PCB copper processing experience

The copper cladding uses the unused space on the PCB as the reference surface and is then filled with solid copper, also known as copper fill. The significance of the copper cladding is to reduce the ground impedance, improve the anti-interference ability; reduce the voltage drop, improve the power efficiency; and connect with the ground to reduce the loop area.

If the PCB has more grounding, there are SGND, AGND, GND, etc. How to cover copper? My approach is to separate copper from the location of the PCB surface, using the most important "grounding" as a reference, and separating the digital ground from the analog ground to apply copper.

At the same time, before covering the copper wire, first increase the corresponding power connection: V5.0V, V3.6V, V3.3V (SD card power supply) and so on. In this way, a plurality of multi-deformed structures of different shapes are formed.

The copper cladding needs to solve several problems:

1. Single point connection in different places;

2. Copper near the crystal oscillator, the crystal oscillator in the circuit is a high frequency emission source. The method is to apply copper to the surrounding crystal oscillator and then ground the crystal case separately.

3, the problem of the island (dead zone), if you think it is very big, then defining a place to add holes is not too much.

In addition, large areas of copper are good or the grid is copper, which is not easy to promote. why? Large area of copper, if wave soldering, the board may be upturned or even foamed. From this perspective, the cooling effect of the grid is better. Generally, high frequency circuits are used to resist interference from a multi-purpose power grid, and low frequency circuits have large current circuits and the like.

In digital circuits, especially in circuits with MCUs, circuits operating at frequencies above mega is used to reduce the impedance of the entire ground plane. More specific processing methods I generally operate in this way: each core module (also digital circuit) will also split the copper wire when allowed, and then connect each copper wire with a wire, the purpose of this is also to reduce the circuit between The impact is at each stage.

For the circuit mixed with the digital circuit analog circuit, the independent trace of the ground line, and the summary of the final power supply filter capacitor are not mentioned, we all know. However, there is one point: in many cases, the ground line distribution in the analog circuit cannot be simply applied to a piece of copper, because the analog circuit focuses on the interaction between the front and the rear, and the analog ground also requires a single point of grounding, so it can be based on the actual situation. A simulation application for handling copper skin.