A method for online monitoring of the thickness of a flat plate coating film

Abstract

The application discloses a kind of flat plate coating film thickness online monitoring method, including coating platform, coating die head is set up above, and multiple frequency thickness measuring device constitutes and is integrated with the online monitoring device of flat plate coating machine;Online monitoring method includes: by coating die head to the coating platform on the material piece of coating is coated to form coating, coating is conductive film, the detection probe of multiple frequency thickness measuring device is downward and directly opposite the material piece on the coating platform and has been coated with coating, real-time obtains impedance variation, that is, obtains resistance variation, inductance variation;By the mapping relationship between resistance variation, inductance variation and square resistance, in combination with the relationship between square resistance and coating thickness, obtain coating thickness, and then by material piece coating thickness and coating preset value are compared, can real-time online adjust coating process parameter, realize the non-contact type, real-time, high-precision film thickness online monitoring and thickness accurate regulation and control of conductive film, effectively guarantee product quality, greatly help to improve production efficiency.

Description

Technical Field

[0001] This invention relates to the field of flatbed coating technology, and in particular to a method for online monitoring of film thickness in flatbed coating. Background Technology

[0002] Flat-panel coating technology, with its unique advantages such as high precision, high efficiency, and customizable adaptability, is increasingly widely used in the preparation of functional coatings for both rigid sheet substrates (silicon wafers, glass) and easily breakable flexible sheet substrates. This technology enables the precise preparation of nanoscale thin films, and is particularly well-suited for the efficient coating of noble metal pastes, photoresists, zinc oxide, and other coating solutions, meeting the production needs of optoelectronics, energy, displays, and semiconductors, with its application scenarios continuously expanding.

[0003] In flatbed coating processes, film thickness measurement is a core step throughout the entire process of "process development - production quality control - product performance assurance." As the most basic and critical parameter of the coating, thickness is directly related to the "dosage distribution" and "flow field stability" of the coating solution, and ultimately determines the core performance of the product. Therefore, achieving accurate thickness measurement by quantifying coating parameters is key to ensuring the stability of the coating process, the consistency of product quality, and the reliability of the final function.

[0004] In existing technologies, an offline thin film thickness measurement scheme is typically adopted, which involves first coating and drying the wet film, and then transferring it to a thickness measurement platform for inspection. This approach has several significant drawbacks. Firstly, the film needs to be moved during thickness measurement, which can easily lead to surface wear and localized peeling of the coating, directly affecting the accuracy of the measurement. Simultaneously, it may cause undried solution on the substrate surface to flow in a certain direction, resulting in areas of excessive thickness. Secondly, offline detection cannot provide real-time feedback on thickness changes; data feedback is significantly delayed, making it impossible to adjust process parameters in a timely manner. This often results in multiple subsequent films exhibiting the same deviation, leading to batch scrapping, reducing coating efficiency, and increasing production costs. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a reasonable online monitoring method for flat-plate coated film thickness, thereby enabling non-contact, real-time, and high-precision online monitoring and precise thickness control of conductive films, effectively ensuring product quality and greatly contributing to improved production efficiency.

[0006] The technical solution adopted in this invention is as follows: A method for online monitoring of film thickness in flat plate coating includes a coating platform, on which a coating die and a multi-frequency thickness measuring device are mounted, forming an online monitoring device integrated with a flat plate coating machine; The online monitoring method is implemented using the online monitoring device, including: coating a sheet on a coating platform with a coating die to form a conductive thin film; the detection probe of the multi-frequency thickness measuring device faces downwards towards the coated sheet on the coating platform to obtain the impedance change in real time, that is, the resistance change and inductance change; and the coating thickness is obtained by the mapping relationship between the resistance change, inductance change and sheet resistance, combined with the relationship between sheet resistance and coating thickness, thus realizing real-time online monitoring of the coating thickness.

[0007] As a further improvement to the above technical solution: The coating comprises one or more thin films. The sheet resistance of each thin film in the coating is obtained by mapping the changes in resistance, inductance, and sheet resistance. Then, the thickness of each thin film in the coating is obtained by the relationship between sheet resistance and thickness.

[0008] The online monitoring method also includes calibration, in which a standard sample with the same number of layers and the same material coating as the one used in the online measurement is used. The thickness of the coating in the standard sample is known, which means that the sheet resistance of the coating in the standard sample is known. A multi-frequency thickness measuring device is used to measure the standard sample to establish a mapping relationship between the change in resistance, the change in inductance and the sheet resistance.

