Copper Plating on Zinc Alloy

Ask an Expert From: Products Finishing, ,

Posted on: 4/1/2004

Question: We have a customer who wants our company to copper plate on a zinc alloy (Zamak 3) substrate.

Question:

We have a customer who wants our company to copper plate on a zinc alloy (Zamak 3) substrate. We currently cyanide copper plate on steel. What is the process for doing this? P.H.

Answer:

Actually, the plating of zinc alloys is fairly straightforward. Since you are currently using cyanide-based copper plating baths, you are familiar with one of the plating baths required. A standard process for plating copper on zinc alloys is as follows:

  • Degrease the part
  • Electroclean cathodically (direct or forward)
  • Rinse thoroughly
  • Dip in a five ml in one liter sulfuric acid solution for 30 sec or until gassing begins
  • Rinse thoroughly
  • Place parts in a cyanide copper strike bath. The parts must be placed in the strike bath "live." (Current must be on when the rack is placed in the plating tank.)
  • Plate at a CD of 25-30 asf for two min. Reduce the current to 10-15 asf and plate for an additional 4-5 min
  • Rinse thoroughly
  • Dip in a 10 ml/l sulfuric acid solution
  • Plate in copper sulfate bath to the desired thickness

I should also add that a number of proprietary non-cyanide alkaline copper plating baths are commercially available. They work well in many applications and allow you to get away from using cyanide-based materials. Vendors of these baths can be found in the Products Finishing Directory and Guidebook, 2004 edition, www.pfonline.com/suppliers.html.

 



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