A method for determining the consistency of solder pull force and solder creep of tin-plated pins

Abstract

This invention discloses a method for determining the soldering pull force and solder creep consistency of tin-plated PIN pins, relating to the field of industrial quality inspection. The method includes: acquiring the appearance morphology parameters and mechanical property parameters of the solder joints, performing correlation analysis on the parameters to calculate a comprehensive appearance coupling factor, and defining a set of high-risk failure modes; constructing a three-dimensional feature space based on the maximum breaking force, fracture energy, and comprehensive appearance coupling factor; defining a healthy solder joint cluster and setting an independent threshold based on the statistical distribution of historical qualified solder joint samples in the three-dimensional feature space; delineating judgment areas and judgment rules to distinguish between consistent qualified, camouflaged strength risk, hidden fracture risk, and unqualified based on the statistical characteristics of the healthy solder joint clusters, the independent threshold, and the set of high-risk failure modes; mapping the solder joints to be tested to the three-dimensional feature space for judgment; and statistically analyzing the solder joint quality judgment results within the same production batch, triggering a process warning when batch quality indicators exceed limits or show abnormal trends.

Description

Technical Field

[0001] This invention relates to the field of industrial quality inspection, specifically to a method for determining the consistency between the soldering pull force and solder creep of tin-plated PIN pins. Background Technology

[0002] In the field of electronic product manufacturing, the soldering quality of tin-plated pins is a key factor affecting the reliability of electrical connections and the long-term stability of products. The current quality acceptance system mainly relies on two independent dimensions: the first is the inspection of the appearance of the solder joint, which uses quantitative evaluation of parameters such as solder creep height and wetting angle to determine the adequacy of the soldering process; the second is destructive mechanical property testing, which verifies whether the connection strength meets the design specifications by measuring indicators such as the tensile strength of the solder joint.

[0003] However, in actual production quality control and incoming material verification, the two assessment methods mentioned above are usually implemented independently, lacking effective integration. Relying solely on visual inspection cannot accurately infer the actual mechanical properties and long-term reliability of solder joints, posing a potential risk of acceptable appearance but insufficient connection strength. While a single mechanical performance test can verify instantaneous strength, its destructive nature makes it impossible to conduct full inspection and makes it difficult to effectively identify solder joints that, although meeting the lower limit of tensile strength, may have early failure risks due to insufficient solder filling or poor interface bonding. Especially when facing material substitution, process parameter adjustments, or supplier changes, traditional acceptance methods lack the sensitivity to identify potential risks and may fail to provide timely warnings of transferred failure risks caused by mismatches between appearance quality and mechanical properties.

[0004] Therefore, there is an urgent need in this field for a method that can deeply correlate and collaboratively determine the surface morphology parameters and mechanical property parameters of weld points, in order to identify welded connections with hidden defects earlier and more accurately based on sampling tests or non-complete destructive testing, thereby improving the reliability of quality acceptance and the effectiveness of process verification. Summary of the Invention

[0005] Based on the shortcomings of the prior art described above, the purpose of this invention is to provide a method for determining the soldering pull force and solder creep consistency of tin-plated PIN pins, so as to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins, comprising: S1: Obtain the apparent morphology parameters and mechanical property parameters of the solder joint; the apparent morphology parameters include solder creep height, solder creep wrap angle and solder filling volume; the mechanical property parameters include the maximum tensile force and fracture energy extracted from the tensile-displacement curve, as well as the specific failure location recorded after failure; S2: Analyze the correlation between appearance morphology parameters and mechanical performance parameters, and calculate the comprehensive appearance coupling factor that characterizes the overall appearance quality of the weld joint based on this correlation; analyze the statistical correlation between different failure locations and mechanical performance parameters and comprehensive appearance coupling factor, and define a set of high-risk failure modes; S3: Construct a three-dimensional feature space based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor. Define a healthy weld point cluster based on the joint probability density distribution of historical qualified weld point samples in the three-dimensional feature space, and pre-set independent thresholds for each parameter. Based on the statistical characteristics, independent thresholds, and high-risk failure mode set of the healthy weld point cluster, define the judgment area and judgment rules to distinguish between consistent qualified weld points, disguised strength risk weld points, hidden fracture risk weld points, and unqualified weld points. S4: Determine the comprehensive appearance coupling factor of the weld point to be tested, and obtain its maximum tensile force, fracture energy and failure location; map the weld point to be tested to a three-dimensional feature space according to its maximum tensile force, fracture energy and comprehensive appearance coupling factor, and make a judgment according to the judgment area and judgment rules, and output the judgment conclusion of consistency qualified, camouflage strength risk, hidden fracture risk or unqualified. S5: Statistically analyze the quality judgment results of all solder joints within the same production batch, calculate the batch non-conforming rate, batch comprehensive risk rate, and batch average of comprehensive appearance coupling factor for that batch. When the batch non-conforming rate, batch comprehensive risk rate, or batch average of comprehensive appearance coupling factor exceeds the preset statistical control limit or shows a preset abnormal statistical trend, trigger a process warning.

[0007] The present invention is further configured such that the independent thresholds of each parameter include an independent threshold for the maximum tensile force, an independent threshold for the fracture energy, and an independent threshold for the comprehensive appearance coupling factor.

[0008] The present invention is further configured such that the quality judgment result is the judgment conclusion output in step S4, which is either consistent and qualified, camouflage strength risk, hidden danger breakage risk, or unqualified.

[0009] The present invention is further configured such that S1 includes: A predetermined number of tin-plated PIN pin welding samples were randomly selected from the production batch to be tested and fixed. The solder joint area of ​​each fixed tin-plated PIN pin soldering sample was three-dimensionally scanned using a white light interferometer or a laser confocal microscope to obtain three-dimensional point cloud data of the solder joint surface; based on the three-dimensional point cloud data, the appearance morphology parameters including solder creep height, solder creep wrap angle and solder filling volume were calculated through geometric analysis. Each tin-plated PIN solder sample was subjected to axial tensile or pull-out tests on a material testing machine until the solder joint broke. During the test, the tensile force-displacement curve was recorded synchronously at a preset sampling rate. Mechanical property parameters, including the maximum breaking force and fracture energy, were extracted from the tensile force-displacement curve. The fracture surface morphology of each weld point was observed under a stereomicroscope, and the specific failure location was recorded according to the preset failure category coding rules. The appearance morphology parameters and mechanical property parameters are normalized, and outliers are removed based on statistical distribution criteria.

[0010] The present invention is further configured such that the solder climbing height is the maximum vertical height of the solder climbing along the side of the PIN pin; The solder wrapping angle is the circumferential angle of the solder wetting and covering on the cross-section of the PIN pin; The solder filling volume is the total volume of solder filling between the PIN pin and the pad, calculated based on the reconstructed solder joint solid model using 3D point cloud data. The maximum breaking force is the peak tensile force on the force-displacement curve; The fracture energy is the area obtained by integrating the tensile-displacement curve from the starting point to the fracture point.

