Testing and Sorting Method for MLCC

Abstract

The present application relates to a test and sorting method for MLCCs, which is applicable to a test device including a plurality of annular test tracks. The method includes the following steps: batch testing MLCC products on different tracks to obtain test data; calculating a dynamic test reference value based on the data distribution, comparing it with a preset fixed threshold to determine the screening criteria; and during subsequent testing, sorting qualified products and defective products according to the screening criteria. Compared with the traditional fixed-threshold screening method, the present application can adapt to batch differences and equipment aging, improve the screening accuracy, reduce misjudgment, and improve the intelligent level of MLCC product quality control.

Description

Technical Field

[0001] This application relates to the technical field of MLCC product testing, and particularly to a testing and sorting method for MLCCs. Background Art

[0002] As a commonly used passive component in electronic products, the chip multi-layer ceramic capacitor (MLCC) has extremely high requirements for its electrical performance. In particular, the leakage current parameter directly affects the long-term reliability of the device and the safety of the circuit. During the manufacturing process of MLCCs, leakage current testing is an important part of quality screening. Usually, a testing and sorting machine is used for large-scale detection to ensure that the products leaving the factory meet the quality requirements.

[0003] Currently, commonly used MLCC testing and sorting machines in the industry, such as multi-test track testing equipment with 3 tracks, 4 tracks, 6 tracks, 8 tracks, 12 tracks, etc., usually work in the following ways:

[0004] MLCC products enter the test holes of the test disk through vacuum adsorption to form a fixed test circuit; the test disk rotates to drive the MLCCs into the test stations one by one, and the test is completed through the upper and lower electrodes (test rollers + axles); the test system records the leakage current data and sorts according to a set fixed threshold, that is: leakage current ≤ set threshold → judged as a qualified product (OK). Leakage current > set threshold → judged as a defective product (NG) and rejected.

[0005] Taking the existing high-precision MLCC four-parameter testing mechanism (such as the comparative document CN218727718U) as an example, its testing mechanism completes multiple parameter tests of MLCCs in sequence by rotating the test disk to ensure the testing accuracy. In this comparative document, only 1 circular test track is shown on its test disk. In other existing technologies, there are also multiple mutually surrounding circular test tracks, such as multi-test track testing equipment with 3 tracks, 4 tracks, 6 tracks, 8 tracks, 12 tracks, etc.

[0006] Although the existing MLCC leakage current testing equipment can achieve batch automated detection, in practical applications, there are still the following significant problems:

[0007] (1) Changes in equipment status affect testing accuracy

[0008] Due to the long-term operation of the testing equipment, the wear of the rollers, axles of the test stations and the test disk will cause unstable contact between the product and the test electrodes, thereby affecting the leakage current test results.

[0009] (2) Poor test consistency between test tracks

[0010] Multi - test - track test equipment (such as an 8 - track tester), the contact time of products on each test track on the test disk is different, resulting in deviation of test results between test tracks: the inner test track has a long contact time, is fully charged, and the test value may be low; the outer test track has a short contact time, is undercharged, and the test value may be high.

[0011] (3) It is difficult to detect equipment anomalies in a timely manner

[0012] The existing test system lacks a monitoring mechanism for the health status of the equipment. Problems such as poor equipment contact and test fixture failures are often only discovered after the defective rate of a large batch increases, and early warning cannot be provided. Summary of the Invention

[0013] Based on this, the present application provides a test and sorting method for MLCCs that can solve the above - mentioned technical problems.

[0014] The above - mentioned object of the present application is achieved through the following technical solutions:

[0015] The present application provides a test and sorting method for MLCCs, which is applied to a test device including multiple circular test tracks. The method includes the following steps:

[0016] Batch - test MLCC products on different test tracks, and respectively obtain the test data of each test track;

[0017] Based on the distribution of the test data of each test track and a preset value - taking strategy, calculate the dynamic test reference value of this test track;

[0018] Compare each dynamic test reference value with a preset fixed threshold to determine the screening criteria for each test track: when the dynamic test reference value is lower than the fixed threshold, the screening criteria is the dynamic test reference value; when the dynamic test reference value is higher than the fixed threshold, the screening criteria is the fixed threshold;

[0019] Test subsequent MLCC products on different test tracks, and sort out qualified products and defective products according to the screening criteria.

