Tray installation rack for test handler

A tray installation rack is used for a test handler to install therein a plurality of trays each of which has a large number of IC devices to be tested. The tray installation rack includes, a main base fixed to the test handler, a slide base slidably mounted on the main base and has a floor for receiving the trays thereon, a pair of tray guide bars perpendicularly mounted on the slide base to meet two adjacent sides of the trays for limiting movements of the trays in two horizontal directions, a pair of tray adjust bars slidably provided on the slide base to press the trays against the pair of guide bars in the two horizontal directions, an elevator provided on the test handler to lift the trays in a vertical direction in the tray installation rack until an uppermost tray exceeds top ends of the tray guide bars, a pair of tray pushers provided at top portions of the tray adjust bars, and tray standard members mounted on the main base at immediately above the top ends of the tray guide bars to restrict movements of the uppermost tray in the two horizontal directions, wherein the uppermost tray is positioned when the uppermost tray is pressed by the tray pushers against the tray standard members.

FIELD OF THE INVENTION 
This invention relates to a tray installation rack to be incorporated in a 
test handler for installing a plurality of trays carrying IC devices to be 
tested, and more particularly, to a tray installation rack on the test 
handler for accurately positioning different sizes of trays having IC 
devices to be tested and assuring an easy and safe work of loading and 
unloading the trays for the test handler. 
BACKGROUND OF THE INVENTION 
In testing IC devices, an automatic test handler is frequently used in 
combination with an IC tester to automatically provides IC devices (DUT) 
to be tested to a test position (test head) of the IC tester. There are 
generally two types of test handlers, a self-drop type handler wherein the 
IC devices to be tested are transferred in a vertical direction with their 
own gravity and a tray type handler wherein IC devices aligned on a tray 
are transferred in a horizontal direction to the test position either 
directly or via a test tray. 
In a typical tray type test handler, IC devices to be tested are aligned on 
a tray which is sometimes called a customer tray provided by manufacturers 
of the IC devices. The size of the tray varies depending on the type of IC 
devices and the manufacture of the IC devices. 
A plurality of such trays are installed in a tray installation rack prior 
to the testing. During the testing, the IC devices on the trays are 
removed from the tray and loaded on a test by a pick and place mechanism 
of the test handler. The test tray is specially made for the test handler 
to carry the IC devices to the test head of the IC tester where the IC 
devices are tested. Alternatively, the IC devices to be tested are 
transferred directly to the test head by the pick and place mechanism of 
the test handler. The IC devices are sorted based on the test result. This 
invention relates to such a tray installation rack to be used in such a 
tray type test handler. 
As noted above, a tray installation rack of a tray type test handler 
involves processes of placing a number of trays containing IC devices to 
be tested in a container like portion of the tray installation rack, 
providing the IC devices automatically to an IC test system by replacing 
the IC devices on the trays to the test trays. During the processes, each 
tray is lifted by an elevator mechanism provided in the tray installation 
rack and the IC devices at the top position of the tray are transferred to 
the test tray by the pick and place mechanism of the test handler. 
Therefore, the tray installation rack is required to have a precise 
positioning ability to accurately shift the trays so that the IC devices 
are transferred to the test tray without an error. Further, the tray 
installation rack is required to safely and efficiently load and unload a 
large number of trays before and after the testing. Since the size of the 
tray varies, the tray installation rack needs to have a mechanism for 
positioning such differently sized trays to accommodate various type of 
trays and IC devices. 
FIGS. 3-5 show a first example of conventional tray installation rack to be 
used in a test handler. This example is a tray installation rack designed 
with the main purpose of precise positioning the trays. 
FIG. 3 is a perspective view and FIG. 4 is a side view of the tray 
installation rack. The tray installation rack of FIGS. 3-5 include a main 
base 80, adjustment bars 25, tray pushers 26, an elevator 35, linear 
guides 45, a gear 75 and a linear head 76. A plurality of trays 90 are 
stacked in a container like portion formed by the main base 80 and the 
adjustment bars 25 as shown in FIGS. 3 and 4. 
