JP7114446B2 - Conductive film and patterning method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conductive film and its patterning method, and more particularly to a conductive film suitable for optical applications and its patterning method.

BACKGROUND ART Conventionally, it is known that a transparent conductive film having a transparent conductive layer is used for optical applications such as touch panels.

For example, a transparent conductive film comprising a transparent substrate and a light-transmitting inorganic layer, wherein the light-transmitting inorganic layer comprises a first inorganic oxide layer, a metal layer, and a second inorganic oxide layer in this order. (See, for example, Patent Document 1).

In the transparent conductive film of Patent Document 1, for example, a metal layer such as a silver layer serves as a conductive layer. known to perform.

On the other hand, in the transparent conductive film, a conductive film with a copper layer was proposed, in which a copper layer is laminated on the upper surface of the transparent conductive layer in order to form routing wiring on the outer edge of the touch input area and achieve a narrower frame. It is In such a conductive film with a copper layer, the copper layer is easily oxidized and the conductivity changes over time, so there is a problem that the conductivity such as surface resistance (sheet resistance) varies in plan view after a long period of time. occurs. Therefore, it is known to arrange a metal layer such as a copper-nickel alloy on the copper layer to suppress natural oxidation of the copper layer (see, for example, Patent Document 2).

In the conductive film with a copper layer of Patent Document 2, the copper layer and the transparent conductive film are patterned in order to form the lead wiring of the frame portion from the copper layer, and the electrode pattern of the touch panel portion is formed from the transparent conductive film. Form.

JP 2016-155377 A Japanese Unexamined Patent Application Publication No. 2013-1009

By the way, in order to meet various needs in recent years, for a low-resistance transparent conductive film represented by Patent Document 1, in order to achieve a narrow frame and stability of the frame (copper layer), the transparent conductive layer It is contemplated to place additional copper and copper-nickel layers on the top surface.

In this case, since it is necessary to pattern the copper-nickel layer together with the copper layer, it is necessary to use a strong acidic etchant. Then, there arises a problem of reaching the metal layer (silver layer) of the transparent conductive layer and damaging the metal layer. As a result, the metal layer may not be able to form a desired electrode pattern or achieve a desired surface resistance.

The present invention provides a conductive film and a method for patterning the same, which have excellent stability of the copper layer, can easily pattern the copper layer, and can suppress damage to the metal layer in the transparent conductive layer.

The present invention [1] provides a transparent base material, a transparent conductive layer arranged on one side in a thickness direction of the transparent base material and comprising in order a first inorganic oxide layer, a metal layer and a second inorganic oxide layer; A conductive film comprising a copper layer arranged on one side in the thickness direction of a transparent conductive layer and a copper oxide layer arranged on one side in the thickness direction of the copper layer.

The present invention [2] includes the conductive film according to [1], wherein the copper oxide layer has a thickness of 13 nm or less.

The present invention [3] includes the conductive film according to [1] or [2], wherein the copper layer and the copper oxide layer are patterned.

The present invention [4] is a process of preparing the conductive film according to [1] or [2], and bringing a neutral etchant into contact with one surface in the thickness direction of the conductive film, thereby the copper oxide layer and patterning the copper layer.

According to the conductive film of the present invention, since it has a transparent conductive layer having the first inorganic oxide layer, the metal layer and the second inorganic oxide layer in this order, it has excellent conductivity.

According to the conductive film of the present invention, since the copper oxide layer is arranged on one side in the thickness direction of the copper layer, natural oxidation of the copper layer is suppressed and the stability of the copper layer is excellent.

According to the conductive film of the present invention, since the copper oxide layer is provided, the copper oxide layer and the copper layer can be easily etched with a neutral etchant. In addition, since the inorganic oxide layer arranged on the other side in the thickness direction of the copper layer is difficult to etch with a neutral etchant, damage to the metal layer in the transparent conductive layer can be suppressed.

According to the patterning method of the present invention, the copper oxide layer and the copper layer are patterned by bringing the conductive film into contact with the neutral etchant. Etching can be suppressed. Therefore, damage to the metal layer in the transparent conductive layer can be suppressed.

FIG. 1 shows a cross-sectional view of one embodiment of the conductive film of the present invention. 2A-F show process diagrams of the patterning method of the conductive film shown in FIG. 1, FIG. 2A is a step of placing a dry film resist, FIG. 2B is a step of etching a copper oxide layer and a copper layer, FIG. 2C is a step of removing the dry film resist, FIG. 2D is a step of placing the dry film resist, FIG. 2E is a step of etching the transparent conductive layer, and FIG. 2F is a step of obtaining a patterned conductive film.

A conductive film 1 that is an embodiment of the present invention will be described with reference to FIG.

