Blackening method for metal grid, metal grid, and touch sensor

Abstract

The present application relates to a method for blackening a metal grid, a metal grid, and a touch sensor. The method for blackening the metal grid of the present application includes the following steps: blackening the metal grid with a blackening solution, wherein the color parameters of the metal grid after the blackening treatment are detected; adjusting the blackening parameters of the blackening treatment according to the correspondence between the color parameters and the impedance change rate of the metal grid, so that the color parameters of the obtained metal grid after adjustment are within a preset weakly blackened color range, and the weakly blackened color range is set based on the corresponding impedance change rate. The above method for blackening a metal grid can accurately control the blackening degree of the metal grid within the allowable impedance change rate, fully reduce the influence of the blackening process on the impedance change rate of the device, improve the reliability of the device, and at the same time can also meet the blackening requirement of reducing the visibility of the metal grid.

Description

Technical Field

[0001] The present application relates to the field of touch sensing technology, and particularly to a method for blackening a metal grid, a metal grid, and a touch sensor. Background Art

[0002] Currently, in the consumer electronics touch screen industry, the conductive materials of conductive films, which are one of the key components, usually use indium tin oxide (ITO), nanosilver wires, metal grids, etc. Among them, the metal grid conductive film has attracted wide attention due to its advantages such as low cost, low resistance, and applicability to ultra-thin and foldable electronic products. During the preparation process of the metal grid, blackening treatment is usually carried out, that is, a blackening layer is formed on the metal grid, which can effectively reduce the reflectivity of the copper in the metal grid to reduce the visibility of the metal wires and can significantly improve the appearance when applied in the module state. However, after the metal grid is blackened by using the traditional metal grid blackening process, the impedance change rate of the metal grid in different environments is relatively large and the reliability is low. Summary of the Invention

[0003] Based on this, it is necessary to provide a method for blackening a metal grid, a metal grid, and a touch sensor. The method for blackening the metal grid of the present application can accurately control the blackening degree of the metal grid within the allowable impedance change rate, fully reduce the influence of the blackening process on the impedance change rate of the device, improve the reliability of the device, and at the same time can also meet the blackening requirement of reducing the visibility of the metal grid.

[0004] In a first aspect, the present application provides a method for blackening a metal grid, including the following steps:

[0005] The metal grid is blackened by a blackening solution. Among them, the color parameters of the metal grid after the blackening treatment are detected, and the blackening parameters of the blackening solution are adjusted according to the corresponding relationship between the color parameters and the impedance change rate of the metal grid, so that the color parameters of the adjusted metal grid are within a preset weak blackening color range, and the weak blackening color range is set based on the corresponding impedance change rate.

[0006] In some embodiments, the adjustment of the blackening parameters of the blackening treatment according to the corresponding relationship between the color parameters and the impedance change rate of the metal grid includes:

[0007] The concentration of the blackening solution in the blackening treatment is adjusted according to the corresponding relationship between the color parameters and the impedance change rate of the metal grid.

[0008] In some embodiments, the mass percentage concentration of the blackening agent in the blackening solution is 0.025% - 0.45%.

[0009] In some embodiments, adjusting the blackening parameters of the blackening treatment according to the correspondence between the color parameters and the impedance change rate of the metal grid includes:

[0010] Adjusting the blackening temperature or blackening time of the blackening treatment according to the correspondence between the color parameters and the impedance change rate of the metal grid.

[0011] In some embodiments, the blackening temperature is 26°C to 34°C, and the blackening time is 30s to 70s.

[0012] In some embodiments, adjusting the blackening parameters according to the correspondence between the color parameters and the impedance change rate of the metal grid includes:

[0013] Comparing the color parameters with the blackening chromatogram, verifying the impedance change rate corresponding to the color parameters, and adjusting the blackening parameters of the blackening treatment based on the impedance change rate;

[0014] The blackening chromatogram is the correspondence between the color parameters and the impedance change rate of the metal grid.

[0015] In some embodiments, the color parameters are Lab values or RGB values.

[0016] In some embodiments, after blackening the metal grid with the blackening solution, it further includes: forming a protective layer on the blackened metal grid;

[0017] Detecting the color parameters of the metal grid after the blackening treatment includes: detecting the color parameters of the metal grid after the blackening treatment and / or after the formation of the protective layer.

[0018] In some embodiments, after blackening the metal grid with the blackening solution, the following steps are further included:

[0019] Performing a first cleaning on the blackened metal grid, and the first cleaning is an alkaline cleaning.

