Abstract:
A head assembly has a head slider including a magnetic head and a first electrode, an IC chip supporting the head slider on a principal surface of the IC chip, and a suspension supporting the IC chip, the IC chip comprising a second electrode and a third electrode on the principal surface thereof, the third electrode being connected to the suspension, the second electrode being electrically connected to the first electrode.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a head assembly and disk drive having same. 
     2. Description of the Related Art 
     Generally, a hard disk drive has a head assembly positioned at the tip of an arm driven by an actuator. The head assembly is composed of a head slider mounted on a suspension together with an integrated circuit, or IC, chip. The head slider has a magnetic head formed using thin film technology. The magnetic head is composed of an inductive head and a magneto-resistive head, hereinafter referred to as an MR head. The inductive head writes information to a hard disk and the MR head reads recorded information from the hard disk. The head IC chip has the function of, for example, amplifying a microsignal read by means of the MR head. 
     Attendant upon recent improvements, that is, increases, of the frequency of the data signals handled by data processing devices, there is a demand for hard disk drives capable of reading and writing high data-signal frequencies of for example 200-300 MHz, well in excess of the current 70 MHz standard. As can be appreciated by those skilled in the art, raising the data signal write frequency necessitates increasing the data signal transfer rate. Increasing the data signal transfer rate in turn requires physically reducing the distance from the head slider to the IC chip, thus minimizing inductance and electrostatic capacitance along the signal transmission path between the head slider and the head IC chip. 
     Additionally, the head assembly must be one that can be produced using production techniques currently in use or under development. 
     FIGS. 1A and 1B show a head assembly  10  described in Japanese Laid-Open Patent App. No. 10-124839. A head slider  11  is joined to a head IC chip  12  and the head IC chip  12  is fixedly mounted on a suspension  13 . 
     The head IC chip  12  comprises a lower surface  12   a , an integrated circuit part and a wire pattern (neither of which is shown in the drawing), an electrode  16 , an upper surface  12   b  and another electrode  17 , the electrodes  16  and  17  being connected by a through hole  18 . 
     The head slider  11  is affixed to the lower surface  12   a  of the IC chip  12  using an adhesive agent  19 . The electrodes  15  and  16  are electrically connected to each other. A flexible cable  20  is affixed to the upper surface  12   b  of the head IC chip  12  using another adhesive agent  21 . The electrode  17  and an electrode  22  of the flexible cable  20  are electrically connected to each other. 
     According to the above-described head assembly  10 , the physical distance separating the head slider  11  and the head IC chip  12  is essentially eliminated, making it possible to greatly increase the transfer rate of the data signal. 
     However, referring to the head IC chip  12 , it can be appreciated that the electrode  17  must be formed on a surface opposite a surface on which the integrated circuit part is formed, and, further, one or more holes must be opened in a silicon wafer to form one or more through holes  18 . Yet the formation of the electrode  17  on the surface opposite the surface on which the integrated circuit part is formed and the opening of one or more holes in a silicon wafer is either very difficult or virtually impossible, and accordingly, the head IC chip  12  described above is essentially impossible to produce. 
     Additionally, referring to the common method by which the head slider  11  is produced, it should be noted that, as shown in FIG. 2, a plurality of magnetic heads  14  are arranged in the form of a matrix on a surface  26  of a wafer  25 . The wafer  25  is then cut along the matrix so as to cut out individual sliders  11 . As can be appreciated, the electrode  15  on the head slider  11  as shown in FIG. 1B is formed on a surface different from the surface on which the magnetic head  14  is formed. The surface on which the electrode  15  is formed is not the surface  26  of the wafer  25  but is instead the surface that first appears once the wafer  25  has been cut along the matrix and the individual sliders  11  cut out. Accordingly, the electrodes  15  are formed on each individual slider  11  cut from the wafer  25 . Additionally, the length of the longest side is small, that is, approximately 1 mm. Accordingly, it is very difficult to form the electrodes  15  on the surfaces of individual head sliders  11  and hence it is exceedingly difficult and substantially impossible to produce the head slider  11 . 
     Accordingly, the head assembly  10 , too, is essentially impossible to mass produce. 
