Abstract:
An adapter for positioning of contact tips has a location surface for locating a contact tip and a base element with a base for setting the adapter on a mounting surface. A positioning element is in mechanical contact with and mobile relative to the base element. The location surface can be positioned relative to the base, in at least one positioning direction, by the positioning element which includes a gearing for converting rotary movement to translational movement in the positioning direction.

Description:
BACKGROUND ART 
     The invention relates to an adapter for positioning of contact tips. The adapter has a location surface for locating a contact tip as well as a base element with a base. This base is used for setting the adapter on a mounting surface. A positioning element that is mobile relative to the base element is in mechanical contact with the base element so that the location surface can be positioned relative to the base in at least one direction by means of the positioning element. 
     Adapters of this kind are used for precise positioning of all varieties of contact tip which, according to their application, establish a locally restricted electrical, mechanical or thermal contact with a component. This kind of precise contacting is necessary in all varieties of applications, in particular microelectronics. 
     Positioning mechanisms that use micrometer screws or X-Y cross tables are known there in particular for positioning of probe tips on the contacts of semiconductor components to be tested. Although such position mechanisms allow highly precise positioning, they are not suitable for continuous flow testing in ongoing production in terms of their time requirement for each individual positioning, their space requirement and their costs. Such complex mechanisms are not always needed where one-off positioning of one or more contact tips relative to a fixed point is carried out and is used for a large number of identical contact tips in that the components to be contacted are positioned with a high level of reproducibility relative to this fixed point. 
     As several contacts are to be established simultaneously in most applications when testing semiconductor components, including on an industrial scale, and these contacts have a defined position in relation to each other, the positioning of the contact tips in relation to each other is particularly important in these cases. For this purpose, the contact tips are fixed on probe cards in the corresponding position in relation to each other, and these probe cards are used in isolation or on the wafer in the testing arrangement relative to the mounting of the component to be tested. For industrial production testing, the individual probe tips and the probe cards are standardised for the various applications, in particular high-frequency (HF) and direct current (DC) probe tips. The probe cards are mostly disc-shaped insulation carriers that are equipped with the necessary components and devices for electrical contacting of the probe tips and with a mechanically stable, mostly metallic supporting ring for installation in the testing station. 
     The probe tips are mounted on the probe cards with suitable adapters, mostly in the form of simple geometric dies or base plates, and positioned relative to each other. This assembly does not allow subsequent adjustment of the position. If fingerlike DC probe tips are assembled in this way, adjustment of the tips relative to each other is possible to a limited extent by bending the probe tips. However, if comb-shaped HF probe tips are used, the shape of the tips precludes this possibility, and assembly itself can only be performed with a high degree of precision, mostly only on specially equipped workstations. As the necessary mechanical contacting causes a high level of wear in continuous flow testing, this procedure must be performed regularly for renewing the probe tips, involving a large amount of time and expenditure. 
     U.S. Pat. No. 4,971,159 describes a micropositioner in which, depending on the number of necessary positioning directions, a corresponding number of plates are arranged, each of which are moved against each other in the corresponding direction. The moving of an individual plate is effected by means of a mechanical impulse of a piston based on the necessary movement, which piston is arranged in a mobile manner in a cylinder and is moved by means of pressurised air. As a result of the fixed connection of the cylinder with the respective plate, the impulse is transferred to the plate. One disadvantage here is the need for a pneumatic system with the corresponding number of separate connections and a complex, separate or adjustable channel route up to each piston. The space requirement for the cylinder and the piston, which must always have a minimum dimension and be moveable along a minimum distance in order to generate the necessary impulse, is obstructive. This particularly applies if a large number of probe tips are to be placed next to each other on a probe card. 
     BRIEF SUMMARY OF THE INVENTION 
     One aspect of the invention is therefore to provide a positioning system of the aforementioned kind with which contact tips can be positioned precisely in a fixed end position in a manageable, space-saving, independent and low-cost manner. 
     This aspect is firstly achieved by means of a positioning system that has the characteristics of claim  1 . Advantageous embodiments of this positioning system can be found in the claims that refer back to claim  1 . 
     The term for the “gearing”, with which the location surface is moved according to the invention, is to be understood here in line with its general meaning as a mechanism for converting movements, i.e. for guiding parts on a defined motion path. By tapping the translational movement that is needed to position the location surface and, via its connection with the contact tip, to position the contact tip, from the rotating drive section by means of a suitable sampler and transmitting it to a translation element by means of a coupling element, the necessary precision is attainable through the corresponding design of the gearing and both motion sequences can be realised in a very small space. 
