What is parallax and why is this important in my inspection of conformal coated circuit boards?

Parallax is defined as a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.

How this relates to conformal coating AOI is that with a fixed camera or a standard scanner the camera is at a fixed point and the circuit board with its 3D components may have “shadows” where the camera cannot see down the side of the components. This can be seen in the two photos below.

Camera slightly to the side. Hidden areas behind the components are now shown clearly.

Camera slightly to the side. Hidden areas behind the components are now shown clearly.

Camera directly above image with the image showing all detail down the side of the components

Camera directly above image with the image showing all detail down the side of the components

 

 

 

 

 

 

 

In figure 1 some components are obscured by others since the camera is not vertically above the board. In figure 2 the image shows the components directly from above and no components are hidden by others.

Click Automated Conformal Coating Inspection System for further information on how to avoid parallax.

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About Dr Lee Hitchens

Dr Hitchens has been working in the electronics industry and the area of conformal coatings for over 25 years in various areas including sales and technical support. He has also been training people for almost the same amount of time in all areas of conformal coating whether that is materials & equipment selection, process development or troubleshooting to help them solve their particular problem. Recently, he decided that the industry needed a specific place where all of the useful knowledge on conformal coatings could be collated for users to find easily and use in their own production process. So, Nexus was born and he began the Nexus eBook project.

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