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Pretreatment for Tungsten-Copper Alloy

Our customer asked us to plate electroless nickel and then gold for the 85% tungsten 15% copper alloy. We checked that it can be done with a sulfuric acid and hydrofluoric acid (we used ammonium bifluoride and nitric acid) mixture. But this mixture does not give us consistent result. I suspect it is due to nitric acid which is an oxidation agent. Is there any other better acid for etching and pickling?

Best regards - Yours truly

Tian Ang
consulting - Kajang, Malaysia
2001

Plating process for this alloy is a highly proprietary matter to most companies manufacturing and selling the components. However, a couple of important points can be made. In many procedures, one metal from the alloy is etched out. You have to select that first. After etching that metal, micro-cavities are left behind. Then rinsing becomes critical. And this is not all, but a good start.

Mandar Sunthankar
- Fort Collins, Colorado
2001