Electrode structure and device including the same

Abstract

To provide an electrode structure in which change rate / ratio of a resistance value of a bending portion is controlled, and to provide a device including the electrode structure.SOLUTION: An electrode structure 10 includes a substrate 11 and a silver nanowire electrode 12 disposed on the substrate, and can be changed from a developed state to a bent state with a bending radius RR of about 2 to 4 mm, and includes a bent region BZ and two non-bent regions FZ respectively adjacent to the bent region in the bent state. In the silver nanowire electrode, change rate of a resistance value between the bent state and the developed state in an electrode portion of the silver nanowire electrode in the bent region is less than 10%.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electrode structure and a device including the electrode structure, and more particularly to an electrode structure in which the rate / ratio of change in resistance value of a bent portion is controlled, and a device including the electrode structure. [Background technology]

[0002] In recent years, flexible applications are becoming the standard specification of electronic products. Compared with fixed-shape displays, flexible displays can be folded, rolled or bent to change the shape of the flexible display into a squashed state, which makes it easier to carry and more convenient for users. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Taiwan Patent Application Publication No. 2022 / 21400 [Patent Document 2] U.S. Pat. No. 1,134,3911 Summary of the Invention [Problem to be solved by the invention]

[0004] Dynamic bending tests are commonly employed to evaluate the reliability of flexible devices in customer use. For example, Taiwan Patent Application Publication No. 2022 / 21400 (hereinafter referred to as TW400) discloses a touch panel including a silver nanowire (SNW) electrode and a peripheral metal trace, and performs a dynamic bending test (e.g., 200K times) on the peripheral metal trace at a specific radius of curvature to measure the change in the overall resistance value of the peripheral metal trace. However, in TW400, the resistance change of the SNW electrode in the bending region is not measured. Furthermore, U.S. Patent No. 11,343,911 (hereinafter referred to as US911) discloses a fixed bending device in which a transparent conductive electrode is first bent and then fixed in the bent state. US911 discloses the change in the resistance value of the transparent conductive electrode before and after bending. However, in US911, the resistance value is measured over the entire length of the electrode. For example, as shown in FIG. 6 of US911, a measuring contact is placed at both ends of the entire length of the electrode, which is 5 cm, to measure the change in the resistance value of the entire length of the electrode before and after bending. In other words, no specific measurements have been performed on the change in electrode resistance in the bending region, because US911 is a fixed bending structure and not a flexible device, and the user cannot switch the fixed bending structure between the folded and unfolded states, so the difference (or change) in the resistance of the bending region in both use states is not relevant for US911.

[0005] Flexible devices are broadly divided into outwardly folding and inwardly folding types. Outwardly folding types allow the user to see and touch the screen in the folded state. Whether the system can perform touch sensing correctly when the user tries to touch the screen in the bending region has a significant impact on the user's experience. Meanwhile, the user may switch the device from the unfolded state to the folded state and simultaneously perform screen touch (handwriting, gesture sliding, etc.). If the touch is not sensed correctly or at an incorrect timing when the finger slides into the folding region, it will be a bad experience. As mentioned above, the touch performance of the folding region is very important to the user experience, and whether the resistance value of the touch electrode in the part within the folding region can be prevented from generating an obviously excessive resistance change rate due to folding plays an important role. Although US911 is not a flexible device, referring to the resistance data disclosed in US911, it can be calculated that the resistance change rate of US911 in the bending region exceeds 100%. In other words, in the conventional technology, the rate of change of the resistance value in the curved region is high, which causes problems such as delay and poor sensing when touched by a user.

[0006] Therefore, the present disclosure has been developed in consideration of the above shortcomings. The objective of the present disclosure is to provide an electrode structure in which the rate of change in resistance at a bent portion in a bent state is less than 10%, and therefore the electrode structure has an excellent balance between electrical conductivity and optical properties. [Means for solving the problem]

[0007] The electrode structure of the present disclosure is an electrode structure including a substrate and a silver nanowire electrode disposed on the substrate, wherein the electrode structure can be changed from an unfolded state to a bent state having a bending radius of approximately 2 to 4 mm, and wherein, in the bent state, the electrode structure includes a bent region and a first non-bent region and a second non-bent region each adjacent to the bent region, and the silver nanowire electrode has a resistance change rate between the bent state and the unfolded state of less than 10% in the electrode portion of the silver nanowire electrode within the bent region.

[0008] Preferably, according to the electrode structure of the present disclosure, the silver nanowire electrode includes silver nanowires and a resin.

[0009] Preferably, according to the electrode structure of the present disclosure, the electrode structure changes from an unfolded state to a bent state with a bending radius of approximately 3 mm, and the silver nanowire electrode has a resistance value change rate between the bent state and the unfolded state at the electrode portion of the silver nanowire electrode in the bending region of approximately 2.8% to 7.2%, or the electrode structure changes from an unfolded state to a bent state with a bending radius of approximately 2 to 4 mm, and the silver nanowire electrode has a resistance value change rate between the bent state and the unfolded state at the electrode portion of the silver nanowire electrode in the bending region of approximately 2.4% to 7.2%.

