Printed circuit board inspection system and method

Abstract

To provide a printed circuit board inspection system and a method for the same.SOLUTION: A printed circuit board inspection system according to the present invention includes an automatic optical line measurement device and a line characteristic checking device. The automatic optical line measurement device photographs a line image of a printed circuit board, thereby obtaining line size information of the printed circuit board. The line characteristic checking device is connected to the automatic optical line measurement device and obtains the line size information. On the basis of line reference characteristic information of a test coupon and the line size information of the printed circuit board, the line characteristic checking device obtains the electric characteristic information of the printed circuit board.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printed circuit board inspection system and method, and more particularly to a printed circuit board inspection system and method that performs calibration based on line reference characteristic information of a test coupon. [Background technology]

[0002] The impedance of a printed circuit board (PCB) refers to the total resistance consisting of electrical characteristic parameters such as resistance, inductance, and capacitance in the signal transmission line on the PCB. These parameters affect the signal transmission speed, the degree of waveform distortion, noise, power consumption, etc., so controlling the PCB impedance is of great significance for ensuring signal quality.

[0003] In the application of high-speed data transmission and high-frequency circuits, it is especially necessary to control the impedance of the PCB to ensure that the signal can be transmitted effectively and the signal distortion can be reduced. Otherwise, it may affect the signal quality and transmission speed. Therefore, the purpose of measuring the PCB impedance is to confirm whether the PCB design meets the specification requirements and whether it needs adjustment and optimization so that the signal can be transmitted properly.

[0004] PCB impedance is usually expressed in units of ohms (Ω), and the value is affected by many factors (transmission line geometry, dielectric constant, signal frequency, etc.). Whether the structural stacking, material matching, and process parameters of high-end printed circuit board design are proper and stable will have a great impact on the quality of the finished product. In particular, the interlayer conduction method and its reliability have a great impact on the performance of the entire circuit board.

[0005] In order to test the presence or absence of defects in the printed circuit board during the manufacturing process and ensure the yield rate of the printed circuit board, a test coupon located at the edge or corner of the printed circuit board may be added to the design of the printed circuit board. By testing these test coupons, the manufacturing of the printed circuit board is made to comply with standards and regulations, and mistakes and defects during the manufacturing process are reduced. In order to check whether the line characteristics of the printed circuit board comply with the standards, printed circuit board testing (PCB testing) is usually performed on the test coupons. This type of testing is mainly used to contact check the continuity and insulation of the printed circuit board using test points and test lines, or to check the resistance or impedance characteristics of the printed circuit board. This type of testing may be a flying probe test.

[0006] However, when using the contact inspection method, if the impedance value of the PCB does not meet the standard, it can only be found that some areas or certain lines are defective, but the actual location of the defect cannot be identified and repaired. In addition, using the contact inspection method requires testing each test point on the printed circuit board or test coupon, which takes a long time to complete the test of the entire board, reducing production efficiency. Summary of the Invention [Means for solving the problem]

[0007] A primary object of the present invention is to provide a printed circuit board inspection system including an automatic optical line measurement device and a line characteristic checking device. The automatic optical line measurement device obtains line size information of the printed circuit board by taking a line image of the printed circuit board. The line characteristic checking device is connected to the automatic optical line measurement device and obtains the line size information. The line characteristic checking device obtains electrical characteristic information of the printed circuit board based on line reference characteristic information of the test coupon and the line size information of the printed circuit board.

[0008] Another object of the present invention is to provide a printed circuit board inspection method including the steps of obtaining line reference characteristic information based on a test coupon for the printed circuit board, photographing a line image of the printed circuit board to obtain line size information of the printed circuit board, and obtaining electrical characteristic information of the printed circuit board based on the line reference characteristic information of the test coupon and the line size information of the printed circuit board. Effect of the Invention

