Coating inspection with UV light
Various components PCB’s used in electronics are coated thus protect from moisture. The coating is difficult to see with the human eye. However the correct application of most coatings can be easily checked when illuminated with 365 nm UV light. Coatings typically separate from uncoated parts with a sharp interface when exposed to intense UV light. With darkening, the differences increase, however, the adaptation of the human eye to darkness must be kept in mind during the inspection.