Gimbaled micro-head/Flexure/conductor assembly and system

Abstract: A low-mass head/flexure/conductor assembly for reading and writing information with respect to a rigid magnetic recording disk. The assembly includes a read/write transducer unit, an elongate flexure, and gimbal structure interconnecting and articulating the transducer unit and the flexure for selected, limited relative roll and pitch, without relative yaw. Conductive ribbons that form part of the gimbal structure also form part of the conductive circuit provided in the assembly. The assembly has an effective mass of no more than about 1.5-milligrams. Plural, hardened, wear-resistant feet are formed on the transducer unit for enabling sliding contact with the recording surface in a disk.

Description: Background and Summary of the Invention This invention relates generally to a rigid-disk information-storage system, and more particularly to a miniature, low-mass, gimbaled, head/flexure/conductor assembly for use in and with such a system. For the purposes of illustration and explanation herein, a preferred embodiment of such an assembly, and of a system employing the same, are disclosed in the setting of an extremely small-format, largely self-contained storage system which employs one or more rotary, rigid, magnetic recording disks. Those skilled in the art, after reading the contents of this specification, will recognize that the invention may be employed in a rigid disk recording system of any size. The quest for increasing storage density and decreasing costs in rigid medium disk drive data storage systems has focused attention on the need to minimize the separation between the head (transducer) and the media -- the so-called "flying height" of the usual air-bearing slider. Improvements in slider and associated manufacture, along with improvements in media surface properties, have enabled the flying height in available rigid disk systems to be reduced to about 0.1-micrometer. Numerous efforts are now devoted to reducing even further the flying height to 0.05-micrometer, or less. These efforts face and present still greater challenges respecting the issue of volume manufacture of sliders, suspensions, media and their assembly and operation in disk drive systems. An example of a prior art magnetic device is described in EP-A-0432145 (Fujitsu Limited). With regard to the issue of flying-head technology, significant advances over this prior art technology have been made, and by way of background illustration, some of the key advances are disclosed in U.S. Patents Nos. 5,041,932 for INTEGRATED MAGNETIC READ/WRITE HEAD/FLEXURE STRUCTURE, 5,073,242 for METHOD OF MAKING INTEGRATED MAGNETIC READ/WRITE HEAD/FLEXURE/CONDUCTOR STRUCTURE, and 5,111,351 for INTEGRATED MAGNETIC READ/WRITE HEAD/FLEXURE/CONDUCTOR STRUCTURE. In the '932 patent, the patentee describes a very low-mass, integrated head/flexure/conductor structure for continuous sliding-contact operation with rigid media, thereby enabling the minimum possible head/media separation and the maximum achievable recording performance. By reducing, as can be done, "effective mass" and applied load by two to three orders of magnitude, relative to conventional air-bearing sliders and suspensions, the local pressure exerted on asperities or microscopic contaminants may be kept well below the onset of destructive physical and chemical avalanche processes, which processes lead to catastrophic failure of the head/media interface. Such reduction of the local pressure also helps to reduce the rate of abrasive wear of the head and media and to extend useful operational life. The validity of the logic behind the development set forth in the '932 patent has been demonstrated in more than two-hundred-thousand hours of wear testing of Flexhead™ integrated head/suspension structures on numerous test fixtures (Flexhead™ is a trademark owned by Censtor Corp. of San Jose, California). Likewise, read/write tests of these structures, employing, for example, probe-type heads with two-layer perpendicular recording media, have demonstrated a capability for very high recording density. Moreover, the extremely small mass of these structures, and the rigidity of the suspensions, result in high resonant frequencies in the lateral and torsional bending modes, and enable thereby significant improvements in actuator and servo-system design and performance. Other advances which have been proposed in the prior art provide, for example, for the employment of a selected wear-resistance material (in the form of a wear-resistant contact pad) in the region (in a contact-recording situation) which makes contact with the media. With this kind of an arrangement, appropriate limitations need to be observed regarding the length and width of such a wear-resistant contact pad, which limitations derive from the need to minimize signal modulation resulting from axial run-out of a disk or other mechanical variance in the drive which is provided for the disk. The present invention addresses this latter concern, and in addition focuses on the desirability of further extending the performance tolerance of integrated head/suspension structures to mechanical variations in the manufacture and assembly of disk drives. Accordingly, an important object of the present invention is to provide a novel low-mass, gimbaled micro-head/flexure/conductor assembly which minimizes signal modulation resulting from nonflatness from a disk surface, from accumulated assembly tolerances, from improper alignment of the disk spindle and actuator support bearing, or from other mechanical imperfections which might give rise to unwanted dynamic