TWI747376B - Thin film sensor and touch display - Google Patents

Abstract

A thin film sensor comprises a substrate, a metal nanowire layer and an optical adhesive layer. The metal nanowire layer is formed above the substrate, and includes a plurality of electrode wires spaced apart from each other. The optical adhesive layer is formed above and is matched with the metal nanowire layer so as to let the variation rate of line resistance of each of the electrode wires less than 10% and the insulation resistance between adjacent two of the electrode wires more than 300M Ω under the weathering test of high temperature and high humidity (65℃/90% RH/DC 5V/240hrs), such that the reliability of the thin film sensor is improved.

Description

Thin film sensor and touch display

The present invention relates to a thin film sensor and a touch display, in particular to a thin film sensor and a touch display containing metal nanowires.

In recent years, touch screens have been widely used in various electronic products. In particular, most mobile communication products use touch screens, and in order to facilitate portability, foldable touch screens have been further developed.

Generally, the transparent conductive material used for display panels is indium tin oxide (ITO for short), but the ITO film is fragile and cannot be flexed, and its application in portable electronic products is relatively limited. Therefore, the development of flexible transparent conductive films that replace ITO is one of the key projects in the technical field.

At present, one of the more mature materials to replace ITO is metal nanowires. Patterning coatings containing metal nanowires can form conductive circuits and further form thin-film sensors. However, in the existing thin-film sensors containing metal nanowires, the conductive lines are prone to open circuit or short circuit under certain usage environments, resulting in product failures. Therefore, to provide a gold with improved reliability The thin film sensor belonging to the nanowire is the subject of current research and development.

Therefore, the present invention provides a thin film sensor capable of improving reliability.

Therefore, in some embodiments, the thin film sensor of the present invention includes a substrate, a metal nanowire layer, and an optical adhesive layer. The metal nanowire layer is formed on the substrate, and the metal nanowire layer forms a plurality of electrode lines spaced apart from each other. The optical adhesive layer is formed on the metal nanowire layer and matched with the metal nanowire layer, so that the electrode wire can be subjected to a weather resistance test under high temperature and humidity (65°C/90% RH/DC 5V/240 hours) The resistance change rate is less than 10%, and the insulation resistance between two adjacent electrode wires is greater than 300M Ω.

In some embodiments, the optical adhesive layer is made of the following optical adhesive materials: non-UV-curable acrylic adhesive and rubber, wherein the non-UV-curable acrylic adhesive is made of The optical adhesive layer has the properties of dielectric constant (frequency 100KHz) less than 4, water absorption (WA%) less than 0.3, and water vapor transmission rate (38°C/90% RH) less than 400g/m ² /day; from the rubber series The optical adhesive layer made of the material has the properties of dielectric constant (frequency 100KHz) less than 4, water absorption (WA%) less than 0.3, and water vapor transmission rate (38°C/90% RH) less than 100g/m ² /day.

In some embodiments, the thickness of the optical adhesive layer is 25 to 250 microns.

In some embodiments, the metal nanowire layer further includes a plurality of Fill the insulating part between the electrode wires.

In some embodiments, the metal nanowire layer is a structural layer of the insulating portion after the electrode lines are patterned.

In some embodiments, the thin film sensor further includes a protective layer formed on the metal nanowire layer, and the optical adhesive layer is formed on the protective layer.

In some embodiments, the protective layer has the properties of a dielectric constant (frequency 100KHz) less than 4 and a water vapor transmission rate (38°C/90% RH) less than 12 g/m ² /day.

In some embodiments, the thickness of the protective layer is between 0.2 and 10 microns.

In some embodiments, the distance between two adjacent electrode wires is between 10 and 50 microns.

In addition, the present invention provides a touch display containing the aforementioned thin film sensor capable of improving reliability.

In some embodiments, the touch display of the present invention includes a display module and the aforementioned thin film sensor.

In some embodiments, the touch display further includes an adhesive layer disposed between the display module and the film sensor, and the film sensor is attached to the display module through the adhesive layer.

In some embodiments, the thin film sensor is attached to the display module A packaging substrate, a polarizing plate or an electrode carrying substrate.

In some embodiments, the substrate is used as a substrate of a packaging substrate, a polarizing plate, or an electrode carrying substrate of the display module.

