Handling device

The handling device is particularly suited for handling the test heads on a wafer tester. The test head is thereby supported on a mount which is rotatable about its longitudinal axis on a supporting part. A frame column supports the supporting part adjustably in a vertical direction relative to the frame column via at least one linear bearing. A weight balancing device balances the weight of the head and the mount. The supporting part is configured such that the mount is laterally displayed relative to the frame column.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a handling device, in particular to a 
device for handling the test heads of a wafer tester, including a mount 
for the test head disposed rotatably about its longitudinal axis on a 
supporting part, a frame column on which the supporting part is vertically 
adjustable relative to the frame column via at least one linear bearing 
and a weight balancing device for balancing the weight of the test head 
and the mount. 
2. Description of the Related Art 
A test head handling device of the above type is disclosed in applicant's 
German patent publication DE 195 17 330. That handling device comprises a 
mount for the test head which is vertically and horizontally adjustable 
relative to at least one vertical member. The mount is adjustably guided 
horizontally on a supporting part. The supporting part in turn is 
vertically guided adjustably on the at least one vertical member. 
Furthermore that handling device is provided with a weight balancing 
device for balancing the weight of the test head of the mount and of the 
supporting part. The weight balancing device includes balance weights and 
ribbed belts and guide pulleys connecting the weights to the supporting 
part. 
High dimensional accuracy and good accessibility for adjusting the test 
head are required when the handling device is employed in known wafer 
testers. Since such wafer testers are put to use in a clean room 
environment they should have a minimum space requirement. Furthermore, 
good accessibility to the wafer tester is desirable, especially when to 
system is to be serviced. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a handling device, 
which overcomes the disadvantages of the prior art devices and methods of 
this general type and which allows the test head to be adjusted relative 
to a wafer tester with high dimensional accuracy and smooth operation and 
which handling device has a minimum space requirement yet provides for 
good accessibility to the wafer tester. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, a handling device, comprising: 
a frame column; 
at least one linear bearing on said frame column; 
a supporting part connected to said at least one linear bearing and being 
vertically adjustable along said frame column; 
a mount rotatably supported about a longitudinal axis thereof on said 
supporting part; and 
a weight balancing device for balancing a weight of a test head supported 
on said mount; 
said supporting part being formed such that said mount is disposed 
laterally offset relative to said frame column. 
In other words, the object of the invention is satisfied by a handling 
device of the above-mentioned kind in which the supporting part is such 
that the mount is laterally displaced relative to the frame column. 
The advantages obtained by the invention are that the handling device is 
compact and space-saving, and it ensures that the wafer tester, for 
example, is very accessible for maintenance work and the like. Disposing 
the mount laterally enables the cable loom leaving the test head to be 
guided alongside the frame column. Accordingly, the cable loom no longer 
needs to be guided through the supporting structure of the frame column. 
This feature thus results in a simplification in the design of the 
handling device and thus in cost savings. The test head can thus be moved 
in a vertical plane arrangement laterally displaced relative to the frame 
column. In addition, the extent of the handling device horizontally is 
reduced, as a result of which the handling device is more compact and 
space-saving. Furthermore, due to the lateral guidance of the mount on the 
frame column superior stability of the handling device in accordance with 
the invention is achieved since the main weight of the mount and that of 
the test head is located in the immediate surroundings of the frame 
column. 
In accordance with an additional feature of the invention, the supporting 
part includes a jib portion protruding laterally from the frame column. 
The mount is disposed on the jib portion. 
