Conformal coatings are used to enhance the performance and reliability of printed circuit board assembly, enabling it to be used in harsh environments such as underwater, aerospace, and military applications. Consumer electronics manufacturers are increasingly using conformal coatings as an economical method to improve product reliability.
When a printed circuit assembly board without a conformal coating is exposed to humid air, a thick film of water molecules will form on its surface, reducing the surface insulation resistance (SIR) of the circuit board. The lower the surface insulation resistance, the worse the transmission performance of the electrical signal will deteriorate. The typical consequence is that it will cause crosstalk, electrical leakage and transmission interruption, which may lead to a permanent interruption of the signal, that is, a short circuit.
The moisture film on the printed circuit board without a conformal coating also provides favorable conditions for metal growth and corrosion, which in turn will eventually affect the insulation strength and high-frequency signals, dust, dirt and other environments that fall on the assembly board Contaminants continue to absorb moisture, thereby expanding its negative effects, and conductive particles like metal fragments can also cause electrical bridging.
Conformal coating is a layer of coating wrapped around the printed circuit assembly board. The thickness of this film is 0.005in, which seals dust and environmental contaminants outside the circuit board. Of course, the conformal coating may also seal contaminants that were not removed during the pre-cleaning process, so it is important to clean the surface of the circuit board before applying the conformal coating.
The function of the shape-protecting coating is as follows:
1) Protect the circuit from extreme environments and prevent it from being affected by moisture, fungi, dust and rust;
2) Prevent the circuit board from being damaged during manufacturing, assembly and use, reduce the mechanical stress on the components and protect it from thermal oscillations;
3) Reduce wear during use;
4) Since the protective coating increases the insulation strength between the conductors, it enhances the performance of the circuit board and allows greater component density.