[0011] The present invention is further configured such that S2 includes: For each appearance morphology parameter, the Pearson correlation coefficient between it and the maximum tensile force and fracture energy is calculated. Appearance morphology parameters whose absolute values ​​of the Pearson correlation coefficient with the maximum tensile force and fracture energy are all greater than the preset correlation screening threshold are selected to form a set of key appearance features. Principal component analysis is performed on all key appearance feature parameters in the key appearance feature set to obtain the variance contribution rate and eigenvector of each principal component. The principal component whose cumulative variance contribution rate first exceeds the preset contribution rate threshold is identified as the feature fusion principal component, and its corresponding eigenvector is obtained. This eigenvector contains the weight coefficients corresponding to each key appearance feature parameter. After normalizing the key appearance feature parameters of each historical solder joint sample, they are multiplied by the corresponding weight coefficients and summed to obtain the comprehensive appearance coupling factor of the solder joint sample. For each preset failure location category, the following processing is performed: count the number of samples belonging to that failure location category in all historical weld point samples, and calculate the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor of all weld point samples under that failure location category; use analysis of variance or nonparametric hypothesis testing to determine whether there are statistically significant differences in the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor between different failure location categories. Based on the results of the significant difference analysis, failure location categories that meet any of the following conditions will be included in the high-risk failure mode set: the mean maximum tensile force of the weld samples in this failure location category is lower than the preset lower quantile of the distribution of the maximum tensile force of the overall historical weld samples; the mean fracture energy of the weld samples in this failure location category is lower than the preset lower quantile of the distribution of the overall fracture energy of the overall historical weld samples; the mean comprehensive appearance coupling factor of the weld samples in this failure location category is lower than the preset lower quantile of the distribution of the comprehensive appearance coupling factor of the overall historical weld samples.

[0012] The present invention is further configured such that S3 includes: A three-dimensional feature space characterizing the quality status of weld joints is constructed using the maximum tensile force, fracture energy, and comprehensive appearance coupling factor as three orthogonal dimensions. A preset number of historical qualified solder joint samples are mapped to a three-dimensional feature space based on their respective maximum tensile force, fracture energy, and comprehensive appearance coupling factor. Based on the positional distribution of the historical qualified solder joint samples in the three-dimensional feature space, their joint probability density distribution is fitted by multivariate kernel density estimation. Spatial regions with probability density values ​​higher than a preset density threshold are defined as healthy solder joint clusters. The mean vector and covariance matrix of the healthy solder joint clusters are calculated. Based on the statistical characteristics of healthy weld joint clusters, the set of high-risk failure modes, a pre-set first independent threshold for maximum tensile force, a second independent threshold for fracture energy, and a third independent threshold for comprehensive appearance coupling factor, the following four mutually exclusive decision regions are delineated in the three-dimensional feature space, and their decision rules are defined: The criteria for determining a consistent and qualified area are as follows: the maximum tensile strength of the weld point under test is not lower than the first independent threshold, the fracture energy is not lower than the second independent threshold, the comprehensive appearance coupling factor is not lower than the third independent threshold, and the Mahalanobis distance between the coordinate vector of the weld point under test in the three-dimensional feature space and the mean vector of the healthy weld point cluster is less than or equal to a preset statistical distance threshold; the Mahalanobis distance is calculated based on the covariance matrix of the healthy weld point cluster. The criteria for determining the camouflage strength risk area are as follows: the maximum tensile strength of the weld point to be tested is not lower than the first independent threshold and the comprehensive appearance coupling factor is lower than the third independent threshold. The criteria for determining the potential fracture risk area are as follows: the maximum tensile strength of the weld joint under test is not lower than the first independent threshold and the comprehensive appearance coupling factor is not lower than the third independent threshold, and it meets any of the following conditions: the failure location of the weld joint under test belongs to the set of high-risk failure modes; the fracture energy of the weld joint under test is lower than the average fracture energy value of all samples in the healthy weld joint cluster whose maximum tensile strength and comprehensive appearance coupling factor fall within a preset neighborhood centered on the value of the weld joint under test, minus a preset fluctuation amount. The criteria for determining non-conforming areas are as follows: weld points that do not meet any of the criteria for conformity compliance areas, camouflage strength risk areas, and hidden fracture risk areas.

[0013] The present invention is further configured such that S4 includes: Determine the comprehensive appearance coupling factor of the weld joint under test, and obtain its maximum tensile force, fracture energy and failure location; Based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor of the weld point to be tested, the weld point to be tested is mapped to a three-dimensional feature space, and the Mahalanobis distance between its coordinate vector in the three-dimensional feature space and the mean vector of the healthy weld point cluster is calculated. Based on the judgment area and judgment rules, the following logical judgment is performed: If the maximum tensile strength of the weld joint under test is lower than the first independent threshold or the fracture energy of the weld joint under test is lower than the second independent threshold, the weld joint under test is determined to be unqualified. If the maximum tensile strength of the weld joint under test is not lower than the first independent threshold, then proceed with the subsequent judgments in sequence: If the overall appearance coupling factor of the solder joint under test is lower than the third independent threshold, the solder joint under test is determined to be at risk of camouflage strength. If the comprehensive appearance coupling factor of the solder joint under test is not lower than the third independent threshold, then further judgment is made: if the failure location of the solder joint under test belongs to the set of high-risk failure modes, or if the fracture energy of the solder joint under test is lower than the maximum tensile force in the healthy solder joint cluster and the comprehensive appearance coupling factor falls within the average fracture energy value of all samples in the preset neighborhood centered on the corresponding value of the solder joint under test minus the preset fluctuation amount, then the solder joint under test is judged to be a hidden fracture risk. If the conditions for determining the risk of camouflage strength and the risk of hidden breakage are not met, and the Mahalanobis distance is less than or equal to the preset statistical distance threshold, then the weld point to be tested is determined to be of acceptable consistency. Output the judgment conclusion of the weld point under test: whether it is qualified, has a risk of camouflage strength, has a risk of hidden fracture, or is unqualified.

[0014] The present invention is further configured such that S5 includes: For the same production batch, the quality judgment results of all solder joints within the batch are statistically analyzed, and the batch non-conformance rate and the overall batch risk rate are calculated. Calculate the batch mean of the overall appearance coupling factor for all solder joints within this batch; The failure mode distribution of this batch is obtained by statistically analyzing the frequency of occurrence of each failure location category in all solder joints within the batch. The batch average of batch nonconformity rate, batch comprehensive risk rate, and comprehensive appearance coupling factor is monitored. A process warning is triggered when any of the following conditions are met: The batch non-conformance rate, the batch comprehensive risk rate, or the batch mean of the comprehensive appearance coupling factor exceeds the preset statistical control limit. The batch non-conformance rate or the batch comprehensive risk rate shows a monotonically increasing trend in a continuously preset number of batches. In the failure mode distribution, the frequency of occurrence of any failure location category is consistently higher than a preset multiple of its historical average frequency in a consecutive preset number of batches.

[0015] The present invention is further configured such that the batch non-conforming rate is the proportion of the number of solder joints judged to be non-conforming to the total number of solder joints in the batch; The overall risk rate for the batch is the ratio of the sum of the number of weld points identified as having camouflage strength risk and hidden breakage risk to the total number of weld points in that batch.

