Abstract:
A system and method for treating, such as insulating, piezoelectric components, such as piezoelectric micro-actuators for use in magnetic hard disk drives is disclosed, different embodiments involving material dipping, spraying, pin application, and chemical vapor deposition.

Description:
BACKGROUND INFORMATION  
         [0001]    The present invention relates to magnetic hard disk drives. More specifically, the present invention relates to a system and method for treating, such as insulating, piezoelectric components, such as piezoelectric micro-actuators.  
           [0002]    In the art today, different methods are utilized to improve recording density of hard disk drives. FIG. 1 provides an illustration of a typical drive arm configured to read from and write to a magnetic hard disk. Typically, voice-coil motors (VCM)  102  are used for controlling a hard drive&#39;s arm  104  motion across a magnetic hard disk  106 . Because of the inherent tolerance (dynamic play) that exists in the placement of a recording head  108  by a VCM  102  alone, micro-actuators  110  are now being utilized to ‘fine-tune’ head  108  placement, as is described in U.S. Pat. No. 6,198,606. A VCM 102 is utilized for course adjustment and the micro-actuator then corrects the placement on a much smaller scale to compensate for the VCM&#39;s  102  (with the arm  104 ) tolerance. This enables a smaller recordable track width, increasing the ‘tracks per inch’ (TPI) value of the hard drive (increased drive density).  
           [0003]    [0003]FIG. 2 provides an illustration of a micro-actuator as used in the art. Typically, a slider  202  (containing a read/write magnetic head; not shown) is utilized for maintaining a prescribed flying height above the disk surface  106  (See FIG. 1). Micro-actuators may have flexible beams  204  connecting a support device  206  to a slider containment unit  208  enabling slider  202  motion independent of the drive arm  104  (See FIG. 1). An electromagnetic assembly or an electromagnetic/ferromagnetic assembly (not shown) may be utilized to provide minute adjustments in orientation/location of the slider/head  202  with respect to the arm  104  (See FIG. 1).  
           [0004]    Utilizing actuation means such as piezoelectrics (see FIG. 3), problems such as electrical sparking and particulate-enabled shortage can exist. It is therefore desirable to have a system for component treatment that prevents the above-mentioned problems in addition to having other benefits. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 provides an illustration of a drive arm configured to read from and write to a magnetic hard disk as used in the art.  
         [0006]    [0006]FIG. 2 provides an illustration of a micro-actuator as used in the art.  
         [0007]    [0007]FIG. 3 provides an illustration of a ‘U’-shaped micro-actuator utilizing multi-layered piezoelectric transducers (PZT) to provide slider actuation.  
         [0008]    [0008]FIG. 4 demonstrates the problem of electrical shortage between PZT layers.  
         [0009]    [0009]FIG. 5 illustrates the damage caused by electrical sparking between PZT layers.  
         [0010]    [0010]FIG. 6 illustrates the problem of electrical shortage between one or more PZT layers and the micro-actuator suspension.  
         [0011]    [0011]FIG. 7 illustrates a dipping method for coating a micro-actuator under principles of the present invention.  
         [0012]    [0012]FIG. 8 describes a pin applicator method for coating the piezoelectric structure under principles of the present invention.  
         [0013]    [0013]FIG. 9 illustrates a method of coating a micro-actuator with a spray device under principles of the present invention.  
         [0014]    [0014]FIG. 10 describes a method for coating which involves chemical vapor deposition.  
     
    
     DETAILED DESCRIPTION  
       [0015]    [0015]FIG. 3 provides an illustration of a ‘U’-shaped micro-actuator utilizing multi-layered piezoelectric transducers (PZT) to provide slider actuation. A slider (not shown) is attached between two arms  302 ,  304  of the micro-actuator  301  at two connection points  306 ,  308 . Layers  310  of PZT material, such as Lead Zirconate Titanate, are bonded to the outside of each arm  302 ,  304 . PZT material has an anisotropic structure whereby the charge separation between the positive and negative ions provides for electric dipole behavior. When a potential is applied across a poled piezoelectric material, Weiss domains increase their alignment proportional to the voltage, resulting in structural deformation (i.e. regional expansion/contraction) of the PZT material. As the PZT structures  310  bend (in unison), the arms  302 , 304  (which are bonded to the PZT structures  310 ), bend also, causing the slider (not shown) to adjust its position in relation to the micro-actuator  301  (for magnetic head fine adjustments).  
