Abstract:
A thin film piezoelectric element includes a piezoelectric thin film layer, a seed layer and an elastic substrate layer. The piezoelectric thin film layer is a laminated structure comprising a first electrode layer, a second electrode layer and a piezoelectric layer sandwiched between the first electrode layer and the second electrode layer. The seed layer is formed on the second electrode layer, and the elastic substrate layer is formed on the seed layer. The thin film piezoelectric element is a single layer structure and has an elastic substrate layer for supporting the single layer structure, thereby it has enough stiffness and flexibility to afford facilities for manufacture and assembly and to avoid film peeling and deformation, ultimately increasing the production efficiency and lowering the cost. The invention also discloses a method for manufacturing the thin film piezoelectric element, a head gimal assembly and a disk drive unit with the same.

Description:
This application claims priority to Japanese Application No. 200810125022.5, filed Jun. 23, 2008, the entire contents of which are hereby incorporated by reference in this application. 
     FIELD OF THE INVENTION 
     The present invention relates to an information recording disk drive unit, and more particularly to a thin film piezoelectric element and its manufacture method, a head gimbal assembly and a disk drive unit with the same. 
     BACKGROUND OF THE INVENTION 
     One known type of information storage device is a disk drive device that uses magnetic media to store data and a movable read/write head that is positioned over the magnetic media to selectively read from or write to the rotating magnetic media, such as a magnetic disk. 
     Consumers are constantly desiring greater storage capacity for such disk drive devices, as well as faster and more accurate reading and writing operations. Thus disk drive manufacturers have continued to develop higher capacity disk drives by, for example, increasing the recording and reproducing density of the information tracks on the disks by using a narrower track width and/or a narrower track pitch. However, each increase in track density requires that the disk drive device have a corresponding increase in the positional control of the read/write head in order to enable quick and accurate reading and writing operations using the higher density disks. As track density increases, it becomes more and more difficult to quickly and accurately position the read/write head over the desired information tracks on the disk. Thus, disk drive manufacturers are constantly seeking ways to improve the positional control of the read/write head in order to take advantage of the continual increases in track density. One conventional approach is to employ a dual-stage actuator system. 
       FIG. 1   a - 1   c  is a conventional disk drive unit incorporating a dual-stage actuator system. The dual-stage actuator system includes a primary actuator such as a voice-coil motor  105  and a secondary micro-actuator such as a piezoelectric micro-actuator  107 . A magnetic disk  101  of the disk drive unit is mounted on a spindle motor  102  for spinning the disk  101 . A voice coil motor arm  104  carries a head gimbal assembly  106  that includes a slider  103  incorporating a read/write head, a piezoelectric micro-actuator  107  and a suspension  110  to support the slider  103  and the piezoelectric micro-actuator  107 . 
     As the primary actuator, the voice-coil motor  105  is provided for controlling the motion of the motor arm  104  and, in turn, controlling the slider  103  to move from track to track across the surface of the disk  101 , thereby enabling the read/write head to read data from or write data to the disk  101 . According to the voice-coil motor  105 , the piezoelectric micro-actuator  107  corrects the placement on a much small scale to compensate the vibration tolerance of the suspension  110  or the voice-coil micro-actuator  105 . Thereby, the piezoelectric micro-actuator  107  enables a smaller recordable track width, and increases the tracks per inch (TPI), also, it reduces traces accessing time and positioning time. Thus, the introduction of the piezoelectric micro-actuator increases the trace density of the disk drive unit greatly. 
       FIG. 1   b  illustrates a head gimbal assembly  106  of the conventional disk drive unit with a dual-stage actuator shown in  FIG. 1   a . As illustrated, the suspension  110  of the head gimbal assembly  106  includes a flexure  111  with a plurality of traces, a slider support portion  112  with a bump  112   a , a metal base plate  113  and a load beam  114  with a dimple  114   a  to support the slider support portion  112  and the metal base plate  113 . The flexure  111  connects the slider support portion  112  and the metal base plate  113  by the traces thereon, the tongue region of the flexure  111  has a slider mounting region  111   b  for mounting the slider thereon and a piezoelectric element mounting region  111   a  for mounting the piezoelectric element of the piezoelectric micro-actuator  107  thereon, the slider  103  is partially mounted on the slider support portion  112  through the slider mounting region  111   b . The slider support portion  112  forms a bump  112   a  thereon to support the center of the backside of the slider  103  and the dimple  114   a  of the load beam  114  sustains the bump  112   a , in doing this, enabling the bump  112   a  to keep the load force from the load beam  114  always evenly applying to the center of the slider  103  when the slider  103  flying on the disk. The piezoelectric micro-actuator  107  includes a left thin film piezoelectric element  201  and a right thin film piezoelectric element  202  connecting with the left thin film piezoelectric element  201 , the left thin film piezoelectric element  201  and the right thin film piezoelectric element  202  adhere to the piezoelectric element mounting region  111   a  of the flexure  111 . Referring to  FIG. 1   c  also, when a voltage is input to the two thin film piezoelectric element  201 , 202 , one thin film piezoelectric element  201 / 202  thereof will contract and the other thin film piezoelectric element  202 / 201  thereof will expand, this will generate a rotation torque to the slider support portion  112 , thus the slider support portion  112  and the slider  103  will rotate against the dimple  114   a  subsequently, to achieve a slider fine position adjustment. 
