Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/4806—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed specially adapted for disk drive assemblies, e.g. assembly prior to operation, hard or flexible disk drives
  • G11B5/486—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed specially adapted for disk drive assemblies, e.g. assembly prior to operation, hard or flexible disk drives with provision for mounting or arranging electrical conducting means or circuits on or along the arm assembly
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/4806—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed specially adapted for disk drive assemblies, e.g. assembly prior to operation, hard or flexible disk drives
  • G11B5/4853—Constructional details of the electrical connection between head and arm
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B25/00—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus
  • G11B25/04—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card
  • G11B25/043—Apparatus characterised by the shape of record carrier employed but not specific to the method of recording or reproducing, e.g. dictating apparatus; Combinations of such apparatus using flat record carriers, e.g. disc, card using rotating discs
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/012—Recording on, or reproducing or erasing from, magnetic disks
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
  • G11B5/027—Analogue recording
  • G11B5/035—Equalising
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/4806—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed specially adapted for disk drive assemblies, e.g. assembly prior to operation, hard or flexible disk drives
  • G11B5/4813—Mounting or aligning of arm assemblies, e.g. actuator arm supported by bearings, multiple arm assemblies, arm stacks or multiple heads on single arm
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/4806—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed specially adapted for disk drive assemblies, e.g. assembly prior to operation, hard or flexible disk drives
  • G11B5/4833—Structure of the arm assembly, e.g. load beams, flexures, parts of the arm adapted for controlling vertical force on the head
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B2005/0002—Special dispositions or recording techniques
  • G11B2005/0005—Arrangements, methods or circuits
  • G11B2005/001—Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure
  • G11B2005/0013—Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure of transducers, e.g. linearisation, equalisation
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B2220/00—Record carriers by type
  • G11B2220/20—Disc-shaped record carriers
  • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
  • G11B2220/2508—Magnetic discs
  • G11B2220/2516—Hard disks