In FIG. 1, the vertical direction of the paper is the vertical direction (thickness direction, first direction), the upper side of the paper is the upper side (one side in the thickness direction, the one side of the first direction), and the lower side of the paper is the lower side (thickness direction). the other side, the other side in the first direction). Moreover, the left-right direction and the depth direction on the paper surface are plane directions orthogonal to the up-down direction. Specifically, it conforms to the directional arrows in each figure. Specifically, it conforms to the directional arrows in each figure.

1. Conductive transparent film The conductive film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in a plane direction perpendicular to the thickness direction, and has a flat upper surface (one surface in the thickness direction) and a flat lower surface ( thickness direction other surface). The conductive film 1 is, for example, a component such as a substrate for a touch panel provided in an optical device (for example, an image display device), that is, it is not an optical device. That is, the conductive film 1 is a component for producing an optical device or the like, does not include an image display element such as an LCD module or a light source such as an LED, and is a device that can be distributed independently and can be used industrially. .

Specifically, as shown in FIG. 1, the conductive film 1 of the first embodiment is a conductive film that includes a transparent substrate 2, a transparent conductive layer 3, a copper layer 4, and a copper oxide layer 5 in this order. It's a film. That is, the conductive film 1 includes a transparent substrate 2, a transparent conductive layer 3 arranged on the upper side of the transparent substrate 2, a copper layer 4 arranged on the transparent conductive layer 3, and an upper side of the copper layer 4. and a copper oxide layer 5 disposed on the . Preferably, the conductive film 1 consists of the transparent substrate 2, the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5 only. Each layer will be described in detail below.

2. Transparent Base Material A support material that secures the mechanical strength of the conductive film 1 . That is, the transparent substrate 2 supports the transparent conductive layer 3 , the copper layer 4 and the copper oxide layer 5 .

The transparent substrate 2 has a film shape and is the bottom layer of the conductive film 1 .

The transparent substrate 2 is, for example, a polymer film having transparency. Polymer film materials include, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; (meth)acrylic resins (acrylic resins and/or methacrylic resins) such as polymethacrylate; Olefin resins such as polypropylene, cycloolefin polymers (e.g., polymers of norbornenes, cyclopentadienes, cyclohexadienes, etc.), e.g., polycarbonate resins, polyethersulfone resins, polyarylate resins, melamine resins, polyamide resins, polyimide resins , cellulose resins, polystyrene resins, and the like. Polymer films can be used singly or in combination of two or more.

From the viewpoint of transparency, heat resistance, mechanical strength, etc., polyester resins are preferred, and polyethylene terephthalate is more preferred.

The total light transmittance (JIS K 7375-2008) of the transparent substrate 2 is, for example, 80% or more, preferably 85% or more.

The thickness of the transparent substrate 2 is, for example, 2 μm or more, preferably 20 μm or more, from the viewpoint of mechanical strength, transparency, and spotting characteristics when the conductive film 1 is used as a touch panel film. , 300 μm or less, preferably 150 μm or less.

The thickness of the transparent substrate 2 can be measured using, for example, a film thickness gauge (digital dial gauge).

An easy-adhesion layer, an adhesive layer, a separator, or the like may be arranged on the upper surface and/or the lower surface of the transparent base material 2, if necessary.

3. Transparent Conductive Layer The transparent conductive layer 3 is a conductive layer that is formed into a desired pattern (patterned transparent conductive layer 3A described later) in a second patterning step described later, and becomes, for example, an electrode pattern in a touch input area of a touch panel.

The transparent conductive layer 3 has a film shape and is arranged on the entire upper surface of the transparent base material 2 so as to be in contact with the upper surface of the transparent base material 2 . More specifically, the transparent conductive layer 3 is arranged between the transparent substrate 2 and the copper layer 4 so as to be in contact with the upper surface of the transparent substrate 2 and the lower surface of the copper layer 4 .

The transparent conductive layer 3 comprises a first inorganic oxide layer 6, a metal layer 7 and a second inorganic oxide layer 8 in order. That is, the transparent conductive layer 3 comprises a first inorganic oxide layer 6 arranged on the upper surface of the transparent substrate 2, a metal layer 7 arranged on the upper surface of the first inorganic oxide layer 6, and an upper surface of the metal layer 7. and a second inorganic oxide layer 8 disposed on the Preferably, the transparent conductive layer 3 consists of only the first inorganic oxide layer 6 , the metal layer 7 and the second inorganic oxide layer 8 .

The surface resistance of the upper surface of the transparent conductive layer 3 is, for example, 10Ω/square or less, preferably 5Ω/square or less, and is, for example, 0.1Ω/square or more.

The total light transmittance (JIS K 7375-2008) of the transparent conductive layer 3 is, for example, 60% or more, preferably 85% or more.

The average reflectance of the transparent conductive layer 3 for near infrared rays (wavelength 850 to 2500 nm) is, for example, 10% or more, preferably 50% or more, and is, for example, 95% or less.

