Abstract:
A method of fabricating a magnetic head device comprising a slider having a magnetic head element, a suspension structure made of a thin resilient material and having one end supporting the slider and the other end to be attached to another member, and a head IC chip. The head IC chip is mounted on the suspension structure so as to face a magnetic recording disc and at a position spaced from the slider-supporting one end of the suspension structure by an intervening portion of the suspension structure. The position is selected so that the intervening portion is effective to suppress a temperature increase in the head IC chip due to at least thermal conduction through the intervening portion.

Description:
PRIORITY CLAIM AND RELATED APPLICATIONS 
   This is a Divisional of application Ser. No. 09/033,789 filed on Mar. 3, 1998 and now issued as U.S. Pat. No. 6,084,746. 

   FIELD OF THE INVENTION 
   The present invention relates to a magnetic head device including a slider having a magnetic head mounted thereon, a resilient suspension structure carrying the slider and a head IC chip. The present invention further pertains to a magnetic disc device provided with such magnetic head device. 
   PRIOR ART 
   In conventional magnetic head devices having a magnetic head for writing and/or reading information on a magnetic recording medium such as a magnetic disc, it has been common to mount the magnetic head on a slider which is maintained in a floating relationship with respect to the magnetic recording medium. The slider is generally formed from a resilient metallic material sheet which is arranged to extend from a movable arm structure and supported by a suspension member. 
   The movable arm is provided for supporting one end of the suspension member and it has been common to mount a head IC chip on the movable arm. The head IC is provided for including electronic circuits for amplifying writing current which is to be suppled to the magnetic head and reading voltage from the magnetic head, and for controlling the writing and/or reading operation. In an arrangement wherein the head IC chip is mounted on the movable arm, an increased length of connecting lead is required between the head IC chip and the magnetic head and this increased length of the connecting lead may be a cause of noise generation. Such increased length of the connecting lead may produce a parasitic capacitance and an inductance which have an effect of undesirably increasing rising time and falling time of pulse signals. Thus, high speed data transmission will be disturbed. 
   In order to solve the problems, there has been proposed by the Japanese Laid-Open Patent Publication No. Sho 53-69623 to mount the head IC chip on the slider. Further, the Japanese Laid-Open Patent Publication No. Hei 3-108120 proposes to divide the head IC into an IC main body and an IC sub-body, and mount the IC main body on the movable arm supporting the suspension member and the IC sub-body on the slider or the suspension member. 
   In these known structures, it is possible to decrease to a certain extent the distance between the head IC chip and the magnetic head so that it may be possible to suppress noise which may otherwise be produced because of the length of the connecting lead. However, the structure has another unsolved problem in that the temperature of the IC chip is increased due to the writing current which flows through the head IC chip during recording operation. It should further be noted that in the structure the IC chip is located close to the magnetic head so that the magnetic head may receive an adverse thermal effect from the head IC chip which generally generates heat in operation. 
   More specifically, in a structure where the head IC chip is mounted on the movable arm which has a sufficient thermal capacity as well as a substantial area for heat radiation, the temperature of the IC chip can be maintained sufficiently low. Further, since the head IC chip is located far from the magnetic head, there is least possibility that the magnetic head is adversely affected by the heat generated in the head IC chip. To the contrary, where the head IC chip is located on the slider, it is difficult to ensure sufficient surface area for heat dissipation so that it cannot be expected to have the temperature of the IC chip decreased through dissipation of heat. It should further be noted that the slider usually has a limited thermal capacity so that it cannot be an effective tool for providing a temperature decrease through thermal conduction. As a result, there will be a possibility in the aforementioned structures that the temperature of the head IC chip is undesirably increased to an extent that the reliability of the IC chip will be lowered. It should further be noted that since the magnetic head is located close to the head IC chip, the magnetic head is thermally affected by the heat generated in the head IC chip. Thus, the temperature of the magnetic head itself may increase to an unacceptable level. A similar problem will also be encountered in a structure where the head IC chip is located on the suspension member if the location of the head IC chip is close to a tip end of the suspension member. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a technique wherein the temperature increase in the head IC chip in a magnetic head device of the type as described above can be suppressed to a satisfactory level and the heat generated in the head IC chip is effectively prevented from being transmitted to the magnetic head. 
