Why does the PCB Board Control the Magnetic Flux of the Circuit Board?

When we draw the board, we often hear a sentence to make the circuit as small as possible. As a PCB Company, share with you.

PCB wiring diagram, you can know by using electromagnetic field knowledge, then this board becomes a good antenna, and the circuit board design becomes a mess. The electromagnetic interference generated by the trace is much smaller, which is the idea of minimizing the magnetic flux of the circuit board.

Using a mirror plane is a good choice when designing. It can effectively eliminate the impact of interference from power or ground planes on electronic circuits. The mirror plane refers to the plane that constitutes the return flow, such as the power and ground planes at most levels, but there are also power and power planes that are mirrored, such as RS232 levels. The mirror plane can also be regarded as a differential signal. The differential signal has a good suppression effect on common mode interference. The distance between the mirror planes should be as small as possible. If it is a double-sided or single-sided board, it is a good method to double-sided copper and punch more holes. Generally do not stack two irrelevant power planes together, especially when the voltage difference is relatively large, otherwise the mutual interference of power sources will become serious due to the effect of capacitive coupling. No matter how well the PCB is designed, magnetic and electric fields will always exist, but if the magnetic flux is reduced or eliminated, the EMI will become very small or non-existent.

When designing Prototype PCB, through good routing to reduce the board signal line loop and reduce interference, I have summarized the following methods:

1. Multi-layer board design is based on multi-layer board stacking settings and signal line impedance control. For the top layer, power supply, ground, and bottom layers of the 4-layer board, on the one hand, it greatly solves the problem of electromagnetic interference and improves the reliability of the system; on the other hand, it can increase the routing rate of the wires and reduce the area of the PCB board. The 6-layer board usually adds 2 and 2 signal layers to the 4-layer board. An 8-layer board usually includes a power layer, two ground layers, and five signal layers. For the setting of the layer, there are rich materials on the network, or leave a message to discuss. For impedance control of traces, we usually use SI9000 to design;

2. Keep the clock traces as short as possible and close to the ground. Do not run key signal lines for multilayer boards. Single-sided and double-sided boards can use grounding or protective wiring;

3. For the RF chip or high-frequency chip, the Faraday cage method can be used to shield and ground it, leaving only the input and output and power connection externally;

4. Select appropriate component modules, concentrate the operating frequency in a narrower frequency band, and reduce electromagnetic interference through hardware processing;

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