[0009] Therefore, the present invention obtains resistance data or impedance data of a circuit through a non-contact automatic optical line measurement method, shortens the inspection time of the entire circuit, and further calibrates the data obtained by the automatic optical line measurement through line reference characteristic information obtained by a test coupon (PCB test coupon), making the resistance or impedance data more accurate, thereby improving the inspection efficiency and effect. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a schematic diagram of a printed circuit board inspection system according to the present invention; [Diagram 2] 1 is a block diagram illustrating a printed circuit board inspection system according to an embodiment of the present invention. [Diagram 3] 1 is a block diagram illustrating a contact-type measuring device according to an embodiment of the present invention. [Figure 4] 1 is a block diagram illustrating an automatic optical line measuring device according to an embodiment of the present invention. [Diagram 5] 1 is a block diagram illustrating an automatic optical line measuring device according to an embodiment of the present invention. [Figure 6] 1 is a schematic diagram showing an optical arrangement of an automatic optical line measuring device according to an embodiment of the present invention; [Figure 7] 1 is a schematic cross-sectional view of a printed circuit board trace according to one embodiment of the present invention. [Figure 8] 2 is a schematic diagram of a printed circuit board trace divided into multiple cross sections according to one embodiment of the present invention; [Figure 9] 1 is a block diagram illustrating a manual inspection device according to an embodiment of the present invention; [Figure 10] 1 is a schematic diagram of a circuit board marking image according to one embodiment of the present invention. [Figure 11] 1 is a trend graph of impedance change in a section line according to an embodiment of the present invention. [Figure 12] 2 is a flowchart of a printed circuit board inspection method according to an embodiment of the present invention. [Figure 13] FIG. 2 is a block diagram illustrating a schematic diagram of a printed circuit board inspection system according to another embodiment of the present invention. [Figure 14] 5 is a flowchart of a printed circuit board inspection method according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The detailed description and technical contents of the present invention will be described below with reference to the drawings. The term "one side" in the present invention may be the upper side, lower side, left side, right side, front side, or rear side of a specific corresponding object, or may be provided at any adjacent position of an object, or may be directly or indirectly connected to an object, and is not limited in the present invention.

[0012] The various materials and data described in the present invention can be stored in any non-transitory storage device, such as a local server or a cloud server, but this is not limited in the present invention. Alternatively, the various materials and data can be stored in the storage device of each device or in a database of a central control system, but this is not limited in the present invention.

[0013] The "modules" and the corresponding functions described in the present invention can be incorporated into a storage device by a single chip or a combination of multiple chips, and can be executed in cooperation with each other, and the number of chips is not included in the scope of the present invention. The chips can be, but are not limited to, a combination of devices such as a processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and the like, and the present invention is not limited to these. The "storage device" described in the present invention can be, but is not limited to, a device capable of storing and retrieving data, such as a cache memory, a dynamic random access memory (DRAM), a persistent memory, and the like, or a combination thereof, and the present invention is not limited to these.

[0014] A specific embodiment will be described. "Figure 1" is a block diagram showing a schematic diagram of a printed circuit board inspection system in the present invention, and as shown in the figure, the object to be inspected is a printed circuit board A including a circuit board body A1 and a test coupon A2 (PCB test coupon) bonded to one side of the circuit board body A1. The test coupon A2 is a small sample for testing the quality and performance of the circuit board body A1, and is usually disposed at an edge or corner of the circuit board body A1, and has various layers and characteristics the same as the circuit board body A1.

[0015] This embodiment discloses a printed circuit board inspection system 100, which mainly includes an automatic optical line measurement device 10, a line characteristic checking device 20, and a central control system 30. The automatic optical line measurement device 10 obtains line size information of the circuit board body A1 by photographing a line image of the circuit board body A1. The line characteristic checking device 20 is connected to the automatic optical line measurement device 10 to obtain the line size information. The line characteristic checking device 20 obtains electrical characteristic information of the circuit board body A1 based on the line reference characteristic information of the test coupon A2 and the line size information of the circuit board body A1.

[0016] In one embodiment, various parameters inspected by the automatic optical line measurement apparatus 10 can be transmitted to a central control system 30 (e.g., a programmable logic controller PLC), and the corresponding parameters can be stored in a database (not shown) through the central control system 30 and can be called up from the database as needed. In another embodiment, various parameters inspected by the automatic optical line measurement apparatus 10 can be stored in a server of an individual device, and variations in these embodiments are not within the scope of the present invention. In one embodiment, the line reference characteristic information of the test coupon A2 can also be stored in the database of the central control system 30 for easy calling. In this embodiment, the line reference characteristic information can include, for example, but is not limited to, line resistance data of the coupon portion or line impedance data of the coupon portion.

[0017] Regarding one embodiment of the present invention, referring to the following "FIG. 2", "FIG. 3" and "FIG. 4" in combination, a block diagram of a printed circuit board inspection system according to an embodiment of the present invention, a block diagram of a contact type measuring device according to an embodiment of the present invention, and a block diagram of an automatic optical line measuring device according to an embodiment of the present invention are shown. As shown in the figures, in this embodiment, the line reference characteristic information of the test coupon A2 can be obtained through a contact type measuring device 40, the contact type measuring device 40 includes a storage device 41, and obtains line resistance data or line impedance data of the coupon part of the test coupon A2 by contact inspection of the test coupon A2. The contact type measuring device 40 may include, but is not limited to, a flying probe tester or other contact type equipment, and the present invention is not limited thereto.

