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Testing of gold plating adhesion

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Hi,

We are plating stainless steel gold (0.5 um) over nickel (2 um). We're occasionally finding areas of plating flaking off. Can anyone recommend a test we can perform on a sample of each lot to check the adherence of the gold plating?

Thanks!

Anthony Johnson
designer - San Francisco, California, USA

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Anthony,
It would be important of course to get to the root of the problem. If you are getting gold from nickel peeling the nickel is becoming passive. Going right into the gold after nickel plate is imperative. If that is not possible a good nickel activator is in order. If both layers of plating are peeling (Ni & Au), the pre-clean and woods Ni strike should be addressed.
Most Au adhesion tests are done by a tape pull test. Locate a reputable tape supplier that sells plating tapes, they normally have adhesion test tape available. Press the tape on the part completely, pull off quickly with a slight upward angle. Pulling straight up on the tape does not put enough pressure on the plated layer, the test would be inconclusive. Good Luck!

Mark Baker
Process Engineer - Syracuse, New York

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The tape test sounds good to me in your situation (clean the surface thorougly, apply a good quality vinyl tape and pull it off vigorously). But the most important action would be to review your process to eliminate the problem. Are you using a Woods strike to activate the SS?

Guillermo Marrufo
Monterrey, NL, Mexico

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Hello;

I want to apply rubbing as an ndt test for adhesion ofcadmium platings.Is there anyone know how to perform rubbing test? Or does anyone know a relevant standard or process specification for rubbing?

Thanks in advance

Burak Deger
- Turkey