PCB is divided into single panel, double panel and multi-layer according to the number of circuit layers. Common multi-layer boards are generally 4-layer boards or 6-layer boards, and complex multi-layer boards can reach dozens of layers.
There are three main types of PCB boards: the single panel is on the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side (when there are patch components, they are on the same side as the wires and the plug-in components are on the other side). Because the wires only appear on one side, this PCB is called single side. Because the single board has many strict restrictions on the design of wiring (because there is only one side, the wiring cannot cross and must bypass a separate path), only early circuits used this board.
Both sides of the double panel have wiring, and both sides of the double panel have wiring. However, in order to use wires on both sides, there must be an appropriate circuit connection between the two sides. The "bridge" between these circuits is called a via. Guide holes are small holes filled or coated with metal on PCB, which can connect wires on both sides. Because the area of double panel is twice that of single panel, double panel solves the difficulty of wiring interleaving in single panel (it can be connected to the other side through holes) and is more suitable for more complicated circuits than single panel.
Multilayer board in order to increase the area that can be wired, do multilayer boards use one side or two sides? Terminal block. A printed circuit board with two inner layers, two outer layers or two inner layers and two outer layers, which are interconnected by the positioning system and insulating adhesive materials alternately, becomes a four-layer and six-layer printed circuit board, also known as a multilayer printed circuit board. The number of layers on the board does not mean that there are several independent wiring layers. Under special circumstances, the thickness of the empty floor control board will be increased. Usually, the number of layers is even, including the outermost two layers. Most motherboards have a 4-8-layer structure, but technically, it can be nearly 100-layer PCB board. Most large supercomputers use quite a few layers of motherboards, but because this kind of computer can be replaced by many clusters of ordinary computers, the super multilayer board has gradually ceased to be used. Because the layers of PCB are closely combined, it is generally not easy to see the actual figures, but you can still see them by looking at the motherboard carefully.