     In accordance with the spatial conditions, the size of the area in which the contact tip is to be positioned and the force to be transmitted that is necessary to move the contact tip including the connection means with the positioning element, different types of gearing with the above-mentioned function can be used. One advantage here is that a limited distance is to be overcome only at the time of positioning and no continuous movement is to be realised. The necessary temporary rotational movement can be triggered in accordance with the gearing used in a wide variety of ways, in the simplest case by means of a non-recurring, purely mechanically triggered rotation of the drive section, for example a screw, so that the positioning element forms a self-contained unit without the need for media connections. 
     If the set position (end position) of the contact tip is to be maintained for a defined period and/or a force is to be exerted on the contact tips that is suitable for moving the contact tip from this position, the end position can be fixed by means of suitable elements in accordance with an embodiment of the adapter. The elements for fixing are to be adapted in accordance with the forces produced and the complexity of the adapter. 
     The object according to the invention is also achieved by means of an adapter that comprises the features according to claim  2 . Advantageous embodiments can in turn be found in the claims that refer back to claim  2 . This adapter according to the invention also enables positioning of the location surface of the adapter and therefore of a contact tip mounted on the location surface by means of a simple mechanical actuation capability with which the extension arm is changed in terms of its deflection and then fixed in the new position. However, deflection can also be carried out by means of a magnetic or electrical field. 
     Depending on the shape of the extension arm, one-dimensional or two-dimensional positioning is possible with this adapter. With a tongue-shaped extension arm that, depending on the shape, has a fixed and a free edge or corner, deflection is, for example, only possible in one direction, that of the surface normals. In contrast, a rod-shaped extension arm allows two-dimensional deflection and positioning. The arrangement of an extension arm relative to the base is possible in accordance with the necessary positioning direction so that movement in the x, y or z direction or a corresponding combination of two directions can be attained with the extension arm. 
     The shape of the extension arm depends on factors including the contact tip to be located, so that the extension arm in the standardised HF or DC probe tips used for component testing with a longitudinally extended fastening surface, for example, is tongue-shaped. 
     To allow three-dimensional positioning of the location surface, according to particularly advantageous embodiments of the invention, it is possible to combine several gearings for each direction of an adapter or one or two gearings with an extension arm in an adapter. As a result of the compact and easily operable form of gearing and extension, a combination of the two also has the described advantages. 
     It has proved to be particularly advantageous that the positioning of a contact tip can be carried out on site by the user with the adapter according to the invention independently of the embodiment described above with no special aids and the geometric design of the adapter itself allows such degrees of freedom that it can be adapted to all kinds of contact tips and to all kinds of mounting surfaces, for example standardised probe cards, without impeding the necessary electrical contacting of the contact tips or mechanical load shedding of the leads. 
     A further advantage is the opportunity to provide a separate adapter even in a very small space for every contact tip so that the contact tips can be positioned in relation to each other individually. The combination of the described embodiments also makes it possible to position several tips jointly in one positioning direction and, additionally, to position them separately from each other. 
     In accordance with a further embodiment of the adapter, the angle between the base and the location surface can be changed and fixed by means of torsion of the extension arm so that, depending on the shape of the extension arm, a defined rotation or a defined angle of the contact tip can be set in relation to its axis or in relation to the base of the adapter. Insofar as the torsion of the extension arm serves the purpose of levelling the contact tip, the torsion of the extension arm should be approximately 0 to 3° according to an embodiment of the invention. 
     Insofar as an additional positioning direction is to be set with an additional gearing with the adapter, it proves to be favourable if the positioning element is designed in two pieces. In this way, it is possible to position the entire positioning element relative to the base of the base element in one direction with the first gearing and to position one part of the positioning element relative to the other and therefore relative to the base in the other direction with the second gearing. This embodiment also has the advantageous properties described above in terms of design, ease of operation and combination capability of the different variants of the adapter. 
     The aspect is particularly achieved by an adapter that has an eccentric with at least one guide element for guiding the movement of the location surface in the respective positioning direction as a gearing for converting a rotatory movement to a translational movement. The need for a movement of the contact tip that is limited in terms of time and space for positioning thereof allows this simple design. 
