Thin-film magnetic head comprising contact pad including portions of closure and substrate and magnetic recording apparatus comprising the head

A thin-film magnetic head that shows stable read and/or write performances, maintaining the reliability over time by suppressing the wear of the head sufficiently, is provided. The head comprises: a substrate having an element-formed surface and an opposed-to-medium surface; a magnetic head element; an overcoat layer formed on the element-formed surface so as to cover the magnetic head element; a closure provided on the overcoat layer, a surface of the closure being in contact with the upper surface of the overcoat layer; and an element contact pad formed in a sliding-side surface of the head and having a contact surface including a part of the opposed-to-medium surface, a part of an end surface of the overcoat layer and a part of an end surface of the closure, one end of the magnetic head element reaching the contact surface.

PRIORITY CLAIM

This application claims priorities from Japanese patent application No. 2005-230496, filed on Aug. 9, 2005 and Japanese patent application No. 2005-258872, filed on Sep. 7, 2005, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin-film magnetic head that comprises a closure and makes contact with a magnetic recording medium, a head gimbal assembly (HGA) with the thin-film magnetic head and a magnetic recording apparatus with the HGA and the medium.

2. Description of the Related Art

A magnetic disk drive apparatus such as a hard disk drive (HDD) or a flexible disk drive (FDD) is a representative example of the magnetic recording apparatuses, which is portable and lower in price per byte than semiconductor memory. Recently, because the volume of various data becomes larger due to the spread use of the multimedia and the Internet, the magnetic disk drive apparatus is strongly required to have much larger capacity and to be further miniaturized.

In the situation, a contact-type apparatus is worth noting because of its possibility of higher recording density, which, for example, has a loading mechanism for transferring an inserted cartridge including a disk to the predetermined position, a rotary drive mechanism for holding and rotating the disk in the transferred cartridge, a magnetic head device for writing data signals to the rotated disk and reading data signals from it, and a moving mechanism for moving the magnetic head device in the radial direction on the disk.

The magnetic head in the magnetic head device writes and reads data signals in contact with the magnetic disk. A Metal-In-Gap (MIG) head has conventionally used as the contact-type head. However, in order to respond the increasing data storage capacity and the further miniaturization of the magnetic disk drive apparatus, a thin-film magnetic head for an HDD, which inherently meets higher recording density, is being applied to the contact-type apparatus. The thin-film magnetic head for the HDD has a structure suitable for flying on the magnetic disk without contact during read and write operations. Therefore, the simple use of the thin-film magnetic head under the contact condition may cause a significant wear or crash of the head. To avoid the problem, U.S. Pat. No. 6,947,259 proposes the limitation to a predetermined range of the distance between an electromagnetic transducer (magnetic head element) and the contact edge of an overcoat layer. Further, Japanese Patent Publication No. 06-309625A describes a contact-type head for perpendicular magnetic recording with the sliding surface of an antiwear layer.

Furthermore, U.S. Pat. No. 5,142,768 and Japanese Patent Publications Nos. 08-321012A and 06-012622A describe a magnetic head used for a magnetic tape drive etc., which has a bonded protection plate such as a closure block.

However, in the head described in U.S. Pat. No. 6,947,259, the sliding surface of the protective film is still worn largely, and especially when an alumina thick film is used as the protective film, the degree of wear becomes larger than that of the slider substrate. Further, the formation of the thick film with thickness of 50 to 200 micrometers requires significant man-hours. A contact-type head described in Japanese Patent Publication No. 06-309625A has the same kind of problem.

Further, when the “closure-type” magnetic head described in U.S. Pat. No. 5,142,768 and Japanese Patent Publications Nos. 08-321012A and 06-012622A is used for a magnetic disk drive apparatus such as a FDD, the contact edge of the whole magnetic head is rather separated from the contact end of the head element during read and write operations. Therefore, the area of the magnetic disk such as the flexible disk opposed to the end of the head element is bent, then the bending is likely to cause the distance between the end of the head element and the disk surface to be fluctuated. As a result, read and write performances may become unstable.

BRIEF SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a thin-film magnetic head that shows stable read and/or write performances, maintaining the reliability over time by suppressing the wear of the head sufficiently, an HGA provided with this thin-film magnetic head and a magnetic recording apparatus provided with this HGA.

Here, some terms will be defined before explaining the present invention. In a layered structure of the head elements formed on an element-formed surface of a substrate, a component that is closer to the substrate than a standard layer is defined to be “below” or “lower” in relation to the standard layer, and a component that is in the stacked direction side of the standard layer is defined to be “above” or “upper” in relation to the standard layer.

According to the present invention, a thin-film magnetic head is provided, which comprises: a substrate having an element-formed surface and an opposed-to-medium surface; at least one magnetic head element provided on/above the element-formed surface, for writing and/or reading data signals; an overcoat layer formed on the element-formed surface so as to cover the at least one magnetic head element; a closure provided on the overcoat layer, a surface of the closure being in contact with the upper surface of the overcoat layer; and at least one element contact pad formed in a sliding-side surface of the thin-film magnetic head and having a contact surface including a part of the opposed-to-medium surface of the substrate, a part of an end surface of the overcoat layer and a part of an end surface of the closure, one end of the at least one magnetic head element reaching the contact surface.

