Circuit board implantable temperature distribution monitoring system and fault positioning method

Abstract

The invention discloses a circuit board implantable temperature distribution monitoring system and a fault positioning method, and relates to the technical field of circuit board temperature distribution monitoring, and the system comprises a to-be-detected circuit board, a sensing optical fiber, a photoelectric integrated system, and a signal processing and data analysis unit. A plurality of groups of metal bonding pads are arranged on the surface of the to-be-tested circuit board; the sensing optical fiber is fixed on the metal bonding pad through a high-temperature solid sealing material, and a fiber grating array which is distributed in series is inscribed in a fiber core of the sensing optical fiber; the photoelectric integrated system is connected with the sensing optical fiber; and the signal processing and data analysis unit is in communication connection with the photoelectric integrated system. The sensing optical fiber is fixed on the metal bonding pad of the circuit board to be detected through the high-temperature sealing material, the two-dimensional temperature distribution cloud picture is generated based on temperature data and position information, correlation analysis is carried out on the temperature data and real-time electrical parameters, and in conclusion, the reliability of circuit board temperature distribution monitoring and the accuracy of fault positioning are jointly improved.

Description

Technical Field

[0001] This application relates to the field of circuit board temperature distribution monitoring technology, and in particular to a circuit board embedded temperature distribution monitoring system and fault location method. Background Technology

[0002] The temperature field distribution of a circuit board is one of the key factors affecting the basic functions and lifespan of the circuit, determining the reliability and safety of the product. The temperature field distribution of a circuit board is mainly determined by two factors: ambient temperature and the self-heating of the components. To promote the development of critical fields such as energy, defense, and aerospace, which have stringent requirements for circuit boards in high-reliability equipment, research is needed on temperature distribution monitoring systems and fault location methods.

[0003] In the prior art, Chinese patent CN114674457A discloses a printed circuit board temperature monitoring device and method. The device includes a laser module, an optical fiber circulator, a photoelectric detection module, and a printed circuit board temperature monitoring module. The laser module is used to emit a detection laser with a linearly changing wavelength in the time domain. The optical fiber circulator is used to receive the detection laser and introduce it into the printed circuit board temperature monitoring module. Each fiber Bragg grating sensor reflects different wavelengths of detection laser light to generate reflected light with different central reflection wavelengths. The reflected light enters the photoelectric detection module through the optical fiber circulator. The photoelectric detection module is used to receive all the reflected light and generate the position coordinates of each fiber Bragg grating sensor accordingly, and demodulate the temperature change information of the printed circuit board based on the changes in the position coordinates.

[0004] However, the aforementioned existing technologies do not take into account the situation where sensors are prone to loosening under high temperature and vibration environments, and it is also difficult to distinguish between ambient temperature rise and device fault heating. The reliability of circuit board temperature distribution monitoring and the accuracy of fault location are poor. Summary of the Invention

[0005] This application provides a circuit board embedded temperature distribution monitoring system and fault location method to solve the problems of existing circuit board temperature distribution monitoring technology not taking into account the situation where sensors are prone to loosening under high temperature and vibration environments, and also having difficulty distinguishing between ambient temperature rise and device fault heat generation, resulting in poor reliability of circuit board temperature distribution monitoring and poor accuracy of fault location.

[0006] On the one hand, this application provides a circuit board embedded temperature distribution monitoring system, including: a circuit board under test, a sensing optical fiber, an optoelectronic integrated system, and a signal processing and data analysis unit.

[0007] The surface of the circuit board under test is provided with several sets of metal pads; the sensing optical fiber is fixed to the metal pads by a high-temperature sealing material, and a series-distributed fiber grating array is engraved in the core of the sensing optical fiber; the optoelectronic integrated system is connected to the sensing optical fiber; the signal processing and data analysis unit is communicatively connected to the optoelectronic integrated system.

[0008] The fiber grating array is used to sense temperature changes in different areas of the circuit board under test.

[0009] The optoelectronic integrated system is used to emit probe light to the fiber grating array of the sensing fiber and receive reflected signals.

