WO2020177294A1

WO2020177294A1 - Transparent conductive film, touch screen, and preparation methods therefor

Info

Publication number: WO2020177294A1
Application number: PCT/CN2019/105611
Authority: WO
Inventors: 刘统辉; 黄梅峰
Original assignee: 南昌欧菲光科技有限公司
Priority date: 2019-03-06
Filing date: 2019-09-12
Publication date: 2020-09-10
Also published as: JP7202480B2; CN111665971A; KR20210118156A; KR102608549B1; JP2022523979A

Abstract

A transparent conductive film, comprising a substrate, a transition layer, a nano-conductive layer, and a metal layer. Both the nano-conductive layer and the metal layer have relative good flexibility, and thus can be applied to a foldable touch screen solution. Moreover, the transition layer and the nano-conductive layer partially overlap and are partially fused to form a mixed layer, thereby enhancing the adhesion between the nano-conductive layer and the transition layer, and therefore, the reliability of the transparent conductive film can be improved without providing an additional outer coating layer. Hence, when the transparent conductive film is used for preparing a touch screen, the metal layer and the nano-conductive layer can be etched and processed simultaneously, so that the preparation process of the touch screen can be significantly simplified, and the production efficiency is effectively improved. In addition, the present invention also provides a preparation method for the transparent conductive film, a touch screen, and a preparation method for the touch screen.

Description

Transparent conductive film, touch screen and preparation method thereof

Technical field

The invention relates to the technical field of capacitive touch control, in particular to a transparent conductive film, a touch screen and a preparation method thereof.

Background technique

The transparent conductive film is the core element of the capacitive touch screen, which generally includes a substrate layer, an ITO transparent conductive layer and a metal layer. With the continuous exploration of user needs, foldable touch solutions have emerged. Because ITO is hard and fragile, it is not suitable for bendable conductive material, so it is used in the conductive film of the foldable touch solution, and the ITO transparent conductive layer is replaced by a nano conductive layer.

The nano conductive layer has poor adhesion with the substrate due to structural limitations. Therefore, after the nano conductive layer is formed, it is necessary to coat the surface with an outer coating to enhance the adhesion. However, the outer coating cannot be etched by an acid etching solution. Therefore, when the conventional transparent conductive film is used to prepare a touch screen, the etching of the metal layer and the transparent conductive layer needs to be performed in two steps, which will complicate the processing technology of the touch screen and reduce the production efficiency.

Summary of the invention

According to various embodiments of the present application, a transparent conductive film, a touch screen, and a preparation method thereof are provided.

A transparent conductive film, including:

The substrate has two opposing surfaces; and

A transition layer, a nano conductive layer and a metal layer sequentially formed on at least one surface of the substrate, the transition layer and the nano conductive layer are respectively formed by curing a curing glue and a nano conductive material;

Wherein, the transition layer and the nano conductive layer partially overlap to form a mixed layer including part of the cured glue and part of the nano conductive material.

A method for preparing a transparent conductive film includes the steps:

Forming a nano conductive layer on the surface of the base film;

Coating curing glue on the side of the nano conductive layer facing away from the base film, and allowing the curing glue to partially penetrate and cure into the nano conductive layer to form a transition layer and a mixed layer;

Attaching the transition layer to the surface of the substrate, and removing the base film;

A metal layer is formed on the surface of the nano conductive layer facing away from the mixed layer.

A method for preparing a touch screen includes the steps:

To provide a transparent conductive film according to any one of the above preferred embodiments;

The metal layer and the nano-conductive layer are simultaneously etched using an exposure, development and etching process to form a metal lead pattern and a transparent lead pattern in the lead area, and a metal non-lead pattern and an electrode pattern in the touch area;

The metal non-lead pattern is etched by an exposure, development and etching process to expose the electrode pattern, and the metal lead pattern and the transparent lead pattern together form an electrode lead.

A touch screen, the touch screen is made by the method for manufacturing the touch screen described in the above preferred embodiment, the touch screen includes a touch area and a lead area, the touch area includes The electrode formed by the electrode pattern; the lead area includes a lead formed by a metal lead pattern and the transparent lead pattern.

