Camera module electrical testing platform and testing method

Abstract

The invention aims to provide a camera module electrical testing platform and a testing method. The device comprises a to-be-tested product and a test base plate, the test base plate is connected with a power supply, a multi-channel SMU measurement module, a digital bridge LCR measurement module, a micro-current constant current source, a core processing plate and an industrial personal computer, and the to-be-tested product is connected to the test base plate through a test adapter plate; the multi-channel SMU measurement module comprises a first 24-bit ADC circuit, a 16-bit DAC circuit, a constant voltage source circuit, an electronic load circuit and a switching circuit, the core processing board is connected with the first 24-bit ADC circuit and the 16-bit DAC circuit, the 16-bit DAC circuit is connected with the constant voltage source circuit and the electronic load circuit, and the switching circuit is connected with the constant voltage source circuit and the electronic load circuit. The constant voltage source circuit is connected with the first 24-bit ADC circuit through the switching circuit, and the constant voltage source circuit, the electronic load circuit and the switching circuit are all connected with the product to be tested. The invention is applied to the technical field of camera module testing.

Description

Technical Field

[0001] The present invention is applied to the technical field of camera module testing, and particularly relates to an electrical testing platform and a testing method for camera modules. Background Art

[0002] With the continuous progress of technology, camera modules have become indispensable components in multiple fields such as smartphones, automotive electronics, security monitoring, and medical imaging. The core components of these modules include image sensors, optical lenses, image signal processors, and interface circuits. In order to ensure that the performance of the Camera Module meets industry standards, such as ISO 12233 image resolution testing and EMVA1288 sensor performance standards, strict electrical and optical performance tests need to be carried out through an electrical testing platform. The test parameters include electrical characteristics, optical performance, and environmental adaptability.

[0003] Existing Camera Module testing platforms face multiple challenges, including protocol parsing of high-speed data interfaces, improvement of the efficiency of multi-parameter parallel testing, and precise control of the testing environment. The existing testing platforms on the market are mainly based on the following implementation schemes: 1. NIPXI platform: Based on modular PXI hardware and LabVIEW / TestStand software, it supports custom testing processes, but the system setup is complex and the cost is relatively high.

[0004] 2. Chroma 1910 camera testing system: Designed specifically for optical testing, but it is weak in electrical testing capabilities and requires additional equipment to support interface protocol testing.

[0005] 3. Teradyne UltraFLEX testing system: Oriented towards semiconductor ATE, supporting high-parallel testing, but focusing on wafer-level testing, with an extremely high system cost.

[0006] 4. Keysight PathWave test automation software: A software-centered platform, compatible with multi-brand instruments, but relying on external hardware integration and having limited real-time performance.

[0007] These solutions perform excellently in specific fields, but they have deficiencies in cross-field integration capabilities, cost control, and flexibility. In the prior art, testing platforms are often designed specifically for a specific model or several similar models of Camera Modules, resulting in poor compatibility and difficulty in adapting to the testing requirements of different models or new-generation Camera Modules. Therefore, it is necessary to provide an electrical testing platform and a testing method for camera modules, which are low-cost, modular, highly compatible, and can adapt to various different models and generations of camera modules, facilitating the improvement of testing efficiency and shortening of the testing cycle. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a camera module electrical measurement platform and a test method, which are low in cost, modular, and high in compatibility, can adapt to various camera modules of different models and generations, are beneficial to improving the test efficiency, and shortening the test cycle.

[0009] The technical solution adopted by the present invention is as follows: The present invention includes a product under test and a test base plate. The test base plate is connected with a power supply, a multi-channel SMU measurement module, a digital bridge LCR measurement module, a micro-current constant current source, a core processing board, and an industrial control computer. The product under test is connected to the test base plate through a test adapter board. The multi-channel SMU measurement module includes a first 24-bit ADC circuit, a 16-bit DAC circuit, a constant voltage source circuit, an electronic load circuit, and a switching circuit. The core processing board is connected to the first 24-bit ADC circuit and the 16-bit DAC circuit. The 16-bit DAC circuit is connected to the constant voltage source circuit and the electronic load circuit. The constant voltage source circuit is connected to the first 24-bit ADC circuit through the switching circuit. The constant voltage source circuit, the electronic load circuit, and the switching circuit are all connected to the product under test.

