The signal layer: mainly used for wiring or placing components. DXP Protel usually contains 30 intermediate layers, that is, Layer1~Mid Layer30 Mid, the middle layer is used to set the signal line, the top and bottom used to place components or deposited copper.
The protective layer: mainly used to ensure the circuit board does not need to tin not be tin, so as to ensure the reliability of the circuit board to run. The top paste and bottom paste were top solder layer and bottom solder layer; top solder and bottom solder were solder mask layer and the bottom layer of the solder mask layer.
The screen layer: mainly used in printed circuit board components, production number, serial number company name etc..