PATENT DOCUMENT

Publication Number: US-8847617-B2
Application Number: US-201113092808-A
Country: US
Kind Code: B2

Title: Non-contact test system for determining whether electronic device structures contain manufacturing faults

Abstract:
Electronic device structures such as structures containing antennas, connectors, welds, electronic device components, conductive housing structures, and other structures can be tested for faults using a non-contact test system. The test system may include a vector network analyzer or other test unit that generates radio-frequency tests signals in a range of frequencies. The radio-frequency test signals may be transmitted to electronic device structures under test using an antenna probe that has one or more test antennas. The antenna probe may receive corresponding radio-frequency signals. The transmitted and received radio-frequency test signals may be analyzed to determine whether the electronic device structures under test contain a fault.

Claims:
What is claimed is: 
     
       1. A method for testing electronic device housing structures under test using a tester that has a test unit and an associated antenna probe, comprising:
 generating radio-frequency test signals with the test unit; 
 wirelessly transmitting the radio-frequency test signals to the device housing structures under test using the antenna probe; 
 receiving corresponding radio-frequency test signals from the device housing structures under test using the antenna probe; 
 providing the received radio-frequency test signals to the test unit from the antenna probe; 
 determining from at least the received radio-frequency test signals whether the device housing structures under test contain a fault; and 
 performing calibration operations to obtain calibration data, wherein determining from at least the received radio-frequency test signals whether the device housing structures under test contain a fault comprises comparing the received radio-frequency test signals to the calibration data. 
 
     
     
       2. The method defined in  claim 1 , wherein the received radio-frequency test signals comprises reflected radio-frequency test signals, and wherein determining from at least the received radio-frequency test signals whether the device housing structures under test contain a fault comprises using the reflected radio-frequency test signals to determine whether the device housing structures under test contain a fault. 
     
     
       3. The method defined in  claim 2  further comprising issuing an alert with the tester when comparing the reflected radio-frequency test signals to the calibration data reveals that the reflected radio-frequency test signals and the calibration data differ by more than a predetermined amount. 
     
     
       4. The method defined in  claim 1 , wherein performing the calibration operations comprises gathering the calibration data by using the test unit and antenna probe to perform measurements on a properly assembled version of the device housing structures under test. 
     
     
       5. The method defined in  claim 4  wherein the antenna probe contains first and second test antennas and wherein wirelessly transmitting the radio-frequency test signals comprises wirelessly transmitting the radio-frequency test signals using the first and second test antennas. 
     
     
       6. The method defined in  claim 5  wherein the device housing structures under test include first and second device antennas, the method further comprising placing the first and second test antennas respectively in the vicinity of the first and second device antennas while transmitting the radio-frequency test signals. 
     
     
       7. The method defined in  claim 4  wherein the antenna probe contains at least one probe antenna and wherein the device housing structures under test include at least one device antenna, the method further comprising placing the antenna probe in the vicinity of the device antenna while transmitting the radio-frequency test signals. 
     
     
       8. The method defined in  claim 1  wherein the device housing structures under test include a first connector and include a second connector coupled to an antenna resonating element and wherein determining from at least the received radio-frequency test signals whether the device housing structures under test contain a fault comprises determining whether the first and second connectors are properly connected to each other. 
     
     
       9. The method defined in  claim 1  further comprising:
 placing the device housing structures under test in a test fixture before wirelessly transmitting the radio-frequency test signals to the device structures under test using the antenna probe. 
 
     
     
       10. A method for testing electronic device housing structures under test using a tester that has at least one test antenna, comprising:
 with the tester, transmitting radio-frequency test signals to the device housing structures under test using the test antenna; 
 receiving corresponding radio-frequency test signals from the device housing structures under test using the test antenna; 
 determining from at least the received radio-frequency signals whether the device housing structures under test contain a fault; and 
 performing calibration operations to obtain calibration data, wherein determining from at least the received radio-frequency test signals whether the device housing structures under test contain a fault comprises comparing the received radio-frequency test signals to the calibration data. 
 
     
     
       11. The method defined in  claim 10  further comprising:
 in response to determining that the device housing structures under test contain a fault, displaying an alert on a display. 
 
     
     
       12. The method defined in  claim 10  wherein receiving the corresponding radio-frequency test signals from the device housing structures under test using the test antenna comprises receiving near-field radio-frequency test signals. 
     
     
       13. A test system for performing non-contact testing on electronic device structures under test, comprising:
 a test unit that generates radio-frequency test signals; and 
 an antenna with which the radio-frequency test signals are transmitted to the electronic device structures under test and with which corresponding radio-frequency test signals are received, wherein the test unit is configured to determine whether the electronic device structures under test include a fault based on the transmitted and received radio-frequency test signals, wherein the radio-frequency test signals that are received includes reflected versions of the transmitted radio-frequency test signals, wherein the test unit comprises a network analyzer, wherein the radio-frequency test signals include signals that range from a first frequency to a second frequency, and wherein the test unit computes complex impedance data from the transmitted and reflected versions of the radio-frequency test signals. 
 
     
     
       14. The test system defined in  claim 13 , further comprising:
 performing calibration operations to obtain baseline data from a known fault-free version of the electronic device structures under test, wherein the test unit is configured to compare the computed complex impedance data to the baseline data to determine whether the electronic device structures under test include a fault.

