TOF-SIMS analysis of perfluoropolyether lubricant smear transferred from disk surface following laser heating

The structural and molecular weight changes of perfluoropolyether lubricant picked up following laser heating in heat-assisted magnetic recording (HAMR) were analyzed using time-of-flight secondary ion mass spectrometry. The molecular weight of the picked up lubricant molecules increase, as the low-molecular-weight molecules decompose owing to laser heating and readily evaporate. The dissociation starts from the end groups of the lubricant molecules at a relatively low heating temperature, and the dissociation of longer hydrocarbon terminal elements occurs with increasing temperature. It is estimated that the decomposition of the ether bond of the main chain also occurs when the temperature further increases. These dissociated lubricant elements are picked up by the pin surface during laser heating. Overall, the results presented herein suggest that the chemical and thermal stability of the hydrocarbon end groups of the lubricants should be improved to reduce the rate of depletion of the lubricant film and lubricant pickup by laser heating in HAMR.