Patent Publication Number: US-2009231758-A1

Title: Head suspension unit and head suspension assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a head suspension assembly incorporated in a storage apparatus such as a hard disk drive, HDD, for example. 
     2. Description of the Prior Art 
     A head suspension is well known as disclosed in Japanese Patent Application Publication No. 2004-95076, for example. The head suspension includes a base plate attached to the front or tip end of a carriage arm. Swaging technique is employed to attach the base plate. A load beam is coupled to the base plate. A hinge plate is utilized to couple the load beam. A flexure is attached to the surface of the load beam. A head slider is mounted on the flexure within a region received on the load beam. 
     The flexure includes a stainless steel plate. Wiring patterns are formed on the stainless steel plate. The flexure extends from the trailing end of the head slider to the rear end of the load beam. The flexure further extends outward from the contour of the load beam to the supported end of a carriage along the side of the carriage arm. The flexure is received in a groove formed in the side of the carriage arm. Electric connection is in this manner established between the head slider and a head IC (integrated circuit) on the supported end of the carriage through the wiring patterns on the stainless steel plate. 
     A cylindrical boss of the base plate is received in a through hole, defining a columnar hollow space, formed in the carriage arm for the attachment of the head suspension to the base plate. The base plate and the carriage arm are firmly held between predetermined jigs. A relatively large urging force is applied to the base plate against the carriage arm. A ball is then pushed into the cylindrical boss. The ball has the diameter larger than the inner diameter of the cylindrical boss, so that the cylindrical boss is forced to plastically deform to closely contact the inner wall surface of the through hole. In this manner, the head suspension is coupled to the carriage arm. 
     The base plate is urged against the carriage arm with a relatively large urging force for the alignment with a higher accuracy when the head suspension is attached to the carriage arm. It is thus required to maximize the contact area between the jig and the base plate. On the other hand, it is preferable to reduce the area of the flexure outside the contour of the load beam for reduction in vibration of the flexure. Vibration of the flexure results in deterioration of accuracy in positioning the head slider. Accordingly, the flexure preferably extends outward from the contour of the base plate at the position as close as possible to the rear end of the base plate. 
     However, the flexure has to extend outward from the contour of the load beam at a position forward from the front end of the base plate so as to ensure a sufficiently large contact area between the jig and the base plate. Vibration of the flexure is inevitable outside the contour of the load beam. On the other hand, in the case where the flexure extends outward from the contour of the base plate at a position closer to the rear end of the base plate, it is impossible to ensure a sufficiently large contact area between the jig and the base plate. Trade-off should be considered between suppression of vibration of the flexure and the establishment of a larger contact area between the jig and the base plate. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide a head suspension unit and a head suspension assembly contributing to establishment of a sufficiently large contact area between a jig and a base plate with a flexure enjoying suppression of vibration outside the contour of the base plate. 
     There is provided a head suspension unit comprising: a base plate; a load beam coupled to the front end of the base plate; a groove formed on the surface of the base plate; and a flexure extending from the load beam and received in the groove of the base plate, the flexure extending outward from the contour of the base plate. 
     The head suspension unit enables reception of the flexure in the groove over an area received on the base plate. The flexure is thus allowed to extend outward from the contour of the base plate at a position closest to the rear end of the base plate. The area of the flexure is significantly reduced outside the contour of the base plate as compared with the case where the flexure extends outward from the contour of the base plate at a position closer to the front end of the base plate. Vibration of the flexure is suppressed. 
     Moreover, the flexure is received in the groove in the course of attachment of the head suspension unit. The flexure is contained in a hollow space defined between the groove and an imaginary plane including the surface of the base plate. Even when a jig is urged against the base plate, the flexure is reliably prevented from being damaged. Simultaneously, a sufficiently large contact area is ensured between the base plate and the jig. A sufficient urging force can thus be applied to the base plate from the jig against the surface of the carriage arm. Misalignment or shift of position is prevented between the base plate, namely the head suspension unit, and the carriage arm. 
