Abstract:
A stainless steel dual stage actuated disk drive head suspension baseplate including a plated electrical contact area having nickel and gold. The baseplate can be heat treated. The nickel and gold can be in a mixture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/531,571, filed on Nov. 3, 2014, which is a continuation of U.S. patent application Ser. No. 13/114,212, filed May 24, 2011, now U.S. Pat. No. 8,885,299, issued Nov. 11, 2014, which claims the benefit under 35 U.S.C. 119 of Provisional Application No. 61/396,239, filed May 24, 2010, which are incorporated herein by reference in their entirety for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to suspensions for disk drives. In particular, the invention is a dual stage actuation (DSA) suspension and method of manufacture. 
       BACKGROUND OF THE INVENTION 
       [0003]    Dual stage actuation (DSA) disk drive head suspensions are generally known and commercially available. By way of example, one embodiment of a DSA head suspension  10  is shown in  FIGS. 1A and 1B . The illustrated DSA suspension includes a baseplate  12 , hinge  14  or spring region, load beam  16  and integrated lead flexure  18  with traces  20 . The hinge  14  is mounted to the baseplate  12  and extends from the distal end of the baseplate. The load beam is mounted to the distal end of the hinge  14 . The flexure  18  is mounted to the load beam  16 , typically on the side of the load beam mounted to the hinge  14 . Welds such as  22  are typically used to join these components. The baseplate  12 , hinge  14  and load beam  16  are typically formed from stainless steel, and the flexure  18  typically includes a base layer of stainless steel. The copper or copper alloy traces  20  on the flexure  18  are separated from the stainless steel base layer by a layer of polyimide or other insulator. 
         [0004]    The second stage actuation functionality of the illustrated DSA suspension  10  is incorporated into the baseplate  12 . As shown, the baseplate  12  has one or more motor-receiving areas or openings  24  (two in the illustrated embodiment). Piezoelectric (PZT) motors  26  are mounted to the baseplate  12  in the motor-receiving openings  24 . The motors  26  are mounted to tabs  28  extending from the baseplate  12  into the motor-receiving openings  24 . In the illustrated suspension  10  the tabs  28  are portions of the hinge  14 . In other embodiments (not shown) the tabs  28  to which the PZT motors  26  are mounted can be other components such as a separate motor plate welded to the baseplate. Epoxy or other adhesive is typically used to mount the motors  26  to the tabs  28 . 
         [0005]    DSA suspensions can be embodied in still other forms. For example, an alternative DSA suspension structure is illustrated and described in the Okawara U.S. Patent Publication No. 2010/0067151 which is incorporated herein by reference in its entirety and for all purposes. Briefly, the suspension shown in the Okawara publication has an actuator plate to which the motors are mounted. The actuator plate is mounted between the baseplate and hinge. In still other DSA suspensions (not shown), the motors can be mounted to the load beam or hinge. 
         [0006]    An electrical connection or conductive joint between an electrical ground contact on a face of the motor and the ground plane of the suspension is typically made by conductive adhesive (e.g., epoxy with silver and/or nickel particles). The ground contacts on the motors typically have an external plated gold (Au) layer. These connections are typically formed by applying a mass of the conductive adhesive at a location where the ground contact of the motor is adjacent to a stainless steel portion of the baseplate, load beam, hinge or flexure. The conductive adhesive contacts both the motor ground contact and the stainless steel portion of the suspension, thereby providing an electrical connection or ground joint from the motor to the stainless steel portions of the suspension that function as the ground plane. 
         [0007]    The conductive joint between the motor and the ground plane should be capable of functioning at or below a threshold level of acceptable resistance under all applied processing and operational load conditions. However, consistently maintaining acceptable resistance to ground levels has been difficult. In particular, the resistance of the conductive adhesive-to-stainless steel component joints have been determined to be relatively high and unstable. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the invention include a stainless steel disk drive head suspension baseplate including a plated contact area. The plated contact area comprises nickel and gold. In embodiments, the plated contact area comprises a mixture of nickel and gold. The baseplate and contact area are heat treated in embodiments. The baseplate is a dual stage actuated baseplate in embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1A  is an isometric illustration of the flexure side of a prior art dual stage actuation (DSA) suspension. 
           [0010]      FIG. 1B  is an isometric illustration of the opposite, baseplate side of the prior art suspension shown in  FIG. 1A . 
           [0011]      FIG. 2  is a plan view illustration of a portion of a DSA suspension in accordance with an embodiment of the invention having a plated flexure. 
           [0012]      FIG. 3  is a plan view illustration of an alternative embodiment of the suspension shown in  FIG. 2 . 
           [0013]      FIG. 4  is a side view illustration of a portion of a DSA suspension in accordance with another embodiment of the invention having a plated flexure. 
           [0014]      FIG. 5  is a plan view illustration of the suspension shown in  FIG. 4 . 
           [0015]      FIG. 6  is a plan view illustration of a portion of a DSA suspension in accordance with another embodiment of the invention having a formed flexure tab. 
