In order to reduce crosstalk between lines, the line spacing should be large enough. When the line center spacing is not less than 3 times the line width, 70% of the electric fields can be kept from interfering with each other, which is called the 3W rule. If you want to achieve 98% of the electric fields without interfering with each other, you can use a spacing of 10W. ——3W rule
Crosstalk refers to the mutual interference between different networks on the PCB caused by long parallel wiring, mainly due to the distributed capacitance and distributed inductance between parallel lines. The main measures to overcome crosstalk are:
√ Increase the spacing between parallel wiring and follow the 3W rule.
√ Insert grounded isolation wires between parallel lines.
√ Reduce the distance between the wiring layer and the ground plane.
In actual PCB design, the 3W rule cannot fully meet the requirements of avoiding crosstalk.
According to practical experience, if there is no shielded ground wire, the distance between printed signal lines must be greater than 1 cm to effectively prevent crosstalk. Therefore, when routing PCB lines, it is necessary to not only enforce the 3W rule but also perform shielded ground wire wrapping treatment between noise source signals (such as clock traces) and non-noise source signal lines, and between “dirty” lines affected by EFTlB, ESD, etc. and “clean” lines that need protection, to prevent crosstalk.