The details of one or more embodiments of the present invention are set forth in the following drawings and description. Other features, objects and advantages of the present invention will become apparent from the description, drawings and claims.

Description of the drawings

FIG. 1 is a schematic diagram of the structure of a transparent conductive film in an embodiment of the present invention;

2 is a schematic diagram of the structure of a transparent conductive film in another embodiment of the present invention;

3 is a schematic flow chart of a method for preparing a transparent conductive film in an embodiment of the present invention;

4 is a schematic diagram of the structure of a touch screen in an embodiment of the present invention;

Figure 5 is a schematic structural diagram of a touch screen in another embodiment of the present invention

FIG. 6 is a schematic flow chart of a manufacturing method of a touch screen in an embodiment of the present invention;

FIG. 7 is a schematic diagram of an intermediate product structure of the manufacturing method of the touch screen shown in FIG. 6.

detailed description

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The drawings show preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or a central element may also exist. When an element is considered to be "connected" to another element, it can be directly connected to the other element or an intermediate element may be present at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "and/or" as used herein includes any and all combinations of one or more related listed items.

Referring to FIG. 1, the present invention provides a transparent conductive film 10. The transparent conductive film 10 includes a substrate 11, a transition layer 12, a nano conductive layer 13 and a metal layer 14.

The substrate 11 has two opposite surfaces, namely the upper surface and the lower surface shown in FIG. 1. Since the above-mentioned transparent conductive film 10 needs to be foldable, the base material 11 must also be formed of a material with better bending properties. Specifically, the substrate 11 may be PET (polyethylene terephthalate), PI (polyester imine), COP (polycyclic olefin), PEN (polyethylene naphthalate), PC ( Any one of organic polymer materials such as polycarbonate), PMMA (polymethyl methacrylate), or a mixture of any two or more.

The substrate 11 plays a supporting role. Specifically, in this embodiment, the thickness of the substrate 11 is 5 μm to 100 μm. In theory, the smaller the thickness of the base material 12 of the same material, the better the bending performance, but the lower the corresponding mechanical strength. When the thickness of the substrate 11 is less than 5 microns, its mechanical strength is not enough to play a supporting role; when the thickness of the substrate 11 is greater than 100 microns, its bending performance cannot meet the foldable requirements of the transparent conductive film 10 . Therefore, the substrate 11 with a thickness of 5 μm to 100 μm can have both bending performance and mechanical strength.

The transition layer 12, the nano conductive layer 13 and the metal layer 14 are sequentially formed on at least one surface of the substrate 11. The above-mentioned transparent conductive film 10 may be a single-sided conductive film or a double-sided conductive film to be applied to GF and GFF touch screen solutions respectively.

As shown in FIG. 1, in one embodiment, a transition layer 12, a nano conductive layer 13 and a metal layer 14 are formed on one surface of the substrate 11. At this time, the transparent conductive film 10 is a single-sided conductive film.

As shown in FIG. 2, in another embodiment, the transition layer 12, the nano conductive layer 13 and the metal layer 14 are formed on both surfaces of the substrate 11. At this time, the transparent conductive film 10 is a double-sided conductive film.

The transition layer 12 serves to connect the substrate 11 and the nano conductive layer 14, and its material has good affinity with the substrate 11 and the nano conductive layer 14. The transition layer 12 is formed by curing a curing glue. After curing, the pencil hardness of the transition layer 12 is required to be less than 1H.

Specifically, curing adhesives generally contain oligomers and curing catalysts. Among them, the oligomer can be acrylic acid, acrylate, acrylamide, methacrylate, methacrylic acid, urethane acrylate, methacrylamide, styrene, methyl styrene, polyurethane acrylate, polyamide Various epoxides such as imine acrylate, etc. or mixtures thereof; the curing catalyst can be a free radical catalyst, a cationic UV curing catalyst or a mixture thereof.

Specifically, in this embodiment, the thickness of the transition layer 12 is less than 10 microns. If the thickness of the transition layer 12 is too large, the flexibility of the transparent conductive film 10 will be reduced. At the same time, it will adversely affect the light transmittance of the transparent conductive film 10. Therefore, controlling the transition layer 12 to be less than 10 microns is beneficial to improve the light transmittance and flexibility of the transparent conductive film 10.

