Abstract:
An HGA loader provides HGAs, in succession, to a multiple workstation head tester. An HGAs carrier station receives HGAs to be tested. An alignment station on the base includes an alignment surface which selectively rotates about an alignment axis. A camera generates images of an HGA on the alignment surface, which is rotated so that the HGA has a desired spatial orientation which is maintained as the HGA is transferred to an HGA testing workstation. A received, oriented HGA is positioned to enable read/write test operations on a disk rotating on an adjacent spinstand. To effect the successive position operations, a transporter includes a track overlying the workstations, and a carriage movable along the track, to pass from workstation to workstations. The loader is automatically operative under the control of a controller.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to U.S. Provisional Patent Application Ser. No. 62/138,105, filed Mar. 25, 2015, and its successor U.S. patent application Ser. No. 15/081,299 (Attorney Docket No. GUZL-0302), entitled “HEAD GIMBAL ASSEMBLY (HGA) SUPPORT CARTRIDGE FOR MAGNETIC HEAD AND DISK TESTERS” (copy attached hereto as Attachment A), filed on even date herewith, and U.S. Provisional Patent Application Ser. No. 62/138,114, filed Mar. 25, 2015, and its successor U.S. patent application Ser. No. 15/080,726 (Attorney Docket No. GUZL-0303), entitled “HEAD GIMBAL ASSEMBLY (HGA) MOUNTING APPARATUS FOR A MAGNETIC HEAD AND DISK TESTER” (copy attached hereto as Attachment B), filed on even date herewith. Those applications are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to magnetic head and disk testers, and in particular to an apparatus that automatically loads a read/write head on a tester. 
       BACKGROUND OF THE INVENTION 
       [0003]    A head/disk tester is an instrument that is used for testing the characteristics of magnetic heads and disks, such as signal-to-noise ratio, track profile, etc. The tester simulates motions of the head with respect to the disk that occur in an actual hard disk drive during operation. A tester comprises a mechanical component, commonly referred to as a spinstand, that performs movements of the head with respect to the disk, and an electronic component, that is responsible for measurement, calculation, and analysis of the measured signal. 
         [0004]    Examples of prior art spinstands for a head and disk tester include the Guzik V2002 XY-positioning spinstand and the Guzik S-1701B Micro Positioning spinstand, both of which are available from the assignee of the present disclosure, Guzik Technical Enterprises, 2443 Wyandotte Street, Mountain View, Calif. 94043, USA. 
         [0005]    A read/write head is usually incorporated into a head gimbal assembly (HGA), such as shown in  FIG. 1 . The basic components of an HGA  100  are a head  102 , an elongated load beam  104 , a tooling hole  106 , a base plate  108  having a planar major surface extending between a first edge and a second edge, a boss hole  110  with an angled surface  110 A, and a elongated flex circuit support sheet element  112  with an array of electrically conductive pads  118 . The boss hole  110  passes through base plate  108  and is characterized by a radius R about an HGA mounting axis perpendicular to the planar surface with center point CP. The boss hole  110  and the tooling hole  106  (sometimes) are used for orientation of the HGA in the X-Y plane. The angled surface  110 A of the boss hole  110  is used for clamping the HGA to an HGA support assembly associated with a spinstand. The flex circuit sheet element  112  is used to support electrical connections of the head of the HGA, by way of pads  118 , to an external head preamplifier (not shown). Generally, the base plate  108  and load beam  104  are relatively stiff compared to the flex circuit sheet element  112 . 
         [0006]    In order to test a head with a spinstand, an HGA is loaded to the HGA support assembly associated with the tester. The HGA is mechanically coupled to a corresponding component of the spinstand, and electrically connected to spinstand preamplifiers. To make these operations possible, an alignment of the HGA relative to the spinstand is carried out. After testing, the tested head is removed from the tester. 
         [0007]    In the prior art, these steps may be performed by a human operator. Alternatively, some or all of these steps can be automated. Automation is particularly useful in a manufacturing environment, as automation can perform loading faster than a human operator and thus can lead to a greater throughput of heads. Modern heads are particularly susceptible to electrostatic damage. Using automation to perform HGA loading, instead of human operator, helps to avoid such damage and to reduce the loss of the heads. 
         [0008]    Various methods and apparatus for automatic loading the HGA to a tester are known in the prior art and are described, for example, in U.S. Pat. No. 7,520,047 “Method and apparatus for loading a read/write head to a spinstand”, U.S. Pat. No. 7,542,868 “Head gimbal assembly loader”, U.S. Pat. No. 7,529,635 “Method and apparatus for head gimbal assembly testing”, U.S. Pat. No. 8,176,794 “Unmounted head gimbal assembly clamping plate”, U.S. Pat. No. 8,873,200 “Spinstands for testing a head gimbal assembly”, U.S. Pat. No. 8,611,048 “Apparatus and method for receiving and positioning a read/write head to a disk for testing and method of removing a tested read/write head from a test apparatus”. 