[0018] In one embodiment, the contact measuring device 40 may include, but is not limited to, a multimeter (DMM), an impedance analyzer (TDR instrument), or other similar device, and measures the line resistance data of the coupon portion and / or the line impedance data of the coupon portion by connecting a test probe to two or more test points on the test coupon A2, and stores the corresponding data in a database. In one embodiment, the obtained line resistance data of the coupon portion or the line impedance data of the coupon portion may be stored in a storage device 41 disposed in the contact measuring device 40, but the present invention is not limited thereto.

[0019] In this embodiment, the automatic optical line measurement device 10 generates calibration parameters based on the line reference characteristic information of the test coupon A2 and the line size information of the circuit board body A1, and calibrates the electrical characteristic information of the circuit board body A1 using the calibration parameters. The line resistance data and / or line impedance data of the coupon portion obtained by the contact type measurement device 40 are used to correct the calibration parameters used when the automatic optical line measurement device 10 measures the line resistance data and / or line impedance data.

[0020] As shown in FIG. 4, the automatic optical line measurement device 10 obtains line size information of the circuit board body A1 by photographing a line image of the circuit board body A1. The line size information includes a line width (for example, may include, but is not limited to, a line top width and a line bottom width), a line height, a line length, or a line cross-sectional area, but is not limited to these in the present invention. Regarding one embodiment of the automatic optical line measurement device 10, with reference to "FIG. 5" as well, a block diagram showing a schematic diagram of an automatic optical line measurement device according to an embodiment of the present invention is shown. As shown in the figure, the automatic optical line measurement device 10 includes a sensing unit 11, a light source 12, and an image measurement module 13. The image measurement module 13 can be executed after being loaded into a storage device via a processor, and the image measurement module 13 is coupled to the sensing unit 11 and used to generate line size information based on the line image.

[0021] The sensing unit 11 is directed to a target area of ​​the circuit board body A1 to obtain a track image. Specifically, the sensing unit 11 can be configured as an area scan camera or a line scan camera, and the track image of the circuit board body A1 is captured by these imaging devices. The target area refers to any area including tracks on the circuit board body A1. The circuit board body A1 can be appropriately illuminated by a light source 12 so that the sensing unit 11 can easily obtain the track image on the circuit board body A1.

[0022] In one embodiment, the image measurement module 13 includes a corresponding image processing program for performing image processing functions, which may be, for example, an image pre-processing program, image segmentation and positioning, defect detection (gradient, region growing, growing compensation, etc.), machine learning system, deep learning system, etc., but are not limited thereto in the present invention. The image measurement module 13 is coupled to the sensing unit 11 and generates track size information according to the track image.

[0023] Hereinafter, the optical arrangement of the automatic optical line measuring device 10 will be described in detail with reference to an embodiment. Referring to "FIG. 6", a schematic diagram showing the optical arrangement of an automatic optical line measuring device according to an embodiment of the present invention is shown. As shown in the figure, in this embodiment, the sensing unit 11 includes a top-view image capturing device 111 and at least one side-view image capturing device 112. The top-view image capturing device 111 is provided on the top-view direction side of the target area to obtain a top-view image of the line image. At least one side-view image capturing device 112 is provided on the side-view direction side of the target area, and the shooting direction of the at least one side-view image capturing device 112 maintains an appropriate inclination angle with respect to the line on the circuit board body A1 to obtain a side-view image of the line. In one embodiment, the side-view image capturing device 112 has an optical axis direction L and has a shooting angle α with respect to the plane of the circuit board body A1, and the shooting angle α is 0 degrees to 90 degrees. In one embodiment, the number of side view image capturing devices 112 is one, but in other embodiments, multiple side view image capturing devices 112 can be provided, and the multiple side view image capturing devices 112 can have the same shooting angle α or different shooting angles α, and the design can be changed according to the inspection needs, but the present invention is not limited thereto.

[0024] With the above-mentioned arrangement, the top view image capturing device 111 and the side view image capturing device 112 respectively obtain top view images and side view images (hereinafter collectively referred to as "track images") of the circuit board body A1, and via these track images, the image measuring module 13 can obtain track size information on the circuit board body A1.

[0025] The calculation procedure executed by the image measurement module 13 will now be described.

[0026] The image measurement module 13 generates track size information mainly based on the track image. Specifically, when the processor loads and executes the program of the image measurement module 13, it analyzes the track image to obtain the first region image feature (top width, bottom width) and the second region image feature (sidewall width) in the track image. Specifically, the image measurement module 13 can perform image pre-processing procedures (image enhancement, noise removal, contrast enhancement, edge enhancement, feature extraction, image compression, image conversion, etc.), and segments or extracts boundaries of the image after the image pre-processing procedures to divide the Region of Interest (ROI). Methods for extracting the Region of Interest include, but are not limited to, binarization or a method of cutting out the first region image feature and the second region image feature from the image after training in a system via a spiking neural network such as a machine learning system or a deep learning system. The present invention is not limited to this. The track image referred to here does not necessarily have to be a single image, and may be two or more track images.