The nano conductive layer 13 is formed by curing nano conductive materials. The nano conductive layer 13 replaces the ITO layer in the traditional transparent conductive film, and is etched into a transparent electrode pattern when the touch screen is prepared. Among them, the nano-conductive material is in the form of nanotubes or nanoparticles, specifically metal nanotubes and nanoparticles such as silver, gold, copper, etc., or carbon nanotubes, ITO nanoparticles, and the like. After the conductive materials such as nanoparticles or nanotube structures are cured, a nano conductive layer 13 with gaps inside is formed. Compared with the traditional ITO layer, the bending performance of the nano conductive layer 13 is better.

In this embodiment, the thickness of the nano conductive layer 13 is 5 nm to 1000 nm. When the thickness of the nano conductive layer 13 is less than 5 nanometers, the reliability of its realization of conduction is not high; and when the thickness of the nano conductive layer 13 is greater than 1000 nanometers, its bending performance cannot meet the foldable properties of the transparent conductive film 10 demand. Therefore, the nano-conductive layer 13 with a thickness of 5 nm to 1000 nm can take into account bending performance and conductivity reliability.

Further, the transition layer 12 partially overlaps the nano conductive layer 13 to form a mixed layer 15 including part of the cured glue and part of the nano conductive material. As described above, after the nano conductive layer 13 is formed, there is a gap inside, so the cured glue forming the transition layer 12 can partially penetrate into the gap, so that the nano conductive layer 13 and the transition layer 12 are included with each other to obtain the mixed layer 15.

When preparing the transparent conductive film 10, the nano conductive layer 13 needs to be formed first, then curing glue is coated on the surface of the nano conductive layer 13 to make the transition layer 12, and finally the transition layer 12 and the nano conductive layer 13 are attached to the substrate 11. Due to the effect of the mixed layer, the adhesion between the nano conductive layer 13 and the transition layer 12 can be increased. On the one hand, the increased adhesion can improve the reliability of the transparent conductive film 10 described above. On the other hand, due to the pulling effect of the mixed layer 15, there is no need to provide an additional outer coating to enhance the adhesion of the nano conductive layer 13.

In this embodiment, the thickness of the mixed layer 15 is 1 nm to 5 nm. When the above-mentioned transparent conductive film 10 is prepared into a touch screen, since the mixed layer 15 contains curing glue, the pattern corresponding to the city cannot be etched. If the thickness of the mixed layer 15 is small, the amount of nano conductive material contained therein is small. When the thickness of the mixed layer 15 is less than 5 nanometers, the content of the nano-conductive material is extremely small, which is not enough to achieve conduction, thereby preventing the conductive pattern in the touch screen from forming a short circuit. Moreover, when the thickness of the mixed layer 15 is greater than 1 nanometer, it can better increase the adhesion between the nano-conductive layer 13 and the transition layer 12.

The metal layer 14 is attached to the side of the nano conductive layer 13 facing away from the transition layer 12. Specifically, the metal layer 14 may be formed by electroplating, vapor deposition, sputtering, spraying, or the like. The metal layer 14 is used to form electrode leads outside the touch input area when the transparent conductive film 10 is used in, for example, a touch panel. The material of the metal layer 14 is generally a metal or alloy with good conductivity, and representatively copper, silver, aluminum, nickel, molybdenum, and titanium. Of course, other metals with excellent conductivity can also be used.

Since both the nano conductive layer 13 and the metal layer 14 have better flexibility, the above-mentioned transparent conductive film 10 has better flexibility and can be applied to a foldable touch screen solution.

In addition, since the surface of the nano conductive layer 13 is not additionally provided with an overcoat layer. Therefore, the transparent conductive film 10 has good wet process capability. When the transparent conductive film 10 is used to prepare a touch screen, the metal layer 14 and the nano conductive layer 13 can be etched by an acidic etching solution at the same time, which can significantly simplify the preparation process of the touch screen and effectively improve the production efficiency .