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 a cable and connectors. Connectors and cables are also used to convey other signals such as digital data signals in an electronic device. Many electronic devices include conductive structures with holes, slots, and other shapes. Welds and springs may be used in forming connections between conductive structures such as these 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. In some situations, it can be difficult or impossible to detect and identify these faults, if at all, until assembly is complete and a finished device is available for testing. Detection of faults only after assembly is complete can results in costly device scrapping or extensive reworking. 
     It would therefore be desirable to be able to provide improved ways in which to detect faults during the manufacturing of electronic devices. 
     SUMMARY 
     A non-contact test system may be provided for performing tests on electronic device structures. The electronic device structures may be tested during manufacturing, before or after the structures are fully assembled to form a finished electronic device. Testing may reveal faults that might otherwise be missed in tests on finished devices and may detect faults at a sufficiently early stage in the manufacturing process to allow parts to be reworked or scrapped at minimal. 
     The electronic device structures may contain structures such as antennas, connectors and other conductive structures that form electrical connections, welds, solder joints, conductive traces, conductive surfaces on conductive housing structures and other device structures, dielectric layers such as foam layers, electronic components, and other structures. These structures can be tested using wireless test signals from the non-contact test system. During testing, the device structures under test may be placed in a test fixture. 
     The test system may include a vector network analyzer or other test unit that generates radio-frequency tests signals in a range of frequencies. The radio-frequency test signals may be transmitted to electronic device structures under test using an antenna probe. The antenna probe may include one or more test antennas for transmitting the radio-frequency test signals. During testing, the test antennas may be placed in the vicinity of corresponding structures to be tested such as electronic device antennas, connectors, structures with welds, electronic components, conductive housing structures, conductive traces, conductive surfaces on housing structures or other device structures, device structures including dielectric layers, structures with solder joints, and other structures. The antenna probe may use the test antennas to receive corresponding radio-frequency signals from the device structures under test. For example, the antenna probe may use one or more antennas to receive reflected radio-frequency signals or radio-frequency signals that have been transmitted through the device structures under test. The transmitted and reflected radio-frequency test signals may be analyzed to produce complex impedance measurements and complex forward transfer coefficient measurements. These measurements or other gathered test data may be compared to previously obtained baseline measurements on properly assembled structures to determine whether the electronic device structures under test contain a fault. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a diagram of an illustrative test system environment in which electronic device structures may be tested using a non-contact tester with a wireless probe in accordance an embodiment of the present invention. 
         FIG. 1B  is a diagram of illustrative test system equipment in which probe antennas are used to transmit test signals through device structures under test in accordance with an embodiment of the present invention. 
         FIG. 2  is a diagram of illustrative electronic device structures with wireless components during testing with a tester that has a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 3  is a graph showing how the magnitude of reflected radio-frequency signals that are received by a test system probe antenna may vary as a function of whether a test structure contains faults in accordance with an embodiment of the present invention. 
         FIG. 4  is a graph showing how the phase of reflected radio-frequency signals that are received by a test system probe antenna may vary as a function of whether a test structure contains faults in accordance with an embodiment of the present invention. 
         FIG. 5A  is a side view of an illustrative probe antenna in accordance with an embodiment of the present invention. 
         FIG. 5B  is a perspective view of an illustrative probe antenna based on an open-ended waveguide in accordance with an embodiment of the present invention. 
         FIG. 6  is a top view of an illustrative wireless probe based on a loop antenna structure in accordance with an embodiment of the present invention. 
         FIG. 7  is a top view of an illustrative dipole patch antenna that may be used in a wireless test probe in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of the dipole patch antenna of  FIG. 7  in accordance with an embodiment of the present invention. 
         FIG. 9  is a top view of illustrative electronic device structures of the type that may be tested using a wireless test system of the type shown in  FIG. 1A  in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an illustrative wireless probe structure having two probe antennas that are configured to test components such as mating antennas in a device of the type shown in  FIG. 9  in accordance with an embodiment of the present invention. 
         FIG. 11A  is a top view of illustrative electronic device structures that include a conductive planar electronic device housing structure having slots that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 11B  is a Smith chart of illustrative test measurements that may be gathered when testing electronic device structures of the type shown in  FIG. 11A  in accordance with an embodiment of the present invention. 
         FIG. 12  is a top view of illustrative electronic device structures that include conductive structures with welds that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 13  is a side view of an illustrative electronic component in an electronic device that has electrical contacts that are configured to make contact with mating contacts on a printed circuit board in the device in accordance with an embodiment of the present invention. 
         FIG. 14  is an exploded perspective view of electronic device structure including a rigid printed circuit board and a flexible printed circuit board with mating connectors of the type that may be tested using a non-contact test system of the type shown in  FIG. 1A  in accordance with an embodiment of the present invention. 
