Abstract:
The traditional device interface board is replaced by a number of smaller strips containing one or more electrical components for interfacing the device under test and the test head. The device interface modules may mount to a stiffening member having a back bone and multiple ribs running through the stiffening member. The device interface strips can create a lattice-like structure for the interface circuitry. Individual circuits may be disposed on the interface strips to perform functionality relating to the device under test and/or the test head.

Description:
FIELD OF THE INVENTION 
     The present invention relates to automated testing equipment, more specifically a device interface board and method for automatic test equipment. 
     BACKGROUND OF THE INVENTION 
     Automatic test equipment (“ATE”) has been known in the art for several years. Automating the testing procedures for circuit boards and electronic devices expedites the testing process and allows for greater production of tested electronic devices. When testing an instrument, an interface assembly is docked to a test head using methods well known in the art. The interface assembly contains a device interface board (“DIB”) attached to a stiffening member. An instrument interface block makes an electrical connection to the DIB. The DIB is a printed circuit board (“PCB”) that is pre-designed and manufactured specifically for the instrument to be tested and the test that is to be run. 
     For every configuration and every instrument to be tested, a unique DIB is needed with circuitry unique to that configuration or instrument and device to be tested. The requirement of producing new boards for every configuration drastically increases the cost of testing and developing electrical devices. The development of a DIB requires a great amount of time and energy into the design, manufacture, and testing of the board itself. The replacement of the DIB in the probe interface during testing is also time consuming. 
     SUMMARY OF THE INVENTION 
     Various embodiments of the present invention provide for a modularized device and method for automatic testing equipment (“ATE”). The traditional device interface board (“DIB”) is replaced by a number of smaller strips containing circuitry networks for interfacing the instrument interface block and the test head. An example of the present invention modularizes the DIB and its connections, providing for the easy reconfiguration of testing instruments without the cost of creating entirely new DIB boards for every instrument or test configuration. The device interface modules, or strips, mount to a stiffening member having a back bone and multiple ribs running through the stiffening member. The backbone bisects the length of the stiffening member; the ribs run parallel to the backbone. The device interface strips mount to the backbone extending perpendicularly across the ribs creating a lattice-like structure for the interface circuitry. Individual circuits are disposed on the interface strips to lie between mounting points on the strips and the backbone and ribs of the stiffening member. 
     Another illustrative embodiment provides for a method of testing electrical equipment through affixing a number of device interface strips to a stiffening member. The stiffening member is then coupled to a test head. A device under test, through an electrically coupled instrument interface block, interfaces with the test head through the circuitry of the device interface strips. 
     In yet another embodiment, the device interface strips are coupled to the stiffening member through a communication board interconnecting the device interface strips. The backbone of the stiffening member serves as a docking center through which the interface strips may communicate to the test head through a series of electrical contacts. Power may also be distributed from the various utility power supplies to the circuitry on the interface strips. Control signals can also be sent between the device interface strips through a matrix control circuit on the communication board allow for a generic interface bas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the present invention will be more fully understood from the following detailed description of illustrative embodiments, taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view of the device interface strips mounted on the stiffening member in accordance with an embodiment of the present invention; 
         FIG. 2A  is a top-down view of an arrangement of device interface strips in accordance with one embodiment of the present invention; 
         FIG. 2B  is an enlarged view of a device interface strip in accordance with one embodiment of the present invention; 
         FIG. 3  depicts a top-down view of a stiffening member in accordance with an embodiment of the present invention; 
         FIG. 4A  is a top-down view of a communication board and stiffening member in accordance with one embodiment of the present invention; 
         FIG. 4B  is a depicts an exploded view of a communication board and stiffening member in and accordance with one embodiment of the present invention; and 
         FIG. 5  depicts a flow diagram of a testing process in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention can provide a reliable and cost effective testing interface for electronic equipment. The modularization of the device interface circuitry greatly eases the interchangeability of instruments as well as drastically reducing cost in the manufacture and design time of automatic test equipment (“ATE”). Various embodiments of the present invention may also reduce the time-to-market by minimizing or eliminating a need to customize test boards, which is typically a very expensive and time consuming effort. 