In this head, it is preferable that at least one of the at least one element contact pad is provided on a central axis of the sliding-side surface expanding in the direction along track. It is also preferable that at least one of the at least one element contact pad is provided in a position that is out of a central axis of the sliding-side surface expanding in the direction along track and is not overlapped with the central axis.

By providing the above-described element contact pad, only the contact surface of the element contact pad can have contact with the surface of the magnetic recording medium in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained.

Furthermore, in the case where the magnetic recording medium is pinched by the two thin-film magnetic heads or by the thin-film magnetic head and the dummy head, the bending of the magnetic recording medium is adjusted to be a predetermined shape. As a result, one end of the magnetic head element and the surface of the magnetic recording medium have a secure contact with each other, therefore, the head can realize stable read and write performances.

Further, in the head according to the present invention, it is preferable that a distance LPfrom the one end of the magnetic head element to the trailing end of a contact region of the contact surface satisfies a conditional expression of 22≦LP≦100, a unit of said distance LPbeing micrometer (μm). Here, in the case that the element contact pad and a magnetic recording medium are in contact with the whole part of the contact surface ranging on the trailing side in relation to the one end of the magnetic head element, the distance LPis a distance between the trailing end of the contact surface and the one end of the magnetic head element.

When the distance LPis 22 μm or more, a secure and favorable wear resistance can be obtained as explained later in detail. And when the distance LPis 100 μm or less, a predetermined reproduction power can be maintained also as explained later in detail.

Furthermore, in the head according to the present invention, at least one contact pad is preferably provided in the opposed-to-medium surface of the substrate. The contact pad causes the degree of the contact between the head and the medium to be decreased, therefore, the wear of the head becomes more suppressed. In the case, it is also preferable that the one element contact pad and the two contact pads are provided in the sliding-side surface of the thin-film magnetic head.

Further, in the head according to the present invention, the closure preferably has a flat or curved cut-surface bordering a sliding-side end surface of the closure at its trailing edge. It is also preferable that the closure has at least one flat or curved cut-surface cutting obliquely across a trailing edge of a sliding-side end surface of the closure.

Further, in the head according to the present invention, the at least one magnetic head element comprises a electromagnetic coil element for writing data signals and a magnetoresistive (MR) effect element for reading data signals. In the case, it is more preferable that the MR effect element is a tunnel magnetoresistive (TMR) effect element.

Further, in the head according to the present invention, preferably, at least one signal electrode used for the at least one magnetic head element is provided on an exposed part of the upper surface of the overcoat layer.

According to the present invention, an HGA (head gimbal assembly) is further provided, which comprises: the above-described thin-film magnetic head, trace conductors for supplying currents to the at least one magnetic head element, and a support structure for supporting the thin-film magnetic head.

According to the present invention, a magnetic recording apparatus is further provided, which comprises; at least one HGA described-above, at least one magnetic recording medium, and a recording and/or reproducing circuit for controlling write and/or read operations of the at least one thin-film magnetic head in relation with the at least one magnetic recording medium.

In the magnetic recording apparatus, it is preferable that the respective sliding-side surfaces of the two thin-film magnetic heads pinch the magnetic recording medium and the respective element contact pads of the two thin-film magnetic heads are positioned not to be opposed to each other. In the case, more preferably, each of the two thin-film magnetic heads has the one element contact pad, and the one element contact pad is provided in a position to be out of respective central axes expanding in the direction along track of the sliding-side surfaces of the two thin-film magnetic heads, in opposite direction to each other, and the one element contact pad is not overlapped with the central axis.

In the just-described embodiment, only the contact surface of the element contact pad can have contact with the surface of the magnetic recording medium in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained. Furthermore, because the bending of the magnetic recording medium is adjusted to be a predetermined shape, one end of the magnetic head element and the surface of the magnetic recording medium have a secure contact with each other, therefore, the head can realize stable read and write performances.

Furthermore, it is more preferable that a spacing DPin the track width direction between the respective two element contact pads of the two thin-film magnetic heads and a distance SPbetween the respective contact surfaces of the two element contact pads satisfy a condition expression of 0.02≦SP/DP≦0.2.

When the ratio SP/DPsatisfies 0.02≦SP/DP≦0.2, the contact condition between the element contact pads and the surface of the magnetic recording medium can be stabilized as explained later in detail. As a result, a predetermined reproduction power can be maintained.

Further, it is also preferable that respective sliding-side surfaces of the thin-film magnetic head and a dummy head pinch the magnetic recording medium, and the dummy head has at least one concave portion provided in a position that is in the sliding-side surface and is opposed to the at least one element contact pad, the at least one concave portion being so large in size that at least a part of the element contact pad can be inserted. In the case, it is more preferable that the thin-film magnetic head has the one element contact pad, and the one element contact pad is provided on a central axis of the sliding-side surface of the thin-film magnetic head expanding in the direction along track.