Definitions

• This invention relates generally to structure and method of controlling capacitance and impedance arising from integral conductors in a suspension for supporting a read/write head adjacent to a relatively moving recording medium in a disk drive. More particularly, it relates to an integrated suspension and conductor stucture wherein the suspension includes voids such that portions of the suspension are generally the complement of the conductor structure and a method for fabricating the same.
• Contemporary disk drives typically include a rotating rigid storage disk and a head positioner for positioning a data transducer at different radial locations relative to the axis of rotation of the disk, thereby defining numerous concentric data storage tracks on each recording surface of the disk.
• the head positioner is typically referred to as an actuator.
• numerous actuator structures are known in the art, in-line rotary voice coil actuators are now most frequently employed due to their simplicity, high performance, and their ability to be mass balanced about their axis of rotation, the latter being important for making the actuator less sensitive to perturbations.
• a closed-loop servo system is employed to operate the actuator and thereby position the heads with respect to -the disk surface.
• the read/write transducer which may be of a single or dual element design, is typically deposited upon a ceramic slider structure having an air bearing surface for supporting the transducer at a small distance away from the surface of the moving medium.
• Single element designs typically require two wire connections while dual element designs require four.
• Magnetoresistive (MR) heads in particular, generally require four wires.
• the combination of an air bearing slider and a read/write transducer is also known as a read/write head or a recording head.
• Sliders are generally mounted to a gimbaled flexure structure attached to the distal end of a suspension's load beam structure.
• a spring biases the load beam, and therethrough the head, towards the disk, while the air pressure beneath the head pushes the head away from the disk. The equilibrium distance then determines the "flying height" of the head.
• the head operates in a hydrodynamically lubricated regime at the head/disk interface rather than in a boundary lubricated regime.
• the air bearing maintains spacing between the transducer and the medium which reduces transducer efficiency, however, the avoidance of direct contact vastly improves the reliability and useful life of the head and disk components. Demand for increased areal densities may nonetheless require that heads be operated in pseudo contact or even boundary lubricated contact regimes, however.
• the size (and therefore mass) of a slider is usually characterized with reference to a so-called standard 100% slider (minislider).
• standard 100% slider minislider
• 70%, 50%, and 30% slider microslider, nanoslider, and picoslider, respectively
• Smaller slider structures generally require more compliant gimbals, hence the intrinsic stiffness of the conductor wires attached to the slider can give rise to a significant bias effect.
• hybrid stainless steel flexure and conductor structures have been proposed which incorporate most of the -benefits of the integrated conductor flex-circuit flexure structures while remaining largely compatible "with prior art fabrication and loadbeam attachment methods.
• Such hybrid designs typically employ stainless steel flexures having deposited insulating and conductive layers for electrical interconnection of the head to the associated drive electronics, e.g., a preamp chip and read channel circuitry.
• hybrid flexure designs employ relatively lengthy runs of conductors which extend from bonding pads at the distal, head-mounting end of the flexure to the proximal end of the flexure to provide a conductive path from the read/write head along the length of the associated suspension structure to the preamp or read-channel chip(s). Because the conductors are positioned extremely close to but electrically isolated from the conductive stainless steel flexure structure which is in turn grounded to the load beam, the magnitude of the conductor capacitance to ground is increased relative to a conventional insulated discrete wire twisted pair conductor structure.
• the invention to be described provides, inter alia, a flexure for a suspension in a disk drive which includes integrated conductor structure configured to limit the parasitic capacitance between the conductor structure and other parts of the suspension structure and a method for fabricating the same.
• a suspension assembly in accordance with a preferred embodiment of the invention includes a flexure having one or more shaped voids and having integrated conductors which extend along the flexure generally adjacent to the voids.
• the integral conductors replace prior art discrete twisted-pair, insulated conductor wires which would normally extend along the length of the associated suspension.
• the size and shape of the flexure voids as well as the conductor geometry are controlled to reduce undesirable effects of conductor capacitance to ground.
• the conductor traces may be configured to reduce the mutual capacitance of the traces. The invention provides improved electrical performance without materially affecting the suspension' s mechanical performance.
• a general object of the present invention is to provide a low-profile, robust, reliable, suspension having integral conductors for electrically interconnecting a read/write head to associated read/write circuitry which overcomes limitations and drawbacks of the prior art.
• a more specific object of the present invention is to provide a method to control the capacitance or impedance of an integrated flexure/conductor structure for use with a read/write head in a disk drive.