In this embodiment, the thickness of the metal layer 14 is 100 nm to 1000 nm. When the thickness of the metal layer 14 is less than 100 nanometers, the reliability of conduction when it is etched into electrode leads is not high; and when the thickness of the metal layer 14 is greater than 1000 nanometers, its bending performance cannot meet the requirements of the transparent conductive film 10 The need for folding. Therefore, the metal layer 14 with a thickness of 100 nanometers to 1,000 nanometers can take into account both bending performance and electrical conductivity.

The above-mentioned transparent conductive film 10 can be applied to a foldable touch screen solution because both the nano conductive layer 13 and the metal layer 14 have better flexibility. Moreover, the transition layer 12 and the nano conductive layer 13 are partially overlapped and fused to form a mixed layer 15, thereby increasing the adhesion between the nano conductive layer 13 and the transition layer 12, thus improving the reliability of the transparent conductive film 10 At the same time, there is no need to provide an additional outer cover. Therefore, when the transparent conductive film 10 is used to prepare a touch screen, the metal layer 14 and the nano conductive layer 13 can be etched at the same time, which can significantly simplify the preparation process of the touch screen and effectively improve the production efficiency.

1 to 3 together, the present invention also provides a method for preparing a transparent conductive film. The transparent conductive film 10 can be prepared by the method for preparing the transparent conductive film. The preparation method of the transparent conductive film includes steps S210 to S240:

Step S210, forming a nano conductive layer 13 on the surface of the base film.

Specifically, conductive materials such as nanoparticles or nanotube structures can be coated on the surface of the base film first, and the nano conductive layer 13 can be formed after curing. The base film is an auxiliary material that plays a supporting role, and its material can be a polymer material. Generally, a material with poor affinity with the nano conductive layer 13 is selected for molding. In order to better bear the load and facilitate subsequent operations, the thickness of the base film is on the order of millimeters or more.

In step S220, the cured adhesive is applied to the side of the nano conductive layer 13 facing away from the base film, and the cured adhesive partially penetrates into the nano conductive layer 13 and cured to form the transition layer 12 and the mixed layer 15.

Specifically, by controlling the curing time and environmental parameters, it is possible to control only a part of the curing glue to penetrate into the nano conductive layer 13. Moreover, the partially cured adhesive only penetrates into a part of the depth of the nano conductive layer 13. Therefore, after the partially cured adhesive is cured, a mixed layer 15 containing nano conductive materials and cured adhesive can be obtained. The curing glue that has not penetrated into the nano conductive layer 13 is cured to obtain the transition layer 12. It should be pointed out that the curing of the cured adhesive in this step can be semi-cured or fully cured.

In one embodiment, the curing time and environmental parameters are controlled so that the penetration depth of the cured adhesive into the nano conductive layer 13 is 1 nanometer to 5 nanometers. Therefore, the thickness of the resulting mixed layer 15 is 1 nm to 5 nm.

In step S230, the transition layer 12 is attached to the surface of the substrate 11, and the base film is removed.

Specifically, the transition layer 12 can be attached to the surface of the substrate 11 by pressing, intermolecular force, gluing, or the like. If the curing adhesive is not fully cured during bonding, the curing adhesive itself can also be used to achieve bonding. At this time, the base film, the nano conductive layer 13, the mixed layer 15 and the transition layer 12 are combined with the base material 11 as a whole.

The base film is the middle supporting film layer, so it needs to be removed. After the base film is removed, the surface of the nano conductive layer 13 facing away from the mixed layer 15 can be exposed. Among them, the base film can be removed by tearing off. Moreover, a material that can be etched by a specific etching solution can be used to form the base film, so that the base film can be removed by etching. So far, the transition layer 12, the mixed layer 15 and the nano conductive layer 13 are formed on the substrate 11, which are sequentially stacked.

In one embodiment, the above step S230 includes: attaching the transition layer 12 to the surface of one side of the substrate 11. Therefore, the finally produced transparent conductive film is the single-sided conductive film shown in FIG. 1.