[0020] In some embodiments, after performing the first cleaning on the blackened metal grid, the following steps are further included:

[0021] Performing a second cleaning on the metal grid after the first cleaning, and the second cleaning is an alcohol cleaning or a ketone cleaning.

[0022] Second, the present application provides a metal grid obtained by blackening through the blackening method of the metal grid described in any one of the above.

[0023] Third, the present application provides a touch sensor including the above metal grid.

[0024] The above-mentioned method for blackening a metal grid involves blackening the metal grid with a blackening solution. Meanwhile, the color parameters of the metal grid after the blackening treatment are detected, and the blackening parameters of the blackening treatment are adjusted according to the corresponding relationship between the color parameters and the impedance change rate of the metal grid, so that the color parameters of the obtained metal grid after adjustment are within a preset weak blackening color range, and the weak blackening color range is set based on the corresponding impedance change rate. It can accurately control the blackening degree of the metal grid within the allowable impedance change rate, fully reduce the impact of the blackening process on the impedance change rate of the device, improve the reliability of the device, and at the same time meet the blackening requirement of reducing the visibility of the metal grid. Brief Description of the Drawings

[0025] Figure 1 It is a schematic flowchart of the method for blackening a metal grid provided by an embodiment of the present application;

[0026] Figure 2 It is a schematic flowchart of the method for blackening a metal grid provided by another embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of color numbers corresponding to copper grids with different blackening degrees provided by the present application. Detailed Embodiments

[0028] To make the above objects, features, and advantages of the present application more obvious and understandable, the following detailed description of the specific embodiments of the present application will be given in conjunction with the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0030] In a first aspect, the present application provides a method for blackening a metal grid. Referring to Figure 1 [[ID=2,8]] , it includes the following steps:

[0031] S110: Blacken the metal grid with a blackening solution, wherein the color parameters of the metal grid after the blackening treatment are detected.

[0032] S120: Adjust the blackening parameters of the blackening process according to the correspondence between the color parameters and the impedance change rate of the metal grid, so that the color parameters of the metal grid obtained after adjustment are within the preset weak blackening color range, and the weak blackening color range is set based on the corresponding impedance change rate.

[0033] The above blackening method for the metal grid blackens the metal grid with a blackening solution. At the same time, the color parameters of the blackened metal grid are detected, and the blackening parameters of the blackening process are adjusted according to the correspondence between the color parameters and the impedance change rate of the metal grid, so that the color parameters of the metal grid obtained after adjustment are within the preset weak blackening color range, and the weak blackening color range is set based on the corresponding impedance change rate. It can accurately control the blackening degree of the metal grid within the allowable impedance change rate, fully reduce the impact of the blackening process on the impedance change rate of the device, improve the reliability of the device, and at the same time can also meet the blackening requirement of reducing the visibility of the metal grid. It should be noted that the traditional color parameters are only used for the evaluation of the visibility of the metal grid, while the color parameters in this application are used for the evaluation of the impedance change rate of the metal grid, that is, the reliability evaluation. This correspondence is obtained through pre-measurement and can be presented in the form of a blackening chromatogram. At the same time, by corresponding the color parameters to the impedance change rate of the metal grid, the data of the impedance change rate that need to be obtained through a long-time test can be visually and quickly displayed and evaluated, which can improve production efficiency.

[0034] In some embodiments, adjusting the blackening parameters of the blackening process according to the correspondence between the color parameters and the impedance change rate of the metal grid includes: adjusting the concentration of the blackening solution in the blackening process according to the correspondence between the color parameters and the impedance change rate of the metal grid. By adjusting the concentration of the blackening solution, the effect of the blackening process can be regulated, so that the color parameters of the metal grid obtained after adjustment are within the preset weak blackening color range, and further the impedance change rate of the blackened metal grid meets the preset conditions.

[0035] In some embodiments, the impedance change rate corresponding to the weak blackening color range is less than or equal to 40%.

[0036] It can be understood that the lower limit value of the impedance change rate corresponding to the weak blackening color range is set according to the requirements of the visibility of the metal grid. In some embodiments, the impedance change rate corresponding to the weak blackening color range is greater than or equal to 8%.

[0037] In some embodiments, the impedance change rate corresponding to the weak blackening color range is 8% - 40%.

[0038] In some embodiments, the mass percentage concentration of the blackening agent in the blackening solution is 0.025% to 0.45%. Optionally, the mass percentage concentration of the blackening agent in the blackening solution is 0.025%, 0.05%, 0.1%, 0.125%, 0.15%, 0.175%, 0.2%, 0.225%, 0.25%, 0.275%, 0.3%, 0.325%, 0.35%, 0.375%, 0.4%, 0.425% or 0.45%.

