Air-Bearing Effects on Actuated Thermal Pole-Tip Protrusion for Hard Disk Drives

Abstract

Flying height (FH) control sliders with thermal actuation have been introduced recently in commercial products for compensating the static FH loss and reducing the risk of head-disk contacts. In the research reported here, we investigated the effects of air-bearing surface (ABS) designs on the thermal actuation. We created a three-dimensional finite element model of an entire slider with a detailed read/write transducer structure and conducted thermal-structural coupled-field analysis using velocity slip and temperature jump boundary conditions to formulate the heat transfer across the head-disk interface when a slider flies over a spinning disk. An iteration procedure was used to obtain the equilibrium solutions. Four ABS designs with distinct features were simulated. We defined five measures of merit, including protrusion rate, actuation efficiency, power consumption, pressure peak, and temperature rise of the sensor to evaluate the performance of thermal actuation. It is found that the effect of the pressure is more significant than that of the FH on the heat conduction from the slider to the disk. The efficiencies of three conventional designs decrease as the FHs are continuously reduced. A new ABS design, called “Scorpion III,” is presented and demonstrates an overall enhancement, including virtually 100% efficiency with significantly less power consumption. Transient thermal analysis showed that it requires ∼1–2ms for the temperature to reach the steady-state values, and there is a trade-off between increasing the actuation bandwidth and decreasing the power consumption.