[0010] The signal processing and data analysis unit is configured to: demodulate the reflected signal to obtain wavelength data of each fiber grating in the fiber grating array; convert the wavelength data into temperature data and generate a two-dimensional temperature distribution cloud map of the circuit board under test by combining the position information of each fiber grating in the fiber grating array; perform correlation analysis between the temperature data and the real-time electrical parameters of the circuit board under test to establish a working condition linkage database; compare the real-time temperature and temperature rise rate in the temperature data with a preset threshold, trigger an alarm when the threshold is exceeded, and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map.

[0011] In one possible implementation, the metal pad has a groove, and the high-temperature sealing material is filled in the groove. The high-temperature sealing material is a high-temperature glass solder.

[0012] In one possible implementation, the sensing fiber is a polyimide-coated quartz fiber.

[0013] The fiber Bragg grating array is written by femtosecond laser, and the length of each fiber Bragg grating in the fiber Bragg grating array is adjustable.

[0014] In one possible implementation, the sensing fiber is subjected to negative prestress in the portion between each set of metal pads.

[0015] In one possible implementation, the signal processing and data analysis unit includes: a multi-wavelength demodulation and real-time tracking module, a temperature inversion and two-dimensional visualization module, a working condition linkage analysis module, and an early warning and fault location module.

[0016] The multi-wavelength demodulation and real-time tracking module is used to demodulate the reflected signal and obtain the wavelength data of each fiber grating in the fiber grating array.

[0017] The temperature inversion and two-dimensional visualization module is used to convert the wavelength data into temperature data and generate a two-dimensional temperature distribution cloud map of the circuit board under test by combining the position information of each fiber grating in the fiber grating array.

[0018] The operating condition linkage analysis module is used to perform correlation analysis between the temperature data and the real-time electrical parameters of the circuit board under test, and to establish an operating condition linkage database.

[0019] The early warning and fault location module is used to compare the real-time temperature and temperature rise rate in the temperature data with a preset threshold, trigger an alarm when the threshold is exceeded, and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map.

[0020] In one possible implementation, the multi-wavelength demodulation and real-time tracking module is also used to identify and remove high-frequency abnormal data in the wavelength data.

[0021] In one possible implementation, the temperature inversion and two-dimensional visualization module uses the position information of each fiber grating in the fiber grating array to generate a two-dimensional temperature distribution cloud map of the circuit board under test using an interpolation algorithm. The color gradient of the cloud map corresponds to the temperature range, and the cloud map refresh frequency is synchronized with the data acquisition frequency.

[0022] In one possible implementation, the signal processing and data analysis unit further includes a data storage and backtracking module.

[0023] The data storage and backtracking module is used to store temperature data, electrical parameters, alarm records, and two-dimensional temperature distribution cloud maps, and supports querying and exporting by time, device, or fault type.

[0024] On the other hand, this application provides a circuit board fault location method, using the above-mentioned circuit board embedded temperature distribution monitoring system, including the following steps: Step 1: Place the circuit board under test, which integrates a fiber optic grating array, into the programmable temperature control chamber and connect the circuit to raise the temperature of the chamber to reach the target ambient temperature.

[0025] Step two: The optoelectronic integrated system emits probe light to the fiber Bragg grating array and receives the reflected signal.

[0026] Step 3: Demodulate the reflected signal to obtain the wavelength data of each fiber grating in the fiber grating array; convert the wavelength data into temperature data, and combine it with the position information of each fiber grating in the fiber grating array to generate a two-dimensional temperature distribution cloud map of the circuit board under test.

[0027] Step four: Compare the real-time temperature and temperature rise rate in the temperature data with a preset threshold. If the threshold is exceeded, trigger an alarm and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map. Combine the working condition linkage database to determine the type of abnormal heating and preliminarily identify suspected faulty devices.

[0028] In one possible implementation, step four is followed by: Step 5: If the circuit board under test needs to be put into practical application, first cut off the area connecting the sensing fiber to the optoelectronic integrated system, perform potting treatment, and then install it in the industrial scene; when a fault alarm occurs in the industrial scene, reconnect the cut sensing fiber to the optoelectronic integrated system using a miniature fusion splicing tool, and repeat steps 2 to 4 after powering on. Compare the two-dimensional temperature distribution cloud map before and after the fault to locate and verify the faulty device.