[0010] Preferably, according to the electrode structure of the present disclosure, the electrode structure changes from an unfolded state to a bent state with a bending radius of approximately 3 mm, and the silver nanowire electrode has a resistance value change rate between the bent state and the unfolded state at the electrode portion of the silver nanowire electrode in the bending region of approximately 2% to 8%, or the electrode structure changes from an unfolded state to a bent state with a bending radius of approximately 2 to 4 mm, and the silver nanowire electrode has a resistance value change rate between the bent state and the unfolded state at the electrode portion of the silver nanowire electrode in the bending region of approximately 2% to 8%.

[0011] Preferably, according to the electrode structure of the present disclosure, the silver nanowire electrode includes a first electrode and a second electrode, the first electrode and the second electrode are disposed on different sides of the substrate, the first electrode has a first rate of change of resistance between the bent state and the unfolded state, and the second electrode has a second rate of change of resistance between the bent state and the unfolded state, and the first rate of change of resistance is different from the second rate of change of resistance.

[0012] Preferably, according to the electrode structure of the present disclosure, the silver nanowire electrode includes a first electrode and a second electrode, the first electrode and the second electrode are disposed on different sides of the substrate, the second electrode is closer to the bending axis than the first electrode, the first electrode has a first rate of change of resistance between the bent state and the unfolded state, and the second electrode has a second rate of change of resistance between the bent state and the unfolded state, the second rate of change of resistance being greater than the first rate of change of resistance.

[0013] Preferably, according to the electrode structure of the present disclosure, the silver nanowire electrode includes a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, the second electrode is closer to the bending axis than the first electrode, the first electrode has a first rate of change in resistance between the bent state with a bending radius of approximately 3 mm and the unfolded state, the second electrode has a second rate of change in resistance between the bent state with a bending radius of approximately 3 mm and the unfolded state, the second rate of change in resistance is approximately 1.1 to 2.5 times or 1.2 to 1.8 times the first rate of change in resistance, and both the second rate of change in resistance and the first rate of change in resistance are less than 10%.

[0014] Preferably, according to the electrode structure of the present disclosure, the silver nanowire electrode is made from a silver nanowire paste having a sheet resistance of 15 to 100 ops and has a thickness of less than 50 nm, or the silver nanowire electrode is made from a silver nanowire paste having a sheet resistance of 30 to 70 ops and has a thickness of less than 50 nm.

[0015] The present disclosure further provides a device, such as a display device, including the above electrode structure, which is a flexible display device including a display element, an optical adhesive layer disposed between the display element and the electrode structure, the display element displaying an image corresponding to the bent region, the first non-bent region, and the second non-bent region.

[0016] Preferably, according to the device of the present disclosure, the optical adhesive layer has an average gradient of storage modulus in the temperature range of -30°C to 60°C within the range of -4.0 kPa / °C to -1.5 kPa / °C.

[0017] As mentioned above, the electrode structure provided by the present disclosure allows users to obtain a good touch experience when operating in a bent state, and the electrical and optical properties (such as transmittance and haze) of the electrode structure provided by the present disclosure in a bent state are all within the product specifications.

[0018] In order to help those skilled in the art understand the objectives, features and advantages of the present disclosure, the present disclosure is described in detail by providing the following specific embodiments and accompanying drawings. [Brief description of the drawings]

[0019] The present disclosure will become apparent to those skilled in the art from the following detailed description of the preferred embodiments thereof, when read in conjunction with the accompanying drawings.

[0020] [Figure 1] 1 is a schematic diagram illustrating an electrode structure according to an embodiment of the present disclosure.

[0021] [Diagram 2] 2 is a cross-sectional view showing the electrode structure of FIG. 1 in a bent state.

[0022] [Diagram 3] FIG. 1 is a perspective view of a touch display device according to the present disclosure.

[0023] [Figure 4] FIG. 4 is a perspective view of the touch display device of FIG. 3 in a bent state;

[0024] [Diagram 5] 1 is a schematic diagram showing a pattern of an electrode structure according to the present disclosure.

[0025] [Figure 6]11 is a cross-sectional view showing an electrode structure according to another embodiment of the present disclosure in a bent state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The advantages, features, and methods of achieving the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. However, it should be noted that the present disclosure is not limited to the following exemplary embodiments, and can be implemented in various forms.

[0027] The terms used herein are used only to describe particular embodiments and are not intended to limit the present disclosure. As used herein, the singular form "a," "an," or "the" includes the plural form unless otherwise specified.

