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PCB Gold Pad Corrosion.

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#77446

PCB Gold Pad Corrosion. | 20 April, 2017

Hi Guys, Currently im seeing corrosion on a gold pad as i shown in the picture. May i know is this corrosion or pad oxidation??

This defect were found after complete of all process including cleaning and im using water-soluble flux to run the product. Im suspecting this defect may occur due to uncleaned flux.May i know what are the possibility can lead to this defect?? Is there any chances to remove the corrosion?

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#77447

PCB Gold Pad Corrosion. | 20 April, 2017

Hi ,

It can be wiped out by eraser or not ?

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#77449

PCB Gold Pad Corrosion. | 20 April, 2017

It's difficult to tell anything from your picture. But playing the odds, I'd say it's not "gold corrosion." It is very difficult to corrode gold. Gold is a NOBLE metal.

From Wikipedia, the free encyclopedia In chemistry, the noble metals are metals that are resistant to corrosion and oxidation in moist air (unlike most base metals). The short list of chemically noble metals (those elements upon which almost all chemists agree) comprises ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au).[A. Holleman, N. Wiberg, "Lehrbuch der Anorganischen Chemie", de Gruyter, 1985, 33. edition, p. 1486]

Again paying the odds, I'd start by considering that someone may have shorted you on the thickness of the gold over-plate on your pads, which has allowed theunder=plating to oxidize.

Finally, stay away from pencil erasers [and sand paper] for troubleshooting issues like this. They're abrasives and primarily reduce the thickness of your plating.

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#77451

PCB Gold Pad Corrosion. | 20 April, 2017

already tried but still the same.

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#77578

PCB Gold Pad Corrosion | 15 May, 2017

Pin holes in the gold can allow for corrosion of the underlying nickel and copper to form copper and nickel oxides on the gold surface (example - http://www.semlab.com/blog/?p=564).

The corrosion can work itself all the way through the EN layer (example - http://www.semlab.com/blog/?p=85)

Finally, if the contamination is bad enough and involves halides left behind from assembly, then surface ECM can occur as well (example - http://www.semlab.com/blog/?p=632)

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