Perfluoropolyether Lubricant Depletion and Reflow in Hard Disk Drives

Abstract

In this study, the effects of on-track dwell time on a hard disk drive (HDD) multidentate perfluoropolyether media lubricant were investigated. It was found that increasing dwell times increase the magnitude of lubricant depletion to a point, after which the depletion does not increase with increasing dwell time. Light interference with the media and high skew angles were shown to increase depletion. Once the dwell is complete, it was found that the lubricant reflows into the depletion region. This reflow was shown to be accelerated by increasing humidity and temperature. The rates for both depletion and reflow were measured and used to develop a simple model. This model was used to predict the final depletion depth for a sample that experienced a sequence of on- /off- track dwell steps. Experimental verification of this model found that it is reasonably accurate, especially for short dwell times and long off-track reflow periods.