[0027] After obtaining the first and second region image features, the image measurement module 13 analyzes the first and second region image features to obtain line size information including the line width, line height, line cross-sectional area, etc. of the circuit board body A1. The method of obtaining line size information will be described below. Referring to "FIG. 7", a schematic cross-sectional view of a printed circuit board line according to an embodiment of the present invention is shown. As shown in the figure, the line on the circuit board body A1 mainly includes several sets of structure information such as a line upper width UW, a line lower width DW, a line height T, a first sidewall width SW1, and a second sidewall width SW2.

[0028] Taking the aforementioned embodiment of the dual lens (top view image capture device 111, side view image capture device 112) as an example, through the above optical arrangement, the image measurement module 13 can obtain the top track width UW, bottom track width DW, first side wall width SW1, second side wall width SW2 and track height T from two sets of images taken from different directions, and calculate the track cross-sectional area from these data.

[0029] In addition to obtaining such track size information through top view and side view images, in another embodiment, track size information can also be generated by 3D scanning techniques (e.g., Time of Flight (TOF), Triangulation, Stereo Vision), and these methods of obtaining track size information are not within the scope of the present invention.

[0030] In addition to the above embodiments, the line size information may also include, but is not limited to, line length and line volume. The line volume can be calculated from the line cross-sectional area and line length. As a more accurate calculation method, the line volume can be calculated from each sampled line cross-sectional area and each sampled line length.

[0031] Hereinafter, the process of acquiring electrical characteristic information of the circuit board body A1 by the line characteristic checking device 20 in this embodiment will be described with reference to the drawings.

[0032] First, referring to FIG. 8, a schematic diagram of a printed circuit board line divided into multiple cross sections according to an embodiment of the present invention is shown. As shown in the figure, the line characteristic checking device 20 can generate corresponding electrical characteristic information based on the obtained line size information. Here, the electrical characteristic information can include line resistance data or line impedance data. The line characteristic checking device 20 can generate line resistance data according to the line cross-sectional area and line length. Specifically, the line resistance data can be obtained, for example, by the following resistance formula:

number

[0033] In the formula, R is the resistance value, ρ is the resistivity, L is the line length, A is the line cross-sectional area, and k0 is a calibration parameter.

[0034] Based on the line size information, the line is cut into N equal parts to obtain the cross-sectional area data of each section SG1 to SGN of the line at maximum resolution, and the resistance values ​​R1, R2, ... R corresponding to each small section length L1-LN in the previous formula are obtained. N After summing up, the line resistance data of the whole section line is finally obtained as shown in the following formula:

number

[0035] where A1 to AN are the cross-sectional areas of each section of the line. It can be determined that if the resolution or sampling density is increased, the measurement of the resistance value will generally be more accurate.

[0036] In an optional embodiment, taking a microstrip line structure as an example, the line characteristic checking device 20 can generate line impedance value information based on the line width, line height, and the thickness of the dielectric layer of the line in the target area and the conductivity of the line. Here, the thickness of the dielectric layer of the line and the conductivity of the line can be preset values ​​or can be obtained from the test coupon A2 through other inspection methods, and the present invention is not limited thereto. Specifically, the line characteristic checking device 20 can obtain impedance data using, for example, but not limited to, the Wadell equation, the IPC-2141 empirical formula, or estimation software developed by Polar.

[0037] The Wadell equation is:

number

[0038] In the formula, Z0 is the characteristic impedance of the microstrip line (unit: ohms), ε eff is the modified dielectric constant of the medium used in the microstrip line, h is the thickness of the line dielectric layer, w' is the modified width of the microstrip line, and k1 is a calibration parameter.

[0039] The modified dielectric constant of the microstrip line is modified based on the following formula:

number

[0040] In the formula, ε r is the relative dielectric constant of the medium used in the microstrip line, and w is the effective width of the microstrip line.

[0041] The modified width of the microstrip line is modified based on the following formula:

number

[0042] In the formula, w is the original microstrip line width, w' is the modified microstrip line width, Δw is the change in the microstrip line width, Δw' is the change in the microstrip line width after modification, ε r is the relative dielectric constant of the medium used in the microstrip line, t is the thickness of the metal used in the microstrip line, and h is the thickness of the line dielectric layer.

[0043] The empirical formula of IPC-2141 is:

number

[0044] In the formula, Z0 is the characteristic impedance of the microstrip line (unit: ohms), ε r is the relative dielectric constant of the medium used in the microstrip line, h is the thickness of the line dielectric layer, w is the width of the microstrip line, t is the thickness of the metal used in the microstrip line, and k2 is a calibration parameter.