separation between the transducer and the recording surface of the media. A correlative object of the invention, in the setting just expressed, is to increase the permissible tolerance on disk run-out, spindle alignment, etc., without impairment of the performance of integrated head/suspension structures. Another key objective of the invention is to increase permissible dimensional and alignment tolerances in the assembly of integrated head/suspension structures and media in disk drives in order to achieve optimal performance with minimal adjustment and run-in time. A further object of this invention is to extend the limits on contact pad dimensions without incurring detrimental signal modulation resulting from disk run-out or other mechanical imperfections. Still another object is to minimize head and media wear by enabling a larger contact pad area and consequently a lower local pressure at the head/media interface. Still another object of the present invention is to separate the manufacture of head and flexure/conductor structures, and to facilitate automated assembly of the one to the other into integrated head/flexure/conductor structures. An object related to that just stated is to increase the number of heads which may be fabricated by deposition processes on a wafer, thereby correspondingly decreasing manufacturing costs. Another related object of the invention is to facilitate independent optimization of materials, configurations, and processes in the fabrication of both the heads and the flexure/conductor structures. Proposed according to a preferred embodiment of the invention is a micro-head/flexure/conductor assembly, or organization, (for reading and writing information with respect to the recording surface in a rigid magnetic recording medium) which assembly includes a read/write transducer unit, an elongate carrier unit for supporting the transducer unit, and gimbal structure interconnecting and articulating these two units for selected, limited relative movement. Significantly, constituent materials and sizing for these assembly components are chosen in such a manner that the effective mass of the assembly is no greater than about 1.5-milligrams. The "effective mass" of an assembly of the type referred to is, as this phrase is employed herein, the same as the equivalent free mass that would accelerate at the same rate as the head structure in the assembly when subjected to a given net inertial force in a direction perpendicular to the disk surface. Included in the assembly which has just been outlined is the necessary conductor structure which cooperates with the magnetic components in the transducer unit and which is employed for communicating with the "outside world". Uniquely, a part of this conductor structure in a preferred embodiment, in the form of two laterally spaced conductive ribbons, also forms a portion of the interconnective gimbal structure. In modified forms of the invention, gimbal ribbons formed of dielectric material carry conductive traces. This gimbal structure unites the transducer unit and the carrier unit in a generally parallel planar relationship, and allows limited relative pitch and roll between these two units while at the same time inhibiting relative yaw between the two. A fulcrum projection formed on a surface in the transducer unit rockingly contacts a surface expanse provided on the carrier unit -- these two components cooperating with the conductive ribbons to form the gimbal structure which defines the permitted pitching and rolling that can occur between the two units. Feet that project from an opposite surface in the transducer unit, preferably formed of a hardened wear-resistant material, are provided for making sliding contact with the recording surface in a disk medium. These and other important features, objects and advantages which are attained by the present invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawings. Description of the Drawings Fig. 1 is an opened-up plan view illustrating a small-format, rigid-magnetic-disk, digital-information storage system incorporating a gimbaled micro-head/flexure/conductor assembly constructed in accordance with the present invention. This assembly is illustrated in Fig. 1 in highly schematic form, and for the sake of simplicity, given the scale of Fig. 1, without detailing respecting its precise configuration and number of component elements. Fig. 2 is a view on a slightly larger scale than that used in Fig. 1 which illustrates, in longitudinal section, the system of Fig. 1, with this view of Fig. 2 taken as if looking generally upwardly from the bottom of Fig. 1. Fig. 3 is a greatly enlarged, fragmentary plan detail, taken generally in the area embraced by the two curved arrows shown at 3-3 in Fig. 1, illustrating details of construction of the micro-head/flexure/conductor assembly incorporated in the system of Figs. 1 and 2. Fig. 4 is a fragmentary view, on substantially the same scale as that employed in Fig. 3, taken generally along the line 4-4 in Fig. 3. Fig. 5 is an even more greatly enlarged perspective view of a generally planar read/write transducer unit, or slider, which forms part of the micro-head/flexure/conductor assembly of the invention, with this unit shown isolated from other structure. Fig. 6 is a fragmentary plan view, on a scale somewhat smaller than that employed in Fig. 3, illustrating a generally planar carrier unit, or flexure, which forms part of the micro-head/flexure/conductor assembly of the invention, with this carrier unit shown isolated from other structure. Fig. 7 is a fragmentary elevation taken generally from the top side of Fig. 6. Figs. 8A, 8B