In the just-described embodiment, only the contact surface of the element contact pad can have contact with the surface of the magnetic recording medium in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained. Furthermore, because the bending of the magnetic recording medium is adjusted to be a predetermined shape, one end of the magnetic head element and the surface of the magnetic recording medium have a secure contact with each other, therefore, the head can realize stable read and write performances.

Furthermore, it is more preferable that a width WPin the track width direction of the one element contact pad, a width WCin the track width direction of the concave portion, and a distance SCbetween the contact surface of the one element contact pad and a sliding-side surface of the dummy head satisfy a condition expression of 0.012≦SC/(0.5*(WC−WP))≦0.1.

When the ratio SC/(0.5*(WC−WP)) satisfies 0.012≦SP/DP≦0.1, the contact condition between the element contact pads and the surface of the magnetic recording medium can be stabilized as explained later in detail. As a result, a predetermined reproduction power can be maintained.

Further objects and advantages of the present invention will be apparent from the following description of preferred embodiments of the invention as illustrated in the accompanying drawings. Some elements have been designated with same reference numerals in the different drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a perspective view schematically illustrating a structure of a main part of an embodiment of a magnetic recording apparatus according to the present invention.

InFIG. 1, reference numeral10indicates a magnetic disk that is included in a disk cartridge11and has a centered hub12to be coupled with a spindle motor. The magnetic disk10may be flexible or rigid, and is formed by stacking magnetic recording layer(s) on one/both side(s) of a disk substrate made of a polymer film, a thin metal foil, a thick nonmagnetic metal such as Al or Al alloys, or a glass.

Also in the figure, Reference numeral13indicates an assembly carriage device for positioning two thin-film magnetic heads30on both tracks on front and rear sides of the disk respectively,18indicates a recording and reproducing circuit for controlling write and read operations of the thin-film magnetic heads30, and19indicates a loading slot to which the disk cartridge11is inserted, respectively. The disk cartridge11has a window and a shutter, though not shown in the figure. When the disk cartridge11is loaded through the loading slot19, the shutter is opened and the surface of the magnetic disk10is exposed, then the thin-film magnetic heads30writes to the disk10and reads from the disk10.

The assembly carriage device13is provided with two drive arms14. These drive arms14are rotatable around a pivot bearing axis16by means of a voice coil motor (VCM)15and stacked in the direction along this axis16. An HGA17is provided on the end portion of each drive arm14. A thin-film magnetic head30is mounted on each HGA17so that the magnetic disk10is pinched by the two magnetic heads. A part of the sliding-side surface of each thin-film magnetic head30is in contact with the front/rear surface of the magnetic disk10during read and write operations. As described later, one of the thin-film magnetic heads30may be a dummy head for stabilizing the contact between the other head and the surface of the disk10.

In the above-described embodiment, the magnetic disk10is included in the disk cartridge11, however, it is also preferable that the center of the magnetic disk is connected to the axis of the spindle motor, and the disk is full-time fixed in the apparatus. Further, in this disk-fixed case, a plurality of the magnetic disks can be stacked in the direction along the axis of the spindle motor accompanied by double or appropriate number of the HGAs and drive arms.

FIG. 2shows a perspective view illustrating an embodiment of an HGA according to the present invention.

As shown inFIG. 2, the HGA17is constructed by fixing the thin-film magnetic head30on an end portion of a suspension20and by electrically connecting one end of a wiring member25to signal electrodes of the head30. The suspension20is mainly constructed of a load beam22, a flexure23with elasticity fixed and supported on this load beam22, a base plate24provided on the base portion of the load beam22, and the wiring member25that is made up of trace conductors and connection pads electrically connected to both ends of the trace conductors, provided on the flexure23. Though not shown in the figure, it is also possible to attach a head drive IC chip at some midpoint of the suspension20.

FIG. 3shows a perspective view schematically illustrating an embodiment of a thin-film magnetic head provided on the end portion of the HGA.

As shown in the figure, the thin-film magnetic head30is provided with a slider substrate31having a opposed-to-disk surface (opposed-to-medium surface)310and an element-formed surface311perpendicular to the surface310, a magnetic head element32formed on/above the element-formed surface311, an overcoat layer33formed on the element-formed surface311so as to cover the magnetic head element32, a closure34bonded on a part of the upper surface330of the overcoat layer33, an element contact pad36formed in the sliding-side surface300of the head30where one end320of the magnetic head element32reaches the contact surface360of the pad36, two contact pads37formed in the opposed-to-disk surface310, and four signal electrodes35used for the magnetic head element32, formed on an exposed part of the upper surface331of the overcoat layer33.

The element contact pad36has the contact surface360with an elliptical shape having a major axis along track, and is provided on the central axis38of sliding-side surface300expanding in the direction along track. That is to say, the element contact pad36is centrally positioned in track width direction. The contact surface360consists of a part of the opposed-to-disk surface310of the slider substrate31, a part of the end surface330of the overcoat layer33, and a part of the end surface340of the closure34. One end320of the magnetic head element32reaches the above-described part of the end surface330of the overcoat layer33. In this embodiment, the contact surfaces of the contact pads37also have an elliptical shape.