[0010] As can be seen from the above solution, the camera module electrical measurement platform is a highly modular and highly compatible test platform, which can adapt to various Camera Modules of different models and generations. By adopting advanced test technologies and automated control strategies, the test efficiency is improved and the test cycle is shortened. Through modular design in this application, when the Camera Module is updated, only some modules need to be replaced, which greatly reduces the upgrade cost. By integrating multiple SMU modules, LCR digital bridge modules, and constant current source modules, etc., compared with using the NI (National Instruments) PXI platform, this application has more channels, lower cost, and higher test efficiency. Compared with the Keysight PathWave test automation software, this application has lower cost, higher test efficiency, and a smaller volume; it is easy to achieve high-precision and accurate testing of various camera modules during mass production, and is also applicable to verification testing in the product R & D stage.

[0011] A preferred solution is that the digital bridge LCR measurement module includes a second 24-bit ADC circuit, a sine wave generator, a first voltage sine wave RMS conversion circuit, a second voltage sine wave RMS conversion circuit, and a current transimpedance amplifier. The core processing board is connected to the P terminal of the product under test through the sine wave generator. The core processing board is connected to the N terminal of the product under test through the second 24-bit ADC circuit, the first voltage sine wave RMS conversion circuit, and the current transimpedance amplifier. The second 24-bit ADC circuit is connected to the P terminal and the N terminal of the product under test through the second voltage sine wave RMS conversion circuit.

[0012] One preferred solution is that the test method includes power-on protection check, resistance test, LDO test, Driver function test, and capacitance test; the test method includes the following steps: Step A: After placing the product under test on the Socket of the test adapter board, first perform a power-on protection check. Power on the LDO and Driver, and measure the power-on voltage. If the supply voltage is inconsistent with the set voltage, subsequent test items will not be tested; among them, LDO refers to a low-dropout linear regulator, and Driver refers to the communication function test of a driver chip. Step B: After the power-on protection check passes, perform a resistance test. While the resistance item channels to be tested are opened, measure the voltage and current values, and determine whether the voltage and current values are within the corresponding range. If they are not within the range, the calculated value of the corresponding channel will be fed back as an error value; otherwise, the calculated value obtained by calculating the measured current and voltage will be fed back. Step C: After the resistance test is completed, generally perform an LDO test. The LDO test is divided into standby current, no-load detection, and load detection for sequential testing; among them, standby current refers to the standby current, that is, the static current, which is the current consumed by the device itself without being affected by external factors. Step D: Subsequently, for the Driver function test, after powering on the Driver IC, configure the measured values of the product under test through I2C. Step E: Finally, measure the capacitance of the product under test.

[0013] One preferred solution is that the resistance test includes DCR measurement and Open test. The DCR measurement refers to direct current impedance measurement, and the Open test refers to open circuit test. The DCR measurement is performed on both ends of the same signal of the product under test, and measures the resistance of the signal path. The Open test is to check whether there is an open circuit between different signals in the product under test. Since the impedance of the signal path is small, generally in the range of 0.001~5Ω, a constant current source mode is adopted for measurement; a constant current is provided by an electronic load, and the voltage V across both ends of the product under test and the current I of the entire loop are measured. The calculation formula is: Rx = V / I.

[0014] One preferred solution is that the resistance test further includes a Short test. The Short test refers to a short circuit test. The Short test is to check whether there is a short circuit between different signals in the product under test. Since the Short test involves the impedance between different signals, and its impedance is relatively large, generally above 1 MΩ, unless there are components such as resistors, capacitors, and diodes between two signals, the test adopts the voltage source mode, provides voltage through an operational amplifier, measures the voltage V across the DUT and the current I of the entire loop, and the calculation formula is: Rx = V / I.

[0015] A preferred solution is that the DCR measurement, the Open test, and the Short test can all test 16 groups of tests simultaneously, and achieve fast switching through the MUX matrix group, and process multiple test items in parallel. MUX refers to a multiplexer. The MUX matrix group includes a PIN Check Module and a MUX_V1; the PIN Check Module is mainly used to switch between 4 lines to achieve preliminary signal selection and switching; the MUX_V1 is used as a switching expansion matrix to further expand the signal switching function and achieve more complex signal routing. Among them, the PIN Check Module is a pin detection module, and the MUX_V1 is a matrix analog switch channel expansion module.

