Note that, Simply because you placed power on an internal layer, that doesn’t indicate you may’t put power elsewhere. You could nonetheless route power on the other signal layers as rails employing copper pour, or as thick traces. In short, the four-layer board has an inner layer. Concerning the process, https://double-sidedimmersiongold95937.blog-gold.com/38742583/facts-about-four-layer-tin-spraying-module-power-pcb-revealed