By providing the above-described element contact pad36, only the contact surface360can have contact with the surface of the magnetic disk in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained. Further, peripheral corners of the element contact pad36and the contact pads37are chamfered to be made round. The chamfered corners are preventive against damage on the surface of the magnetic disk by contact.

Further, a distance LP(μm (micrometer)) between the trailing end of the contact surface360and the one end320of the magnetic head element32is preferably set to a value satisfying the conditional expression of 22 (μm)≦LP≦100 (μm). The appropriate LPvalue allows a lopsided wear of the element contact pad36to be suppressed sufficiently, and furthermore, the reproduction power of the magnetic head element32remains a required level. Here, the starting point on the magnetic head element side in the definition of the distance LPis a trailing edge in the surface of the one end320of the magnetic head element32, which is exposed from the contact surface360. The above-described conditional expression of the distance LPwill be explained later in detail.

The four signal electrodes35are formed on an exposed part of the upper surface331of the overcoat layer33. In the conventional manufacturing process of a thin-film magnetic head with a closure on the overcoat layer, it is difficult to set up a surface for forming the signal electrodes. However, by forming the signal electrodes on the exposed part of the upper surface of the overcoat layer33, the reliable signal electrodes can be provided without great burden in manufacturing process.

As is obvious, the thin-film magnetic head according to the present invention is not limited to the above-described embodiment. For example, the contact surface of the element contact pad36as well as the contact pads37may have a shape of ellipsoid with the major axis along track width direction, circle or rectangle. Further, the number of the signal electrodes35may be optional though depending on the structure and number of the magnetic head element32or the other elements, and the presence of grounding to the slider substrate31. Some alternatives of the element contact pad will be described later in detail.

FIG. 4shows a cross-sectional view taken along line A-A illustrating a main part of the magnetic head element32inFIG. 3. In the figure, the magnetic head element32and the signal electrode35appear on the same cross-section in convenience. However, for example, the signal electrodes35may be provided in the positions where they do not appear in this cross-section.

As shown in the figure, the magnetic head element32comprises an MR effect element321for reading data signals and an electromagnetic coil element322for writing data signals. Two and two of the four signal electrodes35(only one appears in the figure) are connected to the MR effect element321and the electromagnetic coil element322respectively.

The one ends of the MR effect element321and the electromagnetic coil element322reaches the contact surface360of the element contact pad36. In the thin-film magnetic head30, the contact surface360has contact with the rotated magnetic disk during read and write operations, then the MR effect element321reads by receiving signal fields form the disk and the electromagnetic coil element321writes by applying signal fields to the disk.

The MR effect element321includes an MR multilayer321b, and a lower shield layer321aand an upper shield layer321cdisposed in positions sandwiching the MR multilayer321b. The lower shield layer321aand the upper shield layer321cprevent the MR multilayer321bfrom receiving external magnetic fields as disturbing noises. The lower shield layer321aand the upper shield layer321care formed of, for example, NiFe, CoFeNi, CoFe, FeN, FeZrN or the multilayer of these materials with thickness of approximately 0.5 μm to 3 μm by means of, for example, frame plating technique, respectively.

The MR multilayer321bis preferably a TMR multilayer that is a magnetic field sensitive part utilizing a TMR effect. The TMR multilayer has a main multilayered structure in which a free layer and a pinned layer sandwich a tunnel barrier layer. In this structure, when the direction of the magnetization in the free layer varies according to signal fields, the tunnel current increase or decease due to the fluctuation in the state density of up-spin and down-spin electrons, therefore, the electrical resistance of the TMR multilayer is changed. The measurement of change in the resistance allows weak signal fields to be read.

Generally, a temperature coefficient of the resistance-change ratio has a minus value, and the absolute value is at least one order of magnitude smaller than that of the other MR effect. Therefore, using the TMR multilayer can suppress the generation of abnormal signals (thermal asperity) due to the frictional heat between the MR effect element and the surface of the disk. When the generated thermal asperity is tolerable, the MR multilayer321bmay be a CIP (current in plain)—GMR (giant magnetoresistive) multilayer or a CPP (current perpendicular to plain)—GMR multilayer, each of which can also senses signal fields with very high sensitivity.

The electromagnetic coil element322comprises: a lower magnetic pole layer322aformed of, for example, NiFe, CoFeNi, CoFe, FeN, FeZrN or the multilayer of these materials with thickness of approximately 0.5 μm to 3 μm by means of, for example, frame plating technique; a write gap layer322bformed of, for example, Al2O3, SiO2, AlN or DLC (diamond-like carbon) with thickness of approximately 0.01 μm to 0.05 μm by means of sputtering or chemical vapor deposition (CVD) method; a coil layer322cformed of, for example, Cu with thickness of approximately 1 μm to 5 μm by means of, for example, frame plating; a coil insulating layer322dformed of, for example, a heat-cured resist so as to cover the coil layer322cwith thickness of approximately 0.5 μm to 7 μm; and an upper magnetic pole layer322eformed of, for example, NiFe, CoFeNi, CoFe, FeN, FeZrN or the multilayer of these materials with thickness of approximately 0.5 μm to 3 μm by means of, for example, frame plating technique.

