Patent Publication Number: US-2007094866-A1

Title: Thin-film tape head processes

Description:
RELATED APPLICATIONS  
      This application is a divisional of U.S. patent application Ser. No. 09/938,458 to Biskeborn et al, filed Aug. 23, 2001. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to thin-film recording heads, and more particularly, this invention relates to improving the manufacturing process of thin-film recording heads and the structure thereof.  
     BACKGROUND OF THE INVENTION  
      Conventional recording heads for linear tape drives have small transducers incorporated into a large head assembly to span the full width of the tape. For recording heads fabricated using thin-film wafer technology, this requires that the head either be fabricated individually on a wafer which is at least as wide as the recording tape and lapped individually to the proper shape, or be fabricated as a small part and assembled with larger pieces and the full assembly lapped individually to the proper shape.  
      Prior art  FIG. 1  illustrates a wafer  100  on which a plurality of heads  102  may be manufactured. As shown, the water  100  includes two columns of multiple rows of heads  102 . During the fabrication of the wafer  100 , an array of heads  102  including transducers and auxiliary circuits are fabricated on a common substrate in a deposition of metallic and non-metallic layers. The auxiliary circuits are sometimes referred to as electrical lap guides (ELGs). Patterning of the array of transducers and ELGs is accomplished using photolithography in combination with etching and lift-off processes. The finished array or wafer is then optically and electrically inspected and subsequently cut into smaller arrays of heads  102 . Next, individual heads  102  are machined, at a surface  106  which will eventually face the recording medium, to obtain a desired transducer height (sometimes referred to as the stripe height (SH) or to obtain a desired inductive transducer height sometimes referred to as the throat height (TH).  
      Prior art  FIG. 2  illustrates a wafer  200  including a plurality of strips of closures  202  attached thereto. Such closures  202  define a plurality of slots  204  in which the aforementioned contacts  206  associated with the ELGs reside. Stick closures  202  have recently become a common part of wafer processing in view of the benefits they afford in resultant heads. More information on the manufacture and use of closures  202  and the related benefits may be found with reference to U.S. Pat. Nos. 5,883,770 and 5,905,613 which are incorporated herein by reference in their entirety.  
      Prior art  FIG. 3  illustrates one of the heads  300  set forth in  FIG. 1  with a closure  302  attached thereto. As shown, the present head  300  is detached from a wafer. Since the head  300  is generated from a wafer structure, the head  300  is extremely thin in shape and form. In order to increase the stability of the head  300  for the suitable use thereof, the head  300  must be attached to a beam  304  of some sort formed of a rigid material. Such beams  304  are often referred to as a “U-beams.” One stringent requirement in attaching the head  300  to an associated beam  304  is that the relative position of the head  300  and beam  304  be precisely aligned. Absent such alignment, the operation of the head  300  may be compromised.  
      There is thus a need for a method and apparatus for the precise attachment of a head  300  and a beam  304 .  
      Yet another problem arises when attempting to dice the heads  300  on a wafer. In the prior art, a traditional magnetic head saw blade may be used to cut the heads  300  from the wafer. Recently, however, the use of the closures  302  such as that shown in  FIG. 3  has complicated such process. In particular, the increased thickness of the material to be cut has been increased since a slight portion of the closure  302  must also be diced.  
       FIG. 4  illustrates a prior art saw blade  400  in the process of dicing a head  402  equipped with a closure  404 . As shown, the increased thickness of the combined head  402  and closure  404  cause the blade to slightly bend due to the cutting forces resulting from cutting the additional material. This bending, in turn, results in non-planarity in the operating surface  406  of the head  402 .  
      There is thus a need for a method and apparatus capable of dicing a head equipped with a closure while maintaining the planarity of the head operating surface.  
