The Preparation of 80%Ni-Permalloy Films by Electrodeposition and Their Magnetic Properties

Abstract

The electroplating condition of permalloy films formed on copper plates has been studied in relation to the composition of the films. This composition depends not only on the bath composition but also on current density, pH and temperature. 80%Ni-Permalloy film can always be obtained under the following plating condition: Bath composition, 32 g/L of NiSO₄·7H₂O, 20 g/L of NiCl₂·6H₂O, 18 g/L of FeSO₄·7H₂O and 30 g/L of H₃BO₃; current density, 1 A/dm²; pH, 2.8 to 3.0; temperature, 58∼60°C. Magnetic hysteresis loops have been measured by a 50 cps B-H loop tracer in 80%Ni-permalloy films. The polishing direction of substrates has been found to affect very much the shape of B-H curves. The rectangular B-H loops correspond to the direction parallel to scratches due to polishing. The coercive force, Hc, is proportional to D^−\frac65 in the films thinner than 5000 Å, D being the film thickness. In the films thicker than 5000 Å, however, Hc becomes a constant value, 2.8 Oe, which is far larger than the value of the corresponding bulk alloy.