In 1989 during a conference about Electroless Nickel; a paper was submitted titled as “Soldering ability Parameters of Electroless Nickel Bearing Electronic Finishes” by Louis Kosarek of STB Systems, Inc. stated that:
"An electroless nickel deposit which contains a concentration of phosphorus ranging from 0.1% to 3.0% is readily soldering ability on an "As-plated Basis" per Mil-Std 883c method 2003. The frequency of soldering ability tests which fail per Mil-Std 883c will increase as the phosphorus content of electroless nickel alloy increases from 3.0 to 7.0% phosphorus. A soldering ability test conducted per Mil-Std 883c method 2003 incorporating an as-plated surface finish containing phosphorus in excess of 7%, the components will consistently fail. The mode of failure is non-wetting of the surface."
The fact and figures produced by Mr. Kosarek lead to a research work to the university students as well as became a helpful source for the practical engineers in providing precision engineering services especially while working with Electroless Nickel soldering property.
In my point of view most of the solderability problems that came across were due to the fact when the buyers switches vendors, and the new vendor does not have low Phosphorus nickel, and uses medium or high Phosphorus instead or the vendor simply stops using the low Phosphorus because of low demand and substitutes mid or high Phosphorus thinking they are the same. In most of the cases the solderability problems demolished when the venders understand the requirements of the buyers and maintain the supply up to the standards as recommended by the buyer.
"The purer the nickel alloy; the better the soldering ability will be"
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