     The groove reaches the contour of the base plate at the rear end of the base plate in the head suspension unit. The flexure is thus allowed to extend outward from the contour of the base plate at the rear end of the base plate. The area of the flexure is further reduced outside the contour of the base plate, namely the carriage arm. Vibration of the flexure is further suppressed. 
     The groove extends symmetrically relative to the longitudinal centerline of the base plate. When the base plate is urged against the surface of the carriage arm, the urging force is uniformly applied to the entire surface of the base plate from a jig. Uneven warp or twist of the base plate is reliably prevented. 
     The base plate has a first surface and a second surface at the backside of the first surface in the head suspension unit. The base plate receives the load beam on the first surface. The groove is formed on the second surface No groove is formed on the first surface of the base plate in the head suspension unit. The jig is allowed to contact with the entire first surface of the base plate. A larger urging force is allowed to act on the base plate from the jig. Moreover, as compared with the case where the flexure is located on the surface of the base plate, the flexure is allowed to extend outward from the contour of the base plate at a position closer to the surface of the carriage arm. A difference in level is reduced between the groove formed in the side of the carriage arm and the flexure, for example. The flexure can thus be received in the groove of the carriage arm in a relatively facilitated manner. This results in improvement of efficiency in the assembling process of a carriage. 
     The head suspension unit may further comprise a hinge plate coupling the base plate to the load beam. 
     There is provided a head suspension assembly comprising: a base plate; a load beam coupled to the front end of the base plate; a groove formed on the surface of the base plate; a flexure extending from the load beam and received in the groove of the base plate, the flexure extending outward from the contour of the base plate; and a head slider mounted on the surface of the flexure on the load beam. The head suspension assembly is allowed to enjoy the advantages identical to those obtained in the aforementioned head suspension unit. 
     There is provided a carriage comprising: a carriage block supported on a support shaft for relative rotation; a carriage arm defined in the carriage block, the carriage arm extending forward; a base plate attached to the front end of the carriage arm; a load beam coupled to the front end of the base plate, the load beam extending forward from the front end of the base plate; a groove formed in the surface of the base plate; a flexure extending from the load beam and received in the groove of the base plate, the flexure extending outward from a contour of the base plate; and a head slider mounted on the surface of the flexure on the load beam. The carriage is allowed to enjoy the advantages identical to those obtained in the aforementioned head suspension unit. The carriage may be incorporated in a storage apparatus. 
     There is provided a head suspension unit comprising: a base plate; a load beam coupled to the front end of the base plate; a flexure body extending on the load beam and the base plate, the flexure body extending outward from the contour of the base plate; a groove formed on the surface of the flexure body on the base plate; and a wiring pattern formed on the surface of the flexure body, the wiring pattern received in the groove on the base plate. 
     The head suspension unit enables establishment of the groove on the surface of the flexure body in an area received on the base plate. The wiring pattern is received in the groove of the flexure body on the base plate. The wiring pattern is thus allowed to extend outward from the contour of the base plate at a position closer to the rear end of the base plate. As compared with the case where the wiring pattern extends outward from the contour of the base plate at a position closer to the front end of the base plate, the area of the wiring pattern, namely the area of the flexure body, is significantly reduced outside the contour of the base plate. Vibration of the flexure body is suppressed. 
     Moreover, the wiring pattern is received in the groove in the course of attachment of the head suspension unit. Even when a jig is urged against the surface of the flexure body on the base plate, the wiring pattern is reliably prevented from being damaged. Simultaneously, a sufficiently large contact area is ensured between the flexure body and the jig. A sufficient urging force can be applied to the flexure body and the base plate from the jig against the surface of the carriage arm. Misalignment of shift of position is prevented between the base plate, namely the head suspension unit, and the carriage arm. 
