Abstract:
A system and method are disclosed for edge blending hard drive head sliders by oscillating abrasive lapping tape across the edges of multiple sliders simultaneously.

Description:
BACKGROUND INFORMATION  
         [0001]    The present invention relates to hard disk drives. More specifically, the invention relates to a system and method for edge blending hard drive head sliders.  
           [0002]    [0002]FIG. 1 provides an illustration of a typical hard disk drive. Hard disk drive storage devices typically include a rotating disk  1  mounted for rotation by a spindle motor (not shown). A slider  3 , supported by a suspension arm  5 , ‘flies’ over the surface of the magnetic disk  1  at a high velocity, reading data from and writing data to concentric data tracks  11  on the disk  1 . The slider  1  is positioned radially by a voice coil motor  7 .  
           [0003]    [0003]FIG. 2 shows a more detailed view of a head slider  3  flying over the surface of a magnetic disk  1  as is typical in the art. Modem head sliders  3  float over the surface of the disk  1  on a cushion of air. If the ‘flying height’ is too great, the head  12  on the head slider cannot properly read from and write to the disk  1 . If it is too small, there is an increased chance of a head crash.  
           [0004]    If a head slider  3  contacts the surface of the disk while it is at operational speed, the result can be a loss of data, damage to the head slider, damage to the surface of the disk  1 , or all three. One of the most common causes of head crashes is a contaminant getting wedged in the microscopic gap between head  3  and disk  1 . Head sliders  3  are typically ceramic for durability and corrosion resistance. A ceramic slider is durable due to its hardness. The tradeoff, however, of ceramic&#39;s hardness is its brittleness. When a row bar is cut into individual sliders  3  (explained below), the ceramic crystal array causes the slider  3  edges to crack easily. Loose chips of ceramic material may be found on the cutting surface edge corners even after solvent cleaning. Also, after cutting a row bar into individual sliders, a high point is often left on the cut slider surface. This is known as ‘edge jump’. Edge jump is believed to be from the stress applied to the cut edge of the slider  3 . A deformation layer is created by the pressure  20  created by the cutting process. (See FIG. 3).  
           [0005]    [0005]FIG. 3 illustrates the problems related to particle contamination and edge jump as is typical in the art. The problems concerning loose chips  21  and edge jump  20  can cause hard drive head crashes. A loose chip  21  may fall from the slider and contaminate the interface between the slider  3  and disk  1 . An edge jump  20  can affect a slider&#39;s anti-shock performance negatively. If the HDD gets a physical impact while operating, a location of edge jump may contact and damage the disk  1 .  
           [0006]    It is therefore desirable to have a system and method for edge blending hard drive head sliders that avoids the above-mentioned problems, as well as having additional benefits.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 provides an illustration of a typical hard disk drive.  
         [0008]    [0008]FIG. 2 shows a more detailed view of a head slider flying over the surface of a magnetic disk as is typical in the art.  
         [0009]    [0009]FIG. 3 illustrates the problems related to particle contamination and edge jump as is typical in the art.  
         [0010]    [0010]FIG. 4 illustrates a head parting jig as is typical in the art.  
         [0011]    [0011]FIG. 5 illustrates an edge blending jig according to an embodiment of the present invention.  
         [0012]    [0012]FIG. 6 illustrates the attachment of a head blending jig to a head blending machine according to an embodiment of the present invention.  
         [0013]    [0013]FIG. 7 illustrates portions of lapping tape inserted between individual head sliders mounted to an edge blending jig in a standby configuration and in two edge blending configurations according to an embodiment of the present invention.  
         [0014]    [0014]FIG. 8 provides a more detailed illustration of lapping tape partially wrapping a slider&#39;s edge to perform edge blending according to an embodiment of the present invention.  
         [0015]    [0015]FIG. 9 provides a detailed view of an individual slider mounted to an arm of an edge blending jig with lapping tape partially wrapping a slider edge for edge blending according to an embodiment of the present invention.  
         [0016]    [0016]FIG. 10 illustrates an edge blending machine according to an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0017]    [0017]FIG. 4 illustrates head parting jig as is typical in the art. As is illustrated in FIG. 4 a , a slider row bar  401  is typically bonded to multiple arms  402  of a head parting jig  403 . As is illustrated in FIG. 4 b  and described further below, the row bar is cut into individual head sliders  3  by a slider parting tool (not shown).  
         [0018]    [0018]FIG. 5 illustrates an edge blending jig according to an embodiment of the present invention. As illustrated in FIG. 5 a , in one embodiment, a slider row bar  501  is bonded to multiple arms  502  of the edge blending jig, whereupon the row bar is separated into individual head sliders  3  by a slider parting tool (not shown). One advantage of this jig design is that imperfections on the edges of the sliders  3  (such as edge jump) can be detected by viewing the sliders from behind  505  and observing the uniformity of gaps between the sliders  3 .  