     Turning now to  FIG. 1 , a perspective view of one embodiment of a device interface assembly  100  in accordance with the present invention is shown. A stiffening member  102  is shown with device interface strips  104  mounted to the stiffening member  102 . In the illustrative example, the sixteen inch by sixteen inch square stiffening member  102  can accommodate twenty-six distinct device interface strips  104 . Each device interface strip  104  contains one or more electrical components for signal transmission. Examples of an electrical component can include, without limitation, a trace wire, a loop-back circuit, an integrated circuit, etc. Each device interface strip  104  can contain mounting holes  106  for affixing to the stiffening member  102 . The device interface strips  104  contain alignment holes  108  at both ends of the strip to receive the precision alignment pins (not shown) of the stiffening member  102 . After the device interface strips  104  are aligned with the alignment holes  108  engaging the precision alignment pins, screws are used to secure the device interface strips  104  to the stiffening member  102 . The stiffening member  102  also has frame mounting holes  110  along the outer edge to securely attach the stiffening member  104  to a frame. The frame then securely attaches to the test head. 
     The device interface strips  104  represent the modularization of the traditional device interface boards common in the art. Traditional ATE probe assemblies required the design, manufacture, and installation of distinct device interface boards for every instrument used and every tested device configuration required. A typical device interface board consists of 20-40 layers of complex printed circuit board technology, requiring substantial cost and time to produce. Embodiments of the present invention can provide for complete modularization of the device interface board. Segmenting the board into strips allows for easy interchangeability and configuration of the probe interface. The individual strips can be interconnected through wires or ribbon cables to maintain intercommunication throughout all the circuits on the strips. Replacement of a testing device requires only a change to the corresponding device interface strip  104  instead of replacing the entire device interface board. The addition, removal or substitution of a device interface strip  104  can be accomplished by the removal of the fastening structure, here six mounting screws, replacing the strip  104  with the desired strip, and re-fastening the mounting screws. Additionally, the manufacture of the device interface strips  104  involves only a fraction of the cost and time of an entire device interface board. 
     Although the examples explained above detail screw attachments and engagements between the components of the system, one skilled in the art should recognize that any method of securely fastening the components together, e.g. snap fit, clamp fit, button fit, quick-release, etc., does not deviate from the scope of the present invention. 
     Turning to  FIG. 2A , an illustrative layout  200  of the device interface strips  104  is shown in accordance with one embodiment of the present invention. The layout  200  utilizes twenty-six device interface strips  104  with mounting holes  106  along each of the device interface strips  104  and two additional mounting holes  107  located at one end. The two additional mounting holes  107  at the end of the device interface strip  104  affix to a backbone on the stiffening member (not shown). The device interface strips  104  may have alignment holes  108  at both ends to engage alignment pins of the stiffening member. While the illustrated embodiment shows device interface strips with alignment holes centered at the ends of the strip, one skilled in the art should appreciate any alignment pattern or number of mounting holes, such as off-centered alignment holes may be implemented without deviating from the spirit of the invention. 
     With reference to  FIG. 2B , alternative embodiments of device interface strips  104 A,  104 B are illustrated having at least one conductive edge  105 . A device interface strip  104 A is illustrated as having two conductive edges, while device interface strip  104 B is illustrated as having a single conductive edge. Conductive edges may be formed by a wide variety of methods, such as, but not limited to, plating the edge with copper, nicked or gold. A conductive grounding insert  201  may be placed between two conductive edges to provide an electrically conductive path between neighboring device interface strips  104 A,  104 B. Examples of conductive grounding inserts can include, but are not limited to, a conductive foil and a flexible corrugated metal sheet or film. In one example, the grounding insert can provide a ground path between neighboring device interface strips. 