       FIG. 2  is a plan view of a conventional piezoelectric micro-actuator shown in FIG.,  FIG. 2   a  is cross-sectional view taken along line A-A of  FIG. 2 , and  FIG. 2   b  is cross-sectional view taken along line B-B of  FIG. 2 . As is shown, a pair of electrode pads  204  are formed on the left thin film piezoelectric element  202  and a pair of electrode pads  206  are formed on the right thin film piezoelectric element  201 . The right thin film piezoelectric element  201  and the left thin film piezoelectric (PZT) element  202  are coated and covered by a polymer  209 , the polymer  209  includes a connection portion  911  at the place between the right and the left thin film piezoelectric (PZT) element  201 ,  202  to connect them physically. The right and the left thin film piezoelectric (PZT) element  201 ,  202  are laminated structures, and respectively include a first piezoelectric thin film layer  22  and a second piezoelectric thin film layer  25 , and the two thin film layers  22 ,  25  are laminated together by adhesive  28 . Specifically, the first piezoelectric thin film layer  22  includes a first electrode layer  223 , a second electrode layer  224  and a first piezoelectric layer  222  sandwiched between the first electrode layer  223  and the second electrode layer  224 , the second thin film layers  25  includes a third electrode layer  256 , a fourth electrode layer  257  and a second piezoelectric layer  225  sandwiched between the third electrode layer  256  and the fourth electrode layer  257 , the adhesive  28  is coated between the second electrode layer  224  and the third electrode layer  256  to bond the first and the second piezoelectric thin film layer  22 ,  25  together. 
       FIGS. 3   a - 3   d  show a conventional method of manufacturing the thin film piezoelectric element. Firstly, as shown in  FIG. 3   a , laminating a first electrode layer  223 , a first piezoelectric layer  222  and a second electrode layer  224  on a substrate  11  in succession to form a first piezoelectric thin film layer  22 , and laminating a fourth electrode layer  257 , a second piezoelectric layer  225  and a third electrode layer  256  on a substrate  12  in succession to form a second piezoelectric thin film layer  25 . Further referring to  FIG. 3   b , bonding the two piezoelectric thin film layers  22 ,  25  with the substrate  11 ,  12  respectively thereon together by an adhesive  28 . Then, as shown in  FIG. 3   c , removing the substrate  11  by chemical etching or other similar technique. Finally, as shown in  FIG. 3   d , removing the second substrate  12  to form the thin film piezoelectric element. 
     However, due to the process limitation, especially the chemical etching accuracy control limitation, the process yield for the above-mentioned thin film piezoelectric element is very low. Moreover, since there are two piezoelectric thin film layer are bonded together by an adhesive, the process is very complex and expensive, and it is easy to cause the piezoelectric thin film peeling. In addition, there are two substrate-removing processes in the process, which may cause a high reject rate and in turn, increase the manufacture cost. 
     Hence, in order to lower cost and eliminate the adhesive process to increase the process yield, a design of a piezoelectric element having only a single piezoelectric thin film layer is put forward, however, the stiffness and flexibility of a single piezoelectric thin film layer is too weak to operate and it is easy to be damaged during its manufacturing and assembly process, thus it still can not increase the production efficiency and the rate of finished products. 
     Thus, it is desired to provide an improved thin film piezoelectric element and its manufacturing method to overcome the above-mentioned drawbacks. 
     SUMMARY OF THE INVENTION 
     One objective of the invention is to provide a thin film piezoelectric element, which has a single piezoelectric thin film layer structure and an elastic substrate layer for supporting the piezoelectric thin film layer, thereby it has enough stiffness and flexibility to afford facilities for its manufacture and assembly process, also, eliminates the adhesive process to avoid the thin film peeling and deformation, ultimately increasing the production efficiency and lowering the cost. 
