Patent Publication Number: US-2007102485-A1

Title: Soldering method and apparatus

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a soldering method and an apparatus thereof and, more particularly, to a soldering method and apparatus for bonding, by soldering, each bonding pad formed on respective bonding targets which are to be bonded to each other.  
      2. Description of the Related Art  
      Soldering is to perform bonding through heating and melting solder on a bonding pad surface where a gold-plated layer is formed, so that the solder and the gold on the bonding pad surface are fused to form a gold-tin alloy. It is used as a means for bonding electronic components to a substrate and the like, for example. By way of example, as shown in  FIG. 1A , it is used when fabricating a magnetic head assembly  101  by soldering a magnetic head slider  114  having a magnetic head element  115  as an electronic component to a suspension  11  to which a flexible printed circuit  112  is integrated.  
      A typical method for soldering will be described here by referring to  FIG. 12 . As shown in this illustration, a solder ball  104  (or paste-type solder) is placed in advance on a junction area where a bonding pad  113  of the suspension  111  side and a bonding pad  116  of the magnetic head slider  114  side are located. Alternatively, it is set at the tip of a laser irradiation device  102  (nozzle). Then, the solder is melted by irradiating laser beams from the nozzle  102  and the molten solder is attached to each of the bonding pads  113  and  116  in the junction area to perform soldering.  
      Subsequently, a more detailed example of the soldering method will be described First, the method shown in  FIG. 2A  is a method in which the solder ball  104  is inserted into the nozzle  102  of a laser torch to be discharged from the tip of the nozzle to the junction area, thereby bonding the bonding pads  113  and  116  by the molten solder. Further, a soldering apparatus utilizing a method shown in  FIG. 3A  comprises, first of all, the nozzle  102  formed in a shape that is tapered towards the tip and, at the same time, a laser irradiating part placed above the nozzle. In that state, the tip opening of the nozzle  102  is formed in a smaller diameter than that of the solder ball  104 , and a suction device (not shown) is connected inside the nozzle  102 . By the operation of the suction device, the solder ball  104  is sucked from the tip side of the nozzle  102  and the solder ball  104  is held at the tip of the nozzle  102 . Soldering is performed by irradiating laser beams through moving the sucked solder ball to the junction area.  
      However, the opening diameter of the laser torch in the conventional case is formed in a circular shape by corresponding to the shape of the solder ball  104 , and the size thereof is set larger or smaller with respect to the external shape of the solder ball  104 . For example, in the case of the above-described method shown in  FIG. 2A , it is formed larger than the external shape of the solder ball  104 . Meanwhile, in the case of the above-described method shown in  FIG. 3A , it is formed smaller than the external shape of the solder ball  104 . Thus, in the case of  FIG. 2A  where it is formed larger, there is caused such an inconvenience that laser beams L leak from the gaps in the periphery of the solder ball  104  so that the laser beams are irradiated out of the area of the bonding pads  113  and  116 . Therefore, the laser intensity distribution of this case becomes the one as indicated by reference code LA of  FIG. 2B , and there may be a risk of damaging the members (for example, polyimide and she like for constituting a flexure) in the periphery of the bonding pads  113  and  116 . Furthermore, in the case of  FIG. 3A  where the opening diameter of the nozzle is formed smaller than the solder ball  104 , the laser beams L are irradiated only to the solder ball, which causes such an inconvenience that the laser beams are not irradiated at all to the bonding pads. Therefore, the laser intensity distribution of this case becomes the one as indicated by reference code LB of  FIG. 3B . Thus, the temperatures of the bonding pads  113  and  116  are not sufficiently increased and the wettability of the molten solder is deteriorated, which may deteriorate the reliability of the solder bonding, e.g. generating connection failure.  
      Patent Literature 1 noted below discloses a technique for solving such shortcomings. In the invention thereof, as shown in  FIG. 4B , a mask  121  is arranged at the tip part of a nozzle  102 . Thereby, the shape of the opening from which laser beams are irradiated is constituted with a circular hole  122  and slits  123 ,  124  crossing the hole  122 . As shown in  FIG. 4A , a laser beam L 101  passing through the hole  122  is set to irradiate the solder ball  104 , while the laser beams L 102  and L 013  passing through the slits  123 ,  124  are set to irradiate the bonding pads  113  and  116 . With this, the bonding pads  113  and  116  are heated before the solder  104  is bonded, so that the wettability can be improved.  FIG. 4C  shows the state where the bonding pads are bonded by the molten solder  140 .  
      However, when the bonding targets of the above-described soldering are electronic components as described above, the electronic components may be heated to a temperature higher than the heat-resistant temperature thereof by the heat applied at the time of soldering. This may cause damaging of the electronic components by the heat of soldering. Therefore, heating of the solder by the laser or the like has conventionally been restricted to a short time.  
      [Patent Literature 1] Japanese Unexamined Patent Publication 2005-123581  
      However, when heating of solder is restricted to a short time, fusion of the solder becomes insufficient due to the short-heating time. Thus, as noted below, stable soldering cannot be achieved.  
      That is, when the heating time of soldering is insufficient, diffusion of gold from the bonding pads  113 ,  116  to the solder  117  becomes insufficient.  FIG. 5A  shows a crystallographic picture of the solder  117  after soldering is performed with a short heating time, and  FIG. 5B  shows an enlarged picture R 11 ′ that is a part of an area R 11 . In these pictures, white needle-shaped substance is the gold-tin alloy. As shown in areas indicated by reference numerals R 11  and R 12  in  FIG. 5A , the gold-tin alloy is concentratedly formed in the vicinity of the bonding pad surfaces  113  and  116 , Thus, a gold-tin alloy layer is formed in the vicinity of the bonding pad surfaces  213  and  116 , and tin alloy is formed in other areas. Therefore, the solder  140  in the junction area is divided into the gold-tin alloy and the tin alloy, so that solder cracks are likely to be generated at the boundary surface between each alloy. In addition, solder separation is likely to be generated since the strength of the tin alloy is weak. As a result, reliability of soldering is decreased. The part where the above-described gold-tin alloy layer is formed and bonding becomes insufficient may particularly be generated at the areas (areas indicated by reference numerals  141 ) which are most distant from the center area of heating and insufficiently heated.  
     SUMMARY OF THE INVENTION  
      The object of the present invention therefore is to improve the inconveniences of the above-described conventional cases and, in particular, to provide a soldering method and an apparatus thereof which can achieve highly reliable soldering.  
