Abstract:
A method producing a limiter and flexure configuration that includes a flexure that has a first section attached to the load beam, and a second section defining a slider mounting section and a frame that defines an aperture into which the slide mounting section extends in a direction towards the first section, and terminating in an end that interacts with the free end of the limiter. The aperture is sized and positioned to provide a clearance allowing the limiter to freely move through the aperture such that the limiter is free to be bent from the first position to the second position and to extend through the aperture after the flexure assembly has been attached to the load beam. The limiter is bent from the first position to the second position, extending through the aperture, after the flexure assembly has been attached to the load beam.

Description:
This is a Divisional of U.S. patent application Ser. No. 09/676,216, filed Sep. 28, 2000 now U.S. Pat. No. 6,965,501. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to magnetic disk storage systems, and more particularly, to a head suspension assembly for use in a magnetic disk storage system. 
   2. Description of Related Art 
   Magnetic disk drives are information storage devices that utilize at least one rotatable magnetic media disk having concentric data tracks defined for storing data, a magnetic recording head or transducer for reading data from and/or writing data to the various data tracks, a slider for supporting the transducer in proximity to the data tracks typically in a flying mode above the storage media, a suspension assembly for resiliently supporting the slider and the transducer over the data tracks, and a positioning actuator coupled to the transducer/slider/suspension combination for moving the transducer across the media to the desired data track and for maintaining the transducer over the data track center line during a read or a write operation. The magnetic media disk or disks in the disk drive are mounted to a spindle. The spindle is attached to a spindle motor, which rotates the spindle and the disks to provide read/write access to the various portions on the concentric tracks on the disks. 
   One type of suspension is an integrated lead suspension assembly that includes a load beam, a flexure, and a mount plate. The flexure assembly is supported at its forward portion on a gimbal for allowing gimballing of the slider/magnetic head combination, and mounts at its rearward portion to the load beam. The actuator shifts the load beam generally radially across the disk to carry the head to all desired portions of the disk. The main function of a load beam is to suspend the flexure along with a slider/magnetic head assembly at a desired position and at the same time apply pre-load to the head assembly. The pre-load is typically exerted by the rearward spring area portion of the load beam. The flexure assembly may include an integrated assembly of a layer of flexible metal, and electrical traces separated from the metal layer by an insulation layer. 
   The prior art integrated lead suspension assembly has a number of drawbacks. Prior art shows different methods of bonding of the electrical leads to the slider on the flexure assembly. Ultrasonic bonding methods involve clamping on the slider through the load beam, which requires a wider load beam tip to facilitate a clamping means (e.g., see U.S. Pat. No. 5,892,637). However, the external excitation acting upon the wide load beam results in torsional (off track) and in-plane bending modes that are at lower resonance frequencies during operation of the disk drive, which are undesirable as they affect the dynamic performance of the drive. Other clamping approach permits narrower load beam tip, but such load beam structures exclude a lift tab for interacting with a ramp for head loading and unloading (e.g., see U.S. Pat. No. 6,021,022). 
   Prior art integrated lead suspensions include a limiter for limiting the separation of the flexure from the load beam during unload operation of the slider from the disk. However, because of the relative location of the slider and the limiter, the limiter in prior art is known to slide away from the load beam during high shock in the unloaded position. The limiter location also causes higher force to pull the slider off the disk. 
   Prior art also requires prebending of the limiter on the load beam before attachment of the flexure to the load beam. The steps required for this structure create difficulties in manufacturing. 
   It is desirable to design an integrated lead suspension assembly that overcomes the above-mentioned drawbacks. 