[0029] The circuit board-embedded temperature distribution monitoring system and fault location method disclosed in this application have the following advantages: By fixing the sensing fiber to the metal pads of the circuit board under test using a high-temperature sealing material, long-term in-situ high-temperature monitoring of the circuit board was achieved. A two-dimensional temperature distribution cloud map was generated based on temperature data and location information, enabling visualization of the temperature distribution. Correlation analysis between temperature data and real-time electrical parameters allowed for the differentiation between ambient temperature rise and device fault-induced heating. These combined improvements enhanced the reliability of circuit board temperature distribution monitoring and the accuracy of fault location.

[0030] The proposed sensing fiber uses polyimide-coated quartz fiber, which improves the speed at which the fiber core reaches thermal equilibrium and enhances the real-time performance of temperature measurement. The fiber grating array is written by femtosecond laser, which is not easily erased at high temperatures, thus having better high-temperature resistance. The length of each fiber grating in the fiber grating array is adjustable to match the test areas of different sizes on the circuit board under test, adapting to the compact component layout space on the millimeter scale.

[0031] The proposed sensing fiber has a negative prestress applied between each set of metal pads to counteract the positive stress caused by factors such as vibration and thermal expansion and contraction of the circuit board. A stress buffer zone is reserved so that the grating wavelength drift is only affected by temperature changes.

[0032] The proposed multi-wavelength demodulation and real-time tracking module is also used to identify and remove high-frequency abnormal data in wavelength data, thereby improving the effectiveness of wavelength data.

[0033] The proposed temperature inversion and two-dimensional visualization module utilizes the position information of each fiber grating in the fiber grating array and uses an interpolation algorithm to generate a two-dimensional temperature distribution cloud map of the circuit board under test. The color gradient of the cloud map corresponds to the temperature range, and the cloud map refresh frequency is synchronized with the data acquisition frequency, thereby improving the reliability of the two-dimensional temperature distribution cloud map. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of a circuit board-embedded temperature distribution monitoring system provided in an embodiment of this application; Figure 2 A schematic diagram illustrating the application of negative prestress to the sensing fiber provided in an embodiment of this application; Figure 3 The response curve of wavelength data versus temperature data provided in the embodiments of this application; Figure 4 This is a flowchart illustrating a circuit board fault location method provided in an embodiment of this application.

[0036] Explanation of reference numerals in the attached figures: 1-Sensing fiber, 2-Metal pad, 3-Fiber Bragg grating, 4-Integrated unit, 5-Two-dimensional visualization terminal. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] like Figure 1 As shown in the figure, this application provides a circuit board embedded temperature distribution monitoring system, including: a circuit board under test, a sensing optical fiber 1, an optoelectronic integrated system, and a signal processing and data analysis unit.

[0039] The surface of the circuit board under test is provided with several sets of metal pads 2; the sensing optical fiber 1 is fixed to the metal pads 2 by a high-temperature sealing material, and a series-distributed fiber grating array is engraved in the core of the sensing optical fiber 1; the optoelectronic integrated system is connected to the sensing optical fiber; the signal processing and data analysis unit is communicatively connected to the optoelectronic integrated system.

[0040] The fiber grating array is used to sense temperature changes in different areas of the circuit board under test.

[0041] The optoelectronic integrated system is used to emit probe light to the fiber grating array of the sensing fiber 1 and receive reflected signals.

[0042] The signal processing and data analysis unit is configured to: demodulate the reflected signal to obtain wavelength data of each fiber grating 3 in the fiber grating array; convert the wavelength data into temperature data and generate a two-dimensional temperature distribution cloud map of the circuit board under test by combining the position information of each fiber grating 3 in the fiber grating array; perform correlation analysis between the temperature data and the real-time electrical parameters of the circuit board under test to establish a working condition linkage database; compare the real-time temperature and temperature rise rate in the temperature data with a preset threshold, trigger an alarm when the threshold is exceeded, and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map.

[0043] For example, the metal pad 2 has a groove, and the high-temperature sealing material is filled in the groove. The high-temperature sealing material is a high-temperature glass solder.