through 14 are fragmentary views illustrating steps employed in the fabrication of the assembly of the invention. Figs. 15 and 16 are fragmentary views, similar to those present in Figs. 3 and 4, respectively, illustrating a modified form of a gimbaled head/flexure/conductor assembly. Figs. 17A and 17B are fragmentary plan and side-elevation views, respectively, of another modified form of transducer unit. Figs. 18A and 18B are fragmentary plan and side-elevation views, respectively, of a modified form of flexure unit usable with the transducer unit of Figs. 17A, 17B. Fig. 19 is a fragmentary plan view illustrating the transducer unit and flexure unit of Figs. 17A, 17B and 18A, 18B, respectively, assembled. Fig. 20 is a fragmentary plan view illustrating yet another modification of an assembly constructed in accordance with the invention, wherein a wire-bond electrical interconnection is employed. Detailed Description of, and Best Mode for Carrying Out, the Invention Turning attention now to the drawings, and referring first of all to Figs. 1 and 2, indicated generally at 10 is an information storage system in the form of a rigid-disk-drive magnetic recording system for storing digital information, which system is constructed in accordance with the present invention. Included in system 10 is a two-part housing 12, including a base 12 a , and, sealingly joined thereto (as via a concealed gasket made, for example, of silicone rubber), a cover 12 b . Housing 12 encloses all of the other components which, together with the housing, make up system 10. In the preferred embodiment now being described, the inside of the sealed housing is maintained essentially at nominal atmospheric pressure. However, there may be instances, where it is desirable to enhance certain performance behavior, to evacuate the housing, and to this end a suitable evacuation pressure is about 0.05-atmosphere. Disposed within housing 12 is a low-power, brushless, D.C. spindle motor 14 which includes a coil-carrying stator 14 a mounted suitably on the outside of a hollow, cylindrical supporting boss 12 c formed in housing base 12 a . Motor 14 also includes a permanent-magnet rotor 14 b which is suitably joined, with the disposition shown, to a lightweight rotary spindle 16. Spindle 16 is mounted, through a journal bearing 20 which is seated within the hollow interior of boss 12 c , for rotation about an axis shown at 18. During drive operation, through appropriate connections (not shown) with conventional control/feedback electronics, motor 14 maintains an accurate, constant spindle rotational speed of about 4800-rpm. Supported on the upper side of spindle 16 (for rotation as a unit therewith) through a suitable clamp 22 is a rigid magnetic recording disk (medium) 24 which is prepared on its opposite axial sides with a magnetic layer surface structure, or surface, for two-sided reading and writing of digitized information. These two sides of disk 24 are shown at 24 a , 24 b . Information is recorded on this surface structure in concentric, adjacent recording tracks. Further discussing disk 24, each recording surface takes the form of an underlying soft magnetic flux-return layer with an in-plane, preferably radially oriented, magnetic anisotropy, and an outer, or overlying, hard magnetic recording film with an out-of-plane magnetic anisotropy. The recording film is protected by a smooth overcoat of wear-resistant material (like carbon), and an lubricant layer to minimize head and disk wear. Because of the fact, which will become apparent, that the loads applied to disk 24 herein are far reduced in comparison with loads applied to disks in prior art flying-head drives, the central supporting substrate of the disk can optionally be made thinner than those substrates which are employed in prior art disks. For example, in the system now being described, the transducers, or transducer units, (still to be described) which are used contact the disk's recording surfaces, do so with a load of only about 40- to about 120-milligrams. Such a load is several orders of magnitude lower than comparable load forces that characterize transducer/disk loading in prior art flying-head designs. Among the end results of all of this are not only that head/disk wear is greatly minimized, but so also are the overall system size and system operating-power requirements. Cooperating with disk 24 in system 10 in the embodiment now being described, for reading and writing digital information with respect to recording surfaces 24 a , 24 b , are two read/write organizations, or micro-head/flexure/conductor assemblies 26, 28, respectively, which are constructed in accordance with the special features of the present invention. Each of assemblies 26, 28, as will be explained more fully below, is gimbaled in construction, and includes a read/write transducer unit (or slider) carried adjacent the distal end of the assembly (ends 26 a , 28 a ), through gimbal structure, on the distal end of an elongate, cantilevered, laterally tapered carrier unit, or flexure. Each of these elongate assemblies is mounted with its fixed end at an angle of about 3-degrees with respect to the associated surface of disk 24, and each has an effective mass, as expressed earlier, of no more than about 1.5-milligrams. The transducer units in these assemblies contact the associated disk surface through hardened wear feet, or pads, with the force mentioned above. Continuing with a general description of other components included in system 10, indicated generally at 60 in Figs. 1 and 2 is a servo-controlled actuator which operates in conjunction with a voice coil motor 62 to support