PCB Tech - How to distinguish PCB layers

With the rapid development of integrated circuit technology, the number of layers of circuit board has also developed from the original single and double-layer boards to more than ten layers or even higher. Therefore, it is difficult for many people to distinguish the number of PCB layers. When the number of layers is more, the more difficult it is to distinguish the number of PCB layers. Therefore, it is necessary for circuit board practitioners to master a fast method to distinguish the number of PCB layers.

The substrate of the circuit board itself is made of insulating and non bending materials. The small circuit material that can be seen on the surface is copper foil. Originally, the copper foil was covered on the whole circuit board, but part of it was etched during the manufacturing process, and the remaining part became a network of small wires. These circuits are called wires, or wiring, and are used to provide circuit connections to parts on a circuit board. Usually the color of the circuit board is green or brown, which is the color of solder mask. It is an insulating protective layer, which can protect copper wire and prevent parts from being welded to the wrong place. Now the motherboard and graphics card are using multilayer board, greatly increasing the area of wiring. Multilayer boards use more single or double-sided wiring boards, and a layer of insulation is placed between each layer and then pressed together.

The number of layers of PCB board represents several independent wiring layers. Usually, the number of layers is even and contains the two outermost layers. The common PCB board is generally 4-8 layers in structure. Many layers of PCB can be distinguished by viewing the section of PCB. But in fact, no one has such a good eye. So, let's teach you a way to distinguish the number of PCB layers.

The circuit connection of multi-layer board is through buried hole and blind hole technology. The main board and display card mostly use 4-layer PCB, and some use 6-layer, 8-layer or even 10-layer PCB. If you want to distinguish the number of PCB layers, you can identify them by observing the pilot holes, because the 4-layer boards used on the motherboard and display card are the wiring of layers 1 and 4, and the other layers have other uses (ground wire and power supply). Therefore, as with the double-layer board, the pilot hole will punch through the PCB board. If some pilot holes appear on the front of the PCB but can't be found on the reverse side, it must be a 6 / 8-layer board. If the same pilot hole can be found on both sides of PCB , it will be a 4-layer PCB. On the other hand, if the PCB is facing the light source, it means that it can distinguish the position of the light source board.