A 6 / 2 / 2 / 6 oz stackup has 0.56 mm nominal copperA 6 / 2 / 2 / 6 oz stackup has 0.56 mm nominal copperL1 6 oz ≈ 0.210 mmDielectric spacing: agree after pressingL2 2 oz ≈ 0.070 mmCore dielectric: separate dimensionL3 2 oz ≈ 0.070 mmDielectric spacing: agree after pressingL4 6 oz ≈ 0.210 mmEngineering illustration · Not to scale · Example values are not product ratings