A polyimide film thickness measurement method and system

Abstract

The present invention relates to the technical field of thickness measurement, and in particular to a method and system for measuring the thickness of a polyimide film, the method comprising: firstly using a laser thickness gauge to measure the initial thickness of a plurality of measuring points of a polyimide film; then determining the roughness of the surface of the polyimide film according to the initial thickness of each measuring point; when the roughness is greater than a first threshold, determining the laser rotation angle of the laser thickness gauge according to the roughness; then using the laser thickness gauge to measure the true thickness of each measuring point of the polyimide film based on the laser rotation angle; and determining the degree of uneven thickness defects of the polyimide film according to the true thickness of each measuring point; and finally evaluating the thickness quality of the polyimide film using the degree of uneven thickness defects. The technical solution provided by the present invention improves the measurement accuracy of the thickness of the polyimide film.

Description

Technical Field

[0001] The present invention relates to the technical field of thickness measurement, and in particular to a method and system for measuring the thickness of a polyimide film. Background Art

[0002] Polyimide film is a high-performance plastic film. It is widely used in electronic insulation materials, aerospace thermal insulation materials, display screens, etc. due to its excellent heat resistance, electrical insulation and chemical stability. Among them, the uniformity of film thickness has a great influence on its performance and stability during application. Therefore, accurate measurement of film thickness is crucial to ensure product quality.

[0003] In some scenarios, a laser thickness gauge is often used to measure the thickness of a polyimide film. The thickness of the polyimide film is measured based on the intensity of the laser emitted by the laser thickness gauge and the intensity of the reflection of the laser on the polyimide film. However, in some scenarios, in order to increase the surface adhesion and heat dissipation of the polyimide film, the surface of the polyimide film needs to have a relatively rough texture. When the surface texture of the polyimide film is rough, the laser will be scattered on the surface of the polyimide film, and the measurement accuracy of the polyimide film thickness is low, resulting in the measured thickness of the polyimide film being unable to reflect the actual film thickness, making it difficult to evaluate the thickness quality level of the polyimide film. Summary of the invention

[0004] In order to solve the technical problem of low measurement accuracy of polyimide film thickness, the object of the present invention is to provide a polyimide film thickness measurement method and system, and the technical solution adopted is as follows:

[0005] In a first aspect, an embodiment of the present invention provides a method for measuring the thickness of a polyimide film, comprising: using a laser thickness gauge to measure the initial thickness of multiple measurement points of the polyimide film, the laser thickness gauge emitting laser at an initial emission angle to measure the initial thickness of each measurement point; determining the roughness of the surface of the polyimide film according to the initial thickness of each measurement point; when the roughness is greater than or equal to a first threshold, determining a laser rotation angle of the laser thickness gauge according to the roughness, the laser rotation angle being an angle at which the laser emitted by the laser thickness gauge rotates relative to the initial emission angle; using the laser thickness gauge to measure the true thickness of each measurement point of the polyimide film based on the laser rotation angle; determining the degree of thickness unevenness defects of the polyimide film according to the true thickness of each measurement point; and evaluating the thickness quality of the polyimide film using the degree of thickness unevenness defects.

[0006] Optionally, determining the roughness of the polyimide film surface based on the initial thickness of each measuring point includes: clustering the initial thickness of each measuring point to obtain multiple clusters; calculating the standard deviation of the initial thickness within each cluster; and determining the roughness of the polyimide film surface based on a first number of clusters, a second number of measuring points included in each cluster, the standard deviation corresponding to each cluster, and a third number of all measuring points.

[0007] Optionally, determining the laser rotation angle of the laser thickness gauge according to the roughness includes: acquiring an initial rotation angle of the laser thickness gauge; and determining the product of the roughness and the initial rotation angle as the laser rotation angle of the laser thickness gauge.

[0008] Optionally, using a laser thickness gauge to measure the true thickness of each measuring point of the polyimide film based on the laser rotation angle includes: controlling the laser emission port of the laser thickness gauge to rotate the laser rotation angle in multiple directions from the measuring point where the initial emission angle is located to obtain the laser emission angle of the laser thickness gauge; using the laser thickness gauge to measure the thickness of each measuring point at each laser emission angle based on the laser emission angle; determining the target roughness of the polyimide film surface at each laser emission angle based on the thickness of each measuring point at each laser emission angle; selecting the minimum value from each target roughness, and determining the thickness of each measuring point at the laser emission angle corresponding to the minimum value as the true thickness.

