Measurement method capable of distinguishing number abnormity of P sheets of circuit board
By adopting the measurement point arrangement method of diffusing center to edge on the circuit board and two-stage alarm logic, it is solved that existing equipment is difficult to distinguish between abnormal number of P pieces and the board thickness does not exceed the range, and improves the accuracy of circuit board thickness monitoring and product yield.
Patent Information
- Application Number
- CN202510282661.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-11
- Publication Date
- 2025-06-27
AI Technical Summary
It is difficult for existing equipment to accurately distinguish the abnormal number of circuit board P sheets and the plate thickness does not exceed the range, resulting in abnormal plate flowing into subsequent processes and affecting product quality.
The measurement point arrangement method is adopted to diffuse the center to the edge, and the thickness of multiple points is measured through a non-contact laser rangefinder, and the first thickness threshold range and the second thickness threshold range are preset, and two-stage alarm trigger logic is established to accurately distinguish the abnormal number of P pieces.
It improves the accuracy of circuit board thickness monitoring, effectively avoids abnormal board flow in subsequent processes, improves product yield, and facilitates technicians to distinguish and analyze adverse situations.
Smart Images
Figure CN120212883A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of circuit boards, and more particularly to a measurement method capable of distinguishing abnormal quantities of P sheets on a circuit board. Background Art
[0002] P sheets (Prepreg), that is, semi-cured sheets, are used to bond different layers of core boards or copper foils together to form a multi-layer structure. After the multi-layer board is laminated, the board thickness needs to be measured for quality control. Currently, a side board thickness measuring machine is commonly used to measure the thickness of the circuit board. The number of P sheets will have a certain impact on the quality of the circuit board. In existing equipment, when the number of P sheets is normal and the board thickness exceeds the range, it can be detected. When the number of P sheets is over-inserted or under-inserted but the board thickness exceeds the range, it can also be detected. However, when the number of P sheets is over-inserted or under-inserted and the board thickness does not exceed the range, such abnormal boards will directly flow out, resulting in affecting product quality and subsequent use. Summary of the Invention
[0003] In view of this, the present invention provides a measurement method capable of distinguishing abnormal quantities of P sheets on a circuit board.
[0004] The object of the present invention is achieved by the following technical solutions: A measurement method capable of distinguishing abnormal quantities of P sheets on a circuit board, comprising: S1. Select measurement points: Select a plurality of measurement points on the surface of the circuit board, and the plurality of measurement points are arranged in a manner of spreading from the center of the circuit board to the edge; S2. Set measurement parameters: Preset a first thickness threshold range and a second thickness threshold range, wherein the first thickness threshold range is the overall thickness tolerance range of the circuit board, and the second thickness threshold range is the average thickness tolerance range of the measurement points in the central area of the circuit board; S3. Measure the board thickness: Use a non-contact laser rangefinder to detect the thickness of each measurement point and generate a plurality of measurement data corresponding to the measurement points; S4. Judge abnormality: When any of the measurement data is not within the first thickness threshold, trigger a first-level alarm; when all the measurement data are within the first thickness threshold but not within the second thickness threshold, trigger a second-level alarm.
[0005] In the measurement method of the above technical solution, the arrangement of measurement points spreads from the center to the edge, covering both the stress concentration area of the circuit board and monitoring the edge thermal radiation effect. Compared with randomly selecting points, the thickness data of the measurement points can cover the thicknesses of all parts of the circuit board, that is, the accuracy of circuit board thickness monitoring can be effectively improved. In addition, by presetting the first thickness threshold range and the second thickness threshold range, a two-level alarm trigger logic is established, which can accurately distinguish the situation where the overall thickness of the circuit board does not meet the requirements when too many or too few P sheets are placed, and the situation where the overall thickness of the circuit board meets the requirements when too many or too few P sheets are placed. Thus, it can not only effectively prevent abnormal circuit boards from flowing into the subsequent process and improve the product yield rate, but also facilitate technicians to distinguish and analyze defective situations, facilitating the improvement of subsequent processes and the monitoring of processes.
[0006] Optionally, in a possible implementation manner, nine measurement points are selected, and the nine measurement points are arranged in a nine-square grid manner, where the middle measurement point is located at the center of the circuit board, and the remaining measurement points are respectively close to the edges of the circuit board.
[0007] In the above technical solution, through the symmetrical layout of the nine-square grid, that is, one center point and eight edge points, while ensuring high-density sampling in the central area of the circuit board, it evenly covers the key positions at the edges. It not only avoids local missed inspections that may be caused by random point layout, but also monitors the process deviation sensitive area through the center point, ensuring that the thickness at the measurement point positions can completely cover all thicknesses of all parts of the circuit board, and further more accurately determining the board thickness range of the circuit board.
