Abstract:
In a magnetic head adhesively fixing a slider having a thin film magnetic element on a slider adhesive tongue of a flexure made of metal material constituting a gimbal suspension through a plurality of spacer projections formed on the slider adhesive tongue, four spacer projections are provided on the slider adhesion tongue in a radial direction from a predetermined center position overlapping a center of an adhesive surface of the slider. The slider is adhered onto the spacer projections by adhesive resin applied therebetween.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a magnetic head having a slider which is adhesively supported to a flexure of a head gimbal assembly.  
         [0003]     2. Description of the Related Art  
         [0004]     A HGA (head gimbal assembly) widely used in HDD is formed by adhesively fixing a slider having a thin film magnetic head element (MR element, GMR element) on one tip of a flexure which made of metal and is fixed on a front tip of a load beam. In a structure in which the slider is adhesively fixed on the surface of the flexure directly by adhesive resin, the thickness of the applied adhesive resin is not uniform, and the structure may introduce deformation and declination to the slider due to uneven shrinkage and temperature changes upon curing of the adhesive resin.  
         [0005]     Therefore, a structure has been developing in which spacer projections and slits are provided on the surface of the flexure, the adhesive resin fills a region surrounded by the spacer projections and a region defined by the spacer projections and slits, so that the slider is adhesively fixed on the flexure (see JP-A-7-169224 (U.S. Pat. No. 6,801,398 B1), JP-A-9-282824 (U.S. Pat. No. 5,880,908), and JP-A-11-149625 (U.S. Pat. No. 6,078,472)).  FIG. 7  is a perspective view showing a state before a slider is adhesively fixed on a front tip of a flexure according to the related art, and  FIG. 8  is a plan view showing a flexure according to the related art. A flexure  121  has thereon a plurality of rod-shaped spacer projections  122   a ,  122   b , and  122   c  supporting the vicinities of three sides of a rear surface of a slider  11 , a circular spacer projection  122   d  supporting the center of the rear surface of the slider  111 , and electrodes  133   a  to  133   d  formed on a FPC substrate. The slider  111  has a magnetic head element  113  meeting with a surface (ABS surface)  112  facing a magnetic recording medium, and electrodes  114   a  to  114   d  connected to the magnetic head element  113  on its trailing end surface. The electrodes  114   a  to  114   d  are connected to the electrodes  133   a  to  133   d  by ball bonding.  
         [0006]     The slider  111  is adhered onto the spacer projections  122   a  to  122   d  and the flexure  121  at the rear surface of the slider opposite to the surface  112  facing the recording medium by adhesive resin  124  that is applied on the spacer projections  122   a  to  122   d  or filled in the region surrounded by the spacer projections  122   a  to  122   c . An ultraviolet curing adhesive resin is used as the adhesive resin  124 , the ultraviolet curing adhesive resin is cured by irradiating with ultraviolet rays thereon.  
         [0007]     However, when the adhesive resin  124  is applied on a central region, as shown in  FIG. 8 , the adhesive resin  124  partially and unevenly spreads, which leads to variations in an applied area and irregular deformation. In addition, if the adhesive resin is thickly applied on the surface of the circular spacer projection  122   d  at the center, the slider  111  is separated from one of the spacer projections  122   a  to  122   c  other than the spacer projection  122   d,  which leads to declining and out of alignment of the slider  111 .  
         [0008]     While the ultraviolet curing adhesive resin  124  is being cured by irradiating ultraviolet rays, most of the ultraviolet rays entering from the side are blocked by the spacer projections  122   a  to  122   c.  For this reason, according to the related art, the UV holes  125   a  and  125   b  are formed in the flexure  121  so as to enlarge an area irradiated by the ultraviolet radiation. However, the ultraviolet radiation does not sufficiently irradiate the adhesive resin through the UV holes  125   a  and  125   b , and the adhesive resin  124  that is separated from the holes are not sufficiently cured, which causes the flexure  121  to deform. If the UV holes  125   a  and  125   b  are formed in a larger size, for example, when a long slit is formed as described in JP-A-1995-169224, the strength of the flexure  121  grows weaker, which causes the flexure  121  to easily deform and even leads to leakage of the adhesive resin  124  from the slit. Moreover, the structure (JP-A-1997-282824 and JP-A-1999-149625), in which more spacer projections are provided by decreasing the size of each spacer projection, may introduce deformation due to uneven application and curing of the adhesive resin.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention has been made in view of the drawbacks inherent in the magnetic head according to the related art, and it is an object of the present invention to provide a magnetic head in which an adhesive resin adhering a slider of the magnetic head onto a flexure is evenly applied, the slider and the flexure are kept from deforming, and thereby easily adhering onto each other.  