   SUMMARY OF THE INVENTION 
   The integrated lead suspension assembly design of the present invention overcomes many of the drawbacks in the prior art. In accordance with one aspect of the present invention, a solder ball bonding technique is applied to bond the electrical traces to a slider. A novel configuration of the terminating pads for the electrical traces and the adjacent insulation layer on the flexure assembly facilitates laser solder ball bonding of the pads to the read/write terminal contacts on the slider. The pads are oversized with respect to the insulation layer to prevent damage to the insulating layer during laser bonding process. Laser solder ball bonding process does not require clamping of the components through the tip region of the load beam. Consequently, the tip of the load beam can be made narrow while providing a structure permitting head loading and unloading functions, which improves the dynamic performance of the suspension assembly. 
   In a further aspect of the present invention, the limiter is configured and positioned to minimize the possibility of disengagement of the limiter and the flexure assembly during unloading of the slider from the disk or under high shock environment. In accordance with one embodiment of the present invention, the limiter is located on the leading edge side of the slider. Due to the dynamics of this configuration, there is a tendency for the flexure assembly to flex towards the load beam limiter hook, thus keeping the flexure assembly against the load beam and from disengaging from the load beam. 
   In accordance with another aspect of the present invention, the flexure assembly is configured such that it requires no permanent bending (as opposed to flexing) in its forming process, and any permanent bending required is done to the load beam. This improves better tolerance control in view of the flat structure. This also simplifies processing, since the flexure assembly comprises thinner and more delicate components of traces, insulation and backing layer, which are more difficult to be accurately bent and handled. In another aspect of the present invention, the limiter that limits the travel of the flexure assembly is formed on the load beam and it is bent to the functional position only after attachment of the flexure assembly to the load beam. 
   Other improvements in accordance with the present invention include providing asymmetric steel backing branches for the read and write traces in the flexure assembly located at the hinge area of the load beam. To improve the flexibility at the hinge area, a cutout is provided to remove the section of the backing, which does not support traces. The widths of the branches of the backing adjacent the cutout are sized to optimize the dynamic signal performance of the read and write traces. 
   Low profile flanges are provided along the edges of the load beam to optimize bending stiffness and flow induced vibration. In accordance with one embodiment of the present invention, a 30°–60° bend from the plane of the load beam would provide improved dynamic characteristics. Dimples may be provided along the load beam to facilitate insertion of a plastic head separation tool. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature and advantages of the present invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings. In the following drawings, like reference numerals designate like or similar parts throughout the drawings. 
       FIG. 1  is a top view of the suspension assembly with side views of the flanges. 
       FIG. 2  is an exploded top view of the suspension assembly, which includes the flexure assembly, the stainless steel load beam, and the mount plate. 
       FIG. 3  is an exploded view of the flexure assembly of the suspension as shown in  FIG. 1 , including a stainless steel backing layer, a polyimide insulation layer, and a copper trace/conductor lead layer. 
       FIG. 4  is an enlarged top view of the suspension assembly tip region with all of its component layers: the stainless steel load beam and the three flexure layers (stainless steel trace, polyimide insulation, copper trace/conductor lead). 
       FIGS. 5A–5F  are sectional views along different sections of the suspension assembly as shown in  FIG. 4 . 
       FIG. 6  is an enlarged side view of the suspension assembly tip region as shown in  FIG. 1 . 
       FIGS. 7A–C  are enlarged views of the exploded parts of the flexure assembly tip region as shown in  FIG. 3 . 
       FIG. 8  is a perspective view illustrating loading and unloading of the slider/suspension assembly with respect to the disk. 
       FIG. 9  is a perspective view of the load/unload ramp dynamics. 
       FIG. 10  is a simplified drawing of a magnetic recording disk drive system. 
       FIG. 11  is a perspective view of a disk drive. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   This invention is described in a preferred embodiment in the following description with reference to the figures. While this invention is described in terms of the best mode for achieving this invention&#39;s objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the invention. 
   Referring now to  FIG. 10 , there is shown a disk drive  120  embodying the suspension of the present invention. As shown in  FIG. 10 , at least one rotatable magnetic disk  122  is supported on a spindle  126  and rotated by a disk drive motor  130 . The magnetic recording media on each disk is in the form of an annular pattern of concentric data tracks (not shown) on the disk  122 . 
