Epoxy Conformal Coating

Conformal Coating

Epoxy Conformal Coatings

Epoxy-based coatings are usually two-part systems with limited pot life.  Similar to polyurethanes, they provide good moisture and chemical resistance.  A major downfall is that they are almost impossible to remove chemically for rework.


  • Useful to 150°C [302°F]
  • Harder Durometer
  • Abrasion Resistance
  • CTE Closer to Epoxy PCB Substrates
  • Higher Tg
  • Dielectric Properties


Weaknesses of Cure Type

Solvent Evaporation

  • Higher chloride contamination potential
  • Process intensive, difficult to maintain viscosity, complex mix ratios
  • Potential for high stress during temperature cycling conditions
  • Difficult to rework
  • 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
  • Susceptible to cure inhibition
  • Selective coating quality (edge definition) could be impacted
  • Shrinkage (3% - 10%), potential for damaging fragile (e.g. glass) components
  • 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


  • Cure inhibition
  • Short work life
  • Contamination sensitive
  • Difficult to rework
  • Pungent order
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