It is divided into three categories: single panel, double-sided board and multilayer circuit board. 1. Single panel, on the most basic PCB, the parts are concentrated on one side and the wires are concentrated on the other side. Because the wires only appear on one side, this kind of PCB is called single-sided circuit board. Single panel is usually simple to manufacture and low cost, but the disadvantage is that it can not be applied to too complex.