         [0009]    A tester with automatic loading of an HGA, known in the prior art, usually contains a loading area, a precising (or “alignment”) area and a test area. A transporter, incorporated in the tester, enables transfer of the tested HGAs from the loading area to the precising area, from the precising area to the test area and, after testing, from the test area back to the loading area. In the loading area, an operator loads and unloads HGAs using some HGA containers. In the precising area, the HGA is aligned with the disk for eventual testing. The components of the precising area are purportedly accurately aligned with corresponding components of the test area, so that the alignment performed at the precising area is retained when the HGA is moved to the test area. In the test area, an electrical connection of the HGA with the preamplifier is established and a dynamic test of the read/write head in association with a disk is performed. 
         [0010]    Typically, in the prior art, at a planar surface in an X-Y plane in the precising area, a boss hole pin and a front alignment pin are erected. Both pins are tapered. When an HGA to-be-tested is lowered along the Z direction at the planar surface of the precising area, the HGA&#39;s boss hole  110  slips over the boss hole pin and the tooling hole  106  slips over the front alignment pin. As the HGA travels downward, the taper on the pins pulls the boss hole  10  and the tooling hole  106  into their proper positions. The achieved alignment is maintained while the HGA is transferred to the test area. After the transfer to the test area has been carried out, the flex circuit pads  118  of the HGA are generally in the vicinity of the preamplifier terminals and the mechanical structure of the tester attempts to establish an electrical connection between the HGA and the preamplifier terminals, and the preamplifiers. 
         [0011]    There are two straight lines that characterize the geometry of an HGA: (a) an axis of symmetry of the HGA&#39;s base plate  108  that goes through the centers of the boss hole  110  and the tooling hole  106 , and (b) a flex axis that passes through the center point CP of the boss hole  110  and through the array of electrically conductive pads  118  of the flex circuit sheet element  112 . The angle between these two lines is not the same for all HGAs—it varies from one type of HGA to another. Accordingly, the position of the pads  118  relative to the axis of symmetry of the HGA&#39;s base plate  108  varies—the pads  118  of the flex circuit sheet element  112  of different HGAs are scattered around some nominal (proper) position. 
         [0012]    The structure that establishes electrical connection between the pads of array  118  and preamplifier terminals, is designed in such a manner that the terminals of the preamplifier come into contact with the pads  118  of the flex circuit sheet element  112  of an “average” HGA. The pads  118  of a real HGA, which is to be tested, are generally displaced from the “average” position. If the displacement is small enough, it does not hinder the establishment of an electrical connection. If the displacement exceeds a certain value, which is typically of the same order of magnitude as a pad size, then the pads  118  of the HGA&#39;s flex circuit sheet element  112  and the preamplifier terminals are spaced apart and are thus mis-aligned so that the needed electrical connection cannot be established for the subject HGA. In this situation, the test fails and, typically, the failed “not-tested” HGA (and its head) is marked as unfit for use. 
         [0013]    In the prior art, the “two points alignment” of the HGA, which is performed by aligning the positions of the boss hole  110  (the first point) and the tooling hole  106  (the second point), and which was suggested in the above-cited patents, aligns only the position of the HGA&#39;s base plate  108 . After that limited alignment, the HGA becomes fixed in the X-Y plane and further alignment is impossible. Any possible shift of the circuit pads of array  118  in relation to the preamplifier terminals however remains unchanged, so that the pads cannot be brought into contact with the preamplifier terminals. This is particularly important since the circuit sheet element  12  relatively compliant/flexible compared to the relatively stiff base plate  108  and load beam  104 . If the load beam  104  and base plate  108  are fixed, as in the prior art, the pad array  118 , at the distal end of the flexible circuit sheet element is simply not known/controlled. Attempts to establish an electrical connection fail often enough for this reason, so that significant numbers of possibly good, but untested, heads are baselessly rejected as flawed, because of their inability to connect the HGA to preamplifier terminals, and are erroneously discarded. This is an important disadvantage of prior art HGA loaders. 