and move the two head/flexure/conductor assemblies (26, 28) in arcs over the opposing recording surfaces in disk 24, thus to position the transducers in these assemblies with respect to any selected, concentric read/write track on the disk's surfaces. The actuator is a relatively lightweight assembly (about 1.5-grams) which pivots on an axis shown at 63, with this assembly including upper and lower, radially extending arms 60 a , 60 b which carry, in a radially extending, cantilevered fashion, previously mentioned micro-head/flexure/conductor assemblies 26, 28, respectively. These arms are borne on a central rotary hub 60 c which is journaled on the inside of a hollow, cylindrical boss 12 d formed in housing base 12 a . A suitable journal connection is established through a journal bearing 64 which is like previously mentioned bearing 20. Actuator 60 is a mass-balanced rotary design, with the cantilevered masses of arms 60 a , 60 b , and of assemblies 26, 28, counterbalanced by a counterbalance-formation 60 d which, in the embodiment now being described, takes the form of a coil winding that actually forms the "rotor" in previously mentioned voice coil motor 62. A position limiter pin 66 (see Fig. 1) limits the swing of the transducers in assemblies 26, 28 to an arc of about 30-degrees, which allows these transducers to sweep into operative positions over the full recordable expanses of recording surfaces 24 a , 24 b . More specifically, pin 66 permits the transducers to swing inwardly to a distance of about 9-mm from axis 18 and outwardly to a distance of about 23-mm from the same axis. Those skilled in the art will thus recognize that the system of the present invention is capable of reading and writing data radially inwardly on a disk (regardless of media form factor) closer to the spin axis than the innermost radial locations typically usable by conventional flying-head systems. Forming the stator in motor 62, which stator cooperates with rotor 60 d , are permanent magnets, such as magnet 62 a , which are suitably joined to base 12 a beneath the rotor. The rotary actuator and associated mechanism selected for system 10 herein can be viewed as taking the form essentially of a pivoted beam with read/write transducer units located adjacent one end, and with a voice coil motor positioned adjacent the opposite end. When energized during system operation, actuator 60 moves the transducer units in arcuate paths approximating radial paths over the recording surfaces in disk 24. In conventional flying-head drives, such arcuate motion with a rotary actuator creates head-skewing effects which cause significant variations in air-bearing stiffness, and consequent changes in head/media spacing. However, because the system of the present invention does not rely upon air-bearing effects in order to maintain a uniform head/disk interface, head skew is largely irrelevant, and actuator 60 can be used successfully to transport the transducers radially inwardly to positions very close to spin axis 18. In system 10, motion in actuator 60 is controlled using conventional closed-loop servo techniques, with appropriate servo-positioning data recorded within data tracks in disk 24 to form a feedback loop that ensures accurate transducer-unit positioning. Conventional high-transfer-rate data-channel structure (not shown) is employed to provide an electrical interconnection between the head/flexure/conductor assemblies and conventional interface electronics which connect system 10 to external devices. System 10, as described herein, includes but a single recording disk. However, one should recognize that a like system may be constructed for plural disks, and such a system is described in the '586 patent application referred to above. Addressing attention now to the constructions of assemblies 26, 28, and focusing attention particularly on Figs. 3-7, inclusive, each of these assemblies is essentially the same in construction as the other, and accordingly, the following description will focus just on the construction of assembly 26. This assembly includes a generally planar read/write transducer unit, or slider, 84, and an elongate, generally planar carrier unit, or flexure, 86, the distal end in which is joined, as will be explained, to the transducer unit through gimbal structure 88 for limited relative articulation between the transducer unit and the flexure. Units 84, 86 are thought of herein as being disposed generally in parallel-planar relationship, with the carrier unit supporting the transducer unit. Unit 84 includes a solid body formed entirely by well known thin-film deposition, patterning and etch-release processes (such as those set forth in the '932 patent) of a suitable dielectric material, such as aluminum oxide, diamond-like carbon (DLC), combinations of the two, or others. This body is shaped with three projecting feet, seen herein at 84 a , 84 b , 84 c , which function as contact pads to define three areas of sliding contact with a media surface during normal operation. Regardless of the material which makes up the bulk of the body in unit 84, preferably, and as disclosed herein, feet 84 a , 84 b , 84 c are formed of a hardened wear-resistant material (Knoop hardness no less than about 1000-kg/mm 2 ), such as DLC, with these feet protruding about 10- to about 15-micrometers beyond the surface of unit 84 which is adapted to face a media recording surface -- i.e., the surface of this unit which faces the viewer in Fig. 3, and which forms the undersurface of unit 84 as seen in Figs. 4 and 5. The projection distance just mentioned has been selected to allow for normal wear of these feet, and also