         FIG. 15  is a side view of illustrative electronic device structures that include surface height variations that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 16  is a side view of an illustrative electronic component mounted to a substrate using solder of the type that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 17  is a side view of an illustrative electronic component covered with an electromagnetic shield structure the type that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 18  is a top view of a pair of metal traces on a substrate of the type that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 19  is a cross-sectional side view of device structures under test that include a dielectric layer of the type that may be tested for defects with a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 20  is a perspective view of an electronic device having a peripheral conductive member of the type that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 21  is a cross-sectional side view of an illustrative speaker of the type that may be tested using a wireless probe in accordance with an embodiment of the present invention. 
         FIG. 22  is a flow chart of illustrative steps involved in wirelessly testing electronic devices and structures in electronic devices using a wireless test system of the type shown in  FIG. 1A  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 within the structures such as speakers, microphones, displays, antennas, switches, connectors, and other components, may be mounted within the housing of an 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. 
     With conventional testing arrangements, these faults may sometimes be detected after final assembly operations are complete. For example, over-the-air wireless tests on a fully assembled device may reveal that an antenna is not performing within desired limits. This type of fault may be due to improper connection of a pair of connectors in the signal path between the antenna and a radio-frequency transceiver. Detection of faults at late stages in the assembly process may, however, result in the need for extensive reworking. It may often be impractical to determine the nature of the fault, forcing the device to be scrapped. 
     Earlier and potentially more revealing and accurate tests may be performed by using a wireless probe structure to wirelessly test electronic device structures. An illustrative test system with a wireless probe for use in testing electronic device structures is shown in  FIG. 1A . In test system  10 , tester  12  may be used to perform wireless (non-contact) tests on device structures under test  14 . Device structures under test  14  may include portions of an 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. 
     Tester  12  may include a test unit such as test unit  20  and one or more wireless probes such as antenna probe  18 . Antenna probe  18  may be used to transmit radio-frequency signals  26  to device structures  14  and may be used to receive corresponding radio-frequency signals  28  from device structures under test  14 . The transmitted and received signals may be processed to compute complex impedance data (sometimes referred to as S 11  parameter data), complex forward transfer coefficient data (sometimes referred to as S 21  data), or other suitable data for determining whether device structures  14  contain a fault. 
     Antenna probe  18 , which may sometimes be referred to as a wireless probe, may include one or more antennas. The antennas in antenna probe  18 , which are sometimes referred to herein as test antennas or probe antennas, may be implemented using any suitable antenna type (e.g., loop antennas, patch antennas, dipole antennas, monopole antennas, inverted-F antennas, planar inverted-F antennas, coil antennas, open-ended waveguides, horn antennas, etc.). 
     During testing, antenna probe  18  may be placed in the vicinity of device structures under test  14 . For example, antenna probe  18  may be placed within 10 cm or less of device structures under test  14 , within 2 cm or less of device structures under test  14 , or within 1 cm or less of device structures under test  14  (as examples). These distances may be sufficiently small to place antenna probe  18  within the “near field” of device structures under test  14  (i.e., a location at which signals are received by an antenna that is located within about one or two wavelengths from device structures under test  14  or less). Device structures under test  14  may be mounted in a test fixture such as test fixture  31  during testing. Test fixture  31  may contain a cavity that receives some or all of device structures under test  14 . Test fixture  31  may, if desired, be formed from dielectric materials such as plastic to avoid interference with radio-frequency test measurements. The relative position between antenna probe  18  and device structures under test  14  may be controlled manually by an operator of test system  10  or may be adjusted using computer-controlled or manually controlled positioners such as positioners  16  and  33 . Positioners  16  and  33  may include actuators for controlling lateral and/or rotational movement of antenna probe  18  and/or device structures under test  14 , respectively. 
     Test unit  20  may include signal generator equipment that generates radio-frequency signals over a range of frequencies. These generated signals may be provided to antenna probe  18  over path  24  and may be transmitted towards device structures under test  14  as transmitted radio-frequency test signals  26 . Test unit  20  may also include radio-frequency receiver circuitry that is able to gather information on the magnitude and phase of corresponding received signals from device structures under test  14  (i.e., radio-frequency signals  28  that are reflected from device structures under test  14  and that are received using antenna probe  18  or radio-frequency signals  28  that have passed through device structures under test  14 ). Using the transmitted and received signals, the magnitude and phase of the complex impedance and/or complex forward transfer coefficient of the device structures under test may be determined. With one suitable arrangement, test unit  20  may be a vector network analyzer (VNA) or other network analyzer and a computer that is coupled to the vector network analyzer for gathering and processing test results. This is, however, merely illustrative. Test unit  20  may include any suitable equipment for generating radio-frequency test signals of desired frequencies while measuring and processing corresponding received signals. 
     The radio-frequency signals that are generated by test unit  20  may be supplied to antenna probe  18  using path  24 . Path  24  may include, for example, a coaxial cable or, when multiple test antennas are included in antenna probe  18 , may include multiple coaxial cables, each associated with a respective one of test antennas. 