[0039] In some embodiments, adjusting the blackening parameters of the blackening treatment according to the correspondence between the color parameters and the impedance change rate of the metal grid includes: adjusting the blackening temperature or the blackening time of the blackening treatment according to the correspondence between the color parameters and the impedance change rate of the metal grid. By adjusting the blackening temperature or the blackening time of the blackening treatment, the effect of the blackening treatment can be regulated so that the color parameters of the metal grid obtained after adjustment are within the preset weak blackening color range, and further the impedance change rate of the blackened metal grid meets the preset conditions.

[0040] In some embodiments, the temperature of the blackening treatment is 26°C to 34°C, and the time of the blackening treatment is 30s to 70s. Within this temperature range of the blackening treatment, the control of the blackening degree is better. When the temperature of the blackening treatment is too high, it is easy to cause excessive blackening. When the temperature of the blackening treatment is too low, it is easy to cause incomplete blackening or local blackening, and the blackening effect is poor. Optionally, the temperature of the blackening treatment is 26°C, 26.5°C, 27°C, 27.5°C, 28°C, 28.5°C, 29°C, 29.5°C, 30°C, 30.5°C, 31°C, 31.5°C, 32°C, 32.5°C, 33°C, 33.5°C or 34°C. Within this time range of the blackening treatment, the control of the blackening degree is better. When the time of the blackening treatment is too long, it is easy to cause excessive blackening. When the time of the blackening treatment is too short, it is easy to cause incomplete blackening or local blackening, and the blackening effect is poor. Optionally, the time of the blackening treatment is 30s, 31s, 32s, 33s, 34s, 35s, 36s, 37s, 38s, 39s, 40s, 41s, 42s, 43s, 44s, 45s, 46s, 47s, 48s, 49s, 50s, 51s, 52s, 53s, 54s, 55s, 56s, 57s, 58s, 59s, 60s, 61s, 62s, 63s, 64s, 65s, 66s, 67s, 68s, 69s or 70s.

[0041] In some embodiments, adjusting the blackening parameters of the blackening treatment according to the correspondence between the color parameters and the impedance change rate of the metal grid includes: comparing the color parameters with the blackening chromatogram to verify the impedance change rate corresponding to the color parameters, and adjusting the blackening parameters of the blackening treatment based on the impedance change rate; the blackening chromatogram is the correspondence between the color parameters and the impedance change rate of the metal grid. Exemplarily, referring to Figure 3 as shown, the specific blackening chromatogram shows the relationship between the color number and NG / OK. The color number corresponds to the color parameters RGB\Lab, the color number is determined by the RGB / Lab value, NG / OK corresponds to the reliability, if the impedance change rate is less than the preset threshold, the reliability is OK, and if the impedance change rate is greater than the preset threshold, the reliability is NG.

[0042] In some embodiments, the color parameters are Lab values or RGB values. It can be understood that the Lab value is composed of three elements of illuminance (L) and related colors a and b. L represents illuminance (Luminosity), equivalent to brightness, a represents the range from red to green, and b represents the range from blue to yellow. The value range of L is from 0 to 100, and the value ranges of a and b are both from +120 to -120. All colors are composed of the interaction of these three values. The RGB value is a color standard in the industry. It obtains various colors through the changes of the three color channels of red (R), green (G), and blue (B) and their superposition with each other. RGB represents the colors of the three channels of red, green, and blue. The two parameters can be converted to each other.

[0043] Exemplarily, the Lab value (same shooting brightness) after the blackening of the metal grid or after the coating of the protective layer can be detected by a detection device such as a color difference meter, and the color parameter difference comparison of the Lab value can be carried out through the blackening chromatogram such as Figure 3 to determine the corresponding metal grid color number. Among them, as Figure 3 shown, the color parameters of the corresponding metal grid are divided into each color number to determine whether the reliability corresponding to the blackening degree of the current blackening process meets the requirements. The reliability NG / OK is determined by measuring the impedance change rate of the corresponding metal grid.

[0044] In some embodiments, the blackening agent includes at least one of selenium dioxide, palladium nitrate, palladium acetate, palladium oxide, palladium chloride, palladium sulfate, palladium iodide, and palladium bromide.