The total thickness of the transparent conductive layer 3 (that is, the total thickness of the first inorganic oxide layer 6, the metal layer 7 and the second inorganic oxide layer 8) is, for example, 20 nm or more, preferably 40 nm or more, and For example, it is 150 nm or less, preferably 100 nm or less. The total thickness of the transparent conductive layer 3 and the thickness of each layer can be measured by cross-sectional observation using a transmission electron microscope (TEM), for example. The first inorganic oxide layer 6, the metal layer 7 and the second inorganic oxide layer 8 are described in detail below.

4. First Inorganic Oxide Layer The first inorganic oxide layer 6 is a barrier layer that suppresses penetration of hydrogen and carbon elements derived from the transparent substrate 2 into the metal layer 7 . In addition, the first inorganic oxide layer 6 suppresses the visible light reflectance of the metal layer 7 and improves the visible light transmittance (transparency) of the transparent conductive layer 3 together with the second inorganic oxide layer 8. Also a layer. Moreover, preferably, the first inorganic oxide layer 6 is a conductive layer that imparts conductivity to the transparent conductive layer 3 together with the metal layer 7, and more preferably a transparent conductive layer.

The first inorganic oxide layer 6 has a film shape and is the lowest layer in the transparent conductive layer 3 . More specifically, the first inorganic oxide layer 6 is arranged over the entire upper surface of the transparent substrate 2 so as to be in contact with the upper surface of the transparent substrate 2 .

Examples of inorganic oxides forming the first inorganic oxide layer 6 include In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, W, Fe, Metal oxides formed from at least one metal selected from the group consisting of Pb, Ni, Nb, and Cr are included. The metal oxides can be further doped with metal atoms shown in the above groups, if desired.

Inorganic oxides preferably include oxides containing indium oxide (indium oxide-containing oxides) from the viewpoint of reducing surface resistance and ensuring excellent transparency.

The indium oxide-containing oxide may contain only indium (In) as a metal element, or may contain (semi)metal elements other than indium (In). The indium oxide-containing oxide preferably has indium (In) as the main metal element. The indium oxide-containing oxide whose main metal element is indium has an excellent barrier function and tends to favorably suppress corrosion of the metal layer 7 due to the influence of water or the like.

Specific examples of indium oxide-containing oxides include indium zinc composite oxide (IZO), indium gallium composite oxide (IGO), indium gallium zinc composite oxide (IGZO), indium tin composite oxide (ITO ), more preferably indium tin composite oxide (ITO). “ITO” in this specification may be a composite oxide containing at least indium (In) and tin (Sn), and may contain additional components other than these. Examples of additional components include metal elements other than In and Sn, such as metal elements shown in the above groups and combinations thereof. The content of the additional component is, for example, 5% by mass or less.

The content of tin oxide (SnO ₂ ) contained in ITO is, for example, 0.5% by mass or more, preferably 3% by mass or more, with respect to the total amount of tin oxide and indium oxide (In ₂ O ₃ ). , more preferably 10% by mass or more, and for example, 35% by mass or less, preferably 20% by mass or less, and more preferably 15% by mass or less. The content of indium oxide (In ₂ O ₃ ) is the remainder of the content of tin oxide (SnO ₂ ). If the content of tin oxide (SnO ₂ ) contained in ITO is within the above range, the crystallinity of the ITO film can be easily adjusted.

The first inorganic oxide layer 6 may be either crystalline or amorphous.

The thickness of the first inorganic oxide layer 6 is, for example, 5 nm or more, preferably 20 nm or more, and is, for example, 100 nm or less, preferably 50 nm or less. If the thickness of the first inorganic oxide layer 6 is within the above range, it is easy to adjust the visible light transmittance of the transparent conductive layer 3 to a high level.

5. Metal Layer The metal layer 7 is a conductive layer that imparts conductivity to the transparent conductive layer 3 together with the first inorganic oxide layer 6 and the second inorganic oxide layer 8 . Moreover, the metal layer 7 is also a low resistance layer that reduces the surface resistance of the transparent conductive layer 3 . Moreover, preferably, the metal layer 7 is also an infrared reflective layer that provides a high infrared reflectance.

The metal layer 7 has a film shape and is arranged on the upper surface of the first inorganic oxide layer 6 so as to be in contact with the upper surface of the first inorganic oxide layer 6 . More specifically, between the first inorganic oxide layer 6 and the second inorganic oxide layer 8 , the metal layer 7 is formed between the upper surface of the first inorganic oxide layer 6 and the lower surface of the second inorganic oxide layer 8 . positioned so as to come into contact with

The metal forming the metal layer 7 is not limited as long as it has a low surface resistance. consisting of one metal selected from the group consisting of Pb, Pd, Pt, Cu, Ge, Ru, Nd, Mg, Ca, Na, W, Zr, Ta and Hf, or two or more thereof Alloys containing metals are included.