[0028] In addition, it should be understood that spatial terms such as "below," "below," "lower," "over," "higher," "above," "left side," "right side," "side," and the like may be used herein to describe the relationship of an element to other elements as depicted in the drawings, depending on the spatial relationship within the drawings. The spatial terms herein may include different orientations of an apparatus / device / element during use, operation, and / or manufacture in addition to the orientation depicted in the drawings. For example, an element described as "below" another element or feature would be correspondingly positioned "above" the other element or feature if the apparatus / device / element in the drawings were inverted. Thus, the term "below" as described herein may include both an orientation of above and below, depending on the spatial relationship of the apparatus / device / element. In addition, the apparatus / device / element may be otherwise oriented (e.g., rotated 45°, 90°, or in other directions). Thus, the spatial relative terms used herein should be interpreted accordingly. In addition, unless otherwise indicated, values ​​such as thickness, width, wire diameter, wire length, and the like, as used herein, are not fixed values ​​and may be considered approximate values. That is, it includes a margin of error or range as expressed by "about," "approximately," or "substantially." It will be understood by those skilled in the art that values ​​such as thickness, width, wire diameter, and wire length mentioned herein may include manufacturing tolerances, measurement errors, etc. The error or range of the values ​​mentioned herein may be ±20%, ±10%, or ±5%.

[0029] It will also be understood that, although terms such as "first" and "second" may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish between the respective elements. Thus, a first element referred to in some embodiments may be referred to as a second element in other embodiments without departing from the teachings of the present disclosure. In this specification, the same reference numerals refer to the same elements.

[0030] Please refer to FIG. 1 and FIG. 2. Here, FIG. 1 is a schematic diagram showing an electrode structure according to the present disclosure, which is an electrode structure for inductive touch. FIG. 2 is a cross-sectional view showing the electrode structure of FIG. 1 in a bent state. Referring to FIG. 1, the electrode structure 10 includes an electrode 12 and a substrate 11 that can be used to support the electrode 12. In one embodiment, the electrode structure 10 can be combined with a transparent cover plate, a display module, an optical film, an optical adhesive, and the like (not shown in FIG. 1) to form a touch display device 100. Here, the touch display device 100 can be a bendable, foldable, or other flexible display device (flexible display) for similar applications, as shown in FIG. 3 and FIG. 4.

[0031] In this embodiment, the touch display device 100 includes a bending region BZ, but the present disclosure is not limited thereto. According to another embodiment of the present disclosure, the touch display device 100 can include multiple folding regions. The touch display device 100 can include a display region DA and a peripheral region PA located outside the display region DA, but the electrode structure 10 of this embodiment of the present disclosure substantially corresponds to the display region DA, which makes it easy for the user to see the display screen and perform the touch operation.

[0032] In Fig. 1 and Fig. 2, only the electrode structure is shown for simplicity. Referring to Fig. 2, the electrode structure 10 in this embodiment of the present disclosure includes a bending region BZ. That is, the electrode 12 and the substrate 11 can be bent and folded back within the bending region BZ. As shown in Fig. 2, the electrode structure 10 can be folded along an axis FX1 extending in a predetermined direction, but in this embodiment of the present disclosure, the bending radius RR is defined as the distance from the vertical projection position of the axis FX1 to the lower surface of the substrate 11. Here, this folded state can be called a "folded state" or a "bent state". Fig. 1 shows the electrode structure 10 unfolded. That is, the unbent state can be called an "unfolded state", an "unfolded state", or an "unbent state". In addition, Fig. 1 shows that the electrode structure 10 includes one bending region BZ, but the present disclosure is not limited thereto. That is, the electrode structure 10 can include multiple bending regions BZ. The electrode structure 10 of this embodiment of the present disclosure can be defined into multiple regions according to the operation mode of the electronic product, for example, the electrode structure 10 can include at least one of a bending region BZ or a non-bending region FZ. As shown in FIG. 1, the bending region BZ can be set between two non-bending regions FZ.

[0033] In other embodiments, the touch display device can include a bending region BZ and a non-bending region FZ. The electrode structure 10 of the present disclosure can be combined with a transparent cover plate, a display module, an optical film, an optical adhesive, etc. (not shown in FIG. 1) to form a touch display device. Here, the touch display device can be a rollable touch display device. When the device is rolled, the entire display device forms one bending region BZ.

[0034] In some embodiments, the substrate 11 is not particularly limited, but may be a glass substrate (such as a bendable ultra-thin glass substrate), a polyethylene terephthalate (PET) substrate, a cyclic olefin polymer (COP) substrate, a transparent polyimide (CPI) substrate, a polyethylene naphthalate (PEN) substrate, a polycarbonate (PC) substrate, a polyether sulfide (PES) substrate, or the like. In addition, the substrate 11 may have a function of holding an electrode, and may also provide an optical function as required. For example, the substrate 11 may be a retardation film (specifically, a 1 / 2 wavelength retardation film or a 1 / 4 wavelength retardation film), a compensation film, a polarizing film, an anti-glare film, an anti-reflection film, or a combination thereof, or other functional films such as a protective film, an anti-scratch film, an anti-fouling film, or a combination thereof, or a composite film having multiple functions as described above.