to ensure that the associated "confronting" surface of unit 84 is always sufficiently removed from a media recording surface to avoid undesirable air-bearing effects. Embedded and encapsulated in unit 84 is an electromagnetic read/write head, or head structure, including a pole tip which is herein encapsulated in foot 84 c , as illustrated schematically at 89 in Figs. 3 and 5. Those skilled in the art will recognize that any one of a variety of electromagnetic read/write heads may be employed in the structure which is now being described, and these, for example, could take the form of an inductive-type head, of a cross-field-type head, or of a magneto-resistive-type head. In the preferred embodiment which is now being described the head structure employed within the body of unit 84 is of the inductive-probe type, such as that which is illustrated in the above-referred to '932, '242 and '351 U.S. patents. Extending at the locations shown from the opposite surface of the body in unit 84 are two projecting posts 84 d , 84 e which are formed of a highly conductive metal, such as gold. These posts function both as a part of conductor structure in assembly 26, and as bonding pads through which joinder occurs, as will be explained, between unit 84 and flexure 86. These two posts connect conductively with conductive structure embedded within the body of unit 84 which extends to and forms a coil that operates as a part of the read/write head structure mentioned. Also projecting from the same surface from which the posts project is a somewhat central pivot stud, or fulcrum structure, 84 f , formed of aluminum oxide or DLC, which functions as a part of previously mentioned gimbal structure 88. Posts 84 d , 84 e project from their associated surface in the body of unit 84 by a distance of about 10- to about 15-micrometers, and the same is true with respect to stud 84 f . Flexure 86 is formed also through thin-film deposition, patterning and etch-release processes to have an elongate, laterally tapered shape such as that partially illustrated in Figs. 3 and 6. Deposited on or encapsulated within the body of flexure 86, which body preferably takes the form of a dielectric material such as those mentioned earlier, are two elongate conductors, or conductor structure, 90, 92. These conductors are formed, for example of gold, by thin-film deposition and patterning processes, with conductors 90, 92 having respective, distally extending leaf-spring extensions, or ribbons, 94, 96 of gold or other suitable conducting material, e.g., tantalum, which is insolvent in the etch-release bath. The distal ends of ribbons 90, 92 are bonded conductively to posts 84 d , 84 e , respectively, in unit 84. These laterally spaced ribbons function both as a part of gimbal structure 88, and as a part of the conductor structure in assembly 26 interconnecting the conductor structure which is within unit 84 with that which is within flexure 86. As can be seen particularly in Figs. 3 and 6, the distal end 86 a in flexure 86 projects in a central blade-like fashion, and the surface expanse of this extension which faces unit 84 rockingly contacts the distal end of stud 84 f and functions as the portion of gimbal structure 88 which transmits a vertical force to unit 84. Suitable gimbal action requires that gimbal structure 88 resist motion of unit 84 relative to flexure 86 in all directions in their respective parallel planes, while allowing limited free relative rolling and pitching of the transducer unit about axes 98, 100, respectively, via rocking interaction between stud 84 f and flexure end 86 a . The projection distances expressed above for posts 84 d , 84 e and for stud 84 f allow a suitable range of such rolling and pitching motion. Ribbons 94, 96 resist yawing motion, for example about an axis such as axis 102 (see Fig. 3) between the transducer unit and the flexure. Shifting attention now from the invention's structural organization, and refocussing a look at fabrication of the assembly of the invention, as has been pointed out hereinabove, most of the fabrication steps, processes, materials, etc. relating to the transducer and carrier units are well understood by those skilled in the art to include well-known material-deposition and photolithographic patterning processes. Not specifically discussed or necessarily known well in the prior art, however, are the steps employed in establishing the gimbal-structure interconnection. The remaining, now-to-be-examined drawing figures in this disclosure, 8A, 8B-14, inclusive, relate to the establishment of the gimbal-structure interconnection. Preferably, multiple rows of side-by-side-adjacent flexures and associated ribbons are prepared simultaneously. Formation of the gimbal ribbons begins with the deposition of aluminum oxide, DLC, or other suitable dielectric material 120 on the polished surface of an etch-release layer 121 (e.g. copper) on a host wafer 122. This is done in the manner previously described (in the referenced materials), and to a thickness of about 30-micrometers (see Figs. 8A, 8B). Isolation walls 124 of the same etch-release material may be formed prior to the deposition of flexure material, together with planarization to define the lateral boundaries of each flexure, as described in the reference material. Alternatively, these lateral dimensions may be defined in a later operation by a selective etch process. In the case of DLC, selective plasma ashing or oxidation of the carbon provides a very effective means of isolating individual flexures. Turning to Figs. 9A, 9B, on the planarized surface thus formed, layer 126 of copper is deposited and patterned, defining