Seong-hoon Kim

Head and media design considerations for reducing thermal asperity

Abstract Recent use of magnetoresistive (MR)/giant-magnetoresistive (GMR) heads in disk drives requires tighter control on particle contamination that may generate thermal asperities at the head/disk interface. In this study, the effects of slider air bearing surface (ABS) design and media on TA reduction capability are investigated. The motion of particles at the head/media interface is simulated numerically. Drive level TA tests are performed using a particle injection chamber. It is observed that a new ABS design, that has an aerodynamic U-shaped rail and a central airflow passage, is beneficial in reducing the particle contamination on the slider. Scratch-resistance of the media surface is correlated to TA reduction capability of the media; more scratch-resistant media produced less TA. On the other hand, the adhesion properties of the media have minor effects on TA reduction, as the particles that usually generate TA in a drive are too small to spin off the media.

The reduction of air-borne noise in hard disk drive

An air-borne noise should occur when a platter (disk) is rotating under high rpm in hard disk drive. Here the air-borne noise includes not only an interaction between fluids itself, but also forced vibration of structures in contact with the flow. Nearly all problems of flow-generated noise, the energy source for sound production is some form of flow unsteadiness. An essential ingredient of flow unsteadiness is turbulence and vorticity. In this paper the thickness of Ekman boundary layer was analyzed, and with this theory a noise reduction was carried out by an optimized spacing between upper platter and cover housing.