[0020] In an optional embodiment, based on the distribution of the test data of each test track and a preset value - taking strategy, calculating the dynamic test reference value of this test track includes:

[0021] If the test data conforms to a normal distribution, calculate the dynamic test reference value according to the mean and standard deviation of the test data;

[0022] If the test data conforms to a skewed distribution, calculate the percentile value of the data of this test track as the dynamic test reference value.

[0023] In an alternative embodiment, the method for calculating the dynamic test reference value in the case of a normal distribution includes:

[0024] Calculating the mean μ and the standard deviation σ of the test data;

[0025] Using μ + 3σ as the dynamic test reference value;

[0026] The method for calculating the dynamic test reference value in the case of a skewed distribution includes:

[0027] Calculating the 99.865% percentile P99.865 of the test data and using it as the dynamic test reference value.

[0028] In an alternative embodiment, the following steps are further included:

[0029] Calculating the skewness coefficient and the kurtosis value of the test data;

[0030] When the absolute value of the skewness coefficient is less than a preset threshold and the kurtosis value is within a preset range, it is determined that the test data conforms to a normal distribution;

[0031] Otherwise, it is determined that the test data conforms to a skewed distribution.

[0032] In an alternative embodiment, the preset threshold is less than 0.5, and the preset range of the kurtosis value is between 2 and 4.

[0033] In an alternative embodiment, during the process of testing subsequent MLCC products on different test tracks, when a set trigger condition is met, the following steps are further included:

[0034] Calculating a new dynamic test reference value for the test track according to the real-time test data on each test track;

[0035] Comparing the new dynamic test reference value with the dynamic test reference value calculated in the previous time. If the deviation is greater than a first set deviation value, the screening criterion is updated according to the new dynamic test reference value.

[0036] In an alternative embodiment, the set trigger condition includes at least one of the following:

[0037] The set test time is reached, the set test quantity is reached.

[0038] In an alternative embodiment, the following steps are further included:

[0039] If the deviation between the new dynamic test reference value and the dynamic test reference value calculated in the previous time is less than a second set deviation value, the set test time is extended or the set test quantity is increased;

[0040] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the third set deviation value, then shorten the set test time or reduce the set test quantity;

[0041] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the second set deviation value and less than the third set deviation value, then maintain the set test time or shorten the set test quantity;

[0042] Wherein, the first set deviation value is greater than the second set deviation value and less than the third set deviation value.

[0043] In an alternative embodiment, the following steps are further included:

[0044] Obtain the dynamic test reference values calculated in the most recent N times and calculate their rate of change;

[0045] If the rate of change is greater than the set rate threshold, then trigger an alarm.

[0046] In an alternative embodiment, the following steps are further included:

[0047] If the rate of change is greater than the set rate threshold and the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the first set deviation value, then trigger a shutdown.

[0048] The present application has the following beneficial effects:

[0049] The test sorting method of MLCC of the present application, through the screening strategy of combining the dynamic test reference value with a fixed threshold, while improving the screening accuracy, enhances the adaptability of the system to batch changes and equipment aging, and improves the intelligent level of MLCC product quality control; when meeting the set trigger conditions, recalculate the dynamic test reference value, which can adapt to the fluctuations of test data in the production process, improve the real-time performance and effectiveness of the screening standard; by dynamically adjusting the test time and test quantity, optimize the update interval of the screening standard according to the data deviation size, improve the test efficiency, reduce unnecessary screening adjustments, and improve production stability; also calculate the rate of change based on the most recent N dynamic test reference values and trigger an alarm when exceeding the set threshold, which can detect production or equipment abnormalities in advance and prevent a large number of defective products from flowing into the subsequent process due to the failure of the screening standard; when the rate of change exceeds the limit and the deviation of the dynamic test reference value exceeds the set threshold, trigger a shutdown, which can automatically pause production when the screening standard mutates, avoid quality accidents, and improve the reliability and safety of the production line. Description of the Drawings

