A circuit board soldering quality detection system

Abstract

The application discloses a circuit board welding quality detection system and relates to the technical field of circuit board detection; the application divides the circuit board image into regions according to function modules, analyzes the roundness of welding points for each subregion, compares the shape of the welding points with a reference sample to find abnormal welding points, matches the center coordinates of the welding points to calculate the deviation and determine position abnormal welding points, and accurately evaluates the welding quality from the shape and position, thereby avoiding the omission of general evaluation, improving the detection precision, and solving the problem that in the prior art, the welding quality of the circuit board is generally evaluated, the targeted evaluation cannot be performed on each function subregion of the circuit board, and the intelligent degree of quality detection is low.

Description

Technical Field

[0001] This application relates to the field of circuit board testing technology, and in particular to a circuit board soldering quality testing system. Background Technology

[0002] In the circuit board manufacturing process, the welding quality directly affects the performance and reliability of the circuit board. With the continuous improvement of circuit board integration, higher requirements are placed on the accuracy and efficiency of welding quality inspection.

[0003] However, existing circuit board soldering quality inspection systems still have the following shortcomings in practical applications:

[0004] Existing inspection systems only provide a broad and general assessment of the soldering quality of circuit boards, failing to conduct targeted analysis of each functional sub-region of the circuit board. Due to the significant differences in circuit structure and soldering process requirements among different functional modules on the circuit board, such as power modules, signal processing modules, and storage modules, the level of intelligence in quality inspection is low.

[0005] Furthermore, in terms of electrical performance evaluation, existing testing systems ignore the impact of transmission delay on circuit board performance. In high-speed circuits, if the transmission delay does not meet the requirements, it will lead to signal asynchrony, causing data transmission errors and system instability. On the other hand, the testing methods for component parameters such as resistors, capacitors, and inductors are not scientific and rigorous enough. They often simply measure a single value without considering measurement errors and random interference factors.

[0006] To address this, a circuit board soldering quality inspection system has been developed. Summary of the Invention

[0007] To address the problems mentioned in the background art, this application provides a circuit board welding quality inspection system.

[0008] The circuit board welding quality inspection system provided in this application adopts the following technical solution: A circuit board welding quality inspection system, comprising:

[0009] Quality inspection module: includes sample screening unit, welding analysis unit and electrical testing unit;

[0010] The sample screening unit is used to count the total number of circuit boards produced in the current batch, and to determine the sampling ratio of welding analysis samples and electrical test samples based on the total number range, thereby extracting the corresponding proportion of welding analysis samples and electrical test samples.

[0011] The welding analysis unit is used to acquire images of the extracted welding analysis samples and preprocess the acquired sample images of each group; after the preprocessing is completed, the sample images of each group are comprehensively analyzed to obtain the welding evaluation index hju of the current production batch of circuit boards.

[0012] The electrical testing unit is used to collect electrical parameters from the extracted electrical test samples. These electrical parameters include resistance, capacitance, inductance, and transmission delay. After the data collection is completed, the electrical parameters of each electrical test sample are comprehensively evaluated to obtain the electrical performance index hjr of the current production batch of circuit boards.

[0013] Optionally, the sampling ratio for welding analysis samples and electrical testing samples can be determined based on the total number range, specifically as follows:

[0014] The preset number of circuit boards corresponds to the range of each group of quantities, and each range of quantities corresponds to a sampling ratio set; the sampling ratio set includes the sampling ratios corresponding to the welding analysis samples and the electrical test samples respectively;

[0015] The total number of circuit boards produced in the current batch is matched with the preset range of each group to obtain the sampling ratio set of the circuit boards produced in the current batch; the total number of circuit boards produced in the current batch is multiplied by the sampling ratio of the welding analysis samples in the sampling ratio set to determine the number of welding analysis samples to be extracted.

[0016] The number of electrical test samples to be drawn is determined by multiplying the total number of circuit boards produced in the current batch by the sampling ratio of the electrical test samples within the sampling ratio set.

[0017] Optionally, after preprocessing, a comprehensive analysis of the images from each group of samples can be performed, specifically as follows:

[0018] Input a sample image of a circuit board with acceptable soldering quality in advance, as a reference quality sample for the current production batch of circuit boards;

[0019] Based on the pre-set division regions, each group of sample images is divided into various functional sub-regions;

[0020] For each functional sub-region of each group of sample images, extract the edge contour of the solder joint in each functional sub-region of each group of sample images, and obtain the roundness of each solder joint in each functional sub-region of each group of sample images.