[0035] Specifically, with reference to FIG. 1 , electrode 12 is disposed on substrate 11. In some embodiments, electrode 12 comprises a touch electrode layer disposed on substrate 11. According to some embodiments, the touch electrode layer can be formed from a transparent conductive material, including a material selected from a metal oxide, such as indium tin oxide (ITO); or a metal mesh, a silver nanowire (SNW), a carbon nanotube (CNT), graphene; or a conductive polymer, such as poly(3,4-ethylenedioxythiophene (PEDOT). In particular, the touch electrode layer can be formed from one or more of these materials.

[0036] In particular, in one embodiment, the electrode 12 is made from silver nanowires, and the method can be a method of directly or indirectly coating a dispersion / ink containing silver nanowires onto the substrate 11. For example, the silver nanowires are mixed in a solvent, such as water, alcohol, ketone, ether, hydrocarbon, or aromatic solvent (benzene, toluene, xylene, etc.), to form a coating material / paste / ink. The coating material / paste / ink can also include additives, surfactants, or binders, such as carboxymethylcellulose (CMC), 2-hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC), sulfonates, sulfates, disulfonates, sulfosuccinates, phosphates, or fluorine-containing surfactants.

[0037] More specifically, the phrase "metal nanowire" as used herein is a generic term referring to a collection of metal wires containing multiple elemental metals, metal alloys, or metal compounds (including metal oxides), and the number of metal nanowires contained therein does not affect the scope of the present disclosure. In addition, the size of at least one cross section (i.e., cross-sectional diameter) of one metal nanowire is less than about 500 nm, preferably less than about 100 nm, and more preferably less than about 50 nm. Metal nanostructures referred to as "wires" in the present disclosure primarily have high aspect ratios, for example, approximately 10 to 100,000. More specifically, the aspect ratio of metal nanowires (ratio of wire length to cross-sectional diameter) can be greater than about 10, preferably greater than about 50, and more preferably greater than about 100. Metal nanowires can be any metal, including, but not limited to, silver, gold, copper, nickel, or gold-plated silver. Other terms such as silk, fiber, tube, etc., which also have the above sizes and high aspect ratios, are also within the scope of the present disclosure. Considering that the parameters of the silver nanowires contained in the dispersion used for coating are not completely identical, for example, silver nanowires produced in different production batches with the same specifications may have different average diameters (wire diameters), standard deviations of diameters, maximum / minimum diameters, diameter distributions, etc., or may have different average wire lengths, standard deviations of wire lengths, maximum / minimum wire lengths, wire length distributions, etc. For the distribution of metal nanowires, reference may be made to US Patent Application Publication No. 2011 / 0174190, which is incorporated into the entirety of this embodiment of the present disclosure. Therefore, in this embodiment of the present disclosure, in order to avoid that electrodes made from silver nanowire pastes with the same specifications have different resistance value changes in the bending region, the difference in the resistance value changes of the electrodes in the bending region should be limited to approximately less than 15%, less than 12%, less than 10%, or less than 8%, depending on the standards of mass production and the acceptance standards of the products.

[0038] In a preferred embodiment, the shape of the nanostructures is anisotropic (i.e., aspect ratio ≠ 1). Anisotropic nanostructures typically have a major axis along their length. Exemplary anisotropic nanostructures can include nanowires, i.e., solid nanowire structures with an aspect ratio (ratio of wire length to wire diameter) of at least 10, more typically at least 50. In addition, a group of nanowires with a particular specification (e.g., a synthesized and purified product, or a coating material / paste formed by mixing with a solvent, etc.) does not have a single size, but includes nanostructures within a certain size range (wire length, wire diameter, etc.). Thus, the specifications of a thin film formed by such a group of nanowires (optical properties, electrical properties, flexible properties after stress, etc.) depend on the common effects of the entire group of nanowires.

[0039] After coating is complete, a curing process forms a silver nanowire layer that can then be used to form the electrode 12 by patterning methods known in the art (e.g., photolithography using photoresist and etching using laser or etchant, etc.).

