Highway overpasses are very common. But if an overpass is built on a railway, it is limited by the slope of the slope, which leads to a large amount of earthwork excavation and high construction and maintenance costs. Therefore, the common intersection of two railways is on the same plane:

　　This phenomenon also occurs on PCBs. If the signal through hole size, line width, and line spacing are not limited, theoretically, a double-sided board can accommodate any complex circuit.

　　However, due to cost considerations, consumer electronics products in the last century were mostly single panel, and there were always situations where they could not be connected. Therefore, they flew over using a stapled jumper:

　　When designing a PCB for the same circuit diagram, the number of jumpers becomes an important indicator to measure the level of layout.

　　This type of stapled jumper can only cross through DC or low-frequency signals.

　　What if there is an RF signal that cannot be laid on the double-sided board?

　　The RF double-sided board must have a complete ground plane with only one layer of wiring left, and the wiring difficulty is equivalent to a single panel!

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