[0016] This invention provides a method for determining the consistency of soldering pull force and solder creep in tin-plated PIN pins. The method involves: S1: Obtaining the apparent morphology and mechanical properties of the solder joint; the apparent morphology parameters include solder creep height, solder creep wrap angle, and solder filling volume; the mechanical properties parameters include the maximum tensile force and fracture energy extracted from the force-displacement curve, and the specific failure location recorded after failure; S2: Analyzing the correlation between the apparent morphology and mechanical properties, and calculating a comprehensive appearance coupling factor characterizing the overall appearance quality of the solder joint based on this correlation; analyzing the statistical correlation between different failure locations and mechanical properties and the comprehensive appearance coupling factor, and defining a set of high-risk failure modes; S3: Constructing a three-dimensional feature space based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor; defining a healthy solder joint cluster based on the joint probability density distribution of historical qualified solder joint samples in the three-dimensional feature space, and pre-setting independent thresholds for each parameter; and based on the statistical analysis of the healthy solder joint cluster... The system uses a set of characteristics, independent thresholds, and high-risk failure modes to define the judgment areas and rules for distinguishing between consistent and qualified solder joints, solder joints with disguised strength risks, solder joints with hidden fracture risks, and unqualified solder joints; S4: Determine the comprehensive appearance coupling factor of the solder joint to be tested and obtain its maximum tensile force, fracture energy, and failure location; Map the solder joint to be tested to a three-dimensional feature space based on its maximum tensile force, fracture energy, and comprehensive appearance coupling factor, and judge it according to the judgment area and judgment rules, outputting the judgment conclusion of consistent and qualified, disguised strength risk, hidden fracture risk, or unqualified; S5: Statistically analyze the quality judgment results of all solder joints in the same production batch, calculate the batch non-conforming rate, batch comprehensive risk rate, and batch mean of comprehensive appearance coupling factor for that batch. When the batch non-conforming rate, batch comprehensive risk rate, or batch mean of comprehensive appearance coupling factor exceeds the preset statistical control limit or shows a preset abnormal statistical trend, a process warning is triggered. The beneficial effects include: 1. By correlating the apparent morphology parameters and mechanical property parameters of weld joints, this method overcomes the limitations of relying on a single mechanical index or isolated visual inspection in traditional quality acceptance. This method establishes a quantitative correlation between appearance features and connection strength, enabling the assessment of welding reliability from the perspective of connection mechanism. This effectively identifies abnormal weld joints that meet the tensile strength requirements but have hidden dangers in the connection structure, or whose appearance is acceptable but whose mechanical properties are at risk. This achieves a comprehensive judgment of welding quality from the surface to the core. 2. By integrating multiple related appearance morphology parameters into a comprehensive appearance coupling factor that characterizes the overall appearance quality of the solder joint, the multicollinearity problem among multiple parameters is effectively avoided. This comprehensive appearance coupling factor can characterize the overall quality of the solder's wetting, filling, and forming states. Its statistical correlation with mechanical properties is more significant and stable than any single appearance parameter, thereby improving the accuracy and robustness of quality prediction and judgment based on this comprehensive appearance coupling factor.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a flowchart illustrating a method for determining the soldering pull force and solder creep consistency of tin-plated PIN pins, as an exemplary embodiment of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0020] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0022] A method for determining the consistency between solder pull force and solder creep of tin-plated pins, such as... Figure 1 As shown, it includes: S1: Obtain the apparent morphology parameters and mechanical property parameters of the solder joint; the apparent morphology parameters include solder creep height, solder creep wrap angle and solder filling volume; the mechanical property parameters include the maximum tensile force and fracture energy extracted from the tensile-displacement curve, as well as the specific failure location recorded after failure; S2: Analyze the correlation between appearance morphology parameters and mechanical performance parameters, and calculate the comprehensive appearance coupling factor that characterizes the overall appearance quality of the weld joint based on this correlation; analyze the statistical correlation between different failure locations and mechanical performance parameters and comprehensive appearance coupling factor, and define a set of high-risk failure modes; S3: A three-dimensional feature space is constructed based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor. A healthy weld point cluster is defined according to the joint probability density distribution of historical qualified weld point samples in the three-dimensional feature space, and independent thresholds for each parameter are pre-set. Based on the statistical characteristics, independent thresholds, and high-risk failure mode set of the healthy weld point cluster, the judgment area and judgment rules for distinguishing consistent qualified weld points, disguised strength risk weld points, hidden fracture risk weld points, and unqualified weld points are defined. The independent thresholds for each parameter include the independent thresholds for the maximum tensile force, fracture energy, and comprehensive appearance coupling factor. S4: Determine the comprehensive appearance coupling factor of the weld point to be tested, and obtain its maximum tensile force, fracture energy and failure location; map the weld point to be tested to a three-dimensional feature space according to its maximum tensile force, fracture energy and comprehensive appearance coupling factor, and make a judgment according to the judgment area and judgment rules, and output the judgment conclusion of consistency qualified, camouflage strength risk, hidden fracture risk or unqualified. S5: Statistically analyze the quality judgment results of all solder joints within the same production batch, calculate the batch non-conforming rate, batch comprehensive risk rate, and batch average of the comprehensive appearance coupling factor for that batch. When the batch non-conforming rate, batch comprehensive risk rate, or batch average of the comprehensive appearance coupling factor exceeds the preset statistical control limit or shows a preset abnormal statistical trend, trigger a process warning. The quality judgment result is the judgment conclusion output in step S4: consistency qualified, camouflage strength risk, hidden breakage risk, or unqualified.