[0009] Optionally, determining the degree of uneven thickness defect of the polyimide film based on the true thickness of each measuring point includes: determining a texture window of each measuring point with each measuring point as the center, the texture window including the central measuring point and the measuring points around the center; selecting other measuring points that are consistent with the true thickness of the current measuring point; determining the possibility that the true thickness of the current measuring point belongs to the standard thickness based on the texture window of the current measuring point and the texture windows of the other measuring points; when the possibility is less than a second threshold, determining that the current measuring point has an uneven thickness defect, and when the possibility is not less than the second threshold, determining that the current measuring point does not have an uneven thickness defect; determining the degree of uneven thickness defect of the polyimide film based on the true thickness of the measuring points in the polyimide film that do not have an uneven thickness defect and the true thickness of the measuring points that have an uneven thickness defect.

[0010] Optionally, determining the possibility that the true thickness of the current measurement point belongs to the standard thickness based on the texture window of the current measurement point and the texture windows of other measurement points includes: determining the texture similarity between the current measurement point and the other measurement points based on the true thickness of each measurement point in the texture window of the current measurement point, the true thickness of each measurement point in the texture windows of other measurement points and the distance between each measurement point in the texture window of the current measurement point and the center measurement point, the texture similarity characterizing the degree of similarity between the film thickness distribution of the current measurement point and the film thickness distribution of the other measurement points; determining the possibility that the true thickness of the current measurement point belongs to the standard thickness based on the texture similarity.

[0011] Optionally, determining the degree of uneven thickness defects in the polyimide film based on the true thickness of the measurement points in the polyimide film where there is no uneven thickness defect and the true thickness of the measurement points where there is uneven thickness defect includes: determining the average thickness of the true thicknesses of the measurement points in the polyimide film where there is no uneven thickness defect; and determining the degree of uneven thickness defects in the polyimide film based on the average thickness and the true thickness of the measurement points where there is uneven thickness defect.

[0012] Optionally, determining the degree of uneven thickness defects of the polyimide film based on the average thickness and the true thickness of the measurement points where the uneven thickness defects exist includes: calculating the absolute value of the difference between the true thickness of each measurement point where the uneven thickness defects exist and the average thickness; superimposing and normalizing the absolute values ​​to obtain the degree of uneven thickness defects of the polyimide film.

[0013] Optionally, evaluating the thickness quality of the polyimide film using the degree of thickness unevenness defects includes: when the degree of thickness unevenness defects is less than or equal to a third threshold, determining that the thickness quality of the polyimide film is qualified; when the degree of thickness unevenness defects is greater than the third threshold, determining that the thickness quality of the polyimide film is unqualified.

[0014] In a second aspect, an embodiment of the present invention provides a polyimide film thickness measurement system, which includes: a processor and a memory; wherein the memory is used to store a computer program that can be run on the processor; the processor is used to execute the program stored in the memory to implement the steps of the polyimide film thickness measurement method mentioned in the first aspect.

[0015] The present invention has the following beneficial effects: firstly, the initial thickness of a plurality of measuring points of a polyimide film is measured by using a laser thickness gauge, the laser thickness gauge emits laser at an initial emission angle to measure the initial thickness of each of the measuring points; then, the roughness of the surface of the polyimide film is determined according to the initial thickness of each of the measuring points; when the roughness is greater than a first threshold, the laser rotation angle of the laser thickness gauge is determined according to the roughness, the laser rotation angle being the angle at which the laser emitted by the laser thickness gauge rotates relative to the initial emission angle; then, the laser thickness gauge is used to measure the true thickness of each of the measuring points of the polyimide film based on the laser rotation angle; and the degree of uneven thickness defects of the polyimide film is determined according to the true thickness of each of the measuring points; finally, the thickness quality of the polyimide film is evaluated using the degree of uneven thickness defects.