In another embodiment, the above step S230 includes: attaching the transition layer 12 to the surface of the substrate 11 on opposite sides. Therefore, the finally produced transparent conductive film is the double-sided conductive film shown in FIG. 2.

In step S230, a metal layer 14 is formed on the surface of the nano conductive layer 13 facing away from the mixed layer 15.

As mentioned above, the metal layer 14 can be formed by electroplating, evaporation, sputtering, spraying, etc., so as to obtain a complete transparent conductive film 10.

The method for preparing the transparent conductive film described above adopts a base film as an intermediate supporting film layer. Therefore, the nano conductive layer 13 can be formed first, and then the transition layer 12 can be formed, so as to realize the preparation of the mixed layer 15. The above-mentioned transparent conductive film 10 can be obtained by adopting the above-mentioned preparation method of the transparent conductive film.

Please refer to FIG. 4, the present invention also provides a touch screen 20, which is made of the transparent conductive film 10 in the above embodiment. among them:

The touch screen 20 includes a touch area 21 and a lead area 22. Specifically, the touch area 21 is located in the middle of the touch screen 20, and the lead area 22 is arranged around the circumference of the touch area 21. The metal layer 14 is located in the lead area 22.

The touch area 21 includes an electrode 211, which is formed by etching the nano conductive layer 13. That is, the electrode 211 is an electrode pattern etched from the nano conductive layer 13. Specifically, the electrode patterns are generally elongated and intersect vertically to form a grid.

The lead area 22 includes leads 221. Wherein, the lead 221 is formed by etching the metal layer 14 and the nano conductive layer 13 in the lead region 22. The lead 221 has a double-layer structure, thereby achieving electrical connection with the electrode 211.

FIG. 4 shows a touch screen made of a single-layer transparent conductive film 10, that is, the GF touch screen structure. FIG. 5 shows a touch screen made of a double-layer transparent conductive film 10, that is, a GFF touch screen structure. For the double-layer touch screen 20, electrodes 211 and leads 221 are formed on opposite sides thereof.

The aforementioned touch screen 20 can be folded because the transparent conductive film 10 has better flexibility. Moreover, due to the presence of the mixed layer 15, the adhesion between the electrode 211 and the transition layer 12 is increased, so the reliability of the touch screen 20 can be improved. Moreover, the preparation of the lead 221 does not require an additional space for the alignment deviation with the nano conductive layer 13, so an extremely narrow frame of the touch screen 20 can also be realized.

Please refer to FIG. 6 and FIG. 7 together. The present invention also provides a method for manufacturing a touch screen. The method includes steps S310 to S330:

Step S310: Provide a transparent conductive film.

Specifically, the transparent conductive film is the transparent conductive film 10 in the above embodiment, which includes a substrate 11, a transition layer 12, a mixed layer 15, a nano conductive layer 13, and a metal layer 14 that are stacked.

Step S320: The metal layer 14 and the nano conductive layer 13 are simultaneously etched by the exposure, development and etching process to form the metal lead pattern 141 and the transparent lead pattern 131 in the lead area, and the metal non-lead pattern 142 and the electrode pattern 132 in the touch area .

Specifically, the transparent conductive film 10 may be a single-sided conductive film or a double-sided conductive film. The steps of the exposure, development and etching process are: coating photoresist or attaching a dry film-exposure-development and etching. Single-sided conductive film can be exposed by a single-sided exposure machine, and double-sided conductive film can be exposed by a double-sided exposure machine. The etching solution can simultaneously etch the metal layer 14 and the nano conductive layer 13, and since there is no overcoat on the surface of the nano conductive layer 13, the metal layer 14 and the nano conductive layer 13 can be etched at the same time.

As shown in FIG. 5, after the metal layer 14 is etched, a metal lead pattern 141 located in the lead area and a metal non-lead pattern 142 located in the touch area are obtained. After the nano conductive layer 13 is etched, a transparent lead pattern 131 and located in the lead area are obtained. The electrode pattern 132 located in the touch area.

Step S320: the metal non-lead pattern 142 is etched by an exposure, development and etching process to expose the electrode pattern 132, and the metal lead pattern 141 and the transparent lead pattern 131 together form an electrode lead.

