THE BIODEGRADATION OF CONFORMAL COATINGS

PRINTED BOARDS AND COMPONENTS ARE COATED WITH A PROTECTIVE FILM, CALLED CONFORMAL COATINGS, PRIMARILY TO PREVENT, OR AT LEAST TO MINIMIZE, DEGRADATION IN ELECTRICAL PERFORMANCE WHEN SUBJECTED TO ENVIRONMENTAL STRESSES. THESE CONFORMAL COATINGS ARE SYSTEMS OF SYNTHETIC RESINS THAT ARE DISSOLVED IN BALANCED VOLATILE SOLVENT VEHICLES. OF THE VAST NUMBERS OF SYNTHETIC RESINS NOW AVAILABLE, A SELECTED FEW TYPES OF ACRYLICS, POLYURETHANES, AND EPOXIES HAVE BEEN FOUND TO HAVE THE BEST ALL-ROUND PROPERTIES AND ARE CURRENTLY BEING USED AS THE BASIS FOR MOST GENERAL PURPOSE CONFORMAL COATINGS. THE ENVIRONMENTAL STRESSES OFTEN PRECIPITATE THE NEED FOR PARTIAL BOARD REPAIR OR REPLACEMENT. THE ONLY RESIN EASILY REMOVED IS THE ACRYLIC AND THAT ONLY BY CHLORINATED SOLVENTS, NOW CONSIDERED POTENTIAL CARCINOGENS. THE OTHER RESINS REQUIRE BURN-THROUGH OR MECHANICAL REMOVAL WHICH MAY DAMAGE THE ELECTRONICS AND/OR BOARDS. IN RESPONSE TO THESE REPAIRABILITY AND/OR REPLACEMENT PROBLEMS, TECHNICAL RESEARCH ASSOCIATES (TRA) PROPOSES TO FULLY STUDY AND DEVELOP A CONFORMAL COATING BIODEGRADATION PROCESS WHICH DOES NOT DAMAGE BOARD CIRCUITRY AND WHICH WOULD REPLACE CHEMICAL AND MECHANICAL PROCESSES. THIS WORK WILL BE BASED UPON PROVEN DEGRADATION APPROACHES FOUND IN PREVIOUS TRA WORK INVOLVING THE BIODEGRADATION OF POLYURETHANES, EPOXIES, POLYSULFIDES AND FLUOROCARBONS.