[0023] The present invention is further configured such that S1 includes: A predetermined number of tin-plated PIN pin welding samples were randomly selected from the production batch to be tested and fixed. Three-dimensional scanning of the solder joint area of ​​each fixed tin-plated PIN pin soldering sample was performed using a white light interferometer or a laser confocal microscope to obtain three-dimensional point cloud data of the solder joint surface. Based on the three-dimensional point cloud data, geometric analysis was used to calculate the appearance morphology parameters, including solder creep height, solder creep wrap angle, and solder fill volume. The solder creep height is the maximum vertical height of the solder creeping along the side of the PIN pin; the solder creep wrap angle is the circumferential angle of the solder wetting coverage on the cross-section of the PIN pin; and the solder fill volume is the total volume of solder filling between the PIN pin and the pad, calculated based on the solid model of the solder joint reconstructed from the three-dimensional point cloud data. Each tin-plated PIN solder sample was subjected to axial tensile or pull-out tests on a material testing machine until the solder joint broke. During the test, the tensile force-displacement curve was recorded synchronously at a preset sampling rate. Mechanical property parameters, including the maximum breaking force and the fracture energy, were extracted from the tensile force-displacement curve. The maximum breaking force is the peak tensile force of the tensile force-displacement curve. The fracture energy is the area obtained by integrating the tensile force-displacement curve from the starting point to the fracture point. The fracture surface morphology of each weld point was observed under a stereomicroscope, and the specific failure location was recorded according to the preset failure category coding rules. The appearance and mechanical properties parameters were normalized, and outliers were removed based on statistical distribution criteria. Specifically, a predetermined number of tin-plated pin soldering samples were randomly selected from the same production batch to be evaluated, and each sample was independently mounted in a dedicated test fixture. This fixture was specially designed to ensure that each sample maintained a completely consistent spatial position and three-dimensional orientation during subsequent morphology observation and destructive mechanical testing, thereby eliminating systematic measurement errors introduced by differences in sample orientation. Before destructive mechanical testing, non-contact measurement equipment such as a white light interferometer or a laser confocal microscope was used to inspect the fixed tin-plated pin soldering samples. The solder joint area of ​​the sample is subjected to 3D scanning to obtain 3D point cloud data characterizing the microstructure of the solder joint surface. Subsequently, the 3D point cloud data is automatically processed using specialized 3D analysis software to obtain quantitative parameters of the surface morphology. For solder climb height, the software automatically identifies the boundary line between the PIN sidewall contour and the solder outer contour, and locates the highest point of the solder climb along the PIN sidewall in a direction perpendicular to the pad plane. The vertical distance between this highest point and the pad reference plane is calculated, and this vertical distance is defined as the solder climb height. For solder wrap angle, the software defines a specific cross-section through the theoretical axis of the PIN in a 3D coordinate system established by the measuring device. On this cross-section, the software automatically identifies the solder wetting front and... The software calculates the starting and ending boundary points where the sidewalls of the PIN pins intersect, and the angle formed by the rays connecting these two points to the center of the PIN pin cross-section. This angle is defined as the solder wrapping angle, which quantifies the coverage area of ​​the solder in the circumferential direction of the PIN pin. Regarding the solder filling volume, the software reconstructs a 3D model of the solder joint based on 3D point cloud data. By calculating the volume of this solder joint model and subtracting the volume of the PIN pin portion with known geometric dimensions, the total volume of solder filling the gap between the PIN pin and the circuit board pad is obtained. This total volume is defined as the solder filling volume. The tin-plated PIN pin soldering sample, after morphological observation, is placed in a material testing machine for axial tensile or pull-out tests until the solder joint completely breaks. During the test, the force sensor and displacement sensor integrated into the material testing machine synchronously collect data at a preset sampling rate to generate a complete tensile-displacement curve of the tin-plated PIN pin welding sample. Two mechanical performance parameters are extracted from the tensile-displacement curve: one is the maximum tensile breaking force, which corresponds to the peak tensile force in the tensile-displacement curve and characterizes the ultimate bearing capacity of the solder joint before fracture; the other is the fracture energy, which is obtained by numerically integrating the tensile-displacement curve from the test start point to the solder joint fracture point. The integration result is physically equivalent to the area under the tensile-displacement curve, which characterizes the total mechanical work consumed to fracture the solder joint and reflects the toughness and energy absorption characteristics of the solder joint.After destructive mechanical testing was completed and the solder joints fractured, the fracture surface morphology of the solder joints was observed using a stereomicroscope. Based on the morphological characteristics, the specific failure location of the fracture was determined. According to a preset classification standard based on fracture location, the failure mode of each solder joint was determined and assigned a corresponding failure category code. The classification standard includes, for example, the following: if the fracture occurs entirely within the solder material itself, it is coded as a first-class failure mode; if the fracture occurs at the interface between the solder and the tin plating layer on the PIN pin surface, it is coded as a second-class failure mode; if the fracture occurs between the tin plating layer of the PIN pin and its base metal, it is coded as a third-class failure mode; if the fracture occurs at the interface between the solder and the PCB pad, it is coded as a fourth-class failure mode; if the fracture is accompanied by the PCB pad being wholly or partially peeled off from the substrate, it is coded as a fifth-class failure mode; and if the fracture occurs within the PIN pin body material, it is coded as a sixth-class failure mode. The obtained continuous appearance morphology parameters and mechanical performance parameters, including solder climb height, solder climb wrap angle, solder fill volume, maximum tensile force, and fracture energy, are used to determine the failure mode. Each parameter has different physical dimensions and numerical magnitudes. To eliminate the impact of these differences on subsequent multivariate statistical analysis, all continuous parameters need to be normalized. The normalization methods used include Z-score standardization and min-max normalization. Z-score standardization transforms the data sequence corresponding to each parameter into a distribution with a mean of zero and a standard deviation of one, while min-max normalization linearly maps the data of each parameter to a closed interval between zero and one. After normalization, outlier detection and cleaning are also performed on the data sequence corresponding to each parameter. The outlier detection methods employed include box plot analysis and the standard deviation principle. Box plot analysis calculates the lower quartile, upper quartile, and interquartile range of the data sequence, identifying data points with values ​​less than the lower quartile minus 1.5 times the interquartile range or greater than the upper quartile plus 1.5 times the interquartile range as statistical outliers. The standard deviation principle identifies data points deviating from the data sequence mean by more than three standard deviations as outliers. All sample records corresponding to data points identified as outliers are removed from the dataset used for subsequent modeling and analysis.

[0024] The present invention is further configured such that S2 includes: For each appearance morphology parameter, the Pearson correlation coefficient between it and the maximum tensile force and fracture energy is calculated. Appearance morphology parameters whose absolute values ​​of the Pearson correlation coefficient with the maximum tensile force and fracture energy are all greater than the preset correlation screening threshold are selected to form a set of key appearance features. Principal component analysis is performed on all key appearance feature parameters in the key appearance feature set to obtain the variance contribution rate and eigenvector of each principal component. The principal component whose cumulative variance contribution rate first exceeds the preset contribution rate threshold is identified as the feature fusion principal component, and its corresponding eigenvector is obtained. This eigenvector contains the weight coefficients corresponding to each key appearance feature parameter. After normalizing the key appearance feature parameters of each historical solder joint sample, they are multiplied by the corresponding weight coefficients and summed to obtain the comprehensive appearance coupling factor of the solder joint sample. For each preset failure location category, the following processing is performed: count the number of samples belonging to that failure location category in all historical weld point samples, and calculate the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor of all weld point samples under that failure location category; use analysis of variance or nonparametric hypothesis testing to determine whether there are statistically significant differences in the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor between different failure location categories. Based on the results of the significant difference analysis, failure location categories that meet any of the following conditions are included in the high-risk failure mode set: the mean maximum tensile force of the weld joint samples in this failure location category is lower than the preset lower quantile of the overall maximum tensile force distribution of historical weld joint samples; the mean fracture energy of the weld joint samples in this failure location category is lower than the preset lower quantile of the overall fracture energy distribution of historical weld joint samples; the mean comprehensive appearance coupling factor of the weld joint samples in this failure location category is lower than the preset lower quantile of the overall comprehensive appearance coupling factor distribution of historical weld joint samples. Specifically, key appearance features that have a decisive influence on the mechanical properties of weld joints are screened from all appearance morphology parameters. In practice, for each obtained appearance morphology quantification parameter, the following is analyzed: Calculate the Pearson correlation coefficient between the morphological parameters and the maximum tensile strength, as well as the Pearson correlation coefficient between the morphological parameters and the fracture energy. The Pearson correlation coefficient is used to quantify the degree and direction of the linear correlation between two continuous variables. Based on domain knowledge or statistical significance requirements, a correlation screening threshold is preset. morphological parameters that simultaneously meet the following dual conditions are identified: the absolute value of their Pearson correlation coefficient with the maximum tensile strength is greater than the correlation screening threshold, and the absolute value of their Pearson correlation coefficient with the fracture energy is also greater than the correlation screening threshold. morphological parameters meeting these dual conditions are judged to have a statistically significant strong correlation with both the ultimate bearing strength and energy absorption toughness of the weld joint. All parameters identified through this screening... Other appearance morphology parameters are summarized to form a key appearance feature set. The parameters in this key appearance feature set constitute the basic input for subsequent comprehensive evaluation of the solder joint appearance quality. Multiple related or overlapping key appearance feature parameters in the key appearance feature set are integrated into a single index that can comprehensively and concisely characterize the overall appearance quality of the solder joint, namely the comprehensive appearance coupling factor. This is achieved using principal component analysis, a multivariate statistical method. This multivariate statistical method performs an orthogonal linear transformation on the data matrix composed of all key appearance feature parameters in the key appearance feature set. Its purpose is to transform the original set of interrelated variables into a new set of unrelated variables arranged in descending order of their explanatory power for data variation. The quantities are called principal components. The first few principal components are designed to cover most of the variation information in the original data. The calculation process outputs a series of principal components and their corresponding statistics. Each principal component can explain a specific proportion of the total variance of the original data. Usually, the first principal component can explain the largest proportion of the variance. In the specific implementation of this method, the principal component whose cumulative variance contribution rate first exceeds the preset contribution rate threshold is determined as the principal component for feature fusion. This principal component is usually the first principal component. The determined feature fusion principal component corresponds to a specific feature vector. Each numerical component in this feature vector corresponds to the weight coefficient of each original key appearance feature parameter in the key appearance feature set.To calculate the comprehensive appearance coupling factor of any historical solder joint sample, the key appearance feature parameters of the sample must first be normalized. Each normalized key appearance feature parameter value is then multiplied by its corresponding weight coefficient in the feature vector. The sum of all multiplication results is then defined as the comprehensive appearance coupling factor of the solder joint sample. This factor characterizes the overall quality level of the solder joint across multiple key appearance dimensions. For each preset failure location category, the number of historical solder joint samples belonging to that category is counted, and the average maximum tensile force of all solder joint samples within that failure location category is calculated. To determine whether there are statistically significant differences in the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor among different failure location categories, statistical hypothesis tests need to be performed on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor respectively. Specifically, based on the assumptions that the data distribution satisfies normality and homogeneity of variance, parametric tests such as ANOVA or non-parametric tests such as the Kruskal-Wallis test are selected to perform an overall significance test on the differences in the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor among all failure location categories. This test will generate a statistical hypothesis test. The statistically inferred significance probability value is compared with a preset significance level to determine whether the differences in the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor among the observed different failure location categories are statistically significant. This helps identify which failure location categories are generally associated with lower levels of maximum tensile force, fracture energy, or comprehensive appearance coupling factor. Based on the aforementioned significant difference analysis results, the rules for defining the high-risk failure mode set are as follows: Failure location categories that meet any of the following conditions are included in the high-risk failure mode set: the mean maximum tensile force of the weld point samples in that failure location category is lower than the mean maximum tensile force of the overall historical weld point samples. The failure location category is determined by the following criteria: the lower quantile of the failure location, or the mean fracture energy of the weld point samples in that failure location category is lower than the lower quantile of the overall fracture energy distribution of historical weld point samples; or the mean comprehensive appearance coupling factor of the weld point samples in that failure location category is lower than the lower quantile of the overall comprehensive appearance coupling factor distribution of historical weld point samples. The lower quantile is set according to the quality control requirements and acceptable risk tolerance of the specific production process. Its function is to provide an objective and quantifiable statistical threshold for judging whether the maximum tensile force, fracture energy, and comprehensive appearance coupling factor are at an overall low level. Any failure location category can be determined as a high-risk failure mode based on meeting one or more of the aforementioned conditions.

