CN114479559A

CN114479559A - Ink composition and method for forming insulating layer and touch panel

Info

Publication number: CN114479559A
Application number: CN202011258777.XA
Authority: CN
Inventors: 陈龙宾; 杨宜龙; 陈威州; 朱俊鸿
Original assignee: TPK Touch Solutions Xiamen Inc
Current assignee: TPK Touch Solutions Xiamen Inc
Priority date: 2020-11-12
Filing date: 2020-11-12
Publication date: 2022-05-13

Abstract

The present disclosure discloses an ink composition for forming an insulating layer, a method for forming the same, and a touch panel, wherein the ink composition for forming the insulating layer includes an acrylic resin, an acrylic monomer, a fluorine-containing thiol compound, a silane coupling agent, a photo-curing agent, and a solvent, and the ink composition can be used in an inkjet process. The insulating layer formed using the ink composition has a breakdown voltage of more than 800V at a thickness of 2 μm and a dielectric constant of 2.0 to 4.0 at a frequency of 100 kHz. The ink composition disclosed in the present disclosure can directly form a patterned insulating layer in a low temperature process, thereby preventing damage to other components caused by high temperature or additional patterning processes. The ink composition comprises the fluorine-containing thiol compound and the silane coupling agent, so that the breakdown voltage of the insulating layer can be increased, and the dielectric constant of the insulating layer can be reduced.

Description

Ink composition and method for forming insulating layer and touch panel

Technical Field

The present disclosure relates to an ink composition for forming an insulating layer, a method thereof, and a touch panel.

Background

In electronic devices, the insulating layer provides the necessary electrical isolation and is patterned into a suitable shape in cooperation with the design of the electronic device. The patterning of the insulating layer includes a plurality of steps, for example, coating a material of the insulating layer on the substrate, exposing the insulating layer using a mask having a pattern, removing a portion of the insulating layer through a developing process, and finally baking the patterned insulating layer at a high temperature to obtain a patterned insulating layer on the substrate.

Disclosure of Invention

The present disclosure provides an ink composition for forming an insulating layer, including an acrylic resin, an acrylic monomer, a fluorine-containing thiol compound, a silane coupling agent, a photo-curing agent, and a solvent, wherein the ink composition is used in an inkjet process.

In some embodiments of the present disclosure, the viscosity of the ink composition is 5 to 40mPa · s at 25 ℃.

In some embodiments of the present disclosure, the acrylic resin is present at a weight percent concentration of 9 wt% to 33 wt% and the acrylic monomer is present at a weight percent concentration of 10 wt% to 30 wt%.

In some embodiments of the present disclosure, the concentration of the fluorine-containing thiol compound is about 0.001 wt% to 0.1 wt%, and the concentration of the silane coupling agent is about 0.1 wt% to 1 wt%.

The present disclosure provides a method of forming an insulating layer, including inkjet-printing an ink composition on a substrate to form an ink layer, curing the ink layer at a low temperature, and curing the ink layer using ultraviolet light to form the insulating layer, wherein the ink composition includes an acrylic resin, an acrylic monomer, a fluorine-containing thiol compound, a silane coupling agent, a photo-curing agent, and a solvent.

In some embodiments of the present disclosure, the temperature of the low temperature cured ink layer is 50 ℃ to 130 ℃.

In some embodiments of the present disclosure, the dimensional shrinkage of the insulating layer compared to the ink layer is less than 10%.

The present disclosure provides an insulating layer made using the above method.

In some embodiments of the present disclosure, the breakdown voltage of the insulating layer at a thickness of 2 μm is greater than 800V.

In some embodiments of the present disclosure, the dielectric constant of the insulating layer is 2.0 to 4.0 at a frequency of 100 kHz.

In some embodiments of the present disclosure, the insulating layer has a thickness of 2 μm to 12 μm.

The present disclosure provides a touch panel including the above insulating layer.

