Abstract:
A slider assembly used in a direct access storage device includes electrically conductive bond pads formed on the slider body. A rigid and electrically non-conductive material surrounds and abuts the bond pads. The material and the bond pads form a planar surface. The material prevents the bond pads from migrating and shorting, so that the bond pads can be placed closer together.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates generally to the field of direct access storage devices. 
       BACKGROUND 
       [0002]    Direct access storage devices (DASDs) have become part of everyday life, and as such, the capability to manipulate and store larger amounts of data at greater speeds is expected. To meet these expectations, DASDs such as hard disk drives (HDDs) have undergone many changes. 
         [0003]    The basic hard disk drive model resembles a phonograph. That is, the hard disk drive model includes a storage disk, or hard disk, that spins at a standard rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The arm carries a head assembly that has a magnetic read/write transducer, or head, for writing or reading information to or from a location on the disk. The complete head assembly, e.g., the suspension and head, is called a head gimbal assembly (HGA). 
         [0004]    Bond pads are formed on a surface of the slider. A conductive path extends from the head to the bond pads, which in turn are connected to wires that carry information between the disk and the host computer system. 
         [0005]    Advances in magnetic read/write heads as well as in the disk have allowed more data to be stored and quickly accessed. The ability of an HDD to access this data is largely a function of the performance of the mechanical components of the HDD. Once this data is accessed, the ability of an HDD to read and write this data is primarily a function of the electrical components of the HDD. Other advances have led to significant reductions in the size of the hard disk drive. 
         [0006]    A problem that can occur during fabrication is referred to as “bond pad bridging.” After the bond pads are formed, subsequent cleaning and mechanical processes during fabrication may cause the pads to spread, bringing adjacent pads in contact with each other, thereby introducing a short. If the bond pads are placed closer to each—to increase the number of bond pads without increasing the size of the device, for example—the problem of bond pad bridging can become worse. 
         [0007]    If a short is introduced, the device has to be discarded, reducing yields. A solution to the problem of bond pad bridging would therefore provide value by increasing yields. 
       SUMMARY 
       [0008]    A slider assembly used in a direct access storage device includes electrically conductive bond pads formed on and protruding from the slider body. A rigid and electrically non-conductive material surrounds and abuts the bond pads. The material and the bond pads form a planar surface. The material prevents the bond pads from migrating and shorting, so that the bond pads can be placed closer together. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
           [0010]      FIG. 1  illustrates an exploded view of a hard disk drive including an enlarged representation of a slider assembly according to embodiments of the present invention. 
           [0011]      FIG. 2  is a flowchart of a process for forming a slider assembly according to embodiments of the present invention. 
           [0012]      FIG. 3  illustrates various stages in a process for forming a slider assembly according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Reference will now be made in detail to embodiments of the present invention. While the invention will be described in conjunction with the embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0014]    Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure aspects of the present invention. 
         [0015]      FIG. 1  illustrates an exploded view of an example of a hard disk drive (HDD)  110  including an enlarged representation of a slider assembly  155  upon which embodiments of the present invention can be implemented. HDD  110  represents one example of the many types of direct access storage devices (DASDs) and HDDs in which embodiments in accordance with the present invention can be implemented. 
         [0016]    In the example of  FIG. 1 , the components of HDD  110  are assembled into base casting  113 , which provides attachment and registration points for components and sub-assemblies. A disk&#39;s surface is spun at high speed by means of a motor hub assembly  130 . Data is recorded onto the surface of a disk  135  in a pattern of concentric rings known as data tracks. Data tracks are recorded onto the surface of a disk  135  by means of a magnetic head  156 , which can be included in the body of the slider assembly  155  and which can also be used to read data from the data tracks. When the disk is spun by the motor hub assembly  130 , the slider assembly  155  is supported on a thin cushion of air between the disk and an air bearing surface (not shown). An actuator  140  can be used to position the magnetic head  156  over the disk  135 . In general, the motor-hub assembly  130  supports the disk stack  138  so that the surface of a disk  135  can be spun adjacent to the slider assembly  155 , thus allowing the magnetic head  156  to read and write data tracks on the surface of the disk  135 . HDD  110  can include other components in addition to those shown or discussed. 
         [0017]    Slider assembly  155 , shown in enlarged view, is in general composed of a substrate upon which various materials and devices are added; not all of these materials and devices are shown or discussed. Those material and devices generally constitute a slider body  157 . The slider body  157  has surfaces that can be referred to as the serial side (on which a serial number may appear), the sidewalls, and the flex side. The slider body  157  also has a surface that can be referred to as the deposit side  170 , on which a number of bond pads  160  are formed. In the example of  FIG. 1 , four (4) bond pads  160  are shown; however, the present invention is not so limited. Some HDDs may incorporate up to nine (9) bond pads, but again the present invention is not so limited. In general, the bond pads  160  are made of a conductive metal. In one embodiment, the bond pads  160  are made of gold. 
         [0018]    The magnetic head  156  is formed within or on slider body  157 . Although not shown in  FIG. 1 , a conductive path exists between the head  156  and the bond pads  160 . The bond pads  160  in turn can be connected (bonded) to data transmission lines (e.g., leads or wires), thereby providing a path between the surface of a disk  135  and a host computer system (not shown) in which the HDD  110  resides, so that information can be passed back and forth between the disk and the host computer system. 
