Preparation process for semi-permeable metal film layer of automobile lamp part

Abstract

The invention relates to the technical field of vacuum coating, in particular to a preparation process for a semi-permeable metal film layer of an automobile lamp part. The process comprises the following steps: S1, cleaning and dedusting the surface of a base material; s2, carrying out cleaning and activating treatment on the cleaned base material by adopting plasma; s3, plating a silicon oxide bottom film on the surface of the activated base material; s4, plating a metal film on the silicon oxide bottom film, and controlling the thickness of the metal film to be 4-7nm so as to realize the effects of static light-proof and light-transmitting when being lightened; and S5, plating a silicon oxide protective film on the surface of the metal film. The metal film prepared by the invention realizes the effects of being light-proof in a static state, being light-transmitting when being lighted up and showing metallic luster on the surface, and is suitable for the surface of a transparent / milk white base material at the same time. In addition, a film thickness monitoring system is introduced, the film thickness is accurately controlled, the process and performance stability is guaranteed, and mass production feasibility is achieved. In addition, by depositing the silicon oxide protective film, the corrosion resistance of the metal film layer is remarkably enhanced, and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of vacuum coating technology, and in particular to a process for preparing a semi-transparent metal film layer for automotive lighting parts. Background Technology

[0002] With the rapid development of the automotive industry, headlights have evolved from single-function components to important exterior decorative parts. Currently, most headlight coating processes involve evaporation coating on black or opaque substrates, resulting in limited effects. There is a growing market demand for a soft, semi-transparent effect that is "opaque when stationary, but translucent when illuminated." "Opaque when stationary, translucent when illuminated" means that when observed under ambient light, the underlying structure is invisible, appearing as an opaque metallic appearance; however, when the internal light source of the headlight is turned on, light can penetrate the coating layer, displaying a predetermined pattern or shape. However, due to high technical barriers, limited material selection, and poor mass production stability, existing technologies lack a mature, reliable, and mass-producible semi-transparent coating solution. Summary of the Invention

[0003] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a stable, reliable, and mass-producible process for preparing semi-transparent metal films for automotive lighting components. A semi-transparent metal film refers to a film with 10% to 30% optical transmittance in the visible light range and a metallic luster on its surface. The metal film prepared by this invention achieves the effect of being statically opaque, translucent when illuminated, and exhibiting a metallic luster on its surface, and is suitable for transparent / milky white substrates.

[0004] The technical solution adopted by this invention to solve its technical problem is: A process for preparing a semi-transparent metal film layer for automotive lamp components specifically includes the following steps: Step S1: Clean and remove dust from the surface of the substrate; Step S2: The cleaned substrate is cleaned and activated using plasma. Step S3: Deposit a silicon oxide substrate film onto the activated substrate surface; Step S4: Deposit a metal film on the silicon oxide substrate, and control the thickness of the metal film to be 4-7 nm to achieve the effect of being opaque when static and transparent when lit. Step S5: Deposit a silicon oxide protective film onto the surface of the metal film.

[0005] Furthermore, in step S1, an electrostatic dust removal gun is used for cleaning, with the gun head 100-150mm away from the substrate surface.

[0006] Furthermore, in step S2, the process parameters for plasma cleaning are: vacuum degree 2-5 Pa, argon flow rate 70-80 sccm, discharge power 4-5 KW, processing time 1-1.5 min, and coating fixture rotation speed 5-7 rpm.

[0007] Furthermore, in step S3, the process parameters for depositing the silicon oxide substrate are: vacuum degree 2-5 Pa, silicone oil flow rate 80-100 sccm, discharge power 3.6-4.5 KW, process time 1-1.5 min, and coating fixture rotation speed 5-7 rpm.

[0008] Furthermore, in step S4, a quartz crystal oscillator is used to monitor the deposition thickness of the metal film in real time, and the thickness of the metal film is controlled within the range of 4 to 7 nm by controlling the amount of film loading and the vacuum degree of the coating chamber.

[0009] Furthermore, in step S4, the metal film is deposited using an evaporation deposition process, the process parameters of which include: evaporation vacuum degree ≤ 2.0 × 10⁻⁶. -3 Pa, pre-melting process current 600~800A, pre-melting time 9~15S; evaporation process current 800~1600A, evaporation time 15~21S, coating fixture speed 25rpm.

[0010] Furthermore, in step S5, the process parameters for depositing the silicon oxide protective film are: vacuum degree 2-5 Pa, argon flow rate 80-90 sccm, discharge power 3.6-4.5 KW, process time 3.5-5 min, and coating fixture rotation speed 5-7 rpm.

[0011] Furthermore, in step S1, the substrate is a transparent or milky white material.

