Patent Application
20130015870
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. 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.
A 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, cables connected to the connectors, 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 radio-frequency test signals generated using the 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 a contact (or wired) test probe. The contact test probe may include at least signal and ground pins for making physical contact at desired locations on the device structures under test.
During testing, one or more contact test probe may be used to probe 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 to perform conducted testing. The test probe may receive corresponding radio-frequency signals from the device structures under test. For example, the test probe may 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 (when two or more test probes are used). 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 present invention, its nature and various advantages will be more apparent from the accompanying drawings and the following 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
Tester 12 may include a test unit such as test unit 20 and one or more test probes such as test probe 18. Test probe 18 may be used to convey radio-frequency test signals 26 to device structures 14 and to receive corresponding radio-frequency signals 28 from device structures under test 14. Signals 26 and 28 may be processed to compute complex impedance data (sometimes referred to as S11 parameter data) or other suitable data for determining whether device structures 14 contain a fault.
During testing, test probe 18 may be placed in physical contact with device structures under test 14 (e.g., to perform conducted radio-frequency testing). For example, test probe 18 may include first and second probe pins 17 and 19 configured to make contact at desired locations on device structures under test 14. Pins 17 and 19 may serve as signal and ground pins, respectively. At least one of pins 17 and 19 may be spring-loaded to reduce the chance of damaging test equipment 12 and device structures under test 14. Test probe 18 of this type may sometimes be referred to as a pogo-pin test probe. If desired, test probes such as alligator clip probes, tweezer probes, shielded-lead probes, or other types of test probes may be used in test system 10.
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. Fixture 31 may be configured to hold device structures under test 14 via pressure and/or friction on one or more sides of structures 14. Fixture 31 may be a robotically controlled fixture having automated alignment capabilities. 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 test 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 positioner such as positioner 16. Positioner 16 may include actuators for controlling horizontal and/or vertical movement of test probe 18 and/or device structures under test 14.
Test unit 20 may include signal generator equipment that generates radio-frequency test signals over a range of frequencies. These generated test signals may be provided to test probe 18 over radio-frequency cable 24 (e.g., a coaxial cable). Radio-frequency cable 24 may include an inner conductor that is coupled to signal pin 17 and an outer tubular conductor that is coupled to ground pin 19. The inner and outer conductors of cable 24 may be electrically isolated with dielectric material. In scenarios in which more than one test probe 18 is used to test device structures under test 14, multiple radio-frequency cables may be used to couple a respective one of the test probes to test unit 20.
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 test probe 18 or radio-frequency signals 28 that have passed through at least a portion of device structures under test 14). Using the transmitted and received signals 26 and 28, the magnitude and phase of the complex impedance (sometimes referred to as a reflection coefficient) of the device structures under test may be determined.
With one suitable arrangement, test unit 20 may be a vector network analyzer (VNA), a spectrum analyzer, or other radio-frequency tester and a computer that is coupled to the test unit 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.
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 S11 (complex impedance) measurement and/or an S21 (complex forward transfer coefficient) measurement. The values of S11 and S21 (phase and magnitude) may be measured as a function of signal frequency. In situations in which device structures under test 14 are fault free, S11 and S21 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 S11 and S21 measurements will exceed normal tolerances. When test unit 20 determines that the S11 and/or S21 measurements have deviated from normal S11 and S21 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 test 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, S11 and/or S21 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 (S11 phase an magnitude data) on device structures under test 14 may be made by transmitting radio-frequency signals with a test probe and receiving corresponding reflected radio-frequency signals from the device under test using the same test probe. Complex forward transfer coefficient measurements (S21 phase and magnitude data) on device structures under test 14 may be made by transmitting radio-frequency signals with a first test probe and receiving a corresponding set of radio-frequency signals from device structures under test 14 using a second test probe.
In one suitable arrangement, test system 10 may be used to test device components that are mounted on a circuit board. As shown in
Transceiver 34 may be coupled to an antenna resonating element such as antenna resonating element 42 through mating conductive pads 38 and 40 (sometimes referred to as flex pads). In general, transceiver 34 may be coupled to antenna resonating element via a spring, screw, conductive foam, radio-frequency conductors, or other suitable coupling mechanisms. Antenna resonating element 42 may form part of a loop antenna, inverted-F antenna, strip antenna, planar inverted-F antenna, slot antenna, hybrid antenna that includes antenna structures of more than one type, or other suitable antennas for transmitting and receiving radio-frequency signals for a wireless electronic device. Conductive pad 38 may be formed on the surface of board 32, whereas conductive pad 40 may be mounted on antenna resonating element 42. During conducted testing, of device structures under test 14, antenna resonating element 42 may be decoupled from transceiver 34 (e.g., by unmating pads 38 and 40).
