11. The design of PCB (multiple layer board)--Basic requirement of designing multiple layer PCB VOL3
Requirements of power layer, stratigraphic partition and flow-hole:
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For PCB multilayer, there is at least one power layer and one layer.
Because of all the voltage on the PCB are in the same power level, so you have to partition the isolation of power supply layer, the size of the partition line generally USES 20 ~ 80 mil line width advisable, ultra-high voltage, the more coarse partition line.
In order to increase the reliability of the welding hole and the power supply layer and the stratigraphic connection, it is necessary to design the shape of the flower hole to reduce the large area metal heat absorption in the welding process
The aperture of the isolation pad is greater than that of borehole aperture +20mil
Requirements for safe spacing
The setting of safety spacing should meet the requirements of electrical safety.
Generally speaking, the minimum spacing of the outer conductor shall not be less than 4mil, and the minimum spacing of the inner wire shall not be less than 4mil.
When the wiring can be arranged, the spacing should be as large as possible to increase the yield of the plate and reduce the trouble of the finished plate failure.
Improve the anti-interference ability of the whole plate
The design of PCB multilayer board also has to pay attention to the anti-interference ability of the whole plate. The general methods are:
The filter capacitance is added to the power source of each IC, and the capacity is usually 473 or 104.
For sensitive signals on the printed board, the companion shielding wire should be added separately, and the signal source should be as little cabling as possible.
Choose a reasonable location.