[0009] In the calibration, the number of standard samples N≥5, and the N standard samples have different thicknesses, forming a thickness range; in the online measurement, the thickness of the coating on the sheet is within the thickness range; after measuring the standard samples with a multi-frequency thickness measuring device to obtain the resistance change and inductance change corresponding to each standard sample, the resistance change and inductance change are used as independent variables, and the sheet resistance of the standard sample is used as the dependent variable. The least squares method is used for surface fitting to establish the mapping relationship between the resistance change, inductance change and sheet resistance.

[0010] The calibration and online measurement use the same measurement conditions, including but not limited to measurement distance and measurement frequency.

[0011] The multi-frequency thickness measurement device includes a housing, inside which are a main unit, a pickup coil, an induction coil, and a detection probe. The induction coil is energized with a high-frequency alternating current to generate a primary magnetic field. When the detection probe approaches the coating, the primary magnetic field penetrates the coating and excites eddy currents within it. These eddy currents then generate a secondary magnetic field, which in turn changes the equivalent impedance of the pickup coil, thus providing the impedance change.

[0012] The multi-frequency thickness measuring device is mounted on the horizontal adjustment component, which is mounted on the vertical adjustment component. The vertical adjustment component is mounted on the bracket, which is horizontally positioned above the coating platform. During online measurement, the position of the multi-frequency thickness measuring device relative to the material sheet can be adjusted at the same height through the operation of the horizontal adjustment component.

[0013] A drying device is installed on the coating platform located between the coating die head and the multi-frequency thickness measuring device. The material sheet moves with the coating platform and is coated by the coating platform, dried by the drying device, and then its thickness is measured by the multi-frequency thickness measuring device.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention is ingeniously conceived. By simultaneously deploying an online film thickness monitoring device during the flat sheet coating process, the coating thickness of the sheet is compared with the preset coating value, and the coating process parameters can be adjusted online in real time. This achieves non-contact, real-time, and high-precision online film thickness monitoring and precise thickness control of conductive films, effectively ensuring product quality and greatly contributing to improving production efficiency. The present invention also includes the following advantages: This invention is based on high-frequency eddy current technology and uses a multi-frequency thickness measuring device for online non-contact real-time film thickness monitoring, which effectively solves the technical pain points in the existing coating process and can be adapted to the continuous production process of conventional processes such as slot coating, blade coating and wire rod coating. The online film thickness monitoring method of the present invention is not limited by the specific installation position of each component, which effectively enhances the adaptability, flexibility and versatility of the online monitoring method; This invention employs a multi-frequency thickness measuring device for film thickness measurement, which has a wide range of applications and can accurately measure single-layer conductive films, multi-layer conductive films, and encapsulated conductive films. It breaks through the application limitations of traditional thickness measurement methods and improves the practicality and versatility of the method and device. Moreover, this wide applicability is independent of the installation location, effectively enhancing the industrial application value of the method and device. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the deployment of the online monitoring device of the present invention (Example 1).

[0016] Figure 2 This is a schematic diagram of the state before coating of the present invention (Example 1).

[0017] Figure 3 This is a schematic diagram of the coating and measurement process of the present invention (Example 1).

[0018] Figure 4 This is a schematic diagram of the state after measurement according to the present invention (Example 1).

[0019] Figure 5This is a schematic diagram of the deployment of the online monitoring device of the present invention (Example 2).

[0020] Figure 6 This is a schematic diagram of the state before coating of the present invention (Example 2).

[0021] Figure 7 This is a schematic diagram of the coating and drying process of the present invention (Example 2).

[0022] Figure 8 This is a schematic diagram of the state of the device after drying (Example 2).

[0023] Figure 9 This is a schematic diagram of the state after measurement according to the present invention (Example 2).

[0024] Figure 10 This is a schematic diagram of the support frame, moving guide rail, and multi-frequency thickness measuring device of the present invention.

[0025] Figure 11 This is a schematic diagram of the structure of the multi-frequency thickness measurement device of the present invention.

