Polyurethane Coatings

Polyurethane coatings are among the most popular choices for protecting electronics applications. They are available as single component, two component, UV curable and water borne systems. As a group, urethanes provide excellent humidity and chemical resistance in addition to outstanding dielectric properties for extended periods. These properties and more make enable urethane coatings to protect critical electronics and components.

Urethane Conformal Coating Process

Polyurethane coatings are applied with one of three liquid deposition techniques:

• Dip: An arm holds the device and lowers it into a dip tank containing the urethane coating. This technique provides excellent penetration and a fast processing time. Dipping processes can be manual or automated.
• Spray: Using a spray gun or aerosol can, urethanes can be sprayed onto the device. Robotic processes can automate coating for high-volume production needs.
• Brush: With this technique, the operator brushes the coating onto the device. Brushing is common for low volume orders.

The final step for urethane coatings is curing. Single-component urethane coatings are easy to apply; the trade-off, however, is that they have a long cure cycle (up to several days). Two-component urethane coatings have a shorter cure cycle (1-3 days) but are more difficult to apply.

Rework of Polyurethanes

Due to their excellent chemical resistance, urethane conformal coatings can be quite difficult to remove or rework, especially after the material has gone through a full cure.