The upper and lower magnetic pole layers322eand322aconstitute a magnetic path for magnetic flux generated by the coil layer322c, their one end portions pinching one end portion of the write gap layer322b. The leakage field near the one end portion of the write gap layer322bis used for writing to the magnetic disk.

InFIG. 4, the coil layer322cis a monolayered coil, however, may be an at-least-two-layered coil or a helical coil. Further, instead of the upper shield layer321cand the lower magnetic pole layer322a, only one magnetic layer may be formed which serves as both layers.

Here, the above-described starting point on the magnetic head element side in the definition of the distance LPbecomes the trailing edge of the pole end of the upper magnetic pole layer322e, which is exposed from the contact surface360.

Further, when the element contact pad36has a crown (rounded shape in the contact surface360) as shown inFIG. 4b, the distance LPis defined as a distance from the just-described starting point to the contact end CMbetween the surface of the magnetic disk40and the rounded contact surface360. That is to say, the distance LPcorresponds to the distance from the one end of the magnetic head element to the trailing end of the actual contact region between the element contact pad and the disk. Therefore, the definition of the distance LPshown inFIG. 4ais premised on the contact between the chamfered corner of the contact surface360and the disk surface. If not the case, the end point in the definition of the LPbecomes the actual contact end.

The signal electrode35is formed on a lead electrode350, and is connected electrically to the lead electrode350. The lead electrode350is connected electrically to the MR multilayer321bof the MR effect element321or the coil layer322cof the electromagnetic coil element322, and is drawn from the element. A base electrode film351with conductivity is formed on the lead electrode350, and a bump352that is extending upward are formed by electrolytic plating using the base electrode film351as electrode. The base electrode film351and the bump352are made of a conductive material such as Cu. The thickness of the base electrode film351is, for example, approximately 10 nm to 200 nm and the thickness of the bump352is, for example, approximately 5 μm to 30 μm.

The top end of the bump352is exposed from the overcoat layer33, and a pad353is provided on this top end. These above-described parts constitute the signal electrode35, and currents are supplied to the magnetic head element32through the four signal electrodes35.

FIG. 5shows a perspective view schematically illustrating another embodiment of a thin-film magnetic head according to the present invention.

As shown in the figure, the thin-film magnetic head30′ is provided with a slider substrate31′, a magnetic head element32′, an overcoat layer33′, a closure34′, an element contact pad36′, two contact pads37′, and four signal electrodes35′. Explanations for elements other than the element contact pad36′ will be omitted because the structures and positions of these elements are the same as those shown inFIG. 3.

The element contact pad36′ is provided in a position that is out of a central axis38′ of a sliding-side surface300′ expanding in the direction along track and is not overlapped with the central axis38′. That is to say, the element contact pad36′ is off-centered in track width direction, and is positioned near one head edge expanding in the direction along track. The contact surface360′ consists of a part of an opposed-to-disk surface310′ of the slider substrate31′, a part of an end surface330′ of the overcoat layer33′, and a part of an end surface340′ of the closure34′. One end320′ of the magnetic head element32′ reaches the above-described part of the end surface330′ of the overcoat layer33′.

By providing the above-described element contact pad36′, only the contact surface360′ can have contact with the surface of the magnetic disk in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained. Further, peripheral corners of the element contact pad36′ and the contact pads37′ are chamfered to be made round. The chamfered corners are preventive against damage on the surface of the magnetic disk by contact.

Further, a distance LP′ (μm (micrometer)) between the trailing end of the contact surface360′ and the one end320′ of the magnetic head element32′ is preferably set to a value satisfying the conditional expression of 22 (μm)≦LP′≦100 (μm). The appropriate LP′ value allows a lopsided wear of the element contact pad36′ to be suppressed sufficiently, and furthermore, the reproduction power of the magnetic head element32′ remains a required level. Here, the starting point on the magnetic head element side in the definition of the distance LP′ is a trailing edge in the surface of the one end320′ of the magnetic head element32′, which is exposed from the contact surface360′. When the element contact pad36′ has a crown (rounded shape-in the contact surface360′), the definition of the distance LP′ becomes the same as the content explained usingFIG. 4b. Further, The above-described conditional expression of the distance LP′ will be explained as an expression of the distance LPlater in detail.

When two thin-film magnetic heads30′ pinch the magnetic disk, the respective element contact pads36′ are positioned to be out of the respective central axes38′ in opposite direction to each other, and not to be opposed to each other.

FIGS. 6aand6bshow cross-sectional views illustrating two embodiments in condition of the contact between the thin-film magnetic head and the magnetic disk in a magnetic recording apparatus according to the present invention.

According toFIG. 6a, a magnetic disk60is pinched by the two thin-film magnetic heads30′, as just described above. In the case, especially when the disk is flexible, the element contact pads36′ support the magnetic disk in such a way that that a vertical section of the disk becomes a gradual S-curve shape. As a result, one end320′ of the magnetic head element32′ reaching the contact surface of the pad36′ and the surface of the disk60have a secure contact with each other.

