07.06.2021 | Technical topic

Layout Tipps & Tricks

Layout Tipps & Tricks

Avoid AOI pseudo errors

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Optical inspections are intended to help find errors, such as components placed at an angle on assembled printed circuit boards, after the assembly has been completed.

A pseudo defect is a position to be checked by the AOI (Automatic Optical Inspection) that has been incorrectly identified as a defect. These can be avoided by taking component spacing into account.

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As can be seen in the image, C360 is located within the search range of C228 (purple in the image). If you move C228 one millimeter further away from C360, there will be no pseudo error in the automatic optical inspection.


Note: When locating an electrolytic capacitor, the bright circle and the plastic base are searched by height. In the areas to the left, right, top and bottom of the body, the search range can be reduced.

Components to the left and right of the terminals of the electrolytic capacitor are always recognized as belonging to the component body.
The electrolytic capacitor is incorrectly recognized as faulty, e.g. with "Dimensions incorrect", or "Offset".


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Tips and tricks from 30 years of experience in electronics production can be found in our   EMS Design Guide.

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