Head, head suspension assembly, and disk drive provided with the same

According to an embodiment, a head includes a slider and a head portion on the slider. A facing surface of the slider includes a negative-pressure cavity defined by a recess in the facing surface, a leading step portion on an upstream side of the negative-pressure cavity, a pair of side portions extending in a first direction from the leading step portion, a trailing step portion on an outflow side of the negative-pressure cavity, a pair of skirt portions extending in the first direction from the side portions toward the outflow end of the slider, and an enclosure step portion continuously arranged along an outflow end edge and opposite side edges of the facing surface from the trailing step portion to opposite sides of the skirt portions and outsides of the side portions and formed deeper than the skirt portions and shallower than the negative-pressure cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-146796, filed Jun. 19, 2009, the entire contents of which are incorporated herein by reference.

BACKGROUND

One embodiment of the invention relates to a head used in a disk drive such as a magnetic disk drive, a head suspension assembly provided with the head, and a disk drive provided with the head suspension assembly.

2. Description of the Related Art

A disk drive, e.g., a magnetic disk drive, comprises a magnetic disk, spindle motor, magnetic head, and carriage assembly. The magnetic disk is disposed in a base. The spindle motor supports and rotates the disk. The magnetic head writes and reads information to and from the disk. The carriage assembly supports the head for movement relative to the disk. The carriage assembly comprises a pivotably supported arm and a suspension extending from the arm. The head is supported on an extended end of the suspension. The head comprises a slider attached to the suspension and a head portion on the slider. The head portion is constructed including a reproducing head for reading and a recording head for writing.

The slider comprises a facing surface or air bearing surface (ABS) that faces a recording surface of the magnetic disk. The slider is subjected by the suspension to a predetermined head load that is directed to a magnetic recording layer of the disk. When the magnetic disk drive is powered, airflow is produced between the rotating disk and slider. Thereupon, a force (positive pressure) to fly the slider above the recording surface of the disk acts on the facing surface of the slider, based on the principle of air lubrication. By balancing this flying force and head load, the slider is flown above the recording surface of the disk with a gap therebetween. There is known a disk drive in which a negative-pressure cavity or groove producing dynamic pressure is formed near the center a facing surface of a slider, in order to prevent fluctuation of the flying height of the slider.

Specifically, this slider comprises a negative-pressure groove in a central part of an ABS, leading pad on the inflow end side of the slider, side pads extending from the leading pad toward the outflow end, and skirt portions extending from the side pads, individually, and a magnetic head is disposed on the trailing pad (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2008-16068).

If the pressure within the disk drive with the magnetic head constructed in this manner is reduced by change of environment or the like, the flying height of the head may be reduced so that the head touches down or contacts a surface of a disk, in some cases. If the magnetic head contacts the disk, it vibrates and repeats touchdown and takeoff. Consequently, there is a possibility of the head being finally adhered to the disk surface.

DETAILED DESCRIPTION

Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, a head comprises: a slider comprising a facing surface configured to face a surface of a rotatable recording medium, and configured to fly by airflow produced between the recording medium surface and the facing surface; and a head portion on the slider and configured to perform information processing for the recording medium, the facing surface of the slider comprising a negative-pressure cavity defined by a recess in the facing surface, a leading step portion on an upstream side of the negative-pressure cavity with respect to the airflow, a pair of side portions extending in a first direction from the leading step portion toward an outflow end of the slider, a trailing step portion on an outflow side of the negative-pressure cavity with respect to the airflow, a pair of skirt portions extending in the first direction from the side portions toward the outflow end of the slider and formed deeper than the side portions, and an enclosure step portion continuously arranged along an outflow end edge and opposite side edges of the facing surface from the trailing step portion to opposite sides of the skirt portions and outsides of the side portions and formed deeper than the skirt portions and shallower than the negative-pressure cavity.

According to another aspect of the invention, a disk drive comprises: a disk recording medium; a drive section configured to support and rotate the recording medium; a head comprising a slider, which comprises a facing surface configured to face a surface of the rotatable recording medium and is configured to fly by airflow produced between the recording medium surface and the facing surface, and a head portion on the slider and configured to perform information processing for the recording medium; and a head suspension configured to support the head for movement relative to the recording medium, the facing surface of the slider comprising a negative-pressure cavity defined by a recess in the facing surface, a leading step portion on an upstream side of the negative-pressure cavity with respect to the airflow, a pair of side portions extending in a first direction from the leading step portion toward an outflow end of the slider, a trailing step portion on an outflow side of the negative-pressure cavity with respect to the airflow, a pair of skirt portions extending in the first direction from the side portions toward the outflow end of the slider and formed deeper than the side portions, and an enclosure step portion continuously arranged along an outflow end edge and opposite side edges of the facing surface from the trailing step portion to opposite sides of the skirt portions and outsides of the side portions and formed deeper than the skirt portions and shallower than the negative-pressure cavity.

