Silver nanowire touch module and preparation method, touch screen and terminal device

Abstract

The present invention discloses a silver nanowire touch module and preparation method, a touch screen, and a terminal device. The method comprises coating silver nanowire ink on a flexible substrate to form a silver nanowire layer, coating an OC layer on the silver nanowire layer, coating a positive photoresist on the OC layer to form a positive photoresist layer, and obtaining a positive photoresist-covered silver nanowire film; then exposing and developing the film under yellow light, etching, and stripping the film; silk-screening silver paste and laser etching the stripped silver nanowire film, respectively laminating upper and lower lines and OCA glue to obtain a silver nanowire touch module. The method can achieve the effect of fine etching lines and is not prone to side etching. The method uses a stripping solution mixed with a polar organic solvent and an alkaline solvent, which solves the problems of severe etching lines and secondary staining during the stripping process, ensures the weather resistance of the silver nanowire touch module, and has the advantages of fast etching speed and low cost, making it suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of transparent conductive film materials and relates to a silver nanowire touch module and a preparation method thereof, a touch screen and a terminal device. Background Art

[0002] With the increasing application of silver nanowires in touchscreens, the shortcomings of laser etching for touchscreen modules, such as slow speed, high cost, and difficulty meeting industrial mass production targets, have become increasingly apparent. Silver nanowire touchscreen modules are etched using a negative dry film (negative photoresist) with yellow photolithography. Due to their rough surface structure and the numerous gaps between the silver nanowires and the negative dry film, they are prone to severe undercutting and overetching of the channels. Furthermore, silver nanowire touchscreen modules are prone to severe etch streaks during the etching process of positive photoresist coatings. The use of oxidants during the etching process can lead to secondary staining of the touchscreen module during the stripping process, or direct staining by colored oxidants (such as KMnO4, CuCl2, and FeCl3) during the etching process. Traditional yellow photolithography results in poor weather resistance for silver nanowire touchscreen modules, directly impacting their service life and potentially leading to the abandonment of this process route. This compromises the technical and cost advantages of the yellow photolithography process, which offers high etching speed and low cost.

[0003] The current industrial process for producing large-scale silver nanowire touch modules is laser etching. While this process is inefficient and costly, it avoids the degradation of silver nanowires' weather resistance and even device failure during the yellow light etching process, leading to its widespread adoption by silver nanowire touch module manufacturers. However, yellow light etching, as a mature etching process, offers advantages over laser etching, including faster etching speeds and lower costs, potentially further reducing the cost of silver nanowire touch modules and promoting their widespread use. Therefore, there is an urgent need to address the technical challenges of yellow light etching for silver nanowire touch modules, such as severe undercutting and overetching, the tendency to stain during stripping due to etching with strong oxidants, and poor weather resistance. Summary of the Invention

[0004] In order to overcome the technical problems in the prior art of silver nanowire touch modules, such as severe side etching and overetching during the yellow light process, easy staining during the film stripping process caused by etching with strong oxidants, and poor weather resistance, the present invention aims to provide a silver nanowire touch module and a preparation method, a touch screen and a terminal device. The etching method can produce fine patterns that are not prone to side etching. By using an etching solution containing an oxidizing salt, the developed film undergoes oxidative bleaching, avoiding staining by dark-colored positive photoresist during the film stripping process, and ensuring the environmental weather resistance of the touch module. The method has the advantages of fast etching speed and low cost, and is suitable for large-scale industrial production.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a silver nanowire touch module comprises the following steps:

[0007] coating silver nanowire ink on a flexible substrate to form a silver nanowire layer, coating an OC layer on the silver nanowire layer, coating a positive photoresist on the OC layer to form a positive photoresist layer, and obtaining a positive photoresist-covered silver nanowire film;

[0008] Expose and develop the silver nanowire film covered with positive photoresist under yellow light;

[0009] The developed film is etched using an etching solution, wherein the etching solution includes an oxidizing salt and a weak acid;

[0010] Stripping the silver nanowire film after etching and patterning;

[0011] The silver nanowire film after stripping is screen-printed with silver paste and laser etched, and then attached with upper and lower lines and OCA glue respectively to obtain a silver nanowire touch module.

[0012] Furthermore, the flexible substrate is a transparent polyethylene terephthalate film or a transparent polyimide film; the substrate is pre-aged before being coated with silver nanowires, and the pre-aging temperature is 140° C.-160° C. and the time is 30 minutes;

[0013] The silver nanowire coating method adopts the slot coating method, the speed of the silver nanowire coating machine is 1m / min-6m / min, the pump speed is 30rpm-60rpm, and the drying temperature is 80℃-120℃;

[0014] The OC layer is slit-coated on the silver nanowire layer at a vehicle speed of 1 m / min-4 m / min, a pump speed of 400 rpm-800 rpm, a drying temperature of 50°C-100°C, and then dried and solidified;

[0015] In a darkroom environment, slit coating or roller coating of positive photoresist is performed on the OC layer. The vehicle speed for coating positive photoresist is 1m / min-4m / min, the pump speed is 350rpm-450rpm, and the drying temperature is 55℃-85℃;

[0016] The thickness of the OC layer is 50nm-100nm;

[0017] The thickness of the positive photoresist layer is 0.5um-2um.

[0018] Furthermore, the positive photoresist-covered silver nanowire film is developed and etched under yellow light as follows:

[0019] The positive photoresist-covered silver nanowire film is baked under yellow light conditions, then exposed, and finally immersed in an alkaline solution for development and drying;

[0020] The baking temperature is 70°C-90°C;

[0021] The exposure energy is 50mJ / cm 2 -150mJ / cm 2 ;

[0022] The alkaline solution is 0.1mol / L-0.4mol / L KOH or tetramethylammonium hydroxide solution, and the soaking time is 60s-120s;

[0023] The drying temperature is 80℃-140℃ and the drying time is 20min-40min.

[0024] Further, the developed film is etched with an etching solution. The specific process is as follows: the developed film is immersed in the etching solution for 10s-360s, and then washed with water for 10s-180s;

[0025] The etching solution is prepared by adding a 0.1 mol / L-0.4 mol / L acid solution to an oxidizing salt solution, then adding a 0.6 mol / L-3 mol / L acid solution, and stirring for 0.3 h-2 h to obtain an etching solution with a pH value of 4-11; wherein the volume ratio of the oxidizing salt solution to the 0.1 mol / L-0.4 mol / L acid solution is 1-2:1.

[0026] Furthermore, the oxidizing salt is at least one of hypochlorite, chlorite, hypobromite, bromite and hypoiodite;

[0027] The acid is at least one of malic acid, gluconic acid, formic acid, lactic acid, benzoic acid, acrylic acid, acetic acid, propionic acid and stearic acid;

[0028] The concentration of the oxidizing salt is 0.1 mol / L-3 mol / L.

[0029] Furthermore, the process of stripping the etched film is as follows:

[0030] The etched film is immersed in a stripping solution for 10s-120s, washed for 10s-120s, and blown dry; the stripping solution is a mixture of an alkaline solution and a polar organic solvent in a volume ratio of 0-2:1.

