PATENT DOCUMENT

Publication Number: US-9285419-B2
Application Number: US-201113173387-A
Country: US
Kind Code: B2

Title: Test probe alignment structures for radio-frequency test systems

Abstract:
Electronic devices may be tested using a test station with a test fixture. The test fixture may include a first holding structure in which a device under test may be placed and a second holding structure for supporting test probes. The second holding structure may be mated with a test probe alignment structure during test station setup operations. The test probe alignment structure may include registration features configured to set the relative position of the first and second holding structures to a known configuration and may include test probe alignment features that can be used to correctly position the placement of the test probes. If at least one of the test probes is not sufficiently aligned to its corresponding alignment feature, the test probe alignment structures will not be able to engage properly with the second holding structure, and the position of the problematic test probe may be adjusted accordingly.

Claims:
What is claimed is: 
     
       1. A method for configuring at least one test probe that is located at an adjustable position within a test fixture in a radio-frequency test station, comprising:
 placing a test probe alignment structure into alignment with the test fixture; and 
 while the test probe alignment structure and the test fixture are aligned, adjusting the position of the test probe with respect to the test fixture and the test probe alignment structure so that the test probe aligns with at least one corresponding test probe alignment feature in the test probe alignment structure, wherein adjusting the position of the test probe with respect to the test fixture and the test probe alignment structure so that the test probe aligns with at least one corresponding test probe alignment feature in the test probe alignment structure comprises moving the test probe horizontally within a test probe adjustment region, with respect to the test fixture and the test probe alignment structure, so that the test probe protrudes vertically into the at least one corresponding test probe alignment feature in the test probe alignment structure. 
 
     
     
       2. The method defined in  claim 1  wherein placing the test probe alignment structure into alignment with the test fixture comprises registering the test probe alignment structure with the test fixture using mating registration features in the test probe alignment structure and the test fixture. 
     
     
       3. The method defined in  claim 2  further comprising:
 following adjustment of the test probe into alignment with the at least one corresponding test probe alignment feature, securing the test probe to the test fixture using an attachment mechanism selected from the group consisting of: welds, screws, clamps, levers, adhesive, and solder. 
 
     
     
       4. The method defined in  claim 2  wherein a first portion of the mating registration features in the test fixture comprises at least one protruding member, wherein a first portion of the mating registration features in the test probe alignment structure comprises at least one corresponding recess, and wherein registering the test probe alignment structure with the test fixture comprises mating the at least one protruding member of the test fixture with the at least one corresponding recess in the test probe alignment structure. 
     
     
       5. The method defined in  claim 4  wherein a second portion of the mating registration features in the test fixture comprises at least one recess, wherein a second portion of the mating registration features in the test probe alignment structure comprises at least one corresponding protruding member, and wherein registering the test probe alignment structure with the test fixture further comprises mating the at least one recess of the test fixture with the at least one corresponding protruding member in the test probe alignment structure. 
     
     
       6. The method defined in  claim 2  wherein a portion of the mating registration features in the test fixture comprises at least one recess, wherein a portion of the mating registration features in the test probe alignment structure comprises at least one corresponding protruding member, and wherein registering the test probe alignment structure with the test fixture further comprises mating the at least one recess of the test fixture with the at least one corresponding protruding member in the test probe alignment structure. 
     
     
       7. The method defined in  claim 1  wherein the at least one corresponding test probe alignment feature comprises a recess within a block of material, and wherein adjusting the position of the test probe within the test fixture so that the probe aligns with the at least one corresponding test probe alignment feature in the test probe alignment structure comprises adjusting the position of the test probe until the test probe is aligned with the recess within the block of material. 
     
     
       8. A method for determining whether a radio-frequency test probe is located at a proper position within a test fixture, wherein the test fixture includes registration features corresponding to registration features in a test probe alignment structure, comprising:
 attempting to mate the test probe with a test probe alignment feature in the test probe alignment structure while mating the registration features of the test fixture with the registration features of the test probe alignment structure; 
 following an unsuccessful attempt at mating the test probe with the test probe alignment feature while mating the registration features of the test fixture with the registration features of the test probe alignment structure, adjusting where the test probe is positioned with respect to the test fixture and the test probe alignment structure; 
 following successful mating of the test probe with the test probe alignment feature while mating the registration features of the test fixture with the registration features of the test probe alignment structure, removing the test probe alignment structure from the test fixture; 
 inserting at least a given one of the registration features of the test fixture through an opening in a device under test; and 
 while the given one of the registration features is within the opening of the device under test, testing the device under test using the radio-frequency test probe. 
 
