Abstract:
A system and method are disclosed for manufacturing a hard disk drive suspension flexure and for preventing damage due to electrical arcing between traces and between a trace and a grounding structure. In one embodiment, one or more portions of the suspension flexure is etched and laminated with an insulative coating.

Description:
BACKGROUND INFORMATION  
         [0001]    The present invention relates to hard disk drives. More specifically, the invention relates to a system and method for manufacturing a hard disk drive suspension flexure and for preventing electrical spark damage.  
           [0002]    In the art today, different methods are used to improve the recording density of hard disk drives. FIG. 1 provides an illustration of a typical disk drive with a typical drive arm configured to read from and write to a magnetic hard disk. Typically, voice-coil motors (VCM)  106  are used for controlling a hard drive&#39;s arm  102  motion across a magnetic hard disk  104 . Because of the inherent tolerance (dynamic play) that exists in the placement of a recording head  108  by a VCM  106  alone, micro-actuators  110  are now being utilized to ‘fine tune’ head  108  placement. A VCM  106  is utilized for course adjustment and the micro-actuator  110  then corrects the placement on a much smaller scale to compensate for the VCM&#39;s  106  (with the arm  102 ) tolerance. This enables a smaller recordable track width, increasing the ‘tracks per inch’ (TPI) value of the hard disk drive (increasing the density).  
           [0003]    [0003]FIG. 2 provides an illustration of a micro-actuator as used in the art. As described in Japanese patents, JP 2002-133803 and JP 2002-074871, a slider  202  (containing a read/write magnetic head; not shown) is utilized for maintaining a prescribed flying height above the disk surface  104  (See FIG. 1). U-shaped micro-actuators may have two ceramic beams  208  with two pieces PZT on each side of the beams (not show), which are bonded at two points  204  on the slider  202  enabling slider  202  motion independent of the drive arm  102  (See FIG.  1 ). The micro-actuator  206  is commonly coupled to a suspension  212 , by electrical connector balls  207  (such as gold ball bonding (GBB) or solder bump bonding (SBB)) on each side of the micro-actuator frame  210 . Similarly, there are commonly GBB or SBB electrical connectors  205  to couple the trailing edge of magnetic head(slider)  202  to the suspension  212 . Under piezoelectric expansion and contraction, the U-shape micro-actuator  210  will deform, causing the magnetic head to move over the disk for fine adjustment.  
           [0004]    [0004]FIG. 3 illustrates another micro-actuator design existing in the art. As shown in FIG. 3 b , between the slider  302  and a suspension tongue  306 , is an I-beam micro-actuator  303 . The micro-actuator  303  may have two PZT beams  311  and  312 . One end support  300  is coupled to the suspension tongue  306 , and the other end support  305  is coupled to the magnetic head  302 . Under PZT beam  311 , 312  expansion and contraction, the magnetic head moves back and forth to fine adjust the location of the head  302  on the magnetic disk (not shown). As shown in FIG. 3 c , in the alternative, a micro-electro-mechanical system (MEMS) or other micro-actuator system (such as electromagnetic, electrostatic, capacitive, fluidic, thermal, etc.) may be used for fine positioning.  
           [0005]    [0005]FIG. 4 illustrates a load beam configuration PZT micro-actuator typical in the art and disclosed in US patent application 20020145831. Two PZT components  411  and  412  are coupled to the suspension load beam  402 . Under expansion and contraction, the head suspension  402  (with magnetic head  422 ) moves for fine adjustment.  
           [0006]    [0006]FIG. 5 illustrates a typical suspension flexure design used for hard disk drives. As shown in FIG. 5 a , there are two traces  501  for micro-actuator control, called channels A and B. As shown in FIG. 5 e , 10 to 60V sinusoidal waveforms with opposing phases are used to excite the micro-actuator. The stainless steel of the suspension body  504  is used as the ground. The other four traces  502 , 503  are used for magnetic head read and write functions. As shown in FIG. 5 c , a cross-section, A-A, of the flexure illustrates the polyimide layer  505 , mounted to the stainless steel base layer  504 . Typically, six traces  501 , 502 , 503  of a material such as copper are located on the polyimide layer  505 . Because of variations in the fabrication process, the polyimide layer  505  may be thinner than desired. When this happens, an electrical arc (spark)  506  may occur during periods of high voltage at a micro-actuator trace  501  (with respect to ground  504 ). As shown in FIG. 5 c , a spark  506  may occur between a micro-actuator trace  501  and ground  504 .  