     Additionally, referring to the adhesive agent  19 , it can be appreciated that because the adhesive agent  19  is injected into a gap between the head slider  11  and the head IC chip  12  after electrodes  15  and  16  have been connected to each other, there is a possibility that air bubbles may be trapped therewithin, thus reducing the strength of the bond between the head slider  11  and the head IC chip  12 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide an improved and useful head assembly and disk drive having same, wherein the foregoing problems are eliminated, 
     Another object of the present invention is to provide an improved and useful head assembly and disk drive having same, wherein the head assembly can be produced without undue difficulty. 
     Still another object of the present invention is to provide an improved and useful head assembly and disk drive having same, wherein the bonding of the head slider to the head IC chip is improved. 
     The above-described objects of the present invention are achieved by a head assembly comprising: 
     a head slider including a magnetic head and a first electrode; 
     an IC chip supporting the head slider on a principal surface of the IC chip; and 
     a suspension supporting the IC chip, the IC chip comprising a second electrode and a third electrode on the principal surface thereof, the third electrode being connected to the suspension, the second electrode being electrically connected to the first electrode. 
     Additionally, the above-described objects of the present invention are also achieved by a disk drive comprising: 
     a recording medium; 
     an arm driven by an actuator; and 
     a head assembly that rotates together with the arm, 
     the head assembly comprising: 
     a head slider including a magnetic head and a first electrode; 
     an IC chip supporting the head slider on a principal surface of the IC chip; and 
     a suspension supporting the IC chip, 
     the IC chip comprising a second electrode and a third electrode on the principal surface thereof, the third electrode being connected to the suspension, the second electrode being electrically connected to the first electrode. 
     Additionally, the above-described objects of the present invention are also achieved by an IC chip, the IC chip supporting a head slider including a magnetic head and a first electrode on a principal surface of the IC chip, a suspension supporting the IC chip, the IC chip having a size larger than a size of the head slider, the principal surface of the IC chip including an area for supporting the head slider and a second electrode electrically connected to the first electrode of the head slider and a third electrode electrically connected to the suspension, the second electrode and the third electrode provided at an area outside the area for supporting the head slider. 
     Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are diagrams showing a conventional head assembly; 
     FIG. 2 is a diagram for explaining how a head slider is manufactured; 
     FIG. 3 is a diagram showing an oblique view of a magnetic head assembly according to a first embodiment of the present invention; 
     FIG. 4 is an enlarged view of an essential part of the head assembly of FIG. 3; 
     FIG. 5 is a cross-sectional view along a line V—V shown in FIG. 4; 
     FIG. 6 is an exploded oblique view of the head slider/head IC chip assembly; 
     FIG. 7 shows one method for assembling the head assembly shown in FIG. 3; 
     FIG. 8 shows another method for assembling the head assembly shown in FIG. 3; 
     FIGS. 9A and 9B are diagrams showing a hard disk drive having the head assembly shown in FIG. 3; 
     FIG. 10 is an enlarged oblique view of a head assembly according to a second embodiment of the present invention; 
     FIG. 11 is a cross-sectional view along a line XI—XI shown in FIG. 10; and 
     FIG. 12 is an exploded oblique view of the head assembly shown in FIG.  10 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will now be given of preferred embodiments of the present invention with reference to the accompanying drawings, specifically in the first instance FIG.  3 . 
     FIG. 3 shows an oblique view of a magnetic head assembly  30  according to a first embodiment of the present invention, hereinafter referred to as a head assembly. It should be noted that FIGS. 9A and 9B show a hard disk drive  31  having the head assembly shown in FIG.  2 . For ease of explanation, a brief description will first be given of the hard disk drive  31 . 
     As shown in FIGS. 9A and 9B, the hard disk drive  31  comprises a housing  32 , within which are provided, for example, two rotating hard disks  33 - 1 ,  33 - 2 , an actuator  34  having a coil and a permanent magnet and which is electro-magnetically driven, arms  35 - 1 ,  35 - 2 ,  35 - 3  swung by the actuator  34 , and head assemblies  30 - 1 ,  30 - 2 ,  30 - 3 ,  30 - 4  mounted on the tips of the actuators  35 - 1 ,  35 - 2 ,  35 - 3 . The hard disks  33 - 1 ,  33 - 2  swing, the actuator  34  is activated, the arms  35 - 1 ,  35 - 2 ,  35 - 3  returnably rotate, the head assemblies  30 - 1  through  30 - 4  are moved in a direction of a radius of the hard disks  33 - 1 ,  33 - 2  so as to access a predetermined track and record information to and read information from the hard disks  33 - 1 ,  33 - 2 . 
