Abstract:
A method of assembling a disk drive includes providing a disk drive base. The method further includes providing a disk drive cover having an inside face and an outside face. The inside face is coated with an electrically insulative material. The method further includes contacting, continuously during a period, the outside face with an electrically conductive grounding element that is part of an assembly fixture that is not part of the disk drive being assembled. The method further includes attaching the disk drive cover to the disk drive base during the period.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to disk drives, and more particularly to a method of assembling a disk drive while electrically grounding a disk drive cover. 
   2. Description of the Prior Art 
   The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The head disk assembly includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA). The spindle motor includes a spindle motor hub that is rotatably attached to the disk drive base. The hub has an outer hub flange that supports a lowermost one of the disks. Additional disks may be stacked and separated with annular disk spacers that are disposed about the hub. The head stack assembly has an actuator assembly having at least one transducer head, typically several, for reading and writing data to and from the disk. The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk. 
   The head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit cable assembly. A conventional “rotary” or “swing-type” actuator assembly typically comprises an actuator body that rotates on a pivot assembly between limited positions, a coil portion that extends from one side of the actuator body to interact with one or more permanent magnets to form a voice coil motor, and one or more actuator arms which that extend from an opposite side of the actuator body. A head gimbal assembly includes a head which is distally attached to each of the actuator arms. The actuator assembly includes the actuator body that has a bore and a pivot bearing cartridge engaged within the bore. The head gimbal assembly and the flex circuit cable assembly are attached to the actuator assembly. 
   A plurality of fasteners, such as metal screws, are disposed about a periphery of the disk drive cover and engage the periphery of the disk drive base for attachment of the disk drive cover with the disk drive base. Typically, a fastener is engaged to the pivot bearing cartridge through the disk drive cover, and another fastener is engaged to the spindle motor also through the disk drive cover. 
   For any number of reasons, it may be desirable to provide a coating, such as E-coating, about the surface of the disk drive cover. For example, the coating may be utilized as a corrosion barrier for protecting the disk drive cover. 
   A problem that is introduced with the application of such a coating upon the disk drive cover is that the coated disk drive cover may become electrically insulated from other portions of the disk drive, because the coating tends to be electrically insulative in nature. In the absence of the coating, the disk drive cover is typically in direct electrical contact with a grounded portion of a fixture utilized to support the disk drive cover during assembly of the disk drive cover to the disk drive base thereby grounding the disk drive cover. On the coated disk drive cover, however, a static electric charge may be built up on the surface of the coated disk drive cover. Unless removed, this static electric charge creates a high voltage potential between the disk drive cover and the other portions of the disk drive that may discharge to any number of the components within the disk drive, such as the transducers. Such a discharge may damage the disk drive components. 
   Accordingly, there is a need in the art for an improved method of assembling the disk drive and in particular grounding the disk drive cover during the attachment process in comparison to the prior art. 
   SUMMARY OF THE INVENTION 
   An aspect of the invention can be regarded a method of assembling a disk drive. The disk drive includes a disk drive cover and a base assembly. The disk drive cover includes a main cover portion having opposing sides and formed of an electrically conductive material. The disk drive cover further includes an electrically insulative coating and a grounding opening formed through the electrically insulative coating. The main cover portion includes an exposed surface at the grounding opening. The method includes mounting the base assembly upon a base support portion of a fixture, and mounting the disk drive cover upon a cover support portion of the fixture. The method further includes positioning the disk drive cover with a grounding element of the fixture in electrical contact with the exposed surface for electrically grounding the disk drive cover. The method further includes attaching the disk drive cover to the base assembly. 
