PCB Tech - PCB circuit board 4 layers or more wiring​

Summary of wiring above 4 layers of high-speed PCB board

1. Connect the wires above 3 points, try to let the wires pass through each point in turn for easy testing, and keep the wire length as short as possible.
2. Try not to put wires between the pins, especially between and around the pins of integrated circuits.

3. The lines between different layers should not be parallel as much as possible, so as not to form actual capacitance.
4. The wiring should be as straight as possible, or a 45-degree broken line, to avoid electromagnetic radiation.
5. The ground wire and power wire should be at least 10-15mil or more (for logic circuits).

6. Try to connect the grounding polylines together to increase the grounding area. Try to be as neat as possible between lines.
7. Pay attention to the uniform discharge of components to facilitate installation, plug-in, and welding operations. The text is arranged in the current character layer, the position is reasonable, pay attention to the orientation, avoid being blocked, and facilitate production.

8. Consider the structure of component placement. The positive and negative poles of SMD 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, 12/20mil pad. The wiring should consider the influence of sink current, etc.

10. Put the functional block components together as much as possible, and the zebra strips and other components near the LCD should not be too close.
11. The vias should be painted with green oil (set to negative double value).

12. It is best not to place pads, excessive air, etc. under the battery holder. The size of PAD and VIL is reasonable.
13. After the wiring is completed, carefully check whether each connection (including NETLABLE) is really connected (lighting method can be used).
14. The oscillating circuit components should be as close to the IC as possible, and the oscillating circuit should be 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.
16. Design process: A: design principle diagram; B: confirm principle; C: check whether the electrical connection is complete; D: check whether all components are encapsulated and whether the size is correct; E: place the components; F: check whether the position of the components is reasonable (can be Print 1:1 picture comparison); G: ground wire and power cord can be laid out first; H: check for flying wires (other layers except the flying wire layer can be turned off); I: optimize the wiring; J: check the integrity of the wiring ; K: Compare the network table to check whether there are any omissions; L: Check the rules, whether there are any wrong marks that should not be made; M: Arrange the text description; N: Add the iconic text description of the board system; O: Comprehensive inspection.

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