[0016] A preferred solution is that the digital bridge LCR measurement module is used to measure the parameters of electronic components. The electronic components include inductors, capacitors, and resistors. The test method includes LCR digital bridge measurement. The working principle of LCR digital bridge measurement is based on the automatic balance bridge method, and calculates the impedance by measuring the vector relationship between voltage and current; the second voltage sine wave RMS conversion circuit is used as the core excitation source. The core excitation source generates a sine wave excitation signal with adjustable frequency and amplitude. The signal is connected to both ends of the product under test through the excitation positive electrode and the excitation negative electrode, and the voltage value V1 across both ends of the product under test is measured through the detection positive electrode and the detection negative electrode; after measuring the current transimpedance amplifier at the back end of the LC, the voltage value V2 is measured, and the impedance Z calculation formula is: Description of the Drawings

[0017] Figure 1 is the system architecture diagram of the present invention; Figure 2 is the system block diagram of the multi-channel SMU measurement module; Figure 3 is the system block diagram of the digital bridge LCR measurement module; Figure 4 is the circuit structure diagram of the DCR measurement, the Open test, and the Short test; Figure 5 is the 1 / 16 structure diagram of the MUX matrix group; Figure 6 is the principle block diagram of the digital bridge LCR measurement module; Figure 7 is the schematic diagram of the Socket on the test adapter board for placing the product under test; Figure 8 is the system block diagram of the first part of the test base plate; Figure 9 is the system block diagram of the second part of the test base plate; Figure 10 is the circuit schematic diagram of the power protection; Figure 11 is the circuit schematic diagram of the micro-current constant current source. Detailed implementation manners

[0018] As Figures 1 to 2 shown, in this embodiment, the present invention includes a product under test 1 and a test base plate 2. The test base plate 2 is connected with a power supply 3, a multi-channel SMU measurement module 4, a digital bridge LCR measurement module 5, a micro-current constant current source 6, a core processing board 7, and an industrial computer 8. The product under test 1 is connected to the test base plate 2 through a test adapter board 19. The multi-channel SMU measurement module 4 includes a first 24-bit ADC circuit 9, a 16-bit DAC circuit 10, a constant voltage source circuit 11, an electronic load circuit 12, and a switching circuit 13. The core processing board 7 is connected to the first 24-bit ADC circuit 9 and the 16-bit DAC circuit 10. The 16-bit DAC circuit 10 is connected to the constant voltage source circuit 11 and the electronic load circuit 12. The constant voltage source circuit 11 is connected to the first 24-bit ADC circuit 9 through the switching circuit 13. The constant voltage source circuit 11, the electronic load circuit 12, and the switching circuit 13 are all connected to the product under test 1. The product under test 1 is the product under test 1.

[0019] As Figure 3 shown, in this embodiment, the digital bridge LCR measurement module 5 includes a second 24-bit ADC circuit 14, a sine wave generator 15, a first voltage sine wave RMS conversion circuit 16, a second voltage sine wave RMS conversion circuit 17, and a current transimpedance amplifier 18. The core processing board 7 is connected to the P terminal of the product under test 1 through the sine wave generator 15. The core processing board 7 is connected to the N terminal of the product under test 1 through the second 24-bit ADC circuit 14, the first voltage sine wave RMS conversion circuit 16, and the current transimpedance amplifier 18. The second 24-bit ADC circuit 14 is connected to the P terminal and the N terminal of the product under test 1 through the second voltage sine wave RMS conversion circuit 17.

[0020] As Figures 1 to 7As shown, in this embodiment, the test method includes power-on protection check, resistance test, LDO test, Driver function test, and capacitance test; the test method includes the following steps: Step A: After placing the product under test 1 in the Socket of the test adapter board 19, first perform a power-on protection check. Power on the LDO and Driver, and measure the power-on voltage. If the supply voltage is inconsistent with the set voltage, subsequent test items will not be tested; among them, LDO refers to a low-dropout linear regulator, and Driver refers to the communication function test of a driver chip. Step B: After the power-on protection check passes, perform a resistance test. While the resistance item channels to be tested are open, measure the voltage and current values, and determine whether the voltage and current values are within the corresponding range. If they are not within the range, the calculated value of the corresponding channel will be fed back as an error value; otherwise, the calculated value obtained by measuring the current and voltage will be fed back. Step C: After the resistance test is completed, generally perform an LDO test. The LDO test is divided into standby current, no-load detection, and load detection for testing in sequence; among them, standby current refers to the standby current, that is, the static current, which is the current consumed by the device itself without being affected by external factors. Step D: Subsequently, for the Driver function test, after powering on the Driver IC, configure the measured values of the product under test 1 through I2C. Step E: Finally, measure the capacitance of the product under test 1.