[0016] Thus, after the present invention uses a laser thickness gauge to measure the initial thickness of multiple measurement points of a polyimide film, the roughness of the surface of the polyimide film is determined based on the obtained initial thickness, and the laser emission angle of the laser thickness gauge is adjusted according to the roughness, thereby obtaining a more accurate true thickness of the polyimide film, thereby effectively reducing the influence of the scattering of the laser by the rough surface of the polyimide film on the thickness measurement result of the polyimide film, and improving the measurement accuracy of the thickness of the polyimide film. Furthermore, the uneven thickness defect of the polyimide film is identified by using a more accurate thickness of the polyimide film, which improves the recognition accuracy of the uneven thickness defect of the polyimide film, thereby improving the accuracy of the evaluation result of the thickness quality level of the polyimide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a polyimide film thickness measurement method provided by one embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the relationship between the laser emission direction and the reflection direction of a laser thickness gauge provided by one embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a texture window provided by an embodiment of the present invention;

[0021] Figure 4A schematic diagram of measurement points with similar texture features provided by an embodiment of the present invention;

[0022] Figure 5 A schematic structural diagram of a polyimide film thickness measurement system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a polyimide film thickness measurement method and system proposed by the present invention, its specific implementation, structure, characteristics and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0025] The specific scheme of a polyimide film thickness measurement method and system provided by the present invention is described in detail below with reference to the accompanying drawings.

[0026] Embodiment 1:

[0027] See also Figure 1 , which shows a flow chart of a polyimide film thickness measurement method provided by an embodiment of the present invention, comprising:

[0028] S101, using a laser thickness gauge to measure the initial thickness of a polyimide film at a plurality of measurement points.

[0029] The laser thickness gauge emits laser at an initial emission angle to measure the initial thickness of each measuring point.

[0030] Specifically, when using a laser thickness gauge to measure the thickness of a polyimide film, the polyimide film is laid flat on a measuring platform, and the plane of the measuring platform is parallel to the horizontal plane. The laser emitted from the laser emission port of the laser thickness gauge is perpendicular to the surface of the measuring platform, with the surface of the measuring platform as the X-axis, and the axis perpendicular to the surface of the measuring platform as the Y-axis. The angle between the laser emitted by the laser thickness gauge and the Y-axis is the emission angle of the laser thickness gauge. In the embodiment of the present invention, the laser emitted by the laser thickness gauge is perpendicular to the X-axis, that is, the laser emitted by the laser thickness gauge is parallel to the Y-axis, and the angle between the laser emitted by the laser thickness gauge and the Y-axis is 0, then the initial emission angle in the embodiment of the present invention can be 0 degrees. It is worth noting that the initial emission angle of the laser thickness gauge can be determined according to actual conditions, and the embodiment of the present invention is not limited to the case where the initial emission angle is 0 degrees.

[0031] Furthermore, a predetermined distance is set as a measurement point on the surface of the polyimide film, and the predetermined distance can be determined according to actual conditions, such as a value of 1 mm.

[0032] Furthermore, the specific measurement principle of measuring the thickness of the polyimide film using a laser thickness gauge can be found in the prior art, and the embodiments of the present invention will not be described in detail herein.

[0033] S102, determining the roughness of the surface of the polyimide film according to the initial thickness of each measuring point.

[0034] Specifically, the thickness consistency of different locations of a smooth polyimide film is high, while the thickness of a rough polyimide film at different locations varies greatly due to the surface texture causing light to dissipate heat. Therefore, the roughness of the polyimide film surface can be determined based on the initial thickness of each measurement point.

[0035] When determining the roughness of the surface of a polyimide film, as an optional embodiment of the present invention, the initial thickness of each measuring point is first clustered to obtain multiple clusters; then the standard deviation of the initial thickness within each cluster is calculated; finally, the roughness of the surface of the polyimide film is determined based on a first number of clusters, a second number of measuring points contained in each cluster, the standard deviation corresponding to each cluster, and a third number of all measuring points.

[0036] Specifically, when clustering the initial thickness of each measuring point, first draw a scatter plot for each measuring point according to its position and initial thickness. The three-dimensional coordinates of each point in the scatter plot represent the spatial position of the measuring point, and the value on the Z axis in the scatter plot represents the initial thickness of the measuring point. Then, the k-means clustering method is used to cluster the initial thickness of the measuring points in the scatter plot to obtain multiple clusters, each cluster containing the initial thickness of multiple measuring points and the consistency of the initial thickness of the measuring points in each cluster is high. Considering that the polyimide film may have uneven thickness, the number of clusters k in the embodiment of the present invention is set to 4. Of course, according to actual conditions, the number of clusters k can also be set to other values, which are not limited in the embodiment of the present invention. It is worth noting that the specific implementation process of clustering using the k-means clustering method can refer to the prior art, and the embodiment of the present invention will not be repeated here.

