STOICHIOMETRIC MEASUREMENTS IN NICKEL-HYPOPHOSPHITE BATHS FOR ELECTROLESS DEPOSITION

Titrimetric methods and P-31 NMR spectrometry have been compared for t he determination of hypophosphite (H2PO2-) and phosphite (HPO32-) in b oth alkaline and acid solutions used in the electroless deposition of nickel-phosphorus alloys. It has been shown that reproducible and reli able redox titrimetric methods can be used to follow the changes in co ncentration of both species with time during the plating process. In a ddition, measurements of the phosphorus in the nickel deposit by conve rsion to phosphate in acidic solution and use of flow-injection analys is has enabled satisfactory phosphorus mass-balance in the system to b e achieved.