a constituent 128 which ultimately will become an end 86 a of a flexure. Additional dielectric material is deposited, and the surface is again planarized, resulting in a thickness for copper layer 126 of about 3- to about 5-micrometers. Layer 130 of gold, about 3- to about 5-micrometers thick (see Figs. 10A, 10B), is then deposited and patterned to form what will become flexure conductors 90, 92 and ribbons 94, 96. Gold bonding studs, such as the two shown at 132 (shown with intentionally distorted proportions in Figs. 11A, 11B), are now deposited on what will he the distal ends of the flexure ribbons and on the ends of the flexure conductors (the ends of the latter not being shown) to facilitate the later bonding of the flexure both to the posts in a transducer unit, and to conductors provided in the external flexure support structure furnished by an actuator arm, respectively. The wafer is, at this point in the procedure, ready for slicing between rows into bars of laterally adjacent flexures in preparation for bonding (gimbal interconnecting) of transducer units and flexures. Optionally, the "conductor" portions of layer 130 may be overcoated with a thin layer 134 of dielectric material, leaving the "ribbon" portions, and the bonding studs on the opposite ends of each flexure, exposed as shown in Figs. 12A, 12B. Digressing for a moment, fabrication of the transducer units for the assemblies is accomplished in multiple rows of side-by-side-adjacent units, and in much the same manner as that described in the '932 patent respecting the formation of integrated heads, except in reverse order. That is, contact pads formed of wear-resistant material are first deposited on the polished surface of an etch-release layer of copper on top of a host wafer. Since each transducer unit will have a gimbal suspension, three contact pads rather than one are formed. Dielectric material, high-permeability magnetic material, and electrical conductors are deposited and patterned to create the transducer in the form of a probe type perpendicular head with a helical coil, as described in the cited '932 patent; or, a familiar, multilayer, pancake type coil construction may be created if desired. Alternatively, the transducer units could be fabricated with conventional ring-structure heads for use with longitudinally oriented media. The final wafer-level deposition processes leave the surfaces as shown in Figs. 13A, 13B, revealing gold bonding studs (with intentionally distorted proportions) 136 (which become posts, like posts 84 d , 84 e ), and a load pivot stud 138 (which becomes a pivot stud, like stud 84 f ) formed of dielectric material. The wafer is now sliced between rows of transducer units into bars of laterally adjacent transducer units, in which the registration of each unit corresponds precisely with that of adjacent flexures on a bar of laterally adjacent flexures. The cut surface of each "transducer" bar, which exposes the ends of the magnetic cores of the internal transducer, is lapped and polished in preparation for the deposition of the pole and yoke structures, and of a protective overcoat, as described in the '958 patent application. The next operation (see Fig. 14) involves the bonding of the flexures on one bar to the transducer units on another bar. A transducer-unit bar 140 is placed in a suitable fixture 142 in such a manner that bonding studs 136 protrude slightly above an upper surface 142 a (in Fig. 14) of fixture 142. A flexure-unit bar 144 is placed in fixture 142 such that the bonding studs 132 of the flexures rest on top of bonding studs 136 which project above bar 140. Transducer units and flexure units on bars 140, 144, respectively, are now joined by pressure welds (or by other suitable means), thus making mechanical and electrical connections between the confronting bonding studs. In the final fabrication step, the two unit-carrying bars, supported by fixture 142, thus joined, are immersed in an acid etch solution which simultaneously releases the transducer units and the flexure units from their respective bars, leaving the transducer units attached to the flexure units via the gimbal ribbons. In the process, layer 126 of copper dissolves, thereby freeing the gimbal ribbons from support, and allowing the transducer units to rock about the pivot studs. Turning attention now to Figs. 15 and 16 in the drawings, here there are illustrated modified forms of construction for flexure 86 and for gimbal structure 88. In this modification, the body of the flexure is formed with its distal end 86 a , rather than being laterally inset and blade-like (as in the first-described embodiment), having a lateral width which flows smoothly into and with the width of the remaining portion of the flexure body (see Fig. 15), and with this end extending from a step, or shoulder, 86 b (see particularly Fig. 16) where it joins with the main portion of the body longitudinally to an extent where it completely overlies and "shelters" the attached/associated slider 84 and the distally extending, interconnective gimbal ribbons. Formed on the side of "stepped" end 86 a which faces slider 84 is a central cylindrical projection 86 c which provides the appropriate surface expanse which accommodates rocking contact with stud 84 f in slider 84. Laterally straddling projection 86 c , and also forming part of gimbal structure 88 as before, are ribbons 94, 96 which are substantially the same in construction as their counterparts which bear the same numbers and which are illustrated in the prior-described embodiment of the invention. Ribbons 94, 96 lie, as can be seen, within a zone that is protected by