[0037] Furthermore, the process of calculating the standard deviation of the initial thickness within the cluster is as follows: first, the average value of the initial thickness within the cluster is calculated, and then the deviation of the initial thickness of each measurement point in the cluster from the average value is calculated, and then the square of each deviation is calculated to obtain the square difference, and then the average value of each square difference is calculated to obtain the variance, and finally the positive square root of the variance is taken to obtain the standard deviation.

[0038] Furthermore, the roughness of the polyimide film surface can be calculated using the following formula:

[0039]

[0040] In the above formula, Indicates the roughness of the polyimide film surface. Indicates the number of clusters (first quantity). Indicates The number of measurement points contained in each cluster (the second number). Indicates the total quantity of all measurement points (third quantity). Indicates The standard deviation of the initial thickness of the measured points in the cluster. The larger the standard deviation of the initial thickness, the greater the difference in initial thickness among the measurement points in the cluster. The more measurement points each cluster contains, the greater the degree to which the cluster represents the roughness of the polyimide film surface. Represents the normalization function, which is used to The results are normalized so that their values ​​fall within the range of 0 to 1.

[0041] S103: When the roughness is greater than or equal to the first threshold, determine a laser rotation angle of the laser thickness gauge according to the roughness.

[0042] The laser rotation angle is the angle at which the laser emitted by the laser thickness gauge rotates relative to the initial emission angle.

[0043] Specifically, after the roughness is calculated through the above embodiment, it is compared with the first threshold value to determine whether the surface of the polyimide film is rough. Among them, the first threshold value can be determined according to the actual scenario, and the value in the embodiment of the present invention is 0.3. If the roughness is less than 0.3, it is considered that the surface of the polyimide film is relatively smooth, and the measured initial thickness can be used as the true thickness of the polyimide film. If the roughness is greater than or equal to 0.3, it is considered that the surface of the polyimide film is relatively rough, and it is necessary to adjust the angle of the laser emission of the laser thickness gauge to obtain the thickness with the least effect of laser scattering as the true thickness of the polyimide film. The following is combined with Figure 2 The laser scattering is described below. Figure 2 A schematic diagram of the relationship between the laser emission direction and the reflection direction of a laser thickness gauge provided by an embodiment of the present invention is shown in FIG. Figure 2As shown in the figure, when the laser emission direction of the laser thickness gauge is more perpendicular to the surface of the polyimide film, the angle between the laser reflection direction and the laser emission direction is smaller, the effect on the thickness measurement result of the polyimide film is smaller, and the roughness of the surface of the polyimide film is smaller. Therefore, the laser emission angle of the laser thickness gauge can be adjusted based on the roughness of the surface of the polyimide film.

[0044] In determining the laser rotation angle of the laser thickness gauge, as an optional embodiment of the present invention, the initial rotation angle of the laser thickness gauge is first obtained; then the product of the roughness and the initial rotation angle is determined as the laser rotation angle of the laser thickness gauge.

[0045] Specifically, the laser rotation angle of the laser thickness gauge can be calculated using the following formula:

[0046]

[0047] In the above formula, Indicates the laser rotation angle, Indicates the roughness of the polyimide film surface. Indicates the initial rotation angle of the laser thickness gauge. The initial rotation angle may be preset and may be set according to the actual scenario. .

[0048] S104, using a laser thickness gauge to measure the true thickness of each measuring point of the polyimide film based on the laser rotation angle.

[0049] Specifically, after obtaining the laser rotation angle of the laser thickness gauge, the laser rotation angle is rotated based on the initial emission angle of the laser thickness gauge. For example, the laser of the laser thickness gauge is rotated left and right based on the initial emission angle. The laser thickness gauge sequentially emits laser light to each measuring point of the polyimide film at the laser emission angle obtained after rotation, thereby measuring the true thickness of each measuring point of the polyimide film.

[0050] Furthermore, when measuring the true thickness of each measuring point of the polyimide film based on the laser rotation angle, as an optional embodiment of the present invention, the laser emission port of the laser thickness gauge is first controlled to rotate the laser rotation angle in multiple directions from the measuring point where the initial emission angle is located, so as to obtain the laser emission angle of the laser thickness gauge; then, the laser thickness gauge is used to measure the thickness of each measuring point at each laser emission angle based on the laser emission angle; then, the target roughness of the polyimide film surface at each laser emission angle is determined according to the thickness of each measuring point at each laser emission angle; finally, the minimum value is selected from each target roughness, and the thickness of each measuring point at the laser emission angle corresponding to the minimum value is determined as the true thickness.