[0031] Furthermore, the polar organic solvent is at least one of acetone, dimethyl sulfoxide, N-methylpyrrolidone, propylene glycol methyl ether acetate, methanol, tetramethylethylenediamine and tetrahydrofuran;

[0032] The alkaline solution is a solution of at least one of sodium hydroxide, potassium hydroxide and basic amino acid.

[0033] A silver nanowire touch module prepared by the preparation method described above.

[0034] A touch screen comprises the silver nanowire touch module as described above and a touch module stacked with the silver nanowire touch module.

[0035] A terminal device includes the touch screen as described above.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention uses positive photoresist for etching, resulting in fewer voids in the etched sample compared to negative photoresist (dry film) applied to the silver nanowire thin film, achieving fine etched lines and less prone to undercutting. The silver nanowire touch module is produced using a yellow light etching process, addressing the severe undercutting and overcutting issues experienced in traditional yellow light etching processes. The oxidizing agent acts as a strong oxidant, and during etching, the etching solution forms stable compounds such as AgCl, AgBr, or AgI on the surface of the developed film, ensuring the weather resistance of the silver nanowire touch module. This method for preparing a silver nanowire touch module offers the advantages of high etching speed and low cost, making it suitable for large-scale industrial production.

[0038] Furthermore, the present invention uses a mixed etching solution of a strong oxidant and a weak acid to form AgCl, AgBr or AgI compounds on the silver nanowires during the etching process, thereby improving the optical performance comparison between the etched and unetched areas of the silver nanowires during the patterning process, enhancing the visual quality of the touch module, and overcoming the problem of currently mainstream strong acid etching solutions that directly remove all silver nanowires, thereby causing severe etching lines in the patterned silver wire film.

[0039] Furthermore, during the etching process of the positive photoresist-covered silver nanowire film using a mixed solution containing an oxidizing salt, the silver wire film undergoes oxidative bleaching, thereby avoiding severe etching lines during the etching process and staining by the dark-colored positive photoresist during the film stripping process.

[0040] Furthermore, the thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0041] Furthermore, the thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0042] Furthermore, in the present invention, a low concentration of 0.1mol / L-0.4mol / L acid solution is first added to the oxidized salt solution, and then an acid solution of 0.6mol / L-3mol / L is added to avoid a violent reaction of the mixed etching solution, and then stirred in the dark for 0.3h-2h to ensure that the solution can stably release effective etching substances for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention and in conjunction with the attached tables, wherein:

[0044] Figure 1 This is a schematic structural diagram of the positive photoresist coated silver nanowire film used in the present invention. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below through embodiments with reference to the accompanying drawings.

[0046] A method for preparing a silver nanowire touch module of the present invention comprises the following steps:

[0047] (1) A positive photoresist is coated on the silver nanowire film. A colorless and transparent flexible substrate such as PET (transparent polyethylene terephthalate film) or CPI (transparent polyimide film) is pre-aged at 140°C-160°C for 30 minutes. Then, silver nanowire ink is coated on the pre-aged flexible substrate to form a silver nanowire layer 3. The silver nanowire ink (silver nanowire) is coated by a slit coating method. The speed of the vehicle for coating the silver nanowires is 1m / min-6m / min, the pump speed is 30rpm-60rpm, and the drying temperature is 80℃-120℃. Then, the OC layer 2 is coated. The speed of the vehicle for coating the OC layer (optical protective layer) is 1m / min-4m / min, the pump speed is 400rpm-800rpm, the drying temperature is 50℃-100℃, and then ultraviolet irradiation is performed for curing. Then, a positive photoresist is roller-coated or slit-coated in a darkroom environment to form a positive photoresist layer 1. The speed of the vehicle for coating the positive photoresist is 1m / min-4m / min, the pump speed is 350rpm-450rpm, and the drying temperature is 55℃-85℃. Finally, a positive photoresist-covered silver nanowire film is obtained, and the structure is as shown. Figure 1 As shown, from top to bottom, there are a positive photoresist layer 1, an OC layer 2 and a silver nanowire layer 3, forming a sandwich structure.

[0048] The silver nanowire film coated with positive photoresist is affixed with a front protective film to prevent physical damage such as wear and scratches to the film.

[0049] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0050] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0051] (2) Development process: Cut the film to be etched under yellow light, remove the positive photoresist and bake it before development. The baking temperature is 70℃-90℃. The silver nanowires coated with positive photoresist are exposed to UV light under an exposure machine with an exposure energy of 50mJ / cm 2 -150mJ / cm 2 After exposure, the sample is immersed in an alkaline solution such as KOH or tetramethylammonium hydroxide at room temperature for 60-120 seconds. The concentration of the alkaline solution is 0.1mol / L-0.4mol / L. After development, the sample is rinsed with deionized water and then post-baked under yellow light at a temperature of 80°C-140°C for 20-40 minutes.

[0052] (3) Etching process: The etching solution used is a mixed solution of an oxidizing salt and a weak acid, and uses an oxidizing salt (at least one of hypochlorite (sodium hypochlorite or potassium hypochlorite), chlorite (sodium chlorite or potassium chlorite), hypobromite (sodium hypobromite or potassium hypobromite), bromite (sodium bromite or potassium bromite), and hypoiodite (sodium hypoiodite or potassium hypoiodite)) and a weak acid (the weak acid includes at least one of malic acid, gluconic acid, formic acid, lactic acid, benzoic acid, acrylic acid, acetic acid, propionic acid, and stearic acid). The concentration of the oxidizing salt in the etching solution is 0.1 mol / L-3 mol / L, and the concentration of the weak acid is 0.1 mol / L-3 mol / L. This type of etching solution is prepared by adding acid solutions of varying concentrations to an oxidizing salt solution in batches: first adding a low-concentration weak acid solution of 0.1mol / L-0.4mol / L, followed by a 0.6mol / L-3mol / L weak acid solution to prevent a violent reaction in the mixed etching solution. After preparation, the mixture is stirred in the dark for 0.3-2 hours to ensure that the solution can stably release effective etching substances for a long time, ultimately obtaining an etching solution with a pH of 4-11. The volume ratio of the oxidizing salt solution to the low-concentration weak acid solution is 1-2:1, and the volume ratio of the high-concentration weak acid solution is determined by the final pH value of the etching solution.

[0053] The post-baked sample is immersed in an etching solution for 10s-360s, and then rinsed with deionized water for 10s-180s to remove the residual etching solution on the surface, thereby etching an electrical channel on the sample surface;

[0054] In the present invention, two different types of solutions, namely, an oxidizing salt solution and a weak acid solution, are mixed to control the slow release of oxidizing substances in the etching solution.

[0055] By controlling the concentrations of the oxidizing salt solution and the weak acid solution, etching solutions with different pH values ​​are obtained, and the pH value range of the etching solution is 4-11.

[0056] In the present invention, the silver nanowires are oxidized into silver compounds by using oxidizing salts, thereby rendering them electrically non-conductive, thereby meeting the patterning requirements of the touch module.

