Multilayer wiring board drilling defect automatic detection method and system

Abstract

The application discloses a multilayer circuit board drilling defect automatic detection method and system, relates to the field of circuit board detection, and solves the problem that the drilling defect of the multilayer circuit board cannot be accurately judged. The method is as follows: collecting the outer surface image of the multilayer circuit board, pre-processing the outer surface image, and obtaining the edge contour graph of the first circuit board and the Nth circuit board; analyzing the edge contour of the first circuit board and the Nth circuit board, obtaining the expression and direction vector of the corresponding drilling straight line equation; measuring the second circuit board to the N-1th circuit board in the multilayer circuit board, obtaining the corresponding X-ray image and ultrasonic wave model, analyzing the X-ray image and the ultrasonic wave model of the multilayer circuit board, and obtaining the drilling offset level of the drilling hole corresponding to any circuit board; receiving the abnormal signal or the drilling offset level corresponding to the multilayer circuit board, reading the abnormal signal or the drilling offset level, and knowing the drilling defect condition of the multilayer circuit board. The application realizes accurate judgment of the drilling defect of the multilayer circuit board.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of circuit board detection, and particularly relates to a multilayer circuit board drilling defect automatic detection method and system. BACKGROUND

[0002] A circuit board, also known as a printed circuit board, is an important electronic component, is a support body of electronic components, and is also a carrier for electrical connection of electronic components. A multilayer circuit board is formed by stacking at least three copper foil layers and two insulating layers, and a connection between the layers is formed through a via plating process. The structure of the multilayer circuit board is usually composed of 3 to 16 or even more copper foil layers stacked together and contains vias for completing the connection. Each copper foil layer has its own circuit pattern, and the circuit patterns are connected to each other through conductive holes. In order to avoid mispositioning of blind holes, the inner wall of the hole is often coated with conductive metal, which increases the complexity of the process.

[0003] However, at the present stage, when the drilling of the multilayer circuit board is monitored, the detection precision is low, and the traditional method cannot determine the defect conditions of the internal drilling of the multilayer circuit board, such as the offset condition and the size of the internal drilling, so that the quality of the corresponding multilayer circuit board cannot be accurately known.

[0004] Therefore, the application provides a multilayer circuit board drilling defect automatic detection method and system. SUMMARY

[0005] The application aims to provide a multilayer circuit board drilling defect automatic detection method and system to solve the problems in the background.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] The multilayer circuit board drilling defect automatic detection method comprises the following steps:

[0008] Step S1, an outer surface image of the multilayer circuit board is collected, and then the outer surface image is preprocessed to obtain edge contour maps of a first circuit board and an Nth circuit board;

[0009] Step S2, the edge contours of the first circuit board and the Nth circuit board are analyzed to obtain an expression of a straight line equation corresponding to the drilling and a direction vector;

[0010] Step S3, the second circuit board to the N-1th circuit board in the multilayer circuit board are measured to obtain corresponding X-ray images and ultrasonic wave models;

[0011] Step S4, the X-ray images and the ultrasonic wave models of the multilayer circuit board are analyzed to obtain a drilling offset level of the drilling corresponding to any circuit board;

[0012] Step S5, receiving the abnormal signal or the drilling deviation level corresponding to the multilayer circuit board, reading the abnormal signal or the drilling deviation level to know the drilling defect condition of the multilayer circuit board.

[0013] Further, the step S1 comprises the following sub-steps:

[0014] Step S11, sequentially dividing the multilayer circuit board into a first circuit board to an Nth circuit board, wherein N is the number of layers of the circuit board;

[0015] Step S12, adjusting the multilayer circuit board to the first circuit board facing upward and being placed in the camera shooting range, and shooting the outer surface image of the first circuit board through the camera;

[0016] Step S13, adjusting the multilayer circuit board to the Nth circuit board facing upward and being placed in the camera shooting range, and then shooting the outer surface image of the Nth circuit board through the camera;

[0017] Step S14, analyzing the outer surface image of the first circuit board to obtain the edge contour of the first circuit board;

[0018] Step S15, similarly, extracting the edge contour of the Nth circuit board.

[0019] Further, the step S14 comprises the following sub-steps:

[0020] Step S141, obtaining the outer surface image of the first circuit board, extracting the pixel value of a plurality of pixel points in the first circuit board, and obtaining the R value component RZx, the G value component GZx and the B value component BZx of each pixel point; wherein x is the number of the pixel point, x=1, 2, …, z, and z is a positive integer;

[0021] Step S142, calculating the gray value HDx of each pixel point in the first circuit board by the formula, and the formula is as follows:

[0022] HDx= (A1×RZx+A2×GZx+A3×BZx) / 3; wherein A1, A2 and A3 are proportional coefficients of fixed values, A1

[0023] Step S143, obtaining the Gaussian gray value GHDx of the corresponding pixel point by the Gaussian filtering function of the gray value of the pixel point, and the Gaussian filtering function is specifically:

[0024] ; wherein σ is a constant, and exp is the power function with e as the base.