[0025] The present invention is further configured such that S3 includes: A three-dimensional feature space characterizing the quality status of weld joints is constructed using the maximum tensile force, fracture energy, and comprehensive appearance coupling factor as three orthogonal dimensions. A preset number of historical qualified solder joint samples are mapped to a three-dimensional feature space based on their respective maximum tensile force, fracture energy, and comprehensive appearance coupling factor. Based on the positional distribution of the historical qualified solder joint samples in the three-dimensional feature space, their joint probability density distribution is fitted by multivariate kernel density estimation. Spatial regions with probability density values ​​higher than a preset density threshold are defined as healthy solder joint clusters. The mean vector and covariance matrix of the healthy solder joint clusters are calculated. Based on the statistical characteristics of healthy weld joint clusters, the set of high-risk failure modes, a pre-set first independent threshold for maximum tensile force, a second independent threshold for fracture energy, and a third independent threshold for comprehensive appearance coupling factor, the following four mutually exclusive decision regions are delineated in the three-dimensional feature space, and their decision rules are defined: The criteria for determining a consistent and qualified area are as follows: the maximum tensile strength of the weld point under test is not lower than the first independent threshold, the fracture energy is not lower than the second independent threshold, the comprehensive appearance coupling factor is not lower than the third independent threshold, and the Mahalanobis distance between the coordinate vector of the weld point under test in the three-dimensional feature space and the mean vector of the healthy weld point cluster is less than or equal to a preset statistical distance threshold; the Mahalanobis distance is calculated based on the covariance matrix of the healthy weld point cluster. The criteria for determining the camouflage strength risk area are as follows: the maximum tensile strength of the weld point to be tested is not lower than the first independent threshold and the comprehensive appearance coupling factor is lower than the third independent threshold. The criteria for determining the potential fracture risk area are as follows: the maximum tensile strength of the weld joint under test is not lower than the first independent threshold and the comprehensive appearance coupling factor is not lower than the third independent threshold, and it meets any of the following conditions: the failure location of the weld joint under test belongs to the set of high-risk failure modes; the fracture energy of the weld joint under test is lower than the average fracture energy value of all samples in the healthy weld joint cluster whose maximum tensile strength and comprehensive appearance coupling factor fall within a preset neighborhood centered on the value of the weld joint under test, minus a preset fluctuation amount. The criteria for determining non-conforming areas are as follows: any weld point that fails to meet any of the criteria for conformity compliance areas, camouflage strength risk areas, or hidden fracture risk areas. Specifically, a three-dimensional feature space is constructed with maximum tensile force, fracture energy, and comprehensive appearance coupling factor as three orthogonal dimensions. The maximum tensile force characterizes the weld point's ultimate bearing strength, fracture energy characterizes the weld point's toughness and energy absorption capacity, and the comprehensive appearance coupling factor characterizes the overall appearance quality level formed by the fusion of multiple key appearance parameters. Each weld point sample can be uniquely mapped to a coordinate point in this three-dimensional feature space based on its own maximum tensile force, fracture energy, and comprehensive appearance coupling factor. Based on the historical qualified weld point sample group in this three-dimensional feature space... A healthy weld point cluster is defined by selecting a predetermined number of historical qualified weld point samples that have undergone long-term reliability verification. Their maximum tensile force, fracture energy, and comprehensive appearance coupling factor are mapped onto the three-dimensional feature space as coordinates, forming a spatial point set representing good welding quality. The spatial distribution of this point set is fitted using a multivariate kernel density estimation method to obtain a continuous joint probability density function describing the probability distribution of historical qualified weld point samples in the three-dimensional feature space. The spatial region consisting of all spatial points with probability densities higher than a predetermined density threshold in this joint probability density function is defined as the healthy weld point cluster. Geometrically, this healthy weld point cluster corresponds to a highly dense core region of historical qualified weld point samples. The healthy weld point cluster is then calculated. The mean vector of all sample point coordinates is used to characterize the center position, and its covariance matrix is ​​calculated to quantitatively characterize the dispersion of the healthy solder joint cluster along each dimension and the synergistic relationship between each dimension. Based on the minimum mechanical performance standards defined in the product design specifications, a first independent threshold for maximum tensile force and a second independent threshold for fracture energy are pre-set. Simultaneously, based on the actual data distribution of the comprehensive appearance coupling factor in the healthy solder joint cluster, a third independent threshold for the comprehensive appearance coupling factor is pre-set at a specific low quantile of its probability distribution. These three independent thresholds together constitute a rigid standard for judging whether the solder joint quality meets the basic access requirements. Within the constructed three-dimensional feature space, the statistical characteristics of the healthy solder joint cluster, namely the mean vector and covariance matrix, are comprehensively considered. The difference matrix, the set of high-risk failure modes, and three independent thresholds are used to define four mutually exclusive judgment regions and define their judgment rules respectively: the judgment rule for the consistency qualified region is that the maximum tensile force of the solder joint under test is not lower than the first independent threshold, the fracture energy is not lower than the second independent threshold, the comprehensive appearance coupling factor is not lower than the third independent threshold, and the Mahalanobis distance between the coordinate vector of the solder joint in the three-dimensional feature space and the mean vector of the healthy solder joint cluster is not greater than a preset statistical distance threshold; wherein, the calculation logic of the Mahalanobis distance is as follows: obtain the coordinate vector of the solder joint under test and the mean vector of the healthy solder joint cluster, and calculate the difference between the coordinate vector and the mean vector to obtain the difference vector; based on the covariance matrix of the healthy solder joint cluster, calculate its inverse matrix;The difference vector is transposed and multiplied by the inverse of the covariance matrix. This multiplication result is then multiplied by the original difference vector to obtain a standardized squared distance value. The square root of this squared distance value is defined as the Mahalanobis distance from the tested weld point to the center of the healthy weld point cluster. This Mahalanobis distance measures the statistical deviation of the tested weld point from the core of the healthy weld point cluster. The criteria for determining the camouflage strength risk area are: the maximum tensile strength of the tested weld point is not lower than the first independent threshold and its comprehensive appearance coupling factor is lower than the third independent threshold. Although such weld points meet the minimum strength requirements, their overall appearance quality is low, indicating defects such as poor wetting, insufficient filling, or voids at the welding interface, and their connection reliability is at risk of long-term degradation. The criteria for determining the hidden fracture risk area are: the maximum tensile strength of the tested weld point is not lower than the first independent threshold. The weld point must meet one of the following conditions: its comprehensive appearance coupling factor is not lower than the third independent threshold, and it must also meet one of the following conditions: the failure category code of the weld point under test belongs to the high-risk failure mode set, or the fracture energy of the weld point under test is lower than the calculated average fracture energy value of a specific sample subset in the healthy weld point cluster minus a preset fluctuation amount. The specific sample subset consists of all samples in the healthy weld point cluster whose maximum tensile force and comprehensive appearance coupling factor fall within a preset neighborhood centered on the corresponding value of the weld point under test. Such weld points exhibit high-risk characteristics due to their failure modes or their toughness level is lower than that of similar healthy weld points, indicating potential brittle fracture or weak interface bonding. The judgment rule for unqualified areas is that weld points under test that do not meet any of the judgment rules for the above-mentioned consistency qualified area, disguised strength risk area, and hidden fracture risk area mainly include weld points with a maximum tensile force lower than the first independent threshold.