As the metal, silver (Ag) and silver alloys are preferably used. If the metal is silver or a silver alloy, the resistance value of the transparent conductive layer 3 can be reduced, and in addition, the transparent conductive layer 3 has a particularly high average reflectance in the near-infrared region (wavelength 850 to 2500 nm). It can be suitably applied to image display devices used outdoors.

A silver alloy contains silver as a main component and other metals as subcomponents. The metal element of the subcomponent is not limited. Silver alloys include, for example, Ag—Cu alloy, Ag—Pd alloy, Ag—Pd—Cu alloy, Ag—Pd—Cu—Ge alloy, Ag—Cu—Au alloy, Ag—Cu—In alloy, Ag—Cu -Sn alloy, Ag-Ru-Cu alloy, Ag-Ru-Au alloy, Ag-Nd alloy, Ag-Mg alloy, Ag-Ca alloy, Ag-Na alloy, Ag-Ni alloy, Ag-Ti alloy, Ag- In alloys, Ag—Sn alloys, and the like are included. From the viewpoint of wet heat durability, silver alloys preferably include Ag--Cu alloys, Ag--Cu--In alloys, Ag--Cu--Sn alloys, Ag--Pd alloys and Ag--Pd--Cu alloys.

The content of silver in the silver alloy is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and is, for example, 99.9% by mass or less. The content of other metals in the silver alloy is the balance of the silver content described above.

From the viewpoint of improving the transmittance of the transparent conductive layer 3, the thickness of the metal layer 7 is, for example, 1 nm or more, preferably 5 nm or more, and is, for example, 20 nm or less, preferably 10 nm or less.

6. Second Inorganic Oxide Layer The second inorganic oxide layer 8 is a barrier layer that prevents external oxygen, moisture, and the like from entering the metal layer 7 . The second inorganic oxide layer 8 is also an optical adjustment layer that suppresses the visible light reflectance of the metal layer 7 and improves the visible light transmittance of the transparent conductive layer 3 together with the first inorganic oxide layer 6 . Moreover, preferably, the second inorganic oxide layer 8 is a conductive layer that imparts conductivity to the transparent conductive layer 3 together with the metal layer 7, and more preferably is a transparent conductive layer.

The second inorganic oxide layer 8 has a film shape and is the uppermost layer in the transparent conductive layer 3 . More specifically, the second inorganic oxide layer 8 is arranged on the entire upper surface of the metal layer 7 so as to be in contact with the upper surface of the metal layer 7 .

Inorganic oxides forming the second inorganic oxide layer 8 include the inorganic oxides exemplified for the first inorganic oxide layer 6, preferably indium oxide-containing oxides, and more preferably ITO. mentioned.

The inorganic oxide forming the second inorganic oxide layer 8 may be the same as or different from the inorganic oxide forming the first inorganic oxide layer 6, but from the viewpoint of patterning properties, preferably the first inorganic oxide It is the same inorganic oxide as the oxide layer 6 .

When the second inorganic oxide layer 8 is made of ITO, the content of tin oxide (SnO ₂ ) contained in ITO is the same as that of the first inorganic oxide layer 6 .

The second inorganic oxide layer 8 may be either crystalline or amorphous.

The thickness of the second inorganic oxide layer 8 is, for example, 5 nm or more, preferably 20 nm or more, and is, for example, 100 nm or less, preferably 50 nm or less. If the thickness of the second inorganic oxide layer 8 is within the above range, it is easy to adjust the visible light transmittance of the transparent conductive layer 3 to a high level.

The ratio of the thickness of the second inorganic oxide layer 8 to the thickness of the first inorganic oxide layer 6 (second/first) is, for example, 0.5 or more, preferably 0.75 or more. It is 1.5 or less, preferably 1.25 or less. If the said ratio is in the above-mentioned range, deterioration of the metal layer 7 can be suppressed further.

The ratio of the thickness of the second inorganic oxide layer 8 to the thickness of the metal layer 7 (second inorganic oxide layer/metal layer) is, for example, 2.0 or more, preferably 3.0 or more, and For example, it is 10 or less, preferably 8.0 or less.

7. Copper Layer The copper layer 4 is formed into a desired pattern (patterned copper layer 4A described later) in a first patterning step described later, and is used, for example, as wiring in the outer edge portion (peripheral edge portion) of the outside (periphery) of the touch input area. It is a conductive layer that becomes a pattern (for example, routing wiring).

The copper layer 4 has a film shape and is arranged on the entire upper surface of the transparent conductive layer 3 so as to be in contact with the upper surface of the transparent conductive layer 3 . More specifically, the copper layer 4 is arranged between the transparent conductive layer 3 and the copper oxide layer 5 so as to be in contact with the upper surface of the transparent conductive layer 3 and the lower surface of the copper oxide layer 5 .

Examples of materials for the copper layer 4 include copper and copper alloys. Metals constituting the copper alloy are not limited, and examples thereof include silver, tin, chromium, and zirconium. Copper is preferred from the viewpoint of conductivity and the like.