Although not shown, a large number of IC devices to be tested are mounted 
on each tray 90. The test handler system picks up these IC devices and 
transfers and places them on the test trays or a test socket of the test 
head. The test trays horizontally move in the test handler to the test 
head of the IC test system whereby electrical testing for the IC devices 
is performed. Numerous trays 90 are piled up and stored in the tray 
installation rack. The trays 90 are lifted to a predetermined position by 
the elevator 35. The associated mechanism of the linear guides 45, the 
gear 75 and the linear head 76 are provided to accurately drive the 
elevator 35 in the vertical direction. 
As noted above, according to the kind of IC devices, there are several 
trays with different sizes. In order to handle various sizes of trays, the 
tray installation rack is provided with a positioning system formed of the 
main base 80, adjustment bars 25 and the tray pushers 26 to determine the 
position of the trays in X and Y directions. It should be noted that 
although the tray installation rack can accommodated difference sizes of 
trays, the same trays are installed in the tray installation rack for each 
test. In other words, differently sized trays are not installed together 
in the tray installation rack. 
The main base 80 is fixedly provided on the test handler to determine the 
positioning reference of the test handler system. As shown in FIG. 3, the 
main base 80 has a floor and X and Y walls. The X and Y walls limit the 
movement of the trays 90 in the X and Y directions. The trays 90 are 
placed at the corner formed by the X and Y walls of the main base 80 to 
determined the position in the X direction and Y direction of the test 
handler. For doing this, the trays 90 are pressed toward the X and Y 
directions by the tray adjust bars 25 and the tray pushers 26. 
In general, the bigger the elevator 35 for lifting the trays 90, the easier 
it becomes to secure the horizontal position of the trays 90. FIG. 5 is a 
plan view of the tray installation rack including the elevator 35 which 
loads the trays 90. The horizontal surface (floor) of the elevator 35 
which lifts the tray 90 is structured to be wide enough to accommodate the 
largest tray except for the portion in which the tray adjust bars 25 move 
back and forth. Hence, it has the surface defined by the pints a, b, c, d, 
e, f, g, h, i, j, k, l, as shown by the hatched lines excluding the area 
defined by the points d, e, f, g and i, j, k, l in which the movement of 
the tray adjust bars 25 is secured. 
The tray adjust bars 25 are arranged so that both bars can move in the X 
and Y directions, respectively, until reaching the minimum tray size. 
Thus, the minimum tray size is determined by the X and Y walls (upper and 
right sides of FIG. 5) and the two surfaces of the tray adjust bars 25 
facing the X and Y walls. The rectangular surface defined by the points a, 
b, c, h of the elevator 35 has the area that can cover the maximum tray 
size. Thus, even if the trays are with different sizes, the trays 90 are 
always maintained horizontally because the elevator 35 floor has a 
sufficient space to receive the trays. 
To provide the trays 90 at a position suitable for picking the IC devices 
to be tested and placing them on the test tray or directly on the test 
head, the tray 90 is lifted or lowered to a desired position by the 
elevator 35 by the following operation. 
The linear head 76 is connected to the elevator floor to drive the elevator 
35 in a vertical direction. The elevator 35 moves in the vertical 
direction by the rotation of the gear 75 which engages with the linear 
head 76. The linear guides 45 are provided to guide the movement of the 
elevator 35 so as to maintain the horizontal plane of the elevator 35 
during the movement. 
The tray pushers 26 are provided at the upper part of the tray adjustment 
bars 25 to press the top tray 90 which is lifted to the predetermined 
height. The precise positioning for the top tray 90 is necessary because 
the IC devices on the top tray 90 have to be unloaded by a pick and place 
mechanism or a robot hand of the test handler. The tray pushers 26 press 
the top tray 90 against the X and Y walls of the main base 80 to 
accurately positioning the tray 90 as shown in FIG. 4. The tray 90 is thus 
fixed to the walls of the main base 80, and thus accurately positioned to 
avoid the error in the operation of picking the IC devices by the handler 
system. 
