A high-precision multi-layer display board line conductivity testing system and method

Abstract

The present invention relates to the technical field of electronic circuit testing, and particularly relates to a high-precision multi-layer display board line conductivity testing system and method. This method obtains the via quality coefficient through the similarity between vias, the stability and symmetry of the current density curve of vias. By the phase similarity, periodicity, and data change characteristics between the near-end crosstalk signals on the transmission line, and further combining the variation regularity of the far-end crosstalk signals under frequency variation, the transmission quality coefficient of the transmission line is obtained. The data is statistically integrated to obtain the conduction quality coefficient of the multi-layer display board for the evaluation of conductivity. The present invention utilizes the characteristics of vias and transmission lines during the current transmission process, analyzes the changes and laws of signals, and accurately quantifies the conduction quality of the multi-layer display board.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuit testing, and particularly to a high-precision multi-layer display board line conductivity testing system and method. Background Art

[0002] With the rapid development of electronic technology, multi-layer display boards are increasingly widely used in fields such as consumer electronics, communication equipment, and medical instruments. These complex circuit boards not only carry the task of high-speed signal transmission but also integrate a large number of tiny components and high-density wiring. Ensuring the reliable conductivity of their internal lines is crucial for the integrity of signal transmission and maintaining the stable operation of the system. Traditional conductivity detection methods such as flying probe testing and bed-of-nails testing have been widely used in the industry.

[0003] For the traditional conductivity detection process, it mainly focuses on the instantaneous changes of electrical data and does not analyze the change trends of data at different positions, resulting in incomplete test results. For example, when flying probe testing and bed-of-nails testing face fine-pitch components, due to the mutual interference between components, the data changes. Evaluating conductivity only using the data in the instantaneous state is likely to result in misjudgments. Summary of the Invention

[0004] In order to solve the technical problem that in the existing technology, during the conductivity testing process of multi-layer display boards, the change trends of electrical data are not analyzed, resulting in misjudgments in the final conductivity detection results, the purpose of the present invention is to provide a high-precision multi-layer display board line conductivity testing system and method, and the specific technical solutions adopted are as follows:

[0005] The present invention proposes a high-precision multi-layer display board line conductivity testing method, and the method includes:

[0006] Obtaining the current density curve of each via hole on the multi-layer display board; the current density curve is composed of the current densities at different positions on a straight line passing through the center of the via hole; obtaining the via hole temperature of each via hole;

[0007] For each via hole, according to the via hole temperature similarity and current density curve similarity between the via hole and other via holes, obtaining the conduction stability of the via hole; obtaining the current density stability of the current density curve of the via hole; on the current density curve of the via hole, taking the minimum value as the segmentation point, obtaining the data symmetry of the two segments at the segmentation point; according to the conduction stability, current density stability, and data symmetry, obtaining the via hole quality coefficient of each via hole;

[0008] Take any transmission line on the multi-layer display board as a noise source, take the ports of other transmission lines on the same side of one end of the noise source as near-end crosstalk receivers, and take the ports of other transmission lines on the same side of the other end as far-end crosstalk receivers; obtain the near-end crosstalk signals of each near-end crosstalk receiver and the far-end crosstalk signals of each far-end crosstalk receiver;

[0009] For each transmission line other than the noise source, obtain the transmission quality coefficient of the transmission line according to the phase similarity of the near-end crosstalk signal and other near-end crosstalk signals, the periodicity of the near-end crosstalk signal, the data change characteristics of the near-end crosstalk signal, and the change regularity of the far-end crosstalk signal in the frequency dimension;

[0010] Obtain the conduction quality coefficient of the multi-layer display board according to the via quality coefficient of the vias on the multi-layer display board and the transmission quality coefficient of the transmission line; evaluate the conductivity of the multi-layer display board according to the conduction quality coefficient.

[0011] Further, the method for obtaining the conduction stability includes:

[0012] Perform a negative correlation mapping on the via temperature difference between the via and other vias to obtain temperature similarity; multiply the cosine similarity of the current density curves between the via and other vias by the temperature similarity to obtain the feature similarity between the via and other vias; take the average feature similarity between the via and all other vias as the conduction stability.

[0013] Further, the method for obtaining the current density stability includes:

[0014] The sequence corresponding to each data point on the current density curve is the current density sequence, obtain the first difference sequence of the current density sequence, and perform a negative correlation mapping on the average value of the absolute values of the elements in the first difference sequence to obtain the current density stability.