[0012] Furthermore, the metal coating device in step S4 includes a vacuum coating machine, an evaporation source is placed in the inner cavity of the vacuum coating machine, and a substrate to be coated is placed directly above the evaporation source; a quartz crystal oscillator is provided between the evaporation source and the substrate for monitoring the thickness of the metal film, and the quartz crystal oscillator is located outside the substrate (3).

[0013] The beneficial effects of this invention are as follows: This invention has a reasonable design and a simple preparation method, and has the following advantages: (1) Precise optical effect control: By precisely controlling the thickness of the metal film within the nanometer range of 4 to 7 nm and using a quartz crystal oscillator for real-time monitoring, the film layer can achieve a specific semi-transparent effect of "static opaqueness and light transmission when lit", and the optical transmittance is stable within the ideal range of 10% to 30%. (2) Excellent film performance: Through plasma cleaning activation and deposition of silicon oxide substrate, the bonding force between the film and the substrate is greatly enhanced; the outermost silicon oxide protective film effectively isolates air and moisture, significantly improving the corrosion resistance and durability of the metal film. (3) Wide applicability: This process is applicable to transparent and milky white substrates, which broadens the range of material choices for automotive lighting parts design; (4) High feasibility for mass production: The process parameters of each step have been optimized and specified, forming a stable, controllable and repeatable process flow, which provides a reliable guarantee for large-scale industrial production. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a flowchart of the preparation process of the present invention; Figure 2 This is a schematic diagram of the metal film plating device used in step S4 of the present invention; Figure 3 This is a schematic diagram of the structure of a quartz crystal oscillator. Figure 4 It is a graph showing the relationship between the thickness of the metal film and the optical transmittance; Figure 5 This is a graph showing the relationship between the frequency of a quartz crystal oscillator and the film thickness. Figure 6 These are test results of the film adhesion of the samples prepared in Example 1, Comparative Example 1, and Comparative Example 2. Figure 7 These are corrosion resistance test images of the samples prepared in Example 1 and Comparative Example 3.

[0017] Among them, 1. vacuum coating machine, 2. evaporation source, 3. substrate, and 4. quartz crystal oscillator. Detailed Implementation

[0018] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1 The process for preparing a semi-transparent metal film layer for automotive lamp components, as shown, specifically includes the following steps: Step S1: Clean and remove dust from the surface of the substrate; Step S2: Use plasma to clean and activate the cleaned substrate; Step S3: Deposit a silicon oxide substrate film onto the activated substrate surface; Step S4: Deposit a metal film on the silicon oxide substrate, controlling the thickness of the metal film to be 4-7 nm, so as to achieve the effect of being opaque when static and transparent when lit. Step S5: Deposit a silicon oxide protective film on the surface of the metal film.

[0022] The following is a detailed description of each step: (1) Step S1: Personnel use a handheld electrostatic dust removal gun to blow away static electricity and adsorbed dust from the surface of the transparent substrate.

[0023] The specific parameters are as follows: the reference model of the handheld electrostatic dust collector is AAC HFG10, the output voltage of the dust collector is AC2.0KV, and the airflow rate of the dust collector is 89~314L / min.

[0024] In this step, keeping the electrostatic air gun nozzle 100-150mm away from the surface of the substrate to be cleaned and extending the blowing time can effectively improve the cleanliness of the substrate surface and remove dust and impurity particles adsorbed on the substrate surface.

[0025] (2) Step S2 uses a vacuum coating equipment to perform plasma cleaning treatment on the surface of the transparent substrate through the glow discharge effect in a vacuum environment, achieving three main functions: Surface cleaning: Highly active particles in plasma can effectively remove contaminants from the surface of materials through chemical bond breaking, ultimately converting them into gaseous small molecule products.

[0026] Surface activation: Ion bombardment induces lattice defects on the material surface, leading to the formation of nanoscale micro-uneven morphology and increasing surface temperature. This micro / nano rough structure effectively increases the mechanical interlocking contact area between the coating material and the substrate, thereby significantly enhancing the physical bonding strength between them.

[0027] Modification treatment: Oxygen free radicals in plasma can react with hydrocarbon groups on the substrate surface to generate polar functional groups such as hydroxyl and carboxyl groups. These functional groups can not only improve surface wettability, but also form chemical bonds with the coating material, enhancing the interfacial bonding strength.

[0028] The specific parameters are as follows: the low vacuum degree of the vacuum coating machine is 2-5 Pa, the argon flow rate is 70-80 sccm, the discharge power is 4-5 KW, the process time is 1-1.5 min, and the rotation speed of the coating fixture is 5-7 rpm.

[0029] In this step, by appropriately increasing the plasma density and improving the radio frequency power, the activity and cleanliness of the substrate surface can be effectively enhanced, thereby improving the adhesion between the substrate and the film layer and significantly reducing the problem of point defects in the metal layer caused by the shedding of particles from the substrate surface.