         [0014]    There are several ways suggested in the prior art, to overcome the adverse effect of the positional errors of the HGA flexible circuit sheet element upon test results (see, for example, the U.S. Pat. No. 7,529,635, entitled “Method and apparatus for head gimbal assembly testing”). It has been suggested that the area of preamplifier terminals be widened, to enable a higher likelihood of successful interconnection with the flex circuit pads  118 . By using contacts with an area that covers the tolerance range of flex circuit location, one may ensure that the flex circuit pads  118  touch the preamplifier terminals, when they are pressed together. 
         [0015]    Another suggestion has been to terminate each of the preamplifier conductors, which are to contact the same flex circuit pad, with two pogo pins. The use of two pogo pins for one conductor permits the flex circuit pad to contact one of them, even when the flex circuit  112  is not optimally aligned. This would increase the variance permitted in the positioning of the flex circuit  112 . However, for increasingly needed high density connector pad arrays, it is not possible to accommodate error tolerances in the position of the pad arrays  118 . 
         [0016]    The trend of increasing track density on a disk, has led to new methods of magnetic writing, such as those encompassing preheating of the media. Such new techniques have introduced new components (a heater, a laser and so on) to read/write heads, so that the number of head inputs/outputs is increased. This causes a corresponding increase of the number of pads on an HGA flex circuit  112 . Some manufacturers have begun to produce HGA&#39;s with flex circuit pads  118  arranged in several rows (see  FIG. 2B  and  FIG. 2C , for example). For this reason, the described suggestions cannot be used in the needed contemporary HGA loaders, and the problem of elimination (or at least reduction) of the flex circuit sheet element  112  positioning-caused errors, remains urgent. 
       SUMMARY 
       [0017]    According to the present invention, an alignment of an HGA is performed in two steps. As a first step, improved translation alignment is effected by more accurately centering an HGA boss hole  110  of an HGA to be tested. As a second step, improved angular alignment of the HGA to be tested is achieved whereby the HGA is angularly displaced around the center of the boss hole  110 , so that the pads  118  of the HGA flex circuit sheet element  112  (rather than the magnetic head at the end of the load beam  104  as in the prior art) are placed in the required position as well. In this way, the possible displacement of the flex circuit pads of array  118  relative to preamplifier terminals, is prevented and a principal reason for unjustified rejection of the tested read/write heads is eliminated. 
         [0018]    Additionally, according to the present invention, after the alignment of an HGA is accomplished, the HGA is disengaged from adjacent components in a novel manner. In that way, when the HGA is raised before the transfer to a next workstation, friction between the inner facing surface of HGA boss hole  110  with the supporting parts, is eliminated, so that a possible cause of alignment infringement is removed. 
         [0019]    In the mounting structure, among other operations, the HGA flex circuit sheet element  112  is flattened and fastened to the mounting surface prior to testing. According to the present invention, the mounting structure is configured in such a way that the procedure of flattening and fastening is applied not to just a portion of the whole flex circuit sheet element  112 , but to the whole flex circuit sheet element  112 , including the part that contains the pads  118 . In that case, the pads of array  118  become immovable, and that increases the accuracy of engagement of the pads of array  118  with the preamplifier terminals, as well as eliminates the possibility of pads scratching during establishing electrical connection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  shows in details a conventional HGA (prior art). 
           [0021]      FIGS. 2A-2C  show different types of HGAs (prior art). 
           [0022]      FIG. 3  shows a general view of a part of a tester that contains components of an embodiment of the present invention. 
           [0023]      FIG. 3A  shows a general view of a part of a tester that contains components of an alternative embodiment of the present invention. 
           [0024]      FIG. 3B  shows the tester of  FIG. 3A  with the transporter  322  and its support structure  322 A,  322 B removed to show the spinstand residing behind the transporter as viewed in  FIG. 3A . 
           [0025]      FIGS. 4A-4D  illustrate the use of the digital camera. 
           [0026]      FIG. 5  shows a cross section of an alignment table according to an embodiment of the present invention. 
           [0027]      FIG. 6  shows separate components of an alignment table according to an embodiment of the present invention. 
           [0028]      FIGS. 7A-7B  show an interconnection unit of the embodiment of Figs. 
           [0029]      FIGS. 8A-8C  show the rear side of an interconnection unit according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 3  shows an overview of a portion of a head and disk tester  10 , having multiple components that form an HGA loader  12  according to an embodiment of the present invention. An X-Y-Z coordinate system is shown in  FIG. 3  for directional references. Head and disk tester  120  is includes a base B upon which a spinstand  318  including its support structure  318 A and rotary drive motor  318 B ( 318 A and  318 B are not clearly shown in  FIG. 3 , but are clearly shown in the alternative head and disk tester  12  shown in part in  FIG. 3B ) are positioned along with HGA loader  12 . The spinstand support structure  318 A includes a magnetic disk support structure for attaching one or more magnetic disks and coupling the attached disk(s) for spinning about a spin axis SA (parallel to the Z axis) by motor  318 B during testing of an HGA. 