[0015] Further, the method for obtaining the data symmetry includes:

[0016] The segmentation point divides the current density curve into two sub-curves, obtain the determination coefficient in the fitting process of each sub-curve, and perform a negative correlation mapping on the absolute value of the difference between the determination coefficients between the two sub-curves to obtain the data symmetry.

[0017] Further, the method for obtaining the periodicity includes:

[0018] Arrange the phases of each frequency on the near-end crosstalk signal according to the frequency magnitude to obtain a phase sequence; obtain the sample entropy according to the phase sequence, and perform a negative correlation mapping on the sample entropy to obtain the periodicity.

[0019] Further, the method for obtaining the data change feature includes:

[0020] Obtain the average amplitude and coefficient of variation of the near-end crosstalk signal, and use the product of the average amplitude and the coefficient of variation as the data change feature.

[0021] Further, the method for obtaining the change regularity includes:

[0022] For the far-end crosstalk signal, arrange the amplitudes of the far-end crosstalk signal according to the frequency magnitude to obtain a far-end amplitude sequence; obtain the smoothed signal of the far-end amplitude sequence, obtain the second difference sequence of the smoothed signal, and use the ratio of the number of positive numbers to the number of negative numbers in the second difference sequence as the change regularity.

[0023] Further, the method for obtaining the phase similarity includes:

[0024] Take the average of the cosine similarities of the phase sequences between the near-end crosstalk signal and all other near-end crosstalk signals as the phase similarity.

[0025] Further, the method for obtaining the conduction quality coefficient includes:

[0026] Obtain the average via quality coefficient of all vias on the multi-layer display board, obtain the average transmission quality coefficient of all transmission lines, and use the sum of the average via quality coefficient and the average transmission quality coefficient as the conduction quality coefficient.

[0027] The present invention also provides a high-precision multi-layer display board line conduction test system, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of any one of the high-precision multi-layer display board line conduction test methods.

[0028] The present invention has the following beneficial effects:

[0029] The present invention first takes into account that there are two components for transmission, namely transmission lines and vias, on a multi-layer display board. Therefore, the two components are analyzed separately. For vias, considering that when current passes through a via for transmission, due to the skin effect, the current density will show a special change. The poorer the conductivity of the via, the more uneven the distribution of the current density at different positions on the via, and the temperature of the via will also become abnormal. Therefore, the obtained via quality coefficient can be used to accurately evaluate the transmission quality of each via during the transmission of current. For transmission lines, first, the near-end crosstalk receiver and the far-end crosstalk receiver are determined according to the positions of the transmission line ports. For the near-end crosstalk receiver, it is closer to the signal injection port of the interference source, and the coupling effect is stronger. Therefore, the higher the transmission quality, the more stable the corresponding near-end crosstalk signal, and the amplitude of the corresponding far-end crosstalk signal will also show a fixed trend as the frequency changes. Therefore, the transmission quality coefficient is used to quantify the transmission quality on the transmission line. Combining the quality coefficients corresponding to vias and transmission lines, the conduction quality coefficient of the multi-layer display board can be obtained and the conductivity can be evaluated. The present invention utilizes the characteristics of vias and transmission lines during the current transmission process, analyzes the changes and laws of signals, and accurately quantifies the conduction quality of the multi-layer display board. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a flowchart of a method for testing the line conductivity of a high-precision multi-layer display board provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation manners, structures, features, and effects of a high-precision multi-layer display board line conductivity testing system and method proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0034] The embodiments of the present invention are directed to the optimization and improvement of the conduction detection process of high-precision multi-layer display boards. First, through the design files of the multi-layer display boards, design parameters such as the board length and width, dielectric constant, loss tangent, via radius, anti-pad radius, dielectric thickness, and metal thickness of the multi-layer display boards are obtained. These design parameters can be used in subsequent processes such as simulation.

[0035] The following specifically describes the specific solutions of a high-precision multi-layer display board line conduction test system and method provided by the present invention in conjunction with the accompanying drawings.

[0036] Please refer to Figure 1 , which shows a flowchart of a method for testing the line conduction of a high-precision multi-layer display board provided by an embodiment of the present invention. The method includes:

[0037] Step S1: Obtain the current density curve of each via on the multi-layer display board; the current density curve is composed of the current densities at different positions on the via; obtain the via temperature of each via.