         [0019]    [0019]FIG. 6 illustrates the attachment of a head blending jig to a head blending machine according to an embodiment of the present invention. In one embodiment, the edge blending jig is coupled to a support assembly  12  of the head blending machine by a pair of pins  11 .  
         [0020]    [0020]FIG. 7 illustrates portions of lapping tape inserted between individual head sliders mounted to an edge blending jig in a ‘standby ’ configuration and in two edge blending configurations according to an embodiment of the present invention. As illustrated in FIG. 7 a , in one embodiment, lapping tape  701  covered with an abrasive, such as diamond powder (e.g., of a grade between 0.1 microns and 3.0 microns), is inserted between sliders  3 . FIG. 7 a  shows the edge blending assembly in a ‘standby ’ configuration with the sliders  3  out of contact with the lapping tape  701 . FIG. 7 b  shows the edge blending assembly configured to partially wrap the lapping tape  701  across one of the edges of each slider  3  on the edge blending jig  2  according to an embodiment of the present invention. In this embodiment, the lapping tape is positioned by an adjustable series of rollers (described below) to be stretched across the slider edges at a predetermined tension force (e.g., less than 0.8 kilograms). In this embodiment, the edge blending jig  2  is directionally oscillated  712  by the edge blending assembly to cause relative motion between the sliders  3  and the lapping tape  701  (e.g., at a frequency of at least 1 cycle per second and at an amplitude between 10 millimeters and 40 millimeters). FIG. 7 c  shows the edge blending assembly configured to partially wrap the lapping tape  701  across the opposite edge of each slider  3  according to an embodiment of the present invention. In this embodiment, the edge blending assembly is configured to stretch the lapping tape  701  across the opposite edge of each slider to complete the edge blending process. As explained below, in one embodiment, the process of edge blending is performed submerged in lubricant.  
         [0021]    [0021]FIG. 8 provides a more detailed illustration of lapping tape partially wrapping a slider&#39;s edge to perform edge blending according to an embodiment of the present invention. In one embodiment, a first angle (α) is formed between a face  805  of the slider  3  and the lapping tape  801 , and a second angle (β) is formed between the opposite face  806  of the slider  3  and the lapping tape  801  (α and β being between 3 degrees and 90 degrees, for example).  
         [0022]    [0022]FIG. 9 provides a detailed view of an individual slider mounted to an arm of an edge blending jig with lapping tape partially wrapping a slider edge for edge blending according to an embodiment of the present invention. In one embodiment, after a row bar is bonded to multiple arms of an edge blending jig  2  (by, e.g., epoxy) and cut into individual mounted sliders  3  (such as by a diamond cutting wheel), lapping tape  1  is inserted between the sliders  3  and the edge blending assembly is configured to wrap the lapping tape  1  around an edge of the slider  3  under a predetermined amount of tensile force. As stated above, in this embodiment, the slider  3  is directionally oscillated to achieve relative motion between the slider  3  and the lapping tape  1 .  
         [0023]    [0023]FIG. 10 illustrates an edge blending machine according to an embodiment of the present invention. In one embodiment, an edge blending jig with mounted sliders is coupled to a jig support  5  and mounted in the edge blending machine. In this embodiment, a top platform  4 , containing lapping tape rollers  16 , is attached to a base unit  9 , supporting the edge blending jig. In this embodiment, portions of lap tape  1001  are positioned and kept in alignment by a series of guide arms  17 . In this embodiment a spring mechanism  6 , which is adjusted by a tension adjustment knob  1002 , is utilized to maintain the appropriate tensile force for the portions of lapping tape  1001 . Maintaining appropriate lapping tape tension is important to prevent lapping tape  1001  breakage or dislodging of sliders from the edge blending jig arms.  
         [0024]    In this embodiment, another adjustment knob  1003  is utilized to move the lapping tape portions relative to the sliders (on the edge blending jig) to shift the relative position to partially wrap the slider edges appropriately (to provide the appropriate angles of α and β. In this embodiment, the process of edge blending is performed with the edge blending assembly submerged in lubricant. In this embodiment, a reservoir  7  is filled above the level of the sliders with a lubricant (such as a mixture of de-ionized (DI) water and oil) before edge blending.  
         [0025]    In one embodiment, rubber tape is used instead of the lapping tape with the reservoir  7  filled with a diamond slurry. In this embodiment, the diamond particles travel on the rubber tape as an abrasive to smooth the slider edge&#39;s surface. Also, in an embodiment, a cleaning process could be performed after edge blending, wherein the lapping tape  1001  is replaced with rubber tape and the reservoir  7  is filled with a cleaning solution. The slider would be oscillated with respect to the rubber tape in the cleaning solution to clean any debris left on the sliders after the edge blending process.  
         [0026]    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.