An evaluation method, improvement method and evaluation system for the uniformity of a thin film coating

Abstract

The present invention provides a method for evaluating the uniformity of a thin film coating, an improvement method, and an evaluation system. By obtaining the thickness or quality of the coating (3) at different positions on the surface of the baffle (2) in the coating unit during the entire process of coating the thin film (1), the uniformity of the thin film coating is evaluated. The coating on the thin film (1) corresponding to the thicker coating (3) on the surface of the baffle (2) is thinner, and the coating on the thin film (1) corresponding to the thinner coating (3) on the surface of the baffle (2) is thicker; or the coating on the thin film (1) corresponding to the coating (3) with a smaller mass on the surface of the baffle (2) is thicker, and the coating on the thin film (1) corresponding to the coating (3) with a larger mass on the surface of the baffle (2) is thinner. The present invention improves the accuracy of measuring very thin coatings on the surface of the thin film (1), and ultimately enables the thin films of each coating unit along the TD direction to be uniformly coated.

Description

Technical Field

[0001] The present invention relates to the field of vacuum thermal evaporation coating, and specifically relates to a test and evaluation method for the film layer deposition uniformity of a vacuum thermal evaporation coating system, especially an evaluation method, improvement method and evaluation system for the uniformity of thin film coatings. Background Art

[0002] At present, for the surface coating modification of flexible substrates with a roll length of tens of thousands of meters or longer, the common coating methods include vacuum magnetron sputtering coating and vacuum thermal evaporation coating. In particular, vacuum thermal evaporation coating has been relatively maturely applied in the batch production field of packaging composite film layers, and it has the advantages of efficient large-scale production. Relatively speaking, the thin film deposition of packaging films is relatively thin, and the requirement for the uniformity of the coating layer is relatively reduced, and it is relatively easy to meet the quality requirements by this method of production. However, in recent years, the application of composite current collectors in the field of lithium-ion batteries has once again pushed efficient vacuum thermal evaporation coating to new applications. Generally, there are two implementation forms of this method, namely the evaporation boat method and the high-temperature resistant container evaporation method. The former is carried out in the form of continuous wire feeding, that is, wire feeding realizes the continuous supply of evaporation materials, while the latter places the evaporation materials to be evaporated in a high-temperature resistant container in advance, and as the temperature rises, the evaporation effect is achieved. When the evaporation efficiency reaches a certain target, the thin film to be coated starts to be driven at a certain speed. When the evaporation materials inside the high-temperature resistant container are not enough to support the uniform deposition of the subsequent coating layer, the coating is stopped.

[0003] Since the coating layer deposited on the composite current collector for lithium-ion batteries reaches 1 μm or more, it may be necessary to deposit a coating layer with a thickness of several hundred meters at one time and may need to be deposited multiple times to complete the preparation of the required thickness of the coating layer. If the difference in the coating layer thickness uniformity is too large, it may cause the thin film to wrinkle during the deposition and winding process of tens of thousands of meters of the coating layer and not meet the quality requirements, or it may also cause the quality to fail due to the uneven coating layer thickness, or be the main factor limiting the roll length of the coated thin film. The uniformity of the thin film surface is especially reflected in the direction along the width of the thin film (TD direction). On the other hand, in the high-temperature resistant container evaporation method, generally, there are multiple high-temperature resistant containers for evaporation in the TD direction, and its uniformity is closely related to the states of each high-temperature resistant container.

[0004] For the uniformity of the coating deposited in general cases, we can directly measure the film after coating. The uniformity of the coating on the film can be obtained by methods such as direct in-line sheet resistance testing, off-line sheet resistance testing, or off-line thickness testing. However, due to the relatively thin single-layer coating or the non-contact operation testing of the high-speed running film, these methods cause very large errors. Moreover, especially for the equipment system with multiple evaporation units, the uniformity finally tested is the superposition effect of multiple evaporation units after the entire coating is completed, and it is impossible to obtain the uniformity of the thin film coating of each evaporation unit in the formal production process more conveniently and accurately. In addition, it is also quite troublesome to conduct the testing of the relevant coating.

[0005] In summary, the following problems exist in the prior art: The prior art cannot accurately measure the thickness of the coating deposited on the composite current collector product for lithium-ion batteries. In particular, there are large errors in the testing of the very thin coating on the film surface, and the uniformity of the thin film coating at different positions in each evaporation unit cannot be accurately measured. Summary of the Invention

[0006] The present invention provides a method for evaluating the uniformity of a thin film coating, a method for improving the uniformity, and an evaluation system to solve the problems in the above prior art that the thickness of the coating deposited on the composite current collector product for lithium-ion batteries cannot be accurately measured, especially there are large errors in the testing of the very thin coating on the film surface, and the uniformity of the thin film coating at different positions in each evaporation unit cannot be accurately measured, and to achieve a significant improvement in the coating uniformity along the width direction (TD direction) of the film.

