Urethanes

Polyurethane coatings are available as either single or two-component formulations. Both formulations provide excellent humidity resistance and far greater chemical resistance than Acrylic coatings. Single component Polyurethanes, while easy to apply, enjoy long pot life but sometimes require very lengthy cure cycles to achieve full or optimum cure. In some instances the cure cycle 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 coatings can be difficult due to their very high resistance to solvents. For single-components, 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 for more wide-ranging rework concerns.