Electrostatic Force Manipulation Methodology: Principles, Mechanisms, and Setup for Head–Disk Interactions Monitoring

Abstract

To achieve higher hard disk drive areal density, the head–disk clearance had been reduced to $F_{\mathrm {es}}$ ) across the head–disk interface were investigated. It was shown that the distribution of the applied $F_{\mathrm {es}}$ was different for the two setups. This led to further studies of the effects of the $F_{\mathrm {es}}$ distribution on interactions monitoring. The results showed that when an alternating $F_{\mathrm {es}}$ was distributed at the pole region, the magnitude of the electrodynamically excited first-harmonic vibration increased significantly as the gap fly height was reduced. It was very sensitive to spacing change and useful for the head–disk interactions monitoring at the near-contact regime. The second harmonic was found sensitive to head–disk contact. When the alternating $F_{\mathrm {es}}$ was distributed at the slider body, the magnitudes of the first and second harmonics were larger due to larger effective surface area. However, the fly height of the slider body was mainly affected by the protrusion push-up effect, and hence the first and second harmonics showed a reverse trend as compared with the case where $F_{\mathrm {es}}$ was distributed at the pole region. In addition, slider pitch motion was also significantly affected. The effective EFM setup was constructed to demonstrate its effectiveness in head–disk interactions monitoring and contact detection.