[0057] (4) Demolding process: In step (3), a strong oxidant (oxidizing salt) is used as an effective component of the etching solution of the present invention, which can etch the electrical channel of the silver nanowire thin film touch module. At the same time, the traditional alkali (such as NaOH, KOH or tetramethylammonium hydroxide, etc.) used as the stripping solution, the positive photoresist dissolved in the stripping solution is very likely to cause the silver nanowire touch module to stain. In order to avoid this adverse effect, the present invention adopts a polar organic solvent (acetone, dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), propylene glycol methyl ether acetate (PGMEA), methanol, tetramethylethylenediamine and tetrahydrofuran at least one), or a mixture of the above organic solvent and an alkaline solution (NaOH, KOH and at least one of alkaline amino acids) as the stripping solution, and the sample soaked in the etching solution is subjected to the demolding process. The sample soaked in the etching solution is soaked in the stripping solution for 10s-120s, then washed in ethanol and deionized water for 10s-120s, and blown dry with compressed air.

[0058] The concentration of the alkaline solution is 0.01-0.5 mol / L, and the volume ratio of the alkaline solution to the organic solvent is 0-2:1.

[0059] (5) Screen-print silver paste on the stripped silver wire film sample, and then dry it at 120℃-150℃. Finally, laser blast the screen-printed silver wire sample to create each conductive channel to obtain a silver wire film sample. Then, use OCA glue to bond the upper and lower lines of the silver wire film sample together to form a silver nanowire touch module.

[0060] Example 1

[0061] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 150°C for 30 minutes. Second, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire coating machine is 3 m / min, the pump speed is 50 rpm, and the drying temperature is 120°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 450 rpm, and a drying temperature of 80°C, and perform UV curing. In a darkroom environment, roll or coat the surface of the silver nanowire film with a positive photoresist at a speed of 3 m / min, a pump speed of 430 rpm, and a drying temperature of 80°C.

[0062] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0063] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0064] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 80°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 80mJ / cm 2 After exposure, the sample was immersed in a 0.2 mol / L KOH solution at room temperature for 90 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 130°C for 30 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0065] (3) First, prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution, and add them to 20 mL of a 1.6 mol / L sodium hypochlorite solution in sequence to avoid a violent reaction of the mixed etching solution, and control the pH value of the etching solution to 4. After the etching solution is prepared, stir it in the dark for 1 hour. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0066] (4) The stripping process uses a mixture of NaOH solution and acetone to remove the residual positive photoresist. First, prepare a 0.1 mol / L NaOH solution and then mix it with acetone; the volume ratio of NaOH solution to acetone is 1:1. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0067] (5) Screen-printing silver paste on the etched silver wire film sample, and then drying it at 130°C. Finally, the screen-printed silver wire sample is laser-processed to produce each conductive channel to obtain a silver wire film sample. Then, OCA glue is used to bond the silver wire film sample to prepare the upper and lower lines of the silver nanowire touch module. The upper and lower lines are bonded to prepare the silver nanowire touch module.

[0068] Example 2

[0069] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 4, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 4 minutes, and then rinsed with deionized water for 30 seconds.

[0070] Example 3

[0071] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 4, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 6 minutes, and then rinsed with deionized water for 30 seconds.

[0072] Example 4

[0073] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 4, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 8 minutes, and then rinsed with deionized water for 30 seconds.

[0074] Example 5

[0075] The same as Example 1, except that, in step 3), the pH value of the etching solution is controlled to 5.5, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0076] Example 6

[0077] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 5.5, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 4 minutes, and then rinsed with deionized water for 30 seconds.

[0078] Example 7

[0079] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 5.5, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 6 minutes, and then rinsed with deionized water for 30 seconds.

[0080] Example 8

[0081] The same as Example 1, except that, in step 3), the pH value of the etching solution is controlled to 5.5, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 8 minutes, and then rinsed with deionized water for 30 seconds.

[0082] Example 9

[0083] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 7, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0084] Example 10

[0085] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 7, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 4 minutes, and then rinsed with deionized water for 30 seconds.

[0086] Example 11

[0087] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 7, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 6 minutes, and then rinsed with deionized water for 30 seconds.

[0088] Example 12

[0089] The same as Example 1, except that in step 3), the pH value of the etching solution is controlled to 7, and after the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film covered positive photoresist sample is immersed in the etching solution for 8 minutes, and then rinsed with deionized water for 30 seconds.

[0090] In Example 1-Example 12, the samples of the silver line thin film covered with positive photoresist were obtained. The etching pH value was 7 and the etching was 2 minutes as described in the present invention. The average channel value of the sample was 109um (design line width 108um), the standard deviation was 1.97um, and the channel deviation from the designed etching pattern was 1.65%. The neutral etching solution was relatively stable, could steadily release effective etching substances, and had less pollution to the environment.

[0091] Table 1 Comparison of channel fineness after yellow photoetching of positive photoresist silver nanowire film at different pH values ​​of etching solution

[0092]

[0093]

[0094] [Note]: 1. Deviation = (channel size after etching - designed channel size) / designed channel size;

[0095] The designed line width of the silver nanowire film channel covered with positive photoresist is 108um.

[0096] Comparative Example 1

[0097] (1) Applying negative photoresist to the silver nanowire film. First, slit-coat the silver nanowires on the PET substrate. The speed of the silver nanowire film is 3 m / min, the pump speed is 50 rpm, and the drying temperature is 120°C. Then, the OC layer (optical protective layer) is coated at a speed of 3 m / min, a pump speed of 450 rpm, and a drying temperature of 80°C. The OC layer is then cured by UV irradiation. Finally, the silver wire film is pre-aged at 150°C for 30 minutes.

[0098] (2) Cut the silver nanowire film under yellow light conditions and apply negative photoresist (dry film) to the surface of the silver nanowire film using a laminator. The laminating temperature of the laminator is 80°C, the pressing roller temperature is 120°C, the laminating pressure is 60 PSI, the laminating speed is 1.5 m / min, and the laminating time is 1 s.

[0099] (3) The silver nanowires bonded to the negative dry film were exposed to UV light in an exposure machine under yellow light conditions with an exposure energy of 80 mJ / cm 2 After exposure, the sample was immersed in a 0.15 mol / L NaCO3 alkaline solution at room temperature for 90 s, then rinsed in deionized water for 10 s and dried with compressed air.

[0100] (4) First, prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution, and add them to 20 mL of a 1.6 mol / L sodium hypochlorite solution in sequence to prevent the mixed etching solution from reacting violently, and control the pH value of the etching solution to 4. After the etching solution is prepared, stir it in the dark for 1 hour, and soak the silver nanowire film-bonded negative dry film sample in the etching solution for 1 minute, and then rinse with deionized water for 30 seconds.

[0101] (5) The film stripping process uses NaOH solution to soak the residual negative dry film. The concentration of NaOH solution is prepared to be 0.1 mol / L. After etching, the sample is soaked in the stripping solution for 30 seconds, then rinsed in deionized water for 10 seconds and blown dry with compressed air.

[0102] (6) Screen-print silver paste on the etched silver wire film sample, and then dry it at 130°C. Finally, the screen-printed silver wire sample is laser-cut to produce each conductive channel.