     As a drive section, different designs are possible that have an eccentric structure in terms of the rotation axis, for example a pin arranged outside the rotation axis or a disc whose centre is outside the rotation axis. There are also various possibilities as a sampler for tapping the movement. For example, a defined, linear slot design in the translation section is conceivable into which the drive section engages, or a linear edge of the translation section that is pressed onto the drive section by means of a return element, e.g. a screw. 
     The guide that the positioning element has in this embodiment forces the translation section into the requisite direction of movement. In the simplest case, this guide can consist of one or more slots in which one or more pins run. The precision of the direction of movement can be improved through the arrangement of two guide elements. 
     Depending on whether the positioning element has one gearing or an additional one, the described translation section is the entire positioning element or part of it. The movement of the translation section into the requisite positioning direction is carried out with the described adapter through simple rotation of the eccentric. This can be initiated mechanically or electrically. 
     For many applications, particularly in microelectronics, it is sufficient and particularly favourable for the design of an adapter according to the object if the positioning element realises movements of the location surface relative to the base in the range up to 5 mm, preferably up to 1 mm. For motion sequences of this application in a larger range, as described above, the more complex positioning mechanisms to be operated under laboratory conditions are mostly used, with the corresponding dimensioning of the gearing or extension arm also making it possible to use the adapter according to the invention. 
     As a result of the described simple, compact construction and the low laterally acting forces that are produced during positioning compared with the described positioning mechanism according to the state of the art due to application of the gearing and/or the extension arm, it is possible to fasten the adapter on a mounting surface by means of vacuum suction or magnetic attachment in addition to the known mechanical mounting methods using screws or clamps. Crucial factors for the type of mounting are firstly the forces produced and secondly the material and shape of the adapter as well as the design and freedom of assembly of the mounting surface. If the possibility of connection to a vacuum source and sufficiently even fitting surfaces are present, suction of the adapter can be carried out particularly easily. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The invention is explained in further detail below on the basis of an execution example. In the associated drawing, 
         FIG. 1  shows a perspective view of an adapter according to the invention; 
         FIG. 2  shows a top view of an adapter according to  FIG. 1  in a mirror-image execution; 
         FIG. 3  shows a cross-section view of the adapter according to  FIG. 2 , along the line of intersection A-A; 
         FIG. 4  shows a side view of the adapter according to  FIG. 2  and 
         FIG. 5  shows a perspective view of a probe card with four contact tips and three adapters according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The adapter  1  according to the invention according to  FIG. 1  and  FIG. 2  comprises a base element  2  in the form of a flat plate with an even base  3 . The positioning element  5  is mounted on the even top surface  4  of the base element  2 , which top surface is parallel to the base. 
     The positioning element  5  is designed in two pieces and consists of a bottom section  6  and a top section  7 . The bottom section  6  largely consists of an L-shaped plate that rests on the base plate  2  with the entire surface of its even underside. The top section  7  rests on a rectangular partial surface of the bottom section  6  with a segment. The top section  7  consists of a stepped main body whose top horizontal step  8  rests on the bottom section  6  with its entire surface. The stepped shape of the top section  7  is formed in such a way that the remaining surface that faces the bottom section  6  and the base element  2  maintains an equal distance from the bottom section  6  and the base element  2 . This distance ensures movement of the top section  7  relative to the bottom section  6  and is dimensioned in accordance with the freedom of movement required for positioning in the two horizontal directions (x and y directions). The adapter  1  shown realises positionings in the range up to 1 mm in each of the three directions of movement. 
     An extension arm  11 , also stepped, is attached on the horizontal top side of the top step  8  of the top section. The extension arm  11  is connected with the top section  7  along a narrow, longitudinally stretched joining surface  10  in the central third of the top side of the top section, the connection being designed as a material joint that ensures movement of the extension arm  11  in the z direction. The extension arm  11 , with its surface facing the top section  7 , replicates the stepped shape of the top section  7  and has an almost consistent distance to the top section  7  along this entire surface. This distance ensures the deflection of the extension arm  11  in the vertical direction (z direction) in relation to the base  3  of the adapter  1  and is also dimensioned in accordance with the freedom of movement required in this direction. The lowermost horizontal surface of the stepped extension arm  11  runs parallel to the base  3  of the adapter  1  and ends at a distance therefrom that is less than the height of the base element  2 . This distance also ensures the displacement of the extension arm  11  and is dimensioned accordingly. 