   According to various embodiments, the main cover portion is formed of a metallic material, such as carbon steel or aluminum for example. In another embodiment, the main cover portion may be formed of a plastic material. The grounding element may be formed as a pin, and may be spring loaded. The base assembly may include a disk drive base. The grounding opening may be formed through the main cover portion, and the exposed surface may be an inner surface within the main cover portion. In another arrangement, the exposed surface is disposed upon a respective one of the opposing sides. The grounding element may be in electrical contact with the exposed surface by direct physical contact between the grounding element and the exposed surface. In another arrangement, the grounding element may be in electrical contact with the exposed surface via an intermediate contact element. Upon attaching the disk drive cover to the base assembly, the method may provide for electrically grounding the disk drive cover to the base assembly. In this regard, conductive fasteners may be inserted through fastener openings formed in the disk drive cover into fastener engagement holes formed in the base assembly for attaching the disk drive cover to the base assembly and electrically grounding the disk drive cover to the base assembly. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of a disk drive including a base assembly and a disk drive cover; 
       FIG. 2  is a top plan view of the disk drive cover of  FIG. 1 ; 
       FIG. 3  is a bottom view of the disk drive cover; 
       FIG. 4  is a perspective view of a fixture including a grounding element as shown with the disk drive cover and the base assembly as may be utilized according to the method of assembly of the invention; 
       FIG. 5  is a cross-sectional side view of the fixture of  FIG. 4  as seen along axis  5 — 5  of  FIG. 4 ; 
       FIG. 6  is a cross-sectional side view of the fixture of  FIG. 5 , however as shown with the disk drive cover attached to the base assembly; 
       FIG. 7  is a cross-sectional view of a portion of the disk drive cover at a grounding opening and exposed surface as seen along axis  7 — 7  of  FIG. 2 ; 
       FIG. 8  is a cross-sectional view of a portion of a cover support portion of the fixture with a grounding element in relation to a portion of the disk drive cover of  FIG. 7  as seen along axis  8 — 8  of  FIG. 4 ; 
       FIG. 9  is a cross-sectional view of a portion of the disk drive cover similar to  FIG. 7 , however with a grounding element in a spring loaded configuration; 
       FIG. 10  is a cross-sectional view of a portion of the disk drive cover similar to  FIG. 7 , however with conductive coating at the exposed surface; 
       FIG. 11  is a cross-sectional view of a portion of the disk drive cover similar to  FIG. 7 , however with a conductive adhesive and disk at the exposed surface; 
       FIG. 12  is a cross-sectional view of a portion of the disk drive cover similar to  FIG. 7 , however with an H-shaped grommet at the exposed surface; 
       FIG. 13  is a cross-sectional view of a portion of the disk drive cover similar to  FIG. 7 , however with a T-shaped grommet at the exposed surface; 
       FIG. 14  is a cross-sectional view of a portion of the disk drive cover similar to  FIG. 7 , however with conductive adhesive at the exposed surface; and 
       FIG. 15  is a cross-sectional view of a portion of a disk drive cover support in relation to a portion of the disk drive cover, however with direct contact between the grounding element and the exposed surface. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same,  FIGS. 1–15  illustrate a disk drive assembly process in accordance with the aspects of the present invention. 
   Referring now to  FIG. 1 , there is depicted an exploded perspective view of a disk drive  10  constructed in accordance with an aspect of the present invention. The disk drive  10  includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA). The head disk assembly includes a disk drive base  12  and a disk drive cover  14  that collectively house magnetic disks  16 ,  18 ,  20 . The head disk assembly includes a base assembly  21  and the disk drive cover  14 . The disks  16 ,  18 ,  20  each contain a plurality of tracks for storing data. The head disk assembly further includes a spindle motor  22  for rotating the disks  16 ,  18 ,  20 . The head disk assembly further includes a head stack assembly  24 . The head stack assembly  24  includes a rotatable actuator  26 . A pivot bearing cartridge  28  is provided for pivoting the actuator  26  of the head stack assembly  24  relative to the rotating disks  16 ,  18 ,  20 . The actuator  26  includes a plurality of actuator arms, each actuator arm supporting at least one head gimbal assembly (“HGA”). Each HGA includes a load beam, a gimbal, and a head or transducer which is configured to read/write data from the tracks. Suitably, the head is a magneto-resistive head (“MR head”). 