In some embodiments of the present disclosure, the touch panel includes a substrate, a plurality of first sensing electrodes disposed on the substrate along a first direction, a connection electrode disposed on the substrate and electrically connected to the first sensing electrodes, a plurality of second sensing electrodes disposed on the substrate along a second direction, an insulating layer disposed on the connection electrode, and a bridging wire disposed on the insulating layer. The second direction is different from the first direction, the vertical projections of the first sensing electrode and the second sensing electrode are not overlapped, the bridging lead is electrically connected with the second sensing electrode, and the insulating layer electrically isolates the first sensing electrode from the second sensing electrode.

In some embodiments of the present disclosure, the first sensing electrode, the connection electrode, and the second sensing electrode comprise a layer of nanosilver.

Drawings

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying drawing figures. It should be noted that the various features are not drawn to scale according to standard methods in the industry. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a flow chart illustrating a process for forming an insulating layer, according to some embodiments;

FIGS. 2A-2C illustrate schematic cross-sectional views of stages in a process flow diagram, according to some embodiments;

FIG. 3 is a graph showing current versus voltage in an insulating layer according to various embodiments;

FIG. 4 shows a top view of a touch panel, according to some embodiments;

fig. 5 is a cross-sectional view of the touch panel according to the reference cross-section in fig. 4.

[ notation ] to show

100 flow chart of the process

110,120,130, step

200 base plate

210 ink layer

212 cured ink layer

214 insulating layer

220 low temperature curing process

230 ultraviolet light

300,310 curve

400 touch panel

405 substrate

410 first sensing electrode

415 connecting electrode

420 second induction electrode

430 insulating layer

440 bridge conductor

A-A reference section

D1 first direction

D2 second direction

T1 thickness

W1 width

Detailed Description

To achieve the various features of the subject matter referred to, the following disclosure provides many different embodiments, or examples. Specific examples of components, operations, materials, configurations, etc., are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. Other components, operations, materials, configurations, etc. are also contemplated. For example, in the description that follows, forming a first feature over or on a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact. Additionally, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Furthermore, spatially relative terms, such as "below …," "below …," "lower," "above …," "upper," and the like, may be used herein to facilitate describing one element or feature's relationship to another element or feature as shown. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In the present process for forming an insulating layer, due to the composition characteristics of the insulating layer solution, the insulating layer is required to be coated on a substrate and cured, and then patterned by photolithography process (e.g., wet etching) using a mask and high-temperature baking (e.g., 150 to 250 ℃). In some embodiments, it is also desirable to cure the pattern of the insulating layer by irradiation (e.g., ultraviolet irradiation). These photolithography processes include multi-step etching processes, which are costly and time consuming, and high temperature processes are difficult to be compatible with flexible substrates, and are generally limited.

The ink composition for forming an insulating layer disclosed in the present disclosure can directly form a patterned insulating layer on a substrate by inkjet printing, and can be cured directly by ultraviolet light without a mask after low-temperature curing. The insulating layer process provided by the disclosure simplifies the patterning step, can be used for a flexible substrate due to a low-temperature process, and has a wide process application range.

Fig. 1 illustrates a process flow diagram 100 for forming an insulating layer, and fig. 2A-2C illustrate schematic cross-sectional views of stages in the process flow diagram 100, according to some embodiments of the present disclosure. Fig. 1 to 2C are merely illustrative of processes using the ink composition provided by the present disclosure, however, it should be understood that alternative embodiments in which other steps are added before, during and after the processes are also within the scope of the present disclosure.

Referring to fig. 1 and 2A, an Ink composition is applied on a substrate 200 through an Ink jet (Ink-jet) process (or may be referred to as a spray process) to form an Ink layer 210. The corresponding process is illustrated as step 110 of the process flow diagram 100 shown in FIG. 1.

