Abstract:
A new method and apparatus is provided to quickly and reliably position, connect and dock a handler plate with a test head plate of a Universal Docking System. A handler plate is provided with roller assemblies while a test head plate is provided with matching receiver block assemblies. The roller assemblies are aligned with and partially inserted into the receiver block assemblies. Part of the roller assembly is mechanically engaged by the receiver block assembly, a mechanical linkage between an operator handle and the receiver block assembly allows the operator to complete the locking of the test head plate with the handler plate thereby at the same time establishing electrical contacts between arrays of pins that are mounted on surfaces of the handler base plate and the test head.

Description:
[0001]    This application is related to patent application ST98-005, Ser. No. 09/174,620 filed on Oct. 19, 1998, assigned to a common assignee. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    (1) Field of the Invention  
           [0003]    The invention relates to the fabrication and the testing of Integrated Circuit (IC) devices, and, more particularly, to an apparatus for a robust Universal Docking System that is used for purposes of docking and undocking of an electronic test head with a semiconductor device handler.  
           [0004]    (2) Description of the Prior Art  
           [0005]    In the automatic testing of Integrated Circuits (IC) and other electronic devices, special device handlers are used to place the device that is to be tested in position. The electronic testing itself is provided by a large and sophisticated automatic testing system that includes a test head. The test head is required to connect to and dock with the device handler. In such testing systems, the test head is usually very heavy. The reason for this heaviness is that the test head uses high-speed electronic timing signals. The electronic test circuits must therefore be located as close as possible to the device under test. Accordingly, the test head has been densely packaged with electronic circuits in order to achieve high speed testing of state of the art devices.  
           [0006]    The state of the art leaves much to be desired in providing a manipulator or positioner that readily and accurately moves the heavy test head in position with respect to the device handler mechanism. The user typically must move the heavy device handler or the heavy positioner in order to provide alignment. When the test head is accurately in position with respect to the device handler, the test head and the device handler are said to be aligned. After the test head and the device handler have been aligned, the fragile test head and the device handler electrical connections can be brought together (that is docked) thereby enabling the transfer of test signals between the test head and the device handler. Prior to docking, the test head and the device handler electrical connections must be precisely aligned to avoid damaging the electrical connectors.  
           [0007]    In a typical operational environment that has as function the electrical testing of semiconductor devices, the test head is manually guided to connect delicate electrical pins to the contacting plate of the device handler, without thereby making use of alignment guides. After this operation of guiding the test head has been completed (that is the test head has been positioned in the location where the test head can be connected and docked with the device handler) the test head is locked or kept level by means of a device manipulator. This often presents problems during production testing. For instance, the position of the test head can change as a consequence of which the electrical connections with the device handler are interrupted. Or the device handler vibrates causing intermittent electrical connections with the device test head or even causing damage to the electrical equipment.  
           [0008]    Due to the complexity and density of advanced, sophisticated semiconductor devices, the number of connections that must be provided to the semiconductor device during the test operation can be very large resulting in a heavy cable that must be connected to the device under test. This heavy cable provides increased weight and mass that further aggravates the problem of establishing and maintaining firm positioning between the test head and the device handler of the semiconductor device. Special arrangements are typically provided for the heavy interconnect cable, which address problems of being able to position the test head into the desired position without interference by the cable, providing flexibility in positioning of the test head without interference by the heavy cable, avoiding interference of the cable with freedom of movement that must by provided to the operator of the test equipment, keeping the length of the cable at a minimum to avoid negative electrical performance aspects that can be introduced as a consequence of a long electrical path to the device under test, maintaining mechanical stability to the combined and interlocked device handler and the test head thereby negating the need for mechanical counterbalancing arrangements, and the like.  
           [0009]    Prior Art methods of positioning the test head with respect to the device handler frequently use lead screws and sliding/rotating mechanisms of various designs that assisted in the positioning of the test head with respect to the device handler. These mechanisms are in addition frequently aided by electrical motors that provided three-dimensional degree of movement in addition to rotational movement of the components of the test assembly. The various motions that are provided in this manner are however difficult to control to the required degree of accuracy leading to potential damage to device or test head pins, pins that are in most cases of a delicate nature and therefore easily damaged. The addition of the indicated components such as electrical motors and the like further require extensive floor space and do therefore not meet the need that positioning apparatus must be of a simple but sturdy design.  
