Abstract:
A compliance module, particularly for a manipulator for positioning a test head, comprising a housing that is securable to a component. The compliance module furthermore comprises an inner sleeve shiftingly mounted in said housing and axially urged by a spring element, and a pin arranged on said housing and connected to said inner sleeve. A compliance module of such kind provides a precise location on the one hand and a certain compliance achievable of a portion of the manipulator for positioning a test head on the other hand.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This claims priority under 35 USC 119 from German Patent Appln. No. 10 2004 008 487.4-15, filed Feb. 20, 2004, incorporated herein by reference in its entirety.  
       FIELD OF THE INVENTION  
       [0002]     The invention relates to a compliance module, finding application particularly for a manipulator for positioning a test head. The invention relates further to a manipulator serving particularly for positioning a test head at a testing device and provided with means for positioning a test head three-dimensionally.  
       BACKGROUND ART  
       [0003]     A manipulator for positioning a test head usually has several translational and rotational degrees of freedom in thus being suitable for precisely positioning the test head three-dimensionally. This is why such a manipulator finds application, as a rule, in testing electronic devices, such as for example ICs or wafers. To permit testing proper functioning of the electronic devices it is necessary that the relatively heavy test head is precisely docked at a testing device. The testing device, for example a component handler or wafer tester furnishes the electronic devices to be tested by the test head. Obtaining a genuine result in testing electronic devices requires precise docking of the test head at the testing device, it being for this reason that precisely and smoothly locating the manipulator positioning the test head is mandatory.  
         [0004]     DE 101 32 489 A1 incorporated herein by reference in its entirety describes a manipulator excelling by exactly reproducible motion of the test head. This is primarily due to the manipulator being provided with means for three-dimensionally positioning the test head, comprising articulated arms pivotable in the horizontal plane. The articulated arms are coupled to slides for travelling in the horizontal direction so that any motion of the test head can be split into a translational motion of the slides and a rotational motion of the articulated arms in thus achieving a reproducible location of the positioning means in ensuring reliably correct positioning of the test head.  
       SUMMARY OF THE INVENTION  
       [0005]     Contrary to the precision of the positioning means as needed for a reproducible location is the fact that it has been discovered in actual practice to be an advantage when the position of the test head can be corrected by slight manual jiggling when docking at the testing device. Such a correction to the position of the test head to facilitate docking necessitates a certain compliance of the positioning means.  
         [0006]     The invention is based on the objective of providing a compliance module which is particularly suitable for a manipulator for positioning a test head and by means of which, on the one hand, a precise location, and on the other a certain compliance is achievable.  
         [0007]     To achieve this objective a compliance module is proposed which is provided with a housing that is securable to a component, an inner sleeve shiftingly mounted in the housing and axially urged by a spring element, and a pin arranged on the housing and connected to the inner sleeve.  
         [0008]     The compliance module in accordance with the invention particularly for application on a manipulator for positioning a test head now makes it possible to jiggle movably mounted components, for example means for positioning a test head three-dimensionally, contrary to the effect of a restoring force between a first position and a second position, resulting in the component being endowed with a certain compliance. The restoring force caused by the spring element in the axial direction of the compliance module ensures that despite the compliance generated by the compliance module, a component holding the test head, for example, is suitable to be moved precisely reproducibly.  
         [0009]     Advantageous further embodiments of the compliance module in accordance with the invention read as the claimed subject matter.  
         [0010]     Thus, to advantage, the pin is shiftingly mounted on the housing so that the pin supporting the inner sleeve radially can be moved together with the inner sleeve.  
         [0011]     To achieve a simple connection of the pin to the inner sleeve, preferably the inner sleeve comprises a female thread and the pin comprises a threaded portion mating with the female thread. In this case it has further discovered to be of advantage when the pin comprises a head which positions the inner sleeve contrary to the effect of the spring element in the housing. The head of the pin represents a stop in the axial direction of the compliance module enabling the spring element engaging the inner sleeve to be biased. The amount of this bias depends on the distance between the inner sleeve and the head of the pin. By altering the extent by which the pin is screwed into the inner sleeve, the distance between the inner sleeve and the head of the pin can be varied in thus setting the bias. It is because of this bias that it is assured that it is only possible to move the component when a force exceeding the bias is applied to the component.  
         [0012]     Preferably the pin is rotatably mounted by means of a bearing sleeve and the inner sleeve non-rotatably mounted in the housing, in thus enabling the pin to be screwed into the inner sleeve or screwed out thereof to vary the bias.  
         [0013]     In one preferred aspect of the compliance module in accordance with the invention the housing comprises an axially slot and the inner sleeve is provided with a slaving member engaging the slot. The slaving member guided by the slot holds the inner sleeve in the housing against the bias exerted by the spring element on the inner sleeve and thus assuring non-rotatable mounting of the inner sleeve. The length of the slot dictates the distance by which the inner sleeve is shiftable in the housing.  
