A narrow-frame electronic paper display device touch sensor and a production process thereof

Abstract

This invention discloses a touch sensor for a narrow-bezel electronic paper display device and its manufacturing process. It comprises a display area and at least one bending area. By bending the bending area to the side of the electronic paper tablet, the wiring occupied by the front bezel is completely eliminated, achieving a narrow bezel or even zero-bezel design. The touch sensor's flexibility is significantly improved by employing a double-sided F2 structure Metal Mesh and vacuum sputtering and photolithography to prepare the Metal Mesh. The bending area can be bent stably, ensuring that the electrical properties of the touch sensor are not damaged during assembly. The Metal Mesh is prepared using vacuum sputtering and photolithography, resulting in higher touch sensitivity, meeting the high-precision touch and handwriting requirements of electronic paper notebooks. The Metal Mesh grid lines are treated with a full black finish, improving display consistency and visual experience.

Description

Technical Field

[0001] This invention relates to the field of electronic paper touch display technology, specifically to a touch sensor for a narrow-bezel electronic paper display device, and also to the manufacturing process of the touch sensor. Background Technology

[0002] With its core advantages such as low power consumption, paper-like diffuse reflection display effect, and portability, e-paper tablets have become one of the mainstream terminal devices in reading, mobile office, and education. As consumer demand continues to upgrade, users are increasingly demanding higher visual experiences and portability from e-paper tablets. Narrow bezels and even zero bezels have become the core focus of industry competition. The circuit and structural design of touch sensors are key bottlenecks restricting the improvement of screen-to-body ratio in e-paper tablets, and are also technical challenges that the industry urgently needs to solve.

[0003] As a core functional component of e-paper tablets, the touch sensor's bezel wiring connects the sensing circuitry to the external driver chip, serving as a crucial channel for touch signal transmission. Traditionally, the touch sensor bezel wiring in e-paper tablets is fixedly arranged around the front perimeter of the display area. This wiring itself occupies a certain width of bezel space, typically no less than 5mm, making it impossible to achieve truly narrow or zero bezels. This not only severely compromises the product's visual integrity but also increases the overall size of the e-paper tablet, reducing its portability and contradicting the current trend towards lightweight and integrated e-paper tablets.

[0004] To address the narrow bezel issue, several related technologies have been attempted in the industry, but all have significant shortcomings and cannot meet the specific needs of e-paper tablets, failing to fundamentally solve the pain points of existing technologies. Specifically: First, some solutions enhance bending strength by increasing the density of the metal mesh in the folding area, optimizing only the reliability of the circuitry in the folding area. This cannot fundamentally reduce the width of the front bezel and does not consider the optical display characteristics of e-paper. Increased mesh density leads to a deterioration in display quality, conflicting with the display requirements of e-paper. Second, some solutions optimize the lead layout by folding a conductive film into a U-shaped structure. However, the use of silver paste leads is insufficient in conductivity and bending resistance to meet the repeated bending requirements of e-paper tablets. Furthermore, the lack of optical blackening treatment results in severe glare from the silver paste circuitry, significantly degrading the display quality of e-paper and affecting the user's reading experience.

[0005] Meanwhile, existing electronic paper touch sensors still have many technical shortcomings in terms of substrate selection, circuit structure, and manufacturing process, which further restricts the development of narrow-bezel electronic paper tablets. Regarding the circuit structure: When using ITO material as the conductive circuit, the conductivity and bending resistance are poor, and the circuit is prone to breakage after bending, which cannot meet the bending requirements of the frame wiring; Metal Mesh prepared by processes such as chemical plating Mesh and imprinted silver Mesh has problems with insufficient conductivity and poor bending resistance, and the grid lines are easy to show from different viewing angles, which destroys the display consistency of electronic paper; The overall thickness of the circuit pattern is relatively large, which is not conducive to the bending operation of the frame wiring, and it is easy to cause the substrate to peel off from the circuit when bending, affecting the touch stability.

[0006] In terms of optical compatibility: the existing Metal Mesh touch circuitry exhibits severe glare under certain lighting conditions, with the reflected light appearing coppery red, which significantly degrades the display effect of e-paper and fails to meet the optical compatibility requirements of e-paper, thus affecting the user's reading experience.

[0007] Regarding bending reliability: Traditional solutions do not perform targeted stress optimization on the frame wiring, and stress concentration is prone to occur at right angles, leading to problems such as wire breakage, bonding layer separation, and air bubbles, which seriously affect the lifespan of the touch sensor and the stability of touch. Summary of the Invention

[0008] The purpose of this invention is to provide a touch sensor for a narrow-bezel electronic paper display device and its manufacturing process, which can achieve compatibility of narrow bezel, high screen ratio, excellent bending resistance, high conductivity and high optical performance.

[0009] To achieve the above objectives, embodiments of the present invention provide a touch sensor for a narrow-bezel electronic paper display device, including a transparent substrate and a touch circuit disposed on the transparent substrate. The transparent substrate includes a display area and at least one bent area, the bent area being located outside the display area and bent relative to the display area; the touch circuit is arranged in a Metal Mesh structure.