     There is provided a head suspension assembly comprising: a base plate; a load beam coupled to the front end of the base plate; a flexure body extending on the load beam and the base plate, the flexure body extending outward from the contour of the base plate; a groove formed on the surface of the flexure body on the base plate; a wiring pattern formed on the surface of the flexure body, the wiring pattern received in the groove on the base plate; and a head slider mounted on the surface of the flexure body on the load beam. The head suspension assembly is allowed to enjoy the advantages identical to those obtained in the aforementioned head suspension unit. 
     There is provided a head suspension unit comprising: a base plate; a load beam distanced forward from the front end of the base plate at a predetermined interval; a hinge plate attached to the base plate and the load beam; a groove formed on the surface of the hinge plate on the base plate; and a flexure extending on the load beam and the base plate and received in the groove of the hinge plate, the flexure extending outward from the contour of the base plate. 
     The head suspension unit enables establishment of the groove on the surface of the hinge plate in an area received on the base plate. The flexure is received in the groove of the hinge plate on the base plate. The flexure is thus allowed to extend outward from the contour of the base plate at a position closer to the rear end of the base plate. As compared with the case where a wiring pattern extends outward from the contour of the base plate at a position closer to the front end of the base plate, the area of the flexure is significantly reduced outside the contour of the base plate. Vibration of the flexure is suppressed. 
     Moreover, the flexure is received in the groove in the course of attachment of the head suspension unit. Even when a jig is urged against the surface of the hinge plate on the base plate, the flexure is reliably prevented from being damaged. Simultaneously, a sufficiently large contact area is ensured between the hinge plate and the jig. A sufficient urging force can be applied to the hinge plate and the base plate from the jig against the surface of the carriage arm. Misalignment of shift of position is prevented between the base plate, namely the head suspension unit, and the carriage arm. 
     There is provided a head suspension assembly comprising: a base plate; a load beam distanced forward from the front end of the base plate at a predetermined interval; a hinge plate attached to the base plate and the load beam; a groove formed on the surface of the hinge plate on the base plate; a flexure extending on the load beam and the base plate and received in the groove of the hinge plate, the flexure extending outward from the contour of the base plate; and a head slider mounted on the surface of the flexure on the load beam. The head suspension assembly is allowed to enjoy the advantages identical to those obtained in the aforementioned head suspension unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiment in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a plan view schematically illustrating the inner structure of a hard disk drive, HDD, as a specific example of an electronic apparatus according to the present invention; 
         FIG. 2  is a plan view schematically illustrating a head suspension assembly according to a first embodiment of the present invention; 
         FIG. 3  is a partial sectional view schematically illustrating the head suspension assembly; 
         FIG. 4  is a sectional view taken along the line  4 - 4  in  FIG. 2 ; 
         FIG. 5  is a sectional view schematically illustrating the process of attaching the head suspension assembly to a carriage arm; 
         FIG. 6  is a plan view schematically illustrating a head suspension assembly according to a second embodiment of the present invention; 
         FIG. 7  is a plan view schematically illustrating a head suspension assembly according to a third embodiment of the present invention; 
         FIG. 8  is a sectional view taken along the line  8 - 8  in  FIG. 7 ; 
         FIG. 9  is a plan view schematically illustrating a head suspension assembly according to a fourth embodiment of the present invention; 
         FIG. 10  is a sectional view taken along the line  10 - 10  in  FIG. 9 ; 
         FIG. 11  is a plan view schematically illustrating a head suspension assembly according to a fifth embodiment of the present invention; 
         FIG. 12  is a plan view schematically illustrating a head suspension assembly according to a sixth embodiment of the present invention; and 
         FIG. 13  is a sectional view taken along the line  13 - 13  in  FIG. 12 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  schematically illustrates the structure of a hard disk drive, HDD,  11  as an example of a storage medium drive or a storage apparatus according to the present invention. The hard disk drive  11  includes an enclosure  12 . The enclosure  12  includes a box-shaped base  13  and a cover, not shown. The base  13  defines an inner space in the form of a flat parallelepiped, for example. The base  13  may be made of a metallic material such as aluminum, for example. Molding process may be employed to form the base  13 . The cover is coupled to the opening of the base  13 . A closed space is defined between the base  13  and the cover. Pressing process may be employed to form the cover out of a plate material, for example. 
