Abstract:
A system and method for improving the process of attaching a hard disk microactuator to a slider device with a bonding agent such as epoxy, the slider having design characteristics to avoid various problems associated with bonding said components with a bonding agent such as epoxy.

Description:
BACKGROUND INFORMATION 
     The present invention relates to magnetic hard disk drives. More specifically, the present invention relates to a system for attachment of a hard disk micro-actuator to a slider device. 
     In the art today, different methods are utilized to improve recording density of hard disk drives. FIG. 1 provides an illustration of a typical drive arm configured to read from and write to a magnetic hard disk. Typically, voice-coil motors (VCM)  102  are used for controlling a hard drive&#39;s arm  104  motion across a magnetic hard disk  106 . Because of the inherent tolerance (dynamic play) that exists in the placement of a recording head  108  by a VCM  102  alone, microactuators  110  are now being utilized to ‘fine-tune’ head  108  placement, as is described in U.S. Pat. No. 6,198,606. A VCM  102  is utilized for course adjustment and the micro-actuator then corrects the placement on a much smaller scale to compensate for the VCM&#39;s  102  (with the arm  104 ) tolerance. This enables a smaller recordable track width, increasing the ‘tracks per inch’ (TPI) value of the hard drive (increased drive density). 
     FIG. 2 provides an illustration of a micro-actuator as used in the art. Typically, a slider  202  (containing a read/write magnetic head; not shown) is utilized for maintaining a prescribed flying height above the disk surface  106  (See FIG.  1 ). Micro-actuators may have flexible beams  204  connecting a support device  206  to a slider containment unit  208  enabling slider  202  motion independent of the drive arm  104  (See FIG.  1 ). An electromagnetic assembly or an electromagnetic/ferromagnetic assembly (not shown) may be utilized to provide minute adjustments in orientation/location of the slider/head  202  with respect to the arm  104  (See FIG.  1 ). 
     Attachment of a slider assembly to a micro-actuator can be difficult and/or expensive due to the dimensions within which it must occur. Bonding means must be very precise. It is therefore desirable to have a system for attachment of a hard disk micro-actuator to a slider device that improves the precision and consistency of slider bonding operations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 provides an illustration of a drive arm configured to read from and write to a magnetic hard disk as used in the art. 
     FIG. 2 provides an illustration of a micro-actuator as used in the art. 
     FIG. 3 describes a hard disk drive head gimbal assembly (HGA) with a ‘U’-shaped micro-actuator under principles of the present invention. 
     FIG. 4 provides an exploded, detailed illustration of a slider with a ‘U’-shaped microactuator under principles of the present invention. 
     FIG. 5 provides an illustration of two different problems involved with the process of bonding a slider to a ‘U’-shaped micro-actuator by a bonding agent such as epoxy. 
     FIG. 6 provides an illustration of two other problems involved with utilizing a bonding agent such as epoxy. 
     FIG. 7 illustrates design improvements to correct the slider asymmetry and rotation problems under principles of the present invention. 
     FIG. 8 illustrates design improvements to correct the rotation problem as well as the overflow problem under principles of the present invention. 
     FIG. 9 illustrates the fabrication of a first slider design under principles of the present invention. 
     FIG. 10 illustrates the fabrication of a second slider design under principles of the present invention. 
     FIG. 11 illustrates the fabrication of a third slider design under principles of the present invention. 
     FIG. 12 illustrates the fabrication of a fourth slider design under principles of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Illustrated in an upside-down orientation, FIG. 3 describes a hard disk drive head gimbal assembly (HGA) with a ‘U’-shaped micro-actuator under principles of the present invention. In one embodiment, a slider  302  is bonded at two points  304  to a ‘U’-shaped micro-actuator  306 . Further, in an embodiment, the ‘U’-shaped micro-actuator has a piezoelectric PZT (Lead Zirconate Titanate) beam (arm)  306  on each side of a Zirconia support frame (actuator base)  308 . 
     FIG. 4 provides an exploded, detailed illustration of a slider with a ‘U’-shaped microactuator under principles of the present invention. PZT material has an anisotropic structure whereby the charge separation between the positive and negative ions provides for electric dipole Nits behavior. When a potential is applied across a poled piezoelectric material, Weiss domains increase their alignment proportional to the voltage, resulting in structural deformation (i.e. regional expansion/contraction) of the PZT material. As the PZT structures  402  bend (in unison), the Zirconia arms  404 , which are bonded to the PZT structures  402 , bend also, causing the slider  406  to adjust its position in relation to the micro-actuator  408  (for magnetic head fine adjustments). 
     FIG. 5 provides an illustration of two different problems involved with the process of bonding a slider to a ‘U’-shaped micro-actuator by a bonding agent such as epoxy. A ‘U’shaped micro-actuator  502  is attached to a slider device  504  at two points  506  by epoxy. FIG. 5 a  illustrates a problem involving an overflow of epoxy during the bonding process. While the epoxy is curing, it is possible for an amount of epoxy to overflow  508  onto the slider surface. Because of the dimensional scale of the device, it is difficult to consistently apply a precise amount of epoxy (or other bonding agent). If a surplus of epoxy is provided, it may overflow  506  onto the surface of the slider  504 . This can affect the flying height of the slider  504 , which could cause magnetic interaction outside of the desired track (too high) or cause disk surface damage (too low). FIG. 5 b  provides a description of a problem with epoxy overflowing beyond the desired contact patch  506  to a location  510  in which it can bind and restrict slider  504  motion with respect to the micro-actuator  502  or it can cause slider  502  motion asymmetry (with respect to the micro-actuator). 