[0021] From each functional sub-region of the reference quality sample, the roundness of each solder joint is extracted, and the roundness with the largest difference from the integer is taken as the passing roundness of each functional sub-region of the sample image.

[0022] The roundness of each solder joint in each functional sub-region of each group of sample images is compared with the corresponding acceptable roundness. If the roundness of a solder joint in a certain functional sub-region of a certain group of sample images is lower than the corresponding acceptable roundness, it is judged as an abnormal shape solder joint.

[0023] The number of abnormal weld points in each functional sub-region within each group of sample images is counted and recorded as the number of abnormal weld points. A weight coefficient is set for each functional sub-region corresponding to the number of abnormal weld points. The number of abnormal weld points in each functional sub-region within each group of sample images is multiplied by the corresponding weight coefficient, and then the sum is obtained to obtain the welding abnormality index of each group of sample images.

[0024] Optionally, the soldering evaluation index hju for the current production batch of circuit boards is obtained, specifically:

[0025] For the reference quality sample, obtain the geometric center of the contour of each solder joint, and use it as the center coordinate of each solder joint;

[0026] Simultaneously, the center coordinates of each solder joint in each group of sample images are obtained, and the center coordinates of each solder joint in each group of sample images are matched with the corresponding center coordinates of the solder joint in the reference quality sample. After the matching is completed, the solder joint pairs of each solder joint in each group of sample images are obtained, namely (solder joint center coordinates of sample image, center coordinates of reference solder joint).

[0027] For each group of weld points, calculate the difference on the horizontal and vertical axes respectively, and set the allowable position deviation thresholds corresponding to the horizontal and vertical axes respectively;

[0028] The difference between the horizontal and vertical coordinates of each group of solder joints is compared with the corresponding set allowable position deviation threshold. If there is a group of differences that are greater than the corresponding set allowable position deviation threshold, the solder joints that are greater than the allowable position deviation threshold are marked as solder joints with abnormal positions.

[0029] The number of abnormal weld points in each functional sub-region of each group of sample images is counted and recorded as the number of abnormal weld points. A weight coefficient is set for each functional sub-region corresponding to the number of abnormal weld points. The number of abnormal weld points in each functional sub-region of each group of sample images is multiplied by the corresponding weight coefficient, and then the sum is obtained to obtain the welding abnormal weld index of each group of sample images.

[0030] Extract the welding shape index and welding position index corresponding to each group of sample images, and label them as E1 and E2 respectively; according to the formula The welding shape index E1 and welding position index E2 of each group of sample images are weighted and calculated to obtain the welding effect index E3 corresponding to each group of sample images.

[0031] The average value of the welding effect index E3 of each group of sample images is taken to obtain the welding evaluation index hju of the current production batch of circuit boards.

[0032] Optionally, a comprehensive evaluation of the electrical parameters of each electrical test sample can be performed, specifically as follows:

[0033] The number of measurements G corresponding to the preset resistance, capacitance, and inductance values;

[0034] Based on the number of measurements G, the resistance, capacitance, and inductance values ​​of each electrical test sample in group G are obtained; and the average values ​​of the resistance, capacitance, and inductance values ​​of each electrical test sample in group G are calculated to obtain the comprehensive resistance, comprehensive capacitance, and comprehensive inductance values ​​of each electrical test sample.

[0035] Preset the nominal values ​​corresponding to the combined resistance, combined capacitance, and combined inductance values, and calculate the resistance deviation rate D. R Capacitor deviation rate D C and inductance deviation rate D L That is, through the formula The calculation yields R; 综合 and R 标称 These represent the combined resistance value and the corresponding preset nominal value, respectively. C 综合 and C 标称 These represent the combined capacitance value and the corresponding preset nominal value, respectively. L 综合 and L 标称 These represent the overall inductance value and the corresponding preset nominal value, respectively.

[0036] Set resistance deviation rate D R Capacitor deviation rate D C and inductance deviation rate D L The corresponding weighting coefficients will determine the resistance deviation rate D of each electrical test sample. R Capacitor deviation rate D C and inductance deviation rate D L Each component is multiplied by its corresponding weighting coefficient and then summed to obtain the component performance index Dt for each electrical test sample.

