Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


nickel corrosion

Views: 3357


XPS

#62259

nickel corrosion | 15 July, 2010

Hi after an enviromental test 85C/85RH, for 3 months (powered), of an electronic assembly with edge finger tabs ENIG finished (nickel 5micron, gold 0.02micron), the nickel disappears completely under the gold (due to corrosion, I think). Does anyone know the reasons for this ? Perhaps it is due to the presence of phosphorus ? XPS

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#62260

nickel corrosion | 15 July, 2010

Things don't disappear completely. If something caused nickel corrosion, the nickel corrosion by-product would be in place of the nickel.

Is it possible that ... There never was any nickel? We know that the nickel will diffuse into the copper. That's why the nickel plate needs to be greater than 2 microns. There's no way all of your 5 micron plating would diffuse into the copper. Test this theory by analyzing the copper.

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XPS

#62262

nickel corrosion | 15 July, 2010

Thanks... anyway I confirm, the nickel disappear (verified by cross section)and a strange substance greyish above gold, covering the tabs after test. I don't know the reason for this phenomenon. I don't believe that with proper electrolytic nickel finish, this would have happened. So, I think that has to do with the different composition of nickel electroless... Is a very mystery.

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