[0010] As a preferred technical solution, the edge of the bending sheet area is connected to a second bending sheet area, and the second bending sheet area is bent relative to the bending sheet area.

[0011] As a preferred technical solution, the touch circuit is a double-sided F2 structure Metal Mesh.

[0012] As a preferred technical solution, the mesh line width of Metal Mesh is 1-5um, the mesh period is 100-1000um, and the sheet resistance of the mesh line is ≤5Ω / □; the mesh shape of Metal Mesh is square, rhombus, hexagon or random polygon.

[0013] As a preferred technical solution, Metal Mesh uses a completely black mesh line treatment.

[0014] As a preferred technical solution, a gap is provided between adjacent bending areas, the gap including two sides, the sides being one or a combination of two or more of the following: straight line segment, curve, and broken line segment.

[0015] To achieve the above objectives, embodiments of the present invention provide a manufacturing process for a touch sensor in a narrow-bezel electronic paper display device, comprising the following steps: The steps for preparing the first blackening layer and copper film are as follows: the first blackening layer is sputtered onto the upper and lower surfaces of the transparent substrate respectively; and then copper films are sputtered onto the surfaces of the two blackening layers respectively. Steps for fabricating Metal Mesh touch circuits; Post-blackening treatment step: Perform post-blackening treatment on the surface and side-etched surfaces of the etched Metal Mesh grid lines; Bending and forming steps: Bending the bending area.

[0016] As a preferred technical solution, in the step of preparing the first blackening layer and copper film, the pretreated transparent substrate is fed into a vacuum sputtering equipment, and the vacuum degree is controlled at [value missing]. The temperature of the transparent substrate is controlled at 60℃-80℃, and the thickness of the first blackening layer is 20-80nm. Then, copper films are sputtered on the surfaces of the two first blackening layers, with a thickness of 200-700nm. In step three, when performing post-blackening treatment on the surface of the etched Metal Mesh grid lines and the side-etched surface, a second blackening layer is prepared by using a selenite series blackening solution, with a thickness of 10-100nm.

[0017] As a preferred technical solution, in the step of fabricating the Metal Mesh touch circuit, photolithography is used to fabricate a double-sided F2 structure Metal Mesh touch circuit; photoresist is coated on the copper film surface, and ultraviolet exposure and development processes are used to transfer the double-sided F2 structure Metal Mesh touch circuit pattern onto the photoresist; then, etching is used to remove the copper film not protected by the photoresist and the first blackening layer, forming the driving circuit layer, the sensing circuit layer and the frame traces.

[0018] As a preferred technical solution, when the two bending areas are adjacent, a gap is opened in the clearance area between the adjacent bending areas after the post-blackening treatment step.

[0019] The above technical solution has the following significant beneficial effects: 1. Significantly improved screen-to-body ratio and better visual experience: The transparent substrate includes a display area and at least one bent area. By bending the bent area to the side of the e-paper tablet or the junction of the side and back edge, the wiring of the front bezel is completely eliminated, achieving a narrow bezel or even a zero bezel design. The screen-to-body ratio can be increased to over 95%, and can reach up to 98%. This solves the core pain point of excessively wide bezels in traditional products, making the e-paper tablet more visually integrated and more in line with the current development trend of e-paper tablets, significantly improving the user's reading and usage experience.

[0020] 2. Excellent bending resistance and longer service life: The double-sided F2 thin circuit structure and the metal mesh prepared by vacuum sputtering and photolithography greatly improve the flexibility of the touch sensor. The bending area can be bent stably, ensuring that the electrical properties of the touch sensor will not be damaged during the installation process. It is suitable for the portability requirements of electronic paper tablets and effectively avoids problems such as circuit detachment and open circuit caused by bending, thus significantly extending the product's service life.

[0021] 3. Excellent conductivity and high touch sensitivity: Metal Mesh is prepared using vacuum sputtering and photolithography processes. Compared with existing solutions such as ITO, chemical plating Mesh, and imprinted silver Mesh, its conductivity is improved by 200%-500%, with a sheet resistance of ≤5Ω / □. It has higher touch sensitivity and a response time of ≤50ms, which can meet the high-precision touch and handwriting requirements of e-paper notebooks. It solves the problems of touch delay and unsmooth handwriting caused by insufficient conductivity of existing touch sensors, thus improving the user experience.

[0022] 4. Excellent optical performance and strong display compatibility: The Metal Mesh grid lines are fully blackened, with a blackening coverage of ≥99% on the side etching surface. At the same time, the grid line width and period are optimized, the transmittance in the visible light band is ≥92%, and the grid line reflectivity is ≤10%. This completely avoids the problem of grid lines being visible or degrading the electronic paper display effect at different angles. It is perfectly adapted to the paper-like diffuse reflection display effect of electronic paper, improving display consistency and visual experience, which is different from existing solutions with incomplete blackening and visible grid lines.

