A solder joint detection method for highly integrated circuit board

Abstract

The present application relates to the technical field of circuit board detection, and specifically to a method for detecting solder joints of highly integrated circuit boards, the method comprising: using an intelligent sensor to obtain the current signal at each moment in each circuit of the circuit board; obtaining the current signal sequence of each circuit; determining the interference influence coefficient of each subsequence in the current signal sequence of each circuit according to the discrete degree of each subsequence in the current signal sequence of each circuit when eliminating trend changes and the deviation of the current signal from the fundamental wave; determining the distribution consistency of each subsequence in the current signal sequence of each circuit according to the symmetry of the periodic changes between different subsequences in the current signal sequence of each circuit and the degree of similarity of the changes, combined with the interference influence coefficient; determining the electromagnetic influence index of each circuit, and detecting the solder joints of the circuit board. The present application can improve the accuracy of solder joint detection of highly integrated circuit boards.

Description

Technical Field

[0001] The present application relates to the technical field of circuit board detection, and in particular to a method for detecting solder joints of a highly integrated circuit board. Background Art

[0002] A highly integrated circuit board is a printed circuit board with higher circuit density and smaller component packaging. The guide holes and through holes on a highly integrated circuit board are smaller, which allows more circuits and components to be arranged on the same area of ​​the circuit board. Compared with traditional PCB boards, its solder joints are more prone to failure, so a more accurate solder joint detection method is needed to ensure the quality and reliability of the product.

[0003] Some methods use a multimeter to detect solder joints. However, the multimeter can only measure when the circuit board is not working, and cannot detect the circuit board in use. Therefore, a method that can detect solder joints when a highly integrated circuit board is working is needed. Since the width of the circuit and the spacing between components of the highly integrated circuit board are smaller, the circuit board has higher circuit complexity and integration, and the solder joints are smaller, which makes it easier to have defects such as cold solder joints during welding. These defects will make the electromagnetic interference problem of the highly integrated circuit board more serious and affect the integrity of the signal. The existing detection methods for highly integrated circuit boards fail to fully consider the impact of signal crosstalk and electromagnetic interference on the detection results, resulting in possible false positives and false negatives. Summary of the invention

[0004] In order to solve the above technical problems, a solder joint detection method for a highly integrated circuit board is provided to solve the existing problems.

[0005] The solution to the technical problem of the present application is to provide a solder joint detection method for a highly integrated circuit board, comprising the following steps:

[0006] Use intelligent sensors to obtain the current signal of each circuit of the circuit board at each moment;

[0007] The current signal of each line is divided according to the periodic characteristics of the current signal at all times, and the current signal sequence of each line is obtained; the interference influence coefficient of each subsequence in the current signal sequence of each line is determined according to the discrete degree of each subsequence in the current signal sequence of each line when the trend change is eliminated and the deviation of the current signal from the fundamental wave;

[0008] According to the symmetry of periodic changes between different subsequences in the current signal sequence of each line and the degree of similarity of changes, combined with the interference influence coefficient, the distribution consistency of each subsequence in the current signal sequence of each line is determined;

[0009] According to the discrete degree and difference of the distribution consistency of all subsequences in the current signal sequence of each circuit, the electromagnetic influence index of each circuit is determined, and the solder joints of the circuit board are detected.

[0010] Preferably, the method for acquiring the current signal sequence of each line is:

[0011] A variable-length subsequence clustering algorithm is used to extract subsequences from the current signals of each line at all times, and all subsequences are clustered;

[0012] Arrange the subsequences in all clusters in the order of acquisition time to form the current signal sequence of each line.

[0013] Preferably, determining the interference influence coefficient of each subsequence in the current signal sequence of each line includes:

[0014] Analyze the discrete degree of each subsequence in the current signal sequence of each line when eliminating trend changes, and determine the current mutation degree of each subsequence in the current signal sequence of each line;

[0015] Analyze the degree of deviation between the current signal of each subsequence and the fundamental wave in the current signal sequence of each line, and determine the harmonic influence of each subsequence in the current signal sequence of each line;

[0016] The current mutation degree and the harmonic influence degree are merged to determine the interference influence coefficient of each subsequence in the current signal sequence of each line.