The present invention has at least the following functions: The thin film sensor of the present invention is designed to match the optical adhesive layer of the metal nanowire layer, so that the weather resistance test at high temperature and humidity (65°C/90% RH/DC 5V/240 hours) Below, the resistance change rate of the electrode wires of the metal nanowire layer is less than 10%, and the insulation resistance between two adjacent electrode wires is greater than 300M Ω, which can improve the reliability of the thin film sensor as a whole.

1: Thin film sensor

11: Substrate

12: Metal nanowire layer

121: Electrode wire

122: Insulation part

13: Optical adhesive layer

14: protective layer

2: Display module

3: Adhesive layer

100: Touch display

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: FIG. 1 is a schematic cross-sectional view of an embodiment of the thin film sensor of the present invention; and FIG. 2 is a touch display of the present invention A schematic cross-sectional view of an embodiment of the device.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same numbers. Position words such as "up" and "down" mentioned in the text only refer to the relative position of the currently specified view, not the absolute position. In addition, unless specifically limited in the text, "formed (or set) on..." is used The aspect represented by a word can include different aspects formed directly and indirectly.

Refer to FIG. 1, which is a schematic cross-sectional view of an embodiment of the thin film sensor of the present invention. The thin film sensor 1 includes: a substrate 11, a metal nanowire layer 12 and an optical adhesive layer 13. The metal nanowire layer 12 is formed on the substrate 11, and the metal nanowire layer 12 forms a plurality of electrode wires 121 spaced apart from each other, wherein the distance between two adjacent electrode wires 121 is about 10 microns Between 50 microns and 50 microns, for example, it can be 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, or 50 microns. The optical adhesive layer 13 is formed on the metal nanowire layer 12, and in addition to providing a bonding function, it is also used to improve the reliability of the thin film sensor 1. More specifically, the optical adhesive layer 13 is matched with the metal nanowire layer 12 to be subjected to the weather resistance test of High Temperature and High Humidity (HTHH) (65°C/90% RH/DC 5V/240 hours) , The resistance change rate of the electrode line 121 is less than 10%, and the insulation resistance between two adjacent electrode lines 121 is greater than 300MΩ. Among them, because the metal ions of the metal nanowire layer 12 will migrate, the optical adhesive layer 13 needs to be arranged to match the metal nanowire layer 12 to effectively reduce the occurrence of metal ion migration. On the other hand, other sensors that use traditional conductive material layers (such as ITO) do not have the problem of metal ion migration, and therefore do not need or specifically match the conductive material layer in the arrangement of the optical glue. In other words, the optical adhesive layer 13 matches the metal nanowire layer 12, which means that the optical adhesive selected for the optical adhesive layer 13 matches the metal nanowire material of the metal nanowire layer 12 to control the water content and keep the metal ions. Below the electrolysis critical value, in order to effectively reduce the generation of metal ion migration. In addition, add It is noted that the line distance between two adjacent electrode wires 121 may also affect the probability of product function failure due to metal ion migration. The smaller the line distance, the more severe the test environment. The thin film sensing of this embodiment The distance between the two adjacent electrode wires 121 of the device 1 is between 10 μm and 50 μm, which can still meet the above-mentioned specifications under the weather resistance test.

In some embodiments, the thickness of the optical adhesive layer 13 may be between 25 and 250 μm, preferably between 50 and 150 μm. The material of the optical adhesive layer 13 can be selected from the following optical adhesive materials: non-UV-curable acrylic adhesive and rubber, wherein the optical adhesive layer 13 made of the non-UV-curable acrylic adhesive has a medium The electrical constant (frequency 100KHz) is less than 4 (preferably less than 3), the water absorption rate (WA%) is less than 0.3 (preferably less than 0.25), and the water vapor transmission rate (38°C/90% RH) is less than 400g/m ² /day , That is, the water vapor transmission rate (WVTR) measured in an environment with a temperature of 38°C and a relative humidity of 90% is less than 400 grams per square meter per day (24 hours); from this rubber-based material The prepared optical adhesive layer 13 has a dielectric constant (frequency 100KHz) less than 4 (preferably less than 3), water absorption (WA%) less than 0.3 (preferably less than 0.25), and water vapor transmission rate (38°C/90% RH) The property is less than 100g/m ² /day. In an embodiment, the optical adhesive layer 13 is preferably an optical adhesive made of rubber-based materials.

In this embodiment, the metal nanowire layer 12 further includes an insulating portion 122 filled between the electrode wires 121. The manufacturing process of the metal nanowire layer 12 is further described below.

