How to optimize the return flow of copper plating in the I/O module ground plane?

Optimizing the copper plating of the I/O module PCB ground plane to control the return current path is key to improving EMC. The ground plane should be as complete and continuous as possible, avoiding long, narrow gaps created by signal lines. When a signal line must be moved to a different layer, place a ground via near its via to provide the nearest return path for the return current. For high-speed signal lines, ensure there is a continuous ground plane underneath them, and keep the line width and distance to the ground plane constant to control impedance.

In mixed-signal designs, digital ground and analog ground can be separated, but no other traces should cross the gap between them; they should be connected via ferrite beads or single points. A dense array of ground vias should be placed around the board edges and connectors to form a "ground wall" and suppress edge radiation. When plating copper, avoid creating isolated copper islands; connect them to the main ground plane via vias. For high-current areas, the ground copper should be thickened or have windows to allow for later soldering. Simulation tools can be used to visualize and analyze the return current path, ensuring that the high-frequency return loop area is minimized.