Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a device test handler, and more particularly, to a device test handler which facilitates room temperature as well as elevated or lower temperature testing of a logic device; and a method for operating the same.  
           [0003]    2. Background of the Related Art  
           [0004]    In general, a semiconductor device undergoes a test for inspection of defects after completion of fabrication on a production line. The device test handler is employed in testing various logic devices, such as QFP, BGA, PGA, SOP and the like, which are mostly non-memory semiconductor packages. During such testing, the device is placed in a tray which travels through the test machine. At some point, the logic device is tested at a test part. The logic devices are then unloaded onto trays after classifying the devices into different grades according to a result of the test. Different classifications of logic devices are loaded into different trays.  
           [0005]    However, the related art device test handler has the following problems. First, the frequent pickup and placing of logic devices by the related art device test handler causes breakage to the expensive logic devices during testing, and also prolongs index times.  
           [0006]    Second, the related art device test handler has a test part that temporarily holds the logic devices to be tested in test sockets for a time period until the testing is completed. There is an indexing device for automatic and continuous transportation and loading of the logic devices to be tested from input trays into the test socket, and for unloading the tested devices from the test socket to an unloading tray. However, the indexing device in the related art device test handler is quite complicated. For example, the indexing device disclosed in JP Laid Open Patent No. H10-82830 (Mar. 31, 1998) has a system in which two contact hands reciprocate in two directions for loading and unloading the logic devices in succession. This system was intended to reduce the index time compared to other indexing devices without increasing a number of components of the indexing device. However, this indexing device, which transports the logic devices in both directions, requires a separate device for continuous and simultaneous placing and picking up of the logic devices to/from two stages loaded on shuttles on both sides of the indexing device. As a result, the whole system of the related art device test handler becomes complicated because the separate device is very complicated and difficult to operate.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, the present invention is directed to a device test handler and a method for operating the same that substantially obviates one or more of the problems, limitations and disadvantages of the related art.  
           [0008]    An object of the present invention is to provide a device test handler, which can conduct room temperature or elevated temperature testing, and a method for operating the same, which can reduce frequent picking and placing of logic devices. As a result, damage to the logic devices is minimized, and an index time is reduced.  
           [0009]    Another object of the present invention is to provide an indexing device for a device test handler, which is simple, and which can minimize an index time and make device testing easy without provision of a separate device placing/picking up device.  
           [0010]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description which follows, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
           [0011]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a device test handler embodying the invention includes a loading part movably fitted on a base of the device test handler. The loading part moves trays in forward and backward directions, each of the trays having logic devices to be tested placed therein. Multiple loading shuttles are movably fitted on the base for transferring the logic devices through the test handler. A pre-heating part may be used for pre-heating the logic devices on the shuttles as the shuttles pass therethrough when it is required to test the logic devices at an elevated temperature. The test handler includes a test chamber having one or more test sockets, each of which is configured to receive, hold, and test the logic devices. An indexing device of the test handler is configured for successive transferring of the logic devices from one of the loading shuttles into the test socket, and for transferring the tested logic devices from the test socket to one of the unloading shuttles. A heat supply means of the test handler is used for supplying a high temperature heat to the test socket when the devices must be tested in a hot state. The logic devices are classified according to a result of the test. A transporting device of the test handler is used for transferring the logic devices from trays in the loading part to one of the shuttles, and for transferring the devices from one of the shuttles, after testing, into trays or an unloading part. The logic devices are placed in different trays of the unloading part by the transporting device depending on their classification.  
           [0012]    A device test handler embodying the invention may further includes a buffer part for temporary storage of logic devices determined to be defective before transferring the logic devices to the unloading part.  
