Why do PCB circuit boards need to use conformal paint?

Reading Volume：【 2886 】

Time：【 2018-11-17 】

Moisture is the most common and destructive main factor to PCB circuit boards. Excessive moisture will greatly reduce the insulation resistance between conductors, accelerate high-speed decomposition, reduce the Q value, and corrode the conductors. We often see the patina on the metal part of the PCB circuit board, which is caused by the chemical reaction of the metal copper that is not coated with the three-proof paint, water vapor and oxygen.
Hundreds of pollutants randomly found on printed circuit boards are equally destructive. They can cause the same results as moisture erosion-electronic decay, corrosion of conductors and even irreversible short circuits. The most common pollutants found in electrical systems may be chemicals left over from the manufacturing process. Examples of these contaminants include fluxes, solvent release agents, metal particles and marking inks. There are also major pollution groups that are caused by humans carelessly, such as body oils, fingerprints, cosmetics and food residues. There are also many pollutants in the operating environment, such as salt spray, sand, fuel, acid, and other corrosive vapors and molds.
Coating the three-proof paint on the printed circuit board and components can reduce or eliminate the decline of electronic operating performance when it may be affected by adverse factors in the operating environment. If this coating paint can maintain its effect for a satisfactory period of time, such as longer than the product's service life, it can be deemed to have achieved its coating purpose.
Even if the coating layer is very thin, it can withstand mechanical vibration and swing, thermal shock, and operation under high temperature to a certain extent. Of course, the idea that the film can be used to make the individual parts inserted into the printed circuit board have mechanical strength or sufficient insulation is wrong. The components must be mechanically inserted, and they must have their own suitable caulking agent, so that there is double insurance to prevent accidents.
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