Electroless Copper Plating on Alumina

A. You can plate alumina like you do ABS through etching, palladium-tin catalyst etc.
-- sara

A. It might help if you mentioned the thickness you require. Most commonly, if you need a thick layer, and the part isn't too complex geometrically, you would first consider electroless copper followed by electroplated copper.

If, for some reason, you HAVE to use strictly electroless copper, why not replenish the copper, caustic, and reducer instead of making up new baths?

A freshly plated copper is quite active and will oxidize. You could use a benzotriazole ⇦ this on eBay or Amazon [affil links] coat between electroless platings, but then you would have to reactivate the surface prior to the next plating.

A. Dear James :
I suggest a 5% H2SO4 solution dip, after rinsing the parts and washing the electro-less Cu solution from them.

Take Care

"Electroless Plating"
by Mallory & Hajdu

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A. Hi cousin Dheeraj. It is my understanding that the HCl is only there as a carrier to maintain pH and make the deposition of the palladium possible. It is the palladium which deposits on the aluminum and acts as the catalyst to start the electroless copper deposition.

But if your interest is in building parts as opposed to developing chemistry, please be aware that these activating solutions are available as proprietary solutions from plating process vendors, and you may get better results from standard sequences of such processes which probably involve tin chloride followed by palladium chloride.

Mallory & Hajdu covers how this activation/catalyzing works in their Electroless Copper chapter. Sorry, I don't know whether alumina works differently than plastics in this activation sequence. Good luck.

Regards,

"Chemical (Electroless) Nickel Plating"
by G. G. Gawrilov

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A. Hi again Dheeraj. I think one alternative is to try to find a vendor of plating-on-plastics process chemistry and see if you can get help. I'm not on top of developments, but I understand that graphite based and organo-metallic metallizing solutions are replacing palladium chloride in some applications. But these processes are the product of years of intense closely-guarded privately funded research, so it would be a matter of buying those proprietary chemicals not trying to find out how to make them. Best of luck.

Regards,

A. I have been able copper plate a form of Alumina Al2O3 (anodized aluminum articles to be precise), so my experience is limited to that -- but it may prove to be an viable alternative to you.
These are the steps for Anodized sheet of aluminum:
Degrease and clean the surface, sensitize the surface with a standard stannous chloride sensitizer solution (3 grams of stannous chloride, 5 ml of HCl, and enough DI Water to make 1 L of solution).
Rinse the article(don't let it dry) and while is wet apply a standard silver mirroring solution( tollen's reagent, brashear process)
After the Silver layer has been applied I was able to coat it with a strong copper layer using the simple but tested 'galvanic copper backing 'layer for silver mirrors. How it works? Make the recently Silvered alumina come in contact with very fine iron or zinc powdered metal and apply a standard copper sulphate ⇦ this on eBay or Amazon [affil links] solution. By way of galvanic electrical contact (standard electrode potential difference between Silver, Iron/Zinc and Copper electrolyte) will deposit a copper layer on the Silvered Alumina.

A video of such process(coating a recently silvered mirror with copper, the only one I could find on the web:

Another way would be by skipping the Silvering and use a Silver Nitrate Activating solution instead of Palladium chloride.
Very good reading here
http://www.ibchem.com/IB/ibe/ibe_doc/Cumirror.doc.