           [0013]    The transporting device includes a guide frame fitted to cross over the base of the device test handler. A loading picker is movably fitted at one side of the guide frame and is configured to move along the guide frame. The loading picker is used to transfer logic devices to be tested from input trays in the loading part onto a loading shuttle. A first unloading picker is also movably fitted to the guide frame to move along the guide frame. The first unloading picker transfers the tested logic devices from an unloading shuttle onto respective trays in an unloading part, and onto a buffer part. A second unloading picker is also movably fitted to the guide frame to move along the guide frame. The second unloading picker is used to transfer logic devices from the buffer part to a defective device tray in the unloading part.  
           [0014]    The pre-heating part includes a heating plate for heating the loading shuttles while the loading shuttles are placed and carried thereon. Because the logic devices can be preheated as the shuttles move along the heating plate, there is no need to pick and place the devices into a preheating chamber. Thus, a test handler embodying the invention reduces device picking up and placing times compared to prior art devices, and facilitates room temperature and high temperature testing.  
           [0015]    The unloading part includes a plurality of good device trays for holding logic devices determined by the test to be good devices. The unloading part also includes a plurality of retest device trays for holding logic devices classified for retesting, and a plurality of defective device trays for holding logic devices classified as defective.  
           [0016]    The device test handler further includes a loading shuttle direct transporting device for transporting a loading shuttle directly to the test chamber without forcing the loading shuttle to pass through the pre-heating part. This can occur when the logic devices are to be tested at room temperature. The loading shuttle direct transporting device allows testing to be carried out more efficiently as a moving path of the loading shuttle becomes shorter when the devices are to be at room temperature.  
           [0017]    The device test handler further includes a tray distributing device for distributing empty trays from the loading part to the unloading part after all the logic devices are transferred from the input trays. The tray distributing device simplifies operations and reduces the need for operator action, as empty trays can be re-circulated on the device test handler.  
           [0018]    The indexing device in the testing part includes a pair of opposing frames fitted to crossover the loading shuttle, the test socket and the unloading shuttle. A first index head and a second index head are movably fitted in parallel to the frames for alternately repeating a process of transferring logic devices from a loading shuttle to the test sockets, loading the devices into the sockets, and transferring the devices from the test sockets to an unloading shuttle. A first driving means and second driving means are provided for respectively moving the first index head and the second index head in a rotational manner along the frames. First vertical driving means and second vertical driving means are provided for respectively moving the first index head and the second index head in up and down directions.  
           [0019]    Each of the first driving means and second driving means includes a motor fitted to one side of the frame. A threaded driving rod is rotatably fitted in parallel to the frame and is configured to rotate as the motor is driven. A supporting block thread is coupled to the threaded driving rod for moving along the threaded driving rod as the threaded driving rod rotates. A guide member is coupled to the supporting block in parallel to the threaded driving rod for guiding a movement of the supporting block as the supporting block is moved by the threaded driving rod.  
           [0020]    Each of the first vertical driving means and second vertical driving means includes a vertical motor, and a threaded vertical driving rod coupled to the vertical motor. An elevating member is coupled to the threaded vertical driving rod for moving up and down as the threaded vertical driving rod rotates. A supporting member is coupled to the elevating member, and a front portion the first index head or the second index head is fitted thereto. A guide member is coupled to the supporting member for guiding a vertical movement of the supporting member as the supporting member is moved by the threaded vertical driving rod.  
           [0021]    A method for operating a device test handler embodying the invention includes the steps of: (1) loading a tray having devices to be tested on a loading part; (2) transporting the devices loaded on the loading part, by means of a loading picker, into a loading shuttle; (3) pre-heating the devices on the loading shuttle as the loading shuttle passes through a pre-heating part; (4) transporting the loading shuttle, after it has passed through the pre-heating part, to a test chamber; (5) loading the devices on the loading shuttle in the test chamber into one or more test sockets, by means of the indexing device, testing the logic devices, and unloading the devices from the test sockets to an unloading shuttle; (6) classifying the tested devices on the unloading shuttle according to a result of the testing; (7) transferring the tested devices determined good or to be retested into trays for the good devices or the devices to be retested by means of a first unloading picker; (8) transferring and temporarily storing the devices determined defective on a buffer part, and (9) transferring the devices from the buffer part to the tray for defective devices in the unloading part by means of a second unloading picker.  