     By analyzing the transmitted and reflected signals, test unit  20  may obtain measurements such as s-parameter measurements that reveal information about whether device structures under test  14  are faulty. Test unit  20  may, for example, obtain an S 11  (complex impedance) measurement and/or an S 21  (complex forward transfer coefficient) measurement. The values of S 11  and S 21  (phase and magnitude) may be measured as a function of signal frequency. In situations in which device structures under test  14  are fault free, S 11  and S 21  measurements will have values that are relatively close to baseline measurements on fault-free structures (sometimes referred to as reference structures or a “gold” unit). In situations in which device structures under test  14  contain a fault that affects the electromagnetic properties of device structures under test  14 , the S 11  and S 21  measurements will exceed normal tolerances. When test unit  20  determines that the S 11  and/or S 21  measurements have deviated from normal S 11  and S 21  measurements by more than predetermined limits, test unit  20  can alert an operator that device structures under test  14  likely contain a fault and/or other appropriate action can be taken. For example, an alert message may be displayed on display  200  of test unit  20 . The faulty device structures under test  14  may then be repaired to correct the fault or may be scrapped. With one suitable arrangement, an operator of system  10  may be alerted that device structures under test  14  have passed testing by displaying an alert message such as a green screen and/or the message “pass” on display  200 . The operator may be alerted that device structures under test  14  have failed testing by displaying an alert message such as a green screen and/or the message “fail” on display  200  (as examples). If desired, S 11  and/or S 21  data can be gathered over limited frequency ranges that are known to be sensitive to the presence or absence of faults. This may allow data to be gathered rapidly (e.g., so that the operator may be provided with a “pass” or “fail” message within less than 30 seconds, as an example). 
     Complex impedance measurements (S 11  phase an magnitude data) on device structures under test  14  may be made by transmitting radio-frequency signals with an antenna and receiving corresponding reflected radio-frequency signals from the device under test using the same antenna. Complex forward transfer coefficient measurements (S 21  phase and magnitude data) on device structures under test  14  may be made by transmitting radio-frequency signals with a first antenna and receiving a corresponding set of radio-frequency signals from device structures under test  14  using a second antenna.  FIG. 1B  shows show antenna probe  18  may contain a first antenna such as antenna  18 A and a second antenna such as antenna  18 B. During testing, antenna  18 A may be used to transmit radio-frequency test signals to device structures under test  14 . Antenna  18 B may be used to receive corresponding test signals from device structures under test  14  so that data such as complex forward transfer coefficient data (S 21  parameter data) may be produced. 
     Test system  10  may be used to detect faults in conductive housing structures, faults associated with welds or solder joints between conductive structures, antenna structure faults, faults in connector structures such as connector structures coupled to cables and printed circuit boards or other conductive structures that form electrical connections, faults in conductive traces, faults in conductive surfaces, faults in dielectric structures adjacent to conductive structures, faults in structures that include components that are electrically connected using springs or other contacts, or faults in other device structures under test  14 . Any fault that affects the electromagnetic properties of device structures under test  14  and therefore affects the measured S 11  and/or S 21  data that is gathered using test unit  20  may potentially be detected using test system  10 . 
     In the illustrative scenario of  FIG. 2 , for example, non-contact tester  12  is being used to test device structures under test  14  that contain antenna structures. As shown in  FIG. 2 , device structures under test  14  may include a printed circuit board such as printed circuit board  32 . Printed circuit board  32  may be, for example, a rigid printed circuit board formed from fiberglass-filled epoxy (e.g., FR-4) or may be a flexible printed circuit (“flex circuit”) formed from a sheet of polymer such as a polyimide sheet. Printed circuit board  32  may be mounted to housing structures such as conductive housing structures  30 . Structures  30  and/or conductive metal traces within printed circuit board  32  such as traces  36  may be used to form antenna ground. One or more antennas may be formed using the antenna ground and one or more corresponding antenna resonating elements such as antenna resonating element  46 . 
     A radio-frequency transceiver such as transceiver  34  may be mounted to printed circuit board  32 . Conductive traces  36  may be used to form a transmission line (e.g., a microstrip transmission line, a stripline transmission line, an edge coupled microstrip or stripline transmission line, etc.) that is coupled between transceiver  34  and an antenna that is formed from antenna resonating element  46  and antenna ground (e.g., conductive antenna ground structure  30 ). If desired, one or more segments of coaxial cable may be incorporated within a transmission line path in device structures under test  14 . The example of  FIG. 2  in which conductive traces  36  in printed circuit board  32  are used in forming a transmission line that is coupled between transceiver  34  and an antenna is merely illustrative. 
     Antenna resonating element  46  may include antenna resonating element conductive structures such as patterned metal traces  44 . Metal traces  44  may be formed on a substrate such as substrate  42 . Substrate  42  may be formed from a dielectric such as a plastic support structure, a rigid printed circuit board, or a flexible printed circuit. A connector such as connector  40  may be electrically coupled to antenna resonating element traces  44 . Connector  40  may be, for example, a U.FL connector or a W.FL connector (as examples). Connector  40  may mate with a coaxial cable connector or, in the example of  FIG. 2 , a mating connector such as connector  38  on printed circuit board  32 . 
     The electromagnetic signature (i.e., the S 11  and/or S 21  measurements made by tester  12 ) of device structures under test  14  of  FIG. 2  may be affected by the way in which these structures are manufactured and assembled. For example, if part of trace  44  or part of trace  36  is not present, antenna resonating element  46  may not be properly connected to transceiver  34  or may have a shape or size that is different than expected. The presence or absence of a proper connection between mating connectors such as connectors  38  and  40  may also influence the electromagnetic signature of device structures under test  14 . If, for example, connector  40  has been properly connected to connector  38 , antenna resonating element  46  may be properly coupled to the transmission line formed from traces  36  on printed circuit board  32 . In this situation, tester  12  may measure normal (expected) values of S 11  (or S 21 ) when wirelessly probing device structures under test  14 . If, on the other hand, connector  40  has not been properly connected to connector  38  (e.g., because an operator or assembly tool has formed an incomplete or otherwise faulty connection), tester  12  may measure abnormal values of S 11  (or S 21 ) when wirelessly probing device structures under test  14  due to the impedance discontinuities or other irregularities resulting from the faulty connection. In response to detection of abnormal wireless measurements on device structures under test  14 , tester  12  may generate an audible and/or visual alert for an operator (e.g., an alert displayed on display  200 ) or may take other suitable actions. 