     Turning now to  FIG. 3 , a top-down view of an example of a stiffening member  102  in accordance with one embodiment of the present invention is shown. The stiffening member  102  has a central backbone  322  and a series of ribs  324 - 329  running parallel to the backbone  322 . The backbone  322  is a central mounting point for the device interface strips (not shown). Ribs  324 - 329  in this embodiment are mounting points and support structures for the device interface strips. The device interface strip may be supported by pads  342  on each rib  324 - 329  when affixed to the stiffening member  102 . The ribs  324 - 329  of the stiffening member  102  create sidewalks for the segmentation of the signal pads of the device interface circuitry. 
     The device interface strips are disposed on the stiffening member extending from the backbone  322  to the edge of the stiffening member  102 , substantially perpendicular to the backbone  322  and the ribs  324 - 329 . Precision alignment pins  338  are spaced along the top and bottom edges of the stiffening member  102  as well as along the backbone  322 . The alignment pins  338  engage the alignment holes of the device interface strips during assembly. The backbone  322  and the ribs  324 - 329  have screw holes  340  that align with the mounting holes of the device interface strips. Upon assembly the device interface strip is placed over the alignment pins  338  and screws affix the strip to the stiffening member  102  through the mounting holes and screw holes  340 . 
     The stiffening member  102 , in this example, is approximately sixteen inches by sixteen inches square with an internal lattice structure creating a series of open passages that may be used to pass wires or locate circuit components. As used herein, the term “sidewalk” is used to refer to each passage row. Sidewalk one  330 ,  331  is the row defined by the backbone  322  and the first rib  324 ,  325  to either side of the backbone  322 . Sidewalk one  330 ,  331  is typically reserved for high performance instruments. The circuitry on the device interface strips for these high performance instruments overlaps the area defined as sidewalk one. Sidewalk two  332 ,  333  is defined by the next outer ribs  326 ,  327 ; sidewalk three  334 ,  335  is defined by the next outer ribs  328 ,  329 ; and sidewalk four  336 ,  337  is defined by the outer ribs  328 ,  329  and the outer edge of the stiffening member  102 . The circuitry of the device interface is designed such that the circuitry of the instruments with the highest performance are disposed closest to the center of the stiffening member  102  and the circuitry of the lowest performance instruments is to the outer sidewalk four  336 ,  337 . 
     While the embodiments described herein contain a substantially rectangular stiffening member with parallel ribs extending the length of the stiffening member, one skilled in the art should appreciate that any shape, e.g., circular, oval, cross, pentagonal, etc. can be implemented in the form of a stiffening member may be implemented without deviating from the scope of the invention. 
     Additionally, while the embodiments described herein contain a backbone and ribs that extend the length of the rectangular stiffening member and are substantially parallel to each other, one skilled in the art should recognize that any arrangement of the backbone, e.g., circular ring, rectangular center, etc., and ribs, e.g. radial, non-parallel, skewed, cross-hatch, concentric rings, concentric rectangles, etc., may be implemented without deviating from the scope of the invention. 
     Additionally, while the examples contained herein depict a stiffening member with a single backbone, one skilled in the art should recognize that any number of backbones may be implemented without deviating from the spirit of the present invention. 
     While the examples explained above depict a sixteen by sixteen inch square, 24 slot stiffening member, one skilled in the art should recognize that using other size stiffening members commonly used in the art would not deviate from the teachings of the present invention. 
     Turning now to  FIG. 4A  and  FIG. 4B , an embodiment of the present invention is shown in which one or more communication boards  448  are provided for communication with one or more device interface strips  404 . The communication board can eliminate cumbersome wires attached to the device interface strips  404 , while maintaining flexibility of intercommunication with the circuitry between the device interface strips  404 . In the present example, the communication board  448  is disposed on both sides of the backbone  422  of the stiffening member. The communication board  448  contains electrical connectors that couple with the connectors of the device interface strip  404 . The end of the device interface strip  404  that mounts to the communication board  448  contains a series of electrical connectors connected to the circuitry of the device interface strip  404 . 