       FIG. 5  is an end view illustration of one particular type of bidirectional tape head. As shown, a head  560  is provided with a flat transducing surface  561  and a row of transducers on the surface of gap  562 . An electrical connection cable  563  connects the transducers to the read/write channel of the associated tape drive. Alumina overcoat  564  protects the transducers and forms a slope discontinuity edge with respect to the flat transducing surface  561 . A slope discontinuity edge  565  is formed parallel to the gap  562  at the side of the flat transducing surface  561  opposite the gap surface.  
      To control the overwrap angle of the tape  566  at edge  565 , an outrigger  567  is provided. The outrigger  567  may be formed by cutting a groove  568  in the head  560 . A taper  569  may be lapped on the outrigger  567 , preferably at and angle about midway between the expected wrap angles the head will be presented with for various cartridges. The depth of the taper  569  is controlled so that the line from edge  565  to edge  570  is at the desired overwrap angle with respect to the flat transducing surface  561 .  
      The head penetration into the tape  566  of a cartridge is controlled so that at the minimum wrap angle  571 , the tape just touches the edge  570 . Thus, for various cartridges, the tape wrap can move between the positions indicated by  571  and  572 , while the outrigger  567  maintains a constant wrap angle onto the flat transducing surface  561 . More information on the head design shown in  FIG. 5  may be found with reference to U.S. Pat. No.: 5,905,613, which is incorporated herein by reference in its entirety.  
      Unfortunately, the above design requires two actions to afford the accompanying benefits, namely the cutting of the groove  568  and the lapping of the taper  569 . As is well known, each action that is required during the process of thin-film magnetic head manufacture creates much expense.  
      There is thus a need for a technique of affording the benefits of the groove  568  and taper  569  of  FIG. 5 , with less of a manufacturing expense.  
     DISCLOSURE OF THE INVENTION  
      A plurality of apparatuses and methods are provided for improving the manufacture and operational characteristics of thin magnetic film heads. Various embodiments of the present invention provide an apparatus and method for attaching a thin film head to a beam. An apparatus for attaching a thin film head to a beam according to one embodiment includes a base; a head mounting assembly coupled to the base and including a head holder for holding a head; and a beam mounting assembly coupled to the base and including a beam holder for holding a beam; wherein the relative position of the head holder and beam holder is configurable along an x-axis, y-axis, and z-axis and further configurable in a θx direction, θy direction, and θz direction so that the head is precisely attached to the beam.  
      A method for attaching a thin-film head to a beam according to one embodiment includes adjusting the relative position of a head holder and a beam holder along an x-axis, y-axis, and z-axis and further in a θx direction, θy direction, and θz direction, wherein the head holder is a component of a head mounting assembly pivotally coupled to a base and the beam holder is a component of a beam mounting assembly fixedly mounted to the base; attaching a head to the head holder of the head holder mounting assembly; attaching a beam to the beam holder of the beam mounting assembly; and pivoting the head holder relative to the beam holder for attaching the head to the beam.  
      Other embodiments of the present invention include a system, method and apparatus for dicing a thin film head on a wafer. A system for dicing a thin-film head on a wafer according to one embodiment of the present invention includes a wafer including a plurality of magnetic heads formed therein and a plurality of closures formed thereon; a saw blade with a substantially thin circular configuration having a planar first face, a second face, and a serrated periphery, the saw blade having a first thickness and a first diameter; and a thickened portion with a substantially disk-shaped configuration integrally coupled to the first face of the saw, the thickened portion having a second thickness greater than the first thickness and a second diameter less than ½ the first diameter; wherein the thickened portion is adapted for maintaining a rigidity of the saw blade when separating the magnetic heads from the wafer such that the magnetic heads each have a planar operating surface.  
      An apparatus for dicing a thin-film head on a wafer according to one embodiment includes a saw blade including: an outer portion with a substantially circular configuration having a periphery and a first thickness, and an inner portion with a second thickness greater than the first thickness of the outer portion. The inner portion is adapted for maintaining a rigidity of the saw blade when separating magnetic heads from a wafer such that the magnetic heads each have a planar operating surface.  
