[mehulmatrix]

Hello All,
Im working on Ni-Cu base contacts and have to electroplate Cu over electroless Ni.
I have read that for obtaining good adhesion of Cu over Ni , the native oxide should be removed.
Can any one suggest methods to remove the native NiO?
Also how can i ensure that the surface is clean for a good deposit?
What other factors are important to obtain a good adhesion of Cu over Ni?
We have observed weak adhesion of plated Cu on Ni for our samples.

Thanks,
Mehul.

[eazye1334]

I've only been working for about a month at my new company, but we do a lot of electroforming so I may be able to help you. We electroform with electrolytic nickel and with electroforming, you actually want the adhesion to be weak, otherwise you will not be able to remove the electroform from the mandrel. To do so, we passivate the nickel mandrel, which is essentially creating a thin "film" of oxidized nickel on the surface.

So, to me, it sounds like you'll want to do the opposite. From my (limited) knowledge, I would suggest a 5% acetic acid solution. Dip the part in the solution for a minute or so and then rinse with DI water. Because we are just trying to clean it, you may have to leave it in longer for your purposes, I'm not really sure. If this doesn't work, I would suggest increasing the concentration or the time in the solution.

Hope this helps!

[Enthalpy]

As a customer, I heard electroplating contractors say they deposit nickel and move the parts quickly to the next bath to deposit the next metal, without wiping nor drying the electrolyte adhering to the part from the first bath.

Which sounds logical to my very limited understanding: the reducing conditions that deposit nickel must be the ones least prone to create an oxide.

Hope someone more knowledgeable passes by.