JP2020082566A - Conductive film and patterning method thereof - Google Patents

Abstract

To provide a conductive film and a patterning method thereof, excellent in stability of a copper layer, capable of easily patterning the copper layer, and capable of preventing a damage of a metal layer inside a transparent conductive layer.SOLUTION: A conductive film 1 includes a transparent substrate 2; a transparent conductive layer 3 arranged on an upper side of the transparent substrate 2 and sequentially including a first inorganic oxide layer 6, a metal layer 7 and a second inorganic oxide layer 8; a copper layer 4 arranged on an upper side of the transparent conductive layer 3; and a copper oxide layer 5 arranged on an upper side of the copper layer 4.SELECTED DRAWING: Figure 1

Description

The present invention relates to a conductive film and a patterning method thereof, and more specifically, to a conductive film suitably used for optical applications and a patterning method thereof.

Conventionally, it is known that a transparent conductive film provided with a transparent conductive layer is used for optical applications such as a touch panel.

For example, a transparent conductive film that includes a transparent substrate and a light-transmissive inorganic layer, and the light-transmissive inorganic layer includes a first inorganic oxide layer, a metal layer, and a second inorganic oxide layer in that order. It is described (for example, see Patent Document 1).

In the transparent conductive film of Patent Document 1, for example, a metal layer such as a silver layer plays a role as a conductive layer, and therefore has a higher conductivity (lower resistance) than a conventional transparent conductive layer made of indium oxide. It is known to exert.

On the other hand, in a transparent conductive film, a conductive film with a copper layer in which a copper layer is laminated on the upper surface of a transparent conductive layer is proposed in order to form a wiring around the outer edge of the touch input area to achieve a narrow frame. Has been done. In such a conductive film with a copper layer, since the copper layer is easily oxidized and the conductivity changes with time, the conductivity such as surface resistance (sheet resistance) varies in plan view after a long time has elapsed. Occurs. Therefore, it is known to dispose 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, by patterning each of the copper layer and the transparent conductive film in order, a leading wiring of a frame portion is formed from the copper layer, and an electrode pattern of the touch panel portion is formed from the transparent conductive film. Form.

JP, 2016-155377, A JP, 2013-1009, A

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

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 acid-based etching solution. Then, the metal layer (silver layer) of the transparent conductive layer is reached and the metal layer is damaged. As a result, the metal layer may not be formed in a desired electrode pattern, or a desired surface resistance may not be achieved.

The present invention provides a conductive film having excellent stability of a copper layer, capable of easily patterning the copper layer, and suppressing damage to a metal layer in a transparent conductive layer, and a patterning method thereof.

The present invention [1] includes a transparent base material, a transparent conductive layer which is disposed on one side in the thickness direction of the transparent base material, and which includes a first inorganic oxide layer, a metal layer and a second inorganic oxide layer in this order. It includes a conductive film including 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.

The present invention [2] includes the conductive film according to [1], wherein the thickness of the copper oxide layer is 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] comprises the step of preparing the conductive film according to [1] or [2] and the step of bringing a neutral etching solution into contact with one surface in the thickness direction of the conductive film to thereby form the copper oxide layer. And a step of patterning the copper layer.

Since the conductive film of the present invention includes the transparent conductive layer that includes 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 provided 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.

Since the conductive film of the present invention includes the copper oxide layer, the copper oxide layer and the copper layer can be easily etched with a neutral etching solution. Further, since the inorganic oxide layer arranged on the other side in the thickness direction of the copper layer is hard to be etched by the neutral etching solution, 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 etching solution, so that the transparent conductive layer disposed on the other side in the thickness direction of the copper oxide layer is formed. 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 are process diagrams of the method for patterning the conductive film shown in FIG. 1, FIG. 2A is a process of disposing a dry film resist, and FIG. 2B is a process of etching a copper oxide layer and a copper layer. 2C shows a step of removing the dry film resist, FIG. 2D shows a step of disposing the dry film resist, FIG. 2E shows a step of etching the transparent conductive layer, and FIG. 2F shows a step of obtaining a patterned conductive film.