           [0010]    Semiconductor device testing can further take place in a clean room environment. Where this ability to perform device testing in a clean room environment is required, this requirement must not add a significant amount of either expense or complexity to device testing components such as device handler, test head and positioning and docking arrangements that are required for the device testing. Usable space within a clean environment usually involves considerable expense in providing this clean room environment, further emphasizing the need for test components that are simple in design and sturdy in their application.  
           [0011]    U.S. Pat. No. 5,440,943 (Holt et al.) shows test head manipulator that facilitates docking and docking of the test heads and device handlers.  
           [0012]    U.S. Pat. No. 4,893,074 (Holt et al.) and U.S. Pat. No. 5,149,029 (Smith) show other testing systems with test heads and device handlers.  
           [0013]    U.S. Pat. No. 5,600,258 (Graham et al.) (inTEST Corporation) shows an automated docking test head and device handler.  
         SUMMARY OF THE INVENTION  
         [0014]    The present invention addresses the problem of quickly and reliably positioning and interlocking a Universal Docking system (UDS) handler plate with respect to a UDS test head plate.  
           [0015]    The primary objective of the present invention is to provide an apparatus for establishing quick and reliable connections between a semiconductor device handler plate and a semiconductor device test head plate.  
           [0016]    Another objective of the present invention is to reduce the negative effect on device yield caused by unreliable interconnection between a device handler plate and a device test head plate.  
           [0017]    Yet another objective of the present invention is to reduce the need for device re-testing due to unreliable testing results caused by unreliable device handler plate to device test head plate connections (re-screen downtime reduction).  
           [0018]    Yet another objective of the present invention is to reduce the downtime required for changing equipment set-up in semiconductor testing and manufacturing environments.  
           [0019]    In accordance with the objectives of the invention a new method and apparatus is provided to quickly and reliably position, connect and dock a handler plate with a test head plate of a Universal Docking System. The handler plate is provided with at least two roller assemblies whereby each roller assembly consists of a main body or block to which four roller bearings or dowel pins are connected whereby the roller bearings protrude from the vertical body of the roller assembly in a horizontal plane. The test head plate is provided with at least two matching (with the roller assemblies of the handler plate) receiver block assemblies to which a sliding block is attached. Each receiving block assembly of the test head plate is provided with a sliding block whereby the sliding blocks are interconnected with a pivoting linkage assembly such that the movements of the sliding blocks (and with that the movements of the receiving blocks) are synchronized with respect to each other. Each sliding block is provided with a cutout that is designed such that a roller bearing (of the roller assembly) can slide through this cutout. After positioning the roller block with respect to the receiver block and engaging (by the sliding block) at least one of the roller bearings of the roller assembly, the sliding block will be (manually) forced in a direction such that the roller bearing (that now slides through the cut-out of the sliding block) will be further inserted into the receiving block. Since the roller assembly is attached to the handler plate and the receiver block is attached to the test head plate, the action of forcing the roller bearing into the receiver block results in forcing the handler plate closer to the test head plate. The pivoting arrangement that is part of the sliding block assembly synchronizes the motions of the sliding blocks such that, for all receiving blocks, the roller bearings will enter the receiving blocks at the same rate resulting in the plane of the handler plate and the plane of the test head plate remaining parallel during the process of bringing the two plates together. After the roller bearings of the roller assemblies have been forced into the receiver blocks, thereby positioning and locking the handler plate with respect to the test head plate, electrical contact between the electrical contacts of the device handler and the electrical contacts of the device test head has been established. The device is now securely positioned for testing.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 a  shows a three-dimensional view of the device handler plate and the device test head plate, components that are part of these two assemblies are highlighted.  
         [0021]    [0021]FIGS. 1 b  and  1   c  show a side view and a cross section of two interacting components that are part of the test head plate of the invention.  
         [0022]    [0022]FIG. 1 d  shows the relative positioning of major system components, such as device handler, a device prober and the like, that make use of the docking system of the invention.  