     
     
       9. The method defined in  claim 8  wherein adjusting where the test probe is positioned with respect to the test fixture and the test probe alignment structure comprises adjusting the test probe to the proper position within the test fixture so that the test probe is in alignment with the test probe alignment feature. 
     
     
       10. The method defined in  claim 9  further comprising:
 following adjustment of the test probe into alignment with the test probe alignment feature, securing the test probe to the test fixture such that the test probe does not move with respect to the test fixture using an attachment mechanism selected from the group consisting of: welds, screws, clamps, levers, adhesive, and solder.

Description:
BACKGROUND 
     This relates to testing and, more particularly, to testing of electronic device structures. 
     Electronic devices such as computers, cellular telephones, music players, and other electronic equipment are often provided with wireless communications circuitry. In a typical configuration, the wireless communications circuitry includes an antenna that is coupled to a transceiver on a printed circuit board using radio-frequency cables and connectors. Many electronic devices include conductive structures with holes, slots, and other shapes. Welds and springs may be used in forming connections between such types of conductive structures and electronic device components. 
     During device assembly, workers and automated assembly machines may be used to form welds, machine features into conductive device structures, connect connectors for antennas and other components to mating connectors, and otherwise form and interconnect electronic device structures. If care is not taken, however, faults may result that can impact the performance of a final assembled device. For example, a metal part may not be machined correctly or a connector may not be seated properly within its mating connector. 
     Methods have been developed for detecting such types of manufacturing defects during device assembly. Testing for manufacturing defects typically involves transmitting radio-frequency test signals to the electronic device structures using a test station having a test fixture and radio-frequency test probes. The electronic device structures are placed within the test fixture. The radio-frequency test probes are used to contact the electronic device structures at desired locations while the electronic device structures are secured within the test fixture. The accuracy and precision with which the radio-frequency test probes make contact to the desired locations on the electronic device structures may impact the accuracy and consistency of test results gathered across different test stations. 
     It would therefore be desirable to be able to provide improved ways for accurately positioning the radio-frequency test probes in each test station. 
     SUMMARY 
     Electronic device structures under test may be tested using a radio-frequency test station. The device structures under test (sometimes referred to as a DUT) may be partially-assembled devices or fully-assembled finished products. 
     The test station may include a test host, a test unit, and a test fixture. The test fixture may include a test probe holding structure and a DUT holding structure. 
     Radio-frequency test probes may be supported using the test probe holding structure. The radio-frequency test probes may be coupled to the test unit. The test unit may be configured to send and receive radio-frequency test signals to and from the device structures under test. The test results gathered using the test unit may be conveyed to the test host for further analysis. 
     During testing, a DUT may be placed in the DUT holding structure. The DUT may then be brought into contact with the test probes while the DUT is secured within the DUT holding structure. The location at which the test probes contact the DUT has to be sufficiently precise to provide accurate test results. 
     A test probe alignment structure (sometimes referred to as a gauge block) may be used to align the test probes to desired positions. The gauge block may include registration features (e.g., vertical registration features configured to set the vertical distance between the gauge block and the test probe holding structure to a known value and horizontal registration features configured to minimize the horizontal offset between the gauge block and the test probe holding structure) and test probe alignment features. The test probe alignment features may serve as mechanical guiding members for correctly positioning the different test probes. 
     During test station setup procedures, the gauge block may be used to mate with the test probe holding structure. The gauge block may or may not be secured within the DUT holding structure during test station setup/validation operations. The positions of each test probe may be adjusted manually or using computer-controlled positions until the each of the test probes are properly aligned to its corresponding alignment feature. When all the test probes have been aligned, the test probes may be anchored using screws, levers, clamps, welds, adhesive, solder, or other suitable attachment mechanisms for securing the placement of the test probes. 
     The gauge block may also be used during test station validation procedures to check whether a test station has properly aligned probes. For example, test station personnel may attempt to mate a gauge block with the test probe holding structure in a test station. If the gauge block is able to properly mate with the test probe holding structure (i.e., if the test probes are sufficiently aligned to the corresponding test probe alignment features), no adjustment needs to be made to the test probes. If the gauge block is unable to properly mate with the test probe holding structure (i.e., if at least one test probe is sufficiently offset from its corresponding test probe alignment feature), the problematic test probe(s) may be repositioned for proper alignment. 