The thickness of the copper layer 4 is, for example, 100 nm or more, preferably 150 nm or more, and for example, 400 nm or less, preferably 300 nm or less. If the thickness of the metal layer 7 is at least the above lower limit, the conductivity of the copper layer 4 is excellent. Therefore, it is possible to form a narrower and longer wiring pattern (copper wiring for the frame portion) in response to an increase in the size of the touch panel. If the thickness of the copper layer 4 is equal to or less than the above upper limit, the thickness of the frame portion can be reduced.

The thickness of the copper layer 4 can be measured by cross-sectional observation using a transmission electron microscope (TEM), for example.

8. Copper Oxide Layer The copper oxide layer 5 is a protective layer that suppresses a decrease in conductivity due to natural oxidation of the copper layer 4 . In addition, along with the copper layer 4, it is formed in a desired pattern (patterned copper oxide layer 5A described later), for example, a wiring pattern (for example, routing wiring ).

The copper oxide layer 5 has a film shape and is the uppermost layer of the conductive film 1 . More specifically, the copper oxide layer 5 is arranged over the entire upper surface of the copper layer 4 so as to be in contact with the upper surface of the copper layer 4 .

The material of the copper oxide layer 5 is an oxide of copper or a copper alloy. Metals constituting the copper alloy are not limited, and examples thereof include silver, tin, chromium, and zirconium. From the viewpoint of electrical conductivity, copper oxide is preferred.

The thickness of the copper oxide layer 5 is, for example, 1 nm or more, preferably 3 nm or more, and is, for example, 30 nm or less, preferably 13 nm or less, more preferably 8 nm or less, and still more preferably 6 nm or less. If the thickness of the copper oxide layer 5 is within the above range, it is possible to further suppress changes in surface resistance over time (natural oxidation) on the upper surface of the conductive film 1 (copper oxide layer 5 and copper layer 4). It is possible to further reduce variations in surface resistance.

The ratio of the thickness of the copper oxide layer 5 to the thickness of the copper layer 4 (copper oxide layer 5/copper layer 4) is, for example, 1/100 or more, preferably 2/100 or more, and is, for example, 15/100. Below, it is preferably 7/100 or less, more preferably 5/100 or less, and still more preferably 3/100 or less. If the above ratio is within the range, variations in surface resistance can be further reduced.

The thickness of the copper oxide layer 5 can be measured using, for example, a scanning fluorescent X-ray analyzer.

9. Method for Manufacturing Conductive Film Next, a method for manufacturing the conductive film 1 will be described. The manufacturing method of the conductive film 1 includes, for example, a step of sequentially arranging (laminating) a transparent conductive layer 3 , a copper layer 4 and a copper oxide layer 5 on a transparent substrate 2 .

In this method, first, a transparent substrate 2 is prepared. A known or commercially available transparent base material 2 can be used.

A transparent conductive layer 3 is then placed on top of the transparent substrate 2 . For example, the first inorganic oxide layer 6, the metal layer 7 and the second inorganic oxide layer 8 are arranged in order on the upper surface of the transparent substrate 2 by a dry method.

Dry methods include, for example, a vacuum deposition method, a sputtering method, an ion plating method, and the like. Sputtering is preferred.

Gases used in the sputtering method include, for example, inert gases such as Ar. In addition, a reactive gas such as oxygen can be used together as necessary. When a reactive gas is used in combination, the volume ratio of the reactive gas flow rate to the inert gas flow rate (reactive gas/inert gas) is, for example, 0.1/100 or more, preferably 1/100 or more. , or, for example, 5/100 or less.

Specifically, in the formation of the first inorganic oxide layer 6, an inert gas and a reactive gas are preferably used together as the gas. An inert gas is preferably used alone as the gas in forming the metal layer 7 . In forming the second inorganic oxide layer 8, as the gas, an inert gas and a reactive gas are preferably used together.

When the sputtering method is employed, the target material includes the above inorganic oxides or metals constituting each layer.

The power source used in the sputtering method includes, for example, DC power source, MF/AC power source and RF power source used alone or in combination, preferably DC power source.

As a result, the first inorganic oxide layer 6 , the metal layer 7 and the second inorganic oxide layer 8 are formed on the upper surface of the transparent substrate 2 in this order.

Heating may be performed to crystallize the first inorganic oxide layer 6 and/or the second inorganic oxide layer 8, if desired.

The heating temperature is, for example, 80° C. or higher and 180° C. or lower, and the heating time is, for example, 10 minutes or longer and 5 hours or shorter. Heating may be carried out under an air atmosphere, an inert atmosphere, or under vacuum.

A copper layer 4 is then placed on top of the transparent conductive layer 3 . For example, a copper layer 4 is formed on the upper surface of the transparent conductive layer 3 by a dry method.

Examples of the dry method include those described above for forming the transparent conductive layer 3, preferably sputtering. By this method, a copper layer 4 having a uniform thickness can be formed even if it is a thick film.

