Single panel

At the most basic PCB, parts focused on one side of the wire is concentrated on the other side. Because the wire only in one side, so this is called single-sided PCB (Single-sided). Because there are many single-panel strict restrictions (because only one side, between the wiring must not cross the path around alone) in the design of the line, so only early before the use of such a circuit board.
Double panel

Both sides have such a circuit board wiring, but to use the wire on both sides, both sides must be between the appropriate circuit connection down. "Bridge" between this circuit is called pilot hole (via). Pilot hole in the PCB, full of holes or painted metal, it can be connected to the wire on both sides. Because dual-panel area twice as big than the single panel, double panel to solve the single panel because wiring staggered difficulty (can pass to the other side through the guide hole), it is more suitable for use in more complex than single-sided circuit.
Multilayer

In order to increase the area can be wired, multilayer spend more single or double-sided circuit board. As an inner layer with a double-sided, two-sided or two-sided as the outer layer as an inner layer, two-sided printed circuit boards for the outer layer, by positioning system and insulation adhesive material alternately together and conductive pattern According to the design requirements for interconnection of printed circuit boards has become four, six printed circuit board, and is also known as multi-layer printed circuit board. Board of layers does not mean that there are several layers separate wiring layer, in exceptional circumstances will be added to control the air layer thickness, number of layers are generally even, and includes the outermost layers. Most motherboards are 4-8 layer structure, but can be done technically theory nearly 100 layers of PCB board. Most large-scale supercomputers use quite multilayer board, but because such computer can already use the cluster replace many ordinary computer, super multilayer has gradually not being used. Because the PCB layers are closely integrated, generally less easy to see that the actual number, but if you look closely motherboard, still can be seen.