Head protrusion and its implications on head-disk interface reliability

As magnetic recording areal density increases the mechanical spacing betwee n the head and the disk continues to shrink. Head protrusion, induced by wr ite current heating of the coil and yoke during recording at operating temp erature, may interfere with the disk. In this work, we have measured the he ad temperatures as a function of write current, frequency and flying condit ions. The rise in coil temperature for a flying head was found to be much l ess than a head on the load/unload ramp. The measured temperature coefficie nt was consistent with the simulation. The amount of head protrusion was me asured as a function of the write current. The head-disk interaction of the interface after 100 000 write current bursts resulted in alumina wear. Som e of the effects of head protrusion on the interface reliability are discus sed.