     Each of the head assemblies  30 - 1  through  30 - 4  has the same composition, so hereinafter reference numeral  30  is used as a designation thereof when not referring to any one specific head assembly. 
     A description will now be given of the head assembly  30 , with reference to the accompanying drawings, specifically FIGS. 3,  4  and  5 . 
     FIG. 3 shows an oblique view of a magnetic head assembly according to a first embodiment of the present invention. FIG. 4 shows an enlarged view of an essential part of the head assembly of FIG.  3 . FIG. 5 is a cross-sectional view along a line V—V shown in FIG.  4 . 
     As shown in the diagrams, the head assembly  30  comprises a head slider  40 , head IC chip  60  and suspension  80 . More specifically, a head slider/head IC chip assembly  100  comprising the head slider  40  and head IC chip  60  Is fixedly mounted on the suspension  80 . 
     It should be noted that in FIGS. 3,  4  and  5 , an X 1  direction is toward a tip of the suspension  80  and an X 2  direction is toward a base of the suspension  80 . A Y 1 , Y 2  direction represents a width of the suspension  80 , that is, the head assembly  30 . A Z 1 , Z 2  direction represents a height of the head assembly  30 . 
     An intermediate member, that is, a spacer  110 , is fixedly mounted on a base side of the suspension  80 , the spacer  110  being fixedly mounted at a tip of the arm  35 . 
     A flexible printed cable  111  is extended from the head assembly  30 . The flexible printed cable  111  is connected to a circuit board module  112  and is electrically connected to a main IC  113  on the circuit board module  112 . The main IC  113  has recording, reproduction and amplifying circuits. Other flexible printed cables extending from other head assemblies are similarly connected to the main IC  113 . 
     The suspension  80  is made from a thin stainless steel plate, at the tip of which a gimbal  81  is provided. A plurality of copper wire patterns  82 ,  83 ,  84 ,  85  for signal transmission are formed on a top surface of the suspension  80 . The wire patterns  82 ,  83 ,  84 ,  85  are formed on top of a polyimide layer  86  itself formed on top of the stainless steel plate that composes the suspension, and are covered by another polyimide layer  87  for protection. One end of the wiring patterns  82 ,  83 ,  84 ,  85  are extended to the gimbal  81  and has electrodes  82   a ,  83   a ,  84   a  and  85   a . The other end of the wiring patterns  82 ,  83 ,  84 ,  85  extends to the base of the suspension  80  and is connected to the flexible printed cable  111 . 
     The head slider/head IC chip assembly  100  has a structure wherein, using an adhesive agent  115 , the head slider  40  is affixed to and fixedly mounted on the top surface of the head IC chip  60 , thus directly joining the head slider  40  and the head IC chip  60  to each other. 
     The head slider/head IC chip assembly  100  is mounted on the suspension by putting an adhesive agent  114  on a bottom surface of the head IC chip  60  of the head slider/head IC chip assembly  100  and affixing the head slider/head IC chip assembly  100  to the gimbal  81  of the suspension  80 . 
     The adhesive agents  114 ,  115  described above may, for example, be an epoxy-type thermosetting adhesive, an anaerobic adhesive that sets instantaneously, or a two-part adhesive. 
