What role does copper play in circuit boards?
PCB manufacturers take you to know that there are several reasons for PCB copper laying:
1. EMC can shield large area of ground or power supply copper, and some special areas, such as PGND, play a protective role.
2. PCB process requirements. Generally, in order to ensure the plating effect, or the lamination pressure is not deformed, the PCB board with less wiring is coated with copper.
3. The requirement of signal integrity is to provide a complete backflow path for high frequency digital signals and reduce the wiring of DC network. Of course, there are also heat dissipation, special device installation requirements for copper and other reasons.
一、A great advantage of copper laying is to reduce the ground wire impedance of Jiangmen single-sided and double-sided circuit boards (the so-called anti-interference is also caused by the reduction of ground wire impedance). There are a large number of spike pulse currents in digital circuits. Therefore, it is more necessary to reduce ground wire impedance. It is generally believed that the circuit composed of all digital devices should have a large area. For analog circuits, the ground loop formed by copper paving will lead to electromagnetic coupling interference (except for high frequency circuits). Therefore, it is not a circuit that needs copper (BTW: net copper paving is better than the whole block paving).
二、The significance of copper-laying in circuit lies in: 1. Copper-laying is connected with ground wire, which can reduce the area of circuit 2. Copper-laying in large area is equivalent to reducing the resistance of ground wire and reducing the voltage drop. From these two points, whether digital or analog, copper-laying should be used to increase the anti-interference ability, and at high frequencies, it should also be used to reduce the resistance of ground wire. Copper is digitally and analogically separated and then connected by a single point, which can be wired around a magnetic ring several times and then connected. However, if the frequency is not too high, or the working conditions of the instrument are not bad, it can be relatively relaxed. Crystal oscillator in the circuit can be calculated as a high-frequency emitter, you can lay copper around, and then the shell of the crystal oscillator grounded, so it will be better.
三、The Difference between Copper Paving Block and Grid of Jiangmen Single-sided and Double-sided Circuit Board
Specifically, there are about three functions: 1. Beauty 2. Noise suppression 3. In order to reduce high-frequency interference (in the circuit version of the reason)
According to the routing criteria: power supply and formation as wide as possible, why do we need to add grid ah is not in line with the principle? If viewed from the perspective of high frequency, it is even more wrong that the most taboo in high frequency wiring is the sharp wiring. If there are more than 90 degrees in the power layer, there are many problems. In fact, why did it do that is entirely a process requirement: to see if there is such a manual welding painting, almost no; you see that there must be a chip on it when you see such painting, because there is a process called wave soldering when patching, he needs to heat the plate locally, if fully copper-coated, the specific heat coefficient of the two sides is different. The problem of plate warping is that the pin on the chip is easy to make mistakes and the rejection rate goes straight up in the upper steel cover (which is also the need of the process). In fact, this method has its drawbacks: in our current corrosion process, Filin is easy to stick to it, so in the later strong acid engineering, Filin is easy to stick to it. That point may not corrode, and there are a lot of waste, but only if the board is broken and the chip is broken with the board.
Of course, there are also some tables without grid. From the point of view of product consistency, there may be two situations: 1. Corrosion process is good; 2. Instead of wave soldering, higher reflow soldering is adopted, but in this case, the investment of the whole pipeline will increase by 3-5 times.
The article originated from Jiangmen single-sided and double-sided circuit boards. http://www.yonghongpcb.com