[0051] Specifically, the multiple directions can be left and right directions based on the initial emission angle, such as rotating the laser of the laser thickness gauge to the left and right based on the initial emission angle. , the laser thickness gauge sequentially emits lasers to each measuring point of the polyimide film at the laser emission angle obtained after the rotation, and then uses the laser thickness gauge to measure the thickness of each measuring point at each laser emission angle based on the laser emission angle, and then uses the roughness calculation formula recorded in the embodiment of the present invention to recalculate the roughness of the polyimide film surface at the laser emission angle after rotating to the left and right by a certain angle based on the thickness, and selects the direction with smaller roughness as the direction closer to the optimal emission angle, that is, the measured thickness is closer to the true value. Repeat the above process until the roughness of the obtained polyimide film surface no longer decreases, and the thickness measured at the laser emission angle corresponding to the minimum roughness is used as the true thickness of the polyimide film.

[0052] S105, determining the degree of uneven thickness defect of the polyimide film according to the true thickness of each measuring point.

[0053] Specifically, for a polyimide film that does not have uneven thickness defects and has a rough surface, the thickness distribution of different areas on the surface of the polyimide film should be similar, that is, the texture characteristics of different areas on the surface of the polyimide film are normal and similar. If there is an uneven thickness defect on the surface of the polyimide film, since the thickness of the location where the uneven thickness defect exists is relatively random, the thickness distribution at the defect location will not meet the normal texture characteristics, and will be greatly different from the texture characteristics of the location where there is no defect. Therefore, the uneven thickness defect of the polyimide film can be identified based on the distribution of the true thickness of the measurement point.

[0054] When determining the degree of uneven thickness defect of a polyimide film, as an optional embodiment of the present invention, firstly, a texture window of each measuring point is determined with each measuring point as the center, and the texture window includes the measuring point at the center and the measuring points around the center; then, other measuring points that are consistent with the true thickness of the current measuring point are selected; then, based on the texture window of the current measuring point and the texture windows of the other measuring points, the possibility that the true thickness of the current measuring point belongs to the standard thickness is determined; secondly, when the possibility is less than a second threshold, it is determined that the current measuring point has an uneven thickness defect, and when the possibility is not less than the second threshold, it is determined that the current measuring point does not have an uneven thickness defect; finally, based on the true thickness of the measuring points in the polyimide film that do not have an uneven thickness defect and the true thickness of the measuring points that have an uneven thickness defect, the degree of uneven thickness defect of the polyimide film is determined.

[0055] Specifically, a window for analyzing the texture features of each measurement point is first set. The side length of the window can be determined according to the actual scene. In the embodiment of the present invention, the side length of the window is set to 5 mm. Figure 3 As shown, Figure 3 A schematic diagram of a texture window provided in an embodiment of the present invention, a certain measuring point 301 is placed at the center of the window, and the texture window contains the real thickness of the certain measuring point placed at the center and the real thickness of the measuring points around the certain measuring point. The distribution of the real thickness of each measuring point in the texture window can be used as the texture feature of the measuring point at the center. Then find other measuring points with the same real thickness as the current measuring point. In the embodiment of the present invention, the measuring points with the same real thickness are used as measuring points with similar texture features, such as Figure 4 As shown, Figure 4 A schematic diagram of measurement points with similar texture features provided by an embodiment of the present invention, Figure 4 The texture features in the middle are in a stripe pattern, and the positions between the stripes have similar texture features. The measurement point 401 and the measurement point 402 are both located between the stripes, so it can be considered that the measurement point 401 and the measurement point 402 have similar texture features.

[0056] Furthermore, the standard thickness refers to the thickness of a polyimide film with a smooth surface, and the possibility that the true thickness of the current measurement point belongs to the standard thickness refers to the possibility that the true thickness of the current measurement point belongs to the standard thickness. When determining the possibility that the true thickness of the current measurement point belongs to the standard thickness, as an optional embodiment of the present invention, firstly, based on the true thickness of each measurement point in the texture window of the current measurement point, the true thickness of each measurement point in the texture windows of other measurement points, and the distance between each measurement point in the texture window of the current measurement point and the central measurement point, the texture similarity between the current measurement point and the other measurement points is determined, and the texture similarity characterizes the similarity between the film thickness distribution of the current measurement point and the film thickness distribution of the other measurement points; then, based on the texture similarity, the possibility that the true thickness of the current measurement point belongs to the standard thickness is determined.