     At least one magnetic recording disk  14  as a storage medium is enclosed in the enclosure  12 . The magnetic recording disk or disks  14  are mounted on the driving shaft of a spindle motor  15 . The spindle motor  15  drives the magnetic recording disk or disks  14  at a higher revolution speed such as 5,400 rpm, 7,200 rpm, 10,000 rpm, 15,000 rpm, or the like. 
     A carriage  16  is also enclosed in the enclosure  12 . The carriage  16  includes a carriage block  17 . The carriage block  17  is supported on a vertical support shaft  18  for relative rotation. Carriage arms  19  are defined in the carriage block  17 . The carriage arms  19  extend in the horizontal direction from the vertical support shaft  18 . The carriage block  17  may be made of aluminum, for example. Extrusion molding process may be employed to form the carriage block  17 , for example. 
     A head suspension assembly  21  is attached to the front or tip end of the individual carriage arm  19 . The head suspension assembly  21  includes a head suspension  22 . The head suspension  22  extends forward from the tip end of the carriage arm  19 . A flying head slider  23  is supported on the front or tip end of the head suspension  22 . A head element or electromagnetic transducer is mounted on the flying head slider  23 . 
     When the magnetic recording disk  14  rotates, the flying head slider  23  is allowed to receive airflow generated along the rotating magnetic recording disk  14 . The airflow serves to generate a positive pressure or a lift as well as a negative pressure on the flying head slider  23 . The lift is balanced with the negative pressure and the urging force from the head suspension  22  during the rotation of the magnetic recording disk  14 . The flying head slider  23  is thus allowed to keep flying above the surface of the magnetic recording disk  14  at a higher stability. 
     When the carriage  16  swings around the vertical support shaft  18  during the flight of the flying head slider  23 , the flying head slider  23  is allowed to move along the radial direction of the magnetic recording disk  14 . The electromagnetic transducer on the flying head slider  23  is allowed to cross the data zone defined between the innermost recording track and the outermost recording track. The electromagnetic transducer on the flying head slider  23  can thus be positioned right above a target recording track on the magnetic recording disk  14 . 
     A power source such as a voice coil motor, VCM,  24  is connected to the carriage block  17 . The voice coil motor  24  serves to drive the carriage block  17  around the vertical support shaft  18 . The rotation of the carriage block  17  allows the carriage arms  19  and the head suspensions  22  to swing. 
     As is apparent from  FIG. 1 , a flexible printed circuit board unit  25  is placed on the carriage block  17 . The flexible printed circuit board unit  25  includes a head IC (integrated circuit)  27  mounted on a flexible printed wiring board  26 . The head IC  27  is designed to supply the read element of the electromagnetic transducer with a sensing current when the magnetic bit data is to be read. The head IC  27  is also designed to supply the write element of the electromagnetic transducer with a writing current when the magnetic bit data is to be written. 
     A small-sized circuit board  28  is placed within the inner space of the enclosure  12 . A printed wiring board, not shown, is attached to the backside of the bottom plate of the base  13 . The head IC  27  receives the sensing current and the writing current from the small-sized circuit board  28  or the printed wiring board on the bottom plate through the small-sized circuit board  28 . A flexure  29  is utilized to relay the sensing current and the writing current to the electromagnetic transducer. One end of the flexure  29  is connected to the flexible printed circuit board unit  25 . The flexure  29  extends along the side of the carriage arm  19 . The other end of the flexure  29  is attached to the head suspension  22 . 