To improve a test efficiency, a large number of trays 90 are installed in 
the tray rack to test a large number of IC devices by the test handler. 
Loading and unloading the trays 90 in the tray rack are usually performed 
by a manual labor before and after the test. 
In the foregoing example, the tray 90 is fixed to the position in the main 
base 80 of the handler fairly accurately since the position of the tray 90 
is determined by the walls of the main base 80 when pressed by the tray 
pusher 26. Namely, since the main base 80 is integrally or fixedly provide 
on the test handler, the relative positioning between the test handler and 
the trays 90 are achieved with high accuracy by the arrangement of FIGS. 
3-5. 
However, the loading and unloading of the trays 90 to and from the tray 
installation rack is proceeded by human workers. Further, since moving 
parts of the handler, such as the pick and place mechanism, are provided 
at the upper position of the tray installation rack, an enough space for 
loading and unloading the large number of trays by the human workers is 
not available. 
FIGS. 6 and 7 show a second example of a conventional tray installation 
rack. This tray installation rack is primarily designed to ease the 
loading and unloading works of the trays by providing a mechanism for 
moving the tray installation rack in a horizontal direction on the test 
handler. 
FIG. 6 is a perspective view while FIG. 7 is a side view of the tray 
installation rack. Tray installment rack of FIGS. 6 and 7 includes a slide 
base 5 having slide packs 6, and tray guide bars 15 for positioning the 
trays 90. As in the example of FIGS. 3-5, the tray rack further includes 
the adjustment bars 25 and the tray pushers 26. The slide base 5 is 
mounted on tray rack guide rails 8 provided on the test handler. The slide 
base 5 serves as a floor for stacking the trays 90 as well as to form a 
sliding mechanism for horizontally slide on the test handler along the 
tray rack guide rails 8. A plurality of trays 90 are piled up on the floor 
of the slide base 5. To accommodate the difference of size, the trays 90 
are pressed by the adjustment bars 25 toward the tray guides 15 which form 
walls to limit the movement of the trays 90 in the X and Y directions. 
Similar to the example of FIGS. 3-5, the elevator 35, the linear guides 45, 
the gear 75 and the linear head 76 are also provided. The trays 90 are 
lifted to a predetermined position by the elevator 35 so that the tray 90 
at the top position is accessed by a pick and place mechanism or a robot 
hand to replace the IC devices to the test handler as mentioned above. The 
elevator 35 includes the linear guides 45, the gear 75 and the linear head 
76 to accurately drive the elevator 35 in the up and down direction. The 
elevator 35, the linear guides 45, the gear 75, the linear head 76, and 
the tray rack guide rails 8 are fixedly provided on the main base 80. 
The example of FIGS. 6 and 7 is provided with the slide pack 6 for pulling 
out and pushing in the slide base 5 on the test handler to allow a 
horizontal movement of the tray rack on the handler. Namely, the slide 
base 5 is guided by the tray rack guide rails 8 via the slide pack 6 in 
the direction shown by the arrow on the test handler. The slide pack 6 is 
provided to allow a smooth movement of the slide base 5 along the tray 
rack guide rails 8. 
Thus, the trays 90 can be replaced when the tray installation rack is 
pulled out from the position where the elevator is provided. Although not 
shown, the test handler has, on the upper part of the elevator and the 
tray installation rack, a mechanism for removing the IC devices from the 
tray, such as the pick and place mechanism. By shifting the horizontal 
position of the tray installation rack from the pick and place, a larger 
space at the top of the tray installation rack is available which makes 
the tray replacement easy and smooth. Further, since the moving mechanism 
or components do not exist around the tray installation rack at this 
position, the tray replacement work is undertaken safely. 
