Abstract:
A method and apparatus for bending probe pins that is semi-automated and uses machine vision to eliminate human error.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    The present invention relates generally to an improved method of making probe needles for probe cards. More particularly, the present invention relates to the apparatus used in bending the probe needles for probe cards.  
           [0003]    2. Description of Prior Art  
           [0004]    Probe needles (or leads) used for probe card assembly are now bended and inspected manually. The probe needles are bent to the desired tip diameter and angle with a tool known as a jig. A trial and error method is used during the setup until the desired parameters are achieved. The inspection for the desired tip length, diameter and angle is done on a shadow comparator. Comparison is done by matching the shadow of the needle to a template.  
           [0005]    Workers in the art are aware that this process is slow, tedious, and prone to human error. The human error and manual aspects of this process lead ultimately in not being able to use about 20 percent of probe pins.  
           [0006]    Others have striven to solve this problem. For Example U.S. Pat. No. 5,513,430 (Yanof et al.) teaches creating the leads as part of the device and using resist and deposition to form the probe needles at appropriate angle. U.S. Pat. No. 4,892,122 (Ickes) teaches a probe pin alignment tool. U.S. Pat. No. 4,510,686 (Foster) teaches an apparatus for straightening and aligning leads. However this straightening and aligning takes place after the probe needles were bent. U.S. Pat. No. 5,969,533 (Takagi) shows a very general process of a probe card having bent probe tips. Finally, U.S. Pat. No. 5,517,126 (Yamaguchi) teaches a probe apparatus for testing.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, the present invention provides a method for bending the probe needles that is semi-automated and uses machine vision to eliminate human error. Further to improve the output of the probes from approximately 1.5 minutes per probe to approximately 7.5 seconds per probe. Finally the devices that are unusable due to error in probe needles drops from approximately 20 percent to approximately 1 percent.  
           [0008]    Another purpose of the present invention is to provide an apparatus for bending a probe pin having a base structure with a guide block attached to the top of the base structure. The structure further comprising a bending fixture for bending of a probe pin such that a probe pin can be placed on the guide block and pushed into place, and then bended by the bending fixture. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    In the accompanying drawings forming a material part of this description there is shown:  
         [0010]    [0010]FIG. 1 shows a perspective view of an apparatus of the current invention.  
         [0011]    [0011]FIG. 2A shows a cross-sectional view of a guide block of the apparatus of the current invention.  
         [0012]    [0012]FIGS. 2B show a top view of a guide block of the apparatus of the current invention.  
         [0013]    [0013]FIG. 3 is a simplified cross-sectional view of a probe pin on the guide block of the apparatus of the current invention.  
         [0014]    [0014]FIG. 4 is a simplified cross-sectional view of a probe pin on the guide block and ready to bend.  
         [0015]    [0015]FIG. 5 is a simplified cross-sectional view of a probe pin during bending on the guide block of the apparatus of the current invention.  
         [0016]    [0016]FIG. 6A-C is another set of simplified cross-sectional views of a probe pin during bending on the guide block of the apparatus of the current invention emphasizing the bending fixture having a pivotal feature.  
         [0017]    [0017]FIG. 7 is a simplified cross sectional view of a second embodiment of the current invention.  
         [0018]    [0018]FIG. 8 is a simplified cross sectional view of the probe pin on the incoming tray of the invention.  
         [0019]    [0019]FIG. 9 is a simplified cross sectional view of an optional pick-up finger of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    Referring now more particularly to FIG. 1, an apparatus for bending probe pins  10 . The apparatus  10  consists of a base  12 . The base  12  is preferably made of Aluminum. The base has two guide blocks  14   a  and  14   b . Only one guide block is in use at a time, the operator is loading a second guide block while the other is being used. The guide blocks  14   a  and  14   b  have the ability to slide into position for bending and then out of position for bending. The guide blocks are preferably made of Aluminum. Probe pins can be manually placed on guide blocks or optionally the probe pins can be placed on an incoming tray  40  along side the apparatus  10  (see FIG. 8). Optionally, a pick up finger  42  shown in FIG. 9 can suck up the probe pin  30  from the incoming tray  40  and transfer it to the guide block  14   a  or  14   b . Near guide block  14   a  is a probe pin pusher  16 . The probe pusher  16  pushes the probe pin until the vision camera  24 , See FIG. 6 a , detects a desired length. The probe pin pusher is preferably made of Aluminum.  
         [0021]    As seen in FIGS. 2 a  and  2   b , guide block  14   a  also has a groove  18  to guide probe. The apparatus further has fixture  20  having a vision camera  24 , and a bending fixture  26 .  
         [0022]    As shown in FIG. 3 guide block  14   a  further has a cramp  26  and a spring  28  so that the cramp will hold down a probe pin  30 . A stepper motor  44  is connected to a probe pusher  16 . The stepper motor will push the probe pusher so that the probe pin is at the proper distance.  
         [0023]    In FIG. 4, the probe pin  30  is placed ready for bending. Vision camera  24  will determine length A. The probe pins have a diameter of 10 to 16 mils at the thickest section The probe pins have a diameter of 6 to 10 mils and the average pin is usually 0.6 to 2 mils and an average of 1 mils at the point of the probe pin. The probe pin length is 0.5 to 3 inches and the average pin is usually 1 inches. The probe pins are usually made of Tungsten or Rhenium Tungsten. Vision camera  24  measures the probe pin to make sure the probe pin placement is correct.  
         [0024]    As shown in FIG. 5 bending fixture  26  comes down to bend probe pin  30 , while the cramp  26  holds the probe pin in place and the vision camera checks the bending angle. After the bending of the pin, the pin can be taken off manually or, again the optional pick-up finger  42  can suck up the probe pin  30  and transfer to the loading tray  40 .  
         [0025]    [0025]FIG. 6 further illustrates the bending process with a simplified drawing that does not show some of the details of the invention FIG. 6 a  shows probe pin pusher  16  that has pushed the probe pin till a desired length detected by the vision camera  24 . FIG. 6 a  further illustrates the structure of bending fixture  26 . Bending fixture  26  has an adjusting screw  32  and a horizontal portion  34 . The horizontal portion  34  of bending fixture  26  pivots as bending fixture  26  lowers to bend the probe pin, see FIG. 6 b . FIG. 6 c  illustrates the vision camera  24  inspecting the angle, and tip length of the probe pin once bent The angle of the bent probe pin is preferably 100 to 110 degrees.  
         [0026]    [0026]FIG. 7 illustrates a second embodiment of the invention. Bending fixture  26  in this embodiment further comprises a pin  36 , and a block  38  that lowers toward the probe pin as bending fire  26  lowers to bend the probe pin The block  38  can be made out of metal or a plastic.  
         [0027]    While the invention has been partiularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form, and details may be made without departing from the spirit and scope of the invention.