[0050] Figure 1Schematic diagram of the steps of the MLCC test sorting method in an exemplary embodiment. Detailed implementation manners

[0051] To make the above objects, features, and advantages of the present application more obvious and understandable, the following provides a detailed description of the specific implementation manners of the present application. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0052] In addition, the terms "first", "first" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "first" may explicitly or implicitly include at least one of such features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0054] In view of the technical problems in the background art, the present application provides an MLCC test sorting method, which is applied to a test device including a plurality of circular test tracks, overcomes the defect of the traditional method that can only perform defective product sorting by setting a fixed threshold for each test track, can dynamically adjust the screening criteria according to the distribution of the actual test data of the MLCC leakage current, improves the accuracy of MLCC screening, and reduces the misjudgment problem caused by production batch fluctuations or equipment aging.

[0055] As Figure 1 shown, in one embodiment, the MLCC test sorting method of the present application includes the following steps:

[0056] S01: Batch test MLCC products on different test tracks, and respectively obtain the test data of each test track.

[0057] During the production process of MLCCs, products from different batches may have slightly different performances due to differences in production processes, raw materials, environmental factors, and equipment status. Especially in leakage current tests, such differences may affect the accuracy of screening. Therefore, when implementing the method of this application, it is first necessary to select a certain number (such as 100 pcs or more) of MLCC products on each test track for batch preliminary testing to obtain the test data of each test track. These data are used to analyze the leakage current distribution of MLCC products and provide a basis for setting subsequent screening criteria.

[0058] In the test equipment applied in the embodiments of this application, multiple annular test tracks are arranged on the test disk in a concentric circle manner. The MLCC products on each test track are placed into the disk holes by automated equipment, and voltages are applied through the electrodes at both the upper and lower ends for testing. This method is not only applicable to the leakage current test of MLCCs but also applicable to similar electrical parameter tests, such as insulation resistance tests, etc.

[0059] S02: Calculate the dynamic test reference value of this test track based on the distribution of the test data of each test track and a preset value-taking strategy.

[0060] Since the distribution of test data of MLCC products may vary, in order to reasonably set the screening criteria, the method of this application calculates the dynamic test reference value of each test track based on the actual distribution of test data. During the actual test process, the test data may show a normal distribution or a skewed distribution. Therefore, different calculation strategies need to be adopted:

[0061] If the test data conforms to a normal distribution, calculate the mean (μ) and standard deviation (σ), and use μ + 3σ as the dynamic test reference value to ensure that 99.865% of the product data is within the screening range, and only extreme outliers are excluded. In other embodiments, the dynamic test reference value can also be μ + 2σ, or μ + σ, etc.

[0062] If the test data conforms to a skewed distribution, use the percentile method (such as the 99.865% percentile) to calculate the dynamic test reference value to avoid an unreasonable screening range caused by data skewness.

[0063] Before calculating the dynamic test reference value, preferably, this method can also pre-exclude obvious abnormal data (such as abnormally small values caused by poor equipment contact or abnormally large values caused by defective MLCCs) to ensure the accuracy and representativeness of the screening criteria. Compared with the traditional fixed-threshold screening method, the method of this application can adapt to the data distribution of different batches of products, improve the screening accuracy, and reduce the misjudgment rate.

[0064] S03: Compare each of the dynamic test reference values with a preset fixed threshold to determine the screening criteria for each test track: when the dynamic test reference value is lower than the fixed threshold, the screening criteria is the dynamic test reference value; when the dynamic test reference value is higher than the fixed threshold, the screening criteria is the fixed threshold.