A first embodiment in which a disk drive according to this invention is applied to a hard disk drive (HDD) will now be described in detail with reference to the accompanying drawings.

FIG. 1shows the internal structure of the HDD according to the first embodiment with a top cover of its housing removed. As shown inFIG. 1, the HDD comprises the housing, which comprises a base12in the form of an open-topped rectangular box and a top cover (not shown). The top cover is fastened to the base by screws so as to close a top opening of the base.

The base12contains a magnetic disk16for use as a recording medium, spindle motor18, magnetic heads40, carriage assembly22, and voice coil motor (VCM)24, ramp load mechanism25, board unit21, etc. The spindle motor18serves as a drive section that supports and rotates the disk. The heads40write and read information to and from the disk. The carriage assembly22supports the heads for movement relative to the disk16. The VCM24rotates and positions the carriage assembly. The ramp load mechanism25holds the heads in a retracted position at a distance from the disk when the heads are moved to the outermost periphery of the disk. The board unit21comprises a head IC and the like.

A printed circuit board (not shown) is attached to the outer surface of a bottom wall of the base12by screws. The circuit board controls the operations of the spindle motor18, VCM24, and magnetic heads40through the board unit21.

The magnetic disk16comprises magnetic recording layers on its upper and lower surfaces, individually. The disk16is fitted on a hub (not shown) of the spindle motor18and fixed to the hub by a clamp spring17. The disk16is rotated at a predetermined speed in the direction of arrow B when the spindle motor18is powered.

The carriage assembly22comprises a bearing26, which is fixed on the bottom wall of the base12, and arms32extending from the bearing. The arms32are spaced apart from the surfaces of the magnetic disk16in parallel relation and extend in the same direction from the bearing26. The carriage assembly22comprises suspensions38each in the form of an elastically deformable elongated plate. Each suspension38, which is formed of, for example, a leaf spring, has its proximal end fixed to the distal end of its corresponding arm32by spot welding or adhesive bonding and extends from the arm. Each suspension38may be formed integrally with its corresponding arm32. The arms32and suspensions38constitute a head suspension, and the head suspension and magnetic heads40constitute a head suspension assembly.

As shown inFIG. 2, each magnetic head40comprises a substantially cuboid slider42and read/write head portion44on the slider and is fixed to a gimbal spring41on the distal end portion of each suspension38. Each head40is subjected by the elasticity of the suspension38to a head load L that is directed to a surface of the magnetic disk16.

As shown inFIG. 1, the carriage assembly22comprises a support frame45, which extends from the bearing26in the direction opposite from the arms32. This support frame supports a voice coil47that constitutes a part of the VCM24. The support frame45is made of a synthetic resin and molded integrally on the outer periphery of the voice coil47. The voice coil47is located between a pair of yokes49fixed on the base12. In conjunction with these yokes and a magnet (not shown) fixed to one of the yokes, the voice coil constitutes the VCM24. If the voice coil47is energized, the carriage assembly22pivots around the bearing26, whereupon each magnetic head40is moved to and positioned in a region over a desired track of the magnetic disk16.

The ramp load mechanism25comprises a ramp51, which is disposed on the bottom wall of the base12so as to be located outside the magnetic disk16, and tabs53(FIG. 2) extending individually from the respective distal ends of the reverse conductor38. When the carriage assembly22pivots to its retracted position outside the disk16, each tab53engages with a ramp surface formed on the ramp51and is then pulled up along the slope of the ramp surface, whereupon each magnetic head40is unloaded.

The configuration of the magnetic head40will now be described in detail.FIG. 3is an exemplary perspective view showing the slider of the head,FIG. 4is an exemplary plan view of the slider, andFIG. 5is an exemplary sectional view of the slider.

As shown inFIGS. 2 to 5, each magnetic head40comprises the substantially cuboid slider42. The slider comprises a rectangular disk-facing surface or air bearing surface (ABS)43, inflow end face44a, outflow end face44b, and a pair of side faces44c. The disk-facing surface43faces the surface of the magnetic disk16. The inflow and outflow end faces44aand44bindividually extend at right angles to the disk-facing surface. The side faces44cindividually extend at right angles to the disk-facing surface between the end faces44aand44b.

