Simulation of Thermal Protrusions on Magnetic Head Elements

Abstract

Under recent low flying height conditions of magnetic head sliders, both the heat generated by the high-frequency current in the write coils and the rise in the ambient temperature cause local protrusion on head elements. Such protrusion reduces the flying height below the design value, thus reducing the safety margin for head/disk interference. To analyze this problem, we numerically simulated the heat transfer in the head slider, the thermal deformation of the head, and the flying height changes of the slider due to the deformation. The typical temperature distribution obtained from the simulation agrees well with reported experimental results. The simulation results show that decreasing the alumina base coat thickness can reduce the magnitude of a protrusion. For write-current-induced protrusions, the reduced flying height is partly compensated by increased air pressure on the air-bearing surface. However, almost the entire magnitude of an ambient-temperature-induced protrusion translates into flying height reduction.