Preparation method of high-precision metal mask

Abstract

The present application provides a method for preparing a high-precision metal mask used in the production of an OLED display panel, comprising the steps of forming an oxide film on the surface of a nickel-iron alloy sample. By ultrasonically cleaning and then alkali-treating the nickel-iron alloy sample, an oxide film mainly composed of ferroferric oxide and nickel oxide can be formed on the surface of the nickel-iron alloy. The proportion of ferroferric oxide in the oxide film is higher, and the structure is more uniform. The structure of the oxide film can effectively block the penetration of oxygen and moisture, and can keep the surface of the nickel-iron alloy sample intact during static storage, transportation, cleaning, etc. The steps of ultrasonically cleaning and alkali-treating the nickel-iron alloy sample can be performed immediately after the nickel-iron alloy is produced in a metal factory; or it can be performed immediately after the nickel-iron alloy is purchased from a high-precision metal mask manufacturer and transported to an FMM manufacturer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for preparing a high-precision metal mask used in the production of an OLED display panel. Background Art

[0002] Masks primarily serve as pattern transfer masters and are typically customizable. Masks are categorized as photomasks (light masks) and high-precision metal masks (shadow masks). Photomasks, made of high-purity quartz glass, are primarily used in the photolithography process to create circuits. Fine metal masks (FMMs) are key components in OLED display manufacturing, used for the precise deposition of organic materials to form pixel patterns.

[0003] Currently, the mainstream production process of FMM is wet etching, which uses ultra-thin Invar alloy (or nickel-iron alloy) as raw material, transfers the pattern through photolithography, and then undergoes two chemical etchings to form a dense hole structure. After that, it is packaged and shipped after precise inspection.

[0004] After cleaning and drying, nickel-iron alloy materials or FMM products have no protective layer on their surface. After long-term static storage or affected by environmental humidity, rust is likely to grow on the surface of the nickel-iron alloy. The surface of nickel-iron alloy finished products is easily damaged during static storage and transportation, resulting in a decrease in product quality and reliability.

[0005] Traditional protection methods such as physical isolation and chemical coatings have problems with insufficient protection or difficulty in removal, which leads to problems in the subsequent organic vapor deposition process of the FMM finished product; chemical coatings may decompose and become ineffective under certain conditions, and the complex removal process may introduce new sources of pollution, affecting the surface quality of the FMM finished product. Summary of the Invention

[0006] The purpose of this application is to provide a method for preparing a high-precision metal mask used in the production of OLED display panels. The method can protect nickel-iron alloy and prevent the surface of the nickel-iron alloy finished product from being easily damaged during static storage and transportation, resulting in a decrease in the quality and reliability of the high-precision metal mask product.

[0007] The present application provides a method for preparing a high-precision metal mask used in the production of an OLED display panel, comprising:

[0008] S01, raw material preparation and pre-treatment, providing nickel-iron alloy samples that can be processed later;

[0009] S01, raw material preparation and pre-processing, including:

[0010] Providing a nickel-iron alloy sample and performing ultrasonic cleaning on the nickel-iron alloy sample, wherein the nickel-iron alloy sample has a thickness of less than 30 microns;

[0011] The nickel-iron alloy sample after ultrasonic cleaning was treated with an alkali solution containing NaOH. The alkali treatment included pretreatment, mid-stage treatment and post-treatment. The concentrations of NaOH in the three treatment stages were C 预 、C 中段 、C 后 ; The treatment temperatures in the three treatment stages are T 预 、T 中段 、T 后 ; The reaction times in the three treatment stages are t 预 , t 中段 , t 后 , and satisfy:

[0012] C 中段 >C 预 >C 后 ;T 中段 >T 预 >T 后 ;t 中段 >t 预 >t 后 ;as well as,

[0013] The nickel-iron alloy sample after the alkali treatment is passivated to form an oxide film, wherein the oxide film includes nickel oxide and ferrosoferric oxide.

[0014] In one embodiment,

[0015] During the pretreatment process, a NaOH solution with a concentration of 5wt%-8wt% is used;

[0016] During the middle stage treatment, a NaOH solution with a concentration of 9wt%-14wt% is used;

[0017] In the post-treatment process, a NaOH solution with a concentration of 3wt%-5wt% is used.

[0018] In one embodiment, the treatment temperature during the pretreatment process is 75° C.-85° C., and the treatment time is 30 minutes;

[0019] The treatment temperature during the middle stage treatment is 95°C-110°C, and the treatment time is 110 minutes-140 minutes;

[0020] The treatment temperature in the post-treatment process is 55° C.-65° C., and the treatment time is 8 minutes-15 minutes.

[0021] In one embodiment, during the middle stage treatment, the alkaline solution includes a mixed solution of NaOH and sodium lauryl sulfate, wherein the concentration of NaOH in the mixed solution is 12 wt %-14 wt %, and the concentration of sodium lauryl sulfate is 0.1 wt %-0.5 wt %.

[0022] In one embodiment, the method further comprises: S02, performing photoresist coating and pattern transfer on the surface of the nickel-iron alloy sample;

[0023] In step S02, deoxidation treatment is first performed, followed by photoresist coating and pattern transfer;

[0024] The deoxidation treatment uses an acid solution including HCl to remove the oxide film. The deoxidation treatment includes: softening treatment, main treatment and flattening treatment; the concentration of HCl in the three treatment stages is C 软化 、C 主 、C 平整化 ; The treatment temperatures in the three treatment stages are T 软化 、T 主 、T 平整化 ; The reaction times in the three processing stages are t 软化 , t 主 , t 平整化 , and satisfy:

[0025] C 主 >C 软化 >C 平整化 ;T 主 >T 平整化 >T 软化 ;t 主 >t 平整化 >t 软化 .

[0026] In one embodiment, a HCl solution with a concentration of 10 wt % to 14 wt % is used during the softening process;

[0027] The main treatment process uses a HCl solution with a concentration of 14wt%-16wt%;

[0028] During the planarization process, an HCl solution with a concentration of 2wt%-7wt% is used.

