Humidity effects on lubricant transfer in the head-disk interface of a hard disk drive

Abstract

As head-media spacing decreases down to 10nm in the current hard disk drive systems, interaction of lubricant on the disk with a flying slider becomes increasingly important. With this extremely small spacing, environmental conditions such as temperature and humidity influence the interaction in the head-disk interface and lubricant transfer between the disk surface and the slider surface. This paper describes a systematic and quantitative study on humidity effects on the amount of lubricant transfer between the disk surface and the slider surface. The lubricant transfer was proportional to absolute humidity, absolute amount of water in the system, rather than relative humidity alone. Profiles of depleted lubricant layer on the disk surface also showed that the increase in the amount of transferred lubricant was directly related to the increase in the mobility of the lubricant with higher absolute humidity rather than with relative humidity alone.