Specifically, the process of the second exposure, development and etching is exactly the same as that of the first exposure, development and etching, and the difference lies in the shape of the photoresist or dry film. The secondary exposure, development and etching are used to remove the metal non-lead pattern 142, and the exposed electrode pattern 132 constitutes the electrode 211 shown in FIG. 4. The electrode lead is the lead 221 shown in FIG. 4.

In the above-mentioned preparation method of the touch screen, the metal layer 14 and the nano conductive layer 13 can be simultaneously etched by the first exposure, development and etching, and the finished touch screen can be obtained by two exposures, development and etching. It can be seen that the above-mentioned preparation method of the touch screen effectively improves the production efficiency of the touch screen.

The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, All should be considered as the scope of this specification.

The above-mentioned embodiments only express several embodiments of the present invention, and the descriptions are more specific and detailed, but they should not be understood as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A transparent conductive film, characterized by comprising:

The substrate has two opposing surfaces; and

A transition layer, a nano conductive layer and a metal layer sequentially formed on at least one surface of the substrate, the transition layer and the nano conductive layer are respectively formed by curing a curing glue and a nano conductive material;

Wherein, the transition layer and the nano conductive layer partially overlap to form a mixed layer including part of the cured glue and part of the nano conductive material.
The transparent conductive film according to claim 1, wherein the thickness of the substrate is 5 μm to 100 μm.
The transparent conductive film according to claim 1, wherein the thickness of the transition layer is less than 10 microns.
The transparent conductive film according to claim 1, wherein the thickness of the nano conductive layer is 5 nm to 1000 nm.
The transparent conductive film according to claim 1, wherein the thickness of the mixed layer is 1 nanometer to 5 nanometers.
The transparent conductive film according to claim 1, wherein the thickness of the metal layer is 100 nm to 1000 nm.
The transparent conductive film according to claim 1, wherein the transition layer, the nano conductive layer, and the metal layer are formed on one surface of the substrate.
The transparent conductive film according to claim 1, wherein the transition layer, the nano conductive layer, and the metal layer are formed on both surfaces of the substrate.
A method for preparing a transparent conductive film is characterized in that it comprises the steps:

Forming a nano conductive layer on the surface of the base film;

Coating curing glue on the side of the nano conductive layer facing away from the base film, and allowing the curing glue to partially penetrate and cure into the nano conductive layer to form a transition layer and a mixed layer;

Attaching the transition layer to the surface of the substrate, and removing the base film;

A metal layer is formed on the surface of the nano conductive layer facing away from the mixed layer.
The method for preparing a transparent conductive film according to claim 9, wherein the side of the nano conductive layer facing away from the base film is coated with a curing glue, and the curing glue is partially penetrated and The step of curing into the nano conductive layer to form a transition layer and a mixed layer includes:

By controlling the curing time and environmental parameters, the penetration depth of the cured adhesive into the nano conductive layer is 1 nanometer to 5 nanometers.
The method for preparing a transparent conductive film according to claim 9, wherein the step of attaching the transition layer to the surface of the substrate and removing the base film comprises:

The transition layer is attached to the surface of one side of the substrate.
The method for preparing a transparent conductive film according to claim 9, wherein the step of attaching the transition layer to the surface of the substrate and removing the base film comprises:

The transition layer is attached to the surfaces on opposite sides of the substrate.
A method for preparing a touch screen is characterized by comprising the steps:

To provide a transparent conductive film according to any one of claims 1 to 8;

The metal layer and the nano-conductive layer are simultaneously etched using an exposure, development and etching process to form a metal lead pattern and a transparent lead pattern in the lead area, and a metal non-lead pattern and an electrode pattern in the touch area;

The metal non-lead pattern is etched by an exposure, development and etching process to expose the electrode pattern, and the metal lead pattern and the transparent lead pattern together form an electrode lead.
A touch screen, characterized in that, the touch screen is made of the method for manufacturing the touch screen according to claim 13, the touch screen includes a touch area and a lead area, the touch The area includes an electrode composed of the electrode pattern; the lead area includes a lead composed of the metal lead pattern and the transparent lead pattern.