[0023] 5. High bending reliability and more stable use: There are notches between adjacent bending areas to effectively disperse the stress at right angles, prevent problems such as wire breakage and air bubbles in the bonding, solve the problem of easy damage at right angles in traditional bending solutions, improve the stability and durability of the product, and reduce the product failure rate. Attached Figure Description

[0024] The accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort. Figure 1 This is a schematic diagram of the structure of the bending sheet area after bending in an embodiment of the present invention; Figure 2 These are the circuit patterns of the driving layer and sensing layer in the embodiments of the present invention; Figure 3 This is the driving layer circuit pattern in an embodiment of the present invention; Figure 4 This is the circuit pattern of the sensing layer in an embodiment of the present invention; Figure 5 This is a schematic diagram of the notch location in an embodiment of the present invention; Figure 6 This is a schematic diagram showing the location of the second bending section in an embodiment of the present invention; Figures 7 to 10 This is a schematic diagram of the notch structure in an embodiment of the present invention; Figure 11 It is the cross-sectional structure of the film after the preparation of the first blackening layer and copper film is completed; Figure 12 It is the cross-sectional structure of the membrane after the fabrication of the Metal Mesh touch circuit is completed; Figure 13 This is the cross-sectional structure of the membrane after the post-blackening treatment step is completed; Figure 14 This is a schematic diagram of the structure after the touch sensor and display screen are assembled. Detailed Implementation

[0025] This invention provides a touch sensor for a narrow-bezel electronic paper display device.

[0026] like Figures 1 to 4 As shown, the touch sensor of the narrow-bezel electronic paper display device includes a transparent substrate 1 and a touch circuit disposed on the transparent substrate 1. The transparent substrate 1 includes a display area 2 and at least one bent area 3. In this embodiment, there are two bent areas 2, but the bent areas can also be one, three, or four. The touch circuit includes a sensing electrode 4 and a driving electrode 14 disposed on the display area. The bent area 3 has a sensing circuit frame trace 5 electrically connected to the sensing electrode 4 and a driving circuit frame trace 23 electrically connected to the driving electrode 14. The bent area is located outside the display area 2, and the bent area is bent relative to the display area. Preferably, as shown... Figure 6 As shown, a second bending area 6 is connected to the edge of the bending area. The second bending area 6 has a border line and can be bent relative to the bending area. The bent area can be attached to the side of the electronic paper tablet. The second bending area, bent relative to the first bending area, can be bent again relative to the first bending area, thus attaching the second bending area to the other side or back of the electronic paper tablet. Figure 10As shown, in one embodiment, one side of the bending plate area 3 is provided with the second bending plate area 6, and the other side of the bending plate area 3 is provided with a clearance notch 22 to accommodate the bent second bending plate area 6, which makes it easier to arrange the circuit.

[0027] Preferably, the thickness of the transparent substrate is less than or equal to 23 μm, and the transparent substrate is one or more composites of polyethylene terephthalate, cyclic olefin polymers, cellulose triacetate, and polymethyl methacrylate. Preferably, the visible light transmittance of the transparent substrate is ≥92%, and the glass transition temperature is ≥90℃, which is suitable for the mass production process and optical display requirements of electronic paper tablets, while also possessing excellent flexibility and heat resistance to prevent substrate damage during bending and substrate deformation and yellowing at high temperatures.

[0028] The touch circuit is a double-sided F2 structure Metal Mesh. A sensing circuit layer 7 and a driving circuit layer 8 are respectively disposed on the upper and lower surfaces of the transparent substrate. The sensing electrodes and sensing circuit frame traces 5 are located on the sensing circuit layer 7, and the driving electrodes and driving circuit frame traces 23 are located on the driving circuit layer 8. Compared to the traditional FF structure, the overall thickness is reduced by more than 50%, making it easier to bend while maintaining touch sensitivity. This solves the shortcomings of the traditional FF structure, such as large thickness and difficulty in bending, and adapts to the multi-sided bending requirements of the frame traces.

[0029] The touch circuit employs a Metal Mesh structure. The mesh line width is 1-5µm, the mesh period is 100-1000µm, and the sheet resistance of the mesh lines is ≤5Ω / □. The mesh shape can be square, rhombus, hexagon, or random polygon. This design balances high conductivity and high optical transmittance, preventing the mesh lines from being visible from different viewing angles and ensuring compatibility with electronic paper displays. A rhombus shape is preferred to further enhance bending resistance. The random polygon refers to a simple polygon formed by randomly generated vertex sequences and their orderly connection.

[0030] like Figure 13 As shown, the grid lines of Metal Mesh are rendered entirely in black.

[0031] like Figure 5 As shown, a notch 9 is provided between adjacent bending sections, and the notch includes two side portions 10. Figures 6 to 10 As shown, the edge is one or more of a straight line segment, a curve, or a broken line segment, and the notch 9 is U-shaped, V-shaped, semi-circular, etc. When the edge is a straight line segment and the notch is V-shaped, the included angle between the two edges is preferably greater than or equal to 90°. Figure 6 As shown, the edge is a straight line segment, the angle between the two edges is 130°, and the notch 9 is V-shaped. Figure 7 As shown, the edge is a broken line segment, the angle between the two edges is 90°, and the notch 9 is V-shaped. Figure 8 As shown, the edge is curved, and the notch 9 is U-shaped. Figure 9 As shown, the edge is curved, and the notch 9 is semi-circular.

