Conformal Coating

Polyurethane Conformal Coatings

Polyurethane conformal coatings come as single-component, two-component, UV-curable, and water-borne systems. Although polyurethanes provide good chemical and moisture resistance, they are often hard to rework and have low tolerance in humid environments. 

Strengths

• Good Dielectric Properties
• Good Moisture Resistance
• Solvent Resistance
• Less Reversion Potential
• Abrasion Resistance

Weaknesses of Cure Type

Solvent Evaporation

• Moisture affects cure rate and desired properties
• Long complete cure time (up to 30 days)
• Health and safety concerns
• Potential for high stress during temperature cycling conditions
• High probability of reversion under temperature and humidity stress conditions

Heat Cure

• Cure is dependent on thickness
• Component mass affects time and temperature of cure process
• High VOC potential
• Reacts violently with presence of water
• Should be used with caution for low temperature components

UV Cure

• One component coatings require accurate application material to avoid shadowed areas
• Two part systems require meter mix equipment
• Some coatings are more difficult to rework
• UV intensity and wavelength effects cure
• Some secondary cure mechanisms require heat exposure