         [0031]    The HGA loader  12  comprises three principal workstations aligned along a work axis W, where W is parallel to the X axis. The first workstation is an HGAs carrier  314  having a planar top surface in an X-Y plane for receiving and supporting HGAs to be tested, preferably in a single layer array. The second workstation is an alignment table  316  having a planar top surface (TS) in an X-Y plane for receiving HGAs one at a time. The alignment table  316  has an associated rotary actuator  320  for angularly displacing the top surface of the alignment table  316  together with a received HGA thereon, about an alignment axis A parallel to the Z axis, to align the received HGA to a test orientation. The third workstation is a mounting structure MS on a mounting structure support  324  affixed to an X-Y transport plate  330 , for receiving oriented HGAs one at a time on mounting support MS, and supporting the received oriented HGAs in a desired angular position in relation to a disk on spinstand  318 , for testing while maintaining the test orientation of the HGA. An Y transport assembly  332  and an X transport assembly  334  are disposed on a top-facing surface of base B of head and disk tester  10  and are configured in a conventional manner to selectively displace the X-Y transport plate, and thus, in turn, mounting support gross motion in the X-direction and Y-direction from an initial (HGA receiving location along workstation axis W) to a test position with an HGA on mounting structure MS opposite a spinning (about spin axis SA) disk-to-be-tested at spinstand  318 . 
         [0032]    The mounting structure MS in  FIG. 3  is, for example, of the type of apparatus shown in U.S. Provisional Patent Application Ser. No. 62/138,114, filed Mar. 25, 2015, and its successor U.S. patent application Ser. No. 15/080,726 (Attorney Docket No. GUZL-0303, filed on even date herewith, both incorporated by reference herein. Other types of mounting structures for clamping an aligned HGA can be used as well. 
         [0033]    A transporter  322 , supported by support structures  322 A and  332 B extending from base B, includes a carriage  325  that is moveable along a track axis T that is parallel to the X axis. Carriage  325  carries a digital camera  312  and pickers  326  with vacuum-operated fasteners, and is operable operative over and across a top-facing surface of head loader  12  of tester  10 , and particularly along the transport axis T overlying carrier  314  of the first workstation, alignment table  316  of the second workstation and mounting structure MS of the third workstation. Transporter  322  selectively picks up and transfers HGAs to, from and between the components  314 ,  316  and MS. As set forth below, transporter  322  particularly transports an HGA picked from alignment table  316  which has been angularly aligned to a desired testing angle about alignment axis A, and places that HGA on mounting structure, while maintaining the alignment of the HGA at all times at the angular orientation at the alignment table  316 . Since an HGA transported by transporter  322  is aligned for testing at alignment table  316 , it is not absolutely necessary the HGA be transported from the HGA carrier  314  to alignment table  316  while maintaining any particular alignment, or even by the same transporter as in the table  316 -to-MS transport step. However, in the two different embodiments illustrated in  FIGS. 3-3B , the transporter  322  operates over a unitary track along axis T. That track is linear over and between each of components  314 ,  316  and MS, so that rough pre-alignment at HGA carrier  314  enables smaller fine adjustment at table  316 , and is advantageous. 
         [0034]    A computer  14  controls the head tester  10 , and among other things, monitors and controls the interaction of the workstations of HGA loader  12  and the transporter  322 , and carries out other operations well. For example, the other operations may include control of the spinstand, control of interconnections of test equipment to mounted HGAs, and the actual testing of HGAs once they are disposed on mounting structure MS. 
         [0035]      FIGS. 3A and 3B  shows an exemplary alternative form of head and disk tester  10  with the same components except for an alternative form of the mounting structure support at the third workstation, that is, the cartridge-type mounting structure support  324 ′ which is substituted for the simple block element mounting structure support  324  in  FIG. 3 . 
         [0036]    The cartridge-type mounting structure support  324 ′ in  FIGS. 3A and 3B  is of the type of apparatus shown in Provisional Patent Application Ser. No. 62/138,105, and its successor, U.S. patent application Ser. No. 15/081,299 (Attorney Docket No GUZL-0302), filed on even date herewith, both incorporated by reference herein. 
         [0037]    The cartridge-type mounting structure support  324 ′ in  FIGS. 3A and 3B  is a unitary cartridge, or module, providing a self-contained, high accuracy, ready-to-use assembly for controlling fine positioning of an HGA-bearing head mounting unit mounted on the cartridge, with respect to a spinstand or other device associated with a head and disk tester  10 . 