[0026] The components include: 1. Base; 2. Coating platform; 3. Material sheet; 4. Coating die head; 5. Gantry frame; 6. Moving guide rail; 7. Multi-frequency thickness measuring device; 8. Drying device; 9. Support frame; 10. Coating layer; 71. Main unit; 72. Pickup coil; 73. Induction coil; 74. Detection probe; 75. Housing. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] like Figure 1 As shown, an online monitoring method for flat plate coating film thickness in this embodiment includes a coating platform 2 set on a base 1, a coating die head 4 and a multi-frequency thickness measuring device 7 mounted above the coating platform 2, forming an online monitoring device integrated with the flat plate coating machine.

[0029] In this embodiment, the multi-frequency thickness measuring device 7 is integrated into the flat plate coating machine to form an online monitoring device, without the need to build an additional independent thickness measuring platform.

[0030] The online monitoring method is implemented using an online monitoring device, including: coating a sheet 3 on a coating platform 2 with a coating die 4 to form a coating layer 10, the coating layer 10 being a conductive thin film; the detection probe 74 of the multi-frequency thickness measuring device 7 facing downwards and directly facing the sheet 3 on the coating platform 2 coated with the coating layer 10, to obtain the impedance change in real time, that is, to obtain the resistance change and inductance change; and to obtain the thickness of the coating layer 10 by the mapping relationship between the resistance change, inductance change and sheet resistance, combined with the relationship between sheet resistance and coating layer 10 thickness, thus realizing real-time online monitoring of the coating layer 10 thickness.

[0031] In this embodiment, by simultaneously deploying an online film thickness monitoring device during the flat plate coating process, the coating thickness of the sheet 3 and the coating 10 is compared with the preset coating value, and the coating process parameters can be adjusted online in real time, realizing non-contact, real-time, high-precision online film thickness monitoring and precise thickness control of the conductive film.

[0032] In actual operation, the impedance change needs to be obtained by first detecting the basic impedance by the multi-frequency thickness measuring device 7 under no-load conditions, that is, when the sheet 3 is not coated with the coating 10. After the sheet 3 is coated with the coating 10, the current impedance is detected by the multi-frequency thickness measuring device 7. The impedance change is obtained from the difference between the current impedance and the basic impedance.

[0033] The impedance Z, resistance R, and inductance L have a physical relationship: Z = R + jωL, where ω is the angular frequency and j is the imaginary unit. Therefore, after obtaining the basic impedance and the current impedance, it is possible to obtain the resistance change and inductance change corresponding to the impedance change.

[0034] The coating 10 includes one or more thin films. The sheet resistance of each thin film in the coating 10 is obtained by mapping the change in resistance, the change in inductance and the sheet resistance. Then, the thickness of each thin film in the coating 10 is obtained by the relationship between the sheet resistance and the thickness. This enables the measurement of the thickness of the coating 10, which has one or more thin films.

[0035] In this embodiment, the relationship between sheet resistance and corresponding thickness is cleverly utilized: ; in, The sheet resistance of a certain thin film layer in coating 10 (unit: Ω / □); The resistivity of the corresponding thin film (unit: Ω·cm); The corresponding film thickness (unit: nm).

[0036] The online monitoring method also includes calibration. In the calibration, a standard sample with the same number of layers and the same material as the coating 10 used in the online measurement is used. The thickness of the coating 10 in the standard sample is known, which means that the sheet resistance of the coating 10 in the standard sample is known. A multi-frequency thickness measuring device 7 is used to measure the standard sample to establish the mapping relationship between the change in resistance, the change in inductance and the sheet resistance.

[0037] In this embodiment, the structure of coating 10 in the standard sample is defined to be the same as that of coating 10 on the material sheet 3 in online measurement, including the number of coating layers and the same material for each layer, so that the mapping relationship obtained by calibration can be effectively corresponded and applied to online measurement, ensuring the accuracy and reliability of online measurement.

[0038] In the calibration, the number of standard samples N≥5, and the N standard samples have different thicknesses, forming a thickness range; in the online measurement, the thickness of the coating 10 on the material sheet 3 is within the thickness range; after measuring the standard samples using the multi-frequency thickness measuring device 7 and obtaining the resistance change and inductance change corresponding to each standard sample, the resistance change and inductance change are used as independent variables, and the sheet resistance of the standard sample is used as the dependent variable. The least squares method is used to perform surface fitting, thereby establishing the mapping relationship between the resistance change, inductance change and sheet resistance.

[0039] The same measurement conditions are used in calibration and online measurement, including but not limited to measurement distance and measurement frequency.

