# PCB layer copper thickness calculation

In a 4 layer PCB, the outer layers 1 and 4 have 1 oz copper thickness and inner layers 2 and 3 have 0.5 oz copper thickness.

For example, if I allocate a VCC voltage to 3rd and 4th layer, can I say the copper thickness makes 1.5 oz. for pcb current vs heat calculation. (The question is theoretical not PCB design specific)

• If this is for resistance/voltage-drop calculations then yes. Nov 23, 2017 at 23:21
• Keep in mind your Gnd needs to be just low resistance as Vcc. Nov 23, 2017 at 23:22
• I am wondering this for pcb current calculation. 2 oz 4 layer pcb are expensive so if i allocate more layer to high current will they add up in thickness. Also yes same consideration is given to both VCC and Gnd but just wrote the VCC as example. Nov 23, 2017 at 23:23
• Don't forget about heat dissipation for internal layers which is much worse. Don't know how much current you are talking about but.. you should probably keep that in mind. Nov 23, 2017 at 23:24
• Yes i learned that the outer layer is important for heat dissipation. Thank you. But also i do not have much to do rather that allocating as much as copper area possible. Current is 10-15A average and some peaks to 30-40A for a few seconds. Nov 23, 2017 at 23:28