         [0038]    Again, as in  FIG. 3 , the mounting structure MS in  FIGS. 3A and 3B  is of the novel “collet” type of apparatus shown in U.S. Provisional Patent Application Ser. No. 62/138,114, filed Mar. 25, 2015, and its successor U.S. patent application Ser. No. 15/080,726 (Attorney Docket No. GUZL-0303, filed on even date herewith, both incorporated by reference herein. Other types of mounting structures for clamping an aligned HGA can be used as well. 
         [0039]    In operation, a set of HGAs to be tested is initially mounted by an operator, human or robotic, on the HGAs carrier  314 . Thereafter, the operator, again, human or robotic, may initiate a sequential automatic test of the HGAs (one HGA after another). A next HGA to be tested is picked up from the HGAs carrier  314  by the pickers  326  of transporter  322  and is transferred to alignment table  316 . The alignment table  316  interacts with the TV digital camera  312  and rotary actuator  320 , to carry out alignment of the HGA in the X-Y plane. The aligned-for-testing HGA is transferred by the pickers  326  of transporter  322  from the alignment table  316  to the mounting structure MS, with the angular orientation of the HGA in the X-Y plane being maintained unchanged during the transfer. In the mounting structure MS, the base plate  108  of the HGA, is clamped to a mounting surface, the flex circuit  112  is straightened out, followed by fastening to a mounting surface, and the pads  118  of the flex circuit  112  are connected to terminals of a preamplifier (or, what is the effectively same, to pins of a preamplifier pogo pin connector which are electrically connected to the preamplifier). A dynamic test of the HGA in association with a disk is carried out. After completion of the test, the tested HGA is transferred by the transporter  322  back to the HGAs carrier  314 . 
         [0040]    The mounting structure MS, for example, of the type shown in Provisional Patent Application Ser. No. 62/138,114 (the “&#39;114 application”), and its successor US non-provisional application filed on even date herewith, both incorporated by reference herein, consists of a clamping unit (a so-called “collet assembly”) and an interconnection unit IU. The clamping unit clamps the HGA to a mounting surface and the interconnection unit IU connects the pads  118  of the HGA flex circuit  112  to terminals of the preamplifier or other test equipment. The alignment of the HGA being tested at a given time, brings that HGA close to a so-called “reference position”. The reference position is a position of the HGA at the alignment table  316  which ensures that after transfer to the mounting structure MS: (i) the HGA boss hole  110  is centered at a symmetry axis of the clamping unit of the mounting structure MS, and (ii) the pads  118  of the HGA flex circuit  112  are directly under the pogo pins of preamplifier terminals that are located on the interconnection unit IU. With this configuration, the successful clamping of an HGA to the mounting surface, and connection of the pads  118  of the HGA to the preamplifier terminals, are established. 
         [0041]    During a test, the next HGA to be tested is brought to the required position by an alignment procedure that has two stages. The first stage of alignment effects a translation of the HGA, bringing the center of the HGA boss hole  110  into the required position on alignment table  316 . After that operation, a second stage of alignment, a rotation around the center of the HGA boss hole  110 , brings the pads  118  of the HGA flex circuit  112  into their required position. 
         [0042]    The second stage of alignment—the angular alignment of the pads  118 —utilizes a preparatory operation that creates a reference image, that is, an image of the HGA localized in the reference position for each type of HGA to be tested on the tester. Creation of the reference image is performed one time only, before testing of HGAs of the respective type begins. 
         [0043]    The relative positions of the alignment table and the mounting structure MS are known in advance and do not change in time. As a consequence, the expected location of the symmetry axis of base plate of the HGA in the reference position is calculated. After such location is calculated, one HGA, of the type under consideration, is transferred from the HGAs carrier  314  to the alignment table  316 . The HGAs carrier  314  ensures that the boss hole is positioned in the vicinity of the pin at the center of alignment table  316 , so that it slides onto that pin. Then, an image of the HGA is produced by the digital camera  312  and the symmetry axis of the HGA in this image is determined. Comparison of the symmetry axis of the received image with the expected location of the symmetry axis, is used to determine an angular discrepancy w between those axes. A rotation of the alignment table by angle w brings the HGA to a position that is an approximation of the reference positions. 
