Process for the manufacture of high quality very low profile copper foil and copper foil produced thereby

Abstract

An electrolytic process for producing copper foil having a low profile surface exhibiting a high peel strength when bonded to a polymeric substrate, which process comprises: (a) preparing an electrolyte comprising a copper sulfate-sulfuric acid solution, containing as addition agents, a low molecular weight water-soluble cellulose ether, a low molecular weight water-soluble polyalkylene glycol ether, a low molecular weight water-soluble polyethylene imine and a water-soluble sulfonated organic sulfur compound; (b) passing an electric current through the electrolyte from a primary anode to a cathode spaced from the primary anode in a first electrodeposition zone under first mass transfer conditions including a first current density to electrodeposit on the cathode a base copper foil having a fine-grained microstructure and a matte surface having micropeaks with a height not greater than about 150 microinches; (c) passing the base foil and electrolyte from the first electrodeposition zone to a second electrodeposition zone; and (d) passing an electric current through the electrolyte from a secondary anode to the cathode spaced from the secondary electrode in the second electrodeposition zone under second mass transfer conditions including a second current density greater than the first current density and which provide a mass transfer poorer than that in the first electrodeposition zone, while introducing into the second electrodeposition zone a supplemental stream of the electrolyte, to electrodeposit on the matte surface micronodules of copper, so as to produce a copper foil having a total matte height not greater than about 200 microinches. The produced foil can be passed directly to a station for applying a barrier layer, a station for applying a stain-proofing layer and a station for applying an adhesion promoter to the foil.

Dependencies are inferred from the claim text.