   At least one slider  124  is positioned on the disk  122 , each slider  124  supporting one or more magnetic read/write heads  134 . As the disks rotate, the slider  124  is moved radially in and out over the disk surface  136  so that the heads  134  may access different portions of the disk where desired data is recorded. Each slider  124  is attached to a positioner arm  132  by means of a suspension  128  to form a head gimbal assembly. The suspension  128  provides a slight spring force, which biases the slider  124  against the disk surface  136 . Each positioner arm  132  is attached to an actuator  142 . 
   During operation of the disk storage system, the rotation of the disk  122  generates an air bearing between the slider  124  and the disk surface  136  which exerts an upward force or lift on the force of the suspension  128  and supports the slider  124  off and slightly above the disk surface by a small, substantially constant spacing during normal operation. 
   The various components of the disk storage system are controlled in operation by control signals generated by a control unit  146 , such as access control signals and internal clock signals. Typically, the control unit  146  comprises logic control circuits, storage chips and a microprocessor. The control unit  146  generates control signals to control various system operations such as drive motor control signals on line  138  and head position and seek control signals on line  144 . The control signals on line  144  provide the desired current profiles to optimally move and position the slider  124  to the desired data track on the disk  122 . Read and write signals are communicated to and from the read/write heads  134  by means of a recording channel  140 . 
   The above description of a typical magnetic disk storage system, and the accompanying illustration of  FIG. 10  are for representation purposes only. It should be apparent that disk storage systems may contain a large number of disks and actuators, and each actuator may support a number of sliders. 
     FIG. 11  shows a hard disk drive  150  using the suspension of the present invention. The cover  154  of the disk drive is shown exploded. In operation, the cover would be disposed on top of the housing  152 . The disk drive  150  comprises one or more magnetic disks  156 . The disks may be conventional particulate or thin film recording disks, which are capable of storing digital data in concentric tracks. In a preferred embodiment, both sides of the disks  156  are available for storage, and it will be recognized by one of ordinary skill in the art that the disk drive  150  may include any number of such disks  156 . 
   The disks  156  are mounted to a spindle  158 . The spindle  158  is attached to a spindle motor (not shown), which rotates the spindle  158  and the disks  156  to provide read/write access to the various portions of the concentric tracks on the disks  156 . 
   An actuator assembly  176  includes positioner arm  160 , and a suspension assembly  162 . The suspension assembly  162  includes a slider/transducer assembly  164  at its distal end. Although only one slider/transducer assembly  164  of the suspension assembly  162  is shown, it will be recognized that the disk drive  150  has one slider/transducer assembly  164  for each side of each disk  156  included in the disk drive  150 . The actuator assembly  176  further comprises a pivot  172  around which the actuator  176  with positioner arm  160  pivots. 
   The main function of the actuator assembly  176  is to move the positioner arm  160  around the pivot  172 . Part of the actuator assembly  176  is the voice coil motor (VCM) assembly  174 , which comprises a VCM bottom plate, one or more magnets, and a VCM top plate in combination with an actuator coil. Current passing through the actuator coil interacts with the magnetic field of the magnets to rotate the positioner arm  160  and suspension assembly  162  around the pivot  172 , thus positioning the slider/transducer assembly  164  as desired. 
   Most disk drives  150  have a number of disks  156  mounted on the spindle  158  to form a disk stack  170 . The actuator assembly  176  comprises a plurality of positioner arms  160  fixed in a comb-like arrangement such that the inner arms  165  fit between the disks  156  forming disk stack  170  and the outer arms  166 ,  168  extend over the top surface of the top disk and the bottom surface of the bottom disk, respectively. The inner arms  165  each support two suspension assemblies  162  (upper and lower suspension assemblies) with attached slider/transducer assemblies  164 . The upper outer arm  166  supports one suspension assembly  162  with its slider/transducer assembly  164  to access data on the top surface of the top disk of disk stack  170 . The lower outer arm  168  supports one suspension assembly  162  with its slider/transducer assembly  164  to access data on the bottom surface of the bottom disk of disk stack  170 . 