[0040] like Figure 11 As shown, the multi-frequency thickness measuring device 7 includes a housing 75, inside which a main unit 71, a pickup coil 72, an induction coil 73, and a detection probe 74 are disposed. The induction coil 73 is supplied with a high-frequency alternating current to generate a primary magnetic field. When the detection probe 74 approaches the coating 10, the primary magnetic field penetrates the coating 10 and excites eddy currents within the coating 10. The eddy currents then generate a secondary magnetic field, which causes a change in the equivalent impedance of the pickup coil 72, thereby obtaining the impedance change.

[0041] In practical use, during detection, the pickup coil 72 transmits the signal to the host 71. The host 71 calculates the impedance change based on the magnetic field amplitude, calculates the sheet resistance using a mapping relationship, and obtains the coating thickness using the known resistivity of the coating material. The thickness data is then fed back to the coating machine's control system in real time. When the detected thickness exceeds the preset range (e.g., preset thickness 500±30nm, detected value 550nm), the control system immediately adjusts the coating speed to ensure that the subsequent coating thickness meets the requirements.

[0042] The multi-frequency thickness measuring device 7 is installed on the horizontal adjustment component, the horizontal adjustment component is installed on the vertical adjustment component, the vertical adjustment component is installed on the bracket, and the bracket is horizontally mounted above the coating platform 2.

[0043] In this embodiment, the horizontal adjustment component and the vertical adjustment component can be general linear adjustment components such as the moving guide rail 6 and the moving module in the corresponding direction, which can meet the horizontal and vertical adjustment of the multi-frequency thickness measuring device 7.

[0044] In online measurement, the position of the multi-frequency thickness measuring device 7 relative to the sheet 3 can be adjusted at the same height by the operation of the lateral adjustment component, thereby realizing online monitoring of the coating 10 of the sheet 3 at different lateral positions at the same height.

[0045] In actual operation, the multi-frequency thickness measuring device 7 can be used to form a linear or "S"-shaped multi-path movement relative to the material sheet 3 by combining the operation of the horizontal adjustment component, so as to meet the needs of coating 10 of material sheets 3 of different sizes and monitoring requirements.

[0046] In this embodiment, the online monitoring function, real-time data feedback function, and linkage function with the coating machine are not limited by the installation height, horizontal position, or other layout of the multi-frequency thickness measuring device on the support frame. As long as the multi-frequency thickness measuring device and the coating platform are set relative to each other and can generate relative movement, the preset detection function can be realized, which greatly improves the adaptability, flexibility, and versatility on different models of flatbed coating machines.

[0047] A drying device 8 is installed on the coating platform 2 located between the coating die head 4 and the multi-frequency thickness measuring device 7. The material sheet 3 moves with the coating platform 2, and the material sheet 3 is coated by the coating platform 2, dried by the drying device 8, and measured by the multi-frequency thickness measuring device 7 in sequence.

[0048] Example 1: like Figures 1-4 As shown, this is a coating-thickness measurement synchronous mode, with the coating die 4 and the multi-frequency thickness measurement device 7 supported on both sides of the gantry 5.

[0049] The collaborative method is as follows: The sheet material 3 is placed on the coating platform 2 of the flatbed coater, and the coating device is started for coating. During coating, the coating platform 2 moves the sheet material 3, and simultaneously, the moving guide rail 6 drives the multi-frequency thickness measuring device 7 to move relative to the sheet material 3. The multi-frequency thickness measuring device 7 synchronously detects the film thickness and outputs data in real time. Based on the data, coating process parameters, such as coating speed and paint output, are adjusted in real time to ensure the film thickness meets requirements. In this mode, the synchronous coordination function of coating and thickness measurement is not affected by the installation position of each component; only the adaptation of the motion trajectory needs to be ensured.

[0050] Example 2: like Figures 5-9 As shown, this is a coating-drying-thickness measurement coordinated mode. The coating die 4 and the drying device 8 are supported on both sides of the gantry 5, and the multi-frequency thickness measurement device 7 is supported on the support frame 9.

[0051] The collaborative method is as follows: the sheet material 3 is placed on the coating platform 2, the coating device is started for coating, and the drying device 8 simultaneously dries the coated sheet material 3. After coating and drying are completed, the coating platform 2 moves the sheet material 3 to the detection area of ​​the multi-frequency thickness measuring device 7. According to the testing requirements of the sheet material 3, the relative position and measurement path of the multi-frequency thickness measuring device 7 are adjusted to detect the film thickness on the sheet material 3, ensuring detection accuracy. The drying function of the drying device 8 and its collaborative effect with the coating device and the thickness measuring device are not limited by its specific installation position. As long as the positions of the drying area, coating area, and detection area are compatible, efficient collaboration can be achieved.

