Patent Publication Number: US-2009231761-A1

Title: Head suspension assembly and storage device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The embodiments discussed herein are directed to a head suspension assembly incorporated in a storage device such as a hard disk drive (HDD). 
     2. Description of the Related Art 
     Head suspension assemblies are widely known as disclosed in Patent Document (Japanese Patent Laid-Open No. 2001-143422, Japanese Patent Laid-Open No. 06-203508, Japanese Patent Laid-Open No. 2004-213820), for example. In such a head suspension assembly, a flexure is attached to a head suspension. A head slider is mounted on a gimbal of the flexure. The contour of the head slider is defined to be larger than the contour of the gimbal. The gimbal is received on a protrusion of the head suspension so as to freely change its attitude. 
     If the head slider is positioned with high accuracy with respect to the protrusion, the attitude change of the head slider is stably established. The contour of the head slider is defined to be larger than the contour of the gimbal as described above. As a result, the position of the head slider with respect to the gimbal can be easily identified from behind the gimbal, for example. However, since the gimbal has a small surface area, the head slider cannot be bonded to the gimbal with sufficient strength. 
     A head suspension assembly and a storage device according to a present embodiment have been made in view of the aforementioned circumstances, and an object thereof is to provide a head suspension assembly and a storage device capable of positioning a head slider with high accuracy by ensuring high bonding strength with respect to a flexure such as a gimbal. 
     SUMMARY 
     In accordance with an aspect of embodiments, a head suspension assembly includes a head suspension, a protrusion defined on the head suspension, and a flexure attached to the head suspension. A support plate defined on the flexure is received on the protrusion so as to freely change its attitude and a head slider is bonded to the support plate. The support plate has a contour extending around a contour of the head slider. At least two openings are formed in the support plate, and the head slider is located within a contour defined by the openings. A window is formed in the head suspension behind the flexure. The openings are located within a contour of the window, so the openings can be seen when the head slider is adhered to the support plate. In this manner, the head slider is accurately located in the head suspension assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view schematically illustrating the inner structure of a hard disk drive (HDD) as an example of a storage device according to the present invention. 
         FIG. 2  is a plan view schematically illustrating the structure of a head suspension assembly according to a first embodiment of the present invention. 
         FIG. 3  is an enlarged partial plan view schematically illustrating the structure of the head suspension assembly according to the first embodiment of the present invention. 
         FIG. 4  is a partial sectional view schematically illustrating the structure of the head suspension assembly according to the first embodiment of the present invention. 
         FIG. 5  is an enlarged partial rear view schematically illustrating the structure of the head suspension assembly according to the first embodiment of the present invention. 
         FIG. 6  is an enlarged partial rear view schematically illustrating the structure of a head suspension assembly according to a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In the following, an embodiment of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  schematically illustrates the inner structure of a hard disk drive (HDD)  11  as an example of a storage device according to the present invention. The HDD  11  includes an enclosure, namely, a housing  12 . The housing  12  includes a box-shaped base  13  and a cover (not shown). The base  13  defines an inner space, namely, an accommodating space, in the form of a flat parallelepiped, for example. The base  13  may be made of a metallic material such as aluminum, for example. Molding process may be employed to form the base  13 . The cover is coupled to the opening of the base  13 . The accommodating space is sealed between the cover and the base  13 . Pressing process may be employed to form the cover out of a single plate material, for example. 
     One or more magnetic disks  14  as a storage medium are accommodated in the accommodating space. The magnetic disks  14  are mounted on the rotating shaft of a spindle motor  15 . The spindle motor  15  can rotate the magnetic disks  14  at a high speed such as 5400 rpm, 7200 rpm, 10000 rpm, 15000 rpm or the like. 
     A carriage  16  is also accommodated in the accommodating space. The carriage  16  includes a carriage block  17 . The carriage block  17  is rotatably coupled to a support shaft  18  extending in the vertical direction. A plurality of carriage arms  19  extending in the horizontal direction from the support shaft  18  are defined in the carriage block  17 . The carriage block  17  may be made of aluminum, for example. Extrusion molding process may be employed to form the carriage block  17 , for example. 
     A head suspension assembly  21  is attached to the tip end of the individual carriage arm  19 . A caulking technique may be used for the attachment, for example. A hole defined in the tip end of the carriage arm  19  may be aligned with a hole defined in the rear end of the head suspension assembly  21  for the caulking. 