[0037] Optionally, the electrical performance index hjr of the current production batch of circuit boards can be obtained, specifically:

[0038] A set excitation signal is input to each electrical test sample. The time point of the input excitation signal is marked as the start point, and the time point of the output excitation signal is marked as the end point. The time difference between the start point and the end point is used as the transmission delay.

[0039] Set the number of times the excitation signal is input, and obtain the transmission delay of each electrical test sample corresponding to each input excitation signal. Calculate the average of the transmission delays of each group of electrical test samples to obtain the comprehensive transmission delay value De of each electrical test sample.

[0040] According to the formula The component performance index Dt and the comprehensive transmission delay value De of each electrical test sample are weighted and calculated to obtain the comprehensive electrical index Dy of each electrical test sample; where Da and Db are the preset allowable performance index and allowable delay value, respectively; β1 and β2 are the influence weight factors of component performance index Dt and comprehensive transmission delay value De, respectively.

[0041] The electrical performance index hjr of the current production batch of circuit boards is obtained by taking the average of the electrical comprehensive index Dy of each electrical test sample.

[0042] Optional, also includes:

[0043] Quality assessment module: Receives the soldering assessment index hju and electrical performance index hjr of the current production batch of circuit boards, and outputs the soldering quality level and electrical quality level of the current production batch of circuit boards, and sends the output soldering quality level and electrical quality level to the management personnel.

[0044] Optionally, output the soldering quality grade and electrical quality grade of the current production batch of circuit boards, specifically:

[0045] The system pre-defines the three sets of index value ranges corresponding to the welding evaluation index hju and the electrical performance index hjr. Each set of index value ranges corresponding to the welding evaluation index hju corresponds to a welding quality level, and each set of index value ranges corresponding to the electrical performance index hjr corresponds to an electrical quality level. The welding quality levels include poor welding, passable welding, and excellent welding, while the electrical quality levels include poor electrical, passable electrical, and excellent electrical.

[0046] The soldering evaluation index hju and electrical performance index hjr of the current production batch of circuit boards are matched with their corresponding index value ranges to determine the soldering quality level and electrical quality level of the current production batch of circuit boards.

[0047] In summary, this application includes at least one of the following beneficial technical effects:

[0048] This invention divides circuit board images into regions according to functional modules, analyzes the roundness of solder joints in each sub-region, compares with reference samples to find solder joints with abnormal shapes, and calculates the deviation by matching the center coordinates of the solder joints to determine the location of solder joints with abnormal positions. It accurately evaluates the welding quality from the shape and position, avoids the omissions of general evaluation, improves the detection accuracy, and solves the problem that most existing technologies only perform general evaluation of the welding quality of circuit boards and cannot perform targeted evaluation of each functional sub-region of the circuit board, resulting in a low level of intelligence in quality detection.

[0049] This invention measures resistance, capacitance, inductance, and transmission delay, takes the average of multiple measurements to calculate a comprehensive value, compares the deviation rate of the nominal value to evaluate component performance, and combines the transmission delay comprehensive value for weighted calculation to comprehensively and accurately evaluate the electrical performance of the circuit board, thus overcoming the one-sidedness of the existing technology.

[0050] This invention determines the sampling ratio based on the total number of circuit boards and extracts soldering and electrical test samples. The scientific sampling plan enables the samples to represent the quality of the entire batch. While ensuring the accuracy of the test, it greatly reduces the amount of testing, improves the overall production efficiency, and avoids the waste of time and resources in full inspection.

[0051] This invention calculates the welding effect index by measuring the welding shape index and welding position index, and takes the average value to obtain the welding evaluation index, which quantifies the welding quality and intuitively reflects the welding quality level of the circuit boards in the production batch. At the same time, it calculates the component performance index and the comprehensive value of transmission delay to obtain the electrical comprehensive index, and takes the average value to obtain the electrical performance index, which quantifies the electrical performance and provides accurate data support for electrical quality assessment. Attached Figure Description

[0052] Further details, features, and advantages of this application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0053] Figure 1 This is a schematic diagram of the principle of the present invention. Detailed Implementation

[0054] Several embodiments of this application will now be described in more detail with reference to the accompanying drawings to enable those skilled in the art to implement this application. This application may be embodied in many different forms and for various purposes and should not be limited to the embodiments set forth herein. These embodiments are provided to make this application thorough and complete, and to fully convey the scope of this application to those skilled in the art. The embodiments described do not limit this application.

