Patent Publication Number: US-2009237843-A1

Title: Magnetic head assembly and storage apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2008-76683, filed on Mar. 24, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are directed to a magnetic head assembly and a storage apparatus. More specifically, the present invention relates to a magnetic head assembly having terminals attached on one of the surfaces thereof excluding a surface with which the magnetic head is attached onto a suspension, and to the storage apparatus having the magnetic head assembly. 
     BACKGROUND 
     Storage apparatuses such as magnetic disk apparatuses have magnetic head assemblies. The magnetic head assembly has a suspension, and the suspension has a magnetic head on its tip. The suspension is provided with wires and each a first end of each wires connects with a signal processor and a second end of each wires connects with one of a plurality of terminals. The magnetic head is attached on a head slider having a tracking surface, or an air bearing surface (ABS), that flies over a recording surface of a magnetic disk in reading and writing signals and a fixed surface formed on the opposite side of the ABS, with which the head slider is fixed to the suspension. On one of the surfaces of the head slider excluding the ABS and the fixed surface, a plurality of terminals are attached that connect with terminals attached on the suspension electrically. 
       FIG. 1  is a side view illustrating a portion of a conventional magnetic head assembly. As illustrated in  FIG. 1 , the magnetic head assembly has a head slider  1  and a suspension  2 . The head slider  1  has an ABS  11 , a fixed surface  12  and a lateral side  13 . On the lateral side  13 , a plurality of terminals  14  are attached. The fixed surface  12  of the head slider  1  is attached onto an upper surface, or an attachment surface, of the suspension  2  with, for example, adhesive  3 . Each of a plurality of terminals  24  attached onto the upper surface of the suspension  2  connects with a correspondent terminal  14  attached on the head slider  1  with solder. 
     With downsizing of the magnetic disk apparatuses, the magnetic head assemblies are miniaturized. As the magnetic head assemblies become smaller, the terminals attached on the head sliders and the suspensions become miniscule. There has been a technique for controlling a flying height of the magnetic head from a magnetic disk by controlling a heater embedded in the magnetic head to deal with the increasing recording density. For the magnetic head having the heaters, the terminals attached onto the head slider and the suspension are increased by an amount equal to the number of the heaters. Consequently, the terminals become more and more minuscule due to the decrease of the terminals in size and the increase of the terminals in quantity. 
     The technique to attach the head slider onto the attachment surface of the suspension with solder and to connect the terminals with solder electrically has been disclosed in patent literature 1 (Japanese Unexamined Patent Application Publication No. S63-113918). The technique to circumvent constraints on a rotational movement of the head slider has been proposed in patent literature 2 (Japanese Unexamined Patent Application Publication No. H8-31127). 
     Conventionally, an exposed area of the solder applied for connecting the terminals on the head slider with the terminals on the suspension electrically is relatively large, which increases a probability of the solder chip off. 
     SUMMARY 
     An an aspect of embodiments of the present invention is to provide a magnetic head assembly and a storage apparatus to reduce if not prevent the conductive material materials such as solder for connecting the terminals attached on the head slider with the terminals attached on the suspension electrically from chipping off. 