[0103] Comparative Example 2

[0104] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 4. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0105] Comparative Example 3

[0106] The same as comparative example 1, except that in step (4), the pH value of the etching solution is controlled to be 4. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 3 minutes, and then rinsed with deionized water for 30 seconds.

[0107] Comparative Example 4

[0108] The same as comparative example 1, except that in step (4), the pH value of the etching solution is controlled to be 4. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 4 minutes, and then rinsed with deionized water for 30 seconds.

[0109] Comparative Example 5

[0110] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 5.5. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 1 minute, and then rinsed with deionized water for 30 seconds.

[0111] Comparative Example 6

[0112] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 5.5. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0113] Comparative Example 7

[0114] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 5.5. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 3 minutes, followed by rinsing with deionized water for 30 seconds.

[0115] Comparative Example 8

[0116] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution was controlled to be 5.5. After the etching solution was prepared, it was stirred in the dark for 1 hour. The silver nanowire film-laminated negative dry film sample was immersed in the etching solution for 4 minutes and then rinsed with deionized water for 30 seconds.

[0117] Comparative Example 9

[0118] The same as comparative example 1, except that in step (4), the pH value of the etching solution is controlled to be 7. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 1 minute, and then rinsed with deionized water for 30 seconds.

[0119] Comparative Example 10

[0120] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 7. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0121] Comparative Example 11

[0122] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 7. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 3 minutes, and then rinsed with deionized water for 30 seconds.

[0123] Comparative Example 12

[0124] The same as Comparative Example 1, except that in step (4), the pH value of the etching solution is controlled to be 7. After the etching solution is prepared, it is stirred in the dark for 1 hour, and the silver nanowire film-laminated negative dry film sample is immersed in the etching solution for 4 minutes, and then rinsed with deionized water for 30 seconds.

[0125] Comparative Examples 1-12 obtained the optimal etching parameters for silver nanowire thin film samples bonded to negative dry film, using an etching solution with a pH of 7 and etching for 2 minutes. The average channel size of the samples was 101.14 μm, with a standard deviation of 3.07 μm and a deviation of 1.14% from the designed etched pattern. Furthermore, the neutral etching solution was relatively stable. However, the channels produced in all comparative examples were somewhat larger than the designed channels. This indicates that the rough surface structure of silver nanowires bonded to negative dry film creates gaps between the negative dry film and the silver nanowires, which can easily lead to severe undercutting and overetching of the channels, hindering the refined fabrication of silver wire touch devices. Comparing Examples 1-12 with Comparative Examples 1-12, the silver nanowire samples bonded to negative dry film are not conducive to the fine etching of touch modules.

[0126] Table 2 Comparison of channel fineness after yellow photoetching of negative dry film silver nanowire film at different pH values ​​of etching solution in Examples 1 to 12

[0127]

[0128]

[0129] 2. The designed line width of the silver nanowire film channel bonded to the negative dry film is 100 μm.

[0130] Compared with the various process conditions of Examples 1 to 12, the silver wire film sample covered with positive photoresist has smaller standard deviation of the channel after etching and smaller deviation after etching, and the size of the etched channel is basically distributed around the designed line width, which indicates that the yellow light etching process for manufacturing silver wire touch samples can improve the fineness of the yellow light etching process of the silver nanowire film, and avoid the serious side etching and over etching of the silver nanowire touch module sample covered with negative photoresist during the yellow light etching process.

[0131] Example 13

[0132] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 150°C for 30 minutes. Next, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire film is 3 m / min, the pump speed is 50 rpm, and the drying temperature is 120°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 450 rpm, and a drying temperature of 80°C, and perform UV curing. In a darkroom environment, roll or coat the silver nanowire film with a positive photoresist at a speed of 3 m / min, a pump speed of 430 rpm, and a drying temperature of 80°C.

[0133] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0134] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0135] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 80°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 80mJ / cm 2 After exposure, the sample was immersed in a 0.2 mol / L KOH alkaline solution at room temperature for 90 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 130°C for 30 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0136] (3) First, prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution. These are added to 20 mL of a 1.6 mol / L sodium hypochlorite solution in sequence to prevent the mixed etching solution from reacting violently, and the pH value of the etching solution is controlled to 7. After the etching solution is prepared, stir in the dark for 1 hour. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0137] (4) The stripping process uses a mixed solution of a polar organic solvent (acetone) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, prepare a NaOH solution with a concentration of 0.1 mol / L and then mix it with the polar organic solvent; the volume ratio of NaOH solution to polar organic solvent is 1:0. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0138] (5) Screen-print silver paste on the etched silver wire film sample, and then dry it at 130°C. Finally, the screen-printed silver wire sample is laser-cut to produce each conductive channel.

[0139] Example 14

[0140] The same as Example 13, except that in step (4), the volume ratio of the polar organic solvent (acetone) to the NaOH solution is 1:0.2. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0141] Example 15

[0142] The same as Example 13, except that in step (4), the volume ratio of the polar organic solvent (acetone) to the NaOH solution is 1:0.6. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0143] Example 16

[0144] The same as Example 13, except that in step (4), the volume ratio of the polar organic solvent (acetone) to the NaOH solution is 1:1. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0145] Example 17

[0146] The same as Example 13, except that in step (4), the volume ratio of the polar organic solvent (acetone) to the NaOH solution is 1:2. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0147] Example 18

[0148] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (PGMEA) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0. After etching, the sample is immersed in the stripping solution for 10 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0149] Example 19

[0150] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (PGMEA) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0.2. After etching, the sample is immersed in the stripping solution for 10 seconds, then rinsed in ethanol and deionized water for 10 seconds, respectively, and blown dry with compressed air.

[0151] Example 20

[0152] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (PGMEA) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0.6. After etching, the sample is soaked in the stripping solution for 10 seconds, then rinsed in ethanol and deionized water for 10 seconds, respectively, and blown dry with compressed air.

[0153] Example 21

[0154] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (PGMEA) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:1. After etching, the sample is immersed in the stripping solution for 10 seconds, then rinsed in ethanol and deionized water for 10 seconds, respectively, and blown dry with compressed air.

[0155] Example 22

[0156] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (PGMEA) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:2. After etching, the sample is immersed in the stripping solution for 90 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0157] Example 23

[0158] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (DMSO) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0159] Example 24

[0160] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (DMSO) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0.2. After etching, the sample is soaked in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0161] Example 25

[0162] The same as Example 13, except that, in step (4), the stripping process uses a mixed solution of a polar organic solvent (NMP) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0. After etching, the sample is soaked in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0163] Example 26

[0164] The same as Example 13, except that, in step (4), the film stripping process uses a mixed solution of a polar organic solvent (NMP) and a NaOH solution to remove the positive photoresist remaining on the sample after yellow light etching. First, a NaOH solution with a concentration of 0.1 mol / L is prepared and then mixed with the polar organic solvent; the volume ratio of the polar organic solvent to the NaOH solution is 1:0.2. After etching, the sample is soaked in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds respectively, and blown dry with compressed air.

