With the increase of recording densities in HDDs, the magnetic spacing, also known by the term of art, “fly height,” between a magnetic-recording head and a recording surface of a magnetic-recording disk has narrowed; and, securing the reliability of the HDD from deleterious head-disk interactions (HDIs) has become an issue of greater concern to engineers and scientists engaged in HDD manufacturing and development. In a HDD, an air-bearing head-slider is used which flies above a spinning magnetic-recording disk at a very small fly height.
As is known in the art, the basic configuration of a prior art head-slider 101 used in a HDD is shown in FIG. 11, which shows a perspective view of such a head-slider 101. The air-bearing surface (ABS) of the head-slider 101 includes: air-bearing portions 102; shallow-recessed surfaces 104, which are slightly recessed from the air-bearing portions 102; and, a deep-recessed surface 105, which is etched deeper than the shallow-recessed surfaces 104 from the air-bearing portions 102. The air-bearing portions 102 include: a pair of left and right air-bearing portions 102a and 102b, which occupy rear portions of the leading-end shallow-recessed surface 104a; and, a center pad 102c including a magnetic-recording head 103 disposed in proximity to the trailing edge of the head-slider 101. The deep-recessed surface 105 is partially surrounded by the leading-end shallow-recessed surface 104a, the leading-end air-bearing portions 102a and 102b and the side shallow recessed rails 104b. In this configuration, while the stepped air-bearing action by the shallow-recessed surfaces and the air-bearing portions generates lift to lift the head-slider off the magnetic-recording disk, a negative pressure is also generated by the deep-recessed surface 105. By using both positive and negative pressures, a suitable air bearing stiffness may be provided for stable flight of the head-slider 101 that serves to maintain the magnetic-recording head 103 of the center pad as the nearest point to the magnetic-recording disk. Thus, this configuration may be said to be offer high performance for the head-slider 101. Currently, two kinds of head-sliders are widely used: one has length Lx=1.25 millimeters (mm), width Ly=0.7 mm, and thickness Lz=0.23 mm; and, another has length Lx=0.85 mm, width Ly=0.7 mm, and thickness Lz=0.23 mm.
In a HDD employing a head-slider load/unload system, especially if the magnetic-recording disk rotation speed is as high as 7200 rpm, 10 krpm, 15 krpm, or similar high rotation speeds, the head-slider may touch the magnetic-recording disk without developing a lift during load, because the head-slider is dropped onto the magnetic-recording disk at high speed. To prevent damage to both head-slider and magnetic-recording disk, the head-slider must be able to immediately initiate stable flight above the magnetic-recording disk by generating a lift even in such a situation.
Engineers and scientists engaged in HDD manufacturing and development are interested in the design of HDDs that control the fly height and variations in the fly height between the head-slider and the recording surface of the magnetic-recording disk to meet the rising demands of the marketplace for increased data-storage capacity, performance, and reliability.