     Another objective of the invention is to provide a method for manufacturing a thin film piezoelectric element, which produces a thin film piezoelectric element having a single piezoelectric thin film layer structure and an elastic substrate layer for supporting the piezoelectric thin film layer, thereby the thin film piezoelectric element has enough stiffness and flexibility to afford facilities for its manufacture and assembly process, also, eliminates the adhesive process to avoid the thin film peeling and deformation, ultimately increasing the production efficiency and lowering the cost. 
     Another objective of the invention is to provide a head gimbal assembly (HGA), which has a thin film piezoelectric element having a single piezoelectric thin film layer structure and an elastic substrate layer for supporting the piezoelectric thin film layer, thereby the thin film piezoelectric element has enough stiffness and flexibility to afford facilities for its manufacture and assembly process, also, eliminates the adhesive process to avoid the thin film peeling and deformation, ultimately increasing the efficiency production and lowering the cost. 
     A further objective of the invention is to provide a disk drive unit, which has a head gimbal assembly with a thin film piezoelectric element having a single piezoelectric thin film layer structure and an elastic substrate layer for supporting the piezoelectric thin film layer, thereby the thin film piezoelectric element has enough stiffness and flexibility to afford facilities for its manufacture and assembly process, also, eliminates the adhesive process to avoid the thin film peeling and deformation, ultimately increasing the production efficiency and lowering the cost. 
     To achieve the above objectives, a thin film piezoelectric element comprises a piezoelectric thin film layer, a seed layer and an elastic substrate layer, the piezoelectric thin film layer is a laminated structure and comprises a first electrode layer, a second electrode layer and a piezoelectric layer sandwiched between the first electrode layer and the second electrode layer. The seed layer is formed on the second electrode layer, and the elastic substrate layer is formed on the seed layer. 
     In one embodiment of the thin film piezoelectric element according to the present invention, the invention further comprises a seed layer sandwiched between any two adjacent layers among the first electrode layer, the piezoelectric layer and the second electrode layer and/or further comprises a seed layer is formed on the electrode layer. 
     In another embodiment of the thin film piezoelectric element according to the present invention, the material of the elastic substrate layer is epoxy material or polymer material. The material of the seed layer is metal or metal oxide, preferably, it is SiO or Ti, and the seed layer is 10-200 angstrom in thickness. 
     A method for manufacturing a thin film piezoelectric element comprises steps of: (1) forming a piezoelectric thin film layer by laminating a first electrode layer, a piezoelectric layer and a second electrode layer together, wherein the piezoelectric layer is sandwiched between the first electrode layer and the second electrode layer; (2) forming a seed layer on the second electrode layer; and (3) forming an elastic substrate layer on the seed layer. 
     A head gimbal assembly of a disk drive unit comprises a suspension and a thin film piezoelectric element, the suspension comprises a flexure having a piezoelectric element mounting region thereon, the thin film piezoelectric element comprises a piezoelectric thin film layer, a seed layer and an elastic substrate layer, the piezoelectric thin film layer being a laminated structure comprises a first electrode layer, a second electrode layer and a piezoelectric layer sandwiched between the first electrode layer and the second electrode layer, the seed layer is formed on the second electrode layer and the elastic substrate layer is formed on the seed layer. The first and the second electrode layer respectively have a plurality of electrode pads extending outwards therefrom, the thin film piezoelectric element is mounted onto the flexure by cling the elastic substrate layer to the piezoelectric element mounting region and electrically connecting the electrode pads to the flexure. 
     A disk drive unit comprises a disk, a spindle motor to spin the disk, a drive arm and a head gimbal assembly mounted on the drive arm, the head gimbal assembly of a disk drive unit comprises a suspension and a thin film piezoelectric element, the suspension comprises a flexure having a piezoelectric element mounting region thereon, the thin film piezoelectric element comprises a piezoelectric thin film layer, a seed layer and an elastic substrate layer, the piezoelectric thin film layer being a laminated structure comprises a first electrode layer, a second electrode layer and a piezoelectric layer sandwiched between the first electrode layer and the second electrode layer, the seed layer is formed on the second electrode layer and the elastic substrate layer is formed on the seed layer. The first and the second electrode layer respectively have a plurality of electrode pads extending outwards therefrom, the thin film piezoelectric element is mounted onto the flexure by cling the elastic substrate layer to the piezoelectric element mounting region and electrically connecting the electrode pads to the flexure. 
