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Electroform defect on nickel sulfamate

I'm having a defect in nickel sulfamate electroforming, my base is glass, and sputter nickel-vanadium, when I get the thickness in 3um, the sputter had broken a hole, the hole size is 50um to 150um, what can I do?

Thanks and regards,

Stanly Chen
electroform shop employee - Taipei, Taiwan
March 26, 2008

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Stanly,I am not sure I understand what you are saying. Are you suggesting that after 3 microns of nickel has been deposited, the Ni-V sputtered layer shows holes in it, or are the holes already thre and it takes the nickel electroform to show them? The usual reasons for holes in electroforms are either incomplete metallising layers, as with sputtered Ni-V, or gas bubbles forming on the surface and not being released. If the metallising layer is discontinuous, it can be rectified by increasing the thickness of the coating. If it is due to gas bubbles, you need to add more wetting agent to the electroforming bath.
Electroforming onto very thin metal films can be very tricky, as any thinness could result in the metallising layer being "blown off" by too higher current being passed through it.
If the Ni-V layer is discontinuous, this could be due to a dirty glass surface, or defects in the glass. It would be a good idea if you treated the glass with a plasma discharge in the same chamber and immediately prior to metallising it with Ni-V - in other words, once the glass is in the chamber it should not be removed or touched until after it has been metallised.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
April 9, 2008