Abstract:
An integrated lead disk drive suspension flexure including a gimbal region including gimbal spring arms having conductive spring metal traces embedded within dielectric between a pair of conductive metal shields. The traces function as the spring arms of the gimbal spring arms, wherein the gimbal spring arms are free from spring metal layers opposite the pair of conductive metal shields from the spring metal trace supports.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to flexures of the type used in disk drive head suspensions. In particular, the invention is an integrated lead flexure and method of manufacture. 
     BACKGROUND OF THE INVENTION 
     Wireless or integrated lead flexures of the type used in magnetic disk drive head suspension assemblies and associated manufacturing methods are known and disclosed, for example, in the following U.S. Patents. 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Inventor 
                 U.S. Pat. No./Publication No. 
               
               
                   
                   
               
             
             
               
                   
                 Hamilton et al. 
                 5,490,027 
               
               
                   
                 Balakrishnan 
                 5,995,328 
               
               
                   
                 Omote et al. 
                 6,100,582 
               
               
                   
                 Bennin et al. 
                 6,587,310 
               
               
                   
                 Kangawa et al. 
                 2005/0122627 
               
               
                   
                   
               
             
          
         
       
     
     There remains, however, a continuing need for improved flexures and methods of manufacture. In particular, there is a need for flexures having both high performance mechanical characteristics and high performance electrical signal transmission characteristics. To be commercially viable the flexures must be capable of being efficiently manufactured to a high degree of precision. 
     SUMMARY OF THE INVENTION 
     The present invention is an improved integrated lead flexure having high performance mechanical and electrical specifications. The flexure can also be efficiently manufactured. One embodiment of the flexure includes a plurality of head bond pads and a plurality of spring metal trace supports extending from the head bond pads along gimbal spring arms. A layer of high conductivity metal plating is on the spring metal trace supports. Dielectric surrounds at least portions of the plated spring metal trace supports along the gimbal spring arms. A first conductive metal shield is located on a first side of at least portions of the plated spring metal trace supports at the gimbal spring arms and at a slider mounting region. The first conductive shield is spaced from the plated spring metal trace supports by the dielectric. A second conductive metal shield is located on a second side of at least portions of the plated spring metal trace supports at the gimbal spring arms. The second conductive shield is spaced from the plated spring metal trace supports by the dielectric. 
     Another embodiment of the invention includes a spring metal trace support extending along the slider mounting region. A layer of high conductivity metal plating is on the spring metal trace support extending along the slider mounting region. A layer of dielectric is between the spring metal trace support extending along the slider mounting region and the first conductive metal shield at the slider mounting region. 
     Yet another embodiment of the invention includes a plurality of spring metal trace supports extending from the spring metal trace supports at the gimbal spring arms along a base region. A layer of high conductivity metal plating is on the spring metal trace supports along the base region. A dielectric layer surrounds at least portions of the plated spring metal trace supports along the base region. A first conductive metal shield is on a first side of at least portions of the plated spring metal trace supports along the base region. The first conductive shield along the base region is spaced from the plated spring metal trace supports by the dielectric. A second conductive metal shield is on a second side of at least portions of the plated spring metal trace supports along the base region. The second conductive shield along the base region is spaced from the plated spring metal trace supports by the dielectric. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a head suspension assembly including a flexure in accordance with one embodiment of the present invention. 
         FIG. 2  is a detailed plan view of a distal end or gimbal portion of the flexure shown in  FIG. 1 . 
         FIG. 3  is a detailed view of the gimbal portion shown in  FIG. 2  with the upper shield and covercoat layers removed. 
         FIG. 4  is a cross sectional illustration of a portion of the flexure shown in  FIG. 2 , taken at line  4 - 4  in  FIG. 2 . 
         FIG. 5  is a cross sectional illustration of a portion of the flexure shown in  FIG. 2 , taken at line  5 - 5  in  FIG. 2 . 