According toFIG. 6b, a magnetic disk61is pinched by the thin-film magnetic head30and a dummy head62formed of the same material as the slider substrate. The dummy head62has a concave portion63in the sliding-side surface. The concave portion63is provided in a position opposed to the element contact pad36of the head30, and is so large in size that a part of the element contact pad36can be inserted. As a result, the element contact pad36and the concave portion63support the magnetic disk so as to make a gradual dent on the disk, especially when the disk is flexible. Therefore, one end320of the magnetic head element32reaching the contact surface of the pad36and the surface of the disk61have a secure contact with each other. Further, the opening edge of the concave portion63is chamfered to be made round. The chamfered edge is preventive against damage on the surface of the magnetic disk by contact.

Embodiments or alternatives other than the two embodiments shown inFIG. 6aand6bcan be allowed. For example, inFIG. 6a, one thin-film magnetic head30′ may have a plurality of element contact pads36′, and the other head30′ may have the element contact pad(s)36′ in the position not to opposed to any of the plurality of element contact pads36′. Further, one or some of the element contact pads36′ may be a dummy that has no magnetic head elements and is just for adjusting the bending of the magnetic disk.

Further, inFIG. 6b, the element contact pad36and the concave portion63may be provided in the position out of the middle, that is, not to be central in the track-width direction. Furthermore, inFIG. 6b, a plurality of the element contact pads36may be provided and the same number of the concave portions63may be positioned so as to be opposed to the plurality of the element contact pads36respectively.

In any embodiment and alternative described above, only the contact surface of the element contact pad can have contact with the surface of the magnetic disk in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained. Furthermore, by adjusting the bending of the magnetic disk, one end of the magnetic head element and the surface of the magnetic disk can have a secure contact with each other. Therefore, the head can realize stable read and write performances.

In each configuration ofFIGS. 6aand6b, an appreciate adjustment of the positional relation between the element contact pads or between the element contact pad and the dummy head allows the element contact pad(s) and the magnetic disk to have a secure and favorable contact with each other. As a result, the reproduction power remains a required level. The relation between the positional relation and the reproduction power will be described later in detail.

FIGS. 7aand7bshow perspective views schematically illustrating alternatives in shape of the element contact pad of the thin-film magnetic head according to the present invention, andFIG. 7cshows a perspective view schematically illustrating an alternative of the contact pads of the thin-film magnetic head according to the present invention.

As shown inFIG. 7a, a contact surface of an element contact pad70has a triangular shape, and as shown inFIG. 7b, a contact surface of an element contact pad71has a rectangular shape. The shape of the contact surface may also be a circle, a trapezoid or a polygon. In any above-described shape including an ellipsoid shown inFIG. 3, only the contact surface of the element contact pad can have contact with the surface of the magnetic disk in the peripheral area of the magnetic head element during read and write operations. As a result, the wear of the head is sufficiently suppressed and the high reliability over time of the head can be maintained.

According toFIG. 7c, two contact pads72have a shape of two rails expanding in the direction along track. In this alternative, an element contact pad73has a shape of ellipsoid, however, it may have a shape of, for example, circle, triangle, rectangle, trapezoid or polygon.

Further, as shown inFIG. 7ato7c, peripheral corners of the element contact pad and the contact pads with rail shape are chamfered to be made round. The chamfered corners are preventive against damage on the surface of the magnetic disk by contact.

FIGS. 8ato8dandFIGS. 9ato9dshow perspective views and cross-sectional views illustrating alternatives in shape of the closure of the thin-film magnetic head according to the present invention.

According toFIG. 8a, a closure80has a cut-surface802bordering a sliding-side end surface800of the closure80at a trailing edge801. The cut-surface802is flat, however, may be curved like a cut-surface802′ shown inFIG. 8b. Further, a step811may be formed in a sliding-side end surface810of a closure81.

In the thin-film magnetic head with the above-described closure, the element contact pad can be provided so as to have contact with the disk surface before the closure has, even when a pitch angle α (alpha) becomes large, as shown inFIG. 8d. As a result, the end of the magnetic head element and the surface of the magnetic disk can be in contact with each other more stably.

As shown inFIG. 9a, a closure82has cut-surfaces822cutting obliquely across a trailing edge821of a sliding-side end surface820of the closure82. The cut-surfaces822are flat, however, may be curved. Further, as shown inFIG. 9b, cut-surfaces822′ may be provided together with a cut-surface823. Furthermore, all of cut-surfaces822″ and823′ may be curved as shown inFIG. 9c.

In the thin-film magnetic head with the above-described closure, the element contact pad can be provided so as to have contact with the disk surface before the closure has, even when a roll angle β (beta) becomes large, as shown inFIG. 9d. As a result, the end of the magnetic head element and the surface of the magnetic disk can be in contact with each other more stably.

FIGS. 10ato10dshow perspective views schematically illustrating a part of an embodiment of a manufacturing method of a thin-film magnetic head according to the present invention.

