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Clean pit in electroless nickel layer

I am working with a electroless nickel plating operation for disk drives. They are experiencing a pitting problem. The pit appears to be circular and domed and occurs throughout the plated layer from the aluminum substrate to the surface of the nickel layer. Auger has been performed and only phosphorus and nickel have been identified. I have heard the term "clean pit" used to as a defect type and was wondering what causes the clean pit. If you have any information the cause of the "clean pit" I would greatly appreciate you contacting me.

Thanks,

Thomas G.
- York, Pennsylvania , USA
2004

A bubble that adheres to the surface and stays there most of the time will "mask it" and therefore leave a clean pitt. Improve your pretreatment and add an approved wetting agent for your bath. Your EN vendor will be able to advise you in this respect as he knows what's in your bath.

Guillermo Marrufo
Monterrey, NL, Mexico
2004

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2004

Guillermo is correct that hydrogen gas bubbles will cause pits. These pits are usually hemispherical in shape. They need something on the surface on which to initiate. This can be a soil left behind by inadequate cleaning, or it can be a defect in the aluminum itself, like a pit or inclusion. You should investigate both possible sources.

Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.