Effects of nodule treatment of rolled copper on the mechanical properties of the flexible copper-clad laminate

Rolled copper foil of 18 μm thickness underwent nodule treatment via electro plating in a solution containing dissolved CuSO4 and NiSO4. The product formed on the surface of the copper foil varied from copper oxides to nickel compounds of the sphere type with increasing current density and plating time. The highest surface roughness and maximum peel strength of 680 gf/cm were obtained with the formation of nickel compounds at a current density of 1.5 A/dm2 and plating time of 30 s. In addition, the fracture location varied according to the plating parameters and occurred at the interface between the polyimide film and adhesive layer at the condition of the maximum adhesion strength.