In accordance with an added feature of the invention, the supporting part 
is guided by two linear bearings spaced away from each other on the frame 
column, the linear bearing rails and the slide guides being arranged 
alternatingly. Accordingly, in the case of the first linear bearing, for 
example the linear bearing rail, is arranged on the supporting part and 
the associated slide guide on the frame column whilst in the case of the 
second linear bearing an inverse arrangement is provided. This alternating 
arrangement enhances guidance stability. Advantageously the linear guide 
located nearer to the mount is longer since this substantially handles the 
resulting torques. In that case it is also expedient to arrange the linear 
guide rail on the supporting part while the slide guides are defined on 
the frame column. Due to the arrangement in accordance with the invention 
it is achieved that the mount and thus the test head too, can be elevated 
beyond the free end of the frame column. This has the advantage that the 
overall height of the handling device and more particularly that of the 
frame column can be reduced. Furthermore, this configuration of the linear 
bearings ensures that the test head is still guided dimensionally true on 
the frame column even in such an elevated condition of the mount. Being 
able to elevate the test head beyond the free end of the frame column is 
of advantage, for example, to servicing since all components of the frame 
column, test head or mount are freely accessible on all sides. In 
addition, the wafer tester is accessible on all sides in this position. 
In accordance with another feature of the invention, the supporting part 
comprises a base portion guided by the frame column, the jib portion 
jutting from the base portion at an angle of preferably 90.degree.. 
In accordance with a further feature of the invention, the supporting part 
comprises a base portion guided by the frame column, the base portion 
being connected to the jib portion by a crank. 
In accordance with again an additional feature of the invention, the 
supporting part comprises two mutually spaced apart vertical members, 
which differ in length. 
In accordance with again an added feature of the invention, the supporting 
part may comprise at least one, preferably two horizontal members 
connected to the vertical members. Advantageously the supporting part may 
comprise two cross members spaced apart from each other connected to the 
horizontal members as well as to at least one of the vertical members. 
In accordance with again another feature of the invention, there is 
provided at least one positioning element for locking the system in a 
defined position along the vertical movement direction. In this 
configuration the positioning element may be a manually actuated latch 
pin. 
In accordance with again a further feature of the invention, the cable loom 
of the test head may be accommodated by a supporting ring swivably 
supported relative to the supporting part to minimize the mechanical load 
of the cable loom. 
Expediently the cable loom may be supported between the supporting ring and 
the test head by further supporting means. Advantageously the cable loom 
is guided in the region of the test head by a mounting ring firmly 
clamping the cable loom in place. Furthermore, an intermediate support for 
the cable loom may be provided between the mounting ring and the 
supporting ring. 
In yet another advantageous aspect the mount may be carried by a rotary 
bearing on the supporting part, the cable loom of the test head being 
guided through the inner opening of the supporting part. For this purpose 
the supporting part may comprise expediently a supporting plate arranged 
on the cross members and connected to the rotary bearing. In an 
advantageous aspect the supporting plate comprises an inner opening 
through which the cable loom is guided. Furthermore, the supporting plate 
may be carried swivably on the at least one cross member. Where two cross 
members are provided the supporting plate is swivelably carried by the 
upper cross member. In accordance with another aspect of the invention, 
the supporting plate may be a ring plate. 
In accordance with yet an additional feature of the invention, the 
supporting plate is carried swivelably on the upper cross member via the 
rotary bearing. Advantageously the rotary bearing comprises a trunnion and 
a counterbearing, the trunnion being arranged on the supporting plate and 
the counter-bearing being disposed on the cross member. 
Expediently to lock the supporting plate in the swiveling direction at 
least one locking element is provided. This locking element may consist of 
a manually actuatable positioning spindle. 
In accordance with yet another feature of the invention, the horizontal 
members, the vertical members, and the cross members are made of metal. 
This ensures a cost-effective, simple means of manufacturing the 
individual supporting part components. The individual member elements are 
preferably welded to each other. 
In accordance with yet again another feature of the invention, the mount is 
formed of two forks connected to each other by an end plate. 
The two forks may thereby be formed with slots into which guide pins on the 
test head may engage. Expediently the guide pins may be provided with 
clamping means for locking the longitudinal position of the test head. 
This configuration of the forks in accordance with the invention enables 
the test head to be longitudinally adjustable within the mount. 
In accordance with yet again an additional feature of the invention, the 
forks are provided with at least one mechanical connector for locking the 
test head to the wafer tester, the connecting means bringing and locking 
the test head and the wafer tester together. 
Advantageously the weight balancing device is arranged within the frame 
column, as a result of which the space requirement of the handling device 
is further reduced. 
