Abstract:
An integrated suspension for a hard disk drive is formed as a single-piece flat assembly. The design eliminates the need for mechanical reinforcement such as flange forming, and requires no additional weld processing to form the functional portion of the assembly. A partial etch process is used to reduce local thicknesses in the gimbal and hinge areas to reduce the overall stiffness of the suspension. The proximal end structure of the suspension is also built by partial etching to achieve higher natural frequencies. The suspension design also incorporates built-in load/unload features and two-sided, opposite-facing limiters to limit excessive slider displacement during the manufacturing process, loading/unloading, and non-operational shock environments.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates in general to improved hard disk drive performance, and in particular to an improved suspension for hard disk drives. Still more particularly, the present invention relates to an improved, integrated gimbal design for a disk drive suspension. 
     2. Description of the Prior Art 
     Generally, a data access and storage system consists of one or more storage devices that store data on storage media such as magnetic or optical data storage disks. In magnetic disk storage systems, a storage device is called a direct access storage device (DASD) or hard disk drive (HDD), which includes one or more hard disks and an HDD controller to manage local operations concerning the disks. Hard disks are rigid platters, typically made of aluminum alloy or a mixture of glass and ceramic, covered with a magnetic coating. Typically, two or three platters are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm). 
     The only other moving part within a typical HDD is the head stack assembly. Within most drives, one read/write head is associated with each side of each platter and flies just above or below the platter&#39;s surface. Each read/write head is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid arm apparatus which supports the entire head flying unit. More than one of such arms may be utilized together to form a single armature unit. 
     Each read/write head scans the hard disk platter surface during a “read” or “write” operation. The head/arm assembly is moved utilizing an actuator which is often a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which is also mounted the spindle supporting the disks. The base casting is in turn mounted to a frame via a compliant suspension. When current is fed to the motor, the VCM develops force or torque which is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head nears the desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop directly over the desired track. 
     Conventional disk drive suspensions are made as either two pieces including a load beam and a flexure, or as a single, integrated gimbal assembly. In order to increase the stiffness of the suspension and its dynamic performance, flanges are typically formed on the suspension. Unfortunately, the extra forming step changes the flatness of the suspension and increases its overall thickness, such that the dynamic performance of the suspension is downgraded. In addition, the two-piece suspension designs require an extra laser welding processing step to assemble the pieces together. This welding process requires additional tooling and introduces assembly tolerances as well. Moreover, the weld process tends to distort the suspension due to high welding temperatures, and degrades the dynamic performance and quality control for the suspension. Thus, an improved disk drive suspension design that overcomes the limitations of the prior art is needed. 
     SUMMARY OF THE INVENTION 
     An integrated suspension for a hard disk drive is formed as a single-piece flat assembly. The design eliminates the need for mechanical reinforcement such as flange forming, and requires no additional weld processing to form the functional portion of the assembly. A partial etch process is used to reduce local thicknesses in the gimbal and hinge areas to reduce the overall stiffness of the suspension. The proximal end structure of the suspension is also built by partial etching to achieve higher natural frequencies. The suspension design also incorporates built-in load/unload features and two-sided, opposite-facing limiters to limit slider displacement during the manufacturing process, loading/unloading, and non-operational shock environments. 
     Accordingly, it is an object of the present invention to provide improved hard disk drive performance. 
     It is an additional object of the present invention to provide an improved suspension for hard disk drives. 
     Still another object of the present invention is to provide an improved, integrated gimbal design for a disk drive suspension. 
    
    
     The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments. 
     FIG. 1 is a schematic diagram of a conventional hard disk drive. 
     FIG. 2 is a top plan view of a suspension for the hard disk drive of FIG.  1  and is constructed in accordance with the invention. 
     FIG. 3 is an enlarged top plan view of a gimbal portion of the disk drive suspension of FIG.  2 . 
     FIG. 4 is a side elevational view of the gimbal portion of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a schematic drawing of an information storage system comprising a magnetic hard s disk file or drive  11  for a computer system is shown. Drive  11  has an outer housing or base  13  containing a plurality of stacked, parallel magnetic disks  15  (one shown) which are closely spaced apart. Disks  15  are rotated by a spindle motor located therebelow about a central drive hub  17 . A plurality of stacked, parallel actuator arms  21  (one shown) are pivotally mounted to base  13  about a pivot assembly  23 . A controller  19  is mounted to the base for selectively moving arms  21  relative to disks  15 . 
     In the embodiment shown, each arm  21  comprises a mounting support  25 , a pair of parallel, cantilevered load beams or suspensions  27  extending from each mounting support  25 , and a head gimbal assembly  29  having at least one magnetic read/write head secured to each suspension  27  for magnetically reading data from or magnetically writing data to disks  15 . Suspensions  27  have a spring-like quality which biases or maintains them in parallel relationship relative to one another. A motor assembly  31  having a conventional voice coil motor is also mounted to pivot assembly  23  opposite head gimbal assemblies  29 . Movement of an actuator driver  33  (indicated by arrow  35 ) moves head gimbal assemblies  29  radially across tracks on the disks  15  until the heads on assemblies  29  settle on the target tracks. The head gimbal assemblies  29  operate in a conventional manner and always move in unison with one another, unless drive  11  uses a split actuator (not shown) wherein the arms move independently of one another. 