[0045] In addition to the impedance formula provided in the above embodiment, other calculation methods can be referred to and conformed to related standards such as IPC issued by the International Council for Electronics Industry Connection, including but not limited to related standards such as IPC-2221, IPC-2222, IPC-2223, IPC-2224, IPC-2225, IPC-2226, and IPC-2227. In another possible embodiment, the line characteristic verification device 20 can obtain the impedance / resistance through a look-up table. In the look-up table, values ​​that are not displayed in the look-up table can be calculated by the K-Nearest Neighbor method or the Insertion Method, which can be determined according to design needs.

[0046] The automatic optical measurement method may still generate some errors, and in order to ensure the accuracy of the measurement results of resistance or impedance, the above formula includes calibration parameters k0, k1 and k2, which are used to modify the above formula according to the calibration parameters k0, k1 and k2.

[0047] Specifically, the line characteristic verification device 20 obtains line resistance data or line impedance data of the coupon portion of the test coupon A2 via the contact-type measuring device 40, adjusts calibration parameters according to line reference characteristic information such as the line resistance data of the coupon portion or the line impedance data of the coupon portion, and then, when performing automatic optical inspection, can generate line resistance data or line impedance data based on the adjusted calibration parameters.

[0048] In one embodiment, the line closest to the test coupon A2 on the circuit board body A1 can be selected as the standard line for calculating the calibration parameters. The term "closest" can refer to, for example, the closest position, the closest line shape, the closest line size, the closest manufacturing process environmental conditions, and / or the closest line lamination shape, and is not limited thereto in the present invention. The calibration parameters obtained through the standard line can be substituted into the calculation formula to generate accurate line resistance data or line impedance data according to the calibration parameters.

[0049] For example, the electrical resistance measurement data obtained from test coupon A2 is R p The standard line on the circuit board body A1 has theoretical resistance data R q When the resistance data is calculated, the formula is as follows:

number

[0050] Resistance data obtained on the standard line R q and the electrical resistance measurement data R obtained with test coupon A2 p The calibration parameter k0 is obtained by calculating the ratio of

number

[0051] Using the above formula, the resistance data of any line on the printed circuit board can be calculated based on equation (1) through the adjusted calibration parameter k0.

[0052] The impedance test data obtained from test coupon A2 was Z p Then, the standard line on the circuit board body A1 is calculated as theoretical impedance data Z through the Wadell equation, which is an impedance formula. q When the impedance data Z q The calculation formula is as follows:

number

[0053] Impedance data Z obtained from the standard line q and the impedance test value Z obtained with test coupon A2 p The calibration parameter k1 is obtained by calculating the ratio of

number

[0054] Using the above formula, the impedance data of any line on the printed circuit board can be calculated based on equation (2) through the adjusted calibration parameter k1.

[0055] In another embodiment, the theoretical impedance data Z w When the impedance data Z w The calculation formula is as follows:

number

[0056] Impedance data Z obtained from the standard line w and the impedance test value Z obtained with test coupon A2 p The calibration parameter k2 is obtained by calculating the ratio of

number

[0057] Using the above formula, the impedance data of any line on the printed circuit board can be calculated based on equation (3) through the adjusted calibration parameter k2.

[0058] In another embodiment, the impedance electrical measurement data Z from, for example, the test coupon A2 pThe impedance data Z of the standard line was obtained using a TDR impedance measuring instrument. E and further obtain the impedance data Z E and impedance test data Z obtained with test coupon A2 p The calibration parameter k3 is obtained by calculating the ratio of

number

[0059] Using the above formula, the impedance data of any line on the printed circuit board can be constructed through the adjusted calibration parameter k3.

[0060] The present invention can also mark defects and call them up for re-inspection by manual equipment. Referring to Figures 9, 10 and 11, a block diagram showing a manual inspection device according to an embodiment of the present invention, a schematic diagram of a circuit board marking image according to an embodiment of the present invention, and a section line impedance change trend graph according to an embodiment of the present invention are shown. As shown in the figures, in this embodiment, the printed circuit board inspection system of the present invention can further include a defect marking device 50 and a manual inspection device 60.