[0038] When the multi-layer display board is working, the current is transmitted through the transmission lines on the multi-layer board and needs to be transmitted through vias between different layers. Therefore, the embodiments of the present invention analyze the transmission quality of vias and the transmission quality of transmission lines separately. For vias, when the current enters or leaves the via from the plane, it will first concentrate at the via opening. Due to the skin effect, the current tends to flow along the shortest path, resulting in regular changes in the current density on the via. And during the current transmission process of the via, due to the concentrated current density at the via opening, heat will be generated, causing the via to exhibit certain temperature characteristics. Therefore, in order to analyze the transmission quality of the via, it is necessary to obtain the current density information and via temperature information at different positions on the via. And the current density curve is composed of the current densities at different positions on a straight line passing through the center of the via. By defining the composition order of the current density curve, it is convenient to extract features such as its symmetry in subsequent steps.

[0039] In the embodiments of the present invention, considering that the vias are relatively small on the multi-layer display board, and the aperture diameter is usually between 0.15 mm and 0.6 mm, it is difficult to directly obtain the current density at different positions through sensors. Therefore, in the embodiments of the present invention, the HFSS simulation method is adopted to perform simulation using the design parameters of the multi-layer display board, and an electric energy meter can be used to obtain the amount of power transmission per unit time at the power supply end of the circuit board during this test process. Taking the design parameters and the amount of power transmission as inputs, where the amount of power transmission is used as the excitation source for the simulation, the current density information on the surface and inside of the multi-layer display board can be obtained by using the HFSS simulation method. Then, based on the built-in calculator in the simulation process, the current density at each position of each via can be obtained. By arranging them in a fixed position sequence, the current density sequence of each via can be obtained. Using the least squares method to fit the current density sequence, the current density curve can be obtained.

[0040] It should be noted that methods such as the HFSS simulation method and the least squares method are all well-known technical means to those skilled in the art and will not be elaborated here.

[0041] In the embodiments of the present invention, the via temperature of the via is determined by using the thermal imaging image. A thermal imager can be used to obtain the thermal imaging image of the multi-layer display board, and then several easily recognizable feature points, such as solder pads, component pins, etc., are marked on the multi-layer display board based on the design parameters. Based on the feature points, the thermal imaging image can be aligned with the PCB design file of the multi-layer display board. After ensuring that the spatial coordinates are consistent, the via temperature at each via position can be determined in the thermal imaging image.

[0042] Step S2: For each via, obtain the conduction stability of the via according to the via temperature similarity and current density curve similarity between the via and other vias; obtain the current density stability of the current density curve of the via; on the current density curve of the via, take the minimum value as the segmentation point to obtain the data symmetry of the two segments at the segmentation point; according to the conduction stability, current density stability, and data symmetry, obtain the via quality coefficient of each via.

[0043] During the process of current transmission at the via, as the current conducts downward along the via wall, the current density gradually decreases, resulting in the minimum current density at the center of the via. At the same time, the magnetic fields generated by adjacent transmission lines interact with each other, causing the current to concentrate on the outer side of the wire, resulting in a more concentrated current at the orifice of the via and a relatively smaller current density at the center of the via. Therefore, under normal circumstances, if the conductivity of a via is good, the current density from one side of the via to the other side shows a shape similar to a quadratic function with a decrease first and then an increase, that is, a certain axisymmetric situation. If there is an abnormality in the conductivity of the via, and the abnormality is caused by factors such as abnormal plating on the via wall that affect the resistance properties of the via, the symmetric distribution of the current density will be broken when the current passes through the via. Therefore, in the embodiments of the present invention, for the current density curve of the via, taking the minimum value as the segmentation point, the data symmetry of the two segments at the segmentation point is obtained. That is, the greater the data symmetry, the better the transmission quality of the via.

[0044] Furthermore, considering that the change in conductivity has the characteristic of locality, that is, a problem in conductivity at one position only affects the vias or transmission lines under that local position. Therefore, under normal circumstances, the information such as the current density distribution of each via has obvious similarity. Therefore, in the embodiments of the present invention, the conduction stability of the via can be obtained according to the similarity of the via temperature and the similarity of the current density curve between the via and other vias with holes. That is, the similarity is analyzed from the data in two dimensions. The greater the similarity, the more likely the via is a normally conducting via, and the greater the conduction stability.