The conditions of the sputtering method for the copper layer 4 are also the same as the conditions exemplified for the formation of the transparent conductive layer 3 . Preferably, in forming the copper layer 4, an inert gas is used alone as the gas. Moreover, the target material preferably includes oxygen-free copper.

A copper oxide layer 5 is then placed on top of the copper layer 4 . For example, a copper oxide layer 5 is formed on the upper surface of the copper layer 4 by a dry method.

Examples of the dry method include those described above for forming the transparent conductive layer 3, preferably sputtering. By this method, a copper oxide layer 5 having a uniform thickness can be formed on the upper surface of the copper layer 4 with good adhesion.

The sputtering conditions for the copper oxide layer 5 are also the same as those exemplified for the formation of the transparent conductive layer 3 . Preferably, in forming the copper oxide layer 5, an inert gas is used alone, or an inert gas and a reactive gas (specifically, oxygen) are used in combination. Moreover, the target material preferably includes copper oxide (CuO).

Thus, a conductive film 1 comprising a transparent base material 2, a transparent conductive layer 3, a copper layer 4, and a copper oxide layer 5 is obtained as shown in FIG. This conductive film 1 is a transparent conductive film with a copper layer.

In addition, the above-described manufacturing method can be implemented by a roll-to-roll method. Also, part or all of it can be carried out in batch mode.

10. Patterning Method for Conductive Film Next, a method for patterning the conductive film 1 will be described. The patterning method for the conductive film 1 includes, for example, a first etching process and a second etching process in order.

In the first etching step, the copper oxide layer 5 and the copper layer 4 are etched. That is, the upper surface (one surface in the thickness direction) of the conductive film 1, that is, the upper surface of the copper oxide layer 5 is brought into contact with a neutral etching liquid.

For example, the central portion (touch input region) of the copper oxide layer 5 and the copper layer 4 in plan view is etched so that a desired pattern (lead-out wire) is formed in the peripheral end portion (region corresponding to the lead-out wire) in plan view. Remove by

Specifically, first, as shown in FIG. 2A, a photosensitive dry film resist 10 is placed on the entire upper surface of the copper oxide layer 5, and the dry film resist 10 is developed into a desired pattern.

Subsequently, the copper oxide layer 5 exposed from the dry film resist 10 is brought into contact with a neutral etchant. As a result, as shown in FIG. 2B, the copper oxide layer 5 and the underlying copper layer 4 are etched with the neutral etchant. That is, the copper oxide layer 5 and the copper layer 4 are etched simultaneously. On the other hand, the transparent conductive layer 3 exposed from the copper layer 4 is not etched.

The pH of the neutral etching solution is, for example, 5.0 or higher, preferably 6.0 or higher, and for example, 9.0 or lower, preferably 8.0 or lower.

Examples of the neutral etching solution include ferric chloride aqueous solution, cupric chloride aqueous solution, amine compound-organic acid-copper compound aqueous solution, copper (II) sulfate aqueous solution, sulfuric acid-hydrogen peroxide aqueous solution, and the like. , preferably an amine compound-organic acid-copper compound aqueous solution.

After that, the dry film resist 10 is removed from the upper surface of the copper oxide layer 5 by, for example, peeling.

Thereby, the copper oxide layer 5 and the copper layer 4 are patterned as shown in FIG. 2C. That is, a patterned copper oxide layer 5A and a patterned copper layer 4A are formed. The patterned copper oxide layer 5A and the patterned copper layer 4A have substantially the same pattern in plan view.

In the second etching step, the transparent conductive layer 3 is etched. That is, the upper surface of the transparent conductive layer 3 is brought into contact with an acidic etchant.

For example, the central portion of the transparent conductive layer 3 exposed from the copper layer 4 and the copper oxide layer 5 is removed by etching so that a desired pattern (electrode pattern) is formed in the central portion (touch input area) in plan view. do.

Specifically, first, as shown in FIG. 2D, a photosensitive dry film resist 10 is placed on the entire upper surface of the patterned copper oxide layer 5A and the transparent conductive layer 3 exposed therefrom. pattern.

Subsequently, the transparent conductive layer 3 exposed from the dry film resist 10 is brought into contact with an acidic etchant. Thereby, as shown in FIG. 2E, the transparent conductive layer 3 is etched by the acidic etchant.

The pH of the acidic etchant is, for example, less than 4.0, preferably less than 3.0.

Examples of acidic etching solutions include aqueous solutions containing acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid, phosphoric acid, and mixed acids thereof.

After that, the dry film resist 10 is removed from the top surface of the transparent conductive layer 3 by, for example, peeling.

As a result, the transparent conductive layer 3 is patterned to form a patterned transparent conductive layer 3A (laminated body composed of the patterned first inorganic oxide layer 6A, the patterned metal layer 7A and the patterned second inorganic oxide layer 8A).

