Patent Publication Number: US-9849567-B2

Title: Lapping assembly or process utilizing a bar stack extender

Description:
SUMMARY 
     The present application discloses embodiments of a slider bar extender to removably connect one or more slider bars to a processing machine or tool. In illustrated embodiments, the extender is coupled to a holder structure through a tongue and groove connection. In illustrated embodiments, the tongue of the tongue and groove connection is formed on the holder structure and the groove is formed on the extender. In illustrated embodiments, the extender includes a plurality of reduced thickness strips. The reduced thickness strips are orientated lengthwise to control or transfer bending to one or more slider bars connected to the bar extender. Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a slider bar stack, slider bar and head fabricated from a wafer using thin film deposition techniques. 
         FIGS. 2A-2C  illustrate a slider bar extender and tongue and groove connection to connect the bar extender and one or more slider bars to a holder structure of a processing machine or tool. 
         FIGS. 3A-3C  illustrate an alternate embodiment of the tongue and groove connection for connecting the extender and the one or more slider bars to the holder structure of the processing machine or tool. 
         FIGS. 4A-4C  illustrate embodiments of a tongue and groove connection and clamping mechanism to secure the bar extender to a holder structure. 
         FIGS. 5A-5B  illustrate an embodiment of a bar extender including the groove of the tongue and groove connection. 
         FIGS. 6A-6B  illustrate an embodiment of a modular lapping carrier holder structure for a bar extender utilizing a tongue and groove connection. 
         FIGS. 7A-7B  illustrate a bending insert for the lapping carrier holder structure illustrated in  FIGS. 6A-6B . 
         FIG. 7C  illustrates an extender slot formed between upright holder portions of the bending insert illustrated in  FIGS. 7A-7B . 
         FIGS. 8A-8B  illustrate an embodiment of a camming device for opening the extender slot to insert the bar extender and release or close the slot to grip the bar extender for lapping. 
         FIGS. 9A-9B  illustrate an embodiment of the bending insert of the lapping carrier holder structure including a tongue and groove connection and clamping mechanism to secure the extender to the bending insert for lapping. 
         FIGS. 10A-10C  illustrate one embodiment of a bar extender including a plurality of reduced thickness strips or portions, where  FIG. 10A  is a perspective view,  FIG. 10B  is a front view and  FIG. 10C  is an end view. 
         FIGS. 11A-11C  illustrate another embodiment of a bar extender including a plurality of reduced thickness strips or portions, where  FIG. 11A  is a perspective view,  FIG. 11B  is a front view and  FIG. 11C  is an end view. 
         FIG. 12  illustrates a processing sequence for slider bars in which embodiments of the present application are used. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present application discloses a workpiece extender for holding a bar stack for grinding, lapping and slicing steps for fabricating heads for data storage devices. As shown in  FIG. 1 , heads  100  are fabricated on a wafer  102  using thin film deposition techniques to deposit one or more transducer elements on a front surface  104  of the wafer  102 . The wafer  102  is sliced to form a bar stack  110  having a plurality of slider bars  112 . The bar stack  110  includes multiple or any number of slider bars  112 . Bars  112  are sliced from the bar stack  110  and the heads  100  are sliced from the bars  112  as progressively shown. The slider bars  112  include a leading edge  120 , a trailing edge  122 , an air bearing surface  124  and a back surface  126 . As shown, the deposited thin film layers form one or more transducer elements  130  along the air bearing surface  124  of the slider bar  112 . During the fabrication process, bars  112  are subjected to grinding and lapping steps to control dimensional parameters and bow of the bars  112  utilizing various processing machines or tools. 