[0007] To this end, the present invention proposes a method for evaluating the uniformity of a thin film coating, a method for improving the uniformity, and an evaluation system.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for evaluating the uniformity of a thin film coating, the method comprising the following steps:

[0010] (1) Obtain the coating thickness or mass at different positions on the surface of the baffle in the coating unit based on the entire process of thin film coating. The evaporation source of the coating unit includes a number of high-temperature resistant containers containing evaporation materials. The baffle is located between the evaporation source and the thin film and is used to block the evaporation materials during informal coating.

[0011] (2) Evaluate the uniformity of the thin film coating according to the coating thickness or mass at different positions on the surface of the baffle. The thin film coating is the coating of the evaporation material of a certain evaporation source on the thin film. The thinner the coating on the thin film corresponding to the thicker coating on the surface of the baffle, and the thicker the coating on the thin film corresponding to the thinner coating on the surface of the baffle; or the thicker the coating on the thin film corresponding to the smaller mass coating on the surface of the baffle, and the thinner the coating on the thin film corresponding to the larger mass coating on the surface of the baffle.

[0012] Further, the coating thickness or quality at different positions on the surface of the baffle is obtained by acquiring the three-dimensional scanned image of the lower surface of the baffle.

[0013] Further, a three-dimensional coordinate system is established with the surface of the baffle in the coating unit as the reference plane and the position of the evaporation source as the starting point of the abscissa and ordinate.

[0014] Further, through the three-dimensional coordinate system, the coating thickness or quality at different positions on the surface of the baffle in the coating unit is associated with the coordinate positions of the several high-temperature resistant containers one by one, and the evaporation efficiency of each high-temperature resistant container is obtained.

[0015] Further, the three-dimensional scanned image takes the length direction of the baffle as the X-axis, the width direction of the baffle as the Y-axis, the height direction of the coating as the Z-axis, and the center position of the first high-temperature resistant container corresponding to the X-axis and the Y-axis as the starting point; the X-axis corresponds to the width direction of the thin film, and the Y-axis corresponds to the roll length direction of the thin film.

[0016] Further, in step S1, there are multiple coating units, each coating unit includes a baffle and an array of high-temperature resistant containers, and the coating thickness or quality at different positions on the surface of the baffle is associated with the coordinate positions of the high-temperature resistant containers in the high-temperature resistant container array one by one.

[0017] Further, based on the coating thickness or quality at different positions on the surface of the baffle, the coating thickness of the thin film at the positions corresponding to the coating thickness or quality at different positions on the surface of the thin film and the surface of the baffle in the coating unit is determined.

[0018] A method for improving the uniformity of thin film coating, the coating unit further includes a heating module and a heat preservation module, and the uniformity of the thin film coating is improved based on any one of the above thin film coating uniformity evaluation methods. At the corresponding positions where the coating on the baffle is thicker or the quality is greater, the heating power or heat preservation effect of the high-temperature resistant container is relatively reduced; at the corresponding positions where the coating on the baffle is thinner or the quality is smaller, the heating efficiency or heat preservation effect of the high-temperature resistant container is relatively increased.

[0019] Further, the method for improving the uniformity of thin film coating further includes adjusting the evaporation efficiency of each high-temperature resistant container by adjusting the spacing between each high-temperature resistant container.

[0020] A thin film coating uniformity evaluation system, including:

[0021] An acquisition module and an evaluation module, the function of the acquisition module is to acquire the coating thickness or quality at different positions on the surface of the baffle in the coating unit based on the entire process of thin film coating. The evaporation source of the coating unit includes several high-temperature resistant containers containing evaporation materials, and the baffle is located between the evaporation source and the thin film and is used to block the evaporation materials during non-formal coating.

