Abstract:
A probe for test connecting an apparatus contact of a probe apparatus with a test contact of a tested electronic device along a contacting axis has a top structure, a bottom structure a spring member and a guide. The guide may be an outer guide face of the spring member or be part of the bottom or top structure in the form of a circumferential recess or a snap finger. The probe may be guided either slidably in a rigid carrier structure and/or via its circumferential recess in one or two flexible membranes snapped on a rigid support frame. The probes may be simultaneously fabricated in large numbers by micro fabrication techniques with a fixed fabrication pitch and assembled in a probe apparatus with a probe pitch independently of the fabrication pitch.

Description:
FIELD OF INVENTION  
       [0001]     The present invention relates to testing interconnectors. In particular, the present invention relates to a testing probe with an integrated spring member centrally held in a template in an individually replaceable fashion.  
       BACKGROUND OF INVENTION  
       [0002]     With the advancement of micro fabrication techniques, probes for testing electronic circuitry may be increasingly mass fabricated at ever decreasing scale and increasing complexity. In an exemplary multilayer deposition process, a large number of microstructures are simultaneously grown on a substrate by the use of multiple masks and sacrificial fill structures to generate multistep structures substantially free of shape constraints. In the field of probe apparatus fabrication, this multilayer deposition process is used at the time of this invention, to fabricate the probes of a probe apparatus simultaneously on the substrate with a spacing that corresponds to the operational pitch of the finally assembled probes. Unfortunately, probe apparatus are highly individualized devices with many differing pitches of the assembled probes, which have to comply with the particularities of the tested circuitry and/or tested devices. To the contrary, the multilayer deposition process is very cost intensive due to the large number of deposition processes that need to be individually prepared and require also a large number of expensive masks. Therefore, there exists a need for probe designs and probe assembly techniques that utilize the free shaping capabilities of multilayer deposition processes without limitation of the affiliated fabrication spacing constraint. The present invention addresses this need.  
       SUMMARY  
       [0003]     A probe for test connecting an apparatus contact of a probe apparatus with a test contact of a tested electronic device along a contacting axis has a top structure, a bottom structure a spring member and a guide. The guide may be an outer guide face of the spring member. The guide may also be part of the bottom or top structure in the form of a circumferential recess or a snap finger.  
         [0004]     The snap finger may be arranged with respect to the contacting axis and extend substantially parallel to the contacting axis. The snap fingers may have snap hooks for snapping in at a rigid assembly hole of a rigid carrier structure for a releasable positioning together with other probes in a rigid carrier structure. The probe may be guided via its circumferential recess in a carrier structure in the configuration of a flexible membrane snapped on a rigid support frame. A flexible membrane and rigid carrier structure may be employed together.  
         [0005]     The probes are assembled with their carrier structure(s) together with a space transformer that provides the apparatus contacts adjacent the top structure. The space transformer is in a plate spacing to the top of the top carrier structure that is larger than the top structure height such that the carrier structure may be assembled together with a number of probes and the space transformer substantially without deflection of the carrier structure and such that the top structures of the probes are brought into contact with the apparatus contacts during operational contact of the bottom structures with the test contacts.  
         [0006]     The probes may be simultaneously fabricated in large numbers by micro fabrication techniques with a fixed fabrication pitch and assembled in a probe apparatus with a probe pitch independently of the fabrication pitch. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]      FIG. 1  is a first perspective view of a partial probe apparatus according to a first embodiment of the invention.  
         [0008]      FIG. 2  is a frontal cut view of the partial probe apparatus of  FIG. 1 .  
         [0009]      FIG. 3  is a first perspective view of a partial probe apparatus according to a second embodiment of the invention.  
         [0010]      FIG. 4  is a frontal cut view of the partial probe apparatus of  FIG. 3 .  
         [0011]      FIG. 5  is a first perspective view of a probe assembly according to a third embodiment of the invention.  
         [0012]      FIG. 6  is a frontal cut view of the probe assembly of  FIG. 5 .  
         [0013]      FIG. 7  is a detailed frontal cut view of a single assembled probe of the second embodiment.  
         [0014]      FIGS. 8-10  are partial second perspective views of various exemplary configurations of the bottom structure of the probe of the three embodiments.  