[0061] The defect marking device 50 includes a defect locating module T1 connected to a storage device 52 through a processor 51, and an image marking module T2. The defect locating module T1 can inspect a specific point in a line, the entire line or a specific section, or a selected line area surface, or the entire board, and this part can be implemented according to actual needs. The defect locating module T1 can set a threshold value (for example, ±10% of the desired resistance value or desired impedance value when the line resistance data or line impedance data is lower or higher than a reasonable threshold range) to check whether the corresponding line has a defect, and store the defect location in the storage device 52. The defect location can be associated with the coordinates of a pixel in a block range, and can be stored in the form of the coordinates of an anchor point and a pixel range, and the present invention is not limited thereto. In one embodiment, when the defect locating module T1 performs inspection of a selected line area surface or the entire board, a threshold value can be set for the line size of the circuit board body A1 to avoid too much calculation, and the part with size abnormality is found according to the threshold value, and then the electrical characteristic inspection of the abnormal part is performed, thereby reducing the calculation burden. In one embodiment, after the inspection of the selected line area surface or the entire board is completed, the object in the image is clicked, and after the click is detected, the defect location module T1 can obtain the electrical characteristic information of the object based on the known line size information of the circuit board body A1 for the position of the object, and such a method can also reduce the calculation burden.

[0062] After the defect location module T1 identifies the defect location, the image marking module T2 can color the defect location and set an index according to the defect information (e.g., line resistance data or line impedance data) and the corresponding coloring location, and transmit this data to the manual inspection device 60 so that the defect can be inspected by the manual inspection device 60.

[0063] The manual inspection device 60 can open the circuit board body image PI of the circuit board body A1 and perform visual inspection (FIG. 10), and when the cursor is moved over the colored defect position (e.g., colored area D1 and colored area D2), various information of the line (including electrical property information, line size information, etc.) can be displayed to confirm the defect of the line at the corresponding location. In a further embodiment, the manual inspection device 60 can plot the result corresponding to the continuous section line as an impedance change trend graph, and as shown in FIG. 11, the vertical axis is the impedance value Zn and the horizontal axis is the line position Ln, thereby obtaining the impedance trend of the section line.

[0064] The flow of the printed circuit board inspection method of the present invention will be described below with reference to an embodiment. Referring to FIG. 12, a flow chart of the printed circuit board inspection method according to an embodiment of the present invention is shown. As shown in the figure, the parameter calibration of the printed circuit board in this embodiment mainly includes the following steps:

[0065] Step S01: First, the line resistance data or line impedance data of the coupon part is obtained based on the test coupon of the printed circuit board. In this embodiment, the line resistance data or line impedance data of the coupon part is obtained by a contact inspection method of the test coupon A2 by the contact type measuring device 40.

[0066] Step S02: Take a line image of the printed circuit board to obtain line size information of the printed circuit board. In this embodiment, the automatic optical line measuring device 10 takes a line image of the circuit board body A1 to obtain line size information, which includes, but is not limited to, the line top width, line bottom width, line height, line length, or line cross-sectional area. It should be noted that steps S01 and S02 may be performed simultaneously, or step S02 may be performed before step S01. The order of the two steps is not limited in the present invention.

[0067] Step S03: Finally, obtain electrical characteristic information of the circuit board body based on the line resistance data or line impedance data of the coupon part of the test coupon and the line size information of the circuit board body. In this embodiment, the line characteristic confirmation device 20 adjusts the calibration parameters based on the line resistance data or line impedance data of the coupon part of the test coupon A2, and uses the calibration parameters after the adjustment during the subsequent inspection to generate the line resistance data or line impedance data of the circuit board body A1. Through the above steps, the line resistance data or line impedance data of the circuit board body A1 can be calibrated based on the line resistance data or line impedance data of the coupon part of the test coupon A2, thereby improving the accuracy of subsequent line measurements.

[0068] Hereinafter, another embodiment of the present invention will be described. Referring to FIG. 13 and FIG. 14, a block diagram showing a schematic diagram of a printed circuit board inspection system according to another embodiment of the present invention and a flow chart of a printed circuit board inspection method according to another embodiment of the present invention are shown. As shown in the figures, the main difference between the printed circuit board inspection system 200 of this embodiment and the above-mentioned embodiment is that the present invention uses an automatic optical line measurement device 70 instead of a contact type measurement method to confirm the line reference characteristic information of the test coupon A2, thereby obtaining electrical characteristic information of the printed circuit board based on the line reference characteristic information and the line size information of the printed circuit board body A1. The hardware and software configuration of the automatic optical line measurement device 70 is basically the same as that of the automatic optical line measurement device 10 of the above-mentioned embodiment, so that detailed description of the parts having the same hardware and software configuration will be omitted.

[0069] In this embodiment, the automatic optical line measurement device 70 obtains line size information of the coupon portion of the test coupon A2 by photographing a line image of the test coupon A2, and the line characteristic confirmation device 80 obtains line reference characteristic information of the test coupon A2 from the line size information of the coupon portion.

