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Nickel hydroxide causes problem in electroless nickel tank

2005

I have a problem about Ni hydroxide that always occur in my plating tank ( electroless Ni plating ),it occur in many time some time before plating sometime during plating.We use chemi robot for auto replenishment during plating and before plating we use manual replenishing for adjust any setting value ( Ni , NaOH(for pH ) , Sodium hypophosphite ).
please clarify me about the cause of this problem.
Thank you very much.

Mr.Wutthichai Paengkaew
plating shop - Thailand

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First of two simultaneous responses --

I'm not sure but it seems that your bath may have insufficient or incorrect complexors and buffers, so when you add the caustic to raise the pH the reaction is too violent and cannot be controlled. If you're using a home brew bath, you will have some troubles in exchange for the lower cost. Keep asking and learning and you may end up with a chemical system very close to a patented bath. If yours is a commercial bath, your vendor must tell you.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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Second of two simultaneous responses -- 2005

Dear Wutthichai Paengkaew,

If you add a very high concentration of NaOH as the make up solution or bulk addition of NaOH, precipitation of nickel hydroxide will happen.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note: The good doctor offers a fascinating blog, "Advancement in Science" )

If you must use NaOH, do it in the most dilute form that you can. Turn your air agitation up as high as you can tolerate and very slowly add the caustic while rapidly moving the point where you are putting it into the tank.IE: use all of the area of the top to make the addition. VERY slow additions!

James Watts
- Navarre, Florida
2005