[0029] In one embodiment, the treatment temperature during the softening treatment is 15° C.-25° C., and the treatment time is 1.5 minutes-3 minutes;

[0030] The treatment temperature in the main treatment process is 45°C-55°C, and the treatment time is 28 minutes-35 minutes;

[0031] The treatment temperature during the planarization treatment is 30° C.-40° C., and the treatment time is 10 minutes-15 minutes.

[0032] In one embodiment, the oxide film has a thickness of 100 nm to 200 nm.

[0033] In one embodiment, the passivation treatment after the alkali treatment comprises:

[0034] Washing the alkali-treated nickel-iron alloy sample with deionized water;

[0035] The nickel-iron alloy sample after being washed with deionized water is placed in a dilute nitric acid solution with a concentration of 3wt%-6wt% for passivation treatment at a treatment temperature of 15°C-25°C and a treatment time of 18 minutes-22 minutes.

[0036] In one embodiment, it further includes:

[0037] S03, chemically etching the two surfaces of the nickel-iron alloy sample to form etching patterns on the first surface and the second surface; and

[0038] S04, removing the photoresist on the surface of the nickel-iron alloy sample on which the etching patterns on both sides have been formed, and performing post-processing on the nickel-iron alloy sample to form the high-precision metal mask.

[0039] In one embodiment, after step S04, the method further includes:

[0040] Ultrasonic cleaning of the completed high-precision metal mask;

[0041] The high-precision metal mask after ultrasonic cleaning is subjected to an alkali treatment, wherein the alkali treatment includes: pretreatment, mid-stage treatment, and post-treatment; an alkali solution including NaOH is used during the alkali treatment; the mid-stage treatment includes using an alkali solution with a concentration of 9wt%-14wt%, a treatment temperature of 95°C-105°C, and a treatment time of 110 minutes-130 minutes; and,

[0042] The high-precision metal mask after alkali treatment is passivated to form an oxide film, which includes nickel oxide and ferrosoferric oxide.

[0043] The method for preparing a high-precision metal mask used in the production of an OLED display panel of the present application has at least the following advantages or beneficial effects:

[0044] 1. The present application provides a method for preparing a high-precision metal mask used in the production of OLED display panels. The key step in forming an oxide film includes alkali treatment. The alkali treatment process is divided into three steps. The pretreatment can first remove surface dirt (grease and impurities), the mid-stage treatment can more efficiently achieve the growth of the oxide film, and the post-treatment is used to grow the top oxide film. The nickel-iron alloy sample after alkali treatment is passivated to form a uniform oxide film on the surface. The oxide film includes nickel oxide and ferroferric oxide. The alkali treatment scheme involved in this application can ensure the continuous growth of Fe3O4 in the oxide film, avoid natural oxidation to form Fe2O3, and facilitate the removal of the surface oxide film in subsequent processes.

[0045] 2. The alkali treatment described in this application includes pretreatment, mid-stage treatment, and post-treatment, which can better promote the uniform growth of the oxide film, making the oxide film have a good protective effect (the surface of the nickel-iron alloy material is not corroded by water vapor, etc., and surface friction is reduced). The technical solution for alkali treatment provided in this application, the concentration difference, treatment time difference, and temperature difference in the three steps of the alkali treatment process, combined together, can further facilitate the formation of a protective oxide film on the surface of the nickel-iron alloy sample. This can be specifically reflected in the roughness or thickness in the subsequent examples.

[0046] 3. This application also includes passivation treatment after alkali treatment, which helps to optimize the surface properties of the oxide film on the one hand, and helps to completely remove the alkaline ions (Na + OH - ), to avoid subsequent local electrochemical corrosion caused by residues.

[0047] 4. In step S02 of this application, a deoxidation treatment is performed before photoresist coating and pattern transfer. Specifically, deoxidation treatment is performed before the high-precision metal mask production process begins to prevent the negative impact of oxide films on the FMM product production process. Since the two chemical etching processes in the FMM production process form an etched pattern with small holes and an etched pattern with large holes, the etching solution ferric chloride is generally used in this etching process. If the oxide film is not removed before the FMM production process begins, the oxygen ions in the oxide film will prevent the ferric chloride from replacing iron ions. The rate and efficiency of ferric chloride replacing iron in nickel-iron alloys differ from that of ferric chloride replacing iron ions in ferroferric oxide. Furthermore, since the production process of the first surface (small holes) and second surface (large holes) of the FMM product requires a design accuracy within a range of ±3 microns, deoxidation treatment is performed before the high-precision metal mask production process begins to prevent the impact of the hundreds-nanometer-thick oxide film on FMM production and design accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0049] Figure 1 A schematic flow chart of a method for preparing a high-precision metal mask used in the manufacture of an OLED display panel provided in an embodiment of the present application;

[0050] Figure 2 Schematic diagram of XRD of the nickel-iron alloy shown in Comparative Examples 1 and 2 of the present application;

[0051] Figure 3 This is a schematic diagram of XRD of an oxide film formed on the alloy surface after alkali treatment during the preparation of the high-precision metal mask illustrated in Examples 1 to 4 of the present application;

[0052] Figure 4 Schematic diagram of SEM analysis of the thickness of the oxide film formed in Example 1 of the present application;

[0053] Figure 5 Schematic diagram of SEM analysis of the thickness of the oxide film formed in Example 2 of the present application;

[0054] Figure 6 Schematic diagram of SEM analysis of the thickness of the oxide film formed in Example 3 of the present application;

[0055] Figure 7 Schematic diagram of SEM analysis of the thickness of the oxide film formed in Example 4 of the present application;

[0056] Figure 8 Schematic diagram of the surface roughness of the nickel-iron alloy sample in Comparative Example 2 provided in this application;

[0057] Figure 9 This is a schematic diagram of the surface roughness of the nickel-iron alloy sample in Example 3 provided in this application. DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0059] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0060] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0061] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended only to facilitate the description of this application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting this application. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0062] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0063] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0064] The current process flow for high-precision metal masks for OLEDs includes: the metal factory produces nickel-iron alloy; the nickel-iron alloy is transported to a high-precision metal mask (FMM) manufacturer, where it is processed and manufactured to form a standard FMM; the standard FMM is transported to the OLED panel factory, where the OLED panel factory uses the standard FMM to evaporate the organic light-emitting material.