         [0023]    [0023]FIG. 2 a  shows a cross section of the handler plate and the test head plate at the time when these two plates are not engaged but are in approximate alignment with each other. Cross sections of the components that are part of the two assemblies are also indicated.  
         [0024]    [0024]FIGS. 2 b  shows a three dimensional view of a receiver block and a sliding block.  
         [0025]    [0025]FIG. 2 c  shows a three dimensional view of a roller assembly with roller bearings.  
         [0026]    [0026]FIG. 2 d  shows the UDS handler plate in more detail.  
         [0027]    [0027]FIG. 3 a  shows a cross section of the handler plate and the test head plate during the initial step of the docking process between the handler plate and the test head plate.  
         [0028]    [0028]FIG. 3 b  shows further detail regarding the test head plate.  
         [0029]    [0029]FIG. 4 shows a cross section of the handler plate and the test head plate at the point during the docking process when the roller bearings of the roller assembly have been partially inserted into the receiver block assembly of the test head plate.  
         [0030]    [0030]FIG. 5 shows a cross section of the handler plate and the test head plate at the point during the docking process when the pivoting link assembly of the sliding blocks (that are attached to the receiver blocks of the test head plate) pushes the sliding blocks in a horizontal direction forcing the roller assembly down along a sloping cavity that is provided in the sliding block thereby forcing the roller bearing/roller assembly into the receiver block.  
         [0031]    [0031]FIG. 6 shows a cross section of the handler plate and the test head plate at the point during the docking process when the roller bearings (of the roller assembly of the handler plate) have been fully inserted into the receiver assemblies (of the test head plate) thereby positioning and docking the handler plate with respect to the test head plate and thereby furthermore establishing electrical contact between the electrical contacts of the handler plate and the electrical contacts of the test head plate.  
         [0032]    [0032]FIG. 7 shows a docking square.  
         [0033]    [0033]FIG. 8 shows a docking triangle. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    Referring now specifically to FIG. 1 a , there is shown a three dimensional view of the device handler plate  10  and the device test head plate  12 . The handler plate  10  is provided with roller assemblies, the test head plate  12  is provided with receiver blocks to which sliding plates are attached.  
         [0035]    The operation of the apparatus of the invention can be summarized as follows: the roller assemblies (part of the handler plate) are aligned with and minimally inserted into the receiver block assemblies (part of the test head plate). Operator action further forces the complete entry of the roller assembly into the receiver block assembly. Operator action requires the turning of a handle, which motion is translated into a motion of sliding plates that are part of the receiver block assembly. This sliding motion results in the indicated insertion of the roller assemblies into the receiver block assemblies.  
         [0036]    The components that are part of these two assemblies are the following:  
         [0037]    [0037] 10  is the handler plate  
         [0038]    [0038] 12  is the test head plate  
         [0039]    [0039] 14  is a roller assembly that is part of and attached to the handler plate  10 . The handler plate  10  is provided with at least two roller assemblies  14 , the three dimensional view that is shown in FIG. 1 a  shows two roller assemblies  14  that are mounted on opposing corners of the handler plate  10 . The handler plate can be provided with a total of four roller assemblies  14  whereby these four roller assemblies are mounted on the four corners of the handler plate  10  with one roller assembly  14  on each of the four corners of the handler plate  10 . The method and apparatus of the invention are not limited to four roller assemblies per handler plate but can, dependent on specific design requirements, be extended beyond the number of four; this number can also be reduced to two or three roller assemblies. Roller block assemblies  14  have been provided in the X-direction of the handler plate  10  at a first Y-coordinate of the handler plate  
         [0040]    [0040] 15  is one of the (four) roller bearings that is attached to and forms part of the roller assembly  14 ; the construct is not limited to four roller bearings per assembly and is dependent on specific design requirements; the number of roller bearings can range from two roller bearings and up  
         [0041]    [0041] 16  is the relative vertical motion (Z-direction, see Cartesian diagram of FIG. 1 a ) of the handler plate  10  with respect to the test head plate  12   
         [0042]    [0042] 17  is (one of two) roller assemblies that have been provided in the X-direction of the handler plate  10  at a second Y-coordinate of the handler plate  
         [0043]    [0043] 18  is the relative X-direction motion of receiver block assemblies  20 / 21  and  23 / 25  with respect to the test head plate  12   
         [0044]    [0044] 20  is a first receiver block assembly that is part of the test head plate  12   