With reference to FIG. 1, the conductive film 1 which is one embodiment of the present invention will be described.

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, one side in 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). Further, the left-right direction and the depth direction of the paper are plane directions orthogonal to the up-down direction. Specifically, it is based on the directional arrow in each figure. Specifically, it is based on the directional arrow 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 surface direction orthogonal to the thickness direction, and has a flat upper surface (one surface in the thickness direction) and a flat lower surface ( (The other surface in the thickness direction). The conductive film 1 is, for example, a component such as a touch panel substrate provided in an optical device (for example, an image display device), that is, not an optical device. That is, the conductive film 1 is a component for manufacturing 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 is independently distributed and industrially usable. ..

Specifically, as shown in FIG. 1, the conductive film 1 of the first embodiment is provided with a transparent base material 2, a transparent conductive layer 3, a copper layer 4, and a copper oxide layer 5 in this order. It is a film. That is, the conductive film 1 includes the transparent base material 2, the transparent conductive layer 3 arranged on the upper side of the transparent base material 2, the copper layer 4 arranged on the upper side of the transparent conductive layer 3, and the upper side of the copper layer 4. And a copper oxide layer 5 disposed on the. Preferably, the conductive film 1 is composed only of the transparent substrate 2, the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5. Hereinafter, each layer will be described in detail.

2. Transparent base material A support material that secures the mechanical strength of the conductive film 1. That is, the transparent base material 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 lowermost layer of the conductive film 1.

The transparent substrate 2 is, for example, a polymer film having transparency. Examples of the material for the polymer film include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; (meth)acrylic resins (acrylic resin and/or methacrylic resin) such as polymethacrylate; Olefin resins such as polypropylene and cycloolefin polymers (for example, polymers such as norbornenes, cyclopentadiene and cyclohexadiene), for example, polycarbonate resin, polyether sulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin , Cellulose resins, polystyrene resins and the like. The polymer films can be used alone or in combination of two or more kinds.

From the viewpoint of transparency, heat resistance, mechanical strength, and the like, polyester resin is preferable, and polyethylene terephthalate is more preferable.

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 viewpoints of mechanical strength, transparency, and the dot properties when the conductive film 1 is used as a film for a touch panel, and, for example, , 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 meter (digital dial gauge).

In addition, an easily adhesive layer, an adhesive layer, a separator, and the like may be arranged on the upper surface and/or the lower surface of the transparent substrate 2 as necessary.

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

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 base material 2 and the copper layer 4 so as to contact the upper surface of the transparent base material 2 and the lower surface of the copper layer 4.

The transparent conductive layer 3 includes a first inorganic oxide layer 6, a metal layer 7, and a second inorganic oxide layer 8 in that order. That is, the transparent conductive layer 3 includes the first inorganic oxide layer 6 arranged on the upper surface of the transparent substrate 2, the metal layer 7 arranged on the upper surface of the first inorganic oxide layer 6, and the upper surface of the metal layer 7. And a second inorganic oxide layer 8 disposed on the. Preferably, the transparent conductive layer 3 is composed only of 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, 10 Ω/□ or less, preferably 5 Ω/□ or less, and for example, 0.1 Ω/□ 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 near infrared rays (wavelength 850 to 2500 nm) of the transparent conductive layer 3 is, for example, 10% or more, preferably 50% or more, and 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, for example, by observing a cross section using a transmission electron microscope (TEM). Hereinafter, the first inorganic oxide layer 6, the metal layer 7, and the second inorganic oxide layer 8 will be described in detail.