[0065] See also Figure 1The present application provides a method for preparing a high-precision metal mask used in the production of an OLED display panel, comprising:

[0066] S01, Raw Material Preparation and Pre-treatment: Providing nickel-iron alloy samples ready for subsequent processing. High-precision metal masks for OLEDs typically use ultra-thin Invar alloy (also known as nickel-iron alloy) as raw material. This step requires the provision of nickel-iron alloy materials suitable for subsequent processing steps before fabrication at the FMM fabrication plant. Specific material preparation includes the production and transportation of nickel-iron alloy materials, as well as cleaning and surface treatment.

[0067] S02, coating the surface of the nickel-iron alloy sample with photoresist and transferring the pattern. This step includes coating, exposing, and developing the photoresist on both surfaces of the nickel-iron alloy material to transfer the pattern to the photoresist. In this step, the first and second surfaces of the nickel-iron alloy material can be coated with photoresist, exposed, and developed simultaneously.

[0068] S03, performing a first chemical etching on the first surface of the nickel-iron alloy sample to form an etching pattern on the first surface. In this step, the first etching is performed on the first surface of the nickel-iron alloy material to form a small opening (small hole).

[0069] A second chemical etching is performed on the second surface of the nickel-iron alloy sample to form an etching pattern on the second surface. In this step, a small opening protective film is formed on the first surface of the nickel-iron alloy material, and a second chemical etching is performed on the second surface of the nickel-iron alloy material to form a large opening (macropore).

[0070] S04: Remove the photoresist from the surface of the nickel-iron alloy sample, where the etched patterns have been formed on both sides. Post-process the nickel-iron alloy sample to form a high-precision metal mask for OLEDs. In this step, the photoresist or other thin film used for the second chemical etching is stripped. Post-processing includes surface cleaning, visual inspection, TPCD (Total Pitch and Critical Dimension) inspection, AOI (Automated Optical Inspection), packaging, and shipping.

[0071] Among them, S01, raw material preparation and pre-processing, includes:

[0072] A nickel-iron alloy sample is provided and ultrasonically cleaned, wherein the thickness of the nickel-iron alloy sample is less than 30 microns. The thickness of the nickel-iron alloy material used for preparing the high-precision metal mask in this step can be set to 23 microns, 25 microns, 28 microns or other thicknesses.

[0073] The nickel-iron alloy sample after ultrasonic cleaning is subjected to alkali treatment, and the alkali treatment includes: pretreatment, mid-stage treatment and post-treatment. An alkali solution including NaOH is used in the alkali treatment process. The concentration of NaOH in the alkali solution used in the mid-stage treatment process is higher than the concentration of NaOH in the alkali solution used in the pretreatment process. The concentration of NaOH in the alkali solution used in the pretreatment process is higher than the concentration of NaOH in the alkali solution used in the post-treatment process. The treatment temperature used in the mid-stage treatment process is higher than the treatment temperature used in the pretreatment process. The treatment temperature used in the pretreatment process is higher than the treatment temperature used in the post-treatment process. The reaction time of the mid-stage treatment process is longer than the reaction time of the pretreatment process. The reaction time of the pretreatment process is longer than the reaction time of the post-treatment process.

[0074] The nickel-iron alloy sample after the alkali treatment is passivated to form an oxide film, wherein the oxide film includes nickel oxide and ferrosoferric oxide. In this step, the passivation treatment may include deionized water cleaning and acid washing.

[0075] In the present embodiment, the key step of forming the oxide film provided includes alkali treatment, and the alkali treatment process is divided into three steps. Pretreatment can first remove surface dirt (grease and impurities), mid-stage treatment can more efficiently achieve the growth of the oxide film, and post-treatment is carried out to grow the top oxide film. Post-treatment can neutralize residual alkali solution and reduce film defects. The nickel-iron alloy sample after alkali treatment is passivated to form a surface uniform oxide film, which includes nickel oxide and ferrosoferric oxide. The alkali treatment scheme involved in this embodiment can ensure the continuous growth of Fe3O4 in the oxide film, avoid natural oxidation to form Fe2O3, and also facilitate the removal of the surface oxide film in subsequent processes. The alkali treatment in the embodiment of the present application includes: pretreatment, mid-stage treatment and post-treatment, which can better promote the uniform growth of the oxide film, so that the oxide film has a good protective effect (the surface of the nickel-iron alloy material will not be corroded by water vapor, etc., reducing surface friction). The technical solution for alkali treatment provided in this application, the combination of the concentration difference, treatment time difference and temperature difference in the three steps of the alkali treatment process can be more conducive to the formation of a protective oxide film on the surface of the nickel-iron alloy sample, which can be specifically reflected in the roughness or thickness in subsequent embodiments.

[0076] In existing technology, nickel-iron alloys naturally form a thin oxide layer when exposed to air. This oxide layer is the inevitable result of metal exposure to oxygen. This naturally formed thin oxide layer consists of FeO (ferrous oxide), Fe2O3 (hematite), and NiO. The mixture ratios of these three are uneven, with the Fe oxide and Ni oxide randomly distributed, making them difficult to remove. Removal of this naturally formed thin oxide layer requires the intervention of strong acids or bases, as well as high temperatures, and the reaction process is difficult to control.

[0077] In the specific step S01 of the present application, after ultrasonic cleaning, the nickel-iron alloy sample is subjected to alkali treatment, which can form an oxide film mainly composed of Fe3O4 (magnetite) and NiO (nickel oxide) on the surface of the nickel-iron alloy. The Fe3O4 ratio in the oxide film is higher and the structure is more uniform. In addition, the Fe3O4 film layer generated by the alkali treatment is loose and porous, has weak bonding strength, and Fe 2+ It has high activity and is easier to remove in the subsequent oxide film removal / stripping than Fe2O3 formed by natural oxidation.

[0078] In this step, the oxide film formed on the surface of Renickel is Fe with spinel structure o . In this step, the oxide film formed on the surface of Renickel is thicker, can reach tens to hundreds of nanometers, and the oxide film formed in this solution can reach the thickness of 100nm-200nm. In this step, the structure of the oxide film formed on the surface of Renickel can effectively block oxygen, moisture penetration. In this step, the oxide film formed by the mode of chemical reaction on the surface of Renickel, is combined by chemical bond between this oxide film and Renickel.

