Printed Circuit Board Classification
According to the number of circuit layers: divided into single board, double board and multi-layer board. Common multi-layer boards are usually 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:
Single panel On the most basic PCB, the components are concentrated on one side, and the wires are concentrated on the other side (on the side where the chip component is on the same side as the wires, and the plug-in device is on the other side).
Since the wire appears only on one side, the PCB is called a single face. Since a single panel has many strict restrictions on the design line (because there is only one side, the wiring cannot cross and must be around the path), so only early circuits used this type of board.
Double panel board
Double Panels board： These boards have wiring on both sides, but use the wires on both sides and have proper electrical connections between the sides. The "bridge" between these circuits is called a through hole.
A through hole is a small hole filled or coated with metal on a PCB that can be connected to the wires on both sides. Since the area of the double panel is twice that of the single panel, the double panel solves the difficulty of wiring crossing in a single panel (which can be conducted through the hole to the other side), which is more suitable for circuits that are more complex than a single panel.
Multilayer Boards: In order to increase the area that can be routed, multi-layer boards use more single-sided or double-sided wiring boards. Using a double-sided inner layer, two single-sided outer layers or two double-sided inner layers, two single-sided outer printed circuit boards, alternating printed circuit boards between the positioning system and the insulating bonding material and the conductive pattern are designed according to design requirements Four-layer, six-layer printed circuit board, also known as multi-layer printed circuit board.
The number of layers in a board does not mean that there are multiple separate wiring layers. In special cases, add an empty layer to control the thickness of the board. Typically, the number of layers is even and includes the outermost two layers. Most motherboards are 4 to 8 layer structures, but technically they can implement nearly 100 layers of PCB.