[0070] In this embodiment, the line reference characteristic information includes the line conductivity and the thickness of the line dielectric layer, and the line characteristic confirmation device 80 obtains the line reference characteristic information through the line size information of the coupon part, the Wadell equation, the IPC-2141 empirical formula, and a TDR impedance measuring device. As a specific method, the automatic optical line measurement device 70 first captures a line image of the test coupon A2 to obtain line size information of the coupon part of the test coupon A2 (step S11). Here, the line size information of the coupon part includes the line width (which may include, but is not limited to, the line top width and the line bottom width), line height, line length, or line cross-sectional area of ​​the test coupon A2.

[0071] Next, the line characteristic checking device 80 obtains the line conductivity and the thickness of the line dielectric layer based on the test coupon A2 (step S12). Specifically, the line characteristic checking device 80 obtains line size information of the coupon portion, and measures the average impedance Z of the microstrip line of the test coupon A2 through a TDR impedance measuring device. 0_mea The line size information and Z of the coupon part can be measured. 0_mea Substituting into the Wadell equation:

number

[0072] Similarly, the average impedance Z 0_mea And substitute the line size information of the coupon part into the following IPC-2141 empirical formula.

number

[0073] In the above formula, Z 0_mea (average impedance), w (microstrip line width), and t (thickness of the metal used in the microstrip line) are all known, and the line conductivity ε rOnly the thickness h of the line dielectric layer has yet to be determined. At this time, the line conductivity ε r and the thickness h of the line dielectric layer is obtained.

[0074] Next, the automatic optical line measuring device 70 photographs the line image of the circuit board body A1 to obtain line size information of the circuit board body A1 (step S13). The line size information includes, but is not limited to, for example, the line top width, the line bottom width, the line height, the line length, or the line cross-sectional area. This step is the same as the method of photographing and obtaining line size information using the automatic optical line measuring device 10 of the above embodiment, so detailed description of the same parts will be omitted.

[0075] Finally, the line impedance information of the circuit board body A1 is obtained based on the line conductivity of the test coupon, the thickness of the line dielectric layer, and the line size information of the circuit board body A1 (step S14). In this step, the line conductivity, the thickness of the line dielectric layer, and the line size information of the circuit board body A1 are all determined, so that the corresponding values ​​can be substituted into the Wadell equation, the IPC-2141 empirical formula, or the Polar estimation software to obtain the line impedance information calibrated according to the test coupon.

[0076] In summary, the present invention obtains resistance data or impedance data of a circuit through a non-contact automatic optical line measurement method, shortens the inspection time of the entire circuit, and further calibrates the data obtained by the automatic optical line measurement through line reference characteristic information obtained by a test coupon (PCB test coupon), making the resistance or impedance data more accurate, thereby improving the inspection efficiency and effect.

[0077] Although the present invention has been described in detail above, what has been described above is only a preferred embodiment of the present invention, and is not limited to the scope of the present invention. Of course, equivalent modifications and adaptations based on the claims of the present invention are included within the scope of protection of the present invention. [Explanation of symbols]

[0078] 100 Printed Circuit Board Inspection System 10 Automatic optical line measuring device 11 Sensing unit 111 Top view image capture device 112 Side-view image capture device 12 light source 13 Image Measurement Module 200 Printed Circuit Board Inspection System 20. Line characteristic verification device 30 Central Control System 40 Contact measuring device 41 Storage device 50 Defect marking device 51 Processors 52 Storage device 60 Manual Inspection Equipment 70 Automatic Optical Line Measuring Device 80 Line characteristic checking device A. Printed circuit board A1 Circuit board body A2 Test Coupon D1 colored area D2 colored area DW Track width L Optical axis direction PI Printed Circuit Board Images SW1 First side wall width SW2 Second side wall width S01~S03 steps S11~S14 steps T Track height T1 Defect Location Module T2 Image Marking Module UW Track top width α Shooting angle

Claims

1. an automatic optical line measuring device for obtaining line size information of a printed circuit board by photographing an image of the line of the printed circuit board; a line characteristic verification device connected to the automatic optical line measurement device to obtain line size information, The line characteristic checking device is a printed circuit board inspection system that obtains electrical characteristic information of the printed circuit board based on line reference characteristic information of a test coupon and line size information of the printed circuit board.

2. 2. The printed circuit board inspection system of claim 1, wherein the automatic optical line measurement device generates calibration parameters based on the line reference characteristic information of the test coupon and the line size information of the printed circuit board, and calibrates the electrical characteristic information of the printed circuit board using the calibration parameters.

3. 3. The printed circuit board inspection system according to claim 2, wherein the line reference characteristic information is line resistance data or line impedance data of the coupon portion of the test coupon.