       FIG. 2  schematically illustrates the head suspension assembly  21  according to a first embodiment of the present invention. The head suspension assembly  21  includes a base plate  31  and a load beam  32 . The base plate  31  is attached to the tip end of the carriage arm  19 . The load beam  32  is distanced forward from the base plate  31  at a predetermined interval. A hinge plate  33  is fixed to the surfaces of the base plate  31  and the load beam  32 . The hinge plate  33  provides an elastic bending section  34  between the front end of the base plate  31  and the rear end of the load beam  32 . The hinge plate  33  in this manner serves to couple the base plate  31  with the load beam  32 . Each of the base plate  31 , the load beam  32  and the hinge plate  33  is made out of a thin plate of stainless steel, for example. 
     The base plate  31 , the load beam  32  and the hinge plate  33  in combination establish the head suspension  22 . The aforementioned flexure  29  is attached to the front surface of the head suspension  22 . The flexure  29  includes a flexure body, namely a stainless steel plate  35 . The stainless steel plate  35  includes a support plate  36  and a fixation plate  37 . The flying head slider  23  is received on the surface of the support plate  36 . The fixation plate  37  is attached to the surfaces of the load beam  32  and the hinge plate  33 . Spot welding may be effected at joint spots so as to fix the fixation plate  37 , for example. The flying head slider  23  is bonded to the surface of the support plate  36 . The support plate  36  and the fixation plate  37  are made out of a single thin plate of stainless steel. 
     A wiring pattern set  38  is formed on the surface of the fixation plate  37 . One end of the wiring pattern set  38  is connected to the flying head slider  23 . The wiring pattern set  38  includes a pair of wiring patterns  38   a  related to the read element and a pair of wiring patterns  38   b  related to the write element, for example. The fixation plate  37  is bifurcated on the hinge plate  33 , for example. The bifurcated portions of the fixation plate  37  are respectively received in two grooves  39  formed on a first surface of the base plate  31 , namely the front surface of the base plate  31 . A through hole  41  penetrates through the base plate  31  from the front surface to the back surface of the base plate  31  at a position between the grooves  39 . The grooves  39  are thus formed on the base plate  31  at both sides of the longitudinal centerline of the base plate  31 , respectively. The individual groove  39  reaches the contour of the base plate  31  at the side of the base plate  31 . The wiring patterns  38   a  and the wiring patterns  38   b  are formed in the bifurcated portions of the fixation plate  37 , which are received in the grooves  39 , respectively. One of etching process, stamping process and cutting process may be applied to the base plate  31  so as to form the grooves  39 , for example. 
     The fixation plate  37  extends outward from the contour of the base plate  31  at the side of the base plate  31 . The fixation plate  37  is bent at right angles at a position outside the contour of the base plate  31 . The fixation plate  37  thus extends to the flexible printed circuit board unit  25  along the side of the carriage arm  19 . The fixation plate  37  is received in a groove  42  formed in the side of the carriage arm  19 . The head suspension assembly  21  in this manner has the structure of a so-called long tail. The other end of the wiring pattern set  38  is connected to the head IC  27 . Electrical connection is thus established between the flying head slider  23  and the head IC  27 . The base plate  31 , the load beam  32 , the hinge plate  33  and the flexure  29  in combination establish a head suspension unit according to the present invention. 
     As shown in  FIG. 3 , a second surface of the base plate  31 , namely the back surface of the base plate  31 , is received on the front surface of the carriage arm  19 . The base plate  31  includes a cylindrical boss  43  standing upright from the back surface of the base plate  31  around the aforementioned through hole  41 . The cylindrical boss  43  serves to define the aforementioned through hole  41  inside. The cylindrical boss  43  is received in a through hole  44  defined in the tip end of the carriage arm  19 . The through hole  44  penetrates through the carriage arm  19  from the front surface to the back surface of the carriage arm  19 . The cylindrical boss  43  of the base plate  31  is urged against the inner wall surface of the through hole  44  based on swaging process. The swaging process will be described later in detail. The base plate  31  is in this manner fixed to the carriage arm  19 . 