[0045] If the via is in a normal conducting state, the current density curve shows a relatively smooth change and there will be no large data fluctuations. Therefore, the current density stability of the current density curve is further obtained.

[0046] For each via, the via quality coefficient of each via can be obtained according to its conduction stability, current density stability, and data symmetry. That is, the greater these three characteristics are, the greater the via quality coefficient of the via.

[0047] In an embodiment of the present invention, after quantifying the conduction stability, current density stability, and data symmetry respectively, the result of multiplying the three is normalized to obtain the via quality coefficient. The normalization operation can be implemented by basic mathematical means such as linear normalization and function mapping method, which are not limited and elaborated here.

[0048] Preferably, in an embodiment of the present invention, the method for obtaining the conduction stability includes:

[0049] Negatively correlate the via hole temperature difference between a via hole and other via holes to obtain temperature similarity. Multiply the cosine similarity of the current density curves between the via hole and other via holes by the temperature similarity to obtain the feature similarity between the via hole and other via holes. That is, the greater the feature similarity, the more similar the conduction characteristics between this via hole and that other via hole. Since there are multiple other via holes, the average feature similarity between the via hole and all other via holes is used as the conduction stability.

[0050] In an embodiment of the present invention, if the negative correlation mapping method of the via hole temperature difference adopts the reciprocal form, the formula for the conduction stability can be expressed as:

[0051] ; where is the conduction stability of the th via hole, is the number of other via holes on the multi-layer display board except the th via hole, is the absolute value of the difference in the via hole temperature between the th via hole and the th other via hole, is the cosine similarity of the current density curves between the th via hole and the th other via hole. The purpose of adding the positive integer 1 to the denominator is to prevent the denominator from being 0.

[0052] Preferably, in an embodiment of the present invention, the method for obtaining the current density stability includes:

[0053] The sequence corresponding to each data point on the current density curve is the current density sequence. Obtain the first difference sequence of the current density sequence, and negatively correlate the average value of the absolute values of the elements in the first difference sequence to obtain the current density stability. In the embodiment of the present invention, the difference sequence is the latter element of the original sequence minus the former element. Therefore, the elements on the difference sequence represent the degree of data change at a certain position, the value represents the degree of change, and the positive and negative signs represent the change direction. Therefore, the greater the average value of the absolute values of the elements in the first difference sequence, the greater the change amplitude of the current density sequence and the more unstable the data. Therefore, negatively correlate it to obtain the current density stability.

[0054] In other embodiments of the present invention, the variance of the data in the current density sequence can also be directly negatively correlated to obtain the current density stability.

[0055] It should be noted that the negative correlation mapping in the embodiments of the present invention can all adopt the same mapping method. For example, the reciprocal form is adopted for the negative correlation mapping of the via hole temperature difference, and the negative correlation mapping methods of other technical features will not be elaborated specifically.

[0056] Preferably, in an embodiment of the present invention, the method for obtaining data symmetry includes:

[0057] The segmentation point divides the current density curve into two sub-curves, and the coefficient of determination in the fitting process of each sub-curve is obtained. The absolute value of the difference between the coefficients of determination between the two sub-curves is negatively correlated and mapped to obtain data symmetry. It should be noted that the coefficient of determination is an index obtained during the curve fitting process of the data, which represents the fitting degree of the curve. It is a well-known technical means for those skilled in the art, and the specific acquisition method will not be elaborated here. That is, the absolute value of the difference in the coefficient of determination characterizes the difference in the fitting degree of the sub-curves on both sides of the minimum point. If the current density distribution of the via shows axial symmetry, the difference in the fitting degree between the two sub-curves is small, and the data symmetry is large.

[0058] Step S3: Take any transmission line on the multi-layer display board as the interference source, take the ports of other transmission lines on the same side of one end of the interference source as the near-end crosstalk receivers, and take the ports of other transmission lines on the same side of the other end as the far-end crosstalk receivers; obtain the near-end crosstalk signals of each near-end crosstalk receiver and the far-end crosstalk signals of each far-end crosstalk receiver.