[0032] This invention also provides a manufacturing process for an electronic paper touch sensor, comprising the following steps performed sequentially: Step 1, the preparation of the first blackening layer 11 and the copper film, as follows: Figure 11 As shown, a first blackening layer 11 is sputtered on the upper and lower surfaces of a transparent substrate, and then a copper film is sputtered on the surfaces of the two blackening layers.

[0033] Step 2: Fabrication of the Metal Mesh Touch Circuit; Step 3: Post-blackening treatment. The surface and side-etched surfaces of the etched Metal Mesh grid lines are then subjected to post-blackening treatment. Step 4: Creating a notch. When two bent areas are adjacent, a notch needs to be created in the clearance area between them after the post-blackening process. When the display area is quadrilateral, adjacent display areas mean that bent areas are located on two adjacent sides of the quadrilateral. When two bent areas are adjacent, the wiring at the intersection of the two bent areas is designed to avoid obstacles, achieving clearance for the circuit pattern. A clearance area is formed between the two adjacent bent areas. A notch is created in the clearance area between the two bent areas using laser engraving or die-cutting to effectively disperse stress.

[0034] Step 5: Bending and shaping. According to design requirements, bend the bending area, controlling the bending angle between 90° and 180°, specifically 90°, 95°, 100°, 105°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, and 180°. The bending radius is 0.5-3mm, specifically 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, and 3mm. The bending rate is 5-10° / s, specifically 5° / s, 6° / s, 7° / s, 8° / s, 9° / s, or 10° / s. An optical adhesive with a refractive index of 1.45-1.55 is used for bonding and fixing. The refractive index of the optical adhesive can be 1.45, 1.50, or 1.55. After bonding, a hot-press curing treatment is performed at 80-100℃, specifically 80℃, 90℃, or 100℃. The hot-pressing pressure is 0.1-0.3MPa, specifically 0.1MPa, 0.2MPa, or 0.3MPa, and the hot-pressing time is 10-20min, specifically 10min, 15min, or 20min, to ensure structural stability after bending. In this embodiment, an optical adhesive with a refractive index of 1.45 is used for bonding and fixing. After bonding, a hot-press curing treatment is performed at 80℃, with a hot-pressing pressure of 0.1MPa and a hot-pressing time of 10min. The bending and shaping of the second bending section and the opening of the avoidance gap should follow the steps above.

[0035] In the steps of preparing the first blackening layer 11 and the copper film, the pretreated transparent substrate is fed into a vacuum sputtering apparatus, and the vacuum degree is controlled at... Specifically, it can be as follows

[0036] The temperature of the transparent substrate is controlled between 60℃ and 80℃, specifically 60℃, 70℃, and 80℃. The thickness of the first blackening layer 11 is 20-80nm, specifically 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, and 80nm. Then, copper films are sputtered onto the surfaces of the two first blackening layers 11, with a thickness of 200-700nm, specifically 200nm, 300nm, 400nm, 500nm, 600nm, and 700nm, forming a composite structure of "copper film-blackening layer-transparent substrate-blackening layer-copper film". The cross-sectional structure of the film after preparation is as follows: Figure 11 As shown in step three, during the post-blackening treatment of the etched Metal Mesh grid lines and side-etched surfaces, a second blackening layer 12 is prepared using a selenite-based blackening solution. The thickness of the second blackening layer is 10-100 nm, specifically 10 nm, 30 nm, 40 nm, 60 nm, 80 nm, or 100 nm. The blackening coverage of the side-etched surfaces is ≥99%. The cross-sectional structure of the film after preparation is shown in the figure. Figure 13 As shown.

[0037] In the fabrication of the Metal Mesh touch circuit, photolithography is used to fabricate a double-sided F2 structure Metal Mesh touch circuit: a photoresist is coated on the surface of the copper film 13, with a thickness of 1-3 μm, specifically 1 μm, 2 μm, or 3 μm. Ultraviolet exposure and development are employed, with exposure energy of 80-120 mJ / cm², specifically 80 mJ / cm², 90 mJ / cm², 100 mJ / cm², 110 mJ / cm², or 120 mJ / cm². The double-sided F2 structure Metal Mesh touch circuit pattern is transferred onto the photoresist, and the development time is 30-60 s, specifically 30 s, 40 s, 50 s, or 60 s. Then, an etching process is used to remove the copper film not protected by the photoresist and the first blackening layer 11. The etching temperature is 30-40℃, specifically 30℃, 40℃, 50℃, or 60℃, with etching precision controlled within ±0.5 μm, thus forming the touch circuit. The cross-sectional structure of the membrane after preparation is as follows Figure 12 As shown.

[0038] The etching solution is a mixture of ferric chloride and hydrochloric acid with a volume ratio of ferric chloride to hydrochloric acid of 5:1 to 3:1, specifically 5:1, 4:1, or 3:1.

[0039] Preferably, before preparing the first blackening layer and copper film, a substrate pretreatment step is required. An optical-grade transparent substrate with a thickness of 23 μm or less is selected, specifically 23 μm, 22 μm, or 21 μm. Surface pretreatment is performed in a vacuum sputtering chamber. Plasma activation treatment can be used to improve the surface dyne value. The dyne value is ≥38 mN / m, which enhances the adhesion between the substrate and the subsequent coating and reduces the risk of circuit detachment.