     The support plate  36  of the flexure  29  is received on a domed swelling, not shown, formed on the surface of the load beam  32  behind the flying head slider  23 . The aforementioned elastic bending section  34  is designed to exhibit elasticity or bending force of a predetermined intensity. The bending force is utilized to provide the front end of the load beam  32  with the aforementioned urging force toward the surface of the magnetic recording disk  14 . The domed swelling behind the flying head slider  23  serves to apply the urging force to the flying head slider  23 . The flying head slider  23  is allowed to enjoy a change in its flying attitude based on the lift generated based on airflow. The domed swelling accepts a change in the attitude of the flying head slider  23 , namely the support plate  36 . 
     As shown in  FIG. 4 , the flexure  29 , namely the wiring pattern set  38 , is located in the grooves  39  on the base plate  31 . The flexure  29  is contained in the hollow spaces defined between the grooves  39  and an imaginary plane including the front surface of the base plate  31 , respectively. The fixation plate  37  of the flexure  29  is fixed to the bottom surfaces of the grooves  39 . An adhesive may be utilized to fix the fixation plate  37 . It should be noted that spot welding may alternatively be employed to fix the fixation plate  37  to the bottom surfaces of the grooves  39 . The wiring pattern set  38  includes an insulating layer  46 , an electrically-conductive layer  47  and a protection layer  48 , overlaid on the fixation plate  37  in this sequence, for example. The electrically-conductive layer  47  is made of an electrically-conductive material such as copper, for example. The insulating layer  46  and the protection layer  48  are made of a resin material such as polyimide resin, for example. 
     The flexure  29  is received in the grooves  39  on the base plate  31  in the head suspension assembly  21 . The flexure  29  is thus allowed to extend outward from the contour of the base plate  31  at a position closest to the rear end of the base plate  31 . The area of the flexure  29  is significantly reduced outside the contour of the base plate  31  as compared with the case where a flexure extends outward from the contour of the hinge plate  33  at a position forward from the base plate  31 , for example. Vibration of the flexure  29  is suppressed. The flying head slider  23  can be positioned with a higher accuracy. In addition, since the through hole  41  allows the wiring patterns  38   a ,  38   b  to be distanced from each other on the base plate  31 , transmission of noise is prevented between the wiring patterns  38   a ,  38   b.    
     Next, description will be made on a method of making the carriage  16 . The carriage block  17  is first prepared. The head suspension assembly  21  has already been assembled. The flexure  29  is located in the grooves  39  positioned on the base plate  31 . As shown in  FIG. 5 , the cylindrical boss  43  of the base plate  31  is received in the through hole  44  of the carriage arm  19 . A circular flange  49  is formed in the inner wall surface of the cylindrical boss  43 . The flange  49  protrudes into the through hole  41 . The base plate  31  and the carriage arm  19  are interposed between the flattened surfaces of jigs  51 . The base plate  31  is in this manner urged against the front surface of the carriage arm  19 . Since the flexure  29  is received in the grooves  39 , the wiring pattern set  38  is prevented from suffering from damages resulting from the urging force applied from the jigs  51 . 
     A ball  52  for swaging process is pushed into the through hole  41  of the base plate  31  while the jigs  51  are kept urged. The diameter of the ball  52  is set slightly larger than the inner diameter of the through hole  41 . When the ball  52  is pushed into the through hole  41 , the through hole  41  receives an outward force in the radial direction so that the through hole  41  expands. The flange  49  is squashed against the inner wall surface of the through hole  44  of the carriage arm  19 . The flange  49  is thus forced to plastically deform. The plastic deformation of the flange  49  results in establishment of the cylindrical boss  43 . The cylindrical boss  43  is firmly fixed in the through hole  44  of the carriage arm  19 . The head suspension assembly  21  is fixed to the tip end of the carriage arm  19 . In this manner, the carriage  16  is produced. 