In accordance with another feature of the invention, the weight balancing 
device comprises one or more balancing weights which are connected via at 
least one ribbed belt over a pulley to the supporting part. In accordance 
with a preferred feature of the invention, two ribbed belts are provided 
guided parallel to each other about a respective guide pulley. 
Due to the weight balancing device as provided in accordance with the 
invention the weight on the adjustably arranged parts of the handling 
device is relieved, as a result of which controlling the test head 
relative to the wafer tester is assured dimensionally accurately. Due to 
the weight balancing device the full weight of the adjustable parts need 
not be moved in making the adjustment, so that the handling device is 
highly safe in operation. At the same time due to the special 
configuration of the weight balancing device within the frame column of 
the handling device a large weight may be used for a low overall height 
and minimum space requirement. The balance weights are preferably 
plate-shaped. Expediently the plate-shaped balance weights are arranged 
releasably in the weight balancing device. In this way the quantity of the 
weights needed can be set individually for each application. 
In accordance with a further feature of the invention, the frame column 
comprises a base plate on which at least one jib is arranged, and the jib 
has at least one jib foot. 
Using jibs makes for a simple as well as highly stable supporting structure 
for the handling device in accordance with the invention. Furthermore, due 
to the use of jibs, which are advantageously telescopic, a stable 
supporting system is created on all sides. The jibs are advantageously 
configured rod-like so that they take up little space in the floor region 
of the clean room in which the handling device is employed. 
A particularly simple and safe means of adjusting the test head is achieved 
by assigning the supporting part or the weight balancing device a 
positioning drive. By way of example, the drive may be an electric or 
pneumatic drive. A separate drive may be provided for both the vertical 
movement of the supporting part and for the horizontal movement of the 
test head in the longitudinal direction thereof as well as for the 
swiveling movement of the mount. 
In accordance with a concomitant feature of the invention, the drive is an 
electric drive cooperating with the guide pulley for the ribbed belts. 
Advantageously the electric drive is assigned an incremental control 
permitting dimensionally accurate adjustment of the test head. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
handling device, it is nevertheless not intended to be limited to the 
details shown, since various modifications and structural changes may be 
made therein without departing from the spirit of the invention and within 
the scope and range of equivalents of the claims. 
The construction and method of operation of the invention, however, 
together with additional objects and advantages thereof will be best 
understood from the following description of specific embodiments when 
read in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures of the drawing in detail and first, 
particularly, to FIGS. 1 and 2 thereof, there is seen a handling device 10 
with a mount 20 in which a test head or test head 11 is inserted. Such a 
handling device 10 finds application in a wafer tester, which is not 
illustrated herein for purposes of clarity. The handling device 10 is 
disposed relative to the wafer tester so that the test head 11 can be 
assigned to the wafer tester by means of the handling device 10. 
The test head 11 is held by the mount 20. The mount 20 comprises side forks 
21, 22 connected to each other via an end plate 23. The test head 11 is 
slidingly held in the longitudinal direction L by the horizontally 
oriented forks 21, 22. Slots 24 are formed in the forks 21, 22 which 
define the shiftability in the longitudinal direction L. A corresponding 
guide pin 25 of the test head 11 engages in the slots 24. The guide pin 25 
can be assigned a clamping means for locating the test head 11. The forks 
21, 22 comprise further mechanical connecting means 27 via which the test 
head and the wafer tester can be interlocked. The end plate 23 is formed 
with an opening through which a cable loom 12 connected to the test head 
11 can be guided. 
The mount 20 for the test head 11 is rotatably mounted about the 
longitudinal axis 28 by means of a rotary bearing 26. The rotary position 
of the mount 20 can be set by means of a non-illustrated latch pin. The 
rotary bearing 26 is ring-shaped and it comprises an inner opening through 
which the cable loom 12 of the test head 11 is guided. The cable loom 12 
is accommodated by a supporting ring 75 which is swivelable on a 
supporting arm 76 connected to a supporting part 70 for the mount 20. As a 
result, a decoupling of the cable loom is achieved. For further decoupling 
the cable loom 12 further supporting elements may be provided between the 
supporting ring 75 and the mount 20. 