[0008] Optionally, in a possible implementation manner, when measuring the board thickness in step S3, a circular measurement area is formed with the measurement point as the center, and three groups of laser rangefinders are used to measure three positions in the measurement area respectively, and the middle value among the nine groups of measured data is selected as the measurement data.
[0009] In the above technical solution, the same measurement point is measured nine times through three groups of laser rangefinders and the three-point measurement method, and then the middle value is selected as the final measurement data, which can effectively eliminate single-point abnormal data caused by surface micro-deformation, local foreign objects or instantaneous environmental interference (such as vibration, temperature drift). This algorithm is similar to the median filtering principle, which can suppress the influence of pulse noise on the measurement result and ensure that the output data is closer to the true thickness value. Compared with single-point measurement, this solution reduces the systematic error caused by surface roughness or slight inclination through the spatial averaging effect.
[0010] Optionally, in a possible implementation manner, the three groups of laser rangefinders are spaced apart in a linear array or a circular array.
[0011] In the above technical solution, the linear array achieves redundant sampling on the same axis through directional arrangement, which can effectively suppress the single-point error caused by local surface deformation or foreign object interference; the circular array can capture the thickness changes in different directions through multi-angle coverage, reducing the risk of measurement blind spots. Both can effectively reduce the interference of external factors, thereby improving the accuracy of printed circuit board thickness measurement.
[0012] Optionally, in a possible implementation manner, the setting step of the second thickness threshold range is as follows: S2.1. Randomly select more than five printed circuit boards and measure the thickness at their central positions respectively, and take the average value; S2.2. Determine the corresponding P-chip tolerance according to the type of P-chip in the printed circuit board: S3.3. Determine the second thickness threshold range based on the average value obtained in step S2.1 and the P-chip tolerance obtained in step S2.2.
[0013] In the above technical solution, by randomly selecting more than five printed circuit boards to measure the central thickness and taking the average value, the single-sample deviation is effectively eliminated, and a dynamic benchmark conforming to the actual production state is established. This method avoids the problem of the disconnection between the traditional fixed threshold and the current process parameters and can adapt to the thickness fluctuations of different batches of materials. In addition, by combining the P-chip tolerance parameters corresponding to the P-chip type for threshold adjustment, the dual constraints of material characteristics and process standards can be achieved.
[0014] Optionally, in a possible implementation manner, in step S2.2, when there are multiple different types of P-chips in the printed circuit board, the P-chip tolerance corresponds to the thinnest one of them.
[0015] In the above technical solution, the superposition of the thickness tolerances of different P-chips may cause the overall thickness fluctuation of the printed circuit board to exceed the limit. Selecting the lowest thickness tolerance as the unified standard can eliminate the tolerance chain amplification effect when combining multiple types of materials.
[0016] Optionally, in a possible implementation manner, the P-chip tolerance is ±1.6mil - ±7.0mil.
[0017] In the above technical solution, the P-chip tolerance range covers common P-chip types in printed circuit board production. For example, the P-chip tolerance of 106P-chip is ±1.6mil, and the P-chip tolerance of 7630P-chip is ±7.0mil. That is, by covering the wide tolerance band from ±1.6mil to ±7.0mil, the manufacturing deviations of different types of P-chips can be compatible.
[0018] Optionally, in a possible implementation manner, in step S4, when the first-level alarm is triggered, the corresponding circuit board is placed in the first NG area through the board receiving machine; when the second-level alarm is triggered, the corresponding circuit board is placed in the second NG area through the board receiving machine.
[0019] In the above technical solution, by distinguishing the first-level and second-level alarm thresholds, the dynamic grading determination of the circuit board quality problems is realized. The first NG area is used to store the circuit boards with unqualified overall thickness when there are too many or too few P pieces placed, and the second NG area is used to store the circuit boards with qualified overall thickness when there are too many or too few P pieces placed. This classification management mode significantly improves the processing efficiency of defective products and reduces the secondary processing cost.
[0020] Optionally, in a possible implementation manner, multiple pieces of the measurement data are simultaneously displayed on the same screen through the display.
[0021] In the above technical solution, by integrating multi-source measurement data on a unified interface, the panoramic visualization monitoring of the measurement parameters is realized. The operator can synchronously obtain multi-dimensional data without switching the screen, which significantly improves the abnormal detection response speed and the timeliness of process adjustment. Description of the Drawings
[0022] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0023] Figure 1 It is a schematic flowchart of an embodiment.
