Letter 10006

Plating Adhesion Problem, Gold/Nickel/Aluminum 

I am having a problem with adhesion of my plating (electrolytic gold on electroless nickel over aluminum 6061). After environmental testing (moisture 85% temp 85 C) there is bubbling. When viewed, it can be seen that the nickel has bubbled off the aluminum. It is interesting because if the part is not gold plated, there are no adhesion problems. It must be something to do with the current applied from the gold plating. I bake my parts for one hour at 320 F after gold plating. This helps a bit but not much. I have tried both cyanide and non-cyanide zincate. I plate the gold at 5 ASF.

Any body have any suggestions?

Thank you very much.

Darwin Running
- Ottawa, Ontario, Canada

If the EN let go from the aluminum, I would question the quality of the zincate step. I am a very strong believer in the use of the alkaline EN strikes. It is excellent for improving adhesion. The ammonia smell is strong tho.

James Watts
- FL

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