[0021] As Figure 4 shown, in this embodiment, the resistance test includes DCR measurement and Open test. The DCR measurement refers to direct current impedance measurement, and the Open test refers to open circuit test. The DCR measurement is performed on both ends of the same signal of the product under test, and measures the resistance of the signal path. The Open test is to check whether there is an open circuit between different signals in the product under test 1. Since the impedance of the signal path is small, generally in the range of 0.001~5Ω, a constant current source mode is used for measurement; a constant current is provided by an electronic load, and the voltage V at both ends of the product under test 1 and the current I of the entire loop are measured. The calculation formula is: Rx = V / I.

[0022] As Figure 4 shown, in this embodiment, the resistance test also includes a Short test. The Short test refers to a short circuit test. The Short test is to check whether there is a short circuit between different signals in the product 1 to be tested. Since the Short test involves the impedance between different signals, and its impedance is relatively large, generally above 1 MΩ, unless there are components such as resistors, capacitors, and diodes between two signals, the test adopts the voltage source mode. A voltage is provided by an operational amplifier, and the voltage V across the DUT and the current I in the entire loop are measured. The calculation formula is: Rx = V / I.

[0023] As Figure 5 shown, in this embodiment, the DCR measurement, the Open test, and the Short test can all test 16 groups of tests simultaneously. Through the MUX matrix group, rapid switching is achieved, and multiple test items are processed in parallel. MUX refers to a multiplexer. The MUX matrix group includes a PIN Check Module and a MUX_V1. The PIN Check Module is mainly used to switch between 4 lines to achieve preliminary signal selection and switching. The MUX_V1 serves as a switching expansion matrix to further expand the signal switching function and achieve more complex signal routing. Among them, the PIN Check Module is a pin detection module, and the MUX_V1 is a matrix analog switch channel expansion module. The MUX matrix group realizes 16 groups of parallel tests with the same structure, greatly improving the test efficiency. The MUX matrix group is divided into two parts. The PIN Check Module: mainly used to switch between 4 lines to achieve preliminary signal selection and switching. The MUX_V1: serves as a switching expansion matrix to further expand the signal switching function and achieve more complex signal routing. Through this design, the MUX matrix group can quickly switch 16 groups of test signals to achieve parallel testing.

[0024] As Figure 6 shown, in this embodiment, the digital bridge LCR measurement module 5 is used to measure the parameters of electronic components. The electronic components include inductors, capacitors, and resistors. The test method includes LCR digital bridge measurement. The working principle of LCR digital bridge measurement is based on the automatic balance bridge method, and the impedance is calculated by measuring the vector relationship between voltage and current. The second voltage sine wave RMS conversion circuit 17 serves as the core excitation source. The core excitation source generates a sine wave excitation signal with adjustable frequency and amplitude. The signal is connected to both ends of the product 1 to be tested through the excitation positive electrode HC and the excitation negative electrode LC. The voltage value V1 across both ends of the product 1 to be tested is measured through the detection positive electrode HP and the detection negative electrode LP. The current transimpedance amplifier 18 is connected to a resistor Rr. After measuring the current transimpedance amplifier 18 at the back end of LC, the voltage value V2 is measured. The impedance Z calculation formula is: Through the above steps and calculations, the LCR digital bridge measurement can accurately measure the impedance parameters of electronic components, including resistance, inductance, capacitance values, as well as parameters such as their resonance frequencies and quality factors.

[0025] As Figure 7 shown, in this embodiment, after the camera module electrical measurement platform is connected according to the Figure 1 system architecture mode, it can be powered on and used. After placing the product under test 1 in the socket and ensuring it is properly placed, lock the socket upper cover. Click the start test button on the TM to start the test. After the test is completed, open the socket upper cover and remove the product under test 1; at the same time, display the data on the TM interface and store the data. TM is the test management platform.