     FIG. 1  shows a top view of a suspension assembly  10  according to one embodiment of the present invention for use in the disk drive in  FIG. 11 .  FIG. 2  shows an exploded top view of the suspension assembly  10 , which includes a flexure assembly  22 , a stainless steel load beam  14 , and a mount plate  12 , attached to each other in that order. The suspension assembly carries at its forward portion a gimballing structure comprising the interaction of the load beam and the flexure and slider/magnetic head combination, and mounts at its rearward portion to the actuator (not shown). The suspension assembly  10  supports a slider  40  near a limiter  50  and a hook  60 . A head lift  58  extends from the tip region  15  of the suspension assembly  10 . 
   Along the suspension assembly  10  are various openings in the load beam  14 , flexure  22 , and mount plate  12 , which overlap when the components are stacked. These openings not only act as guides for placement, but also efficiently reduce the overall mass of the suspension assembly  10 . In  FIG. 2 , the flexure rear opening  76 , the load beam mid opening  78 , and the plate opening  80  are lined up as the suspension assembly  10  components are stacked. In addition, the flexure front opening  72  and the load beam front opening  74  are lined up. Swaging hole  82  is shown overlapping over load beam hole  86 . 
     FIG. 3  is an exploded view of the flexure assembly  22  of the suspension assembly  10 , as shown in  FIG. 1 . The flexure assembly  22  comprises electrical traces  20 , a polyimide insulation  18 , and a stainless steel backing  16 , attached to each other in that order. To join the parts of the suspension assembly  10 , the welding points  4  are used. As can be seen in  FIG. 1 , the welding points  4  are placed so that welding only occurs with the stainless steel backing  16  of the suspension assembly  10 , avoiding the polyimide insulation  18  and traces  20 . The welding points  4  at wings  70  on the steel backing  16  join the flexure assembly  22  to the load beam  14 . The flexure assembly  22  has read traces  26  and write traces  28 , one end of which terminating at the connector  84  at the rearward portion of the suspension assembly  10 , and another end terminating at the pads  42  near the slider  40 . The traces provide electrical connections between the read/write heads on the slider and the control system (shown in  FIG. 10 ). 
   Referring also to  FIG. 2 , for better mechanical and electrical performance, the flexure assembly  22  splits into branches  45  and  47  of unequal width at the cutout  44  at the hinge region (line  2 — 2 ) of the suspension assembly  10 . At this region, the flexure assembly  22  has a symmetric boundary for mechanical balance, but it has the asymmetric branches  45  and  47  for improved electrical characteristics of the traces  26  and  28  according to data signal response requirements. The asymmetric cutouts  44  accommodate different widths of read trace  26  and write trace  28  (see also  FIG. 5E ), which are fully backed with stainless steel backing  16  for uniform impedance requirement of high data rate and better structural integrity of the traces as they are subject to flexing during operation. To accommodate the different requirements of the read and write signals, the read traces  26  are wider than the write traces  28 , thus requiring a wider branch  47  along the flexure assembly  22 . 
     FIGS. 1 and 2  show that the load beam  14  is pre-bent to define a hinge  46  along line  2 — 2 , which allows bending of the load beam at the hinge during loading and unloading of the slider  40  with respect to the disk. Bending at hinge  46  is in a direction away from the mount plate  12  and towards the flexure assembly  22 , so as to provide a preload spring force on the slider when it is loaded onto the disk.  FIG. 6  shows an enlarged side view of the suspension assembly tip region  15 . In this view, a disk (not shown) rotates below the slider  40  in the direction of the arrow  32 , as an air bearing exists between the disk and the slider  40 . The hinge  46  allows the load beam  14  to bias the slider  40  towards the surface of the disk during operating conditions. 