[0040] Preferably, in one embodiment, a polymer layer can be further disposed to cover the silver nanowire layer, so that the polymer layer can be called an overcoat (OC). In one embodiment, a suitable polymer is coated on the silver nanowire layer, and the polymer having a flowable state / flowability can infiltrate between the silver nanowires as a filler, so that the polymer layer can also be called a matrix layer, while the silver nanowires can be embedded in the polymer, thereby forming a silver wire / resin composite structure after the polymer is cured. That is, in this process, a polymer layer is added on the silver nanowire layer by coating the polymer, while the silver nanowires can be embedded in the polymer layer to form a composite structure. In some embodiments of the present disclosure, the polymer layer is formed of an insulating material. For example, the material of the polymer layer can be a non-conductive resin or other organic material, such as polyacrylate, epoxy resin, polyurethane, polysilane, silicone, poly(silicon-acrylic acid), polyethylene (PE), polypropylene (PP), polyvinyl butyral (PVB), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), etc. In some embodiments of the present disclosure, the polymer layer can be formed by a method such as spin coating, spray coating, printing, etc. In some embodiments of the present disclosure, the polymer layer has a thickness of approximately 20 nm to 10 nm, 50 nm to 200 nm, or 30 nm to 100 nm. For example, the thickness of the polymer layer is approximately 90 nm or 100 nm. For the above specific method, for example, U.S. Patent Application Publication No. 2019 / 0227650 and Chinese Patent Application Publication No. 101292362 can be referenced, which are incorporated herein in their entirety. Both the silver nanowire paste and the polymer coating material are available from Cambrios. Unless otherwise specified, the silver nanowire electrode referred to herein is a conductive layer of a silver wire / resin composite structure. In some embodiments, the silver nanowire electrode having a sheet resistance of 30 ops (Ω / □) can have a thickness of less than 50 nm, or a thickness of 10 nm to 50 nm, 20 nm to 40 nm, or 40 nm to 50 nm.Under this sheet resistance, when the thickness of the silver nanowire electrode is excessive (e.g., greater than 50 nm), the optical properties (e.g., yellowness index b. * It may be difficult to meet the requirement for the thickness (value), and the contact impedance between the silver nanowire electrode and the material layer disposed thereafter (e.g., the lead wiring in the surrounding area made of a metal material) may become high. Also, if the thickness of the silver nanowire electrode is too small (e.g., less than 10 nm), the anti-ultraviolet performance of the silver nanowire electrode may be insufficient.

[0041] Specifically, according to some embodiments, the electrode structure 10 may further include an isolation layer or a protective layer. The isolation layer is disposed on the silver nanowire layer or the silver nanowire / resin composite structure layer. In the present disclosure, the term "isolation" includes both electrical isolation and physical isolation aspects. The isolation layer is a single layer or a multi-layer stack of inorganic mounting materials, or a stack of inorganic and organic mounting materials. The inorganic mounting materials used are not particularly limited, but may be, for example, silicon nitride (SiN x ), silicon oxide (SiO x ), silicon oxynitride (SiON x ), aluminum oxide (AlO x ), or titanium dioxide (TiO x ).

[0042] The specific process of the electrode structure according to the first embodiment of the present disclosure is as follows:

[0043] S1: Provide a substrate 11. This substrate is a 50 μm-thick PET substrate (product number: U483) manufactured by Toray Industries, Inc.

[0044] S2: A transparent conductive film is placed. A silver nanowire paste (product number: G6; sheet resistance: 30 ops (Ω / □); aspect ratio of nanowires: approximately 450 to 550) and a polymer coating material (product number: OCHE) manufactured by Cambrios are sequentially formed on the substrate 11 by roll-to-roll coating (specifically, slot die coating), and then cured to form a silver nanowire layer with a thickness of approximately 30 nm.

[0045] S3: Form touch electrode. The silver nanowire layer is laser etched into an electrode with a specific pattern (e.g., multiple axial touch electrodes 121 as shown in FIG. 5) to form the electrode structure 10 of this embodiment of the present disclosure. In addition, the cross section ab of the electrode in the bending region BZ is identified (specifically, point a is substantially located at the boundary / interface between the bending region BZ and the left non-bending region FZ; point b is substantially located at the boundary / interface between the bending region BZ and the right non-bending region FZ in FIG. 5), points c and d are the two ends of the total length of the axial touch electrode 121, the length of the cross section cd is about 10 mm, the length of the cross section ab is about 1 mm, and the width of each axial touch electrode 121 is about 10 μm.

[0046] S4: Measure the change in resistance (line resistance) at cross section ab of touch electrode 121 in the bent state. First, contacts are placed at points a and b of the touch electrode. For example, conductive silver paste is placed at points a and b. Then, a probe of a resistance measuring device is connected to the hardened conductive silver paste, and the resistance at cross section ab can be measured. This allows the resistances at cross sections ab and cd to be measured in a bent state (wherein electrode structure 10 of this embodiment of the present disclosure is folded back by 180° under a bending radius of 3 mm, as shown in FIG. 2) and in a non-bent state.

[0047] The specific process of the electrode structure according to the second embodiment of the present disclosure is similar to that of the first embodiment using the same specification of silver nanowire ink, except that the silver nanowire ink is manufactured in a different batch from the silver nanowire ink used in the first embodiment of the present disclosure.

[0048] The specific process of the electrode structure according to the third embodiment of the present disclosure is similar to that of the first embodiment, except that a silver nanowire paste with different product specifications is used. In this embodiment, a silver nanowire paste with product number G6 and sheet resistance of 70 ops manufactured by Cambrios is used. The thickness of the cured silver nanowire layer is approximately 40 to 50 nm.

[0049] The specific process of the electrode structure according to the fourth embodiment of the present disclosure is similar to that of the third embodiment, except that the bending condition is changed to folding backwards by 180° under the condition of a bending radius of 2 mm.

[0050] The specific process of the electrode structure according to the fifth embodiment of the present disclosure is similar to that of the third embodiment, except that the bending condition is changed to folding backwards by 180° under the condition of a bending radius of 4 mm.

