There are several reasons for general copper laying.

1. EMC. Copper laying on a large area of ground or power supply will play a shielding role. In some special cases, such as PGND, it plays a protective role.

2. PCB process requirements. Generally, in order to ensure the electroplating effect or the lamination does not deform, copper is laid on the PCB layer with less wiring.

3. Signal integrity requirements, give a complete return path to high-frequency digital signals, and reduce the wiring of DC network. Of course, there are heat dissipation, special device installation requirements, copper laying and so on.

1、 One of the great advantages of copper laying is to reduce the ground wire impedance (a large part of the so-called anti-interference is also caused by the reduction of ground wire impedance). There are a large number of peak pulse currents in digital circuits, so it is more necessary to reduce the ground wire impedance. It is generally believed that the circuit composed of all digital devices should be laid on a large area, while for analog circuits, The ground wire loop formed by copper laying will cause electromagnetic coupling interference, which is not worth the loss (except for high-frequency circuits). Therefore, not all circuits need ordinary copper (btw: the performance of mesh copper laying is better than that of the whole block).

What is the significance of laying copper on PCB

2、 Significance of laying copper on circuit

1. Copper laying is connected with the ground wire, which can reduce the loop area.

2. Laying copper on a large area is equivalent to reducing the resistance of the ground wire and reducing the voltage drop. From these two points, copper should be laid on both digital and analog ground to increase the anti-interference ability. Moreover, at high frequency, copper should be laid on digital and analog ground separately, and then connected with a single point. The single point can be wound on a magnetic ring with a conductor for several turns, 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. The crystal oscillator can be regarded as a high-frequency emission source in the circuit. You can lay copper around and then ground the shell of the crystal oscillator, which will be better.

3、 What is the difference between the whole copper block and the grid?

Specifically, there are about three functions: 1. Beauty, 2. Noise suppression, 3. In order to reduce high-frequency interference (for reasons on the circuit board), according to the routing criteria: the power supply and the stratum should be as wide as possible. Why should a grid be added? Isn’t it inconsistent with the principle? From the perspective of high frequency, it is even more wrong. The most taboo in high frequency wiring is sharp wiring. There are many problems if there are n more than 90 degrees in the power layer. In fact, why do you do that is entirely the requirement of the process: see if the manual welding has such painting, almost none; If you see a picture like this, there must be a watch chip on it. At that time, because there was a process called wave soldering when pasting the chip, he had to heat the plate locally. If the specific heat coefficient of the two sides was different, the plate would curl up, and the problem would arise as soon as the plate curled up, and the steel cover was put on (also the need of the process) The pin of the chip is easy to make mistakes, and the scrap rate goes straight up. In fact, this method also has disadvantages: under our current corrosion process, the film is easy to stick to it. In this case, in the later strong acid project, that point may not corrode and there are a lot of waste products, but only if the board is broken, and the chip and the board are finished together! From this point of view, do you understand why you draw like that? Of course, some tables are pasted without grid. From the perspective of product consistency, there may be two situations: 1. His corrosion process is very good; 2. Instead of wave soldering, he uses more advanced reflow soldering, but in this way, the investment of the whole assembly line will be 3-5 times higher.

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