4. 2. The printed circuit board inspection system of claim 1, wherein the automatic optical line measurement device acquires line size information of the coupon portion of the test coupon by photographing a line image of the test coupon, and the line characteristic confirmation device acquires the line reference characteristic information of the test coupon from the line size information of the coupon portion.

5. 5. The printed circuit board inspection system according to claim 4, wherein the line reference characteristic information is a line conductivity and a line dielectric layer thickness.

6. 6. The printed circuit board inspection system of claim 5, wherein the line characteristic checking device obtains the line reference characteristic information through line size information of the coupon portion, Wadell equation, IPC-2141 empirical formula, and a TDR impedance measuring device.

7. The automatic optical line measuring device includes: a sensing unit for capturing an image of a target area of ​​the printed circuit board to obtain the track image; an image measurement module coupled to the sensing unit and configured to generate the track size information based on the track image; 2. The printed circuit board inspection system of claim 1, comprising:

8. 8. The printed circuit board inspection system of claim 7, wherein the line size information includes a line top width, a line bottom width, a line height, a line length, or a line cross-sectional area.

9. 9. The printed circuit board inspection system according to claim 8, wherein the electrical characteristic information is line resistance data, and the line characteristic confirmation device generates the line resistance data based on the line cross-sectional area and the line length.

10. 9. The printed circuit board inspection system of claim 8, wherein the electrical characteristic information is line impedance data, and the line characteristic verification device generates the line impedance data based on the line upper width, the line lower width, the line height, and the thickness and line conductivity of the line dielectric layer in the target area.

11. 11. The printed circuit board inspection system of claim 10, wherein the thickness of the line dielectric layer and the line conductivity are preset values, or the thickness of the line dielectric layer and the line conductivity are obtained by testing the test coupon.

12. 8. The printed circuit board inspection system of claim 7, wherein the sensing unit includes a top-view image capturing device and at least one side-view image capturing device, the top-view image capturing device being disposed on a top-view direction side of the target area to obtain a top-view image of the track image, and the at least one side-view image capturing device being disposed on a side-view direction side of the target area to obtain a side-view image of the track image.

13. 13. The printed circuit board inspection system of claim 12, wherein an optical axis direction of the at least one side-view image capture device forms a shooting angle with respect to a plane of the printed circuit board, the shooting angle being between 0 degrees and 90 degrees.

14. 7. The printed circuit board inspection system according to claim 1, wherein the line characteristic checking device obtains the electrical characteristic information based on a resistance formula, a Wadell equation, an IPC-2141 empirical formula, or Polar estimation software.

15. obtaining line reference characteristic information based on a test coupon of the printed circuit board; Taking a line image of the printed circuit board to obtain line size information of the printed circuit board; obtaining electrical characteristic information of the printed circuit board based on line reference characteristic information of the test coupon and line size information of the printed circuit board; A method for inspecting a printed circuit board comprising:

16. 16. The printed circuit board inspection method of claim 15, further comprising generating calibration parameters based on the line reference characteristic information of the test coupon and the line size information of the printed circuit board, and calibrating the electrical characteristic information of the printed circuit board using the calibration parameters.

17. 17. The method of claim 16, wherein the line reference characteristic information is line resistance data or line impedance data of a coupon portion of the test coupon.

18. 16. The method for inspecting a printed circuit board according to claim 15, wherein the line reference characteristic information of the test coupon is obtained from line size information of the coupon portion of the test coupon after acquiring line size information of the coupon portion by photographing a line image of the test coupon.

19. The method for inspecting a printed circuit board according to claim 18, wherein the line reference characteristic information is a line conductivity and a line dielectric layer thickness.

20. 20. The method of claim 19, wherein the line reference characteristic information is obtained through line size information of the coupon portion, Wadell equation, IPC-2141 empirical formula, and a TDR impedance measuring instrument.

21. The method of claim 15, wherein the line size information includes a line top width, a line bottom width, a line height, a line length, or a line cross-sectional area.

22. 22. The method of claim 21, wherein the line size information generates line resistance data based on the line cross-sectional area and the line length.

23. 22. The method of claim 21, wherein the line size information generates line impedance data based on the line top width, the line bottom width, the line height, and a thickness and line conductivity of a line dielectric layer of the printed circuit board.

24. 24. The method for inspecting a printed circuit board according to claim 23, wherein the thickness of the line dielectric layer and the line conductivity are preset values, or the thickness of the line dielectric layer and the line conductivity are obtained by testing the test coupon.

25. 16. The method of claim 15, wherein the line size information is obtained from a top-view image and at least one side-view image of the line image of the printed circuit board.

26. 16. The method for testing a printed circuit board according to claim 15, wherein the electrical characteristic information is obtained based on a resistance formula, a Wadell equation, an IPC-2141 empirical formula, or Polar estimation software.

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