Test Method AOI - Automatic Optical Inspection
The automatic optical inspection of electronic boards relieves the strain on the manual visual inspection and leads to repetitious test criterias and thereby often to increased quality in series production with, reducing costs at the same time.With the automatic optical inspection the major part of typical manufacturing error can be found and repaired economically .
- Placing and position of components
- Polarity of components (with visible markings)
- Solder joint inspection (as far as visible)
- Lifted components by means of laser measurement
Within the electronic boards inspection, the extreme fluctuations and differences of brightness, caused by reflections on shiny or partly matt-finished solder joints and the fluctuations of brightness due to different batches of components and PCBs represent a major difficulty when it comes to image acquisition and image analysis.
The inspection severity and thereby the slippage rate can be adjusted with most systems. A high inspection severity leads to borderline cases being displayed as faults, the so called pseudo faults. As a slippage rate is not tolerated in most cases, a certain amount of pseudo faults is accepted.