What is Copper (Finished Copper) Weight
Copper (finished copper) weight is the weight or thickness of the copper layer that covers one square foot of a PCB after the fabrication process is complete. It determines the conductivity, current-carrying capacity, and overall performance of the PCB.
The copper weight is measured in ounces per square foot (oz/ft2) and serves as an indicator of the overall thickness of the copper layer on a specific layer of the PCB. Different copper weights are available to meet design requirements, with common options ranging from 0.5 oz to 6 oz.
For internal layers, the standard copper weight is often 1 oz, which translates to a thickness of approximately 35µm or 1.4 mils. This weight is suitable for PCBs with a 1 oz or 2 oz finished copper weight selection. In contrast, for PCBs with a 3 oz finished copper weight selection, the standard internal layer copper thickness is 2 oz, equivalent to approximately 70µm or 2.8 mils.
Non-standard stackups can accommodate multiple copper weights in a multilayer build. Therefore, when specifying copper weight requirements for a PCB, it is recommended to include a “Read Me” or stack-up with the desired copper weight per layer.