   This and other objects are attained in accordance with one aspect of the present invention directed to a method of fabricating a magnetic head device comprising a slider having a magnetic head element, a suspension structure made of a thin resilient material and having one end supporting the slider and the other end to be attached to another member, and a head IC chip. The head IC chip is mounted on the suspension structure so as to face a magnetic recording disc and at a position spaced from the slider-supporting one end of the suspension structure by an intervening portion of the suspension structure. The position is selected so that the intervening portion is effective to suppress a temperature increase in the head IC chip due to at least thermal conduction through the intervening portion. 
   Another aspect of the present invention is directed to a method of increasing cooling of a head IC chip in the above-described magnetic head device. The head IC chip is mounted on the suspension structure so as to face a magnetic recording disc and at a position spaced from the slider-supporting one end of the suspension structure by an intervening portion of the suspension structure. The position is selected so that the intervening portion is effective to suppress a temperature increase in the head IC chip due to at least thermal conduction through the intervening portion. 
   Another aspect of the present invention is directed to a method of increasing cooling of a head IC chip in the above-described magnetic head device. The head IC chip is mounted on the suspension structure so as to face a magnetic recording disc and at a position spaced from the slider-supporting one end of the suspension structure. The slider is mounted on the slider-supporting one end of the suspension structure so as to face a magnetic recording disc. The head IC chip position is defined by,
 
0.2 ≦Lb/La≦ 1 
 
where La is a distance between the slider and a point of attachment of the suspension structure to said other member, and Lb is a distance between the slider and the head IC chip.
 
   Another aspect of the present invention is directed to a method of fabricating a magnetic disc device comprising a magnetic head device including a slider having a magnetic head element and a suspension structure having one end supporting the slider, a rotatable magnetic disc, a head IC chip which is a separately-formed component from the slider, and an electrically conductive connecting device for establishing an electrical connection between the magnetic head element and the head IC chip. The head IC chip is mounted on the connecting device so as to face the magnetic disc which is rotated at least when the head IC chip is in operation. The mounting position of the head IC chip on the connecting device is selected to be where the head IC chip is always exposed to a flow of air produced by rotations of the magnetic disc so that the head IC chip is continuously cooled by the flow of air at least when the head IC chip is in operation. 
   Another aspect of the present invention is directed to a method of increasing cooling of a head IC chip in a magnetic disc device comprising a magnetic head device including a slider having a magnetic head element and a suspension structure having one end supporting the slider, a rotatable magnetic disc, a head IC chip which is a separately-formed component from the slider, and an electrically conductive connecting device for establishing an electrical connection between the magnetic head element and the head IC chip. The head IC chip is mounted on the connecting device so as to face the magnetic disc which is rotated at least when the head IC chip is in operation. The mounting position of the head IC chip on the connecting device is selected to be where the head IC chip is always exposed to a flow of air produced by rotations of the magnetic disc so that the head IC chip is continuously cooled by the flow of air at least when the head IC chip is in operation. 
   Another aspect of the present invention is directed to a method of fabricating a magnetic disc device comprising a magnetic head device including a slider having a magnetic head element and a suspension structure having one end supporting the slider, a rotatable magnetic disc, a head IC chip which is a separately-formed component from the slider, and an electrically conductive connecting device for establishing an electrical connection between the magnetic head element and the head IC chip. The head IC chip is mounted on the connecting device so as to face the magnetic disc which is rotated at least when the head IC chip is in operation. A position of the suspension structure is controlled so that the head IC chip is located inside an outer periphery of the magnetic disc at least when the head IC chip is in operation. 
   Another aspect of the present invention is directed to a method of increasing cooling of a head IC chip in a magnetic disc device comprising a magnetic head device including a slider having a magnetic head element and a suspension structure having one end supporting the slider, a rotatable magnetic disc, a head IC chip which is a separately-formed component from the slider, and an electrically conductive connecting device for establishing an electrical connection between the magnetic head element and the head IC chip. The head IC chip is mounted on the connecting device so as to face the magnetic disc which is rotated at least when the head IC chip is in operation. A position of the suspension structure is controlled so that the head IC chip is located inside an outer periphery of the magnetic disc at least when the head IC chip is in operation. 
   Another aspect of the present invention is directed to a method of fabricating a magnetic disc device comprising a magnetic head device including a slider having a magnetic head element and a suspension structure having one end supporting the slider, a rotatable magnetic disc, a head IC chip which is a separately-formed component from the slider, and an electrically conductive connecting device for establishing an electrical connection between the magnetic head element and the head IC chip. The head IC chip is mounted on the connecting device so as to face the magnetic disc which is rotated at least when the head IC chip is in operation. The mounting position of the head IC chip on the connecting device is selected to be where the head IC chip is always exposed to a flow of air produced by rotations of the magnetic disc so that the head IC chip is continuously cooled by the flow of air at least when the head IC chip is in operation. The head IC chip is arranged to be located with respect to the magnetic disc with a distance between opposing surfaces of the head IC ship and the magnetic disc smaller than 1000 μm. 
