High/Medium/Low Phosphorus Electroless Nickel Bath

Quickstart:
     Electroless nickel is not a single process but a process which can be engineered to deposit anywhere from less than 4% phosphorous to over 12%. We generally call them low-phosphorous, mid-phosphorous, and high phosphorous and their properties can be very different regarding corrosion resistance, ductility, magnetic properties, heat treatability, etc.
     Additionally, although electroless nickel phosphorous coatings are usually deposited from acidic hypophosphite solutions, alkaline hypophosphite electroless nickel is done as well.

Q. I need to plate Electroless Nickel coating onto Copper substrate. The coating must be with high (>10%), Medium (8-10%) and low (<4%) phosphorus content. What are the bath combinations that produce such coating? Or is there any commercial bath supplier?

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A. There are a number of commercial suppliers of all three baths you mention.

James Totter, CEF
- Tallahassee, Florida

A. Yes, proprietaries are the way to go with electroless nickel. Home-brew will not achieve as many turnovers, so it may end up costing more. Plus it's a changing world and the various materials used in home-brew, may incorporate traces of lead or cadmium or other contaminants whereas the major suppliers keep up and help keep you in environmental and safety compliance. There are numerous reputable suppliers available.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.

Q. I've tried the following combination of EN plating solution. It is said to produce low Phosphorus content (2%). Somehow I've got 12%. Why is it so?

Nickel sulphate 30 g/L
Sodium hypophosphite 30 g/L
Sodium pyrophosphite 60 g/L
Thiourea 3 mg/L
pH 9
Temperature 85 °C

What other combinations that can produce low and medium Phosphorus deposition?