[0025] Further, the step S14 further comprises:

[0026] Step S144, any pixel point is recorded as a selected pixel point, a pixel point adjacent to the selected pixel point is recorded as an adjacent pixel point, and a difference value between the adjacent pixel point and the selected pixel point is recorded as a gray value difference value;

[0027] Step S145, the gray value difference value of the selected pixel point is compared with a gray value difference value threshold value, if any gray value difference value corresponding to the selected pixel point is greater than or equal to the gray value difference value threshold value, the selected pixel point is recorded as an edge pixel point, if all the gray value difference values corresponding to the selected pixel point are less than the gray value difference value threshold value, no operation is performed;

[0028] Step S146, adjacent edge pixel points are connected to obtain an edge contour of the first circuit board.

[0029] Further, the step S2 comprises the following sub-steps:

[0030] Step S21, an edge contour of the first circuit board and an edge contour of the Nth circuit board are obtained;

[0031] Step S22, the edge contour of the first circuit board and the edge contour of the Nth circuit board are matched with a drilling schematic diagram, if the matching is successful, the successfully matched edge contour is recorded as a drilling contour, if the matching fails, it is determined that the circuit board has a drilling defect, and an abnormal signal is generated;

[0032] Step S23, any two mutually perpendicular straight lines in a plane where the Nth circuit board is located are taken as an X axis and a Y axis, a straight line perpendicular to the plane where the Nth circuit board is located is taken as a Z axis, and a space rectangular coordinate system is constructed;

[0033] Step S24, a first center coordinate of the drilling contour corresponding to the first circuit board is recorded as (X1, Y1, Z1), and an Nth center coordinate of the drilling contour corresponding to the Nth circuit board is recorded as (X2, Y2, 0).

[0034] Further, the step S2 further comprises the following sub-steps:

[0035] Step S25, an offset distance PY between the projection of the first center coordinate and the Nth center coordinate is calculated by a formula, and the formula is as follows:

[0036] ;

[0037] Step S26, the offset distance is compared with an offset distance threshold value, if the offset distance is greater than or equal to the offset distance threshold value, it is determined that the circuit board has a drilling defect, and an abnormal signal is generated, if the offset distance is less than the offset distance threshold value, a drilling straight line equation expression of the corresponding drilling hole is obtained, and the drilling straight line equation expression is specifically as follows:

[0038] Step S27, further, the direction vector XL= (X2-X1, Y2-Y1, -Z1) corresponding to the drilling straight line equation is obtained.

[0039] Further, the step S4 comprises the following sub-steps:

[0040] Step S41, the X-ray image of the multilayer circuit board is acquired, and the three-dimensional X-ray model of the multilayer circuit board is obtained by synthesizing the corresponding multiple X-ray images of the multilayer circuit board;

[0041] Step S42, the standard thickness of the circuit board is acquired, the three-dimensional X-ray model is segmented according to the standard thickness of the circuit board, and then the uppermost circuit board and the lowermost circuit board are removed to obtain the three-dimensional X-ray model of the second circuit board to the N-1 circuit board;

[0042] Step S43, for the second circuit board to the N-1 circuit board, the three-dimensional X-ray model of any circuit board is matched with the drilling model, if the matching is successful, the geometric center coordinates (Xi, Yi, Zi) of the matching position are read; wherein, i is the number of the circuit board, i=2, 3, …, N-1;

[0043] If the matching fails, it is determined that there is a drilling defect in the corresponding circuit board, and an abnormal signal is generated;

[0044] Step S44, the shortest distance JLi between the geometric center coordinates of any circuit board and the drilling straight line equation is calculated.

[0045] Further, the step S4 further comprises the following sub-steps:

[0046] Step S45, the shortest distance between the geometric center coordinates and the drilling straight line equation is compared with the distance threshold value, if the shortest distance is less than or equal to the first distance threshold value, the drilling offset level of the corresponding circuit board is recorded as the first offset; if the shortest distance is greater than the first distance threshold value and the shortest distance is less than or equal to the first distance threshold value, the drilling offset level of the corresponding circuit board is recorded as the second offset; if the shortest distance is greater than the second distance threshold value, it is determined that there is a drilling defect in the corresponding circuit board, and an abnormal signal is generated;

[0047] Wherein, the drilling corresponding to the first offset is better than the drilling corresponding to the second offset, and the first distance threshold value is less than the second distance threshold value;