   Another aspect of the present invention is directed to a method of increasing cooling of a head IC chip in a magnetic disc device comprising a magnetic head device including a slider having a magnetic head element and a suspension structure having one end supporting the slider, a rotatable magnetic disc, a head IC chip which is a separately-formed component from the slider, and an electrically conductive connecting device for establishing an electrical connection between the magnetic head element and the head IC chip. The head IC chip is mounted on the connecting device so as to face the magnetic disc which is rotated at least when the head IC chip is in operation. The mounting position of the head IC chip on the connecting device is selected to be where the head IC chip is always exposed to a flow of air produced by rotations of the magnetic disc so that the head IC chip is continuously cooled by the flow of air at least when the head IC chip is in operation. The head IC chip is arranged to be located with respect to the magnetic disc with a distance between opposing surfaces of the head IC chip and the magnetic disc smaller than 1000 μm. 
   The magnetic head device includes a slider having a magnetic head thereon, a suspension structure formed from a resilient metallic sheet and having one end supporting the slider, and a head IC chip, the suspension structure being attached at the other end to another member such as a movable arm, the head IC chip being mounted on the suspension structure at a location defined by 0.2≦Lb/La≦1, where La is a distance between the slider and the point of connection of the slider to the aforementioned other member, and Lb is a distance between the slider and the head IC chip. 
   Where the head IC chip is mounted on the suspension structure at the side facing the magnetic recording medium, the magnetic recording medium is moved relative to the slider and the head IC chip and there is produced flow of air between the magnetic recording medium and the slider and also between the magnetic recording medium and the head IC chip. Usually, the slider and the head IC chip are held stationary and the magnetic recording medium is in the form of a rotatably driven disc. Then, flow of air is produced as the magnetic recording disc rotates in the vicinity of the surface of the disc and serves to cool off the head IC chip. As the result, the temperature of the head IC chip can be suppressed to a substantially low value. 
   In this aspect of the present invention, it is It is in the mounted state from the suspension structure is smaller than the height of the slider. In this instance, the head IC chip is preferably in the form of a bare chip which is preferably mounted or attached to the suspension structure by means of flip-chip-bonding. By adopting the flip-chip-bonding for mounting such bare chip, it is possible to decrease the height of the head IC chip in the mounted state. Therefore, with this arrangement, the IC chip can be mounted on the recording medium side of the suspension structure without having any risk of the head IC chip interfering with the magnetic recording medium in use. 
   In an arrangement wherein the suspension structure is attached at the other end to the other member such as a movable arm, it is preferable that the location of the head IC chip on the suspension structure be, in terms of La which is a distance between the slider and the point of connection of the slider to the aforementioned other member, and Lb which is a distance between the slider and the head IC chip, within a range 0.2≦Lb/La≦1, more preferably within a range 0.3≦Lb/La≦0.7, and most preferably within a range 0.4≦Lb/La≦0.6. 
   In a structure wherein the head IC chip is mounted on the suspension structure, it may be possible because of a thin structure of the suspension that heat may not be sufficiently dissipated nor conducted depending on the location of the head IC chip as described with reference to the prior art. Thus, there is a risk that the temperature of the IC chip is increased to an unacceptable level and the magnetic head may receive an adverse thermal effect from the high temperature IC chip. It has now been found that the temperature of the head IC chip is greatly increased when the IC chip is mounted on the suspension structure at a location close to its tip end. The reason for this is understood that the thermal conduction takes place substantially in one direction only so that the IC chip cannot be cooled off sufficiently. It has also been realized that the temperature of the magnetic head increases higher as the location of the IC chip becomes closer to the tip end of the suspension structure. This is because the IC chip which is considered as a heat source is located close to the magnetic head. It has also been found that, in the structure of the aforementioned prior art wherein the head IC chip is mounted on the slider, both the temperature of the IC chip itself and that of the magnetic head increase to an extremely high level. 
   It should be noted that wherein the head IC chip is mounted on the suspension structure at the side facing the magnetic recording medium and the location on the suspension structure in the range as defined, it is possible to maintain the temperature of the IC chip sufficiently below an acceptable level and to suppress the temperature of the magnetic head to a low value. 