[0045] In some embodiments, the blackening solution comprises the following components in mass percentages: 0.025% to 0.45% of a blackening agent, 0.025% to 1.125% of a surfactant, and 98.425% to 99.95% of water. Optionally, the mass percentage of the surfactant is 0.025%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.025%, 1.05%, 1.075%, 1.1% or 1.125%.

[0046] In some embodiments, the surfactant comprises at least one of fatty alcohol polyoxyethylene ether, fatty alcohol alkoxy ether, fatty acid methyl ester polyoxyethylene ether, diethylenetriamine, diethylenetetramine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and iminodipropylamine. It can be understood that fatty alcohol polyoxyethylene ether, fatty alcohol alkoxy ether, and fatty acid methyl ester polyoxyethylene ether are used in combination with selenium dioxide. Diethylenetriamine, diethylenetetramine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and iminodipropylamine are used in combination with palladium nitrate, palladium acetate, palladium oxide, palladium chloride, palladium sulfate, palladium iodide, and palladium bromide.

[0047] In some embodiments, during the blackening process, the pH value of the blackening solution is adjusted to 2.0 to 2.8. It can be understood that the pH of the blackening agent is adjusted by a pH regulator. The pH regulator can be sulfuric acid or hydrochloric acid. Optionally, during the blackening process, the pH value of the blackening solution is adjusted to 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, or 2.8.

[0048] In some embodiments, after the metal grid is blackened by the blackening solution, it further includes: forming a protective layer on the blackened metal grid; detecting the color parameters of the blackened metal grid, including detecting the color parameters of the blackened metal grid after and / or after the formation of the protective layer. Similarly, the color parameters of the metal grid after blackening and after the formation of the protective layer can be combined to jointly determine the impedance change rate of the metal grid, thereby adjusting the concentration of the blackening solution. Exemplarily, the protective layer can include at least one of a polymer coating, a cover glass, and a hard coating.

[0049] In some embodiments, after the metal grid is blackened by the blackening solution, the following steps are further included: performing a first cleaning on the blackened metal grid, and the first cleaning is an alkali cleaning. The first cleaning can neutralize and remove the residual blackening solution, further improving the reliability of the metal grid. Exemplarily, the alkali cleaning can include isopropanolamine cleaning or diethyl adipate cleaning.

[0050] In some embodiments, after the first cleaning of the blackened metal grid, the following steps are further included: performing a second cleaning on the metal grid after the first cleaning, and the second cleaning is an alcohol cleaning or a ketone cleaning. The second cleaning can remove the residual moisture and the blackening solution in the blackening layer, improve the drying degree of the metal grid, and further improve the reliability of the metal grid. Optionally, the alcohol cleaning is performed using isopropyl alcohol or ethanol. Optionally, the ketone cleaning is performed using acetone or methyl ethyl ketone.

[0051] In some embodiments, before the first cleaning of the blackened metal grid, deionized water cleaning of the blackened metal grid is further included.

[0052] In some embodiments, before the second cleaning of the blackened metal grid, deionized water cleaning of the metal grid after the first cleaning is further included.

[0053] In some embodiments, the method for preparing a metal grid includes the following steps: forming a photoresist layer on a substrate, and forming a catalyst layer on the photoresist layer; performing patterned exposure and development on the substrate after forming the photoresist layer and the catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer; forming a metal grid on the patterned catalyst layer using an electroless plating solution.

[0054] In some embodiments, the electroless plating solution includes at least one of a silver plating solution, a nickel plating solution, a copper plating solution, and a cobalt plating solution.

[0055] Refer to Figure 2 , in some embodiments, the method for blackening a metal grid includes the following steps:

[0056] S210: forming a photoresist layer on a substrate, and forming a catalyst layer on the photoresist layer;

[0057] S220: performing patterned exposure and development on the substrate after forming the photoresist layer and the catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer;

[0058] S230: forming a metal grid on the patterned catalyst layer using an electroless plating solution;

[0059] S240: blackening the metal grid using a blackening solution;

[0060] S250: cleaning the blackened metal grid, and the cleaning includes sequentially performing a first deionized water cleaning, a first cleaning, a second deionized water cleaning, and a second cleaning;

[0061] S260: forming a protective layer on the cleaned metal grid;

[0062] S270: Detect the color parameters of the metal grid. Compare the color parameters with the blackening chromatogram, verify the impedance change rate corresponding to the color parameters, and adjust the blackening parameters of the blackening process based on the impedance change rate.

[0063] Another embodiment of the present application provides a metal grid obtained by blackening through the blackening method of the metal grid in any one of the above.

