Conformal coatings that effectively protect printed circuit boards are: acrylic, polyurethane, silicone. Each has its advantages and disadvantages, but the method of conformal coating application must also be considered.
The amount of processing, manual or automated application affect the choice of the appropriate method. Protecting a PCB from chemical, electrical, environmental and mechanical stresses begins with the selection of a conformal coating. In doing so, questions should be asked: What does the PCB need to be protected against? What equipment is it intended for? Under what conditions will it be used? Will it be exposed to extreme temperatures?
Once the conformal coating has been properly selected, the application method can be determined. Finding the optimal combination of chemical composition and application method will allow you to create reliable printed circuit boards.