[0022] The evaluation module is used to evaluate the uniformity of the thin film coating based on the coating thickness or quality at different positions on the surface of the baffle. The thin film coating is the coating of the evaporation material of a certain evaporation source on the thin film. The coating on the thin film corresponding to the thicker coating on the surface of the baffle is thinner, and the coating on the thin film corresponding to the thinner coating on the surface of the baffle is thicker; or for the coating with a smaller mass on the surface of the baffle, the coating on the corresponding thin film is thicker, and for the coating with a larger mass on the surface of the baffle, the coating on the corresponding thin film is thinner.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for evaluating the uniformity of a thin film coating, and the method includes the following steps: S1. Obtain the coating thickness or quality at different positions on the surface of the baffle in the coating unit based on the entire process of thin film coating. The evaporation source of the coating unit includes a number of high-temperature resistant containers containing evaporation materials. The baffle is located between the evaporation source and the thin film and is used to block the evaporation material during informal coating; S2. Evaluate the uniformity of the thin film coating according to the coating thickness or quality at different positions on the surface of the baffle. The thin film coating is the coating of the evaporation material of a certain evaporation source on the thin film. The coating on the thin film corresponding to the thicker coating on the surface of the baffle is thinner, and the coating on the thin film corresponding to the thinner coating on the surface of the baffle is thicker; or for the coating with a smaller mass on the surface of the baffle, the coating on the corresponding thin film is thicker, and for the coating with a larger mass on the surface of the baffle, the coating on the corresponding thin film is thinner. By measuring the thickness or quality of the coating on the surface of the baffle and associating the mass distribution at the corresponding positions with the thin film coating one by one, the present invention improves the accuracy of measuring the very thin coating on the surface of the thin film, and finally realizes that the thin films of each coating unit along the TD direction can be evenly coated. Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of the coating unit in the length direction (coating TD direction) of the baffle of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the combination of the width direction (coating MD direction) of the baffle of the present invention and a number of high-temperature resistant containers.

[0026] Explanation of the Reference Numerals in the Drawings:

[0027] 1. Thin film; 2. Baffle; 3. Coating; 4. High-temperature resistant container; 5. Heating module. Detailed Embodiments

[0028] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the present invention will now be described.

[0029] During vacuum thermal evaporation coating, the thin film 1 will pass through multiple coating units from the unwinding end to the winding end, such asFigure 1 and Figure 2 As shown, each coating unit includes an evaporation unit, each coating unit includes a baffle 2, each evaporation unit includes a high temperature resistant container array, and the high temperature resistant container array is, for example, a 3×6 crucible array. Each evaporation unit also includes an evaporation source, and the evaporation source includes an evaporation material and a plurality of high temperature resistant containers 4 containing the evaporation material, and the high temperature resistant container 4 is, for example, a crucible. Each coating unit includes the characteristics of the thin film coating based on the high temperature container evaporation method. The destination of the total evaporation material is now divided into three aspects: 1) the part that is drawn away during the coating process with vacuum; 2) the coating deposited on the surface of the film 1 during the evaporation coating process; 3) the remaining coating 3 deposited on the surface of the baffle 2.

[0030] like Figure 1 As shown, the baffle 2 is arranged between the evaporation source and the film 1, so as to shield and protect the film 1 from being broken by high temperature baking before and after the formal coating. The baffle 2 is arranged above the evaporation source, and is used to block the evaporation material during the informal coating. The whole coating process includes formal coating and informal coating. During the formal coating, the evaporation material is plated on the film 1, and during the informal coating, the evaporation material is deposited on the baffle 2.

[0031] A three-dimensional coordinate system is established with the surface of the baffle 2 in the coating unit as the reference plane, the length direction of the baffle 2 as the X-axis, the width direction of the baffle 2 as the Y-axis, the height direction of the coating 3 as the Z-axis, and the center position of the first high-temperature resistant container 4 corresponding to the X-axis and the Y-axis as the starting point; based on the entire process of film 1 coating, a three-dimensional scanning image of the lower surface of the baffle 2 is obtained by three-dimensional scanning technology to obtain the thickness or mass of the coating 3 at different positions on the surface of the baffle 2. The thickness of the coating 3 at different positions on the surface of the baffle 2 is directly determined by scanning with the three-dimensional scanning technology, and the mass of the coating 3 at different positions on the surface of the baffle 2 is calculated based on the thickness data obtained by scanning. The three-dimensional scanning technology uses, for example, a three-dimensional laser scanning tester. After obtaining the three-dimensional scanning image, the coordinate positions of the coating 3 at different positions on the surface of the baffle 2 can be obtained, and the coordinate positions of the coating 3 at different positions on the surface of the baffle 2 are associated one by one with the coordinate positions of each high-temperature resistant container 4 in the high-temperature resistant container array, so as to obtain the evaporation efficiency of each high-temperature resistant container 4. The X-axis corresponds to the width direction (TD direction) of the film 1 , and the Y-axis corresponds to the roll length direction (MD direction) of the film 1 , so as to provide a more sufficient basis for adjusting the uniformity of the film 1 in the TD direction and the MD direction.