[0048] Step S46, the ultrasonic wave model of the multilayer circuit board is acquired, and the ultrasonic wave models of the second circuit board to the N-1 circuit board are obtained in turn, and the drilling model of the drilling in the corresponding circuit board ultrasonic wave model is obtained according to the geometric center coordinates;

[0049] Step S47, read the maximum width and the minimum width of the drilling model, and compare the maximum width and the minimum width of the drilling model with the width threshold interval; if the maximum width and the minimum width of the drilling model are both located between the width threshold interval, then proceed to the subsequent step; if any one of the maximum width and the minimum width of the drilling model is located outside the width threshold interval, it is determined that there is a drilling defect in the corresponding circuit board, and an abnormal signal is generated.

[0050] Further, the calculation process of the shortest distance in step S44 is as follows:

[0051] Step S441, obtain the drilling straight line equation, and set the drilling straight line equation as t, that is:

[0052] ;

[0053] Step S442, further, x=(X2-X1) t+X1; y=(Y2-Y1) t+Y1, Z=-Z1 t+Z1 are obtained; step S443, set the geometric center coordinates Q(Xi, Yi, Zi), and any point P(x, y, z) on the straight line;

[0054] Step S444, then the vector PQ is represented as: PQ= ((Xi-(X2-X1) t-X1), (Yi-(Y2-Y1) t-Y1), (Zi+Z1 t-Z1));

[0055] Step S445, obtain the direction vector XL of the drilling straight line equation, XL=(X2-X1, Y2-Y1, -Z1);

[0056] Step S446, obtain the shortest distance JLi by using the projection of the vector:

[0057] ; in the formula, the cross product of the vector is represented as ×, and the module length of the calculation vector XL is represented as |XL|.

[0058] The multi-layer circuit board drilling defect automatic detection system comprises:

[0059] The first acquisition module is used for acquiring the outer surface image of the multi-layer circuit board and sending the outer surface image to the image processing module.

[0060] The image processing module is used for processing the outer surface image of the multi-layer circuit board to obtain the edge contour images of the first circuit board and the Nth circuit board in the multi-layer circuit board and send the edge contour images to the image analysis module.

[0061] The image analysis module is used for analyzing the edge contour images of the first circuit board and the Nth circuit board, obtaining the expression of the drilling straight line equation and the direction vector corresponding to the multi-layer circuit board, and sending the expression and the direction vector to the comprehensive analysis module, or obtaining an abnormal signal and sending the abnormal signal to the user terminal.

[0062] a second acquisition module, configured to acquire X-ray images and ultrasonic wave models corresponding to the second circuit board to the N-1th circuit board in the multilayer circuit board and send the X-ray images and the ultrasonic wave models to the comprehensive analysis module;

[0063] a comprehensive analysis module, configured to analyze the X-ray images and the ultrasonic wave models of the multilayer circuit board, obtain a drilling deviation level or an abnormal signal corresponding to a drilling hole of an arbitrary circuit board, and send the drilling deviation level or the abnormal signal to a user terminal;

[0064] the user terminal, configured to receive the abnormal signal or the drilling deviation level corresponding to the multilayer circuit board, and read the abnormal signal or the drilling deviation level to know a drilling defect of the multilayer circuit board.

[0065] In summary, due to the adoption of the technical scheme, the present application has the following beneficial effects:

[0066] 1. The present application firstly acquires an outer surface image of the multilayer circuit board, then pre-processes the outer surface image to obtain edge contour maps of the first circuit board and the Nth circuit board, and then analyzes the edge contours of the first circuit board and the Nth circuit board to obtain an expression and a direction vector of a drilling straight line equation, thereby realizing accurate determination of drilling defects on the outer surface of the multilayer circuit board.

[0067] 2. The present application measures the second circuit board to the N-1th circuit board in the multilayer circuit board to obtain corresponding X-ray images and ultrasonic wave models, analyzes the X-ray images and the ultrasonic wave models of the multilayer circuit board to obtain a drilling deviation level corresponding to a drilling hole of an arbitrary circuit board, and finally receives an abnormal signal or a drilling deviation level corresponding to the multilayer circuit board, and reads the abnormal signal or the drilling deviation level to know a drilling defect of the multilayer circuit board, thereby realizing accurate determination of drilling defects inside the multilayer circuit board. BRIEF DESCRIPTION OF DRAWINGS

[0068] For the convenience of those skilled in the art, the present application will be further described below with reference to the accompanying drawings.

[0069] Figure 1 The present application is a method flowchart.

[0070] Figure 2 The present application is a schematic diagram of a drilling straight line equation.