         [0010]     According to an aspect of the invention, in a magnetic head in which a slider having a thin film magnetic element is adhesively fixed on a flexure, made of metal material, constituting a gimbal suspension through a plurality of spacer projections provided on the flexure, the slider is adhered onto the flexure by adhesive resin which is applied between the slider and the spacer projections and spreads along the respective spacer projections.  
         [0011]     According to the aspect of the invention, preferably, the spacer projections are provided in a radial direction from the vicinity of a predetermined center position overlapping a plane center of the slider, when the slider is mounted on the flexure.  
         [0012]     In fact, the spacer projections are separated from one another in a diagonal direction of the slider from the vicinity of the predetermined center position.  
         [0013]     According to another aspect of the invention, the spacer projections extend in four directions overlapping the diagonal direction of the slider from the vicinity of the predetermined center position, and spacer projections extending in two directions of the leading side and two directions of the trailing side of the slider are continuously connected, respectively, in the vicinity of the predetermined center position.  
         [0014]     According to another aspect of the invention, the spacer projections are radially provided, from the vicinity of the predetermined center position, at the positions overlapping the diagonal line of the slider, a center line which is parallel to a longitudinal direction and passes through the plane center of the slider, and a center line which is parallel to a latitudinal direction and passes through the plane center of the slider.  
         [0015]     According to these aspects of the invention, the slider and the respective spacer projections are adhered onto each other by an adhesive resin which is dropped, applied or filled in the vicinity of the predetermined center position and spreads out between the slider and the respective spacer projections.  
         [0016]     According to another aspect of the invention, in a magnetic head in which a slider having a thin film magnetic element is adhesively fixed on a flexure, made of metal material, constituting a gimbal suspension through a plurality of spacer projections provided on the flexure, a plurality of spacer projections extending from a vicinity of a predetermined center position of the flexure toward edges are provided, and the respective spacer projections are formed such that the adhesive resin that is dropped, applied or filled between the slider and the respective spacer projections, and spreads along the respective spacer projections.  
         [0017]     According to another aspect of the invention, the spacer projections which adhesively fix the slider to the flexure are provided to extend in a direction from the predetermined center position of the flexure toward edges is provided, and the slider is adhered onto the flexure by adhesive resin which is applied or filled between the slider and the spacer projections and spreads along the respective spacer projections. Therefore, the adhesive resin can be evenly applied, so that it is possible to have the whole adhesive resin uniformly exposed to ultraviolet rays when the ultraviolet rays irradiate the adhesive from the side of the slider, and to evenly cure the adhesive resin. Accordingly, the slider and flexure are kept from deforming. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is an exploded perspective view showing an embodiment of a structure in which a slider is adhered onto a flexure to which the invention is applied;  
         [0019]      FIG. 2  is a plan view of the flexure according to a first embodiment of the invention;  
         [0020]      FIG. 3  is a plan view of the flexure according to a second embodiment of the invention;  
         [0021]      FIG. 4  is a plan view of the flexure according to a third embodiment of the invention;  
         [0022]      FIG. 5  is a plan view of the flexure according to a fourth embodiment of the invention;  
         [0023]      FIG. 6  is a plan view of the flexure according to a fifth embodiment of the invention;  
         [0024]      FIG. 7  is a perspective view showing an exploded state of a flexure and a slider according to the related art; and  
         [0025]      FIG. 8  is a plan view showing a biased state of adhesive resin of a flexure according to the related art. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]      FIG. 1  is an exploded perspective view of a front tip of a flexure constituting a head gimbal assembly to which the invention is applied to, and  FIG. 2  is a plan view of the flexure according to a first embodiment of the invention. A flexure  21  according to this embodiment is made of stainless steel which is laser-welded to a front tip of a load beam pivotably supported by a rotation shaft (not shown).  
         [0027]     In the front tip of the flexure  21 , a slider adhesion tongue  21   b  which is elastically deformable is formed by a U-shaped through groove  21   a.  An FPC substrate  31  is provided on the flexure  21  so as to surround the U-shaped through groove  21   a.  In  FIG. 1 , even though the FPC substrate  31  is separated from the flexure  21  for descriptive purposes, the FPC substrate  31  is formed by laminating a resin base and a lead on the flexure  21  in fact. The slider adhesion tongue  21   b  is exposed through an opening  31   b  of the FPC substrate  31 .  
