Lee Kevin Dorius

Air bearing design considerations for constant fly height applications

Various air bearing designs are compared for a typical 3.5-inch disk drive application. The air bearing designs discussed here are machined taper flat (MTF), shaped rail positive pressure, negative pressure, and transverse pressure contour (TPC). The comparisons are based on the results of computer simulations. The strengths and weaknesses of these designs with respect to some of the important design considerations are discussed. The MTF designs are not capable of constant fly height. The shaped rail positive pressure designs, both two-rail and tri-rail, have significantly flatter fly height profiles, tighter fly height tolerances and better performance as compared to the MTF designs. The TPC designs give near constant by height under a wide range of conditions but are very sensitive to manufacturing tolerances and require tighter process controls than other designs do. They also have large skew sensitivity which results in accessing fly height loss no better than that for shaped rail designs. The negative pressure designs have the best overall performance. They permit low gram load for improved head/disk interface reliability and also work well at high gram loads. The negative pressure designs have tighter fly height tolerances, lower crown sensitivity, lower skew sensitivity, and better accessing performance as compared to the other designs discussed here. >

Design tradeoffs for beyond 20 Gb/in.2: Using a merged notched head on advanced low noise media (invited)

Design considerations for areal densities beyond 20 Gb/in.2 are discussed, and in particular a demonstration at 24.8 Gb/in.2 is shown. The demonstrations used a single combined write and read head (Merge, Notched head). In this article we will discuss the tradeoffs in kilobytes per inch (KBPI) and tracks-per-inch in obtaining areal densities at 25 Gb/in.2 densities. The KBPI is limited by both the total signal-to-noise ratio and the nonlinear-transition shift. Simple estimates of the increase in channel performance from class IV partial response (PR4), extended partial response 4 (EPR4), and modified EEPR4, as well as the addition of codes which eliminate bit shift and tribit errors are discussed as large contributors to the increase in the areal density.

Challenges of the head-disk interface for near contact and contact recording

As the magnetic recording areal density approaches 10 Gb/in/sup 2/, the mechanical spacing between the head and the disk is expected to reduce rapidly below 20 nm. This lends to an increase of head-disk interaction which may induce an unacceptable level of interfacial wear. In this study experimental air bearing sliders were designed and fabricated to fly in close proximity or substantial contact with the disk. The durability of the interface decreased with decreasing mechanical clearance. The amount of head and disk wear was determined. The metrology and some of the challenges in maintaining a functional interface are presented.

The challenges beyond proximity head-disk interface

lntsoduction As the areal density for magnetic recording increases towards I O Gb/in’, the mechanical spacing between the head and the disk is expected to reduce rapidly below 20 nm. This leads to an increase of head-disk interaction which may induce unacceptable level of magnetic jitter and wear of the interface. In this study experimental air bearing sliders were designed and fabricated to fly near and below the take-off-hei&t of the disks. The durability of the interface was tested and the challenges in maintaining a functional interface will be discussed.