Spinning Effects on the Spreading Profiles in PFPE Nanofilms

As fly height of slider in head-disk interface (HDI) decreases with increasing areal density, the intermittent contacts between head and disk during operation could occur and cause lubricant depletion in the nanofilm. Therefore, the spreading behavior of perfluoropolyether (PFPE) lubricant films is an important consideration in the HDI to maintain long-term reliability of hard disk drives. The spreading behaviors of PFPE monolayer on a spinning disk in operating condition were investigated via optical surface analyzer. A lubricated zone suitable for the study of spreading in a spinning disk was prepared via a special coating technique. L-t plot and convective Cattaneo equation were adopted to analyze the spreading behavior. In case of spinning disk, shear stress by air flow or centrifugal force dominates the spreading characteristics. We developed a mesoscale diffusion equation including convective effects induced by the disk spinning.