     Further features of the present invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device that may be tested in accordance with an embodiment of the present invention. 
         FIG. 2  is a top view of illustrative device structures under test of the type shown in  FIG. 1  showing the locations of gaps in a peripheral conductive housing member in accordance with an embodiment of the present invention. 
         FIG. 3  is a block diagram of a test station for testing device structures under test in accordance with an embodiment of the present invention. 
         FIG. 4  is a block diagram showing how a test station may be set up using test probe alignment structures in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram showing test probe alignment structures having a test probe alignment feature configured to mate with a corresponding test probe in a test probe holding structure in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of an illustrative test station for testing device structures under test in accordance with an embodiment of the present invention. 
         FIG. 7  is a perspective view of an illustrative holding structure in which device structures under test may be inserted in accordance with an embodiment of the present invention. 
         FIG. 8  is a perspective view of illustrative device structures under test showing locations of possible probe points in accordance with an embodiment of the present invention. 
         FIG. 9A  is a cross-sectional side view of an illustrative test probe holding structure in accordance with an embodiment of the present invention. 
         FIG. 9B  is a bottom view of the test probe holding structure of  FIG. 9A  in accordance with an embodiment of the present invention. 
         FIG. 10  is an exploded perspective view of illustrative test probe alignment structures that may be mated with corresponding test probes in a test probe holding structure of the type shown in  FIGS. 9A and 9B  in accordance with an embodiment of the present invention. 
         FIGS. 11 and 12  are perspective views of illustrative test probe alignment structures in accordance with an embodiment of the present invention. 
         FIG. 13  is a cross-sectional view showing a test probe mated with a corresponding test probe alignment feature in accordance with an embodiment of the present invention. 
         FIG. 14  is a flow chart of illustrative steps involved in initially setting up a test station in accordance with an embodiment of the present invention. 
         FIG. 15  is flow chart of illustrative steps for determining whether a test station has properly aligned test probes in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be assembled from conductive structures such as conductive housing structures. Electronic components such as speakers, microphones, displays, antennas, switches, connectors, and other components may be mounted within the housing of an electronic device. Electronic device structures such as these may be assembled using automated manufacturing tools. 
     Examples of automated manufacturing tools include automated milling machines, robotic pick-and-place tools for populating printed circuit boards with connectors and integrated circuits, computer-controlled tools for attaching connectors to each other, and automated welding machines (as examples). Manual assembly techniques may also be used in assembling electronic devices. For example, assembly personnel may attach a pair of mating connectors to each other by pressing the connectors together. 
     Regardless of whether operations such as these are performed using automated tools or manually, there will generally be a potential for error. Parts may not be manufactured properly and faults may arise during assembly operations. It may therefore be desirable to test an electronic device (e.g., a partially-assembled or fully-assembled electronic device) to detect for the presence of manufacturing defects during device production. For example, an electronic device (sometimes referred to as a device under test, a “DUT,” or device structures under test) may be tested to determine whether its wireless circuitry satisfies performance criteria, to determine whether its conductive housing structure has properly formed gaps, to determine whether a first conductive component is welded properly to a second conductive component, to determine whether a pair of mating connectors are properly connected, etc. 
     An illustrative electronic device of the type that may be provided with conductive electronic device structures such as a peripheral conductive housing member that forms part of one or more antennas is shown in  FIG. 1 . Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a cellular telephone, a media player, etc. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may, for example, be a touch screen that incorporates capacitive touch electrodes. Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electronic ink elements, liquid crystal display (LCD) components, or other suitable image pixel structures. A cover glass layer may cover the surface of display  14 . Buttons such as button  19  may pass through openings in the cover glass. 
     Housing  12  may include structures such as housing member  16 . Member  16  may run around the rectangular periphery of device  10  and display  14 . Member  16  or part of member  16  may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or helps hold display  14  to device  10 ). Member  16  may also, if desired, form sidewall structures for device  10 . 
     Member  16  may be formed of a conductive material and may therefore sometimes be referred to as a peripheral conductive housing member or conductive housing structures. Member  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming member  16 . 