[0030] (3) In step S3, the silicone oil is decomposed by using the glow discharge effect in a vacuum environment through a vacuum coating machine, and then a silicon oxide film is deposited on the surface of the substrate, thereby effectively improving the bonding force between the substrate and the film.

[0031] The specific parameters are as follows: when depositing a silicon oxide base film, the discharge low vacuum degree of the vacuum coating machine is 2-5 Pa, the silicone oil flow rate is 80-100 sccm, the discharge power is 3.6-4.5 KW, the process time is 1-1.5 min, and the rotation speed of the coating fixture is 5-7 rpm.

[0032] In this step, increasing the discharge power can enhance the ionization effect of the silicone oil, thereby forming a more uniform and dense microstructure of the silicon oxide film on the substrate surface and significantly improving the bonding strength between the film layers.

[0033] (4) In step S4, the thickness of the metal film deposited on the transparent substrate is usually between 10 and 150 nm. When the thickness of the metal film is greater than 70 nm, the whole film is opaque; when the thickness of the metal film is less than or equal to 70 nm, it is transparent.

[0034] like Figure 4As shown, transmittance and film thickness exhibit a near-exponentially decreasing negative correlation; the higher the film thickness, the lower the transmittance. Transmittance initially decreases rapidly with increasing film thickness, then gradually stabilizes. For the automotive lighting decoration industry, a transmittance of 10%–30% is sufficient for the material to achieve a good semi-transparent effect, meeting the requirement of being opaque when static and translucent when illuminated. In this case, the film thickness needs to be controlled within the range of 4–7 nm.

[0035] In this step, a vacuum coating process is used. The metal film material is heated by thermal evaporation in a high vacuum environment, so that metal atoms or molecules are deposited on the surface of the substrate to form a uniform metal film layer with a specific thickness. The specific parameters are: evaporation vacuum degree ≤2.0×10-3Pa; pre-melting process current 600~800A; pre-melting process time 9~15S; evaporation process current 800~1600A; evaporation process time 15~21S; coating fixture rotation speed 25rpm.

[0036] In the evaporation coating process, key factors affecting the evaporation rate include the amount of film loaded and the vacuum level of the coating chamber. Precisely controlling the amount of film loaded can effectively control the film thickness, thereby adjusting the optical transmittance. Increasing the vacuum level of the coating chamber significantly increases the mean free path of the film molecules, thus accelerating the evaporation process. Based on this principle, in this process, by precisely controlling the amount of evaporated film and the vacuum level of the coating chamber, the thickness of the metal film can be maintained between 4 and 7 nm, achieving optimal semi-transparency.

[0037] like Figure 2 and Figure 3 As shown, the metal film coating device in step S4 includes a vacuum coating machine 1. An evaporation source 2 is placed inside the vacuum coating machine 1, and a substrate 3 to be coated is positioned directly above the evaporation source 2. A quartz crystal oscillator 4 for monitoring the thickness of the metal film is positioned between the evaporation source 2 and the substrate 3. The quartz crystal oscillator 4 is located outside the substrate 3 and does not interfere with the coating process of the substrate 3. A frequency monitor is connected to the quartz crystal oscillator 4.

[0038] like Figure 5 As shown, step S4 uses a quartz crystal oscillator 4 to monitor the deposition thickness of the thin film in real time by measuring the change in the resonant frequency. Its principle is based on the piezoelectric effect and resonant characteristics of quartz crystals, and it features high precision, real-time performance, and non-destructive operation. When the thickness of the quartz crystal oscillator d increases by Δd, its resonant frequency f changes by Δf (frequency constant N = 1670 Hz). "-" indicates that the frequency of the chip crystal oscillator decreases as the film thickness increases, i.e., equation (1): ; Since various film materials are deposited, and not all of them are quartz crystal materials, it is necessary to convert the quartz crystal thickness increment Δd into the film thickness increment Δd through mass transformation.M That is, equation (2): Δm=A*ρ M *Δd M = A*ρ*Δd; Where A is the area to be plated, ρ M ρ is the film density, where ρ is the density of quartz, which is equal to 265 g / cm³. 3 .

[0039] Equation (2) above can be simplified to obtain equation (3), that is: Δd=(ρ M / ρ)* Δd M ; Substituting equation (3) into equation (1), we obtain equation (4): Δf=-N / d 2 *(ρ M / ρ)* Δd M .

[0040] (5) S5 utilizes the glow discharge effect generated by the vacuum coating machine to cause the silicone oil to undergo ionization and decomposition reaction through plasma excitation, thereby promoting the chemical deposition of active silicon groups on the surface of the metal film layer, and finally forming a silicon oxide protective film with excellent protective performance.

