HK1084769B - Air-bearing design with particle rejection features - Google Patents

Description

Air bearing structure with particle rejection features

Technical Field

The present invention relates to the field of air-bearing sliders, such as for hard disk drives. In particular, the present invention relates to an air bearing structure for a slider that helps deflect particles from interacting with the slider circuit.

Background

The magnetic hard disk drive stores user data in one or more rotating disks. Data is recorded and read by the magnetic head element. Each head element is embedded on a small slider (typically 1.25mm x 1mm x 0.3mm) that flies above the top of the disk at a pitch of less than 10 nm. This spacing or "flying height" is important for recording density because in prior art constructions the flying height of the head is inversely proportional to the recording density. The flying height is typically maintained by an automatic air bearing formed between the rotating disk and an Air Bearing Surface (ABS) etched on the adjacent slider surface. The performance and reliability of hard disk drives critically depend on the maintenance of the fly height stability. Small sized debris and other contaminants (in the tens of microns range) within the disk drive can pass under the ABS, changing the flying height and causing bit error rates. Debris comes from external sources or may be generated due to movement of the hard disk components. It can cause the slider to hit the disk, thereby causing data loss. Furthermore, if such debris is metal, it can cause a reduction in the electrical operability of the disk drive. Accordingly, there is a need in the disk drive industry for an air bearing surface structure that includes particle deflection characteristics that facilitate deflecting particles from critical magnetic head elements.

Drawings

FIGS. 1a and 1b illustrate a prior art hard disk drive;

FIG. 2 illustrates how particles are embedded between the magnetic head and the disk in a prior art disk drive;

FIG. 3 illustrates a typical air bearing surface structure configured with a long compressed length and corresponding particle flow direction;

FIG. 4 illustrates the effect on particles when trenches are employed in the slider structure;

FIG. 5 illustrates one embodiment of the present invention having an air bearing surface structure with particle deflection features; and

fig. 6a and 6b illustrate another embodiment of the present invention having an air bearing surface structure with particle deflection features.

Detailed Description

Fig. 1 shows a typical hard disk drive. A spindle motor 102 rotates the disk 101 while a magnetic head 103 is controlled to fly above the disk by a Voice Coil Motor (VCM) driven drive arm (head gimbal assembly) 104. Typically, a voice coil motor is used to control the drive arm through a magnetic hard disk that is centered around a spindle motor. In the prior art, microactuators are now used to fine-tune the head position due to the inherent error (dynamic play) present in positioning the head solely by the VCM. This results in a smaller recordable track width, which in turn increases the density or Track Per Inch (TPI) value of the hard disk drive. FIG. 1b is a more detailed view of the illustrated elements of FIG. 1 a.

As mentioned above, one of the most detrimental phenomena to data integrity is hard particles embedded on the disc, since during the embedding process there is a possibility of scratching the disc, thereby causing data bits to be lost. In addition, the magnetic head element may be gradually damaged as the magnetic head flies past the particles. Figure 2 shows one way of embedding particles in a disc. As shown in fig. 2, the particle 201 may be wedged between the slider 202 and the disk surface 203. This wedging action causes a so-called "compression length" increase for the ABS of the slider.

Such compressed length is shown in fig. 3. Currently used ABS structures have a large air bearing area at the leading portion 300 of the slider (e.g., leading pad 301). This is required to provide a large tilt angle for an ABS structure with PDLC pads (i.e., pads made of diamond-like carbon). The large area means a long compression length and causes more compressive stress on the pellet causing the pellet to become wedged into the disc. Typical sizes of these particles found in a faulty drive are in the range of 0.1 μm-0.5 μm, which corresponds to the pitch at the leading edge of the slider.

It is highly advantageous to reduce or eliminate this wedging action. In one embodiment of the present invention, the wedging action is reduced by introducing a separation gap or groove in the ABS structure. This reduces the compressive stress and at the same time acts as a conduit to deflect particles away from under the ABS.