[0024] Figure 2 It is a schematic diagram of the distribution of measurement points and the heating rate of different areas during the pressing of the circuit board in an embodiment. Detailed Embodiments
[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.
[0026] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0027] Please refer to Figure 1 This embodiment provides a measurement method that can distinguish the abnormal number of P chips on a circuit board, including: S1. Select measurement points: select multiple measurement points on the surface of the circuit board, and the multiple measurement points are arranged in a manner of spreading from the center to the edge of the circuit board; S2, measurement parameter setting: preset a first thickness threshold range and a second thickness threshold range, wherein the first thickness threshold range is the overall thickness tolerance range of the circuit board, and the second thickness threshold range is the average thickness tolerance range of the measurement point in the center area of the circuit board; S3. Plate thickness measurement: Use a non-contact laser rangefinder to measure the thickness of each measuring point and generate multiple measurement data of the corresponding measuring points; S4. Determine abnormality: When any measurement data is not within the first thickness threshold, a first-level alarm is triggered; when all measurement data are within the first thickness threshold but not within the second thickness threshold, a second-level alarm is triggered.
[0028] The measurement method of this embodiment adopts a measurement point arrangement method that spreads from the center to the edge, which not only covers the stress concentration area of the circuit board, but also monitors the edge thermal radiation effect. Compared with random point selection, the data of the thickness of the measurement point can cover the thickness of each part of the circuit board, that is, it can effectively improve the accuracy of circuit board thickness monitoring. In addition, by presetting the first thickness threshold range and the second thickness threshold range, a two-level alarm trigger logic is established, which can accurately distinguish the situation where the overall thickness of the circuit board does not meet the requirements when too many or too few P sheets are placed, and the situation where the overall thickness of the circuit board meets the requirements when too many or too few P sheets are placed, thereby effectively avoiding abnormal circuit boards from flowing into subsequent processes and improving product yields, and also facilitating technicians to distinguish and analyze bad situations, and facilitating subsequent process improvements and process monitoring.
[0029] In this embodiment, nine measuring points are selected and arranged in a nine-square grid, wherein the middle measuring point is located at the center of the circuit board, and the remaining measuring points are close to the edges of the circuit board.
[0030] Through the nine-grid symmetrical layout, i.e. one center point and eight edge points, high-density sampling is ensured in the center area of the circuit board while evenly covering the key edge positions. This not only avoids local missed inspections that may be caused by random point distribution, but also monitors the process deviation sensitive areas through the center point to ensure that the thickness at the measurement point position can completely cover all thicknesses of the circuit board, thereby more accurately determining the thickness range of the circuit board.
[0031] It should be noted that the circuit board needs to be pressed by a press during the manufacturing process, and the heating principle of the press is: the circuit board is heated in the press by heat transfer and heat radiation, among which the middle area of the circuit board is heated by heat transfer, and the edge area of the board is heated by a combination of heat transfer and heat radiation. Therefore, the actual edge of the board is heated quickly, so the P-sheet at the edge of the board heats up quickly, the numerical viscosity of the P-sheet is low, the flow is fast, and the thickness of the dielectric layer is unstable, resulting in a thinner thickness at the edge of the board. The middle position of the circuit board is heated slowly, and the P-sheet in the middle of the board heats up slowly. After the resin of the P-sheet is melted, the viscosity is high, the flow is slow, and the thickness of the dielectric layer is thick and stable. Therefore, this embodiment adopts a method of arranging measurement points in a diffuse manner from the middle to the edge of the board to cover the thinnest and thickest positions of the circuit board, so that all thicknesses of the circuit board can be effectively covered, thereby accurately determining the thickness extremes of the circuit board.
[0032] Please refer to Figure 2 In this embodiment, when measuring the board thickness in step S3, a circular measurement area is formed with the measurement point as the center, three groups of laser rangefinders are used to measure three positions in the measurement area respectively, and the middle value is selected from the nine groups of measured data as the measurement data. The circular measurement area can be set according to the size of the actual circuit board, such as the diameter of the circular area can be set to between one quarter and one fifth of the width of the circuit board.
[0033] This embodiment uses three groups of laser rangefinders for measurement. These three groups of laser rangefinders can be spaced in a predetermined manner, but are all located in a circular measurement area. Each group of laser rangefinders measures three points three times, and nine groups of data are obtained. The middle value is selected as the plate thickness of the measurement point. In addition, one laser rangefinder can also be used for measurement. In this case, the laser rangefinder randomly selects three points in the circular measurement area and measures these three points three times. In this way, nine groups of data can be measured, and the middle value is also selected as the plate thickness of the measurement point.