[0032] The coating unit further includes a heating module 5 and a heat preservation module. The heating module 5 includes heating electrodes, such as graphite heating electrodes. Each heating electrode controls all the high-temperature resistant containers 4 within one coating unit. However, the heating temperatures of each heating electrode for each high-temperature resistant container 4 are not exactly the same, resulting in different heating rates of each high-temperature resistant container 4. The high-temperature resistant container 4 is arranged in the accommodation hole of the graphite heating electrode, and one high-temperature resistant container 4 is placed in one accommodation hole. The actual heating environments of different accommodation holes are different, that is, the heating rates are different, so the thicknesses deposited on the baffle 2 are different. The uniformity of the thin film coating is evaluated according to the thickness or quality of the coating 3 at different positions on the surface of the baffle 2. The thin film coating is the coating of the evaporation material of a certain evaporation source on the thin film 1. If the coating 3 on the surface of the baffle 2 is thicker, the coating of the corresponding thin film 1 is thinner, which indicates that the temperature at this position rises rapidly before the coating is implemented. Therefore, the evaporation material evaporates in advance and is deposited on the coating 3 on the baffle 2 thicker. Therefore, it is necessary to reduce the heating rate of the high-temperature resistant container 4 at this corresponding position or reduce the heat preservation performance, so that the heating environment at this position is closer to that of other high-temperature resistant containers 4, thereby achieving a more uniform coating on the surface of the thin film 1; or for the coating 3 with a larger mass on the surface of the baffle 2, the corresponding coating of the thin film 1 is thinner, and the principle and adjustment principle are the same as above.

[0033] If the coating 3 on the surface of the baffle 2 is thinner, the coating of the corresponding thin film 1 is thicker, or for the coating 3 with a smaller mass on the surface of the baffle 2, the corresponding coating of the thin film 1 is thicker, which indicates that the temperature at this position rises slowly before the coating is implemented, resulting in a relatively small evaporation amount of the evaporation material in the high-temperature resistant container 4 and insufficient deposition speed on the baffle 2. Until the coating of the thin film 1 is completed normally and the coating is stopped, there is still a relatively large amount of evaporation material to be evaporated in the high-temperature resistant container 4 at this corresponding position. Therefore, it is necessary to increase the heating rate of the high-temperature resistant container 4 at this corresponding position or increase the heat preservation performance, so that the heating environment at this position is closer to that of other high-temperature resistant containers 4, thereby achieving a more uniform coating on the surface of the thin film 1.

[0034] Furthermore, the evaporation efficiency of each high-temperature resistant container 4 can also be adjusted by adjusting the spacing between each high-temperature resistant container 4. If the coating deposited on the baffle 2 shows regular thickness fluctuations, it is due to the unreasonable arrangement or design of the spacing of the high-temperature resistant containers 4 in the TD direction or MD direction of the thin film. Therefore, by adjusting the spacing of each high-temperature resistant container 4 in the TD direction or MD direction of the thin film, it can be ensured that each coating unit can perform a uniform thin film coating.

[0035] A thin film coating uniformity evaluation system includes:

[0036] An acquisition module and an evaluation module. The function of the acquisition module is to obtain the coating thickness or quality at different positions on the surface of the baffle 2 in the coating unit based on the entire process of coating the thin film 1, so as to obtain feedback on the unevenness of the coating of the thin film 1. After obtaining the coating distribution of the baffle 2 corresponding to each coating unit, the evaluation module makes an evaluation, thereby adjusting the thermal environment of each high-temperature resistant container 4 so that the evaporation efficiency of each high-temperature resistant container 4 is adjusted to be consistent, so as to achieve uniform thin film coating for each coating unit.

[0037] In the present invention, in order to better determine whether the evaporation unit at certain positions evaporates in advance or delays evaporation, during the actual application process, the uniformity of the coating on the surface of the thin film can be checked at the end of the coating process. If there is still a coating film attached to certain positions, the evaporation at these positions is relatively slow (then the evaporation efficiency will be optimized and improved through the heating module or heat preservation measures). If there is no coating film on the thin film at certain positions, it means that the evaporation at this position is relatively fast (then the heat preservation effect at this place needs to be reduced or a module with a lower evaporation efficiency needs to be replaced).