[0055] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0056] Please see Figure 1 As shown, a circuit board soldering quality inspection system includes a quality inspection module and a quality assessment module.

[0057] The quality inspection module includes a sample screening unit, a welding analysis unit, and an electrical testing unit;

[0058] The sample screening unit is used to count the total number of circuit boards produced in the current batch, and to determine the sampling ratio of welding analysis samples and electrical test samples based on the total number range, thereby extracting the corresponding proportion of welding analysis samples and electrical test samples.

[0059] Specifically:

[0060] The preset number of circuit boards corresponds to the range of each group of quantities, and each range of quantities corresponds to a sampling ratio set; the sampling ratio set includes the sampling ratios corresponding to the welding analysis samples and the electrical test samples respectively;

[0061] The total number of circuit boards produced in the current batch is matched with the preset range of each group to obtain the sampling ratio set of the circuit boards produced in the current batch; the total number of circuit boards produced in the current batch is multiplied by the sampling ratio of the welding analysis samples in the sampling ratio set to determine the number of welding analysis samples to be extracted.

[0062] Multiply the total number of circuit boards produced in the current batch by the sampling ratio of electrical testing samples within the sampling ratio set to determine the number of electrical testing samples to be sampled.

[0063] It should be noted that performing soldering analysis and electrical testing on every circuit board would consume a lot of time and testing resources, leading to a significant decrease in production efficiency and a significant increase in testing costs. By determining the sampling ratio based on the total number of circuit boards for sampling testing, the workload of testing can be greatly reduced while ensuring a certain level of testing accuracy, thereby improving overall production efficiency and reducing testing costs.

[0064] The preset quantity range and corresponding sampling ratio set are based on scientific analysis and practical verification. Appropriate sampling ratios can be selected according to different production scales. In this way, the extracted welding analysis samples and electrical test samples can represent the quality status of the entire batch of circuit boards to a certain extent. Thus, the quality of the entire batch of products can be inferred from the test results of the samples, providing a reliable basis for quality control.

[0065] The welding analysis unit is used to acquire images of the extracted welding analysis samples. For each sample, a high-resolution industrial camera is used for multi-angle image acquisition. The camera's position, angle, and focal length are adjusted according to the circuit board's size and solder joint distribution to ensure clear and complete solder joint images. During acquisition, various lighting methods, such as ring lights and coaxial lights, are used to eliminate shadows and reflections, ensuring image quality. Preprocessing is performed on each set of sample images, including grayscale conversion, noise reduction, and contrast adjustment. After preprocessing, a comprehensive analysis of each set of sample images is conducted to obtain the welding evaluation index hju for the current production batch of circuit boards.

[0066] It should be noted that the original images acquired may contain noise, uneven lighting, and other issues. First, grayscale processing is performed to convert the color images into grayscale images, which facilitates subsequent calculations and analysis. Then, filtering algorithms, such as Gaussian filtering, are used to remove noise from the images and smooth them. At the same time, histogram equalization and other methods are used to adjust the brightness and contrast of the images and enhance the features of the solder joints in the images, making subsequent feature extraction and analysis more accurate.

[0067] Specifically:

[0068] Input a sample image of a circuit board with acceptable soldering quality in advance, as a reference quality sample for the current production batch of circuit boards;

[0069] Based on pre-defined regions, each group of sample images is divided into functional sub-regions. Regions are also divided according to different functional modules on the circuit board; for example, power modules, signal processing modules, and storage modules are each divided into separate regions. This division facilitates analysis of the welding conditions in different functional regions, as the circuit structures and soldering process requirements of different functional modules may vary.

[0070] For each functional sub-region of each group of sample images, the edge detection algorithm is used to extract the edge contour of the solder joint in each functional sub-region of each group of sample images, and the roundness of each solder joint in each functional sub-region of each group of sample images is obtained.

[0071] From each functional sub-region of the reference quality sample, the roundness of each solder joint with the largest difference from an integer is extracted and taken as the passing roundness of each functional sub-region of the sample image; that is, the lowest roundness of the solder joint in each functional sub-region.