In some embodiments, as shown in fig. 2A, the ink layer 210 may have a patterned shape when formed on the substrate 200 by an inkjet process, for example, a mask is used to cover a portion of the substrate 200 and then the inkjet process is performed, so that an additional photolithography process is not required for patterning in a subsequent process. In other embodiments, the ink composition may be jetted onto the entire substrate 200 and patterned (e.g., dry or wet etched) in a subsequent process to form the ink layer 210.

The substrate 200 may be applied to various electronic devices, such as a touch panel. In some embodiments, the substrate 200 may comprise a hard substrate for high temperature processing, such as a glass substrate, a wafer, a quartz substrate, a silicon carbide substrate, a ceramic substrate, and the like.

In some embodiments, the substrate 200 may be a flexible substrate suitable for use in a flexible device. In some embodiments, the substrate 200 may include a flexible substrate for low temperature processing, such as Polyethylene Terephthalate (PET), Cyclic Olefin Polymer (COP), Cyclic Olefin Copolymer (COC), Polycarbonate (PC), polymethyl methacrylate (PMMA), Polyimide (PI), Polyethylene Naphthalate (PEN), Polyvinylidene fluoride (PVDF), Polydimethylsiloxane (PDMS), and the like.

The ink composition for forming the ink layer 210 includes Acrylic resin (Acrylic resin), Acrylic monomer (Acrylic monomer), fluorine-Containing Thiol Compound (Fluoro-Containing Thiol Compound), Silane Coupling agent (Silane Coupling agent), photo-curing agent (photo-curing agent), and solvent.

In some embodiments, the acrylic resin may include soluble acrylate copolymer (acrylate copolymer), soluble epoxy acrylate resin (epoxyacrylate resin), the like, or combinations thereof. In some embodiments, the weight percent concentration of the acrylic in the ink composition forming the ink layer 210 may be between about 9 wt% to about 33 wt%.

In some embodiments, the acrylic monomers may include dimethacrylate (dimethacrylate), triacrylate (triacrylate), pentaacrylate, hexaacrylate, and the like, or combinations thereof. In some embodiments, the weight percent concentration of the acrylic monomer in the ink composition forming the ink layer 210 may be between about 10 wt% to about 30 wt%.

Since the acrylic resin is a high molecular compound and has a high viscosity, if it is used alone as an ink composition, the viscosity of the ink composition is too high to be applied in an ink jet process. In contrast, the acrylic monomer is a small molecular compound having a low viscosity, and if it is used alone as an ink composition, the viscosity of the ink composition is too low to maintain the film-forming property on the substrate 200 or to be directly sprayed to form a patterned shape. In the embodiment of the disclosure, by properly adjusting the ink composition for forming the ink layer 210, the ink composition can have a proper viscosity and can be directly applied to the inkjet process.

Further, the ink composition includes a high viscosity acrylic resin and a low viscosity acrylic monomer, and the ratio of the acrylic resin to the acrylic monomer is adjusted, for example, such that the acrylic resin concentration in the ink composition is about 9 wt% to about 33 wt%, and the acrylic monomer concentration in the ink composition is about 10 wt% to about 30 wt%, so that the ink composition can have a viscosity of about 5 millipascal-seconds (mPa · s) to about 40mPa · s at room temperature (e.g., at 25 ℃) to be suitable for use in an apparatus for inkjet printing, thereby directly forming the patterned ink layer 210 on the substrate 200 using an inkjet process. In some embodiments, the surface tension of the ink composition forming the ink layer 210 may be between about 20 dynes (dynes) to about 42 dynes.

The ink composition forming the ink layer 210 includes a photo-curing agent therein. And (3) adding ultraviolet light for irradiation in the subsequent ultraviolet light curing process, wherein the light curing agent generates free radicals due to the irradiation of the ultraviolet light, and the free radicals initiate the polymerization reaction of the acrylic resin and the acrylic monomer to form the cured insulating layer. In some embodiments, the photocuring agent can include

184、

1173、

2959、

127、

907、

379、

754、

OXE01、

OXE02、

TOP、

819、

784, the like, or combinations thereof. In some embodiments, the photo-curing agent may be present in the ink composition forming the ink layer 210 at a weight percent concentration of between about 2 wt% and about 7 wt%.