           [0022]    If the devices are to be tested at room temperature, a method embodying the invention could eliminate step (3) so that the loading shuttle is transported to the test chamber directly by means of a direct transporting device without passing through the pre-heating part after the devices are loaded on the loading shuttle.  
           [0023]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.  
         [0025]    In the drawings:  
         [0026]    [0026]FIG. 1 illustrates a plan view of a device test handler in accordance with a preferred embodiment of the present invention;  
         [0027]    [0027]FIG. 2 illustrates a perspective view showing main parts of the device test handler in FIG. 1;  
         [0028]    [0028]FIG. 3 illustrates a perspective view of an indexing device of the device test handler with a part omitted; and,  
         [0029]    FIGS.  4 A- 4 D illustrate plan views of the indexing device in FIG. 3 showing a sequence of operation thereof, schematically.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0030]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. FIGS. 1 and 2 illustrate device test handlers in accordance with a preferred embodiment of the present invention.  
         [0031]    Referring to FIGS. 1 and 2, there is a loading part  10  on one side of a front portion of a base  1  of the device test handler. A stack of trays  11 , having devices to be tested placed therein, are placed on the loading part  10 . A stack of trays  21  for holding good devices, classified as a result of testing, are placed on one side of the loading part  10 . A stack of trays  22  for holding devices to be re-tested are placed on the other side of the loading part  10 . There are also a plurality of trays  23  on the other side of the front portion of the base  1  for holding defective devices according to class of defect degrees.  
         [0032]    The trays  21  for holding good devices, the trays  22  for holding devices to be re-tested, and the trays  23  for holding the defective devices comprise an unloading part  20 . The trays in the loading part  10  and the unloading part  20  are movable on the base  1  in front and rear directions, as indicated by the arrows in FIG. 1.  
         [0033]    A plurality of shuttles, each of which is configured to hold a plurality of logic devices, move around the test handler in a loop. The shuttles transport the logic devices into and out of a test chamber  60 . Logic devices to be tested are transferred to a loading shuttle  51  when it is located at a central portion of the base  1 , as shown in FIG. 1. The loading shuttle is divided into a plurality of cells for receiving the devices transported from the input tray  11  in the loading part  10 .  
         [0034]    A guide frame  31  in the middle of the base  1  crosses over the base  1 . A loading picker  32 , a first unloading picker  33 , and a second unloading picker  34  are movably fitted on the frame  31 . The loading picker  32  and the second unloading picker  34  are fitted on the same face of the guide frame  31 . The range of movements the loading picker  32  and the second unloading picker  34  are not overlapped.  
         [0035]    The loading picker  32  transports the devices from the input tray  11  to the loading shuttle  51 . The first and second unloading pickers  33  and  34  transport the devices from a shuttle that has left the test chamber  60  onto respective trays  21 ,  22 , and  23  in the unloading part  20 .  
         [0036]    On the front portion of the base  1  there is a pre-heating part  40  which includes a heating plate  41  for pre-heating the devices on the loading shuttles  51  as the loading shuttles  51  filled with the devices are transported along the pre-heating part  40 . A transfer device  42  is used to move the loading shuttles  51  along the heating plate  41 . Preferably, the heating plate  41  is operative electrically for easy temperature control. The heating plate  41  in the pre-heating part  40  may extend rearward up to a test chamber  60  in which the devices are tested. The loading shuttle  51  passes through the pre-heating part  40  and inside the test chamber  60 .  
         [0037]    When no pre-heating of the devices on the loading shuttles  51  is required, a bypass transfer mechanism  45  can be used to move a loading shuttle directly across the pre-heating part  40  and into a path leading to the test chamber. In this instance, the loading shuttle does not travel along all the path of the pre-heating part  40 , but rather through a shortened bypass path, thus reducing the test time.  