   The suspension structure may be made of a resilient metallic material such as a corrosion resistant steel. It is preferable that the head IC chip be attached to a surface of the suspension structure through a layer of an electrically insulating material such as a resin material like polyimide. 
   The suspension structure can comprise a load beam formed from resilient metallic material such as a corrosion resistant steel, and a flexure member made of a resilient metallic material such as a corrosion resistant steel having a width smaller than the load beam and provided on a side of the load beam where the head IC chip is to be attached. It is preferable that the flexure member is coated with a first layer of an insulating material such as a resin material like polyimide, and at least one conductive layer is provided on the first insulating layer to form a portion of connecting lead or leads for connection with the magnetic head and the head IC chip. It is also preferable to cover the conductive layer with a second layer of an insulating material such as a resin material like polyimide. In this instance, it is preferable to locate the head IC chip on the second insulating layer and connected with the conducive layer by soldering. 
   Where the head IC chip is mounted on the suspension structure at the side facing to the magnetic recording medium, it is preferable that the surface of the head IC chip facing to the magnetic recording medium has such a configuration that a substantial heat dissipating area can be ensured. More specifically, the head IC chip may have a wide and flat surface at the side facing the magnetic recording medium. Alternatively, the head IC chip may have a rough surface at the side facing the magnetic recording medium or an undulated surface as well. In a still alternative structure, the head IC chip may be formed at the side facing to the magnetic recording medium with one or more grooves for allowing flow of air to pass through. The groove or each of the grooves may have a width which is large at an end opposite to the direction of movement of the magnetic recording medium with respect to the head IC chip and gradually decreasing toward the direction of the movement of the medium. 
   It is preferred that the head IC chip has a mass less than 1.0 mg so that the head IC chip may not have any adverse effect on the mechanical vibration characteristics of the suspension structure when the chip is mounted on the suspension structure. 
   It is further preferable in the magnetic head device and the magnetic disc device having a magnetic recording disc located to be opposed to the magnetic head of the magnetic head device that the spacing between mutually facing surfaces of the head IC chip and the magnetic disc is maintained to be less than 1000 μm. It has been found that with this arrangement, the cooling effect of air flow can be enhanced and the temperature of the head IC chip can always be maintained below 150° C. 
   It is further contemplated that there is provided a magnetic disc device comprising a magnetic head device and a rotatable magnetic recording disc. The magnetic head device includes a slider having a magnetic head thereon and a suspension structure having one end supporting the slider. The magnetic head is arranged so that it is faced to the magnetic head of the magnetic head device. There are provided a head IC chip and at least one connecting lead member for connecting the magnetic head with the head IC chip. The head IC chip is mounted on the connecting lead member at a location where the head IC chip is always exposed to flow of air which is produced by a rotation of the magnetic recording disc. 
   According to the arrangement wherein the head IC chip is mounted on the connecting lead member at a location where the head IC chip is always exposed to flow of air which is produced by a rotation of the magnetic recording disc, the head IC chip is always exposed to a cooling air flow throughout the stroke of the movement of the magnetic head between the inner and outer peripheries of the recording area of the magnetic recording disc so that the temperature increase in the IC chip can be substantially suppressed. 
   It is preferred that in the aforementioned arrangement the head IC chip is located radially inside the outer periphery of the magnetic recording disc and is opposed to the disc. It is also preferable in order to enhance the cooling effect by the air flow that the distance between the opposing surfaces of the head IC chip and the rotating magnetic recording medium is maintained to be less than 1000 μm. It is possible with this arrangement to suppress the temperature of the head well below 150° C. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing essential portion of the magnetic disc device having a magnetic head device in accordance with one embodiment of the present invention; 
       FIG. 2  is a side view showing a carriage arrangement adopted in the embodiment shown in  FIG. 1 ; 
       FIG. 3  is a plan view showing an example of the magnetic head device in the embodiment of  FIG. 1  as seen from a side of the magnetic recording disc; 
       FIG. 4  is a sectional view taken substantially along the line A—A in  FIG. 3 ; 
       FIG. 5  is a sectional view taken substantially along the line B—B in  FIG. 3 ; 
       FIG. 6  is a diagram showing the temperature change in the IC chip in relation to the writing current; 
       FIG. 7  is a diagram showing the temperature change in the suspension structure at the side opposite to the IC chip in relation to the writing current; 
       FIG. 8  is a diagram showing the temperature change in the slider in relation to the writing current; 
       FIG. 9  is a diagrammatical illustration designating the distance D between opposing surfaces of the head IC chip and the magnetic recording disc in the embodiment of  FIG. 1 ; 
       FIG. 10  is a diagram showing the temperature change in the head IC chip in reflation to the distance between the opposing surfaces of the IC chip and the magnetic recording disc; 
       FIG. 11  is a diagram showing the relationship between the location of the head IC chip and the temperature of the head IC chip in operation; 
       FIG. 12  is a diagram showing the relationship between the location of the head IC chip and the temperature of the slider during operation; 
       FIG. 13  shows various possible configurations of the head IC chip; 
       FIG. 14  is a side view of the structure around the carriage assembly; and, 
       FIG. 15  is a diagrammatical illustration similar to  FIG. 9  but showing another example of the distance D. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, particularly to FIG.  1 , there is shown in a perspective view a magnetic disc device using a magnetic head device in accordance with one embodiment of the present invention.  FIG. 2  shows a carriage assembly used in the magnetic disc device shown in FIG.  1 . 