[0038] The above are only the schematic specific embodiments of the present invention and are not intended to limit the scope of the present invention. The components of the present invention can be combined with each other under the condition of no conflict. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the uniformity of a thin film coating, characterized in that, The method includes the following steps: S1. Obtain the thickness or quality of the coating (3) at different positions on the surface of the baffle (2) in the coating unit based on the entire process of coating the thin film (1). The evaporation source of the coating unit includes a number of high-temperature-resistant containers containing evaporation materials. The baffle (2) is located between the evaporation source and the thin film (1) and is used to block the evaporation materials during informal coating. S2. Evaluate the uniformity of the thin film coating according to the thickness or quality of the coating (3) at different positions on the surface of the baffle (2). The thin film coating is the coating of the evaporation material of a certain evaporation source on the thin film (1). The coating on the thin film (1) corresponding to the thicker coating (3) on the surface of the baffle (2) is thinner, and the coating on the thin film (1) corresponding to the thinner coating (3) on the surface of the baffle (2) is thicker; or the coating on the thin film (1) corresponding to the coating (3) with a smaller mass on the surface of the baffle (2) is thicker, and the coating on the thin film (1) corresponding to the coating (3) with a larger mass on the surface of the baffle (2) is thinner. In step S1, there are multiple coating units, and each coating unit includes a baffle (2) and an array of high-temperature-resistant containers. The thickness or quality of the coating (3) at different positions on the surface of the baffle (2) is in one-to-one correspondence with the coordinate positions of the high-temperature-resistant containers (4) in the high-temperature-resistant container array.

2. The evaluation method for the uniformity of a thin film coating according to claim 1, characterized in that Obtain the thickness or quality of the coating (3) at different positions on the surface of the baffle (2) by obtaining a three-dimensional scanned image of the lower surface of the baffle (2).

3. The evaluation method for the uniformity of a thin film coating according to claim 1, wherein, Establish a three-dimensional coordinate system with the surface of the baffle (2) in the coating unit as the reference plane and the position of the evaporation source as the starting point of the abscissa and ordinate.

4. The evaluation method for the uniformity of a thin film coating according to claim 3, characterized in that, Through the three-dimensional coordinate system, the thickness or quality of the coating (3) at different positions on the surface of the baffle (2) in the coating unit is in one-to-one correspondence with the coordinate positions of the several high-temperature-resistant containers (4), and the evaporation efficiency of each high-temperature-resistant container (4) is obtained.

5. The evaluation method for the uniformity of a thin film coating according to claim 2, characterized in that The three-dimensional scanned image takes the length direction of the baffle (2) as the X-axis, the width direction of the baffle (2) as the Y-axis, the height direction of the coating (3) as the Z-axis, and the center position of the first high-temperature-resistant container (4) corresponding to the X-axis and Y-axis as the starting point; the X-axis corresponds to the width direction of the thin film (1), and the Y-axis corresponds to the roll length direction of the thin film (1).

6. The evaluation method for the uniformity of a thin film coating according to claim 1, wherein Based on the thickness or quality of the coating (3) at different positions on the surface of the baffle (2), determine the thickness of the thin film coating at the positions corresponding to the thickness or quality of the coating (3) at different positions on the surface of the thin film (1) and the surface of the baffle (2) in the coating unit.

7. A film coating uniformity evaluation system, characterized in that, It includes: An acquisition module and an evaluation module. The function of the acquisition module is to obtain the thickness or quality of the coating (3) at different positions on the surface of the baffle (2) in the coating unit based on the entire process of coating the thin film (1). The evaporation source of the coating unit includes a number of high-temperature-resistant containers containing evaporation materials. The baffle (2) is located between the evaporation source and the thin film (1) and is used to block the evaporation materials during informal coating. The evaluation module is used to evaluate the uniformity of the thin film coating according to the thickness or quality of the coating (3) at different positions on the surface of the baffle (2). The thin film coating is the coating of the evaporation material of a certain evaporation source on the thin film (1). The coating on the thin film (1) corresponding to the thicker coating (3) on the surface of the baffle (2) is thinner, and the coating on the thin film (1) corresponding to the thinner coating (3) on the surface of the baffle (2) is thicker; or the coating (3) with a smaller mass on the surface of the baffle (2) corresponds to a thicker coating on the thin film (1), and the coating (3) with a larger mass on the surface of the baffle (2) corresponds to a thinner coating on the thin film (1). There are multiple coating units, and each coating unit includes a baffle (2) and an array of high-temperature resistant containers. The thickness or quality of the coating (3) at different positions on the surface of the baffle (2) is in one-to-one correspondence with the coordinate positions of the high-temperature resistant containers (4) in the high-temperature resistant container array.

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