[0051] The specific process of the electrode structure according to the sixth embodiment of the present disclosure is similar to that of the first embodiment, except that the substrate 11 is replaced with a 125 μm-thick PET substrate (product model number: U483) manufactured by Toray Industries, Inc.

[0052] The specific process of the electrode structure according to the seventh embodiment of the present disclosure is similar to that of the first embodiment, except that the substrate 11 is replaced with a 125 μm thick PET substrate (product model number: U483) manufactured by Toray Industries, Inc., and a silver nanowire paste with different product specifications is used. In this embodiment, a silver nanowire paste with product model number G5 manufactured by Cambrios, Inc., having a sheet resistance of 30 ops and an aspect ratio of the silver nanowires of approximately 400 to 750, is used.

[0053] According to this embodiment of the present disclosure, because of the computing element (such as a touch chip), the resistance value of the touch electrode changes at the cross section ab of the bending region BZ, so that the excessive change in the resistance value will cause a delay in signal transmission, leading to a decrease in the touch transmission speed or inaccurate touch sensing. In one embodiment, when the touch electrode is applied to an electronic product that can be folded outward (i.e., in the folded state, the user can see and touch the display screen), if the change in the resistance value of the touch electrode occurring at the cross section ab of the bending region BZ exceeds the specification of the computing element (e.g., more than 15%, more than 12%, or more than 10%), the above problem will occur. Therefore, this embodiment of the present disclosure can meet the specification of the computing element to meet the specification of the electronic product that can be folded outward (e.g., the change in the resistance value of the touch electrode at the cross section ab of the bending region BZ can be less than 15%, less than 12%, less than 10%, and less than 8%). The following Table 1 shows the results of a touch sensing simulation performed on the electrode made in the above embodiment, and the electrode of the second embodiment has a touch sensing failure phenomenon. Although the resistance change rates shown in Table 1 are all positive numbers, the present disclosure does not exclude the aspect that the resistance change rate is a negative number. In other words, as long as the absolute value of the resistance change rate meets the requirements listed here, it falls within the scope of the present disclosure. The formula for the change rate or change ratio is (resistance in bent state (ab)-resistance in normal state (ab)) / resistance in normal state (ab). [Table 1]

[0054] With reference to the first and second embodiments, it can be seen that electrodes made of the same specifications but different batches of silver nanowires have different resistance value changes after bending. In the touch sensing simulation transmission, the electrode of the second embodiment encountered a touch sensing transmission delay problem (represented by "△" in Table 1). As mentioned above, the common performance of each batch of silver nanowire paste is consistent, but there are differences in the specifications of individual silver wires between batches. Therefore, specifications are determined according to the characteristics of the electrodes to ensure the test suitability of the final product.

[0055] With reference to the first and third embodiments, a smaller percentage change in resistance can be achieved by using a silver nanowire paste with a high sheet resistance. The reason can be understood as follows: the silver nanowire paste with a high sheet resistance forms a higher resistance electrode after coating, so that the resistance change caused by the electrode in the bending region does not lead to a large percentage change in resistance. However, from the viewpoint of signal transmission, an electrode with a high resistance is not preferable. Therefore, although the silver nanowire paste with a high sheet resistance helps to achieve a smaller percentage change in resistance, considering the signal transmission of the whole electrode, it is recommended to use a silver nanowire paste with a sheet resistance of less than 100 ops, preferably less than 85 ops, or less than 70 ops in this embodiment of the present disclosure.

[0056] Also, taking the first and third embodiments for analysis, using a silver nanowire paste with a low sheet resistance may lead to a higher resistance change rate (%). Also, from the viewpoint of optics, a silver nanowire paste with a low sheet resistance may also cause a decrease in optical properties (such as an increase in haze) because it contains a large amount of silver nanowire components. Therefore, in this embodiment of the present disclosure, it is recommended to use a silver nanowire paste with a sheet resistance of more than 15 ops, preferably more than 20 ops, or more than 30 ops. In summary, in order to ensure that the change in resistance value of the touch electrode at the cross section ab of the bending region BZ does not exceed the specifications of the computing element and has good optical properties (such as a haze less than 1) and signal transmission properties, a silver nanowire paste with a sheet resistance of 15 to 100 ops, 20 to 85 ops, or 30 to 70 ops can be used. In the first embodiment, the haze of the conductive film made of a silver nanowire paste with 30 ops is 0.4 to 0.6. In the third embodiment, the conductive film made of 70 ops silver nanowire paste has a haze of 0.25 to 0.3. The conductive film in this embodiment is made of 30 to 70 ops silver nanowire paste and has a haze of 0.25 to 0.6.