In some embodiments, the metal nanowire layer 12 is made of metal nanowires. The thread dispersion or slurry is formed through the steps of coating, drying/curing molding, and patterning. The coating step is for example, but not limited to: screen printing, nozzle coating, roller coating and other processes; in one embodiment, a roll to roll process can be used to disperse the dispersion liquid containing metal nanowires Or the slurry is coated on the surface of the continuously supplied substrate. The dispersion with metal nanowires can be solvents, such as water, alcohols, ketones, ethers, hydrocarbons or aromatic solvents (benzene, toluene, xylene, etc.); the dispersions can also contain additives, surfactants or Binders, such as carboxymethyl cellulose (CMC), 2-hydroxyethyl cellulose (hydroxyethyl Cellulose, HEC), hydroxypropyl methylcellulose (HPMC), sulfonate, sulfate , Disulfonate, sulfosuccinate, phosphate or fluorine-containing surfactant, etc. The metal nanowires (metal nanowires) layer, for example, can be composed of a silver nanowires layer, a gold nanowires layer or a copper nanowires layer; In detail, the "metal nanowires" used in this article can be metal wires of elemental metals, metal alloys, and combinations thereof. The number of metal nanowires contained therein does not affect the original The scope of protection claimed by the invention; and at least one cross-sectional dimension (ie the diameter of the cross-section) of a single metal nanowire is less than 500nm, preferably less than 100nm, and more preferably less than 50nm; and the invention is called "wire" "Metal nanostructures mainly have a high aspect ratio, such as between 10 and 100,000. In more detail, the aspect ratio (length: diameter of the cross section) of the metal nanowire can be greater than 10, preferably greater than 50 And more Preferably greater than 100; the metal nanowire can be any metal, including (but not limited to) silver, gold, copper, nickel and gold-plated silver. Other terms, such as silk, fiber, tube, etc., if they also have the above-mentioned size and high aspect ratio, are also covered by the present invention.

In some embodiments, the metal nanowires can be silver nanowires or silver nanofibers, which can have an average diameter of about 20 to 100 nanometers, and an average of about 20 to 100 microns. The length is preferably an average diameter of about 20 to 70 nanometers, and an average length of about 20 to 70 microns (that is, an aspect ratio of 1000). In some embodiments, the diameter of the metal nanowire can be between 70 nanometers and 80 nanometers, and the length is about 8 micrometers.

The curing/drying step is mainly to volatilize solvents and other substances, so that the metal nanowires are distributed on the surface of the substrate in a random manner; preferably, the metal nanowires will be fixed on the surface of the substrate and not The metal nanowire layer 12 is formed until it falls off, and the metal nanowires can contact each other to provide a continuous current path, thereby forming a conductive network.

In addition, the aforementioned metal nanowires can be further subjected to post-processing to increase their conductivity. The post-processing can include process steps such as heating, plasma, corona discharge, UV ozone, or pressure. For example, after the step of curing and forming the metal nanowire layer 12, a roller can be used to apply pressure thereon. In one embodiment, one or more rollers can be used to apply 50 to 3400 psi to the metal nanowire layer 12 Pressure, preferably 100 To 1000 psi, 200 to 800 psi or 300 to 500 psi pressure. In some embodiments, heating and pressure post-processing can be performed at the same time; in detail, the formed metal nanowire can be heated through one or more rollers as described above and heated at the same time, for example, the roller is applied. The pressure is 10 to 500 psi, preferably 40 to 100 psi; while heating the roller to between about 70°C and 200°C, preferably between about 100°C and 175°C, it can improve the conductivity of the metal nanowire layer 12 Spend. In some embodiments, the metal nanowires can preferably be exposed to a reducing agent for post-processing. For example, metal nanowires containing silver nanowires can preferably be exposed to a silver reducing agent for post-processing. The silver reducing agent includes Borohydrides, such as sodium borohydride; boron nitrogen compounds, such as dimethylaminoborane (DMAB); or gaseous reducing agents, such as hydrogen (H2). The exposure time is about 10 seconds to about 30 minutes, preferably about 1 minute to about 10 minutes. The above-mentioned steps of applying pressure can be implemented in appropriate steps according to actual needs.

The patterning step can be, for example, exposure/development (ie, a well-known lithography process) and etching on the cured metal nanowire layer 12. In one embodiment, the metal nanowire layer 12 preferably has the following characteristics: the light transmittance of visible light (for example, the wavelength is between about 400nm-700nm) can be greater than about 80%, and the surface resistivity (surface resistivity) resistance) is between about 10 to 1000 ohm/square; preferably, the visible light (for example, the wavelength is between about 400nm-700nm) of the metal nanowire layer 12 has a light transmittance (Transmission) greater than about 85%, and the surface resistance is about 50 to 500 ohms/square (ohm/square).

