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Hypophosphite - What's it for and what does it do?

2004

Hi,

I work for a shop that does electroless nickel plating, and I would like to know about sodium hypophosphite. What significance to the electroless nickel bath does this chemical play.

If it goes above the recommended concentration, will it damage the bath?

What is it used for in the bath? Does it normally increase as the bath is used?

I've just begun titrating it weekly, which we never did before. It shows an increase of approx. .5 each week. Before, we only titrated it at the make-up of a new bath.

Please help me, I'm not that knowledgeable, just a lab tech, and could really use someone with real time knowledge on this subject.

Thank You,

Kathi Houchin
- Anaheim, California, USA

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It is NaH2PO2.H2O and has a molecular weight of 106. It is a reducing agent and used to reduce nickel ions to nickel metal in some electroless nickel baths.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004

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Sodium hypophosphite is the chemical that causes nickel to deposit. With out it no plating can take place. It is not harmful if there is more than the recommended amount as far as the plating is concerned. It may increase the deposit rate slightly. Continued use of concentrations above the recommended amount can lead to somewhat shorter solution life, since sodium hypophosphite is oxidezed to the orthophosphite form by heat and by reducinging nickel ions. The orthophosphite form is less soluble and when it reches a high level, precipitation can occur causing plat-out or spontaineous decomposition of the plating solution, plating out nickel powder. If you have additional qluestions, e-mail them to me. I suggest you take the AESF electroless nickel Plating course. Or if your company will allow I or others can put on a course for you and other employees of your company. Ask for costs.

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
           and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])
2004