[0057] With reference to the first and sixth embodiments, it can be seen that when a thicker substrate is adopted, the distortion of the silver nanowire electrode in the bending region is larger. According to the mechanical simulation system, the distortion of the electrodes in the first and sixth embodiments is 0.56% and 1.91% in the bending region, respectively. That is, when a thicker substrate is adopted, the distortion of the electrode in the bending region will be larger, and the change rate of the resistance value in the bending region will be larger. Considering that the distortion is directly proportional to the change rate of the resistance value of the electrode in the bending region, it can be predicted that when the distortion is more than 2.76%, the change rate of the resistance value of the electrode in the bending region may exceed 10% when the silver wire of the first embodiment is adopted. Meanwhile, when a thicker substrate is adopted, it can be seen from the mechanics theory that when the membrane layer is bent by applying stress, a tensile stress region and a compressive stress region will be formed, and a stress-free neutral axis / plane (see "Mechanics of Materials", James M. Gere et al.) will be formed between the two regions. Therefore, taking the first and sixth embodiments for illustration, when the substrate is thicker (i.e., the sixth embodiment), when the whole laminate structure is bent by applying stress, the position of the electrode will be farther from the neutral axis (compared to the first embodiment). As a result, in the sixth embodiment, the stress / strain in the electrode in the bending region will be larger, and the change rate of the resistance value in the bending region will be larger. According to the above neutral axis viewpoint, when a thicker substrate is adopted, it is conceivable to form other film layers, such as a protective layer, an adhesive layer, an optical film layer, etc., on the silver nanowire electrode to move the position of the neutral axis upward, i.e., to move the silver nanowire electrode closer to the neutral axis, thereby reducing the stress / strain in the electrode in the bending region, thereby achieving the change rate of the resistance value not exceeding 10%.

[0058] In addition, in the bent state, the change in the resistance value of the cross section cd also affects the sensitivity of the touch sensing. Taking the first embodiment as an example, the change in the resistance value of the cross section cd is approximately 1 to 5%. The formula for the rate of change or the change ratio is (resistance in the bent state (cd)-resistance in the normal state (cd)) / resistance in the normal state (cd).

[0059] In another embodiment of the electrode structure of the present disclosure, touch electrodes are arranged on both sides (e.g., upper and lower sides) of the substrate 11. For example, as shown in FIG. 6, the second electrode 12B (driving electrode, etc.) is arranged on the lower side of the substrate 11, and the first electrode 12A (sensing electrode, etc.) is arranged on the upper side of the substrate 11, so that both the first electrode 12A and the second electrode 12B can be formed as described above. In a bending state, both the first electrode 12A and the second electrode 12B need to satisfy the requirement that the rate of change of the resistance value does not exceed 10%. Meanwhile, since the distances to the axis FX1 are different between the first electrode 12A and the second electrode 12B, the distortions of the first electrode 12A and the second electrode 12B are different in the same bending state. Therefore, it can be seen that the rate of change of the resistance value of the first electrode 12A and the second electrode 12B is different in the same bending condition. In this embodiment, the distance from the first electrode 12A to the axis FX1 is longer than the distance from the second electrode 12B to the axis FX1 (i.e., the bending radius of the first electrode 12A is larger), so the second electrode 12B is subjected to a larger stress. Therefore, the rate of change in the resistance value of the second electrode 12B is larger than the rate of change in the resistance value of the first electrode 12A (however, both satisfy the requirement of not exceeding 10%). Taking the first and sixth embodiments as examples for analysis, under the condition of a bending radius of 3 mm, the rate of change in the resistance value of the second electrode 12B is approximately 1.1 to 2.5 times or 1.2 to 1.8 times the rate of change in the resistance value of the first electrode 12A.

[0060] In the eighth embodiment of the present disclosure, an electrode 12 is fabricated on a 25 μm thick cyclic olefin copolymer (COP) substrate manufactured by Konica Minolta, Inc., and then a 50 μm thick transparent polyimide thin film (colorless PI, CPI) is laminated via an optical adhesive layer, and a bending test with a bending radius of 3 mm is performed. In this embodiment, the CPI substrate is used to simulate a display element such as an organic light-emitting diode display (OLED). In this embodiment, the rate of change of the resistance value of the electrode 12 complies with the above-mentioned specifications.

[0061] In addition, the storage modulus and bending test results are measured by dynamic loading tests at different temperatures, and the average gradient of the storage modulus of the optical adhesive layer (~30℃~60℃) is -4.0kPa / ℃~-1.5kPa / ℃, so as to achieve sufficient stability (i.e., the adhesive properties do not change significantly with temperature changes) and to achieve good product reliability.

[0062] As shown in Table 2, in this embodiment of the disclosure, a variety of optical adhesive layers are tested. [Table 2]

[0063] As can be seen from these embodiments, the larger absolute value of the average slope of the storage modulus (for example, the absolute value of the average slope of the storage modulus of sample 4 is estimated to be more than 10 times that of the other three samples) indicates a larger variation in the storage modulus at -30°C to 60°C. Therefore, sample 4 has an excessively small storage modulus at high temperatures (such as 60°C), in which the material softens rapidly and has high fluidity (low material strength and very low cohesive force / crystallization force) in that temperature range, which is unfavorable for engineering applications. Specifically, the material strength of sample 4 at high temperatures (such as 60°C) is unfavorable for practical manufacturing processes, and in a bending state, the material strength of sample 4 is low, and stress is concentrated on the electrode 12, which may not meet the above-mentioned requirement for the rate of change of resistance value (specifically, less than 12% or less than 10%).