   To further provide a biasing force, a dimple  48  on the load beam  14  is used. Since the dimple  48  protrudes toward the flexure assembly  22 , thus towards the slider  40  and the surface of the disk (not shown), the load beam  14  biases the slider  40  to the disk. The air bearing, or the cushion on which the slider  40  sits, provides a counterforce to maintain the suspension assembly  10  at the proper distance from the disk. The pivoting feature of the dimple  48  also provides flexibility in the flexure assembly  22  so that it can adapt to variations in disk surfaces as well as in different disk operating conditions. 
     FIGS. 5A–5E  show sectional views of the suspension assembly  10  as shown in  FIG. 4 . The edges of the load beam  14  are bent, which forms flange  30 , to improve the rigidity of the generally flat load beam  14 . In accordance with another aspect of the present invention, the flange  30  of the load beam  14  is set at an angle between 30°–60° to the plane of the load beam (e.g., 45°), which would allow an acceptable compromise between high bending stiffness and low flow-induced vibration. The lower profile of the load beam  14  results in less excitation caused by air turbulence, which maintains adequate stiffness of the load beam  14 . 
     FIG. 5F  shows the sectional view of the suspension assembly  10  at the terminating pads  42 . This sectional view, taken along line  5 F— 5 F in  FIG. 4 , shows that the size of the copper pad  42  is slightly bigger than that of the insulating pad  43  such that the copper pad  42  extends over the insulating pad  43  on the side of the slider  40 . In accordance with one aspect of the present invention, laser solder ball bonding may be applied to join the contacts of the read/write heads on the side of the slider  40  to the copper pads  42 .  FIG. 7C  shows the relative placement of the slider  40 , the read/write contacts  41 , and the copper pads  42 . When a laser is used to reflow a solder ball to connect the slider read/write contact pads  42  to the copper pad  42 , the oversized copper pads  42  prevent the edges of the polyimide insulation pads  43  underneath them from burning, which may also lead to damage to the entire insulation pads and the insulation under the neighboring traces. When the electrical traces  20 , insulation  18 , and steel backing  16  are stacked, the copper pads  42  and the polyimide insulation pads  43  are suspended over the opening  34  without the support of the stainless steel backing  16 . This configuration prevents potential electrical shorting by the steel backing  16  in the event the insulation pads  43  are defective. 
   Prior art uses ultrasonic bonding operations to bond the pads to the slider. This typically requires clamping of the slider support and the terminating leads of the traces through the load beam opening. Since laser solder ball bonding techniques are used with the present invention, no clamping of the components is required during the bonding process. Without such clamping, the present invention overcomes the drawback associated with the requirements for clamping the slider through load beam window (see U.S. Pat. No. 5,892,637) or exposed flexure tongue (see U.S. Pat. No. 6,021,022). In accordance with the present invention, the load beam tip can be made narrow for a suspension without compromising the structure for the load/unload function (see discussion below). Referring to FIG.  4 ., it can be seen that the width of the tip section of the load beam below the slider  40  is about the same or less than the width of the slider  40 . For prior art narrow load beam applications, the load beam does not extend beyond the slider to provide a lift tab to permit head loading and unloading functions. For prior art wide load beam tip applications (the width of the load beam being significantly larger than the width of the slider) that have head loading and unloading functions, the external excitation acting upon the wide load beam results in torsional (off track) and in-plane bending modes that have lower resonance frequencies during operation of the disk drive, which are undesirable as they affect the dynamic performance of the drive. Thus, the narrow load beam  14  is designed for improved dynamic performance by pushing the resonance modes to higher frequencies while providing head loading and unloading functions. 
