Contact and temperature rise of thermal flying height control sliders in hard disk drives

Contact and interfacial temperature rise upon slider-disk contact in hard disk drives is investigated using thermal flying height control (TFC) sliders. To achieve contact, the heater element of the TFC slider is energized with constant and square wave voltage input profiles with increasing bias. The temperature rise during slider-disk contact is estimated from the resistance change at the read element using auxiliary calibration measurements. Laser Doppler vibrometer measurements show that vertical gimbal vibrations occur if the power input to the heater exceeds a critical level, seemingly related to slider-disk contact. During contact, the same frequencies occur in the spectrum of the resistance of the read element and the vertical gimbal velocity. Furthermore, it is found that the gimbal is excited at additional frequencies for a square wave heater input profile compared to a constant heater input profile.