         [0038]    The test chamber  60  is substantially an enclosed space for maintaining an environmental temperature of the devices in a fixed state when the devices are tested. The devices could be tested at a temperature that is elevated or lowered relative to room temperature. In the test chamber  60 , there are test sockets  61 , each of which is configured to hold and test a logic device. There could be one or a plurality of such test sockets  61  on any given machine embodying the invention. Unloading shuttles  55  are located on one side of the test sockets, each for receiving and holding the devices tested at the test sockets  61 . An indexing device is used for successive transferring and loading of devices to be tested from the loading shuttle  51  to the test socket  61 , and for transporting the tested devices from the test socket  61  to the unloading shuttle  55 . A gas supply duct  63  is used for supplying hot or cool gas to the test socket  61  when the devices are tested in a hot or cold state. The shuttles are movable in the test chamber  60  so that after the devices to be tested are emptied from one of the shuttles, the shuttle can move behind the test sockets, and around to the other side of the test socket to an unloading portion so that the shuttle can then act as an unloading shuttle  55 . Once an unloading shuttle  55  has been filled with tested devices, it is moved out of the test chamber  60  to a position of the guide frame  31  in the middle of the base  1 .  
         [0039]    A buffer part  71 , located in front of the test chamber  60 , is used for temporary storage of devices classified as being defective. Defective devices are transported from an unloading shuttle  55  to the buffer part  71  by the first unloading picker  33 . The buffer part  71  can then move forward to a position aligned with the second unloading picker  34 . The second unloading picker  34  can then transfer the defective devices to one of the defective device output trays  23 . If there is more than one classification of defective devices, the separate classifications could be stored in different defective output trays.  
         [0040]    There is a tray transfer device  80  in a rear portion of the base  1  for distributing empty trays  11  from the loading part  10  in either direction so that the empty trays  11  can be used as the trays  21  for loading good devices and the trays  22  for loading the devices to be re-tested.  
         [0041]    The operation of the device test handler in accordance with a preferred embodiment of the present invention will be explained.  
         [0042]    When the device test handler is put into operation after the loading part is stacked with trays  11  that contain devices to be tested, a tray  11  from the loading part  10  is transported toward the rear of the base to a position in front of the guide frame  31  in the middle of the base  1 . The loading picker  32  on the guide frame  31  transfers the devices from the tray  11  to one or more of loading shuttles  51 . Once all the devices have been transferred to loading the shuttle  51 , the tray  11  is transferred to the tray transfer  80  device at a rear portion of the base.  
         [0043]    The loading shuttle  51 , which is now full of the logic devices, is transferred to the heating plate  41  in the pre-heating part  40  or directly over a rear portion of the pre-heating part  40  via the bypass mechanism  45 . The loading shuttle  51  is ultimately transported to the test chamber  60  in the rear portion of the base  1 . Once the loading shuttle  51  is inside the test chamber  60 , the devices in the loading shuttle  51  are loaded into the test sockets  61  continuously by the indexing device in the test chamber  60 . The devices are then tested, and the tested devices are loaded on an unloading shuttle  55  positioned opposite to the loading shuttle  51  by the indexing device. Once an unloading shuttle  55  is fully loaded with tested devices, the unloading shuttle  55  is moved out of the test chamber  60  through a front thereof to beneath the guide frame  31 .  
         [0044]    Then, the first unloading picker  33  on the guide frame  31  transfers the devices from the unloading shuttle  55  to respective trays  21 ,  22 , and  23  according to the classifications assigned to the devices during the testing. The devices determined to be good are loaded on the tray  21  for good devices, and the devices determined to require re-test are loaded on the tray  22  for devices to be re-tested. The devices determined defective are temporarily loaded on the buffer part  71 . The buffer part  71  then moves to an opposite side of the guide frame  31 , so that it is aligned with the second unloading picker  34 . The second unloading picker then transfers the defective devices from the buffer part  71  to the tray  23  for defective devices. Because multiple separate trays for defective devices are available, the defective devices can be classified into different categories. The defective device trays can move backward and forward so that the second unloading picker  34  can load the defective devices into the appropriate defective device tray according to the classification assigned during testing.  