         [0016]    [0016]FIG. 4 demonstrates the problem of particulate-enabled shorting between PZT layers. During manufacture and/or drive operation, particles may be generated, and a particle(s)  404  may end up between layers of the PZT  406 . Relative humidity can cause the particle(s) to absorb moisture from the air, enabling electrical conduction between PZT layers. This short  404  in the piezoelectric structure  406  can prevent its normal operation, adversely affecting micro-actuator  402  performance.  
         [0017]    [0017]FIG. 5 illustrates the damage caused by electrical sparking between PZT layers. The scale of the micro-actuator  502 , combined with the amount of piezoelectric voltage and the amount of moisture in the air, can cause electrical current to arc between layers of the piezoelectric structure  504 , damaging  506  the structure. The greater the amount of humidity, the higher the risk for electrical spark due to the increased conductance (decreased insulation) of the air. This spark problem can be further aggravated by particulate accumulation, decreasing the gap distance for an arc between PZT layers  504 .  
         [0018]    [0018]FIG. 6 illustrates the problem of electrical shortage between one or more PZT layers and the micro-actuator suspension (such as at a stainless steel portion). Similar to the problem of electrical shortage between PZT layers described in FIG. 4, it is likely for electrical current to short  602  between the piezoelectric structure  604  and the suspension  606 .  
         [0019]    In order to prevent problems such as particulate-enabled shorting and electrical sparking (arcing) a micro-actuator is coated with a material such as an insulator under principles of the present invention. FIG. 7 illustrates a dipping method for coating a micro-actuator under principles of the present invention. In one embodiment, a micro-actuator  702  is first  711  lowered into a reservoir filled with coating material  704  to cover the surface of the micro-actuator  702 . Next  712 , in one embodiment, the micro-actuator  702  is exposed to ultraviolet (UV) light  706  to bond and dry the film of coating material remaining on the surface. Next  713 , after the coating has dried, the micro-actuator is attached to a head gimbal assembly (HGA).  
         [0020]    [0020]FIG. 8 describes a pin applicator method for coating the piezoelectric structure under principles of the present invention. First  811 , in an embodiment, a pin applicator  802  with coating material is used to apply the coating material to desired areas, such as the surface of a piezoelectric structure  804 . Next  812 , in an embodiment, the micro-actuator  804  is exposed to UV light  806  to bond and dry the film of coating material remaining on the surface. Next  813 , after the coating has dried, the micro-actuator is attached to the HGA.  
         [0021]    [0021]FIG. 9 illustrates a method of coating a micro-actuator with a spray device under principles of the present invention. First  911 , in one embodiment, a spray gun  902  is utilized to coat the surface of a micro-actuator  904  with a material such as an insulator. Next  912 , in an embodiment, the micro-actuator  904  is exposed to UV light  906  to bond and dry the film of coating material remaining on the surface. Next  813 , after the coating has dried, the microactuator is attached to the HGA.  
         [0022]    [0022]FIG. 10 describes a method for coating which involves chemical vapor deposition (CVD). In an embodiment, a micro-actuator  1002  is placed within a CVD chamber  1004 . Next, a material such as an insulator  1006  is injected into the chamber  1004  in a vapor form while a platform holding the micro-actuator  1002  rotates, enabling a uniform thickness of material deposited on the surface of the micro-actuator  1002 . Once a target material thickness is achieved, a heater  1008  is utilized to bond and dry the film of coating material remaining on the surface, and the surplus vapor is evacuated  1010 .  
         [0023]    Although several embodiments are specifically illustrated and described herein, it will be appreciated that modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.