     The bar stack  110  is connected to a processing machine or tool to fabricate the heads  100  through an extender  140  shown in  FIG. 2A . The extender  140  connects to a holder structure  142  of the processing machine or tool. As shown in  FIG. 2A , the extender  140  is connected to the holder structure  142  of the processing machine or tool through a tongue and groove connection. In the illustrated embodiment shown in  FIGS. 2A-2C , the tongue and groove connection includes a groove  144  formed on the extender  140  (as shown in  FIG. 2A ) and a tongue  146  formed on the holder structure  142 . In the embodiment shown, the tongue  146  is formed in an extender slot  150  between upright holder portions  152 ,  154  of the holder structure  142 . As shown in  FIGS. 2B-2C , the tongue  146  is formed on the upright holder portion  152  and protrudes into the slot  150  between the upright holder portions  152 ,  154 . 
     As shown, the upright holder portions  152 ,  154  of the holder structure  142  are separated as shown in  FIG. 2C  to open slot  150  to insert the extender  140  into the slot  150 . The upright holder portions  152 ,  154  are separated via application of a camming force through a camming device  156  as comparatively shown in  FIGS. 2B-2C . After the extender  140  is inserted into the slot  150 , the camming force is released to close the upright holder portions  152 ,  154  so that tongue  146  inserts into groove  144  to grip the extender  140  between the upright holder portions  152 ,  154  to secure the slider bar stack  110  to the holder structure  142  of the processing machine or tool. 
     As illustrated in  FIGS. 2A-2B , in a closed position, a camming lobe of the camming device  156  is orientated lengthwise. As shown in  FIG. 2C , the camming lobe of the camming device  156  is orientated crosswise to separate or opened the upright holder portions  152 ,  154  to connect the bar stack  110  to the holder structure  142  of the processing machine or tool. The dimension of the lobe is wide enough to separate the upright holder portions  152 ,  154  to slide the extender  140  into the slot  150  and engaged the tongue and groove connection.  FIGS. 3A-3C  illustrate an alternate embodiment of holder structure  142  and tongue and groove connection where the tongue  146  is on the extender  140  and the groove  144  is formed on the upright holder portion  152 . 
       FIGS. 4A-4B  illustrate an embodiment of the holder structure  142  including holder portion  160  and clamping device  162  (schematically shown). As shown in  FIG. 4A , the holder portion  160  includes tongue  146  on a backside of the holder portion  160  to interface with the groove  144  on the extender  140 . As shown, the clamping mechanism  162  operates between a clamped position shown in  FIG. 4A  and an open position shown in  FIG. 4B . In the clamped position shown in  FIG. 4A , the clamping device  162  biases the extender  140  against the holder portion  160  to maintain the tongue  146  in groove  144  to hold the slider bar stack  110  to the processing machine or tool. In the open position, the clamping mechanism  162  is disengaged from the extender  140  to remove the extender  140  and bar stack  110  from the processing machine or tool. In an alternate embodiment shown in  FIG. 4C , the tongue  146  is formed on the extender  140  and the groove  144  is on the holder portion  160  to secure the bar stack  110  to the holder structure  142  for processing. 
       FIGS. 5A-5B  illustrate an embodiment of the extender  140  having the groove  144  of the tongue and groove connection. As shown the extender  140  is formed of an extender body  180  having a lengthwise dimension  182  between a proximal edge surface  184  and a distal edge surface  186 . The body  180  also includes and a crosswidth  190  extending between opposed end surfaces  192 ,  194 . The extender  140  includes a thickness between a front surface  196  and a back surface  198 . As shown, groove  144  is formed along the front surface  196  of the extender  140  and extends along the crosswidth  190  of the extender between the opposed end surfaces  192 ,  194 . The groove  144  forms a recessed surface spaced from the front surface  196  between upper and lower edges of the groove  144 . The ends of the groove  144  are opened at the opposed end surfaces  192 ,  194  of the extender body  180 . As shown, the bar stack  110  is attached to the proximal edge surface  184  of the extender  140  through an adhesive layer  200  connecting the bar stack  110  to the top surface  184  of the extender  140 . 