         [0014]     To achieve low-friction shifting the inner sleeve is expediently provided with a sliding surface contacting the housing.  
         [0015]     For a simple, compact design it is of advantageous to provide the inner sleeve with a boss for supporting the spring element, The boss is expediently arranged so that the spring element is reliably guided by a portion of the inner sleeve.  
         [0016]     In another preferred aspect of the compliance module in accordance with the invention the inner sleeve is provided with a stopper plate. The stopper plate serves to urge a movably mounted component, for instance a plate mounting a test head, with the restoring force as exerted by the spring element. For this purpose the stopper plate may be made of a suitable material for high impact performance, for example.  
         [0017]     To achieve the objective as cited above it is further proposed, as it reads from claim  10 , a manipulator serving particularly to position a test head on a testing device. The manipulator is provided with means for positioning a test head three-dimensionally and at least one compliance module. By means of the compliance module a movably mounted component can be moved against a restoring force between a first position and a second position.  
         [0018]     One such manipulator is accorded the advantages of the compliance module in accordance with the invention.  
         [0019]     Advantageous aspects of the manipulator in accordance with the invention read from the claimed subject matter.  
         [0020]     Thus, it is of advantage when the movably mounted component features a first contact flat and a second contact flat oriented substantially parallel to each other. The first contact flat is urged by a first compliance module, whereas the second contact flat is urged in the opposite sense by a second compliance module. It is in this way that the movably mounted component can be moved between a first position and a second position in the axial direction of the compliance modules. The restoring force exerted by the compliance modules on the movably mounted component ensures that the component on having left the first position, in other words the home position, is always returned thereto. Because of the compliance modules being arranged opposite in sense the component returns to the home position both from a motion in the direction of the first compliance module and from a motion in the direction of the second compliance module.  
         [0021]     In a preferred aspect the manipulator in accordance with the invention is provided with a support for the test head, the support comprising two side arms between which the test head is tensioned. The side arms tensioning the test head ensure safe securement of the test head even when it is relatively heavy.  
         [0022]     To advantage, the side arms are each provided with at least one fastener plate to which the test head is secured and which is movably mounted. The fastener plate constitutes a movably mounted component in the aforementioned sense engaged by at least one compliance module.  
         [0023]     Preferably the fastener plate is arranged linearly displaceable. So that the position of the test head secured to the fastener plate can be corrected by manual jiggling. As an alternative the fastener plate can be arranged pivotable, enabling the position of the test head secured to the fastener plate to be corrected by jiggling. Advantageously, the fastener plate can be locked in a defined position by locking means to achieve a fixed arrangement of the test head, when required. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     Details and further advantages of the present invention read from the following description of a preferred example embodiment as merely shown diagrammatically in the corresponding drawings in which:  
         [0025]      FIG. 1  is a view in perspective of a manipulator, on which a test head is arranged.  
         [0026]      FIG. 2   a  is a side view of a side arm showing a fastener plate moveably mounted on the side arm in a first position I;  
         [0027]      FIG. 2   b  is a side view of the side arm as shown in  FIG. 2   a  showing the fastener plate in a second position II;  
         [0028]      FIG. 3  is a view in perspective of a compliance module and  
         [0029]      FIG. 4  is a section taken along the line IV-IV in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]     Referring now to  FIG. 1  there is illustrated a manipulator serving to position a test head  60  on a testing device (not shown) for electronic devices, such as, for example, ICs or wafers. For this purpose the manipulator features positioning means  30  comprising a column  31  extending in the vertical direction z. The column is shiftingly mounted on a base frame  34  in a horizontal longitudinal direction x. Arranged on the column  31  is a cross-slide  32  shiftingly mounted in the vertical direction z. The cross-slide  32  extending in a horizontal crosswise direction y is connected to a pivoting arm  33 . The pivoting arm  33  is pivotable about an axis extending in the vertical direction z and shiftingly mounted in the horizontal crosswise direction y by means of the cross-slide  32 .  
         [0031]     As further evident from  FIG. 1  arranged on the pivoting arm  33  is a support  40  for the test head  60 . The support  40  comprises two side arms  41  between which the test head  60  is tensioned. For this purpose each of the side arms  41  is provided with two fastener plates  42 ,  46  to which the test head  60  is secured. The fastener plate  42  is arranged linearly shiftable both horizontally and vertically on the side arm  41  and for this purpose is guided in linear guide  45 , as evident from  FIGS. 2   a  and  2   b  in particular. By contrast, the fastener plate  46  is arranged pivotable about a trunnion  49  on the fastener plate  42 . It is in this way that the fastener plate  46  together with the fastener plate  42  can be shifted along the side arm  41  to achieve, for example, a so-called “theta” motion of the test head  60 . A locking lever  50  ensures that the test head  60  can be locked in the desired home position, whereas a locking lever  51  permits locking the fastener plate  42  in the desired vertical position. Each of the fastener plates  42 ,  46  comprises a first contact flat  43 ,  47  and second contact flat  44 ,  48  oriented substantially parallel to each other. Engaging the first contact flat  43 ,  47  is a compliance module  10   a , the second contact flat  44 ,  48  being engaged by a compliance module  10   b . The first compliance module  10   a  and the second compliance module  10   b  are arranged such that the fastener plates  42 ,  46  are urged in opposite directions.  