[0017] Preferably, determining the degree of current mutation of each subsequence in the current signal sequence of each line includes:

[0018] A detrending fluctuation analysis algorithm is used for each subsequence in the current signal sequence of each line to obtain a subsequence without trend characteristics;

[0019] The discrete degree of the subsequence without trend feature is used as the current mutation degree of each subsequence in the current signal sequence of each line.

[0020] Preferably, determining the harmonic influence of each subsequence in the current signal sequence of each line includes:

[0021] A sliding window iteration algorithm is used for each subsequence in the current signal sequence of each line to obtain the fundamental wave subsequence of each subsequence;

[0022] The harmonic influence degree of each subsequence in the current signal sequence of each line is determined according to the difference degree between the fundamental wave subsequence and the corresponding subsequence of each subsequence in the current signal sequence of each line.

[0023] Preferably, determining the distribution consistency of each subsequence in the current signal sequence of each line includes:

[0024] Analyze the symmetry of periodic changes between each subsequence and adjacent subsequences in the current signal sequence of each line, and determine the waveform symmetry of each subsequence in the current signal sequence of each line;

[0025] Analyze the fluctuation similarity between each subsequence in the current signal sequence of each line and the adjacent subsequence in the same cluster to which it belongs, and determine the waveform similarity of each subsequence in the current signal sequence of each line in combination with the interference influence coefficient;

[0026] The ratio of the waveform similarity to the waveform symmetry is used as the distribution consistency of each subsequence in the current signal sequence of each line.

[0027] Preferably, determining the waveform symmetry of each subsequence in the current signal sequence of each line includes:

[0028] Calculate the skewness of the periodic sequence formed by each subsequence and the previous subsequence in the current signal sequence of each line, and record it as the first skewness;

[0029] Calculate the skewness of the periodic sequence formed by each subsequence and the next subsequence in the current signal sequence of each line, and record it as the second skewness;

[0030] The average of the first skewness and the second skewness is used as the waveform symmetry of each subsequence in the current signal sequence of each line.

[0031] Preferably, the determining of the waveform similarity of each subsequence in the current signal sequence of each line includes: in is the waveform similarity of the i-th subsequence in the current signal sequence of the k-th line, is the i-th subsequence in the current signal sequence of the k-th line, is the i-2th subsequence in the current signal sequence of the kth line, is the i+2th subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the ith subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the i-2th subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the i+2th subsequence in the current signal sequence of the kth line, and R() represents the calculated correlation coefficient.

[0032] Preferably, determining the electromagnetic impact index of each line includes:

[0033] The distribution consistency of all subsequences in the current signal sequence of each line is used to form a current distribution sequence of each line;

[0034] The mean value of the difference between the current distribution sequence of each line and the other lines is calculated, and the mean value is integrated with the discrete degree of the current distribution sequence of each line to determine the electromagnetic influence index of each line.

[0035] Preferably, the detection of the solder joints of the circuit board includes: normalizing the electromagnetic influence index of each circuit, if the normalization result is greater than or equal to a preset abnormal threshold, the solder joints at both ends of the circuit are defective, otherwise, the solder joints at both ends of the circuit are not defective.

[0036] This application has at least the following beneficial effects:

[0037] The present application divides the current signal according to the periodic characteristics of all moments in each line to obtain the current signal sequence of each line. The beneficial effect is that the periodic characteristics of the current signal are analyzed, and the current signal is divided according to the different change trends of the current signal, so that the local change characteristics can be better analyzed later; according to the discrete degree of each subsequence in the current signal sequence of each line when the trend change is eliminated and the degree of deviation of the current signal from the fundamental wave, the interference influence coefficient of each subsequence in the current signal sequence of each line is determined. The beneficial effect is that the influence of the trend change of each subsequence on the mutation degree analysis of the current signal is considered, and the mutation characteristics of the subsequence are more accurately reflected by eliminating the change trend characteristics, and by comparing the difference between the fundamental wave and the subsequence changes, the interference influence coefficient of each subsequence in the current signal sequence of each line is considered. The interference of harmonics on the current signal is taken into account; according to the symmetry of periodic changes and the similarity of changes between different subsequences in the current signal sequence of each line, combined with the interference influence coefficient, the distribution consistency of each subsequence in the current signal sequence of each line is determined, and its beneficial effect is that the periodic symmetry relationship and the similarity of fluctuations between subsequences are considered to reflect the stable state of local changes of subsequences; according to the discrete degree and difference of the distribution consistency of all subsequences in the current signal sequence of each line, the electromagnetic influence index of each line is determined, and the solder joints of the circuit board are detected. The beneficial effect is that the degree of electromagnetic interference between different lines is considered to reflect the stable working state of the line between the solder joints, and the accuracy of solder joint detection of the circuit board is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] A solder joint detection method for a highly integrated circuit board of the present application is further described in detail below in conjunction with the accompanying drawings.