         [0045]    [0045] 21  is a second receiver block assembly that is part of the test head plate  12 ; receiver block assemblies  20  and  21  are mounted in the X-direction of the test head plate  12   
         [0046]    [0046] 22  is a receiver block that is part of the receiver block assembly  20 . The test head plate can be provided with a total of four receiver block assemblies  22  whereby these four receiver block assemblies are mounted on the four corners of the test head plate with one receiver block assembly on each of the four corners of the test head plate  12 . The method and apparatus of the invention are not limited to four receiver block assemblies per test head plate but can, dependent on specific design requirements, be extended beyond the number of four or can be reduced to two or three receiver block assemblies  
         [0047]    [0047] 23  and  25  are receiver block assemblies that are mounted in the X-direction of the test head plate  12  but that have Y-coordinates of the test head plate  12  that differ from the Y-coordinates of the receiver block assemblies  20 / 21   
         [0048]    [0048] 24  is a cavity that has been provided in the receiver block  22  whereby the horizontal cross section of cavity  24  is essentially the same as the horizontal cross section of the roller block assembly  14  such that the roller assembly  14  can penetrate cavity  24  and is, in this penetration, guided by the inside walls of cavity  24  (see FIGS. 2 b  and  2   c  following). Each receiver block of the invention is provided with a cavity that is identical to cavity  24   
         [0049]    [0049] 26  is a sliding block that is attached to the receiver block  22  such that the sliding block  26  and the receiver block  22  form one mechanical unit that moves in unison. Key to the method of the invention is that the sliding block  26  has been provided with a cavity (not shown in FIG. 1 a ) that matches and aligns with one of the roller bearings of the roller assembly  14 . The function of this cavity will become clear under the following artwork of the present invention  
         [0050]    [0050] 28  is a pivot linkage assembly that contains components  30 ,  32 ,  34 , and  36 , these components will be explained following  
         [0051]    [0051] 30  is an X-directional cross-link bar that interconnects receiver block assembly  20  with receiver block assembly  21 . The distance between receiver block assembly  20  and receiver block assembly  21  remains fixed once these two receiver block assemblies have been interconnected by the X-directional cross link bar  30   
         [0052]    [0052] 32  is an Y-directional cross-link bar that interconnects receiver block assemblies  20 / 21  with receiver block assemblies  23 / 25 . The distance between receiver block assemblies  20 / 21  and receiver block assemblies  23 / 25  remains fixed once these two receiver block assemblies have been interconnected by the Y-directional cross link bar  32   
         [0053]    [0053] 34  is an insertion handle that is used (by an operator) to force the roller assembly into the cavity  24  of the receiver block  22  by means of the cavity (not shown in FIG. 1 a ) that has been provided for this purpose in the sliding block  26   
         [0054]    [0054] 36  is an insertion plate to which the insertion handle  38  is mechanically and fixedly attached, the insertion plate  36  translates the rotational motion of insertion handle  34  into a sliding motion of the sliding block  26  (see FIGS. 1 b  and  1   c  following)  
         [0055]    [0055] 37  is the point at which the insertion plate  36  is rotationally attached to the test head plate  12   
         [0056]    [0056] 38  is the direction of rotation that is provided by an operator to the insertion plate  36  by means of the insertion handle  34   
         [0057]    [0057] 39  is a cut-out in the insertion plate  36  through which a motion pin (not shown) that is attached to the sliding block  26  can slide thereby translating the rotational motion  38  of handle  34  into a sliding motion of the sliding block  26  (see FIGS. 1 b  and  1   c  following). At the time that the roller bearing has been (manually) inserted into the cavity (not shown in FIG. 1 a ) that has been provided for this purpose in the sliding block  26  to the point where the roller bearing can be engaged by the cavity, the operator turns the insertion handle  34  thereby rotating the insertion plate  36  thereby translating the rotation of the insertion plate  36  into a sliding motion of the sliding block  26 . The sliding motion of the sliding block  26  forces the roller assembly  14  further into the cavity  24  of the receiver block  22  in a direction  16  and toward the test head plate  12 , and  
         [0058]    [0058] 40  is the pivoting point for the Y-directional cross link bar  32 ; by providing the Y-directional cross link bar  32  the insertion of roller bearings that belong to roller assemblies  14  that have been provided in the X-direction of the handler plate  10  at a first Y-coordinate of the handler plate is coordinated with the insertion of the roller bearings that belong to roller assemblies  17  that have been provided in the X-direction of the handler plate  10  at a second Y-coordinate of the handler plate. This latter action that is provided by the pivot link assembly  28  is important for the concurrent and accurate insertion of X-directional roller bearings that have been provided at different Y-dimensions of the handler plate  10 .  