[0040] Preferably, after the notch is created, the insulation protective layer preparation and testing steps are performed sequentially. Only after these steps are completed can the bending and forming step proceed. In the insulation protective layer preparation step, a transparent insulating material is coated onto the surface of the touch circuit using coating or screen printing methods. The coating thickness is 1-5 μm; specifically, it can be 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm. It can be cured using UV-curable resin or polyimide. If UV-curable resin is used, the curing dosage is 100-150 mJ / cm², specifically 100 mJ / cm², 120 mJ / cm², 130 mJ / cm², or 150 mJ / cm². The curing time is 30-60 seconds, specifically 30 seconds, 50 seconds, or 60 seconds; if it is polyimide, the curing temperature is 150-200℃, specifically 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃, and the curing time is 30-60 minutes, specifically 30 minutes, 50 minutes, or 60 minutes, forming an insulating protective layer; the connection position between the touch sensor and the FPC is cut out, and no insulating layer is made at the corresponding position to ensure that the sensor and the FPC circuit are conductive.

[0041] The testing process involves comprehensive performance testing of the prepared touch sensor, with the following standards: Conductivity test: sheet resistance ≤ 5Ω / □; Bending resistance test: no circuit breakage and conductivity attenuation of no more than 10% after 100,000 bends at a bending radius of 3mm and a bending frequency of 10 times / minute; Optical performance test: visible light transmittance ≥ 92% and no visible grid lines; Touch sensitivity test: response time ≤ 50ms; Insulation performance test: breakdown voltage ≥ 10kV / mm; Fit test: no bubbles at the bonding area and fit ≥ 99%.

[0042] Figure 14 A schematic diagram of the assembled structure of the touch sensor 15 and the electronic paper EPD display screen 21 is shown, wherein the components are: transparent cover plate 16, upper OCA optical adhesive 17, touch sensor 15, transparent insulating protective layer 18, lower OCA optical adhesive 20, and electronic paper EPD display screen 21. Example

[0043] This invention provides a manufacturing process for an electronic paper touch sensor with adjacent bending areas, comprising the following steps performed sequentially: Step 1, Preparation of the first blackening layer and copper film: The first blackening layer 11 is sputtered on the upper and lower surfaces of the transparent substrate, and then copper film is sputtered on the two blackening layer surfaces.

[0044] Step 2: Fabrication of the Metal Mesh Touch Circuit; Step 3: Post-blackening treatment. The surface and side-etched surfaces of the etched Metal Mesh grid lines are then subjected to post-blackening treatment. Step 4: Creating a notch. When two bent areas are adjacent, a notch needs to be created in the clearance area between them after the post-blackening process. When the display area is quadrilateral, adjacent display areas mean that bent areas are located on two adjacent sides of the quadrilateral. When two bent areas are adjacent, the wiring at the intersection of the two bent areas is designed to avoid obstacles, achieving clearance for the circuit pattern. A clearance area is formed between the two adjacent bent areas. A notch is created in the clearance area between the two bent areas using laser engraving or die-cutting to effectively disperse stress.

[0045] Step 5, bending and forming step: According to the design requirements, the bending area is bent. In this embodiment, the bending angle is 90 degrees, the bending radius is 3mm, the bending speed is 10° / s, and optical adhesive with a refractive index of 1.55 is used for bonding and fixing. After bonding, hot pressing and curing treatment is performed at 100℃, the hot pressing pressure is 0.3MPa, and the hot pressing time is 20min.

[0046] In the steps of preparing the first blackening layer and copper film, the pretreated transparent substrate is fed into a vacuum sputtering apparatus, and the vacuum level is controlled at [value missing]. The transparent substrate temperature is controlled at 80℃, and the thickness of the first blackening layer 11 is 80nm. Then, copper films 13 with a thickness of 700nm are sputtered onto the surfaces of the two first blackening layers 11, forming a composite structure of "copper film-blackening layer-transparent substrate-blackening layer-copper film". In step three, when performing post-blackening treatment on the surface and side-etched surfaces of the etched Metal Mesh grid lines, a second blackening layer with a thickness of 100nm is prepared using a selenite-based blackening solution. The blackening coverage of the side-etched surface is 99.5%.

[0047] In the fabrication of the Metal Mesh touch circuit, photolithography is used to fabricate a double-sided F2 structure Metal Mesh touch circuit: a photoresist with a thickness of 3 μm is coated on the copper film surface. Ultraviolet exposure and development processes are used, with an exposure energy of 120 mJ / cm², to transfer the circuit pattern of the double-sided F2 structure onto the photoresist. The development time is 60 s. Then, an etching process is used to remove the copper film not protected by the photoresist and the first blackening layer. The etching temperature is 40℃, and the etching accuracy is controlled within ±0.5 μm to form the touch circuit.

[0048] The etching solution is a mixture of ferric chloride and hydrochloric acid, with a volume ratio of ferric chloride to hydrochloric acid of 3:1.

