Optimization of Asperities for Laser-Textured Magnetic Disk Surfaces

Abstract

Increasing areal densities on the order of I Gbit/in2 in magnetic disk drives demands the use of supersmooth disk substrates which can, however, lead to a severe sticlion problem. A practical solution involves the creation of bumps in a dedicated landing zone near the disk inner diameter using a focused laser beam. The tribological performance of the laser-textured disk depends on the size and number of bumps on its surface. A large number of asperities (bumps) can result in high sticlion force. On the other hand, to prevent plastic deformation, the number of asperities must be greater than a certain number. A statistical contact model has been developed to generate design curves for estimating the critical number of asperities as a function of asperity radius which can prevent both plastic deformation and severe sticlion.