[0034] In this embodiment, nine measurements are taken on the same measurement point by means of three groups of laser rangefinders and three-point measurement, and then the median value is selected as the final measurement data, which can effectively eliminate single-point abnormal data caused by surface micro-deformation, local foreign objects or instantaneous environmental interference (such as vibration, temperature drift). This algorithm is similar to the median filtering principle, which can suppress the influence of pulse noise on the measurement result and ensure that the output data is closer to the true thickness value. Compared with single-point measurement, this scheme reduces the systematic error caused by surface roughness or slight inclination through the spatial averaging effect.
[0035] It should be noted that the three groups of laser rangefinders are distributed at intervals in a linear array or a circular array. The linear array realizes redundant sampling on the same axis through directional arrangement, which can effectively suppress single-point errors caused by local surface deformation or foreign object interference; the circular array can capture thickness changes in different directions through multi-angle coverage, reducing the risk of measurement blind spots. Both can effectively reduce the interference of external factors, thereby improving the accuracy of PCB thickness measurement.
[0036] In this embodiment, the steps for setting the second thickness threshold range are as follows: S2.1. Randomly select more than five PCBs and measure the thickness at their center positions respectively, and take the average value; S2.2. Determine the corresponding P-chip tolerance according to the type of P-chip in the PCB: S3.3. Determine the second thickness threshold range based on the average value obtained in step S2.1 and the P-chip tolerance obtained in step S2.2.
[0037] By randomly selecting more than five PCBs to measure the center thickness and taking the average value, the single-sample deviation is effectively eliminated, and a dynamic benchmark conforming to the actual production status is established. This method avoids the problem that the traditional fixed threshold is out of touch with the current process parameters and can adapt to the thickness fluctuations of different batches of materials. In addition, by combining the P-chip tolerance parameters corresponding to the P-chip type for threshold adjustment, dual constraints of material characteristics and process standards can be achieved.
[0038] In addition, in step S2.2, when there are multiple different types of P-chips in the PCB, the P-chip tolerance corresponds to the thinnest one of them. The superposition of the thickness tolerances of different P-chips may cause the overall thickness fluctuation of the PCB to exceed the limit. Selecting the lowest thickness tolerance as the unified standard can eliminate the tolerance chain amplification effect when multiple types of materials are combined.
[0039] The tolerance of the P-sheet in this embodiment is ±1.6 mil - ±7.0 mil. The P-sheet tolerance range covers common P-sheet types in printed circuit board production. For example, the P-sheet tolerance of the 106P-sheet is ±1.6 mil, and the P-sheet tolerance of the 7630P-sheet is ±7.0 mil. That is, by covering the broad tolerance band from ±1.6 mil to ±7.0 mil, the manufacturing deviations of different types of P-sheets can be accommodated. For details, refer to Table 1: Corresponding P-sheet tolerances for different types of P-sheets.
[0040]
[0041] In step S4 of this embodiment, when the first-level alarm is triggered, the corresponding printed circuit board is placed in the first NG area through the board collector; when the second-level alarm is triggered, the corresponding printed circuit board is placed in the second NG area through the board collector.
[0042] By distinguishing the first-level and second-level alarm thresholds, dynamic classification determination of the quality problems of printed circuit boards is realized. The first NG area is used to store printed circuit boards with unqualified overall thickness when there are too many or too few P-sheets placed. The second NG area is used to store printed circuit boards with qualified overall thickness when there are too many or too few P-sheets placed. This classification management mode significantly improves the processing efficiency of defective products and reduces the secondary processing cost.
[0043] In addition, multiple measurement data are simultaneously displayed on the same screen through the display. By integrating multi-source measurement data on a unified interface, panoramic visualization monitoring of measurement parameters is realized. Operators can synchronously obtain multi-dimensional data without switching screens, significantly improving the response speed of anomaly detection and the timeliness of process adjustment.
[0044] Next, this embodiment will be described in detail through specific examples.
[0045] Taking a certain type of printed circuit board as an example, the overall board thickness range of this printed circuit board after lamination is 29.21 - 36.04 mil. That is, this range is the first thickness threshold range, and this range is the value obtained by measuring the normal board thickness during the processing and production process. Different printed circuit boards have different values.
