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What are the precautions for the wiring of PCB four-layer boards

Release Time: 2021/5/18 20:16:17

PCB is divided into single-layer board and multi-layer board. Today, taking PCB four-layer board as an example, I will briefly introduce the related matters that should be paid attention to when wiring the multi-layer board:


1. When designing the connection of more than 3 points, let the line pass through each point in a regular manner to facilitate the later test, and the line length should be shortened as much as possible.


2. Avoid arranging wiring around the pins, and pay special attention to reducing the design of wiring between and around the pins of the integrated circuit.


3. Adjacent layers should not be wired in parallel. For example, 8 address buses and 8 data buses are ok to be pulled out in parallel on the same layer. In theory, there will be interference as long as the lines are parallel, but it does not mean that it is impossible. Work effectively.


4. Minimize bending and bending wiring to avoid electromagnetic radiation.


5. For multi-logic circuits, at least 10-15 mils or more when designing ground wires and power wires.


6. Try to connect the ground multi-segment lines to increase the grounding area. Lines should be kept neatly between lines.


7. In the early stage of wiring, the space for the later components should be reserved evenly to facilitate the installation, plug-in, and welding operations of the later components. The text is arranged in the current character layer, the position is reasonable, pay attention to the orientation, and avoid being blocked, which is convenient for processing and production.


8. The installation of the component row should be based on the sense of space. The positive and negative poles of the SMT components should be marked at the package and at the end to avoid space conflicts.


9. At present, the printed circuit board can be used for 4-5mil wiring, but it is usually 6mil line width, 8mil line spacing, and 12/20mil pad. The influence of multiple factors such as sink current should be considered when wiring.


10. Put the functional block components together as much as possible to facilitate later inspection. Special reminder: Do not get close to LCD components such as zebra strips.


11. The vias should be painted with green oil (set to negative double value).


12. It is best not to place pads, over-empty, etc. under the battery base to ensure the firmness of repeated use, and the size of PAD and VIL are reasonable.


13. Checking requires care: After wiring is completed, carefully check whether each connection (including NETLABLE) is really connected (lighting method can be used).


14. The oscillating circuit components are as close as possible to the IC chip, and the oscillating circuit is as far away as possible from the antenna and other vulnerable areas. Place a ground pad under the crystal oscillator.


15. Consider more methods such as reinforcement and hollowing out components to avoid excessive radiation sources.


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