Film layer preparation method, film layer, watch and terminal

Abstract

The invention relates to a preparation method for preparing a film layer with a coplanar multicolor and large-angle color changing effect on the surface of a base material, and belongs to the technical field of optical thin films. The method comprises the following steps: firstly, structural parameters of a first film layer and a second film layer are designed through optical simulation software, so that the first film layer, the second film layer and the first film layer present a target color under vertical incidence and inclined incidence conditions after being overlapped; then depositing a first film layer on the whole surface of the base material, and silk-screening a non-water-soluble protective ink layer in a specified area; depositing a second film layer on the whole surface; and finally, the protective ink layer is removed, so that the non-covered area presents the second color, the other areas keep the first color, and the effect of coplanar double-color and large-angle color changing is achieved. The method may also produce more color partitions by repeating some of the steps. The method is simple in process, clear in color boundary, high in production efficiency, good in finished product yield and suitable for preparing multifunctional optical film layers on the surfaces of materials such as sapphire and glass.

Description

Technical Field

[0001] The present invention relates to the technical field of optical thin films, and in particular to a film preparation method, a film layer, a watch and a terminal. Background Art

[0002] In high-end product sectors such as consumer electronics, watches, and jewelry, decorative surface films not only protect the substrate but also play a crucial role in enhancing the aesthetic appeal of the product. In recent years, as consumers' demand for personalized products and enhanced visual experiences continues to rise, optical films with multi-color distribution and wide-angle color-shifting effects have become a research hotspot.

[0003] Traditionally, achieving different colors on the same surface typically involves multiple coatings combined with masking using jigs or partial stripping. For example, after coating a certain area with the first color, the area is protected by screen printing with protective ink or applying masking tape, and then the remaining areas are coated with the second color. This method has several drawbacks: first, the process is complex, requiring multiple coating and stripping cycles; second, the boundaries are blurred, making transitional colors more likely; and third, the yield rate is low, the operation is difficult, and the cost is high.

[0004] In addition, the single film layer or multi-layer film structure in the prior art is difficult to achieve a significant large-angle color change effect, that is, when the observation angle changes, the color change is not obvious and lacks visual impact.

[0005] Therefore, there is an urgent need to provide a new film preparation method that can achieve different colors in multiple areas on a single surface and show obvious color changes at different observation angles, thereby meeting the design requirements of high-end products. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: to provide a film preparation method in view of the above-mentioned defects of the prior art.

[0007] To achieve the above object, the present invention provides a method for preparing a film layer, the method comprising the following steps:

[0008] Step S1, using optical simulation software to design the structures of the first film layer and the second film layer so that:

[0009] The first film layer presents a first color when the incident angle is 0°, and presents a second color when tilted to a larger angle;

[0010] After the second film layer is superimposed on the outermost layer of the first film layer, it presents a third color when the incident angle is 0°, and presents a fourth color when tilted to a larger angle;

[0011] Wherein, the first film layer is a composite film layer with no less than three layers; the second film layer is a single-layer structure;

[0012] Step S2: depositing a first film layer on the entire first surface of the substrate;

[0013] Step S3: screen printing a protective ink layer on the first area of ​​the first surface, and then baking the protective ink layer;

[0014] Step S4: depositing a second film layer on the entire surface of the first surface;

[0015] Step S5: removing the protective ink layer.

[0016] In the film preparation method of the present invention, the thickness of the first film layer is 300nm to 400nm.

[0017] In the film preparation method of the present invention, the step S5 further includes:

[0018] At least one additional film layer is designed to be superimposed on the second film layer using optical simulation software, so that each additional film layer, when superimposed on the original film layer, exhibits a desired color at an incident angle of 0° and after being tilted at a large angle;

[0019] For each additional film layer, steps S3-S5 are repeated, wherein a protective ink layer is screen-printed in the area to be masked, an additional film layer is deposited on the entire surface, and the protective ink layer is removed.

[0020] In the film preparation method of the present invention, the thickness of the protective ink layer is 4 μm to 6 μm.

[0021] In the film preparation method of the present invention, the method of depositing the first film layer and the method of depositing the second film layer are magnetron sputtering coating or evaporation coating.