end 86 a . In the modification now being described, flexure 86 and slider 84 are disposed, as before, generally in parallel planar relationship. Viewed normal to these planes, as in Fig. 15, one can see that the marginal boundaries of end 86 a are substantially coextensive with those of slider 84. Fabrication of the modification now being described differs only slightly from that which has been set forth in the steps mentioned earlier. What, in the embodiment now being described, forms a void space between end 86 a and ribbons 94, 96, surrounding projection 86 c will, during early fabrication stages, be filled in with deposited copper planarized to be level with what is shown as the undersurface of the main body of flexure 86 in Fig. 16. Ribbons 94, 96, and the conductors (mentioned with regard to the embodiment earlier described) that extend from these ribbons lengthwise in the main body of the flexure, are formed by the deposition of gold, tantalum, etc., with the ribbons lying on the surface of the filling-in copper just mentioned. Slider 84 is unchanged in construction. Bars of side-by-side adjacent sliders and flexures are joined as previously described, and a copper etch process is performed to free these structures from constraints, and to remove, at the same time, the copper filling which has heretofore occupied the space within a flexure between the extending ribbons, and the now roofing end 86 a in the flexure. This modified form of the invention offers a construction which provides extra resistance to damage that could be caused during shipping, handling or assembly operations. Figs. 17A-20, inclusive, illustrate two other modifications of the assembly of the invention, with Figs. 17A-19 illustrating one of these two modifications, and Fig. 20 illustrating the other. The transducer units and carrier units which make up these modifications are formed with dielectric bodies and with conductor structure and a read/write transducer, similar to those like-identified components mentioned earlier herein, with all fabrication performed utilizing thin-film deposition and patterning processes, and etch-release procedures, like those discussed earlier. Naturally, the specific patternings which are employed are different, and relate to the specific different outlines and topographies that characterize these modifications. In Figs. 17A, 17B, there is illustrated at 150 a transducer unit, or slider, which is shown isolated from other structure. Slider 150 has a body 150 a which is generally planar (see particularly Figs. 17B), from one side of which project three wear feet 150 b , 150 c , 150 d , and from the opposite side of which project a fulcrum pin 150 e and a post 150 f . A read/write transducer with an appropriate read/write pole tip is formed in foot 150 d , and, internally embedded conductive traces that extend from a coil included in this transducer continue to a pair of conductive bonding pads 152 (proportions distorted). Turning attention to Figs. 18A, 18B, here there is shown at 154 an elongate, generally planar dielectric flexure, or carrier unit, which is intended for joinder to slider 150. Flexure 154 includes a body 154 a from the distal end in which project two laterally spaced ribbons 154 b whose distal ends are joined through an interposing structure including a proximally extending tongue 154 c . Also included in flexure 154, and projecting distally toward tongue 154 c , is a laterally centered blade 154 d whose far surface in Fig. 18A (its undersurface in Fig. 18B) is adapted rockingly to contact fulcrum pin 150 e in slider 150, thus to form part of the gimbal structure. Conductive traces, such as the one shown at 156 in Figs. 18A, 19, extend in the flexure toward conductive bonding pads 158 (proportions distorted) which are adapted for bonding to previously mentioned bonding pads 152. In Fig. 19, slider 150 and flexure 154 are shown joined in generally parallel-planar relationship through suitable joinder of bonding pads 152, 158. Shifting attention now, in Fig. 20, which is taken from the same point of view as that offered in Fig. 19, there is shown at 160 a gimbaled head/flexure/conductor assembly including a substantially planar transducer unit, or slider, 162, and an elongate, generally planar flexure, or carrier unit, 164. Slider 162 includes a body 162 a , three wear feet 162 b , 162 c , 162 d , and a projecting fulcrum pin 162 e . Foot 162 d carries an embedded transducer including the necessary coil from which conductive traces, that are suitably formed within body 162 a , extend to a pair of conductive bonding pads 166 which face the viewer in Fig. 20. Flexure 164 includes, adjacent its distal end, a pair of laterally spaced, distally projecting ribbons 164 a which include outrigger portions 164 a 1 that turn back, so-to-speak, to extend proximally over slider 162. Extending in the flexure, and through the ribbons and outrigger portions, are conductive traces, such as trace 168, which extend toward conductive bonding pads 170 that also face the viewer in Fig. 20. The far sides of outriggers 164 a 1 in Fig. 20 are suitably mechanically bonded to the side of slider 162 which faces the viewer in Fig. 20, and conventional conductive interconnects are established between bonding pads 166, 170 through well-known wire-bonding techniques. Wire-bond interconnects are shown at 172. Extending distally from the distal end of the body in flexure 164 is a laterally-centered blade 164 b which extends over and rockingly contacts fulcrum pin 162 e . Slider 162 and flexure 164 are disposed generally in parallel planar relationship. The modifications just discussed in Figs. 