[0049] Before the preparation of the first blackening layer and copper film, a substrate pretreatment step is required. An optical-grade transparent substrate with a thickness of 23 μm is selected, and surface pretreatment is performed in a vacuum sputtering chamber. Plasma activation treatment is used to improve the surface dyne value to 39 mN / m, thereby enhancing the adhesion between the substrate and the subsequent coating and reducing the risk of circuit detachment.

[0050] Preferably, after the notch is created, the insulation protective layer preparation and testing steps are performed sequentially. Only after these steps are completed can the bending and forming step begin. In the insulation protective layer preparation step, a transparent insulating material is coated onto the surface of the touch circuit using coating or screen printing methods, with a coating thickness of 5µm. An ultraviolet-cured resin is used, with a curing dose of 150mJ / cm² and a curing time of 60s. The connection point between the touch sensor and the FPC is cut out, and no insulating layer is applied to the corresponding location to ensure conductivity between the sensor and the FPC circuit. The prepared touch sensors were randomly inspected. Conductivity testing showed a sheet resistance of ≤5Ω / □ (minimum 3.6Ω / □, maximum 4.7Ω / □). Bending resistance testing involved 100,000 bends at a 3mm radius and a frequency of 10 bends / minute; no wire breakage was observed, and conductivity attenuation was ≤10% (minimum 5.6%, maximum 8.2%). Visible light transmittance was ≥92% (minimum 93.1%, maximum 94.7%), with no visible grid lines. Touch sensitivity testing showed a response time ≤50ms (minimum 33ms, maximum 42ms). Insulation performance testing showed a breakdown voltage ≥10kV / mm (minimum 12kV / mm, maximum 15kV / mm). Fit testing showed no air bubbles at the bonding area, with a fit of ≥99% (minimum 99.2%, maximum 99.8%).

[0051] The product exhibits significantly superior performance compared to existing similar products in the following aspects: conductivity test: sheet resistance 6.1Ω / □; bending resistance test: conductivity decays by 12% after 100,000 bends with a bending radius of 3mm and a bending frequency of 10 bends / minute; optical performance test: visible light transmittance 90%; touch sensitivity test: response time 62ms; insulation performance test: breakdown voltage 9.2kV / mm; fit test: fit 98.3%. Example

[0052] This invention provides a manufacturing process for an electronic paper touch sensor with interleaved bent areas, comprising the following steps performed sequentially: Step 1: Preparation of the first blackening layer and copper film; The first blackening layer 11 is sputtered onto the upper and lower surfaces of the transparent substrate respectively. Then, copper films are sputtered onto the surfaces of the two blackening layers respectively.

[0053] Step 2: Fabrication of the Metal Mesh Touch Circuit.

[0054] Step 3: Post-blackening treatment. The surface and side-etched surfaces of the etched Metal Mesh grid lines are then subjected to post-blackening treatment. Step four, bending and forming: According to design requirements, the bending area is bent at a 100° angle with a bending radius of 0.5mm. The bending rate is 5° / s. Optical adhesive with a refractive index of 1.45 is used for bonding and fixing. After bonding, hot-press curing is performed at 80℃ with a pressure of 0.1MPa for 10 minutes to ensure structural stability after bending.

[0055] In the steps of preparing the first blackening layer and copper film, the pretreated transparent substrate is fed into a vacuum sputtering apparatus, and the vacuum level is controlled at [value missing]. The transparent substrate temperature is controlled at 60℃, and the thickness of the first blackening layer 11 is 20nm. Then, copper films 13 with a thickness of 200nm are sputtered onto the surfaces of the two first blackening layers, forming a composite structure of "copper film-blackening layer-transparent substrate-blackening layer-copper film". In step three, when performing post-blackening treatment on the surface of the etched Metal Mesh grid lines and the side-etched surface, a second blackening layer is prepared by using a selenite series blackening solution. The thickness of the second blackening layer 12 is 10nm. The blackening coverage of the side-etched surface is 99.3%.

[0056] In the fabrication of the Metal Mesh touch circuit, photolithography is used to fabricate a double-sided F2 structure Metal Mesh touch circuit: a photoresist with a thickness of 1 μm is coated on the copper film surface. Ultraviolet exposure and development processes are used, with an exposure energy of 80 mJ / cm², to transfer the circuit pattern of the double-sided F2 structure onto the photoresist. The development time is 30 s. Then, an etching process is used to remove the copper film not protected by the photoresist and the first blackening layer. The etching temperature is 30℃, and the etching accuracy is controlled within ±0.5 μm to form the touch circuit.

[0057] The etching solution is a mixture of ferric chloride and hydrochloric acid, with a volume ratio of ferric chloride to hydrochloric acid of 5:1.

[0058] Preferably, before preparing the first blackening layer and copper film, a substrate pretreatment step is required. An optical-grade transparent substrate with a thickness of 21 μm is selected, and surface pretreatment is performed in a vacuum sputtering chamber. Plasma activation treatment is used to improve the surface dyne value to 40 mN / m, thereby enhancing the adhesion between the substrate and the subsequent coating and reducing the risk of circuit detachment.