      Therefore, one form of the present invention is a soldering method for bonding, by solder, each bonding pad formed on respective bonding targets to be bonded to each other. The method comprises steps of: a pad heating step for irradiating heating beams while the solder is placed on irradiation paths of the heating beams in such a manner that each bonding pad is heated before the solder is melted; and a solder melting step for melting the solder by the heating beams to be attached on each bonding pad, wherein the heating beams are irradiated almost simultaneously In the pad heating step and the solder melting step, and a molten solder heating step is provided thereafter for further heating the molten solder on the bonding pads by the heating beams.  
      With the present invention, first, the solder placed on the irradiation paths is heated by the irradiation of the heating beams, and the bonding pads are heated at the same time. By the irradiation of the heating beams, the solder is melted thereafter, and the molten solder in attached onto the bonding pads. By heating the bonding pads in this manner before fusion of the solder, the bonding pads can be cleaned and activated by the heat. Thus, wettability of the solder for the bonding pads can be improved so that reliability of soldering can be improved. Through continuing irradiation of the heating beams for the molten solder further, the molten solder is heated and the gold on the bonding pads can be diffused over the entire solder. Thereby, the strength of the solder is improved and the reliability of soldering can be improved. In this manner described above, it becomes possible for improve the efficiency of heating by the heating beams and, at the same time, reliability of soldering can be improved by a simple method.  
      Further, the pad heating step irradiates the heating beams to the bonding pads through a periphery of the solder. Thereby, the solder and the bonding pads can be heated effectively, so that energies can be utilized effectively.  
      Further, the pad heating step irradiates the heating beams in an amount of heat with which the solder is not melted within a prescribed time. Furthermore, the pad heating step irradiates heating beams with an intensity weaker than that off the heating beams irradiated in the solder melting step. Moreover, the molten solder heating step irradiates heating beams with an intensity weaker than that of the heating beams in the solder melting step. With this, it is possible to achieve heating of the bonding pads and dispersion of the gold as described above or allowing an improvement in the reliability of soldering, while suppressing excessive heating of the bonding targets. Therefore, generation of malfunctions due to the heat of the bonding targets can be suppressed.  
      Further, irradiation of the heating beams in each of the steps is performed continuously. With this, soldering can be achieved by performing the irradiation once. Thus, It is possible to improve the reliability of t soldering as described above, while simplifying the soldering step.  
      The pad heating step is performed while the solder is placed in advance on the bonding pads. Alternatively, the pad heating step is performed while the solder is held at a tip of an irradiation device for irradiating the heating beams. Furthermore, the pad heating step irradiates the heating beams to each bonding pad before placing the solder on the irradiation paths of the heating beams, and the solder is placed on the irradiation paths during irradiation of the heating beams to each bonding pad. The molten solder heating step discharges the molten solder or the solder before being melted from the tip of the irradiation device of the heating beams to attach the solder on the bonding pads. As described, the present invention can be utilized for various kinds of soldering methods, so that highly reliable soldering can be achieved by various kinds of methods.  
      Further, the molten solder heating step heats at least the vicinity of outer periphery of the solder melted on the bonding pads. At that time, the molten solder heating step performs heating in such a manner that gold is diffused in the molten solder from the bonding pads. With this, the outer periphery of the molten solder, which tends to be heated insufficiently, can be heated efficiently and the gold from the bonding pads can be diffused into the molten solder. Thus, it is possible to suppress generation of a gold-tin alloy layer in the vicinity of the bonding pads, so that the bonding strength by the solder can be improved.  
      Furthermore, irradiation of the heating beams at least in the pad heating step is performed through an irradiation mask that restricts irradiation areas of the heating beams. At that time, it is preferable to perform irradiation of the heating beams in the molten solder heating step through the irradiation mask as well. With this, the irradiations areas of the heating beams can be easily set, so that highly reliable soldering as can be achieved by a simple method as described above.  
      Further, the heating beams are irradiated, respectively, to each bonding pad as irradiation targets. At that time, the heating beams are irradiated simultaneously to the bonding pads which are positioned at a plurality of junction areas, respectively. Furthermore, the heating beams are irradiated, respectively, with intensities set in advance in accordance with positions of the bonding pads or with intensities set in advance in accordance with each of the bonding pads. With this, it is possible to heat only the bonding pads effectively before melting the solder. At the same time, diffusion of the gold from the vicinity of the bonding pads to the molten solder can be more promoted after the solder is melted as well. Therefore, excessive heating of the bonding targets and the like can be suppressed to prevent the damages thereof. At the same time, secure bonding can be achieved, and the reliability of soldering can he improved. Furthermore, by simultaneously performing irradiations to each of the plurality of bonding pads, the soldering step can be simplified. Moreover, through performing laser irradiations by setting the intensities of the laser beams in accordance with the positions of the bonding pads or in accordance with each of she bonding pads, a proper amount of heat can be applied to each pad. Therefore, thermal damages to the bonding targets can be suppressed further.  
      Further, the present invention manufactures a head gimbal assembly in which a magnetic head slider is bonded to a suspension by the above-described soldering. Furthermore, the present invention manufactures a magnetic disk device in which the head gimbal assembly is loaded, Like this, by forming the head gimbal assembly and the magnetic disk device by employing the above-described soldering method for bonding the magnetic head slider, it becomes possible to manufacture the magnetic disk device with still higher reliability.  
      Another form of the present invention is a soldering apparatus used for bonding, by solder, each bonding pad formed on respective bonding targets to be bonded to each other. The apparatus comprises an irradiation device having a nozzle for irradiating heating beams to a junction area, and a control device for controlling irradiation state of the heating beams through controlling action of the irradiation device, wherein: at a tip of the nozzle, there are formed a solder irradiation hole for irradiating the heating beams to solder placed on irradiation paths of the heating beams and bonding-pad irradiation holes for irradiating the heating beams to the bonding pads; and the control device controls action of the irradiation device to irradiate the heating beams, respectively, to the junction area, before and after the solder is melted.  
      Before melting the solder, the control device controls action of the irradiation device to irradiate the heating beams in an amount of heat with which the solder is not melted within a prescribed time. Further, before melting the solder, the control device controls action of the irradiation device to irradiate the heating beams with an intensity weaker than that of irradiation for melting the solder. Furthermore, after the solder is melted, the control device controls action of the irradiation device to irradiate the heating beams with an intensity weaker than that of irradiation for melting the solder. Moreover, the control device controls action of the irradiation device to irradiate the heating beams continuously.  