[0022] In the film preparation method of the present invention, the first film layer includes a 7-layer structure.

[0023] In the film layer preparation method of the present invention, the first film layer includes a first silicon oxide layer, a first metal niobium layer, a second silicon oxide layer, a second metal niobium layer, a third silicon oxide layer, a niobium oxide layer, and a first silicon nitride layer stacked in sequence from bottom to top; the first silicon oxide layer is arranged opposite to the first surface, and the first silicon nitride layer is arranged opposite to the second film layer; and the second film layer includes a second silicon nitride layer.

[0024] The present invention also provides a film layer prepared by the above method.

[0025] The present invention also provides a watch, the dial of which includes the film layer described above.

[0026] The present invention further provides a terminal, comprising at least a terminal body and a shell, wherein the shell comprises the film layer as described above.

[0027] The present invention provides a novel film preparation method, which has the following significant technical advantages and practical application value compared with the existing technology:

[0028] 1. Achieve multi-color and wide-angle color-changing effects on the same surface: Through the rational design of the composite film structure and the combination of selective masking technology, color differences in multiple areas on the same surface are achieved, and significant color changes are presented at different observation angles, enhancing visual expression.

[0029] 2. Simplify the process flow and improve production efficiency: The two-color effect can be achieved by coating the entire surface twice, without the need for multiple coatings or complicated stripping processes, reducing manual operation links and improving production efficiency and product consistency.

[0030] 3. Clear color boundaries and no transition areas: By precisely controlling the screen printing size and the selection of protective ink, the boundaries between different color areas are ensured to be clear and distinct, avoiding the transition color problem common in traditional methods.

[0031] 4. The film structure is simple and easy to control: The second film layer is a single-layer structure, which is convenient for process control and reduces the risk of color instability caused by film thickness deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 A schematic diagram of the steps of the film preparation method provided in an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the vertical angle color of the sapphire dial provided in Example 1 of the present invention.

[0035] Figure 3 This is a schematic diagram of the color of the sapphire dial according to the tilt angle provided in Example 1 of the present invention.

[0036] Figure 4 This is a schematic diagram of the membrane layer structure provided in Example 1 of the present invention.

[0037] Figure 5 Schematic diagram of the process flow and effect comparison between the control example and embodiment 1. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] The embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0040] This invention provides a film preparation method particularly suitable for producing functional films with multi-color, wide-angle color-shifting effects on the surfaces of optically transparent substrates such as sapphire watch dials and glass cover plates for mobile phones and tablets. By rationally designing the film structure and incorporating a selective masking process, this method achieves multiple color distributions on a single surface, exhibiting significant color changes at different viewing angles, thus meeting the dual aesthetic and functional requirements of high-end consumer electronics products.

[0041] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing a film layer, the method comprising the following steps:

[0042] Step S1, using optical simulation software to design the structures of the first film layer and the second film layer so that:

[0043] The first film layer presents a first color when the incident angle is 0°, and presents a second color when tilted to a larger angle (e.g., 45°-60°);

[0044] After the second film layer is superimposed on the outermost layer of the first film layer, it presents a third color when the incident angle is 0°, and presents a fourth color when tilted to a larger angle;

[0045] Wherein, the first film layer is a composite film layer with no less than three layers; the second film layer is a single-layer structure.

[0046] The key to film design lies in controlling the thickness, refractive index, and arrangement of each layer to achieve the desired optical interference effect and color change characteristics. In one specific embodiment of the present invention, the optical simulation software used is TFCalc. This software is a professional tool widely used in the field of optical thin film design, with powerful computing capabilities, a rich material database, and a user-friendly interface. By inputting information such as the target color, tilt angle, and material parameters, a film structure that meets specific optical performance requirements can be simulated. Specifically, the structural parameters of the first film layer are first set according to the desired first and second colors, ensuring that it exhibits the first color under normal incidence and shifts toward the shorter wavelength direction to exhibit the second color under tilted angles. Subsequently, the second film layer is superimposed on the first film layer, and the parameters are readjusted so that the entire film system exhibits a third color under normal incidence and a fourth color under tilted angles. This design method can achieve differentiated color expression in multiple areas on the same surface, while maintaining a consistent color transition effect when viewed from a wide angle. To achieve wide-angle color change, the first film layer comprises at least three stacked film layers.

