Generally, PCB circuit boards can be divided into single-sided and double-sided circuit boards according to the number of layers. and multilayer circuit boards into three major categories.
1. Single-layer pcb circuit board:
On a basic circuit PCB, the components are gathered on one side, and the wires are gathered on the other side. Since the wires only appear on one side of the inside, this type of PCB is called a single-layer PCB (Single-sided). Because the single-layer pcb circuit board has many strict restrictions on the design of the circuit (since it can only be on one side, the wiring cannot be crossed and must be wound in a separate way), so only the initial circuit or the circuit with particularly simple wiring can be used. class of plates.
2. Double-sided circuit board:
This type of pcb circuit board has wiring on both sides, but if you want double-sided wires, you must have a proper circuit connection between the two sides. The "bridge" between such lines is called a guide hole (via). The guide hole is a small hole filled or coated with metal on the pcb circuit board PCB, which can be connected to the wires on both sides. Since the area of the double-sided circuit board is twice as large as that of the single-layer pcb circuit board, the buried double-sided circuit board solves the difficulty of interlacing wiring in the single-layer pcb circuit board (it can be passed to the other side through the guide hole), and it is more It is suitable for use on circuits that are more complex than single-layer pcb circuit boards.
3. Multi-layer circuit board:
In order to increase the range that can be wired, more single or double-sided wiring boards are used on multilayer circuit boards. Use a double-sided circuit board as the inner layer, two single-layers as the surface layer or two double-sided as the inner layer. Two single-layer PCB circuit boards are used as the surface layer, and they are alternately connected according to the positioning system and insulating bonding materials and conduct electricity. The pcb circuit board PCB whose graphics are interconnected according to the design requirements becomes a four-layer or six-layer pcb circuit board PCB, also known as a multilayer circuit board PCE. The number of layers of the board does not have multi-layer wiring layers. In special cases, it can enter the empty layer to control the thickness of the board. Generally, the number of layers is all even numbers, and includes the two outer layers.
Most motherboards have a structure of 4 to 8 layers, but technically, a PCB with nearly 100 layers can be achieved. Most of the large mainframe computers use very multi-layer motherboards, but since this type of electronic computer can already be replaced by clusters of many ordinary computers, super-multi-layer circuit boards have gradually been out of use. Since the layers in the PCB are tightly combined, it is generally not easy to get the specific number, but if you carefully observe the motherboard. It can still be seen that it is a multi-layer board.