   The disk drive cover  14  includes a plurality of fastener openings  30   a–f ,  32 ,  34 . An enlarged plan view of the disk drive cover  14  is shown in  FIG. 2 . Corresponding to each of the fastener openings  30   a–f ,  32 ,  34  are a plurality of fasteners  36   a–f ,  38 ,  40 . Suitably, the fasteners  36   a–f ,  38 ,  40  are conductive screws, such as stainless steel screws. The fasteners  36   a–f ,  38 ,  40  may be used to attach the disk drive cover  14  to the base assembly  21 . In this regard, the disk drive base  12  may include fastener engagement holes  42   a–f , the actuator  26  may have a fastener engagement hole  44 , and the spindle motor  22  may have a fastener engagement hole  46  for respectively receiving the fasteners  36   a–f ,  38 ,  40 . 
   Referring additionally now to  FIGS. 2 and 3 , there is depicted top and bottom plan views of the disk drive cover  14 . Further,  FIG. 7  is an enlarged cross-sectional view of a portion of the disk drive cover  14  as seen along axis  7 — 7  of  FIG. 2 . The disk drive cover  14  includes a main cover portion  48  having opposing sides  50 ,  52  and formed of an electrically conductive material. For example, the main cover portion  48  may be formed of cold rolled steel (also known as carbon steel) or aluminum. A conductive plastic material may also be suitable. The side  50  is associated with an outside face of the disk drive cover  14 , and the side  52  is associated with an inside face of the disk drive cover  14 . 
   It is contemplated that the cold rolled steel is a relatively inexpensive material in comparison to other material selections such a stainless steel or aluminum, although such other material selections may be utilized. It is further contemplated that the disk drive cover  14  may be machined stamped. The disk drive cover  14  may be formed of multiple layers  54  and further may include an insulative layer  56  between adjacent ones of the multiple layers  54 . Where the disk drive cover  14  is formed of the layers  54 , each of the layers  54  may be individually stamped and subsequently bonded to form a laminate structure. 
   Use of the cold rolled steel is contemplated to be relatively susceptible to corrosion. In this regard, an electrically insulative coating  58  may be disposed upon the main cover portion  48 . The electrically insulative coating  58  may have corrosion resistant qualities to protect the surface of the main cover portion  48  from oxidation. In a preferred embodiment, the electrically insulative coating  58  is an epoxy coating (“E-coating”). Fabrication of the disk drive cover  14  with the electrically insulative coating  58  may be effected by various means. This may be effected via electro-deposition, a dipping process or a spray process for example. 
   The disk drive cover  14  includes a grounding opening  60  formed through the electrically insulative coating  58 . The main cover portion  48  includes an exposed surface  62  at the grounding opening  60 . In this regard, the grounding opening  60  is that region where the electrically insulative coating  58  is not located upon the main cover portion  48  thereby exposing the exposed surface  62 . 
   An aspect of the invention can be regarded as a method of assembling the disk drive  10 . Referring additionally now to  FIGS. 4–6 , the method includes mounting the base assembly  21  upon a base support portion  70  of a fixture  72 . The method further provides for mounting the disk drive cover  14  upon a cover support portion  74  of the fixture  72 . Referring additionally now to  FIG. 6 , the method further includes positioning the disk drive cover  14  with a grounding element  76  of the fixture  72  in electrical contact with the exposed surface  62  for electrically grounding the disk drive cover  14 . The method further includes attaching the disk drive cover  14  to the base assembly  21 . 
   In further detail, there is depicted in  FIG. 5  the cross-sectional side view of the fixture  72  as seen along axis  5 — 5  of  FIG. 4 . The disk drive cover  14  may be mounted upon the cover support portion  74  via suction elements  78 . It is contemplated that the cover support portion  74  is grounded. The disk drive cover  14  is selectively positioned with respect to the grounding element  76  so as to establish an electrical path from the disk drive cover  14  through the grounding element  76  to the grounded cover support portion  74 . As the disk drive cover  14  has been grounded the assembly of the disk drive  10  proceeds with the positioning of the disk drive cover  14  with respect to the base assembly  21  as shown in  FIG. 6 . It is contemplated that the cover support portion  74  is configured to facilitate such positioning. It is understood that the base support portion  70 , the cover support portion  74 , and the grounding element  76  may be integrally formed or attached to each other or exist as separate and distinct elements so as to collectively define the fixture  72 . 