[0065] In the method of the present application, the dynamic test reference value is usually lower than the fixed threshold, and the main reasons are as follows:

[0066] Factors such as equipment aging and poor contact usually result in a smaller measured value of leakage current rather than a larger one. Therefore, the measured dynamic test reference value is generally less than the fixed upper limit value.

[0067] The dynamic test reference value of each test track is calculated based on the measured data of the current batch, which can adapt to the characteristics of the current product and avoid screening misjudgment caused by batch differences.

[0068] Therefore, in the method of the present application, the setting of each screening criteria follows the following principle:

[0069] When the dynamic test reference value is less than the fixed threshold, it indicates that the overall leakage current distribution of the products in this batch is small. At this time, directly use the dynamic test reference value as the screening criteria to ensure the rationality of screening, improve the production yield, and avoid misjudging qualified products as defective products due to over-screening.

[0070] When the dynamic test reference value is higher than the fixed threshold, it means that the overall leakage current level of the products in the current batch is high. In order to prevent defective products from flowing into the subsequent process, the fixed threshold is used as the screening criteria to ensure the consistency of quality requirements.

[0071] S04: Test subsequent MLCC products on different test tracks and sort out qualified products and defective products according to the screening criteria.

[0072] After determining the screening criteria for each test track, the method of the present application enters the formal test stage to perform a screening operation on the subsequent MLCC products entering the test. This screening process mainly includes the following steps:

[0073] In the test equipment, the MLCC products sequentially enter the disk holes of the test track. The test probes apply a set voltage to the MLCC through the upper and lower electrodes and measure its leakage current value.

[0074] Classify the test results according to the screening criteria of this test track:

[0075] If the measured leakage current value ≤ the screening criteria, it is determined that the MLCC product is a qualified product (OK) and can enter the next process or packaging.

[0076] If the measured leakage current value > the screening standard, then the MLCC product is determined to be a defective product (NG), and it is removed from the test track through an automatic rejection device to prevent it from entering the subsequent production process.

[0077] The test and sorting method of the MLCC of the present application is more adaptable and stable compared with the traditional fixed threshold screening method:

[0078] Reduce misjudgment: Since the dynamic test reference value is generally lower than the fixed threshold, the screening standard can be automatically adjusted according to the batch characteristics, avoiding misjudgment problems caused by equipment status or batch fluctuations;

[0079] Prevent abnormal batches from affecting quality control: If the dynamic test reference value of a certain batch is too high, then the fixed threshold is forcibly adopted to ensure that the product quality will not decline;

[0080] Adapt to the aging of the equipment: If the measurement is low due to equipment aging, the dynamic test reference value will decrease accordingly, thus avoiding too strict screening standards caused by changes in equipment status.

[0081] In order to ensure the rationality of the screening standard, the test data may need to be classified as a normal distribution or a skewed distribution, so as to determine which screening strategy to use. In a preferred embodiment, the present application further includes analyzing the distribution characteristics of the test data to select a suitable screening method.

[0082] The analysis process specifically includes calculating the skewness coefficient (Skewness) and calculating the kurtosis (Kurtosis). The skewness coefficient is used to measure the symmetry of the data, that is, whether the data is evenly distributed around the mean. When the absolute value of the skewness coefficient is small (for example, less than 0.5), it means that the data is relatively symmetric and close to a normal distribution; the kurtosis value is used to measure the steepness of the data distribution, whether it is sharper or flatter than the standard normal distribution. If the kurtosis value is between 2 and 4, it means that the data distribution is relatively close to the standard normal distribution.

[0083] Preferably, if the absolute value of the skewness coefficient is less than 0.5 and the kurtosis value is between 2 and 4, then it is determined that the set of test data is a normal distribution, and the screening standard can be calculated using the mean and standard deviation. Otherwise, it is determined to be a skewed distribution, and the percentile method is used to calculate the screening standard.

