Observe that, just because you placed power on an internal layer, that doesn’t signify you are able to’t put power somewhere else. You'll be able to still route power with your other signal layers as rails using copper pour, or as thick traces. Meaning DFA is in total effect for https://double-sided-tin-sprayed38260.wizzardsblog.com/31191407/ultrasound-machine-high-level-pcb-circuit-board-fundamentals-explained