The ink composition forming the ink layer 210 includes a fluorine-containing thiol compound and a silane coupling agent, which have a synergistic effect (synergy) in the ink composition, so that the ink layer 210 has a higher breakdown voltage (breakdown voltage) and a lower dielectric constant after being subsequently cured, and details will be further described later.

The ink composition for forming the ink layer 210 includes a fluorine-containing thiol compound and a silane coupling agent. In some embodiments, the fluorothiol compound may include fluoroalkylthiol (fluoroalkylthiol), fluoroalkylthiophenol (fluoroalkylthiophenol), and the like, or derivatives thereof. In some embodiments, the silane coupling agent may include 2- (3, 4-epoxycyclohexane) ethyltrimethoxysilane (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane), N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (N- (2-aminoethyl) -3-aminopropyltrimethoxysilane), 3- (methacryloyloxy) propyltrimethoxysilane (3- (methacryloyloxy) propyltrimethoxysilane), and the like.

In some embodiments, the concentration of the fluoro-thiol compound in the ink composition forming the ink layer 210 may be between about 0.001 wt% and about 0.1 wt%, and the concentration of the silane coupling agent may be between about 0.1 wt% and about 1 wt%.

The ink composition forming the ink layer 210 includes a solvent that can dissolve the above-described constituent compounds, and includes, for example, water, ethanol, isopropyl alcohol, acetone, diacetone alcohol, tetrahydrofuran, aprotic solvents (e.g., N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide), propylene glycol methyl ether acetate, propylene glycol monomethyl ether, 3-methoxy-1-butanol, ethyl acetate, cyclohexanone, cyclopentanone, and the like, or a combination thereof. In some embodiments, the weight percent concentration of the solvent in the ink composition forming the ink layer 210 may be between about 29 wt% to about 79 wt%.

Referring to fig. 1 and 2B, a cured ink layer 212 is formed on the substrate 200 through a low temperature curing process 220 (which may be referred to as a first curing process), for example, heating to form the cured ink layer 212. The corresponding process is illustrated as step 120 of the process flow diagram 100 shown in FIG. 1. After the ink layer 210 in fig. 2A is subjected to a low temperature curing process 220, a cured ink layer 212 is formed on the substrate 200.

The low temperature curing process 220 is a low temperature process that does not deform or damage the substrate 200 due to high temperature during the formation of the cured ink layer 212, thereby increasing the number of options for the substrate 200, such as the types of the substrate 200 mentioned above. In some embodiments, the temperature of the low temperature curing process 220 is less than the maximum process temperature of the substrate 200. Generally, the maximum processing temperature of the substrate 200 is generally related to the glass transition temperature (Tg) of the substrate 200.

In some embodiments, the temperature of the low temperature curing process 220 may be less than or equal to 130 ℃. In some embodiments, the temperature of the low temperature curing process 220 may be between about 50 ℃ and about 130 ℃, which is substantially lower than the highest processing temperature of low temperature plastic substrates used in the electronics industry, such as PET with a maximum processing temperature of about 120 ℃, PC with a maximum processing temperature of about 130 ℃, PMMA with a maximum processing temperature of about 110 ℃, and the like. The manufacturing temperature range is lower than the maximum processing temperature of the substrate that can withstand high temperature (e.g., the maximum processing temperature of the glass substrate is about 500 ℃, and the maximum processing temperature of PEN is about 150 ℃), so the low temperature curing process 220 is also applicable to the substrate.

In some embodiments, the low temperature curing process 220 heats the space or chamber where the substrate 200 is located to form the cured ink layer 212. In some embodiments, the low temperature curing process 220 is a process of directly heating the substrate 200 to form the cured ink layer 212.

