Discharge mechanism for electrostatic fly control

Electrostatic force has been proposed for use in fly height reduction and control. The dominant failure mode is electrical discharge at the head-disk interface (HDI) due to field emission. Ballast resistor films have been used for limiting field emission. We applied this idea to the HDI by depositing a thick coating of diamond-like carbon (DLC) on the slider. A typical slider has 25 Å of DLC and exhibits breakdown voltage of less than 3 V on product media. When the coating thickness was increased to 430 Å, it was sufficient to prevent discharge up to 6 V and allowed approximately 33% clearance reduction without crashing or discharging. The result is in good agreement with fly height modeling, which takes into account the head-disk electrostatic force.