Electroplating Method and Electroplated Product

A method for electroplating a substrate having an aluminum alloy surface comprising:

• applying a zinc layer onto the aluminum alloy surface;
• electroplating a first copper layer onto the zinc layer from an alkaline copper electroplating solution, wherein the alkaline copper solution is substantially free of cyanide ion;
• electroplating a second copper layer onto the first copper layer from an acid copper electroplating solution;
• applying an activating solution onto the second copper layer;
• electroplating a Cu—Sn alloy layer onto the second copper layer from a Cu—Sn electroplating solution;
• and
• electroplating a chromium layer onto the Cu—Sn alloy layer from a trivalent chromium solution.

An electroplated product comprising:

• a substrate having an aluminum alloy surface;
• a zinc layer on the aluminum alloy surface;
• a copper layer on the zinc layer, wherein the copper layer is formed by electroplating from an alkaline copper electroplating solution, and wherein the alkaline copper electroplating solution is substantially free of cyanide ion;
• a Cu—Sn alloy layer on the copper layer;
• and
• a chromium layer on Cu—Sn alloy layer;
• wherein the electroplated layers are substantially free of nickel.