[0044] Specifically, in this embodiment, the softening temperature of the high-temperature glass solder is 800℃, and the long-term operating temperature after curing is 600℃. The sensing fiber 1 is fixed using the high-temperature glass solder, achieving a tight, gapless, and offset-free fit between the fiber Bragg grating array and the test area of ​​the circuit board under test, ensuring excellent heat conduction efficiency. The size of the metal pad 2 is precisely matched to the packaging structure of the sensing fiber 1, used to rigidly fix the sensing fiber 1 to the circuit board under test using the high-temperature glass solder. This fixing method avoids external application of additional residual stress to the fiber Bragg grating array of the sensing fiber 1, reducing cross-interference of non-measured components to the fiber Bragg grating 3.

[0045] For example, the sensing fiber 1 is a quartz fiber with a polyimide coating.

[0046] The fiber grating array is written by femtosecond laser, and the length of each fiber grating 3 in the fiber grating array is adjustable.

[0047] Specifically, the sensing fiber 1 is made of polyimide-coated quartz fiber (preferably with a diameter of 90.0 μm), which improves the speed at which the fiber core reaches thermal equilibrium and enhances the real-time performance of temperature measurement; the fiber grating array is written by femtosecond laser (8 to 32 fiber gratings 3), which is not easily erased at high temperatures and therefore has better high-temperature resistance; the length of each fiber grating 3 in the fiber grating array is adjustable to match the test areas of different sizes on the circuit board under test (each fiber grating 3 corresponds to a device under test or a certain area of ​​the circuit board), adapting to the compact component layout space on the millimeter scale.

[0048] For example, the sensing fiber 1 is subjected to negative prestress in the portion between each set of metal pads 2.

[0049] Specifically, such as Figure 2 As shown, the negative prestress of fiber grating 3 is applied through the following steps: The fiber grating 3 (corresponding) Figure 2The fiber segment of the grating (in the image) is pre-installed on two fixed pulleys (corresponding to...) Figure 2 Between pulleys 1 and 2 in the optical fiber, one end of which is connected to a tension meter. First, an axial tension is applied to the fiber segment to make it taut, and then the multi-wavelength demodulation and real-time tracking module (corresponding to) is used to achieve this. Figure 2 The optical fiber segment is monitored in real time using wavelength demodulation and tracking. When a positive wavelength shift is detected, it indicates that the fiber segment has entered a tensile state. Subsequently, the tension is gradually reduced so that the strain of the fiber segment returns from the tensile state to a predetermined negative value (preferably within the strain range of -2% to -5%). At this point, high-temperature glass solder is used to fix the fiber segment to a preset pad on the circuit board, thereby permanently locking the negative prestress in the fiber grating 3.

[0050] Specifically, such as Figure 3 The graph shows the response relationship between wavelength data and temperature data, including the linear fitting curve and the measured result curve. It can be seen that the reflected wavelength of fiber grating 3 has an approximately linear positive correlation with the ambient temperature. The temperature measurement range can cover room temperature to 200℃, and the temperature sensitivity is about 11.0 pm / ℃.

[0051] For example, the signal processing and data analysis unit includes: a multi-wavelength demodulation and real-time tracking module, a temperature inversion and two-dimensional visualization module, an operating condition linkage analysis module, and an early warning and fault location module.

[0052] The multi-wavelength demodulation and real-time tracking module is used to demodulate the reflected signal and obtain the wavelength data of each fiber grating 3 in the fiber grating array.

[0053] The temperature inversion and two-dimensional visualization module is used to convert the wavelength data into temperature data and generate a two-dimensional temperature distribution cloud map of the circuit board under test by combining the position information of each fiber grating 3 in the fiber grating array.

[0054] The operating condition linkage analysis module is used to perform correlation analysis between the temperature data and the real-time electrical parameters of the circuit board under test, and to establish an operating condition linkage database.

[0055] The early warning and fault location module is used to compare the real-time temperature and temperature rise rate in the temperature data with a preset threshold, trigger an alarm when the threshold is exceeded, and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map.