           [0007]    In addition to inconsistent layer thickness, the spark problem can also be caused by environmental conditions, such as high humidity. As shown in FIG. 5 d , a spark  506  can occur between two micro-actuator traces  501  (sinusoidal voltage with opposing phase) due to high humidity, etc. Also, particle contamination can cause the spark problem. A contaminant (not shown) existing between two micro-actuator traces  501  can provide a stepping stone for a spark  506 , aiding its jump from one micro-actuator trace to another 501. Because high displacement is necessary for the micro-actuator, large trace voltages are necessary, increasing the likelihood of a spark problem.  
           [0008]    It is therefore desirable to have a system and method for manufacturing a hard disk drive suspension flexure that prevents electrical spark damage, as well as having additional benefits.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 provides an illustration of a typical disk drive with a typical drive arm configured to read from and write to a magnetic hard disk.  
         [0010]    [0010]FIG. 2 provides an illustration of a micro-actuator as used in the art.  
         [0011]    [0011]FIG. 3 illustrates another micro-actuator design existing in the art.  
         [0012]    [0012]FIG. 4 illustrates a load beam configuration PZT micro-actuator typical in the art and disclosed in US patent application 20020145831.  
         [0013]    [0013]FIG. 5 illustrates a typical suspension flexure design used for hard disk drives.  
         [0014]    [0014]FIG. 6 illustrates a hard disk drive suspension flexure according to an embodiment of the present invention.  
         [0015]    [0015]FIG. 7 illustrates the process of etching and laminating a suspension flexure according to an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0016]    [0016]FIG. 6 illustrates a hard disk drive suspension flexure according to an embodiment of the present invention. As shown in FIG. 6 c , in one embodiment an insulative coating (layer)  601  is applied to cover and separate the electrical traces  501 , 502 , 503  of the flexure. In this embodiment, the insulative layer  601  prevents electrical arcing between traces  501 , 502 , 503 . In one embodiment, a portion  602  of the base layer (such as stainless steel)  504  opposite the micro-actuator traces  501  is etched away  602 , such as by a chemical etching technique. As shown in the back side view of FIG. 6 b , in one embodiment, the portion  602  opposite the micro-actuator traces  501  is etched away from one end  604  of the traces  501  (behind the micro-actuator connection pads  603 ; see FIG. 6 a ) to the other end of the traces  501  (behind the micro-actuator ball bonding pads  605  of the suspension tongue). In this embodiment, an insulative material  612  (such as epoxy, acrylic, polyimide, or other insulative film) is applied to fill the etched away portion  602 . The insulative material (layer)  612  is applied by a method such as plating or spray coating.  
         [0017]    In one embodiment, the portion  602  being etched out and filled with insulative material  612  reduces the overall stiffness of the suspension flexure (i.e., the insulative material is not as rigid as stainless steel). This improves flying height stability as well as loading and unloading characteristics. Further, in this embodiment, reducing the amount of stainless steel in the base  504  reduces the traces&#39; electrical impedance and capacitance. Impedance and capacitance matching is important for optimizing the electrical performance (i.e., for preventing signal resonance at high data transmission frequencies and for preventing signal cross-talk).  
         [0018]    [0018]FIG. 7 illustrates a process of etching and laminating a suspension flexure according to an embodiment of the present invention. As shown in FIGS. 7 a  and  7   b , in one embodiment, a base layer  701  is coated with a layer  702  such as a polyimide. As shown in FIG. 7 c , in this embodiment, an electrically conductive layer (of, e.g., Copper, Gold, Nickel alloy, Platinum, or Tin)  703  is joined to the polyimide layer  702 . As shown in FIG. 7 d , in this embodiment, photo-resist elements  704  are joined to the conductive layer  703 . As shown in FIG. 7 e , in this embodiment, the electrically conductive layer  703  is etched away (such as by chemical etching) where no photo-resist  704  is present. As shown in FIGS. 7 f  and  7   g , in this embodiment, an insulative coating  705  is applied to cover and fill the spaces between the traces  704 .  
         [0019]    As shown in FIG. 7 h , in this embodiment, photo-resist elements  706  are joined to the base layer  701 . As shown in FIG. 7 i , in this embodiment, the base layer  701  is etched away (such as by chemical etching) where no photo-resist  704  is present. As shown in FIGS. 7 j  and  7   k , in this embodiment, an insulative coating  707  is applied to fill the space between the portions of the base layer  701 .  
         [0020]    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.