      The irradiation device irradiates the heating beams to solder placed in advance on the bonding pads. Alternatively, the irradiation device performs soldering under a state where the solder is held at the tip of the nozzle. Further, the irradiation device performs soldering by supplying solder to the tip of the nozzle after starting irradiation of the heating beams to each bonding pad. The irradiation device performs soldering by discharging the solder placed at the tip of the nozzle onto the bonding pads to attach the solder thereon.  
      The bonding-pad irradiation holes are formed in a shape, size, or at positions with which the heating beams can be irradiated to the bonding pads through a periphery of the solder. Furthermore, the bonding-pad irradiation holes are formed in a size so that, when the heating beams passed through the bonding-pad irradiation holes are irradiated to the bonding pads, irradiation areas thereof do not exceed areas of the bonding pads.  
      Furthermore, another constitution of the soldering apparatus is a soldering apparatus used for bonding, by solder, each bonding pad formed on respective bonding targets to be bonded to each other. The apparatus comprises an irradiation device having a nozzle for irradiating heating beams to a junction area, and a control device for controlling irradiation state of the heating beams through controlling action of the irradiation device, wherein; the nozzle of the irradiation device is formed to be capable of irradiating the heating beams, respectively, to each bending pad as irradiation targets; and the control device controls action of the irradiation device to irradiate the heating beams, respectively, before and after melting the solder.  
      The irradiation device irradiates the heating beams simultaneously to a plurality of the bonding pads which are positioned at a plurality of junction areas, respectively. Further, the control device performs irradiations, respectively, with intensities set in advance in accordance with positions of the bonding pads.  
      The soldering apparatuses with the above-described constitutions also function like the above-described soldering method, so that it is possible to achieve highly reliable soldering that is the object of the present invention as described above.  
      The present invention is constituted and functions as described above. With this, the bonding pads can be heated before fusion of the solder used for bonding, so that the bonding pads can be cleaned and activated by the heat. Thus, wettability of the solder for the bonding pads can be improved, and the reliability of soldering can be improved. Further, through continuing irradiation of the heating beams for the molten solder, the molten solder is heated and the gold on the bonding pads can be diffused over the entire solder. Thereby, the strength of the solder is improved further, so that the reliability of soldering can be improved further. Those are excellent effects that have not been achieved conventionally. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1A  is an illustration of soldering targets for describing a soldering apparatus according to a conventional case;  
       FIG. 1B  is an illustration for showing the state of soldering performed to the soldering targets shown in  FIG. 1A ;  
       FIG. 2A  is an illustration for showing an example of a soldering method according to the conventional case;  
       FIG. 2D  is an illustration for showing the intensity distribution of laser beams that are irradiated to solder in the soldering method shown in  FIG. 2A ;  
       FIG. 3A  is an illustration for showing an example of a soldering method of the conventional case;  
       FIG. 3B  is an illustration for showing she intensity distribution of laser beams that are irradiated to the solder in the soldering method shown in  FIG. 3A ;  
       FIG. 4A  is an illustration for showing the structure of the soldering apparatus according to the conventional case;  
       FIG. 4B  is a front elevational view of the tip part of a nozzle shown in  FIG. 4A ;  
       FIG. 40  is an illustration for showing the state after performing soldering by the soldering apparatus shown in  FIG. 4A ;  
       FIG. 5A  is a crystallographic picture of the solder after performing soldering in the conventional case;  
       FIG. 5F  is fragmentary enlarged picture of  FIG. 5A ;  
       FIG. 6A  is a schematic view for showing the structure of a soldering apparatus according to a first embodiment;  
       FIG. 6B  is a front elevational view of the tip part of a nozzle shown in  FIG. 6A ;  
       FIG. 7A  is an illustration for showing the state when irradiation of laser beams is started in the first embodiment;  
       FIG. 7B  is an illustration for showing the irradiation state of the laser beams in the first embodiment;  
       FIG. 8A  is an illustration for showing the state where the solder is melted at a junction area in the first embodiment;  
       FIG. 8B  is an illustration for showing the state of the solder when the laser beams are irradiated continuously further after the state of  FIG. 8A ;  
       FIG. 8C  is an illustration for showing the state of the solder after the state of  FIG. 8B ;  
       FIG. 9A  is a crystallographic picture for showing the state of the solder after performing soldering;  
       FIG. 9B  is a fragmentary enlarged picture of  FIG. 9A ;  
       FIG. 10  is a flowchart for showing the operation of the soldering apparatus according to the first embodiment;  
       FIG. 11  is a flowchart for showing the operation of the soldering apparatus according to a second embodiment;  
       FIG. 12A  is a schematic view for showing the structure of a soldering apparatus according to a third embodiment;  
       FIG. 12B  is a front elevational view of the tip part of a nozzle shown in  FIG. 12A ;  
       FIG. 13  is a flowchart for showing the operation of the soldering apparatus according to the third embodiment;  
       FIG. 14A  is a schematic view for showing the structure of a soldering apparatus according to a fourth embodiment;  
       FIG. 14B  is a schematic view for showing the structure of the soldering apparatus according to the fourth embodiment;  
       FIG. 15  is a flowchart for showing the operation of the soldering apparatus according to the fourth embodiment;  
       FIG. 16A  is a front elevational view of the tip part of a nozzle according to a fifth embodiment;  
       FIG. 16B  is an illustration for showing the irradiation state of the laser beams that are irradiated from the nozzle in the fifth embodiment;  
       FIG. 17A  is an illustration for showing the state when laser beams are irradiated in a sixth embodiment;  
       FIG. 17B  is an illustration for showing the state when laser beams are irradiated in the sixth embodiment;  
       FIG. 18A  is an illustration for showing an example of the laser irradiation intensities of each bonding pad in the sixth embodiment;  
       FIG. 18B  is an illustration for showing the state when laser beams are irradiated to the bonding pads in the sixth embodiment;  
       FIG. 18C  is an illustration for showing the temperature distribution on the bonding pad when the laser beams are irradiated in the sixth embodiment;  
       FIG. 18D  is an illustration for showing the temperature distribution en the bonding pad when the laser beams are irradiated in the sixth embodiment; and  
       FIG. 19  is an illustration for showing the structure of a magnetic disk device according to a seventh embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is distinctive in respect that the solder pads are heated in the junction area before melting the solder when soldering the bonding pads to each other, and heating is continued further after the solder is melted. With this, the wettability oaf the solder for the bonding pads can be improved. At the same time, gold on the bonding pads can be diffused over the entire molten solder, so that the bonding strength can be improved and highly reliable soldering can be achieved.  
