Method for electroplating a body-centered cubic nickel-iron alloy thin film with a high saturation flux density

摘要

A process for electroplating and annealing thin-films of nickel-iron alloys having from 63% to 81% iron content by weight to produce pole pieces having saturation flux density (B_S) in the range from 1.9 to 2.3 T (19 to 23 kG) with acceptable magnetic anisotropy and magnetostriction and a coercivity (H_C) no higher than 160 A/m (2 Oe). The desired alloy layer properties, including small crystal size and minimal impurity inclusions, can be produced by including higher relative levels of Fe^++ ions in the electroplating bath while holding the bath at a lower temperature while plating from a suitable seed layer. The resulting alloy layer adopts a small crystal size (BCC) without significant inclusion of impurities, which advantageously permits annealing to an acceptable H_C while retaining the high B_S desired.