4. First Inorganic Oxide Layer The first inorganic oxide layer 6 is a barrier layer that suppresses hydrogen element and carbon element derived from the transparent substrate 2 from entering the metal layer 7. Further, the first inorganic oxide layer 6 together with the second inorganic oxide layer 8 suppresses the visible light reflectance of the metal layer 7 and improves the visible light transmittance (transparency) of the transparent conductive layer 3. It is also a layer. In addition, the first inorganic oxide layer 6 is preferably 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 lowermost layer in the transparent conductive layer 3. More specifically, the first inorganic oxide layer 6 is arranged on the entire upper surface of the transparent base material 2 so as to contact the upper surface of the transparent base material 2.

As the inorganic oxide forming the first inorganic oxide layer 6, for example, In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, W, Fe, Examples thereof include metal oxides formed from at least one metal selected from the group consisting of Pb, Ni, Nb, and Cr. If necessary, the metal oxide can be further doped with a metal atom shown in the above group.

The inorganic oxide is preferably an oxide containing indium oxide (an indium oxide-containing oxide) from the viewpoint of being able to reduce the surface resistance and ensuring excellent transparency.

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

Specific examples of the indium oxide-containing oxide include indium zinc complex oxide (IZO), indium gallium complex oxide (IGO), indium gallium zinc complex oxide (IGZO), indium tin complex oxide (ITO). ) Are mentioned, More preferably, an indium tin compound oxide (ITO) is mentioned. In the present specification, “ITO” may be a composite oxide containing at least indium (In) and tin (Sn), and may contain additional components other than these. Examples of the additional component include metal elements other than In and Sn, and examples thereof include metal elements shown in the above group 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, based on the total amount of tin oxide and indium oxide (In ₂ O ₃ ). Is more preferably 10% by mass or more, and is, for example, 35% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less. The content of indium oxide (In ₂ O ₃ ) is the balance of the content of tin oxide (SnO ₂ ). When 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 for example, 100 nm or less, preferably 50 nm or less. When the thickness of the first inorganic oxide layer 6 is in 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. The metal layer 7 is also a low resistance layer that lowers the surface resistance of the transparent conductive layer 3. Further, preferably, the metal layer 7 is also an infrared reflective layer that imparts 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, the metal layer 7 includes an upper surface of the first inorganic oxide layer 6 and a lower surface of the second inorganic oxide layer 8 between the first inorganic oxide layer 6 and the second inorganic oxide layer 8. It is arranged 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. For example, Ti, Si, Nb, In, Zn, Sn, Au, Ag, Cu, Al, Co, Cr, Ni, Pb, Pd, Pt, Cu, Ge, Ru, Nd, Mg, Ca, Na, W, Zr, Ta and Hf, or a metal selected from the group consisting of two or more thereof. Examples include alloys containing metals.

The metal is preferably silver (Ag) or a silver alloy. When the metal is silver or a silver alloy, in addition to the resistance value of the transparent conductive layer 3 being reduced, the transparent conductive layer 3 having a particularly high average reflectance in the near infrared region (wavelength 850 to 2500 nm) is formed. It is obtained and can be suitably applied to the use of an image display device used outdoors.

The silver alloy contains silver as a main component and other metals as sub-components. The metal element as an accessory component is not limited. Examples of silver alloys include Ag-Cu alloys, Ag-Pd alloys, Ag-Pd-Cu alloys, Ag-Pd-Cu-Ge alloys, Ag-Cu-Au alloys, Ag-Cu-In alloys, 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 alloy, Ag-Sn alloy, etc. are mentioned. From the viewpoint of wet heat durability, as the silver alloy, Ag-Cu alloy, Ag-Cu-In alloy, Ag-Cu-Sn alloy, Ag-Pd alloy, Ag-Pd-Cu alloy and the like are preferable.

The content ratio 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 for example, 99.9% by mass or less. The content ratio of the other metal in the silver alloy is the balance of the content ratio of silver described above.

From the viewpoint of improving the transmittance of the transparent conductive layer 3, the metal layer 7 has a thickness of, for example, 1 nm or more, preferably 5 nm or more, and, 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 and moisture 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. The second inorganic oxide layer 8 is preferably 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 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 contact the upper surface of the metal layer 7.