[0039] Figure 1 A flowchart of a solder joint detection method for a highly integrated circuit board provided in an embodiment of the present application;

[0040] Figure 2 A flowchart of the steps of a method for obtaining the interference influence coefficient of each subsequence in the current signal sequence of each line provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present application more clear, the following is a further detailed description of a solder joint detection method for a highly integrated circuit board proposed in the present application in combination with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0043] See also Figure 1 , which shows a flow chart of a solder joint detection method for a highly integrated circuit board provided by an embodiment of the present application, the method comprising the following steps:

[0044] Step 1: Use intelligent sensors to obtain the current signal of each circuit of the circuit board at each moment.

[0045] Highly integrated circuit boards have finer lines and smaller spacing, and can integrate more circuits and components on the same area of ​​PCB. Secondly, the solder joints on the circuit board are small, and defects such as cold solder joints may exist during the welding process. And because the spacing between the lines is small, it is easy to cause electromagnetic interference between the lines, causing the waveform of the line current to be distorted.

[0046] Intelligent sensors are used to collect current data of all lines in the detection area of ​​a highly integrated circuit board. The solder joints on the circuit board are detected by analyzing the current data characteristics. The collection time interval is t, the collection time is T, and the current signal at each moment in each line is obtained.

[0047] Preferably, in this embodiment, the collection time interval is 1 ms and the collection duration is 20 s. As other implementation modes, the implementer can set them according to the actual situation.

[0048] At this point, the current signal at each moment in each line is obtained.

[0049] Step 2: divide the current signal of each line at all times according to the periodic characteristics of the current signal, and obtain the current signal sequence of each line; determine the interference influence coefficient of each subsequence in the current signal sequence of each line according to the discrete degree of each subsequence in the current signal sequence of each line when eliminating trend changes and the deviation degree of the current signal from the fundamental wave.

[0050] After the high-integration circuit board is welded, different solder joint qualities may lead to different current characteristics. When there are defects in the solder joints, such as unstable electrical connections and increased contact resistance, signal transmission quality may be reduced, signal loss or noise may increase. At the same time, poor solder joints may increase electromagnetic interference, affect the electromagnetic compatibility of the circuit, and cause performance degradation of other electronic devices or the circuit itself. Therefore, the quality of the solder joints can be evaluated by analyzing the current characteristics in the circuit.

[0051] Since the current signal collected at all times is an analog signal, the signal is a sinusoidal waveform with a certain periodicity. Defects in solder joints may cause transient circuit anomalies, which may show inconsistent local characteristics in current signals of different cycles. The originally smooth current waveform may cause spikes or nonlinear distortion in the current sequence within a cycle due to unstable connection or electromagnetic interference.

[0052] Therefore, in order to analyze the local current characteristics within a cycle, the collected current signal is first divided into cycles, specifically:

[0053] A variable-length subsequence clustering algorithm is used to extract subsequences from the current signals of each line at all times, and all subsequences are clustered;

[0054] Arrange the subsequences in all clusters in the order of acquisition time to form the current signal sequence of each line;

[0055] Preferably, in this embodiment, the variable-length subsequence clustering algorithm (Variable-length SubsequenceClustering) sets the minimum length of the subsequence to 8, the maximum length to 12, and the number of clusters to 2. As other implementation methods, the implementer can set them according to actual conditions. Among them, the variable-length subsequence clustering algorithm is a well-known technology and will not be repeated here.