     In accordance with an aspect of embodiments, a magnetic head assembly, includes a suspension comprising an attachment surface, a bent section that extends generally vertically from the attachment surface and a suspension comprising a first plurality of terminals attached on the bent section and a head slider comprising a tracking surface, a fixed surface provided on an opposite side of the tracking surface, a lateral side that extends generally perpendicularly from the fixed surface and connects the tracking surface with the fixed surface, and a second plurality of terminals attached on the lateral side, wherein the first plurality of terminals is opposed and connected electrically to the correspondent second plurality of terminals, with the fixed surface of the head slider fixed onto the attachment surface of the suspension. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view illustrating a portion of the conventional magnetic head assembly; 
         FIGS. 2A through 2D  are the photomicrographs depicting a portion of the exposed area of the solder that connects a pair of the terminals; 
         FIGS. 3A and 3B  are the photomicrographs depicting the adherent matter attached on the head slider incorporated in a failed magnetic disk apparatus; 
         FIG. 4  is a plane view of the magnetic disk apparatus; 
         FIGS. 5A and 5B  illustrate the magnetic head assembly; 
         FIGS. 6A and 6B  illustrate the HGA; 
         FIGS. 7A and 7B  illustrate the attachment surface of the head slider; 
         FIGS. 8A through 8C  illustrate the head slider from three angles; 
         FIG. 9  is a side view of a portion of the magnetic head assembly according to the first embodiment of the present invention; 
         FIG. 10  is a side view illustrating a portion of the magnetic head assembly according to the second embodiment of the present invention; 
         FIG. 11  is a side view illustrating a portion of the magnetic head assembly according to the third embodiment of the present invention; and 
         FIG. 12  is a side view illustrating a portion of the magnetic head assembly according to the fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     For the magnetic head assembly illustrated in  FIG. 1 , the terminals  14  are conventionally connected with the terminals  24  by gold ball bonding (GBB) using solder that is made of gold, Au. However, the miniaturization of the magnetic head assembly and the increase of terminals  14  and  24  in quantity make applying GBB difficult. Thus, solder ball bonding (SBB) is applied instead. For SBB, the solder is made of Pb-free materials in consideration of the effect on the environment. However, the Pb-free solder, in comparison with lead based solder, has lower solderability. Moreover, for the conventional magnetic head assembly, the contact angle of the surfaces on which the terminals  14  and  24  are attached is large, in this case, a substantially a right angle. Therefore, relatively a large amount of the solder is applied thereto, and proportionally the exposed area of the solder is relatively large. 
     The inventors of this invention have found this problem is significant in terms of impacts on performance and reliability of the magnetic disk apparatuses. In  FIG. 2 , photomicrographs depict a portion of the exposed area of the solder  4  connecting a pair of the terminals  14  with  24  illustrated in  FIG. 1 . In  FIG. 2A , the chipped portion of the solder  4  is circled with a white line.  FIG. 2B  is an enlarged image of the circled area illustrated in  FIG. 2A .  FIG. 2C  is an enlarged image of the area labeled as R 1  in  FIG. 2B .  FIG. 2D  is an enlarged image of the area labeled as R 2  in  FIG. 2B . The chip off of the solder  4  is observed in  FIG. 2C . Cracks and cavities are observed in  FIG. 2D . The chip off of the solder  4  may be caused by a stress applied thereto, etc. 
       FIG. 3  is photomicrographs depicting an adherent matter attached on a head slider incorporated in a magnetic disk apparatus that had a failure such as head disk interference (HDI). In  FIG. 3A , a head element on which the adherent matter is attached is circled with a white line.  FIG. 3B  is an enlarged image of the circled area depicted in  FIG. 3A . An analysis of the adherent matter indicates that the adherent matter contains the same content of Sn that is contained in the solder  4 . In many cases, Sn is detected in the adherent matters attached to the head elements incorporated in the failed magnetic disk apparatuses. One of the possible factors is that relatively a large amount of the solder  4  chips off where the solder  4  is exposed in a relatively large area. This suggests that the solder chipped off where the exposed area is large adheres onto the ABS  11  of the head slider  1 , causing the failures such as HDI of the magnetic disk apparatus at a considerable level. 
     In the embodiments disclosed hereinafter, storage apparatuses shall refer to magnetic disk apparatuses using magnetic disks as magnetic storage mediums for the ease of description. 
     Embodiment 1 
       FIG. 4  is the plane view of the magnetic disk apparatus. The basic structure of the magnetic disk apparatus is common through all embodiments disclosed hereinafter. The structure of the magnetic disk apparatus illustrated in  FIG. 4  is a well-known structure, and the other well-known structures are also applicable. 
     A magnetic disk apparatus  31  illustrated in  FIG. 4  has a base  32 , a magnetic head assembly (or a head stack assembly (HSA))  33 , a load-unload mechanism  34 , and a magnetic disk  35 , etc. The magnetic head assembly  33  rotates around a pivot  36 . 