The mount 20 is carried by the supporting part 70 comprising a base portion 
73 and a jib portion 74 protruding vertically therefrom. 
With specific reference to FIG. 2, the base portion 73 comprises two 
vertical members 71, 72 mounted via linear bearings 60a, 60b on a frame 
column 40 of the handling device 10. In this arrangement the vertical 
member 71 facing the mount 20 is longer that the vertical member 72 spaced 
away therefrom in parallel. In this exemplary embodiment the vertical 
member 71 has the same length as the frame column 40. 
Each of the linear bearings 60a, 60b consists of a linear bearing rail 62a, 
62b and an assigned slide guide 61a, 61b. The linear bearing rails 62a, 
62b and the slide guides 61a, 61b are coupled such that the vertical 
members 71, 72 can move in the vertical direction H relative to the frame 
column 40 along the side cover panel 42. The linear bearings 60a, 60b 
thereby permit dimensionally accurate, smooth shifting of the vertical 
members 71, 72. To enhance the stability the linear bearing rails 62a, 62b 
and the assigned slide guides 61a, 61b are arranged alternatingly on the 
two linear bearings 60a, 60b. 
The base portion 73 includes two mutually parallel horizontal members 73a, 
73b bridging the vertical members 71, 72. In the connecting portion of the 
horizontal members 73a, 73b with the longer vertical member 71 two cross 
members 74a, 74b are provided spaced away from each other via which the 
mount 20 is connected to the supporting part 70. In the exemplary 
embodiment, the cross members 74a, 74b are perpendicular relative to the 
horizontal members 73a, 73b. 
The position of the supporting part 70 in the vertical direction H can be 
defined via positioning elements 77. In the exemplary embodiment there are 
provided two positioning elements 77 which are configured as manually 
actuatable latch pins. 
The individual component parts of the supporting part 70 are made of metal 
and are welded together to the supporting part 70 in a welding process. 
The connection of the mount 20 to the supporting part 70 is achieved by a 
supporting plate 78. The supporting plate 78 comprises in turn an inner 
opening through which the cable loom 12 of the test head 11 is guided. 
The supporting plate 78 is swivelable on the supporting part 70 via a 
rotary bearing 79 so that the mount 20 is able to implement a movement in 
the swiveling direction S. With reference to FIG. 3, the mount 20 is 
locked at the supporting part 70 via the rotary bearing 79 such that at 
each upper cross member 74a trunnions 82 are provided. The trunnions 82 
cooperate with counterbearings 80 configured on the supporting plate 78. 
In this way a swivel movement in the direction of the arrow S about the 
upper cross member 74a is made possible. To define the swivel position of 
the test head 11 held in the mount 20 positioning elements 81 are provided 
to adjust the parallel position of the test head 11 relative to the wafer 
tester. 
Again with reference to FIG. 1 the mount 20 is arranged on one side of the 
frame column 40. In this way the cable loom 12 of the test head 11 is 
guided on one side of the frame column 40. 
A weight balancing device 45 is disposed in the frame column 40. The weight 
balancing device 45 serves to balance the weight of the test head 11, 
mount 20 and supporting part 70. With reference to FIG. 3, the weight 
balancing device 45 comprises balancing weights 48. A plurality of 
balancing weights 48 are stacked in the weight balancing device 45. Ribbed 
belts 46 are arranged on the upper side of the weight balancing device 45. 
The ribbed belts 46 are connected via guide pulleys 47 to the supporting 
part 70. As shown in FIG. 2 the ribbed belts 46 are each arranged in pairs 
in the side portions of the weight balancing device 45. This is the reason 
that paired guide pulleys 47 are available for the ribbed belts. 
The frame column 40 comprises in the base portion a base plate 41 on which 
the jibs 43 are arranged. The jibs 43 comprise in turn in their end 
portions jib feet 44. It is achieved by the arrangement of the jibs 43 and 
jib feet 44, that the handling device 10 is very stable and stands safely. 
At the same time the space taken up by the jibs 43 can be pared to a 
minimum and, accordingly, the handling device 10 can be installed with 
substantial space-savings in a clean room. The jibs 43 are telescopically 
shiftable so that the support of the handling device 10 can be 
individually adjusted in accordance with the space available in the room 
and the weight. 