     FIG. 6 provides an illustration of two other problems involved with utilizing a bonding agent such as epoxy. As seen in FIG. 6 a , the slider  602  may shift with respect to the microactuator  604  while the epoxy is curing, causing spatial asymmetry of the slider  602  with respect to the micro-actuator  604 . This can cause problems during operation such as limiting the slider&#39;s  602  range of motion with respect to the micro-actuator  604 . Similarly, as seen in FIG. 6 b , the slider  602  may shift with respect to the micro-actuator  604  while the epoxy is curing, causing slider  602  rotation with respect to the micro-actuator  604 . The resulting slider  602  orientation may adversely affect slider  602  flying height as well as flight control. Further, it may cause the slider  602  to come into contact with the suspension during slider  602  operation. 
     FIG. 7 illustrates design improvements to correct the slider asymmetry/rotation problem illustrated in FIG. 6 under principles of the present invention. Design  1 , as depicted in FIG. 7 a , prevents the rotation and asymmetry problem. In one embodiment of the present invention, a recessed area  702  is formed in opposite sides of the slider  706 , which accepts a raised area  708  on each arm of the micro-actuator  704 , thus preventing rotational motion with respect to the micro-actuator in either the Z-X plane or Z-Y plane. Design  2 , as depicted in FIG. 7 b , prevents the rotation problem. In one embodiment, a step  710  is created in opposite sides of the slider  705 , which leaves a lip  712  on each side of the slider  705  that overlaps the arms of the microactuator  714 , thus preventing rotational motion with respect to the micro-actuator in the Z-Y plane. 
     FIG. 8 illustrates further design improvements to correct the rotation problem as well as the overflow problem associated with slider bondage by agents such as epoxy under principles of the present invention. Design  3 , as depicted in FIG. 8 a , prevents the rotation problem in the same manner as Design  2  (See FIG. 7 b ). Further, in one embodiment, an additional step  802  is created in the leading edge of the slider  804 , which provides slider  804  weight savings, reducing inertial forces and thus improving responsiveness as well as accuracy. 
     Design  4 , as depicted in FIG. 8 b , prevents the epoxy overflow problems illustrated in FIGS. 5 a  and  5   b . As stated previously, the dimensional scale of the slider  806  and microactuator  808  makes it difficult to consistently apply precise amounts of epoxy (or other bonding agent). If a surplus of epoxy is provided, it may overflow onto the surface of the slider during curing (See FIG.  5 ). In one embodiment of the present invention, a recessed area  810  of decreasing depth in the ‘Z’ direction is created on either side of the slider  806 , yielding a partial cleft between the slider  806  and the micro-actuator  808  when placed together. The partial cleft  810  prevents epoxy from being squeezed out onto the slider surface  806 . The raised area  812  of each micro-actuator  808  arm cannot enter the partial cleft because of its decreasing depth in the ‘Z’ direction. In addition, in an embodiment the increased room for epoxy makes a stronger bond possible. 
     FIG. 9 illustrates the fabrication of Design  1  under principles of the present invention. In one embodiment, a cutting wheel  902  is utilized to cut a row bar of slider material  904 . The bar  904  is cut  906  in a direction perpendicular to the length (axis) of the bar  904 . In an embodiment, this process is repeated  908  and the individual sub-bars are re-joined  910  by a bonding agent. In one embodiment, a shallow groove  913  is cut into one side of the re-joined bar  918 , and then into the other side  915  of the bar  918  lengthwise. Next, individual sliders  916  are yielded by separating the sub-bars (from the bar  918 ), each slider  916  having the appropriately recessed plane  917  on each side for joinder with a ‘U’-shaped mico-actuator (not shown). 
     FIG. 10 illustrates the fabrication of Design  2  under principles of the present invention. In one embodiment, a cutting wheel  1002  is utilized to cut  1008  a groove  1006  in a row bar of slider material  1004 . The bar  1004  is cut to a prescribed depth in a direction perpendicular to the length (axis) of the bar  1004 , yielding said groove  1006 . The process is repeated  1010  with a prescribed separation between grooves. In an embodiment, the bar is next cut completely through  1012  with a thinner cutting wheel  1018 , yielding steps  1020  on each separated unit. This process is repeated  1014 , yielding  1016  individual sliders  1022 , having steps  1024  on each side. 
     FIG. 11 illustrates the fabrication of Design  3  under principles of the present invention. In one embodiment, a cutting wheel  1130  is utilized to cut  1107  a step  1132  of a prescribed depth into a row bar  1104 . Next, similar to the manufacturing process of Design  2 , a cutting wheel  1102  is utilized to cut  1108  a groove  1106  in the bar  1104 . The process is repeated  1110  with a prescribed separation between grooves. In an embodiment, the bar is next cut completely through  1112  with a thinner cutting wheel  1118 , yielding steps  1120  on each separated unit. This process is repeated, yielding  1114  individual sliders  1122 , having steps on three sides. 
     FIG. 12 illustrates the fabrication of Design  4  under principles of the present invention. In one embodiment, a cutting wheel  1202  with a rounded edge is utilized to cut  1208  a decreasing-radius slit  1206  in a row bar  1204 . The bar  1204  is cut to a prescribed depth and for a prescribed distance in a direction perpendicular to the length (axis) of the bar  1204 , yielding this slit  1206 . The process is repeated  1210  with a prescribed separation between slits. In an embodiment, the bar is next cut completely through  1212  with a thinner cutting wheel  1018 , yielding recessed areas (planes)  1220  of decreasing depth on each separated unit. This process is repeated  1214 , yielding  1216  individual sliders  1222 , having recessed areas  1224  on each side. 
     Although several embodiments are specifically illustrated and described herein, it will be appreciated that modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.