[0056] Specifically, Figure 1In the integrated unit 4, the multi-wavelength demodulation and real-time tracking module, the temperature inversion part of the temperature inversion and 2D visualization module, the operating condition linkage analysis module, and the early warning and fault location module are integrated into one unit. The 2D visualization terminal 5 is the 2D visualization part of the temperature inversion and 2D visualization module. It is connected to the integrated unit 4 through a communication interface. The 2D visualization terminal 5 intuitively presents the circuit board temperature distribution in the form of 2D temperature distribution cloud map, real-time data curve, etc., and also supports early warning threshold setting, data query and system control.

[0057] For example, the multi-wavelength demodulation and real-time tracking module is also used to identify and remove high-frequency abnormal data in the wavelength data.

[0058] Specifically, high-frequency abnormal data includes data such as instantaneous wavelength jumps caused by vibration.

[0059] For example, the temperature inversion and two-dimensional visualization module uses the position information of each fiber grating 3 in the fiber grating array to generate a two-dimensional temperature distribution cloud map of the circuit board under test using an interpolation algorithm. The color gradient of the cloud map corresponds to the temperature range, and the cloud map refresh frequency is synchronized with the data acquisition frequency.

[0060] Specifically, the position information of each fiber grating 3 is obtained from the device position parameters pre-entered into the circuit board CAD design.

[0061] For example, the signal processing and data analysis unit further includes a data storage and backtracking module.

[0062] The data storage and backtracking module is used to store temperature data, electrical parameters, alarm records, and two-dimensional temperature distribution cloud maps, and supports querying and exporting by time, device, or fault type.

[0063] like Figure 4 As shown, this application embodiment also provides a circuit board fault location method, using the above-described circuit board embedded temperature distribution monitoring system, including the following steps: Step 1: Place the circuit board under test, which integrates a fiber optic grating array, into the programmable temperature control chamber and connect the circuit to raise the temperature of the chamber to reach the target ambient temperature.

[0064] Step two: The optoelectronic integrated system emits probe light to the fiber Bragg grating array and receives the reflected signal.

[0065] Step 3: Demodulate the reflected signal to obtain the wavelength data of each fiber grating 3 in the fiber grating array; convert the wavelength data into temperature data, and combine the position information of each fiber grating 3 in the fiber grating array to generate a two-dimensional temperature distribution cloud map of the circuit board under test.

[0066] Step four: Compare the real-time temperature and temperature rise rate in the temperature data with a preset threshold. If the threshold is exceeded, trigger an alarm and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map. Combine the working condition linkage database to determine the type of abnormal heating and preliminarily identify suspected faulty devices.

[0067] For example, step four is followed by: Step 5: If the circuit board under test needs to be put into practical application, first cut off the area connecting the sensing fiber 1 to the optoelectronic integrated system, perform potting treatment, and then install it in the industrial scene; when a fault alarm occurs in the industrial scene, reconnect the cut sensing fiber 1 to the optoelectronic integrated system using a miniature fusion splicing tool, and repeat steps 2 to 4 after powering on, compare the two-dimensional temperature distribution cloud map before and after the fault, locate the faulty device, and verify it.

[0068] Specifically, in this embodiment, in step two, the optoelectronic integrated system emits probe light from the ASE light source, which is input into the sensing fiber 1 and propagates forward continuously. The fiber grating array in the sensing fiber 1 generates reflective signal light (i.e., reflected signal) due to temperature influence, and the wavelength of the signal light is related to temperature. Therefore, when the signal light is transmitted back to the photodetector, the emission of probe light and the reception of reflected signal are completed.

