Nickel sulfamate electroforming: anti-pit & additives

A. 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.

Saccharin increases compressive stress. Do not use saccharin 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.

First of two simultaneous responses --

A. SNAP is the acronym for sulfamate nickel anti pit that dates back to the Barrett 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.

Second of two simultaneous responses --

A. 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.

A. 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!

A. 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.

A. Hi Neil. I'm not sure why you want to do your own formulation, but you can find the concentrations and other data in the Metal Finishing Guidebook .

One more thing you'll probably need is a wetting agent; I suppose you could try baby shampoo. Good luck.

Regards,

Hi. It's there on page 295 of the book (which seems to be p. 301 in the app's search engine). Good luck.

Regards,

A. Hi again. I think you probably could get away with stainless steel anodes, but then the nickel concentration will decline as you plate; the ideal for your situation is probably sulfurized nickel anodes. A big advantage you have over industrial users though is the "one-off" nature of your need, whereas industrial platers must maintain an equilibrium process (concentrations of everything remaining stable over time despite heavy use).

Although I'm no sulfamate nickel expert, and many people have spent significant portions of their careers on just that one subject, I don't think you need any chloride (one of the important roles of chloride is to promote anode corrosion) -- probably not needed with sulfurized nickel anodes or stainless anodes. If you end up using pure nickel anodes because of availability, then some chloride is necessary if you want the anodes to corrode for stable nickel concentration.

Try to befriend a nickel plater in the Toronto area; it would make things a lot easier :-)

Regards,