      A method for dicing a thin-film head on a wafer according to one embodiment of the present invention includes activating a saw blade including: an outer portion with a substantially circular configuration having a serrated periphery ad a first thickness, and an inner portion with a second thickness greater than the first thickness of the outer portion. A thin-film head on a wafer is diced utilizing the saw blade; wherein the inner portion is adapted for maintaining a rigidity of the saw blade when separating magnetic heads from a wafer such that the magnetic heads each have a planar operating surface.  
      Other aspects and advantages of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a fuller understanding of the nature and advantages of the present invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings.  
      Prior art  FIG. 1  illustrates a wafer on which a plurality of heads may be manufactured.  
      Prior art  FIG. 2  illustrates a wafer including a plurality of strips of closures attached thereto.  
      Prior art  FIG. 3  illustrates one of the heads set forth in  FIG. 1  with a closure attached thereto.  
      Prior art  FIG. 4  illustrates a prior art saw blade in the process of dicing a head equipped with a closure.  
      Prior art  FIG. 5  is an end view illustration of a particular type of prior art bidirectional tape head.  
       FIG. 6  is a perspective view of an apparatus for precisely attaching a thin-film head to a beam.  
       FIG. 6A  illustrates an exploded view showing the various components of the apparatus of  FIG. 6 .  
       FIG. 6B  illustrates a method for precisely attaching a thin-film head to a beam.  
       FIG. 7  illustrates a side view of a strengthened saw blade capable of affording heads with a planar operating surface, in accordance with one embodiment.  
       FIG. 8  is a side view of the saw blade taken along line  8 - 8  of  FIG. 7 .  
       FIG. 9  shows the saw blade of  FIGS. 7 and 8  while dicing heads on an accompanying wafer.  
       FIG. 10  is a perspective view of a magnetic head equipped with a single groove, in accordance with one embodiment.  
       FIG. 11  is a cross-sectional view of the groove taken along line  11 - 11  shown in  FIG. 10 .  
       FIG. 12  illustrates the head of  FIGS. 10 and 11  in use, in accordance with one embodiment.  
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      The following description is the best embodiment presently contemplated for carrying out the present invention. This description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein.  
      Beam and Magnetic Head Bonding Apparatus  
       FIG. 6  is a perspective view of an apparatus  600  for precisely attaching a thin-film head to a beam. As will soon become apparent, this is accomplished by allowing relative alignment of the head and the beam in size directions  601 . Such directions  601  are shown in the lower right-hand corner of  FIG. 6 . For further detail regarding the components of the present apparatus  600  of  FIG. 6 .  FIG. 6A  illustrates an exploded view showing the various components along with the associated fasteners, couplings, etc. of the apparatus  600 .  
      In the context of the present embodiment, a head may refer to any magnetic head capable of operating (i.e. reading, writing, etc.) in conjunction with a tape. Further, the beam may refer to any rigid support that may be attached to the head for support purposes. In one embodiment, the beam may take the form of a “U-beam.” 
      A base  602  is provided including a head mounting assembly  604  positioned thereon. The head mounting assembly  604  includes a pair of stanchions  606  fixedly mounted on a first side of the base  602 . A pivot arm  608  is provided having a first end pivotally coupled to the stanchions  606  about an axis parallel with an x-axis. See directions  601 . The pivot arm  608  further has a second end with a handle  610  and a head holder  612  coupled thereto for securely and precisely receiving a head thereon.  
      As shown in  FIG. 6 , the head holder  612  is attached to a plate  618  which is in turn screwably coupled to the second end of the pivot arm  608  for allowing the placement of a shim  620  between the plate  618  and the second end of the pivot arm  608 . The use of the shim  620  in this manner allows the adjustment of the head in a θz direction. See directions  601 .  
      The bead mounting assembly  604  further includes a vacuum assembly  614  coupled to the bead holder  612  via a hose  616 . Optionally, the vacuum assembly  614  includes gauges and a control switch for controlling purposes. In use, the vacuum assembly  614  serves for securing a head thereto utilizing a vacuum, in a manner that will soon become apparent.  
