Metallic Precipitates in EN Bath



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Q. During our EN plating, we are forming metallic like precipitates in our tank. What are some of the possible causes of this problem? F. T.


A. Most likely, the precipitate is nickel and there are many possible causes for this problem. Here are a few: 


  1. If using a stainless steel tank, the tank was not passivated properly or it is not anodically 
  2. If using a plastic tank, the tank was not completed stripped and/or not properly passivated.
  3. The EN solution is not adequately filtered.
  4. The EN solution requires additional stabilizer. EN solutions must be tested on a frequent basis. Your chemical vendor can help you with this.
  5. The EN tank is etched or has rough surfaces. The tank may have to be replaced. Rough surfaces can cause precipitation of nickel from the solution.


I also recommend that you acquire a copy of the book, Electroless Nickel Plating by Wolfgang Riedel, ASM International. The book contains much information about managing the EN process. It is available at www.amazon.com.


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