Structural Changes of Perfluoropolyether Lubricant Accumulated on the Pin Surface During Laser Heating

Structural and molecular weight changes to lubricant picked up the following laser heating in heat-assisted magnetic recording (HAMR) were analyzed using time-of-flight secondary ion mass spectroscopy. The average molecular weight of the disk lubricant increased by laser heating at temperatures over 500 °C and that of the picked up lubricant increased at temperatures over 400 °C. The presence of end-group fragments with low molecular weight (CH
₃
O
⁺
) increases in both the disk and picked up lubricants, whereas at high temperature the concentration of the end-group component (C
₃
H
₇
O
₂
⁺
) decreases in the disk lubricant and increases in the picked up lubricant. Overall, the results presented herein suggest that the chemical and thermal stability of the terminal ends of lubricants should be improved in order to decrease depletion of the lubricant film and the lubricant pickup by the laser heating in HAMR.