Smear and Decomposition Mechanism of Magnetic Disk PFPE Lubricant Film by Laser Heating in Air and Helium Conditions

Abstract

A heat-assisted magnetic recording (HAMR) is being implemented to increase the density of hard disks. However, adhesion of smear to the head slider is a drawback. We investigated a smear generation mechanism under laser irradiation in different environments (air and helium) using a disk coated with perfluoropolyether lubricant D-4OH. The amount of smear was smaller in air than in helium at all temperatures. An analysis of smears at 258°C using time-of-flight secondary ion mass spectrometry (TOF-SIMS) suggested that the end group was oxidatively decomposed and the hydrocarbons were burned. And the differences in the end group/main chain ratio and the hydrocarbon ratio between the two environments were smaller at 540°C than at 258°C. It suggested that the lubricant molecules were thermally decomposed owing to the high temperature. It was observed that there was a small difference in the smear amounts between the two environmental gases at 540°C due to the thermal decomposition of the lubricants, but the presence of oxygen was effective in reducing the amount of smear when the heating temperature was 200–300°C.

Keywords

• hamr
• laser
• environment gas
• smear
• pfpe
• hard disk
• tof-sims