The surface treatment of PCB boards is generally dominated by immersion gold and HASL, and of course gold plating and OSP are also available. In particular, immersion gold and OSP are easier to oxidize than HASL, so you need to wear gloves during the production process, otherwise the copper surface will be affected, and customers will not be able to apply tin when patching.
There is generally a color on the surface of the PCB board, which is the solder mask. His function is an insulating protective layer to protect the copper and lines on the board. For better production and processing, customers will print a layer of silk screen on the solder mask layer, which is also the characters we often say.