[0047] In the embodiment of the present invention, the thickness of the first film layer is controlled between 300nm and 400nm, and the thickness of the second film layer is less than 100nm, to ensure a balance between film strength and optical performance. Excessively thick film layers may lead to reduced mechanical strength, increased white spots, and greater color deviation, while also extending production cycles and increasing energy consumption.

[0048] Step S2: depositing a first film layer on the entire first surface of the substrate.

[0049] In an embodiment of the present invention, a first film layer is deposited entirely on the first surface of the substrate using a magnetron sputtering coating machine or an evaporation coating device. Using a magnetron sputtering coating machine or an evaporation coating machine with good vacuum performance can produce a thin film with high density and strong adhesion on the surface of the substrate. Specifically, models such as the New Kelong RAS1100, Guangchi 1650, and UNIVAC2700 can be selected.

[0050] The initial vacuum level is one of the most important parameters in the coating process, significantly impacting the film's density, adhesion, actual plating thickness, and optical properties. Therefore, during the coating preparation process, vacuum must be drawn to ensure the vacuum level meets the required standards before starting the coating process.

[0051] Step S3: screen-printing a non-water-soluble protective ink layer on the first area of ​​the first surface (ie, the area where the first color needs to be retained later), and then baking the protective ink layer.

[0052] The protective ink layer is used to shield the area to prevent subsequent coating coverage. In an embodiment of the present invention, the thickness of the protective ink layer is preferably 4μm-6μm, which is sufficient to effectively block the deposition of subsequent film layers, but does not affect the clarity of the boundaries. The silk screen needs to be precisely customized according to the required pattern to ensure that the boundaries of the color partitions are clear and there are no transition areas. The protective ink is preferably a non-water-soluble type that does not contain a curing agent to facilitate subsequent removal. After silk screen printing is completed, the ink layer needs to be dried to avoid affecting the subsequent cleaning and coating processes.

[0053] After screen printing, the substrate needs to be ultrasonically cleaned. When cleaning, you can choose acidic cleaning solution or alkaline cleaning solution according to the type of ink.

[0054] Step S4: depositing a second film layer on the entire first surface of the substrate.

[0055] After the protective ink layer is applied and dried, a second film layer is deposited on the entire first surface. Since the second film layer is a single-layer structure, its thickness is preferably less than 100 nm to reduce process complexity and improve yield.

[0056] Step S5: removing the protective ink layer.

[0057] In an embodiment of the present invention, an organic solvent such as Astron, acetone, or thinner is used to remove the protective ink layer, revealing the original first film layer area. This area retains the original first color, while the unobstructed area is covered by the second film layer, revealing the third color. When the viewing angle is tilted to a larger angle, the two areas respectively exhibit the second and fourth colors, achieving a dual-color effect on the same surface with wide-angle color change. The position of the first area is set according to actual needs. For example, for a circular substrate, the first area can be a circular area at the outer edge of the substrate, a central circular area, or a semicircular area.

[0058] In this embodiment of the present invention, after coating the first film layer, a protective ink layer is simply screen-printed on the first area. A second, single-layer film layer is then applied to the entire surface. The protective ink layer is then removed. This achieves the effect of different colors in different areas, with wide-angle color changes. Both coatings are applied to the entire surface, and the second coating only requires a single layer. This simplifies the process, eliminates the need for de-coloring the film, and eliminates the need for jigs or protective film. Compared to electroplating different film layers in different areas, the boundaries between different colors are more distinct, with no transitional color zones appearing along the boundary.

[0059] In addition to producing a two-color effect on the same surface, more colors can be produced in different areas of the same surface as needed, and a large-angle color change effect can be achieved. In some embodiments of the present invention, after step S5, the following steps are further included:

[0060] At least one additional film layer is designed to be superimposed on the second film layer using optical simulation software, so that each additional film layer, when superimposed on the original film layer, exhibits a desired color at an incident angle of 0° and after being tilted at a large angle;

[0061] For each additional film layer, steps S3-S5 are repeated, wherein a protective ink layer is screen-printed in the area to be masked, an additional film layer is deposited on the entire surface, and the protective ink layer is removed.

