It's really tough for your auto router to route extremely dense BGA packages on super small PCBs. for example, I have a PCB which is about the size of a credit card and it has a Microchip IGLOO2 M2GL025 FPGA. I also have two Realtek PHY chips and it's quite different to run the router, even on a 12 layer PCB, even though it could be done manually with 8 layers.
It's really tough for your auto router to route extremely dense BGA packages on super small PCBs. for example, I have a PCB which is about the size of a credit card and it has a Microchip IGLOO2 M2GL025 FPGA. I also have two Realtek PHY chips and it's quite different to run the router, even on a 12 layer PCB, even though it could be done manually with 8 layers.