[0072] The roundness of each solder joint in each functional sub-region of each group of sample images is compared with the corresponding acceptable roundness. If the roundness of a solder joint in a certain functional sub-region of a certain group of sample images is lower than the corresponding acceptable roundness, it is judged as an abnormal shape solder joint.

[0073] The number of abnormal weld points in each functional sub-region within each group of sample images is counted and recorded as the number of abnormal weld points. A weight coefficient is set for each functional sub-region corresponding to the number of abnormal weld points. The number of abnormal weld points in each functional sub-region within each group of sample images is multiplied by the corresponding weight coefficient, and then the sum is obtained to obtain the welding abnormality index of each group of sample images.

[0074] It should be noted that by dividing the circuit board image into different functional sub-regions and performing solder joint roundness analysis for each sub-region, the previous general evaluation of the circuit board as a whole has been changed, and a refined evaluation of soldering quality from different functional regions has been achieved.

[0075] For the reference quality sample, obtain the geometric center of the contour of each solder joint, and use it as the center coordinate of each solder joint;

[0076] Simultaneously, the center coordinates of each solder joint in each group of sample images are obtained, and the center coordinates of each solder joint in each group of sample images are matched with the corresponding center coordinates of the solder joint in the reference quality sample. After the matching is completed, the solder joint pairs of each solder joint in each group of sample images are obtained, namely (solder joint center coordinates of sample image, center coordinates of reference solder joint).

[0077] For each group of weld points, the difference between the horizontal and vertical axes is calculated separately. Based on the circuit board soldering process standards, set the allowable position deviation thresholds corresponding to the horizontal and vertical axes respectively;

[0078] The difference between the horizontal and vertical coordinates of each group of solder joints is compared with the corresponding set allowable position deviation threshold. If there is a group of differences that are greater than the corresponding set allowable position deviation threshold, the solder joints that are greater than the allowable position deviation threshold are marked as solder joints with abnormal positions.

[0079] The number of abnormal weld points in each functional sub-region of each group of sample images is counted and recorded as the number of abnormal weld points. A weight coefficient is set for each functional sub-region corresponding to the number of abnormal weld points. The number of abnormal weld points in each functional sub-region of each group of sample images is multiplied by the corresponding weight coefficient, and then the sum is obtained to obtain the welding abnormal weld index of each group of sample images.

[0080] It should be noted that by matching and calculating the difference between the center coordinates of each solder joint in the sample image and the corresponding center coordinates of the solder joint in the reference quality sample, solder joints that deviate from the standard can be accurately identified. This precise matching and calculation method avoids omissions and misjudgments that may occur during manual inspection, greatly improving the accuracy and efficiency of the inspection. Dividing the circuit board into different functional sub-regions for statistical analysis of solder joints with abnormal positions makes the localization of welding problems more precise.

[0081] Extract the welding shape index and welding position index corresponding to each group of sample images, and label them as E1 and E2 respectively; according to the formula The welding shape index E1 and welding position index E2 of each group of sample images are weighted and calculated to obtain the welding effect index E3 corresponding to each group of sample images.

[0082] The average value of the welding effect index E3 of each group of sample images is taken to obtain the welding evaluation index hju of the current production batch of circuit boards.

[0083] It should be noted that the average value of the welding effect index of each group of sample images is used to obtain the welding evaluation index of the current production batch of circuit boards, which can reflect the overall welding quality level of the production batch of circuit boards.

[0084] The electrical testing unit is used to collect electrical parameters from the extracted electrical test samples. These electrical parameters include resistance, capacitance, inductance, and transmission delay. After the data collection is completed, the electrical parameters of each electrical test sample are comprehensively evaluated to obtain the electrical performance index hjr of the current production batch of circuit boards.

[0085] Specifically:

[0086] The number of measurements G corresponding to the preset resistance, capacitance, and inductance values ​​is set by the technicians, where G > 3.