Thus, as shown in FIG. 2F, one embodiment of conductive film 1 is a patterned conductive film comprising, in sequence, transparent substrate 2, patterned transparent conductive layer 3A, patterned copper layer 4A, and patterned copper oxide layer 5A. A flexible film 1A is obtained.

The total thickness of the conductive film 1 is, for example, 2 μm or more, preferably 20 μm or more, and is, for example, 300 μm or less, preferably 200 μm or less.

The surface resistance of the upper surface of the conductive film 1 (specifically, the copper oxide layer 5 and the underlying copper layer 4) is, for example, 1.0 Ω/□ or less, preferably 0.5 Ω/□ or less. , or, for example, 0.001Ω/□ or more.

11. Applications The conductive film 1 is used, for example, as a substrate for a touch panel provided in an image display device. Examples of the type of touch panel include various types such as a capacitive type and a resistive film type, and the touch panel is particularly preferably used for a capacitive type touch panel. Specifically, for example, the patterned conductive film 1A is used as a touch panel by arranging it on a protective substrate such as protective glass.

Moreover, the conductive film 1 can be used, for example, as a base material for reflecting near-infrared rays, and can be particularly suitably used for an image quality display device for outdoor use. Specifically, for example, a polarizing film with a transparent conductive layer, in which a polarizer is attached to the conductive film 1, can be arranged in an image display device.

Furthermore, the conductive film 1 is, for example, an electrophoresis method, a twist ball method, a thermal rewritable method, an optical writing liquid crystal method, a polymer dispersed liquid crystal method, a guest/host liquid crystal method, a toner display method, a chromism method, an electric field It can also be suitably used for a flexible display device such as a deposition method.

According to this conductive film 1, since the copper oxide layer 5 is provided on the upper side of the copper layer 4, the natural oxidation of the copper layer 4 is suppressed, and the upper surface of the conductive film 1 (the copper layer 4 and the copper oxide layer 4) It is possible to suppress variations in surface resistance that accompany changes over time. Therefore, the surface resistance of the upper surface of the conductive film 1 (leading wiring, etc.) is excellent in stability.

Moreover, since the protective layer disposed on the upper surface of the copper layer 4 is the copper oxide layer 5, these layers (copper oxide layer 5 and copper layer 4) can be easily etched with a neutral etchant. In addition, since the second inorganic oxide layer 8 arranged under the copper layer 4 is difficult to etch with a neutral etchant, the metal layer 7 in the transparent conductive layer 3 is eroded, and the metal layer 7 is damaged. can be suppressed.

In the method for patterning the conductive film 1, the copper oxide layer 5 and the copper layer 4 are patterned by bringing the conductive film 1 into contact with a neutral etchant. 3 can be suppressed. Therefore, erosion of the metal layer 7 in the transparent conductive layer 3 and damage to the metal layer 7 can be suppressed.

Moreover, since the transparent conductive layer 3 includes the first inorganic oxide layer 6, the metal layer 7 and the second inorganic oxide layer 8, the metal layer 7 serves as a conductive layer and has excellent conductivity. Moreover, since the transparent conductive layer 3 has such a three-layer structure, it has excellent transparency, and when the transparent conductive layer 3 is patterned, the pattern can be suppressed from being visually recognized.

In addition, in the conductive film 1, if the metal layer 7 is a silver layer or a silver alloy layer, the resistance can be made lower. can be effectively blocked. Therefore, it can be suitably applied to an image display device used in an environment where the panel temperature tends to rise (for example, outdoors).

In addition, in the conductive film 1, if both the first inorganic oxide layer 6 and the second inorganic oxide layer 8 contain an indium-tin composite oxide, the transparency is excellent, and the pattern can be visually recognized effectively. can be suppressed.

12. MODIFIED EXAMPLE In the above-described embodiment, as shown in FIG. In addition, functional layers such as a hard coat layer, an optical adjustment layer, and an adhesion layer can be further provided.

In the above embodiment, as shown in FIG. 1, the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5 are provided only on the top surface of the transparent substrate 2. For example, although not shown, the bottom surface of the transparent substrate 2 is provided with the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5. Furthermore, a transparent conductive layer 3, a copper layer 4 and a copper oxide layer 5 can be provided in order.

EXAMPLES Examples and comparative examples are shown below to describe the present invention more specifically. In addition, the present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( Content ratio), physical properties, parameters, etc. be able to.

Example 1
A polyethylene terephthalate (PET) film having a thickness of 50 μm was prepared as a transparent substrate.

Next, the PET film is introduced into a vacuum sputtering device, and an indium tin oxide layer with a thickness of 40 nm, a silver layer with a thickness of 8 nm, and an indium tin oxide layer with a thickness of 36 nm are formed in order from the bottom by a sputtering method to form a transparent conductive film. formed a layer.

A target made of a sintered body of 12% by mass of tin oxide and 88% by mass of indium oxide was used to form the indium tin oxide layer, and a target made of an Ag alloy was used to form the silver layer. each used.

