Arylic conformal coatings that aresolvent based are perhapsthe mostpopularof all conformal coatingsdue to their ease of application, removal and forgiving nature.

Acrylic conformal coatings dry rapidly, reaching optimum physical properties in minutes, are fungus resistant and provide long pot life. Additionally, Acrylic conformal coating give off little or no heat during cure eliminating potential damage to heat-sensitive components. They do not shrink during cure and have good humidity resistance and exhibit low glass transition temperatures.

Acrylic conformal coatings are easy to apply and can be easily removed for rework using solvents. Spot removal of the conformal coating to repair a solder joint or replace a component can be easily accomplished by localised solvent application. Although not encouraged, Acrylic conformal coatings can be soldered through if preferred.

Solvent Polyurethane Conformal Coatings

Polyurethane (urethane) conformal coatings that are solvent based are available as either single or two-component formulations.

Both urethane conformal coating formulations provide excellent humidity resistance and far greater chemical resistance than do Acrylic coatings. Single component Polyurethane's, while easy to apply and enjoying long pot life, sometimes require very lengthy cure cycles to achieve full or optimum cure. In some instances the cure cycle cycles can be accelerated by the judicious application of heat. Two component formulations can reach optimum cure properties in as little as one to three hours with the assistance of heat. However, when compared to single component formulations, two-component formulas can have a relatively short pot life sometimes making them difficult to work with.

Removal of Polyurethane conformal coatings can be difficult due to their very high resistance to solvents. The preferred method of removal is via burn through for spot repair, while the use of specially formulated Strippers enables the user to completely remove the coating from an entire PCB assembly.