FIGS. 4 and 5 illustrate one embodiment of a particle deflection feature on an advanced ABS structure. As shown in FIG. 5, this particular ABS structure has a groove 501 disposed in a leading portion of the ABS 502. These grooves are aligned with respect to the slider 500 (fig. 4) to provide an easier path for particles to flow out. The configuration of the illustrated trenches is generally parallel to the width of the slider 506 (FIG. 5). This configuration is particularly helpful in achieving the objectives detailed above, since as the slider rotates around the disk, the particles are now forced to move in a direction that is inherent to the separation momentum of the disk and particles. Thus, the particles move through the grooves in a more efficient manner than with other structures. In this embodiment, the width of the trench is 25 μm to 40 μm and is defined by the resolution in the photolithography process for fabricating the slider. In this embodiment, the depth of the trench 504 is the same as the shallow step depth 503 in front of the leading portion 505 of the slider. This shallow step provides for initial compression of the incoming air. The depth of this shallow step may be on the order of 0.1 μm.

The present invention is not limited to the number of grooves and the angle formed with respect to the width of the slider. This feature will help reduce the compressed length and provide particle deflection, so long as there are one or more grooves that are generally parallel to the width of the slider.

Fig. 6 shows a further possible embodiment of the invention. FIG. 6a shows an ABS structure having a groove 601 located in the trailing edge pad 603 and the leading edge portion of the ABS 602. FIG. 6b shows four separate grooves in the leading portion of the ABS.

While the invention has been described with reference to the described application, the description of the preferred embodiment is not to be taken in a limiting sense. It is to be understood that all aspects of the present invention are not limited to the specific depictions, configurations or dimensions set forth herein which depend upon a variety of principles and variables. Various modifications in form and detail of the disclosed apparatus, as well as other modifications of the present invention, will be apparent to persons skilled in the art upon reference to the present disclosure. It is therefore contemplated that the appended claims will cover any such modifications and variations of the described embodiments as falling within the true spirit and scope of the present invention.

Claims (13)

1. An air bearing slider comprising:

a slider body defined by a leading edge, inner and outer edges extending longitudinally along the slider body, and a trailing edge, the slider body including an air bearing surface including a leading portion and a stepped region extending from the leading edge of the slider to the leading portion of the air bearing surface, the leading portion including a groove in the leading portion extending from the inner edge of the leading portion to the outer edge of the leading portion.

2. The air bearing slider of claim 1 wherein the width of the channel is sufficient to deflect particles as the slider moves relative to the rotating disk.

3. The air bearing slider of claim 1 wherein the width of the trench is 25 μm to 40 μm.

4. The air bearing slider of claim 1 wherein the depth of the channel is equal to the depth of the land area.

5. The air bearing slider of claim 1 wherein the air bearing surface further comprises a back pad disposed proximate the trailing edge of the slider, the back pad further comprising a groove in the back pad extending from the inner edge of the rear portion to the outer edge of the leading portion.

6. An air bearing slider for a disk drive comprising:

a leading edge and a trailing edge; and

an air bearing surface comprising at least two main rails and a leading portion, wherein the leading portion comprises at least one set of grooves substantially parallel to the width of the slider.

7. The air bearing slider of claim 6 wherein the rails are sufficiently wide to deflect particles as the slider moves relative to the rotating disk.

8. The air bearing slider of claim 6 wherein the width of the trench is 25 μm to 40 μm.

9. The air bearing slider of claim 6 wherein the air bearing surface comprises a shallow step between the leading portion and the leading edge of the slider, and wherein the depth of the channel is equal to the depth of the shallow step.

10. A disk drive, comprising:

a disk connected to the spindle motor;

an actuator;

a slider, comprising:

a leading edge and a trailing edge; and the air bearing surface includes a leading portion;

at least two main rails; and

at least one set of grooves in the leading portion and generally parallel to the width of the slider.

11. The disc drive of claim 10 wherein the track is wide enough to deflect particles as the slider moves relative to the rotating disc.

12. The disc drive of claim 10, wherein the width of the groove is 25 μm to 40 μm.

13. The disk drive of claim 10 wherein the air bearing surface comprises a shallow step between the leading portion and the leading edge of the slider, and wherein the depth of the trench is equal to the depth of the shallow step.