         [0019]    According to embodiments of the present invention, the bond pads  160  are surrounded by and abut an insulator  165 . Furthermore, the exposed surfaces of the bond pads  160  and the insulator  165  are flush with each other, so that they form a planar surface on deposit side  170  (refer also to  FIG. 3 , discussed below). 
         [0020]    In one embodiment, insulator  165  of  FIG. 1  is made of the same material as the substrate of slider body  157 . In one embodiment, insulator  165  is made of aluminum, titanium and carbide, sometimes referred to as AlTiC. In another embodiment, insulator  165  is made of alumina (Al 2 O 3 ). In yet another embodiment, insulator  165  is a ceramic material. 
         [0021]    In addition to being non-conductive, insulator  165  is a rigid material that is harder than the material from which the bond pads  160  are made. By virtue of its hardness and rigidity, insulator  165  prevents the bond pads  160  from spreading or migrating. In effect, insulator  165  separately encloses each of the bond pads  160 , so that spreading of the bond pads is inhibited during subsequent cleaning and mechanical processes during fabrication. If the bond pads do not spread, then they cannot come in contact with each other. Consequently, instances of bond pad bridging can be reduced or prevented, thereby diminishing or eliminating a potential source of shorts and increasing yields. Indeed, available data shows that, with the introduction of the present invention, instances of bond pad bridging are reduced from about 1.65 percent to about 0.14 percent. 
         [0022]    Also, because bond pad bridging can be reduced if not prevented, the bond pads  160  can be placed closer to each other, allowing the slider assembly  155  to be reduced in size, or allowing the use of more bond pads without having to increase the size of the slider assembly. In one embodiment, the distance between bond pads is less than 4-5 microns, and distances less than that are achievable. More bond pads are advantageous, permitting additional electrical connections that can be used for reading and writing information or for connecting with other features associated with the head  156 , such as fly height sensors. 
         [0023]      FIG. 2  is a flowchart  200  of a process for forming a slider assembly (e.g., slider assembly  155  of  FIG. 1 ) according to embodiments of the present invention.  FIG. 3  illustrates certain stages in the process of  FIG. 2 . 
         [0024]    Although specific steps are disclosed in flowchart  200 , such steps are exemplary. That is, the present invention is well-suited to various other steps or variations of the steps recited in flowchart  200 . 
         [0025]    Also, other processes and steps associated with the fabrication of a slider assembly, HDD or DASD may be performed along with the process illustrated by  FIGS. 2 and 3 ; that is, there may be a number of process steps before and after the steps shown and described by  FIGS. 2 and 3 . Importantly, embodiments of the present invention can be implemented in conjunction with these other (conventional) processes and steps without significantly perturbing them. Generally speaking, process steps associated with the various embodiments of the present invention can be added to a conventional process without significantly affecting the peripheral processes and steps. 
         [0026]    With reference to  FIGS. 2 and 3 , in block  202 , conductive bond pads  160  are formed on a substrate  302 . In one embodiment, the bond pads  160  are made of gold. The bond pads protrude from the surface to a specified height. In one embodiment, the height of the bond pads is about 4-6 microns. In various embodiments, the substrate  302  is made of AlTiC or alumina. 
         [0027]    In block  204 , a non-conductive material (insulator  165 ) is deposited or grown between and over the bond pads  160  so that the bond pads are covered by the insulator. In one embodiment, the insulator  165  is deposited to a depth of about six (6) microns. In one embodiment, the insulator  165  is made of the same material as the substrate  302 . 
         [0028]    In block  206 , a process such as, but not limited to, chemical-mechanical polishing (CMP) is employed to remove the insulator  165  until the bond pads  160  just barely begin to show, exposing enough of the bond pads  160  to permit wire bonding. As a result, the specified height of the bond pads is maintained, and the bond pads  160  and the insulator  165  form a planar surface. That is, the surface of deposit side  170  ( FIG. 1 ) is planar. In a sense, at this point in the fabrication process, the bond pads  160  act as a reference surface—the specified height of the bond pads serves as a reference point that identifies how much of the insulator  165  to remove and when to stop removing the insulator material. 
         [0029]    Continuing with reference to  FIGS. 2 and 3 , the bond pads are bonded to a wire or lead. The wire bonding process may cause a portion  306  of a bond pad to grow outward, so that the surface of the bond pad is no longer flush with the surface of the insulator  165 . 
         [0030]    In block  208 , a process such as CMP can be used to remove the portion  306 , so that the surfaces of the bond pad and the insulator are again flush. Because the insulator  165  is made of a material that is harder than the material used to make the bond pads, the surface of the insulator serves as a reference surface at this point in the fabrication process—the depth of the insulator  165  serves as a reference point that identifies how much of the bond pads to remove and when to stop removing the bond pad material, so that the stripe height can be properly controlled. 
         [0031]    In summary, embodiments in accordance with the present invention pertain to HDD and DASD sliders, and methods for fabricating such devices, in which the potential for bond pad bridging is reduced or eliminated, thereby increasing yields. 
         [0032]    The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments described herein were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.