Idea: Every single copper layer is assumed to have the exact same concluded copper body weight Except otherwise specified in your fabrication notes. A 4-layer board with a defined excess weight of 1oz, is assumed to have a completed copper thickness of one.37mils (or more) on every copper layer. PCBs https://16-layer3-levelhdipcb73715.izrablog.com/31779209/examine-this-report-on-8-layer-first-order-pcb