[0064] Conversely, under conditions where the absolute value of the average slope of the storage modulus is too small, such as less than 1.5 (absolute value of -1.5), the variation of the storage modulus in the temperature range (-30°C to 60°C) is not large, but the storage modulus of the material at high temperatures is excessive. An excessively large storage modulus means that the adhesive material is relatively hard and its adhesive strength is poor, which causes phenomena such as peeling and bubbles to occur in bending tests at high temperatures. Furthermore, the peeling and bubbles that occur during bending may simultaneously cause damage to the electrode 12 (i.e., the above-mentioned requirement for the rate of change of resistance value is not met), which will lead to the problem of reduced product reliability.

[0065] In summary, in this embodiment of the present disclosure, an optical adhesive having an average gradient of storage modulus (-30°C to 60°C) of -4.0kPa / °C to -1.5kPa / °C, or -3.8kPa / °C to -1.7kPa / °C, can be used to bond components such as a transparent cover plate, a display module, and an optical film to form a touch display device, so that the touch display device can meet the above-mentioned requirement of the rate of change of resistance value when bending.

[0066] Although not listed one by one here, it is understood that those skilled in the art can make various modifications and variations based on the above embodiments.

[0067] Finally, the technical features of the present disclosure and the technical effects achieved thereby are summarized as follows:

[0068] 1. According to this embodiment of the present disclosure, when the transparent electrode is in a bent state (the bending conditions are not limited), the change rate of the resistance value of the portion located in the bent region is less than 10%, so that the user can have a good touch experience when operating in the bent state.

[0069] 2. According to this embodiment of the present disclosure, when the transparent electrode is in a bent state (the bending radius is approximately 2-4 mm, or approximately 2, 3, or 4 mm), the change rate of the resistance value of the portion located in the bent region is 2%-8% or 2.4%-7.2%, and the electrical and optical properties (transmittance, haze, etc.) of the transparent electrode are all within the product specifications.

[0070] 3. According to this embodiment of the present disclosure, when the transparent electrode is bent with a bending radius of about 3 mm, the change rate of the resistance value of the portion located in the bending region is 2% to 8% or 2.8% to 7.2%. Thus, the electrical and optical properties (transmittance, haze, etc.) of the transparent electrode are all within the product specifications.

[0071] The implementation of the present disclosure has been described with reference to the above specific embodiments. Those skilled in the art can easily understand the technical features, advantages and effects of the present disclosure from the present disclosure.

[0072] The above description is merely a preferred embodiment of the present disclosure, and is not intended to limit the scope of the present disclosure. Other equivalent modifications and variations made without departing from the spirit of the present disclosure should be included in the scope of the appended claims.

Claims

1. A substrate; a sensing electrode disposed on the substrate, The electrode structure changes from an unfolded state to a bent state with a bending radius of 2 to 4 mm, the electrode structure includes, in the bent state, a bent region and a first non-bent region and a second non-bent region respectively adjacent to the bent region; the sensing electrode has a first resistance value change rate of less than 10% between the bent state and the unfolded state at an electrode portion of the sensing electrode in the bent region; the sensing electrode includes a first end within the first non-bending region and a second end within the second non-bending region, and a second resistance value change rate between the bent region and the deployed state in a portion of the sensing electrode between the first end and the second end is 1% to 5%.

2. 2. The electrode structure according to claim 1, wherein the rate of change in the first resistance value of the electrode portion of the sensing electrode in the bending region between the bent state and the unfolded state is 2% to 8%.

3. 3. The electrode structure according to claim 1, wherein the sensing electrodes include a first electrode and a second electrode, the first electrode and the second electrode being disposed on different sides of the substrate, the second electrode being closer to a bending axis than the first electrode, the first electrode having a first rate of change in resistance between the bent state having a bending radius of 3 mm and the unfolded state, the second electrode having a second rate of change in resistance between the bent state having a bending radius of 3 mm and the unfolded state, the second rate of change in resistance being 1.1 to 2.5 times the first rate of change in resistance, and both the second rate of change in resistance and the first rate of change in resistance being less than 10%.

4. The electrode structure according to claim 1 or 2, wherein the sensing electrode is made of silver or copper.

5. A device comprising the electrode structure according to claim 1 or 2, 1. A flexible display device comprising a display element, an optical adhesive layer disposed between the display element and the electrode structure; The display element displays images corresponding to the bent region, the first non-bent region, and the second non-bent region.

6. 6. The device of claim 5, wherein the optical adhesive layer has an average gradient of storage modulus in the temperature range of -30°C to 60°C within the range of -4.0 kPa / °C to -1.5 kPa / °C.

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