         [0045]    Upon completion of testing of all of the devices in the loading part  10 , testing of the devices in the tray  22  for devices to be re-tested is carried out automatically. The retest tray  22  in the front portion of the base  1  is moved backward up to a position of the tray transfer device  80 , and the tray is shifted to a position aligned with the loading part  10 . The tray is then moved forward to a space under the guide frame  31 , and is advanced step by step as the devices are transferred to loading shuttles  51  by the loading picker  32 . The testing process thereafter is identical to the aforementioned process, and upon completion of unloading and test for all of the devices in the retest tray  22 , the process is completed.  
         [0046]    [0046]FIG. 3 illustrates a perspective view of an indexing device  62  embodying the invention that can be used in the device test handler. The front, right transferring mechanism that is used to move the second index head  604  has been omitted from FIG. 3 for purposes of clarity.  
         [0047]    Referring to FIG. 3, when the loading shuttle  51  enters into the test chamber  60  and is positioned at a test loading position, the loading shuttle  51 , the test socket  61 , and the unloading shuttle  55  are arranged on a line, with the test socket  61  positioned lower than the loading shuttle  51  and the unloading shuttle  55 . The loading shuttle  51  and the unloading shuttle  55  move step by step at fixed intervals as the devices thereon are picked up/placed.  
         [0048]    There are a pair of opposing frames  601  located over the test sockets (note: the second frame for holding and moving the second index head  604  has been omitted from FIG. 3). The frames  601  extend in the same direction (hereafter called as ‘X-axis direction’) in which the loading shuttle  51 , the test socket  61  and the unloading shuttle  55  are aligned. A first index head  602  and a second index head  604  are located between the pair of frames  601 , and the indexing heads are movable in the X and Y axes. The first and second indexing heads repeat a process of: (1) transferring the devices from the loading shuttle  51  to the test sockets  61 ; (2) loading the devices into the test sockets; (3) transferring the devices from the test socket  61  to the unloading shuttle  55 ; and (4) returning back to a position of the loading shuttle  51 . The process is described in greater detail below with reference to FIGS.  4 A- 4 D.  
         [0049]    Each of the first and second index heads  602  and  604  has one or more device holders  603  and  605 . The number of device holders on each index head corresponds to the number of devices that can be simultaneously loaded into the test sockets  61 . The device holders  603  or  605  move up and down in the first or second index head  602  or  604 , and are designed to hold and release the devices.  
         [0050]    There are motors  606  fitted to one side of the frames  601  for driving the first and index heads  602  and  604 , individually. There is a threaded driving rod  607  fitted to each of the motors  606  that extends along the X-axis. The driving rod  607  rotates as the motor  606  rotates. A supporting block  609  is thread coupled with the threaded driving rod  607 , for moving in an X-axis direction as the threaded driving rod  607  rotates.  
         [0051]    There is a supporting plate  610 , having the first or second index heads  602  or  604  fitted thereto, coupled with a front portion of the supporting block  609 . The first or second index heads  602  or  604  are movable in up and down directions along an LM guide  612  located between the support plate  610  and the index head. An LM guide  608  is coupled with the supporting block  609  for guiding movement of the supporting block  609  in the X direction. When the motor  606  is put into operation, to rotate the threaded rod  607 , the supporting block  609  moves along the LM guide  608  in the X-axis direction, together with the supporting plate  610  and the index head.  
