SURFACE TREATMENT OF COPPER

PURPOSE:To provide a method of treating a copper surface to form a uniform layer capable of reliable adhesion to resin. CONSTITUTION:A copper surface is treated by oxidation, reduction and nickel plating to enhance its adhesion to resin and prevent haloing. The individual treatment steps are controlled while the potential of the copper surface is monitored. Each step is finished when the surface potential reaches a predetermined level. To this end, a potentiometer 10 is provided for each bath 11 so that it may be connected between a substrate 9 and an electrode 13 when the substrate is immersed in the bath containing a solution 12. This arrangement enables control of different conditions of chemical solution for different treatments by monitoring the respective surface potentials during oxidation, reduction and plating. Therefore, it is possible to carried out uniform treatment of a copper surface.