The cured ink layer 212 is attached to the substrate 200 after the low-temperature curing process 220, and the surface of the cured ink layer 212 is not sticky, so that the cured ink layer 212 can be subjected to other steps before a subsequent ultraviolet curing process or can be temporarily stored first, thereby increasing the flexibility of the process. For example, in some embodiments, when the substrate 200 is a flexible substrate, the cured ink layer 212 on the substrate 200 is pre-rolled with the flexible substrate 200 without damaging the patterned shape, so as to be stored together, and the substrate 200 and the cured ink layer 212 formed in a Roll can be taken out later to perform a Roll-to-Roll (Roll-to-Roll) process.

Since the ink composition forming the ink layer 210 in fig. 2A includes the fluorine-containing thiol compound and the silane coupling agent, both have synergistic effects in the ink composition, so that the cured ink layer 212 after low-temperature curing has a higher breakdown voltage and a lower dielectric constant. In some embodiments, the cured ink layer 212 having the above characteristics may be applied to an insulator in an electronic component, such as an insulating layer between electrodes, thereby improving the electrical insulation performance of the insulating layer.

Referring to fig. 1 and 2C, an insulating layer 214 is formed on the substrate 200 through an ultraviolet curing process (which may be referred to as a second curing process). The corresponding process is illustrated as step 130 of the process flow diagram 100 shown in FIG. 1. Referring to fig. 2B and 2C in combination, after the cured ink layer 212 is further cured by the uv curing process, an insulating layer 214 is formed on the substrate 200.

In the uv curing process, the uv light 230 is used to irradiate the cured ink layer 212, so that the photo-curing agent in the cured ink layer 212 generates radicals, and the radicals catalyze the acrylic resin and the acrylic monomer to generate an acrylic polymer, and form the insulating layer 214. In some embodiments, the energy of the ultraviolet light 230 may be between about 50 millijoules per square centimeter to about 6000 millijoules per square centimeter.

The insulating layer 214 cured by the ultraviolet light 230 includes an acrylic polymer, a fluorine-containing thiol compound, and a silane coupling agent. As shown in fig. 2C, the insulating layer 214 after the uv curing process has a thickness T1 and a width W1. In some embodiments, the thickness T1 may be in the range of about 1 μm to about 15 μm, and more particularly, the thickness T1 may be in the range of about 2 μm to about 12 μm. The width W1 is matched with the resolution of the inkjet process, so that the insulating layer 214 is more suitable for large-sized devices, such as television panels. In some embodiments, width W1 may be greater than or equal to about 40 μm.

The size of the insulating layer 214 after uv curing is slightly smaller than that of the cured ink layer 212 before uv curing, and the difference between before and after uv curing can be expressed by shrinkage rate, and smaller shrinkage rate indicates smaller deformation caused by uv curing. On the other hand, the electrical characteristics (such as the breakdown voltage, dielectric constant, etc.) of the insulating layer 214 are the same as those of the cured ink layer 212, i.e., the second curing (i.e., uv curing) only slightly improves the polymerization characteristics of the cured ink layer 212 and slightly changes the external dimensions of the cured ink layer 212, but does not affect the electrical characteristics of the cured ink layer 212. In some embodiments, the dimensional shrinkage of the insulating layer 214 after uv curing may be less than about 10% compared to the cured ink layer 212.

In some embodiments, the thermal curing (first curing) and the uv curing (second curing) can be performed simultaneously, the electrical characteristics of the resulting insulating layer 214 are similar to those of the above embodiments, and the shrinkage rate of the resulting insulating layer 214 is the size difference between the ink layer after inkjet film formation (i.e., wet film, similar to the ink layer 210 in fig. 2A) and the cured insulating layer 214. In such embodiments, the shrinkage of insulating layer 214 is similar to that described above, e.g., the shrinkage is less than about 10%.

According to some embodiments, FIG. 3 is a graph of current versus voltage in an insulating layer according to various embodiments, thereby illustrating breakdown voltages of insulating layers according to various embodiments. In the graph of the relationship between current and voltage, the current increases rapidly as the voltage increases to a threshold value, and the voltage threshold value at this time is called a breakdown voltage (breakdown voltage).

