What defect in SMT were cuased by dust contamination?

For boards that would need the conformal coating process, you would need to have them as clean as possible; especially the no clean process

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This have been solved by storing the boards right in all places I have worked. You open a pack, label and use. If you collect dust in such a small time window, you should totally start paying for cleaning service of the building. Electronics we build under controlled environment.

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Below list based on my observations.

Nozzle block Sensor block Insufficient issue in printing Solderability issue due to fod

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A certain degree of cleanliness is needed in SMT manufacturing environment but not as overkill as place it in a "clean room" environment...

Yes, dust could cause defect on PCBAs (and there are research papers about it too) but only the ones that's visible to human eyes and need to be plenty accumulated on PCB's surface to do it(or using a PCB that's placed outside for over a few days).... And for that level of contamination unless its a outdoor environment I doubt any indoor environment could reach that circumstances.

for some type of PCBAs need to be conformal coated or likewise they usually under went a cleaning process to remove all the contaminants after soldering.

In my view, a "clean room" level dust control might be necessary for 01005 components, but for 0201 and above? why bother? I spent many years in Mainland China and Taiwan and saw many Factories place their SMT lines in a Clean room environment but most of them are either poorly maintained or they are manufacturing PCBAs that's absolutely no need for Clean room environment. Can't figure out why. ;)

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