     The method enables reception of the wiring pattern set  38  in the grooves  39 . The wiring pattern set  38  is completely contained in the hollow spaces defined between the grooves  39  and the imaginary plane including the front surface of the base plate  31 . Even when the flattened surface of the jig  51  is urged against the base plate  31 , the wiring pattern  38  is reliably prevented from being damaged. Simultaneously, a sufficiently large contact area is ensured between the base plate  31  and the jig  51 . A sufficient urging force is applied to the base plate  31  against the front surface of the carriage arm  19  from the jig  51 . A misalignment or shift of position is prevented between the base plate  31 , namely the head suspension assembly  21 , and the carriage arm  19 . 
     The grooves  39  are formed at both sides of the longitudinal centerline of the base plate  31 , respectively. When the jig  51  is applied, the contact area is equalized on the base plate  31  as much as possible between both sides of the longitudinal centerline of the base plate  31  as compared with the case where the groove  39  is formed around the through hole  41  on one side of the longitudinal centerline of the base plate  31 . The urging force applied from the jig  51  to the entire surface of the base plate  31  is thus balanced as much as possible between both sides of the longitudinal centerline around the through hole  41 . Warp or twist of the base plate  31  is prevented. The head suspension assembly  21  can thus be attached to the carriage arm  19  as designed or expected. 
       FIG. 6  schematically illustrates a head suspension assembly  21   a  according to a second embodiment of the present invention. The head suspension assembly  21   a , includes the grooves  39  reaching the contour of the base plate  31  at the rear end of the base plate  31 . The grooves  39  are thus allowed to extend on the base plate  31  symmetrically with each other relative to the longitudinal centerline of the base plate  31 . The flexure  29  extends outward from the contour of the base plate  31  at the rear end of the base plate  31 . Here, the flexure  29  may be attached to the front surface of the carriage arm  19  at a position backward from the rear end of the base plate  31 . An adhesive may be utilized to attach the flexure  29 , for example. Like reference numerals are attached to the structure or components equivalent to those of the aforementioned head suspension assembly  21 . 
     The grooves  39  are formed on the base plate  31  symmetrically with each other relative to the longitudinal centerline of the base plate  31  in the head suspension assembly  21   a . When the base plate  31  is urged against the front surface of the carriage arm  19 , the urging force of the jig  51  uniformly acts on the entire surface of the base plate  31 . Warp or twist of the base plate  31  is reliably prevented. Moreover, the flexure  29  extends outward from the contour of the base plate  31  at the rear end of the base plate  31 . The area of the flexure  29  is further reduced outside the contour of the base plate  31 , namely the carriage arm  19 . Vibration of the flexure  29  is further suppressed. 
       FIG. 7  schematically illustrates a head suspension assembly  21   b  according to a third embodiment of the present invention. The flexure  29  is located between the carriage arm  19  and the base plate  31  in the head suspension assembly  21   b . As shown in  FIG. 8 , the grooves  39  are formed on the back surface of the base plate  31 . The grooves  39  may extend in the same manner as described above. The flexure  29 , namely the wiring pattern set  38 , is received in the grooves  39 . The flexure  29  may be attached to the bottom surfaces of the grooves  39 . An adhesive is utilized to attach the flexure  29 , for example. The grooves  39  may extend from the front end to the rear end of the base plate  31 . Like reference numerals are attached to the structure or components equivalent to those of the aforementioned head suspension assemblies  21 ,  21   a.    
     The grooves  39  are not formed in the front surface of the base plate  31 . The front surface of the base plate  31  is thus allowed to entirely contact with the flattened surface of the jig  51 . A larger urging force can be applied to the base plate  31  from the jig  51 . Moreover, the flexure  29  extends outward from the contour of the side of the base plate  31  at a position closer to the front surface of the carriage arm  19  as compared with the case where the flexure  29  is located on the front surface of the base plate  31 . A difference in level is reduced between the flexure  29  and the groove formed in the side of the carriage arm  19 . The flexure  29  can thus be received in the groove of the carriage arm  19  in a relatively facilitated manner. This results in improvement of efficiency in the assembling process of the carriage  16 . The head suspension assembly  21   b  is allowed to enjoy the advantages identical to those obtained in the aforementioned head suspension assemblies  21 ,  21   a.    
