There are three main types of PCB boards:
The single-sided Boards are on the most basic PCB, with parts concentrated on one side and wires concentrated on the other (the same side as the wires when there are SMT elements, and the other side of the plugins).Because the wire only appears on one side, the PCB is called a single-sided.Because the single panel has many strict limitations on the design circuit (since there is only one side, the wiring cannot be intersected and must be wound around a single path), only early circuits use such boards.
Double-sided Boards have wiring on both sides of the board, but to use two sides of the lead, you need to have proper electrical connections between the two sides.The "bridge" between these circuits is called the via.
3.A guide hole is a small hole in a PCB, filled or coated with metal, that can be connected to two sides of a wire.Because the area of the double panel is twice as large as that of the single panel, the double panel solves the difficulties in the single panel due to the interlacing of wiring (it can be connected to the other side through holes), and it is more suitable to be used in the electrical circuit which is more complicated than the single panel.
To increase the space available for wiring, multi-layer Boards use more single or double-sided wiring Boards.With a double lining, two one-way for outer layer or two double lining, two blocks of single outer layer of the printed circuit board, through the positioning system and alternate insulation adhesive materials and conductive graphics interconnection according to design requirement of printed circuit board becomes four, six layer printed circuit board, also known as multilayer printed circuit board.
5.The number of layers of the board does not mean that there are several independent wiring layers. In special cases, empty layers will be added to control the thickness of the board. Usually, the number of layers is even, and the two outermost layers are included.Most of the motherboards are four to eight layers, but technically they can be nearly 100 layers.
6.Large supercomputers are mostly multi-tiered mainboards, but because they can be replaced by clusters of ordinary computers, they are becoming obsolete.Because the layers in the PCB are tightly coupled, it's not easy to see the actual number, but if you look closely at the motherboard, you can still see it.