         [0059]    [0059]FIGS. 1 b  and  1   c  further highlight the operation of the insertion plate  36  in conjunction with the sliding block  26 . The views that are shown in FIGS. 1 b  and  1   c  demonstrate how the rotational action of the plate  36  is transposed into a sliding action of the sliding plate  26 . The components that are shown in FIGS. 1 b  and  1   c  have previously been highlighted under FIG. 1 a  with the exception of the pin  27 , which is attached to and forms part of the sliding block  26 . Pin  27  is inserted into the slot  39  that has for this purpose been provided in plate  36 , plate  37  rotates around point  37  as a consequence of the rotating action  38  (FIG. 1 a ). During the rotation of plate  36  therefore pin  27  will be moved to different positions inside slot  39  which in turn makes the sliding block  26  move to different positions. In short: by turning the handle  34 , the sliding block  26  is moved under the actions that are highlighted by FIGS. 1 b  and  1   c.    
         [0060]    Referring now specifically to FIG. 1 d , there is shown the relative positioning of the device handler  1 , the device prober  5 , the device test head  4 , and the two Universal Docking System (UDS) plates, that is the UDS handler plate  2  and the UDS test head plate  3 . The UDS handler plate  2  together with the UDS test head plate  3  form a mechanical system, which aligns, connects and disconnects with respect to each other by means of four pairs of interlocking mechanical sub-assemblies.  
         [0061]    The UDS handier plate  2  (FIG. 1 d ) is attached to the device handler  1  (FIG. 1 d ) or the device prober  5  (FIG. 1 d ). Its function is equivalent to the test handler function, the UDS test head plate  3  (FIG. 1 d ) is attached to the device test head plate  4  (FIG. 1 d ). The UDS handler plate  2  (FIG. 1 d ) with its subassembly plus the UDS test head plate  3  (FIG. 1 d ) with its subassembly form the Robust Universal Docking System (RUDS). The UDS serves as the mechanism for aligning, connecting and disconnecting the two systems with they interface. In FIG. 1 d , these two systems are device handier and the device tester.  
         [0062]    [0062]FIG. 2 a  shows a cross section of the handler plate  10  and the test head plate  12  at the time when these two plates are not engaged but are in approximate alignment with each other. Cross sections of the components that are part of the two assemblies are the following:  
         [0063]    [0063] 42  is an assembly of electrical contact points that are provided in the handler plate  
         [0064]    [0064] 44  is an assembly of electrical contact points that are provided in the test head plate  
         [0065]    [0065] 46  is a cavity that has been provided in the sliding block  26  and that is used for the insertion of the roller assembly by means of the roller bearings as detailed above  
         [0066]    [0066] 47  is the slope of cavity  46 , and  
         [0067]    [0067] 48  are the roller bearings of the roller assembly  14 .  
         [0068]    The profile of the cavity  46  that is provided in the sliding block  26  is such that if the sliding block  26  is moved in direction  45  after a roller bearing  48  has been inserted into the cavity  46  to the point where the upper surface of the roller bearing is at the level or slightly below the slope  47  of the cavity  46 , the slope  47  will press the roller bearing  48  in a downward direction (Z-direction) as a result of the force  34  (FIG. 1 a ). The receiving block assemblies  20 / 21  (FIG. 1 a ) will, as a result move in the direction  45  which further results, as detailed above and by the means of the pivot linkage assembly  28  and the pivoting of the cross link bar  32  that pivots around the pivoting point  40 , in a movement of block assemblies  23 / 25  in a direction that is opposite to direction  45 .  