[0046] Then, determine the second thickness threshold range: Randomly select 5 normal boards and measure the average thickness of the measurement points in the central area of the 5 printed circuit boards. For example, after measurement, the average thickness of the measurement points in the central area of the 5 printed circuit boards is 33.0 mil. At this time, determine the P-sheet tolerance according to Table 1. If the 1080P-sheet is selected for this type of printed circuit board, then determine the second thickness threshold range as 33.0 ± 2.0 mil.
[0047] Subsequently, when measuring the circuit board, if any one of the 9 measurement data points exceeds 29.21 - 36.04 mil, an alarm NG is given; when any one of the 9 measurement data points does not exceed 29.21 - 36.04 mil but exceeds 33.0 ± 2.0 mil, there is overloading or underloading of P sheets, and an alarm NG is also given. The two alarm methods can be distinguished, for example, by the number of beeps to calibrate the alarms for two different situations.
[0048] After using the above method parameter settings and measurement methods, after testing the test boards with 1 extra 1080P sheet and 1 less 1080P sheet, and verifying and confirming through the forming and thickness measurement machine interception after pressing the board, the current process of board thickness control by the forming and thickness measurement machine after pressing the board can meet 100% interception and detection of problem boards with overloaded / underloaded P sheets and completely separate normal boards from problem boards.
[0049] Specifically, in the actual production process, 7 circuit board samples with 1 extra P sheet and 7 circuit board samples with 1 less P sheet are simulated, and the board thickness at the same position is measured with a side board thickness measurement machine. The setting conditions of the board thickness measurement machine are as follows: the first thickness threshold range is set to 29.21 - 36.04 mil, and the second thickness threshold range is set to 33.0 ± 2.0 mil. At this time, 286 circuit boards are taken, and the circuit boards with extra P sheets and less P sheets are marked and randomly inserted into the normal circuit boards and passed through the automatic board thickness measurement machine. All 14 abnormal boards can be accurately identified, and the specific data is shown in Table 2: Measurement data table of abnormal boards.
[0050]
[0051] In the description of the present invention, it should be understood that terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.
[0052] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.
[0053] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A measurement method capable of distinguishing abnormal number of P chips on a circuit board, characterized in that: include: S1. Selecting measurement points: selecting a plurality of measurement points on the surface of the circuit board, wherein the plurality of measurement points are arranged in a manner of spreading from the center to the edge of the circuit board; S2, measurement parameter setting: presetting a first thickness threshold range and a second thickness threshold range, wherein the first thickness threshold range is the overall thickness tolerance range of the circuit board, and the second thickness threshold range is the average thickness tolerance range of the measurement point in the center area of the circuit board; S3. Plate thickness measurement: using a non-contact laser rangefinder to measure the thickness of each measuring point and generate a plurality of measurement data corresponding to the measuring point; S4. Determine abnormality: When any measurement data is not within the first thickness threshold, a first-level alarm is triggered; when all measurement data are within the first thickness threshold but not within the second thickness threshold, a second-level alarm is triggered.
2. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 1, characterized in that: Nine measuring points are selected and arranged in a nine-square grid, wherein the middle measuring point is located at the center of the circuit board, and the remaining measuring points are close to the edges of the circuit board.
3. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 1, characterized in that: When measuring the plate thickness in step S3, a circular measuring area is formed with the measuring point as the center, three groups of laser rangefinders are used to measure three positions in the measuring area respectively, and the middle value is selected from the nine groups of measured data as the measurement data.
4. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 3, characterized in that: The three groups of laser rangefinders are distributed in a linear array or a circular array at intervals.
5. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 1, characterized in that: The steps for setting the second thickness threshold range are: S2.
1. Randomly select five or more circuit boards and measure the thickness at their center positions respectively, and take the average value; S2.
2. Determine the corresponding P chip tolerance according to the P chip type in the circuit board: S3.
3. Determine the second thickness threshold range according to the average value obtained in step S2.1 and the P sheet tolerance obtained in step S2.
2.
6. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 5, characterized in that: In step S2.2, when there are multiple different types of P sheets in the circuit board, the P sheet tolerance corresponds to the thinnest P sheet among them.
7. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 5 or 6, characterized in that: The P sheet tolerance is ±1.6mil-±7.0mil.
8. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 1, characterized in that: In the step S4, when the first level alarm is triggered, the corresponding circuit board is placed in the first NG area through the board collector; when the second level alarm is triggered, the corresponding circuit board is placed in the second NG area through the board collector.
9. The measurement method capable of distinguishing abnormal number of P chips on a circuit board according to claim 1, characterized in that: The plurality of measurement data are displayed simultaneously on the same screen through the display.