[0059] The multi-layer display board contains multiple transmission lines. Any transmission line can be used as the interference source. The purpose of the interference source is to define the direction of the port. One end of the interference source can be regarded as the signal injection point, then the ports of other transmission lines on the same side as the signal injection point are the near-end crosstalk receivers, and the other side is the far-end crosstalk receivers. By using a network analyzer to obtain the signals of each port, the near-end crosstalk signals and the far-end crosstalk signals can be obtained. The integrity of the signals in the transmission line can be measured by the change trends of the near-end crosstalk signals and the far-end crosstalk signals.

[0060] Step S4: For each transmission line except the interference source, obtain the transmission quality coefficient of the transmission line according to the phase similarity between the near-end crosstalk signal and other near-end crosstalk signals, the periodicity of the near-end crosstalk signal, the data change characteristics of the near-end crosstalk signal, and the change regularity of the far-end crosstalk signal in the frequency dimension.

[0061] Under normal circumstances, the near-end crosstalk receivers are relatively close to the signal injection point of the interference source, and the coupling effect is strong. Therefore, the amplitude of the near-end crosstalk signal is relatively small and there is no complex fluctuation; and the distance between the near-end receivers is also relatively close, so the phases of the near-end crosstalk signals between different near-end receivers are significantly similar, and as the frequency changes, the overall trend of the phase of the near-end crosstalk signal is relatively stable, showing an obvious periodic change. The far-end crosstalk signal can be regarded as generated during the transmission of the near-end crosstalk signal. As the frequency increases, the amplitude of the far-end crosstalk signal will show a related increasing trend.

[0062] When the conductivity of the transmission line is poor, it will lead to an increase in the local current density, resulting in a significant high-amplitude of the near-end crosstalk signal, causing signal fluctuations; and the change in local impedance will lead to a stronger randomness in the phase change of the near-end crosstalk, resulting in a weakening of the above periodicity; at the same time, the far-end crosstalk signal will become more complex in a follow-up manner, and the amplitude increase and attenuation no longer follow the original rules, and no longer conform to the monotonic change that the larger the frequency, the larger the amplitude.

[0063] Therefore, in the embodiments of the present invention, for each transmission line except the interference source, according to the phase similarity between the near-end crosstalk signal and other near-end crosstalk signals, the periodicity of the near-end crosstalk signal, the data change characteristics of the near-end crosstalk signal, and the change regularity of the far-end crosstalk signal in the frequency dimension, the transmission quality coefficient of the transmission line is obtained. That is, the greater the phase similarity, the more obvious the periodicity, the weaker the data change characteristics, and the stronger the change regularity, the higher the transmission quality coefficient of the transmission line. In an embodiment of the present invention, after quantifying these technical features respectively, multiply the phase similarity, periodicity, and change regularity, and then divide by the data change characteristics to obtain the transmission quality coefficient.

[0064] Preferably, in an embodiment of the present invention, the method for obtaining the periodicity includes:

[0065] Arrange the phases of each frequency on the near-end crosstalk signal in ascending order of frequency to obtain a phase sequence; obtain the sample entropy according to the phase sequence, and perform a negative correlation mapping on the sample entropy to obtain the periodicity. It should be noted that the method for obtaining the sample entropy is a well-known technical means for those skilled in the art. The sample entropy can be obtained by combining the phase sequence with the existing sample entropy obtaining method by presetting the embedding dimension and tolerance threshold. In the embodiments of the present invention, the embedding dimension is set to 10, and the tolerance threshold is set to 0.15 times the standard deviation of the phase sequence.

[0066] Preferably, in an embodiment of the present invention, the method for obtaining the data change characteristics includes:

[0067] Obtain the average amplitude and coefficient of variation of the near-end crosstalk signal, and take the product of the average amplitude and the coefficient of variation as the data change characteristics. The coefficient of variation characterizes the volatility of the data. The larger the coefficient of variation and the larger the average amplitude at the same time, it indicates that the signal fluctuation is more intense at this time, and the greater the probability of violent fluctuation, the larger the data change characteristics and the stronger the data change. The method for obtaining the coefficient of variation is a well-known technical means for those skilled in the art and will not be elaborated here.

