A new soft magnetic CoNiFeB thin film with high saturation magnetic flux de
nsity, B-S and good corrosion resistance has been prepared by using an elec
troless deposition method. The electroless CoFeB thin film has high B-S but
a poor corrosion resistance compared with the electrodeposited NiFe (80-pe
rmalloy) film. The addition of Ni to the CoFeB film improves corrosion resi
stance without affecting its soft magnetic properties. One of the best CoNi
FeB films prepared had a composition of Co77Ni13Fe9B1 with excellent magnet
ic and electrical properties (high B-S = 1.5-1.7 T, low coercivity, H-C = 1
.2 Oe, low magnetostriction, lambda (S) = 2.0 x 10(-6), and moderate resist
ivity, rho = 40 mu Ohm cm). The new CoNiFeB thin film is suitable for use a
s a core material for the next generation of merged MR-heads. (C) 2000 Else
vier Science B.V. All rights reserved.