           [0016]      FIG. 7  is a side view illustration of the suspension shown in  FIG. 6 . 
           [0017]      FIGS. 8 and 9  are plan view illustrations of portions of a DSA suspension in accordance with another embodiment of the invention having a plated hinge. 
           [0018]      FIGS. 10 and 11  are plan view illustrations of portions of a DSA suspension in accordance with another embodiment of the invention having a plated hinge having a tab. The tab is shown unformed in  FIG. 10  and formed in  FIG. 11 . 
           [0019]      FIG. 12  is an isometric illustration of the suspension shown in  FIG. 11 . 
           [0020]      FIGS. 13 and 14  are plan view illustrations of portions of a DSA suspension in accordance with another embodiment of the invention having a plated add-on feature. 
           [0021]      FIG. 15  is a plan view illustration of a plated unformed baseplate in accordance with another embodiment of the invention. 
           [0022]      FIG. 16  is a plan view illustration of the plated baseplate in  FIG. 15  in the formed state. 
           [0023]      FIG. 17  is a plan view illustration of a portion of a DSA suspension in accordance with an embodiment of the invention having a plated plug. 
           [0024]      FIG. 18  is a plan view illustration of the baseplate and plated plug components of the suspension shown in  FIG. 17 . 
           [0025]      FIG. 19  is a cross section side view illustration of the assembled baseplate and plated plug components shown in  FIGS. 17 and 18 . 
       
    
    
     DETAILED DESCRIPTION 
     Overview 
       [0026]    The invention is a dual stage actuation (DSA) suspension having a stable, low resistance conductive adhesive electrical connection or joint between an electrical contact on a motor of the suspension and a plated metal contact area on a stainless steel component of the suspension. One embodiment of the invention includes a ground joint between the electrical contact of a piezoelectric (PZT) motor and a gold or nickel gold plated contact area on the stainless steel suspension component. The gold or nickel gold or other conductive and generally non-corrosive metal or alloy plated area on the stainless steel suspension component is referred to generally in the description of the invention below as the plated region. In still other embodiments a layer of nickel is plated on the stainless steel, and a gold layer is plated on the nickel layer. 
         [0027]    As described below in connection with the attached drawing figures, the invention can be embodied in a number of different structures. For example, the invention can be embodied in DSA suspensions such as that described above in connection with  FIGS. 1A and 1B . Alternatively, the invention can be embodied in DSA suspension structures of the type disclosed in the Okawara U.S. Patent Publication No. 2010/0067151. For example, the stainless steel suspension component to which the ground joint is made can be a baseplate, load beam, hinge, motor plate, flexure or other component. The plated contact area on the stainless steel suspension component can be heat treat annealed. In some embodiments of the invention, the plated contact surface retains a full surface coverage of the plated alloy. In other embodiments of the invention the plated contact surface includes approximately 98% stainless steel and 2% gold following the heat treat and annealing process. In yet other embodiments, the plated contact surface includes about 90% stainless steel surface and about 10% gold. Only the portion of the component to which the conductive adhesive ground joint is being made need be plated (e.g., patterned and selectively plated), although in other embodiments larger areas or even the entire component surface can be plated. 
         [0028]    The invention provides a reliable, stable and low resistance joint between the conductive adhesive and the plated stainless steel contact area. The desired resistance level can vary with the application of the suspension (e.g., with the drive circuitry that the motor is to be connected). One example specification calls for ground contact resistance levels no greater than 2500 ohms. Another specification calls for resistance levels no greater than 100 ohms. Still other embodiments of the invention have a resistance no greater than 10 ohms and even less than 1 ohm over the life of the suspension. 
       Plated Flexure Embodiments 
       [0029]      FIGS. 2  illustrates portions of a suspension  110  in accordance with an embodiment of the invention having a through hole or opening  130  in the baseplate  112  that exposes a gold plated contact  132  on the flexure  118 . Features of the suspension  110  that are similar to those of suspension  10  described above in connection with  FIGS. 1A and 1B  are identified by similar reference numbers in the “100” series. Conductive adhesive  134  extends from the motor contact  136 , over the baseplate  112 , into and through the baseplate opening  130 , and to the plated flexure contact  132 . The plated contact  132  on the flexure  118  can be a contact plated directly onto the stainless steel base layer of the flexure  118 . In an alternative embodiment shown in  FIG. 3  illustrating portions of suspension  110 ′ a through hole  131 ′ is etched or otherwise formed through the stainless steel base layer of the flexure  118 ′ to expose a plated portion of a trace  120 ′ on the flexure. In this alternative embodiment the conductive adhesive  134 ′ extend through the holes  130 ′ and  131 ′ in the baseplate  112 ′ and the flexure  118 ′, and contacts the plated flexure trace  120 ′. 