[0068] Preferably, in an embodiment of the present invention, the method for obtaining the change regularity includes:

[0069] For the far-end crosstalk signal, arrange the amplitudes of the far-end crosstalk signal according to the frequency magnitude to obtain the far-end amplitude sequence. Obtain the smoothed signal of the far-end amplitude sequence. The purpose of obtaining the smoothed signal is to avoid the influence of local fine fluctuations in the far-end amplitude sequence on the overall change trend. Therefore, those skilled in the art use the moving average method to smooth it, with the window size set to 5, and the smoothed signal of the far-end amplitude sequence can be obtained using the prior art. Further obtain the second difference sequence of the smoothed signal. Similar to the first difference sequence, the positive or negative sign of the elements in the second difference sequence represents the change direction. If the far-end crosstalk signal conforms to the signal distribution under normal conditions, the smoothed signal should be an obviously regular increasing signal, and the number of positive elements in the second difference sequence should be significantly greater than the number of negative elements. Therefore, take the ratio of the number of positive numbers to the number of negative numbers in the second difference sequence as the change regularity. That is, the larger the ratio, the more it conforms to the transmission under normal conditions, and the greater the change regularity.

[0070] Preferably, in an embodiment of the present invention, the method for obtaining the phase similarity includes:

[0071] Take the average value of the cosine similarities of the phase sequences between the near-end crosstalk signal and all other near-end crosstalk signals as the phase similarity. It should be noted that since the value range of the cosine similarity is from -1 to 1, in order to avoid the influence of low similarity data values on the value of the final transmission quality coefficient, after obtaining the average value of the cosine similarities in the embodiment of the present invention, use it as the power of the exponential function with the natural constant as the base, and the output result of the exponential function is used as the phase similarity, that is, adjust the numerical range of the final result through the exponential function.

[0072] Step S5: Obtain the conduction quality coefficient of the multilayer display board according to the via quality coefficient of the vias on the multilayer display board and the transmission quality coefficient of the transmission line; evaluate the conductivity of the multilayer display board according to the conduction quality coefficient.

[0073] So far, the via quality coefficient of each via on the multilayer display board and the transmission quality coefficient of each transmission line have been obtained. Further statistical analysis can obtain the conduction quality coefficient of the multilayer display board. The larger the conduction quality coefficient, the better the conduction quality and the stronger the conductivity of the current multilayer display board.

[0074] In some embodiments of the present invention, by setting a threshold value, compare the conduction quality coefficient of the multilayer display board with the preset threshold value. If it is greater than the threshold value, it means that the conductivity of the multilayer display board meets the requirements.

[0075] In an embodiment of the present invention, considering that the conductivity test usually does not only test one multi-layer display board, but samples and detects a batch of multi-layer display boards, that is, there are multiple samples for the conductivity test. Therefore, in the embodiment of the present invention, clustering is performed on the multi-layer display boards based on the conductivity quality coefficient of the multi-layer display boards. The embodiment of the present invention uses the k-means clustering algorithm and sets the number of clustering clusters to 3. Among the three finally obtained clustering clusters, the clustering cluster with the smallest average conductivity quality coefficient is unqualified, the largest is good in conductivity, and the other is ordinary in conductivity, so as to realize the conductivity statistics of an entire batch of multi-layer display boards.

[0076] Preferably, in an embodiment of the present invention, the method for obtaining the conductivity quality coefficient includes:

[0077] Obtain the average via quality coefficient of all vias on the multi-layer display board, obtain the average transmission quality coefficient of all transmission lines, and use the sum value of the average via quality coefficient and the average transmission quality coefficient as the conductivity quality coefficient. It should be noted that in the embodiment of the present invention, in order to facilitate the judgment of conductivity by the conductivity quality coefficient, the data can be further normalized, and the normalization method is selected as range normalization.

[0078] In summary, in the embodiment of the present invention, the via quality coefficient is obtained through the similarity between vias, the stability and symmetry of the current density curve of the vias. The transmission quality coefficient of the transmission line is obtained through the phase similarity, periodicity, and data change characteristics between the near-end crosstalk signals on the transmission line, and further combined with the change regularity of the far-end crosstalk signals under frequency change. The data is statistically integrated to obtain the conductivity quality coefficient of the multi-layer display board for the evaluation of conductivity. The embodiment of the present invention uses the characteristics of vias and transmission lines in the process of current transmission, analyzes the changes and laws of signals, and accurately quantifies the conductivity quality of multi-layer display boards.

[0079] Based on the same inventive concept, the present invention also proposes a high-precision multi-layer display board line conductivity test system, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of any one of the high-precision multi-layer display board line conductivity test methods.

[0080] It should be noted that: the above-mentioned sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0081] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the differences between each embodiment and other embodiments are emphasized respectively.