   In the arrangement shown in the drawings, it will be understood that a plurality of magnetic recording discs  10  are provided for rotation about an axis of a shaft  11 . The magnetic recording discs  10  are rotated by a mechanism which is well known in the art. Adjacent to the magnetic recording discs  10 , there is provided a carriage assembly  12  for locating sliders with respect to the discs  10 . Each of the sliders has a magnetic head mounted thereon. The carriage assembly  12  primarily comprises a carriage  14  which is rotatable about a shaft  13  and an actuator  15  such as a voice coil motor (VCM) for rotationally driving the carriage  14 . 
   The carriage  14  supports a plurality of movable arms  16  which are stacked one over the other along the shaft  13  and attached to the carriage  14  at the base ends thereof. Each of the movable arms  16  has one or two magnetic head devices  17  mounted on tip ends of the movable arms  16 . Each of the magnetic head devices  17  is structured in the form of a head suspension assembly including a suspension structure  18  carrying at its tip end a slider  19  having a magnetic head and at its intermediate portion a head IC chip  20 . Both of the slider  19  and the head IC chip  20  are mounted on the suspension structure  18  at a side facing one of the recording surfaces of a respective one of the magnetic recording discs  10  so that they are opposed to the one recording surface of the disc  10 . 
   There is provided a connecting lead cable comprising a flexible print cord (FPC)  21  which is connected with an internal circuit (not shown) in the magnetic disc device. The connecting lead cable has a tip end which is divided into a plurality of end portions extending to tip ends of the respective ones of the movable arms  16  in the carriage  14 . 
     FIG. 3  is a plan view showing the magnetic head device  17  of the embodiment of  FIG. 1  as seen from the side facing the magnetic disc  10 .  FIG. 4  is a sectional view in an enlarged scale taken along the line A—A in FIG.  3 .  FIG. 5  is a sectional view taken along the line B—B in FIG.  3 . 
   As shown in  FIG. 3 , the suspension structure  18  includes a load beam  31  and a flexure member  30  secured to the load beam at one side thereof. The flexure member  30  has one end carrying the slider  19  and supports the head IC chip  20  on its intermediate portion. The load beam  31  has a base plate  32  which is formed at a root end portion of the load beam  31 . 
   In the illustrated embodiment, the flexure member  30  is made of a sheet of a corrosion resistant steel (for example, SUS304TA) of approximately 25 μm thick. The flexure member  30  is smaller in width than the load beam  31 . To provide the flexure member  30  with a corrosion resistant steel sheet as described is advantageous as compared with a structure wherein the flexure member is totally made of plastics material. Where the flexure member is totally made of plastics material, flatness of the slider attachment surface may very often not be satisfactory, and the slider attachment surface may be accurately parallel with the movable arm attachment surface. By providing the flexure member  30  with a corrosion resistant steel as described, the aforementioned problems can be avoided. 
   On the flexure member  30 , there is formed a pattern of thin film electrically conductive layer  33  providing a required number of connecting leads which extend along the length of the flexure member  30 . The connecting leads of the conductive layer  33  have ends adjacent to the base plate  32  connected with connecting terminals  34  which are in turn connected with respective ones of connecting leads formed in the flexible print cord  21  constituting the connecting cable. The other ends of the connecting leads in the conductive layer  33  are connected with connecting terminals  35  provided on the tip portion of the flexure member  39 . 
