Abstract:
A probe tip for attaching to a device to be tested includes a flexible circuit board, at least one contact pad arranged to be able to be attached to at least one contact of a probe tip connector, at least one electrical component having first and second ends, and at least one test pad arranged to be able to be attached to the device to be tested. The at least one contact pad is connected to the first end of the at least one electrical component, and the at least one test pad is connected to the second end of the at least one electrical component. Each of the electrical components of the probe tip is connected to at least one contact pad and is connected to at least one test pad.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to probe tips. More specifically, the present invention relates to probe tips including a flexible circuit board. 
         [0003]    2. Description of the Related Art 
         [0004]    It is currently known to test a device by soldering a lead of a resistor to an electrical path on the device so that electrical signals transmitted through the electrical path can be monitored and tested. This method has several drawbacks. First, if more than one electrical path needs to be tested, then a lead of a resistor must separately be soldered to each electrical path. Second, the electrical stub length, which is the length of the lead of the resistor soldered to the electrical path, is long and can be quite inconsistent between different resistors because a technician must cut the lead of each of the resistors soldered to the electrical path. Third, the leads of the resistor are stiff and prone to breaking. Fourth, the soldering of the leads of the resistor to the electrical path can damage or destroy the electrical path. Fifth, additional metal (i.e., the solder used to attach the lead of the resistor) can distort the electrical signals transmitted through the electrical path. Sixth, it is difficult to de-solder the lead of the resistor from the electrical path. 
         [0005]    It is also known to use a probe tip that is not solder to the device to be tested. The problem with this method is that it is very difficult to consistently provide a mechanical connection between the probe tip and the device, which makes it very difficult to accurately and reliably test the electrical signals transmitted in the device to be tested. 
       SUMMARY OF THE INVENTION 
       [0006]    To overcome the problems described above, preferred embodiments of the present invention provide a probe tip that solves at least one of the above described problems. 
         [0007]    According to a preferred embodiment of the present invention, a probe tip for attaching to a device to be tested includes a flexible circuit board, at least one contact pad arranged to be attached to at least one contact of a probe tip connector, at least one electrical component having first and second ends, and at least one test pad arranged to be attached to the device to be tested. The at least one contact pad is connected to the first end of the at least one electrical component, and the at least one test pad is connected to the second end of the at least one electrical component. Each of the electrical components of the probe tip is connected to at least one contact pad and is connected to at least one test pad. 
         [0008]    The at least one electrical component is preferably a resistor. A stiffener is preferably attached to a portion of the flexible circuit board. The at least one electrical component is preferably located on or in a portion of the flexible circuit board which is located away from the portion of the flexible circuit board connected to the stiffener. Preferably, the probe tip includes at least one pair of electrical component pads, where the first end and the second end of the at least one electrical component are attached to corresponding pads of the at least one pair of electrical component pads. 
         [0009]    The at least one electrical component is preferably attached to the surface of the flexible circuit board. The at least one electrical component is preferably provided on or in a layer within the flexible circuit board. The at least one contact pad and the at least one test pad are preferably located on opposing surfaces of the flexible circuit board. The at least one test pad preferably includes a pair of test pads that is arranged on opposing sides of the flexible circuit board and that is arranged such that heat applied to one pad of the pair of test pads is transferred to the other pad of the pair of test pads. The at least one test pad preferably includes a through hole. 
         [0010]    Preferred embodiments of the present invention include a probe tip assembly that includes the probe tip discussed above and a probe tip connector including at least one contact. The at least one contact of the probe tip connector is attached to the at least one contact pad of the probe tip. The at least one contact is preferably soldered to the at least one contact pad. 
         [0011]    Preferred embodiments of the present invention include a connector assembly that includes at least one probe tip assembly discussed above, a test equipment connector, and at least one cable connecting the at least one probe tip assembly and the test equipment connector. The connector assembly preferably includes a circuit board, where the at least one cable is attached to the circuit board and where the probe tip connector is attached to the circuit board. The connector assembly preferably includes a circuit board connector, where the circuit board connector connects the probe tip connector and the circuit board. 
         [0012]    Preferred embodiments of the present invention include a testing assembly that includes a connector assembly discussed above, test equipment, and a device to be tested. The connector assembly connects the test equipment and the device to be tested. 
         [0013]    Preferred embodiments of the present invention include a method of testing a device that includes providing the device, providing a probe tip that is connected to test equipment by a connector assembly, attaching the probe tip to the device, and testing the device. The probe tip includes a flexible circuit board. 
         [0014]    The step of attaching preferably includes the step of soldering the probe tip to the device. After the step of testing, the probe tip is either removed from the device or is left on the device. 
         [0015]    Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1A  is a perspective view of a connector assembly according to a preferred embodiment of the present invention. 
           [0017]      FIG. 1B  is a perspective view of a portion of the connector assembly shown in  FIG. 1A . 
           [0018]      FIG. 1C  is a perspective view of a portion of the connector assembly shown in  FIG. 1A . 
           [0019]      FIG. 2A  is a perspective view of a probe tip assembly according to a preferred embodiment of the present invention. 