[0071] Figure 3 The present application is a side view of a multilayer circuit board.

[0072] Figure 4 The present application relates to a system framework diagram. DETAILED DESCRIPTION

[0073] The technical solutions of the present application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0074] Embodiment 1, please refer to Figures 1-3 As shown in the drawings, the present application provides a technical solution: a multilayer circuit board drilling defect automatic detection method for respectively performing external drilling detection and internal drilling detection on a multilayer circuit board, thereby realizing accurate identification of drilling defects of the multilayer circuit board.

[0075] In this embodiment, the method comprises:

[0076] Step S1, collecting the outer surface image of the multilayer circuit board, and then pre-processing the outer surface image to obtain the edge contour map of the first circuit board and the Nth circuit board; specifically, when collecting the outer surface image of the multilayer circuit board, the multilayer circuit board is placed in a position with sufficient light to ensure that the camera can clearly capture the multilayer circuit board.

[0077] In the present application, the step S1 comprises the following sub-steps:

[0078] Step S11, the multilayer circuit board is divided into the first circuit board to the Nth circuit board in turn, wherein N is the number of layers of the circuit board;

[0079] Step S12, adjusting the multilayer circuit board to the first circuit board facing upward and placing it in the camera shooting range, and shooting the outer surface image of the first circuit board through the camera;

[0080] Step S13, adjusting the multilayer circuit board to the Nth circuit board facing upward and placing it in the camera shooting range, and then shooting the outer surface image of the Nth circuit board through the camera;

[0081] Step S14, analyzing the outer surface image of the first circuit board to obtain the edge contour of the first circuit board;

[0082] In the present application, the step S14 comprises the following sub-steps:

[0083] Step S141, obtaining the outer surface image of the first circuit board, extracting the pixel values of a plurality of pixel points in the first circuit board, and obtaining the R value component RZx, the G value component GZx and the B value component BZx of each pixel point; wherein x is the number of pixel points, x=1, 2, …, z, z is a positive integer;

[0084] Step S142, calculating the gray value HDx of each pixel point in the first circuit board by the formula, which is specifically as follows:

[0085] HDx = ​​(A1 × RZx + A2 × GZx + A3 × BZx) / 3; where A1, A2 and A3 are fixed proportionality coefficients, A1 < A2 < A3 and A1 + A2 + A3 = 1;

[0086] Step S143: Obtain the Gaussian gray value GHDx of the corresponding pixel by passing the gray value of the pixel through a Gaussian filtering function. The Gaussian filtering function is as follows:

[0087] In the formula, σ is a constant, and exp is a power function with base e.

[0088] Step S144: Record any pixel as the selected pixel, record the pixels adjacent to the selected pixel as the neighboring pixels, and calculate the difference in Gaussian gray values ​​between the neighboring pixels and the selected pixel as the gray value difference.

[0089] Step S145: Compare the grayscale difference of the selected pixel with the grayscale difference threshold. If any grayscale difference corresponding to the selected pixel is greater than or equal to the grayscale difference threshold, the selected pixel is recorded as an edge pixel. If all grayscale differences corresponding to the selected pixel are less than the grayscale difference threshold, no operation is performed.

[0090] Step S146: Connect adjacent edge pixels to obtain the edge contour of the first circuit board;

[0091] Step S15, similarly, extract the edge contour of the Nth circuit board.

[0092] Step S2: Analyze the edge contours of the first circuit board and the Nth circuit board to obtain the expression and direction vector of the corresponding drilling line equation;

[0093] In this invention, step S2 includes the following sub-steps:

[0094] Step S21: Obtain the edge contour of the first circuit board and the edge contour of the Nth circuit board;

[0095] Step S22: Match the edge contours of the first circuit board and the Nth circuit board with the drilling diagram. If the matching is successful, the successfully matched edge contour is recorded as the drilling contour. If the matching fails, it is determined that there is a drilling defect in the circuit board, and an abnormal signal is generated.

[0096] Step S23, as Figure 2 As shown, a spatial rectangular coordinate system is constructed by taking any two mutually perpendicular straight lines in the plane where the Nth circuit board is located as the X-axis and Y-axis, and drawing a straight line perpendicular to the plane where the Nth circuit board is located as the Z-axis.

[0097] Step S24: Mark the first center coordinates of the drill hole contour corresponding to the first circuit board as (X1, Y1, Z1); mark the Nth center coordinates of the drill hole contour corresponding to the Nth circuit board as (X2, Y2, 0).

[0098] It should be noted that, due to various factors, the borehole profile may not be a standard circle. In this case, when selecting the center, select the center of the smallest circumcircle corresponding to the borehole profile.

