Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2001-11-02
2004-01-06
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235600
Reexamination Certificate
active
06674612
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to magnetic data transducing head sliders of the type supported aerodynamically during operation of a disk drive, and more particularly to such sliders designed to provide sub-microinch transducer flying heights.
In magnetic data storage devices, magnetic data transducing heads are positioned in close proximity to substantially flat recording surfaces of magnetic data storage disks. Each transducing head is movable generally radially with respect to its associated disk. In higher capacity devices, the disks are rotated at high speeds to create an air cushion or air bearing that supports each transducing head at a controlled distance from its associated recording surface. The transducing heads do not contact the disk during data reading and recording operations. When the rotating disk is brought to a halt after such operations, the transducing heads come to rest against the disk, typically along a dedicated landing zone or head contact zone with a surface textured to counteract stiction.
There is an ongoing effort in the magnetic data storage industry to increase the density at which the magnetic data can be stored. One factor that limits storage density is the transducing head flying height, i.e., the distance of the transducer from the recording surface when supported by the air bearing. As discrete data storage areas are placed more closely to one another, the transducer must “fly” closer to the recording surface to distinguish between adjacent magnetic storage areas.
In recent years, head media spacing (i.e., transducer flying heights) on the order of several microinches was considered a remarkable achievement. Further progress is leading to head media spacings under a microinch, and even less than one-half of a microinch or about 12 nm.
The reduction in head media spacing has given rise to several problems which are better understood in light of traditional slider design concepts. In particular, to facilitate slider takeoff and promote its stable aerodynamic support, the slider typically was tapered near its leading edge to promote leading edge pressurization, i.e., an increase in pressure near the leading edge and between the slider and recording surface, sufficient to separate the slider from the recording surface and maintain aerodynamic support.
FIG. 1
illustrates a slider
1
with a tapered leading edge
2
just ahead of a planar air bearing surface
3
. The arrow indicates the direction of media travel relative to the slider, which direction is circumferential in the case of a magnetic disk. Air travels with the disk in the same direction due to frictional drag, and thus encounters the slider first at its leading edge.
As transducer flying heights were reduced, machining the leading edge tapers to the degree of accuracy required became increasingly difficult. The result was an unwanted variation in head media spacing due to variations in fabrication.
Another problem that increases as flying heights diminish is head modulation due to particulate debris contamination. Particles, even sub-micron in size, have become an increasing problem, with particle contamination causing head modulation, in some cases leading to read/write failures.
As a result, tapered or beveled leading edge designs have been supplanted in some cases by stepped designs, e.g., such as shown in
FIG. 2
, showing a recess
4
in a forward edge
5
of the slider
6
, having a depth of 1.5 micrometers to 3.5 micrometers as measured upwardly from an air bearing surface
7
. This is known as cavity level leading edge trim. The longitudinal depth, viewed horizontally in the figure, is selected to control the slider length, which has considerable impact on the flying height at sub-microinch flying height levels. Cavity level leading edge trim can be accomplished with higher precision than forming beveled or tapered leading edges, because the trim can be accomplished by photo lithography rather than machining. An additional recess
8
is formed to provide leading edge pressurization and the resulting aerodynamic lift and the maintenance of the slider. Recess
8
, referred to as step level edge trim, has a depth, upwardly as viewed in the figure, ranging from 0.1 to 0.5 micrometers.
Although this design allows a more consistent fabrication of sliders within stricter tolerance levels, these sliders in use tend to capture particles which subsequently travel beneath the slider and toward the trailing edge, working their way into the wedge formed by the normal incline of the air bearing surface relative to the data recording surface of the disk.
Particle contamination is reduced in slider designs such as that illustrated in
FIG. 3
, in which there is no cavity level leading edge trim; only a step level leading edge trim
9
with a depth, measured upwardly form the air bearing surface
10
, in the aforementioned range of 0.1-0.5 micrometers. This provides leading edge pressurization for aerodynamic lift. While reducing the tendency to capture particles, this approach foregoes the degree of control over slider length that results from cavity level leading edge trim.
Therefore, it is an object of the present invention to provide a magnetic data transducing head slider capable of developing leading edge pressurization without a leading edge taper or leading edge trim.
Another object is to provide a process for fabricating magnetic data transducing head sliders that affords improved consistency and control over head media spacing.
A further object is to provide a magnetic data transducing head slider less susceptible to contamination by particulate debris at the micron and sub-micron level.
Yet another object is to provide a process for fabricating magnetic data transducing head sliders with more consistency and control over slider length, and increased resistance to particle contamination.
SUMMARY OF THE INVENTION
To address these and other objects, there is provided a magnetic data transducing head slider. The slider includes a slider body having a substantially planar air bearing surface with a leading edge, and a trailing edge opposite the leading edge and spaced longitudinally from the leading edge. A barrier is formed over the air bearing surface, near the leading edge and spaced longitudinally from the leading edge. The barrier extends generally transversely along the air bearing surface, and protrudes outwardly from the air bearing surface by a barrier height.
The transducing head slider further includes a magnetic data transducer mounted to the slider body. The barrier height is selected to provide pressurization proximate the leading edge sufficient to aerodynamically lift and support the slider body in spaced apart relation to a magnetic data recording medium, in response to movement of the recording medium relative to the slider body in a selected direction such that an air flow generated by the moving medium encounters the slider body first at the leading edge.
Preferably the barrier also counteracts contamination by micron and sub-micron particles. More particularly, the slider body when aerodynamically supported is inclined relative to the recording surface such that the leading edge, as compared to the trailing edge, is spaced apart from the recording distance by a greater distance. For example, the trailing edge can be flying at a sub-microinch height while the leading edge height exceeds 1 micron. In this case, the barrier preferably protrudes from the air bearing surface toward the recording surface to form a gap with a gap width considerably less than the leading edge height, e.g. about one-half micron. Consequently, micron and sub-micron particles traveling between the leading edge and recording surface toward the trailing edge are encountered by the barrier and thereby prevented from traveling further toward the trailing edge. Typically the transducer is mounted near or along the trailing edge, with the barrier thus protecting the transducer from the particles.
The barrier can comprise a substantially continuous crossbar, elongate in t
Boutaghou Zine-Eddine
Sannino Anthony P.
Larkin Hoffman Daly & Lindgren Ltd.
Niebuhr Frederick W.
Seagate Technology LLC
Tupper Robert S.
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