[0062] For example, if three colors need to be prepared on the same surface and the color changes at a large angle are present, step S5 may further include:

[0063] The structure of the third film layer is designed using optical simulation software so that after the third film layer is superimposed on the outermost layer of the second film layer, it presents a fifth color at an incident angle of 0° and a sixth color after being tilted at a large angle;

[0064] Screen printing a protective ink layer on a second area on the surface of the substrate, and then baking the protective ink layer;

[0065] Depositing a third film layer on the entire first surface of the substrate;

[0066] The protective ink layer in the second area is removed.

[0067] When the incident angle of the film layer produced by the above method is 0°, the first area presents the first color, the second area presents the third color, and the remaining areas present the fifth color. After tilting at a large angle, the first area presents the second color, the second area presents the fourth color, and the remaining areas present the sixth color, thereby achieving the color effect of three colors on the same surface and large-angle color change, further enhancing the visual impact of the product appearance.

[0068] The present invention also provides a film layer prepared by the above method.

[0069] The present invention also provides a watch, the dial of which includes the film layer described above. The dial is made of sapphire, glass or other materials.

[0070] The present invention further provides a terminal comprising at least a terminal body and a housing, wherein the housing comprises the aforementioned film layer. The terminal includes a smart terminal device such as a mobile phone or tablet computer, wherein the housing may be a glass cover plate, and the film layer is prepared on the outer surface of the glass cover plate using the aforementioned method to enhance the visual impact of the terminal housing.

[0071] Example 1

[0072] like Figure 2 、 Figure 3As shown, in an embodiment of the present invention, it is necessary to make a color film layer on the sapphire dial of a watch, with the goal that: when the angle of incidence is 0°, the outer ring appears red and the inner ring appears blue; when tilted at about 50°, the outer ring becomes orange and the inner ring becomes purple. In order to achieve the above color requirements, the film structure design was carried out using the optical simulation software TFCal. First, the first film layer was designed so that it appears red when the angle of incidence is 0°, and orange when tilted at about 50°. Then, the second film layer was superimposed on the top of the first film layer, so that after the first film layer and the second film layer were superimposed, when viewed from above the second film layer, it appears blue when the angle of incidence is 0°, and purple when tilted at about 50°. Silicon and niobium were selected as materials, silicon oxide was selected as the base layer (the layer bonded to the substrate), and silicon nitride was selected as the outermost layer. The structures of the first and second film layers obtained are as shown below. Figure 4 As shown. The first film layer 10 comprises a seven-layer structure, including, stacked from bottom to top, a first silicon oxide layer 11, a first metal niobium layer 12, a second silicon oxide layer 13, a second metal niobium layer 14, a third silicon oxide layer 15, a niobium oxide layer 16, and a first silicon nitride layer 17. The first silicon oxide layer 11 is disposed opposite the first surface, and the first silicon nitride layer 17 is disposed opposite the second film layer 20. The second film layer includes a second silicon nitride layer 21. The thicknesses of the first silicon oxide layer 11, the first metal niobium layer 12, the second silicon oxide layer 13, the second metal niobium layer 14, the third silicon oxide layer 15, the niobium oxide layer 16, the first silicon nitride layer 17, and the second silicon nitride layer 21 are 10 nm, 50 nm, 70 nm, 11 nm, 93 nm, 94 nm, 10 nm, and 40 nm, respectively. The final Lab values ​​of red are (30.89, 38.63, -10.17), and the Lab values ​​of blue are (23.91, 8.09, -39.9). The first silicon oxide layer 11 serves as a bottom transition layer and can be replaced by other dielectric films such as silicon nitride and silicon carbide. Its thickness can also be 5nm-30nm.

[0073] In this embodiment, a sputtering coating machine is used to prepare the film layer, and the preparation process is as follows:

[0074] (1) The sapphire substrate is sent to the electroplating workshop for electroplating. The sputtering coating machine is evacuated. When the vacuum degree reaches 1.0*10^-3Pa, the oxidation source is started to oxygenate 180SCCM for ion cleaning. The oxidation source power is 2000W and the time is about 2-5 minutes, so that the film layer can better adhere to the substrate.

