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Cracks in the electroformed stampers

adv.  

June 22, 2009

We have a mastering facility in Egypt where we produce Nickel stampers for the CD/DVD industry.

We have a problem with production in one of our electroforming cells. we see a lot of cracks and breaks in the stamper. This makes us stop the process because of the nickel sludge in the bath.

We use a Nickel sulfamate electrolyte with no nickel chloride.
Nickel concentration is 92 g/l
Boric acid is 50 g/l
PH is 4
and operating temp is 52.
The production cell is manufactured by Technotrans.
All the chemicals are pure and we even exchanged the whole electrolyte.

Please advice.

Ahmed Fawzi
Stamper Producers - Cairo, Egypt

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July 23, 2009

I would be concerned about getting sludge in the nickel tank - this suggests to me that you are not using S-Nickel but just normal electrolytic nickel. When using a sulphamate bath with no chloride, you must use S-Nickel, or the anodes will stop dissolving properly and form sparingly soluble oxides. These will co-deposit with your nickel and produce stressed and rough deposits.

One of the advantages of sulphamate baths is that you can get away with not using chloride to promote anode dissolution, but many electroformers tend to add just a bit (say 5g/l) as a "just in case" aid. This will not cause too much stress, but if your are not using S-Nickel, it may help reduce, but not eliminate the sludge.

You also do not give any detail of your current densities - it is possible you are operating at too higher cd and this too can cause problems.

I would also suggest you talk with your supply house and try using a stress reliever.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

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July 24, 2009

For sludge control, ALSO increase the rate of filtration and appropriately double bag your anode baskets. They need regular changing! Being frugal (cheap) ends up costing money because of rejects.
Cracks-Check your stress levels. Something is bad wrong.
Have you tried a stress relief cycle prior to the plating cycle. It might help.

James Watts
- Navarre, Florida