Accurate measurement and evaluation of dynamic characteristics of flying head slider for large-capacity fast-access magnetic disk storage

For large-capacity fast-access magnetic disk storage, a flying head slider with less than 0.2 μm spacing has been developed to achieve a high recording density of 62 kbit/mm2. In attaining higher recording density, it is exceedingly important to minimize spacing and suppress fluctuation. Consequently, accurate spacing measurement and evaluation of slider dynamic characteristics become the most important preconditions for achieving high performance equipment. This paper presents a highly accurate method of measuring spacing over a wide frequency range using visible laser interferometry. Methods for evaluating slider dynamic response due to three types of excitation are presented. Good agreement is obtained between experimental and numerical results. It is clarified that this slider system has a highly dynamic performance. Additionally, it is also confirmed that the modified Reynolds equation is quite suitable for predicting slider dynamic response accurately even at very low 0.1 μm spacing.