[0087] Based on the number of measurements G, the resistance, capacitance, and inductance values ​​of each electrical test sample in group G are obtained; and the average values ​​of the resistance, capacitance, and inductance values ​​of each electrical test sample in group G are calculated to obtain the comprehensive resistance, comprehensive capacitance, and comprehensive inductance values ​​of each electrical test sample; for resistance, capacitance, and inductance, the test clips of the LCR tester are connected to the two ends of the corresponding components respectively, and the actual resistance, capacitance, and inductance values ​​are read and recorded through the preset test frequency and test level;

[0088] Preset the nominal values ​​corresponding to the combined resistance, combined capacitance, and combined inductance values, and calculate the resistance deviation rate D. R Capacitor deviation rate D C and inductance deviation rate D L That is, through the formula The calculation yields R; 综合 and R 标称 These represent the combined resistance value and the corresponding preset nominal value, respectively. C 综合 and C 标称 These represent the combined capacitance value and the corresponding preset nominal value, respectively. L 综合 and L 标称 These represent the overall inductance value and the corresponding preset nominal value, respectively.

[0089] Set resistance deviation rate D R Capacitor deviation rate D C and inductance deviation rate D L The corresponding weighting coefficients will determine the resistance deviation rate D of each electrical test sample. R Capacitor deviation rate D C and inductance deviation rate D L The component performance index Dt of each electrical test sample is obtained by multiplying it by the corresponding set weight coefficient and then summing the results.

[0090] It should be noted that by setting the number of measurements G (G>3) and obtaining the resistance, capacitance and inductance values ​​of G groups, and then calculating the average value to obtain the comprehensive resistance value, comprehensive capacitance value and comprehensive inductance value, the influence of measurement error and random interference can be effectively reduced.

[0091] By setting weighting coefficients for the resistance deviation rate, capacitance deviation rate, and inductance deviation rate, and calculating the component quality index, a quantitative assessment of component quality is achieved.

[0092] A set excitation signal is input to each electrical test sample; the excitation signal is a periodic pulse signal or a clock signal; the time point of input excitation signal is marked as the start point, the time point of output excitation signal is marked as the end point, and the time difference between the start point and the end point is used as the transmission delay;

[0093] Set the number of times the excitation signal is input, and obtain the transmission delay of each electrical test sample corresponding to each input excitation signal. Calculate the average of the transmission delays of each group of electrical test samples to obtain the comprehensive transmission delay value De of each electrical test sample.

[0094] It should be noted that incorporating the overall transmission delay value into the evaluation system takes into account the signal transmission capability of the circuit board.

[0095] According to the formula The component performance index Dt and the comprehensive transmission delay value De of each electrical test sample are weighted and calculated to obtain the comprehensive electrical index Dy of each electrical test sample; where Da and Db are the preset allowable performance index and allowable delay value, respectively; β1 and β2 are the influence weight factors of component performance index Dt and comprehensive transmission delay value De, respectively.

[0096] The electrical performance index hjr of the current production batch of circuit boards is obtained by taking the average of the electrical comprehensive index Dy of each electrical test sample.

[0097] It should be noted that by calculating the comprehensive electrical index, which integrates two important aspects—component performance and transmission delay—a comprehensive evaluation of the electrical performance of the circuit board can be achieved.

[0098] The quality assessment module receives the soldering assessment index hju and electrical performance index hjr of the current production batch of circuit boards, and outputs the soldering quality level and electrical quality level of the current production batch of circuit boards. The output soldering quality level and electrical quality level are sent to the management personnel. After receiving them, the management personnel selectively triggers a repeat signaling. If a repeat signaling is triggered, the triggered repeat signaling is sent to the quality inspection module.

[0099] It should be noted that if the management personnel believe that the welding quality level is "poor welding level" or the electrical quality level is "poor electrical level" and have doubts about the quality inspection results, they can trigger a repeat signaling. After triggering, the repeat signaling will be sent to the quality inspection module. After receiving the repeat signaling, the quality inspection module can re-extract welding analysis samples and electrical inspection samples from the batch of circuit boards for testing to further confirm the quality status of the current batch of circuit boards.

[0100] Specifically:

[0101] The system pre-defines the three sets of index value ranges corresponding to the welding evaluation index hju and the electrical performance index hjr. Each set of index value ranges corresponding to the welding evaluation index hju corresponds to a welding quality level, and each set of index value ranges corresponding to the electrical performance index hjr corresponds to an electrical quality level. The welding quality levels include poor welding, passable welding, and excellent welding, while the electrical quality levels include poor electrical, passable electrical, and excellent electrical.