[0052] In practice, after the first coating layer has dried, the second coating layer and the third coating layer can be applied and dried sequentially. After all three coating layers are completed, the coating platform 2 moves the material sheet 3 to the detection area of ​​the multi-frequency thickness measuring device 7 for online monitoring of the thickness of each layer.

[0053] In such Figure 10 In the embodiment shown, the multi-frequency thickness measuring device 7 is installed above the coating platform 2 via the moving guide rail 6 and the support frame 9.

[0054] Based on high-frequency eddy current technology, a multi-frequency thickness measuring device is used for online non-contact real-time film thickness monitoring, which effectively solves the technical pain points in the existing coating process. It eliminates the need to move the film to the thickness measuring area, avoiding phenomena such as coating edge wear, local peeling, and uneven thickness during the transfer process. This ensures both measurement accuracy and maintains the integrity of the film. At the same time, it can be adapted to the continuous production process of conventional processes such as slot coating, blade coating, and wire rod coating.

[0055] In this embodiment, real-time data feedback and support for instant adjustment of coating process parameters effectively prevent batch products from being scrapped due to the same deviation, significantly reducing production costs.

[0056] The online film thickness monitoring method of this invention is not limited by the specific installation location of each component, effectively enhancing the adaptability, flexibility and versatility of the online monitoring method.

[0057] Examples of calibration and online measurement are given, using 10 layers of coating as an example, whether it is a single layer or a double layer.

[0058] Example 1: The case where coating 10 is a single layer.

[0059] Calibration: Select at least N standard plates (N≥5) with known sheet resistance values; Measure the change in impedance to obtain the change in resistance. With the change in inductance ; Place the detection probe 74 of the multi-frequency thickness measuring device 7 in air (or on an uncoated, bare insulating substrate identical to the sheet 3), and record the baseline impedance at this time. ω is the angular frequency, and j is the imaginary unit. , Basic resistor, It is an unloaded inductor; Place the first standard sample face up in the fixed position directly below the detection probe 74, ensuring the lifting distance is correct. Maintain consistency with subsequent measurements. After the readings stabilize, record the current impedance after loading the standard piece. , For the current resistance, For the current inductance; The following changes were calculated: Change in resistance: (Unit: Ω); Change in inductance: (Unit: H); Repeated measurements: Repeat the above measurements on the remaining N-1 standard pieces, obtaining a total of N sets of data pairs: ( ),in , This corresponds to the sheet resistance value of the standard piece; The measured As the independent variable, As the dependent variable, the least squares method is used for surface fitting to establish a mapping relationship. .

[0060] The least squares method was used for fitting, as follows: Mapping relationship The mathematical model used is a two-variable quadratic polynomial (higher-degree terms can be selected according to accuracy requirements), and its expression is as follows: .

[0061] The goal of fitting is to find a set of coefficients: Such that the sum of squared residuals of all calibrated sample points Minimum. The residual is defined as the model's predicted value. Compared with the true value difference.

[0062] .

[0063] After calibration, a mathematical model is obtained. Then, measurements were taken.

[0064] The measurement process is as follows: Place the detection probe 74 in air or on a bare substrate and record the basic impedance. The film under test is placed under the exact same measurement conditions as during calibration (same probe, same lift-off distance). Record the current impedance in real time. ; Calculation obtained and ;Will Substitute into the fitted polynomial model In the middle, calculate the corresponding sheet resistance. Input the known material resistivity Using basic physical relationships The film thickness was derived. .

[0065] Operating frequency: MHz (fixed), lift-off distance: Taking mm (fixed) as an example, the calibration and measurement are carried out.

[0066] Calibration: Select 5 standard ITO (Indium Tin Oxide) conductive thin film sheets. The corresponding sheet resistances are as follows: The impedance changes of five standard plates were measured and recorded, and the data are shown in the table below: By fitting a bivariate quadratic polynomial using the least squares method and solving the normal equation, the polynomial model is obtained as follows: .

[0067] Measurement: Place the probe in the air and record. , Place the ITO film (unknown thickness) under the probe and measure... , The impedance change is calculated as follows: ; .