   At the forward position of each suspension assembly  10  is a “lift tab,” or a head lift  58 .  FIG. 8  shows a simplified view of the movement of the suspension assembly  10  between “load” and “unload” positions with respect to a disk  11  in the disk drive  150  (shown in  FIG. 11 ). A ramp mechanism  36  is employed to lift the heads from each disk surface as the suspension assembly that supports the read/write head travels beyond the disk&#39;s perimeter, where the heads are “parked” outside of the disk stack. The actuator  76  is shown to move the suspension assembly  10  to access the disk surface at the “load” position  19   b  and to rest at a parked position  19   a . The sectional view of the head lift  58  is shown in  FIG. 5A , taken along line  5 A— 5 A in  FIG. 4 . As seen in  FIGS. 8 and 9 , when the actuator  76  moves to the unloaded (or parked) position  19   a  from the loaded position  19   b , the head lift  58  slides over the ramp  36  that extends over the disk surface. The curved shape of the head lift  58  and the ramp  36  cooperate to create a cam action to lift the load beam and the flexure assembly attached thereto (including the slider  40 ). After moving along the ramp  36 , the head lift  58  rests at a detent  37 , where the heads are in the parked position. During head loading, the actuator  76  is turned to move the suspension assembly  10  towards the disk, such that the slider is lowered and supported on the air bearing formed on the rotating disk surface  11  as the head lift  58  is guided down the ramp  36 . To prevent harmful disk surface contact during loading, descent speed of the slider is controlled by controlling the movement of the actuator. 
   To further aid in parking the heads, a novel suspension tip configuration is used, as shown in  FIGS. 2 ,  4 , and  6 .  FIG. 4  is an enlarged top view of a suspension assembly tip region, which includes a flexure tip  15 . At the parked position, the tip  15  rests above a stop  38  with a small gap  88 . Thus the flexure assembly  22  and the slider  40  are prevented from large movement from the load beam  14  during high non-operational shock. The stop  38  is made of plastic, and it may be part of or an extension from the ramp  36 .  FIGS. 2 and 4  are top views of the layers of the stainless steel backing  16  and polyimide insulation  18 . In accordance with one embodiment of the present invention,  FIG. 6 , which is an enlarged side view of the suspension assembly tip region, shows that the polyimide insulation tip  68  extends beyond the stainless steel backing tip  66  (see also  FIG. 4 ).  FIG. 5C , which is the section taken along line  5 C— 5 C in  FIG. 4 , is another view that shows the steel backing  16  with the extended polyimide insulation  18 . During non-operational shock, the flexure insulation tip  68  protects the stop  38  from abrasion by the stainless steel backing tip  66  since only the extended insulation tip  68  contacts the supporting stop  38 . Otherwise, the steel backing tip  66  could cut or scrape the plastic stop  38 , causing plastic dust particles that could contaminate the disk drive operating environment, leading to head read/write failure. 
   While  FIG. 6  shows only one suspension assembly  10 , ramp  36 , and stop  38 , it is noted that additional components can be stacked to complement a stack of disks in a disk drive assembly. The ramps  36  and stops  38  may be configured in a generally comb shaped configuration, with each “prong” of the “comb” functionally cooperating with the adjacent surfaces of two adjacent disks. 
