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Tin plating over nickel plating on brass oxidized to black problem over tin plating

April 12, 2010

Hello

My question is we did Electro Tin Plating with under quote of nickel over our brass components and after some days it became black.

Can you please suggest us how to prevent this.

Thank n Regards

Nilesh Patel
Manufacturer - India

April 14, 2010

Dear Nilesh,

Several possibilities: A very bad Nickel plating, porous and/or Cu-contaminated and a thin Sn-layer leading to discolouration in a few days (unlikely).

Contaminated Sn electrolyte (too much organics, too much Cu (also unlikely as mostly already visible after plating).

Bad rinsing. Make sure that the parts are thoroughly rinsed (cold / hot / cold water rinse with pure water) and then dip the parts for some time (seconds to a minute) into a 25 g/l. Potassium carbonate solution and rinse again thoroughly.

As volunteers, we always like to get feedback about what helped you out, hope you won't forget that afterwards.....

Success,

Harry van der Zanden
- Budapest, Hungary

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