[0102] The welding evaluation index hju and electrical performance index hjr of the current production batch of circuit boards are matched with the corresponding index value ranges to determine the welding quality level and electrical quality level of the current production batch of circuit boards.

[0103] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A circuit board soldering quality inspection system, characterized in that, include: Quality inspection module: includes sample screening unit, welding analysis unit and electrical testing unit; The sample screening unit is used to count the total number of circuit boards produced in the current batch, and to determine the sampling ratio of welding analysis samples and electrical test samples based on the total number range, thereby extracting the corresponding proportion of welding analysis samples and electrical test samples. The welding analysis unit is used to acquire images of the extracted welding analysis samples and to preprocess the acquired sample images. After preprocessing, the images of each group of samples are comprehensively analyzed to obtain the welding evaluation index hju of the current production batch of circuit boards; The electrical testing unit is used to collect electrical parameters from the extracted electrical testing samples; The electrical parameters include resistance, capacitance, inductance, and transmission delay. After the data collection is completed, the electrical parameters of each electrical test sample are comprehensively evaluated to obtain the electrical performance index hjr of the current production batch of circuit boards. A comprehensive evaluation of the electrical parameters of each electrical test sample was conducted, specifically as follows: The number of measurements G corresponding to the preset resistance, capacitance, and inductance values; Based on the number of measurements G, obtain the resistance, capacitance, and inductance values ​​of G groups for each electrical test sample; The average values ​​of resistance, capacitance, and inductance of each electrical test sample in group G were calculated to obtain the comprehensive resistance, comprehensive capacitance, and comprehensive inductance values ​​of each electrical test sample. The nominal values ​​corresponding to the preset combined resistance, combined capacitance, and combined inductance values ​​are then calculated, and the resistance deviation rate is determined. Capacitor deviation rate and inductance deviation rate That is, through the formula The calculations were performed to obtain the results; where and These represent the combined resistance value and the corresponding preset nominal value, respectively. and These represent the overall capacitance value and the corresponding preset nominal value, respectively. and These represent the overall inductance value and the corresponding preset nominal value, respectively. Set resistance deviation rate Capacitor deviation rate and inductance deviation rate The corresponding weighting coefficients will determine the resistance deviation rate of each electrical test sample. Capacitor deviation rate and inductance deviation rate The component performance index Dt of each electrical test sample is obtained by multiplying it by the corresponding set weight coefficient and then summing the results. A set excitation signal is input to each electrical test sample. The time point of the input excitation signal is marked as the start point, and the time point of the output excitation signal is marked as the end point. The time difference between the start point and the end point is used as the transmission delay. Set the number of times the excitation signal is input, and obtain the transmission delay of each electrical test sample corresponding to each input excitation signal. Calculate the average of the transmission delays of each group of electrical test samples to obtain the comprehensive transmission delay value De of each electrical test sample. According to the formula The component performance index Dt and the comprehensive transmission delay De of each electrical test sample are weighted and calculated to obtain the comprehensive electrical index Dy of each electrical test sample; Where Da and Db are the preset performance allowable index and latency allowable value, respectively; and These are the influence weighting factors for the component performance index Dt and the comprehensive transmission delay value De, respectively; The electrical performance index hjr of the current production batch of circuit boards is obtained by taking the average of the electrical comprehensive index Dy of each electrical test sample.

2. The circuit board soldering quality inspection system according to claim 1, characterized in that, The sampling ratio for welding analysis samples and electrical testing samples is determined based on the total number range, specifically as follows: The preset number of circuit boards corresponds to the interval of each group of quantities, and each interval of the quantity of each group of quantities corresponds to a set of extraction ratios. The sampling ratio set includes the sampling ratios corresponding to welding analysis samples and electrical testing samples, respectively. The total number of circuit boards produced in the current batch is matched with the preset range of each group to obtain the sampling ratio set of the circuit boards produced in the current batch; the total number of circuit boards produced in the current batch is multiplied by the sampling ratio of the welding analysis samples in the sampling ratio set to determine the number of welding analysis samples to be extracted. The number of electrical test samples to be drawn is determined by multiplying the total number of circuit boards produced in the current batch by the sampling ratio of the electrical test samples within the sampling ratio set.

