Head protrusion and its implications on head-disk interface reliability

As magnetic recording areal density increases the mechanical spacing between the head and the disk continues to shrink. Head protrusion, induced by write current heating of the coil and yoke during recording at operating temperature, may interfere with the disk. In this work, we have measured the head temperatures as a function of write current, frequency and flying conditions. The rise in coil temperature for a flying head was found to be much less than a head on the load/unload ramp. The measured temperature coefficient was consistent with the simulation. The amount of head protrusion was measured as a function of the write current. The head-disk interaction of the interface after 100000 write current bursts resulted in alumina wear. Some of the effects of head protrusion on the interface reliability are discussed