         FIG. 6  is a cross sectional illustration of a portion of the flexure shown in  FIG. 2 , taken at line  6 - 6  in  FIG. 2 . 
         FIG. 7  is a cross sectional illustration of a portion of the flexure shown in  FIG. 2 , taken at line  7 - 7  in  FIG. 2 . 
         FIG. 8  is a cross sectional illustration of a portion of the flexure shown in  FIG. 2 , taken at line  8 - 8  in  FIG. 2 . 
         FIGS. 9A-9E  illustrate a sequence of steps of a manufacturing process in accordance with one embodiment of the invention for manufacturing a flexure similar to that shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A suspension assembly  8  including a shielded copper-dielectric flexure  10  in accordance with one embodiment of the present invention is illustrated in  FIG. 1 . Suspension  8  is a three-piece assembly in the illustrated embodiment, and includes a load beam  12  and base plate  14  in addition to the flexure  10 . Load beam  12 , which is typically formed from stainless steel, includes a beam region  16 , hinge or spring region  18  and mounting region  20 . Rails  22  are formed on the side edges of the beam region  16 . Base plate  14  is welded to the mounting region  20  at the proximal end of the load beam  12 . 
     Flexure  10  is an integrated lead or wireless flexure and includes a mounting or base region  24  that is welded or otherwise attached to the beam region  16  of load beam  12 , a gimbal region  26  at its distal end, and a tail  28  extending from the proximal end of the base region. The gimbal region  26  includes a pair of laterally-spaced spring arms  30  extending from the base region  24 , and a slider mounting region  32  that extends from and is supported by and between the spring arms. A plurality of head bond pads  34  are located adjacent to the slider mounting region  32 . A plurality of terminal pads  36  are located on the proximal end of the flexure tail  28 . Traces (not visible in  FIG. 1  and described below) extend along the flexure  10  between the head bond pads  34  and terminal pads  36 . 
     The general structure of flexure  10  can be described in greater detail with respect to  FIG. 7  which is a cross sectional illustration of the base region  24 . As shown, the base region  24  of flexure  10  includes a core  42  and a plurality of traces  44  on a dielectric base insulation layer  40 . Core  42  is generally centrally located in the base region  24 . The traces  44  are laterally spaced on the opposite sides of the core  42  in the illustrated embodiment. Core  42  includes a spring metal support  46  plated with conductive metal  48  in the illustrated embodiment, although other embodiments are described below. Similarly, traces  44  include a spring metal support  50  plated with conductive metal  52 . In one embodiment of the invention the spring metal supports  46  and  50  are both beryllium copper (BeCu) alloy. Conductive metal plating  48  and  52  can be gold or copper. Other metals and metal alloys can be used for core  42  and traces  44  in other embodiments (not shown). A dielectric covercoat  54  overlays the surfaces of the core  42  and traces  44  that are not covered by the base insulation layer  40 . Base insulation layer  40  and covercoat  54  thereby combine to provide an insulation layer that embeds or surrounds the sides of core  42  and traces  44 . First and second conductive metal shield layers  56  and  58  overlay the base insulation layer  40  and covercoat  54 , respectively, on the opposite sides of the core  42  and traces  44 . Metal shield layers  56  and  58  can be copper, copper alloy or other metals or materials having suitable conductivity. 
     Spring metal support  46  of core  42  and spring metal supports  50  of traces  44  provide substantial mechanical structural properties to the base region  24  of flexure  10 . As is described below, the spring metal supports  50  of traces  44  also similarly provide substantial mechanical structural properties to the arms  30  and slider mounting region  32  of gimbal  26 . However, some metals such as BeCu that have mechanical properties suitable for the mechanical function of the structure do not have electrical properties suitable for the electrical functions of the components. BeCu, for example, is a relatively poor conductor. The conductive metal plating  48  and  52  on the spring metal support  46  of core  42  and the spring metal support  50  of traces  44 , respectively, provides the desired electrical properties for the core  42  and traces  44 . In other embodiments (not shown) where both the mechanical and electrical properties of the core  42  and/or traces  44  can be achieved by a single material structure, the conductive metal plating is not required. In still other embodiments (not shown) in which the core  42  is not used for electrical signal transmission, the core can be a single material structure such as BeCu that achieves the desired mechanical properties (e.g., the BeCu need not have the conductive metal plating in these embodiments). In the embodiments of the invention shown, the spring metal supports  46  of core  42  and spring metal supports  50  of traces  44 , in combination with the base insulation layer  40 , covercoat  54  and metal shield layers  56  and  58 , provide the mechanical properties required by the flexure  10  and in particular the resilient mechanical support properties required of the gimbal region  26 . This embodiment of the invention is free of stainless steel or other spring metal layers commonly present as base layers in head suspension flexures. 
