Macroencapsulation of electronic circuits

Macroencapsulation of airborne electronic circuits has been developed to prevent moisture and contamination damage. Aircraft corrosion damage to circuitry causes $8 billion in losses in the U.S. each year. Particle impact noise detection testing is used to screen out new defective parts before installation. Coating materials presently used are normally application-specific. An all-purpose conformal coating was needed that was low cost, pinhole free, fast-drying, easily applied, moisture-proof, strong, and could be removed with common solvents. An organic polymer was evaluated for encapsulation of circuits for military use and tested for tensile strength, outgassing, thermal properties, resistance, dielectric breakdown, humidity, sealing, and bond strength in thermal cycling. The existing encapsulent, Parylene, was found to be superior or equivalent overall, but not in the areas of repairability and cost. The macroencapsulation did perform to military specifications.