Abstract:
A method is provided for reworking a head gimbal assembly (HGA). An ultrasonic probe is used to stress the connection between the slider component of an HGA to remove the slider from its mounting position.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/592,531, filed Jul. 29, 2004, which disclosure is incorporated reference in its entirety for all purposes. 

   BACKGROUND OF THE INVENTION 
   The present invention generally relates to techniques for manufacturing hard disk drives. More particularly, the invention provides a method and system for repairing a magnetic head slider for a head gimbal assembly using an ultrasonic source. Other sources may also be used. 
   A hard disk drive (HDD) for data storage adapts a magnetoresistive thin film element (MR Head) to perform data read/write operations. The MR Head is bonded onto a flexure gimbal and then connected to a flex circuit using solder or gold ball bonding for data transmission. A suspension provides a platform for this architecture forming a Head Gimbal Assembly, HGA, as shown in  FIG. 4 . 
   During the manufacture of an HGA, if it is determined that the electrical property of the magnetic head slider is unacceptable, it is desirable to remove the magnetic head slider and salvage the suspension to minimize material loss. As the areal density of a hard disk drive increases, the magnetic head slider is also reduced in its size from nano- (50%), to pico- (30%), and to femto- (20%) scale dimensions, the detaching process of magnetic head slider becomes an increasingly difficult challenge. In a prior art technique, mechanical cutting using a cutter blade was suggested if gold ball bonding was used. For solder ball bonding, the detachment may employ the use of heat to melt the solder and removal by vacuum suction. As the size of the magnetic head slider gets smaller and the gimbal stiffness continues to decrease, there is a need for less contact and less intrusive techniques to detach a magnetic head slider. 
   From the above, it is seen that an improved technique for manufacturing a hard disk drive is highly desirable. 
   BRIEF SUMMARY OF THE INVENTION 
   A method for reworking a head gimbal assembly (HGA) according to the present invention includes positioning a probe in contact with or near to a slider component that is connected to a gimbal. An ultrasonic excitation is applied to the probe to create a reciprocating action. The reciprocating action creates mechanical stress in the connection between the slider and the gimbal to which the slider is mechanically mounted. The slider is thereby detached from the HGA. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various additional objects, features and advantages of the present invention can be more fully appreciated with reference to the detailed description and accompanying drawing, wherein: 
       FIGS. 1A-1C  show a simplified illustration of a method for detaching a magnetic head slider according to an embodiment of the present invention; 
       FIGS. 2A-2C  show a simplified illustration of a method for detaching a magnetic head slider according to another embodiment of the present invention; 
       FIGS. 3A-3D  show a simplified illustration of a method for detaching a magnetic head slider according to still another embodiment of the present invention; and 
       FIG. 4  is a simplified cross-sectional view of a Head Gimbal Assembly (HGA). 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1A-1C , a specific embodiment of the present invention illustrates a method for reworking a head gimbal assembly for disk drive applications. The method includes holding (e.g., via a support member) a head gimbal assembly (HGA)  100  comprising a magnetic head slider  112 , which is physically attached to a portion of the head gimbal assembly  100 . Preferably, the magnetic head slider  112  is maintained on the support member by an adhesive material  114 . A gold, or solder, ball bond  116  provides an electrical connection to a gimbal  102 . Thus, in  FIG. 1A , the method according to the specific embodiment of the present invention includes contacting a probe member  202  coupled to an ultrasonic transducer unit  200  to a portion of the magnetic head slider  112 . 
   As shown in  FIG. 1B , the method applies a predetermined power from the ultrasonic transducer  200  to the probe member  202  such that the probe member  202  oscillates at a frequency greater than about 1 k Hz in a linear motion having a spatial displacement of less than 0.03 mm as the probe member  202  is in contact within a vicinity of the portion of the magnetic head slider  100 . The method includes causing a repetitive pushing action upon the magnetic head slider  112  using the oscillation of the probe member  202  while applying the predetermined power from the ultrasonic transducer  200  to the probe member  202 . 