         [0015]      FIG. 11  is a second perspective view of the probe of the third embodiment.  
         [0016]      FIG. 12  is a third perspective view of a probe according to a fourth embodiment.  
         [0017]      FIG. 13  is the third perspective view of the probe of  FIG. 12  assembled in a correspondingly shaped assembly hole of a rigid carrier structure. 
     
    
     DETAILED DESCRIPTION  
       [0018]     As in  FIGS. 1, 2 , a probe apparatus  1  according to a first embodiment may include a probe assembly having a number of probes  4  assembled with a probe pitch PPX and PPY in corresponding assembly holes  31  of a rigid carrier structure  3  preferably made of ceramic. The probe  4  has a top structure  43  for conductively operation contacting along a contacting axis CA a corresponding apparatus contact  22  of a circuit board  2 , a bottom structure  41  for conductively test contacting a well known test contact and a spring member  42  interposed in between the top structure  43  and the bottom structure  41 . The carrier structure  3  is substantially planar and extends preferably perpendicular with respect to the contacting axes CA. The contacting axes CA are preferably parallel to each other.  
         [0019]     The spring member  42  conductively connects the structures  41  and  43 . The spring member  42  has an outer guide face  421  with which the probe  4  is guided within a corresponding guide hole  31 . The top structure  43  has a diameter  43 D that is larger than assembly hole diameter  31 D such that the top structure  43  is sandwiched between the carrier structure top  33  and the apparatus contacts  22 . Alignment features  21  of the circuit board  2  snugly fit in alignment holes  32  of the rigid carrier structure  3  for a precise positioning of the probe assembly within the probe apparatus  1 .  
         [0020]     A top structure height  43 H is smaller than a plate spacing  1 H between the apparatus contacts  22  and the carrier structure top  33  such that the carrier structure  3  may be assembled together with a number of probes  4  and the circuit board  2  substantially without deflection of the carrier structure  3  and such that the top structures  43  are brought into contact with the apparatus contacts  22  during operational contact of the bottom structures  41  with the test contacts.  
         [0021]     Operational contact is established when a test contact is forced against the bottom structure  41  forcing the probe  4  along its contacting axis CA towards a respective apparatus contact  22  until contact is established between top structure  43  and assembly contact  22 .  
         [0022]     The spring member  22  may be a coil spring or any other spring structure fitting in close proximity around the contacting axis CA and providing an outer guiding face  421  suitable for slidably interacting with the rigid assembly hole  31  as may be well appreciated by anyone skilled in the art. Two or more coil springs may be interweaved around the contacting axis CA.  
         [0023]     In the first embodiment, the probes  4  are prevented from falling out of the fully assembled probe apparatus  1  irrespective of the probe apparatus&#39;  1  orientation. To provide additionally simplified handling of the probe assembly alone without risk of inadvertent falling out of individual probes  4 , second and third embodiments may be alternately utilized where probes  4 ,  4 F are held in assembly position within the probe assembly alone. This may be advantageous for eventual maintenance work during which both the probes  4 ,  4 F need to be accessed from top and bottom.  
         [0024]     As in  FIGS. 3, 4 ,  7 , a probe apparatus  1  features probes  4  of a second embodiment that have a number of snap fingers  44  acting as guides between the probe  4  and the rigid assembly hole  31  and also provide guidance for the spring member  42 . The snap fingers  44  have snap hooks  441  at their free end for releasable snapping in the rigid carrier structure  3 . The snap fingers  44  may be concentrically arrayed with respect to the contacting axis CA having inner and outer guide faces  44 I,  44 O substantially concentric to their respective other. The outer guide faces  44 O and/or the inner guide faces  44 I may be cylindrical. An outer guide face diameter  44 OD may be slightly smaller than the assembly hole diameter  31 D and a finger length  44 H may be larger than the carrier structure thickness  3 H together with the difference of top structure height  43 H and plate spacing  1 H such that operational contacting may be established before contacting of the snap hooks  441  with the carrier structure bottom  34 . An inner guide face diameter  44 ID is sufficiently larger than a spring guide face diameter  42 OD such that the spring member  42  may freely deflect inside the snap fingers  44 .  