     FIG. 6  shows the relative orientation of the slider  40  and the flexure assembly  22  to a limiter  50 . The limiter  50  extends generally perpendicularly from the plane of the load beam  14 . Its purpose is for limiting the extent by which the flexure assembly  22  can move away from the load beam  14 . Otherwise, the flexure assembly  22  may be damaged when the separation of the flexure assembly  22  from the load beam  14  exceeds its design limit. By interacting with the hook  60  on the flexure assembly  22 , the limiter  50  on the load beam  14  initially lifts the flexure hook  60  of flexure tongue  16  (which supports the slider  40 ) during head loading and unloading operations against the air bearing suction on the slider  40 . As seen in  FIG. 6 , the limiter  50  is located at the leading edge  52  side of the slider  40  (the direction of disk rotation is indicated by the arrow  32 ). The limiter  50  engages with the hook  60  of the stainless steel backing  16  in the flexure assembly  22 . The top view in  FIG. 4  shows the placement required for the limiter  50  and hook  60  during assembly of the flexure assembly  22  to the load beam  14  for proper engagement of the hook  60  and the limiter  50 . In this view, the limiter  50  is shown in its initial configuration as it is formed flat in the plane of the load beam  14 . The inner curve  62  of the unbent limiter  50  fits with the inner curve  64  of the hook  60 .  FIG. 5D , a sectional view taken along line  5 D- 5 D in  FIG. 4 , shows the engagement of the limiter  50  to the hook  60  of the stainless steel backing  16 , but in this view the limiter  50  is bent from its initial position to a position perpendicular to the plane of the load beam  14  (arrow  39 ). With the limiter configuration as shown, the flexure assembly  22  and the load beam  14  are formed without having to bend to form a vertical limiter extending from the structures. All components are kept generally flat (see  FIG. 4 ) until the last step of manufacturing, in which bending of the limiter  50  is undertaken to position the limiter  50  in a functional manner with respect to the hook  60 . Prior art limiters had to be bent prior to assembling the flexure assembly to the load beam. 
   The configuration and positioning of the limiter  50 , as described above, also minimizes the possibility of disengagement of the limiter  50  and the hook  60  when the disk drive is subject to high shock. Prior art limiter configuration and placement are less secure in the engagement of the flexure assembly  22  when subject to high shock. The present invention&#39;s placement of the limiter  50  improves the functional integrity of the limiter. As seen in  FIG. 6 , the limiter  50  is located at the leading edge  52  side of the slider  40 . The tip of the limiter  50  points away from the slider  40 . During loading and unloading and the parked position, the dynamics of the air bearing suction causes a positive pitch  56  about the dimple  48  and the slider  40  separated from the dimple  48 . With the limiter  50  positioned at the leading edge  52  side of the slider  40 , the positive pitch  56  and the separation between the dimple  48  and the slider  40  tend to cause the flexure hook  60  to move towards the load beam limiter  50 . The limiter  50  catches against the hook  60  and reduces the likelihood of the limiter  50  disengaging from the hook  60  of the flexure tongue  16  of the flexure assembly  22 . Consequently, the slider  40  and the flexure assembly  22  are less likely to separate from the load beam  14  beyond their design limit. 
   During manufacturing of an actuator assembly  76  comprising a stack of suspension assemblies, the suspension assemblies should be maintained separated in a manner that maintains clearance between adjacent sliders. The sliders/heads of two opposite facing adjacent suspension assemblies face each other. A plastic head separation tool in the shape of a comb has been used in the past to separate the suspension assemblies to prevent damage to the air bearing surface of the slider  40 . The finger of the comb shaped tool is inserted between two opposite facing adjacent suspension assemblies. In accordance with another aspect of the present invention, to facilitate insertion of the head separation tool, dimples  24  are provided on the load beam  14 .  FIG. 5E  shows two dimples  24 , which are aligned transversely relative to the load beam longitudinal axis. The sectional view in  FIG. 5E  shows wider read trace  26  and narrower write trace  28  that run between the two dimples  24 , which protrude on the side of the traces  26  and  28 . The dimples  24  serve as cam surfaces for head separation tool insertion between adjacent facing suspension assemblies, and prevent damage to the traces. Given that the head separation tool is made of a plastic material that could otherwise be chipped by the sharp edges of the stainless steel layer  16  of the flexure assembly, the dimples  24  reduce the abrasion against the tool. This in turn reduces stray dust arising from abrasion, which would be damaging to the operation of the disk drive. Although one dimple would suffice for facilitating insertion of the head separation tool, the use of two dimples  24  provides symmetry to allow tool insertion from either side of the load beam  14 . 
   While the present invention has been particularly shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit, scope, and teaching of the invention. Accordingly, the disclosed invention is to be considered merely as illustrative and limited in scope only as specified in the appended claims.