[0068] Next, solve for the sheet resistance. , Substitute into the polynomial model: ; Calculations show that .

[0069] Calculate the thickness of the dielectric. The resistivity of the ITO material is known. .

[0070] .

[0071] Therefore, the thickness of the film is approximately 39.8 nanometers.

[0072] Example 2: When coating 10 is a double layer, the thickness of the upper layer of the double conductive film is... lower layer thickness The resistivity of the two-layer material It is known.

[0073] Calibration: Prepare a set of standard samples, covering the upper layer thickness and lower layer thickness The expected range of change.

[0074] For example: the thickness of the upper layer is taken as Level: The thickness of the lower layer is taken as Level: ; prepared in total The thickness of each layer of the standard sheet is known.

[0075] Based on the known resistivity of each layer of material Calculate the equivalent sheet resistance of each layer of each standard piece: upper layer: Lower layer: in: .

[0076] Place the probe in air (or on the same insulating bare substrate as the multilayer film) at a selected set of measurement frequencies. ( For example, at both low and high frequencies, record the probe's fundamental impedance. , .

[0077] The frequency selection method is as follows: Skin depth There is a relationship with the detection frequency f: When making frequency selection, it prompts < , , > , Thus, the corresponding high frequency is obtained. and low frequency .

[0078] Place the first standard film face up in the fixed position directly below the probe, ensuring the lift-off distance. Consistent with subsequent measurements; sequentially at each frequency. Below, the total impedance after loading the standard piece is measured. Calculate the change at each frequency: For each frequency Calculate the impedance change respectively: Change in resistance: ; Change in inductance: ; For the remaining Repeat the above measurements on a standard sample to obtain... Set up data pairs; construct a mathematical model and fit it using the least squares method. As the independent variable, Using the sheet resistance as the dependent variable, the least squares method is used to perform multivariate nonlinear regression fitting to establish a mapping relationship with the upper and lower sheet resistances, thus completing the calibration.

[0079] Next, measurements were performed. The measurement process involved placing the probe in air or on a bare substrate and recording the fundamental impedance. The bilayer film under test was placed under the exact same measurement conditions as during calibration, and the real-time impedance was recorded at all measurement frequencies. ; Calculate the impedance change at each frequency, for each frequency ,calculate: ; Will , Substitute into the model to directly calculate the equivalent sheet resistance of the upper layer. and the lower layer equivalent sheet resistance .

[0080] Based on the operating frequency: select two characteristic frequencies, high frequency MHz (small skin depth, mainly sensitive to the upper layer), low frequency MHz (large skin depth, penetrating to lower layers); lift-off distance: Taking mm (fixed) as an example, the calibration and measurement are carried out.

[0081] The structure of the double-layer thin film to be tested is as follows: Top layer: Copper film (Cu), resistivity ,thickness To be tested; Bottom layer: Aluminum film (Al), resistivity ,thickness To be tested; Substrate: Insulating glass.

[0082] Calibration: Preparation of a standard wafer matrix, comprising 9 standard wafers orthogonally combined; upper copper layer thickness. : 50nm, 100nm, 200nm (3 levels); lower aluminum layer thickness 100nm, 200nm, 500nm (3 levels). Based on the known resistivity, calculate the equivalent sheet resistance of each layer of each standard wafer: By combining the least squares method for fitting, the following mapping relationship is obtained.

[0083] Upper-level equivalent sheet resistance model: ; Lower-level equivalent sheet resistance model: .

[0084] Measurement: In and The air impedance was measured separately; the bilayer membrane to be tested (unknown) was then placed under test. Placed under the probe; the measured impedance change is: exist Below, measured , ; exist Below, measured , .

[0085] Substituting the above values ​​into the equivalent sheet resistance models of the upper and lower layers, we obtain the following calculations: , .

[0086] Based on the known resistivity , Thickness calculations are performed.

[0087] Therefore, the upper copper layer of this double-layer film is approximately 101 nm thick, and the lower aluminum layer is approximately 198 nm thick.

[0088] This invention employs a multi-frequency thickness measuring device for film thickness measurement, which has a wide range of applications and can accurately measure single-layer conductive films, multi-layer conductive films, and encapsulated conductive films. It breaks through the application limitations of traditional thickness measurement methods and improves the practicality and versatility of the method and device. Moreover, this wide applicability is independent of the installation location, effectively enhancing the industrial application value of the method and device.