       FIG. 5  illustrates the magnetic head assembly  33 .  FIG. 5A  is a plane view of the magnetic head assembly  33 .  FIG. 5B  is a side view of the magnetic head assembly  33 . The magnetic head assembly  33  illustrated in  FIG. 5  has a head gimbal assembly (HGA)  37 . 
       FIG. 6  illustrates the HGA  37 .  FIG. 6A  is a plane view of the HGA  37 .  FIG. 6B  is a side view of the HGA  37 . The HGA  37  illustrated in  FIG. 6  has a suspension  41 . The suspension  41  has wires  42  and a head slider  43 . 
       FIG. 7  illustrates the attachment surface for attaching the head slider.  FIG. 7A  illustrates the undersurface of the suspension  41 .  FIG. 7B  is a side view of the suspension  41 . The suspension  41  illustrated in  FIG. 7  has an attachment surface  411  for attaching the head slider  43 ; multiple terminals (a first terminal)  412 ; and a flexure  417 . The multiple terminals  412  connect with the second ends of wires  42 , and the first ends of the wires  42  connect with a signal processor, not shown in the accompanied drawings, incorporated in the magnetic disk apparatus  31 . The suspension  41  has a convex portion  418 . The flexure  417  is supported by the suspension  41  at the convex  418 . In this embodiment, the flexure  417  has the attachment surface  411  and the multiple terminals  412 . The head slider  43  attached onto the tip of the suspension  41 , that is the flexure  417 , writes signals onto and read signals from the magnetic disk  35  rotated by a motor not shown in the accompanied drawings. The number of the suspensions  41  and the head sliders  43  attached on the magnetic head assembly  33  is not limited. 
     For convenience, the magnetic head assembly  33  herein is a load-unload type. Thus, the head slider  43  is loaded from a load-unload mechanism  34  to the magnetic disk  35  or unloaded from the magnetic disk  35  to the load-unload mechanism  34  in accordance with operations of the magnetic disk apparatus  31 . As illustrated in  FIG. 7 , a load-unload tab  415  is provided on the tip of the suspension  41  of the magnetic head assembly  33 , which is engageable with the load-unload mechanism  34 . The load-unload tab  415  may be integrally formed with the suspension  41  for example. The load-unload tab  415  is guided along a guide of the load-unload mechanism  34  in loading and unloading. The head slider  43  is retracted into the load-unload mechanism  34  to prevent contact with a recording surface of the magnetic disk  35 . 
       FIG. 8  illustrates the head slider  43  from three views.  FIG. 8A  illustrates the under surface of the head slider  43 .  FIG. 8B  is a front view of the head slider  43 .  FIG. 8C  is a side view of the head slider  43 . When the head slider  43  tracks the magnetic disk  35  from, for example, 10 nm above the recording surface of the magnetic disk  35 , air flows in from the left side of the head slider  43  and flows out from the right side of the head slider  43 . As illustrated in  FIG. 8 , the head slider  43  has a tracking surface ABS  431 , a fixed surface  432  formed on the opposite side of the ABS  431 , a lateral side  433  that perpendicularly extends between the fixed surface  432  and the ABS  431 , a head element  434  attached in the vicinity of the lateral side  433 , and the multiple terminals (second terminals)  435 , attached on the lateral side  433 . 
     For the head slider  43  in the embodiments herein, three pairs of heaters not shown in the accompanied drawings are embedded. The flying height of the ABS  431  of the head slider  43  from the recording surface of the magnetic disk  35  is controlled via the heaters. The control mechanism of the flying height is known, and hence the description is omitted. There are six terminals  435  on the head slider  43  in total: two for signal writing, two for signal reading, and two for heater control. Of the two terminals for the heater control, one also serves as an earthing terminal. There are six correspondent terminals  412  on the suspension  41 . The number of the terminals  412  and  435  are not fixed at six. When no heaters are embedded in the head slider  43 , four terminals may be provided. When the heaters are embedded in the head slider  43 , six or more terminals may be provided corresponding to the number of the heaters. 