[0099] Step S25: Calculate the offset distance PY between the projections of the first circle center coordinates and the Nth circle center coordinates using the following formula:

[0100] ;

[0101] Step S26: Compare the offset distance with the deviation distance threshold. If the offset distance is greater than or equal to the deviation distance threshold, the circuit board is identified as having a drilling defect, and an abnormal signal is generated. If the offset distance is less than the deviation distance threshold, the drilling line equation expression for the corresponding drill hole is obtained. The drilling line equation expression is specifically as follows:

[0102] In the formula, (x, y, z) are variables describing the position coordinates of different points in the borehole straight line equation;

[0103] For ease of writing, this invention shows the point-direction equation of the borehole straight line equation. In specific calculations, the general form of the borehole straight line equation should be selected. The general form of the straight line equation is: Ax + By + Cz + D = 0, where A, B, C and D are all constants.

[0104] Step S27, further, obtain the direction vector XL = (X2-X1, Y2-Y1, -Z1) of the corresponding borehole line equation.

[0105] Step S3: Measure the second to N-1th circuit boards in the multilayer circuit board to obtain the corresponding X-ray images and ultrasonic models;

[0106] In this invention, step S3 includes the following sub-steps:

[0107] Step S31: Place the multilayer circuit board on the inspection platform, ensuring that the multilayer circuit board is in the path of the X-ray.

[0108] Step S32: Rotate the multilayer circuit board at a constant speed, and take an X-ray image every 0.5° to 1° of rotation until it has rotated one circle, to obtain multiple X-ray images of the multilayer circuit board;

[0109] Step S33, place the multilayer circuit board on the ultrasonic detection platform, send ultrasonic waves to the multilayer circuit board by setting a specific frequency to obtain a corresponding ultrasonic image, denoted as an ultrasonic model of the multilayer circuit board;

[0110] It should be noted that the ultrasonic model is a three-dimensional model of the multilayer circuit board.

[0111] Step S4, analyze the X-ray image of the multilayer circuit board and the ultrasonic model to obtain a drilling offset level of the corresponding drilling of the arbitrary circuit board;

[0112] In the present application, the step S4 includes the following sub-steps:

[0113] Step S41, obtain the X-ray image of the multilayer circuit board, and synthesize the corresponding multiple X-ray images of the multilayer circuit board to obtain a three-dimensional X-ray model of the multilayer circuit board;

[0114] Specifically, the multiple X-ray images can be imported into three-dimensional reconstruction software or tools, which can be Autodesk ReCap and MeshLab, etc.

[0115] Step S42, obtain the standard thickness of the circuit board, segment the three-dimensional X-ray model according to the standard thickness of the circuit board, and then remove the uppermost circuit board and the lowermost circuit board to obtain the three-dimensional X-ray model of the second circuit board to the N-1 circuit board;

[0116] Step S43, for the second circuit board to the N-1 circuit board, select the three-dimensional X-ray model of an arbitrary circuit board to match with the drilling model, if the matching is successful, read the geometric center coordinates (Xi, Yi, Zi) of the matching position; wherein, i is the number of the circuit board, i=2, 3, …, N-1;

[0117] If the matching fails, it is determined that there is a drilling defect in the corresponding circuit board, and an abnormal signal is generated.

[0118] Step S44, calculate the shortest distance JLi between the geometric center coordinates of the arbitrary circuit board and the drilling straight line equation;

[0119] The calculation process of the shortest distance in the step S44 is as follows:

[0120] Step S441, obtain the drilling straight line equation, and set the drilling straight line equation as t, i.e.:

[0121] ;

[0122] Step S442, further, x=(X2-X1)t+X1; y=(Y2-Y1)t+Y1, Z=-Z1t+Z1; step S443, set the geometric center coordinates Q(Xi, Yi, Zi), any point P(x, y, z) on the straight line;

[0123] Step S444, then the vector PQ is represented as: PQ= ((Xi- (X2-X1)t-X1), (Yi- (Y2-Y1)t-Y1), (Zi+Z1t-Z1));

[0124] Step S445, get the direction vector XL of the drilling straight line equation=(X2-X1, Y2-Y1, -Z1);

[0125] Step S446, the shortest distance JLi is obtained by using the projection of the vector:

[0126] ; In the formula, the cross product of the vector represents the cross product of the vector, and |XL| represents the length of the calculation vector XL;

[0127] Step S45, compare the shortest distance between the geometric center coordinates and the drilling straight line equation with the distance threshold value, if the shortest distance is less than or equal to the first distance threshold value, the drilling offset level of the corresponding circuit board is recorded as first level offset; if the shortest distance is greater than the first distance threshold value and the shortest distance is less than or equal to the first distance threshold value, the drilling offset level of the corresponding circuit board is recorded as second level offset; if the shortest distance is greater than the second distance threshold value, it is determined that the corresponding circuit board has drilling defects, and an abnormal signal is generated;

