Mechanism for formation of whiskers on a flying magnetic recording slider

When large amounts of contaminant particles exist in magnetic hard disk drives, whiskers can form at the trailing end of the air bearing of the sliders. Through whisker formation, small particles can accumulate to form a mass comparable to the slider dimensions. Redeposition of these whiskers on the tapers of the slider can lead to a loss of air bearing and head crash. We present a systematic study of the whisker formation mechanism. By injecting fluorescent, spherical polystyrene-latex particles we find that virtually all particles in whiskers are deformed from the original spherical shape. This deformation indicates that particles must pass through the interface before they are collected in the whiskers. Whiskers grow at the tip and not at the base, and form an extension of the air bearing surface. Presence of liquid lubricant on the disk is necessary to form whiskers. The viscosity of the lubricant significantly affects whisker morphology and growth rate. The lower the viscosity, the faster the whisker growth, the shorter the life of the whisker, and the longer and thinner the whisker