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Easily learn PCB design specifications

As a PCB engineer with a strong personality and pursuit, how can I draw a neat, efficient and reliable PCB diagram?

The design of PCB seems to be complicated. It is necessary to consider the direction of various signals and the transmission of energy. The distress caused by interference and heat is always accompanied. In fact, as long as the PCB design specifications are summarized, it will be very clear. To put it bluntly, it is a matter of "how to display" and "how to connect".

how to pose

1. Follow the layout principle of "big first, then small, difficult first, easy first", that is, important unit circuits and core components should be laid out first. This is the same as eating a buffet: buffets have a limited appetite and pick the ones you like first, and when PCB space is limited, pick the important ones first.

First big and then small, first difficult and then easy

2. The heating elements should generally be evenly distributed to facilitate the heat dissipation of the veneer and the whole machine. Temperature sensitive devices other than the temperature detection element should be kept away from the components that generate large amounts of heat.

3. The arrangement of components should be convenient for debugging and maintenance, that is, large components cannot be placed around small components, and there must be enough space around components that need to be debugged. It will often become very embarrassing if it is too crowded.

The heating components are evenly distributed

4. The principle block diagram should be referred to in the layout, and the main components should be arranged according to the main signal flow law of the single board. The layout should meet the following requirements as much as possible: the total wiring should be as short as possible, and the key signal line should be the shortest; the layout of the decoupling capacitor should be as close as possible to the power supply pin of the IC, and the loop formed between it and the power supply and ground should be the shortest; reduce the signal Run unjustly to prevent accidents on the road.

5. For the circuit parts of the same structure, use the "symmetrical" standard layout as much as possible; optimize the layout according to the standards of uniform distribution, balanced center of gravity, and beautiful layout.

6. The same type of plug-in components should be placed in one direction in the X or Y direction. The same type of polarized discrete components should also strive to be consistent in the X or Y direction to facilitate production and inspection.

7. High voltage and large current signals are completely separated from small current and low voltage weak signals; analog signals are separated from digital signals; high-frequency signals are separated from low-frequency signals; the spacing of high-frequency components should be sufficient. In the component layout, appropriate consideration should be given to placing the devices using the same power supply as close together as possible to facilitate future power supply separation.

how to connect

"How to arrange" is the main consideration for the layout, while "how to connect" is relatively more complicated, generally speaking:

1. Rule priority: If there are rules, the signal lines required by the rules will be arranged first, and then the non-critical signal lines will be arranged;

2. Priority of key signal lines: Priority wiring of key signals such as power supply, analog signal, high-speed signal, clock signal, differential signal and synchronization signal;

3. Density priority: Start wiring from the most complicated device on the board, and start wiring from the densest area on the board.

PCB layout example

Smart people are good at simplification of complex things, have you learned "how to put" and "how to connect", PCB design specifications are soeasy!

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