      Embodiments in the followings will be described by referring to the case where a magnetic head slider is bonded to a suspension. That is, there will be described the case of bonding, by solder, a bonding pad to be a connecting terminal of a magnetic head slider as a bonding target and a bonding pad to be a connecting terminal of a flexible printed circuit on which a wiring race integrated with a suspension is formed. It is noted, however, that the present invention can be applied to soldering performed on any kinds of bonding targets.  
     First Embodiment  
      A first embodiment of the present invention will be described by referring to  FIG. 6 - FIG. 10 .  FIG. 6  is a schematic view for showing the structure of a soldering apparatus.  FIG. 7 - FIG. 8  are illustrations for describing the state at the time of soldering.  FIG. 9  is a crystallographic picture for showing the state of the solder after soldering is performed.  FIG. 10  is a flowchart for describing actions at the t-me of soldering performed by the soldering apparatus.  
      [Structure] 
      A soldering apparatus  20  according to this embodiment fabricates a head gimbal assembly  1  by solder-bonding a magnetic head slider  14 (bonding target) to a suspension  11  (bonding target). As shown in  FIG. 6A , the soldering apparatus  20  comprises a laser irradiator (irradiation device) having a nozzle  2  for outputting laser beams (heating beams) to heat the solder, and a controller  3  (controlling device) for controlling the action of the entire apparatus. In the followings, each structure will be described in detail.  
      First of all, the soldering targets (bonding targets) in this embodiment are the magnetic head slider  14  and the suspension  11 . Specifically, a bonding pad  16  (slider-side bonding pad) that is a connecting terminal formed in a magnetic head device part  15  of the magnetic head slider  14  is connected by using solder to a bonding pad  13  (board-side bonding pad) that is a connecting terminal formed on a flexible printed circuit  12  that is integrated with the suspension  11 . In other words, this area becomes the solder junction area. The present invention is particularly effective when bonding both solder pads  13  and  16  arranged roughly at a right angle. The solder used herein is lead-free solder, however, the solder is not limited to such type.  
      The laser irradiator outputs diode lasers from the nozzle  2 . The irradiation action of the laser beams from the nozzle  2  is controlled by the controller  3 . That is, the controller  3  controls the output value, irradiation time, irradiation position, etc, of the laser beams, respectively. The description thereof will be provided later  
      The laser irradiator employs the structure in which a solder ball  4  is held at a position between a tip part  21  of the nozzle  2  and the bonding pads  13 ,  16 , and lasers are irradiated in this state to fuse the solder hall  4  to perform soldering. However, as will be described in other embodiments, there may be employed a structure in which the solder ball  4  is held only by the nozzle  2 , and the solder is discharged to the junction area from the position away from the bonding pads  13 ,  16  to dispose the molten solder to the junction area. Further, there may be employed a structure in which soldering is performed by irradiating laser beams to the solder that is placed in advance on the bonding pads  13 ,  16  (junction area, without holding the solder ball  4  at the nozzle  2 . The type of the laser, the structure and the like of the laser irradiator are not limited to those described above. Furthermore, other irradiators that output heating beams may be used as the device for heating the solder.  
       FIG. 6B  shows the tip part  21  of the nozzle  2  when viewed from the front. As shown in this illustration, a laser output port (irradiation mask) through which the laser beams are outputted is formed at the nozzle tip part  21 . As the laser output port, there are formed a solder irradiation hole  22  formed with a circular hole smaller than the external shape of the solder ball  4  and slit-type bonding-pad irradiation holes  23 ,  24  which cross almost the center of the solder irradiation hole  22 . With this, the laser beams are outputted through each of the holes  22 ,  23 , and  24 , so that the irradiation area of the beams can be restricted thereby. Specifically, the laser beams outputted from the solder irradiation hole  22  are irradiated to the solder ball  4  held mainly at the tip part  21  as will be described later. Further, as will be described later, the laser beams outputted from the bonding-pad irradiation holes  23 ,  24  are irradiated to the bonding pads  13 ,  16 . In the above, there has been described that each of the above-described holes  22 ,  23 ,  24  serving as the laser output port is directly formed in the tip part  21 . However, a member (irradiation mask) in which such holes are formed may be mounted at the tip part  21  to achieve restriction of the irradiation areas of the laser beams as described above.  
      The controller  3  controls the irradiation condition of the laser beams at the tame of soldering. In this embodiment, in particular, it is controlled to perform one-time continuous irradiation of laser beams from the start of the irradiation to melt the solder ball  4 , and to irradiate the laser beams thereafter for a prescribed time as well. The irradiation time thereof is controlled. In the followings, the state of the laser beams at the time of irritation and the state of the solder thereof will be described by referring to  FIG. 7 - FIG. 8 .  
      First, laser beams are irradiated while the solder ball  4  is held at the tip part  21  of the nozzle  2 . With this, laser beams are outputted as indicated by reverence numerals L 1 , L 2 , and L 3  in  FIG. 7A . Among those, the laser beam L 1  is outputted from the solder irradiation hole  22 , and the laser beams L 2 , L 3  are outputted from the bonding-pad irradiation holes  23 ,  24 . Thus, the laser beam L 1  is irradiated to the solder ball  4 , and the laser beams L 2 , L 3  are irradiated onto the respective bonding pads  13 ,  16  through the periphery of the solder ball placed on the irradiation paths of the laser beams. The irradiation area of the laser beams in that state is indicated by reference numeral L 10  in  FIG. 7B . The laser beams are irradiated while being set at the intensity with which the solder ball  4  is not melted in a short time, so that the amount of heat sufficient to fuse the solder ball  4  is applied only after performing irradiation of the laser beams for a certain time. Therefore, for the certain time before the solder ball  4  is melted, the laser beans L 2 , L 3  are also irradiated to each of the bonding pads  13 ,  16  as shown by reference numeral L 10  in  FIG. 7B  to heat the bonding pads  13  and  16  are heated, while heating the solder ball  4 .  
