Omega head—an experimental 120-turn inductive head

Abstract

Experimental 120-turn thin-film inductive heads have been built. The key features of this head are the 6-μm pitch helical coils and an omega-shaped, planar yoke structure having dual easy axes. Hardbaked photoresist insulator layers are used to encapsulate the yoke and to smooth out the wafer surface topography. Micro-Kerr studies show that the easy axis remains in the transverse direction in the yokes after multiple anneals. The P1/G/P2 is 3.8/0.3/3.8 μm, and the yoke length is close to 1 mm. The helical coils were built with a novel process that combines yoke/stud coplating and a photoresist planarization process. The coil resistance is 68Ω and the inductance is 5.5 μH. The yoke saturates at 5 mA. The heads were tested over disks having Mrt of 2.5 memu/cm2 and Hc of 1500 Oe. The write threshold current is 5.3 mA (peak-to-peak) and the overwrite is 30 dB. The isolated pulse amplitude Vpp is 10.3 μV/(TwV), where track width Tw is in μm and the linear velocity V in m/s.