[0079] Furthermore, in the specific step S01 of the present application, the steps of providing the nickel-iron alloy sample and performing ultrasonic cleaning and alkaline treatment can be performed immediately after the nickel-iron alloy is produced at a metal factory; or the steps of purchasing the nickel-iron alloy from a high-precision metal mask (FMM) manufacturer and transporting it to the FMM manufacturer can be performed immediately. In this embodiment, the purpose is to ensure that the nickel-iron alloy sample has an oxide layer on its surface during static storage, transportation, cleaning, etc.

[0080] In one embodiment, pretreatment includes using a 5-8wt% NaOH solution for 25-35 minutes at a temperature of 75-85°C to remove grease and impurities from the surface of the material. Mid-stage treatment includes using a 9-14wt% alkaline solution at a temperature of 95-110°C for 110-140 minutes. Post-treatment includes using a 3-5wt% NaOH solution for 8-15 minutes at a temperature of 55-65°C to facilitate subsequent stripping of the oxide film.

[0081] In one embodiment, during the alkali treatment process, a mixed solution of NaOH and sodium dodecyl sulfate is prepared, wherein the concentration of NaOH in the mixed solution is 12wt%-14wt%, and the concentration of sodium dodecyl sulfate is 0.1wt%~0.5wt%. In this embodiment, the inclusion of sodium dodecyl sulfate at a concentration of 0.1wt%~0.5wt% as a surfactant in the alkali solution can reduce the surface tension of the solution, improve the wettability of the alkali solution on the alloy surface, and make the oxide film grow more uniformly. In other embodiments, NaNO3 can be doped into the alkali solution to provide an oxidizing environment and promote the uniformity of the oxidation reaction on the metal surface. The alkali solution formed by the mixture of NaOH and NaNO3 can inhibit local over-corrosion and reduce surface defects. In other embodiments, Na2SiO3 can be doped into the alkali solution. The alkali solution formed by the mixture of NaOH and Na2SiO3 can protect the substrate from excessive dissolution in the high-temperature alkali solution and enhance the bonding force between the oxide film and the substrate.

[0082] In one embodiment, the thickness of the oxide film formed on the surface of the nickel-iron alloy material after the alkali treatment is 100 nm to 200 nm. In some embodiments, the thickness of the oxide film is 120 nm, 135 nm, 142 nm, 147 nm, 154 nm, 176 nm, or 189 nm.

[0083] In one embodiment, the passivation treatment after the alkali treatment includes: washing the nickel-iron alloy sample after the alkali treatment with deionized water, and placing the nickel-iron alloy sample after the deionized water washing in a dilute nitric acid solution with a concentration of 5wt% for passivation treatment for 20 minutes.

[0084] In this embodiment, the passivation treatment after the alkali treatment helps to optimize the surface properties of the oxide film, and on the other hand helps to completely remove the alkaline ions (Na + OH - ), to avoid subsequent local electrochemical corrosion caused by residues.

[0085] In one embodiment, after removing the oxide film, the surface roughness of the nickel-iron alloy sample is in the range of 0.15 μm to 0.30 μm. In some embodiments, the surface roughness of the nickel-iron alloy sample is 0.15 μm, 0.17 μm, 0.18 μm, 0.20 μm, 0.22 μm, 0.23 μm, 0.26 μm, and 0.29 μm.

[0086] In step S02, deoxidation treatment is first performed, and then photoresist coating and pattern transfer are performed. Specifically, deoxidation treatment is performed before the high-precision metal mask preparation process begins. The deoxidation treatment includes: softening treatment, main treatment and planarization treatment. The deoxidation treatment uses an acid solution including HCl. The concentration of HCl in the acid solution used in the main treatment process is higher than the concentration of HCl in the acid solution used in the softening treatment process. The concentration of HCl in the acid solution used in the softening treatment process is higher than the concentration of HCl in the acid solution used in the planarization treatment process. The treatment temperature used in the main treatment process is higher than the treatment temperature used in the planarization treatment process. The treatment temperature used in the planarization treatment process is higher than the treatment temperature used in the softening treatment process. The reaction time of the main treatment process is longer than the reaction time of the planarization treatment process. The reaction time of the planarization treatment process is longer than the reaction time of the softening treatment process.

[0087] In this step, deoxidation is performed before the high-precision metal mask production process begins to prevent the oxide film from negatively impacting the FMM product production process. Since the two chemical etching processes in the FMM production process form an etched pattern with small holes and an etched pattern with large holes, the etching solution ferric chloride is typically used in this etching process. If the oxide film is not removed before the FMM production process begins, the oxygen ions in the oxide film will prevent the ferric chloride from replacing the iron ions. The rate and efficiency of ferric chloride replacing iron in nickel-iron alloys differ from that of ferric chloride replacing iron ions in ferroferric oxide. Furthermore, since the production process for the first surface (small holes) and second surface (large holes) of the FMM product requires a design accuracy within a range of ±3 microns, deoxidation is performed before the high-precision metal mask production process begins to prevent the oxide film, which is hundreds of nanometers thick, from affecting the production and design accuracy of the FMM.

[0088] In this embodiment, the ferronickel alloy sample can be oxidized by undergoing an alkali treatment immediately after production at the metal factory to form an oxide film. Before being transported from the metal factory to the FMM factory for FMM production, this oxide film can fully protect the surface of the ferronickel alloy sample during processes such as standing, storage, transportation, coiling, and cleaning. Before the actual production of FMM products, the ferronickel alloy sample is deoxidized to remove the oxide film on the ferronickel alloy surface.

