Abstract:
Manufacturing method of a magnetic head slider comprising a ferrite core having read/write gap and a housing of non-magnetic material having a rail on a surface opposite to a magnetic recording medium, the ferrite core and the housing being bonded to each other, a core bond bar constituted by continuation of two or more cores and a stick for the housing are bonded to each other and fine machining is applied thereto, and then the magnetic head slider is separated into individual sliders.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a manufacturing method of a side core type magnetic head slider used in manufacturing a magnetic head slider of a magnetic recording apparatus such as a hard disk drives and a floppy disk drives to be used as an auxiliary storage device of a computer.  
           [0003]    2. Description of the Prior Art  
           [0004]    In a magnetic head slider used in a magnetic recording apparatus at present, with improvement of the recording density, since more information content must be recorded per unit volume and in order to improve the data transfer rate and to prevent damage of the head due to contact or collision to a medium, request for further light weight and further miniaturization has been intensified. Among these circumstances, a magnetic head used in the field of magnetic recording is broadly classified into two groups, mainly a thin-film head and a ferrite head. In the ferrite head as shown in FIG. 13, a slider comprises a housing  23  made of ceramics such as calcium titanate (CaTiO3), zirconia (ZrO2), non-magnetic ferrite or the like, and a ferrite core  13  being a magnetic material, and it is manufactured mainly by the machine work and the high-temperature glass bonding.  
           [0005]    After completed as a slider, a coil for reading/writing signals by action of electromagnetic induction is wound to a leg of a core part and is bonded to prescribed position of a support spring (not shown) having flexibility. As above described, request for miniaturization is strong in a magnetic head slider. In nano mater size slider (also called 50% size slider) in FIG. 13( a ) mainly used at present in hard disk drive, dimension in thickness direction of the slider is 0.432 mm, and in pico mater size slider (also called 30% size slider) in FIG. 13( b ) expected to increase from now, the dimension is 0.305 mm and apt to become further thin. With this tendency, dimension of the core part becomes small, and thickness of the core in the nano mater size slider is 0.050˜0.100 mm and dimension in width direction is less than 0.8 mm. Further a magnet wire of diameter 0.020 mm˜0.025 mm is wound in several tens turns by hand to a leg  21  of the small core part. In the prior art, such fine component parts are subjected to the machine work and the processing work by hand in each single part, and during the work, reduction of the man-hour number in the work and improvement of the yield factor have been intended.  
           [0006]    In a head manufacturing process, when its component parts become small, grasping of parts may fail or parts may be lost during handling or there is a problem of breakage due to lack of strength. Also as shown in FIG. 14, since each of component parts is treated in single part as a core or a slider, dispersion of the positioning accuracy of respective parts affects the machining accuracy and inhibits the quality stabilization.  
           [0007]    In order to eliminate the above-mentioned disadvantages in the prior art, an object of the present invention is to provide a method of manufacturing a side core type magnetic head slider where the yield factor is good and the machining accuracy is high.  
         SUMMARY OF THE INVENTION  
         [0008]    In order to attain the foregoing object, the present invention provide following manufacturing method. That is, in a magnetic head slider comprising a ferrite core having read/write gap and a housing of non-magnetic material having a rail on a surface opposite to a magnetic recording medium, the ferrite core and the housing being bonded to each other, a core bond bar constituted by continuation of two or more cores and a stick for the housing are bonded to each other and fine machining is applied thereto, and then the magnetic head slider is separated into individual sliders. At bonding portion of the housing and the ferrite core, the housing has a notch with depth and width equivalent to the track width or the core thickness of the ferrite core, and also the housing is previously provided with a wiring groove at the side surface on which the ferrite core is mounted. After the ferrite core is bonded to the housing, the tapering work is applied at prescribed angle to the side surface of the surface opposite to the medium, and during the grinding work from the rail surface, the angle of the tapering work is adjusted so that when the track width is ground until prescribed dimension, also the throat height becomes prescribed dimension simultaneously.  