   The thin film pattern can be formed by means of a known patterning process which is generally adopted in providing a print board on a metallic plate. More specifically, as shown in  FIGS. 4 and 5 , the flexure member  30  is covered by a first layer  36  of an electrical insulation material such as a resin material like polyimide. The first layer may be approximately 5 μm thick. On the first layer  36 , there is formed a patterned layer  33  of an electrically conductive material such as copper, which is covered by a second layer  37  of an electrical insulation material such as a resin like polyimide. The second layer  37  may be 5 μm thick. These layers can be formed in this order on the flexure member  30  by a laminating technique. The connecting terminals  34  and  35  may be formed by laminating layers of nickel or gold on the layers of copper. The connecting terminals are not covered by the second insulation layer  37 . In  FIG. 3 , the conductive layer  33  is shown by solid lines for clarity although it is covered by the second insulation layer  37 . 
   The load beam  31  is made of a corrosion resistant steel sheet having a thickness of approximately 70 to 75 μm and is configured to have a width gradually decreasing from the end adjacent to the base plate to the tip. The load beam  31  supports the flexure member  30  throughout its length. The flexure member  30  is connected to the load beam  31  through a plurality of welding points. 
   The base plate  32  is made of a corrosion resistant steel or iron and secured to the base portion of the load beam by welding. The suspension structure  18  is attached to the movable arm  16  by securing the base plate  32  thereto at the attachment  38 . The base plate  32  may not necessarily be a separate part but may be made integrally with the load beam  31 . 
   The slider  19  having a magnetic head  39  is mounted on the flexure member  30 . In  FIG. 3 , it will be noted that the conductive layer  33  providing a required number of leads passes along the opposite sides of the slider  19  to the tip end of the flexure member  30  and then turned back from the tip end of the flexure member  30  to be connected with input and output electrodes provided on the slider  19 . The portion connecting the conductive layer  33  to the electrodes on the slider  19  is covered by a layer  41  of an electrical insulation material such as a resin. Although not shown in the drawings, the flexure member  30  and the load beam  31  may be dimpled at the portion where the slider  19  is to be mounted. 
   The head IC chip  20  is mounted on the suspension structure  18  at an intermediate portion of its length on the side where the slider  19  is to be mounted. In other words, the head IC chip  20  is mounted on the side of the suspension structure  18  which is opposed to the magnetic disc  10 . The head IC chip  20  is preferably in the form of a bare chip desirably having a mass of less than 1.0 mg. With this light weight structure, it is possible to suppress any undesirable mechanical vibration when the chip  20  is mounted on the suspension structure  18 . 
   As shown in detail in  FIG. 4 , the head IC chip  20  is connected by means of a flip-chip bonding using a solder  42  with the conductive layer  33  which is formed on the flexure member  30  of the suspension structure  18  through the first insulation layer  36 . The gap between the lower surface of the head IC chip  20  and the first insulation layer  36  and the second insulation layer  37  is filled with a layer  43  of an insulation material having a good thermal conductivity such as a mixture of a resin like polyimide and an electrical insulation material so that heat generated in the IC chip  20  is dissipated through conduction through the insulation layer  43  to the suspension structure  18 . 
   As already described, the head IC chip  20  is mounted on the suspension structure  18  at the side facing the magnetic disc  10  which is rotated with respect to the slider  16  and head IC chip  20  which are held stationary. Thus, flow of air produced by the rotating magnetic disc  10  in the vicinity of the surface thereof flows around the head IC chip  20  to cool the IC chip. It is therefore possible to suppress increase in temperature of the IC chip  20  to a substantial extent even when the writing current is flowing through the IC chip. As the result, it is also possible to suppress increase in temperature of the slider  19 . 
   Referring to  FIGS. 6 ,  7  and  8 , there are respectively shown the temperature change in head IC chip  20 , the temperature change in the surface of the suspension structure  18  at the location of IC chip and the temperature change of the slider  19  with respect to a change in the write current. In the drawings, the curve a designates the temperature when the write current is continuously supplied while the magnetic disc  10  is stationary, b the temperature when the write current of 50% duty factor is supplied while the magnetic disc  10  is stationary, c the temperature when the write current is continuously supplied while the magnetic disc  10  is rotated with a linear speed of 24.9 m/sec, and d the temperature when the write-in current of 50% duty factor is supplied while the magnetic disc  10  is rotated with a linear speed of 24.9 m/sec. 