[0057] Specifically, the texture similarity between the current measurement point and other measurement points can be calculated using the following formula:

[0058]

[0059] In the above formula, represents the texture similarity between the i-th measurement point and the j-th measurement point, j represents the j-th measurement point whose true thickness is consistent with the true thickness of the j-th measurement point among the other measurement points, Indicates the total number of measurement points contained in the texture window corresponding to the i-th measurement point, represents the true thickness of the u-th measurement point in the texture window corresponding to the i-th measurement point, represents the true thickness of the u-th measurement point in the texture window corresponding to the j-th measurement point, represents the distance between the uth measurement point and the center point (the ith measurement point) in the texture window corresponding to the i-th measurement point, The closer the distance, the higher the degree of defect manifestation of the center point. The smaller the difference in the true thickness of each measuring point in the texture window representing different measuring points, The larger the value is, the more similar the film thickness distribution in the texture window corresponding to the two measurement points is, that is, the more similar the texture between the current measurement point and the other measurement points is.

[0060] Furthermore, the possibility that the actual thickness of the current measurement point belongs to the standard thickness can be calculated using the following formula:

[0061]

[0062] In the above formula, represents the possibility that the true thickness of the i-th measurement point belongs to the standard thickness, represents the number of measurement points that are consistent with the true thickness of the i-th measurement point, represents the texture similarity between the i-th measurement point and the j-th measurement point, Represents the normalization function, which is used to The values ​​are normalized so that their values ​​are distributed in the range of 0 to 1.

[0063] Furthermore, after calculating the possibility that the actual thickness of the current measurement point belongs to the standard thickness through the above embodiment, if the possibility is less than the second threshold, it means that the possibility that the actual thickness of the current measurement point belongs to the standard thickness is small, and it is determined that the current measurement point has a thickness unevenness defect. If the possibility is not less than the second threshold, it means that the possibility that the actual thickness of the current measurement point belongs to the standard thickness is large, and it is determined that the current measurement point does not have a thickness unevenness defect. The value of the second threshold can be determined according to the actual scenario. In the embodiment of the present invention, the value is 0.4. When , it is considered that there is a thickness unevenness defect at the current measuring point.

[0064] Furthermore, when determining the degree of uneven thickness defects in a polyimide film, as an optional embodiment of the present invention, the average thickness of the true thicknesses of the measurement points in the polyimide film where there are no uneven thickness defects is first determined; then the degree of uneven thickness defects in the polyimide film is determined based on the average thickness and the true thicknesses of the measurement points where there are uneven thickness defects.

[0065] Specifically, the true thickness of all measurement points without uneven thickness defects is first superimposed, and then compared with the number of all measurement points without uneven thickness defects to obtain the average thickness. Then, the absolute value of the difference between the true thickness of each measurement point with uneven thickness defects and the average thickness is calculated; then, the absolute values ​​are superimposed and normalized to obtain the uneven thickness defect degree of the polyimide film.

[0066] Among them, the thickness unevenness defect degree of the polyimide film can be calculated by the following formula:

[0067]

[0068] In the above formula, Indicates the uneven thickness defect degree of the polyimide film. Indicates the number of measurement points where uneven thickness defects exist, Indicates There are measurement points with uneven thickness defects. Indicates The actual thickness of the measurement point with uneven thickness defect, The average thickness representing the true thickness of the measurement points where there is no thickness unevenness defect in the polyimide film, Represents the normalization function, which is used to Normalize it so that its value is distributed in the range of 0 to 1.

[0069] S106, evaluating the thickness quality of the polyimide film by using the degree of thickness non-uniformity defects.

[0070] Specifically, after calculating the thickness unevenness defect degree of the polyimide film through the above formula embodiment, when the thickness unevenness defect degree is less than or equal to the third threshold, it is determined that the thickness quality of the polyimide film is qualified. When the thickness unevenness defect degree is greater than the third threshold, it is determined that the thickness quality of the polyimide film is unqualified. Among them, the value of the third threshold can be determined according to the actual scenario. In the embodiment of the present invention, the value is 0.3. When When , it is considered that the thickness of the polyimide film is relatively uniform, that is, the thickness quality of the polyimide film is qualified; when When the thickness of the polyimide film is not uniform, it is considered that the thickness of the polyimide film is not uniform, that is, the thickness quality of the polyimide film is unqualified.