     In the graphs of  FIGS. 3 and 4 , test data gathered by tester  12  is plotted as a function of applied signal frequency over a range of signal frequencies from 0 GHz to 3 GHz. Test measurements may be made using a swept frequency from 0-3 GHz or using other suitable frequency ranges (e.g., frequency ranges starting above 0 GHz and extending to an upper frequency limit of less than 3 GHz or greater than or equal to 3 GHz). The use of a 0-3 GHz test signal frequency range in the example of  FIGS. 3 and 4  is merely illustrative. In the graph of  FIG. 3 , the magnitude of S 11  is plotted as a function of frequency. In the graph of  FIG. 4 , the phase of S 11  is plotted as a function of frequency. 
     The illustrative device structures under test that were used in the test measurements of  FIGS. 3 and 4  contained multiple device antennas. The antennas include a first device structures under test antenna (e.g., a WiFi® antenna that is used to handle IEEE 802.11 traffic) and a second device structures under test antenna (e.g., a cellular telephone antenna). The antenna probe  18  that was used in transmitting radio-frequency signals  26  and that was used in gathering reflected radio-frequency signals  28  includes two corresponding test antennas (i.e., a first test antenna that is placed in the vicinity of the first device structures under test antenna and a second test antenna that is placed in the vicinity of the second device structures under test antenna). 
       FIG. 3  shows S 11  magnitude measurements made using the first and second test antennas and  FIG. 4  shows an S 11  phase measurements made using the first and second test antennas. Initially, during calibration operations, test unit  20  may gather S 11  measurements from device structures under test that are known to be fault free. When device structures under test  14  are fault free, the S 11  measurements follow curves  48  of  FIGS. 3 and 4  (in this example). Curves  48  may therefore represent a baseline (calibration) response for the device structures under test in the absence of faults. The baseline response serves as a reference that can be used to determine when measurements results are meeting expectations or are deviating from expectations. 
     If one or more faults are present, the S 11  measurements made by tester  12  will deviate from curves  48 , because the electromagnetic properties of structures  14  will be different than in situations in which structures  14  are free of faults. For example, a disconnected antenna connector will result in an impedance discontinuity in the transmission line path between the antenna and its associated transceiver. Improperly formed antenna structures such as faults in springs or screws or other metal structures (e.g., feed structures, matching element structures, resonating element structures, antenna ground structures, etc.) may also result in detectable changes in electromagnetic properties. When near-field-coupled or far-field coupled electromagnetic signals from antenna probe  18  reach structures  14 , the impedance discontinuity in structures  14  (or other fault-related change in structures  14 ) will produce a change in received signal  28  (and the computed S 11  or S 21  data) that can be detected by tester  12 . In the present example, the S 11  measurements will follow curves  50  when the first device antenna contains a fault and the second device antenna is free of faults, will follow curves  52  when both the first and second device antennas are not operating properly, and will follow curves  54  when the first device antenna is operating satisfactorily but the second device antenna is not operating satisfactorily. 
     The shapes of curves  50 ,  52 , and  54  and the amounts by which curves  50 ,  52 , and  54  vary from the known reference response (curve  48 ) in  FIGS. 3 and 4  is merely illustrative. Device structures under test with different configurations will typically produce different results. Provided that test results measured with tester  14  have detectable differences from the reference curves associated with satisfactory device structures under test (i.e., structures that do not contain faults such as misshapen antenna resonating element traces or other conductive structures, poorly connected or disconnected connectors, etc.), tester  12  will be able to detect when faults are present and will be able to take appropriate actions. 
     Actions that may be taken in response to detection of a fault in device structures under test  14  include displaying a warning (e.g., on computer monitor  200  in test unit  20 , on a status light-emitting diode in test unit  20 , or on other electronic equipment associated with test unit  20  that may display visual information to a user), issuing an audible alert, using positioning equipment in system  10  to automatically place the device structures under test  14  in a suitable location (e.g., a reject bin), etc. 
       FIG. 5A  is a cross-sectional side view of an illustrative antenna probe of the type that may be used in a test system of the type shown in  FIG. 1A . As shown in  FIG. 5A , antenna probe  18  may include a substrate such as substrate  56 . Substrate  56  may be formed from a dielectric such as plastic, may be formed from a rigid printed circuit board substrate such as fiberglass-filled epoxy, may be formed from a flexible printed circuit (“flex circuit”) substrate such as a sheet of polyimide, or may be formed from other dielectric substrate materials. Conductive antenna structures may be formed on substrate  56  to form one or more antennas. In the example of  FIG. 5A , antenna probe  18  includes conductive traces  58  and  60  on the surface of substrate  56 . Traces  58  and  60  may be separated by a gap such as gap  68  and may form a dipole patch antenna. Conductive traces  62  supported by substrate  56  (e.g., one or more surface traces and/or buried metal traces) may be used in electrically coupling a connector such as coaxial cable connector  64  to traces  58  and  60 . Connector  64  may receive a mating connector such as coaxial cable connector  66  on the end of coaxial cable  24 , thereby coupling antenna probe  18  to test unit  20  ( FIG. 1A ). 
     The pattern of traces such as traces  58 ,  60 , and  62  may be used on substrate  56  to form any suitable type of antenna (e.g., a patch antenna, a loop antenna, a monopole antenna, a dipole antenna, an inverted-F antenna, an open or closed slot antenna, a planar inverted-F antenna, etc.). The conductive traces may be used to form an antenna resonating element that is coupled to a positive antenna feed terminal and an antenna ground that is coupled to an antenna ground feed terminal. 
     As shown in  FIG. 5B , antenna probe  18  may, if desired, be formed from an open-ended waveguide (i.e., a waveguide having a body such as body  220  with an open end such as open end  222 ). Open-ended waveguides may operate in frequency ranges such as 3-14 GHz or frequencies above 14 GHz or below 3 GHz, as examples. The antennas that may be used for forming one or more antennas in antenna probe  18  include dipoles, loops, horns, coils, open-ended waveguides, etc. 
     In the example of  FIG. 6 , conductive traces  70  on substrate  56  have been used to form a loop antenna. Coaxial cable  24  (or other transmission line) may have a positive conductor coupled to positive antenna feed terminal  76  and a ground conductor coupled to ground antenna feed terminal  78 . Positive antenna feed terminal  76  is coupled to upper conductive trace  70 . Via  74  couples upper trace  70  to lower trace  72  (e.g., a trace on an opposing surface of a printed circuit board substrate or in a different layer of substrate  56 ). After looping around the periphery of substrate  56  lower trace  72  may be connected to ground feed terminal  78  by a via structure. The illustrative loop antenna of  FIG. 6  uses two loops (upper and lower), but additional loops (e.g., three or more loops) or fewer loops (e.g., a single loop) may be used in antenna probe  18  if desired. 