[0165] By comparing Examples 13 to 26, it can be found that when the volume ratio of acetone to NaOH is 1:0.6, the volume ratio of propylene glycol methyl ether acetate (PGMEA) to NaOH is 1:1, and the volume ratio of dimethyl sulfoxide (DMSO) to NaOH is 1:0.2, the transmittance, haze, and chromaticity (L*, a*, b* values) of the etched sample using only NMP solvent are similar to those of the unetched area. Furthermore, the yellowing value of the etched sample is further optimized (i.e., reduced) compared to the unetched area. The optical properties of the silver nanowire film sample covered with positive photoresist in the stripping solution of the polar solvent, alkaline solution, and polar organic solvent mixture described in the present invention are improved (no significant difference occurs between the etched and unetched areas), enhancing the visual quality of the touch module. During the etching process of the positive photoresist-covered silver nanowire film using a strong oxidant mixture, the silver wire film undergoes oxidative bleaching, preventing staining by the darker positive photoresist during the stripping process. The silver nanowire touch module samples were not stained by brown or dark positive photoresist, which would cause the touch module to appear yellowish, thus preventing colored oxidants (such as KMnO4, CuCl2 and FeCl3) from directly staining the touch module during the etching process.

[0166] Table 3 Comparison of optical properties of positive photoresist silver nanowire films after treatment with different types of stripping solutions in Examples 13 to 26

[0167]

[0168]

[0169] Note: The volume ratio of the stripping solution is the volume ratio of the polar organic solvent to the NaOH solution.

[0170] Unetched area sample 1 and unetched area sample 2 are two samples randomly taken from the unetched area, ie, the area after large-area exposure, for the purpose of comparison with the etched area to illustrate the optical performance.

[0171] Comparative Example 13

[0172] (1) Coating positive photoresist on the silver nanowire film. First, pre-aging the PET substrate at 150°C for 30 minutes. Then, the silver nanowires are coated using a slit coating method. The speed of the silver nanowire film is 3m / min, the pump speed is 50rpm, and the drying temperature is 120°C. The speed of the OC layer (optical protective layer) is 3m / min, the pump speed is 450rpm, the drying temperature is 80°C, and UV curing is performed. In a darkroom environment, positive photoresist is roller-coated or coated on the surface of the silver nanowire film at a speed of 3m / min, a pump speed of 430rpm, and a drying temperature of 80°C.

[0173] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver wire film and bake it before development at a temperature of 80°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 80mJ / cm 2 After exposure, the samples were immersed in a 0.2 mol / L KOH alkaline solution at room temperature for 90 seconds. After development, the samples were rinsed with deionized water and then post-baked under yellow light at 130°C for 30 minutes.

[0174] (3) First, prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution. These are added to 20 mL of a 1.6 mol / L sodium hypochlorite solution in sequence to prevent the mixed etching solution from reacting violently, and the pH value of the etching solution is controlled to 7. After the etching solution is prepared, stir in the dark for 1 hour. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 2 minutes and then rinsed with deionized water for 30 seconds.

[0175] (4) In the stripping process, 1.25 mol / L NaOH solution was used as the stripping solution to remove the residual positive photoresist from the yellow photoetched samples. The stripping temperature was controlled at 25°C. After etching, the samples were immersed in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0176] (5) Screen-print silver paste on the etched silver wire film sample, and then dry it at 130°C. Finally, the screen-printed silver wire sample is laser-cut to produce each conductive channel.

[0177] Comparative Example 14

[0178] The same as Comparative Example 13, except that, in step (4), the film stripping process uses a 1.25 mol / L NaOH solution as the stripping solution to remove the positive photoresist remaining on the yellow photoetched sample. The film stripping temperature is controlled at 45°C. After etching, the sample is soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0179] Comparative Example 15

[0180] The same as Comparative Example 13, except that, in step (4), the stripping process uses a 2.5 mol / L NaOH solution as the stripping solution to remove the positive photoresist remaining on the yellow photoetched sample. The stripping temperature is controlled at 25°C. After etching, the sample is soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0181] Comparative Example 16

[0182] The same as Comparative Example 13, except that, in step (4), the stripping process uses a 2.5 mol / L NaOH solution as the stripping solution to remove the positive photoresist remaining on the yellow photoetched sample. The stripping temperature is controlled at 45°C. After etching, the sample is soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0183] Comparative Example 17

[0184] The same as Comparative Example 13, except that, in step (4), the film stripping process uses a mixture of 1.25 mol / L NaOH solution and ethanol as the stripping solution to remove the positive photoresist remaining on the yellow photoetched sample. The film stripping temperature is controlled at 25°C. After etching, the sample is soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0185] Comparative Example 18

[0186] The same as Comparative Example 13, except that, in step (4), a mixture of 1.25 mol / L NaOH solution and ethanol was used as the stripping solution to remove the residual positive photoresist from the yellow photoetched sample. The stripping temperature was controlled at 45°C. After etching, the sample was soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0187] Comparative Example 19

[0188] The same as Comparative Example 13, except that, in step (4), a mixture of 2.5 mol / L NaOH solution and ethanol was used as the stripping solution to remove the residual positive photoresist from the yellow photoetched sample. The stripping temperature was controlled at 25°C. After etching, the sample was soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0189] Comparative Example 20

[0190] The same as Comparative Example 13, except that, in step (4), a mixture of 2.5 mol / L NaOH solution and ethanol was used as the stripping solution to remove the residual positive photoresist from the yellow photoetched sample. The stripping temperature was controlled at 45°C. After etching, the sample was soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0191] Comparative Example 21

[0192] The same as Comparative Example 13, except that, in step (4), ethanol was used as the stripping solution to remove the residual positive photoresist from the yellow photoetched sample. The stripping temperature was first controlled at 25°C. After etching, the sample was soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0193] Comparative Example 22

[0194] The same as Comparative Example 13, except that, in step (4), ethanol was used as the stripping solution to remove the residual positive photoresist from the yellow photoetched sample. The stripping temperature was first controlled at 45°C. After etching, the sample was soaked in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0195] Comparisons of Comparative Examples 13-22 reveal that, when a NaOH solution is used to strip the silver nanowire touch panel coated with a positive photoresist, transmittance decreases by approximately 10% and haze increases by 2% with low-concentration (1.25 mol / L) NaOH stripping. Transmittance decreases by 10% with high-concentration (2.5 mol / L) NaOH stripping, while haze increases by 4%. At 45°C, NaOH stripping increases the yellowing (b*) by 3-12. Using a mixture of NaOH and ethanol for stripping reduces transmittance by approximately 20%, increases yellowing by 1-6, and degrades haze in some samples. Using ethanol for stripping increases haze in the silver nanowire touch panel, reaching between 7 and 8, a two-fold increase compared to the haze observed in the unetched areas or when using polar organic solvents, or polar organic solvents and alkaline solvents, degrading the optical performance of the touch panel photoresist. In summary, the transmittance of the silver nanowire touch samples in the NaOH solution and the mixed stripping solution of NaOH solution and ethanol decreased, or the haze increased, or was stained by the dark positive photoresist, which reduced the optical performance of the silver nanowire touch module and seriously hindered its application in the touch field.