         [0044]    In general, the approximate reference position, determined in the above-described manner, is not sufficiently precise, and further refinement is necessary. This refinement is fulfilled by the following sequence of operations:
       a. an impression of the location of the preamplifier terminals (or the preamplifier pogo pin connector) is produced by pressing the preamplifier terminals to a pressure sensitive material placed on the mounting structure MS underlying the preamplifier terminals.   b. the digital camera  312  generates an image of the preamplifier terminals impression.   c. one of the HGAs of the set to be tested, is placed on the alignment table and an approximate alignment of the HGA is performed.   d. the HGA is transferred to mounting structure MS and its image is produced by the digital camera  312 .   e. the image of the HGA at the mounting structure MS is compared with the image of the preamplifier terminals impression, and the angle φ between them is measured.   f. the HGA is transferred from the mounting structure MS to the alignment table  316  with its position in the X-Y plane unchanged.   g. the alignment table  316  together with the HGA so-placed on table  316 , is turned by the rotary actuator  320  by an angle φ.   h. an image of the HGA placed at the alignment table  316  is produced by the digital camera  312 , and that image is saved in memory as a reference image for the specific type of HGAs.       
 
         [0053]    After the reference image has been created, the angular alignment of any HGA of the chosen type becomes possible. The angular alignment of the next HGA from the set of that type to be tested, is performed as a sequence of repeated steps. At each step, the digital camera  312  produces an image of the HGA which is held (by vacuum) to the upper surface of the alignment table  316 . A comparison of the received image of the HGA with the reference image of HGA, determines the angular discrepancy between them. The rotary actuator  320  turns the alignment table  316  together with the HGA, which is held to the alignment table  316 , in a direction and amount to reduce the determined discrepancy. This is the end of the current step. That sequence of described steps brings the HGA close to the reference position, so that the goal of the alignment is achieved. 
         [0054]    Operations performed by or at the components of the HGA loader  12  according to an embodiment of the present invention, and the components themselves, will now be described in more detail. 
         [0055]    In order to transfer an HGA from one component to another, the transporter  322  operates to position a picker  326  above the HGA-to-be-transferred at a first component, namely, one of HGAs on carrier  314 , alignment table  316  and mounting structure MS. Then, the transporter  322  first lowers a picker  326  so that it engages the HGA-to-be-transferred, and then uses a vacuum fastener of the lowered picker to couple to the HGA, and, finally, raises the picker  326  together with the coupled HGA. 
         [0056]    Transporter  322  then translates the picker  326  together with the coupled HGA over and across the deck of the tester so that the picker  326  with the coupled HGA overlie a desired different one of the components  314 ,  316  and MS. Transporter  322  then lowers the picker to the component, cuts the vacuum to release the HGA from the vacuum fastener, and raises the picker  326 . All steps including and after the pickup of the HGA from the alignment table  316  are performed while maintaining the angular orientation of the coupled HGA. 
         [0057]      FIGS. 4A-4D  further show digital camera  312  affixed to transporter  322  (movable along the x axis). Digital camera  312  is shown with its components in more detail than in  FIG. 3 , with a view from a different angle than that of  FIGS. 3-3A . With this configuration, digital camera  312  selectively rides by the transporter  322  in the direction of axis T (parallel to the X axis), under control of computer  14 . As shown in  FIGS. 4A-4D , digital camera  312  is positioned over the alignment table  316 . The objective lens of the digital camera  312  faces downward (as illustrated), facing the HGA on alignment table  316 . The objective lens is surrounded by a ring-shaped illuminator  410  that projects light at the HGA on table  316 . 
         [0058]    In the illustrated form, a tail pusher assembly F for flattening the flex circuit  112  (of the HGA on table  316 ) against the upper surface of the alignment table  316 , and holding it in a fixed position on table  316 , is rigidly coupled to transporter  322 . That tail pusher assembly F includes (i) a linear actuator  414  disposed on carriage  325  of transporter  322 , (ii) a driven element  414 A having two parallel arms  414 B extending transverse to the Z axis, (iii) a pressing rod  412 , and (iv) a pair of flat springs  416 . Driven element  414 A is adapted to be selectively driven in the Z direction by actuator  414 , under the control of computer  14 . In another form, the flex circuit flattening tail pusher assembly F is mounted to the base, but otherwise works in a similar manner. 
         [0059]    The flat springs  416  couple distal ends of the two arms  414 B to opposite ends of the pressing rod  412  so that the pressing rod is transverse to the Z axis but generally parallel to the table  316 . 
         [0060]    In operation, in order angularly orient the HGA  100  on alignment table  316  with a desired orientation, and enable digital camera  312  to generate an image of the oriented HGA  100  on table  316 , computer  14  first controls the transporter  322  to position the digital camera  312  to overlie the alignment table  316  with the objective lens of the camera being opposite the HGA, and the pressing rod  412  of tail pusher assembly F overlying and transverse to the flex circuit  112  of the HGA, with the driven element  414 A of the actuator  414  being an uppermost position (as shown in  FIG. 4B  and  FIG. 4D ). In this position, the pressing rod  412  is vertically spaced apart from the flex circuit  112  of the HGA  100 . 