   In  FIGS. 6 and 7 , it will be understood that the temperature increase in the head IC chip  20  itself and that in the chip mounting surface of the suspension structure  18  can be suppressed to a substantial degree when the magnetic disc  10  is rotated as compared with the situation wherein the magnetic disc  10  is stationary, since the head IC chip  20  is cooled by the flow of air which is produced by the rotating magnetic disc  10 . It will also be noted in  FIG. 8  that the temperature increase in the slider  19  can be maintained at a low value when the magnetic disc is rotated. This is because the temperature in the head IC chip  20  does not increase to a noticeable level and the slider  19  itself is also cooled by the flow of air. 
   In order that the head IC chip  20  be effectively cooled by the flow of air produced by the rotating magnetic disc  10 , it is desirable to maintain as small as possible the distance D between the IC chip  20  and the surface of the magnetic disc  10  facing the IC chip  20 . It should however be noted that care must be taken that the head IC chip  20  does not contact with the surface of the magnetic disc  10 . 
   The inventors have noticed through research that, with the distance D between the IC chip  20  and the surface of the magnetic disc  10  facing the IC chip  20  not larger than 1000 μm, it is possible to maintain the temperature of the IC chip  20  at a sufficiently low value, for example below 150° C.  FIG. 10  shows changes in temperature in the IC chip  20  with respect to the distance D between the IC chip  20  and the surface of the magnetic disc  10  facing the IC chip  20 . The data shown in  FIG. 10  is the one which has been obtained through a relatively severe condition wherein the write current of 40 mA is continuously supplied under an environmental temperature of 50° C. which corresponds to the working temperature in the magnetic disc device. It is generally understood that the permissible temperature at the junctions in the IC of the chip is 150° C. at the highest. If the IC is operated for an extended time under a temperature exceeding 150° C., transistor junctions or other parts may gradually be led to failure. As noted in  FIG. 10 , however, it is possible to maintain the temperature of the IC chip  20  below the critical temperature of 150° C. by maintaining the distance D not larger than 1000 μm. 
   With the structure adopting the bare chip element for the head IC chip  20  and mounting the head IC chip by flip-chip bonding, the overall height of the head IC chip as mounted can be kept to a lower value. More specifically, referring to  FIG. 4 , it is recommendable to provide the relationship H 1 &lt;H 2  where H 1  is the height of the head IC chip  20  as mounted as measured from the upper surface of the load beam  31  and H 2  is the height of the slider  19  as mounted as measured from the upper surface of the load beam  31 . It will thus be noted that even with the structure where the head IC chip  20  is mounted on the suspension structure  18  at the side facing to the magnetic disc  10 , it is possible to completely avoid any interference between the head IC chip  20  and the surface of the magnetic disc  10 . 
   It is preferable to determine the distance Lb between the slider  19  and the head IC chip  20  and the distance La between the slider  19  and the mounting point  38  of the suspension structure  18  as shown in  FIG. 3  so that the ratio Lb/La is in the range between 0.2 and 1. In  FIG. 11 , there is shown a relationship between the temperature in the head IC chip  20  during operation and the ratio Lb/La. In  FIG. 12 , there is shown a relationship between the temperature in the slider  19  during operation and the ratio Lb/La. In these figures, it will be noted that the temperature in the head IC chip  20  as well as that in the slider  19  will increase beyond a permissible value when the head IC chip  20  is located too close to the slider  19 . 
   As shown in  FIG. 11 , the temperature in the head IC chip  20  decreases as the location of the head IC chip  20  is moved away from the slider  19  and the temperature will become below the permissible limit when the ratio Lb/La increases up to 0.2. As the location of the head IC chip  20  is moved further away from the slider  19  beyond this point, the temperature of the head IC chip is further decreased and maintained at a substantially constant value in the range of the ratio Lb/La between 0.4 and 0.6. Thereafter, as the location of the head IC chip  20  is moved further away from the slider  19 , the temperature in the head IC chip  20  shows a tendency of gradual increase to reach a peak value at the ratio Lb/La of 0.8 to again decrease. 
   In  FIG. 11 , it will be noted that the temperature in the head IC chip  20  in operation is below the acceptable upper limit with Lb/La≧0.2 and the temperature is lower in the range 0.3≦LB/La≦0.7 than at the Lb/La value of 0.2. It should further be noted that more preferable results can be obtained with the range 0.4≦Lb/La≦0.6. As far as the temperature of the head IC chip  20  is concerned, a preferable result can be obtained with the location of the head IC chip  20  closer to the point  38  of the attachment. However, locating the head IC chip  20  too far from the magnetic head is not recommendable. Therefore, the permissible range for the location of the head IC chip  20  is 0.2≦Lb/La≦, preferably, 0.3≦LB/La≦0.7 and more preferably 0.4≦Lb/La≦0.6. 