[0128] Wherein, the drilling corresponding to the first level offset is better than the drilling corresponding to the second level offset, and the first distance threshold value is less than the second distance threshold value;

[0129] Step S46, obtain the ultrasonic wave model of the multilayer circuit board, and obtain the ultrasonic wave model of the second circuit board to the N-1 circuit board in turn, and obtain the drilling model of the drilling in the corresponding circuit board ultrasonic wave model according to the geometric center coordinates;

[0130] Step S47, read the maximum width and minimum width of the drilling model, and compare the maximum width and minimum width of the drilling model with the width threshold interval; if the maximum width and minimum width of the drilling model are located between the width threshold interval, the subsequent step is performed; if any one of the maximum width and minimum width of the drilling model is located outside the width threshold interval, it is determined that the corresponding circuit board has drilling defects, and an abnormal signal is generated.

[0131] Step S5, receive the abnormal signal or drilling offset level corresponding to the multilayer circuit board, and read the abnormal signal or drilling offset level to know the drilling defect situation of the multilayer circuit board.

[0132] In the present application, if the corresponding calculation formula appears, the above calculation formula is to calculate the numerical value without dimension, and the weight coefficient, the proportion coefficient and other coefficients existing in the formula are set to obtain a result value of quantization of each parameter. The size of the weight coefficient and the proportion coefficient can be as long as it does not affect the proportional relationship between the parameter and the result value.

[0133] Embodiment 2, please refer to Figure 4 As shown in the same application, based on another concept, the present application proposes a multilayer circuit board drilling defect automatic detection system, comprising a first acquisition module, a second acquisition module, an image processing module, an image analysis module, a comprehensive analysis module and a user terminal;

[0134] The first acquisition module is used for acquiring the outer surface image of the multilayer circuit board and sending it to the image processing module;

[0135] The image processing module is used for processing the outer surface image of the multilayer circuit board to obtain the edge profile of the first circuit board and the Nth circuit board in the multilayer circuit board and send it to the image analysis module;

[0136] The image analysis module is used for analyzing the edge profile of the first circuit board and the Nth circuit board, and obtaining the expression of the straight line equation of the corresponding drilling of the multilayer circuit board and the direction vector and sending it to the comprehensive analysis module, or obtaining the abnormal signal and sending it to the user terminal;

[0137] The second acquisition module is used for acquiring the X-ray image and ultrasonic model corresponding to the second circuit board to the N-1th circuit board in the multilayer circuit board and sending it to the comprehensive analysis module;

[0138] The comprehensive analysis module is used for analyzing the X-ray image and ultrasonic model of the multilayer circuit board to obtain the drilling offset level or abnormal signal of the corresponding drilling of any circuit board and send it to the user terminal;

[0139] The user terminal is used for receiving the corresponding abnormal signal or drilling offset level of the multilayer circuit board, and the user reads the abnormal signal or drilling offset level to know the drilling defect of the multilayer circuit board.

[0140] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments. Obviously, according to the content of the specification, many modifications and changes can be made. The embodiments are selected and described in detail in order to better explain the principles and practical application of the application, so that those skilled in the art can well understand and use the application. The application is limited by the claims and their entire scope and equivalents.