[0026] In this embodiment, the camera module electrical measurement platform needs to perform system calibration. The purpose of calibration is to eliminate measurement errors caused by differences between devices and the accuracy of components within the device itself. Calibration of the test circuit, including errors due to component error accuracy within the circuit itself, long-term drift of the measurement chip, and temperature hysteresis, can all be solved through system calibration methods; 1. Calibration of resistance measurement: Use a high-precision resistor to calibrate the measured values of the digital multimeter 7510 and the measured values of the present invention to obtain calibration coefficients Kres_chx and Bres_chx.

[0027] 2. Calibration of voltage and current output and measurement: Use the measured values of the digital multimeter 7510, the measured values, and the output values of the present invention for calibration to obtain calibration coefficients KVolt_out_chx, BVolt_out_chx, KVolt_meas_chx, and BVolt_meas_chx.

[0028] 3. Calibration of capacitance measurement: Use the measured values of the LCR digital bridge E4980 and the measured values of the present invention for calibration to obtain calibration coefficients Kcap_chx and Bcap_chx.

[0029] As Figure 8 and Figure 9 shown, in this embodiment, the key to high-speed testing lies in using a high-speed switching method to control test conversion. Here, the system architecture and the test circuit protection circuit part are mainly introduced, including power supply, Domino / Domino pro module, Omega / Omega pro module, analog switch switching circuit, power protection circuit, etc. Figure 8 and 9Shown are miami sib and miami pro sib respectively. The corresponding module configurations are that the configuration corresponding to miami sib is domino and omega, and the configuration corresponding to miami pro sib is domino pro and omegapro. The module information, control bus signals and their directions used in the basic measurement part in the figure. Both miami sib and miami pro sib are the codes of the test base plate 2.

[0030] As Figure 10 shown, in this embodiment, the multi-channel SMU measurement module 4 is adopted in this application. When measuring simultaneously in multiple channels, overcurrent protection design is adopted to prevent excessive current from damaging the module. Three power supplies, -12V, 5V, and 12V, are used. Among them, the current capacities of 12V and 5V are 5A, and the current capacity of -12V is 3A. The power supply protection current is as Figure 10 shown.

[0031] As Figure 11 shown, in this embodiment, the design of the voltage-current converter is adopted in this application. INA105 is a differential amplifier. By feeding back the negative terminal voltage of the constant power supply resistor through LF356, the micro-current constant current source 6 is formed.

[0032] Although the embodiments of the present invention are described with actual solutions, they do not constitute a limitation to the meaning of the present invention. For those skilled in the art, it is obvious to modify its implementation solutions according to this specification and combine them with other solutions.

Claims

1. A camera module electrical testing platform, comprising a product to be tested (1), characterized in that: The camera module electrical test platform also includes a test base plate (2), the test base plate (2) is connected to a power supply (3), a multi-channel SMU measurement module (4), a digital bridge LCR measurement module (5), a micro-current constant current source (6), a core processing board (7), and an industrial computer (8), the product to be tested (1) is connected to the test base plate (2) via a test adapter board (19); the multi-channel SMU measurement module (4) includes a first 24-bit ADC circuit (9), a 16-bit DAC circuit (10), a constant voltage source circuit (11), an electronic load circuit (12) and a switching circuit (13), the core processing board (7) is connected to the first 24-bit ADC circuit (9) and the 16-bit DAC circuit (10), the 16-bit DAC circuit (10) is connected to the constant voltage source circuit (11) and the electronic load circuit (12), the constant voltage source circuit (11) is connected to the first 24 The electronic load circuit (12) and the switching circuit (13) are all connected to the product to be tested (1).

2. The camera module electrical measurement platform according to claim 1, characterized in that: The digital bridge LCR measurement module (5) comprises a second 24-bit ADC circuit (14), a sine wave generator (15), a first voltage sine wave RMS conversion circuit (16), a second voltage sine wave RMS conversion circuit (17), and a current quartz-resistance amplifier (18); the core processing board (7) is connected to the P terminal of the product to be tested (1) via the sine wave generator (15); the core processing board (7) is connected to the N terminal of the product to be tested (1) via the second 24-bit ADC circuit (14), the first voltage sine wave RMS conversion circuit (16), and the current quartz-resistance amplifier (18); and the second 24-bit ADC circuit (14) is connected to the P terminal and the N terminal of the product to be tested (1) via the second voltage sine wave RMS conversion circuit (17).

