What is PCB guidelines?
PCB layout best practices recommend that you always keep traces as shortand directas possible between components. If your component placement forces horizontal trace routing on one side of the board, then always route traces vertically on the opposite side.
How to reduce EMI in PCBs?
If you have any bypass or decoupling capacitors in your PCB design, connecting them directly to the ground plane will help reduce EMI. Grounding these capacitors quickly ensures that return currents have a very short path to complete their loop.