Letter 36037

About nickel electroless plating

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I want to plate a nickel film (onto Thicon, a glass which is sputtered with gold). I want to know what solution is required? (Do I need to buy several chemicals for activator, etc.) And what is the step of the electroless plating?
Thanks.

Leo Tam
University - Hong Kong

Ed. note: Hello, Leo. We corrected a couple of speling errors and changed some punctuation, but I'm not sure we got your question right. Could you please spend a copuple of more paragraphs explaining in detail what you are trying to accomplish? Thanks.

Hello Leo,
It is funny that you want nickel over gold... normally people do the contrary.
First of all electroless nickel has only about 90% nickel and is amorph (after deposition).

But the main problem is to plate over gold. Once I saw that it might be possible but you don't have a good adhesion (maybe because we cannot prepare gold).
If you can achieve an oxidoreaction between gold and platine, then you can put electroless nickel over platine.
But I don't know if it's possible and it is surely "very expensive"
Then you can try any eless nickel bath (schloetter, Durnicoat, ...) you can get from 5% to 15% Phosphor in your nickel.
Regards,

Gregory Bellynck

Bellynck Gregory
semiconductor - Regensburg, Germany

Thanks for reply my question. The adhesion is not the problem as I will etch away the gold after plating. However, after reading some books, I saw that mixed colloidal catalyst is required before the electroless plating. I want to know that if I already have gold suface on the surface, can I omit this part and directly immerse the glass with sputtered gold after cleaning? (As I want to use photoresist as a barrier for patterning, immersion of that catalyst may cause the plating on both gold and photoresist surface.)
Thanks.

Leo Tam
University - Hong Kong

Yes you can skip that step when the object you wish to electroless plate (autocatalytic plate) is already conductive. I am not sure, however, whether gold is catalytic to nickel (I doubt that it is). That means you need to 'spark' the plating to get it started, i.e., apply electricity for a second to get the first few atoms of nickel deposited onto the gold.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

I think everything can be plated without "catalyst"... that is the reason for plating problem and instability...

Sometimes I get nickel on non conductive materials (but organic resist work fine to protect from plating). I think it won't be difficult to plate on gold. If you have your own chemicals, try to reduce the stabilisator concentration or simply remove it.
Regards,

Gregory

Bellynck Gregory
- Regensburg, Germany

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