layers together.
The corresponding electronic data used to create the circuits is programmed into the AOI system. That data is then used as the baseline comparison for the finished circuits on the board.
The lens of the system will quickly scan the panel for any obvious defects as well as consistency with the provided data.
When a flaw is found the AOI will stop and show the area on the main overhead viewing screen. The operator can then inspect the area and determine what if any action needs to be taken to correct the problem. They can mark the area and then complete the scanning process and assign any re-work needed to maintain the quality of the board before moving on to the next step.
Other key items that it can inspect include: Line widths (too small or too large), spacing violations, too much copper, missing features, short circuits, etc. These are some of the many rules that can be added to the Automated Optical Inspection system to identify problems.
AOI is an important part of the PCB manufacturing process that helps to ensure on-time delivery, quality and consistency for manufacturing of printed circuit boards.