Permeability of narrow permalloy stripes

The effective permeability between 1 MHz and 100 MHz was measured for 1–3µm thick permalloy(80Ni-20Fe) films in 2–3 cm diameter sheets and compared with the effective permeability for the same films after etching them into 51 µm wide stripes on 127µm centers. Solid permalloy films show a 15%–40% loss of effective permeability at all frequencies after having been etched into stripes. Permalloy films made with nonmagnetic metal laminations show no significant permeability change after etching. Films made with dielectric laminations show no significant permeability change at low frequencies and a 20%–100% increase in the high frequency permeability after etching. © 1977, IEEE. All rights reserved.