17A-20, inclusive, offer different kinds of manufacturing capabilities, tolerances, resonance performances, etc. in comparison with the other modifications described herein, and they are designed to offer certain special advantages in certain applications. For example, the modifications illustrated in Figs. 19 and 20 allow for assembly of a transducer unit to a carrier unit after each has been separated as an individual unit as well as in "bar" form as described above. To interconnect these two as individual units requires use of simple automated holding fixtures like those, for example, routinely used to align and bond die in the manufacture of semiconductor devices. Accordingly, there are disclosed herein several forms of a novel, low-mass, gimbaled head/flexure/conductor assembly, and a system incorporating the same, which offer all of the desirable features, and meet all of the objectives, set forth hereinabove. The proposed gimbaled structure provides decided advantages in manufacturing by allowing appreciable increases in dimensional and alignment tolerances in final assembly of integrated head/suspension structures and, in addition, lends itself to high-volume, reliable fabrication utilizing deposition processes on wafers, thus decreasing overall manufacturing costs. The gimbaled assembly of this invention takes advantage of the superior reading and writing performance attainable through contact operation with the recording surface of a rigid disk, while at the same time, by virtue of the presence of gimbal structure, addressing very satisfactorily the issue of disk-surface unflatness and other matters relating to dynamic changes in topography during system operation. The unique gimbal structure which is proposed utilizes ribbons that interconnect a transducer unit and a flexure, which ribbons have dual functionality -- serving as a part of the mechanical gimbal suspension, and also as a part (carrier or otherwise) of the conductive circuit which communicates between the magnetic components in a read/write head and the outside world. Where extra shipping, handling and assembly protection is desired for the relatively fragile gimbal ribbons, one can utilize the modified construction illustrated in Figs. 15 and 16, wherein the distal end of the flexure body "roofs" over the zone containing these ribbons. The modifications shown in Figs. 17A-20 offer other assembly construction possibilities which can allow more readily for the interconnection of individual transducer units to individual or row-mounted carrier units. These modifications also offer the potential for wide variation of dynamic resonance characteristics through the expedient of readily changing the sizes and shapes of the gimbal ribbons. The modification pictured in Figure 20 provides the additional capability to provide a mechanical interconnect which is independent of an electrical interconnect should such be required for reliability or other reasons. In all of the invention embodiments disclosed and described herein, the incorporated read/write head structure can, as was mentioned earlier with respect to interchangeable variations in one of the disclosed embodiments, take the form of an inductive-type structure, a cross-field-type structure, or of a magneto-resistive-type structure.

Claims: A head-gimbal assembly (26) for reading or writing information with respect to a rigid magnetic recording medium (24), comprising: a generally planar, microscopic slider (84) including an electromagnetic transducer, a low-profile arm (86) having a gimbal structure (88) adjacent to a distal end and connected to said slider (84), characterized in that said slider has a major surface disposed substantially parallel to a major surface of said arm, and, comprises a plurality of protrusions (84 a , 84 b , 84 c ) projecting from said major surface, a plurality of projecting posts (84 d , 84 e ) and a projecting stud (84 f ) protruding from an opposite major surface of said slider; and in that said gimbal-structure includes a pair of latterally spaced elongated ribbons (94, 96) with their distal end bonded to said projecting posts (84 d , 84 e ), and a distal end (86 a ) rockingly contacting the distal end of said stud (84 f ) so that said gimbal structure allows limited relative pitch and roll between said slider and said arm, while inhibiting relative yaw between said slider and said arm. The assembly of claim 1, wherein said gimbal structure includes a laterally centered, proximally extending tongue (86 a ). The assembly of claim 1, wherein said gimbal structure includes a plurality of conductive leads (94,96). The assembly of claim 1, and further comprising a stud (84 f ) disposed between said arm and said slider and serving as a fulcrum. The assembly of claim 1, wherein said arm (86) includes a plurality of conductors (90,92) connected to said gimbal structure (88). The assembly of claim 1, wherein said slider (84) is adapted for dynamic contact with a rapidly spinning disk (24) amid communication with the disk (24). The assembly of claim 1, wherein said major surface of said slider (84) has three protrusions (84 a ,84 b ,84 c ), with a poletip (89) of said transducer encased in one of said protrusions. The assembly of claim 1, wherein said major surface of said slider (84) has a plurality of protrusions (84 a ,84 b ,84 c ), one of said protrusions (84 c ) being laterally centered and encompassing a poletip (89) of said transducer.

Inventors: HAMILTON HAROLD J, MARTIN TIMOTHY W, HAMILTON, HAROLD J., MARTIN, TIMOTHY W.
Applicants: CENSTOR CORP, CENSTOR CORPORATION
Application year: 1992
Main classification: G11B5
IPC codes: G11B5