       FIG. 9  schematically illustrates a head suspension assembly  21   c  according to a fourth embodiment of the present invention. The fixation plate  37  of the flexure  29  extends on the base plate  31 . Spot welding is employed to fix the fixation plate  37  on the front surface of the base plate  31 , for example. The aforementioned grooves  39  are formed not on the front surface of the base plate  31  but on the surface of the fixation plate  37  of the flexure  29  within an area received on the base plate  31 . The grooves  39  may extend in the same manner as described above. The wiring pattern set  38  is located in the grooves  39 . Etching may be effected on the fixation plate  37  so as to form the grooves  39 , for example. 
     As shown in  FIG. 10 , the wiring pattern set  38  is contained in the hollow spaces defined between the grooves  39  and an imaginary plane including the surface of the flexure  29  on the base plate  31 . The front surface of the base plate  31  is exposed within the grooves  39 . The bottom surfaces of the grooves  39  are defined in the front surface of the base plate  31 . The wiring pattern set  38  is attached to the front surface of the base plate  31  within the grooves  39 . An adhesive is utilized to attach the wiring pattern set  38 , for example. Like reference numerals are attached to the structure or components equivalent to those of the aforementioned head suspension assemblies  21 ,  21   a ,  21   b . The head suspension assembly  21   c  is allowed to enjoy the advantages identical to those obtained in the aforementioned embodiments. 
       FIG. 11  schematically illustrates a head suspension assembly  21   d  according to a fifth embodiment of the present invention. The structure of the head suspension assembly  21   d  is identical to that of the head suspension assembly  21   c  except that the hinge plate  33  is replaced with the fixation plate  37  of the flexure  29 . In other words, the elastic bending section  34  is formed in the fixation plate  37 . The base plate  31  and the load beam  32  are coupled to each other through the fixation plate  37 . Like reference numerals are attached to the structure or components equivalent to those of the aforementioned head suspension assemblies  21 ,  21   a ,  21   b ,  21   c . The head suspension assembly  21   d  is allowed to enjoy the advantages identical to those obtained in the aforementioned embodiments. 
       FIG. 12  schematically illustrates a head suspension assembly  21   e  according to a sixth embodiment of the preset invention. The hinge plate  33  extends on the base plate  31  in the head suspension assembly  21   e . Spot welding is employed to fix the hinge plate  33  to the front surface of the base plate  31 , for example. The grooves  39  are formed in the hinge plate  33  within an area received on the base plate  31 . The wiring pattern set  38  is located in the grooves  39 . Etching may be effected on the hinge plate  33  to form the grooves  39 , for example. The fixation plate  37  is omitted in the flexure  29  on the hinge plate  33 . 
     As shown in  FIG. 13 , the wiring pattern set  38  is contained in the hollow spaces defined between the grooves  39  and an imaginary plane including the front surface of the hinge plate  33  within an area received on the base plate  31 . The wiring pattern set  38  is attached to the bottom surfaces of the grooves  39  within the grooves  39 . An adhesive is utilized to attach the wiring pattern set  38 , for example. Like reference numerals are attached to the structure or components equivalent to those of the aforementioned head suspension assemblies  21 ,  21   a ,  21   b ,  21   c ,  21   d . The head suspension assembly  21   e  is allowed to enjoy the advantages identical to those obtained in the aforementioned embodiments. It should be noted that the fixation plate  37  may be extend on the hinge plate  33  within the grooves  39 . In this manner, the wiring pattern  38  may be received on the fixation plate  37  within the grooves  39 . 
     The head suspension assemblies  21 - 21   e  may include a viscoelastic body may be filled in the grooves  39 . The viscoelastic body serves to prevent vibration of the wiring pattern set  38  and the flexure  29  with a higher reliability. The flying head slider  23  can be positioned with a higher accuracy.