     Referring now to FIG. 2, an improved suspension  41  for a hard disk drive such as drive  11  is shown. 
     Suspension  41  is a unitary, flat design that is formed from a three-ply laminate of stainless steel  41   a , copper  41   b , and a dielectric such as polyimide  41   c  (see FIG.  4 ). The copper and dielectric layers of the laminate have approximate thicknesses of about 3 to 20 microns. The stainless steel layer has a thickness of about 18 to 100 microns to meet different dynamic performance requirements. Suspension  41  integrally joins a load beam portion  43  with the traditionally separate flexure portion  45  to form a single integrated suspension from the laminated material. Suspension  41  also has an integrally formed base or mount plate  52  with a mounting hole  53 . A hinge  47  and a set of flexure outriggers  71 ,  73  (FIG. 3) are formed from the stainless steel layer, and may be partially and/or fully etched, depending upon the application. The hinge  47  is provided for achieving an appropriate gram load in suspension  41 . Suspension  41  also has a datum tooling hole  48  and numerous partially-etched pockets  49 , as indicated by the dashed lines in FIG.  2 . 
     A plurality of conductor traces  51  are formed from the copper layer and extend along substantially the entire length of suspension  41 . Traces  51  wind in a circuitous pattern from the proximal end of suspension  41  near mounting hole  53 , to the integrated gimbal section  55  on the distal or functional end of suspension  41 . Note that suspension  41  requires no additional laser welding, and that it has no enhanced structural formations, such as reinforcement flanges, which are commonly required in prior art one piece designs for needed strength. 
     As shown in FIGS. 3 and 4, load beam  43  of suspension  41  has a partially-etched, cup-formed load/unload tab  61  at its tip. Gimbal section  55  is provided for supporting magnetic read/write heads or sliders  80  while maintaining flexibility to accommodate pitch and roll relative to the adjacent spinning disk. The load beam  43  circumscribes the flexure gimbal  55  to form a frame-like structure  57  around gimbal  55 . The us frame  57  merges back together at load/unload tab  61 , beyond the distal end of gimbal  55  such that gimbal  55  is completely surrounded. Structure  57  has a central opening  63  into which protrudes a small rear limiter  65  having an upward-formed tab or ear  67  and a downward-formed ear  69 , as illustrated. Rear limiter  65  and its ears  67 ,  69  are also partially-etched. Ears  67 ,  69  are provided for limiting the displacement of sliders  80  relative to the load beam  43 . 
     A pair of partially-etched flexure legs or outriggers  71 ,  73  extend between opening  63  and rear limiter  65 . Outriggers  71 ,  73  extend forward into opening  63  from approximately the same origin as rear limiter  65  and are separated from contacting the opening  63  frame  57  by a small clearance. However, outriggers  71 ,  73  have a rearward-extending, generally rectangular flexure tongue  75  that protrudes back toward rear limiter  65  but does not contact rear limiter  65  or its ears  67 ,  69 . Flexure tongue  75  has an open window  77  for laser and/or UV light access for curing head bonding adhesives. Note that traces  51  extend from flexure  45  to gimbal  55  and follow along outriggers  71 ,  73 , before winding onto flexure tongue  75 . Magnetic read/write heads or sliders  80  are joined to these distal ends of traces  51 . 
     A front limiter  81  extends forward from the front ends of flexure outriggers  71 ,  73  from the same general area that flexure tongue  75  extends rearward. Like rear limiter  65 , front limiter  81  is partially-etched and has an upward-formed ear  83  and a downward-formed ear  85 . However, the directions of deflection of ears  83 ,  85  are elevationally inverted relative to ears  67 ,  69 , as shown in FIGS. 3 and 4. Front limiter  81  and ears  83 ,  85  do not contact the small tab  87  protruding rearward into opening  63  of frame  57 . Limiters  65 ,  81  limit excessive displacement of sliders  80  during the manufacturing process, loading/unloading, and non-operational shock environments. 
     The invention has several advantages including the elimination of structural formations and additional forming tooling to increase stiffness of the suspension. Unlike prior art two-piece suspension designs, no laser welding is required to assemble the load beam and flexure. This simplification eliminates load beam/flexure assembly tolerances, except for etching tolerances which are minimal. In addition, there is no limiter engagement tolerance due to assembly. The head termination and slider bonding process is flexible to accommodate different applications, and is gold and/or solder ball compatible. The exposed flexure legs make pitch/roll static attitude adjustments possible without the need to offset the flexure legs, while the ears limit excessive slider motion relative to the load beam and improve; the HGA&#39;s integrity. The partially-etched load beam increases the natural frequencies of the suspension with minimal mass and inertia. The suspension is very flat and free of mechanical and thermal distortions, thereby reducing air flow-induced vibration. This suspension design is compatible with integrated lead suspensions (ILS) with either subtractive or additive processing. Integrating the ILS flexure with the load beam can also provide extra damping due to the imbedded polymer. This design is also more flexible in terms of part length variation for different drive platforms such that design convergence is possible. 
     While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.