[0059] Preferably, after creating the notch, the insulation protective layer preparation and testing steps are performed sequentially. Only after these steps are completed can the bending and forming step proceed. In the insulation protective layer preparation step, a transparent insulating material with a thickness of 1µm is coated onto the surface of the touch circuit using coating or screen printing. Polyimide is then used for curing at 150°C for 30 minutes to form the insulation protective layer. The connection point between the touch sensor and the FPC is cut out, and no insulation layer is applied to the corresponding location to ensure conductivity between the sensor and the FPC circuit. The prepared touch sensors were randomly inspected. Conductivity tests showed a sheet resistance of ≤5Ω / □ (minimum 3.9Ω / □, maximum 4.8Ω / □). Bending resistance tests involved 100,000 bends at a 3mm radius and a frequency of 10 bends per minute; no wire breakage was observed, and conductivity attenuation ranged from 6.8% to 8.7%, with all attenuation values ​​less than or equal to 10%. Visible light transmittance ranged from 92.7% to 95.1%, with all transmittance ≥92%, and grid lines were not visible. Touch sensitivity response times ranged from 31ms to 39ms, with all response times ≤50ms. Insulation performance tests showed a breakdown voltage ranged from 11kV / mm to 13kV / mm, with all breakdown voltages ≥10kV / mm.

[0060] The following performance characteristics are significantly superior to those of existing similar products: conductivity test: sheet resistance 6.1Ω / □; bending resistance test: conductivity decays by 12% after 100,000 bends with a bending radius of 3mm and a bending frequency of 10 times / minute; optical performance test: visible light transmittance 90%; touch sensitivity test: response time 62ms; insulation performance test: breakdown voltage 9.2kV / mm. Example

[0061] This invention provides another manufacturing process for an electronic paper touch sensor with adjacent bending areas, comprising the following steps performed sequentially: Step 1, Preparation of the first blackening layer and copper film: The first blackening layer 11 is sputtered on the upper and lower surfaces of the transparent substrate, and then copper film is sputtered on the two blackening layer surfaces.

[0062] Step 2: Fabrication of the Metal Mesh Touch Circuit; Step 3: Post-blackening treatment. The surface and side-etched surfaces of the etched Metal Mesh grid lines are then subjected to post-blackening treatment. Step 4: Creating a notch. When two bent areas are adjacent, a notch needs to be created in the clearance area between them after the post-blackening process. When the display area is quadrilateral, adjacent display areas mean that bent areas are located on two adjacent sides of the quadrilateral. When two bent areas are adjacent, the wiring at the intersection of the two bent areas is designed to avoid obstacles, achieving clearance for the circuit pattern. A clearance area is formed between the two adjacent bent areas. A notch is created in the clearance area between the two bent areas using laser engraving or die-cutting to effectively disperse stress.

[0063] Step 5, bending and forming step: According to the design requirements, the bending area is bent. In this embodiment, the bending angle is 180 degrees, the bending radius is 2mm, the bending speed is 7° / s, and optical adhesive with a refractive index of 1.5 is used for bonding and fixing. After bonding, hot pressing and curing treatment is performed at 90℃, the hot pressing pressure is 0.2MPa, and the hot pressing time is 15min.

[0064] In the steps of preparing the first blackening layer and copper film, the pretreated transparent substrate is fed into a vacuum sputtering apparatus, and the vacuum level is controlled at [value missing]. The transparent substrate temperature is controlled at 70℃, and the thickness of the first blackening layer 11 is 50nm. Then, copper films 13 with a thickness of 300nm are sputtered onto the surfaces of the two first blackening layers 11, forming a composite structure of "copper film-blackening layer-transparent substrate-blackening layer-copper film". In step three, when performing post-blackening treatment on the surface of the etched Metal Mesh grid lines and the side-etched surface, a second blackening layer with a thickness of 80nm is prepared by using a selenite series blackening solution. The blackening coverage of the side-etched surface is 99.8%.

[0065] In the fabrication of the Metal Mesh touch circuit, photolithography is used to fabricate a double-sided F2 structure Metal Mesh touch circuit: a photoresist with a thickness of 2 μm is coated on the copper film surface. Ultraviolet exposure and development processes are used, with an exposure energy of 110 mJ / cm², to transfer the circuit pattern of the double-sided F2 structure onto the photoresist. The development time is 50 s. Then, an etching process is used to remove the copper film not protected by the photoresist and the first blackening layer. The etching temperature is 50℃, and the etching accuracy is controlled within ±0.5 μm to form the touch circuit.

[0066] The etching solution is a mixture of ferric chloride and hydrochloric acid, with a volume ratio of ferric chloride to hydrochloric acid of 4:1.

[0067] Before preparing the first blackening layer and copper film, a substrate pretreatment step is required. A 21µm thick optical-grade transparent substrate is selected and surface pretreatment is performed in a vacuum sputtering chamber. Plasma activation treatment is used to improve the surface dyne value to 40mN / m, thereby enhancing the adhesion between the substrate and the subsequent coating and reducing the risk of circuit detachment.