[0075] (2) Continue to evacuate and wait. When the vacuum reaches 7.0*10^-4Pa, start the coating process. The silicon target power is 7KW, and the argon gas is filled at 250SCCM. The first layer of silicon oxide is 10nm, followed by 50nm of metal niobium, 70nm of silicon oxide, 11nm of metal niobium, 93nm of silicon oxide, 94nm of niobium oxide, and 10nm of silicon nitride. Among them, the metal niobium uses a niobium target. The purity of the silicon target and niobium target must be above 99.99%. The thickness of each layer of coating material cannot exceed + / -3% of the theoretical design thickness. The ultimate goal is to ensure that the color and optical effects of the front and large angles after the film layer is stacked. During the coating process, the oxidation source power is 1000W, and the oxygen filling volume during the silicon oxide and niobium oxide coating process is 120SCCM.

[0076] (3) After the coating is completed, the white sheet material is subjected to a full inspection process, ultrasonic cleaning is performed, and normal acid and alkali solution cleaning can be performed. Then, a circular protective ink layer is screen-printed on the outer ring area. The size ratio of the protective oil hollow window area is 1:1, that is, the ratio of the screen printing screen hollow size to the product hollow size is 1:1, and there is no need for expansion or contraction. The protective ink is a non-water-soluble ink without the addition of a curing agent. After screen printing, the ink layer is baked dry. In the embodiment of the present invention, Seiko's BG001 black ink is selected without the addition of a curing agent.

[0077] (4) The product after screen printing is cleaned with acidic or alkaline solution to prevent ink from contaminating the non-shielded area, and then sent to the sputtering coating machine. The ion source is first cleaned for 5 minutes. When the initial vacuum reaches 7.0*10^-4Pa or below, 40nm thick silicon nitride is sputtered on the entire surface. After sputtering, the middle area turns blue and turns purple when tilted 50°.

[0078] (5) Use Astron, acetone or thinner to remove the protective ink layer to reveal the red color of the outer circle, which turns orange when tilted 50°.

[0079] (6) Prepare AF film on the product surface, conduct quality inspection, and package and ship.

[0080] This embodiment uses silicon and niobium targets, but other materials, such as silicon and titanium, can also be used. The film structure in this embodiment is relatively simple, and more complex film systems can be simulated through optical simulation. However, the overall thickness of the film layer must be controlled to avoid problems such as increased white spots and color deviation caused by excessive film thickness.

[0081] Control Example

[0082] The control example is a control solution of the above embodiment, and its preparation process is as follows:

[0083] First, the entire surface is electroplated with a blue film layer, and then black protective oil is screen-printed in the middle area to protect the blue in the middle. Then, the stripping solution is used to remove the outer color film, and then the entire surface is electroplated with a red composite film. Finally, the inner protective oil area is removed to reveal the blue film layer in the middle.

[0084] like Figure 5 Shown is a schematic diagram of the process flow and effect comparison of the control example and Example 1. The film layer supplemented by the secondary electroplating in the control example is a composite film layer, which is not conducive to the control of production color. Therefore, the color difference between the final produced sample and the target effect is large; and the middle faded plating area is larger than the outer ring, the degreasing area is large, and the loss of labor is high. In contrast, Example 1 of the present invention only requires two full-surface coatings, without the need for additional jigs or complex faded plating processes, which significantly improves production efficiency and finished product yield, and has clear color boundaries and no transition color bands. The color of the final produced sample is very close to the target effect. In summary, the present invention successfully achieves multi-color distribution and large-angle color change effects on the same surface by combining scientific film system design with innovative masking technology. This method is not only simple in process and cost-controllable, but also has good scalability and applicability. It can be widely used in the surface decoration of high-end products such as consumer electronics, watches, and jewelry.