[0084] In this embodiment, through data distribution analysis, it is ensured that the test data can match the best screening method, avoiding screening deviation caused by misjudging the distribution type; using the dual determination criteria of the skewness coefficient and the kurtosis value improves the accuracy of distribution recognition, making the test results more reliable; making the screening standard more adaptable to the characteristics of different batches of MLCC products, improving product consistency, and reducing the screening misjudgment rate.

[0085] Preferably, during the process of testing subsequent MLCC products on different subsequent test tracks, when the set trigger condition is met, the following steps are further included:

[0086] Calculate a new dynamic test benchmark value for each test track based on the real-time test data on that test track;

[0087] Compare the new dynamic test benchmark value with the dynamic test benchmark value obtained in the previous calculation. If the deviation is greater than the first set deviation value, update the screening criteria according to the new dynamic test benchmark value.

[0088] During the testing process, changes in equipment status, environmental factors, and batch characteristics may cause test data to deviate. At this time, it is necessary to recalculate the dynamic test benchmark value. In this embodiment, the method of the present application can monitor the changes in MLCC product test data in real time and dynamically adjust the screening criteria when the trigger condition is met.

[0089] If the deviation between the newly calculated dynamic test benchmark value and the value calculated in the previous time is large (exceeding the first set deviation value), the screening criteria are automatically adjusted to ensure the screening accuracy.

[0090] This adjustment process does not require manual intervention and is automatically completed by the system, improving the intelligence level of the production line.

[0091] In this embodiment, by dynamically adjusting the screening criteria, the method of the present application can adapt to the changes in MLCC product parameters during the production process, avoid the invalidation of the screening criteria; ensure that the screening criteria are always based on the latest test data, improving the real-time performance and accuracy of screening.

[0092] Specifically, the set trigger condition includes at least one of the following: the set test time is reached, the set test quantity is reached.

[0093] The method of the present application uses the test time and the test quantity as trigger conditions to ensure a reasonable calculation timing for the dynamic test benchmark value; when the set test time is reached, it is applicable to a test system with long-term continuous operation to prevent the screening criteria from becoming invalid due to long-term non-update; when the set test quantity is reached, it is applicable to a high-capacity production line to ensure the statistical representativeness of the test data and improve the accuracy of the screening criteria.

[0094] This embodiment adopts two trigger methods, improving the flexibility of updating the screening criteria, avoiding premature or late adjustment of the screening criteria, ensuring data representativeness, improving the screening accuracy; applicable to different production modes, improving the versatility of the method of the present application.

[0095] In a preferred embodiment, the test and sorting method for MLCC of the present application further includes the following steps:

[0096] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is less than the second set deviation value, extend the set test time or increase the set test quantity;

[0097] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the third set deviation value, shorten the set test time or reduce the set test quantity;

[0098] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the second set deviation value and less than the third set deviation value, maintain the set test time or set test quantity unchanged;

[0099] Wherein, the first set deviation value is greater than the second set deviation value and less than the third set deviation value.

[0100] The method of the present application can not only dynamically adjust the screening criteria, but also automatically optimize the test time or test quantity according to the fluctuation of the test data, ensuring the rationality of the test frequency and screening accuracy.

[0101] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is less than the second set deviation value: It indicates that the fluctuation of the test data is small, indicating that the production process is stable and the equipment status is normal. At this time, the test time interval can be appropriately extended or the test quantity can be increased to reduce unnecessary updates of the screening criteria, improve production efficiency, and avoid overly frequent adjustments of the screening criteria.

[0102] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the third set deviation value: It indicates that the change of the test data is large, which may be caused by factors such as production batch changes and equipment status changes. At this time, it is necessary to shorten the test time interval or reduce the test quantity in order to quickly respond to the data change, ensure that the screening criteria can be adjusted in time, and avoid excessive screening errors.

