Studies on Nickel Deposits from Electroless Nickel Plating Solutions Containing Ethylene Diamine

Abstract

Phosphorus content, grain size, and hardness of the deposits from the following electroless bath were measured for various conditions of pH and concentrations of hypophosphite and ethylene diamine.NiSO4·7H2O 0.1mol/l pH 6NaH2PO2·H2O 0.2mol/l Temperature 90±1°CH2NCH2CH2NH2 0.15mol/lThe following results were obtained.(1) Crystalline deposits having preferred orientation of (111) were obtained from acid plating solutions (pH=6) having low concentration of sodium hypophosphite.(2) The deposition rate at pH=6-7 was found to increase with the increase of concentration of sodium phosphate or ethylene diamine.(3) The grain size was smaller when the phoshorus content was higher since the growth of grains was inhibited by phosphorus adsorbed on lattice plane.(4) Change of hardness did not always correspond with the change of phosphorus content. Accordingly, the hardness of deposits would not merely depend upon phoshorus content.