The longitudinal direction of the disk-facing surface43is defined as a first direction X, and the transverse direction at right angles to it as a second direction Y. The slider42is constructed as a so-dalled femto-slider, measuring 1.25 mm or less, e.g., 0.85 mm, in length L in the first direction X and 1.0 mm or less, e.g., 0.7 mm, in width W in the second direction Y.

Each magnetic head40is constructed as a flying head, and the slider42is flown by airflow C (FIG. 2) that is produced between the disk surface and disk-facing surface43as the magnetic disk16rotates. When the HDD is powered, the disk-facing surface43of the slider42never fails to be opposed to the disk surface across a gap. The direction of airflow C is coincident with a direction of rotation B of the disk16. The slider42is located relative to the surface of the disk16in such a manner that the first direction X of the disk-facing surface43is substantially coincident with the direction of airflow C.

As shown inFIGS. 3 to 5, a negative-pressure cavity or recess54is formed in the disk-facing surface43, ranging from a substantially central part of the disk-facing surface to the outflow end side. The negative-pressure cavity54opens toward the outflow end face44b. A thickness H of the slider42is set to, for example, 0.23 mm, and the depth of the cavity54to 800 to 1,500 nm, e.g., to 1,500 nm. The negative-pressure cavity54can produce a negative pressure on the central part of the disk-facing surface43at every feasible yaw angle for the HDD.

A substantially rectangular leading step portion50is formed at the inflow end portion of the disk-facing surface43. The leading step portion50projects above the bottom surface of the negative-pressure cavity54so as to be one level (e.g., 100 nm) lower than the disk-facing surface43and is located on the inflow side of the cavity54with respect to airflow C.

The disk-facing surface43comprises a pair of side portions46that extend along its side edges and are opposed to each other with a space therebetween in the second direction Y. These side portions46project above the bottom surface of the negative-pressure cavity54. The side portions46extend from the leading step portion50toward the downstream end. About one half of each side portion46on the outflow end side is wider (in the second direction) than the other half on the inflow end side.

The leading step portion50and side portions46are disposed symmetrically with respect to a central axis D of the slider42and form a substantially U-shaped structure as a whole, closed on the upstream side and opening downstream. The leading step portion50and side portions46define the negative-pressure cavity54.

In order to maintain the pitch angle of each magnetic head40, a leading pad52that supports the slider42by means of an air film is formed protruding from the leading step portion50. The leading pad52continuously extends across the width of the leading step portion50in the second direction Y and is offset downstream from the inflow end face44aof the slider42.

A side pad48is formed on each side portion46so as to connect with the leading pad52. The leading pad52and side pads48are substantially flat and form the disk-facing surface43.

A first recess56aand second recess56bare continuously formed in each side pad48. The first and second recesses56aand56bopen toward the inflow end of the disk-facing surface43as well as toward the magnetic disk surface. Each of the recesses56aand56bhas a rectangular shape defined by a pair of side edges extending substantially parallel to the first direction X and a bottom edge that connects respective extended ends of the side edges and extends substantially parallel to the second direction Y. The second recess56bis one level deeper than the first recess56a.

The disk-facing surface43of the slider42is formed with a pair of skirt portions57, which individually extend straight in the first direction X from the side portions46toward the outflow end of the slider. The skirt portions57are formed deeper than the side portions46and project above the bottom surface of the negative-pressure cavity54. When compared to the disk-facing surface43, each skirt portion57is formed at a depth of 100 to 200 nm, e.g., 100 nm.

The slider42comprises a trailing step portion58formed at the outflow end portion of the disk-facing surface43with respect to the direction of airflow C. The trailing step portion58projects above the bottom surface of the negative-pressure cavity54, and the height of its projection is equal to that of the leading step portion50. In other words, the trailing step portion58is formed so that its depth below the disk-facing surface43is equal to that of the leading step portion50, that is, at 50 to 250 nm, e.g., 100 nm. The trailing step portion58is located on the downstream side of the negative-pressure cavity54with respect to the direction of airflow C and substantially in the center of the disk-facing surface43in the second direction Y. Further, the trailing step portion58is slightly offset from the outflow end face44bof the slider42toward the inflow end face44a.

As shown inFIGS. 3 to 5, the trailing step portion58has a substantially cuboid shape of which two upstream corners are chamfered. The trailing step portion58has an upper surface opposed to the surface of the magnetic disk16.

A trailing pad60that supports the slider42by means of an air film protrudes from the upper surface of the trailing step portion58. The trailing pad60is formed flush with the leading pad52and side pads48, and its surface constitutes the disk-facing surface43.