           [0009]    At the initial process in the manufacturing, component parts are not treated in each single body and the bonding and the machine work are applied to shape of a bond bar and a stick in size to be easily handled. The component parts are separated into individual parts at step near the final process thereby improvement of the machining accuracy, reduction of the man-hour number due to machining easiness and improvement of the yield factor are dealt with.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a diagram of ferrite substrate for making core.  
         [0011]    [0011]FIG. 2 is a diagram showing state that grooves for coil wiring are provided on the opposite surfaces of the respective substrates and an apex being datum in depth direction of the read/write gap is formed.  
         [0012]    [0012]FIG. 3 is a diagram showing state that metal film and glass film are spattered to the substrate.  
         [0013]    [0013]FIG. 4 is a diagram showing state that opposite surfaces of the substrates abut on each other and are positioned, and the apex part is filled with glass for reinforcement called secondary glass, and the sputtered glass film and the glass for reinforcement as above described are melted by the curing within the electric furnace, and the glass is grasped at the abutting surface between the I bar and the C bar of the ferrite core thereby the gap is constituted and the bonding is performed in the state that the gap length of the prescribed length is formed.  
         [0014]    [0014]FIG. 5 is a diagram showing directions for cutting on the substrate for forming core bond bar.  
         [0015]    [0015]FIG. 6( a ) is a diagram showing core bond bar made by cutting.  
         [0016]    [0016]FIG. 6( b ) is a diagram showing an embodiment where a groove having depth and width equivalent to the track width or the core thickness of the ferrite core is machined to a housing of stick shape having prescribed dimension.  
         [0017]    [0017]FIG. 7 is a diagram showing state that the core bond bar shown in FIG. 6( a ) is bonded to the housing shown in FIG. 6( b ).  
         [0018]    [0018]FIG. 8 is a diagram showing state that a taper groove is machined to a prescribed position on the outside surface of the bonded core bond bar.  
         [0019]    [0019]FIG. 9 is a diagram showing a cutting position of the thickness direction of the slider and the housing.  
         [0020]    [0020]FIG. 10 is a diagram showing a stick shaped housing after cut.  
         [0021]    [0021]FIG. 11 is a diagram showing a cutting position making for a slider.  
         [0022]    [0022]FIG. 12 is a diagram showing a slider.  
         [0023]    [0023]FIG. 13 is a diagram showing a comparison nano mater size slider with pico mater size slider.  
         [0024]    [0024]FIG. 14 is a diagram showing a prior art slider.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    The first embodiment of the present invention will be described as follows by reference to explanatory views.  
         [0026]    A ferrite core is constituted by two parts, so-called I bar and C bar (also called U bar), so as to form read/write gap of sub micron order. FIG. 1 shows the substrate state of the two parts respectively. FIG. 2 is a diagram showing state that grooves  3  for coil wiring are provided on the opposite surfaces of the respective substrates and an apex (FIG. 12: reference numeral  22 ) being datum in depth direction of the read/write gap is formed.  
         [0027]    The groove providing and formation of the apex result in that the I bar and the C bar are made a pair and machined in the grinding work simultaneously on the same jig thereby deviation of the pitch distance generated due to abrasion, vibration or the like of the grindstone during grinding can be canceled and the deviation accuracy of glass bond hereinafter described can be improved. After the groove providing and formation of the apex, as shown in FIG. 3, in order to generate the strong magnetic field in the read/write gap, a metal thin-film  4  made of iron and a glass film  5  of non-magnetic material to form the gap length are formed each other by the sputtering method. And then as shown in FIG. 4, the opposite surfaces abut on each other and are positioned, and the apex part is filled with glass for reinforcement (not shown) called secondary glass, and the sputtered glass film  5  and the glass for reinforcement as above described are melted by the curing within the electric furnace, and the glass is grasped at the abutting surface between the I bar and the C bar of the ferrite core thereby the gap is constituted and the bonding is performed in the state that the gap length of the prescribed length is formed.  