• the invention provides an economical and reliable method for electrically interconnecting a transducer mounted on a slider to an integrated flexure/conductor structure which implements a gimbal and includes exposed conductive electrical bonding pads positioned near the slider mounting region at the distal end of a conductive flexure.
• the bonding pads and associated conductors are electrically isolated from the flexure by a dielectric layer affixed to the flexure with the conductors extending generally coplanarly along a flexure surface.
• the flexure includes one or more voids and the conductors are configured to extend adjacent to the voids.
• the conductor aspect ratio and the interconductor spacing may be tailored to reduce the mutual capacitance between conductors while concurrently maintaining low capacitance to ground.
• the boundaries of the voids may be configured to prevent discontinuous impedance changes along the conductor path.
• Fig. 1 is an enlarged diagrammatic plan view of an integrated flexure/conductor structure in accordance with the invention.
• Fig. 2 shows a cross section of the integrated flexure/conductor structure of Fig. 1 taken along section line A-A.
• Fig. 2A illustrates an alternative cross sectional detail of an integrated flexure/conductor structure of the type illustrated in Fig. 1.
• Fig. 3 is an enlarged diagrammatic plan view of a head gimbal assembly (HGA) in accordance with the invention which includes a loadbeam, an integrated flexure/conductor structure, and a read/write head.
• HGA head gimbal assembly
• Fig. 4 illustrates a graph showing conductor capacitance to ground versus adjacent void width.
• Fig. 5A - 5D illustrate a variety of exemplary void outlines which may be defined in an integrated flexure/conductor structure in accordance with the invention.
• Fig. 6 illustrates an equivalent circuit diagram of a typical read circuit, conductor, and read/write head system which employs an integrated-conductor type conductive flexure member.
• Fig. 7 is a graph modeling the transfer function of the circuit of Fig. 6 assuming a typical capacitance-to-ground value for a flexure having no voids adjacent the conductors.
• Fig. 8 is a graph modeling the transfer function of the circuit of Fig. 6 assuming a typical capacitance-to-ground value achievable by employing voids adjacent the conductors.
• Fig. 9 illustrates a plan view of a disk drive in accordance with the invention.
• Fig. 1 is a plan view of an integrated flexure/conductor structure 10 in accordance with a preferred embodiment of the invention.
• Flexure/conductor structure 10 includes a generally planar stainless steel flexure member 12 which is approximately 20-microns thick and which includes tooling holes 14 and 15 which are used during manufacturing and assembly for precision component alignment.
• a pair of conductive traces of approximately 10-microns thick copper form part of a conductor structure 16 which extends from the proximal end 17 of flexure member 12 to the head supporting distal end 18 of flexure member 12.
• Conductor structure 16 includes a thin (e.g., 10-microns) insulating base film 25 (omitted for clarity but shown in Fig.
• Flexure member 12 includes one or more voids 20 which are positioned adjacent to the path along which conductor structure 16 is routed to reduce the capacitance between the conductor structure and the stainless steel flexure member 12. Accordingly, the invention provides a method for controlling the capacitance arising from the integration of the conductor structure 16 with the stainless steel flexure member 12. As is well known in the art, excessive conductor or lead wire capacitance has a deleterious impact on signals traveling between the associated read/write head and preamp circuit.
• Fig. 2 illustrates a cross section of the flexure/conductor structure 10 of Fig. 1 taken along section line A-
• Conductor structure 16 includes, in this embodiment, a pair of conductive traces 22 and an insulating polyimide (a flexible polymeric resinous material) layer 24 which spans the void 20 to provide support for the conductive traces.
• the pair of traces are configured as close together as the fabrication process reliably permits to reduce the magnitude of the mutual capacitance between the conductors.
• an additional insulation layer of about 4-microns thickness may be used as a protective overcoat for the traces 22.
• the voids should be shaped so as to cause a smooth or relatively continuous change in the cross sectional area of the void 20 along the length of flexure/conductor structure 10 so as to avoid abrupt -transitions in the impedance along the signal path defined by conductor structure 16.
• the flexure member interior boundary that defines void(s) 20 may be undercut (as shown in Fig. 2 or 2A) to further smooth impedance changes along the signal path.
• the conductive traces 22 are plated and photolithographically defined, rather than laminated and etched, so that the insulation and conductive trace layers may be made suitably thin so as not to materially affect the mechanical properties of the stainless steel flexure member. After the insulator and conductor structures are formed, the outlines of the flexure and the voids may be selectively etched to complete the formation of an intergrated flexure/conductor structure.
• Fig. 3 shows a fully assembled head gimbal assembly (HGA) 30 in accordance with the invention which includes a baseplate 32 for mounting the HGA to an actuator arm in a disk drive and a loadbeam 34 for applying a load force onto read/write head 36.
• Head 36 is affixed to the distal end 18 of flexure/conductor structure 10 and the transducer element(s) (not shown) of read/write head 36 are electrically interconnected to the conductive traces 22.
• Flexure/conductor structure 10 may be conventionally spot welded to loadbeam 34.
• Loadbeam 34 typically includes a protuberance or load button (not shown) which approximates point contact between loadbeam 34 and read/write head 36 so that head 36 is capable of limited relative pitch and roll with respect to loadbeam