[0056] It should be noted that the current signal of each line at all times presents a sinusoidal fluctuation process, and the current signal of each cycle shows two trends: rising and falling. The variable-length subsequence clustering algorithm divides the current signal at all times into two clusters, dividing the current data between the trough and the peak into one subsequence, and dividing all the current signals between the peak and the trough into another subsequence. All the subsequences from the trough to the peak belong to the same cluster, and all the subsequences from the peak to the trough belong to the same cluster, so a cycle is divided into two parts. Specifically, the subsequence represents the subsequence from the ith trough to the peak in the kth line, represents the subsequence from the i-th peak to the trough in the k-th line, and the two clusters are Then the current signal sequence of the kth line is in and Can constitute a complete cycle, and It can also constitute a complete cycle.

[0057] Furthermore, the waveform of each subsequence is analyzed to reflect the possibility of abnormal current signal. Since solder joint defects may cause unstable circuit connection, spike mutations are generated at random positions in the subsequence, and the subsequence has an upward or downward trend, these trends may interfere with the accurate identification of the spike features. Therefore, in order to better analyze the mutation characteristics of the subsequence, the subsequence is subjected to trend removal analysis to eliminate the trend characteristics in the subsequence, specifically:

[0058] A detrended fluctuation analysis algorithm (DFA) is used for each subsequence in the current signal sequence of each line to obtain a subsequence without trend characteristics, wherein the detrended fluctuation analysis algorithm is a well-known technology and will not be described in detail here;

[0059] The discrete degree of the subsequence without trend feature is used as the current mutation degree of each subsequence in the current signal sequence of each line;

[0060] Preferably, in this embodiment, the standard deviation of the subsequence without trend characteristics is calculated as the degree of current mutation of each subsequence in the current signal sequence of each line. As other implementation methods, the implementer may use other methods of the prior art to measure the degree of discreteness, such as variance, coefficient of variation, information entropy, etc. This embodiment does not impose any special restrictions on this.

[0061] Furthermore, electromagnetic interference between lines will generate some irregular harmonic currents, causing the collected current signal to deviate from the fundamental wave. By extracting the harmonic components in the subsequence, the degree to which the current is affected by the harmonic current is analyzed, specifically:

[0062] A sliding window iteration algorithm is used for each subsequence in the current signal sequence of each line to obtain the fundamental wave subsequence of each subsequence;

[0063] Determining the harmonic influence of each subsequence in the current signal sequence of each line according to the difference between the fundamental wave subsequence and the corresponding subsequence of each subsequence in the current signal sequence of each line;

[0064] Preferably, in this embodiment, the window function set for the sliding window iterative algorithm is a Hamming window, and the window length is 5. As other implementation methods, the implementer can set it according to the actual situation; the DTW distance between the fundamental wave subsequence and the corresponding subsequence of each subsequence in the current signal sequence of each line is used as the harmonic influence of each subsequence in the current signal sequence of each line; wherein, the sliding window iterative algorithm is a well-known technology and will not be described in detail here.

[0065] It is understandable that this embodiment uses DTW distance to measure the difference between two subsequences. As other implementations, implementers can use other methods in the prior art, such as cosine similarity, Euclidean distance, etc. This embodiment does not impose any special restrictions on this.

[0066] Further, based on the current mutation degree and the harmonic influence degree, the interference influence coefficient of each subsequence in the current signal sequence of each line is determined, specifically:

[0067] The current mutation degree and the harmonic influence degree are combined to determine the interference influence coefficient of each subsequence in the current signal sequence of each line;

[0068] It can be understood that the specific fusion relationship can be an addition relationship, a multiplication relationship, etc. The specific relationship is determined according to the actual scenario, and this embodiment does not impose any special restrictions on this.

[0069] Preferably, in this embodiment, the product of the current mutation degree and the harmonic influence degree is used as the interference influence coefficient of each subsequence in the current signal sequence of each line.

[0070] It should be noted that the greater the degree of current mutation, the greater the degree of mutation of the current signal in the corresponding subsequence, the greater the harmonic influence, the more harmonic components are contained in the current, and the more the obtained fundamental sequence deviates from the corresponding subsequence, that is, the greater the degree of influence of the subsequence by the harmonics; secondly, the greater the interference influence coefficient, the greater the degree of interference of the subsequence by the mutation or harmonics.

