Letter 30306

What kinds of anti-pit and additives for nickel sulfamate electroforming [Hong Kong] 

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I'm not familiar with the nickel electroforming process, may I ask: Is SNAP-AM the most suitable anti-pitting agent for nickel sulfamate bath? What is the chemical structure or type of SNAP-AM? Also, what kinds of additives are suitable for this bath? sodium saccharin? any other suggestion?

Thx so much.

Queenie
plating shop - Hong Kong

Ed. note: Full name next time please, Queenie. Thanks.

SNAP-AM is the commercial trade name for a surfactant product used in Barrett Nickel Sulfamate Plating Solutions. The A stands for air agitation, the M stands for mechanical agitation - so you may use either with out foaming. For electroforming hold the surface tension down under 32 dynes per cubic centimeter. Be aware that when/if you carbon treat that the carbon takes out the surfactant first, before it touches the particular organic contaminants you are trying to remove.

Sachrin increases compressive stress. Do not use sachrin for electroforming.

Do not use any additives. For electroforming you want a very clean simple solution of Nickel Sulfamate and Boric Acid (Solubility a function of temperature). Chloride and/or Bromide are sometimes used to aid in the dissolving of the anodes. If you use S-Rounds you may only need 1/2 oz/gal Nickel Chloride, try it without chloride first, then if the metal goes down, then put in 1/2 oz/gal,. Chloride causes increase in tensile stress so keep it low.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

SNAP is the acronym for sulfamate nickel anti pit that dates back to the Barret process. This is used for plating with a low level of agitation. SNAP-AM is for air or heavy mechanical agitation. You can search this site as the generic version has probably been discussed in the past. BUT, where do you find out how to control the amount for optimum results. I learned a long time ago that it is not worth reinventing the wheel to save a few dollars a year. I would buy the original or a good equivalent from a reputable vendor that can also provide technical service when needed. If your time is worth anything at all, it is cheaper in the long run.

James Watts
- FL

Nickel electroforming is, in principle, reasonably easy, but you need to understand some fundamental concepts. I would say that there is no "best" wetting agent for electroforming, as different wetting agents can have varying effects on the final deposit. You may want to alter the stress in a deposit and this can be done by using the correct additive. Sodium saccharin is an excellent brightener and hardener for nickel, but it can affect the stress. I would suggest you speak to a supply house and tell them exactly what you need and let them supply a well tested system. It will save you a lot of time and effort, as well as money in the long run.

Trevor Crichton R&D practical scientist - UK

Thank you for all your reply and suggestion. I have asked some local vendors what kind of additive is suitable for the nickel sulfamate bath, and they told me that they would mix up the nickel sulfamate with the optimum amount of additive before selling to the customers. Actually, my project is related to the micro-electroforming of nickel,and I realized that the macro-scale is different from the micro-scale, may I ask that what aspects of micro-electroforming I need to take much more attention, or just based on the macro-scale procedure...thanks for giving me kind help!

Queenie Yuen
- Hong Kong

Your important aspects will be the surface tension and viscosity of the electrolyte, the flow rate around your mandrel and the cleanliness of the mandrel. It is important to get as lower surface tension as possible and to have a low viscosity. Do not exceed 70C with sulphamate nickel or it will become increasingly more stressed. You may well get some more reliable tips if you look up MEMS technologies on the Internet.

Trevor Crichton R&D practical scientist - UK

Dear Sir,

I am also a new hand in the nickel electroforming.
As Doc.Trevor Crichton said, my important aspects are the surface tension and nickel flow rate.
If I use saccharin,the result is increasing compressive stress,but the sorption is very well.
If I do not use saccharin, the result is noincreasing comprssive stress, but the sorption is bad .
So could you suggest me how to do?

Sarah Li
nickel plating - Hong Kong, China

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