With reference to FIGS. 3 and 4, the supporting part 70 can be moved via 
the vertical members 71, 72 as well as the linear bearings 60a, 60b in the 
vertical direction relative to the frame column 40 such that the mount 20 
and thus also the test head 11 can be run up beyond the free end of the 
frame column 40. As a result, the height of the frame column can be 
maintained relatively low for high stiffness. Due to the rail-type 
configuration of the linear bearings 60a, 60b proper functioning of the 
supporting part 70 is assured even in the elevated position of the 
supporting part 70. 
Due to the configuration of the handling device 10 the test head 11 can be 
moved in both the vertical direction H as well as in the longitudinal 
direction L along the longitudinal axis 28 and also in the swiveling 
direction S. The movement of the test head 11 in the individual directions 
can be achieved via a common drive or preferably via separate drives. For 
this purpose the guide pulleys 47 may be assigned a non-illustrated 
electric drive for example. The electric drive is controlled by an 
incremental control so that the test head 11 can be precisely moved. As an 
alternative a non-illustrated air cylinder may be attached articulatedly 
to the lower cross member 74b. 
The operation of the handling device 10 is as follows: 
As noted above, the handling device 10 finds its primary application on a 
wafer tester. The handling device 10 is thereby located directly alongside 
the wafer tester so that the test head 11 is oriented above the wafer 
tester. The test head 11 is disposed at the mount 20 of the handling 
device 10. The test head 11 can be moved both in the vertical direction H 
relative to the frame column 40 and in the longitudinal direction L 
relative to the longitudinal axis 28. In addition, the test head 11 is 
rotatably mounted about the longitudinal axis 28 by the rotary bearing 26. 
Furthermore, the test head 11 is rotatably mounted about its transverse 
axis by means of the rotary bearing 79 in the swiveling direction S. The 
precise position of the test head 11 can be defined by the positioning 
elements 77 in the vertical direction H, by the positioning elements 81 in 
the swiveling direction S, and by the clamping elements cooperating with 
the guide pin 25 in the longitudinal direction L. 
Due to the weight balancing device 45 it is possible with the balancing 
weights 48 to balance the test head 11, the mount 20, and the supporting 
part 70. This is achieved by inserting the balancing weights 48 in the 
weight balancing device 45, thus balancing the supporting part 70 and the 
parts connected thereto. As a result, only minor forces are needed for 
adjustment. Furthermore, the configuration is favorable from a technical 
safety viewpoint, since only very small forces are required to make the 
adjustment. 
The supporting part 70 is adjusted via a non-illustrated electric drive. 
When the electric drive is combined with a digitizer, highly accurate 
movement of the test head 11 is enabled. 
The supporting part 70 is vertically shifted in the direction H by shifting 
the weight balancing device 45 within the frame column 40. The supporting 
part 70 is thereby guided via the linear bearing rail 62a, 62b of the 
linear bearings 60a, 60b at the assigned slide guide 61a, 61b which are 
arranged on the side cover panel 42 of the frame column 40. 
The rotary movement of the mount 20 about its longitudinal axis 28 is made 
possible by the rotary bearing 26. In rotation of the mount 20 the cable 
loom 19 of the test head 11 is decoupled by the supporting ring 75. 
The above-described configuration with the weight balancing device permits 
precise travel of the test head 11 with high reliability. In addition, the 
handling device 10 takes up very little space which is of advantage for 
operation in a clean room area. Furthermore, due to the lateral 
arrangement of the supporting part 70 on the frame column 40 and the 
generous travel in the vertical direction the test head and the wafer 
tester are freely accessible on all sides, i.e. also from the rear. This 
freedom of access has the advantage that servicing as well as repair or 
maintenance work are facilitated. Due to the design configuration of the 
handling device 10 it is furthermore assured that the handling device 10 
features high stability since the individual components are arranged 
closely surrounding the frame column 40. Long cantilever components 
necessitating a particularly complicated support can thus be avoided in 
the handling device 10 in accordance with the invention.