[0071] Further, the flowchart of the steps of the method for obtaining the interference influence coefficient of each subsequence in the current signal sequence of each line provided in the embodiment of the present application is as follows: Figure 2 shown.

[0072] At this point, the interference influence coefficient of each subsequence in the current signal sequence of each line is obtained.

[0073] Step 3: Determine the distribution consistency of each subsequence in the current signal sequence of each line according to the symmetry of periodic changes and the degree of similarity of changes between different subsequences in the current signal sequence of each line and the interference influence coefficient.

[0074] Furthermore, when the solder joints of highly integrated circuit boards are in good condition, the waveform of a single cycle of the corresponding line current is close to a standard sine wave, and the waveforms of adjacent cycles should also be relatively consistent. Therefore, the two adjacent subsequences in the current signal sequence have a high degree of symmetry, and the adjacent subsequences in the same cluster also have a high degree of similarity. The unstable connection caused by solder joint defects will reduce the symmetry of adjacent subsequences within a cycle and the consistency of adjacent cycles.

[0075] Based on the above analysis, the symmetry between adjacent subsequences in the current signal sequence is analyzed to determine the waveform symmetry, specifically:

[0076] Calculate the skewness of the periodic sequence formed by each subsequence and the previous subsequence in the current signal sequence of each line, and record it as the first skewness;

[0077] Calculate the skewness of the periodic sequence formed by each subsequence and the next subsequence in the current signal sequence of each line, and record it as the second skewness;

[0078] Taking the average of the first skewness and the second skewness as the waveform symmetry of each subsequence in the current signal sequence of each line;

[0079] It should be noted that, when calculating the waveform symmetry of the first subsequence and the last subsequence in the current signal sequence, the missing previous subsequence and the next subsequence are filled in by the mirror symmetry method; secondly, the skewness reflects the asymmetry of the data distribution. The closer the skewness is to 0, the higher the symmetry of the data distribution. The calculation method of the skewness is a well-known technology and will not be repeated here. The smaller the waveform symmetry, the higher the symmetry of the waveform between the corresponding subsequence and its adjacent subsequence.

[0080] Furthermore, since each subsequence in the current signal sequence of each line has a certain variation similarity with the subsequence in the cluster, the local similarity between adjacent subsequences in the same cluster is analyzed to determine the waveform similarity.

[0081] The adjacent subsequences of each subsequence in the same cluster are represented as the i-th subsequence, the i-2-th subsequence and the i+2-th subsequence in the current signal sequence, that is, the i-2-th subsequence and the i+2-th subsequence have a certain change similarity with the i-th subsequence respectively.

[0082] Therefore, the calculation method of the waveform similarity of each subsequence in the current signal sequence of each line is: in is the waveform similarity of the i-th subsequence in the current signal sequence of the k-th line, is the i-th subsequence in the current signal sequence of the k-th line, is the i-2th subsequence in the current signal sequence of the kth line, is the i+2th subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the ith subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the i-2th subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the i+2th subsequence in the current signal sequence of the kth line, and R() represents the calculated correlation coefficient.

[0083] It is understandable that the Pearson correlation coefficient is used to measure the similarity between two sequences in this embodiment. As other implementations, the implementer may use other methods in the prior art, such as cosine similarity, DTW distance, etc. This embodiment does not impose any special limitation on this.

[0084] It should be noted that, for the first subsequence and the last subsequence in the current signal sequence, when calculating the waveform similarity, the left similarity or right similarity of the subsequence is used as the waveform similarity of the subsequence; the greater the waveform similarity, the closer the interference degree of the corresponding subsequences in the local range within the same cluster is, and the greater the waveform similarity is.

[0085] Further, based on the waveform symmetry and the waveform similarity, the distribution consistency is determined, specifically:

[0086] The ratio of the waveform similarity to the waveform symmetry is used as the distribution consistency of each subsequence in the current signal sequence of each line;

[0087] It should be noted that the greater the waveform similarity, the higher the local similarity of the current in the same cluster; the smaller the waveform symmetry, the higher the symmetry of the subsequence with the waveforms of the previous and next sequences; the greater the obtained distribution consistency, the higher the consistency of the current signal distribution of the subsequence in the local range.

[0088] At this point, the distribution consistency of each subsequence in the current signal sequence of each line is obtained.