         [0025]     The snap fingers  44  may be combined with the top structure  43  as shown in  FIGS. 3, 4 ,  7  or with the bottom structure  41 , in which case the finger length  41  is larger than the rigid carrier structure thickness  3 H together with the operational deflection range DR. Deflection range DR is the maximum deflection of the assembled probe  4  during operation of the probe apparatus  1 .  
         [0026]     As in  FIGS. 5, 6 ,  11 , a probe assembly of a third embodiment includes alternately or combined flexible bottom membrane  51  and/or flexible top membrane  52  that guide with their respective bottom and top membrane assembly holes  511 ,  521  the probes  4 F via respective first and second circumferential recesses  433  and  413 . In case both membranes  51 ,  52  are employed together, full guidance of the probes  4 F along their contacting axes CA is provided by the flexibility of the membrane. The membranes  51 ,  52  may be combined with a peripheral snap frame  53  and snapped on a rigid snap shoulder  35  of a rigid support frame  3 S. The membranes  51 ,  52  may be made of well known Polyimide. The rigid support frame  3 S may be configured similar to the rigid carrier structure  3 . In case of both employed membranes  51 ,  52  the rigid support frame  3 S may feature an assembly cavity  36  surrounding the probes  4 F.  
         [0027]     In case of a single membrane  51  or  52 , the rigid support frame  3 S may also feature assembly holes  31 . Probes  4 F may be guided additionally within the probe assembly either by spring guide faces  421  or outer snap finger guide faces  44 O as described under first and second embodiments. Bottom membrane  52  is particularly advantageous for sealing the remainder of the probe apparatus  1  against eventual debris from the operational contacting of the bottom structures  41  with the test contacts.  
         [0028]     As in  FIGS. 8-10 , probes  4 ,  4 F may feature numerous contacting features  411  such as a pointed tip  411 A, a wedge  411 B or a cross wedge  411 C. The contacting features  411  may be placed on the bottom structure  41  symmetrically with respect to the contacting axis CA. The pointed tip  411 A may be employed alone or in a number circumferentially arrayed with respect to the contacting axis CA.  
         [0029]     As in  FIGS. 12 and 13 , a probe  4 G of a fourth embodiment may be fabricated as a continuous profile with a profile height DH. In the first, second and third embodiment, the probes  4 ,  4 F may be fabricated by layered fabrication processes in direction parallel to the contacting axis CA. In the fourth embodiment to the contrary, the probe  4 G may be fabricated by a layered fabrication process in a direction perpendicular to the contacting axis CA. In that fashion, only a single fabrication layer may be employed for fabricating a complete probe  4 G.  
         [0030]     In the fourth embodiment, the spring member  42 B is configured as a buckling beam preferably with a buckling orientation substantially in plane with the two snap fingers  44 F. The buckling beam  42 B has a buckling beam height  42 BH preferably equal the profile height DH and slightly smaller than a hole width  31 H of a rectangular rigid assembly hole  31 R such that the buckling beam  42 B is supporting itself against the assembly hole  31 R in a direction perpendicular to the buckling orientation. In addition, the buckling beam  42 B may be configured for supporting itself in buckling orientation against at least one inner snap finger guide face  44 FI along at least one support interface  422  shaped for a snug contact with said snap finger guide face  44 FI during at least a portion of the probe&#39;s  4 G operational deflection range DR. The rectangular assembly hole  31 R has a hole length  31 W that corresponds to the distance  44 OW between the outer snap finger guide faces  44 FO. The bottom structure  41  is guided by the inner snap finger guide faces  44 FI.  
         [0031]     The dimensions of all snap hooks  441  are selected in conjunction with other affiliated dimensions of assembly holes  31 ,  31 R and probes  4 ,  4 G for a maximum deflection of the snap fingers  44 ,  44 F during insertion into the assembly hole  31 ,  31 R unimpeded by adjacent probe structures or members as may be well appreciated by anyone skilled in the art. The probes  4 ,  4 F may also be permanently combined with the apparatus contacts  22  by well known reflow techniques. The probes  4 ,  4 F may be monolithically fabricated or may be made of materials suitable to accomplish their particular task. Nickel Cobalt plated with Gold is an example of suitable metal combination.  
         [0032]     Accordingly, the scope of the invention described in the specification above is set forth by the following claims and their legal equivalent: