Classification of PCB circuit board
1. Single panel
On the most basic PCB board, parts gather on one side and wires gather on the other side. Because the wires only appear on one side, this kind of PCB is called single side. Because there are many severe constraints on the planned circuit of a single panel (because there is only one side, the wiring cannot cross, but must go around a separate way), such boards can only be used in the early circuit.
2. Double sided board
This kind of PCB circuit board has wiring on both sides, but to use double-sided wires, there must be appropriate circuit connection between the two sides. This "bridge" between circuits is called a via. The guide hole is a small hole filled or coated with metal on the PCB circuit board, which can be connected with double-sided wires. Because the area of the double-sided board is twice as large as that of the single panel, the double panel solves the difficulty of staggered wiring in the single panel (it can be connected to the other side through the guide hole), and it is more suitable for more messy circuits than the single panel.
3. Multilayer board
In order to increase the area of wiring, multilayer boards use more single or double-sided wiring boards. The printed circuit board with one double-sided as the inner layer, two single-sided as the outer layer, or two double-sided as the inner layer and two single-sided as the outer layer, which is alternately connected together through the positioning system and insulating bonding materials, and the conductive graphics are interconnected according to the planning requirements, becomes a four layer and six layer printed circuit board, also known as multi-layer printed circuit board. The number of layers of the board does not mean that there are several independent wiring layers. In special cases, empty layers will be used to control the board thickness. Generally, the number of layers is even, including the outermost two layers. Most of the main boards have a 4-8-layer structure, but technically, nearly 100 layers of PCB can be achieved in theory. Most large supercomputers use quite multi-layer motherboards, but because such computers can now be replaced by clusters of many ordinary computers, super multi-layer boards are no longer used. Because all layers in the PCB circuit board are closely combined, it is generally not easy to see the actual number. However, if you carefully observe the motherboard, you can still see it.