         [0028]     Lead patterns  32   a  and  32   b  and lead patterns  32   c  and  32   d  are formed along edges of the opening  31   a  of the FPC substrate  31 , that is, along the outside of both edges of the slider adhesion tongue  21   b.  Bonding pads  33   a  and  33   d  are formed on front tips of the lead patterns  32   a  and  32   d.  The lead patterns  32   a  and  32   d  and the bonding pads  33   a  and  33   d  are formed on the flexure  21  by laminating the resin base and the lead.  
         [0029]     Four spacer projections  22   a ,  22   b ,  22   c , and  22   d  are provided on the slider adhesion tongue  21   b  of the flexure  21  to adhesively fix the slider  11  thereon. The four spacer projections  22   a  to  22   d  are separately provided in a radial direction with respect to a plane center position  15   c  on which the center of the rear surface (to be contacted) of the slider  11  is superimposed, when the slider  11  is adhesively fixed. The spacer projections  22   a  to  22   d  are formed of, for example, polyimide resin, in a flat shape, and are adhered onto the slider adhesion tongue  21   b.  The surfaces of the bonding pads  33   a  to  33   d  are positioned at the same height (same face), and the surfaces of the spacer projections  22   a  to  22   c  are positioned at the same height as well.  
         [0030]     The slider  11  is formed of alumina-titanium carbide, or ceramic materials, such as Si (silicon), and an air groove and an ABS surface (not shown) are formed on a surface  12  facing a recording medium. A surface opposite to the recording medium facing surface  12  of the slider  11  is a surface to contact.  
         [0031]     A trailing end surface B of the slider  11  is provided with a film magnetic element  13 , and four electrodes  14   a  to  14   d  connected to the film magnetic element  13 . The film magnetic element  13  is formed by laminating permalloy (Ni—Fe alloys) of a magnetic material and alumina of an insulating material. The film magnetic element  13  includes either of a magnetic detecting part which reproduces magnetic recording signals recorded in a magnetic disk and a magnetic recording part which records magnetic signals in the magnetic disk, or both of the magnetic detecting part and the magnetic recording part. The magnetic detecting part is a GMR head formed by, for example, a giant magnetoresistance effect element (GMR element). The magnetic recording part is formed by an inductive head in which coils and cores are formed in a pattern. These magnetic recording part and magnetic detecting part are connected to the corresponding electrodes  14   a  to  14   d.  In this way, these electrodes  14   a  to  14   d  are connected to the bonding pads  33   a  to  33   d  by ball bonding with a gold ball, etc.  
         [0032]      FIG. 2  illustrates the distribution of adhesive resin  24  on the slider adhesion tongue  21  onto which the slider  11  is adhered. In the first embodiment, a region for contact ranges from a space at the center position  15   c  side of the spacer projections  22   a  to  22   d  to radial ends of the spacer projections  22   a  to  22   d.    
         [0033]     In the first embodiment, the slider  11  is adhesively fixed on the flexure  21  as follows. The adhesive resin  24  is dropped on a region around the center position  15   c , applied and filled in the region. Then, after the surface of the slider  11  for contact is pressed against the spacer projections  22   a  to  22   d,  the electrodes  14   a  to  14   d  of the slider  11  are connected the respective bonding pads  33   a  to  33   d  by ball bonding with a gold ball. As the slider  11  is pressed against the spacer projections  22   a  to  22   d,  the adhesive resin  24  evenly and radially spreads along the contacted surfaces between the spacer projections  22   a  to  22   d  and the slider  11 . Then, ultraviolet radiation irradiates an interval between the slider  11  and the flexure  21  to cure the adhesive resin  24 .  
         [0034]     According to the first embodiment, the adhesive resin  24  that is dropped on the vicinity of the center position  15   c,  applied and filled in the vicinity evenly spreads along the spacer projections  22   a  to  22   d  in a radial direction, as the slider  11  is pressed. Moreover, when ultraviolet radiation irradiates the spread adhesive resin  24  in a direction from edges to the center position  15 c, the ultraviolet radiation can evenly irradiate the adhesive resin  24 , so that the adhesive resin  24  can be evenly cured. Accordingly, the slider  11  is adhesively fixed on the flexure  21  while reliably maintaining the position and direction of the slider  11 . The position and direction of the slider  11  is maintained even after the adhesive resin  24  is cured.  