         [0069]    [0069]FIG. 2 b  shows three dimensional views of the receiver block  22  with the matched sliding block  26  and the groove  46  that has been provided in the sliding block  26 . It is clear from FIG. 2 b  that if a roller assembly is entered into cavity  24  whereby one roller bearing  48  (FIG. 2 c ) protrudes through opening  29  and into groove  46 , the slope  47  of groove  46  can further force the roller assembly into the cavity  24  if the sliding block  26  moves in direction  45 .  
         [0070]    [0070]FIG. 2 c  shows a three dimensional view of the roller assembly  14  with the thereto attached roller bearings  48 .  
         [0071]    [0071]FIG. 2 d  provides additional detail regarding the UDS handier plate  20 . In a typical application, the UDS handier plate  20  is an 8 mm thick aluminum plate that is 876×876 mm square in size. The dimensions for this plate are however not limited to the typical dimensions indicated, the center  21  of the UDS handier plate  20  is cut out so as not to interfere with any electrical or mechanical components of the test head. The UDS handler plate  20  is mounted against the device handler base plate. Threads are tapped into the handler base plate for screws to fasten the UDS handier plate  20  with the handier base plate.  
         [0072]    [0072]FIG. 2 d  also shows the UDS handier plate  20  with adjustment slot guides  41  and side adjustment hole locations  42 . For conversions of the tester where testing is required on more than one center site, such as a second or third site testing, the slot guides  41  are used in conjunction with a suspended screw (not shown) attached to the device handler  1  (FIG. 1 d ) to shift the UDS handler plate  2  (FIG. 1 d ) into the second or third test position. The site adjustments have the same function in adjusting the UDS handler plate  2  (FIG. 1 d ) to positions other than the central test position with respect to the test head  4  (FIG. 1 d ).  
         [0073]    [0073]FIG. 3 a  shows a cross section of the handler plate  10  and the test head plate  12  during the initial step of the docking process between the handler plate and the test head plate. The roller assemblies  14  are initially positioned into the openings  24  (FIG. 1 a ) of the receiver block  22 . The cone shaped extension  50  of the roller assembly aids in positioning the roller assembly with respect to the geometric center of the openings  24 . Further shown in FIG. 3 a  are the regions within the openings  24  where the parts that make up the roller assembly will penetrate the opening, as follows:  
         [0074]    the regions highlighted as  52  that are bounded by the dotted lines on each side of the regions are the regions where the roller bearings of the roller assembly will penetrate the opening  24 , and  
         [0075]    the regions highlighted as  54  that are bounded by the dotted lines on each side of the regions are the regions where the main body of the roller assembly will penetrate the opening  24 .  
         [0076]    [0076]FIG. 3 b  shows the test head plate  70 , this assembly has three main bar members which are mounted in a “U” shape structure. The U-bar mounts around the device test head  4  (FIG. 1 d ) using adjustable “Zee mounting brackets”  71 . This Zee mounting brackets will help to adjust and lock the test head plate  70  in required position in the “Z” direction (depending on the thickness of the test socket interface.  
         [0077]    Basic geometry teaches that three points fixed in space define a plane. It is therefore apparent that, in order to accomplish the alignment of one plane with another, such as the UDS handier plate  2  (FIG. 1 d ) with the UDS test head plate  3  (FIG. 1 d ), three points of suspension suffice for each of these two plates. This leads to the concept of the three point docking system. This as opposed to the four point docking system as highlighted in FIG. 2 d  and FIG. 3 d  where the UDS handler plate  20  and the UDS test head plate  70  are detailed. FIG. 7 and FIG. 8 highlight the concept of the four and three point docking system respectively, this is further highlighted below.  