     The structures of the different portions of gimbal region  26  can be described with reference to  FIGS. 2-6 .  FIG. 2  is a detailed plan view of the gimbal region  26  from the side shown in  FIG. 1 .  FIG. 3  is a plan view of the gimbal region  26  from the side shown in  FIG. 1 , with the second conductive metal shield layer  58  and the covercoat layer  54  removed. As shown in  FIGS. 2 and 3 , the second conductive shield layer  58  and covercoat  54  are not present over the slider mounting region  32 , and an aperture  60  extends through portions of the base insulation layer  40  and first metal shield layer  56  (not visible in  FIGS. 2 and 3 ). In the embodiment shown, the aperture  60  is a generally U-shaped slot, and the slider mounting region  32  is a rectangular tongue extending from and between the arms  30 . In other embodiments (not shown) the aperture  60  and slider mounting region  32  have other shapes and configurations. A ring-shaped support  62  extends around a portion of the slider mounting region  32  and is connected to traces  44  on the arms  30  by links  64 . Support  62  and links  64  can have the same structural components as the core  42  and/or traces  44  described above (e.g., spring metal supports  63  and conductive metal plating  65  as shown in  FIG. 6 ). This configuration of the slider mounting region  32  and its connections to arms  30  by link  64  allow the slider mounting region to move or gimbal in pitch and roll direction with respect to the arms. A head slider (not shown) can be bonded or otherwise attached to the slider mounting region  32  (e.g., to the ring-shaped support  62 ) and the terminals on the head slider electrically connected to the bond pads  34 . Conventional or otherwise known head sliders and bonding and electrical connection processes and technology can be used for these purposes. 
     An aperture  69  extends through the first metal shield layer  56  and base insulation layer  40  of the slider mounting region  32  in the embodiment shown. Aperture  69  can be used as a recess for receiving a load point dimple (not shown) extending from load beam  8 . 
     As shown in  FIG. 3 , the bond pads  34  are connected to traces  44  that extend along the arms  30  to the flexure base region  24 . Although not shown, the traces  44  also extend along the flexure base region  24  to the tail  28 , and along the tail to the terminal pads  36  ( FIG. 1 ). Links  64  connect the ring-shaped support  62  to the core  42  through traces  44  in the illustrated embodiment. In other embodiments (not shown) the links  64  are not connected to core  42 . The ring-shaped support  62  is also connected to a distal core section  66  through a bond pad  34  and link  78 . Core section  66  and link  78  can have the same structural components as the core  42  and/or traces  44  described above. 
       FIG. 8  is a cross sectional illustration of a grounding feature or interconnect  70  that can be formed on flexure  10  to electrically interconnect metal shield layers  56  and/or  58  to core  42  or one or more of traces  44 . In the embodiment shown in  FIG. 2 , interconnect  70  is located on the distal tip of the gimbal region  26  and electrically interconnects core  42  to both metal shield layers  56  and  58 . An aperture  72  extends through both the spring metal support  46  and metal plating  48  of the core  42 , as well as through base insulation layer  40 , covercoat  54  and metal shield layers  56  and  58 . A conductive metal plating layer  74  extends over the interior surfaces of the aperture  72  between the metal shield layers  56  and  58 , and in contact with the core  42 . In other embodiments (not shown), interconnect  70  connects the core  42  to either but not both of metal shield layers  56  and  58 . In these embodiments the aperture  72  need not extend through the flexure  10 . In still other embodiments (not shown), interconnect  70  electrically connects the metal shield layers  56  and  58 , but not core  42  (e.g., an insulation layer can be located between the metal plating layer  74  and the core  42 ). Interconnect  70  can also be located at other positions on flexure  10 . Interconnects such as  70  can also be used to electrically connect traces  44  to one or more of metal shield layer  56  and  58 . 
     Other embodiments of flexure  10  (not shown) can include layers of material and structures in addition to those of flexure  10  and described above. For example, additional layers of conductive material (e.g., ground planes) can be incorporated into the flexure. Similarly, additional layers of metal (e.g., nickel and/or gold) can be plated or otherwise applied to the traces. Dimples, formed offsets and rails are examples of structures that can be incorporated onto the flexure. Furthermore, portions of the flexure need not include all the structures of flexure  10  described above. For example, the base region of the flexure need not include the core. The metal shield layers need not be present over portions of the flexure not having traces. Similarly, one or both of the metal shield layers can be not present over portions of the traces. 