The situation where the uppermost tray 90 is vertically lifted to the 
predetermined position for removing the IC devices to be tested is shown 
in FIG. 7. The tray guide bars 15 and the tray adjust bars 25 are provided 
on the slide base 5 to serve as determining the position of the uppermost 
tray 90. The tray pushers 26 further serve to secure the precise position 
of the tray 90 by pressing the tray against the tray guide bars 15. 
However, in this example, since the positioning of the tray 90 is made with 
respect to the tray guide bars 15 which are not directly attached to the 
test handler, such positioning is not necessarily accurate with respect to 
the test handler, especially with respect to the pick and place mechanism 
of the test handler. Moreover, because the slide pack 6 is to allow a 
slidable movement to the tray installation rack, there required subtle 
gaps between the test handler, i.e., the tray rack guide rails 8 and the 
slide base 5. Thus, the precise positioning is difficult to attain with 
respect to the handler, and an error X such as shown in FIG. 7 is 
unavoidable in the positioning of the tray 90 with respect to the main 
base 80 or the pick and place mechanism of the test handler. 
As note above, in the example of FIGS. 6 and 7, since the positioning 
standard for the slide base is not directly provided to the test handler, 
it is not possible to precisely and accurately position the tray 
installation rack and thus the trays 90 with respect to the test handler. 
To realize the precise positioning of the tray installation rack, an 
expensive linear motion guide, for example, has to be used instead of the 
slide pack of FIGS. 6 and 7 for interfacing the slide base 5 and the test 
handler. 
SUMMARY OF THE INVENTION 
It is therefore, an object of the present invention to provide a tray 
installation rack which is capable of precisely and accurately positioning 
a tray at the top of the tray installation rack with respect to a test 
handler. 
It is another object of the present invention to provide a tray 
installation rack which is capable of easily and safely loading and 
unloading the trays before and after the test of the IC devices. 
It is a further object of the present invention to provide a tray 
installation rack which is capable of precisely and accurately positioning 
a tray at the top of the tray installation rack with respect to a test 
handler without incorporating an expensive mechanism. 
It is a further object of the present invention to provide a tray 
installation rack which is capable of sliding on the test handler for 
loading and unloading a large number of trays and accurately positioning 
the trays with respect to the test handler. 
In order to accomplish the task, the length of the tray guide bars in the 
present invention are shortened with respect to the length of the tray 
adjust bars compared with the conventional example of FIGS. 6 and 7. Over 
the top of the tray guide bars, tray standard bars are arranged on a main 
base of the test handler system. 
When the tray is lifted to the uppermost level of the tray installation 
rack by an elevator, the uppermost tray that has been positioned by the 
tray guide bar, is then positioned by the tray standard bars. A tray 
pusher is installed on each tray adjust bar in the X and Y directions at 
the level corresponding to the height of the tray standard bar. The 
uppermost tray is pressed against the tray standard bar by the tray 
pusher. 
As result of which, the uppermost tray is precisely positioned with respect 
to the test handler because the tray standard bars are fixed to the main 
base of the test handler. The tray installation rack can be pulled out 
together with the tray, and the trays can be replaced when the tray 
installation rack is pulled out and thus an enough space is available 
around the tray installation rack. 
The tray installation rack of the present invention is used for a test 
handler to install therein a plurality of trays each of which has a large 
number of IC devices to be tested. The tray installation rack includes: a 
main base fixed to the test handler; a slide base slidably mounted on the 
main base and has a floor for receiving the trays thereon; a pair of tray 
guide bars perpendicularly mounted on the slide base to meet two adjacent 
sides of each of the trays for limiting movements of the trays in two 
horizontal directions; a pair of tray adjust bars slidably provided on the 
slide base to press the trays against the pair of guide bars in the two 
horizontal directions; an elevator provided on the test handler to lift 
the trays in a vertical direction in the tray installation rack until an 
uppermost tray exceeds top ends of the tray guide bars; a pair of tray 
pushers provided at top portions of the tray adjust bars; and tray 
standard members mounted on the main base at immediately above the top 
ends of the tray guide bars to restrict movements of the uppermost tray in 
the two horizontal directions; wherein the uppermost tray is positioned 
when the uppermost tray is pressed by the tray pushers against the tray 
standard members. 