         [0030]      FIGS. 4 and 5  illustrate portions of a suspension  210  in accordance with another embodiment of the invention. Features of the suspension  210  that are similar to those of suspension  10  described above in connection with  FIGS. 1A and 1B  are identified by similar reference numbers in the “200” series. In this embodiment the mass of conductive adhesive  234  extends from the motor contact  236 , over the edge of the motor  226 , into a gap  227  between the motor and baseplate  212 , and into contact with the plated contact region  232  on the flexure  218 . As with the embodiment shown in  FIGS. 2 and 3 , the plated contact  232  on the flexure  218  can be on the stainless steel base layer or on a trace exposed at a through hole (not shown) in the flexure. Non-conductive adhesive  233  is used to mount the motor  226  to the hinge tabs  228  and isolate the second (bottom) electrode of the motor from the conductive adhesive  234  of the ground joint. 
       Formed Flexure Embodiments 
       [0031]      FIGS. 6 and 7  illustrate portions of a suspension  310  in accordance with another embodiment of the invention having a flexure  318  with a tab  360  or paddle on the stainless steel base layer  361  that has a plated contact  362 . Features of the suspension  310  that are similar to those of suspension  10  described above in connection with  FIGS. 1A and 1B  are identified by similar reference numbers in the “300” series. The flexure tab  360  is formed (e.g., two 90° bends  363 ,  364  are shown) to extend out of the plane of the other portions of the flexure  318 , through a gap  365  between the baseplate  312  and motor  324 , and into contact with the ground contact  336  on the motor. A mass of conductive adhesive  334  joins the plated contact  362  on the formed flexure tab  360  to the motor ground contact  336 . 
       Plated Hinge Embodiments 
       [0032]      FIGS. 8 and 9  illustrate portions of a suspension  410  in accordance with another embodiment of the invention having a plated contact  470  on a portion of the hinge near or adjacent to the motor  426  (e.g., the hinge motor tab).  FIG. 9  shows the suspension  410  after a de-tabbing step relative to  FIG. 8 . Features of the suspension  410  that are similar to those of suspension  10  described above in connection with  FIGS. 1A and 1B  are identified by similar reference numbers in the “400” series. The conductive adhesive  434  extends from the motor contact  436  over the edge of the motor  426  and into contact with the plated contact  470  on the hinge  414 . In the illustrated embodiments the conductive adhesive  434  also extends over a portion of the baseplate  412  and the edge of the baseplate. 
         [0033]      FIGS. 10-12  illustrate portions of suspension  510  in accordance with another embodiment of the invention having a formed plated hinge  514 . Features of the suspension  510  that are similar to those of suspension  10  described above in connection with  FIGS. 1A and 1B  are identified by similar reference numbers in the “500” series. A plated contact  570  is formed on a tab  580  extending from the hinge  514 . The tab  580  is shown in an unformed state in  FIG. 10 . During suspension  510  assembly the tab  580  is formed to extend up the edge and over the baseplate  512  at a location adjacent to the motor  526 . The conductive adhesive  534  extends between the motor ground contact  536  and the plated contact  570  on the formed tab  580 , across the baseplate  512 . 
       Add-On Feature Embodiments 
       [0034]      FIGS. 13 and 14  illustrate portions of a suspension  610  in accordance with another embodiment of the invention including a separately manufactured plated element or feature  682  that is welded (e.g., by welds  622 ) or otherwise attached to the baseplate  612  adjacent to the motors  626 . The conductive adhesive  634  extends from the motor contact pad  636  to the plated surface  681  of the feature  682 , over the edge of the feature.  FIG. 14  shows the suspension  610  after a de-tabbing step and application of conductive adhesive  634  relative to  FIG. 13 . 
       Plated Baseplate Embodiments 
       [0035]      FIGS. 15 and 16  illustrate plated baseplates  712  in accordance with another embodiment of the invention. A plated stripe  790  is formed on the baseplate stock.  FIG. 15  shows the baseplate  712  unformed. The stock is formed with the plated stripe  790  located adjacent to the motor openings  724  as shown in  FIG. 16 . The mass of conductive adhesive (not shown) will extend between the motor contact (not shown) and the plated portion  790  of the baseplate  712 . 
       Plated Plug Baseplate 
       [0036]      FIGS. 17-19  illustrate portions of a suspension  810  in accordance with another embodiment of the invention including plated stainless steel plugs  892  in the baseplate  812 . Features of the suspension  810  that are similar to those of suspension  10  described above in connection with  FIGS. 1A and 1B  are identified by similar reference numbers in the “800” series. The plated plugs  892  can be manufactured separately from the baseplate  812 , and mechanically forced into holes in the baseplate with the plated surface  893  oriented toward the same side of the baseplate as the motor contacts  836 . The plug  892  can be press fit, coined or otherwise forced into the hole in the baseplate  812  to form a substantial and secure mechanical, and low resistance contact between the plug and baseplate. Coining provides the additional adavantage of leaving a depression that can be useful in adhesive wicking control.  FIG. 19  is a cross section view of an assembled baseplate  812  and plated plug  892 . The conductive adhesive  834  is applied so that it extends between the plated surface  893  of the plug  892  and the motor ground contact  836 . 
         [0037]    Although the invention is described with reference to a number of different embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.