[0064] Another embodiment of the present application provides a touch sensor including the above metal grid.

[0065] It can be understood that the touch sensor is only one exemplary application scenario of the metal grid. The above metal grid can also be applied to various other electronic application scenarios. Exemplarily, the metal grid can also be applied to application fields such as metal grid antennas and metal grid conductive films.

[0066] The following are specific embodiments

[0067] Embodiment 1

[0068] Preparation of the metal grid

[0069] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer. Then coat a catalyst solution on the photoresist layer. The catalyst solution is composed of 85% pure water, 5% palladium chloride, 5% ethyl acetate, and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0070] (2) Pattern-expose and develop the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0071] (3) Mix copper salt, complexing agent, pH regulator, reducing agent, and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0072] (4) Mix 0.15% selenium dioxide, 0.3% fatty alcohol polyoxyethylene ether, and 99.55% water by mass percentage to obtain a blackening solution, and add sulfuric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution to perform blackening treatment on the metal grid. The blackening treatment time is 50 s, and the blackening treatment temperature is 30 °C.

[0073] (5) Clean the blackened metal grid. The cleaning includes sequential first deionized water cleaning, isopropanolamine cleaning or diethyl adipate cleaning, second deionized water cleaning, and isopropanol cleaning.

[0074] (6) Form a polymer protective layer on the cleaned metal grid, and the protective layer is silicone resin.

[0075] Example 2

[0076] Preparation of metal grid

[0077] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer, then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorinated surfactant FC-4430 in mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0078] (2) Pattern exposure and development are carried out on the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0079] (3) Mix copper salt, complexing agent, pH regulator, reducing agent and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0080] (4) Mix 0.05% selenium dioxide, 0.075% fatty alcohol polyoxyethylene ether and 99.875% water by mass percentage to obtain a blackening solution, and add sulfuric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution to carry out blackening treatment on the metal grid. The time of blackening treatment is 50 s, and the temperature of blackening treatment is 30 °C.

[0081] (5) Clean the blackened metal grid. The cleaning includes sequential first deionized water cleaning, isopropanolamine cleaning or diethyl adipate cleaning, second deionized water cleaning and isopropanol cleaning.

[0082] (6) Form a polymer protective layer on the cleaned metal grid, and the protective layer is silicone resin.

[0083] Example 3

[0084] Preparation of metal grid

[0085] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer, then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorinated surfactant FC-4430 in mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0086] (2) Pattern exposure and development are carried out on the substrate after forming the photoresist layer and the catalyst layer through a mask, and a grid-patterned photoresist layer and catalyst layer are obtained.

[0087] (3) Copper salt, complexing agent, pH regulator, reducing agent, and stabilizer are mixed to prepare a copper plating solution. The substrate obtained in step (2) is placed in the copper plating solution, and a metal layer is formed on the catalyst layer to obtain a metal grid.

[0088] (4) Selenium dioxide with a mass percentage of 0.45%, fatty alcohol polyoxyethylene ether with a mass percentage of 1.125%, and water with a mass percentage of 98.425% are mixed to obtain a blackening solution, and sulfuric acid is added to adjust the pH of the blackening solution to 2.4. The substrate obtained in step (3) is placed in the blackening solution, and the metal grid is blackened. The blackening time is 50 s, and the blackening temperature is 30 °C.

[0089] (5) The blackened metal grid is cleaned, and the cleaning includes sequential first deionized water cleaning, isopropanolamine cleaning or diethyl adipate cleaning, second deionized water cleaning, and isopropanol cleaning.

[0090] (6) A polymer protective layer is formed on the cleaned metal grid, and the protective layer is silicone resin.

[0091] Example 4

[0092] Preparation of Metal Grid

[0093] (1) A transparent flexible substrate is provided, a photoresist is coated on the substrate and cured at 80 °C for 15 s to obtain a photoresist layer, and then a catalyst solution is coated on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate, and 5% fluorinated surfactant FC-4430 in mass percentage, and is dried at 75 °C for 20 s to form a catalyst layer.

[0094] (2) Pattern exposure and development are carried out on the substrate after forming the photoresist layer and the catalyst layer through a mask, and a grid-patterned photoresist layer and catalyst layer are obtained.

[0095] (3) Copper salt, complexing agent, pH regulator, reducing agent, and stabilizer are mixed to prepare a copper plating solution. The substrate obtained in step (2) is placed in the copper plating solution, and a metal layer is formed on the catalyst layer to obtain a metal grid.

