DYNAMIC STABILITY AND SPACING MODULATION OF SUB-25 NM FLY HEIGHT SLIDERS

Designing a reliable sub-25 nm spacing head/disk interface for today's magnetic hard disk drives demands a greater dynamic stability and a s maller spacing modulation. An air bearing dynamic simulator with multi ple features is developed to investigate the dynamic characteristics o f three shaped-rail negative pressure sub-25 nm fly height sliders. Va rious simulations including air bearing stiffness, impulse response, s urface roughness induced spacing modulation, bump response, and track seeking dynamics are performed. The results indicate that the roughnes s induced spacing modulation decreases with the increase of the air be aring stiffness and the decrease of the slider size. The suspension dy namics is integrated into the air bearing dynamics simulation for the track accessing motion by modal analysis. It is concluded that the fly height modulation during a track accessing event is attributed to man y factors such as the effective skew angle, the seeking velocity, an t he roll motion caused by the inertia of the moving head. The extent of the roll motion effect depends on the air bearing roll stiffness and the level of the inertia force of the moving head. Larger roll stiffne ss and smaller inertia force produce a smoother track accessing perfor mance.