Are usually function of green layer in the board?
In order to prevent copper oxidation, individual the soldered and non-welded parts of the PCB during soldering and protect the surface of the PCB, engineers have invented such a special coating, which the coating color is mostly green.
This coating can easily be applied to the surface of the PCB. Because of this, it forms a protective layer with a certain density. Meanwhile, it also prevents the contact between copper mineral and air. This coating of coating is named the solder mask and the material used is the solder resist.
Why is green coating?
1) Fewer irritating to the sight.
The availability and maintenance employees are not easy to suffer from eye tiredness when staring at the PCB for a long period.
2) Reduced cost.
Due to nearly all of PCB manufacturers tend to use green coating, all coating manufacturers cater to the market and maintain it a lot in stock. In other words, environmentally friendly coating is much better to get than other color covering. The cost is leaner than others to some diploma.
3) Ensure good products rate and be convenient for maintenance.
Regarding the green coating, because the surface traces aren’t completely covered, it won’t have great influence to the PCB production and ensure good products rate. Besides, it may be much convenient for the later maintenance.