     It is not necessary for member  16  to have a uniform cross-section. For example, the top portion of member  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. If desired, the bottom portion of member  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). In the example of  FIG. 1 , member  16  has substantially straight vertical sidewalls. This is merely illustrative. The sidewalls of member  16  may be curved or may have any other suitable shape. In some configurations (e.g., when member  16  serves as a bezel for display  14 ), member  16  may run around the lip of housing  12  (i.e., member  16  may cover only the edge of housing  12  that surrounds display  14  and not the rear edge of the sidewalls of housing  12 ). 
     Display  14  may include conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. Housing  12  may include internal structures such as metal frame members, a planar housing member (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a sheet metal structure that is welded or otherwise connected between the opposing right and left sides of member  16 ), printed circuit boards, and other internal conductive structures. These conductive structures may be located in center of housing  12  (as an example). 
     In regions  20  and  22 , openings may be formed between the conductive housing structures and conductive electrical components that make up device  10 . These openings may be filled with air, plastic, and other dielectrics. Conductive housing structures and other conductive structures in device  10  may serve as a ground plane for the antennas in device  10 . The openings in regions  20  and  22  may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element from the ground plane, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . 
     Portions of member  16  may be provided with gap structures  18 . Gaps  18  may be filled with dielectric such as polymer, ceramic, glass, etc. Gaps  18  may divide member  16  into one or more peripheral conductive member segments. There may be, for example, two segments of member  16  (e.g., in an arrangement with two gaps), three segments of member  16  (e.g., in an arrangement with three gaps), four segments of member  16  (e.g., in an arrangement with four gaps, etc.). The segments of peripheral conductive member  16  that are formed in this way may form parts of antennas in device  10  and may therefore sometimes be referred to as conductive antenna structures. 
     A top view of an interior portion of device  10  is shown in  FIG. 2 . If desired, device  10  may have upper and lower antennas (as an example). An upper antenna such as antenna  40 U may, for example, be formed at the upper end of device  10  in region  22 . A lower antenna such as antenna  40 L may, for example, be formed at the lower end of device  10  in region  20 . The antennas may be used separately to cover separate communications bands of interest or may be used together to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme. 
     Antenna  40 L may be formed from the portions of midplate  58  and peripheral conductive housing member  16  that surround dielectric-filled opening  56 . Antenna  40 L may have associated signal and ground feed terminals at locations  54  and  52 , respectively. Other feed arrangements may be used if desired. During testing, test equipment may be used to make direct contact with these device structures precisely at locations  54  and  52  to perform radio-frequency testing (as an example). The positioning of the test equipment may be controlled so that proper contact is made at the desired locations. The arrangement of  FIG. 2  is merely illustrative. 
     Antenna  40 U may be formed from the portions of midplate  58  and peripheral conductive housing member  16  that surround dielectric-filled opening  60 . Member  16  may have a low-band segment LBA that terminates at one of gaps  18  and a high-band segment HBA that terminates at another one of gaps  18 . Antenna  40 U may have associated signal and ground feed terminals at locations  66  and  64 , respectively. During testing, a tester may be used to make physical contact with these device structures precisely at locations  66  and  64  to perform radio-frequency testing (as an example). Conductive member  68  may span opening  60  to form an inverted-F antenna short-circuit path. Segments LBA and HBA may form low-band and high-band cellular telephone inverted-F antennas (as an example). 
     Test equipment may be used to test electronic device  10  during production testing operations. The electronic device structures being tested may sometimes be referred to as device structures under test. The device structures under test may or may not resemble a finished product. The device structures under test may include portions of a functional electronic device such as conductive housing structures, electronic components such as microphones, speakers, connectors, switches, printed circuit boards, antennas, parts of antennas such as antenna resonating elements and antenna ground structures, metal parts that are coupled to each other using welds, assemblies formed from two or more of these structures, or other suitable electronic device structures. These test structures may be associated with any suitable type of electronic device such as a cellular telephone, a portable computer, a music player, a tablet computer, a desktop computer, a display, a display that includes a built-in computer, a television, a set-top box, or other electronic equipment. 