     Because the communication board  448  is mounted to the stiffening member, mounting of one end of the device interface strips  404  to the communication board provides a physical mount for one end of the device interface strip. Optionally, the device interface strips  404  can be physically directly mounted to the stiffening member  402 , such as at the backbone  422 , with additional electrical connectors providing communication with the communication board  448 . The device interface strips can contain alignment holes  408  for engagement with the alignment pins  438  on the backbone  422 . The stiffening member  402  may be electrically coupled to the test head through the electrical connectors on the backbone  422 , such as for grounding and/or for other electrical communications. 
     While the embodiment depicted in  FIG. 4A  shows two communication boards  448  on either side of the backbone  422 , one skilled in the art should recognize that any number of communication boards may be implemented without deviating from the scope of the present invention, e.g. a single board spanning the backbone or a series of independent or interconnected communication boards disposed along or near the backbone. 
     In the embodiment shown in  FIG. 4B , four distinct busses are implemented into the communication board  448 . The communication board  448  has a non-volatile random access memory (“NVRAM”) bus  450  for communicating with the NVRAM modules on the device interface strip  404 . In the present embodiment, there is one NVRAM per slot available on the stiffening member  402  and a NVRAM located on the communication board (not shown). The communication board  448  also has a utility bus  452  for communication with a transceiver (not shown) located on the device interface strip  404 . In this embodiment, four utility data bits (“UDBs”) are distributed to each device interface strip  404  through the utility bus  452 . The transceiver is controlled by two bits that control whether the transceiver is latching data, reading a support board, or being by-passed. A power bus  454  may be used to provide a connection to utility power supplies. Voltage supplies of 3.3 Volts (“V”), 5 V, 15 A V and 15 B V can be supplied through the power bus  454 . Additionally, in this embodiment, an extra bus  456  is provided for possible expansion of any of the circuitry on the device interface board  404 . This extra bus  456  is four bits wide and allows slot to slot connectivity between any of the device interface strips  404  attached to the stiffening member. The device interface strip  404  contains a NVRAM bus connector  451 , a utility bus connector  453 , a power bus connector  455  and an extra bus connector  457  are aligned such that when the device interface strip  404  is attached to the stiffening member, electrical connections are made through the communication board  448 . The device interface strip  404  may optionally have one or more conductive edges  405 . 
       FIG. 5  shows a method of testing of equipment automatically  500  in accordance with one embodiment of the present invention. The device interface strips are securely affixed  560  to a stiffening member. The stiffening member is then attached  562  to a frame for mounting on a test head. The device interface strips are electronically coupled to the test head and a controller for driving the testing. The device interface strips are then electronically coupled  564  to the instrument interface and the device under test. When electrical connection is made from the test head to the device under test, the specific test is implemented. If the test head or interface circuitry needs to be reconfigured before the next test  566 , the appropriate device interface strips can be substituted, added or removed  570 . After the configuration changes are made to the device interface circuitry, the stiffening member and frame are re-attached to the test head  562 . If no configuration changes are needed after the test is complete, the device under test is changed  568  and the test is run again  564 . 
     The present application incorporates by reference in its entirety, the application entitled Automatic Test Equipment Instrument Card and Probe Cabling System and Apparatus, filed on even date herewith. 
     In addition to the description of specific, non-limited examples of embodiments of the invention provided herein, it should be appreciated that the invention can be implemented in numerous other applications involving the configurations of ATE. Although the invention is described hereinbefore with respect to illustrative embodiments thereof, it will be appreciated that the foregoing and various other changes, omissions and additions in the form and detail thereof may be made without departing from the spirit and scope of the invention.