General, PCB's mostly green or brown, of course, there are some beautiful products using more brilliant colors, but mostly for appearance rather than the consideration of product performance or production requirements, which is the Solder Mask (solder mask) color .
The PCB, the solder resist layer is important, it is an insulating protective layer can protect the copper component can be prevented from being welded to the incorrect place.
Also on the solder layer on layer will be printed silkscreen (silk screen). Usually in it will be printed on text and symbols (mostly white) to mark the location of the various components on the board.
