Conformal Coating of PCB Boards
PCB conformal coating is a special formulation of painting, used to protect the circuit board and related equipment from the environment erosion. It has good resistance to high and low temperature. Conformal coating becomes a layer of transparent protective film after curing, forming superior properties of insulation, anti-moisture, anti-leakage, anti-shock, anti-dust, anti-corrosion, anti-aging, corona resistance, etc. Thus it can improve and extend the service life of circuit boards and related equipment to ensure the safety and reliability.
Under actual conditions like chemical, vibrated, dusty, salty spray, humid and high-temperature environment, PCB boards may generate corrosion, softening, deformation, mildew and other issues, leading to circuit failure. PCB conformal coating can form a layer of three protective film on the board surface (anti-moisture, salt spray resistance, mildew proof). In addition, higher power and closer PCB spacing are allowed thanks to the coating’s anti-leakage feature, thus requirement for component miniaturization can be achieved.
PCB conformal coating from the chemical composition can be divided into acrylic, silicone, polyurethane coating; while from the curing method, can be solvent-based curing, room temperature curing, thermal curing, UV curing, etc. Here we briefly introduce some of them.
1.Solvent-based acrylic conformal coating (the most widely used in the market now)
Features: curing fast, better three anti-properties, cheap, transparent color, soft texture, flexible, easy to repair;
2.No-solvent acrylic conformal coating
Features: UV curing, transparent color, hard texture, better chemical resistance, better wear resistance;
3.Polyurethane conformal coating
Features: crisp texture, excellent solvent resistance, better anti-moisture, stable performance in low temperature environment;
4.Silicone conformal coating
Features: soft flexible coating material, release pressure well, high temperature resistance up to 200 degrees, easy to repair.