Hard-particle-induced physical damage and demagnetization in the head-disk interface

Abstract

Test stand experiments were performed in which 44 μm stainless steel particles and 0.3 μm alumina particles were introduced at the head-disk interface (HDI) of hard disk drives (HDD), and their damage to the HDI was observed and evaluated. An Olympus HDI reliability tester was used to fly the sliders at different radii. Optical microscopy, atomic force microscopy (AFM) and magnetic force microscopy (MFM) were used to examine the physical and magnetic conditions of the sliders and the disks after the particle experiments. The results showed that both particle types were able to produce scratches and demagnetization but in very different ways. The alumina particles could become entrapped in the HDI to cause physical damage to both the sliders and disks, whereas the larger stainless steel particles could not get into the HDI. For the alumina particles plastic deformation and high temperatures occur simultaneously to cause demagnetization when a particle-induced scratch is formed. Stainless steel particles can induce high-speed slider/disk contact and physical damage to the slider’s trailing edge through their contributions to flying instability.