[0089] In one embodiment, the deoxidation process includes a softening treatment, a main treatment, and a flattening treatment. The softening treatment involves mixing hydrochloric acid (HCl) and nitric acid (HNO3) in a mass ratio of 2.5:1, diluting the mixture to a total acid concentration of 10%-14%, controlling the temperature at 15°C-25°C, and treating for 1.5-3 minutes. The main treatment involves treating the sample in a 14wt%-16wt% hydrochloric acid solution at a temperature of 45°C-55°C for 28-35 minutes. The deoxidation treatment is used to remove the oxide film on the surface of the nickel-iron alloy sample. The flattening treatment involves treating the sample in a 2wt%-7wt% hydrochloric acid solution at a temperature of 30°C-40°C for 10-15 minutes. During the flattening treatment, a corrosion inhibitor, hexamethylenetetramine, may be added to the hydrochloric acid solution at a volume ratio of 0.1%-0.5% to reduce corrosion on the surface of the nickel-iron alloy sample.

[0090] In this embodiment, the softening treatment uses a mixture of hydrochloric acid and nitric acid with a mass ratio of 2.5:1. At room temperature, the treatment time is strictly controlled to 1-2 minutes to achieve a rapid reaction, avoid violent reactions caused by high temperature or excessive time, and avoid excessive corrosion of the surface of the nickel-iron alloy sample. HNO3 can enhance the solubility of nickel oxides, and HCl can remove iron oxides. The main treatment includes: in a hydrochloric acid solution with a concentration of 14wt%-16wt%, the temperature is controlled at 45℃-55℃, and the treatment time is 28 minutes-35 minutes. Deoxidation treatment is used to remove the oxide film on the surface of the nickel-iron alloy sample.

[0091] In this example, the planarization treatment uses a dilute hydrochloric acid (HCl) solution with a concentration of 2-7 wt% at a temperature of 30-40°C for 10-15 minutes. Hexamethylenetetramine (0.1-0.5% by volume) is added as a corrosion inhibitor to reduce corrosion on the surface of the nickel-iron alloy sample. HCl effectively dissolves iron oxides (Fe₃O₄ and / or Fe₂O₃) and nickel oxides (NiO), while the corrosion inhibitor protects the surface of the nickel-iron alloy sample. If the oxide contains a high concentration of dense NiO, the treatment time can be extended, but corrosion monitoring is required.

[0092] The core design concept of this application is to provide a method for preparing a high-precision metal mask used in the production of OLED display panels. The core of this preparation method is to form a protective oxide film on the surface of the nickel-iron alloy material during the static, storage, and transportation processes, and then remove this oxide film before the process of preparing the FMM product begins. This preparation method can fully protect the surface of the nickel-iron alloy material from water vapor corrosion and reduce surface friction during the static, storage, and transportation of the nickel-iron alloy material. Through verification in actual production and operation, the yield of FMM products during the static, storage, and transportation processes is higher.

[0093] In this embodiment, the method for preparing a high-precision metal mask used in OLED display panel manufacturing employs an alkaline treatment to form an oxide film and a deoxidation treatment to remove the oxide film. This differs from the method used in semiconductor manufacturing processes, where a sacrificial layer is formed to partially block the surface of a substrate or epitaxial layer and then removed. The sacrificial layer is formed on a portion of the surface of the substrate or epitaxial layer and does not react with the substrate or epitaxial layer. The sacrificial layer primarily serves a shielding function, shielding specific areas. The oxide film described in this application, however, is an oxide film comprising Fe₃O₄ formed on the surface of a nickel-iron alloy through an alkaline treatment. The oxide film in this application primarily serves a protective function: first, it prevents mechanical damage to the nickel-iron alloy surface during storage, storage, transportation, reeling, and cleaning; and second, it prevents the natural oxidation reaction between air and the nickel-iron alloy to form Fe₂O₃. Fe₂O₃ is chemically inert and requires very harsh conditions (such as strong acid, high temperature, or high-energy mechanical treatment) to remove.

[0094] Some existing technologies also offer a method for blackening invar steel. This involves forming an iron alloy layer on the surface of the invar steel, then immersing the steel in a strong alkaline solution. This creates a magnetite oxide layer on the iron alloy layer, exhibiting excellent adhesion and blackening properties. The thin iron alloy layer adheres well to the substrate, preventing it from peeling off during subsequent processing.

[0095] The technical problem addressed by this prior art is that the shadow mask in a color cathode ray tube collides with the electron beam emitted from the electron gun, heating the main body of the shadow mask to a temperature of 150°C and causing thermal deformation. This type of shadow mask deformation is commonly known as shadow mask doming. When doming occurs, the electron beam passes through the electron beam apertures formed inside the shadow mask and reaches the screen, causing mislanding. This results in poor color purity and image quality.

[0096] This prior art blackening method first forms an iron alloy layer on the surface of the Invar steel material, and then forms a magnetite oxide layer on the surface of the iron alloy layer. The magnetite oxide layer is pure magnetite oxide, free of other elements, and exhibits excellent adhesion to the base metal (iron alloy layer), resulting in an excellent blackening effect. This allows color televisions manufactured using the blackened mask to provide clear image quality with high color purity by minimizing the occurrence of ridges. In other words, this prior art method uses a shadow mask with a blackened magnetite oxide layer, but does not remove the blackened magnetite oxide layer from the shadow mask surface.

[0097] The following are two comparative examples of the prior art and specific schemes of four embodiments of the present invention:

[0098] Comparative Example 1: Provide nickel-iron alloy samples just produced by a metal factory without going through static storage, transportation, cleaning, etc. Figure 2 As shown, there are no characteristic peaks of Fe2O3 and Fe3O4 in the XRD test pattern of the sample, and the surface roughness of the sample is 0.23 microns.