         [0028]    Next as shown in FIG. 5, the substrate being glass-bonded is cut into block shape, and machined into a bond bare shown in FIG. 6( a ) having the thickness dimension in the state becoming single body of the ferrite core. In the prior art, the cutting is not performed in the thickness direction of the ferrite core, but such system is adopted that the ferrite core is cut in the overall height direction in the state becoming single body of the core and is separated into the bond bar and further cut into the single body of the core. In the present invention, the ferrite core cut into block shape is called a core bond bar  7  and the handling becomes easy.  
         [0029]    [0029]FIG. 6( b ) shows an embodiment where a groove  9  having depth and width equivalent to the track width or the core thickness of the ferrite core is machined to a housing of stick shape having prescribed dimension. In order to form the groove, the machine work using a grindstone, the ion milling work, the laser machining, the etching machining by chemicals and the like are used. Also using the thin film technology, film of SiO2 or DLC (diamond-like carbon) with high hardness may be sputtered and uneven surface may be provided.  
         [0030]    Also as shown in the drawings, the housing is provided at the bonding surface to the ferrite core with a wiring window  10  being a groove through which a wiring passes when a coil is wound on a leg part of a core.  
         [0031]    [0031]FIG. 7 is a diagram showing state that the core bond bar  7  shown in FIG. 6( a ) is bonded to the housing  8  shown in FIG. 6( b ) as above described. The bonding method is in that glass of low melting point is previously sputtered in thickness of 3000 Å˜5000 Åon the bonding surface of the housing  8  and the core bond bar  7  is arranged, and then using the glass bond method, the glass is melted and fixed. In FIG. 8, a taper groove  11  is machined at angle of 30 degrees˜45 degrees to a prescribed position on the outside surface of the bonded core bond bar  7  thereby in the process of lap machining of a rail surface as hereinafter described, when the grinding is performed until the track width attains to the definite dimension, the important machining of constituting the read/write gap is performed where also throat height becomes prescribed dimension simultaneously.  
         [0032]    Next, after the taper groove is machined, as shown in FIG. 9, cutting work is performed at position of  12  so as to cut out the thickness direction of the slider and the housing in stick shape is formed as shown in FIG. 10. And then as shown in FIG. 11, a rail  14  is machined on the surface of the housing of stick shape at the side of the ferrite core with the taper groove, and the individual slider as shown in FIG. 12 is formed by cutting work  15 . As shown in FIG. 13, the rail surface  14  is machined in grinding work so that track width  24  and throat height  22  become definite dimension. After an air inlet end  19  and an air outlet end  20  of the surface opposite to the magnetic recording medium are machined, chamfering work of the slider rail surface to suppress the friction with the medium is performed.  
         [0033]    In such constitution, handling becomes easy during the machining process, and breakage or loss of parts during the work and dispersion of the positioning accuracy can be reduced and the machining accuracy is improved.  
         [0034]    At the completed state of a slider, a track part formed on a ferrite core bonded to the side surface of a housing being vertical to a rail surface opposite to a magnetic recording medium and parallel to traveling direction of the medium is arranged without being bulged from the end surface of the housing and is not liable to the outer damage due to the handling miss. Also since the track part is bonded within a groove of the housing, the position accuracy is improved, and since the datum for the arrangement becomes clear, the workableness is improved.  
         [0035]    While a coil is wound to a leg part of a ferrite core, grooves through which a wiring passes can be machined with accuracy in bulk together resulting in improvement of the production efficiency. When grinding is performed until track width of read/write gap of a ferrite core provided on the side surface of the slider attains to arbitrary definite dimension, since also throat height becomes arbitrary dimension simultaneously, individual process for the dimension adjustment is not required and the process is simplified therefore the man-hour number can be reduced. Also since the simplification of the process results in decrease of times of the handling, the handling miss is inevitably decreased and the yield factor is improved.