Effect of relative humidity, disk acceleration, and dwell time on tribocharge build-up at a slider disk interface

High performance disk drives require high spindle speed. The spindle speed of typical hard disk drives has increased in recent years. The increasing disk velocity leads to increasing disk acceleration and slider-disk interaction. The slider-disk interaction in CSS (contact-start-stop) mode is an important source of particle generation and tribocharge. Charge build-up in the slider-disk interface can cause ESD (electrostatic discharge) damage and lubricant decomposition. We measured the tribocurrent/voltage build-up generated at increasing disk acceleration. In addition, we examined the effects of relative humidity and dwell time on the tribocharge build-up. We found that the tribocurrent/voltage was generated during pico-slider/disk interaction and its level was about 3-16 pA and 0.1-0.3 V, respectively. Tribocurrent/voltage build-up was reduced with increasing disk acceleration. Higher humidity conditions (75 -80%) yielded lower levels of tribovoltage/current. Dwell time affected the charge build-up at the slider-disk interface. The degree of tribocharge build-up increased with increasing dwell time