[0196] Table 4 Comparison of optical properties of the silver nanowire film covered with positive photoresist after being treated with NaOH solution, ethanol or NaOH and ethanol mixed stripping solution in Comparative Examples 13 to Comparative Examples 22

[0197]

[0198] [Note]: 1. The volume ratio of NaOH solution to ethanol is 1:1.

[0199] Example 27

[0200] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 150°C for 30 minutes. Next, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire film is 3 m / min, the pump speed is 50 rpm, and the drying temperature is 120°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 450 rpm, and a drying temperature of 80°C, and perform UV curing. Roll or apply a positive photoresist on the surface of the silver nanowire film in a darkroom environment at a speed of 3 m / min, a pump speed of 430 rpm, and a drying temperature of 80°C.

[0201] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0202] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0203] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 80°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 80mJ / cm 2 After exposure, the sample was immersed in a 0.2 mol / L KOH alkaline solution at room temperature for 90 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 130°C for 30 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0204] (3) First, prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution. These are added to 20 mL of a 1.6 mol / L sodium hypochlorite solution in sequence to prevent the mixed etching solution from reacting violently, and the pH value of the etching solution is controlled to 7. After the etching solution is prepared, stir in the dark for 1 hour. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 2 minutes, and then rinsed with deionized water for 30 seconds.

[0205] (4) The stripping process uses a mixture of 0.1 mol / L NaOH solution and acetone as the stripping solution to remove the positive photoresist remaining on the sample after yellow photoetching. The volume ratio of acetone to NaOH solution is 1:0.6. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0206] (5) Screen-print silver paste on the etched silver wire film sample, and then dry it at 130°C. Finally, the screen-printed silver wire sample is laser-cut to make the conductive channel of the sample, and then the upper and lower limits of the silver wire film sample are bonded with OCA glue to make a touch module.

[0207] The touch module prepared in Example 27 was tested under low temperature, high temperature, high humidity and heat, and QUV conditions. The test conditions are shown in Table 6, and the test results are shown in Table 5.

[0208] Example 28

[0209] The same as Example 27, except that, in step (4), the film stripping process uses a mixed solution of 0.1 mol / L NaOH solution and PGMEA as the stripping solution to remove the positive photoresist remaining on the sample after yellow photoetching. The volume ratio of NaOH solution to PGMEA is 1:1. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0210] The touch module prepared in Example 28 was tested under low temperature, high temperature, high humidity and heat, and QUV conditions. The test conditions are shown in Table 6, and the test results are shown in Table 5.

[0211] Example 29

[0212] The same as Example 27, except that, in step (4), a mixed solution of 0.1 mol / L NaOH solution and DMSO was used as the stripping solution to remove the positive photoresist remaining on the sample after yellow photoetching. The volume ratio of DMSO to NaOH solution was 1:0.2. After etching, the sample was soaked in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0213] The touch module prepared in Example 29 was tested under low temperature, high temperature, high humidity and heat, and QUV conditions. The test conditions are shown in Table 6, and the test results are shown in Table 5.

[0214] Example 30

[0215] The same as Example 27, except that, in step (4), the stripping process uses NMP alone as a stripping solution to remove the positive photoresist remaining on the sample after yellow light etching. After etching, the sample is soaked in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0216] The touch module prepared in Example 30 was tested under low temperature, high temperature, high humidity and heat, and QUV conditions. The test conditions are shown in Table 6, and the test results are shown in Table 5.

[0217] As can be seen from Examples 27-30, the weather resistance of silver nanowire touch modules prepared from samples coated with positive photoresist silver wire thin films in the stripping solution of a mixed alkaline solution and polar organic solvent described herein is comparable to that of samples etched using conventional yellow light. Table 5 compares the weather resistance of silver nanowire touch modules treated with different stripping solutions. See Table 6 for relevant weather resistance criteria and test conditions. A comparison of the weather resistance of silver nanowire touch modules stripped with acetone, PGMEA, and DMSO mixed with NaOH, respectively, and NMP solution alone reveals minimal changes before and after low-temperature, high-temperature, and high-humidity weathering tests, meeting weathering test standards. However, the change in UV (QUV) resistance is relatively significant, particularly for samples treated with PGMEA, which showed a 13% change. This is primarily due to the residual OC (optical protective layer) remaining after stripping of the silver nanowire touch modules treated with PGMEA and NaOH, making them difficult to pass QUV testing. This is primarily due to the QUV test inducing the generation and migration of silver particles and accelerating the sulfidation of silver ions. However, silver touch screen products stripped using acetone, DMSO and NaOH mixtures, and NMP alone were able to pass the QUV test. In summary, the silver touch screen modules fabricated using this yellow light process can generally guarantee the device's weather resistance.

[0218] Table 5 Comparison of weather resistance of silver nanowire touch modules obtained by treatment with different types of stripping solutions in Examples 27-30

[0219]

[0220]

[0221] Table 6 Weather resistance judgment criteria and test conditions

[0222]

[0223] Example 31

[0224] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 150°C for 30 minutes. Second, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire coating machine is 3 m / min, the pump speed is 50 rpm, and the drying temperature is 120°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 450 rpm, and a drying temperature of 80°C, and perform UV curing. In a darkroom environment, roll or coat the surface of the silver nanowire film with a positive photoresist at a speed of 3 m / min, a pump speed of 430 rpm, and a drying temperature of 80°C.

[0225] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0226] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0227] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 80°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 80mJ / cm 2 After exposure, the sample was immersed in a 0.2 mol / L KOH solution at room temperature for 90 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 130°C for 30 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0228] (3) First, prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution, and add them to 20 mL of a 1.6 mol / L sodium chlorite solution in sequence to avoid a violent reaction of the mixed etching solution, and control the pH value of the etching solution to 4. After the etching solution is prepared, stir it in the dark for 1 hour. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 4 minutes, and then rinsed with deionized water for 30 seconds.

[0229] (4) The stripping process uses a mixture of KOH solution and methanol to remove the residual positive photoresist. First, prepare a KOH solution with a concentration of 0.1 mol / L and then mix it with methanol; the volume ratio of KOH solution to methanol is 1:1. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0230] (5) Screen-printing silver paste on the etched silver wire film sample, and then drying it at 130°C. Finally, the screen-printed silver wire sample is laser-processed to produce each conductive channel to obtain a silver wire film sample. Then, OCA glue is used to bond the silver wire film sample to prepare the upper and lower lines of the silver nanowire touch module. The upper and lower lines are bonded to prepare the silver nanowire touch module.

[0231] Example 32

[0232] The same as Example 31, except that, in step 3), first prepare 20 mL of a low concentration of 0.2 mol / L glacial acetic acid solution, and then prepare 1000 mL of a 1 mol / L glacial acetic acid solution, which are added to 20 mL of a mixed solution of sodium hypobromite and sodium bromite, respectively. The total concentration of sodium hypobromite and sodium bromite in the mixed solution is 1.6 mol / L to avoid a violent reaction of the mixed etching solution, and the pH value of the etching solution is controlled to 4. After the etching solution is prepared, it is stirred in the dark for 1 hour. The silver nanowire film covered with positive photoresist is immersed in the etching solution for 6 minutes, and then rinsed with deionized water for 30 seconds.