According to the present invention, the tray standard members (bars) are 
provided in the X and Y directions of the main base of the handler system 
which has a pick and place mechanism for removing the ID devices from the 
tray and placing the IC devices on the test tray. When the tray is lifted 
by the elevator to the level where the tray standard bars are provided, 
the positioning function is transferred to the tray standard bars. Thus, 
horizontal level of the tray is maintained by the elevator while the 
positioning in the X and Y directions are precisely determined by the tray 
standard bars when the tray is pressed by the tray pushers against the 
tray standard bars. 
Accordingly, problems involved in the conventional tray installation rack 
are eliminated. For example, there was a problem in which the IC devices 
on the tray are not in the accurate positions such that a suction inlet of 
the pick and place mechanism cannot properly attract the IC devices. In 
the other problem, the pick and place mechanism cannot accurately place 
the IC devices that have been tested on the tray based on the test 
results. These problems are solved in the present invention. 
The tray installation of the present invention can be slidably movable 
together with the trays 90 on the test handler. Hence, the trays can be 
easily replaced when the tray installation rack is separated from the 
elevator and pick and place mechanisms. Since the tray replacement, i.e., 
the loading and unloading, is taken place where an enough space is secured 
around the tray installation rack and no moving mechanism exist proximate 
to the tray rack, the exchange of the trays can be safely and efficiently 
performed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred embodiment of the present invention will be explained with 
reference to the drawings. FIG. 1 and 2 explains the tray installment rack 
of the present invention to be used for the test handler system. FIG. 1 is 
a perspective view showing an embodiment of the tray installation rack for 
the test handler system of the present invention. FIG. 2 is a side view 
showing the tray installation rack of the present invention of FIG. 1. For 
convenience and ease of description, the reference numerals used in FIGS. 
1 and 2 correspond to the similar portions of the conventional tray rack 
of FIGS. 6 and 7. 
As shown in FIG. 1, the tray guide bars 15 for positioning the tray are 
arranged in the X and Y directions while crossing together at 90 degrees 
on the slide base 5. The slide base 5 serves as a floor on which a 
plurality of trays 90 are stacked before and after the testing as shown in 
FIG. 2. The slide base 5 has a large opening for the elevator 35 moving in 
the vertical direction to place the top tray 90 at the position for 
removing the IC devices therefrom. The tray adjust bars 25 fix the trays 
90 by pushing them against the tray guide bars 15 in the X and Y 
directions, which accommodate trays 90 of different sizes. Thus, 
positioning for the tray guide bar 15 on the tray slide base 5 is 
performed. 
At the slide base 5, the slide pack 6 which works as promoting the movement 
of the slide base 5 along the tray rack guide rails 8. Thus, the slide 
base 5 can be horizontally pulled out to the front of the test handler 
where the trays 90 can be loaded on or unloaded from the tray installation 
rack. 
Similar to the description made with reference to FIG. 5, the horizontal 
surface of the elevator 35 which lifts the trays 90 is widely formed to 
receive the largest size trays 90 except for the area wherein the try 
adjust bars 25 move toward the X and Y directions. Namely, as shown in 
FIGS. 1 and 5, the elevator 35 has a surface area defined by a, b, c, d, 
e, f, g, h, i, j, k, l in which areas defined by d-e-f-g and i-j-k-l are 
excluded for allowing the movement of the tray adjust bars 25. Hence the 
trays 90 can be aligned with reference to the tray guide bars 15 
regardless of their size when pressed against the tray guide bars 15 while 
the trays 90 can be vertically moved by the elevator 35. 