[0069] In step three, the photodetector transmits the reflected signal to the multi-wavelength demodulation and real-time tracking module. The multi-wavelength demodulation and real-time tracking module performs parallel demodulation and continuous tracking of the wavelength data of the reflected signal, extracts the real-time wavelength data of each fiber grating 3, and transmits it to the temperature inversion part of the temperature inversion and two-dimensional visualization module. The temperature inversion part converts the wavelength data into temperature data according to the "temperature-wavelength" calibration curve (obtained through pre-calibration). The temperature inversion part also interacts with the "temperature-electrical parameter" association library (i.e., the operating condition linkage database). This operating condition linkage database receives electrical parameters such as voltage, current, and power of the circuit board, realizing the timestamp alignment and multi-dimensional association between temperature data and electrical parameters. The processed data is synchronously stored in the local database and uploaded to the cloud server, completing the dual storage of data in the local and cloud environments. The temperature inversion section also transmits the temperature data and the position information of each fiber grating 3 in the fiber grating array to a two-dimensional visualization terminal. The two-dimensional visualization terminal displays the temperature distribution of the circuit board in a two-dimensional temperature distribution cloud map. At the same time, in step four, real-time temperature data, electrical parameter correlation curves and early warning information are integrated to facilitate users' overall control of the circuit board temperature status.

[0070] In step four, the temperature inversion part transmits the temperature data to the early warning and fault location module. The early warning and fault location module compares the real-time temperature and temperature rise rate with preset thresholds (such as the device rated temperature threshold and the fault temperature rise rate threshold). If the threshold is exceeded, an audible and visual alarm is triggered, and the fault area is highlighted in the two-dimensional temperature distribution cloud map on the two-dimensional visualization terminal to achieve accurate fault location.

[0071] In one possible embodiment, the hardware selection and fabrication of a circuit board-embedded temperature distribution monitoring system are as follows: Fabrication of sensing fiber 1: A single-mode quartz fiber with a cladding diameter of 90.0 μm and a core diameter of 10 μm is selected. A femtosecond laser writing system with a wavelength of 800 nm and a pulse width of 50 fs is used to write a 2 mm long fiber grating 3 in the fiber core. The grating period is designed to be 530 nm-550 nm. The fiber surface is coated with a 5 μm thick polyimide coating to form a high-temperature protective layer for the fiber. Each sensing fiber 1 contains 8-32 fiber gratings 3. The spacing of the fiber gratings 3 is set according to the distribution of circuit board devices (5 mm-50 mm). The two ends of the sensing fiber 1 are fused with standard FC / APC connectors to facilitate connection with optoelectronic integrated systems.

[0072] Circuit board pad design and fabrication: Based on the node position of the fiber grating array, a dedicated metal pad 2 is pre-designed during the PCB design stage. The size matches the packaging structure and fiber diameter of the sensing fiber 1. A 0.1mm deep groove is opened in the center of the metal pad 2 to accommodate high-temperature glass solder. At the same time, positioning marks are designed around the metal pad 2 to ensure spatial accuracy during fiber installation.

[0073] Optoelectronic integrated system: ASE light source and wavelength standard meter are selected, and parallel data acquisition is achieved through multi-channel modules (each channel corresponds to a fiber Bragg grating 3); the data acquisition card adopts an industrial-grade embedded motherboard, equipped with RS485 and Ethernet communication interfaces, used to connect the optoelectronic integrated system with the electrical parameter acquisition modules (such as current sensors and voltage sensors) of the circuit board under test; the motherboard has a built-in storage module to support local temporary data storage.

[0074] In one possible embodiment, the fiber optic implantation and system assembly process is as follows: Fiber Optic Positioning and Fixing: First, fix the circuit board under test (PCB) on the fixture platform. Based on the positioning marks on the metal pads 2, lay the sensing fiber 1 on the surface of the PCB, aligning each fiber Bragg grating 3 with the center of the corresponding monitoring device (such as an MCU, power transistor, or sensor). Then, use a dedicated tension fixture to apply negative prestress (the tension value is set according to the fiber material characteristics) to the portion of the sensing fiber 1 between each set of metal pads 2. Simultaneously monitor the change in the reflected wavelength of the fiber Bragg grating 3. When the wavelength stabilizes at the preset "stress compensation reference wavelength" (determined through wavelength calibration under stress-free conditions), lock the tension fixture. Place high-temperature glass solder into the groove of the metal pad 2, heat the metal pad 2 to soften the high-temperature glass solder and fill the gap between the metal pad 2 and the fiber, then allow it to cool naturally to room temperature, completing the fiber fixation. After fixation, inspect the fit between the fiber and the device surface using a microscope to ensure there are no gaps (gap ≤ 0.1 mm). At this point, a stable negative prestress state is formed inside the fiber, which can counteract the positive stress generated by subsequent environmental vibrations and thermal expansion and contraction.