Referring to fig. 3 and table one below, in comparative example 1 represented by curve 300, the ink composition for forming the insulating layer was similar to the ink composition for forming the ink layer 210 in fig. 2A, but did not include the fluorine-containing thiol compound and the silane coupling agent. In example 1 represented by the curve 310, the ink composition for forming the insulating layer is the same as the ink composition for forming the ink layer 210. In some embodiments, the ink composition of comparative example 1 requires a higher curing temperature and does not meet the low temperature processing requirements for plastic substrates.

As shown in fig. 3, curve 300 begins to rise at a voltage of about 800V, while curve 310 begins to rise at a voltage of about 1000V. In example 1 of plot 310, the breakdown voltage of the insulator layer is about 938V at a thickness of about 1.88 μm, and the dielectric constant of the insulator layer is about 2.94 at a test frequency of about 100kHz, as shown in table one. It is to be understood that the thickness in embodiment 1 is merely an example, and other thicknesses, for example, 2 μm to 12 μm, may be included according to different embodiments. Since the insulating layer of example 1 includes the fluorine-containing thiol compound and the silane coupling agent, the breakdown voltage of the insulating layer is increased, and the dielectric constant of the insulating layer is lowered.

(watch one)

Ink composition	Comparative example 1	Example 1
			Acrylic resin	10％	16％
Acrylic acid monomer	20％	20％
			Fluorine-containing thiol compound	NA	0.01％
Silane coupling agent	NA	0.5％
			Light curing agent	5％	5％
Solvent(s)	65％	58.49％
			Breakdown Voltage (@1.88 μm)	838V	983V
Dielectric constant (@100kHz)	4.46	2.94

The breakdown voltage can represent the electrical insulation property of the insulating layer, with a higher breakdown voltage having a higher electrical insulation effect and a thicker insulating layer having a higher breakdown voltage. In addition to breakdown voltage, dielectric constant is also commonly used to represent the electrical insulation property of an insulating layer, and an insulating layer having a smaller dielectric constant has a higher electrical insulation effect. In some embodiments, the insulating layer may have a breakdown voltage of greater than about 800V (e.g., greater than about 850V, greater than about 900V, greater than about 950V, or greater than about 1000V) at a thickness of about 2 μm (i.e., an insulating layer having a thickness of about 2 μm as specified in the specification for process tolerances, metrology errors, etc.), and a dielectric constant of the insulating layer at a frequency of about 100kHz may be in a range of about 2.0 to 5.0, and more particularly, may be in a range of about 2.0 to about 4.0 (e.g., about 2.5, about 3.0, or about 3.5).

Fig. 4 is a top view of a touch panel 400 according to some embodiments, wherein an insulating layer 430 is formed by an inkjet (spraying) process using the ink composition disclosed in the present disclosure. Fig. 5 is a cross-sectional view of the touch panel 400 according to the reference section a-a in fig. 4.

Referring to fig. 4 and 5, the touch panel 400 is a bridge type touch panel. In some embodiments, "single-sided" refers to a transparent conductive layer, such as an Indium Tin Oxide (ITO), a metal nanowire layer, or the like, fabricated on one side of a substrate. In some embodiments, the touch panel 400 may include a substrate 405, a first sensing electrode 410, a connection electrode 415, a second sensing electrode 420, an insulating layer 430, and a bridging wire 440. However, it should be understood that alternative embodiments of the touch panel 400, including other components, are also within the scope of the present disclosure.

Substrate 405 may comprise a flexible substrate or a rigid substrate similar to substrate 200 of FIG. 2A. The materials forming the first sensing electrode 410, the connection electrode 415, the second sensing electrode 420, and the bridging wire 440 may include indium tin oxide, a metal mesh, a metal nanowire, graphene, or other transparent conductors. The material forming the insulating layer 430 includes the ink composition provided by the present disclosure.

