Double-coating and porous treatments and evaluation of rolled copper foil surface

Brush plating technology was employed to directly achieve double coatings of Zn-Ni alloy and Sn-Zn alloy on the surface of rolled copper foil. Dealloying technology was applied to implement porous surface. Surface morphology, roughness, chemical composition, corrosion resistance and interfacial bonding strength of copper foil and double coatings were characterized. For the Zn-Ni alloy coating formed by brush plating at a voltage of 10-14 V, the corrosion resistance was favorable and the surface roughness was about 200 nm. For the brush plating Sn-Zn alloy coating, the surface roughness was about 500 nm. Little diffusion of alloy elements occurred at the interface of two coatings. The brush plating Zn-Ni alloy coating is an effective barrier to copper element diffusion and the brush plating Sn-Zn alloy coating is in capacity of anti-oxidation passivation. The tensile bonding strength between the above two coatings surpassed 32 MPa. The surface roughness of the dealloyed Sn-Zn alloy coating was uniform and could maximally reach to about 3 μm. The peel strength of rolled copper foil combined with resin board was about 1.1 N/mm, which exceeded the current standard of 0.8 N/mm. It is feasible to introduce brush plating and dealloying technologies into the surface treatment of rolled copper foil. A new compact and efficient surface treatment technology for the high performance rolled copper foil is excepted to be developed.