[0075] Encapsulation process adaptation: If the circuit board under test needs to be encapsulated (waterproofing and corrosion resistance are required in downhole drilling scenarios), epoxy resin encapsulation adhesive should be selected. Before encapsulation, check the integrity of the polyimide coating in area 3 of the fiber optic grating to ensure that there is no damage. Vacuum encapsulation process is used during encapsulation to avoid air bubbles encasing the optical fiber. After encapsulation, curing is performed. After curing, the temperature sensing performance of fiber optic grating 3 is tested to ensure that the attenuation rate meets the requirements (the attenuation rate is calculated by comparing the wavelength response values ​​at the same temperature point before and after encapsulation).

[0076] System Connection and Debugging: Connect the FC / APC connector of the fiber Bragg grating array to the input channel of the optoelectronic integrated system. The optoelectronic integrated system is connected to the data acquisition motherboard via Ethernet, and the data acquisition motherboard is connected to the electrical parameter acquisition module via RS485 interface. After power-on, start the temperature inversion and two-dimensional visualization module and the operating condition linkage analysis module for system debugging: First, perform wavelength calibration (by placing the circuit board under test in a constant temperature chamber, setting temperature points of 50℃, 80℃, 110℃, 140℃, 170℃, 200℃, and 230℃, recording the wavelength values ​​of each fiber Bragg grating 3, and generating a temperature-wavelength calibration curve); then simulate the normal operating conditions of the circuit board (such as applying rated voltage and current), check whether the software can display the temperature of each node and the two-dimensional temperature distribution cloud map in real time, and verify whether the operating condition linkage analysis module can accurately correlate electrical parameters and temperature data; finally, simulate a fault scenario (such as a short circuit of a power transistor, causing local temperature rise), and test whether the early warning and fault location module can trigger the early warning in time and whether it can accurately mark the fault area.

[0077] In one possible embodiment, high-temperature reliability testing and performance verification are performed as follows: High-temperature environment simulation test: The assembled circuit board and monitoring system were placed in a high-temperature test chamber to simulate the operation of a downhole drilling environment. The temperature data (derived from wavelength) and two-dimensional temperature distribution cloud map of each fiber grating 3 were recorded sequentially. The test results showed that the temperature measurement error of each node was ≤0.3℃, the wavelength drift was ≤0.5pm / h, and the two-dimensional temperature distribution cloud map clearly reflected the superposition effect of passive heating caused by the high ambient temperature and active heating caused by the self-heating of the device. There was no data loss or abnormal interruption, verifying the stability of the system in a high-temperature and harsh environment.

[0078] Device Failure Simulation Test: Failure simulation is performed on typical devices (such as power MOSFETs) on the circuit board at room temperature (25℃). Overload fault – Apply 120% rated current, and the monitoring system records temperature changes in real time – When the power tube temperature rises from 25℃ to 85℃ (temperature rise rate 3℃ / min), an alarm is triggered when the alarm threshold (90℃) is reached, with a positioning accuracy of ±1.5mm; Short circuit fault – Directly short-circuit the device pins, and the temperature rises to 150℃ within 5 seconds (temperature rise rate 150℃ / s). The system immediately triggers an alarm and accurately locates the faulty device, which is completely consistent with the actual fault location.

[0079] Meanwhile, the operating condition linkage analysis module accurately distinguishes two types of fault characteristics through the "temperature-current" correlation curve: overload faults are characterized by a slow increase in temperature with current, while short circuit faults are characterized by a sudden increase in current accompanied by an instantaneous surge in temperature, thus solving the pain point of traditional monitoring that "cannot distinguish between passive heating and active heating".

[0080] In this embodiment, the sensing fiber optic cable 1 is fixed to the metal pad 2 of the circuit board under test using a high-temperature sealing material, enabling long-term in-situ high-temperature monitoring of the circuit board. A two-dimensional temperature distribution cloud map is generated based on temperature data and location information, achieving visualization of the temperature distribution. Correlation analysis between temperature data and real-time electrical parameters distinguishes between ambient temperature rise and device fault heating. All these improvements enhance the reliability of circuit board temperature distribution monitoring and the accuracy of fault location.

