The anatomy of a disk drive, in general, comprises a substantially rectangular housing having a hollow cavity. The cavity is atmospherically sealed and comprises a centrally located spindle motor with at least one magnetic storage disk mounted for rotation thereon. In addition, there is a head stack assembly which essentially positions a flying read/write head transducer carried on a slider over the magnetic storage disk. The slider flies over the disk on a cushion of air created by the rotating disk. The slider is flown over the disk such that an electromagnetic transducing relationship is maintained between the transducer and a magnetic storage medium formed on a facing surface of the disk. Incident to data blocks being written to the disk or read from the disk via the transducer, channel electronics communicates with an external computing environment via an interface.
In order to increase data storage capacity of disk drives, the industry has explored a plurality of options including increasing track densities, increasing flux transition (bit) densities, producing sharper read-back pulses, etc. One enabling common denominator to the aforementioned options is flying sliders at lower relative altitudes over a rotating disk.
Typical sliders comprise a six-sided rectangular shaped ceramic body (e.g. aluminum titanium carbide) having a leading edge, a trailing edge, a pair of side edges extending longitudinally from the leading to the trailing edges, a top surface that is gimbal-mounted to a load beam within a head stack, and an air bearing surface which directly faces the rotating disk during drive operation.
The air bearing surface of the slider body is aerodynamically shaped to essentially fly the slider over the rotating disk in a controlled manner. Generally, the rails of an air bearing surface comprise a distinct planar surface that extends outwardly from the remainder of the air bearing and towards a rotating disk. The rails can be shaped into a plurality of geometries, whereby the desired flying characteristics typically dictate the required geometry. The air bearing further comprises a ramp, or a step, positioned at the leading edge for aiding in relatively fast lift-off as is conventional in contact stop-start operations.
During operation, a slider may be subject to several variables that inhibit the slider to fly in a controlled manner. Specifically, as a head stack assembly moves a slider from inner diameter tracks of the disk to outer diameter tracks of the disk, the linear velocity vector with respect to the slider and disk increases substantially. Furthermore, the linear velocity vector changes direction as the slider traverses the radius of the disk. Therefore, the combined increase in the linear velocity vector and the change in direction of the linear velocity vector cause the slider to fly at a higher relative altitude at the outer disk radial region than at an inner disk radial region.
Ideally, it is desirable to maintain a constant fly height across all disk radii, thereby enabling the slider to fly as low as possible (e.g. 0.5 to 2.0 micro-inches above the average disk surface) without having to account for fly height variations. Thus, a principal constraint in designing air bearing slider surfaces is to dimension and shape the bearing surface such that a constant fly height may be maintained as the slider traverses the disk. Other slider flying characteristics include: pitch, roll, and yaw angle. Pitch is defined as an angle between the air bearing an imaginary line extending tangentially to the disk surface from a trailing edge of the air bearing. Roll is defined as the amount a slider tips laterally as the slider traverses the disk. The yaw angle is an angle between a longitudinal axis of the slider and a data track locus tangent at the slider.
In an effort to maintain a constant fly height, the industry has discovered that crown, which is defined as dimensioning the lengthwise direction of the slider's rails in a convex geometry with respect to the remainder of the air bearing, is virtually immune to angular velocity variations. Thus, a slider that has rails with crown may achieve a flat fly height profile independent of track radii.
However, it is also known that camber, which is a convex rail geometry across the rails, causes detrimental effects such as inconsistent fly height across the disk and increased roll. Therefore, it is desirable to produce sliders with a tightly controlled crown geometry, while minimizing camber.
Currently, crowned air bearing geometries are created by disposing an adhesive on a top surface of the slider (surface opposite to the air bearing surface) such that curing properties of the adhesive exert a deformation force to the slider. This force is sufficient to slightly deform the slider into a second orientation exhibiting crown and minimal camber at the air bearing surface. However, as shown in FIG. 5 hereof, the adhesive is temperature-sensitive and may adaptively change state, thus causing variations in the crown geometry of the air bearing. Slider temperature sensitivity means that a disk drive equipped with a temperature sensitive slider may function satisfactorily until exposed to conditions with temperature variations.
Therefore, with the disk drive industry experiencing technological advances in capacity, in particular maintaining constant flying height as sliders traverse across a rotating magnetic disk, a hitherto unsolved need has remained for a method and apparatus for manufacturing an air bearing with a predefined crown geometry, and minimal camber, and insensitivity to temperature variations.