         [0032]     Referring now to  FIG. 3  and  FIG. 4  there is illustrated how the compliance module  10  comprises a housing  11  secured to the fastener plates  42 ,  46 . For this purpose the housing  11  is provided with a hole  12 . Shiftingly mounted in an axial direction of the compliance module  10  in the housing  11  is an inner sleeve  18  which for this purpose features a sliding surface area  20  contacting an inner wall of the housing  11 . Furthermore, the inner sleeve  18  is provided with a slaving member  22  supporting a first end of a spring element  25 . A second end of the spring element  25  is supported by an abutment  26  of the housing  11 . The spring element  25  guided by a portion of the inner sleeve  18  accordingly urges the inner sleeve  18  in the axial direction.  
         [0033]     The compliance module  10  is further provided with a pin  14  which by means of a bearing sleeve  17  is rotatably mounted about an axis extending in the axial direction. The pin  14  comprises a head  15  contacting the bearing sleeve  17  axially and a threaded portion  16  projecting into the inner sleeve  18 , the threaded portion  16  mating with a female thread  19  of the inner sleeve  18 . Because of a slaving member  22  axially guided in a slot  13  of the housing  11 , the inner sleeve  18  is non-rotatably mounted in the housing  11 , as a result of which a screw-in distance s by which the pin  14  projects into the inner sleeve  18  can be varied by rotation of the pin  14 . For this purpose the head  15  may feature flats to facilitate rotating the pin  14  by means of a wrench, for example.  
         [0034]     Varying the screw-in distance s alters the distance between the slaving member  22  of the inner sleeve  18  and the abutment  26  of the housing  11 . The spring element  25  supported by the slaving member  22  and the abutment  26  can thus be biased. By how much the inner sleeve is biased can thus be adapted to each case without making it necessary to replace the spring element  25 .  
         [0035]     The inner sleeve  18  features a front end facing away from the pin  14 . Secured to the front end by means of screw  24  is a stopper plate  23 . The stopper plate  23  made, for example, of a high impact material, adjoins the contact flats  43 ,  44 ,  47 ,  48  of the fastener plates  42   46 . Moving the fastener plates  42 ,  46  from the first position I as shown in  FIG. 2   a  into the second position II as shown in  FIG. 2   b  results in this displacement counteracting the restoring force produced by the compliance modules  10   a ,  10   b , i.e. irrespective of whether the fastener plates  42 ,  46  are moved in the direction of the compliance module  10   a  or in the direction of the compliance module  10   b . This is because of the inner sleeve  18  of the compliance modules  10   a ,  10   b  which is axially shiftable by the length of the slot  13  in the housing  11 . When the slaving member  22  of the inner sleeve  18  guided in the slot  13  is located in the first position I, in other words in the home position, for example roughly in the middle of the slot  13 , the inner sleeve  18  can then be shifted axially both to the left and right. The ends of the slot  13  define the shift of the inner sleeve  18  in thus defining the maximum end position II as can be assumed by the fastener plates  42 ,  46 . The bias to which the spring element  25  is subjected in the home position I can be set by the pin  14  in thus ensuring that the fastener plates  42 ,  46  are urged by the compliance modules  10   a ,  10   b  also in the home position I.  
         [0036]     The manipulator as described above permits by the positioning means  30  precise positioning of the test head  60 . In addition, the compliance modules  10   a ,  10   b  ensure a certain compliance of the fastener plates  42 ,  46  to which the test head  60  is secured, since the fastener plates  42 ,  46  can be moved between the home position I and the end position II contrary to the effect of a restoring force in thus making it possible to correct the position of the test head  60  by manual jiggling. The restoring force produced by the compliance modules  10   a ,  10   b  ensures that the fastener plates  42 ,  46  are always returned to the home position I so that reliably precise positioning of the test head  60  is not detrimented because of the compliance existing due to the compliance modules  10   a ,  10   b . This is also supported by it only being possible to move the fastener plates  42 ,  46  when a force exceeding the bias acts on the fastener plates  42 ,  46  because of the spring element  25  as a result of the bias of the compliance modules  10   a ,  10   b . In conclusion, the compliance modules  10   a ,  10   b  are characterized by a simple, compact configuration which takes into account the requirements of cost-effective production.