For the most basic PCB, the components are concentrated on one side, and the wires are concentrated on the other side. Because only one side can be wired, we call this PCB a single panel. Both sides of the double panel can be routed, so the wiring area is twice as large as that of a single panel, making it suitable for use on more complex circuits.
There are many types of surface treatment of circuit boards, which should be selected according to performance and requirements. The following are simple analysis of the advantages and disadvantages of various surface treatments of PCB.