Conformal coating can cure between seconds to days, depending on the type of resin, curing method, and thickness of the coating. There are several types of curing mechanisms available, depending on the type of resin chosen:
Evaporative Cure Mechanism - Liquid carrier evaporates, and what is left behind is the coating resin. This curing method is typically combined with another mechanism like moisture cure. PCBs can generally be handled within an hour, but it will take days to fully cure, when the coating has reached it final properties.
Moisture Cure - Primarily found in silicone and some urethane systems. The coating resin reacts with ambient moisture to form the polymer coating. Moisture curing is often combined with evaporative curing. As carrier solvents evaporate, moisture reacts with resin to initiate final curing. PCBs can generally be handled within minutes or an hour, but it will take days to fully cure, when the coating has reached it final properties.
Heat Cure - Heat cure mechanisms can be used with one or multicomponent systems, as a secondary cure mechanism for UV cure, moisture cure, or evaporative cure. The addition of heat will cause the system to polymerize, or speed the cure of the system. This helps when one cure mechanism is insufficient to gain the cure properties required or expected.
UV Cure - Coatings that are cured by ultraviolet light offer very fast production throughputs. They are 100% solid systems with no carrier solvents. UV curing is line‐of‐site, so a secondary curing mechanism is needed under components and in shadow areas. Cure time is near instantaneous when exposed to UV, but shadowed areas may take days to full cure.