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. Lapping tape is inserted between each of a number of head sliders bonded to a edge blending jig of an edge blending assembly. The edge blending assembly is adjusted to cause the lapping tape to partially wrap an edge of each slider. The head sliders are edge blended by the relative movement between the sliders and the lapping tape.

Description:
BACKGROUND INFORMATION 
   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. 
     FIG. 1  provides an illustration of a typical hard disk drive. Hard disk drive storage devices typically include a rotating disk  101  mounted for rotation by a spindle motor (not shown). A slider  102 , supported by a suspension arm  103 , ‘flies’ over the surface of the magnetic disk  101  at a high velocity, reading data from and writing data to concentric data tracks  104  on the disk  101 . The slider  102  is positioned radially by a voice coil motor  105 . 
     FIG. 2  shows a more detailed view of a head slider  102  flying over the surface of a magnetic disk  101  as is typical in the art. Modern head sliders  102  float over the surface of the disk  101  on a cushion of air. If the ‘flying height’ is too great, the head  201  on the head slider cannot properly read from and write to the disk  101 . If it is too small, there is an increased chance of a head crash. 
   If a head slider  102  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  101 , or all three. One of the most common causes of head crashes is a contaminant getting wedged in the microscopic gap between head  102  and disk  101 . Head sliders  102  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  102  (explained below), the ceramic crystal array causes the slider  102  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  102 . A deformation layer  301  is created by the pressure created by the cutting process. (See  FIG. 3 ). 
     FIG. 3  illustrates the problems related to particle contamination and edge jump as is typical in the art. The problems concerning loose chips  302  and edge jump  301  can cause hard drive head crashes. A loose chip  302  may fall from the slider and contaminate the interface between the slider  102  and disk  101 . An edge jump  301  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  101 . 
   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 DRAWING 
       FIG. 1  provides an illustration of a typical hard-disk drive. 
       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. 
       FIG. 3  illustrates the problems related to particle contamination and edge jump as is typical in the art. 
       FIG. 4  illustrates a head parting jig as is typical in the art. 
       FIG. 5  illustrates an edge blending jig according to an embodiment of the present invention. 
       FIG. 6  illustrates the attachment of a head blending jig to a head blending machine according to an embodiment of the present invention. 
       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. 
       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. 
       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. 
       FIG. 10  illustrates an edge blending machine according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
     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  102  by a slider parting tool (not shown). 
     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  102  by a slider parting tool (not shown). One advantage of this jig design is that imperfections on the edges of the sliders  102  (such as edge jump) can be detected by viewing the sliders from behind  505  and observing the uniformity of gaps between the sliders  102 . 
     FIG. 6  illustrates the attachment of a head blending jig  601  to a head blending machine according to an embodiment of the present invention. In one embodiment, the edge blending jig  601  is coupled to a support assembly  602  of the head blending machine by a pair of pins  603 . 
     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  102 .  FIG. 7   a  shows the edge blending assembly in a ‘standby’ configuration with the sliders  102  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  102  on the edge blending jig  601  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  601  is directionally oscillated  702  by the edge blending assembly to cause relative motion between the sliders  102  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  102  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. 
     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  802  of the slider  102  and the lapping tape  801 , and a second angle (β) is formed between the opposite face  803  of the slider  102  and the lapping tape  801  (α and β being between 102 degrees and 90 degrees, for example). 
     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  901  (by, e.g., epoxy) and cut into individual mounted sliders  102  (such as by a diamond cutting wheel), lapping tape  902  is inserted between the sliders  102  and the edge blending assembly is configured to wrap the lapping tape  902  around an edge of the slider  102  under a predetermined amount of tensile force. As stated above, in this embodiment, the slider  102  is directionally oscillated to achieve relative motion between the slider  102  and the lapping tape  902 . 
     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  1001  and mounted in the edge blending machine. In this embodiment, a top platform  1002 , containing lapping tape rollers  1003 , is attached to a base unit  1004 , supporting the edge blending jig. In this embodiment, portions of lap tape  1005  are positioned and kept in alignment by a series of guide arms  1006 . In this embodiment a spring mechanism  1007 , which is adjusted by a tension adjustment knob  1008 , is utilized to maintain the appropriate tensile force for the portions of lapping tape  1005 . Maintaining appropriate lapping tape tension is important to prevent lapping tape  1005  breakage or dislodging of sliders from the edge blending jig arms. 
   In this embodiment, another adjustment knob  1009  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  1010  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. 
   In one embodiment, rubber tape is used instead of the lapping tape with the reservoir  1010  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  1010  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. 
   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.