       FIG. 3  is a diagram of device structures under test  10 ′ being tested using a test station having test fixture  133 . Test fixture  133  may include radio-frequency (RF) test probes configured to transmit and received RF test signals to and from device structures under test  10 ′. The test probes may be wired test probes for use in conducted testing (i.e., test probes configured to make direct contact with conductive portions of structures  10 ′), wireless test probes for use in radiated testing, or other types of radio-frequency test probes. As shown in  FIG. 3 , the test station may also include a test unit  104  to which the test probes may be coupled. Test unit  104  may serve as a signal generator for outputting radio-frequency test signals to the test probes and a radio-frequency tester for receiving and analyzing corresponding test signals received from the test probes. 
     The relative position of the test probes in test fixture  133  with respect to device structures under test  10 ′ may affect the accuracy of the test results gathered using different test stations. Regardless of whether wired test probes or wireless test probes are used during testing, it may be desirable for the placement of the test probes in test fixture  133  to be consistent across the different test stations. This may be accomplished through the use of test probe alignment structures such as test probe alignment structures  300  (see, e.g.,  FIG. 4 ). As shown in  FIG. 4 , test probe alignment structures  300  may be mated with the test probes in test fixture  133  to check whether the position of each test probe is satisfactory relative to a reference test probe configuration (e.g., test probe alignment structures  300  may serve as a known reference to which the test probes in each test fixture  133  are aligned). 
     Test probe alignment structures  300  may, for example, be used to set up each test station during initial bring-up, to determine whether a test station is properly set up (sometimes referred to as “go/no-go” checking), etc. At least one instance of test probe alignment structures  300  may be mated with multiple test stations to set up each test station with the desired (reference) test probe configuration. If desired, multiple copies of test probe alignment structures  300  may also be used to set up the different test stations. 
       FIG. 5  is a diagram showing one arrangement in which test probe alignment structures  300  can be used to properly align a test probe in a test fixture. Test fixture  133  may include a test probe holding structure  134  configured to support at least one test probe  128  and may include an associated test probe adjustment structure  131  configured to adjust the position of test probe  128  within test probe holding structure  134 . Test probe holding structure  134  may also include first and second registration features  151  (as an example). The distance between first and second registration features  151  is known and fixed (i.e., registration features  151  on test probe holding structure  134  are manufactured precisely so their locations are predictable). 
     As shown in  FIG. 5 , test probe alignment structures  300  (sometimes referred to as a gauge block) may include first and second registrations features  153  corresponding to first and second registration features  151  associated with test probe holding structure  134 . As with registration features  151 , the distance between first and second registration features  153  is known and fixed (i.e., registration features  153  on gauge block  300  are manufactured precisely so their locations are predicable). Mating registration features  151  and  153  may be any suitable type of engagement features that can accurately set the relative position of gauge block  300  and test probe holding structure  134  when they are in the mated state (e.g., to precisely set the vertical distance between block  300  and structure  134  and to precisely set the horizontal orientation of gauge block  300  with respect to structure  134 ). 
     The position of test probe  128  in holding structure  134  may be adjusted using test probe adjustment structure  131 . Test probe adjustment structure  131  may be controlled manually or using a computer. Test probe  128  may include at least one conductive pin such as pin  130 . During initial test station bring-up procedures, the position of test probe  128  may be imprecise and may vary from station to station (e.g., distances d 1  and d 2  between test probe  128  and registration features  151  may be incorrect/misaligned). 
     To ensure precise and accurate alignment of test probe  128  in test probe holding structure  134 , gauge block  300  may include a test probe alignment feature  129  (e.g., a recessed portion for receiving probe pin  130 ) formed in its surface. The position of test probe alignment feature  129  in gauge block  300  may be accurate and consistent with a master reference configuration (e.g., distances d 1 ′ and d 2 ′ between alignment feature  129  and registration features  153  may be correct). Pin  130  and corresponding alignment feature  129  may mate properly only if test probe  128  is properly aligned. For example, if test probe  128  is horizontally offset from its desired position, pin  130  will not fit properly into recessed portion  129  and gauge block  300  will not be able to mate properly with the test fixture. If desired, gauge block  300  may include more than one test probe alignment feature  129  for use in aligning multiple test probes in test fixture  133 . 
     During device assembly operations, many electronic devices (e.g., hundreds, thousands or more of DUTs  10 ) may be tested in a test system such as test system  100  of  FIG. 6 . Test system  100  may include test accessories, computers, network equipment, tester control boxes, cabling, test chambers, and other test equipment for transmitting and receiving radio-frequency test signals and gathering test results. Test stem  100  may, for example, be used to determine whether manufacturing/assembly defects are present in DUT  10  by measuring complex reflection and forward transfer coefficients, to determine whether wireless circuitry in DUT  10  satisfies performance criteria during protocol-compliant and/or non-protocol compliant testing, etc. Test system  100  may include multiple test stations such as test stations  102 . There may, for example, be  80  test stations  102  at a given test site. In general, test system  100  may include any desired number of test stations to achieve desired test throughput. 
