Board divided by the number of layers, then divided into single-sided, double-sided, and multi-layer circuit board three major categories. First, the single-sided PCB, in the most basic PCB, parts concentrated in one side, the wire is concentrated in the other side. Because the wire only appears in one side, so called the PCB called single-sided circuit board. Single-sided panels are usually made simple, low cost, but the shortcomings can not be applied to too complex products. Double-sided panel is a single-panel extension, when the single-layer wiring can not meet the needs of electronic products, it is necessary to use the double panel. Both sides are covered with copper traces, and can be through the hole to turn between the two layers of the line, so that the formation of the required network connection. A multilayer board is a printed circuit board having three or more conductive pattern layers interposed therebetween with insulating material interposed therebetween, and in which the conductive patterns are interconnected as required. Multi-layer circuit board is the electronic information technology to high-speed, multi-function, large capacity, small size, thin, lightweight direction of the product. According to the characteristics of the circuit board, then divided into soft board (FPC), hard board (PCB), soft and hard combination board (FPCB).