US Patent 7153590 Composite copper foil and manufacturing method thereof

A composite copper foil (10) comprises a carrier foil (12) formed by electrodeposition onto a cathode, the carrier foil (12) having a cathode side formed in contact with the cathode and an opposite electrolyte side. A very thin release layer (14) is on the electrolyte side of said carrier foil (12). A thin functional foil (16) formed by deposition of copper has a front side in contact with the release layer (14) and an opposite back side. The electrolyte side of the carrier foil (12) has a surface roughness Rz less than or equal to 3.5 μm. There is also presented a method for manufacturing such a composite copper foil.