      As an option, a lever (not shown) may be provided for facilitating the extraction of the head from the head holder  612 . In use, the lever may be used to eject the head against the force of the vacuum. As yet another option, the pivot arm  608  may be biased against one of the stanchions  606  in order to abate any “play” in the pivoting of the pivot arm  608 . This is done to ensure no movement in any direction other than the pivoting action about an axis parallel to the x-axis.  
      Also provided is a beam mounting assembly  622  including a support member  624  having a first portion  626  with a rectangular configuration having a first height. The support member  624  of the beam mounting assembly  622  is fixedly mounted on a second side of the base  602 . The support member  624  is positioned long an axis parallel with the x-axis. The support member  624  further includes a second portion  628  with a rectangular configuration having a second height greater than the first height. The second portion  628  of the support member  624  is fixedly mounted to the base  602  adjacent to the first portion  626  of the support member  624 .  
      The beam mounting assembly  622  further includes a beam holder  630  positioned on a top surface of the second portion  628  of the support member  624 . The beam holder  630  includes a pair of short end edges and a pair of long side edges. The beam holder  630  is adapted for receiving a beam  632  thereon.  
      The beam holder  630  includes an x-axis stopper  634  positioned at a first one of the short end edges of the beam holder  630  for abutting the beam  632  when positioned on the beam holder  630 . It should be noted that the beam holder  630  is slidably coupled to the top surface of the second portion  628  of the support member  624  in a direction parallel to the x-axis. By this structure adjustment of the beam  632  is permitted along the x-axis. As an option, such sliding may be controlled by use of a screw  636  that is rotatably coupled to the support member  624  and screwably coupled to the beam holder  630 .  
      An intermediate member  638  of the beam mounting assembly  622  is equipped with a size and shape substantially similar to the first portion  626  of the support member  624 . If use, the intermediate member  638  is adapted for being positioned on top of the first portion  626  of the support member  624  and further along a side of the second portion  628  of the support member  624 .  
      The intermediate member  638  includes a pair of smooth holes formed at ends thereof in parallel with a y-axis. See  FIG. 6A . Such smooth holes are sized for loosely receiving a pair of screws  640  which are in turn screwably coupled to a side of the second portion  628  with at least one shim  642  therebetween. The augmented size of the holes is adapted for allowing adjustment of the beam  632  along the y-axis and in a θx direction by way of the shim  642 . See directions  601 .  
      The intermediate member  638  further includes a pair of threaded holes (see  FIG. 6A ) formed completely therethrough at ends thereof each along an axis parallel with a z-axis for screwably receiving a pair of screws  644 . Such screws abut a top of the first portion  626  of the support member  624  for allowing adjustment of the beam  632  along the y-axis and in a θy direction.  
      Still yet, the beam mounting assembly  622  includes an upper member  646  having a lower slider segment  648  with a rectangular configuration. The lower slider segment  648  of the upper member  646  of the bean mounting assembly  622  is slidably coupled to a top of the intermediate member  638  along an axis parallel with the y-axis. Such slidable coupling is preferably controlled by way of a screw  649 .  
      This may be accomplished by positioning the lower slider segment  648  in a track formed in the intermediate member  638 . Further, a rotatable coupling may be provided between the screw  649  and any fixed portion of the base  602  or support member  624 . Moreover, a screwable coupling may be provided between the screw  649  and the lower slider segment  648 . Of course, any other means of accomplishing the same may be employed.  
      An upper pivoting segment  650  of the upper member  646  is pivotally coupled at a first side  652  thereof to the lower slider segment  648 . Such coupling is performed formed about an axis parallel with the z-axis. The upper pivoting segment  650  further has a second side  654  defining a y-axis stopper for abutting the beam  632  along a first one of the long side edges of the beam holder  630 . By this design, macro adjustment of the beam  632  is afforded along the y-axis.  
