Etching continuous periodic pattern on a suspension to adjust pitch and roll static attitude

Description

BACKGROUND

Data storage devices such as disk drives comprise a disk and a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and servo sectors. The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system to control the actuator arm as it seeks from track to track.

The components of the head (e.g., read element, write element, fly height actuator, etc.) are typically fabricated on a substrate of a wafer which is then sliced into individual sliders. A slider is coupled to a distal end of a suspension that biases the slider toward the disk surface. The slider comprises an air-bearing surface (ABS) wherein as the disk rotates, an air-bearing is formed between the slider and the disk that counteracts the bias force of the suspension. Accordingly, the head essentially flies just above the disk surface during write/read operations. The suspension is coupled to the actuator arm so that as the actuator arm rotates about the pivot, the slider is actuated radially over the disk surface. The initial geometry of the suspension may cause and undesirable pitch static attitude (PSA) and/or roll static attitude (RSA) at the slider air-bearing surface. Prior art techniques have attempted to adjust the PSA and RSA of the suspension by laser etching sets of parallel lines (horizontal and vertical relative to the length of the suspension). However, further improvement in PSA and RSA adjustment is desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a data storage device in the form of a disk drive according to an embodiment comprising a head actuated over a disk, wherein the head is coupled to an actuator arm through a suspension.

FIG. 1B shows a head coupled to a suspension according to an embodiment.

FIG. 2 shows an embodiment wherein the suspension comprises at least one continuous cycle of a periodic pattern (a square wave in this embodiment) etched on the suspension, wherein a first part of the continuous cycle adjusts a pitch static attitude (PSA) of the suspension and a second part of the continuous cycle adjusts a roll static attitude (RSA) of the suspension.

FIG. 3 shows an embodiment wherein the periodic pattern etched on the suspension comprises a triangle wave.

FIG. 4 shows an embodiment wherein the periodic pattern etched on the suspension comprises a sinusoidal wave.

DETAILED DESCRIPTION

FIG. 1 shows a data storage device in the form of a disk drive according to an embodiment comprising a head 2 actuated over a disk 4, wherein the head 2 is coupled to an actuator arm 6 through a suspension 8. The suspension 8 comprises at least one continuous cycle of a periodic pattern etched on the suspension 8, wherein a first part of the continuous cycle adjusts a pitch static attitude (PSA) of the suspension 8 and a second part of the continuous cycle adjusts a roll static attitude (RSA) of the suspension 8.

FIG. 2 shows an example embodiment wherein the suspension 8 comprises a first outer arm 10A and a second outer arm 10B, and the periodic pattern comprises a square wave 12 etched along only the second outer arm 10B. In one embodiment, the vertical side segments of the square wave 12 provide PSA adjustment and the horizontal top and bottom segments of the square wave 12 provide RSA adjustment.

The periodic pattern such as the square wave 12 shown in FIG. 2 may be etched on the suspension 8 using any suitable technique, wherein in one embodiment the etching is implemented using a suitable laser. In one embodiment, a continuous power is applied to the laser to etch at least one cycle of a periodic pattern on the suspension 8 which in one embodiment improves the accuracy and/or range of the PSA/RSA adjustment as compared to a prior art technique that may use a laser to etch discrete horizontal and vertical lines on the suspension. For example, cycling the laser on/off/on as each discrete vertical line is etched may result in inconsistencies of the resulting pattern, which in turn may reduce the effective PSA/RSA adjustment accuracy and/or range. This inconstancy in the prior art patterns is overcome, in one embodiment, by continuously etching the pattern so as to form at least one cycle of a periodic pattern, such as one cycle of a square wave as shown in FIG. 2. That is, in one embodiment the laser is continuously powered while etching at least one cycle of the periodic pattern, thereby avoiding the inconsistencies that may be caused by cycling the laser power when etching discrete lines as in the prior art.

Any suitable pattern may be etched on the suspension 8, wherein FIG. 3 shows an embodiment where the periodic pattern may comprise a triangle wave 14, and FIG. 4 shows an embodiment wherein the periodic pattern may comprise a sinusoidal wave 16. In addition, in one embodiment, multiple of the periodic patterns may be etched onto the suspension 8. For example, in the embodiment shown in FIG. 2, multiple square wave patterns 12 may be etched onto the suspension 8, such as by etching a square wave pattern 12 on each of the outer arms 10A and 10B. In another embodiment, multiple of the periodic patterns may be etched onto a single one of the outer arms 10A or 10B, wherein each pattern may be spaced apart by any suitable distance. In yet another embodiment, multiple different types of periodic patterns may be etched onto the suspension 8, such as by etching a square wave pattern and a triangle pattern or any other suitable combination of patterns.

In one embodiment, one or more signal characteristics of the periodic pattern may affect the PSA or RSA of the suspension. For example, in one embodiment a cycle of the periodic pattern may be etched on the suspension 8 with a preconfigured period, duty cycle, and/or amplitude in order to adjust at least one of the PSA and RSA of the suspension. In one embodiment, the signal characteristics of the periodic pattern may remain constant over all cycles, and in another embodiment the signal characteristics may be varied over the cycles while etching the periodic pattern. Any suitable technique may be employed to determine the desired periodic pattern and signal characteristics of the periodic pattern, such as by etching different types of periodic patterns with different signal characteristics on different test suspensions 8 and evaluating the resulting PSA and RSA performance. After the desired periodic pattern and signal characteristics are determined for a particular suspension design, the periodic pattern may be etched on the production suspensions employed in the production data storage devices.