[0103] If the deviation between the new dynamic test reference value and the previously calculated dynamic test reference value is greater than the second set deviation value and less than the third set deviation value: It indicates that the data fluctuation is within the acceptable range and the screening criteria are still applicable. At this time, the test time interval and the test quantity remain unchanged, and the existing screening strategy is maintained.

[0104] This embodiment realizes the intelligent optimization of the update of the screening criteria by dynamically adjusting the test time and test quantity, reduces unnecessary screening adjustments, and improves production efficiency; ensures the stability of the update of the screening criteria, and avoids unnecessary misjudgments caused by overly frequent screening adjustments; enhances the equipment adaptability, can adaptively adjust the screening frequency according to factors such as equipment aging and production batch changes, and improves the long-term stability of screening.

[0105] In a preferred embodiment, the MLCC test and sorting method of the present application further includes the following steps:

[0106] Obtain the dynamic test reference values calculated in the most recent N times, and calculate their change rate;

[0107] If the change rate is greater than the set rate threshold, trigger an alarm.

[0108] In this embodiment, the method of the present application further introduces data change trend analysis. By calculating the change rate of the dynamic test reference values in the most recent N times, the stability of the test data is judged, and the alarm mechanism is triggered when necessary, so as to detect equipment or production anomalies in advance.

[0109] During the batch testing process, the system continuously records the dynamic test reference values of multiple batches. By analyzing the reference values in the most recent N times, the change trend of the data can be observed.

[0110] The formula for calculating the change rate is:

[0111] Change rate = (the latest reference value - the reference value N times before) / N.

[0112] The change rate reflects the fluctuation of the test data. If the change is too fast, it may indicate abnormal equipment status, large environmental changes, or fluctuations in the production process.

[0113] If the change rate exceeds the set rate threshold, trigger an alarm: the alarm information can be sent to the system interface or the management personnel for manual intervention to check the equipment or process status.

[0114] The MLCC test and sorting method of this embodiment can detect potential production anomalies or equipment problems in advance, prevent the screening criteria from failing due to data drift, improve production stability; enhance the prediction ability of the screening method, can give an alarm before the equipment or process fails, improve maintenance efficiency, and reduce losses; the screening system is more intelligent, can not only adapt to the current data changes, but also predict possible future anomalies.

[0115] In a more preferred embodiment, if the change rate is greater than the set rate threshold, and the deviation between the new dynamic test reference value and the dynamic test reference value calculated in the previous time is greater than the first set deviation value, trigger a shutdown.

[0116] In this embodiment, the method of the present application can not only trigger an alarm, but also automatically trigger a shutdown when the data change exceeds the acceptable range to prevent a large number of defective products from flowing into the subsequent production process.

[0117] Conditions for triggering shutdown: The rate of change is greater than the set rate threshold (indicating that the data is drifting rapidly). At the same time, the deviation between the newly calculated dynamic test reference value and the previous calculated value is greater than the first set deviation value (indicating a significant change in the reference value). When both of these conditions are met, shutdown is automatically triggered.

[0118] After triggering shutdown, the system performs the following operations:

[0119] Pause the operation of the test equipment to prevent a large number of abnormal products from entering the subsequent processes.

[0120] Send a shutdown alarm to notify the maintenance personnel to check the equipment status, including the contact condition of the test electrodes, the degree of equipment aging, the power supply stability, etc.

[0121] Record the abnormal data for analyzing the reason for shutdown and optimizing the screening criteria when restarting the equipment.

[0122] The test and sorting method of the MLCC in this embodiment can prevent a large number of NG products from flowing into the subsequent processes due to equipment abnormalities or production batch changes, improving the quality control ability of the production line; reducing the risk of a large number of misjudgments, avoiding a large number of qualified products being misjudged as defective products due to the sudden failure of the screening criteria, and improving the yield; improving the intelligent level of the production process. The system can automatically shut down according to the data trend, reducing manual intervention and improving management efficiency.

