Head Wear of Thermal Flying Height Control Sliders as a Function of Bonded Lubricant Ratio, Temperature, and Relative Humidity

Head wear of thermal flying height control sliders is studied experimentally by (a) comparing the touch-down power before and after a wear test consisting of 300 consecutive touch-down cycles, (b) examining scanning electron microscopy (SEM) images, and (c) investigating atomic force microscopy (AFM) measurements of unworn and worn heads. The effect of bonded lubricant ratio, relative humidity, temperature, and heater power on head wear is investigated. The experiments were carried out on a commercial load/unload tester inside an environmental test chamber. We conclude that (a) head wear increases with increasing bonded lubricant ratio, (b) temperature has a minor effect on head wear for the temperature range of 30–50 °C, (c) head wear increases with decreasing relative humidity, and (d) head wear increases with increasing heater power during the wear test. SEM images show wear of the write shield for changes in touch-down power typically larger than 6 mW. AFM measurements show changes in surface roughness of heads with changes in touch-down power as small as 1.3 mW compared to new, unused head. A wear coefficient on the order of 10⁻¹¹ to 10⁻¹³ was estimated.