[0071] The embodiment of the present invention uses a laser thickness gauge to measure the initial thickness of multiple measurement points of a polyimide film, and then determines the roughness of the surface of the polyimide film based on the obtained initial thickness, and adjusts the laser emission angle of the laser thickness gauge according to the roughness, so as to obtain a more accurate true thickness of the polyimide film, thereby effectively reducing the influence of the scattering of the laser by the rough surface of the polyimide film on the thickness measurement result of the polyimide film, and improving the measurement accuracy of the thickness of the polyimide film. The uneven thickness defect of the polyimide film is identified by using a more accurate thickness of the polyimide film, and the recognition accuracy of the uneven thickness defect of the polyimide film is improved, thereby improving the accuracy of the evaluation result of the thickness quality level of the polyimide film.

[0072] Embodiment 2:

[0073] Corresponding to the polyimide film thickness measurement method provided in the above embodiment, based on the same technical concept, the embodiment of the present invention further provides a polyimide film thickness measurement system, which is used to execute the above polyimide film thickness measurement method. Figure 5 A schematic diagram of a polyimide film thickness measurement system for implementing various embodiments of the present invention is shown in FIG. Figure 5 The polyimide film thickness measurement system may have relatively large differences due to different configurations or performances, and may include one or more processors 501 and memory 502, the memory 502 is used to store computer programs that can be run on the processor 501, and the processor 501 is used to execute the program stored in the memory 502 to achieve the above Figure 1 The various steps in the method embodiment. The memory 502 may be a temporary storage or a permanent storage. The application stored in the memory 502 may include one or more modules (not shown in the figure), each module may include a series of computer executable instructions in the polyimide film thickness measurement system.

[0074] Furthermore, the processor 501 can be configured to communicate with the memory 502 to execute a series of computer executable instructions in the memory 502 on the polyimide film thickness measurement system. The polyimide film thickness measurement system can also include one or more power supplies 503, one or more wired or wireless network interfaces 504, one or more input and output interfaces 505, and one or more keyboards 506.

[0075] Specifically in this embodiment, the polyimide film thickness measurement system includes a processor, a communication interface, a memory and a communication bus; wherein the processor, the communication interface and the memory communicate with each other through the bus; the memory is used to store computer programs; the processor is used to execute the programs stored in the memory to achieve the above Figure 1 The various steps in the method embodiment are similar to those in the method embodiment, and have the beneficial effects of the above method embodiments. To avoid repetition, the embodiments of the present invention will not be described in detail here.

[0076] It should be noted that the polyimide film thickness measurement system provided in the embodiment of the present invention and the polyimide film thickness measurement method provided in the embodiment of the present invention are based on the same inventive concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned polyimide film thickness measurement method, and has the same or similar beneficial effects, and the repeated parts will not be repeated.

[0077] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0078] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A method for measuring the thickness of a polyimide film, characterized in that: The polyimide film thickness measurement method comprises: Using a laser thickness gauge to measure the initial thickness of a plurality of measuring points of the polyimide film, the laser thickness gauge emitting laser light at an initial emitting angle to measure the initial thickness of each of the measuring points; Determining the roughness of the surface of the polyimide film according to the initial thickness of each of the measuring points; When the roughness is greater than or equal to the first threshold, determining a laser rotation angle of the laser thickness gauge according to the roughness, the laser rotation angle being an angle at which the laser emitted by the laser thickness gauge rotates relative to the initial emission angle; Using the laser thickness gauge to measure the true thickness of each measuring point of the polyimide film based on the laser rotation angle; Determining the degree of uneven thickness defect of the polyimide film according to the true thickness of each of the measuring points; The thickness quality of the polyimide film is evaluated by the degree of the thickness non-uniformity defect.

2. The method for measuring the thickness of a polyimide film according to claim 1, characterized in that: Determining the roughness of the surface of the polyimide film according to the initial thickness of each of the measuring points comprises: Clustering the initial thickness of each of the measurement points to obtain a plurality of clusters; calculating the standard deviation of the initial thickness within each of the clusters; The roughness of the surface of the polyimide film is determined according to the first number of the clusters, the second number of the measurement points contained in each cluster, the standard deviation corresponding to each cluster, and the third number of all the measurement points.