As used herein, "metal nanowires (metal nanowires)" is a collective term, a collection of metal wires comprising a plurality of elemental metals, metal alloys or metal compounds (including metal oxides), wherein the number of metal nanowires contained therein does not affect the scope of the present disclosure. At least one cross-sectional dimension (i.e., the diameter of the cross-section) of a single metal nanowire may be less than about 500nm, preferably less than about 100nm, and more preferably less than about 50 nm. The metal nanostructures, referred to herein as "wires", have a high aspect ratio, for example, between about 10 and 100000. more specifically, the aspect ratio (length: diameter of cross section) of the metal nanowires may be greater than about 10, preferably greater than about 50, and more preferably greater than about 100. The metal nanowires can be any metal including, but not limited to, silver, gold, copper, nickel, and gold-plated silver. Other terms such as silk (silk), fiber (fiber), tube (tube), etc., having the above dimensions and high aspect ratio are also within the scope of the present disclosure.

The metal nanowire may include a nano silver wire (silver nanowire), a nano gold wire (gold nanowire), or a nano copper wire (copper nanowire), etc. In some embodiments, a dispersion or slurry (ink) with metal nanowires is formed on the substrate 405 by a coating method, and dried to coat the metal nanowires on the surface of the substrate 405 to form a metal nanowire layer. After the drying (curing) step, the solvent and other substances in the slurry are volatilized, and the metal nanowires are randomly distributed on the surface of the substrate 405, and the metal nanowires can contact with each other to provide a continuous current path, thereby forming a conductive network (conductive network). Patterning of the metal nanowire layer is then performed to fabricate sensing circuits (e.g., the first sensing electrode 410, the connection electrode 415, the second sensing electrode 420, etc.).

In other embodiments, a film may be applied to form a composite structure with the metal nanowires to have certain specific chemical, mechanical, and optical properties, such as adhesion of the metal nanowires to the substrate 405, or better physical mechanical strength, so that the film may also be referred to as a matrix. In still other embodiments, the film layer is made of certain specific polymers to provide additional scratch and abrasion resistant surface protection to the metal nanowires, in which case the film layer may also be referred to as a hard coat or overcoat (over coat), and the use of materials such as polyacrylates, epoxies, polyurethanes, polysilanes, silicones, poly (silicon-acrylic acid), etc. may provide the metal nanowires with higher surface strength to improve scratch resistance. In addition, ultraviolet light stabilizers (UV stabilizers) can be added into the film layer to improve the ultraviolet resistance of the metal nanowires. However, the above is merely illustrative of other possibilities for additional functions or names of the film layers and is not intended to limit the present disclosure.

The first sensing electrodes 410 formed on the substrate 405 may have any shape and are arranged along the first direction D1. The adjacent first sensing electrodes 410 are electrically connected by a connection electrode 415. The second sensing electrodes 420 formed on the substrate 405 may have any shape and are arranged along the second direction D2. As shown in fig. 4, the first sensing electrodes 410 and the second sensing electrodes 420 are staggered in a top view, and vertical projections of the first sensing electrodes and the second sensing electrodes do not overlap.

An insulating layer 430 is then formed on the connection electrode 415. The insulating layer 430 may be formed using the ink composition and the method of forming the insulating layer provided in the present disclosure, i.e., the patterned insulating layer 430 is formed by a low temperature inkjet process. Due to the characteristics of the insulating layer 430, such as low temperature process and patterning without etching, damage to the substrate 405, the first sensing electrode 410, and the second sensing electrode 420 formed in advance can be avoided.

The insulating layer 430 may be adjusted to a suitable thickness according to the processes of the first and

second sensing electrodes

410 and 420. In some embodiments, the first and

second sensing electrodes

410 and 420 are made of ITO material, and the insulating layer 430 may have a thickness of about 2 μm. In other embodiments, the first sensing electrode 410 and the second sensing electrode 420 are made of nano silver wire material, and the thickness of the insulating layer 430 may be about 6 μm.

