TOF-SIMS Analysis of Accumulated PFPE Lubricant Smear Following Laser Heating

The structural and molecular weight changes to lubricant picked up following laser heating in heat-assisted magnetic recording (HAMR) were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The intensity of the ion mass fragments depended on the decomposition pathways and changed drastically, as did the average molecular weight of the picked-up lubricant as heating temperature increased. The fragment series formed by the dissociation of end groups with low molecular weights (CH₃O⁺) showed a high intensity at temperatures under 300 °C, whereas at temperatures over 400 °C, the fragments series formed by the dissociation of the end-group component (C₅H₉O₄F₂⁺) increased. Overall, the results presented herein suggest that the chemical and thermal stability of the hydrocarbon terminal ends of lubricants should be improved in order to decrease depletion of the lubricant film and lubricant pickup by laser heating in HAMR.