You should understand the basic knowledge and basic functions of copper paving in PCB

by:A-TECH      2021-03-28
Why should copper be laid? There are generally several reasons for copper laying. 1. EMC. For large area ground or power supply copper, it will play a shielding role, and some special grounds, such as PGND, play a protective role. 2. PCB process requirements. Generally, in order to ensure the electroplating effect, or the lamination is not deformed, copper is laid on the PCB layer with less wiring. 3. The signal integrity requirements provide a complete return path for high-frequency digital signals and reduce the wiring of the DC network. Of course, there are also reasons such as heat dissipation, special device installation requires copper and so on. One. One of the major benefits of copper paving 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 spike currents in digital circuits, so it is more necessary to reduce the ground wire impedance. It is generally believed that a large area of u200bu200bground should be laid for circuits composed of digital devices, while for analog circuits, the ground loop formed by laying copper will cause electromagnetic coupling interference to outweigh the gains (except for high-frequency circuits). Therefore, it is not that a circuit needs to be copper-plated (BTW: mesh copper paving is better than a whole block paving performance) 2. The significance of circuit copper paving is: 1. The copper paving is connected to the ground wire, which can reduce Loop area 2. A large area of u200bu200bcopper is equivalent to reducing the resistance of the ground wire and reducing the voltage drop. From these two points, whether it is a digital ground or an analog ground, copper should be laid to increase the anti-interference ability, and At high frequencies, the digital ground and the analog ground should be separated to lay the copper, and then connected with a single point. The single point can be wound several times on a magnetic ring with a wire, 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 counted as a high-frequency emission source in the circuit. You can spread copper around and ground the shell of the crystal oscillator, which will be better. 3. What is the difference between a copper block and a grid? To analyze in detail, there are probably three functions: 1 beautiful, 2 noise suppression, 3 to reduce high-frequency interference
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