[0123] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0124] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A test and sorting method for MLCC, applied to a test device including a plurality of annular test tracks, wherein the plurality of annular test tracks are arranged on a test disk in a concentric circle manner, and the MLCC products located in the disk holes on each test track are tested by applying voltage to electrodes at the upper and lower ends, characterized in that: The method comprises the following steps: Batch test the MLCC products on different test tracks, and obtain test data of each test track respectively; Calculate the dynamic test reference value of each test track based on the distribution of the test data and a preset value selection strategy of the test track; Compare each of the dynamic test reference values ​​with a preset fixed threshold value to determine a screening criterion for each test track: when the dynamic test reference value is lower than the fixed threshold value, the screening criterion is the dynamic test reference value; when the dynamic test reference value is higher than the fixed threshold value, the screening criterion is the fixed threshold value; Subsequent MLCC products are tested on different test tracks, and qualified products and defective products are sorted out according to the screening criteria.

2. The MLCC testing and sorting method according to claim 1, characterized in that: Based on the distribution of the test data of each test track and a preset value strategy, a dynamic test reference value of the test track is calculated, including: If the test data conforms to a normal distribution, the dynamic test reference value is calculated according to the mean and standard deviation of the test data; If the test data conforms to the skewed distribution, the percentile value of the test track data is calculated as the dynamic test reference value.

3. The MLCC testing and sorting method according to claim 2, characterized in that: The calculation method of dynamic test benchmark value under normal distribution includes: Calculate the mean μ and standard deviation σ of the test data; μ+3σ is used as the dynamic test benchmark value; The calculation method of dynamic test benchmark value under skewed distribution includes: Calculate the 99.865% percentile P of the test data 99.865 , and use it as the dynamic test benchmark value.

4. The MLCC testing and sorting method according to claim 2, characterized in that: The following steps are also included: Calculating the skewness coefficient and kurtosis value of the test data; When the absolute value of the skewness coefficient is less than a preset threshold value and the kurtosis value is within a preset range, it is determined that the test data conforms to a normal distribution; Otherwise, it is determined that the test data conforms to the skewed distribution.

5. The MLCC testing and sorting method according to claim 4, characterized in that: The preset threshold is less than 0.5, and the preset range of the kurtosis value is between 2 and 4.

6. The MLCC testing and sorting method according to claim 2, characterized in that: In the process of testing subsequent MLCC products on different test tracks, when the set trigger conditions are met, the following steps are also included: Calculating a new dynamic test reference value of each test track according to the real-time test data on the test track; The new dynamic test reference value is compared with the dynamic test reference value calculated last time, and if the deviation is greater than a first set deviation value, the screening criterion is updated according to the new dynamic test reference value.

7. The MLCC testing and sorting method according to claim 6, characterized in that: The setting trigger condition includes at least one of the following: The set test time is reached, the set test quantity is reached.

8. The MLCC testing and sorting method according to claim 7, characterized in that: The following steps are also included: If the deviation between the new dynamic test reference value and the dynamic test reference value calculated last time is less than the second set deviation value, then extending the set test time or increasing the set test quantity; If the deviation between the new dynamic test reference value and the dynamic test reference value calculated last time is greater than a third set deviation value, shortening the set test time or reducing the set test quantity; If the deviation between the new dynamic test reference value and the dynamic test reference value calculated last time is greater than the second set deviation value and less than the third set deviation value, the set test time is maintained or the set test quantity is shortened; The first set deviation value is greater than the second set deviation value and less than the third set deviation value.

9. The MLCC testing and sorting method according to claim 6, characterized in that: The following steps are also included: Obtain the dynamic test reference value obtained by the most recent N calculations, and calculate its rate of change; If the rate of change is greater than a set rate threshold, an early warning is triggered.

10. The MLCC testing and sorting method according to claim 9, characterized in that: The following steps are also included: If the change rate is greater than a set rate threshold, and the deviation between the new dynamic test reference value and the dynamic test reference value calculated last time is greater than a first set deviation value, a shutdown is triggered.

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