   In the embodiment shown in  FIGS. 7 and 8 , the exposed surface  62  is disposed upon the side  50  of the main support portion  48 . A conductive adhesive  64  is depicted as encapsulating the exposed surface  62  at the grounding opening  60 . The conductive adhesive  64  is shown as utilized in attaching an intermediate contact element, such as the washer  68 . As shown in  FIG. 8 , an electrical path to ground may be established through the exposed surface  62  to the conductive adhesive  64  to the washer  68  to the grounding element  76 . The main support portion  48  may include a grounding opening  80  formed through the main support portion  48 . The grounding opening  78  may be configured to internally receive the grounding element  76  as shown. 
   As shown in  FIG. 6 , upon positioning and placement of the disk drive cover  14  adjacent the base assembly  21 , a fastener such as fastener  36   f  may be utilized to engage the disk drive cover  14  to the base assembly  21  and in particular the disk drive base  12 . The cover support portion  74  may include an opening  82  formed to allow the fastener  36   f  to be passed through it for allowing installation of the fastener  36   f  with the cover  14  supported by the cover support portion  74 . As such, the electrical path to ground may be maintained between the cover  14  and the cover support portion  74 . It is contemplated that the method may include the final step of electrically grounding the cover  14  with the base assembly  21 , and that this may be accomplished through the installation of the fastener  36   f.    
   The grounding element  76  may be formed as a rigid pin as shown in  FIGS. 5 ,  6 , and  8 . Referring now to  FIG. 9 , there is depicted another embodiment of the grounding element as shown as a spring loaded pin  84 . A compression spring  86  is housed in a recess  88  of the cover support portion  74 . It is contemplated that other spring loaded arrangements may be utilized such as a leaf spring configuration. 
   Referring now to  FIG. 10 , there is depicted another embodiment of the cover  14 . As shown, a grounding element  90  is disposed within the grounding opening  60  upon exposed surface  62 . The grounding element  90  may take the form of a metal coating such as an electroless Nickel coating. 
   Referring now to  FIG. 11 , there is depicted another embodiment of the cover  14 . As shown, a conductive adhesive  92  is disposed upon the exposed surface  62  at the grounding opening  60 . The conductive adhesive  92  is used to secure a grounding element in the form of conductive disk or plate  94  which may be formed of metal for example. 
   Referring now to  FIG. 12 , there is depicted another embodiment of the cover  14 . As shown, an opening  96  is formed through the main cover portion  48 . In this regard, the grounding opening  60  also extends through the main cover portion  48 . The exposed surface  62  is configured as an inner surface within the main cover portion  48 . An H-shaped conductive grommet  98  is disposed within the opening  96  in contact with the exposed surface  62 . The grommet  98  may be attached via a swage process for example. 
   Referring now to  FIG. 13 , there is depicted another embodiment of the cover  14 . As shown, an opening  100  is formed through the main cover portion  48 . In this regard, the grounding opening  60  also extends through the main cover portion  48 . The exposed surface  62  is upon the side of the main cover portion  48 . A T-shaped conductive grommet  102  is disposed within the opening  100  in contact with the exposed surface  62 . The grommet  102  may be attached via a swage process for example. 
   Referring now to  FIG. 14 , there is depicted another embodiment of the cover  14 . As shown, a grounding element  104  is disposed within the grounding opening  60  upon exposed surface  62 . The grounding element  104  may take the form of conductive adhesive. 
   Referring now to  FIG. 15 , there is depicted another embodiment of the cover  14  as shown with the grounding element  84  as shown in  FIG. 9 . The grounding element  84  is disposed in electrical contact with the exposed surface  62  by direct physical contact between the grounding element  84  and the exposed surface  62 .