[0026] The present invention is further configured such that S4 includes: Determine the comprehensive appearance coupling factor of the weld joint under test, and obtain its maximum tensile force, fracture energy and failure location; Based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor of the weld point to be tested, the weld point to be tested is mapped to a three-dimensional feature space, and the Mahalanobis distance between its coordinate vector in the three-dimensional feature space and the mean vector of the healthy weld point cluster is calculated. Based on the judgment area and judgment rules, the following logical judgment is performed: If the maximum tensile strength of the weld joint under test is lower than the first independent threshold or the fracture energy of the weld joint under test is lower than the second independent threshold, the weld joint under test is determined to be unqualified. If the maximum tensile strength of the weld joint under test is not lower than the first independent threshold, then proceed with the subsequent judgments in sequence: If the overall appearance coupling factor of the solder joint under test is lower than the third independent threshold, the solder joint under test is determined to be at risk of camouflage strength. If the comprehensive appearance coupling factor of the solder joint under test is not lower than the third independent threshold, then further judgment is made: if the failure location of the solder joint under test belongs to the set of high-risk failure modes, or if the fracture energy of the solder joint under test is lower than the maximum tensile force in the healthy solder joint cluster and the comprehensive appearance coupling factor falls within the average fracture energy value of all samples in the preset neighborhood centered on the corresponding value of the solder joint under test minus the preset fluctuation amount, then the solder joint under test is judged to be a hidden fracture risk. If the conditions for determining the risk of camouflage strength and the risk of hidden breakage are not met, and the Mahalanobis distance is less than or equal to the preset statistical distance threshold, then the weld point to be tested is determined to be of acceptable consistency. Output the judgment conclusion of the weld point under test, which is either qualified, has a risk of camouflage strength, has a risk of hidden fracture, or is unqualified. Specifically, the comprehensive appearance coupling factor of the weld point under test is calculated according to the rules established in step S2, and the maximum tensile force and fracture energy are extracted from the tensile-displacement curve generated by its destructive mechanical test. At the same time, the failure category code used to record its specific failure location is obtained. The weld point under test is mapped to a pre-constructed three-dimensional feature space according to its maximum tensile force, fracture energy, and comprehensive appearance coupling factor, and the Mahalanobis distance between the coordinate vector of the weld point under test in the three-dimensional feature space and the mean vector of the healthy weld point cluster is calculated. Then, a set of rules is executed. The hierarchical logic judgment process for the judgment area and judgment rules defined in step S3 is as follows: This logic judgment process first performs a basic admission check, that is, it determines whether the maximum tensile strength of the solder joint under test is lower than the first independent threshold. If the maximum tensile strength of the solder joint under test is lower than the first independent threshold or the fracture energy of the solder joint under test is lower than the second independent threshold, then the solder joint under test is directly judged as unqualified and all subsequent judgment processes are terminated. If the maximum tensile strength of the solder joint under test is not lower than the first independent threshold, then it enters the risk rule matching stage. This stage first performs a camouflage strength risk check, that is, it determines whether the comprehensive appearance coupling factor of the solder joint under test is lower than the third independent threshold. If the comprehensive appearance coupling factor of the solder joint under test is lower than the third independent threshold, then the camouflage strength risk check is performed. If the coefficient of variation of the weld point is below the third independent threshold, the weld point under test is determined to be at risk of camouflaged strength. If the comprehensive appearance coupling factor of the weld point under test is not lower than the third independent threshold, a further check for potential fracture risk is performed. The triggering condition is one of the following two conditions. If either condition is met, the weld point under test is determined to be at risk of potential fracture: Condition 1 is that the failure category code of the weld point under test belongs to the set of high-risk failure modes; Condition 2 is that the fracture energy of the weld point under test is lower than the calculated average fracture energy value of a specific sample subset in the healthy weld point cluster minus a preset fluctuation amount. If the weld point under test does not meet any of the above risk judgment conditions, it enters the final consistency qualification judgment. At this time, its Mahalanobis distance needs to be determined. If the Mahalanobis distance is less than or equal to the statistical distance threshold, the solder joint under test is determined to be of acceptable consistency. If the Mahalanobis distance is greater than the statistical distance threshold, the solder joint under test does not meet any of the definitions of the acceptable consistency area, the camouflage strength risk area, or the hidden breakage risk area because it deviates from the healthy cluster in a statistical sense. Therefore, it is classified into the unacceptable area according to the judgment rule established in step S3. After completing the logical judgment process, the final judgment conclusion of the solder joint under test, whether it is of acceptable consistency, camouflage strength risk, hidden breakage risk, or unacceptable, is output. This judgment conclusion is the quality judgment result made on the solder joint pull force and solder crawling consistency.