     The horizontal top side of the bottom step  13  of the extension arm, which runs parallel to the base  3  of the base element  2 , serves as the location surface  14  for locating the contact tip  40 ,  41 . For fastening the contact tip  40 ,  41 , this step of the extension arm  11  has drilled holes  15  and/or screws  16  ( FIG. 2 ) which help give the contact tip  40 ,  41  screw-on capability. The number and distribution of the drilled holes  15  and/or screws  16  are adapted to the design of a contact tip  40 ,  41  that is not shown. 
     The positioning of the location surface  14  relative to the base  3  can be realised with the shown adapter  1  in the x, y and z direction. For this purpose, the positioning element  5  is arranged on the base plate  2  in a shiftable manner and the top section  7  of the positioning element  5  is shiftable on the top section  6  thereof. 
     For shifting the positioning element  5 , a first gearing  17 , consisting of two eccentrics  18  and a guide element  19 , is arranged. These are designed in such a way that the actuation of both eccentrics  18  generates a shift of the positioning element  5  in the x direction as marked in  FIG. 1  and  FIG. 2 . Both eccentrics  18  consist of an eccentric disc  22 , each of which are inserted in a notch  24  in the bottom section  6  of the positioning element  5  and on the bottom side of which a cylindrical eccentric pin  25  is attached whose axis  26  is offset in relation to the axis of the eccentric disc  23  in the y direction. As shown in  FIG. 2 , the offset of both eccentric pins  25  is identical in terms of direction and amount. Corresponding to each of the two eccentric pins  25 , an eccentric slot  27  with a width according to the pin diameter is arranged in the base element  2  so that each eccentric pin  25  engages in an eccentric slot  27 . Both eccentric slots  27  realise the freedom of movement of the eccentric pins  25  of the first gearing  17  in the y direction during rotation of the eccentric discs  22 . Both eccentric discs  22  have on their top side a hexagonal recess  28  into which a tool for rotating the eccentric disc  22  can engage. 
     The guide element  19  of the bottom section  6  of the positioning element  5  consists of a guide pin  20 , which is set into the bottom section  6  of the positioning element  5  and engages in a corresponding guide slot  21  in the base element  2 . 
     As a result of simultaneous rotating of the two eccentric discs  22 , both eccentric pins  25  define a circular movement. Whereas the y component of this circular movement does not lead to any movement of the positioning element  5  through the eccentric slots  27  that run in the y direction, the positioning element  5  follows the x component as a result of the course of the guide slot  21  in the x direction. The distance that can be covered in this direction with the described eccentrics equates to twice the offset between the eccentric pin axis and eccentric disc axis  26 ,  23 , i.e. the diameter of the circular movement of each eccentric pin  25 , plus the diameter of the eccentric pin  25  itself. 
     The arrangement of two eccentrics  18  to be operated simultaneously can stabilise the movement and increase the positioning precision. 
     The top section  7  is shiftable in the y direction in relation to the bottom section  6  by means of a second gearing  29 , consisting of an additional eccentric  18  and an additional guide element  19 . The eccentric  18  of the top section  7  is structurally identical to those of the bottom section  6 , except that the alignment of its eccentric slot  27  and its guide slot  21  is adapted to the positioning direction of the top section  7 , i.e. the eccentric slot  27  runs in the x direction and the guide slot  21  runs in the y direction. As a result of the fitting of the eccentric disc  22  into a notch  24  of the top section  7  and the formation of the eccentric slot  27  as well as the guide slot  21  in the bottom section  6  of the positioning element  5 , the top section  7  is shifted relative to the bottom section  6  through rotation of this eccentric  18 . To stabilise this movement, the additional guide element  19  contains two guide pins  20  that engage in the same guide slot  21 . 
     Both the bottom section  6  and the top section  7  of the positioning element  5  have two locking screws  30  that are arranged next to the eccentrics  18  and the guide elements  19  and help make each set position fixable. 
     The positioning of the location surface  14  in the z direction by means of the extension arm  11  is carried out through displacement of the extension arm  11  from its rest position or a fixed starting position. By means of an adjusting element  31  in the form of a grub screw  32 , which presses against the horizontal surface of the bottom step of the top section  9  as a result of screwing into a drilled hole  15  with the thread in the top step of the extension arm  12 , the extension arm  11  is moved in the positive z direction. The displacement in the opposite z direction is effected through simultaneous tightening of two jack screws  34  that are arranged symmetrically either side of the adjusting element  31  and screwed into the bottom step of the top section  9 . The position is fixed here by means of the adjusting element  31 . 
