Inductance Saturation of Perpendicular Recording Heads in Magnetic Field

Inductance measurements of perpendicular recording heads provide information about magnetic yoke, coil-yoke interactions, and flare geometry. These techniques combine high-resolution (approximately 1 pH) inductance measurements with head saturation in multidirectional external magnetic field and direct current (dc) write current. Coil-yoke coupling can be measured by simultaneous magnetic field and dc saturation and allows characterization of head efficiency and defects. Yoke anisotropy is detected by comparing inductance levels in transverse/longitudinal magnetic fields. Details of flare geometry and defects can be characterized using saturation dependence on magnetic field angle. These methods allow nondestructive write head characterization at early production stage (wafer or bar-level testing).