First, as shown inFIG. 10a, a wafer90where magnetic head elements are formed on a wafer substrate of alumina-titanium oxide (Al2O3—TiC) by means of the well-known manufacturing method, is cut into blocks91on each of which a plurality of the magnetic head elements is aligned with some rows. Next, as shown inFIG. 10b, a closure member92made of alumina-titanium oxide is bonded on the element-formed surface of the block91. The closure member92has a surface for bonding with a plurality of long convex-portions aligned, and is bonded on surface area including ranges above the magnetic head elements, expect surface area including signal electrodes and their peripheries. Then, as shown inFIG. 10c, a block93with closure is formed by polishing the piece made of the block91and the closure member92from the side of the closure member92.

Next, as shown inFIG. 10d, the block93with closure is cut into bars94, then, the MR height process is performed by polishing the bar94to obtain a desired MR height. Further, a predetermined element contact pad and contact pads are formed by the bombardment of ions96using ion-milling or reactive ion etching method to complete the process of a sliding-side surface95. Then, the bar94is cut to separate into individual sliders (thin-film magnetic heads). After going through the above-described processes, the manufacturing process of the thin-film magnetic head is finished.

Hereinafter, the preferable conditions to be satisfied by the distance LPbetween the trailing end of the contact surface and the one end of the magnetic head element, from the standpoints of the amount of wear and the reproduction power in the head, will be explained in detail.

FIG. 11ashows a schematic view for defining the amount of lopsided wear w of the element contact pad, andFIG. 11bshows a graph illustrating the relation between the hour of use and the amount of lopsided wear w in the thin-film magnetic heads with various distances LP. Thin-film magnetic heads shown inFIG. 3having a pico slider or a femto slider in which the distance LPis 10, 20, 22, 30, 100 or 200 μm, were prepared for the measurements. Then, a flexible disk made by applying a magnetic material on a flexible film substrate was rotated with the same rotating speed as that during write and read operations. After that, the thin-film magnetic heads were in contact with the rotating disk under the same pressure as that during write and read operations.

The pico slider has a normalized size of a length 1.20 mm, a width 1.00 mm and a height 0.3 mm (with a tolerance of plus or minus 0.03), and the femto slider has a normalized size of a length 0.85 mm, a width 0.70 mm and a height 0.23 mm (with a tolerance of plus or minus 0.03). The used flexible disk had a thickness in the range from 40 μm to 80 μm including a major value of 55 μm. The Young's modulus of the disk was actually in the range from 2.9 GPa (300 kgf/mm2) to 8.8 GPa (900 kgf/mm2). Preferably, the Young's modulus may be in the range from 4.9 GPa (500 kgf/mm2) to 7.8 GPa (800 kgf/mm2). The surface roughness Ra of the disk was in the range from 2.0 nm to 3.0 nm.

According toFIG. 11a, a part of the trailing side in the element contact pad is worn away, and the amount of lopsided wear w is defined as a distance between the contact surface98and the trailing end of the wear part.

As shown inFIG. 11b, the amount of lopsided wear w is increased with the hour of use in any of the heads with various distances LP. By comparison of the degree of the increase, it is understood that there are two groups: the magnetic heads in which the distance LPis 20 μm or less; and the magnetic heads in which the distance LPis 22 μm or more. In the former head group, the degree of the increase becomes rapid particularly when the hour of time exceeds 100 hours, however in the latter head group, the degree of the increase becomes slower. Therefore, it is understood that the wear resistance becomes improved critically when the distance LPexceeds 20 μm. Practically, in order to obtain a secure and favorable wear resistance, the distance LP(μm) is required to satisfy the following expression:
LP≧22  (1)

FIG. 12shows a graph illustrating the relation between the distance LPand the reproduction power PN1. The value of the reproduction power PN1is normalized by setting a reproduction power at the distance LP=10 μm to 100. The reproduction power PN1of the thin-film magnetic head pressed to the disk was measured using the same measurement system as that for the wear measurement shown inFIG. 11b.

As shown inFIG. 12, the reproduction power PN1remains approximately a normalized value 90 when the distance LPis 100 μm, though gradually decreases till the distance LPreaches 100 μm. When the distance LPexceeds 100 μm, the reproduction power PN1decreases steeply. It is considered to be a reason of the result that, in the case where the trailing contact end of the element contact pad is rather separated from the one end of the magnetic head element, the area of the flexible disk opposed to the one end of the magnetic head element is bent, then the bending is likely to cause the distance between the one end of the magnetic head element and the disk surface to be fluctuated. Therefore, in order to maintain a predetermined reproduction power, the distance LP(μm) is required to satisfy the following expression:
LP≦100  (2)

From the above-described expressions (1) and (2), it is understood that the condition expression to be satisfied by distance LPis:
22≦LP≦100  (3)

Next, the preferable conditions to be satisfied by the positional relation between the element contact pads or between the element contact pad and the dummy head, from the standpoint of the reproduction power, will be explained in detail.

