Effect of thermal pole tip protrusion and disk roughness on slider disk contacts

Abstract

Ultra-high areal density for hard disk drives requires a stable head disk interface at a flying height lower than 8 nm. At such a low flying height, small flying height variations may cause slider/disk contacts. Slider/disk contacts can also occur when a write-current is applied to the write coil since the flying height between slider and disk can be affected by the thermal expansion of the pole tip. In this paper, we investigate the vibration characteristics of sliders during thermally induced contacts using laser Doppler vibrometry. We perform a parametric study of contact events using disks with different surface roughness and lubricant thicknesses, and analyze the slider motion statistically. For a given write current, we observe that the slider vibrations increase with disk roughness and lubricant thickness.

Characterization of light contact in head disk interface with dynamic flying height control

“…However, when the DFH voltage was further increased, the AE signal dropped quickly to a relatively low level. During the process of the increase in the DFH voltage, the output AE signal exhibit three distinct regions: region I (without DFH voltage), region II (with threshold DFH voltage) and region III (with saturated DFH voltage), which is consistent with previously observed results (Tang et al 2007;Zhang et al 2009;Xu et al 2009;Hua et al 2009;Canchi and Bogy 2010).…”

“…Juang and Bogy (2007) investigated the relationship between air bearing surface design and thermal actuation of a slider. More recently work can be found in (Xu et al 2009;Hua et al 2009;Vakis et al 2009;Shiramatsu et al 2009;Li et al 2009;Tani et al 2009;Ng et al 2009;Canchi and Bogy 2010;Knigge et al (2006); Li et al 2010;Canchi and Bogy 2010). Although the above studies have clarified many aspects of current-induced thermal pole tip protrusion, there are still many areas lacking of understanding.…”

A parameter identification method for thermal flying-height control sliders

“…This low level remains steady when the driving voltage was further increased. During the process of the increase of the driving voltage, the output AE signal exhibit three distinct regions: A (without driving voltage), B (with threshold driving voltage) and C (with saturated driving voltage), which were previously reported (Tang et al 2007;Zhang et al 2009;Xu et al 2009;Hua et al 2009;Canchi and Bogy 2010).…”

“…Slider dynamics in the regime from sub-10 nm clearance to sub-nanometer clearance has been widely investigated by many researchers (Juang et al 2006;Li et al 2009;Zhang et al 2009;Liu et al 2009;Knigge et al 2006;Tang et al 2007;Xu et al 2009;Hua et al 2009;Canchi and Bogy 2010;Suh and Polycarpou 2005;Vakis et al 2009;Tani et al 2009;Ono 2009; Thornton and Bogy 2004). There are many experimental and numerical investigations as well as qualitative correlations.…”

The effect of write current on thermal flying height control sliders with dual heater/insulator elements

“…2 , a stable head/disk interface at an ultra-low magnetic spacing is required for magnetic hard disk drives. Pole tip protrusion caused by the write current may lead to flying instability of the slider and to head/disk contact (Tian et al 1997;Pust et al 2002;Imamura et al 2002;Xu et al 2009;Song et al 2008;Li et al 2005).…”