抄録
Electroless Fe-Ni alloy (20Fe-80Ni permalloy) deposition has been studied in two types of solution containing either sodium hypophosphite (NaPH2O2) or dimethylamine borane (DMAB) as a reducing agent and trisodium citrate as a complexing agent. The partial current densities of Ni and Fe in the alloys electrodeposited at constant potentials showed that less noble Fe exhibited strongly induced codeposition. The alloy deposition rate was obtained both by the superposition of anodic and cathodic partial polarization curves in each solution of 02 for the FN ratio (Fe2+/(Fe2++Ni2+)) and by Tafel extrapolation in the total polarization curves of the complete electroless plating solution. The deposition rate determined by the weight gain in the DMAB plating bath was consistent with those obtained by electrochemical polarization measurements.
The effect of pH and the metallic ion concentration ratio, i e, the FN ratio, of NaPH2O2 and DMAB plating bath on the Fe content in alloys and the deposition rate was examined. The optimum condition for obtaining the alloy in the DMAB plating bath was determined to be pH 95-10 at an FN ratio of 03.
The Fe content of NaPH2O2 plating bath was about 10% at an FN ratio of 02-06, which is low compared to the monotonically increased 45% at an FN ratio of 08 of DMAB plating bath. These results suggest that the phosphorous element in the reducing agent retards Fe deposition.
The X-ray diffraction patterns of the deposits maintained -10V for 1h exhibited three distinct 111, 200, and 220 peaks. The electroless plating deposit showed the preferred orientation of the 111 peak accompanying a broadening peak.