     A top view of an illustrative dipole patch antenna of the type that may be used in forming antenna probe  18  is shown in  FIG. 7 . As shown in  FIG. 7 , antenna probe  18  may be formed from conductive traces formed on substrate  56 . Substrate  56  may be, for example, a printed circuit board substrate. A positive conductor in transmission line path  24  ( FIG. 1A ) may be coupled to positive antenna feed terminal  76  and a ground conductor in transmission line path  24  ( FIG. 1A ) may be coupled to ground antenna feed terminal  78 . Terminal  78  may be coupled to ground antenna patch  80  and terminal  76  may be coupled to patch  82  using a via at terminal  76 , lower layer conductive path  84 , and via  86 . 
     A cross-sectional side view of antenna probe  18  of  FIG. 7  taken along line  88  and viewed in direction  90  is shown in  FIG. 8 . 
       FIG. 9  is a top view of illustrative device structures under test  14  that include multiple structures to be tested (e.g., structures such as structures  14 A and  14 B at opposing ends of structures  14 , etc.). Structures  14 A and  14 B may be antenna structures (e.g., antenna resonating elements on flex circuits or other substrates that are attached to other circuitry in structures  14  using connectors as described in connection with connectors  40  and  38  of  FIG. 2 ). 
     When testing device structures under test such as device structures under test  14  of  FIG. 9 , it may be desirable to provide antenna probe  18  with multiple antennas each of which corresponds to a respective one of the antennas ( 14 A,  14 B) or other structures to be tested. An illustrative antenna probe that includes two antennas  18 A and  18 B for testing structures  14 A and  14 B in device structures under test  14  is shown in  FIG. 10 . As shown in  FIG. 10 , antenna probe  18  may include first probe antenna  18 A (e.g., a first loop antenna of the type shown in  FIG. 6 , a first dipole patch antenna of the type shown in  FIGS. 7 and 8 , or an antenna of another suitable type) and second probe antenna  18 B (e.g., a first loop antenna of the type shown in  FIG. 6 , a first dipole patch antenna of the type shown in  FIGS. 7 and 8 , or an antenna of another suitable type). Test unit  20  may be coupled to antennas using transmission line paths  24 A and  24 B. If desired, paths  24 A and  24 B may be coupled to a single vector network analyzer port using a signal combiner, paths  24 A and  24 B may be coupled to separate ports in one or more vector network analyzers or other suitable test equipment, and one or more radio-frequency switches may be used in conjunction with combiners or other radio-frequency components to interconnect one or more vector network analyzer ports to one or more different paths such as paths  24 A and  24 B. 
     During testing of device structures under test  14  of  FIG. 10 , antenna probe  18  may be placed in the vicinity of device structures under test  14  so that probe antenna  18 A is aligned with antenna or other structures  14 A and so that probe antenna  18 B is aligned with antenna or other structures  14 B. If desired, probe antenna  18  may be provided with additional antennas. For example, if there are three or more antennas or other structures to be wirelessly tested in device structures under test  14 , antenna probe  18  may be provided with three or more corresponding test antennas. 
     If desired, test system  10  may be used to test device structures such as electronic device housing structures.  FIG. 11A  is a top view of illustrative electronic device housing structures of the type that may be tested using test system  10 . As shown in  FIG. 11A , device structures under test  14  may include a partly formed electronic device (e.g., a cellular telephone, media player, computer, etc.) having a peripheral conductive housing member such as peripheral conductive housing member  92  and a planar conductive housing member such as planar conductive housing member  96 . Antennas  94  and  98  may be located at opposing ends of structures  14  (as an example). Planar conductive housing member  96  may be formed from one or more sheet metal members that are connected to each other by over-molded plastic and/or welds or other fastening mechanism. Planar conductive housing member  96  may be welded to the left and right sides of planar conductive housing member  92 . 
     Conductive housing members in device structures under test  14  may have structural features such as openings (e.g., air-filled or plastic-filled openings or other dielectric-filled openings that are used in reducing undesirable eddy currents produced by antenna  94  and/or antenna  98 ), peripheral shapes, three-dimensional shapes, and other structural features whose electromagnetic properties is altered when a fault is present due to faulty manufacturing and/or assembly operations. For example, conductive housing member  96  may have openings such as openings  108 . Openings  108  normally may have relatively short slots such a slots  102  and  104  that are separated by intervening portions of member  96 , such as portions  106 . Due to an error in manufacturing, member  96  portions  106  may be absent. In the example of  FIG. 11A , portions  106  are absent between a pair of slots, so the slots merged to form relatively long slot  100 . During test set-up operations, calibration measurements may be made on a properly fabricated version of member  96  (i.e., a version of member  96  where slot  100  is divided into two openings). Tester  12  may then be used to make S 11  and/or S 21  measurements. Illustrative S 11  measurements made in a frequency range of 0.7 GHz to 2.7 GHz on structures of the type shown in  FIG. 11A  are shown in  FIG. 11B  (plotted on a Smith chart). Solid line  230  corresponds to fault-free structures. Dashed line  232  corresponds to structures in the presence of a fault such as long slot  100 . A computer or other computing equipment in tester  12  may be used to compare the expected signature of device structures under test  14  to the measured data (e.g., S 11  and/or S 21  in magnitude, phase, or both magnitude and phase). If differences are detected, an operator may be instructed to rework or scrap structures  14  or other suitable actions may be taken. 
       FIG. 12  is a top view of illustrative device structures under test  14  that include welds  120 . In the example of  FIG. 12 , structures  14  may correspond to a partly assembled electronic device such as a partly assembled cellular telephone, computer, or media player (as examples). Structures  14  may include peripheral conductive housing member  114  and conductive planar housing member  122 . Member  122  may be separated from peripheral conductive housing member by dielectric-filled gap (opening)  110 . Conductive structures such as members  112 ,  116 , and  124  may be connected to each other by welds  120 . When welds  120  are formed properly, tester  12  will make S 11  measurements (or S 21  measurements) that match calibration results for properly welded structures. When welds  120  contain faults (e.g., one or more missing or incomplete welds or a broken weld), the test measurements may exhibit detectable changes relative to the calibration results. When such a change is detected, appropriate actions may be taken. For example, an operator may be alerted so that structures  14  may be reworked, inspected further using different testing equipment, or scrapped. 
