Script – Pixpect after Reflow
After mounting components with the pick n place machine, and soldering them in the reflow oven, we have an inspection of all SMD parts on the board.
Most assembly houses use AOI or automated optical inspection machines for that purpose.
We assemble mostly prototypes, that means 1 to 5 units only, as well as small batches of PCB’s. For this kind of job AOI equipment is not really suitable as the setup is rather complex.
So we developed our own system, we call it PIXpect to eliminate long preparation and setup times.
We take high resolution pictures of every assembly panel, in the same way we do for first board inspection, and upload the pictures to our system.
Pixpect operators are opening these images in a web-interface for inspection.
The interface aligns all components form the same part in the same way next to each other.
Overlays show the operator where the component should be located, what is the desired rotation, what is printed on the body of the component, etc.
With this tool we can find missing components, wrong rotations, components where the markings are not corresponding with information in our system, mismatch between place component and reference designator.
We can also see elements that should not be present, such as misplaced components.
We can also evaluate the quality of the soldering, and find excessive solder or lack of solder, components that are mounted upside down, solder shorts between leads, or tombstoning.
Mistakes marked by PIXpect operators are shown later in the process to repair operators.
They judge if the problem is real, repair the issue if possible and move the boards further through the process.