| abstract |
The present invention provides a method for forming a heat-treated conductive film on a passivation-forming light metal, which is a conductive film formed of a silver, copper, tin or the like via a base film on a passively formed light metal selected from the group consisting of aluminum, magnesium and titanium. The base film is a nickel-phosphorus film, and the base film is formed by using a nickel-phosphorus plating bath containing a prescribed soluble nickel salt, a phosphorus-containing compound, a complexing agent, a surfactant, a buffer, and a brightener, and The base film, or the base film and the conductive film are heat-treated under conditions including a low temperature range of 30 ° C or higher, and the adhesion of the base film to the passive formable light metal can be strengthened as compared with the method without heat treatment, in a passive state. The forming light metal is more firmly adhered to form a conductive film. |