Moisture is the most common and destructive factor to PCB circuit boards. Excessive moisture will significantly reduce the insulation resistance between conductors, accelerate high-speed decomposition, reduce the Q value, and corrode conductors. We often see patina on the metal part of PCB circuit boards, which is caused by the chemical reaction between metal copper and water vapor and oxygen that is not coated with conformal paint.
And hundreds of contaminants found randomly on printed circuit boards can be just as destructive. They can cause the same results as moisture attack—electron decay, corrosion of conductors, and even irreparable short circuits. The most common contaminants 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 contamination groups caused by careless human handling, such as human body oils, fingerprints, cosmetics and food residues. There are also many pollutants in the operating environment, such as salt spray, sand, fuel, acid, other corrosive vapors and mold.
Coating conformal paint on printed circuit boards and components can reduce or eliminate electronic operating performance degradation when they may be affected by adverse factors in the operating environment. If this kind of coating can maintain its effect for a satisfactory period of time, such as longer than the service life of the product, it can be regarded as having achieved its coating purpose.
Conformal anti-paint coating machine
Even if the coating layer is very thin, it can withstand mechanical vibration and swing, thermal shock, and operation at high temperatures to a certain extent. Of course, it is wrong to think that films can be used to provide mechanical strength or adequate insulation to individual components inserted into a printed circuit board. Components must be mechanically inserted and must have their own suitable caulks, so there is double insurance against accidents.
1. Solvent-containing acrylic resin conformal anti-paint (currently the most widely used and popular product in the market).
Features: It has the characteristics of surface drying, fast curing time, good three-proof properties, cheap price, transparent color, flexible texture and easy repair.
2. Solvent-free acrylic resin conformal paint.
Features: UV curing, it can be dried in a few seconds to more than ten seconds, the color is transparent, the texture is hard, and the resistance to chemical corrosion and wear is also very good.
3. Polyurethane conformal paint.
Features: brittle texture and excellent solvent resistance. In addition to its excellent moisture-proof performance, it also has stable performance in low-temperature environments.
4. Silicone conformal paint.
Features: Soft elastic coating material, good pressure relief, high temperature resistance of 200 degrees, easy to repair.
In addition, from the perspective of price and performance, there is also a crossover phenomenon between the above types of conformal coatings, such as silicone-modified conformal coatings.
Post time: Oct-23-2023