   Referring for a moment to  FIG. 4 , the probe member  202  can be arranged in a parallel relation to the trace interconnect to which the magnetic head slider  112  is in electrical contact. Since the magnetic head slider  112  is typically mounted in a substantially parallel relation to the trace interconnect, the pushing action of the probe member  202  is maximally delivered to overcome the adhesion force of the adhesive  114 . 
   Referring to  FIG. 1C , the pushing action will cause separation of the magnetic head slider  112  from the head gimbal assembly  100 . The method includes removing the predetermined power from the ultrasonic transducer  200 . 
   In accordance with an aspect of the present invention, the probe member  202  is maintained at a temperature ranging from about 20° C. to about 60° C. during the operation. 
   The detachment employs high frequency ultrasonic transducer  200  providing linear motion with a spatial displacement in the order of less than 30 micrometers. By bringing the probe member  202  of the transducer  200  to come into contact or near contact (see  FIGS. 3A-3D ) with the magnetic head slider  112 , the probe can move the magnetic head slider in a back and forth motion with a small displacement at a high frequency in the order of thousands of times per second. This small movement at high frequency creates a significant strain energy which can break away the ball bond  116  and the adhesive  114  underneath. 
   With reference to  FIGS. 2A-2C , another specific embodiment of the present invention is shown of a method for reworking a head gimbal assembly for disk drive applications. The method includes a support member  300  schematically represented in the figure as an object that resembles a clamp, but which will be understood to represent any suitable support/holding structure for performing the described operation. The support member  300  supports the head gimbal assembly (HGA)  100 . As shown in  FIGS. 1A-1C , the HGA  100  includes the magnetic head slider  112  which is physically attached to a portion of the head gimbal assembly via the adhesive  114 . Preferably, the magnetic head slider  112  is also supported on the support member  300 . The method includes contacting the probe member  202  of the ultrasonic transducer  200  to a portion of the magnetic head slider  112 . 
   As shown in  FIG. 2B , the method applies a predetermined power from the ultrasonic transducer  200  to the probe member  202  such that the probe member oscillates at a frequency greater than a predetermined frequency. The range of motion of oscillation of the probe member  202  has a spatial displacement of less than a predetermined distance as the probe member is in contact within a vicinity of the portion of the magnetic head slider  112  that is being supported via the support member  300 . 
   As can be seen in  FIG. 2C , the method includes a repetitive pushing action against the magnetic head slider  112  using the oscillation of the probe member  202  while applying the predetermined power from the ultrasonic transducer  200  to the probe member. The repeated pushing action overcomes the adhesion force of the adhesive  114  and causes separation of the magnetic head slider  112  from the head gimbal assembly  100 . The method includes removing the predetermined power from the ultrasonic transducer. 
   With reference to  FIGS. 3A-3D , yet another specific embodiment of the present invention is shown of a method for reworking a head gimbal assembly for disk drive applications. The method includes holding (e.g., via a support member such as illustrated in  FIGS. 2A-2C ) the HGA  100 . As shown in  FIGS. 1A-1C  and in  FIGS. 2A-2C , the HGA  100  includes the magnetic head slider  112  which is physically attached to a portion of the head gimbal assembly via the adhesive  114 . As shown in  FIG. 3A , the method includes contacting the probe member  202  of the ultrasonic transducer  200  to a portion of the magnetic head slider  112 . Alternatively, the probe member  202  can be brought near to the slider  112 . This arrangement is shown in  FIG. 3B . 
   In  FIG. 3C , the method applies a predetermined power from the ultrasonic transducer  200  to the probe member  202  such that the probe member oscillates at a frequency greater than a predetermined frequency. The range of motion of oscillation of the probe member  202  has a spatial displacement of less than a predetermined distance so that the probe member  202  alternates between contacting and not-contacting the magnetic head slider  112  as the probe member reciprocates back and forth against the magnetic head slider. 
   As can be seen in  FIG. 3C , the oscillations cause repetitive pushing action against the magnetic head slider  112  using the oscillation of the probe member  202  while applying the predetermined power from the ultrasonic transducer  200  to the probe member. The repeated pushing action overcomes the adhesion force of the adhesive  114  and causes separation of the magnetic head slider  112  from the head gimbal assembly  100 . The method includes removing the predetermined power from the ultrasonic transducer. 
   It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.