[0099] Comparative Example 2: A nickel-iron alloy sample produced by a metal factory is provided. The thickness of the nickel-iron alloy sample is 25 microns. The nickel-iron alloy sample is subjected to conventional static storage and transportation. During the process, the surface of the nickel-iron alloy sample will naturally oxidize. Figure 2 As shown, the XRD test pattern of this sample has characteristic peaks of Fe2O3, but no characteristic peaks of Fe3O4. Figure 2 The characteristic peak at 24.1° corresponds to the (012) crystal plane of Fe2O3, the characteristic peak at 33.1° corresponds to the (014) crystal plane of Fe2O3, the characteristic peak at 35.6° corresponds to the (110) crystal plane of Fe2O3, the characteristic peak at 41.8° corresponds to the (113) crystal plane of Fe2O3, the characteristic peak at 49.5° corresponds to the (024) crystal plane of Fe2O3, the characteristic peak at 54.1° corresponds to the (116) crystal plane of Fe2O3, the characteristic peak at 62.4° corresponds to the (214) crystal plane of Fe2O3, and the characteristic peak at 64° corresponds to the (300) crystal plane of Fe2O3. The nickel-iron alloy samples were ultrasonically cleaned at the FMM manufacturer. The surface morphology of the nickel-iron alloy samples was tested at the FMM manufacturer, such as Figure 8 As shown, the surface roughness of the nickel-iron alloy sample in Comparative Example 2 is 1.3 microns, and there is obvious friction damage on the surface, which is randomly distributed in different positions of the nickel-iron alloy sample.

[0100] Example 1: Provide a nickel-iron alloy sample and perform ultrasonic cleaning on it. The thickness of the nickel-iron alloy sample is 25 microns. The nickel-iron alloy sample after ultrasonic cleaning is immersed in a NaOH solution with a concentration of 10wt%, the treatment temperature is 100℃±0.5℃, and the treatment time is 2 hours. Then it is washed with deionized water and placed in a dilute nitric acid solution with a concentration of 5wt% for passivation treatment for 20 minutes. Figure 3 As shown, XRD analysis shows that the main component of iron oxide in the oxide film formed in Example 1 is Fe3O4. Figure 3 The characteristic peak at 30.1° corresponds to the (220) crystal plane of Fe3O4, the characteristic peak at 35.5° corresponds to the (311) crystal plane of Fe3O4, the characteristic peak at 43.1° corresponds to the (400) crystal plane of Fe3O4, the characteristic peak at 53.5° corresponds to the (422) crystal plane of Fe3O4, the characteristic peak at 57° corresponds to the (511) crystal plane of Fe3O4, and the characteristic peak at 62.6° corresponds to the (440) crystal plane of Fe3O4. It should be noted that Figure 2 and Figure 3 The characteristic peaks of NiO have been removed. Figure 4As shown, SEM analysis shows that the thickness of the oxide film formed in Example 1 is about 120 nm.

[0101] Before photoresist coating and pattern transfer, a deoxidation treatment was performed: the nickel-iron alloy sample was immersed in a 15wt% hydrochloric acid solution at 50°C ± 0.5°C for 30 minutes. After this deoxidation treatment, AFM testing revealed a surface roughness of 0.27 microns (not shown), similar to the surface roughness of the nickel-iron alloy when it leaves the metal factory. The nickel-iron alloy sample also showed no obvious friction damage.

[0102] Example 2: Provide a nickel-iron alloy sample and perform ultrasonic cleaning on it. The thickness of the nickel-iron alloy sample is 25 microns. Immerse the nickel-iron alloy sample after ultrasonic cleaning in a NaOH solution with a concentration of 6wt%, and the treatment time is 30 minutes at a temperature of 80°C; then immerse the nickel-iron alloy sample in a NaOH solution with a concentration of 11wt%, and the treatment temperature is 100°C±0.5°C, and the treatment time is 2 hours. Then immerse the nickel-iron alloy sample in a NaOH solution with a concentration of 3wt%, and the treatment time is 10 minutes at a temperature of 60°C. Then, wash with deionized water, and place it in a dilute nitric acid solution with a concentration of 5wt% for passivation treatment for 20 minutes. Figure 3 As shown in FIG, XRD analysis shows that the main component of the iron oxide in the oxide film formed in Example 2 is Fe3O4. Figure 5 As shown, SEM analysis shows that the thickness of the oxide film formed in Example 2 is about 135 nm.

[0103] Before photoresist coating and pattern transfer, deoxygenation treatment is performed: first, hydrochloric acid and nitric acid with a mass ratio of 2.5:1 are mixed and diluted to a total acid concentration of 13wt%, and the nickel-iron alloy sample is immersed in the above-mentioned mixed acid solution, the temperature is controlled at 20℃±2℃, and the treatment time is 2 minutes; then the nickel-iron alloy sample is immersed in a hydrochloric acid solution with a concentration of 15wt%, the temperature is controlled at 50℃±0.5℃, and the treatment time is 30 minutes; finally, the nickel-iron alloy sample is immersed in a hydrochloric acid solution with a concentration of 5wt%, the temperature is controlled at 35℃±2℃, and the treatment time is 12 minutes; during the planarization treatment, a corrosion inhibitor hexamethylenetetramine with a volume ratio of 0.3% is added to the hydrochloric acid solution to reduce corrosion on the surface of the nickel-iron alloy sample. After the above deoxidation treatment, the surface roughness of the nickel-iron alloy sample was 0.25 microns as measured by AFM (not shown), which is close to the surface roughness of the nickel-iron alloy when it leaves the metal factory, and there is no obvious friction damage on the surface of the nickel-iron alloy sample.

[0104] Example 3: Provide a nickel-iron alloy sample and perform ultrasonic cleaning on it. The thickness of the nickel-iron alloy sample is 25 microns. Immerse the nickel-iron alloy sample after ultrasonic cleaning in a NaOH solution with a concentration of 7wt%, and the treatment time is 30 minutes at a temperature of 80°C; then immerse the nickel-iron alloy sample in a NaOH solution with a concentration of 12wt%, and the treatment temperature is 100°C±0.5°C, and the treatment time is 2 hours; then immerse the nickel-iron alloy sample in a NaOH solution with a concentration of 4wt%, and the treatment time is 10 minutes at a temperature of 60°C. Then, wash with deionized water, and place it in a dilute nitric acid solution with a concentration of 5wt% for passivation treatment for 20 minutes. Figure 3 As shown in FIG, XRD analysis shows that the main component of the iron oxide in the oxide film formed in Example 3 is Fe3O4. Figure 6 As shown, SEM analysis shows that the thickness of the oxide film formed in Example 3 is about 142 nm.