      Then after the certain time for irradiating the laser beams has passed, the solder  40  s melted as shown in  FIG. 8A  and attached between each of the bonding pads  13 ,  16 . The controller  3  continues to perform heating thereafter also for a certain time. That is, as shown in  FIG. 5A  and  FIG. 5B , the laser beams L 1 , L 2 , L 3  outputted from the solder irradiation hole  22  and the bonding-pad irradiation holes  23 ,  24  formed in the tip part  21  of the nozzle  2  are irradiated to molten solder  40 . Therefore, not only the center of the molten solder  40  but also the vicinity of the outer periphery of the molten solder  40  is heated especially by the laser beams L 2  and L 3 .  
      By referring to the schematic illustrations of  FIG. 8A and 8B , there will now be described the state of the solder  40  when irradiation of the laser beams L 1 , L 2 , L 3  are continued to the molten solder  40  for the certain time after the solder has been melted as has been described above. First, as shown in  FIG. 8A , gold  41  from the bonding pads  13 ,  16  placed in the vicinity of the surfaces of both bonding pads  13 ,  16  comes to diffuse over the entire solder  40  by continuous heating of the solder  40 . That is, as shown by arrows in the solder  40  of  FIG. 8B , the gold in the vicinity of the surface of the board-side bonding pad  13  is diffused over the entire solder, while the gold is the vicinity of the surface of the slider-side bonding pad  16  is drawn to diffuse towards the opposite side, i.e. in the direction of the board-side bonding pad  13 . With this, the gold is diffused over the entire solder  40  and the gold-tin alloy can be distributed uniformly as shown in  FIG. 8C .  
       FIG. 9A  shows the crystallographic picture of the solder  40  after performing the above-described soldering, in which the white needle-shape and dot-shape substances are the gold-tin alloys. It can be seen from the picture that the gold-tin alloys are diffused uniformly over the entire solder.  FIG. 9B  is an enlarged picture of the solder  40  in the vicinity of the slider-side bonding pad  16 . Compared to the conventional case shown in  FIG. 5B , it can be seen that the gold-tin alloys are not concentrated in the vicinity of the surface of the bonding pad  16  but distributed uniformly.  
      With this, the gold on the bonding pads  13 ,  16  comes to diffuse over the entire solder  40  so that the gold-tin alloys can be distributed uniformly, thereby improving the strength of the solder. Furthermore, overheating of the magnetic head slider  14  (magnetic head element part  15 ) can be suppressed at this time, so that it is possible to protect the magnetic head slider  14 .  
      After the laser beams are irradiated for the certain time in this manner, the controller  3  operates to stop the irradiation of the laser beams  
      The irradiation time of the laser beams is set in such a manner that the magnetic head element of the magnetic head slider is not broken down by the heat even the laser beams with the set laser intensity are irradiated for that time and, as described above, the gold can be properly diffused. It is set to the time that is determined in advance based on an experiment, analysis, logical operation, and experience.  
      [Operation] 
      Next, the soldering operation by the above-described soldering apparatus will be described by referring to a flowchart of  FIG. 10  and illustrations of  FIG. 6 - FIG. 9 .  
      First, the solder ball  4  is set to be held at the tip part  21  of the nozzle  2  (step S 1 ). Then, as shown in  FIG. 6A , the position of the nozzle  2  is set by moving the nozzle  2  so that the solder ball  4  comes in contact with the bonding pad  13  formed in the suspension  11  and the bonding pad  16  formed in the magnetic headslider  14  (step S 2 ). At this stage, for example, the solder ball  4  may be held by being sucked by the nozzle  2  from the tip side, or it may be pinched between the tip part  21  of the nozzle  2  and the bonding pads  13 ,  16  by moving the tip part  21  of the nozzle  2  to the position of the solder ball  4  that is placed in advance to be in contact with the bonding pads  13 ,  16 .  
      In the above-described state, as shown in  FIG. 7A , irradiation of the laser beams from the nozzle  2  is started (step S 3 ), and the irradiation is performed for the set time with the intensity set in advance. With this, first, the laser beam L 1  outputted from the solder irradiation hole  22  of the nozzle  2  is irradiated to the solder ball  4 . Further, the laser beams L 2  and L 3  outputted from the bonding-pad irradiation holes  23  and  24  (slit-type holes) of the nozzle  2  are irradiated to the bonding pads  13 ,  16  through the periphery of the solder ball  4  (see reference numeral L 10  of  FIG. 7B ). This irradiation state is continued for a prescribed time until the solder ball  4  is melted, and each of the bonding pads  13  and  16  is heated during this time (step S 4 , pad heating step). As described above, the intensity of the laser beams is weak to such an extent that the amount of heat capable of melting the solder ball  4  is not applied in a short time within which the bonding pads  13 ,  16  are not heated to the state suitable for soldering with the laser beams L 2 , L 3  that have passed through the bonding-pad irradiation holes  23 ,  24 .  
      Thereafter, when the irradiation is continued for the prescribed time and the amount of the heat that is enough to fuse the solder ball  4  is applied by the above-described laser beam L 1 , the solder is melted as shown in  FIG. 8A  (step S 5 , solder melting step). Thereby, the molten solder  40  is attached to both bonding pads  13  and  16 . In that state, both bonding pads  13 ,  16  have already bean heated so that cleaning and activation of the bonding pads  13 ,  16  have been achieved by the heat. Thus, the wettability of the solder is improved, which enables highly reliable soldering.  
      Thereafter, irradiation of the laser beams L 1 , L 2 , L 3  is continued further for a prescribed time (molten solder heating step). With this, as shown in  FIG. 8A , the entire molten solder  40  is heated and, in particular, not only the center of the molten solder  40  but also the vicinity of the cuter periphery is heated. Upon this, the gold from the bonding pads  13 ,  16  concentrated in the vicinity of the junction area between the molten solder  40  and the bonding pads  13 ,  16  is diffused over the entire solder  40  as the gold  41  shown in  FIG. 8B  and  FIG. 8C  by the heat applied further (step S 6 ). After a prescribed time has passed from the fusion of the solder and a preset time has passed from the start of laser irradiation step S 3 ), the irradiation of laser is stopped (step S 7 ). That is, one-time continuous irradiation of laser beams from the steps S 3 -S 7  is ended.  
      With this, it is possible with one-time irradiation of the laser beams to heat the bonding pads  13 ,  16  before melting the solder to improve the wettability and, at the same time, to heat the molten solder  40  further after melting the solder to disperse the gold. Therefore, it is possible to improve the efficiency of applying heat by the laser beams and the reliability of soldering by a simple method, which enables improvements in the quality of the products produced by the soldering as well as reduction of the manufacturing cost.  