       FIGS. 6A-6B  illustrate an embodiment of a holder structure  142  for the bar stack  110  for a lapping machine including one or more bending actuators to adjust bending or bow to the bar  112  or bar stack  110  (not shown in  FIGS. 6A-6B ) through the extender  140 . As shown, the holder structure  142  is a modular carrier device  210  including a carrier base  212  and a bending insert  214 . The bending insert  214  is supported in the carrier base  212  and forms a bending portion of the holder structure  142 .  FIG. 6B  illustrates the bending insert  214  exploded from the carrier base  212 . The carrier base  212  is coupled to an arm of the lapping machine  216  (schematically shown). The arm of the lapping machine  216  is biased towards an abrasive lapping surface (not shown) to support the modular carrier device  210  and bar stack  110  (not shown in  FIGS. 6A-6B ) against the abrasive lapping surface. The bending insert  214  is connected to the carrier body  212  through one or more pins or fasteners (not shown) extending through openings  218 ,  219  in the bending insert  214  and carrier base  212 . 
     As shown, the lapping machine includes a plurality of bending actuators  220  (schematically shown) to impart a force or bending input to the bending fingers  222  on the bending insert  214 . As shown in more detail in  FIGS. 7A-7B , the bending insert  214  includes slot  150  between upright holder portions  152 ,  154  of the insert  214 . As previously described, the extender  140  is inserted into the slot  150  to support the bars  112  for lapping against the abrasive lapping surface. As shown, the bending insert  214  includes an insert block  240  having a plurality of bending tines  242  to allow the insert  214  to flex to impart bending to the bar stack  110  through the extender  140 . Force is imparted to the bending tines  242  through the fingers  222  spaced along a width of block  240 . As previously described, the bending actuators  220  are coupled to the fingers  222  to impart bending to the block  240  through tines  242 . 
     In the illustrated embodiment, the insert  214  includes a front section  250  and back section  252  connected through flexible plates  254 . As shown, the slot  150  for the extender  140  is formed in the front section  250  between upright holder portions  152 ,  154 . As shown in more detail in  FIG. 7C , the tongue  146  is formed in slot  150  along a backside of upright holder portion  152  to interface with groove  144  along the extender  140 . The front section  250  also includes a channel  260  opened to slot  150  through gap  262  separating the upright holder portions  152 ,  154 . A camming device  265  shown in more detail in  FIGS. 8A-8B  rotates in channel  260  to bias the upright holder portions  152 ,  154  outwardly to open the slot  150  to insert the extender  140  to secure the bar stack  110  to the carrier device or holder structure  142 . While the slot  150  is open, the extender  140  is inserted by sliding the extender  140  into and along the slot  150  to position the extender  140  in the slot  150  before releasing the camming device  265  to close the slot  150 . 
     As shown in  FIGS. 8A-8B , the camming device  265  includes a rod portion  266  and head portion  268 . As shown, the rod portion  266  includes a lobe  270  (shown in  FIG. 8B ), which provides a camming dimension sized so that when the rod portion  266  is orientated in a crosswise direction in channel  260 , the rod portion  266  biases the upright holder portions  152 ,  154  outwardly to open the slot  150 . The lobe  270  is orientated lengthwise direction to close the slot  150 . The head portion  268  of the camming device  265  includes a hex extension  272 , which extends into a hex socket  274  on the rod portion  266 . The head portion  268  includes a detent rail  276 , which engages a lip  278  (shown in  FIG. 6B ) of the carrier base  212  to lock the rod  266  or camming device  265  in the crosswise position so that the slot  150  remains closed to hold the extender  140  and bar stack  110  during the lapping or other operation. 
     In the embodiment shown in  FIGS. 8A-8B , the camming device  265  is rotated by an operator. In an alternate embodiment, the camming device  265  is operated through a mechanized device or includes mechanized components for opening and closing the slot  150  to secure the extender  140  and bar stack  110  to the holder structure  142  of the processing machine or tool. 
