What is Copper Foil
Copper foil is a thin sheet of high-purity copper that is used as a conductor in the manufacturing of PCBs. It serves as the foundation for the circuitry and is an essential component in the PCB fabrication process.
Copper foil can be applied in different ways. It can be pre-attached by the laminate manufacturer to a base material core or introduced as copper foil before pressing in a multi-layer board. The thickness of the copper foil is an important parameter and can vary based on the specific application and design requirements of the PCB. It is typically measured in micrometers (µm).
On the inner layers of the PCB, the final copper thickness remains the same as that of the base copper foil. However, on the outer layers, an additional copper deposition is applied during the galvanic process for plating through the holes. This additional copper deposition, typically 20-30µm, ensures proper conductivity and connectivity between the different layers of the PCB.
For single-layer PCBs and IMS (Insulated Metal Substrate) boards, the galvanic plating process is not involved, and therefore, the additional copper deposition is not applicable.