[0105] Before photoresist coating and pattern transfer, deoxygenation treatment is performed: first, hydrochloric acid and nitric acid with a mass ratio of 2.5:1 are mixed and diluted to a total acid concentration of 14wt%, and the nickel-iron alloy sample is immersed in the above mixed acid solution, the temperature is controlled at 20℃±2℃, and the treatment time is 2 minutes; then the nickel-iron alloy sample is immersed in a hydrochloric acid solution with a concentration of 14wt%, the temperature is controlled at 50℃±0.5℃, and the treatment time is 30 minutes; finally, the nickel-iron alloy sample is immersed in a hydrochloric acid solution with a concentration of 6wt%, the temperature is controlled at 35℃±1℃, and the treatment time is 12 minutes; during the flattening treatment, a corrosion inhibitor hexamethylenetetramine with a volume ratio of 0.4% is added to the hydrochloric acid solution to reduce corrosion on the surface of the nickel-iron alloy sample. After the above deoxygenation treatment, the AFM test shows that Figure 9 It is shown that the surface roughness of the nickel-iron alloy sample formed in Example 3 is 0.22 microns, which is close to the surface roughness of the nickel-iron alloy when it leaves the metal factory, and there is no obvious friction damage on the surface of the nickel-iron alloy sample.

[0106] Example 4: Provide a nickel-iron alloy sample and perform ultrasonic cleaning on it. The thickness of the nickel-iron alloy sample is 25 microns. Immerse the nickel-iron alloy sample after ultrasonic cleaning in a NaOH solution with a concentration of 7wt%, and the treatment time is 30 minutes at a temperature of 80°C; then immerse the nickel-iron alloy sample in a mixed solution consisting of NaOH with a concentration of 11wt% and NaNO3 with a concentration of 2wt%, and the treatment temperature is 100°C±0.5°C, and the treatment time is 2 hours; then immerse the nickel-iron alloy sample in a NaOH solution with a concentration of 4wt%, and the treatment time is 10 minutes at a temperature of 60°C. Then, wash with deionized water, and place it in a dilute nitric acid solution with a concentration of 5wt% for passivation treatment for 20 minutes. As Figure 3As shown in FIG, XRD analysis shows that the main component of the iron oxide in the oxide film formed in Example 4 is Fe3O4. Figure 7 As shown, SEM analysis shows that the thickness of the oxide film formed in Example 4 is about 176nm. It should be noted that the total thickness of the nickel-iron alloy in Examples 1 to 4 is 25 microns. Figure 4-Figure 7 The nickel-iron alloy in the figure only shows a partial thickness of the nickel-iron alloy.

[0107] Before photoresist coating and pattern transfer, deoxidation treatment is performed: first, hydrochloric acid and nitric acid with a mass ratio of 2.5:1 are mixed and diluted to a total acid concentration of 11wt%, and the nickel-iron alloy sample is immersed in the above-mentioned mixed acid solution, the temperature is controlled at 20℃±2℃, and the treatment time is 2 minutes; then the nickel-iron alloy sample is immersed in a hydrochloric acid solution with a concentration of 16wt%, the temperature is controlled at 50℃±0.5℃, and the treatment time is 30 minutes; finally, the nickel-iron alloy sample is immersed in a hydrochloric acid solution with a concentration of 5wt%, the temperature is controlled at 35℃±3℃, and the treatment time is 12 minutes; during the flattening treatment, a corrosion inhibitor hexamethylenetetramine with a volume ratio of 0.35% is added to the hydrochloric acid solution to reduce corrosion on the surface of the nickel-iron alloy sample. After the above deoxidation treatment, the roughness of the nickel-iron alloy sample surface tested by AFM is 0.24 microns, which is close to the roughness of the nickel-iron alloy surface when it leaves the metal factory, and there is no obvious friction damage on the surface of the nickel-iron alloy sample.

[0108] It can be seen from the above-mentioned comparative examples 1-2 and embodiments 1-4 that after the oxide film is formed by the preparation method of the high-precision metal mask provided in the embodiments of the present application, the surface of the nickel-iron alloy sample can be kept intact during static storage, transportation, cleaning, etc. Before photoresist coating and pattern transfer, deoxidation treatment is carried out. After deoxidation treatment, the roughness of the nickel-iron alloy sample surface is within the range of 0.15-0.30 microns, which is close to the roughness of the nickel-iron alloy surface when it leaves the metal factory, and there is no obvious friction damage on the surface of the nickel-iron alloy sample. The alkali treatment and deoxidation treatment in the specific embodiment 1 each include one sub-step, while the alkali treatment and deoxidation treatment in embodiments 2-4 each include three sub-steps. The surface roughness after deoxidation treatment in embodiments 2-4 is closer to the roughness of the nickel-iron alloy surface when it has just left the metal factory.

[0109] In other embodiments, during the planarization treatment, hexamethylenetetramine, a corrosion inhibitor, is added to the hydrochloric acid solution at a volume ratio of 0.48% to reduce corrosion on the surface of the nickel-iron alloy sample.

[0110] In another aspect of the present invention, the surface of the FMM product produced in the FMM factory is subjected to an alkali treatment to form an oxide layer on the surface of the FMM product. The oxide layer can fully protect the FMM product during transportation from the FMM factory to the OLED panel factory.

[0111] In one embodiment, after step S04 (after photoresist removal and post-processing are complete, and after TPCD and AOI inspections are performed), the process further includes ultrasonically cleaning the fabricated high-precision metal mask. The ultrasonically cleaned high-precision metal mask is then subjected to an alkaline treatment, wherein the alkaline treatment comprises treating the mask in an alkaline solution with a concentration of 9wt% to 14wt% at a temperature of 100°C ± 0.5°C for 2 hours to promote uniform growth of an oxide film. The alkaline-treated high-precision metal mask is then passivated to form an oxide film primarily composed of Fe₃O₄. The oxide film primarily comprises nickel oxide and ferrosoferric oxide. The alkaline solution contains NaOH as a solute. In this step, the alkaline treatment forms an oxide film on the fabricated high-precision metal mask (FMM), ensuring that the FMM product maintains an oxide layer on its surface during shipment, storage, transportation, and cleaning.