3. The method for measuring the thickness of a polyimide film according to claim 1, characterized in that: Determining the laser rotation angle of the laser thickness gauge according to the roughness comprises: Obtaining an initial rotation angle of the laser thickness gauge; The product of the roughness and the initial rotation angle is determined as the laser rotation angle of the laser thickness gauge.

4. The method for measuring the thickness of a polyimide film according to claim 1, characterized in that: The measuring the true thickness of each measuring point of the polyimide film by using the laser thickness gauge based on the laser rotation angle comprises: Controlling the laser emission port of the laser thickness gauge to rotate the laser rotation angle in multiple directions from the measuring point where the initial emission angle is located, to obtain the laser emission angle of the laser thickness gauge; Using the laser thickness gauge to measure the thickness of each of the measuring points at each of the laser emission angles based on the laser emission angle; Determine the target roughness of the surface of the polyimide film at each laser emission angle according to the thickness of each measurement point at each laser emission angle; A minimum value is selected from each of the target roughnesses, and the thickness of each of the measuring points at the laser emission angle corresponding to the minimum value is determined as the true thickness.

5. The method for measuring the thickness of a polyimide film according to any one of claims 1 to 4, characterized in that: Determining the degree of uneven thickness defect of the polyimide film according to the true thickness of each of the measuring points includes: Determine a texture window of each measuring point with each measuring point as the center, wherein the texture window includes the measuring point at the center and measuring points around the center; Select other measuring points that are consistent with the actual thickness of the current measuring point; Determining, based on the texture window of the current measurement point and the texture windows of the other measurement points, the possibility that the actual thickness of the current measurement point belongs to the standard thickness; When the probability is less than the second threshold, it is determined that the current measurement point has a thickness unevenness defect; when the probability is not less than the second threshold, it is determined that the current measurement point does not have a thickness unevenness defect; The degree of the uneven thickness defect of the polyimide film is determined according to the true thickness of the measuring point where there is no uneven thickness defect and the true thickness of the measuring point where there is the uneven thickness defect in the polyimide film.

6. The method for measuring the thickness of a polyimide film according to claim 5, characterized in that: The possibility of determining that the actual thickness of the current measurement point belongs to the standard thickness according to the texture window of the current measurement point and the texture windows of the other measurement points includes: Determine the texture similarity between the current measurement point and the other measurement points according to the true thickness of each measurement point in the texture window of the current measurement point, the true thickness of each measurement point in the texture window of the other measurement points, and the distance between each measurement point in the texture window of the current measurement point and the central measurement point, wherein the texture similarity represents the similarity between the film thickness distribution of the current measurement point and the film thickness distribution of the other measurement points; The possibility that the actual thickness of the current measuring point belongs to the standard thickness is determined based on the texture similarity.

7. The method for measuring the thickness of a polyimide film according to claim 5, characterized in that: The step of determining the degree of uneven thickness defects of the polyimide film according to the true thickness of the measuring point where there is no uneven thickness defect and the true thickness of the measuring point where there is uneven thickness defect in the polyimide film comprises: Determine an average thickness of the true thickness of the measurement points where there is no thickness unevenness defect in the polyimide film; The degree of the uneven thickness defect of the polyimide film is determined according to the average thickness and the true thickness of the measuring point where the uneven thickness defect exists.

8. The method for measuring the thickness of a polyimide film according to claim 7, characterized in that: Determining the degree of uneven thickness defect of the polyimide film according to the average thickness and the true thickness of the measuring point where the uneven thickness defect exists includes: Calculating the absolute value of the difference between the actual thickness of each measuring point with uneven thickness defect and the average thickness; The absolute values ​​are superimposed and normalized to obtain the thickness non-uniformity defect degree of the polyimide film.

9. The method for measuring the thickness of a polyimide film according to claim 1, characterized in that: The method of evaluating the thickness quality of the polyimide film by utilizing the thickness non-uniformity defect degree comprises: When the thickness unevenness defect degree is less than or equal to the third threshold, the thickness quality of the polyimide film is determined to be qualified; when the thickness unevenness defect degree is greater than the third threshold, the thickness quality of the polyimide film is determined to be unqualified.

10. A polyimide film thickness measurement system, characterized in that: The polyimide film thickness measurement system comprises: a processor and a memory; wherein the memory is used to store a computer program that can be run on the processor; and the processor is used to execute the program stored in the memory to implement the steps of the polyimide film thickness measurement method as described in any one of claims 1 to 9.

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