On the most basic PCB, the part is on the other side, the lead is concentrated on the other side. The PCB is called a single panel (Single-sided) because the wire only appears on one side of the side. Because the single panel has many strict limits on the design line (because there is only one side, the wiring can not cross and must go around the path), so only the early use of this type of circuit board.
Both sides of the circuit board are wiring, but with both sides of the wire, it must be in the two sides have appropriate circuit connection between the lines. The "bridge" between the circuits is called a pilot (via). The guide hole is a small hole in the PCB, full or coated with metal, which can be connected with the wire on both sides. Because the double sided board area than a single panel big double, double panel solves the single panel because of the staggered wiring difficulties can be mediated through hole which is communicated with a on the other side, it is more suitable for used in more complex than a single panel circuit.
In order to increase the area that can be used, the multilayer board uses more single or double sided wiring board. A printed circuit board is made up of two sides, four sides of the inner layer, two sides of the outer layer or two pieces of double sides as the inner layer, and the conductive pattern is printed circuit board which is connected with the design requirements. The printed circuit board is made up of six layers, which is also called a multilayer printed circuit board. The layers of the board are not representative of several independent wiring layers, in special circumstances will be added to the air layer to control the thickness of the plate, usually the number is even number, and contains the most outside of the two layer. Most of the host board is 4 to 8 layers of structure, but the technology can be done on the theory of nearly 100 layers of PCB board. Large supercomputers are mostly used in quite a number of mainframe computers, but because this kind of computer has been used in many common computer clusters, it is not used. Because the PCB in each layer are closely combined, the general is not easy to see the actual number, but if you carefully observe the motherboard, or you can see.