[0112] The design concept of "forming an oxide film on the surface of the nickel-iron alloy to protect it during storage or transportation for a period of time or distance" described in the embodiments of this application is applicable to: After the FMM product is produced, the surface treatment to form the oxide film is performed. The FMM product is protected by the oxide film during storage, storage, and transportation from the manufacturer to the OLED manufacturer. During application, the implementation parameters for forming the oxide film through alkaline treatment of the FMM product can refer to the implementation parameters for the nickel-iron alloy sample.

[0113] This application provides a method for preparing high-precision metal masks used in the production of OLED display panels. This method takes into account the full protection of the FMMs throughout the entire process, from the metal factory to the FMM manufacturer and the OLED panel factory. By designing a protective oxide film at appropriate time intervals, the FMMs are comprehensively protected from the source, through production, and into use. The formation and removal processes of this oxide film are also specifically designed by the inventors. This simple and efficient method for preparing high-precision metal masks used in the production of OLED display panels, provided in this application, forms an oxide film primarily composed of Fe₃O₄ and NiO on the surface of a nickel-iron alloy sample through a high-temperature alkaline treatment. A deoxidation treatment is performed before the high-precision metal mask preparation process begins. During static storage, transportation, and cleaning, the nickel-iron alloy sample forms an oxide layer on its surface, significantly improving its corrosion resistance, oxidation resistance, and surface adhesion, and has broad application prospects.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a high-precision metal mask used in the production of an OLED display panel, comprising: S01, raw material preparation and pre-treatment, providing nickel-iron alloy samples that can be processed later; It is characterized in that S01, raw material preparation and pre-processing, includes: Providing nickel-iron alloy samples and performing ultrasonic cleaning on them; The nickel-iron alloy sample after ultrasonic cleaning was treated with an alkali solution containing NaOH. The alkali treatment included pretreatment, mid-stage treatment and post-treatment. The concentrations of NaOH in the three treatment stages were C 预 、C 中段 、C 后 ; The treatment temperatures in the three treatment stages are T 预 、T 中段 、T 后 ; The reaction times in the three treatment stages are t 预 , t 中段 , t 后 , and satisfy: C 中段 >C 预 >C 后 ;T 中段 >T 预 >T 后 ;t 中段 >t 预 >t 后 ; The nickel-iron alloy sample after the alkali treatment is passivated to form an oxide film, wherein the oxide film includes nickel oxide and ferrosoferric oxide.

2. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 1, characterized in that: During the pretreatment process, a NaOH solution with a concentration of 5wt%-8wt% is used; During the middle stage treatment, a NaOH solution with a concentration of 9wt%-14wt% is used; In the post-treatment process, a NaOH solution with a concentration of 3wt%-5wt% is used.

3. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 2, characterized in that: The treatment temperature during the pretreatment process is 75°C-85°C, and the treatment time is 25 minutes-35 minutes; The treatment temperature during the middle stage treatment is 95°C-110°C, and the treatment time is 110 minutes-140 minutes; The treatment temperature in the post-treatment process is 55° C.-65° C., and the treatment time is 8 minutes-15 minutes.

4. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 3, wherein: In the middle stage treatment process, the alkaline solution includes: a mixed solution of NaOH and sodium lauryl sulfate, the concentration of NaOH in the mixed solution is 12wt%-14wt%, and the concentration of sodium lauryl sulfate is 0.1wt%-0.5wt%.

5. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 1, wherein: Also includes: S02, performing photoresist coating and pattern transfer on the surface of the nickel-iron alloy sample; In step S02, deoxidation treatment is first performed, followed by photoresist coating and pattern transfer; The deoxidation treatment uses an acid solution including HCl to remove the oxide film, and the deoxidation treatment includes: softening treatment, main treatment and flattening treatment; The concentrations of HCl in the three treatment stages are C 软化 、C 主 、C 平整化 ; The treatment temperatures in the three treatment stages are T 软化 、T 主 、T 平整化 ; The reaction times in the three processing stages are t 软化 , t 主 , t 平整化 , and satisfy: C 主 >C 软化 >C 平整化 ;T 主 >T 平整化 >T 软化 ;t 主 >t 平整化 >t 软化 。 6. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 5, characterized in that: During the softening process, a HCl solution with a concentration of 10wt%-14wt% is used; The main treatment process uses a HCl solution with a concentration of 14wt%-16wt%; During the planarization process, an HCl solution with a concentration of 2wt%-7wt% is used.

7. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 6, characterized in that: The treatment temperature during the softening treatment is 15°C-25°C, and the treatment time is 1.5 minutes-3 minutes; The treatment temperature in the main treatment process is 45°C-55°C, and the treatment time is 28 minutes-35 minutes; The treatment temperature during the planarization treatment is 30° C.-40° C., and the treatment time is 10 minutes-15 minutes.

8. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 1, wherein: The thickness of the oxide film is 100nm-200nm.

9. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 1, wherein: The passivation treatment after the alkali treatment includes: Washing the alkali-treated nickel-iron alloy sample with deionized water; The nickel-iron alloy sample after being washed with deionized water is placed in a dilute nitric acid solution with a concentration of 3wt%-6wt% for passivation treatment at a treatment temperature of 15°C-25°C and a treatment time of 18 minutes-22 minutes.

10. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 1, wherein: Also includes: S03, chemically etching the two surfaces of the nickel-iron alloy sample to form etching patterns on the first surface and the second surface; as well as, S04, removing the photoresist on the surface of the nickel-iron alloy sample on which the etching patterns on both sides have been formed, and performing post-processing on the nickel-iron alloy sample to form the high-precision metal mask.

11. The method for preparing a high-precision metal mask used in the production of an OLED display panel according to claim 10, characterized in that: After step S04, the method further includes: Ultrasonic cleaning of the completed high-precision metal mask; The high-precision metal mask after ultrasonic cleaning is subjected to an alkali treatment, wherein the alkali treatment includes: pretreatment, mid-stage treatment, and post-treatment; an alkali solution including NaOH is used during the alkali treatment; the mid-stage treatment includes using an alkali solution with a concentration of 9wt%-14wt%, a treatment temperature of 95°C-105°C, and a treatment time of 110 minutes-130 minutes; and, The high-precision metal mask after alkali treatment is passivated to form an oxide film, which includes nickel oxide and ferrosoferric oxide.

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