[0233] The same method as Example 31 was used, except that in step 4), the stripping process used a mixture of an alkaline amino acid solution and tetramethylethylenediamine to remove residual positive photoresist. First, a 0.1 mol / L alkaline amino acid solution was prepared and then mixed with tetramethylethylenediamine; the volume ratio of the alkaline amino acid solution to tetramethylethylenediamine was 1:1. After etching, the sample was soaked in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0234] Example 33

[0235] The same as Example 31, except that, in step 3), first prepare 20 mL of a low-concentration 0.2 mol / L glacial acetic acid solution, then prepare 1000 mL of a 1 mol / L glacial acetic acid solution, and add them to 20 mL of a 1.6 mol / L potassium hypoiodite solution, respectively, to avoid a violent reaction of the mixed etching solution, and control the pH value of the etching solution to 4. After the etching solution is prepared, stir in the dark for 1 hour, and the silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 8 minutes, followed by rinsing with deionized water for 30 seconds.

[0236] (4) The stripping process uses a mixture of KOH solution and tetrahydrofuran to remove the residual positive photoresist. First, prepare a KOH solution with a concentration of 0.1 mol / L and then mix it with tetrahydrofuran; the volume ratio of KOH solution to tetrahydrofuran is 1:1. After etching, the sample is immersed in the stripping solution for 30 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and blown dry with compressed air.

[0237] Example 34

[0238] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 140°C for 30 minutes. Next, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire coating machine is 3 m / min, the pump speed is 60 rpm, and the drying temperature is 80°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 600 rpm, and a drying temperature of 50°C, and perform UV curing. In a darkroom environment, roll or coat the surface of the silver nanowire film with a positive photoresist at a speed of 4 m / min, a pump speed of 450 rpm, and a drying temperature of 85°C.

[0239] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0240] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0241] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 75°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 50mJ / cm 2 After exposure, the sample was immersed in a 0.1 mol / L tetramethylammonium hydroxide solution at room temperature for 110 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 130°C for 30 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0242] (3) First, prepare 20 mL of a low-concentration mixed solution of malic acid and gluconic acid, with a total concentration of malic acid and gluconic acid of 0.3 mol / L; then prepare a high-concentration mixed solution of malic acid and gluconic acid, with a total concentration of malic acid and gluconic acid of 3 mol / L, and add them to 20 mL of 0.1 mol / L sodium hypoiodite solution in sequence to avoid a violent reaction of the mixed etching solution, and control the pH value of the etching solution to 4. After the etching solution is prepared, stir in the dark for 1.5 h. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 360 s, and then rinsed with deionized water for 100 s.

[0243] (4) The stripping process uses a mixed solution of alkaline amino acid solution and PGMEA to remove the residual positive photoresist. First, prepare an alkaline amino acid solution with a concentration of 0.01 mol / L and then mix it with acetone; the volume ratio of alkaline amino acid solution to PGMEA is 1:1. After etching, the sample is immersed in the stripping solution for 10 seconds, then rinsed in ethanol and deionized water for 50 seconds respectively, and blown dry with compressed air.

[0244] (5) Screen-printing silver paste on the etched silver wire film sample, and then drying it at 140°C. Finally, the screen-printed silver wire sample is laser-processed to produce each conductive channel to obtain a silver wire film sample. Then, OCA glue is used to bond the silver wire film sample to prepare the upper and lower lines of the silver nanowire touch module. The upper and lower lines are bonded to prepare the silver nanowire touch module.

[0245] Example 32

[0246] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 150°C for 30 minutes. Next, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire coating machine is 3 m / min, the pump speed is 40 rpm, and the drying temperature is 110°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 800 rpm, and a drying temperature of 100°C, and perform UV curing. Roll or apply a positive photoresist on the surface of the silver nanowire film in a darkroom environment at a speed of 2 m / min, a pump speed of 400 rpm, and a drying temperature of 55°C.

[0247] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0248] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0249] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 90°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 150mJ / cm 2 After exposure, the sample was immersed in a 0.4 mol / L KOH solution at room temperature for 60 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 140°C for 20 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0250] (3) First, prepare a 20 mL low-concentration mixed solution of formic acid, lactic acid, and benzoic acid, with a total concentration of 0.5 mol / L. Then, prepare a mixture of formic acid, lactic acid, and benzoic acid, with a total concentration of 0.6 mol / L. Add them to 20 mL of 3 mol / L sodium hypochlorite solution in sequence to avoid a violent reaction of the mixed etching solution, and control the pH value of the etching solution to 11. After the etching solution is prepared, stir in the dark for 2 h. The silver nanowire film covered with positive photoresist sample is immersed in the etching solution for 200 s and then rinsed with deionized water for 180 s.

[0251] (4) The stripping process uses a mixture of KOH solution and DMSO to remove the residual positive photoresist. First, prepare a KOH solution with a concentration of 0.1 mol / L and then mix it with acetone; the volume ratio of KOH solution to DMSO is 2:1. After etching, the sample is immersed in the stripping solution for 120 seconds, then rinsed in ethanol and deionized water for 120 seconds respectively, and blown dry with compressed air.

[0252] (5) Screen-printing silver paste on the etched silver wire film sample, and then drying it at 120°C. Finally, the screen-printed silver wire sample is laser-processed to produce each conductive channel to obtain a silver wire film sample. Then, OCA glue is used to bond the silver wire film sample to prepare the upper and lower lines of the silver nanowire touch module. The upper and lower lines are bonded to prepare the silver nanowire touch module.

[0253] Example 35

[0254] (1) Coating a positive photoresist on the silver nanowire film. First, pre-age the PET substrate at 145°C for 30 minutes. Second, coat the silver nanowires on the pre-aged substrate using a slit coating method. The speed of the silver nanowire coating machine is 3 m / min, the pump speed is 30 rpm, and the drying temperature is 100°C. Then, coat the OC layer (optical protective layer) at a speed of 3 m / min, a pump speed of 400 rpm, and a drying temperature of 90°C, and perform UV curing. In a darkroom environment, roll or coat the surface of the silver nanowire film with a positive photoresist at a speed of 1 m / min, a pump speed of 350 rpm, and a drying temperature of 70°C.

[0255] The thickness of the OC layer is between 50 nm and 100 nm to ensure successful etching of the subsequent silver nanowire film (ie, the silver nanowire layer).

[0256] The thickness of the positive photoresist layer is between 0.5 μm and 2 μm to ensure that the silver nanowire protection area is not etched during the yellow photoetching process.

[0257] (2) Cut the film to be etched under yellow light, remove the positive photoresist of the silver nanowire film and bake it before development at a temperature of 70°C. The silver nanowires coated with positive photoresist are exposed to UV light in an exposure machine at an exposure energy of 100mJ / cm 2 After exposure, the sample was immersed in a 0.3 mol / L KOH solution at room temperature for 120 seconds. After development, the sample was rinsed with deionized water and then post-baked under yellow light at 80°C for 40 minutes to obtain a silver nanowire film covered with a positive photoresist.

