2 layer PCB: copper and dielectric order2 layer PCB: copper and dielectric orderL1 — copperOne substrate dielectricMaterial + dielectric thickness to specifyL2 — copperWHAT THE COUNT MEANS2 conductive copper facesNo interlayer PP bondCopper counted separatelyfrom substrate dielectric.Define material and finish.Then define:signal / ground / power rolesand each dielectric thickness.Engineering illustration, not to scale. Reference geometry is not a released manufacturing stackup.