[0089] Step 4: determine the electromagnetic influence index of each circuit according to the discrete degree and difference of the distribution consistency of all subsequences in the current signal sequence of each circuit, and detect the solder joints of the circuit board.

[0090] Furthermore, based on the distribution consistency, the change trend of the distribution consistency of all subsequences is analyzed. The stability of the change can reflect the welding quality of each line solder joint. However, if a solder joint has a large defect, the current fluctuation generated further induces electromagnetic interference, resulting in irregular fluctuations in the current signal of the adjacent line. Therefore, the electromagnetic influence index of each line is analyzed, specifically:

[0091] The distribution consistency of all subsequences in the current signal sequence of each line is used to form the current distribution sequence of each line;

[0092] Calculating the mean of the difference between the current distribution sequence of each line and the other lines, fusing the mean with the discrete degree of the current distribution sequence of each line, and determining the electromagnetic influence index of each line;

[0093] Preferably, in this embodiment, the product of the mean of the DTW distance between each line and the current distribution sequence of the other lines and the coefficient of variation of the current distribution sequence of each line is used as the electromagnetic influence index of each line, wherein the DTW distance and the coefficient of variation are well-known technologies and will not be described in detail here.

[0094] It can be understood that this embodiment uses DTW distance to measure the difference between two sequences and uses the coefficient of variation to measure the degree of dispersion. As other implementation methods, implementers can use other methods in the prior art, such as Euclidean distance, cosine similarity, etc. to calculate the distribution difference of each line, and use standard deviation, variance, etc. to calculate the distribution dispersion of each line. This embodiment does not impose any special restrictions on this.

[0095] It should be noted that each line corresponds to two welding points, and the stability of the current distribution sequence can reflect the welding quality of the welding points. When the welding points are in good contact, the current distribution sequence is generally large and stable, and the smaller the coefficient of variation, if there is a large defect in one of the welding points, the current distribution sequence shows that some values ​​are significantly reduced, and the coefficient of variation is larger; the closer the consistency characteristics of the current distribution sequence between lines, the smaller the distribution difference; the smaller the electromagnetic influence index, the better the welding effect of the welding points at both ends of the line.

[0096] Furthermore, the electromagnetic influence index reflects the welding effect of the solder joints at both ends of the circuit. The smaller the electromagnetic influence index, the better the corresponding solder joint. Based on the electromagnetic influence index, the solder joints of the circuit board are tested, specifically:

[0097] The electromagnetic influence index of each line is normalized. If the normalized result is greater than or equal to the preset abnormal threshold, the solder joints at both ends of the line are defective. If the normalized result is less than the preset abnormal threshold, the solder joints at both ends of the line are not defective.

[0098] Preferably, in this embodiment, the Z-Score method is used for normalization processing; the preset abnormal threshold is 0.4, and as other implementation methods, the implementer can set it according to the actual situation.

[0099] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0100] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the present application. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the content of the technical solution of the present application, shall fall within the protection scope of the technical solution of the present application.

Claims

1. A solder joint detection method for a highly integrated circuit board, characterized in that: The method comprises the following steps: Use intelligent sensors to obtain the current signal of each circuit of the circuit board at each moment; The current signal of each line is divided according to the periodic characteristics of the current signal at all times, and the current signal sequence of each line is obtained; the interference influence coefficient of each subsequence in the current signal sequence of each line is determined according to the discrete degree of each subsequence in the current signal sequence of each line when the trend change is eliminated and the deviation of the current signal from the fundamental wave; According to the symmetry of periodic changes between different subsequences in the current signal sequence of each line and the degree of similarity of changes, combined with the interference influence coefficient, the distribution consistency of each subsequence in the current signal sequence of each line is determined; According to the discrete degree and difference of the distribution consistency of all subsequences in the current signal sequence of each circuit, the electromagnetic influence index of each circuit is determined, and the solder joints of the circuit board are detected.

2. A solder joint detection method for a highly integrated circuit board as claimed in claim 1, characterized in that: The method for acquiring the current signal sequence of each line is: A variable-length subsequence clustering algorithm is used to extract subsequences from the current signals of each line at all times, and all subsequences are clustered; Arrange the subsequences in all clusters in the order of acquisition time to form the current signal sequence of each line.