     Compared with the prior art, because the thin film piezoelectric element only has a single piezoelectric thin film layer, thus it does not need to bond two single piezoelectric thin film layers together by adhesive and, accordingly simplifies its manufacturing process and avoids the film peeling effectively. In addition, since the seed layer is formed on the second electrode layer of the piezoelectric thin film layer, the elastic substrate layer is enabled to be formed on the seed layer for supporting the piezoelectric thin film layer, thus increasing the stiffness and flexibility of the thin film piezoelectric element, avoiding the inconvenience in manufacturing and assembly process due to inadequate stiffness and flexibility of a single laminated piezoelectric structure, and having no adverse impact on the extension-contraction deformation of the piezoelectric thin film layer. Further, the introduction of the seed layer, on the one hand, enables layers of the thin film piezoelectric element to connect each other more steadily, thus ensuring the layers not too easy to separate each other to prevent the thin film from peeling, on the other hand, the seed layer is also able to increase the stiffness and flexibility of the thin film piezoelectric element benefiting to its manufacturing and assembly process. 
     Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings: 
         FIG. 1   a  is a perspective view of a conventional disk drive device; 
         FIG. 1   b  is an exploded, perspective view of a conventional head gimbal assembly unit with a thin film piezoelectric micro-actuator of the drive disk shown in  FIG. 1   a;    
         FIG. 1   c  is a schematic view illustrating contracting and expanding of the two thin film piezoelectric elements of the thin film piezoelectric micro-actuator of the head gimbal assembly shown in  FIG. 1   b;    
         FIG. 2  is a plan view of a conventional thin film piezoelectric micro-actuator; 
         FIG. 2   a  is a cross-sectional view of  FIG. 2  taken along line A-A; 
         FIG. 2   b  is a cross-sectional view of  FIG. 2  taken along line B-B; 
         FIG. 3   a - 3   d  are sequential views illustrating a manufacturing process of a conventional thin film piezoelectric micro-actuator shown in  FIG. 2 ; 
         FIG. 4  a perspective view of a thin film piezoelectric element according to a first embodiment of the invention; 
         FIG. 5  is a cross-sectional view of  FIG. 4  taken along line V-V; 
         FIG. 6  is a schematic view illustrating the circuit connection of the thin film piezoelectric element according to the first embodiment of the invention shown in  FIG. 4 ; 
         FIGS. 7   a - 7   f  are sequential views illustrating a manufacturing process of the thin film piezoelectric element according to the first embodiment of the invention shown in  FIG. 4 ; 
         FIG. 8  shows a cross-sectional view of a thin film piezoelectric element according to a second embodiment of the invention; 
         FIG. 9  shows a cross-sectional view of a thin film piezoelectric element according to a third embodiment of the invention; 
         FIG. 10  shows a cross-sectional view of a thin film piezoelectric element according to a fourth embodiment of the invention; 
         FIG. 11  shows a cross-sectional view of a thin film piezoelectric element according to a fifth embodiment of the invention; 
         FIG. 12  is a perspective view of a head gimbal assembly of the invention; 
         FIG. 12   a  is a schematic view illustrating a thin film piezoelectric element of the invention preparing to be mounted on a suspension of a head gimbal assembly; 
         FIG. 12   b  is a perspective view illustrating a thin film piezoelectric element of the invention had been mounted on a suspension of a head gimbal assembly; and 
         FIG. 13  is a perspective view of a disk drive unit of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Various preferred embodiments of the invention will now be described with reference to the Figures, wherein like reference numerals designate similar parts throughout the various views. 
     Referring to  FIGS. 4-6 , a thin film piezoelectric element  50  according to a first embodiment of the invention comprises a piezoelectric thin film layer  500 , a seed layer  506  and an elastic substrate layer  504 . The piezoelectric thin film layer  500  is a laminated structure and comprises a first electrode layer  501 , a second electrode layer  503  and a piezoelectric layer  502  sandwiched between the first electrode layer  501  and the second electrode layer  503 . The seed layer  506  is formed on the second electrode layer  503  and the elastic substrate layer  504  is formed on the seed layer  506 . The first and the second electrode layers  501 ,  503  respectively have two electrode pads  51 ,  52  extending outwards therefrom, and the electrode pads  51 ,  52  electrically connect with the outside. The material of the elastic substrate layer  504  is epoxy material or polymer material, and the elastic substrate layer is used for supporting the piezoelectric thin film layer  500 , thus increasing the stiffness and flexibility of the thin film piezoelectric element  50 , and avoiding the inconvenience in manufacturing and assembly process due to inadequate stiffness and flexibility of a single laminated piezoelectric structure and having no adverse impact on the extension-contraction deformation of the piezoelectric thin film layer  500 . The material of the seed layer  506  is metal and metal oxide, such as SiO or Ti, and the seed layer is 10-200 angstrom in thickness. On the one hand, the seed layer  506  enables the piezoelectric thin film layer  500  and the elastic substrate layer  504  to connect each other more steadily, thus to prevent them from peeling, on the other hand, the seed layer  506  is also able to increase the stiffness and flexibility of the thin film piezoelectric element  50  benefiting to its manufacturing and assembly process. 
