Effect of substrate and protective coating on the tribological characteristics of optical recording media

To develop a flying-type optical head mounted on a slider with flying height below 100 nm for Near Field Recording (NFR) application where removability of the media is required, plastic media is preferred because of their manufacturing cost effectiveness. In this work the effects of substrate material, carbon protective coating, and lubricant on the tribological characteristics of the slider/media interface were investigated. For the substrate, glass, engineering plastic (PEEK), and polycarbonate (PC) were used. A thin carbon protective layer and a lubricant layer were deposited on the substrates. The tribological characteristics of carbon and lubricant layers were evaluated using an Atomic Force Microscopy (AFM). Also, the flyability test, drag test, Contact-Start-Stop (CSS) test, and load/unload test were performed for each substrate while monitoring the friction as well as acoustic emission signals. It was found that the flyability was the key factor that affected the durability of the disks. As for the carbon coating, better performance was observed in the order of a-C, a-C:H, and a-C:N. Finally, 5 nm lubricant thickness was better than 2 nm lubricant thickness in terms of durability. The results of this work are expected to serve as the basis for developing an optical media with high durability in NFR application using a flying slider.