[0068] Preferably, after the notch is created, the insulation protective layer preparation and testing steps are performed sequentially. Only after these steps are completed can the bending and forming step proceed. In the insulation protective layer preparation step, a transparent insulating material is coated onto the surface of the touch circuit using coating or screen printing methods, with a coating thickness of 3µm. An ultraviolet-cured resin is used, with a curing dose of 120mJ / cm² and a curing time of 50s. The connection position between the touch sensor and the FPC is cut out, and no insulating layer is applied to the corresponding position to ensure conductivity between the sensor and the FPC circuit. The prepared touch sensors were randomly sampled and tested. Conductivity testing showed a sheet resistance of ≤5Ω / □ (minimum 3.1Ω / □, maximum 4.2Ω / □). Bending resistance testing involved 100,000 bends at a 3mm radius and a frequency of 10 bends / minute; no wire breakage was observed, and conductivity attenuation was ≤10% (minimum 5.1%, maximum 7.2%). Visible light transmittance was ≥92% (minimum 94.3%, maximum 96.4%), with no visible grid lines. Touch sensitivity testing showed a response time ≤50ms (minimum 27ms, maximum 41ms). Insulation performance testing showed a breakdown voltage ≥10kV / mm (minimum 11kV / mm, maximum 13kV / mm). Adhesion testing showed no air bubbles at the bonding area, with an adhesion ≥99% (minimum 99.1%, maximum 99.5%).

[0069] The product exhibits significantly superior performance compared to existing similar products in the following aspects: conductivity test: sheet resistance 6.1Ω / □; bending resistance test: conductivity decays by 12% after 100,000 bends with a bending radius of 3mm and a bending frequency of 10 bends / minute; optical performance test: visible light transmittance 90%; touch sensitivity test: response time 62ms; insulation performance test: breakdown voltage 9.2kV / mm; fit test: fit 98.3%.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A touch sensor for a narrow-bezel electronic paper display device, comprising a transparent substrate and a touch circuit disposed on the transparent substrate, characterized in that, The transparent substrate includes a display area and at least one bent area, the bent area being located outside the display area and bent relative to the display area; the touch circuit is arranged in a Metal Mesh structure.

2. The touch sensor for the narrow-bezel electronic paper display device as described in claim 1, characterized in that, The edge of the bending section is connected to a second bending section, which is bent relative to the bending section.

3. The touch sensor for the narrow-bezel electronic paper display device as described in claim 1, characterized in that, The touch circuit is a double-sided F2 structure Metal Mesh.

4. The touch sensor for the narrow-bezel electronic paper display device as described in claim 1, characterized in that, Metal Mesh has a mesh line width of 1-5um, a mesh period of 100-1000um, and a mesh line sheet resistance of ≤5Ω / □; the mesh shape of Metal Mesh can be square, rhombus, hexagon or random polygon.

5. The touch sensor for the narrow-bezel electronic paper display device as described in claim 1, characterized in that, The mesh lines of Metal Mesh are rendered entirely in black.

6. The touch sensor for the narrow-bezel electronic paper display device as described in claim 1, characterized in that, A gap is provided between adjacent bending areas, the gap including two sides, the sides being one or a combination of two or more of the following: straight line segment, curve, and broken line segment.

7. A manufacturing process for a touch sensor in a narrow-bezel electronic paper display device, characterized in that, Includes the following steps: The steps for preparing the first blackening layer and copper film are as follows: the first blackening layer is sputtered onto the upper and lower surfaces of the transparent substrate respectively; and then copper film is sputtered onto the surfaces of the two blackening layers respectively. Steps for fabricating Metal Mesh touch circuits; Post-blackening treatment step: Perform post-blackening treatment on the surface and side-etched surfaces of the etched Metal Mesh grid lines; Bending and forming steps: Bending the bending area.

8. The manufacturing process for the touch sensor of the narrow-bezel electronic paper display device as described in claim 7, characterized in that, In the steps of preparing the first blackening layer and copper film, the pretreated transparent substrate is fed into a vacuum sputtering equipment, and the vacuum degree is controlled at - The temperature of the transparent substrate is controlled at 60℃-80℃, and the thickness of the first blackening layer is 20-80nm. Then, copper films are sputtered on the surfaces of the two first blackening layers, with a thickness of 200-700nm. In step three, when performing post-blackening treatment on the surface of the etched Metal Mesh grid lines and the side-etched surface, a second blackening layer is prepared by using a selenite series blackening solution, with a thickness of 10-100nm.

9. The manufacturing process for the touch sensor of the narrow-bezel electronic paper display device as described in claim 7, characterized in that, In the process of fabricating the Metal Mesh touch circuit, photolithography is used to fabricate a double-sided F2 structure Metal Mesh touch circuit. Photoresist is coated on the copper film surface. Ultraviolet exposure and development process is used to transfer the double-sided F2 structure Metal Mesh touch circuit pattern onto the photoresist. Then, etching process is used to remove the copper film and the first blackening layer that are not protected by the photoresist, forming the driving circuit layer, the sensing circuit layer and the frame trace.

10. The manufacturing process for the touch sensor of the narrow-bezel electronic paper display device as described in claim 7, characterized in that, When two bending areas are adjacent, a gap is created in the clearance area between the adjacent bending areas after the post-blackening process.

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