The bridge wire 440 is formed on the insulating layer 430 and electrically connected to the adjacent second sensing electrodes 420. Since the insulating layer 430 is located between the connection electrode 415 and the bridge wire 440, and the insulating layer 430 has a breakdown voltage and a dielectric constant as described above, the insulating layer 430 can electrically isolate the first sensing electrode 410 from the second sensing electrode 420.

The present disclosure discloses a method for forming an insulating layer, which directly forms a patterned insulating layer using a low temperature inkjet process to prevent material limitation or damage to other components caused by high temperature or lithography etching. The ink composition for forming the insulating layer includes an acrylic resin and an acrylic monomer, so that the viscosity of the ink composition is suitable for an ink jet device. The ink composition for forming the insulating layer includes a fluorine-containing thiol compound and a silane coupling agent, increases the breakdown voltage of the insulating layer and lowers the dielectric constant.

The method for forming the insulating layer disclosed by the disclosure can be applied to various electronic equipment manufacturing processes, such as forming a touch panel, a flexible panel, a large-size device and the like.

The foregoing outlines features of some embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. An ink composition for forming an insulating layer, comprising:

an acrylic resin;

an acrylic monomer;

a fluorine-containing thiol compound;

a silane coupling agent;

a light curing agent; and

a solvent, wherein the ink composition is used in an ink jet process.

2. The ink composition of claim 1, wherein the viscosity of the ink composition is 5 to 40 mPa-s at 25 ℃.

3. The ink composition of claim 1, wherein the acrylic resin is present in a concentration of 9 wt% to 33 wt% and the acrylic monomer is present in a concentration of 10 wt% to 30 wt%.

4. The ink composition of claim 1, wherein the concentration of the fluorine-containing thiol compound is about 0.001 wt% to about 0.1 wt%, and the concentration of the silane coupling agent is about 0.1 wt% to about 1 wt%.

5. A method of forming an insulating layer, comprising:

ink-jetting an ink composition on a substrate to form an ink layer, wherein the ink composition comprises:

an acrylic resin;

an acrylic monomer;

a fluorine-containing thiol compound;

a silane coupling agent;

a light curing agent; and

a solvent;

curing the ink layer at a low temperature; and

the ink layer is cured using ultraviolet light to form an insulating layer.

6. The method of claim 5, wherein the temperature for low temperature curing the ink layer is 50 ℃ to 130 ℃.

7. The method of claim 5, wherein the insulating layer has a dimensional shrinkage of less than 10% compared to the ink layer.

8. An insulating layer made by the method of claim 5.

9. The insulating layer of claim 8, wherein the breakdown voltage of the insulating layer at a thickness of 2 μm is greater than 800V.

10. The insulating layer of claim 8, wherein the insulating layer has a dielectric constant of 2.0 to 4.0 at a frequency of 100 kHz.

11. The insulating layer of claim 8, wherein the insulating layer has a thickness of 2 μm to 12 μm.

12. A touch panel comprising the insulating layer according to claim 8.

13. The touch panel according to claim 12, comprising:

a substrate;

a plurality of first sensing electrodes arranged on the substrate along a first direction;

a connecting electrode arranged on the substrate and electrically connected with the plurality of first sensing electrodes;

a plurality of second sensing electrodes disposed on the substrate along a second direction, wherein the second direction is different from the first direction, and vertical projections of the plurality of first sensing electrodes and the plurality of second sensing electrodes do not overlap;

the insulating layer is arranged on the connecting electrode; and

and the bridge lead is arranged on the insulating layer, wherein the bridge lead is electrically connected with the plurality of second induction electrodes, and the insulating layer electrically isolates the plurality of first induction electrodes and the plurality of second induction electrodes.

14. The touch panel of claim 13, wherein the first sensing electrodes, the connecting electrode and the second sensing electrodes comprise a layer of nano-silver wires.