PCB design rules
Rule of line spacing: In order to reduce the crosstalk between lines, ensure that the line spacing is large enough. When the distance between line centers is not less than 3 times the line width, 70% electric fields can be kept from interfering with each other; When the spacing of 10 times the line width is used, 98% of the electric fields can not interfere with each other.
Edge effect solution rule: the change of electric field between power supply layer and stratum will radiate electromagnetic interference at the edge of the plate. The solution is to shrink the power layer so that the electric field is only conducted within the scope of the ground layer.
Selection rules of PCB layers: when the clock frequency reaches 5MHz or the pulse rise time is less than 5ns, PCB should adopt multi-layer boards. Considering the cost and other factors, when adopting the double-layer board structure, it is best to regard one side of the printed board as a complete ground plane.
Rule of ground wire loop: the loop area formed by signal wire and its loop should be as small as possible to reduce external radiation and receive external interference. When dividing the ground plane, the distribution of the ground plane and the important signal traces should be considered.
Crosstalk control rules: the crosstalk problem can be overcome by increasing the spacing of parallel wiring, inserting grounded isolation wires between parallel lines, and adopting the shielding structure design of copper axis cable.