Claims

1. An automatic detection method for drilling defects in multilayer circuit boards, characterized in that the method... The method comprises the following steps: Step S1, acquiring the outer surface image of the multilayer circuit board, and then preprocessing the outer surface image to obtain the edge contour graph of the first circuit board and the Nth circuit board; Step S2, analyzing the edge contour of the first circuit board and the Nth circuit board to obtain the expression and direction vector of the corresponding drilling straight line equation, matching the edge contour of the first circuit board and the Nth circuit board with the drilling schematic diagram, if the matching is successful, the successfully matched edge contour is recorded as the drilling contour, if the matching fails, it is determined that the circuit board has drilling defects, and an abnormal signal is generated; Step S3, measuring the second circuit board to the N-1th circuit board in the multilayer circuit board to obtain the corresponding X-ray image and ultrasonic model; Step S4, analyzing the X-ray image and ultrasonic model of the multilayer circuit board to obtain the drilling offset level of the corresponding drilling of any circuit board; Step S5, receiving the abnormal signal or the drilling offset level corresponding to the multilayer circuit board, and reading the abnormal signal or the drilling offset level to know the drilling defect condition of the multilayer circuit board; The step S4 further comprises the following substeps: Obtaining the X-ray image of the multilayer circuit board, synthesizing the plurality of X-ray images corresponding to the multilayer circuit board to obtain a three-dimensional X-ray model of the multilayer circuit board, comparing the shortest distance between the geometric center coordinates of any circuit board and the drilling straight line equation with the distance threshold, if the shortest distance is less than or equal to the first distance threshold, the drilling offset level of the corresponding circuit board is recorded as the first level offset, if the shortest distance is greater than the first distance threshold and the shortest distance is less than or equal to the first distance threshold, the drilling offset level of the corresponding circuit board is recorded as the second level offset, if the shortest distance is greater than the second distance threshold, it is determined that the corresponding circuit board has drilling defects, and an abnormal signal is generated; Wherein, the drilling corresponding to the first level offset is better than the drilling corresponding to the second level offset, and the first distance threshold is less than the second distance threshold; Obtaining the ultrasonic model of the multilayer circuit board, obtaining the ultrasonic model of the second circuit board to the N-1th circuit board in turn, and obtaining the drilling model of the drilling in the ultrasonic model of the corresponding circuit board according to the geometric center coordinates; Reading the maximum width and the minimum width of the drilling model, and comparing the maximum width and the minimum width of the drilling model with the width threshold interval, if the maximum width and the minimum width of the drilling model are both located between the width threshold interval, the subsequent step is performed, if any one of the maximum width and the minimum width of the drilling model is located outside the width threshold interval, it is determined that the corresponding circuit board has drilling defects, and an abnormal signal is generated.

2. The multilayer wiring board drill hole defect automatic detection method according to claim 1, characterized by, The step S1 comprises the following substeps: Step S11, dividing the multilayer circuit board into the first circuit board to the Nth circuit board in turn, wherein N is the number of layers of the circuit board; Step S12, adjusting the multilayer circuit board to the first circuit board facing upward and being placed in the shooting range of the camera, and shooting the outer surface image of the first circuit board through the camera; Step S13, adjusting the multilayer circuit board to the Nth circuit board facing upward and being placed in the shooting range of the camera, and then shooting the outer surface image of the Nth circuit board through the camera; Step S14, analyzing the outer surface image of the first circuit board to obtain the edge contour of the first circuit board; Step S15, similarly, the edge contour of the Nth circuit board is extracted.

3. The multilayer wiring board drill hole defect automatic detection method according to claim 2, characterized by, The step S14 comprises the following sub-steps: Step S141, the outer surface image of the first circuit board is acquired, the pixel values of a plurality of pixel points in the first circuit board are extracted, and the R value component RZx, the G value component GZx and the B value component BZx of each pixel point are obtained; wherein x is the number of the pixel point, x=1, 2, …, z, and z is a positive integer; Step S142, the gray value HDx of each pixel point in the first circuit board is calculated by the formula, and the formula is specifically as follows: HDx= (A1×RZx+A2×GZx+A3×BZx) / 3; wherein A1, A2 and A3 are fixed numerical proportion coefficients, A1 Step S143, the gray value of the pixel point is obtained by the Gaussian filtering function to obtain the Gaussian gray value GHDx of the corresponding pixel point, and the Gaussian filtering function is specifically: ; In the formula, σ is a constant, and exp is the power function with e as the base.

4. The multilayer wiring board drill hole defect automatic detection method according to claim 3, characterized by, The step S14 further comprises: Step S144, any pixel point is recorded as a selected pixel point, a pixel point adjacent to the selected pixel point is recorded as an adjacent pixel point, and the difference between the adjacent pixel point and the selected pixel point is recorded as a gray difference value; Step S145, the gray difference value of the selected pixel point is compared with the gray difference value threshold, if any gray difference value corresponding to the selected pixel point is greater than or equal to the gray difference value threshold, the selected pixel point is recorded as an edge pixel point, if all the gray difference values corresponding to the selected pixel point are less than the gray difference value threshold, no operation is performed; Step S146, the adjacent edge pixel points are connected to obtain the edge contour of the first circuit board.

5. The multilayer wiring board drill hole defect automatic detection method according to claim 1, characterized by, The step S2 comprises the following sub-steps: Step S21, the edge contour of the first circuit board and the edge contour of the Nth circuit board are acquired; Step S22, the edge contour of the first circuit board and the edge contour of the Nth circuit board are matched with the drilling schematic diagram, if the matching is successful, the successfully matched edge contour is recorded as a drilling contour, if the matching fails, it is determined that the circuit board has a drilling defect, and an abnormal signal is generated; Step S23, any two mutually perpendicular straight lines in the plane where the Nth circuit board is located are taken as the X axis and the Y axis, a straight line perpendicular to the plane where the Nth circuit board is located is taken as the Z axis, and a space rectangular coordinate system is constructed; Step S24, the first center coordinates of the first circuit board corresponding to the drilling contour are recorded as (X1, Y1, Z1), and the Nth center coordinates of the Nth circuit board corresponding to the drilling contour are recorded as (X2, Y2, 0).

