Duplex reactive fluorocarbon films with spin-off resistant characteristics

Abstract

As a group, fluorocarbons are by far the most common disc lubricants used in rotating storage memories. They possess excellent properties including chemical inertness, low surface tension, low volativity and moisture repellancy. They have, however, one serious limitation: the continual loss of lubricant from the rotating disc surface due to centrifugal migration. This leads to increased head to disc interference and may eventually cause complete failure of the head-disc assembly (HDA) unit. A unique solution to this problem is described in this paper. It was arrived at by combining two fluorocarbon films, one chemically and permanently bonded to the media surface, the other a normally applied lubricant which is overcoated onto the primed disc surface. These duplex films retain the excellent lubricant properties of the single film but dramatically reduce the lubricant loss by spinoff. Experimental data for duplex and single lubricant systems are presented including spinoff curves, stiction and friction measurements and start-stop wear testing. Finally, a mechanism based upon polymer chain entanglement is proposed to explain the retention of lubricant in this newly discovered system.