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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Gold Fingers Discoloration

Patrick Ng


Gold Fingers Discoloration | 3 July, 2000


We are receiving PCBs with gold fingers "discolored". The "discolored" gold fingers can be removed if rub with soft eraser! We are working with suppliers to determine the root cause and eliminate this issue. Pls assist if you have encountered similar issue before!

Thanks & Regards, Patrick

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Michael Parker


Re: Gold Fingers Discoloration | 5 July, 2000

Patrick- You have not given enought detail of the type of discoloration. Is it "white residue"? Can it be "rust" colored?

Whatever it is, you fab supplier needs to be called in immediately and give you an exact reason for this failure. Just rubbing it away only hides the process defect that created the problem.

If it is white in color, I suspect that your suppliers wash process has dirty water that is leaving flux residues and other junk on your gold fingers. Check your boards for ionic contamination.

If rusty colored, the plating process had a failure. You did not specify how much gold or the process, whether it is plating or flash. If flash, you probably did not get what you ordered. Check the certifications on the suppliers QA sheet for how much gold was verified.

If none of the above helps, get more specific with your description of the failures.

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Re: Gold Fingers Discoloration | 5 July, 2000

Hi Patrick: Mike is correct. Taking it a little differently ...

The approach you take is dependent on: 1 Type of gold finish 2 Source of the staining.

Since you�re talking gold fingers, this is probably hard gold. So, � * If it�s a water or an organic stain, start with DI H2O and a Q-Tip, next 80/20% DI H2O/IPA on a Q-tip, next 100% IPA on a Q-tip, next 100% O2 plasma @ 12 min ambient chamber temperature. * If the stain is metallic, start with IPA and a Q-Tip, then move to the good ol' ruby red eraser that you mentioned.

Good luck

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Michael Parker


Re: Gold Fingers Discoloration | 6 July, 2000

Thanks Dave for the right methods that will get Patrick out of his mess. As long as one is a "Do it yurselfer". I still advocate having the supplier accept responsibility and clean the boards. After a bit of elbow grease, some cussin' and lost time I will bet the supplier won't let it happen again. And if they do continue to pass bad product, it is time to qualify a new vendor.

Good luck, Patrick.

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Re: Gold Fingers Discoloration | 6 July, 2000

I agree. Make them quit doing this ugly thing to your boards!!!

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