         [0061]    Then, computer  14  controls linear actuator  414  to reposition driven element  414 A to a lowermost position (shown in  FIG. 4A  and  FIG. 4C ), again with the objective lens of the camera being opposite the HGA, and the pressing rod  412  overlying and transverse to the flex circuit  112  of the HGA, but with the pressing rod  412  biased (by flat springs  416 ) against the flex circuit  112 , pressing it against the top surface of table  316 . The digital camera  312  then generates an image of HGA  100  on the table  316 . 
         [0062]    Computer  14  then controls linear actuator  414  to return driven element  414 A of the actuator  414  to its uppermost position (as shown in  FIG. 4B  and  FIG. 4D ) so that pressing rod  412  is again vertically spaced apart from the flex circuit  112  of the HGA. 
         [0063]    Computer  14  then controls actuator  320  to rotationally displace table  316  by angle φ, so HGA  100  has the desired orientation. Then, pickers  526  return to overlie HGA  100  and are driven down to press base plate  108  against the top surface TS of table  316 , and the vacuum holding HGA  100  to the top surface TS is released, and the vacuum to pickers  326  is restored. At that point, while base plate  518  is pressed against top surface TS, pin  518  is withdrawn downward, and pickers  526  lift the oriented HGA  100  and transport it along track T to the third workstation, while maintaining the orientation of HGA  100 . Because base plate  108  is biased against and firmly held to top surface TS, as the pin  518  is withdrawn, incidental interfering engagement of the edges of boss hole  110  and the lateral surfaces of pin  518  do not cause any lateral displacement or change in the orientation of HGA  100 . 
         [0064]    A cross-section of the exemplary alignment table  316  is shown in  FIG. 5  with respect to the alignment axis A, parallel to the Z axis. The separate components of the alignment table  316  and the rotary actuator  320  are shown in  FIG. 6 . The alignment table  316  comprises a rotatable disk  502  rigidly coupled to a revolving part  516  of the rotary actuator  320 . In the center of the rotating disk  502 , a suction bushing  504 , perforated by sucking (vacuum) conduits  510 , is built-in. The suction bushing  504  defines at its uppermost surface, the planar, annular top surface TS for supporting (as shown in  FIG. 5 ) surface of the base plate  108  of an HGA  100  mounted thereto. 
         [0065]    The rotating disk  502 , the suction bushing  504  and a cylindrical insert  506 , define a vacuum chamber  508  with sealing O-rings  512 . Exhausting channels  514  connect the vacuum chamber  508  with vacuum inlets  522 . Vacuum applied by way of inlets  522  effect a holding force to the base plate of the mounted HGA  100 , biasing the HGA against the top surface TS. 
         [0066]    There is a central bore B in the suction bushing  504 , which contains a retracting pin  518  with a tapered top end and broadened bottom end. As noted above, the pin  518  is moveable up and down along the alignment axis A, as described below. The space under the retracting pin  518  is coupled through an inlet  520  to a source of pressurized air (not shown). A spring  524  (see  FIG. 6 ) is placed between the broadened bottom end of the retracting pin  518  and the cylindrical insert  506 . 
         [0067]    Before the transporter  322  brings a next HGA to the alignment table  316 , pressurized air at the inlet  520  is switched on. Under the action of the pressurized air, the retracting pin  518  moves upward to an uppermost position so that the tapered end of the retracting pin  518  extends beyond an upper surface of the suction bushing  504 . In operation, an HGA (carried by picker  526  extending downward from carriage  325 ) is lowered onto the top surface of the alignment table  316  along the direction of the alignment axis A (parallel to the Z axis) by the transporter  322 . As the HGA approaches the top surface of table  316 , the picker  526  causes boss hole  110  of the HGA to slip over the tapered end of the retracting pin  518 . In response to continued downward motion of picker  526 , base plate  108  passes over the tapered end of the retracting pin  518 , and pin  518  pulls the boss hole  110  into its proper location, causing a corresponding translation of the HGA in the X-Y plane and bringing the center point CP of the HGA boss hole  110  into the required position with the HGA mounting axis coaxial with the alignment axis. 