       FIG. 9  is a side view illustrating a part of the magnetic head assembly according to the first embodiment of the present invention. As illustrated in  FIG. 9 , the fixed surface  432  of the head slider  43  is attached on the attachment surface  411  of the suspension  41 , or flexure  417 , with adhesive  61 . The adhesive is not limited. For instance, conductive adhesives may be used. The terminals  435  attached on the head slider  43  are electrically connected to the correspondent terminals  412  attached on the suspension  41  with solder  62 . The exposed surface of the solder  62  is covered with insulation  63 . The insulation  63  is not limited. For instance, resin may be used. Preferably, the insulation  63  is made of a material having flexibility. 
     In this embodiment, the solder  62  is covered with the insulation  63  to prevent possible chip off by cracking attributed to stress, etc. 
     Embodiment 2 
       FIG. 10  is a side view illustrating a portion of the magnetic head assembly according to the second embodiment of the present invention. As illustrated in  FIG. 10 , the portions that are common to the portions illustrated in  FIG. 9  are given the same reference numbers and the descriptions are omitted. Through the embodiments 2 to 4 disclosed hereinafter, the structures of the suspension  41  including the flexure  417  are common to the structure in the first embodiment except in that the suspension  41 , or the flexure  417 , has a bent section  43 A or  43 B that perpendicularly extends from the attachment surface  432 . Although there is the difference described above, it is considered unnecessary to illustrate and describe the overall structure of the HGA  37  and the like. 
     As illustrated in  FIG. 10 , the terminals  412  are attached on the bent section  43 A of the suspension  41  with conductive material  65 , opposing the correspondent terminals  435  attached on the head slider  43 . The surfaces of the terminals  412  and  435  are generally parallel to each other. Therefore, the amount of the conductive material  65  used as solder may be reduced compared to the conventional art illustrated in  FIG. 1 . Additionally, since the terminals  412  and  435  are generally parallel and adjacent, the exposed area of the solder may be reduced significantly. Hence, the chip off of the solder may be reduced to a large degree in comparison with the conventional art illustrated in  FIG. 1 . 
     The conductive material  65  is not limited to the solder. There is another method to connect the terminals electrically. The conductive material  65  may be applied to either surface of the terminal  412  or  435  and then heat may be applied from the right side of the bent section  43 A. The conductive material  65  may be coated over the surfaces of the terminals  412  and  435  with a known technique for printing. Alternatively, either of the terminals  412  or  435  may be made of gold and may connect with the correspondent terminals electrically by bonding such as thermocompression or ultrasonic bonding. With this technique, at least one of the terminals is melted and serves as the conductive material  65 . 
     Embodiment 3 
       FIG. 11  is a side view illustrating a portion of the magnetic head assembly according to the third embodiment of the present invention. As illustrated in  FIG. 11 , the portions that are common to the portions illustrated in  FIG. 10  are given the same reference numbers and the descriptions of them are omitted. 
     As illustrated in  FIG. 11 , the terminals  412  attached on the suspension  41  extend over a portion of the attachment surface  411 , and the terminals  435  attached on the head slider  43  extend over a portion of the fixed surface  432 . With this structure, the opposed surfaces of the terminals  412  and  435  are increased compared to the second embodiment illustrated in  FIG. 10 . Therefore, the conductive material  65  is applied between the extended portions of the terminals  412  and  435 , and a more secure electronic connection may be provided. 
     Embodiment 4 
       FIG. 12  is a side view illustrating a portion of the magnetic head assembly according to the fourth embodiment of the present invention. As illustrated in  FIG. 12 , the portions that are common to the portions illustrated in  FIG. 10  are given the same reference numbers and the descriptions of them are omitted. 
     As illustrated in  FIG. 12 , the bent section  43 B of the suspension  41  is in an inverted U-shape. The wires  42  are bent along the inverted U-shape of the bent section  43 B. In other words, the wires  42  may be wired generally parallel with the attachment surface  411  of the suspension  41  even at the bent section  43 B. 
     The magnetic disk apparatus having the structure according to each of the embodiments disclosed herein prevents the chip off of the conductive material materials such as solder for connecting the terminals attached on the head slider with the terminals attached on the suspension electrically. Therefore, the failures such as HDI of the magnetic disk apparatus attributed to the chip off of the conductive material may be reduced if not prevented, and the performance of the magnetic disk apparatus may be improved. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.