     The head suspension assembly  21  includes a head suspension  22 . The head suspension  22  extends forward from the tip end of the carriage arm  19 . A flying head slider  23  is supported on the front end of the head suspension  22 . A head element, namely, an electromagnetic transducer is mounted on the flying head slider  23 . 
     An airflow is generated on the surface of the magnetic disk  14  based on the rotation of the magnetic disk  14 . The airflow serves to cause a positive pressure, namely, a lift, and a negative pressure to be exerted on the flying head slider  23 . The combination of the lift and the negative pressure is balanced with the urging force of the head suspension  22 . The flying head slider  23  is thereby allowed to keep flying during the rotation of the magnetic disk  14  with relatively high stability. 
     When the carriage  16  swings around the support shaft  18  during the flight of the flying head slider  23 , the flying head slider  23  is allowed to move along the radial line of the magnetic disk  14 . Accordingly, the electromagnetic transducer on the flying head slider  23  is allowed to cross the data zone between the innermost recording track and the outermost recording track. The electromagnetic transducer on the flying head slider  23  can be thereby positioned above a target recording track. 
     A power source such as a voice coil motor (VCM)  24  is connected to the carriage block  17 . The VCM  24  serves to rotate the carriage block  17  around the support shaft  18 . The carriage arm  19  and the head suspension  22  are allowed to swing based on the rotation of the carriage block  17 . 
     As seen in  FIG. 1 , a flexible printed circuit board unit  25  is located on the carriage block  17 . The flexible printed circuit board unit  25  includes a head IC (integrated circuit)  27  mounted on a flexible printed circuit board  26 . The head IC  27  supplies a sensing current to a read element of the electromagnetic transducer at the time of reading magnetic information. Similarly, the head IC  27  supplies a writing current to a write element of the electromagnetic transducer at the time of writing magnetic information. 
     A small-sized circuit board  28  located within the accommodating space and a printed circuit board (not shown) attached to the back of the bottom plate of the base  13  supply the sensing current and the writing current to the head IC  27 . A relay flexible printed circuit board  29  is used for the supply of the sensing current and the writing current, for example. The flexible printed circuit board  29  has a wiring pattern thereon. The flexible printed circuit board  29  is connected to the flexible printed circuit board unit  25 . 
       FIG. 2  schematically illustrates the structure of the head suspension assembly  21  according to the first embodiment of the present invention. The head suspension assembly  21  includes a base plate  31  attached to the tip end of the carriage arm  19  and a load beam  32  distanced forward from the base plate  31  at a predetermined interval. Caulking process is employed to fix the base plate  31  to the carriage arm  19 , for example. 
     A hinge plate  33  is bonded to the surfaces of the base plate  31  and the load beam  32 . The hinge plate  33  may be bonded by performing spot welding at a plurality of bonding spots, for example. A YAG laser is used in the spot welding, for example. The hinge plate  33  includes an elastic bending section  34  between the front end of the base plate  31  and the rear end of the load beam  32 . The hinge plate  33  thereby couples the base plate  31  and the load beam  32 . The base plate  31 , the load beam  32  and the hinge plate  33  constitute the head suspension  22 . 
     A flexure  35  is attached to the surface of the head suspension  22 . The flexure  35  includes a stainless steel plate  36  bonded to the surface of the head suspension  22 . The stainless steel plate  36  has a thickness of about 20 μm, for example. The stainless steel plate  36  may be bonded by performing spot welding at a plurality of bonding spots, for example. A YAG laser is used in the spot welding, for example. The stainless steel plate  36  extends backward from the tip end of the head suspension  22 . The stainless steel plate  36  extends outward from the contour of the base plate  31 . A wiring pattern  37  is formed on the surface of the stainless steel plate  36 . The wiring pattern  37  electrically connects the flying head slider  23  and the flexible printed circuit board  29 . The flying head slider  23  is connected to the flexible printed circuit board unit  25  in this manner. 
     As shown in  FIG. 3 , the stainless steel plate  36  includes a support plate  38  for receiving the flying head slider  23  at the surface and a fixation plate  39  fixed to surfaces of the load beam  32  and the hinge plate  33  ( FIG. 2 ). A so-called gimbal spring  41  is defined between the support plate  38  and the fixation plate  39 . The gimbal spring  41  extends in parallel along the side edges of the support plate  38  both sides of the support plate  38 . The gimbal spring  41  allows the support plate  38 , namely, the flying head slider  23  to change its attitude relative to the fixation plate  39 . 
