Metal finishing Q&As since 1989

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Gold Nickel Adhesion decreased due to oxide layer

January 12, 2006

I was wondering if anyone knows how to improve Au to Ni adhesion. I'm plating Au on top of Ni and there seems to be a 25A oxide layer that decreases my adhesion such that it fails the tape test.I'd like to either prevent the oxide from forming or remove it.

[name removed at request]
R&D Engineer - Minnesota, USA

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How much time is there between Ni and Au? As you probably know, you can't let Ni plated parts sit in rinse tanks, they will passivate. Directly after Ni rinses you can use a Ni activator, rinse well and go directly into the gold. Be careful with choices of Ni activators, some contain high chlorides and you don't want to drag them into your gold bath. Good Luck!

Mark Baker
process engineer - Malone, New York
January 13, 2006

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You start by doing a search of this web site. It has been talked about dozens of times.
Can you stand Hydrofluoric acid mixtures or fluoride containing acids?

James Watts
- Navarre, Florida
January 14, 2006

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January 16, 2006

DEAR SIR YOU MAY DO THE FOLLOWING
1-GO FOR GOLD PLATING AS FAST AS POSSIBLE,WITHIN ONE TO TWO MINUTES.
2-USE AN ACTIVATION TANK CONTAINING CYANIDE POTASSIUM,AND THE PART ON THE NEGATIVE
GOOD LUCK

Khair Shishani
aircraft maintenance - Al Ain, UAE

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I do not know what is your electroplating cycle after the Nickel Plate, Normally it is followed with an acid activate or cathodic activator,then a gold Strike before gold plate with drag-outs and rinses in between.

Hamilton Solidum
- Mays Landing, New Jersey, USA
January 16, 2006

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January 16, 2006

Dear Sir
Reduce Time delay from Ni>Au plating.Do Multiple DM water swills in between.Introduce an activator dip prior to gold plating.Caution! Consult your supplier before doing this.The ingredients of the activator should be compatible with the gold bath solution. Introduce a pure gold strike/Flash bath with minimum gold in the bath before the main gold bath.
Regards

T.K. Mohan
plating process supplier - Mumbai, India

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January 19, 2006

Thank you all for you comments.

Unfortunately, my process requires that I go through several steps between the Nickel and Gold Plating. One of those steps happens to be high temperature (over 300C) cure which is likely responsible for the oxide layer growth. Since I can't change my process flow, or my high-temperature cure, what can I do to remove the oxide layer after it is formed? Anything besides HF?

Thanks!

[name removed at request]
R&D Engineer - Minnesota, USA

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Is possible to use an inert atmosphere or reducing atmosphere during heat treatment and cooling procedure to prevent oxide formation.

Have you tried, acid Salts solution with ammonium bifluoride, Hot. Check with your Nickel Solution supplier.

Good Luck,

Hamilton Solidum
- Mays Landing, New Jersey, USA
January 20, 2006

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Sir,
Immediately either go for an anodic cleaning after curing or better introduce an anodic activator/dry salt.
regards

T.K. Mohan
plating process supplier - Mumbai, India
January 20, 2006