6. The multilayer wiring board drill hole defect automatic detection method according to claim 5, characterized by, The step S2 further comprises the following sub-steps: Step S25, the offset distance PY between the projection of the first center coordinates and the Nth center coordinates is calculated by the formula, and the formula is specifically as follows: ； Step S26, the offset distance is compared with the offset distance threshold, if the offset distance is greater than or equal to the offset distance threshold, it is determined that the circuit board has a drilling defect, and an abnormal signal is generated, if the offset distance is less than the offset distance threshold, the drilling straight line equation expression corresponding to the drilling hole is obtained, and the drilling straight line equation expression is specifically as follows: ； Step S27, further, the direction vector XL= (X2-X1, Y2-Y1, -Z1) of the drilling straight line equation is obtained.

7. The multilayer wiring board drill hole defect automatic detection method according to claim 5, characterized by, The step S4 comprises the following sub-steps: Step S41, an X-ray image of the multilayer circuit board is acquired, and a three-dimensional X-ray model of the multilayer circuit board is obtained by synthesizing the corresponding multiple X-ray images of the multilayer circuit board; Step S42, a standard thickness of the circuit board is acquired, the three-dimensional X-ray model is segmented according to the standard thickness of the circuit board, and then the uppermost circuit board and the lowermost circuit board are removed to obtain three-dimensional X-ray models of the second circuit board to the N-1th circuit board; Step S43, for the second circuit board to the N-1th circuit board, the three-dimensional X-ray model of an arbitrary circuit board is matched with a drilling model, if the matching is successful, the geometric center coordinates (Xi, Yi, Zi) of the matching position are read; wherein i is the number of the circuit board, i = 2, 3, …, N-1; If the matching fails, it is determined that there is a drilling defect in the corresponding circuit board, and an abnormal signal is generated; Step S44, the shortest distance JLi between the geometric center coordinates of an arbitrary circuit board and the drilling straight line equation is calculated.

8. The multilayer wiring board drill hole defect automatic detection method according to claim 7, characterized by, The calculation process of the shortest distance in step S44 is as follows: Step S441, the drilling straight line equation is acquired, and the drilling straight line equation is set as t, that is: ； Step S442, further, x = (X2-X1) t + X1; y = (Y2-Y1) t + Y1, Z = -Z1 t + Z1 are obtained; step S443, set the geometric center coordinates Q (Xi, Yi, Zi), and an arbitrary point P (x, y, z) on the straight line; Step S444, then the vector PQ is represented as: PQ = ((Xi- (X2-X1) t-X1), (Yi- (Y2-Y1) t-Y1), (Zi+Z1 t-Z1)); Step S445, the direction vector XL of the drilling straight line equation is acquired, XL = (X2-X1, Y2-Y1, -Z1); Step S446, the shortest distance JLi is obtained by using the projection of the vector: ; where x denotes the cross product of vectors and |XL| denotes the modulus of the vector XL.

9. A multilayer wiring board drill hole defect automatic detection system, characterized by, The multilayer circuit board drilling defect automatic detection method of any one of claims 1-8 comprises: A first acquisition module is configured to acquire an outer surface image of the multilayer circuit board and send the outer surface image to an image processing module; The image processing module is configured to process the outer surface image of the multilayer circuit board to obtain edge profile images of the first circuit board and the Nth circuit board in the multilayer circuit board and send the edge profile images to an image analysis module; The image analysis module is configured to analyze the edge profile images of the first circuit board and the Nth circuit board, obtain an expression of a drilling straight line equation corresponding to the multilayer circuit board and a direction vector of the drilling straight line equation, and send the expression and the direction vector to a comprehensive analysis module, or obtain an abnormal signal and send the abnormal signal to a user terminal; A second acquisition module is configured to acquire X-ray images and ultrasonic wave models corresponding to the second circuit board to the N-1th circuit board in the multilayer circuit board and send the X-ray images and the ultrasonic wave models to the comprehensive analysis module; The comprehensive analysis module is configured to analyze the X-ray images and the ultrasonic wave models of the multilayer circuit board, obtain a drilling deviation level or an abnormal signal of a drilling hole corresponding to an arbitrary circuit board, and send the drilling deviation level or the abnormal signal to a user terminal; The user terminal is configured to receive the abnormal signal or the drilling deviation level corresponding to the multilayer circuit board, and the user reads the abnormal signal or the drilling deviation level to know the drilling defect of the multilayer circuit board.

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