         [0078]    [0078]FIG. 4 shows a cross section of how, after the handler plate  10  and the test head plate  12  at the point during the docking process when the roller bearings  48  of the roller assembly  14  have been partially inserted within the receiver block assemblies  20  and  21  (or  23 / 25 ) of the test head plate  12 . The roller bearings  48  are at this point far enough inserted into opening  24  of the receiver block assemblies that the slope  47  of cavity  46  that has been provided in the sliding block  26  can engage the roller bearings. This engaging of the roller bearings is achieved by the rotating motion of insertion handle  38  (FIG. 1 a ). The sloping profile of the cavity  47  will, as previously highlighted under FIG. 2 a , further force the roller bearings into the cavity  24  of the receiver block thereby pressing the handler plate  10  closer to the test head plate  12 . It must be noted that, at the time that the roller bearings can be engaged by the sloping cavity  46 , the points of electrical contact that are present in the handler plate  10  and in the test head plate  12  are aligned even though at this time these contact points are yet are not touching (FIG. 4).  
         [0079]    [0079]FIG. 5 shows a cross section of the handler plate  10  and the test head plate  12  at the point during the docking process when the pivoting link assembly of the sliding blocks (that are attached to the receiver blocks of the test head plate) pushes the sliding blocks in a horizontal direction  45  forcing the roller bearings  48  down along a sloping cavity  47  that is provided in the slider block thereby forcing the roller assembly  14  into the receiver blocks  20 / 21  and  23 / 25 . Concurrent with this motion the electrical contact points provided in assemblies  42  (for the handler plate  10 ) and  44  (for the test head plate  12 ) are brought closed together.  
         [0080]    [0080]FIG. 6 shows a cross section of the handler plate  10  and the test head plate  12  at the point during the docking process when the roller bearings  48  (of the roller assemblies  14  of the handler plate  10 ) have been fully inserted into the receiver assemblies  20 / 21  and  23 / 25  (of the test head plate  12 ) thereby positioning and docking the handler plate with respect to the test head plate and thereby furthermore establishing electrical contact between the electrical contacts  42  of the handler plate  10  and the electrical contacts  44  of the test head plate  12 . It must be noted from the cross section that is shown in FIG. 6 that the sloping nature of cavity  47  is, at the end of the trajectory of the roller bearings  48  into cavity  24 , the sloping nature of the cavity is converted into a horizontal top surface of the cavity. This horizontal or end section of cavity  47  provides the point where the roller bearings come to rest after insertion and is therefore needed as a horizontal surface (for the roller bearings) in order to provide stability in the (final) positioning of the roller bearings.  
         [0081]    It further deserves pointing out that the cross section that is shown in FIG. 6, which shows a set of two roller assemblies and two receiver block assemblies, can be replicated by a similar cross section that can be made of the second set of two roller assemblies and two receiver block assemblies that are part of the method and apparatus of the invention. This second cross section will look similar to the cross section that is shown in FIG. 6 due to the action of the cross bar  32  and the pivoting action  40  that is provided to this cross bar  32 . This cross bar engages the second set of roller assemblies and receiver block assemblies causing these roller assemblies and receiver block assemblies to be engaged and lock as shown for the first set of roller assemblies and receiver block assemblies in FIG. 6.  
         [0082]    Referring now to FIG. 7, there is shown how the four points 1, 2, 3 and 4 provide docking possibilities of 0-degree, 90degree and 180-degree docking rotation.  
         [0083]    Referring to FIG. 8, there is shown a three point docking configuration whereby three points 1, 2, 3 provide less freedom in possible docking configurations since this configuration limits the docking to one configuration. This limitation is however not to be considered a drawback or limitation of the present invention since there are conditions of device testing where this configuration, due to its very simplicity, can be a configuration of choice, most notably where considerations of high device throughput, speed of test set up and the like are of importance.  
         [0084]    It is clear that the method and process of the invention, that has as objective the positioning and docking of a handler plate with respect to a test head plate, can be provided with a number of variations that are directly derived from the method and process that has been described in detail. For instance, the number of roller assemblies can be varied as can the number of receiver block assemblies. The method and process of the invention can in this manner be applied to a large surface where such an application is of benefit. Increasing the number of roller assemblies and receiver block assemblies can also result in increased accuracy of alignment and in increased stability of the docking condition. The method and process of the invention is therefore not limited to the steps and apparatus that has been described above and that serve as an example that can readily be extended in order to extend the use and benefit that is provided by the invention.  
         [0085]    Although the invention therefore has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the spirit of the invention. It is therefore intended to include within the invention all such variations and modifications which fall within the scope of the appended claims and equivalents thereof.