       FIGS. 7   a - 7   f  illustrate the manufacturing process of the thin film piezoelectric element  50  according to a first embodiment of the invention. The method for manufacturing the thin film piezoelectric element  50  comprises steps of: (1) providing a wafer substrate  550 , and forming the first electrode layer  501  on the wafer substrate (shown in  FIG. 7   a ); (2) forming the piezoelectric layer  502  on the first electrode layer  501  (shown in  FIG. 7   b ); (3) forming the second electrode layer  503  on the piezoelectric layer  502  (shown in  FIG. 7   c ); (4) forming the seed layer  506  on the second electrode layer  503 , wherein the material of the seed layer  506  is metal or metal oxide, such as SiO or Ti, and it is 10-200 angstrom in thickness (shown in  FIG. 7   d ); (5) forming the elastic substrate layer  504  on the seed layer  506 , wherein the material of the elastic substrate layer  504  is epoxy material or polymer material (shown in  FIG. 7   e ); and (5) removing the wafer substrate  550  by chemical etching to get the thin film piezoelectric element  50 . 
     As the thin film piezoelectric element  50  only has a single piezoelectric thin film layer, thus it does not need to bond two single piezoelectric thin film layers together by adhesive and, accordingly simplifies its manufacturing process and avoids the film peeling effectively, ultimately increases the production efficiency and lowers the cost. 
       FIG. 8  is a cross-sectional view of a thin film piezoelectric element  50   a  according to a second embodiment of the invention. As is shown, compared with the thin film piezoelectric element  50  according to the first embodiment of the invention, the thin film piezoelectric element  50   a  still sandwiches an additional seed layer  506   a  between the piezoelectric layer  502  and the second electrode layer  503 , the material of the seed layer  506   a  is metal and metal oxide, such as SiO or Ti, and the seed layer is 10-200 angstrom in thickness. On the one hand, the seed layer  506   a  enables the piezoelectric layer  502  and the second electrode layer  503  to connect with each other more steadily, thus to prevent them from peeling, on the other hand, the seed layer  506   a  is also able to increase the stiffness and flexibility of the thin film piezoelectric element  50   a  benefiting to its manufacturing and assembly process. As structure, function and material of the other parts of the thin film piezoelectric element  50   a  are similar to the thin piezoelectric element  50  according to the first embodiment of the invention, a detailed description of which is omitted herefrom. 
       FIG. 9  is a cross-sectional view of a thin film piezoelectric element  50   b  according to a third embodiment of the invention. As is shown, compared with the thin film piezoelectric element  50   a  according to the second embodiment of the invention, the thin film piezoelectric element  50   b  still sandwiches an additional seed layer  506   b  between the piezoelectric layer  502  and the first electrode layer  501 , the material of the seed layer  506   b  is metal and metal oxide, such as SiO or Ti, and the seed layer is 10-200 angstrom in thickness. On the one hand, the seed layer  506   b  enables the piezoelectric layer  502  and the first electrode layer  501  to connect with each other more steadily, thus to prevent them from peeling, on the other hand, the seed layer  506   b  is also able to increase the stiffness and flexibility of the thin film piezoelectric element  50   b  benefiting to its manufacturing and assembly process. As structure, function and material of the other parts of the thin film piezoelectric element  50   b  are similar to the thin piezoelectric element  50   a  according to the second embodiment of the invention, a detailed description of which is omitted herefrom. 