[0041] The specific parameters are as follows: discharge low vacuum degree of 2-5 Pa; argon flow rate of 80-90 sccm; discharge power of 3.6-4.5 W; process time of 3.5-5 min; and coating fixture rotation speed of 5-7 rpm. In this step, by depositing a protective coating, the metal film is effectively isolated from air and moisture, thereby avoiding oxidation or corrosion reactions and significantly improving its durability and service life.

[0042] Comparative Example 1 Compared with Example 1, this comparative example omits step S2, plasma cleaning and activation.

[0043] Comparative Example 2 Compared with Example 1, this comparative example omits step S3, which involves depositing a silicon oxide substrate.

[0044] Comparative Example 3 Compared with Example 1, this comparative example omits step S5 (protective film).

[0045] Test case (1) Bonding force experiment Example 1: The film adhesion of the samples prepared in Comparative Examples 1 and 2 was tested (e.g., using the cross-cut adhesion test). The test results are as follows: Figure 6 As shown in Table 1.

[0046] Table 1. Test results of samples prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0047] Depend on Figure 6 Table 1 demonstrates that the multi-layer structure design of the present invention significantly improves adhesion.

[0048] (2) Corrosion resistance test The samples prepared in Example 1 and Comparative Example 3 were tested in salt spray or high temperature and humidity tests, and the results are as follows: Figure 7 As shown.

[0049] Depend on Figure 7 It can be seen that the sample prepared in Comparative Example 3 was corroded during the test. The sample prepared in Example 1 had a protective film and was not corroded, thus demonstrating that the protective film plays a key role in improving durability.

[0050] In summary, the metal film prepared by the above-described process achieves the effect of being statically opaque, translucent when illuminated, and exhibiting a metallic luster, and is suitable for transparent / milky white substrates. Furthermore, the introduction of a film thickness monitoring system allows for precise control of the film thickness, ensuring the stability of the process and performance, and making mass production feasible. In addition, the deposition of a silicon oxide protective film significantly enhances the corrosion resistance of the metal film and extends its service life.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing a semi-transparent metallic film layer for automotive lamp parts, characterized in that: Specifically, the steps include the following: Step S1: Clean and remove dust from the surface of the substrate; Step S2: The cleaned substrate is cleaned and activated using plasma. Step S3: Deposit a silicon oxide substrate film onto the activated substrate surface; Step S4: Deposit a metal film on the silicon oxide substrate, and control the thickness of the metal film to be 4-7 nm to achieve the effect of being opaque when static and transparent when lit. Step S5: Deposit a silicon oxide protective film onto the surface of the metal film.

2. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S1, an electrostatic dust removal gun is used for cleaning, with the gun head 100-150mm away from the substrate surface.

3. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S2, the process parameters for plasma cleaning are: vacuum degree 2-5 Pa, argon flow rate 70-80 sccm, discharge power 4-5 KW, processing time 1-1.5 min, and coating fixture rotation speed 5-7 rpm.

4. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S3, the process parameters for depositing the silicon oxide substrate are: vacuum degree 2-5 Pa, silicone oil flow rate 80-100 sccm, discharge power 3.6-4.5 KW, process time 1-1.5 min, and coating fixture rotation speed 5-7 rpm.

5. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S4, a quartz crystal oscillator is used to monitor the deposition thickness of the metal film in real time, and the thickness of the metal film is controlled within the range of 4 to 7 nm by controlling the amount of film loading and the vacuum degree of the coating chamber.

6. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S4, the metal film is deposited using an evaporation deposition process, the process parameters of which include: evaporation vacuum degree ≤ 2.0 × 10⁻⁶. -3 Pa, pre-melting process current 600~800A, pre-melting time 9~15S; evaporation process current 800~1600A, evaporation time 15~21S, coating fixture speed 25rpm.

7. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S5, the process parameters for depositing the silicon oxide protective film are: vacuum degree 2-5 Pa, argon flow rate 80-90 sccm, discharge power 3.6-4.5 KW, process time 3.5-5 min, and coating fixture rotation speed 5-7 rpm.

8. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 1, characterized in that: In step S1, the substrate is a transparent or milky white material.

9. The process for preparing a semi-transparent metal film layer for automotive lamp parts according to claim 5, characterized in that: The metal coating device in step S4 includes a vacuum coating machine (1), an evaporation source (2) is placed in the inner cavity of the vacuum coating machine (1), and a substrate (3) to be coated is placed directly above the evaporation source (2); a quartz crystal oscillator (4) for monitoring the thickness of the metal film is provided between the evaporation source (2) and the substrate (3), and the quartz crystal oscillator (4) is located outside the substrate (3).

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