     Second Embodiment  
      Next, a second embodiment of the present invention will be described by referring to  FIG. 11 . The soldering apparatus  20  of this embodiment has almost the same structure as that of the first embodiment, except that the control of the laser beam irradiation by the controller  3  is different. In the followings, this point will be described in detail. Other structures are same as those of the first embodiment, so that the descriptions thereof are omitted.  
      [Structure] 
      Before the solder is melted, the controller  3  (controlling device) according to this embodiment controls to perform irradiation by setting the intensity of the laser beams weaker than that of the laser beams irradiated when melting the solder as will be described later. That is, there are irradiated the laser beams with low intensity with which the sclder hall  4  is not melted within a time set in advance from the start of the laser irradiation. Further, the controller  3  controls to irradiate the laser beams with stronger intensity than that, after the above-described preset time has passed. The time for irradiating the laser with this strong intensity is the time that is considered in advance to be enough to fuse the solder hall  4 . Thereafter, the controller  3  controls to irradiate the laser beams with weaker intensity than the intensity for melting the solder as described above, after the solder is melted. The laser irradiation is controlled in this manner to irradiate the laser beams with weak, strong, weak intensities from the start of laser irradiation for each set time.  
      [Operation] 
      Next, the operation of the soldering apparatus  20  with the above-described structure will be described by referring to  FIG. 11 . Preparations such as setting the solder ball  4  at the tip part  21  of the nozzle  2  and setting the position of the nozzle  2  by moving it are the same as the above-described case (steps S 11 , S 12 )  
      When irradiation of the laser beams is started (step S 13 ), first, the laser beams are irradiated for a prescribed time by setting the intensity weak so that the solder ball  4  is not melted (step S 14 , pad heating step). During this, the bonding pads  13  and  16  are heated, and the wettability is improved. Thereafter, the laser beams with the intensity set stronger than earlier are irradiated for a prescribed time (step S 15 , solder melting step). With this, the solder ball  4  is melted, and the molten solder  40  is attached to both bonding pads  13 ,  16 . Thereafter, the laser beams with the intensity set weaker than earlier are irradiated for a prescribed time (step S 16 , molten solder heating step). Thereby, gold is diffused entirely in the molten solder  40 , thus increasing the bonding strength. Then, laser irradiation is stopped after a prescribed time (step S 17 ).  
      As described above, by setting the intensity of the laser beams to be weak before and after melting the solder ball  4 , excessive heating of the magnetic head slider and the suspension as the bonding targets can be suppressed. Thus, damages to the magnetic head element part, deformation of the suspension, etc. caused by heat can be suppressed. As a result, the quality of the products can be improved.  
      Irradiation of the laser beams in the steps from S 13  to S 17  is achieved by one-time continuous irradiation. However, irradiation of the laser beams may be stopped when changing the intensity, in order to perform irradiation by setting new intensity for each time. In other words, the above-described soldering may be achieved by irradiating the laser beams for a plurality of times in a single solder bonding process.  
     Third Embodiment  
      Next, a third embodiment of the present invention will be described by referring to  FIG. 12 - FIG. 13 .  FIG. 12  illustrates the structure of the soldering apparatus according to this embodiment, and  FIG. 13  is a flowchart for showing the operation thereof.  
      [Structure] 
      As shown in  FIG. 12A  and  FIG. 12B , the soldering apparatus according to this embodiment performs irradiation of the laser beams L 1 , L 2 , L 3  while holding the solder ball  4  at the tip part  21  of the nozzle  2 , and the solder  40  melted by the laser irradiation is discharged onto the bonding pads  13 ,  16  positioned in the junction area (see an arrow with dotted line in  FIG. 12A ) to attach the solder  40  on the bonding pad  13 ,  16  for achieving soldering.  
      The structure of the soldering apparatus will be described in more detail. As shown in  FIG. 12A , the shape of the nozzle  2  is the same as that described above, and the solder ball  4  is held at the solder irradiation hole  22  among the laser output ports formed in the tip part  21  through which the laser beams are outputted. Regarding the method for holding the solder ball  4 , it may be held at the solder irradiation hole  22  by sucking or the solder ball may be pushed into the solder irradiation hole  22  to be held therein.  
       FIG. 126  shows the tip part  21  of the nozzle  2  viewed from the front. As shown in this illustration, long-and-narrow substantially oval shape bonding pads  23 ,  24  are formed across the solder irradiation hole  22  at which the solder ball  4  is held. In the nozzle  2 , the solder ball  4  is melted by irradiation of the laser beams as will be described later, and the molten solder is discharged from the tip part  21  by a pressing force such as a gas. The solder discharged from the nozzle  2  onto the bonding pads  13 ,  16  may be in the form of solder ball before being melted, and it may be melted on the bonding pads  13 ,  16  by the heat of the bonding pads  13 ,  16  that are heated in advance or by the laser beams irradiated further.  
      [Operation] 
      Next, the operation of the soldering apparatus with the above-described structure will be described by referring to a flowchart of  FIG. 13  and the illustrations of  FIG. 12 . First, the solder bail  4  is set at the tip part  21  of the nozzle  2  (step S 21 ), and the position of the nozzle  2  is moved to be set at the position capable of discharging the solder from the nozzle tip part  21  onto the bonding pads  13 ,  16  (step S 22 ) as shown in  FIG. 12A .  
      When irradiation of the laser beams is started (step S 23 ), first, the laser beam L 1  outputted from the solder irradiation hole  22  of the nozzle  2  is irradiated to the solder ball  4 . Further, the laser beams L 2  and L 3  outputted from the bonding-pad irradiation holes  23  and  24  of the nozzle  2  are irradiated to the bonding pads  13 ,  16  through the periphery of the solder ball  4  (see  FIG. 12A )). This irradiation state is continued for a prescribed time until the solder ball  4  is melted (pad heating step). Thereby, the bonding pads  13 ,  16  are heated until the solder ball  4  is melted (step  324 ), and cleaning and activation thereof is achieved by the heat. Thus, the wettability of the solder can be improved.  
      Thereafter, when the irradiation is continued for the prescribed time and the amount of the heat that is enough to fuse the solder ball  4  is applied by the above-described laser beam L 1 , the solder is melted at the nozzle tip part  21  (step S 25 , solder melting step). Thereby, the molten solder  40  is discharged from the solder irradiation hole  22  by the pressing force of the gas within the nozzle  2  and disposed to the bonding pads  13  and  16  (step S 26 ). The solder discharged onto the bonding pads  13 ,  16  may be in the form of solder ball as it is without being melted, and it may be melted on the bonding pads  13 ,  16  by the heat of the bonding pads  13 ,  16  or by the laser bean L 1  after being discharged.  