3. A solder joint detection method for a highly integrated circuit board as claimed in claim 1, characterized in that: The determining of the interference influence coefficient of each subsequence in the current signal sequence of each line includes: Analyze the discrete degree of each subsequence in the current signal sequence of each line when eliminating trend changes, and determine the current mutation degree of each subsequence in the current signal sequence of each line; Analyze the degree of deviation between the current signal of each subsequence and the fundamental wave in the current signal sequence of each line, and determine the harmonic influence of each subsequence in the current signal sequence of each line; The current mutation degree and the harmonic influence degree are merged to determine the interference influence coefficient of each subsequence in the current signal sequence of each line.

4. A solder joint detection method for a highly integrated circuit board as claimed in claim 3, characterized in that: The step of determining the degree of current mutation of each subsequence in the current signal sequence of each line includes: A detrending fluctuation analysis algorithm is used for each subsequence in the current signal sequence of each line to obtain a subsequence without trend characteristics; The discrete degree of the subsequence without trend feature is used as the current mutation degree of each subsequence in the current signal sequence of each line.

5. A solder joint detection method for a highly integrated circuit board as claimed in claim 3, characterized in that: The step of determining the harmonic influence of each subsequence in the current signal sequence of each line includes: A sliding window iteration algorithm is used for each subsequence in the current signal sequence of each line to obtain the fundamental wave subsequence of each subsequence; The harmonic influence degree of each subsequence in the current signal sequence of each line is determined according to the difference degree between the fundamental wave subsequence and the corresponding subsequence of each subsequence in the current signal sequence of each line.

6. A solder joint detection method for a highly integrated circuit board as claimed in claim 1, characterized in that: The determining of the distribution consistency of each subsequence in the current signal sequence of each line includes: Analyze the symmetry of periodic changes between each subsequence and adjacent subsequences in the current signal sequence of each line, and determine the waveform symmetry of each subsequence in the current signal sequence of each line; Analyze the fluctuation similarity between each subsequence in the current signal sequence of each line and the adjacent subsequence in the same cluster to which it belongs, and determine the waveform similarity of each subsequence in the current signal sequence of each line in combination with the interference influence coefficient; The ratio of the waveform similarity to the waveform symmetry is used as the distribution consistency of each subsequence in the current signal sequence of each line.

7. A solder joint detection method for a highly integrated circuit board as claimed in claim 6, characterized in that: The step of determining the waveform symmetry of each subsequence in the current signal sequence of each line includes: Calculate the skewness of the periodic sequence formed by each subsequence and the previous subsequence in the current signal sequence of each line, and record it as the first skewness; Calculate the skewness of the periodic sequence formed by each subsequence and the next subsequence in the current signal sequence of each line, and record it as the second skewness; The average of the first skewness and the second skewness is used as the waveform symmetry of each subsequence in the current signal sequence of each line.

8. A solder joint detection method for a highly integrated circuit board as claimed in claim 6, characterized in that: The step of determining the waveform similarity of each subsequence in the current signal sequence of each line includes: in is the waveform similarity of the i-th subsequence in the current signal sequence of the k-th line, is the i-th subsequence in the current signal sequence of the k-th line, is the i-2th subsequence in the current signal sequence of the kth line, is the i+2th subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the ith subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the i-2th subsequence in the current signal sequence of the kth line, is the interference influence coefficient of the i+2th subsequence in the current signal sequence of the kth line, and R() represents the calculated correlation coefficient.

9. A solder joint detection method for a highly integrated circuit board as claimed in claim 1, characterized in that: Determining the electromagnetic impact index of each line includes: The distribution consistency of all subsequences in the current signal sequence of each line is used to form a current distribution sequence of each line; The mean value of the difference between the current distribution sequence of each line and the other lines is calculated, and the mean value is integrated with the discrete degree of the current distribution sequence of each line to determine the electromagnetic influence index of each line.

10. A solder joint detection method for a highly integrated circuit board as claimed in claim 1, characterized in that: The detection of the solder joints of the circuit board includes: normalizing the electromagnetic influence index of each circuit. If the normalization result is greater than or equal to a preset abnormal threshold, the solder joints at both ends of the circuit are defective. Otherwise, the solder joints at both ends of the circuit are not defective.

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