Claims

1. A method for testing the circuit conductivity of a high-precision multi-layer display panel, characterized in that: The method comprises: Obtaining a current density curve of each guide hole in a multi-layer display panel; the current density curve is composed of current densities at different positions on a straight line passing through the center of the guide hole; obtaining a guide hole temperature of each guide hole; For each guide hole, the conduction stability of the guide hole is obtained according to the guide hole temperature similarity and the current density curve similarity between the guide hole and other guide holes; the current density stability of the current density curve of the guide hole is obtained; on the current density curve of the guide hole, the minimum value is used as the dividing point, and the data symmetry of the two segments of the dividing point is obtained; according to the conduction stability, the current density stability and the data symmetry, the guide hole quality coefficient of each guide hole is obtained; Any transmission line on the multi-layer display panel is used as an interference source, other transmission line ports on the same side of one end of the interference source are used as near-end crosstalk receiving ends, and other transmission line ports on the same side of the other end are used as far-end crosstalk receiving ends; a near-end crosstalk signal of each near-end crosstalk receiving end and a far-end crosstalk signal of each far-end crosstalk receiving end are obtained; For each transmission line except the interference source, the transmission quality coefficient of the transmission line is obtained according to the phase similarity between the near-end crosstalk signal and other near-end crosstalk signals, the periodicity of the near-end crosstalk signal, the data change characteristics of the near-end crosstalk signal, and the change regularity of the far-end crosstalk signal in the frequency dimension; The conduction quality coefficient of the multilayer display panel is obtained according to the guide hole quality coefficient of the guide hole on the multilayer display panel and the transmission quality coefficient of the transmission line; and the conductivity of the multilayer display panel is evaluated according to the conduction quality coefficient.

2. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The method for obtaining the conduction stability includes: A negative correlation mapping is performed on the guide hole temperature difference between the guide hole and the other guide holes to obtain temperature similarity; a cosine similarity of the current density curve between the guide hole and the other guide holes is multiplied by the temperature similarity to obtain a feature similarity between the guide hole and the other guide holes; and an average feature similarity between the guide hole and all other guide holes is used as the conduction stability.

3. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The method for obtaining the current density stability comprises: The sequence corresponding to each data point on the current density curve is the current density sequence, a first differential sequence of the current density sequence is obtained, and the average value of the absolute values ​​of the elements in the first differential sequence is negatively correlated to obtain the current density stability.

4. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The method for obtaining data symmetry includes: The segmentation point divides the current density curve into two sub-curves, obtains the determination coefficient in the fitting process of each sub-curve, and negatively correlates the absolute value of the difference of the determination coefficient between the two sub-curves to obtain the data symmetry.

5. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The periodic acquisition method includes: The phases of the frequencies on the near-end crosstalk signal are arranged according to the frequency magnitude to obtain a phase sequence; sample entropy is obtained according to the phase sequence, and the sample entropy is negatively correlated mapped to obtain the periodicity.

6. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The method for acquiring the data change feature includes: An average amplitude and a coefficient of variation of the near-end crosstalk signal are obtained, and a product of the average amplitude and the coefficient of variation is used as the data change feature.

7. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The method for obtaining the change regularity includes: For the far-end crosstalk signal, the amplitude of the far-end crosstalk signal is arranged according to the frequency to obtain a far-end amplitude sequence; a smoothed signal of the far-end amplitude sequence is obtained, a second differential sequence of the smoothed signal is obtained, and the ratio of the number of positive numbers to the number of negative numbers in the second differential sequence is used as the change regularity.

8. A high-precision multi-layer display panel circuit conductivity testing method according to claim 5, characterized in that: The method for obtaining the phase similarity comprises: The phase similarity is taken as an average value of cosine similarities of phase sequences between the near-end crosstalk signal and all other near-end crosstalk signals.

9. A high-precision multi-layer display panel circuit conductivity testing method according to claim 1, characterized in that: The method for obtaining the conduction quality coefficient includes: The average guide hole quality coefficient of all guide holes on the multilayer display panel is obtained, the average transmission quality coefficient of all transmission lines is obtained, and the sum of the average guide hole quality coefficient and the average transmission quality coefficient is used as the conduction quality coefficient.

10. A high-precision multi-layer display panel circuit conductivity test system, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of a high-precision multi-layer display panel circuit conductivity testing method as described in any one of claims 1 to 9 are implemented.

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