       FIGS. 9A-9E  illustrate a sequence of steps of a manufacturing process in accordance with one embodiment of the invention for manufacturing a flexure  110 . Flexure  110  can be similar or substantially the same as flexure  10  described above, and similar reference numbers are used to identify similar structures and elements.  FIGS. 9A-9E  illustrate a portion of the gimbal region arms  130 , but as described below, all the other portions of flexure  110  can also be manufactured using the process. 
     As shown in  FIG. 9A , the manufacturing process uses a laminate  111  having a base dielectric or insulation layer  140 , a BeCu or other spring metal layer  150  and a copper or other relatively highly conductive metal layer  152  between the insulation layer and spring metal layer. Laminates such as  111  are commercially available. 
       FIG. 9B  illustrates the gimbal region arms  130  after the laminate  111  is processed to form portions of traces  144 . As shown, the portions of traces  144  are formed by removing portions of the spring metal layer  150  and conductive metal layer  152  to leave strips of the spring metal layer overlaying strips of the conductive metal layer at the locations of the traces. Conventional photolithography and chemical etching processes are used to form the portions of flexure  110  shown in  FIG. 9B  in one embodiment of the invention. 
       FIG. 9C  illustrates the gimbal region arms  130  after conductive metal layer  152 ′ is plated onto the exposed outer surfaces of the portions of spring metal layer  150  and conductive metal layer  152 . The conductive metal layer  152 ′, along with conductive metal layer  152 , effectively surrounds the sides of the spring metal layer  150  to form the traces  144 . The conductive metal layer  152 ′ can be the same metal or other material as conductive metal layer  152 . Alternatively, conductive metal layer  152 ′ can be a metal or material that is different than that of conductive metal layer  152 . Conventional electroplating processes are used to coat the conductive metal layer  152 ′ onto the portions of the traces  144  shown in  FIG. 9C  in one embodiment of the invention. 
       FIG. 9D  illustrates the gimbal region arms  130  after a dielectric covercoat  154  is applied over the traces  144  and base insulating layer  140 . As shown, the covercoat  154  along with the base insulating layer  140  effectively surrounds the sides of the traces  144 . Conventional coating, curing and photolithography processes are used to form the covercoat  154  onto the insulating layer  140  and traces  144  in one embodiment of the invention. 
       FIG. 9E  illustrates the gimbal region arms  130  after the metal shield layers  156  and  158  have been applied to the exposed outer surfaces of the base insulating layer  140  and covercoat  154 , respectively. Conventional sputtering processes are used to form the metal shield layers  156  and  158  in one embodiment of the invention. 
     Apertures such as  60 ,  69  and  72  can be formed on a layer-by-layer basis during the process steps described above in connection with  FIGS. 9A-E . Alternatively, the apertures can be formed by processes such as mechanical boring or chemical etching following the fabrication of some or all of the layers of material through which the aperture is to extend. 
     Process steps similar to those described above in connection with  FIGS. 9A-9E  can be used to form other portions (not shown in  FIGS. 9A-9E ) of the gimbal region such as the slider mounting region and the head bond pads  34 , as well as other portions of the flexure (also not shown in  FIGS. 9A-9E ) such as the tail and base region. For example, the covercoat and upper shield layer can be not formed on the slider mounting region and head bond pads of the gimbal region (e.g., the regions masked off) during the fabrication of the flexure. Alternatively, the covercoat and/or upper shield layer can be initially formed on the gimbal region, and subsequently removed (e.g., by etching processes). Other portions of the flexure having the spring metal layer and/or the conductive metal layer (e.g., the core, ring on the slider mounting region and links), the first and/or second metal shield layers (e.g., flexure base region and slider mounting region) and/or the covercoat (e.g., the slider mounting region) can be formed at the same time and using the same processes and materials as those of the corresponding layers and structures in the gimbal region arms described above. Other known or otherwise conventional manufacturing processes (e.g., additive processes) can also be used to manufacture the flexure. 
     The flexure provides superior mechanical and electrical properties. It can also be efficiently manufactured. 
     Although the invention has been described with reference to preferred 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.