How Do You Apply Conformal Coating?

Common application methods for conformal coatings:

• Manual spraying - For low volume production when capital equipment is not available, conformal coating can be applied by an aerosol can or handheld spray gun. This can be time-consuming and may need to be masked. It is also operator dependent, so variations are common from board to board.
• Automated spraying - Programmed spray systems can move PCBs on a conveyor under a reciprocating spray head.
• Selective coating – An automated spray system can actually be programmable, with a robotic spray nozzle applying the conformal coating to specific areas on the PCB. This is popular for high volume assembly because it eliminates the laborious masking process.
• Dipping – This is a popular conformal coating method for high volume assembly. Masking is usually necessary before PCBs are coated. Dipping is only practical when coating both sides of the board. Immersion speed, withdrawal speed, immersion time and viscosity determine the resulting film formation.
• Brushing - Brushing is used mostly for repair and rework. Conformal coating is brushed onto specific areas on the board, not generally the entire PCB. It is a low cost but labor intensive and highly variable method, so suited more for small production runs.