     Each test station  102  may include a test unit such as test unit  106  and a test host such as test host  104  (e.g., a personal computer). At least some of test stations  102  may be connected to computing equipment  108  via path  114 . Computing equipment  108  may include storage equipment on which a database  110  is stored. Test results gathered using test unit  106  may be stored in database  110 . Test unit (tester)  106  in each test station  102  may be a radio communications tester of the type that is sometimes referred to as a test box or a radio communications tester. Test unit  106  may be used to perform radio-frequency signaling tests for a variety of different radio-frequency communications bands and channels. 
     Test unit  106  may be operated directly or via computer control (e.g., when test unit  106  receives commands from test host  104 ). When operated directly, a user may control test unit  106  by supplying commands directly to the test unit using the user input interface of the test unit. For example, a user may press buttons in a control panel  118  on the test unit while viewing information that is displayed on a display  116  in the test unit. In computer controlled configurations, a test host such as computer  104  (e.g., software running autonomously or semi-autonomously on the computer) may communicate with the test unit (e.g., by sending and receiving data over a wired path  112  or a wireless path between the computer and the test unit). 
     Test unit  106  may be a multiport test box (as an example). As shown in  FIG. 6 , test unit  106  may have at least a first port  120 - 1  and a second port  120 - 2  to which RF cables may be connected. In the example of  FIG. 6 , first RF cable  122 - 1  may have a first end that is connected to port  120 - 1  and a second end that is connected to first RF connector  124 , whereas second RF cable  122 - 2  may have a first end that is connected to port  120 - 2  and a second end that is connected to second RF connector  124 . 
     Test unit  106  may be coupled to test probes  128  attached in test fixture  133 . First test probe  128  may have an associated RF connector  126  that is mated with first RF connector  124 , whereas second test probe  128  may have an associated RF connector  126  that is mated with second RF connector  124  (e.g., first and second test probes  128  may be respectively coupled to cables  122 - 1  and  122 - 2  via corresponding mating connectors  124  and  126 ). Test probes  128  may be held in place within test probe holding structure  134 . The position of each test probe  128  within holding structure  134  may be adjusted using adjustment structures  131 . 
     Test fixture  133  may also include a DUT holding structure  138  and a test fixture vertical support structure  136  configured to support holding structures  134  and  138 . During testing, a DUT  10  or device structures under test  10 ′ may be placed in a cavity within DUT holder  138 . In one suitable arrangement, the position of DUT holder  138  may be controlled using positioner  140 . Positioner  140  may, for example, include actuators for controlling the vertical movement of DUT holder  138  (as an example). When device structures under test  10 ′ are mounted within DUT holder  138 , DUT holder  138  may be moved vertically in direction  142  so that test probes  128  make direct contact with corresponding portions of structures  10 ′. For example, each test probe  128  (e.g., a pogo pin test probe) may include signal pin  130  and ground pin  132 . In the mated state, the signal and ground pins of first test probe  128  may make respectively contact at locations A and B on device structures  10 ′, whereas the signal and ground pins of second test probe  128  may make respect contact at locations C and D on device structures  10 ′. 
     Test system  100  of  FIG. 6  is merely illustrative and is not intended to limit the scope of the present invention. If desired, test fixture  133  may include any number of test probes  128  (e.g., more than two test probes, more than four test probes, etc.). Test station  102  may include any number of test units  106  each with sufficient number of ports to supply and receive radio-frequency test signals to the different test probes in test fixture  133 . Device structures  10 ′ may be mated with test probes  128  manually or semi-automatically by moving only test probe holding structure  134 , by moving only DUT holding structure  138 , or by moving both structures  134  and  136 . 
       FIG. 7  is a perspective view of DUT holding structure  138  having a cavity  150  in which device structures under test  10 ′ may be temporarily mounted during testing. As shown in  FIG. 7 , at least two protruding members  152  may be formed within cavity  150 . Device structures under test  10 ′ may have corresponding engagement features  154  (e.g., holes) through which protruding members  152  may be inserted. Protruding members  152  may serve as registration features for DUT holding structure  138  so that the horizontal placement of device structures under test  10 ′ is set to a known and precise position when device structures under test  10 ′ are placed in DUT holding structure  138 . If desired, device structures under test  10 ′ may be secured to the known position using other types of engagement features. 