     FIG. 6 is an exploded oblique view of the head slider/head IC chip assembly  100 . As shown in the diagram, the head slider  40  has a volume, or size, defined by length a 1  X width b 1  X height c 1 . On a side edge surface  41  in the X 1  direction of the head slider  40  there are formed a magnetic head  42 , wire patterns  43 ,  44 ,  45 ,  46  and four electrodes  43   a ,  44   a ,  45   a ,  46   a . Rails  48 ,  49  are formed on a top surface  47  of the head slider  40 . The magnetic head  42  is formed using thin-film technology, and is composed so that an inductive head and a MR head (neither of which is shown in the drawing) are disposed one atop the other. Two wire patterns  43 ,  44  are extended from the inductive head, with electrodes  43   a ,  44   a  provided at the other ends of the two wire patterns  43 ,  44 , respectively. Two other wire patterns  45 ,  46  are extended from the MR head, with electrodes  45   a ,  46   a  provided at the other ends of the two wire patterns  45 ,  46 , respectively. 
     The electrodes  43   a ,  44   a ,  45   a ,  46   a  are disposed in a predetermined arrangement in the Y 1 , Y 2  direction. 
     Additionally, as also shown in FIG. 6, the head IC chip  60  has a volume, or size, defined by length a 2 ×width b 2 ×height c 2 . The area of the head IC chip  60  defined by length a 2 ×width b 2  is approximately twice the area of the head slider  40  described above. 
     The head IC chip  60  has a top surface (or first surface)  62  and a bottom surface (or second surface)  61 . On only the top surface  62  are formed an integrated circuit  63 , a wire pattern  64 , electrodes  65 ,  66 ,  67 ,  68  for connecting the head slider and electrodes  70 ,  71 ,  72 ,  73  for connecting the suspension. Nothing is formed on the bottom surface  61  of the head IC chip  60 . Accordingly, the head IC chip  60  can be produced efficiently and reliably by performing processes on a single surface of the wafer, using the same production process used to manufacture ordinary IC chips. 
     Reference number  76  represents a head slider mounting area for mounting the head slider  40 , and is disposed toward the X 2  end of the head IC chip  60 . Reference number  77  represents a borderline extending in the Y 1 , Y 2  direction at the X 1  end of the head slider mounting area  76 . 
     The head slider connecting electrodes  65 ,  66 ,  67 ,  68  for connecting the head slider and the suspension connecting electrodes  70 ,  71 ,  72 ,  73  for connecting the suspension are formed on the top surface  62  of the head IC chip  60  yet outside the head slider mounting area  76 , more specifically, in an area extending beyond the head slider mounting area  76  on the X 1  side of the top surface  62  of the head IC chip  60 . Accordingly, in a state in which the head slider  40  is mounted on the head slider mounting area  76  of the top surface  62  of the head IC chip  60 , the head slider connecting electrodes  65 ,  66 ,  67 ,  68  and the suspension connecting electrodes  70 ,  71 ,  72 ,  73  are not covered by the head slider  40  but instead remain exposed. Accordingly, as will be described later, the electrical connections between the electrodes  43   a ,  44   a ,  45   a ,  46   a  and the head slider connecting electrodes  65 ,  66 ,  67 ,  68 , and between the suspension connecting electrodes  70 ,  71 ,  72 ,  73  and the electrodes  82   a ,  83   a ,  84   a ,  85   a , are made using an area of the top surface  62  of the head IC chip  60  that is outside the head slider  40  mounted thereon. 
     The suspension connecting electrodes  70 ,  71 ,  72 ,  73  are aligned along the X 1  edge  78  of the head IC chip  60 . The head slider connecting electrodes  65 ,  66 ,  67 ,  68  and the suspension connecting electrodes  70 ,  71 ,  72 ,  73  are electrically connected to each other by using the wire pattern  64 . 
     Reference number  79 , seen for example in FIG. 5, is a protective layer that covers the entire top surface  62  of the head IC chip  60  except for the head slider connecting electrodes  65 ,  66 ,  67 ,  68  and the suspension connecting electrodes  70 ,  71 ,  72 ,  73 . Accordingly, the head slider  40  is affixed to the head slider mounting area  76  of the top surface  62  of the head IC chip  60  without damaging the integrated circuit  63 . 