           [0020]      FIG. 2B  is a side view of the probe tip assembly shown in  FIG. 2A . 
           [0021]      FIG. 3  is a perspective view of a probe tip according to a preferred embodiment of the present invention. 
           [0022]      FIG. 4  is a top plan view of the probe tip shown in  FIG. 3 . 
           [0023]      FIG. 5  is a bottom plan view of the probe tip shown in  FIG. 3 . 
           [0024]      FIG. 6  is a side view of the probe tip shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0025]    The present invention will be discussed with reference to  FIGS. 1A-6 .  FIGS. 1A-1C  show a connector assembly  100  according to a preferred embodiment of the present invention.  FIGS. 2A and 2B  show a probe tip assembly  200  according to a preferred embodiment of the present invention.  FIGS. 3-6  show a probe tip  201  according to a preferred embodiment of the present invention. 
         [0026]      FIG. 1A-1C  show the connector assembly  100  according to a preferred embodiment of the present invention. The connector assembly  100  includes cables  101  that connect connector  102  with a plurality of female connectors  103 . Connector  102  is connected to test equipment (not shown), which is used to test a device to be tested (not shown). The type of connector  102  used with the connector assembly  100  can be varied and will depend upon the type of test equipment used. Although only one connector  102  is shown in  FIG. 1A , any number of connectors  102  can be used. 
         [0027]    Preferably, cables  101  are twinax cables. However, any other suitable type of cable, e.g., coaxial cable or regular cable (a single conductor surrounded an insulator), can also be used. As seen in  FIGS. 1B and 1C , cables  101  include conductors  109  that are surrounded by an inner insulator  108  that is further surrounded by a ground sheath  107  that is further surrounded by an outer insulator  114 . 
         [0028]    Each of the cables  101  is attached to a corresponding circuit board  106 , as best seen in  FIGS. 1B and 1C . The circuit board  106  preferably includes contact pads  112 , traces  113 , a ground pad  110 , and signal pads  111 . The signal pads  111  are connected to corresponding contact pads  112  by corresponding traces  113 , and the ground pad  110  is connected to the remaining contact pad  112  by the remaining trace  112 . 
         [0029]    Preferably, as shown in  FIGS. 1B and 1C , three contact pads  112 , two signal pads  111 , and one ground pad are used. However, the arrangement of contact pads  112 , traces  113 , ground pad  110 , and signal pads  111  can be varied and will depend upon the type of cables used. For example, if coaxial cables are used, it is possible to use two contact pads  112 , one signal pad  111 , and one ground pad. Even if twinax cables are used, it is possible to use different arrangements. For example, instead of having the two contact pads  112  connected to the signal pads  111  located next to each other, it is possible to have the contact pad  112  connected to the ground pad  110  located between the two contact pads  112  connected to the signal pads  111 . 
         [0030]    Preferably, the conductors  109  and the ground sheath  107  are soldered to the signal pads  111  and the ground pad  110 , respectively. However, any other suitable method of attaching the conductors  109  and the ground sheath  107  to the circuit board  106  can be used. 
         [0031]    Connector assembly  100  preferably includes a plurality of female connector  103 . Although eight female connectors  103  are shown in  FIG. 1A , any number of female connectors  103  can be used. Each of the female connectors  103  includes contacts  105  that are attached to corresponding contact pads  112  on the circuit board  106 . The contacts  105  of the female connector  103  include a tail portion  105   a  for attaching to the circuit board  106  and a head portion  105   b  for connecting to another contact, which will be discussed be below. The head portion of the contact  105  is preferably forked for receiving another contact between the forks. However, other suitable arrangements of the contact  105  can also be used. 
         [0032]    Preferably, the contacts  105  are soldered to the corresponding contact pads  112  on the circuit board  106 . However, any other suitable method can be used to attach the contacts  105  to the corresponding contact pads  112  on the circuit board  106 . The contacts  105  are inserted into the cores  115  of the female connector  103 . The number of cores  115  and the number of contacts  105  can be varied and will depend upon the type of cable used. The type of contact  105  can also be varied and will depend upon the type of connector used with the probe tip assembly  200 , discussed below. 
         [0033]    As shown in  FIG. 1A , the circuit board  106  (not seen in  FIG. 1A ) is covered with heat shrink wrap  104  to protect the circuit board  106 . Instead of heat shrink wrap  104 , any other suitable covering can be used to protect the circuit board  106 . 
         [0034]      FIGS. 2A and 2B  show the probe tip assembly  200  according to a preferred embodiment of the present invention. The probe tip assembly  200  includes a probe tip  201  and a male connector  210 . The probe tip  201  includes a flexible circuit board  202  to which the male connector  210  is attached. Preferably, the contacts  211  are soldered to the flexible circuit board  202 . However, any other suitable method can be used to attach the contacts  211  to the flexible circuit board  202 . 
         [0035]    The contacts  211  of male connector  210  are inserted into the cores  115  of the female connector  103  to engage the contacts  105  of the female connector  103  (not shown in  FIGS. 2A and 2B ). Of course, the gender of female connector  103  and male connector  210  can be reversed. That is, a male connector can be attached to circuit board  106 , and a female connector can be attached to flexible circuit board  202 . 
