Idea: Each individual copper layer is assumed to hold the identical completed copper fat Except or else laid out in your fabrication notes. A 4-layer board with a defined excess weight of 1oz, is assumed to have a concluded copper thickness of 1.37mils (or even more) on each copper layer. https://metalpcbcopperbasedboard06159.ourcodeblog.com/31371762/considerations-to-know-about-6-layer-one-stage-led-small-pitch-display-pcb-board