       FIGS. 9A-9B  illustrates an alternate embodiment of the bending insert  214  for the modular carrier device  210 . As shown, the insert  214  include tongue  146  formed on the upright holder portion on a backside of the front segment  250 . As shown, clamping device  162  is supported in a gap region  280  between the front and back segments  250 ,  252  of the bending insert  214 . As shown, the extender  140  inserts into the gap region  280  between the front and back segments  250 ,  252  and is clamped to the upright holder portion on the back side of the front segment  250  via clamping mechanism  162 . As comparatively illustrated in  FIGS. 9A-9B , the clamping mechanism  162  includes a cam element rotatable between a clamped position and an unclamped position. In particular, as shown, the elongate dimension of the cam element is orientated crosswise to clamp the extender  140  to the upright holder portion or front segment  250  and lengthwise to insert and remove the extender  140 . Although the holder structure  142  illustrated in  FIGS. 6A-6B  and  FIGS. 7A-7B  is a modular carrier device having a separate bending insert  214  and carrier base  212 , application is not limited to the modular construction and additional embodiments of the carrier device include a unitary structure having an integral carrier body and bending portion. 
       FIGS. 10A-10C  and  FIGS. 11A-11C  illustrate embodiments of the extender  140  where like numbers are used to refer to like parts in the previous FIGS. In the embodiment shown, the extender  140  includes a plurality of reduce thickness strips  300  orientated lengthwise and the groove  144  extends crosswise. The reduced thickness strips  300  are spaced between the opposed end surfaces  192 ,  194  to transmit the bending profile from the bending insert  214  to the slider bar stack  110 . The reduced thickness strips  300  are formed of shallow trenches cut along the front surface  196  of the extender  140 . In the embodiment shown in  FIGS. 10A-10B , the reduced thickness strips  300  extend along the front surface  196  and in the embodiment shown in  FIGS. 11A-11C , the shallow trenches of the reduced thickness strips  300  have a length that extends from above the groove  144  below the groove  144  and along the distal edge surface  186  of the extender  140 . 
     The tongue and groove connection shown in the previous FIGS. has application for connecting the slider bar stack  110  to different grinding and lapping machines for grinding, lapping and slicing bars.  FIG. 12  illustrates a process sequence for bars N 1 -N 3  in a bar stack  110 . As shown in  FIG. 12 , the top bar N 1    112  of the stack  110  is sequentially ground in step  310 , lapped in step  314  and cut from the stack  110  in step  314 . In particular, the surface of top bar N 1  is ground in step  310  and lapped in step  312 . Following the grinding and lapping in steps  310 ,  312 , the top bar N 1  is cut from the stack  110  so that bar N 2  becomes the top bar. The process of grinding—lapping—cutting of steps  310 ,  312 ,  314  is then repeated for top bar N 2  so that following step  314  bar N 3  is the top bar. The process steps of grinding and lapping  310 ,  312  the top surface is repeated for top bar N 3 . The process sequence illustrated in steps  310 ,  312  and  314  is repeated until each bar in the stack is ground and lapped and then separated from the stack  110 . As illustrated in  FIG. 12 , once the bottom bar N 3  is ground and lapped in steps  310 ,  312 , the bar N 3  is separated from the extender  140  as shown. 
     In illustrated embodiments, the bars  112  of the bar stack  110  are ground, lapped and sliced using a grinding/slicing machine and a lapping machine. Thus, to implement the process steps illustrated in  FIG. 12 , bar stack  110  is mounted on the grinding/slicing machine for the grinding and slicing steps  310 ,  314  and the lapping machine to implement the lapping step  312 . Embodiments of the present application facilitate mounting and demounting of the bar stack  110  to the different processing machines including the grinding/slicing machine and the lapping machine. In particular as described, the bar stack  110  is adhered or connected to the extender  140 . The extender  140  is connected to the different processing machines or tools via the tongue and groove connection as described. Thus the extender  140  is connected to the grinding/slicing machine to grind the top bar in step  310 . The extender  140  is removed and connected to the lapping carrier or device to lap the top bar in step  312 . Thereafter the extender  140  is connected to the grinding/slicing machine to slice the top bar in step  314  and grind the next bar N 2  in step  310 . 
     It is to be understood that even though numerous characteristics and advantages of various embodiments of the invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, although the preferred embodiment described herein is directed to it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other lapping or grinding applications without departing from the scope and spirit of the present invention.