FIG. 13ashows a schematic view for defining a spacing DPand a distance SPthat represent the positional relation between the element contact pads in the embodiment shown inFIG. 6a, andFIG. 13bshows a graph illustrating the relation between the positional relation and the reproduction power PN2. In order to measure the reproduction power PN2in the embodiment shown inFIG. 6a, a flexible disk rotating with usual speed where signals are written on each of both surfaces, was pinched by the two thin-film magnetic heads shown inFIG. 5with the same pressure as that during read and write operations. Then, a reproduction power was measured in one of the two thin-film magnetic heads. In the case that the pico sliders were used as the two heads, the DPvalue was in the range from 520 μm to 670 μm, and in the case using the femto sliders, the DPvalue was in the range from 150 μm to 350 μm. The properties of the used flexible disk were the same as that used for the wear measurement shown inFIG. 11b.

According toFIG. 13a, the DPis defined as a spacing in the track width direction between the two element contact pads, and the SPis defined as a distance between the respective contact surfaces of the two element contact pads. InFIG. 13b, the horizontal axis is a ratio SP/DP, that is to say, the larger the value is, the more increased the amount of forced bending of the flexible disk is. The value of the reproduction power PN2indicated in the vertical axis is normalized by setting a reproduction power at the ratio SP/DP=0.5 to 100.

As shown inFIG. 13b, when the ratio SP/DPis in the range from 0.02 to 0.2, the reproduction power PN2stably remains in the range from 95 to 100, and is almost constant. However, when the ratio SP/DPis less than 0.02, the reproduction power PN2is significantly decreased. The decrease may be considered to be caused by the destabilization of the contact condition between the element contact pads and the surface of the flexible disk due to decrease in the disk-pinching force of the element contact pads. Meanwhile, when the ratio SP/DPis larger than 0.2, the reproduction power PN2is also significantly decreased. The decrease may be considered to be caused by the destabilization of the contact condition between the element contact pads and the surface of the flexible disk due to increase in the amount of forced bending of the flexible disk. Therefore, it is understood that the condition expression for maintaining a predetermined reproduction power stably, to be satisfied by the ratio SP/DPis:
0.02≦SP/DP≦0.2  (4)

FIG. 14ashows a schematic view for defining a width WPof the element contact pad, a width WCof the concave portion, and a distance SCthat represents the positional relation between the element contact pad and the concave portion in the embodiment shown inFIG. 6b, andFIG. 14bshows a graph illustrating the reproduction power PN3versus the width and the positional relation. In order to measure the reproduction power PN3in the embodiment shown inFIG. 6b, a flexible disk rotating with usual speed where signals are written on each of both surfaces, was pinched by the thin-film magnetic head shown inFIG. 3and the dummy head with the same pressure as that during read and write operations. Then, a reproduction power was measured in the thin-film magnetic head. In both cases that the pico sliders/the femto sliders were used in the head, the WCvalue was in the range from 200 μm to 600 μm. And the WPvalue in the both cases was in the range from 150 μm to 350 μm. The properties of the used flexible disk were the same as that used for the wear measurement shown inFIG. 11b.

According toFIG. 14a, the WPand WC, which are parameters for the element contact pad and the dummy head, were defined as widths in the track width direction of the element contact pad and the concave portion respectively, and the SCis defined as a distance between the contact surface of the element contact pad and the sliding-side surface of the dummy head. InFIG. 14b, the horizontal axis is a ratio SC/(0.5*(WC−WP)). The 0.5*(WC−WP) of the denominator is equivalent to a spacing between the side surface of the element contact pad and the wall surface of the concave portion when a part of the element contact pad is inserted in the concave portion. Therefore, the larger the ratio SC/(0.5*(WC−WP)) is, the more increased the amount of forced bending of the flexible disk is. The value of the reproduction power PN3indicated in the vertical axis is normalized by setting a reproduction power at the ratio SC/(0.5*(WC−WP))=0.025 to 100.

As shown inFIG. 14b, when the ratio SC/(0.5*(WC−WP)) is in the range from 0.012 to 0.1, the reproduction power PN3stably remains in the range from 95 to 100, and is almost constant. However, when the ratio SC/(0.5*(WC−WP)) is less than 0.012, the reproduction power PN3is significantly decreased. The decrease may be considered to be caused by the destabilization of the contact condition between the element contact pad and the surface of the flexible disk due to decrease in the disk-pinching force of the element contact pad and the dummy head. Meanwhile, when the ratio SC/(0.5*(WC−WP)) is larger than 0.1, the reproduction power PN3is also significantly decreased. The decrease may be considered to be caused by the destabilization of the contact condition between the element contact pad and the surface of the flexible disk due to increase in the amount of forced bending of the flexible disk. Therefore, it is understood that the condition expression for maintaining a required reproduction power stably, to be satisfied by the ratio SC/(0.5*(WC−WP)) is:
0.012≦SC/(0.5*(WC−WP))≦0.1  (5)

All the foregoing embodiments are by way of example of the present invention only and not intended to be limiting, and many widely different alternations and modifications of the present invention may be constructed without departing from the spirit and scope of the present invention. Accordingly, the present invention is limited only as defined in the following claims and equivalents thereto.