3. A method for testing a camera module electrical test platform as claimed in claim 2, characterized in that: The test method includes power-on protection check, resistance test, LDO test, Driver function test, and capacitance test; the test method includes the following steps: Step A, after placing the product to be tested (1) in the socket of the test adapter board (19), firstly perform a power-on protection check, power on the LDO and the Driver, and measure the power-on voltage. If the power supply voltage is inconsistent with the set voltage, no subsequent test items will be tested; wherein, LDO refers to a low voltage dropout linear regulator, and Driver refers to a driver chip communication function test; Step B, when the power-on protection check is passed, the resistance test is performed, and the resistance channel to be tested is opened at the same time, and the voltage and current values ​​are measured to determine whether the voltage and current values ​​are within the corresponding range. If not, the calculated value of the corresponding channel is fed back as the error value, otherwise, the calculated value obtained by calculating the measured current and voltage is fed back; Step C: After the resistance test is completed, the LDO test is generally performed. The LDO test is divided into standby current, no-load detection, and load detection. The standby current refers to the standby current, i.e., the static current, which is the current consumed by the device itself without being affected by external factors. Step D: Subsequently, for the Driver function test, the measurement value of the product to be tested (1) is configured through I2C after the Driver IC is powered on; Step E: Finally, measure the capacitance of the product to be tested (1).

4. The testing method according to claim 3, characterized in that: The resistance test includes DCR measurement and Open test, wherein the DCR measurement refers to DC impedance measurement and the Open test refers to open circuit test; The DCR measurement is performed on both ends of the same signal to be measured, and the resistance of the signal path is measured; The Open test is to check whether there is an open circuit between different signals in the product to be tested (1); Since the impedance of the signal path is relatively small, generally in the range of 0.001~5Ω, the constant current source mode is used for measurement; a constant current is provided by the electronic load, and the voltage V at both ends of the product to be tested (1) and the current I of the entire loop are measured, and the calculation formula is: Rx = V / I.

5. The testing method according to claim 4, characterized in that: The resistance test also includes a Short test, which refers to a short circuit test. The Short test is to check whether there is a short circuit between different signals in the product to be tested (1). Since the short test involves the impedance between different signals, the impedance is relatively large, generally above 1MΩ, unless there are components such as resistors, capacitors, and diodes between the two signals. The test adopts a voltage source mode, provides voltage through an operational amplifier, measures the voltage V at both ends of the DUT and the current I of the entire loop, and the calculation formula is: Rx = V / I.

6. The testing method according to claim 5, characterized in that: The DCR measurement, the Open test and the Short test can all test 16 groups of tests at the same time, and fast switching is achieved through the MUX matrix group to process multiple test items in parallel. MUX refers to a multiplexer. The MUX matrix group includes a PIN Check Module and MUX_V1; the PIN Check Module is mainly used to switch the 4 lines between each other to achieve preliminary signal selection and switching; the MUX_V1 is used as a switching extension matrix to further expand the signal switching function.

7. The testing method according to claim 3, characterized in that: The digital bridge LCR measurement module (5) is used to measure parameters of electronic components, wherein the electronic components include inductors, capacitors, and resistors. The test method includes LCR digital bridge measurement. The working principle of the LCR digital bridge measurement is based on the automatic balancing bridge method, and the impedance is calculated by measuring the vector relationship between voltage and current. The second voltage sine wave RMS conversion circuit (17) serves as a core excitation source. The core excitation source generates a sine wave excitation signal with adjustable frequency and amplitude. The signal is linked to the two ends of the product to be tested (1) through an excitation positive pole (HC) and an excitation negative pole (LC). The voltage value V1 at the two ends of the product to be tested (1) is measured and collected by measuring the positive pole (HP) and the negative pole (LP). The voltage value V2 is measured after measuring the current amplifier (18) at the rear end of LC. The impedance Z calculation formula is: 。

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