3. The circuit board welding quality inspection system according to claim 2, characterized in that, After preprocessing, a comprehensive analysis of the images from each group of samples is performed, specifically as follows: Input a sample image of a circuit board with acceptable soldering quality in advance, as a reference quality sample for the current production batch of circuit boards; Based on the pre-set division regions, each group of sample images is divided into various functional sub-regions; For each functional sub-region of each group of sample images, extract the edge contour of the solder joint in each functional sub-region of each group of sample images, and obtain the roundness of each solder joint in each functional sub-region of each group of sample images. From each functional sub-region of the reference quality sample, the roundness of each solder joint is extracted, and the roundness with the largest difference from the integer is taken as the passing roundness of each functional sub-region of the sample image. The roundness of each solder joint in each functional sub-region of each group of sample images is compared with the corresponding acceptable roundness. If the roundness of a solder joint in a certain functional sub-region of a certain group of sample images is lower than the corresponding acceptable roundness, it is judged as an abnormal shape solder joint. The number of abnormal weld points in each functional sub-region within each group of sample images is counted and recorded as the number of abnormal weld points. A weight coefficient is set for each functional sub-region corresponding to the number of abnormal weld points. The number of abnormal weld points in each functional sub-region within each group of sample images is multiplied by the corresponding weight coefficient, and then the sum is obtained to obtain the welding abnormality index of each group of sample images.

4. The circuit board soldering quality inspection system according to claim 3, characterized in that, The soldering evaluation index hju for the current production batch of circuit boards is obtained as follows: For the reference quality sample, obtain the geometric center of the contour of each solder joint, and use it as the center coordinate of each solder joint; Simultaneously, the center coordinates of each solder joint in each group of sample images are obtained, and the center coordinates of each solder joint in each group of sample images are matched with the corresponding center coordinates of the solder joint in the reference quality sample. After the matching is completed, the solder joint pairs of each solder joint in each group of sample images are obtained, namely, the center coordinates of the solder joint in the sample image and the center coordinates of the reference solder joint. For each group of weld points, calculate the difference on the horizontal and vertical axes respectively, and set the allowable position deviation thresholds corresponding to the horizontal and vertical axes respectively; The difference between the horizontal and vertical coordinates of each group of solder joints is compared with the corresponding set allowable position deviation threshold. If there is a group of differences that are greater than the corresponding set allowable position deviation threshold, the solder joints that are greater than the allowable position deviation threshold are marked as solder joints with abnormal positions. The number of abnormal weld points in each functional sub-region of each group of sample images is counted and recorded as the number of abnormal weld points. A weight coefficient is set for each functional sub-region corresponding to the number of abnormal weld points. The number of abnormal weld points in each functional sub-region of each group of sample images is multiplied by the corresponding weight coefficient, and then the sum is obtained to obtain the welding abnormal weld index of each group of sample images. Extract the welding shape index and welding position index corresponding to each group of sample images, and label them as E1 and E2 respectively; according to the formula The welding shape index E1 and welding position index E2 of each group of sample images are weighted and calculated to obtain the welding effect index E3 corresponding to each group of sample images. The average value of the welding effect index E3 of each group of sample images is taken to obtain the welding evaluation index hju of the current production batch of circuit boards.

5. The circuit board soldering quality inspection system according to claim 1, characterized in that, Also includes: Quality assessment module: Receives the soldering assessment index hju and electrical performance index hjr of the current production batch of circuit boards, and outputs the soldering quality level and electrical quality level of the current production batch of circuit boards, and sends the output soldering quality level and electrical quality level to the management personnel.

6. The circuit board soldering quality inspection system according to claim 5, characterized in that, Output the soldering quality grade and electrical quality grade of the current production batch of circuit boards, specifically: The three sets of index value ranges corresponding to the preset welding evaluation index hju and electrical performance index hjr are set respectively. Each set of index value ranges corresponding to the welding evaluation index hju corresponds to a welding quality level, and each set of index value ranges corresponding to the electrical performance index hjr corresponds to an electrical quality level. The welding quality grades include poor welding grade, pass welding grade, and excellent welding grade; the electrical quality grades include poor electrical grade, pass electrical grade, and excellent electrical grade. The soldering evaluation index hju and electrical performance index hjr of the current production batch of circuit boards are matched with their corresponding index value ranges to determine the soldering quality level and electrical quality level of the current production batch of circuit boards.

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