Critical issues on pass-wear durability for CoCr perpendicular flexible disks

Abstract

This paper describes the relation between pass-wear durability and medium tribological factors, including surface roughness, mechanical and chemical properties of CoCr and overcoat layers, lubrication and medium flexural rigidity. CoCr and overcoat layers were sputter deposited on various base films. Pass-wear durability was evaluated by using a single-sided 3.5″ flexible disk drive. CoCr wear strongly depends on the surface roughness and mechanical strength. The wear resistance is proportional to the tensile strenght of the CoCr films, in accordance with Archard's adhesive wear theory. The pass-wear durability is improved by surface treatments, including lubrication and overcoat application. A surface active agent is effective to increase the pass-wear durability, because lubricant affinity to the overcoat surface is improved. Furthermore, pass-wear durability is strongly influenced by medium flexural rigidity. By optimizing these tribological factors. sufficient pass-wear durability for practical use (more than 10 million passes) can be obtained.