      As an option a spring  655  (see  FIG. 6A ) may be coupled between the upper pivoting segment  650  and the lower slider segment  648 . Such spring serves for biasing the second side of the upper pivoting segment  650  away from the beam  632 . Associated therewith is a screw  656  screwably coupled to an arm extending from the lower slider segment  648 . In use, the screw  656  may be used for abutting the upper pivoting segment  650  to selectively determine an extent to which the upper pivoting segment  650  pivots toward the beam  632 . This in turn allows micro adjustment of the beam  632  along the y-axis.  
      Yet another component of the present embodiment is a pair of stabilizers  660  each with a first end  661  having a spring-biased pin  662  mounted therein and an intermediate portion  663  pivotally coupled to the base  602  along an axis parallel with the z-axis. A second end  664  of each of the stabilizers  660  is slidably situated on a top surface of the base  602 . Such second end is adapted for being fixed with respect to the base  602  via a clamp  667 .  
      The stabilizers  660  includes a first stabilizer  668  with the pin  662  thereof adapted for abutting the beam  632  along a second one of the long side edges of the beam holder  630 . A second stabilizer  670  is provided with the pin  662  thereof adapted for abutting the beam  632  along a second one of the short end edges of the beam holder  630 .  
      In use, the head mounting assembly  604  is adapted for attaching the head secured in the head holder  612  with the beam  632  secured in the beam holder  630  upon the pivoting of the lead mounting assembly  604 . Prior to pivoting, the beam  632  and head may be precisely aligned along six (6) degrees of freedom, namely along an x-axis, y-axis, z-axis, θx direction, θy direction, and θz direction.  
       FIG. 6B  illustrates a method  6000  for precisely attaching a thin-film head to a beam. In one embodiment, the present method  6000  may be carried out in the context of the forgoing apparatus  600 . Of course, however, the present method  6000  may also be implemented in the context of any desired machine.  
      Initially, in operation  6002 , the relative position of a head holder and beam holder is adjusted along an x-axis, y-axis, and z-axis and further in a θx direction, θy direction, and θz direction. As mentioned earlier, such adjustment is carried out so that the head is precisely attached to the beam. Next, in operation  6004 , a head is attached to the head holder of the head holder mounting assembly. This may be accomplished utilizing a vacuum assembly, or any other desired mechanism.  
      Next, a beam is attached to the beam holder of the beam mounting assembly. Note operation  6006 . The head holder is then pivoted relative to the beam holder for attaching the head to the beam. See operation  6008 . It should be noted that the vacuum assembly may be disengaged at this point.  
      Improved Saw Blade Apparatus  
       FIGS. 7 through 8  illustrate a rigid saw blade  700  for dicing a thin-film head from a wafer in a manner that prevents non-planarity in a surface on which the transducers of the head operate on an associated tape. As mentioned earlier during reference to prior art  FIG. 4 , conventional saw blades are subject to bending due to the increased thickness of the wafer resulting from the use of closures. This bending of the saw blade, in turn, results in non-planar head surfaces which affords less than optional operational characteristics.  
       FIG. 7  illustrates a side view of a saw blade  700 , in accordance with one embodiment. As shown, the saw blade  700  is equipped with a substantially thin circular configuration. The saw blade  700  further has a serrated periphery  702  for cutting heads from an accompanying wafer. As will soon become apparent, the saw blade  700  includes an outer portion  704  and a thickened inner portion  706  each with a disk-shaped configuration. As shown in  FIG. 7 , the thickened inner portion  706  has a diameter less than ½ the diameter of the outer portion  704 .  
       FIG. 8  is a side view of the saw blade  700  taken along line  8 - 8  of  FIG. 7 . As shown, the saw blade  700  has a planar first face  710  and a second face  712 . The planar first face  710  has the thickened inner portion  706  of the saw blade  700  integrally attached thereto. Further, the outer portion  704  has a first thickness while the thickened inner portion  706  has a second thickness greater than the first thickness. In one embodiment, the first thickness is at least twice the second thickness.  