[0258] (3) First, prepare a low-concentration mixed solution of 20 mL of acrylic acid, acetic acid, propionic acid and stearic acid, and the total concentration of acrylic acid, acetic acid, propionic acid and stearic acid is 0.1 mol / L; then prepare a mixed solution containing acrylic acid, acetic acid, propionic acid and stearic acid, and the total concentration of acrylic acid, acetic acid, propionic acid and stearic acid is 2 mol / L, and add them to 40 mL of 1 mol / L sodium hypochlorite solution in sequence to avoid violent reaction of the mixed etching solution, and control the pH value of the etching solution to 7. After the etching solution is prepared, stir in the dark for 0.3 h, and soak the silver nanowire film covered positive photoresist sample in the etching solution for 10 s, and then rinse with deionized water for 10 s.

[0259] (4) In the stripping process, a mixture of tetrahydrofuran and NaOH (volume ratio of 1:0.4) was used as a stripping solution to remove the residual positive photoresist. After etching, the sample was immersed in the stripping solution for 80 seconds, then rinsed in ethanol and deionized water for 10 seconds each, and dried with compressed air.

[0260] (5) Screen-printing silver paste on the etched silver wire film sample, and then drying it at 150°C. Finally, the screen-printed silver wire sample is laser-processed to produce each conductive channel to obtain a silver wire film sample. Then, OCA glue is used to bond the silver wire film sample to prepare the upper and lower lines of the silver nanowire touch module. The upper and lower lines are bonded to prepare the silver nanowire touch module.

[0261] The present invention also provides a touch screen comprising the aforementioned silver nanowire touch module and a display panel stacked with the silver nanowire touch module. Preferably, the touch screen is used in consumer electronic touch screens such as children's smart watches and LCD e-books, 7- to 12-inch in-vehicle touch screens, and industrial control screens for various applications.

[0262] The present invention also provides a terminal device, which includes the touch screen.

[0263] The present invention discloses a method for preparing a silver nanowire touch module characterized by coating the silver nanowires with a positive photoresist, chemically etching them using a colorless oxidizing salt and a weak acid as an etching solution, and using a polar organic solvent, or a mixture of a polar organic solvent and an alkaline solution, as a stripping solution. Advantages of this method include: 1) utilizing yellow light etching, a complete yellow light process effectively addresses the severe undercutting and overetching problems experienced by silver nanowire touch modules during traditional yellow light etching; 2) preventing severe etching marks during etching and secondary staining during stripping; and 3) ensuring the environmental weatherability of the silver nanowire touch module. This silver nanowire touch module boasts fast etching speeds and low costs, making it suitable for large-scale industrial production.

Claims

1. A method for preparing a silver nanowire touch module, characterized in that: The following steps are involved: coating silver nanowire ink on a flexible substrate to form a silver nanowire layer, coating an OC layer on the silver nanowire layer, coating a positive photoresist on the OC layer to form a positive photoresist layer, and obtaining a positive photoresist-covered silver nanowire film; Expose and develop the silver nanowire film covered with positive photoresist under yellow light; The developed film is etched using an etching solution; the etching solution comprises an oxidizing salt and a weak acid; the oxidizing salt is at least one of hypochlorite, chlorite, hypobromite, bromite and hypoiodite; The acid is at least one of malic acid, gluconic acid, formic acid, lactic acid, benzoic acid, acrylic acid, acetic acid, propionic acid and stearic acid; The silver nanowire film after etching and patterning is stripped; the process of stripping the etched film is as follows: soaking the etched film in a stripping solution for 10s-120s, washing it for 10s-120s, and drying it; the stripping solution is a mixture of an alkaline solution and a polar organic solvent in a volume ratio of 0-2:1; The silver nanowire film after stripping is screen-printed with silver paste and laser-etched, and then attached with upper and lower wires and OCA glue to obtain a silver nanowire touch module; The specific process of etching the developed film with an etching solution is as follows: soaking the developed film in the etching solution for 10s-360s, and washing with water for 10s-180s; The etching solution is prepared by adding a 0.1 mol / L-0.4 mol / L acid solution to an oxidizing salt solution, then adding a 0.6 mol / L-3 mol / L acid solution, and stirring for 0.3 h-2 h to obtain an etching solution with a pH value of 4-11; wherein the volume ratio of the oxidizing salt solution to the 0.1 mol / L-0.4 mol / L acid solution is 1-2:1; The polar organic solvent is at least one of acetone, dimethyl sulfoxide, N-methylpyrrolidone, propylene glycol methyl ether acetate, methanol, tetramethylethylenediamine and tetrahydrofuran; The alkaline solution is a solution of at least one of sodium hydroxide, potassium hydroxide and basic amino acid.

2. The method for preparing a silver nanowire touch module according to claim 1, wherein: The flexible substrate is a transparent polyethylene terephthalate film or a transparent polyimide film; the substrate is pre-aged and then coated with silver nanowires; the pre-aging temperature is 140° C. to 160° C. and the time is 30 minutes; The silver nanowire coating method adopts the slot coating method, the speed of coating the silver nanowires is 1m / min-6m / min, the pump speed is 30rpm-60rpm, and the drying temperature is 80℃-120℃; The OC layer is slit-coated on the silver nanowire layer at a vehicle speed of 1 m / min-4 m / min, a pump speed of 400 rpm-800 rpm, a drying temperature of 50°C-100°C, and then dried and solidified; In a darkroom environment, slit coating or roller coating of positive photoresist is performed on the OC layer. The vehicle speed for coating positive photoresist is 1m / min-4m / min, the pump speed is 350rpm-450rpm, and the drying temperature is 55℃-85℃. The thickness of the OC layer is 50nm-100nm; The thickness of the positive photoresist layer is 0.5 μm-2 μm.

3. The method for preparing a silver nanowire touch module according to claim 1, wherein: The process of developing and etching the silver nanowire film covered with positive photoresist under yellow light is as follows: The positive photoresist-covered silver nanowire film is baked under yellow light conditions, then exposed, and finally immersed in an alkaline solution for development and drying; The baking temperature is 70°C-90°C; The exposure energy is 50mJ / cm 2 -150mJ / cm 2 ; The alkaline solution is 0.1mol / L-0.4mol / L KOH or tetramethylammonium hydroxide solution, and the soaking time is 60s-120s; The drying temperature is 80℃-140℃ and the drying time is 20min-40min.

4. The method for preparing a silver nanowire touch module according to claim 1, wherein: The concentration of the oxidizing salt is 0.1 mol / L-3 mol / L.

5. A silver nanowire touch module prepared according to the preparation method according to any one of claims 1 to 4.

6. A touch screen, characterized in that: The invention comprises the silver nanowire touch module as claimed in claim 5 and a touch module stacked with the silver nanowire touch module.

7. A terminal device, characterized in that: Comprising the touch screen as claimed in claim 6.

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