The trailing pad60comprises a substantially rectangular base portion62and a pair of wing portions64extending in the second direction Y from the base portion to opposite sides. At the trailing step portion58, the base portion62is disposed on the central axis on the outflow end side and located substantially in the center in the second direction Y. The wing portions64individually extend in the first direction X from the opposite ends of the base portion62toward the upstream end of the slider42.

As shown inFIGS. 3 to 5, the disk-facing surface43of the slider42comprises an enclosure step portion70that is substantially U-shaped as a whole. The enclosure step portion70extends along the opposite sides of the trailing step portion58, outside the side portions46, and along the opposite sides of the skirt portions57and cover the rear end and opposite side edge portions of the disk-facing surface on the outflow end side. The enclosure step portion70is continuously arranged along the outflow end edge and opposite side edges of the slider42from the trailing step portion58to the opposite sides of the skirt portions57and the outsides of the side portions46. The enclosure step portion70is formed deeper than the skirt portions57and shallower than the negative-pressure cavity54and at a depth of, for example, 230 nm.

The enclosure step portion70comprises two first portions70a, two second portions70b, and two third portions70c. The first portions70aextend in the second direction Y from the trailing step portion58to the opposite side edges of the slider42. The second portions70bextend in the first direction X along the side edges of the slider42from the first portions70a, outside the skirt portions57and side portions46, individually. The third portions70cextend in the first direction X from the first portions70ato the side portions46inside the skirt portions57, individually. Each of the first to third portions70ato70cis an elongated rectangular structure of a predetermined width.

Each second portion70bhas such a length d that it extends from the first portion70ato the inflow end of the side portion46corresponding thereto. Each second portion70bis formed flush with its corresponding side faces44cof the slider42. A width T that combines the respective widths of each second portion70band its corresponding third portion70cis adjusted so that the side edge of the third portion70con the side of the negative-pressure cavity54is located in coincidence with or outside that of the corresponding side portion46. A corner between each pair of first and third portions70aand70cof the enclosure step portion70is substantially right-angled.

The head portion44of each magnetic head40comprises a recording element and reproducing element for recording and reproducing information on and from the magnetic disk16. The recording and reproducing elements are embedded in a downstream end portion of the slider42with respect to the direction of airflow C. These elements comprise a read/write gap (not shown) formed in the trailing pad60.

According to the HDD and head suspension assembly constructed in this manner, each magnetic head40is flown by airflow C produced between the disk surface and disk-facing surface43as the magnetic disk16is rotated. Thus, when the HDD is powered, the disk-facing surface43of the slider42never fails to be opposed to the disk surface across a gap. As shown inFIG. 2, the magnetic head40flies in such a tilted posture that the read/write gap of the head portion44is located closest to the disk surface.

In each magnetic head40, the negative-pressure cavity54in the disk-facing surface43of the slider42can produce a negative pressure on the central part of the disk-facing surface43at every feasible yaw angle for the HDD. Further, the enclosure step portion70, which encloses the outsides of the skirt portions57and side portions46and the opposite sides of the trailing step portion58, serves to improve the vibration damping force of the slider42in its rolling direction. Consequently, the vibration amplitude of the magnetic head40can be reduced even when the head touches down or contacts the surface of the magnetic disk16. Thus, the magnetic head can be prevented from being adhered to the disk surface.

The inventors hereof prepared the magnetic head according to the present embodiment and a magnetic head comprising a slider according to a comparative example without an enclosure step portion by which the outflow end side of the slider is enclosed, as shown inFIG. 6, and compared the adhesion properties of these magnetic heads by conducting a touchdown-takeoff test.FIG. 7shows results of the test.

As shown inFIG. 7, the adhesion atmospheric pressure (Δ atmospheric pressure) of the magnetic head of the HDD according to Example 1 was 0.29 atm., indicating an improvement of 42% when compared to the magnetic head of the comparative example. This indicates that properties for adhesion (or takeoff performance) to the medium surface can be considerably improved by means of the magnetic head of the present embodiment even if the average roughness (Ra) of the medium surface is reduced, for example, from 0.3 nm to 0.1 nm for super-smoothness, in order to improve the recording density of the HDD.

The guaranteed atmospheric pressure for a 2.5-inch HDD required of a mobile device, such as notebook computer, is 0.7 atm. (=atmospheric pressure at 3,000-m altitude). If the Δ atmospheric pressure is 0.29 atm., therefore, the vibrating magnetic head (in a Δ atmospheric pressure state) is returned to its original flying posture when the inside of the HDD is restored to normal pressure even after a touchdown (start of contact between the head and medium) is made at 0.7 atm., for example. Thus, the adhesion atmospheric pressure of the magnetic head is essential to the maintenance of the flying stability of the head.