         [0068]    After the HGA  100  is placed on the top surface TS of the alignment table  316 , vacuum is switched on, and applied to vacuum inlets  522 . The vacuum passes through the exhausting channels  514 , through the vacuum chamber  508 , through the sucking conduits  510  and creates a low pressure above the upper surface of the suction bushing  504 . In response to that low pressure, the base plate  108  of HGA  100  is pulled down to (or biased against) the planar, annular top surface TS of the suction bushing  504  and is locked there, so that any displacement in the X-Y plane is prevented. Before removing the HGA  100  from the alignment table  316 , pressurized air is applied to inlet  520  and the delivery of vacuum to the vacuum inlets  522  is terminated. With these changes in pressure, the force of the spring  524  causes the retractable pin  518  to move downward to a lowermost position under the upper surface of the alignment table  316 . The absence of vacuum frees the HGA so that the transporter  322  is able to raise the HGA and to transfer it from the alignment table  316  to the mounting surface MS for testing, all without changing the angular orientation of the HGA. 
         [0069]    The advancement of the retractable pin  518  to its lowermost position eliminates possible friction between the inner surface of HGA boss hole  110  and external surface of the retractable pin  518  during the lifting of the HGA by the transporter  322 . Such friction might otherwise create forces which would displace the HGA in X-Y plane and damage the accomplished alignment, a result that is undesirable. 
         [0070]    The mounting support MS is a part of a cartridge  324  incorporated in the tester, and contains a clamping unit and an interconnection unit. The clamping unit can be a well known component of a HGA loader, or it may be of the type disclosed in the &#39;114 application incorporated by reference herein. 
         [0071]    The interconnection unit IU according to the present invention is shown in  FIGS. 7A-7B . The interconnection unit has a moving part  701  that may be turned up (as in  FIG. 7B ) and down (as in  FIG. 7A ) around a horizontal axis by an air-operated actuator  702 . Preamplifier terminals are mounted at the bottom surface of the moving part  701 . 
         [0072]    Before the transporter brings a next HGA to the mounting support MS, the moving part  701  is turned up, as shown in  FIG. 7B . Then, the oriented HGA  100  is lowered to mounting support MS and released by pickers  526 , so that the HGA base plate  108  is positioned at the clamping unit. At the same time, the flex circuit  112  of the HGA is positioned on a surface of an adjacent bench  710 . Vacuum ports hold the flex circuit  112  against the clamping unit. The clamping unit of the mounting support MS clamps the HGA base plate  108  to a mounting surface. In the interconnection unit IU, the flex circuit  112  of the HGA is flattened and fastened to a mounting surface of the interconnection unit IU. The moving part  701  rotates down to its original position  7 A and presses preamplifier terminals of the clamping unit (preferably, pogo pin connectors) against the pads  118  of the flex circuit  112 , establishing the desired electrical connection. 
         [0073]      FIGS. 8A-8B  show a rear side of an interconnection unit IU with moving part  701  being raised, so that a roller  712  may be seen. The roller  712  is moved by an air-operated actuator  714  through a lever  716 .  FIG. 8A  shows the interconnection unit with the roller  712  in an initial position (top position). In the  FIG. 8B  the roller  712  has been moved down and is ready to flatten the HGA&#39;s flex circuit  112  in a depression  704  in the mounting surface of bench  710 . A second depression in the mounting surface of bench  710 , with a port to a selectively applied vacuum source, underlies to location where the head  102  of HGA is positioned. In  FIG. 8C , the roller  712  has finished flattening of the flex circuit  112 . As the roller  712  flattens the flex circuit  112 , vacuum is applied to the port(s) in the second depression. At the last step of this procedure, the roller  712  is raised and returns to the position shown in  FIG. 8A . 
         [0074]    As it follows from the preceding description, the embodiment of the present invention not only places the boss hole  110  of the HGA in a desired (for testing) position, but also aligns the flex circuit  112  by turning the HGA to a necessary angle for a desired orientation. In that way, a displacement of flex circuit pads  118  relative to the preamplifier terminals, is corrected and the reason for unjustified rejection of tested heads is eliminated. 
         [0075]    According to the present invention, a retractable pin  518  is introduced in the alignment table  316 . After the alignment is accomplished, the retractable pin  518  is lowered to be beneath the upper surface of the alignment table  316 . The delivery of vacuum to the vacuum inlets  410  stops, freeing the HGA. When the HGA is raised by the transporter  322  before the transfer to the mounting structure MS, there is neither contact nor friction between the inner surface of HGA boss hole  110  and the retractable pin  518 . In that way, a cause of interference between the HGA and the pin, and consequent misalignment, is removed. 
         [0076]    Although the foregoing description of the embodiment of the present invention contains some details for purposes of clarity of understanding, the invention is not limited to the detail provided. There are many alternative ways of implementing the invention. The disclosed embodiment is illustrative and not restrictive.