     The adjusting element  31  is arranged on the axis of symmetry of the extension arm  11  so that, by means of the two jack screws  34 , the angle of the extension arm  11  and therefore that of the location surface can be changed in relation to the base  3  due to partial, opposing tightening and loosening of both jack screws  34 . The opposing tightening and loosening of the jack screws  34  effects torsion of the extension arm  11  around its axis of symmetry in accordance with the existing distance between the extension arm  11  and the top section  7 . At the same time, the extension arm  11  is fixed in its z position. 
     The adapter  1  shown in  FIG. 2  is designed in a similar manner to the one in  FIG. 1 , but in a mirror image thereof, with the axis of reflection corresponding to the axis of symmetry of the extension arm  11  and being represented by the axis of intersection A-A in  FIG. 2 . This mirror-image design enables the arrangement of both adapters  1  with the sides facing away from the first joint  18  directly next to each other. Through a corresponding redesign of the base  3  and the bottom section  6  of the positioning element  5 , the first joint  18  can be arranged in such a way that a whole series of adapters  1  can be arranged next to each other in a very small space. 
     The adapter  1  according to  FIG. 2  shows a possible variation of the adjusting element  31  and the jack screws  34  as well as the fastening for the contact tip  40 ,  41  on the location surface  14 . 
     In the embodiment shown, the adjusting element  31 , in addition to the grub screw  32 , which presses against the top step of the top section  8  here, comprises an additional locking screw  33 , with both screws  32 ,  33  being arranged on the axis of symmetry of the extension arm  11 . Both jack screws  34  are arranged on both sides next to the locking screw  33  and symmetrical thereto. 
     In  FIG. 3 , in which the adapter  1  according to  FIG. 2  is shown in cross-section according to the line of intersection A-A, the offset of the axis of the eccentric disc  23  to the axis of the eccentric pin  26  of the second gearing  29  is shown.  FIG. 4 , a side view of the adapter  1  according to  FIG. 2 , shows the offset of the axis of the eccentric disc  23  to the axis of the eccentric pin  26  of the first gearing  17 . 
       FIG. 5  shows the adapter  1  according to the invention, installed in a probe card  35  that is used for testing semiconductor components on the wafer. The probe card  35  consists of an insulation carrier  36  and a supporting ring  37 . The insulation carrier  36 , which acts as the mounting surface  44  for the adapter, has a central, rectangular opening  38  through which contact tips  40 ,  41  can contact the semiconductor components. 
     By means of three adapters  1  and an attachment  39 , three positionable contact tips  40  and a fixed contact tip  41  can be mounted on the probe card  35 . The three positionable contact tips  40  are positioned by means of the adapter  1  according to  FIG. 1  or  2  relative to the fixed contact tip  41  in this position and in such a way that the four tips  40 ,  41  can jointly contact a repeating contacting pattern of the semiconductor elements many times in that after the first contacting, a wafer that is not shown in more detail is shifted in accordance with the pitch in which the semiconductor components are arranged thereon relative to the probe card  35  and fed to the contact tips  40 ,  41 . 
     The contact tips  40 ,  41  can be electrically contacted by means of electrical leads  42 . To avoid disturbing the positioning of the contact tips  40  through mechanical voltages of the leads  42 , the leads  42  are mechanically fixed free of tension by means of strain-relief clamps  43 . 
     Adapter for Positioning of Contact Tips 
     Key 
     
         
           1  Adapter 
           2  Base element 
           3  Base 
           4  Top surface 
           5  Positioning element 
           6  Bottom section 
           7  Top section 
           8  Top step of the top section 
           9  Bottom step of the top section 
           10  Joining surface 
           11  Extension arm 
           12  Top step of the extension arm 
           13  Bottom step of the extension arm 
           14  Location surface 
           15  Drilled hole 
           16  Screw 
           17  First gearing 
           18  Eccentric 
           19  Guide element 
           20  Guide pin 
           21  Guide slot 
           22  Eccentric disc 
           23  Axis of the eccentric disc 
           24  Notch 
           25  Eccentric pin 
           26  Axis of the eccentric pin 
           27  Eccentric slot 
           28  Recess 
           29  Second gearing 
           30  Locking screws 
           31  Adjusting element 
           32  Grub screw 
           33  Additional locking screw 
           34  Jack screw 
           35  Probe card 
           36  Insulation carrier 
           37  Supporting ring 
           38  Central opening 
           39  Attachment 
           40  Positionable contact tip 
           41  Fixed contact tip 
           42  Lead 
           43  Strain-relief clamp 
           44  Mounting surface