Transceiver 34 may be coupled to pad 38 via at least one transmission line path. The transmission line path through which transceiver 34 and pad 38 are electrically coupled may include conductive traces such as traces 48 formed in at least one layer in board 32, radio-frequency cable 58, and other conduits for conveying radio-frequency signals. Radio-frequency connectors 60 and 62 may be attached to first and second ends of cable 58, respectively. Cable connector 60 may be mated to a corresponding connector 54 on board 32, whereas cable connector 62 may be mated to a corresponding connector 56 on board 32.
During device assembly, cable 58 may be attached to the on-board device structures by mating connectors 60 and 62 to the corresponding on-board connectors using automated tools or manually by assembly personnel. Test probe 18 may be used to test whether cable connectors 60 and 62 are seated properly within the corresponding mating connectors. For example, pins 17 and 19 may be placed in contact with pad 38 and ground pad 52 (e.g., a conductive pad that is coupled to ground path 44 through via 50), respectively at locations 78-1 and 78-2. While test probe 18 is in this mated state, test probe 18 may be used to transmit radio-frequency test signals to device structures under test 14 and to receive corresponding signals (e.g., reflected signals and/or signals that have pass through some of structures 14). Test results gathered in this way may indicate whether or not cable 58 is properly connected between transceiver 34 and conductive pad 38.
Exemplary test results gathered using test probe 18 in determining whether cable 58 is properly connected to board 32 are shown in
Initially, during calibration operations, test unit 20 may gather S11 measurements from device structures under test that are known to be fault free (e.g., from properly connected cables 58). When device structures under test 14 are fault free, the S11 measurements follow curves 64 of
If one or more faults are present, the S11 measurements made by tester 12 will deviate from curves 64 because the electromagnetic properties of structures 14 will be different than in situations in which structures 14 are free of faults. For example, an improperly-connected cable 58 will result in an impedance discontinuity in the transmission line path between transceiver 34 and pad 38. 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 (see, e.g., curve 66 in
The discrepancy between the shape of curve 66 and the known reference response (curve 64) in
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 of
In one suitable arrangement, test probe 18 may include an inner signal conductor 400 connected to pin 17 and an outer signal conductor 402 that is connected to pin 19 (see, e.g.,
In another suitable arrangement, test probe 18 may include a plastic probe housing portion such as plastic probe head 404′ attached to metal probe body 403 (see, e.g.,
In another suitable arrangement, test probe 18 may include a pin adjustment structure 408 within the probe housing. Pin adjustment structure 408 may allow for adjustment in the location of pin 19. For example, pin 19 may be moved from its current position to new position 410 (see, e.g.,
During test set-up operations, calibration measurements may be made on members 72 and 74 connected via a uniform conductive foam layer. Test 12 may then be used to make S11 and/or S21 measurements on partially assembled devices having conductive members 72 and 74 during production testing. A computer or other computing equipment in test 12 may be used to compare the expected signature of structures 14 to the measured data (e.g., S11 and/or S21 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. As shown in
If desired, test system 10 may be used to test device structures such as electronic device housing structures.
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. If desired, openings such as meshes of holes, grooves, or openings of any shape may be formed in member 96.
In the example of
When welds 120 are formed properly, tester 12 will make S11 measurements (or S21 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. As shown in
During test set-up operations, calibration measurements may be made on structures 14 having properly secured screw 84. Test 12 may then be used to make S11 and/or S21 measurements on partially assembled devices having members 73 and 74 during production testing. A computer or other computing equipment in test 12 may be used to compare the expected signature of structures 14 to the measured data (e.g., S11 and/or S21 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. As shown in
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
Tester 12 may detect this change by using test probe 18 to make contact with component 124 and trace 128 at respective locations 78-1 and 78-2 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.
In the example of
As shown in
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 contact tests on device structures under test 14 using tester 12 of system 10 are shown in
At step 150, calibration operations may be performed on properly manufactured and assembled device structures. In particular, tester 12 may use contact test 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 S11 and/or S21 measurements or other suitable test data. The S11 and/or S21 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, the signal and ground pins in test probe 18 may be placed in contact at desired locations on device structures under test 14 (e.g., manually or using computer-controlled positioners such as positioner 16 of
At step 154, tester 12 may use test probe 18 to gather test data. During the operations of step 154, tester 12 may use test 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). Conducted test data such as S11 and/or S21 measurements or other suitable test data may be gathered. The S11 and/or S21 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.