[0027] The present invention is further configured such that S5 includes: For the same production batch, the quality judgment results of all solder joints in the batch are statistically analyzed, and the batch non-conformance rate and the batch comprehensive risk rate of the batch are calculated. The present invention is further configured such that the batch non-conformance rate is the proportion of the number of solder joints judged as non-conforming to the total number of solder joints in the batch; and the batch comprehensive risk rate is the proportion of the sum of the number of solder joints judged as having camouflage strength risk and hidden fracture risk to the total number of solder joints in the batch. Calculate the batch mean of the overall appearance coupling factor for all solder joints within this batch; The failure mode distribution of this batch is obtained by statistically analyzing the frequency of occurrence of each failure location category in all solder joints within the batch. The batch average of batch nonconformity rate, batch comprehensive risk rate, and comprehensive appearance coupling factor is monitored. A process warning is triggered when any of the following conditions are met: The batch non-conformance rate, the batch comprehensive risk rate, or the batch mean of the comprehensive appearance coupling factor exceeds the preset statistical control limit. The batch non-conformance rate or the batch comprehensive risk rate shows a monotonically increasing trend in a continuously preset number of batches. In the failure mode distribution, the frequency of any failure location category is consistently higher than a preset multiple of its historical average frequency in a consecutive preset number of batches. Specifically, for production batches that have completed step S4, the quality judgment results of all solder joints in the batch are summarized, and core batch-level quality indicators are calculated based on this complete dataset: the first indicator is the batch non-conforming rate, which is the ratio of the number of solder joints judged as non-conforming in the batch to the total number of solder joints in the batch; the second indicator is the batch comprehensive risk rate, which is the sum of the number of solder joints judged as having camouflage strength risk and hidden fracture risk in the batch to the total number of solder joints in the batch. The third item is the batch average of the comprehensive appearance coupling factor, which is the arithmetic mean of the comprehensive appearance coupling factor values ​​of all solder joint samples in the batch, used to characterize the average level of the batch in the overall appearance quality dimension; obtain the failure category codes recorded after destructive mechanical testing of all solder joints in the batch, including qualified solder joints, solder joints with disguised strength risk, solder joints with hidden fracture risk, and unqualified solder joints, and the preset complete set of failure location categories, count the occurrence frequency of each failure location category in the batch, and calculate the proportion of the occurrence frequency of each failure location category to the total number of solder joints in the batch to obtain the occurrence of each failure location category. Frequency is determined by summarizing all failure location categories and their corresponding frequencies to form the failure mode distribution of the batch. This failure mode distribution quantifies the main location modes of weld point fracture in this batch and their relative proportions. An automated monitoring and early warning mechanism based on statistical process control theory is established and implemented. This mechanism continuously tracks and monitors the three quality indicators mentioned above: batch non-conforming rate, batch comprehensive risk rate, and batch mean of comprehensive appearance coupling factor. Based on historical stable production data, statistical control limits are pre-set for each monitored quality indicator to define its normal fluctuation range under controlled conditions. The warning is triggered according to the following rules. A process warning is triggered when any one of the rules is met: Rule 1 is that the quality index exceeds the limit, that is, the batch non-conforming rate, the batch comprehensive risk rate, or the batch average value of the comprehensive appearance coupling factor of the current production batch exceeds the statistical control limit preset for the quality index; Rule 2 is that the trend is abnormal, that is, the batch non-conforming rate or the batch comprehensive risk rate shows a monotonically increasing trend in the production batches that have reached a preset number of consecutive batches; Rule 3 is that the pattern is abnormal, that is, in the failure mode distribution of the current batch, the frequency of occurrence of any failure location category is consistently higher than a preset multiple of its historical average frequency in the batches that have reached a preset number of consecutive batches.

[0028] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining the consistency between solder pull force and solder creep of tin-plated pins, characterized in that, include: S1: Obtain the apparent morphology parameters and mechanical property parameters of the solder joint; the apparent morphology parameters include solder creep height, solder creep wrap angle and solder filling volume; the mechanical property parameters include the maximum tensile force and fracture energy extracted from the tensile-displacement curve, as well as the specific failure location recorded after failure; S2: Analyze the correlation between appearance morphology parameters and mechanical property parameters, and calculate the comprehensive appearance coupling factor that characterizes the overall appearance quality of the weld joint based on this correlation; Analyze the statistical correlation between different failure locations and mechanical performance parameters and comprehensive appearance coupling factors, and define a set of high-risk failure modes; S3: Construct a three-dimensional feature space based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor. Define a healthy weld point cluster based on the joint probability density distribution of historical qualified weld point samples in the three-dimensional feature space, and pre-set independent thresholds for each parameter. Based on the statistical characteristics, independent thresholds, and high-risk failure mode set of the healthy weld point cluster, define the judgment area and judgment rules to distinguish between consistent qualified weld points, disguised strength risk weld points, hidden fracture risk weld points, and unqualified weld points. S4: Determine the comprehensive appearance coupling factor of the weld point to be tested, and obtain its maximum tensile force, fracture energy and failure location; map the weld point to be tested to a three-dimensional feature space according to its maximum tensile force, fracture energy and comprehensive appearance coupling factor, and make a judgment according to the judgment area and judgment rules, and output the judgment conclusion of consistency qualified, camouflage strength risk, hidden fracture risk or unqualified. S5: Statistically analyze the quality judgment results of all solder joints within the same production batch, calculate the batch non-conforming rate, batch comprehensive risk rate, and batch average of comprehensive appearance coupling factor for that batch. When the batch non-conforming rate, batch comprehensive risk rate, or batch average of comprehensive appearance coupling factor exceeds the preset statistical control limit or shows a preset abnormal statistical trend, trigger a process warning.

2. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, The independent thresholds for each parameter include the independent threshold for maximum tensile force, the independent threshold for fracture energy, and the independent threshold for the comprehensive appearance coupling factor.

3. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, The quality judgment result is the judgment conclusion output by step S4, which is either "consistency qualified", "camouflage strength risk", "hidden danger breakage risk", or "unqualified".

4. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, S1 includes: A predetermined number of tin-plated PIN pin welding samples were randomly selected from the production batch to be tested and fixed. The solder joint area of ​​each fixed tin-plated PIN pin soldering sample was three-dimensionally scanned using a white light interferometer or a laser confocal microscope to obtain three-dimensional point cloud data of the solder joint surface; based on the three-dimensional point cloud data, the appearance morphology parameters including solder creep height, solder creep wrap angle and solder filling volume were calculated through geometric analysis. Each tin-plated PIN solder sample was subjected to axial tensile or pull-out tests on a material testing machine until the solder joint broke. During the test, the tensile force-displacement curve was recorded synchronously at a preset sampling rate. Mechanical property parameters, including the maximum breaking force and fracture energy, were extracted from the tensile force-displacement curve. The fracture surface morphology of each weld point was observed under a stereomicroscope, and the specific failure location was recorded according to the preset failure category coding rules. The appearance morphology parameters and mechanical property parameters are normalized, and outliers are removed based on statistical distribution criteria.

5. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 4, characterized in that, The solder climb height is the maximum vertical height that the solder climbs along the side of the PIN pin. The solder wrapping angle is the circumferential angle of the solder wetting and covering on the cross-section of the PIN pin; The solder filling volume is the total volume of solder filling between the PIN pin and the pad, calculated based on the reconstructed solder joint solid model using 3D point cloud data. The maximum breaking force is the peak tensile force on the force-displacement curve; The fracture energy is the area obtained by integrating the tensile-displacement curve from the starting point to the fracture point.

6. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, S2 includes: For each appearance morphology parameter, the Pearson correlation coefficient between it and the maximum tensile force and fracture energy is calculated. Appearance morphology parameters whose absolute values ​​of the Pearson correlation coefficient with the maximum tensile force and fracture energy are all greater than the preset correlation screening threshold are selected to form a set of key appearance features. Principal component analysis is performed on all key appearance feature parameters in the key appearance feature set to obtain the variance contribution rate and eigenvector of each principal component. The principal component whose cumulative variance contribution rate first exceeds the preset contribution rate threshold is identified as the feature fusion principal component, and its corresponding eigenvector is obtained. This eigenvector contains the weight coefficients corresponding to each key appearance feature parameter. After normalizing the key appearance feature parameters of each historical solder joint sample, they are multiplied by the corresponding weight coefficients and summed to obtain the comprehensive appearance coupling factor of the solder joint sample. For each preset failure location category, the following processing is performed: count the number of samples belonging to that failure location category in all historical weld point samples, and calculate the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor of all weld point samples under that failure location category; use analysis of variance or nonparametric hypothesis testing to determine whether there are statistically significant differences in the mean maximum tensile force, mean fracture energy, and mean comprehensive appearance coupling factor between different failure location categories. Based on the results of the significant difference analysis, failure location categories that meet any of the following conditions will be included in the high-risk failure mode set: the mean maximum tensile force of the weld samples in this failure location category is lower than the preset lower quantile of the distribution of the maximum tensile force of the overall historical weld samples; the mean fracture energy of the weld samples in this failure location category is lower than the preset lower quantile of the distribution of the overall fracture energy of the overall historical weld samples; the mean comprehensive appearance coupling factor of the weld samples in this failure location category is lower than the preset lower quantile of the distribution of the comprehensive appearance coupling factor of the overall historical weld samples.

7. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, S3 includes: A three-dimensional feature space characterizing the quality status of weld joints is constructed using the maximum tensile force, fracture energy, and comprehensive appearance coupling factor as three orthogonal dimensions. A preset number of historical qualified solder joint samples are mapped to a three-dimensional feature space based on their respective maximum tensile force, fracture energy, and comprehensive appearance coupling factor. Based on the positional distribution of the historical qualified solder joint samples in the three-dimensional feature space, their joint probability density distribution is fitted by multivariate kernel density estimation. Spatial regions with probability density values ​​higher than a preset density threshold are defined as healthy solder joint clusters. The mean vector and covariance matrix of the healthy solder joint clusters are calculated. Based on the statistical characteristics of healthy weld joint clusters, the set of high-risk failure modes, a pre-set first independent threshold for maximum tensile force, a second independent threshold for fracture energy, and a third independent threshold for comprehensive appearance coupling factor, the following four mutually exclusive decision regions are delineated in the three-dimensional feature space, and their decision rules are defined: The criteria for determining a consistent and qualified area are as follows: the maximum tensile strength of the weld point under test is not lower than the first independent threshold, the fracture energy is not lower than the second independent threshold, the comprehensive appearance coupling factor is not lower than the third independent threshold, and the Mahalanobis distance between the coordinate vector of the weld point under test in the three-dimensional feature space and the mean vector of the healthy weld point cluster is less than or equal to a preset statistical distance threshold; the Mahalanobis distance is calculated based on the covariance matrix of the healthy weld point cluster. The criteria for determining the camouflage strength risk area are as follows: the maximum tensile strength of the weld point to be tested is not lower than the first independent threshold and the comprehensive appearance coupling factor is lower than the third independent threshold. The criteria for determining the potential fracture risk area are as follows: the maximum tensile strength of the weld joint under test is not lower than the first independent threshold and the comprehensive appearance coupling factor is not lower than the third independent threshold, and it meets any of the following conditions: the failure location of the weld joint under test belongs to the set of high-risk failure modes; the fracture energy of the weld joint under test is lower than the average fracture energy value of all samples in the healthy weld joint cluster whose maximum tensile strength and comprehensive appearance coupling factor fall within a preset neighborhood centered on the value of the weld joint under test, minus a preset fluctuation amount. The non-conforming area is determined by the following rules: the weld point under test does not meet any of the judgment rules of the consistency qualified area, the camouflage strength risk area, and the hidden fracture risk area.

8. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, S4 includes: Determine the comprehensive appearance coupling factor of the weld joint under test, and obtain its maximum tensile force, fracture energy and failure location; Based on the maximum tensile force, fracture energy, and comprehensive appearance coupling factor of the weld point to be tested, the weld point to be tested is mapped to a three-dimensional feature space, and the Mahalanobis distance between its coordinate vector in the three-dimensional feature space and the mean vector of the healthy weld point cluster is calculated. Based on the judgment area and judgment rules, the following logical judgment is performed: If the maximum tensile strength of the weld under test is lower than the first independent threshold or the fracture energy of the weld under test is lower than the second independent threshold, the weld under test is deemed unqualified. If the maximum tensile strength of the weld joint under test is not lower than the first independent threshold, then proceed with the subsequent judgments in sequence: If the overall appearance coupling factor of the solder joint under test is lower than the third independent threshold, the solder joint under test is determined to be at risk of camouflage strength. If the comprehensive appearance coupling factor of the solder joint under test is not lower than the third independent threshold, then further judgment is made: if the failure location of the solder joint under test belongs to the set of high-risk failure modes, or if the fracture energy of the solder joint under test is lower than the maximum tensile force in the healthy solder joint cluster and the comprehensive appearance coupling factor falls within the average fracture energy value of all samples in the preset neighborhood centered on the corresponding value of the solder joint under test minus the preset fluctuation amount, then the solder joint under test is judged to be a hidden fracture risk. If the conditions for determining the risk of camouflage strength and the risk of hidden breakage are not met, and the Mahalanobis distance is less than or equal to the preset statistical distance threshold, then the weld point to be tested is determined to be of acceptable consistency. Output the judgment conclusion of the weld point under test: whether it is qualified, has a risk of camouflage strength, has a risk of hidden fracture, or is unqualified.

9. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 1, characterized in that, S5 includes: For the same production batch, the quality judgment results of all solder joints within the batch are statistically analyzed, and the batch non-conformance rate and the overall batch risk rate are calculated. Calculate the batch mean of the overall appearance coupling factor for all solder joints within this batch; The failure mode distribution of this batch is obtained by statistically analyzing the frequency of occurrence of each failure location category in all solder joints within the batch. The batch average of batch nonconformity rate, batch comprehensive risk rate, and comprehensive appearance coupling factor is monitored. A process warning is triggered when any of the following conditions are met: The batch non-conformance rate, the batch comprehensive risk rate, or the batch mean of the comprehensive appearance coupling factor exceeds the preset statistical control limit. The batch non-conformance rate or the batch comprehensive risk rate shows a monotonically increasing trend in a continuously preset number of batches. In the failure mode distribution, the frequency of occurrence of any failure location category is consistently higher than a preset multiple of its historical average frequency in a consecutive preset number of batches.

10. The method for determining the consistency of solder pull force and solder creep of tin-plated PIN pins according to claim 9, characterized in that, The batch non-conforming rate is the proportion of the number of solder joints judged to be non-conforming to the total number of solder joints in that batch. The overall risk rate for the batch is the ratio of the sum of the number of weld points identified as having camouflage strength risk and hidden breakage risk to the total number of weld points in that batch.

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