[0089] This invention enables non-contact, real-time, and high-precision online monitoring and precise control of conductive film thickness, effectively ensuring product quality and greatly contributing to improved production efficiency.

[0090] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0091] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A method for online monitoring of film thickness in flat-plate coatings, characterized in that: It includes a coating platform (2), and a coating die head (4) and a multi-frequency thickness measuring device (7) are mounted on the coating platform (2), forming an online monitoring device integrated with the flat plate coating machine; The online monitoring method is implemented using the online monitoring device, including: coating the sheet (3) on the coating platform (2) with a coating die (4) to form a coating layer (10), the coating layer (10) is a conductive thin film, the detection probe (74) of the multi-frequency thickness measuring device (7) faces downwards and is directly facing the sheet (3) on the coating platform (2) coated with the coating layer (10), and the impedance change is obtained in real time, that is, the resistance change and the inductance change are obtained; the thickness of the coating layer (10) is obtained by mapping the resistance change and the inductance change with the sheet resistance, combined with the relationship between the sheet resistance and the thickness of the coating layer (10), so as to realize the real-time online monitoring of the thickness of the coating layer (10).

2. The method for online monitoring of film thickness in flat-plate coating as described in claim 1, characterized in that: The coating (10) includes one or more thin films. The sheet resistance of each thin film in the coating (10) is obtained by mapping the resistance change, inductance change and sheet resistance. Then, the thickness of each thin film in the coating (10) is obtained by the relationship between sheet resistance and thickness.

3. The method for online monitoring of film thickness in flat-plate coating as described in claim 1, characterized in that: The online monitoring method also includes calibration, in which a standard sample with the same number of layers and the same material coating (10) as the online measurement is used. The thickness of the coating (10) in the standard sample is known, that is, the sheet resistance of the coating (10) in the standard sample is known. A multi-frequency thickness measuring device (7) is used to measure the standard sample to establish the mapping relationship between the resistance change, the inductance change and the sheet resistance.

4. The method for online monitoring of film thickness in flat-plate coating as described in claim 3, characterized in that: In the calibration, the number of standard samples N≥5, and the N standard samples have different thicknesses to form a thickness range; in the online measurement, the thickness of the coating (10) on the sheet (3) is within the thickness range; after measuring the standard samples with a multi-frequency thickness measuring device (7) and obtaining the resistance change and inductance change corresponding to each standard sample, the resistance change and inductance change are used as independent variables, and the sheet resistance of the standard sample is used as the dependent variable. The least squares method is used to fit the surface, thereby establishing the mapping relationship between the resistance change, inductance change and sheet resistance.

5. The method for online monitoring of film thickness in flat-plate coating as described in claim 3, characterized in that: The calibration and online measurement use the same measurement conditions, including but not limited to measurement distance and measurement frequency.

6. The method for online monitoring of film thickness in flat-plate coating as described in claim 1, characterized in that: The multi-frequency thickness measuring device (7) includes a housing (75), and a host (71), a pickup coil (72), an induction coil (73), and a detection probe (74) are arranged inside the housing (75). The induction coil (73) is supplied with a high-frequency alternating current to generate a primary magnetic field. When the detection probe (74) approaches the coating (10), the primary magnetic field penetrates the coating (10) and excites eddy currents in the coating (10). The eddy currents then generate a secondary magnetic field, which causes the equivalent impedance of the pickup coil (72) to change, thereby obtaining the impedance change.

7. The method for online monitoring of film thickness in flat-plate coating as described in claim 1, characterized in that: The multi-frequency thickness measuring device (7) is installed on the horizontal adjustment component, the horizontal adjustment component is installed on the vertical adjustment component, the vertical adjustment component is installed on the bracket, and the bracket is horizontally mounted above the coating platform (2). During online measurement, the position of the multi-frequency thickness measuring device (7) relative to the material sheet (3) can be adjusted at the same height through the operation of the horizontal adjustment component.

8. The method for online monitoring of film thickness in flat-plate coating as described in claim 1, characterized in that: A drying device (8) is installed on the coating platform (2) located between the coating die head (4) and the multi-frequency thickness measuring device (7). The material sheet (3) moves with the coating platform (2). The material sheet (3) is coated by the coating platform (2), dried by the drying device (8), and its thickness is measured by the multi-frequency thickness measuring device (7) in sequence.

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