The placement of the filter capacitor under the BGA: Although it is very simple, there are many things that are connected. I hope it helps you to understand.
Understand the general function of each bank in order to place the filter capacitor reasonably;
When designing, we generally ensure that the ground pin is first, the path is short, and the filtering effect is good. Such as:
The peripheral small circuits of BGA are as neat and beautiful as possible. The holes and lines are unified. Such as:
The beautiful circuit board comes from every detail of you, so you can't miss any detail!