     The support plate  38  extends around and outside the contour of the flying head slider  23 . An adhesive  42  may be employed to bond the flying head slider  23  to the surface of the support plate  38 . The adhesive  42  is spread on the support plate  38  outward from the contour of the flying head slider  23 . The wiring pattern  37  includes an insulating layer, an electrically-conductive layer, and a protection layer laminated in sequence on the stainless steel plate  36 . The electrically-conductive layer is made of an electrically-conductive material such as copper. The insulating layer and the protection layer are made of a resin material such as polyimide resin. As is clear from  FIG. 3 , the wiring pattern  37  extends inside the gimbal spring  41 . The wiring pattern  37  extends partially outward from the stainless steel plate  36  in this manner. 
     Openings  43  are formed in the support plate  38  corresponding to the four corners of the contour of the flying head slider  23 . Etching process may be employed to form the openings  43 , for example. Electrical conductors  44  electrically connect the flying head slider  23  and the flexible printed circuit board  29 . Each electrical conductor  44  is formed of a ball bump, for example. The electrical conductors  44  are received on an electrically-conductive pad formed on the end surface on the air outflow side of the flying head slider  23 . The electrically-conductive pads are connected to the electromagnetic transducer. Similarly, each electrical conductor  44  is received on an electrically-conductive pad formed on the surface of the stainless steel plate  36 . The electrically-conductive pad is connected to the wiring pattern  37 . 
     As shown in  FIG. 4 , the support plate  38  is received on a domed protrusion  45  formed on the surface of the load beam  32  behind the flying head slider  23 . The height of the protrusion  45  from the surface of the load beam  32  is set to about 50 μm, for example. Pressing process may be employed to extrude the shape of the protrusion  45  from a metal plate, for example. The protrusion  45  allows a depression to be formed in the back surface of the load beam  32 . The depression allows the position of the protrusion  45  to be identified in the back surface of the load beam  32 . 
     The aforementioned elastic bending section  34  exerts a predetermined elastic force, namely, bending force. The bending force serves to impart an urging force toward the surface of the magnetic disk  14  to the front end of the load beam  32 . The urging force acts on the flying head slider  23  from behind the support plate  38  through the protrusion  45 . The flying head slider  23  is allowed to change its attitude based on the lift generated by the airflow. Hereby, the protrusion  45  does not interfere with the change in the attitude of the flying head slider  23 , namely, the support plate  38 . 
     As shown in  FIG. 5 , a pair of windows  46  and  46  in which the openings  43  are located within the contour thereof is formed in the load beam  32  behind the support plate  38 , for example. The aforementioned protrusion  45  is located on the load beam  32  between the windows  46  and  46 . The position of the protrusion  45  can be identified by the position of the aforementioned depression. The windows  46  and  46  allow the openings  43  to be observed from behind the flexure  35 . The corner of the contour of the flying head slider  23  is located within the contour of each of the openings  43 . An area in which the flying head slider  23  is allowed to move is decided according to the size of each of the openings  43 . Here, the size of each of the openings  43  may be set based on the assembling accuracy of the head suspension assembly  21 , for example. 
     The base plate  31  and the load beam  32  are coupled by the hinge plate  33  ( FIG. 2 ) in the production of the head suspension assembly  21 . The hinge plate  33  may be spot-welded on the surfaces of the base plate  31  and the load beam  32  so as to couple the base plate  31  and the load beam  32 . The flexure  35  is attached to the surfaces of the load beam  32  and the hinge plate  33  by spot welding. The heat-curable adhesive  42  is applied to the surface of the support plate  38  of the flexure  35 , for example. The adhesive  42  is applied to the inner side of the contour of the flying head slider  23 , for example. 
     The flying head slider  23  is located on the surface of the support plate  38 . The flying head slider  23  is supported by a support arm so as to locate the flying head slider  23  on the surface of the support plate  38 , for example. The adhesive  42  is pressed and spread between the flying head slider  23  and the support plate  38  at this time. The adhesive  42  is spread outward from the contour of the flying head slider  23  on the surface of the support plate  38 . The support arm moves the flying head slider  23  along the surface of the support plate  38 . The four corners of the contour of the flying head slider  23  are located within the respective openings  43 . 