[0085] The present invention provides a novel film preparation method, which has the following significant technical advantages and practical application value compared with the existing technology:

[0086] 1. Achieve multi-color and wide-angle color-changing effects on the same surface: Through the rational design of the composite film structure and the combination of selective masking technology, color differences in multiple areas on the same surface are achieved, and significant color changes are presented at different observation angles, enhancing visual expression.

[0087] 2. Simplify the process flow and improve production efficiency: The two-color effect can be achieved by coating the entire surface twice, without the need for multiple coatings or complicated stripping processes, reducing manual operation links and improving production efficiency and product consistency.

[0088] 3. Clear color boundaries and no transition areas: By precisely controlling the screen printing size and the selection of protective ink, the boundaries between different color areas are ensured to be clear and distinct, avoiding the transition color problem common in traditional methods.

[0089] 4. The film structure is simple and easy to control: The second film layer is a single-layer structure with a thickness of less than 100nm, which facilitates process control and reduces the risk of color instability caused by film thickness deviation.

[0090] 5. Strong applicability and good scalability: This method is not only suitable for two-color patterns, but can also achieve three-color or even multi-color distribution on the same surface by repeating the steps of silk screen printing - coating - ink removal, meeting diverse design needs.

[0091] In summary, the present invention overcomes the problems of complex process, difficult color control, blurred boundaries, etc. in traditional methods, and provides an efficient, controllable and beautiful film preparation solution. It is particularly suitable for surface functionalization treatment of high-end substrates such as sapphire and glass, and has broad market application prospects.

[0092] The above is only a specific embodiment of the present invention and cannot be used to limit the scope of the present invention. Equal changes made by ordinary technicians in this technical field based on this creation, as well as changes well known to technicians in this field, should still fall within the scope of the present invention.

Claims

1. A method for preparing a film layer, characterized in that: The method comprises the following steps: Step S1, using optical simulation software to design the structures of the first film layer and the second film layer so that: The first film layer presents a first color when the incident angle is 0°, and presents a second color when tilted to a larger angle; After the second film layer is superimposed on the outermost layer of the first film layer, it presents a third color when the incident angle is 0°, and presents a fourth color when tilted to a larger angle; Wherein, the first film layer is a composite film layer with no less than three layers; the second film layer is a single-layer structure; Step S2: depositing a first film layer on the entire first surface of the substrate; Step S3: screen printing a protective ink layer on the first area of ​​the first surface, and then baking the protective ink layer; Step S4: depositing a second film layer on the entire surface of the first surface; Step S5: removing the protective ink layer.

2. The film preparation method according to claim 1, characterized in that: The thickness of the first film layer is 300 nm to 400 nm.

3. The film preparation method according to claim 1, characterized in that: After step S5, the following steps are further included: At least one additional film layer is designed to be superimposed on the second film layer using optical simulation software, so that each additional film layer, when superimposed on the original film layer, exhibits a desired color at an incident angle of 0° and after being tilted at a large angle; For each additional film layer, steps S3-S5 are repeated, wherein a protective ink layer is screen-printed in the area to be masked, an additional film layer is deposited on the entire surface, and the protective ink layer is removed.

4. The film preparation method according to claim 1, characterized in that: The protective ink layer has a thickness of 4 μm to 6 μm.

5. The film preparation method according to claim 1, characterized in that: The method of depositing the first film layer and the method of depositing the second film layer are magnetron sputtering coating or evaporation coating.

6. The film preparation method according to claim 1, characterized in that: The first film layer includes a 7-layer structure.

7. The film preparation method according to claim 6, characterized in that: The first film layer includes a first silicon oxide layer, a first metal niobium layer, a second silicon oxide layer, a second metal niobium layer, a third silicon oxide layer, a niobium oxide layer, and a first silicon nitride layer stacked in sequence from bottom to top; the first silicon oxide layer is arranged opposite to the first surface, and the first silicon nitride layer is arranged opposite to the second film layer; the second film layer includes a second silicon nitride layer.

8. A film layer, characterized in that: The method is prepared by any one of claims 1 to 7.

9. A watch, characterized in that: The dial thereof comprises the film layer as claimed in claim 8.

10. A terminal, characterized in that: The terminal comprises at least a terminal body and a shell, wherein the shell comprises the film layer as claimed in claim 8.

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