         [0052]    A vertical motor  614  is also located on a central portion of each of the frames  601  for controlling vertical movement of the first or second index heads  602  or  604 . A threaded vertical driving rod  615  is connected to the vertical motor  614 . An elevating block  616  is coupled to the vertical driving rod  615  and is movable in up and down directions as the threaded vertical driving rod  615  rotates. An LM guide  617  is used for guiding the up and down movement of the elevating block  616 . A vertical plate  618  extends downward from a front portion of the elevating block  616 , and an elevating bar  619  is fixed to a lower end of the vertical plate  618  in the X-axis direction. The supporting plate  610  is coupled to the elevating bar  619  with a supporting bearing  611  inbetween, such that the supporting plate can move in both the X-axis direction and the vertical direction following movement of the elevating bar  619 . When the vertical motor  614  is put into operation, to rotate the threaded vertical driving rod  615 , the elevating block  616  coupled therewith moves along the LM guide  617  in up and down directions, to move the first or second index head  602  or  604  in up and down directions as the supporting plate  610  moves up and down together with the vertical plate  618  and the elevating bar  619  coupled with the elevating block  616 .  
         [0053]    The operation of the indexing device will be explained with reference to FIGS.  4 A- 4 D.  
         [0054]    Referring to FIG. 4A, at an initial starting of the device test handler, the first index head  602  is positioned at a test loading position over the loading shuttle  51 , and the second index head  604  is positioned at a test unloading position over the unloading shuttle  55 , or vice versa. As the motor  614  is driven, the first index head  602  moves down and the device holder  603  grasps one or more of the devices to be tested on the loading shuttle  51 . Then, as shown in FIG. 4B, the first index head  602  moves up in the Y-axis, then over to the right in the X-axis direction to a space over the test socket  61  as the vertical and horizontal motors are driven. The device holder  603  then moves down as the vertical motor  614  is driven again, and loads the one or more devices into the test sockets  61 , for testing. The second index head  604 , which was initially positioned opposite to the first index head  602 , moves in the X-axis direction toward the loading shuttle  51 , and stops at a test loading position over the loading shuttle  51  as the motor  606  is driven. The second index head  604  then moves down and grasps one or more the devices to be tested, and stands by. The second index head  604  may come to rest at a standby position that is immediately adjacent the test sockets  61 , as illustrated by the dashed lines in FIG. 4C. This will allow the second index head to very quickly move into position over the test sockets as soon as the first index head  602  leaves, to minimize index time.  
         [0055]    As shown in FIG. 4C, after elapse of a preset time period for the testing, the first index head  602  holds the tested devices and moves up, moves to the test unloading position over the unloading shuttle  55 , moves down, and loads the tested devices into the unloading shuttle  55 . As soon as the first index head  602  moves away from the test socket  61  toward the unloading shuttle  55 , the second index head  604  moves toward the test socket  61 , and moves down and loads the devices it is holding into the test sockets  61  for testing. After the first index head  602  drops off the tested devices at the unloading shuttle  55 , it returns to the loading shuttle  51  and repeats the foregoing process. FIG. 4D illustrates the second index head  604  positioned over the test socket  61 , and the first index head  602  returning from a space over the unloading shuttle  55  to a position of the loading shuttle  51 .  
         [0056]    Although the second index head  604  and the first index head  602  cross at a position over the test socket  61 , because one of the index heads is moved down toward the test socket  61 , the index heads do not collide. Using the above process, the first index head  602  and the second index head  604  can load the devices into the test socket  61  continuously, in a manner that minimizes an index time period. During the picking up and placing of the devices by the first and second index heads  602  and  604 , the loading shuttle  51  and the unloading shuttle  55  move back and forth in steps, thereby allowing smooth continuous picking up and placing of the devices from/to the shuttles.  
         [0057]    As has been explained, the device test handler and the method for operating the same of the present invention significantly reduces the picking up and placing time periods to reduce possible damage to the devices during production, and to reduce an index time period, which maximizes testing efficiency.  
         [0058]    The continuous supply of the devices to the test sockets by the two index heads minimizes an index time period, and the one directional transportation of the devices eliminates the need for a separate device picking up and placing device, thereby simplifying the device test handler.  
         [0059]    It will be apparent to those skilled in the art that various modifications and variations can be made in the device test handler and the method for operating the same of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Category: 3