Why are many PCBs green in color?

I believe that we must not be unfamiliar with the circuit board, PCB circuit boards have a lot of colors, black, white, yellow, green, etc., may be a lot of electronic enthusiasts will ask, so why is most of the PCB is green? Then let's explore this issue together!

  The green part of the PCB is called solder resist and is composed of resin and pigment. The purpose is to protect, insulate, dustproof, etc. Specifically, the printed circuit board has copper foil on both sides. Copper is not as reactive as iron, aluminum and magnesium, but it is more reactive with oxygen in water. When oxygen and water vapor in the air come into contact with copper at room temperature, an oxidation reaction occurs. This oxidizes the copper foil and makes the printed circuit board non-conductive.

In order to avoid oxidization of the copper foil and also to make the surface of the PCB possible, solder resists are used. Solder resist prevents it from sticking to unwanted parts during the soldering process. At the same time, as a permanent protective film, it protects the circuit pattern from dust, heat, moisture, etc. and maintains the insulation.

When printing resist, green pigment is added and the substrate will turn green. In other words, the color of solder resist is not only green, but also various colors, such as yellow, black, red and purple. There are three reasons for using green color: eye protection; low cost; reduce errors; so many customers do most of the circuit boards in green color according to their needs, so do you know it?