In the present invention, for accurately positioning the tray 90 at the top 
of the tray installation rack for picking the IC devices, the tray 
standard bars 50-53 are provided in the X and Y directions on the main 
base 80 of the test handler system. The tray standard bars 50-53 
ultimately determine the position of the top tray 90 when the tray 90 is 
pressed against the standard bars 50-53 by the tray pushers 26 provided at 
the top portion of the tray adjust bars. 
As explained above, the trays 90 are first positioned by the tray guide 
bars 15 when pressed thereto by the tray adjust bars 25. Then, the trays 
are lifted by the elevator 35 until the uppermost tray 90 comes to the 
predetermined level of the tray installation rack. As shown in FIG. 2, the 
length of the tray guide bars 15 are shorter compared with the tray adjust 
bars 25. Immediately above the top of the tray guide bars 15, the tray 
standard bars 50-53 are arranged in the X and Y directions. The tray 
standard bars 50-53 are provided on the main base 80 rather than the slide 
base 5 as shown in FIGS. 6 and 7. 
Thus, when the top trays 90 are lifted by the elevator 35 and the top tray 
90 reaches the predetermined upper level, the tray 90 which has been 
positioned by the tray guide bars 15 is transferred to the positioning by 
the tray standard bars 50-53. To meet the height of the tray standard bars 
50-53, the tray pushers 26 are attached to the tray adjust bars 25 which 
are movable in the X and Y directions. Thus, the uppermost tray 90 is 
pressed against the tray standard bars 50-53 by the tray pushers 26. As a 
result, the tray 90 is precisely positioned with respect to the test 
handler because the tray standard bars 50-53 are integrally or fixedly 
provided on the main base 80 of the test handler as noted above. 
In this arrangement, the tray guide bars 15 only function to position the 
tray 90 to a certain degree before the tray 90 is ultimately positioned by 
the tray standard bars 50-53. Hence, the precise alignment of the tray 
guide bars 15 or the slide base 5 is unnecessary, which does not require 
to employ an expensive mechanism such as a linear motion guide. 
The above tray standard bars 50-53 only need to secure the positioning the 
trays with respect to the main base 80 of the test handler. Although four 
tray standard bars are shown in the example of FIG. 1, only one tray 
standard bar can be utilized for each of the X and Y directions facing the 
tray adjust bar. Alternatively, three or more standard bars can be used 
for each of the X and Y directions. The tray pushers 26 are provide with a 
drive mechanism (not shown) such as an air cylinder to give a pressure to 
the tray 90. The tray pushers 26 are preferably made of an elastic 
material to flexibly press the tray 90. 
As in the foregoing, according to the present invention, the tray standard 
bars are provided in the X and Y directions of the main base of the 
handler system which has the pick and place mechanism for removing the IC 
devices from the tray and placing the IC devices on the test tray. When 
the tray is lifted by the elevator to the level where the tray standard 
bars are provided, the positioning function is transferred to the tray 
standard bars. Thus, horizontal level of the tray is maintained by the 
elevator while the positioning in the X and Y directions are precisely 
determined by the tray standard bars when the tray is pressed by the tray 
pushers against the tray standard bars. 
Accordingly, problems involved in the conventional tray installation rack 
are eliminated. For example, there was a problem in which the IC devices 
on the tray are not in the accurate positions such that a suction inlet of 
the pick and place mechanism cannot properly attract the IC devices. In 
the other problem, the pick and place mechanism cannot accurately place 
the IC devices that have been tested on the tray based on the test 
results. These problems are solved in the present invention as in the 
foregoing. 
The tray installation of the present invention can be slidably movable 
together with the trays 90 on the test handler. Hence, the trays can be 
easily replaced when the tray installation rack is away from the elevator 
and pick and place mechanisms. Since the tray replacement, i.e., the 
loading and unloading, is taken place where the enough space is secured 
around the tray installation rack and no moving mechanism exist proximate 
to the tray rack, the exchange of the trays can be safely and efficiently 
performed.