• Graph 42 shows only minor capacitance reductions in the case where the grounded loadbeam is not present. Thus, it is not necessary to fabricate or etch voids into the loadbeam itself, unless, for example, the conductors are integrated with a loadbeam having an integral gimbal that is not implemented with a separate flexure member.
• the void width is made too small, the capacitance remains relatively high, however, if the void width is made too large, a point of diminishing returns is reached and structural rigidity may be unecessarily compromised.
• the appropriate void width is ultimately dependent upon the specific conductor configuration under examination but can be readily determined either via modeling or empirically.
• the -capacitance to ground can also be reduced by increasing the thickness of the insulating layer, however, this solution is not desirable because it tends to increase the thickness of the resultant suspension and because the added material and associated mass may give rise to adverse mechanical effects.
• narrower conductive traces may be employed to reduce capacitance to ground, however the narrower conductive traces exhibit undesirable increases in conductor resistance.
• the use of precision shaped voids facilitates the fabrication of potentially thinner suspension structures having integrated conductors that offer improved electrical performance.
• Figs. 5A - 5D illustrate several alternative void shapes that may be employed adjacent to either the read or write signal path to control the capacitance of that signal path.
• Fig. 5A illustrates a substantially rectangular interior boundary defining a void in a flexure member. Although the illustrated void helps to reduce the magnitude of the capacitance to ground, the pe ⁇ endicular crossing of the conductor and the void boundary can give rise to a sha ⁇ or step-function transition in the impedance along the conductor path.
• void boundaries such as those disclosed in Figs. 5B-5D appear to provide better high frequency performance than the void boundary illustrated in 5A.
• the thickness of the flexure member which acts as a ground plane, may also be varied (Fig. 2 A) to cause a more gradual impedance change for any of the void geometries illustrated in Figs. 5A- 5D.
• the void boundary may be either an interior or exterior boundary of the flexure member, since voids may be formed along a lateral edge of the flexure member, for example.
• Fig. 6 shows an equivalent circuit diagram representing a characteristic transmission line model 49 of a typical read circuit, conductor, and magnetoresistive (MR) read head system which employs an integrated conductor type stainless steel flexure.
• MR head equivalent circuit 50 is a conventional model of a 150-kfci (kilo flux changes per inch) read element.
• Conductive trace equivalent circuit 52 represents the conductive traces adjacent a grounded, conductive flexure structure. Forward and rearward looking capacitances to ground arising from the conductor traces are represented by capacitors 53 and 54.
• a driving source 56 is swept from about 10-mhz to 5-Ghz to analyze the frequency driven transfer function of the overall circuit.
• FIG. 7 and 8 show modeling results of the transfer functions of the circuit for the cases where there are no voids in the flexure adjacent the traces and where there are voids in flexure, respectively.
• the forward looking and rearward looking capacitance to ground is assumed to be on the order of about 14- picofarads, whereas, with the voids, the forward looking and rearward looking conductor capacitance to ground may readily be reduced to about 4-picofarads.
• the modeled circuit has a reduced bandwidth and earlier rolloff than the same structure employing voids in accordance with the invention.
• an integrated- conductor flexure in accordance with the invention provides better bandwith and a higher cutoff frequency in the head circuit.
• the overall circuit behaves as a bandpass filter and exhibits a higher Q with the voids.
• MR head design may have the capacitances and/or impedances of the signal paths of the read and write elements separately optimized by employing different conductor geometries and/or the void configurations for the read and write conductive traces, respectively.
• Fig. 9 illustrates an integrated-conductor flexure employed in the context of a disk drive.
• Disk drive 70 includes a rigid base 75 and a rotating storage disk 80 which is rotatably mounted with respect to base 75 via conventional spindle motor means (not shown).
• Drive 70 also includes a rotary actuator assembly 82 which includes a voice-coil 84 that, when selectively energized, is used to move
• Flex circuit 82 is electrically connected to the conductors on flexure 10 to facilitate communication between head 36 and remotely located signal processing circuitry (not shown).

Landscapes

• Supporting Of Heads In Record-Carrier Devices (AREA)
• Adjustment Of The Magnetic Head Position Track Following On Tapes (AREA)
• Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
• Networks Using Active Elements (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=24490152

Family Applications (1)

Country Status (7)

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Citations (4)

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• 1997
  • 1997-03-21 JP JP9534681A patent/JPH11507465A/ja active Pending
  • 1997-03-21 CN CN97190246A patent/CN1185855A/zh active Pending
  • 1997-03-21 KR KR1019970708399A patent/KR19990021924A/ko not_active Application Discontinuation
  • 1997-03-21 EP EP97918493A patent/EP0900434A1/en not_active Withdrawn
  • 1997-03-21 AU AU26587/97A patent/AU2658797A/en not_active Abandoned
  • 1997-03-21 WO PCT/US1997/005346 patent/WO1997036290A1/en not_active Application Discontinuation
  • 1997-03-21 CA CA002221966A patent/CA2221966A1/en not_active Abandoned

Patent Citations (4)

Non-Patent Citations (1)

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