M.S. Thesis Presentation by Daisuke Yano

(Dr. Steven Danyluk, advisor)

"Application of a Contact Potential Difference Probe to Detection of Nano-Meter Thick Lubricant on a Hard Disk"


This research is the outgrowth of prior work applying the scanning contact potential difference (CPD) probe as a non-destructive wear monitor for the hard disk. The prior work showed that the scanning CPD probe can detect a geometrical imperfection such as a scratch on a non-lubricated hard disk in order of 0.25 mm in depth. The present work focuses on the CPD probe signal characteristics of a nano-meter thick lubricant film on the hard disk. The dielectric properties of the lubricant changes the surface characteristics of the hard disk and the probe’s response to the change was observed.

The experiments included a proof-of-concept that the scanning CPD probe can detect a nano-meter thick lubricant film on a hard disk, and relate signal responses to varying scanning velocity, probe separation height, and lubricant film thickness were obtained. These results were then compared to the analytical model in order to quantify the scanning CPD probe characteristics.

The result showed that the scanning CPD probe can detect a 3 nm thick lubricant film with spatial resolution of less than 0.6 mm. The experimental data were compared to an analytical model. The scanning CPD probe output showed a linear relationship with scanning velocity, exponential relationship with probe separation height, and little dependency on lubricant film thickness.