[0096] (4) Selenium dioxide with a mass percentage of 0.15%, fatty alcohol polyoxyethylene ether with a mass percentage of 0.3%, and water with a mass percentage of 99.55% are mixed to obtain a blackening solution, and sulfuric acid is added to adjust the pH of the blackening solution to 2.4. The substrate obtained in step (3) is placed in the blackening solution, and the metal grid is blackened. The blackening time is 30 s, and the blackening temperature is 30 °C.

[0097] (5) Wash the blackened metal grid. The washing includes first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing, and isopropanol washing carried out in sequence.

[0098] (6) Form a polymer protective layer on the washed metal grid. The protective layer is silicone resin.

[0099] Example 5

[0100] Preparation of Metal Grid

[0101] (1) Provide a transparent flexible substrate. Coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer. Then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate, and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0102] (2) Pattern-expose and develop the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0103] (3) Mix copper salt, complexing agent, pH regulator, reducing agent, and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0104] (4) Mix 0.15% selenium dioxide, 0.3% fatty alcohol polyoxyethylene ether, and 99.55% water by mass percentage to obtain a blackening solution. Add sulfuric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution to carry out blackening treatment on the metal grid. The blackening treatment time is 70 s, and the blackening treatment temperature is 30 °C.

[0105] (5) Wash the blackened metal grid. The washing includes first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing, and isopropanol washing carried out in sequence.

[0106] (6) Form a polymer protective layer on the washed metal grid. The protective layer is silicone resin.

[0107] Example 6

[0108] Preparation of Metal Grid

[0109] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer, then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0110] (2) Pattern exposure and development are carried out on the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0111] (3) Mix copper salt, complexing agent, pH regulator, reducing agent and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0112] (4) Mix 0.15% selenium dioxide, 0.3% fatty alcohol polyoxyethylene ether and 99.55% water by mass percentage to obtain a blackening solution, and add sulfuric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution to carry out blackening treatment on the metal grid. The blackening treatment time is 50 s and the blackening treatment temperature is 26 °C.

[0113] (5) Wash the blackened metal grid. The washing includes sequential first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing and isopropanol washing.

[0114] (6) Form a polymer protective layer on the washed metal grid. The protective layer is silicone resin.

[0115] Example 7

[0116] Preparation of Metal Grid

[0117] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer, then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0118] (2) Pattern exposure and development are carried out on the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0119] (3) Mix copper salt, complexing agent, pH regulator, reducing agent and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0120] (4) Mix selenium dioxide with a mass percentage of 0.15%, fatty alcohol polyoxyethylene ether with a mass percentage of 0.3%, and water with a mass percentage of 99.55% to obtain a blackening solution, and add sulfuric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution, and perform blackening treatment on the metal grid. The time for blackening treatment is 50 s, and the temperature for blackening treatment is 34 °C.

[0121] (5) Wash the metal grid after blackening treatment. The washing includes sequential first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing, and isopropanol washing.

[0122] (6) Form a polymer protective layer on the washed metal grid. The protective layer is silicone resin.

[0123] Example 8

[0124] Preparation of Metal Grid

[0125] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer. Then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate, and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0126] (2) Pattern and expose and develop the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0127] (3) Mix copper salt, complexing agent, pH regulator, reducing agent, and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0128] (4) Mix palladium chloride with a mass percentage of 0.2%, diethylenetriamine with a mass percentage of 0.4%, and water with a mass percentage of 99.4% to obtain a blackening solution, and add hydrochloric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution, and perform blackening treatment on the metal grid. The time for blackening treatment is 50 s, and the temperature for blackening treatment is 30 °C.

[0129] (5) Wash the metal grid after blackening treatment. The washing includes sequential first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing, and isopropanol washing.

[0130] (6) Form a polymer protective layer on the washed metal grid. The protective layer is silicone resin.

[0131] Comparative Example 1

[0132] Preparation of metal grids

[0133] (1) A transparent flexible substrate is provided, a photoresist is coated on the substrate and cured at 80°C for 15 seconds to obtain a photoresist layer, and a catalyst solution is coated on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorine-based surfactant FC-4430 in the following mass percentages, and the catalyst layer is formed by drying at 75°C for 20 seconds.

[0134] (2) The substrate after forming the photoresist layer and the catalyst layer is patterned exposed and developed through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0135] (3) A copper salt, a complexing agent, a pH regulator, a reducing agent, and a stabilizer are mixed to prepare a copper plating solution, and the substrate obtained in step (2) is placed in the copper plating solution to form a metal layer on the catalyst layer to obtain a metal grid.