       FIG. 8  shows device structures under test  10 ′ when it is mated with DUT holding structure  138 . As shown in  FIG. 8 , protruding members  152  are inserted through holes  154  in midplate  58 . During testing, it may be desirable to probe various parts of device structures under test  10 ′. Indicator pairs  160 ,  162 ,  164 , and  166  show possible pairs of probe points at which the test probes should contact device structures under test  10 ′ during testing. For example, indicator pair  160  shows that it may be desirable to place a pair of signal and ground pins in a first test probe at the signal and ground feed points for the lower antenna, where as indicator pair  162  shows that it may be desirable to place a pair of signal and ground pins in a second test probe at the signal and ground feed points for the upper antenna. Indicator pair  164  shows that it may be desirable to place the signal and ground pins in a third test probe at opposing ends of gap  18  to test whether that gap is properly formed. Indicator pair  166  shows that it may be desirable to place the signal and ground pins of a fourth test probe in contact with member  16  and midplate  58 , respectively, to determine whether member  16  and midplate  58  are properly welded to each other. If any of the test probes is slightly offset from their intended position (e.g., if any of the test probes is offset by more than 0.1 mm, more than 2 mm, more than 5 mm, etc.), the signal and ground pins of the erroneously positioned test probe will not be able to make proper contact with device structures under test  10 ′. Gauge block  300  may therefore be used to ensure that each of test probes  128  in the test fixture is positioned properly. 
       FIG. 9A  is a cross-sectional side view of one suitable arrangement of test probe holding structure  134  configured for use with the DUT holding structure of the type described in connection with  FIG. 7 . As shown in  FIG. 9A , test probe holding structure  134  may include at least two holes  220  through which protruding member  152  (of  FIGS. 7 and 8 ) may be inserted and protruding structures  222  that protrude out from the bottom surface of test probe holding structure  134  at a length Z 1 . Pin  130  in each test probe  128  may, for example, protrude out from the bottom surface of test probe holding structure  134  at a length Z 2  that is greater than Z 1 , equal to Z 1 , or less than Z 1 . 
     Holes  220  serve to receive protruding member  152  for horizontal registration of device structures under test  10 ′ (e.g., to set the relative horizontal positions of test probes  128  and device structures under test  10 ′ to a known value when they are in the mated state), whereas protruding structures  222  serve to make contact with the surface of midplate  58  for vertical registration of device structures under test  10 ′ (e.g., to set the vertical distance between test probes  128  and device structures under test  10 ′ to a known value when they are in the mated state). Structures  220  and  222  may therefore sometimes be referred to as horizontal registration features and vertical registration features, respectively. Holes  220  and structures  222  represent one suitable implementation for registration features  151  in test probe holding structure  134  described in connection with  FIG. 5 . 
     In the example of  FIG. 9A , the position of first and second test probes  128  may be adjusted by an operator by manually shifting their position within respective test probe adjustment regions  200 . Test probe  128  may have supporting members  202  resting on corresponding surfaces  206  in respectively cavities  204 . The position of first test probe  128  may be secured using screws  208  (e.g., screws that clinch the position of the test probe within region  200 ), whereas the position of second test probe  128  may be secured using a lever mechanism  210  (e.g., levers that lock the position of the test probe within region  200  when turned in the direction of arrow  212 ). In general, the positions of test probes  128  within test probe holding structure  134  may be secured by screwing, clamping, soldering, welding, gluing, or using other permanent/temporary attachment mechanisms. 
       FIG. 9B  shows the bottom view of test probe holding structure  134 . As shown in  FIG. 9B , there may be four protruding registration features  222 , two recessed registration features  220 , and four test probes  128  positioned within test probe holding structure  134 . The example of  FIG. 9B  is merely illustrative and is not intended to limit the scope of the present invention. If desired, there may be more than two horizontal registration features  220 , less than four vertical registration features  222 , and any number of test probes  128  in any suitable configuration within test probe holding structure  134 . 
       FIG. 10  is an exploded perspective view of illustrative gauge  300  configured to mate with test probe holding structure  134 . As shown in  FIG. 10 , test probe holding structure  134  may have five test probes  128  that can be secured within structure  134  using screws  208 . Gauge block  300  may be formed from a piece of material (e.g., a block of plastic, dielectric material, metal, conductive material, or other suitable type of material). Gauge block  300  may include recessed portions  302  configured to engage with vertical registration features  222  associated with test probe holding structure  134 . Gauge block  300  may have at least two holes through with members  152  (see, e.g.,  FIGS. 7 and 8 ) may be inserted when gauge block is placed in DUT holding structure  138 . 
     In another suitable arrangement, these horizontal registration features  152 ′ may be formed as an integral part of gauge block  300  (e.g., gauge block  300  need not be placed within DUT holding structure  138  during test probe alignment procedures). Structures  152 ′ and  302  may represent one implementation of gauge block registration features  153  of the type described in connection with  FIG. 5 . 