[0081] The proposed sensing fiber 1 uses polyimide-coated quartz fiber, which improves the speed at which the fiber core reaches thermal equilibrium and enhances the real-time performance of temperature measurement. The fiber grating array is written by femtosecond laser, which is not easily erased at high temperatures, thus having better high-temperature resistance. The length of each fiber grating 3 in the fiber grating array is adjustable to match the test areas of different sizes on the circuit board under test, adapting to the compact component layout space on the millimeter scale.

[0082] The proposed sensing fiber 1 has a negative prestress applied between each set of metal pads 2 to counteract the positive stress caused by factors such as vibration and thermal expansion and contraction of the circuit board, and a stress buffer is reserved so that the grating wavelength drift is only affected by temperature changes.

[0083] The proposed multi-wavelength demodulation and real-time tracking module is also used to identify and remove high-frequency abnormal data in wavelength data, thereby improving the effectiveness of wavelength data.

[0084] The proposed temperature inversion and two-dimensional visualization module utilizes the position information of each fiber grating 3 in the fiber grating array and uses an interpolation algorithm to generate a two-dimensional temperature distribution cloud map of the circuit board under test. The color gradient of the cloud map corresponds to the temperature range, and the cloud map refresh frequency is synchronized with the data acquisition frequency, thereby improving the reliability of the two-dimensional temperature distribution cloud map.

[0085] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0086] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A temperature distribution monitoring system for a circuit board, characterized by The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board.

2. The circuit board-implanted temperature distribution monitoring system according to claim 1, wherein The application relates to a temperature monitoring system for a circuit board.

3. The circuit board-implanted temperature distribution monitoring system according to claim 1, wherein The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board.

4. The circuit board-implanted temperature distribution monitoring system according to claim 1, wherein The application relates to a temperature monitoring system for a circuit board.

5. The circuit board-implanted temperature distribution monitoring system according to claim 1, wherein The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board.

6. The circuit board-implanted temperature distribution monitoring system according to claim 5, wherein The application relates to a temperature monitoring system for a circuit board.

7. The circuit board-implanted temperature distribution monitoring system according to claim 5, wherein The application relates to a temperature monitoring system for a circuit board.

8. The circuit board-implanted temperature distribution monitoring system of claim 1, wherein, The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring system for a circuit board. The application relates to a temperature monitoring The data storage and backtracking module is used for storing temperature data, electrical parameters, alarm records and two-dimensional temperature distribution cloud maps, and supports query and export according to time, device or fault type.

9. A method for locating a fault in a circuit board using a temperature distribution monitoring system according to any one of claims 1 to 8, wherein The method comprises the following steps: Step one, place the circuit board to be tested integrated with the fiber grating array into the programmable temperature control box and connect the circuit, and make the temperature control box heat up to reach the target environment temperature; Step two, the photoelectric integrated system emits probe light to the fiber grating array and receives the reflected signal; Step three, demodulate the reflected signal to obtain the wavelength data of each fiber grating in the fiber grating array; Convert the wavelength data into temperature data, and generate a two-dimensional temperature distribution cloud map of the circuit board to be tested combined with the position information of each fiber grating in the fiber grating array; Step four, compare the real-time temperature and temperature rise rate in the temperature data with the preset threshold value, trigger an alarm when the threshold value is exceeded, and locate the abnormal heating area based on the two-dimensional temperature distribution cloud map; combined with the working condition linkage database, judge the abnormal heating type, and preliminarily lock the suspected faulty device.

10. The method of claim 9, wherein, Step four also includes: Step five, if the circuit board to be tested needs to be put into actual application, first cut off the area where the sensing optical fiber is connected to the photoelectric integrated system, and then install it in the industrial scene after encapsulation treatment; when a fault alarm occurs in the industrial scene, reconnect the cut sensing optical fiber to the photoelectric integrated system through a miniature fusion tool, and repeat steps two to four after power on, compare the two-dimensional temperature distribution cloud maps before and after the fault, locate the faulty device and verify.

Images