Why do PCB circuit boards need to use conformal coatings?
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Why do PCB circuit boards need to use three-proof paint? Three-proof paint is also called PCB electronic circuit board protection oil, coating oil, moisture-proof paint, three-proof coating, waterproof glue, insulating paint, anti-corrosion paint, anti-salt spray paint, dust-proof paint, protective paint, coating paint, three-proof glue, etc. PCB circuit boards that have used three-proof paint have the properties of waterproof, moisture-proof and dust-proof, and are resistant to cold and hot shock, aging, radiation, salt spray, ozone corrosion, vibration, good flexibility and strong adhesion. Moisture is the most common and destructive factor to PCBs. Excessive moisture can significantly reduce insulation resistance between conductors, accelerate high-speed decomposition, reduce Q values, and corrode conductors. We often see patina on the metal parts of PCBs, which is caused by the chemical reaction between copper, water vapor, and oxygen without a three-conformal coating. The hundreds of contaminants found on printed circuit boards are equally destructive. They can cause the same results as moisture corrosion - electronic decay, corrosion of conductors, and even irreversible short circuits. The most common contaminants found in electrical systems may be chemicals left over from the manufacturing process. Examples of these contaminants include flux, solvent release agents, metal particles, and marking inks. There are also major contaminants caused by carelessness during human handling, such as body oils, fingerprints, cosmetics, and food residues. There are also many contaminants in the operating environment, such as salt spray, sand, fuel, acid, and other corrosive vapors and mold. Conformal coatings applied to printed circuit boards and components can reduce or eliminate degradation of electronic performance when they may be affected by adverse operating conditions. If such coatings can maintain their effectiveness for a satisfactory period of time, such as longer than the product's service life, they can be considered to have achieved their purpose. Even thin coatings can withstand mechanical vibration and oscillation, thermal shock, and operation at high temperatures to a certain extent. Of course, the idea that thin films can be used to provide mechanical strength or adequate insulation to individual components inserted into printed circuit boards is a misconception. Components must be mechanically secured and have their own sealant, providing a double insurance against accidents.
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