In this embodiment, the insulating portion 122 of the metal nanowire layer 12 is an overcoat (OC ), through the provision of the insulating portion 122, the structural layer of the metal nanowire layer 12 can further maintain a better electrical insulation between the adjacent electrode lines 121. The material of the insulating part 122 may be, for example, polymethyl methacrylate, polyvinyl alcohol, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyvinyl toluene, polyvinyl Vinyl xylene, polyimide, polyimide, polyimide-imide, polyetherimide, polysulfide, polyimide, polyphenylene, polyphenylene ether, polyurethane, epoxy resin, Polyurethane, polysiloxane, polysiloxane, poly(silicon-acrylic), etc.

In some embodiments, the material suitable for the substrate 11 is preferably a transparent material, which may be a flexible transparent substrate. The material may be selected from, for example, polyethylene terephthalate (PET). , Polyimide (PI), polycarbonate (PC), polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), polypropylene (PP), Polyethylene naphthalate (PEN), polystyrene (PS), cyclo-olefin polymers (COP), etc.

In this embodiment, the thin-film sensor 1 further includes a passivation layer (Passivation Layer) 14, formed between the metal nanowire layer 12 and the optical adhesive layer 13. Specifically, the passivation layer 14 can be formed on the metal nanowire layer. The surface of the rice wire layer 12, and the optical adhesive layer 13 is formed on the surface of the protective layer 14, so that the protective layer 14 is in direct contact with the metal nanowire layer 12 and the optical adhesive layer 13, respectively. In another embodiment, between the protective layer 14 and the metal nanowire layer 12 or between the optical adhesive layer 13 may be further provided with optical layers, functional layers, etc. required by the design, which is not here. Limited by this disclosure. In addition, the protective layer 14 has the following properties: the dielectric constant (frequency 100KHz) is less than 4 (preferably less than 3), that is, the dielectric constant measured at a frequency of 100KHz is less than 4, and the water vapor transmission rate (38°C/90% RH ) Less than 12g/m ² /day. The thickness of the protective layer 14 may be between 0.2 and 10 microns, preferably between 2.5 and 6.5 microns. Suitable materials for the protective layer 14 can be, for example, dry film, photoresist, ink, etc., in which an embodiment of the ink can be, for example, a baking type insulating ink and the baking temperature of the insulating ink is less than 110°C. This is not the present disclosure. Limited. The design of the protective layer 14 can further block water vapor and improve the reliability of the thin film sensor 1 in a high temperature and high humidity environment.

The completed sample was tested with 5V direct current in a high-temperature and high-humidity environment with a temperature of 65°C and a relative humidity of 90%. The test results are summarized in Table 1 below. Among them: Experimental Example 1 is the structure of the embodiment in Figure 1, without setting The structure of the protective layer 14 is used as a sample; Experimental Example 2 is based on the structure of the embodiment in FIG. The structure of the layer 13 and the protective layer 14 is used as the sample; Comparative Example 1 is the structure of the embodiment in FIG. 1 without the protective layer 14 and the optical adhesive layer 13 as the sample; Comparative Example 2 is the embodiment of FIG. 1 In the structure, the structure without the optical adhesive layer 13 is used as a sample.

From the test results shown in Table 1, it can be seen that the experimental examples 1 and 2 are the samples with the optical adhesive layer 13 compared to the samples without the optical adhesive layer in the comparative examples 1 and 2, and the experimental examples 1 and 2 are in a high-temperature and high-humidity environment. The reliability of 2 is significantly better than that of Comparative Examples 1 and 2. That is, the design of the optical adhesive layer 13 of the thin-film sensor 1 of the present disclosure can effectively improve the verification result of reliability. Furthermore, it can be seen from Experimental Example 2 that if the optical adhesive layer 13 plus the protective layer 14 are stacked in the thin film sensor 1, the reliability can be greatly improved.