         [0035]     Even though a UV hole is not provided in the first embodiment, according to a second embodiment shown in  FIG. 3 , a UV hole  25   a  may be formed in a region between the spacer projections  22   a  and  22   b , and the trailing end surface B (bonding pads  33   a  to  33   d ) of the slider  11 , and a UV hole  25   b  may be formed in a region between the spacer projections  22   a  and  22   b , and a leading end surface A of the slider  11 . In these regions, since the interval between the slider  11  and the flexure  21  is narrowed by the FPC  31 , the UV holes  25   a  and  25   b  are provided such that ultraviolet radiation irradiates the adhesive resin  24  through these UV holes  25   a  and  25   b,  which makes it possible to more evenly cure the adhesive resin  24 . More particularly, providing the UV hole  25   a  in a region at the trailing end surface B is available because the electrodes  14   a  to  14   d  are closely connected to the bonding pads  33   a  to  33   d  by ball bonding.  
         [0036]      FIGS. 4 and 5  illustrate third and fourth embodiments of the invention. In the third and fourth embodiments, a spacer projection connecting part  22   e  connects the center position  15   c  side ends of the spacer projections  22   a  and  22   b  at the trailing end surface B so as to make continuous the spacer projections  22   a  and  22   b , and a spacer projection connecting part  22   f  connects the center position  15   c  side ends of the spacer projections  22   c  and  22   d  at the leading end surface A so as to make continuous the spacer projections  22   c  and  22   d.  The spacer projection connecting parts  22   e  and  22   f  are formed at an interval so as to be extended parallel to the leading end surface A and the trailing end surface B of the slider  11 .  
         [0037]     According to the third and fourth embodiments, the adhesive resin  24 , being applied and filled with respect to the interval between the spacer projections  22   e  to  22   f,  evenly spreads along the contacted surfaces of the spacer projections  22   a  to  22   d  and the slider  11  from the surface of the spacer projection connecting parts  22   e  and  22   f.    
         [0038]     In the fourth embodiment shown in  FIG. 5 , the UV hole  25   a  is formed in a position closer to the bonding pads  33   a  to  33   d  than the spacer projections  22   a ,  22   e  and  22   b  on the trailing end surface B, and the UV hole  25   b  is formed in a position closer to the leading end surface A than the spacer projections  22   c ,  22   f  and  22   d  on the leading end surface A. When ultraviolet radiation irradiates the spacer projections, since the ultraviolet radiation enters through the UV holes  25   a  and  25   b,  the adhesive resin  24  in the vicinity of the holes can be reliably cured.  
         [0039]      FIG. 6  illustrates a fifth embodiment. In the fifth embodiment, eight spacer projections  27   a  to  27   h  are radially provided with respect to the center position  15   c.  According to the fifth embodiment, the spacer projections  27   a ,  27   c ,  27   e  and  27   g  are extended in a direction overlapping a diagonal line of the surface  15  for contact of the slider  11 , the spacer projections  27   b  and  27   f  are extended in a direction overlapping the center line in the longitudinal direction (passes through the center position  15   c  and orthogonal to the trailing end surface B and the leading end surface A) of the slider  11  that passes through the center position  15   c , and the spacer projections  27   d  and  27   h  are extended in a direction overlapping the center line in the vertical direction (passes through the center position  15   c  and parallel to the trailing end surface B and the leading end surface A) of the slider  11  that passes through the center position  15   c.    
         [0040]     The adhesive resin  24  is applied on a central region surrounded by the center side ends of the spacer projections  27   a  to  27   h,  or center side regions of the spacer projections  27   a  to  27   h.  In this case, the adhesive resin  24  evenly spreads along the respective spacer projections  27   a  to  27   h  in a radial direction from the center. Since the length of the respective spacer projections  27   a  to  27   h  is shorter than that of the spacer projections  22   a  to  22   d  in the first embodiment, it is possible to ensure even thickness of the adhesive resin that is applied on the center side region and the outside region of the spacer projections  27   a  to  27   h,  and to allow the adhesive resin to evenly spread.  
         [0041]     In addition, the application of the invention is not limited to the embodiments. The application of the invention may be modified such that the spacer projections  27   a  to  27   h  are radially provided at uniform intervals and angles with respect to the center. Further, even though the number of the spacer projections is 4 and 8, the number is not limited to 4 and 8.  
         [0042]     Further, even though the number of the center position is one, it can be two or more. For example, the center position may be provided at two spots that are uniformly separated from the center position and passes through the center line in the longitudinal direction, or the center position may be provided at two spots that are uniformly separated from the center position and passes through the center line in the latitudinal direction.