     Device structures under test  14  may include components such as speakers, microphones, switches, buttons, connectors, printed circuit boards, cables, light-emitting devices, sensors, displays, cameras, and other components. These components may be attached to each other using springs and other electrical connection mechanisms. As shown in the illustrative arrangement of  FIG. 13 , a component such as component  124  (e.g., a speaker, microphone, camera, etc.) may be coupled to conductive traces  128  on printed circuit board substrate  126  using one, two, or more than two springs  130  or other conductive coupling mechanisms. If component  124  and board  126  are not assembled correctly, springs  130  may not make satisfactory electrical contact to traces  128 . Tester  12  may detect this change by using antenna probe  18  to make wireless test measurements on structures  14  and comparing the test measurements to calibration measurements on known properly assembled structures. If the test measurements differ from the expected measurements, appropriate actions may be taken. For example, an operator may be alerted so that structures  14  may be reworked, inspected further using different testing equipment, or scrapped. 
     Device structures under test  14  may include connectors. As shown in the illustrative example of  FIG. 14 , device structures under test  14  may include a printed circuit board such as printed circuit board  132 . Printed circuit board  132  may have conductive traces  140  such as metal lines  142  and metal ground structure  144  (as an example). Connector  134  on printed circuit board  132  may be coupled to traces  140 . 
     Device structures under test  14  may also include a flex circuit such as flex circuit  138  having conductive traces  148  that are coupled to connector  136 . Flex circuit  138  may be, for example, a cable that is used to convey signals from printed circuit board  132  to a display, printed circuit board, or other component in an electronic device. 
     When properly assembled, connector  136  of flexible printed circuit  138  mates with connector  134  of printed circuit board  132 . In this situation, each conductive line  148  may be electrically connected to a corresponding conductive line in traces  140  (as an example). In the presence of a fault such as an improperly connected or disconnected pair of connectors such as connectors  136  and  134  or breaks or shorts in traces  148  and  140 , the electromagnetic properties of device structures under test  14  may be altered. For example, in a properly assembled configuration, one or more ground lines in conductors  148  may be shorted to ground trace  144 , whereas in an improperly assembled configuration, trace  144  and the ground lines in conductors  148  may be electrically isolated. Tester  12  may detect faults in device structures under test such as structures  14  of  FIG. 14  and other structures that contain connectors by using antenna probe  18  to make wireless test measurements on structures  14  and comparing these test measurements to calibration measurements on a known properly assembled structure. In response to determining that the test measurements differ from expected measurements, appropriate actions may be taken such as alerting an operator that structures  14  should be inspected further, reworked, or scrapped. 
       FIG. 15  is a side view of illustrative electronic device structures that include surface height variations that may be tested using test system  12 . In the example of  FIG. 15 , device structures under test  14  include surface faults such as depression  246  and protrusion  242 . Device structures under test  14  of  FIG. 15  may be a device housing structure, a planar structure associated with a component, a metal plate, a printed circuit board, or other structure that is subject to potential surface faults during manufacturing. During testing, system  12  may detect protrusions such as protrusion  242  due to the shortened distance  244  between structures  14  and antenna probe  18  and due to the local change in surface area associated with protrusion  242 . System  12  may likewise detect depressions such a depression  246  due to the increase in distance  248  relative to the nominal distance ND between antenna probe  18  and structures  14  and due to the local change in surface area associated with depression  246 . 
       FIG. 16  is a side view of an illustrative electronic component such as surface mount assembly (SMA) structures  254  mounted to a substrate such as substrate  250  (e.g., a printed circuit board). This type of electronic device structure may be tested using antenna probe  18  and system  12 . When properly assembled, electronic component  260  will be attached to traces  252  on substrate  250  using solder balls  256 . In the presence of a fault such as gap  258 , the radio-frequency signature of device structures under test  14  will be different, which can be detected by system  12  (e.g., using S 11  and/or S 21  measurements). 
     In the example of  FIG. 17 , an electronic device component such as component  260  has been electromagnetically shielded using electromagnetic shielding can  262 . When properly assembled, springs such as spring  260  and/or solder such a solder  256 ′ may form electrical connections between can  262  and traces such as  52  (e.g., ground traces) on substrate  250 . In the presence of a fault such as an incomplete solder connection (shown as gap  258 ) or an incomplete spring connection (shown as gap  258 ′), system  12  can detect abnormal S 11  and/or S 21  characteristics. 
     As shown in  FIG. 18 , device structures under test  14  may include traces such as traces  264  and  266  on substrate  270 . Traces  262  and  264  may, for example, be part of a patterned metal layer that forms part of a transmission line or a digital bus or other signal path that interconnects electronic components within an electronic device. During testing to gather S 11  and/or S 21  measurements with antenna probe  18 , system  12  may detect the presence of faults such as shorts, opens, etc. In the example of  FIG. 18 , trace  264  contains an open fault due to the presence of gap  268 . 
       FIG. 19  is a cross-sectional side view of illustrative device structures under test  14  showing how faults in materials such as conductive foam layers may be detected using antenna probe  18 . In the  FIG. 19  example, device structures under test  14  include a flexible printed circuit “flex circuit” such as flex circuit  276 . Flex circuit  276  may contain traces such as traces  278 . Flex circuit  278  may be mounted on structure  270  using conductive foam  272 . Structure  270  may be a printed circuit board (e.g., a printed circuit board containing a ground plane trace, a metal shielding can, a planar metal housing structure for an electronic device, or other conductive structure). In the  FIG. 19  example, a fault such as bubble  274  is present, which changes the shape and size of conductive foam  272 . During testing with system  12 , system  12  may detect the presence of fault  274  through gathered S 11  and/or S 21  measurements. 
