The invention provides a routing fan-out structure of a back-to-back connector, a
printed circuit board and a switch, and relates to the technical field of circuit board design. The wiring fan-out structure comprises a plurality of high-speed differential
signal hole pairs which are arranged in the direction perpendicular to the arrangement direction of the connector pins, the wiring difficulty is reduced, and the
signal integrity is improved. A first high-speed differential
signal hole pair in the plurality of high-speed differential signal hole pairs is used for fan-out of a first high-speed
differential line corresponding to a bottom-layer connector, and a second high-speed differential signal hole pair is used for fan-out of a second high-speed
differential line corresponding to a top-layer connector. Wherein the first high-speed
differential line does not coincide with the second high-speed differential signal hole pair, the second high-speed differential line does not coincide with the first high-speed differential signal hole pair, the non-
coincidence design lays a foundation for adopting a
through hole technology, the manufacturing cost of a PCB is reduced, in addition, electrical
short circuit is avoided when the high-speed differential signal holes are manufactured, and safe and reliable fan-out is achieved. And the
printed circuit board is manufactured through one-time pressing, so that the manufacturing cost of the PCB is further reduced.