Electroless nickel on copper

A. Hi, Gabriel.

Copper is not catalytic for electroless nickel, so you need to apply current for a couple of seconds to seed the process. Then remove the power and it should plate fine. Good luck.

Regards,

A. Hi Gabriel,

Besides electrolytic start-up, you may apply catalyst (normally is palladium type, either H2SO4 or HCl base, 50-100 ppm Pd, immersion time 1-3 mins) before EN. Process flow as below:

Cleaner --> Rinses --> Mild Etch --> Rinses --> Predip --> Catalyst --> Postdip --> Rinses --> EN --> Rinses

Regards,
David

Dear Gabriel,

Please share the outcome of your trials and your experience on this forum. It will help others.

Good luck

A. Thomas,
Pd is much more noble than Cu. If my memory is correct, Cu has a potential of .337V, Pd is .987V. For galvanic corrosion to take place, (Cu giving way to the Pd) dissimilar metals of nobility must be used. Pd and Ru are common catalysts used for Electroless Nickel on Cu for this reason.

Q. Mark.

Thank you for your answer. I can understand why Pd is depositing on Cu. It is a replacement reaction related to the galvanic series as you mentioned (less noble material is replaced by more noble material until the whole surface is covered by the noble material - self limiting process). However, I can still not understand why the Ni is depositing on Pd but not on Cu (galvanic series is not the reason since Ni is less noble than Pd - the deposition mechanism is different as well - autocatalytic vs. replacement). So my question unfortunately remains - why is Pd catalytic for Ni and why is Cu not catalytic for Ni?

Thank you for your help,

Thomas.

A. Hello Thomas,
Sorry my answer was off-path a bit. Cu will not catalytically initiate hypophosphite, when employed as the reducing agent in EN solutions. Cu can initiate when aminoborane and borohydride reducing agents are used however. Hope this helps.

Q. Mark,

Thank you again for your answer. OK - copper is catalytically active for aminoborane and borohydride nickel. Still I do not understand why Cu will not catalytically initiate eg. hypophosphite nickel, but Pd does? What is the exact criteria for a surface to be catalytically active or not. There must be a (chemical) reason/theory/explanation when and why a surface A is (or is not) catalytic for a autocatalytic deposition of material B?

A. Hi, Thomas. I think Mark has answered as best he can, and I can't improve upon it. But based on his informative answer, I would suggest that perhaps it's not the nickel (material B) that you should be looking towards, but the hypophosphite? That is, I think the question may be "why do Pd, Fe, &Ni -- but not Cu -- trigger the oxidation of hypophosphite"?

Regards,

A. Ted,
Thank you for your comment on the E-Less Ni questions from Tom. I believe it's the difference in the activity of the metals when it comes into contact with hypophosphite. Our shop plates EN but I am by no means an expert. I've been in this business for over 30 years and still have questions from our suppliers. I wish some of our employees would ask the WHY question more often. Thanks again.....

A. By copper, I assume that you are talking about a high copper content alloy.
You might have better luck with bronze for a braze. Personally, for 316, I would TIG weld it with 316L rod.

Orbital welders do a fantastic hob on tubes. They will not work on horizontal tube to vertical header. That will require hand welding or CNC welding.

A. Hi Sonali. I've never heard of it myself.

If there was anything I never wanted to be, it was a dentist :-)
Please tell us the situation behind your question. Thanks.

Regards,