       FIG. 9  shows the saw blade  700  of  FIGS. 7 and 8  while dicing heads  900  on an accompanying wafer  902 . As shown, such heads  900  are equipped with closures  904 . In the context of the present description, a closure  904  may include any member integrally, adhesively or otherwise attached to a head  900  for enlarging an operating surface thereof. In operation, the saw blade  700  is adapted for cutting the wafer  902  along one of the closures  904  such that a surface of one of the heads  900  is exposed in coplanar relationship with a surface of the closure  904  attached thereto.  
      As shown in  FIG. 9 , the diameter of the thickened inner portion  706  is such that the thickened inner portion  706  resides on a side of the saw blade  700  opposite the closure  904  when cutting, the wafer  902 . This results in the thickened inner portion  706  extending within a gap defined by the closures  904 .  
      By this design, the saw blade  700  is supported by the thickened inner portion  706  and resists any forces that would cause the saw blade  700  to bend. To this end, the surfaces of the resulting heads  900  are substantially planar, and thus exhibit improved operational characteristics.  
      Single Groove Magnetic Head  
       FIGS. 10 and 11  illustrate a magnetic head with a single groove formed therein for accomplishing the benefits of prior art magnetic head devices. As mentioned earlier, prior art magnetic head devices include an intermediate groove to afford a discontinuity edge adjacent the operating surface of the head. Moreover, a lapped surface is provided in order to provide control over the overwrap angle of the tape. See prior art  FIG. 5 .  
       FIG. 10  is a perspective view of a magnetic head  1000  equipped with a single groove  1002 , in accordance with one embodiment. As shown, the magnetic head  1000  is provided with a head body  1004  having a substantially rectangular configuration. The head body  1004  includes a top face  1006 , a bottom face  1008 , a pair of elongated side faces  1010 , and a pair of short end faces  1012 . At least one transducer  1016  is formed in communication with the top face  1006  of the head body  1004 .  
      Also provided is a closure  1018  with a substantially rectangular configuration. The closure  1018  has a length substantially equal to the head body  1004 . Further, the closure  1018  is coupled to a first one of the side faces  1010  of the head body  1004  coincident with the top face  1006  thereof. The single groove  1002  is formed in the top face  1006  of the head body  1004 , and extends between the transducers  1016  and a second one of the side faces  1010 .  
       FIG. 11  is a cross-sectional view of the groove  1002  taken along line  11 - 11  shown in  FIG. 10 . As shown, the groove  1002  is defined by a first surface  1020  positioned in a plane substantially parallel with the side faces  1010 . Such first surface  1020  is defined by edges coincident with the top face  1006  and the end faces  1012 . Note  FIG. 10 .  
      The groove  1002  is further defined by a second surface  1022  positioned in a plane substantially parallel with the top and bottom faces ( 1006  and  1008 ). The second surface  1022  is defined by edges coincident with the first surface  1020 , the end faces  1012  and the second one of the side faces  1010 .  
      In use, the groove  1002  serves for providing a discontinuity edge  1100 . Moreover, the groove  1002  controls an overwrap angle of a tape sliding along the at least one transducer  1016 . This is accomplished by setting a depth of the groove  1002  which in turn selectively positions an outrigger edge  1102 . Both the discontinuity edge  1100  and the overwrap angle control are thus afforded with a single cut during the manufacturing process, thus reducing an overall cost in producing the head.  
       FIG. 12  illustrates the head of  FIGS. 10 and 11  in use, in accordance with one embodiment. As shown,  FIG. 12  illustrates the head of  FIGS. 10 and 11  for a read-while-write bidirectional linear tape drive. “Read-while-write” means that the read transducer follows behind the write transducer. This arrangement allows the data just written by the write transducer to be immediately checked for accuracy and true recording by the following read transducer.  
      Specifically, in  FIG. 12 , two heads  1275  and  1276  as illustrated in  FIGS. 10 and 11  are mounted on U-beams  1277  which are, in turn, adhesively coupled. The wrap angle onto the flat transducing surfaces  1278  and  1279  of the tape  1280  is creased is created by the U-beams  1277 .  
      While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitations. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.