The following is a description of a mechanism in which the magnetic head according to the present embodiment can reduce the adhesion atmospheric pressure (Δ atmospheric pressure). The damping farce produced on the disk-facing surface should be enhanced to suppress vibration produced by the contact between the slider and magnetic disk after the touchdown of the head. In order to reduce the resonance frequencies of the suspension and disk-facing surface that form sources of vibration, therefore, a frequency response analysis is performed for comparison based on specified frequencies of 10, 30 and 50 kHz in the rolling direction, in particular.

FIG. 8shows relationships between roll damping and the ratio between the length d of each second portion70bof the enclosure step portion70in the first direction X and the length L of the slider in the first direction X. As seen fromFIG. 8, the roll damping can be improved at any of the three frequencies by adjusting the length d of the second portion70bto 20 to 60% of the slider length L. Further, damping at 10 kHz is increased by as high as 40% by adjusting the length to 53% (corresponding to the present embodiment).

FIG. 9shows relationships between the roll damping, degree of negative pressure produced, and ratio between the width T of the combination of the enclosure step portion70and second and third portions70band70cand the width W of the slider in the second direction Y. As seen fromFIG. 9, moderate roll damping and degree of negative pressure can be obtained at any of the three frequencies by adjusting the width T of the step portions to 4 to 5% of the slider width W.

FIG. 10shows relationships between the roll damping, degree of negative pressure produced, and ratio between the length d of the first and second portions70aand70bof the enclosure step portion70in the first direction X, that is, the position of the outflow end of the slider, and the length L of the slider in the first direction X. Now let us assume that 0% is set when the respective outflow ends of the first and second portions70aand70bare coincident with the outflow end edge of the slider and that the percentage increases as the outflow ends of the first and second portions are shifted toward the inflow end.

As seen fromFIG. 10, the roll damping can be improved and a moderate degree of negative pressure can be obtained at any of the three frequencies by adjusting the length of the first and second portions70aand70bto 0 to 4.5%, that is, by making the first and second portions extend to the vicinity of the outflow end edge of the slider.

FIG. 11shows relationships between the roll damping, degree of negative pressure produced, and depth of the enclosure step portion70relative to the disk-facing surface. As seen fromFIG. 11, the roll damping can be improved and a necessary degree of negative pressure can be obtained at any of the three frequencies if the depth ranges from 200 to 600 nm.

Thus, it is believed that the enclosure step portion enables a damping effect by the enclosure in the rolling direction of the slider to be combined with a damping effect by the reduction of the height-direction distance between the disk-facing surface and disk surface, so that the vibration amplitude at the time of touchdown is reduced.

The above test results indicate that an appropriate shape of the disk-facing surface of the slider is based on the following conditions. First, the length d of each of the second portions70bon the opposite side edges of the slider should range from the outflow end of the slider to the inflow side of each side portion46. Secondly, the position of the respective outflow ends of the second and third portions70band70cshould only reach an alumina part that constitutes the head portion44. Thirdly, the width T of the second and third portions70band70cshould only reach the cavity-side face of each side portion46. Fourthly, “burrs” produced on the opposite side edges during a manufacturing process for the slider can be removed by forming the enclosure step portion70deeper than the skirt portions and shallower than the negative-pressure cavity. Fifthly, a moderate depth of, for example, 200 to 600 nm may be used on the negative-pressure side, since too small and too large depths cause a negative-pressure loss and insufficient damping, respectively.

According to the present embodiment, as described herein, there may be provided a magnetic head with improved stability and reliability, suppressed in vibration and prevented from being adhered to a recording medium, and a head suspension assembly and a disk drive provided with the head.

FIG. 12shows a magnetic head40of an HDD according to a second embodiment of the invention. In an enclosure step portion70of a slider42, according to the present embodiment, a corner between each pair of first and third portions70aand70cis circular-arc-shaped. Further, both corners of the slider42on the outflow end side are obliquely chamfered.

Other configurations of the magnetic head of the second embodiment are the same as those of the foregoing first embodiment. Therefore, like reference numbers refer to like parts throughout the several views of the drawing, and a detailed description of those parts is omitted. According to the second embodiment, there may also be provided a magnetic head with improved stability and reliability, suppressed in vibration and prevented from being adhered to a recording medium, and a disk drive provided with the head.

The shapes, dimensions, etc., of the leading step portion, trailing step portion, enclosure step portion, and pads are not limited to the embodiments described herein and may be varied as required. This invention is not limited to femto-sliders and may also be applied to pico sliders, pemto sliders, or other larger sliders. The number of magnetic disks used in the disk drive may be increased without being limited to one.