Flyability Failures Due to Organic Siloxanes at the Head/Disk Interface

Abstract

With the trend toward lower flying heights and increasing storage capacity in the magnetic recording industry, the role of contamination and methods to counteract its deleterious effects are expected to become important. One area where the role of contaminants is expected to increasingly affect reliability is long term flyability. This is because volatile and semi-volatile materials in the drive can alter the flying characteristics of the slider during operation because of chemistry at the interface. In this paper, we describe the flyability performance of a head-disk interface system using full body capacitance measurements as a monitor of interface reliability. The principal features observed in flyability tests employing two sources of siloxanes, a model organic compound octamethylcyclotetrasiloxane as well as outgassing from an exposed adhesive tape with a release liner, are described. The deleterious effects of siloxane outgassing that lead to changes in the flying characteristics of the slider and subsequent interface failure are described for disks lubricated with Fomblin Z-dol. Chemical identification of the accumulated material on the slider following flyability testing is described. Strikingly different performance is observed for disks lubricated with the cyclic phosphazene X-1P which shows significantly improved flyability performance. Possible mechanisms that lead to the formation of silica at the head-disk interface for Z-dol based disks and reasons for their absence for an X-1P interface are discussed. [S0742-4787(00)01202-9]