Multidentate functionalized lubricant for ultralow head/disk spacing in a disk drive

Abstract

As areal density in disk drive technology is marching towards the Tbit∕in.2 mark, the slider-to-disk spacing will be required to be within only a few nanometers. Coupled with very high slider velocities (>40m∕s), this leads to extremely high shear stresses on the nanometer-thin lubricant film at the disk surface. As a result, the lubricant film tends to exhibit local redistribution on a micrometer lateral level, decreasing the overall clearance and impacting the integrity of the interface. This paper describes a different approach to functionalized lubricant, where in addition to functional groups placed at the end of the chain, additional attachment moieties are introduced within the main polymer chain. The benefits of this approach is twofold: it increases adhesive interaction with the disk surface, therefore increasing the effective surface viscosity, while at the same time “tying” down the free backbone length for increased clearance. Fabrication, characterization, and performance data obtained on actual magnetic disks will be described.