     In the example of  FIG. 20 , device structures under test  14  include a completed or partially assembled electronic device such as device  300 . Device  300  may have a display such as display  306 . A cover glass layer over the display may be provided with openings for button  308  and speaker port  310 . Peripheral conductive housing member  304  (e.g., a display bezel or housing sidewall member) may be formed from a conductive material such as metal. Structures such as dielectric gap  302  may be included in peripheral conductive housing member  304  and may affect the electromagnetic properties of device structures under test  14 . During the testing, antenna probe  18  may be placed in the vicinity of gap  302  (e.g., in the location indicated by dashed line  312 ). System  12  may detect the presence of a fault such as a faulty conductive structure that bridges and thereby shorts gap  302  using gathered S 11  and/or S 21  data. If desired, measurements of this type may be performed on peripheral conductive housing member  304  before peripheral conductive housing member  304  is attached to other device structures. 
     Device structures under test  14  may include electrical device structures such as illustrative speaker  320 . As shown in the cross-sectional side view of speaker  320  of  FIG. 21 , speaker  320  may include a diaphragm such as diaphragm  322 . Coils  328  may be attached to diaphragm  322  and may surround magnet  326 . Faults that may be measured by system  12  by gathering S 11  and/or S 21  using antenna probe  18  include coil faults such as a full or partial opening in coil  328  at location  332  and magnet faults such as erroneous magnet mounting location  330  (as examples). The testing of a speaker in the  FIG. 21  example is merely illustrative. Other components may be tested using tester  12  is desired. 
     Tester  12  may, in general, be used to test electronic device structures that include antennas, conductive structures such as conductive housing structures, connectors, springs, and other conductive structures that form electrical connections, speakers, shielding cans, solder-mounted components such as integrated circuits, transmission lines and other traces, layers of conductive foam, other electrical components, or any other suitable conductive structures that interact with transmitted radio-frequency electromagnetic signals. The foregoing examples are merely illustrative. 
     Illustrative steps involved in performing non-contact tests on device structures under test  14  using tester  12  of system  10  are shown in  FIG. 22 . 
     At step  150 , calibration operations may be performed on properly manufactured and assembled device structures. In particular, tester  12  may use antenna probe  18  to transmit and receive radio-frequency signals in a desired frequency range (e.g., from 0 Hz to 3 GHz, from 3-14 GHz, a subset of one of these frequency ranges, or another suitable frequency range). Signals corresponding to the transmitted signals may be received from the device structures under test and processed with the transmitted signals to obtain S 11  and/or S 21  measurements or other suitable test data. The S 11  and/or S 21  measurements or other test measurements that are made on the properly manufactured and assembled device structures may be stored in storage in tester  12  (e.g., in storage on a vector network analyzer, in storage on computing equipment such as a computer or network of computers in test unit  20  that are associated with the vector network analyzer, etc.). If desired, the device structures that are tested during the calibration operations of step  150  may be “limit samples” (i.e., structures that have parameters on the edge or limit of the characteristic being tested. Device structures of this type are marginally acceptable and can therefore be used in establishing limits on acceptable device performance during calibration operations. 
     At step  152 , one or more antennas in antenna probe  18  may be placed in the vicinity of device structures under test  14  (e.g., manually or using computer-controlled positioners such as positioners  16  and  32  of  FIG. 1A ). 
     At step  154 , tester  12  may use antenna probe  18  to gather test data. During the operations of step  154 , tester  12  may use antenna probe  18  to transmit and receive radio-frequency signals in a desired frequency range (e.g., from 0 Hz to 3 GHz, 3 GHz to 14 GHz, or other suitable frequency range, preferably matching the frequency range used in obtaining the calibration measurements of step  150 ). Wireless test data such as S 11  and/or S 21  measurements or other suitable test data may be gathered. The S 11  and/or S 21  measurements (phase and magnitude measurements for impedance and forward transfer coefficient) may be stored in storage in tester  12 . 
     At step  156 , the radio-frequency test data may be analyzed. For example, the test data that was gathered during the operations of step  154  may be compared to the baseline (calibration) data obtained during the operations of step  150  (e.g., by calculating the difference between these sets of data and determining whether the calculated difference exceeds predetermined threshold amounts, by comparing test data to calibration data from limit samples that represents limits on acceptable device structure performance, or by otherwise determining whether the test data deviates by more than a desired amount from acceptable data values). After computing the difference between the test data and the calibration data at one or more frequencies to determine whether the difference exceeds predetermined threshold values, appropriate actions may be taken. For example, if the test data and the calibration data differ by more than a predetermined amount, tester  12  may conclude that device structures under test  14  contain a fault and appropriate actions may be taken at step  160  (e.g., by issuing an alert, by informing an operator that additional testing is required, by displaying information instructing an operator to rework or scrap the device structures, etc.). If desired, visible messages may be displayed for an operator of system  12  at step  160  using display  200 . In response to a determination that the test data and the calibration data differ by less than the predetermined amount, tester  12  may conclude that device structures under test  14  have been manufactured and assembled properly and appropriate actions may be taken at step  158  (e.g., by issuing an alert that the structures have passed testing, by completing the assembly of the structures to form a finished electronic device, by shipping the final assembled electronic device to a customer, etc.). If desired, visible messages may be displayed for an operator of system  12  at step  158  using display  200 . 
     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: 20110422
Publication Date: 20140930
Grant Date: 20140930
Priority Date: 20110422
Inventors: NICKEL JOSHUA G.
GAVIN JONATHAN P. G.
Assignee: APPLE INC
CPC Classifications: [{"code": "G01R31/265", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01R31/3025", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R31/3025", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 47020820