     Gauge block  300  of  FIG. 10  may include test probe alignment features corresponding to different test probes  128  in test probe holding structure  134  (see, e.g.,  FIG. 11 ). As shown in  FIG. 11 , recessed portions  310 ,  312 ,  314 ,  316 , and  318  may represent alignment features corresponding to signal and ground pins  130  and  132  in the five respective test probes  128  in  FIG. 10 . These test probe alignment features in gauge block  300  are manufactured precisely to help guide test probes  128  to their desired positions within test probe holding structure  134 . Additional guiding features such as structures  320  may be formed on the surface of gauge block  300  to provide additional retention force and mechanical support for gauge block  300  while it is mated with test probe holding structure  134 . 
     Different types of electronic devices may have different shapes and structures for test. Different test stations may be assembled to test these different device structures. As a result, different gauge blocks  300  associated with the different devices may be used to set up the different test stations. As an example, the gauge block of  FIG. 12  may have test probe alignment features formed at different locations in comparison to the gauge block of  FIG. 11 . 
       FIG. 13  is a cross-sectional side view of gauge block  300  when it is mated with test probe holding structure  134 . If test probe  128  is positioned correctly, signal pin  130  will mate properly with alignment feature  330  so that the surfaces of structure  134  and block  300  are in direct contact, as shown in  FIG. 13 . If test probe  128  is slightly offset from its correct position, however, signal pin  130  will not be aligned with feature  3330  and the surfaces of structure  134  and block  300  will not be able to make direct contact. In such scenarios, an alert may be sent to the operator indicating that at least one of test probes  128  in test probe holding structure  134  is misaligned. This is merely illustrative. The surface of structures  134  and  300  need not be in direct contact to indicate proper test probe alignment. For example, proper test probe alignment can be determined as long as the distance between structures  134  and  300  is less than a predetermined value. 
       FIG. 14  is a flow chart of illustrative steps involved in initially setting up a test station. To set up proper test probe alignment for a given test station (step  400 ), gauge block  300  may first be place into DUT holding structure  138  (step  402 ). At step  403 , the test probes may be placed in an adjustable state to reduce the possibility of damaging the test probes in step  404  (e.g., test probe fasteners may be loosened or other test probe securing mechanisms may be temporarily alleviated to allow for movement in the position of the test probes). At step  404 , DUT holding structure  138  may be moved towards test probe holding structure  134  so that gauge block  300  is engaged with the test probes. At step  406 , the position of each of the test probes may be adjusted (manually or semi-automatically) so that the test probes are properly mated with the corresponding test probe alignment features in gauge block  300 . At step  408 , the test probes may be secured by tightening associated test probe fasteners or using other suitable mechanisms for fixing the position of the test probes (e.g., screws, levers, solder, welds, adhesive material, etc.). 
     At step  410 , the test unit may be powered on and the test station may be calibrated using at least one reference DUT (e.g., the reference DUT may be used to calibrate downlink and uplink path loss characteristics associated with the test station). Other test station characteristics may also be calibrated during step  410 . 
     At step  412 , the test station is ready for use and may be used to test whether partially-assembled device structures under test  10 ′ or fully-assembled electronic devices  10  satisfy design criteria. Processing may loop back to step  400  periodically for test station maintenance purposes (e.g., to ensure that the positions of the test probes have not shifted after some period of use), as indicated by path  414 . 
     Gauge block  300  may also be used as a tool for checking whether a test station is properly set up or exhibits misaligned test probes (i.e., for go/no-go or maintenance checking). At step  500 , gauge block  300  may have placed into DUT holding structure  138 . At step  502 , an operator may attempt to move DUT holding structure  138  towards test probe holding structure  134 . If gauge block  300  is able to properly mate with the test probes (e.g., if the distance between gauge block  300  and test probe holding structure  134  is less than a predetermined value), an alert may be sent to the operator indicating that the test probes are properly aligned and processing may proceed to step  410  ( FIG. 15 ). If gauge block  300  is unable to properly engage with at least one of the test probes (e.g., if the distance between gauge block  300  and test probe holding structure  134  exceeds the predetermined value), an alert may be sent to the operator indicating that at least one of the test probes is misaligned. In such scenarios, the test probes may be loosened so that the position of the test probes may be readjusted to their desired positions (see, e.g., step  400  in  FIG. 14 ). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20110630
Publication Date: 20160315
Grant Date: 20160315
Priority Date: 20110630
Inventors: NICKEL JOSHUA G.
SHEN JR-YI
Assignee: APPLE INC
CPC Classifications: [{"code": "G01R31/3025", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01R31/2891", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R29/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01R29/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B17/0045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01R31/2891", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R31/3025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B17/0032", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 47389983