      Thereafter, irradiation of the laser beams L 1 , L 2 , L 3  is continued further for a prescribed time (molten solder heating step). With this, in the same manner described above, the entire molten solder  40  is heated on the bonding pads  13 ,  16  and, in particular, not only the center of the molten solder  4 C but also the vicinity of the outer periphery is heated. Upon this, the gold  41  from the bonding pads  13 ,  16  concentrated in the vicinity of the junction area between the molten solder  40  and the bonding pads  13 ,  16  is diffused over the entire solder by the heat applied further (step S 27 ). After a prescribed time has passed from the fusion of solder and a preset time has passed from the start of laser irradiation (step S 23 ), the irradiation of laser beams is stopped (step S 28 ).  
      As described above, it Is also possible with this soldering method to achieve highly reliable soldering as described above.  
      As has been described in the second embodiment, the intensity of the laser beams may be controlled by the controller  3  or by manual operation at the time of laser irradiation in the snaps From S 23 -S 28  described above. That is, it may be set to irradiate the laser beams with relatively weak intensity at the time of heating the pads immediately after the start of laser irradiation and at the time of dispersing the gold after the solder is melted.  
     Fourth Embodiment  
      Next, a fourth embodiment of the present invention will be described by referring to  FIG. 14 - FIG. 15 .  FIG. 14  shows the illustrations of the structure of the soldering apparatus according to this embodiment, and  FIG. 15  is a flowchart for showing the operation thereof.  
      [Structure] 
      As shown in  FIG. 14A , the soldering apparatus according to this embodiment does not hold the solder ball  4  at the tip part  21  of the nozzle  2  in advance. It employs the structure in which the solder ball  4  or the molten solder is supplied to the tip part  21  after starting the irradiation of the laser beams. For example, as shown in  FIG. 14A , the solder ball  4  is inserted into the nozzle  2  at the time of irradiating the laser beams (see an arrow Y 2 ), which is then moved to the tip part  21  (see an arrow Y 3  with dotted line). Thereby, as shown in  FIG. 14B , the solder ball  4  or the solder melted within the nozzle  2  is held temporarily in the solder irradiation hole  22  of the tip part  21 , so that the solder is discharged onto the bonding pads  13 ,  16  (see an arrow Y 4  with dotted line) like the above-described case. The soldering apparatus of this embodiment performs soldering by providing the solder on the bonding pads  13  and  16  in this manner.  
      [Operation] 
      Next, the operation of the soldering apparatus with the above-described structure will be described by referring to a flowchart of  FIG. 15  and the illustrations of  FIG. 14 . First, as shown in  FIG. 14A , the position of the nozzle  2  is moved to be set at the position capable of discharging the solder from the nozzle tip part  21  onto the bonding pads  13 ,  16  (step S 31 ) Then, laser irradiation is started (step S 32 ).  
      In this embodiment, the solder ball  4  is not placed at the tip part  21  of the nozzle  2 , so that all the outputted laser beams L 1 , L 2 , L 3  are irradiated to the bonding pads  13 ,  16  that function as the junction area, thereby heating the bonding pads  13 ,  16  (step S 33 ). While the laser beams are irradiated, the solderball  4  is inserted into the nozzle  2  (step S 34 ). Thereby, the solder ball  4  is placed at the nozzle tip part  21  (pad heating step) as shown in  FIG. 14B .  
      Thereafter, when the amount of the heat that is enough to fuse the solder ball  4  is applied by the above-described laser beams, the solder melted at the nozzle tip part  21  is discharged from the solder irradiation hole  22  by the pressing force of the gas within the nozzle  2 . Thereby, the molten solder is attached to the bonding pads  13  and  16  (step S 35 , solder melting step).  
      Thereafter, irradiation of the laser beams L 1 , L 2 , L 3  is continued further for a prescribed time (molten solder heating step). With this, in the same manner described above, the entire molten solder  40  is heated on the bonding pads  13 ,  16  and, in particular, not only the center of the molten solder  40  but also the vicinity of the outer periphery is heated. Upon this, the gold  41  from the bonding pads  13 ,  16  concentrated in the vicinity of the junction area between the molten solder  40  and the bonding pads  13 ,  16  is diffused ever the entire solder by the heat applied further (step S 36 ). After a prescribed time has passed from the fusion of solder and a preset time has passed from the start of laser irradiation (step S 32 ), the irradiation of laser beams is stopped (step S 37 ).  
      As described above, it is also possible with this soldering method to achieve highly reliable soldering as described above.  
      As has been described in the second embodiment, the intensity of the laser beams may be controlled by the controller  3  or by manual operation at the time of laser irradiation in the steps from S 32 -S 37  described above. That is, it may he set to irradiate the laser beams with relatively weak intensity at the time of heating the pads immediately after the start of laser irradiation and at the time of dispersing the gold after the solder is melted.  
     Fifth Embodiment  
      Next, a fifth embodiment of the present invention will be described by referring to  FIG. 16 .  FIG. 16A  is a front elevational view of the tip part  21  of the nozzle  2 , and  FIG. 16B  is an illustration for showing the irradiation state of the laser beams irradiated from the nozzle  2 .  
      The aforementioned embodiments have been described by referring to the case where the bonding-pad irradiation holes  23 ,  24  provided in the tip part  21  of the nozzle  2  are formed in a long-and-narrow slit shape across the solder irradiation hole  22 . However, it should not be limited to that. For example, as shown in  FIG. 16A , the bonding-pad irradiation holes  23  and  24  may be formed in a shape having a wider width. The irradiation state of the laser beams irradiated from such bonding-pad irradiation holes  23 ,  24  to the bonding pads  13 ,  16  is shown by reference numerals L 11 , L 12  in  FIG. 16B . As shown in the illustration, the irradiated area of the bonding pads  13  and  16  by the laser beams becomes wider since the bonding-pad irradiation holes  23 ,  24  are formed larger than those formed in the other embodiments described above. Thus, the bonding pads  13  and  16  can be heated effectively.  
      The bonding-pad holes  23  and  24  may not necessarily have to be formed by being connected to the solder irradiation hole  22 , but each of the holes may be formed as independent holes Further, the number, shape and size of the holes are not limited to the above-described ones. However, as shown in  FIG. 16B , it is necessary to set the shape, size and positions thereof so that the irradiation area of the bonding pads  13 ,  16  by the laser beams passing through the bonding-pad irradiation holes  23 ,  24  does not exceed the area of the bonding pads  13 ,  16 , and the laser beams are not irradiated out of the bonding pads  13 ,  16 .  