       FIG. 10  is a cross-sectional view of a thin film piezoelectric element  50   c  according to a fourth embodiment of the invention. As is shown, compared with the thin film piezoelectric element  50  according to the first embodiment of the invention, the thin film piezoelectric element  50   c  still forms an additional seed layer  506   c  on the first electrode layer  501 , the material of the seed layer  506   c  is metal and metal oxide, such as SiO or Ti, and the seed layer is 10-200 angstrom in thickness. The seed layer  506   c  is able to increase the stiffness and flexibility of the thin film piezoelectric element  50   c  benefiting to its manufacturing and assembly process. As structure, function and material of the other parts of the thin film piezoelectric element  50   c  are similar to the thin piezoelectric element  50  according to the first embodiment of the invention, a detailed description of which is omitted herefrom. 
       FIG. 11  is a cross-sectional view of a thin film piezoelectric element  50   d  according to a fifth embodiment of the invention. As is shown, compared with the thin film piezoelectric element  50   b  according to the third embodiment of the invention, the thin film piezoelectric element  50   d  still forms an additional seed layer  506   d  on the first electrode layer  501 , the material of the seed layer  506   d  is metal and metal oxide, such as SiO or Ti, and the seed layer is 10-200 angstrom in thickness. The seed layer  506   d  is able to increase the stiffness and flexibility of the thin film piezoelectric element  50   d  benefiting to its manufacturing and assembly process. As structure, function and material of the other parts of the thin film piezoelectric element  50   d  are similar to the thin piezoelectric element  50   b  according to the third embodiment of the invention, a detailed description of which is omitted herefrom. 
     Of course, besides the thin film piezoelectric elements  50   a ,  50   b ,  50   c ,  50   d  according to the first, second, third, fourth and fifth embodiments of the invention, the thin film piezoelectric element of the invention can further form a seed layer sandwiched between any two adjacent layers among the first electrode layer  501 , the piezoelectric layer  502  and the second electrode layer  503  and/or further forms a seed layer on the first electrode layer  501 . 
     As the manufacturing methods of the thin film piezoelectric elements  50   a ,  50   b ,  50   c    50   d  are the same as the thin film piezoelectric element  50 , detailed illustrations of which are omitted herefrom. 
     Referring to  FIG. 12 , a head gimbal assembly  300  according to an embodiment of the invention comprises a slider  103 , a thin film piezoelectric micro-actuator with two thin film piezoelectric elements  50  (also can be  50   a ,  50   b ,  50   c  or  50   d ) of the invention, and a suspension  400  supporting the slider  103  and the thin film piezoelectric micro-actuator. The suspension  400  comprises a flexure  307 , a load beam  305 , a base plate  301  and a hinge  302 , which are assembled together. Further referring to  FIG. 12   a , the flexure  307  has a piezoelectric element mounting region  305   a ,  305   b , a slider mounting region  351 , an inner trace  229  and an outer trace  230 . The slider mounting region  351  has a plurality of slider connection pads  231  thereon, and the flexure  307  has piezoelectric element connection pads  224 ,  225 ,  226 ,  227  thereon adjacent the piezoelectric mounting region  350   a ,  350   b . One end of the inner trace  229  electrically connects with the piezoelectric element connection pads  224 ,  227 , the other end thereof electrically connects with the electrode pads  319  of the flexure  307 , and one end of the outer trace  230  electrically connects with the slider connection pads  231 , the other end thereof electrically connects with the electrode pads  319  of the flexure  307 . The piezoelectric element connection pads  225 ,  226  are grounding pads. 
     Further referring to  FIG. 12   a  and  FIG. 12   b , the two thin film piezoelectric elements  50  are mounted onto the flexure  307  of the suspension  400  in the way described bellow: firstly, the two thin film piezoelectric element  50  are mounted on the flexure  307  by respectively clinging their elastic substrate layer to the piezoelectric element mounting region  350   a ,  350   b  and adhering them together by adhesive, then electrically connects the electrode pads  51 ,  52  of one of the thin film piezoelectric elements  50  to the piezoelectric element connection pads  224 ,  225 , and electrically connects the electrode pads  51 ,  52  of the other thin film piezoelectric element  50  to the piezoelectric element connection pads  227 ,  226 . Such electrical connection can be realized by soldering metal balls between the pads. 
       FIG. 13  is a perspective view of a disk drive unit according to an embodiment of the invention. The disk drive unit can be attained by assembling a base  1201 , a disk  1202 , a spindle motor  1203  for spinning the disk  1202 , a VCM  1206 , and a drive arm  1204  with the HGA  300 . Because the structure and/or assembly process of the disk drive unit of the present invention are well known to persons ordinarily skilled in the art, a detailed description of such structure and assembly is omitted herefrom. 
     While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.