   In  FIG. 11 , it will further be noted that the temperature of the head IC chip  20  in operation shows a low value with the head IC chip  20  located in the vicinity of the longitudinal center of the suspension structure  18 . It is understood that this tendency is derived from the fact that the heat in the head IC chip  20  is conducted in opposite directions along the length of the suspension structure  18  both toward the base portion and the tip end thereof. This tendency has been confirmed with the TYPE 1930 and TYPE 830 suspension structures, however, it is understood that this tendency will be seen in any type of suspension structures. 
   As shown in  FIG. 12 , the temperature of the slider  19  in operation decreases as the location of the head IC chip  20  is away from the slider  19 . It will therefore be understood that the location of the head IC chip  20  in the range as described above is also effective to maintain the temperature of the slider  19  and therefore the temperature of the magnetic head  39  within the permissible range. 
   As regards the configuration of the head IC chip  20 , it is preferable that the heat radiating area at the side facing the magnetic disc  10  be as large as possible. More specifically, as shown in FIG.  13 (A), the IC chip  200  may be a thin flat configuration having a substantial area on the surface  200   a  facing the magnetic disc  10 . In an alternative configuration shown in FIG.  13 (B), the IC chip  201  may have an undulated surface configuration at the side facing to the magnetic disc  10 . In this instance, it is preferable that recesses in the undulated pattern be directed substantially parallel to the direction of the flow of air. In a still alternative configuration shown in FIG.  13 (C), the IC chip  202  may have a rough surface  202   a  at the side facing to the magnetic disc  10 . In a still further alternative structure shown in FIG.  13 (D), the IC chip  203  may be provided with a surface  203   a  facing the magnetic disc  10  having one or more grooves  203   b  for allowing the flow of air pass through. The groove  203   b  may have a wide opening toward to the flow of air and a width gradually decreasing toward the other end along the direction of rotation of the magnetic disc  10 . Still further, although not shown in the drawings, the IC chip may be provided at a side facing the magnetic disc  10  with fins or projections which may increase the capability of heat radiation. 
   In order that the heat dissipation be enhanced by any one of the surface configurations of the head IC chip as shown in  FIG. 13 , it is advisable to mount the IC chip by flip-chip bonding on the suspension structure as already described. 
   Referring now to  FIG. 14 , there is shown the structure around the carriage assembly in the magnetic disc device in accordance with another embodiment of the present invention. 
   In the structure illustrated therein, the head IC chip  20  is not mounted on the suspension structure  18  but mounted on the connecting lead member such as the flexible print cord  21  which is connected with an internal circuit of the magnetic disc device. It should however be noted that, in this structure, the IC chip  20  is located inside the outer periphery of the magnetic recording disc  10  during operation and is opposed to the magnetic recording disc  10 . The connecting lead member such as the flexible print cord  21  may be secured to the movable arm  16  or, alternatively, held apart from the movable arm  16 . 
   Thus, it will be noted that the head IC chip  20  is located at a position on the connecting lead member where the IC chip  20  is subjected during operation to the flow of air produced by the rotation of the magnetic disc  10 . It will therefore be understood that the IC chip  20  receives always a cooling action by the flow of air throughout the stroke of the movement of the magnetic head for seeking operation between the inner and outer peripheries of the magnetic disc  10 . As the result, it is possible to decrease temperature increase in the IC chip to a substantial extent. 
   In order to cool the head IC chip effectively by the flow of air produced by the rotation of the magnetic disc  10 , it is preferable that the distance D between the IC chip  20  and the surface of the magnetic disc  10  facing the IC chip  20  as shown in  FIG. 15  be maintained as small as possible. In this instance, care must be taken so that any interference between the IC chip  20  and the adjacent surface of the magnetic disc  10  is avoided. As in the embodiment of  FIG. 1 , it is possible in the present embodiment to maintain the temperature of the IC chip  20  below 150° C. with the distance D between the IC chip  20  and the adjacent surface of the magnetic disc  10  not larger than 1000 μm. 
   In other respects, the structure and function of this embodiment are the same as those in the embodiment of FIG.  1 . 
   It should be noted that the embodiments illustrated and described above are examples only but not restrictive, so that it should be understood that the invention can be put into practice with changes and modifications in various ways. Therefore, the invention shall be limited only by the scope of the appended claims and its equivalents.