     A camera is employed to take an image of the back surface of the flexure  35  from behind the flexure  35 , for example. An operator adjusts the corner positions of the contour of the flying head slider  23  within the openings  43  based on the camera image. The center position of the depression of the protrusion  45  is referenced for the adjustment. The relative positions of the center position of the depression of the protrusion  45  and the corner positions of the contour of the flying head slider  23  are thereby adjusted. The relative positions may be set in advance. As a result of such adjustment, the position of the flying head slider  23  with respect to the protrusion  45  is decided. The openings  43  are set based on the assembling accuracy of the head suspension assembly  21 . Therefore, the corners of the contour of the flying head slider  23  can be reliably located within the openings  43  even if the relative position of the flexure  35  with respect to the load beam  32  is deviated, for example. 
     After that, the adhesive  42  is heated to a predetermined temperature. The adhesive  42  is cured. The flying head slider  23  is thereby bonded to the surface of the support plate  38 . As described above, the support plate  38  defines the contour extending outward from the contour of the flying head slider  23 . The adhesive  42  is pressed and spread outward from the contour of the flying head slider  23  on the support plate  38 . As a result, the adhesive  42  is not only sandwiched between the flying head slider  23  and the support plate  38 , but can also be spread upward on the side faces of the flying head slider  23 , for example. Accordingly, the flying head slider  23  can be bonded to the support plate  38  with high strength. 
     In the head suspension assembly  21  as described above, the flexure  35 , namely, the support plate  38  defines the contour extending outward from the contour of the flying head slider  23 . The flying head slider  23  is thereby attached to the support plate  38  over the entire back surface of the plate. Additionally, the adhesive  42  is spread on the support plate  38  outward from the contour of the flying head slider  23 . The flying head slider  23  is bonded to the support plate  38  with high bonding strength. Moreover, the openings  43  are located within the windows  46  of the load beam  32  behind the support plate  38 . The corners of the contour of the flying head slider  23  are located within the contours of the openings  43 . Accordingly, the position of the flying head slider  23  with respect to the position of the protrusion  45  is correctly set with high accuracy. The flying head slider  23  is thus allowed to establish a stable flying attitude. 
       FIG. 6  schematically illustrates the structure of a head suspension assembly  21   a  according to a second embodiment of the present invention. A load beam  32   a , instead of the above load beam  32 , is incorporated in the head suspension assembly  21   a . The load beam  32   a  has a width smaller than the distance defined between the two openings  43  on the air outflow end side of the flying head slider  23 , and the distance defined between the two openings  43  on the air inflow end side of the flying head slider  23 . Here, the load beam  32   a  is tapered toward the tip end. The openings  43  are thus located outside the contour of the load beam  32   a . As a result, the openings  43  can be observed from the back surface of the support plate  38 . Other configurations and structures equivalent to those of the aforementioned head suspension assembly  21  are assigned the same reference numerals. 
     According to the head suspension assembly  21   a , as described above, the corner positions of the flying head slider  23  can be adjusted within the openings  43  based on the camera image from behind the flexure  35 . The position of the flying head slider  23  with respect to the protrusion  45  is correctly set with high accuracy in this manner. The flying head slider  23  is thus allowed to establish a stable flying attitude. Moreover, the adhesive  42  can be spread on the support plate  38  outward from the contour of the flying head slider  23 . The flying head slider  23  can be bonded to the support plate  38  with high bonding strength. 
     In the HDD  11  as described above, the openings  43  may be individually located with respect to at least any two corners of the contour of the flying head slider  23 . Any of the two corners on the air inflow end side of the flying head slider  23  and the two corners on the air outflow end side of the flying head slider  23  may be selected, for example. Similarly, any two corners specified by a diagonal line on the back surface of the flying head slider  23  laminated on the surface of the support plate  38  may be selected, for example. When at least any two corners are respectively located within the openings  43 , the position of the flying head slider  23  can be identified from the back surface of the support plate  38 . The openings  43  may also be individually located with respect to three corners of the contour of the flying head slider  23 . 
     As described above, according to the head suspension assembly and the storage device of the present embodiments, the head suspension assembly and the storage device capable of positioning the head slider with high accuracy by ensuring high bonding strength with respect to the flexure can be provided. 
     In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.