[0136] (4) 0.6% by mass of selenium dioxide, 1.8% of fatty alcohol polyoxyethylene ether and 98.6% of water were mixed to obtain a blackening liquid, and sulfuric acid was added to adjust the pH of the blackening liquid to 2.4. The substrate obtained in step (3) was placed in the blackening liquid, and the metal grid was blackened for 50 seconds at a temperature of 30°C.

[0137] (5) Cleaning the metal grid after the blackening treatment, which includes a first deionized water cleaning, an isopropylamine cleaning or a diethyl adipate cleaning, a second deionized water cleaning and an isopropyl alcohol cleaning in sequence.

[0138] (6) A polymer protective layer is formed on the cleaned metal grid, and the protective layer is a silicone resin.

[0139] Comparative Example 2

[0140] Preparation of metal grids

[0141] (1) A transparent flexible substrate is provided, a photoresist is coated on the substrate and cured at 80°C for 15 seconds to obtain a photoresist layer, and a catalyst solution is coated on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorine-based surfactant FC-4430 in the following mass percentages, and the catalyst layer is formed by drying at 75°C for 20 seconds.

[0142] (2) The substrate after forming the photoresist layer and the catalyst layer is patterned exposed and developed through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0143] (3) Mix copper salt, complexing agent, pH regulator, reducing agent, and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) into the copper plating solution to form a metal layer on the catalyst layer, thereby obtaining a metal grid.

[0144] (4) Mix 0.01% selenium dioxide, 0.01% fatty alcohol polyoxyethylene ether, and 99.98% water by mass percentage to obtain a blackening solution, and add sulfuric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) into the blackening solution to perform blackening treatment on the metal grid. The time for blackening treatment is 50 s, and the temperature for blackening treatment is 30 °C.

[0145] (5) Wash the metal grid after blackening treatment. The washing includes successively performing first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing, and isopropanol washing.

[0146] (6) Form a polymer protective layer on the washed metal grid. The protective layer is silicone resin.

[0147] Comparative Example 3

[0148] Preparation of Metal Grid

[0149] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer. Then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate, and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0150] (2) Pattern-expose and develop the substrate after forming the photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0151] (3) Mix copper salt, complexing agent, pH regulator, reducing agent, and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) into the copper plating solution to form a metal layer on the catalyst layer, thereby obtaining a metal grid.

[0152] (4) Mix 0.7% palladium chloride, 2% diethylenetriamine, and 97.3% water by mass percentage to obtain a blackening solution, and add hydrochloric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) into the blackening solution to perform blackening treatment on the metal grid. The time for blackening treatment is 50 s, and the temperature for blackening treatment is 30 °C.

[0153] (5) Wash the metal grid after blackening treatment. The washing includes successively performing first deionized water washing, isopropanolamine washing or diethyl adipate washing, second deionized water washing, and isopropanol washing.

[0154] (6) Form a polymer protective layer on the cleaned metal grid, and the protective layer is silicone resin.

[0155] Comparative Example 4

[0156] Preparation of Metal Grid

[0157] (1) Provide a transparent flexible substrate, coat a photoresist on the substrate and cure it at 80 °C for 15 s to obtain a photoresist layer, then coat a catalyst solution on the photoresist layer. The catalyst solution consists of 85% pure water, 5% palladium chloride, 5% ethyl acetate and 5% fluorinated surfactant FC-4430 by mass percentage, and dry it at 75 °C for 20 s to form a catalyst layer.

[0158] (2) Pattern exposure and development are performed on the substrate with the formed photoresist layer and catalyst layer through a mask to obtain a grid-patterned photoresist layer and catalyst layer.

[0159] (3) Mix copper salt, complexing agent, pH regulator, reducing agent and stabilizer to prepare a copper plating solution. Place the substrate obtained in step (2) in the copper plating solution to form a metal layer on the catalyst layer and obtain a metal grid.

[0160] (4) Mix 0.01% palladium chloride, 0.01% diethylenetriamine and 99.98% water by mass percentage to obtain a blackening solution, and add hydrochloric acid to adjust the pH of the blackening solution to 2.4. Place the substrate obtained in step (3) in the blackening solution to perform blackening treatment on the metal grid. The blackening treatment time is 50 s and the blackening treatment temperature is 30 °C.

[0161] (5) Clean the blackened metal grid. The cleaning includes sequential first deionized water cleaning, isopropanolamine cleaning or diethyl adipate cleaning, second deionized water cleaning and isopropanol cleaning.