         [0036]    The flexible circuit board  202  preferably includes contact pads  206 , traces  209 , resistor pads  208 , and test pads  204 . As seen in  FIGS. 2A-4 , the resistor pads  208  are arranged into pairs of resistors pads  208 . A resistor  203  is attached to a corresponding pair of resistor pads  208 . The test pads  204  are also arranged into pairs of test pads  204 . The test pads  204  in a pair of test pads  204  are arranged on opposing sides of the flexible circuit board  202 . Some of the traces  209  connect the contact pads  206  with one of the pair of resistor pads  208 , and some of the traces  209  connect the test pads  204  that are located on the same side of the flexible circuit board  202  as the resistor pads  208  with the other of the pair resistor pads  208 . The pair of test pads  204  are electrically connected to each other. It is preferable to cover the traces  209  with a protective layer (not shown). 
         [0037]    An electrical path is provided between corresponding contact pads  206  and test pads  204  via a corresponding resistor  203 . Preferably, the length of the electrical paths between each of the corresponding contact pads  206  and test pads  204  is the same or substantially the same so that the variation of the effect of the probe tip on the monitored and tested electrical signals is minimized. However, it is also possible that the length of the electrical paths between each of the corresponding contact pads  206  and test pads  204  is different. For example, if the flexible circuit board  202  has an L-shape (“right-angled”) (not shown) instead of the substantially rectangular shape shown in  FIGS. 3-5 , then the length of the electrical path between each of the corresponding contact pads  206  and test pads  204  can be varied. Even if the flexible circuit board  202  has an L-shape, it is still possible for the length of the electrical paths between each of the corresponding contact pads  206  and test pads  204  to be the same or substantially the same. 
         [0038]    As shown in  FIGS. 2A ,  3 , and  4 , the contact pads  206 , traces  209 , resistor pads  208 , and test pads  204  of the probe tip  201  are preferably arranged to provide two electrical paths that connect two contact pads  206  to two corresponding test pads  204 . A third contact pad  206  is provided on the flexible circuit board  202  and is connected to the ground sheath  107  (shown in  FIGS. 1B and 1C ). 
         [0039]    Preferably, as shown in  FIGS. 2A and 2B , the flexible circuit board  202  uses three contact pads  206  and two pairs of test pads  204 . The arrangement of the contact pads  206 , traces  209 , resistor pads  208 , and test pads  204  can be varied and will depend upon the type of cables used. For example, if coaxial cables are used, it is possible to use two contact pads  206  and one pair of test pad  204 . Even if twinax cables are used, it is possible to use different arrangements. For example, instead of having the two contact pads  206  connected to the pairs of test pads  204  next to each other, it is possible to have the contact pad  206  connected to the ground sheath  107  between the two contact pads  206  connected to the pairs of test pads  204 . 
         [0040]    Preferably, resistor  203  is a ceramic chip resistor. However, any other suitable resistor can also be used. It is also possible to embed the resistor in the flexible circuit board  202 . No matter what type of resistor is used, it is preferable to locate the resistor as close to the test pad  204  as possible in order to minimize the electrical stub length of the probe tip  201 . This arrangement of the resistor provides a consistently short electrical stub length. In certain applications, it may be desirable to use another type of electrical component, other than a resistor, in place of the resistor  203 . These electrical components can include both passive and active components and can be attached to the surface of the flexible circuit board  202  or can be embedded within the flexible circuit board  202 . 
         [0041]    As seen in FIGS.  2 A and  3 - 5 , the pairs of test pads  204  are connected by a through hole  205  which extends from one side of the flexible circuit board  202  to the other side of the flexible circuit board  202 . The sides of the through holes  205  are provided with a metal layer to ensure that an electrical path is provided between the pairs of test pads  204 . Instead of using through holes  205  to connect the pairs of test pads  204 , it is also possible to use vias. However, the through holes  205  allow greater and faster heat transfer when the probe tip  201  is soldered to a device to be tested (not shown). Typically, a probe tip  202  is placed on the device to be tested, and a soldering iron (not shown) is placed on the test pads  204  that are located on the same side of the flexible circuit board  205  as the contact pads  206 . This enables each of the test pads  204  not located on the same side of the flexible circuit board  205  as the contact pads  206  to be soldered to the device to be tested at the same time. If the probe tip  201  is soldered to an electrical component (not shown) that is soldered to the device to be tested, it may be possible not to add any more solder and to use the solder attaching the electrical component to the device to be tested. The probe tip assembly  200  can be re-used by de-soldering the probe tip  201  from the device to be tested. 
         [0042]    Preferably, the portion of the flexible circuit board  202  with the contact pads  206  is provided with a stiffener  207 . The stiffener  207  and the contact pads  206  are provided on opposing sides of the flexible circuit board to assist in attaching the contacts  211  to the flexible circuit board  202 . 
         [0043]    It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variances that fall within the scope of the appended claims.