Please refer to FIG. 2, which is a schematic cross-sectional view of an embodiment of the touch display of the present invention. The touch display 100 of this embodiment includes a thin film sensor 1, a display module 2 and an adhesive layer 3. The thin film sensor 1 can, for example, adopt the structure of the thin film sensor 1 disclosed in the embodiment of FIG. 1 , The relevant structure and material content will not be repeated here. The display module 2 can be, for example, an organic light emitting diode display module (OLED), a liquid crystal display

Module (LCD), etc. In addition, since the thin film sensor 1 of the present embodiment uses the flexible metal nanowire layer 12 as the touch electrode, in order to allow the touch display 100 to achieve a bendable effect, the display module 2 may also be Use flexible display module. The adhesive layer 3 is disposed between the film sensor 1 and the display module 2.

The thin film sensor 1 of this embodiment is integrated with the display module 2, and specifically is arranged on the display module 2, and is bonded to the display module 2 through the adhesive layer 3. The thin film sensor 1 can be attached Any structural layer, such as a packaging substrate, a polarizing plate, or an electrode-carrying substrate of the display module 2, is not limited by the present disclosure. In some embodiments, in order to further achieve the effect of thinning, the substrate 11 of the thin film sensor 1 can be directly used as the substrate of the structural layer such as the packaging substrate, the polarizing plate or the electrode carrier substrate in the display module 2, so that The metal nanowire layer 12 of the thin film sensor 1 is directly formed on the surface of the substrate of any structural layer in the display module 2.

In summary, the thin film sensor 1 of the present invention matches the design of the optical adhesive layer 13 of the metal nanowire layer 12, making it weather resistant at high temperature and high humidity (65°C/90% RH/DC 5V/240 hours) Under the test, the resistance change rate of the electrode wire 121 is less than 10%, and the insulation resistance between two adjacent electrode wires 121 is greater than 300 MΩ, which can improve the reliability of the thin film sensor 1 as a whole.

However, the above are only examples of the present invention, and should not be used to limit the scope of implementation of the present invention, all simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the content of the patent specification still belong to The scope of the invention patent 内内。 In the enclosure.

1: Thin film sensor

11: Substrate

12: Metal nanowire layer

121: Electrode wire

122: Insulation part

13: Optical adhesive layer

14: protective layer

Claims (13)

A thin film sensor includes: a substrate; a metal nanowire layer formed on the substrate, and the metal nanowire layer forms a plurality of electrode lines spaced apart from each other; and an optical adhesive layer formed On the metal nanowire layer and matching the metal nanowire layer, the resistance change rate of the electrode wire is less than 10%, and the insulation resistance between two adjacent electrode wires is greater than 300M Ω. The thin film sensor according to claim 1, wherein the optical adhesive layer is made of the following optical adhesive materials: non-ultraviolet light-cured acrylic adhesive and rubber, wherein the non-ultraviolet light-cured acrylic The optical adhesive layer made of adhesive material has a dielectric constant (frequency 100KHz) less than 4, water absorption (WA%) less than 0.3, and water vapor transmission rate (38°C/90% RH) less than 400g/m ² /day Properties: The optical adhesive layer made of this rubber-based material has a dielectric constant (frequency 100KHz) less than 4, water absorption (WA%) less than 0.3, and water vapor transmission rate (38°C/90% RH) less than 100g/m The nature of ^{2 /day.} The thin film sensor according to claim 2, wherein the thickness of the optical adhesive layer is 25 to 250 microns. The thin film sensor according to claim 1, wherein the metal nanowire layer further includes a plurality of insulating portions filled between the electrode wires. The thin film sensor according to claim 4, wherein the metal nanowire layer is The structure layer of the insulating part is formed after the electrode lines are patterned. The thin film sensor according to claim 1, further comprising a protective layer formed on the metal nanowire layer, and the optical adhesive layer is formed on the protective layer. The thin film sensor according to claim 6, wherein the protective layer has a dielectric constant (frequency 100KHz) of less than 4 and a water vapor transmission rate (38°C/90% RH) of less than 12 g/m ² /day. The thin film sensor according to claim 6, wherein the thickness of the protective layer is between 0.2 and 10 microns. The thin film sensor according to claim 1, wherein the line distance between two adjacent electrode lines is between 10 and 50 microns. A touch display includes: a display module; and a thin film sensor as described in any one of claim items 1-9, integrated in the display module. According to claim 10, the touch display further includes an adhesive layer disposed between the display module and the film sensor, and the film sensor is attached to the display module through the adhesive layer. The touch display according to claim 11, wherein the thin film sensor is attached to a packaging substrate, a polarizing plate or an electrode carrying substrate of the display module. The touch display according to claim 10, wherein the substrate is used as the base of a packaging substrate, a polarizing plate, or an electrode carrier substrate of the display module material.

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