     The head slider connecting electrodes  65 ,  66 ,  67 ,  68  are aligned along the borderline  77  of the head slider mounting region  76  so as to correspond to electrodes  43   a ,  44   a ,  45   a ,  46   a . Accordingly, as shown in FIGS. 4 and 5, in a state in which the head slider  40  is affixed to the head slider mounting area  76  on the top surface  62  of the head IC chip  60 , electrodes  43   a ,  44   a ,  45   a ,  46   a  are positioned so as to correspond at right angles to head slider connecting electrodes  65 ,  66 ,  67 ,  68 . Accordingly, electrodes  43   a ,  44   a ,  45   a ,  46   a  and head slider connecting electrodes  65 ,  66 ,  67 ,  68  are electrically connected to each other by a gold (Au) ball  116  formed by a wire bonding method. The gold ball  116  does not project beyond the rails  47 ,  48  of the head slider  40 . A conductive member other than the gold ball  116  may be used. 
     The suspension connecting electrodes  70 ,  71 ,  72 ,  73  and electrodes  82   a ,  83   a ,  84   a ,  85   a  are electrically connected to each other by a gold wire  117  bonded so as to form an arc-shaped bridge. 
     It should be noted that that the head IC chip  60  may alone be covered in a resin. 
     A description will now be given of methods of assembling the above-described head assembly  30 . 
     FIG. 7 shows one method for assembling the head assembly  30  shown in FIG.  3 . As shown in the diagram, the head assembly  30  is assembled by affixing the head slider  40  onto the head IC chip  60 , putting a gold ball  116  so as to assemble the head slider/head IC chip assembly  100  and then affixing the head slider/head IC chip assembly  100  to the gimbal  81  of the suspension  80  and, finally, bonding a gold wire  117 . 
     FIG. 8 shows another method for assembling the head assembly  30  shown in FIG.  3 . As shown in the diagram, the head IC chip  60  is affixed to the gimbal  81  of the suspension  80 , the gold wire  117  is bonded, the head slider  40  is affixed onto the head IC chip  60  and, finally, the gold ball  116  is put in place, completing assembly. 
     The affixing of the head slider  40  onto the top of the head IC chip  60  and the affixing of the head slider/head IC chip assembly  100  onto the top of the gimbal  81  of the suspension  80  are accomplished by applying a coating of adhesive agent and pressing the contact surfaces together. Accordingly, no air is trapped and so no air bubbles arise to weaken the bond, and thus the affixed members are strongly attached to their respective mounting areas. 
     A description will now be given of a head assembly according to a second embodiment of the present invention. 
     FIG. 10 is an enlarged oblique view of a head assembly  30 A according to a second embodiment of the present invention. FIG. 11 is a cross-sectional view along a line XI—XI shown in FIG.  10 . 
     FIG. 12 is an exploded oblique view of the head assembly  30 A shown in FIG.  10 . 
     The head assembly  30 A has a suspension  80 A and a head slider/head IC chip assembly  100 A. 
     As shown in FIGS. 11 and 12, the suspension  80 A has a gimbal  81 A, the gimbal  81 A having an opening  150  of a size corresponding to a size of the head slider  40 . Electrodes  82   a ,  83   a ,  84   a ,  85   a  are aligned along one edge of the opening  150  in the Y 1 , Y 2  direction. 
     The head slider/head IC chip assembly  100 A is of a composition such that a gold bump  155  is formed on each of the suspension connecting electrodes  70 ,  71 ,  72 ,  73  described above with respect to the first embodiment. 
     The head assembly  30 A is of a composition such that the head IC chip  60 A is in a face-down flip-chip state, in which the gold bumps are connected to corresponding electrodes  82   a ,  83   a ,  84   a ,  85   a  and the head slider/head IC chip assembly  100  is mounted on the gimbal  81 A. The head slider  40  is fitted into the opening  150  so as to project beyond the suspension  80 A in a downward Z 2  direction. 
     As shown in FIG. 11, a thickness t of the suspension  80  is included within a thickness of the head slider  40 , so the head assembly  30 A is thinner than for example the head assembly  30  shown in FIG. 6 by a margin equivalent to the thickness t of the suspension. 
     The above description is provided in order to enable any person skilled in the art to make and use the invention and sets forth the best mode contemplated by the inventors of carrying out their invention. 
     The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope and spirit of the present invention. 
     The present application is based on Japanese Priority Application No. 11-189282, filed on Jul. 2, 1999, the entire contents of which are hereby incorporated by reference.