Next, the PET film laminated with the transparent conductive layer was introduced into a vacuum sputtering apparatus, and a copper layer having a thickness of 200 nm was formed by a sputtering method.

Specifically, sputtering was performed on the transparent conductive layer using a Cu target made of oxygen-free copper in a vacuum atmosphere with an atmospheric pressure of 0.4 Pa into which argon gas was introduced.

Then, the PET film laminated with the copper layer and the transparent conductive layer was introduced into a vacuum sputtering apparatus, and a copper oxide layer having a thickness of 4 nm was formed by a sputtering method.

Specifically, sputtering was performed on the transparent conductive layer using a CuO target in a vacuum atmosphere of 0.4 Pa into which argon gas was introduced.

As a result, a conductive film including a PET film, a transparent conductive layer, a copper layer and a copper oxide layer was obtained.

Examples 2-4
A conductive film was obtained in the same manner as in Example 1, except that the thickness of the copper oxide layer was changed to the thickness shown in Table 1.

Comparative example 1
A conductive film 1 was obtained in the same manner as in Example 1, except that no copper oxide layer was formed.

Comparative example 2
A conductive film was obtained in the same manner as in Example 1, except that a copper-nickel-titanium alloy layer (CuNiTi layer) having a thickness of 15 nm was formed instead of the copper oxide layer.

(1) Thickness The thickness of the substrate was measured using a film thickness gauge (digital dial gauge DG-205 manufactured by Peacock). The thicknesses of the first inorganic oxide layer, the metal layer, the second inorganic oxide layer, and the copper layer are measured using a transmission electron microscope (manufactured by Hitachi, "HF-2000"), and the side cross section of the conductive film. was measured by observing The thickness of the copper oxide layer was measured using a scanning fluorescent X-ray analyzer (manufactured by Rigaku, "ZSX PrimusII").

(2) Stability of Surface Resistance The conductive films of each example and each comparative example were left under the conditions of 60° C. and 95 RH% for 240 hours. After that, the surface resistance of each conductive film was measured at 30 points in the width direction at intervals of 10 mm. The measurement of the surface resistance was carried out according to the 4-probe method of JIS K7194 (1994).

At this time, the variation in surface resistance (maximum value or minimum value) is evaluated as 5 when it is within 5% of the average value of the measured surface resistance, and is evaluated as 4 when it is within 15%. When within 50%, it was evaluated as 3, and when it exceeded 50%, it was evaluated as 1 (defective). Table 1 shows the results.

(3) Patterning characteristics with a neutral etching solution On the upper surface of the conductive film of each example and each example, a masking tape was attached so as to form stripes at intervals of 10 mm, and a neutral etching solution (manufactured by MEC, " Mecbrite SF-5404B, pH 7.0, amine compound-organic acid-copper compound aqueous solution) was applied and the upper surface was etched.

Layers above the transparent conductive layer of the conductive film (copper layer and copper oxide layer in each example, copper layer in Comparative Example 1, copper layer and copper-nickel-titanium alloy layer in Comparative Example 2) A case where a striped pattern was formed was evaluated as ◯, and a case where a striped pattern was not formed was evaluated as x. Table 1 shows the results.

(4) Patterning Characteristics by Acidic Etching Liquid In the same procedure as in (3) above, etching was performed using acid etching (30 wt % HNO ₃ aqueous solution, pH 1.0 or less) instead of neutral etching. After that, the surface of the transparent conductive layer exposed from the copper layer and the copper oxide layer was observed by elemental mapping using an energy dispersive X-ray analyzer (EDX, manufactured by JEOL Ltd., "JED-2300"). . As a result, it was found that in all of the conductive films, there were some places where no silver element was present, indicating that the silver layer was damaged. In addition, when the surface resistance of the surface of the transparent conductive layer was measured using a four-terminal resistance measuring device, the surface resistance value increased by 15% or more in all conductive films, and the conductivity decreased. It was also found that

1 conductive film 2 transparent substrate 3 transparent conductive layer 4 copper layer 5 copper oxide layer 6 first inorganic oxide layer 7 metal layer 8 second inorganic oxide layer

Claims (4)

a transparent substrate;
a transparent conductive layer arranged on one side in the thickness direction of the transparent base material and comprising, in order, a first inorganic oxide layer, a metal layer and a second inorganic oxide layer;
a copper layer arranged on one side in the thickness direction of the transparent conductive layer;
and a copper oxide layer arranged on one side in the thickness direction of the copper layer. 2. The conductive film according to claim 1, wherein the copper oxide layer has a thickness of 13 nm or less. 3. The conductive film according to claim 1, wherein said copper layer and said copper oxide layer are patterned. A step of providing the conductive film according to claim 1 or 2;
and patterning the copper oxide layer and the copper layer by bringing a neutral etchant into contact with one surface of the conductive film in the thickness direction.

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