[0162] (6) Form a polymer protective layer on the cleaned metal grid, and the protective layer is silicone resin.

[0163] Perform reliability tests on the metal grids prepared in the examples and comparative examples respectively, and the test results are shown in Table 1 below.

[0164] Among them, the first test in Table 1 means testing the metal grid in an environment of 85 °C temperature and 85% humidity for 120 h, and the second test in Table 1 means testing the metal grid in an environment of 85 °C temperature for 240 h, and record the impedance change rate of each metal grid before and after the test.

[0165] Table 1

[0166]

[0167] Reference Figure 2 As shown in Figure 2 , the blackening degrees of the metal meshes prepared in Examples 1 to 8 are all between No. 2 and No. 5, and the blackening degree is moderate. The blackening degrees of the metal meshes prepared in Comparative Examples 1 and 3 are 7, and the blackening degree is relatively high, which can meet the blackening requirements for the visibility of the metal mesh, but the impedance change rate is too large and does not meet the reliability requirements. The blackening degrees of the metal meshes prepared in Comparative Examples 2 and 4 are 1, and the blackening degree is relatively low, which can meet the reliability requirements, but cannot meet the blackening requirements for the visibility of the metal mesh, that is, the blocking effect of the metal mesh is poor. According to the test results, it can be seen that the impedance change rates of the metal meshes prepared in Examples 1 to 8 after the first test or the second test are all lower than those of the metal meshes prepared in Comparative Examples 1 and 3. That is, the blackening method of the metal mesh of the present application can accurately control the blackening degree within the allowable impedance change rate, fully reduce the influence of the blackening process on the impedance change rate of the device, improve the reliability of the device, and at the same time can also meet the blackening requirements for reducing the visibility of the metal mesh.

[0168] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0169] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims, and the specification and the drawings can be used to explain the content of the claims.

Claims

1. A method for blackening a metal grid, characterized in that: The following steps are involved: Performing a blackening treatment on a metal mesh using a blackening liquid, wherein color parameters of the metal mesh after the blackening treatment are detected, and adjusting the blackening parameters of the blackening treatment according to a correspondence between the color parameters and the impedance change rate of the metal mesh, so that the color parameters of the metal mesh obtained after the adjustment are within a preset weak blackening color range, the weak blackening color range being set based on the corresponding impedance change rate, and the impedance change rate corresponding to the weak blackening color range being 8% to 40%; The step of adjusting the blackening parameters of the blackening process according to the corresponding relationship between the color parameter and the impedance change rate of the metal grid includes: adjusting the concentration of the blackening liquid in the blackening process or the blackening temperature or the blackening time of the blackening process according to the corresponding relationship between the color parameter and the impedance change rate of the metal grid; The color parameter is a Lab value or an RGB value.

2. The method for blackening a metal grid according to claim 1, wherein: The mass percentage concentration of the blackening agent in the blackening liquid is 0.025% to 0.45%.

3. The method for blackening a metal grid according to claim 1, wherein: The blackening temperature is 26° C. to 34° C., and the blackening time is 30s to 70s.

4. The method for blackening a metal grid according to any one of claims 1 to 3, characterized in that: The step of adjusting the blackening parameters of the blackening process according to the corresponding relationship between the color parameter and the impedance change rate of the metal grid includes: Comparing the color parameter with a blackening chromatogram, verifying an impedance change rate corresponding to the color parameter, and adjusting the blackening parameter of the blackening process based on the impedance change rate; The blackening chromatogram is a correspondence between the color parameter and the impedance change rate of the metal grid.

5. The method for blackening a metal grid according to any one of claims 1 to 3, characterized in that: After the metal grid is blackened by the blackening liquid, the method further includes: forming a protective layer on the blackened metal grid; Detecting the color parameters of the metal grid after the blackening treatment includes: detecting the color parameters of the metal grid after the blackening treatment and / or after the protective layer is formed.

6. The method for blackening a metal grid according to any one of claims 1 to 3, characterized in that: After the metal grid is blackened by the blackening liquid, the following steps are further included: The metal grid after the blackening treatment is first cleaned, wherein the first cleaning is alkaline cleaning.

7. The method for blackening a metal grid according to claim 6, wherein: After the first cleaning of the blackened metal grid, the following steps are further included: The metal grid after the first cleaning is subjected to a second cleaning, wherein the second cleaning is alcohol cleaning or ketone cleaning.

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