     Sixth Embodiment  
      Next, a sixth embodiment of the present invention will be described by referring to  FIG. 17 - FIG. 18 .  FIG. 17  shows the structure of the soldering apparatus according to this embodiment, and  FIG. 18  shows illustrations for showing the state of laser irradiation.  
      As shown in  FIG. 17A , the soldering apparatus according to this embodiment has a plurality of laser irradiation ports formed in the nozzle  2 . The laser irradiation ports are formed particularly in accordance with the positions of the bonding pads placed at the bonding area, i.e. the positions of the board-side bonding pad  13  formed on the suspension  11  and the slider-side bonding pad  16  formed in the magnetic head slider  14  at the time of solder bonding, so as to irradiate the laser beams only to the respective pads. For example, in the embodiment, six each of the bonding pads  13 ,  16  are arranged in pairs as shown in  FIG. 17B . In accordance with this, a total of twelve laser irradiation ports are formed in two lines vertically and six lines horizontally to enable irradiation of the laser beams. With this, the laser beams L 11  and L 12  can be irradiated separately to the individual bonding pads  13  and  16 .  
      Specifically, in this embodiment, a plurality of laser irradiation tubes are mounted inside the laser torch  2 . Thus, the laser beams pass through each tube in the laser torch  2 , and the laser beams L 11 , L 12  are irradiated from each tube to each of the bonding pads  13 ,  16 . In other words, the laser irradiation ports are constituted with each of the tubes. When one side of each of the substantially square bonding pads  13 ,  16  is 80 μm, for example, the diameters of the laser irradiation tubes are formed to be capable of irradiating the circular laser beams having the diameter almost in the same length as the one side of the pads. The diameter can be set arbitrarily, however, it is desirable to be as capable of irradiating the laser beams to the range within the area of the bonding pads.  
      It is so constituted that the intensities of each of the laser beams L 11 , L 12  irradiated to the respective bonding pads  13 ,  16  can be set, respectively, by the controller  3 .  FIG. 18  shows an example of the control of the laser beam intensity. As shown in  FIG. 18A , among the bonding pads  13 ,  16  arranged in the lateral direction, the intensities thereof are set to become stronger towards the outer side, respectively, from the bonding pads ( 3 ,  4 ) positioned in the center. In other words, the intensities of the laser beams for the bonding pads ( 1 ,  6 ) positioned at the outermost are the strongest, and it becomes gradually weaker towards the center. For the other bonding pads lined in the vertical direction, the intensities of the laser beams are set in the same manner to perform irradiation. Specifically, the intensities are set to be capable of heating the bonding pads to 220-350° C.  
      With this, the temperature distributions in the vertical direction (y direction in  FIG. 18B ) and the lateral direction (x direction in  FIG. 1D ) at the time of irradiating the laser beams to each of the bonding pads  13 ,  16  become those shown in  FIG. 18C  and  FIG. 18D , respectively. That is, for the temperature distribution in the vertical direction (y direction) as shown in  FIG. 18C , the temperature is decreased in the vicinity of the center since the laser beams L 11 , L 12  are not irradiated between the slider-side bonding pad  16  and the board-side bonding pad  13 . Further, for the temperature distribution in the lateral direction (X direction), the temperature of the pads positioned on the outer side is high since the intensities of the laser beams L 11 , L 12  are controlled by each irradiating position as described above, and the temperature becomes lower as the position of the pad comes closer to the center.  
      The reason for controlling the intensities of the laser beams in the manner as described above is that the temperature required for each of the pads  13 ,  16  differs in accordance with the positions of the bonding pads  13 ,  16  and the incident angle of the laser beams. For example, thee temperature is kept within the pad in the vicinity of the center, so chat soldering can be achieved with a smaller amount of heat compared to the pads on the outer side.  
      While controlling the intensities of the laser beams by using the above-described nozzle  2 , irradiation of the laser beams is carried cut for heating the pads before melting the solder, then melting the solder, and diffusing the gold thereafter. With this, each of the bonding pads  13 ,  16  can be heated before the solder is melted and, at this time, excessive heating of the area other than the bonding pads  13 ,  16 , e.g. the magnetic head slider part  15  of the magnetic head slider  14  and the FPC  12  of the flexure  11 , can be suppressed. Thus, damages thereof can be prevented. Furthermore, the heat applied to the bonding pads  13 ,  16  after melting the solder can promote dispersion of the gold from the vicinity of the bonding pads  13 ,  16  to the molten solder. At the time of performing a series of heating described above, a proper amount of heat can be applied by the laser beams in accordance with the positions of each of the bonding pads  13 ,  16 , so that the excessive heating can be suppressed further.  
      Control of the intensities of the laser beams L 11 , L 12  for each of the bonding pads  13 ,  16  performed by the controller  3  is not limited to the above-described one. It is noted here that the bonding pad  13  (on the magnetic head slider  14  side) to which the laser beam L 12  is irradiated tends to exhibit a high endothermic effect because the magnetic head slider  14  serves as a heat sink. In other words, due to the heat-sink effect of the magnetic head slider  14 , the bonding pad  16  is more likely to release the heat. Thus, it is not easily heated up compared to the bonding pad  13 . Based on this, it may be controlled to irradiate the laser beam L 12  with higher intensity than that of the laser beam L 11 , for example. With this, the amount of heat necessary For the respective junction areas can be applied within the same irradiation time, so that the solder bonding can be achieved simultaneously and uniformly.  
     Seventh Embodiment  
      Next, a seventh embodiment of the present invention will be described by referring to  FIG. 19 .  FIG. 19  shows a magnetic disk device  50  according to this embodiment.  
      As described above, by soldering the magnetic head slider  14  to the suspension  11  through the soldering method according to the present invention, failure of the magnetic head slider  14  can be suppressed and highly reliable solder bonding can be achieved. Therefore, by manufacturing the magnetic disk device  50  having the above-described head gimbal assembly  1  mounted thereon, it is possible to achieve the conditions such as high reliability and high quality that are required for the magnetic disk device.  
      The soldering method and the soldering apparatus according to the present invention can be utilized for soldering the electronic components that require highly reliable solder bonding. Thus, it has the industrial applicability.