Examples of the inorganic oxide forming the second inorganic oxide layer 8 include the inorganic oxides exemplified in the first inorganic oxide layer 6, preferably indium oxide-containing oxides, and more preferably ITO. Can be 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 characteristics, 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 for example, 100 nm or less, preferably 50 nm or less. When the thickness of the second inorganic oxide layer 8 is in the above range, it is easy to adjust the visible light transmittance of the transparent conductive layer 3 to a high level.

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

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 in a desired pattern (patterned copper layer 4A described later) in a first patterning step described later, and, for example, wiring in an outer edge portion (outer periphery) of the touch input area (outer periphery). It is a conductive layer that becomes a pattern (for example, a lead 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 the material of the copper layer 4 include copper or a copper alloy. The metal that constitutes the copper alloy is not limited, and examples thereof include silver, tin, chromium, and zirconium. From the viewpoint of conductivity, copper is preferable.

The thickness of the copper layer 4 is, for example, 100 nm or more, preferably 150 nm or more, and is, for example, 400 nm or less, preferably 300 nm or less. When 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 (leading copper wiring in the frame portion) in response to an increase in the size of the touch panel. When the thickness of the copper layer 4 is equal to or less than the above upper limit, the frame portion can be thinned.

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

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, a wiring pattern (for example, a routing wiring) is formed in a desired pattern (a patterned copper oxide layer 5A described later) together with the copper layer 4, for example, on an outer edge portion (outer peripheral edge portion) outside (outer periphery) of the touch input area of the touch panel. ) Is the layer.

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 on 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. The metal that constitutes the copper alloy is not limited, and examples thereof include silver, tin, chromium, and zirconium. From the viewpoint of conductivity, copper oxide is preferable.

The thickness of the copper oxide layer 5 is, for example, 1 nm or more, preferably 3 nm or more, and for example, 30 nm or less, preferably 13 nm or less, more preferably 8 nm or less, further preferably 6 nm or less. When the thickness of the copper oxide layer 5 is within the above range, it is possible to further suppress the time-dependent change (natural oxidation) of the surface resistance of the upper surface (the copper oxide layer 5 and the copper layer 4) of the conductive film 1. Therefore, the variation in surface resistance can be further reduced.

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, for example, 15/100. The ratio is preferably 7/100 or less, more preferably 5/100 or less, still more preferably 3/100 or less. If the ratio is within the range, it is possible to further reduce the variation in surface resistance.

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 method for manufacturing the conductive film 1 includes, for example, a step of arranging (stacking) the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5 on the transparent substrate 2 in order.

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

Then, the transparent conductive layer 3 is arranged on the upper surface 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 sequentially arranged on the upper surface of the transparent substrate 2 by a dry method.

Examples of the dry method include a vacuum vapor deposition method, a sputtering method, an ion plating method and the like. A sputtering method is preferable.

Examples of the gas used in the sputtering method include an inert gas such as Ar. Moreover, if necessary, a reactive gas such as oxygen can be used together. 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. Also, for example, it is 5/100 or less.

Specifically, in forming the first inorganic oxide layer 6, as the gas, an inert gas and a reactive gas are preferably used together. In forming the metal layer 7, an inert gas is preferably used alone as the gas. 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 adopted, the target material may be the above-mentioned inorganic oxide or metal forming each layer.

As a power source used in the sputtering method, for example, a DC power source, an MF/AC power source, and an RF power source can be used alone or in combination, and preferably a DC power source can be used.

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

If necessary, heating may be performed in order to crystallize the first inorganic oxide layer 6 and/or the second inorganic oxide layer 8.

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. The heating may be performed in any of an air atmosphere, an inert atmosphere, and a vacuum.

Next, the copper layer 4 is arranged on the upper surface of the transparent conductive layer 3. For example, the 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 the same methods as those described above for forming the transparent conductive layer 3, and preferably the sputtering method. By this method, the copper layer 4 having a uniform thickness can be formed even with a thick film.

The conditions for the sputtering method for the copper layer 4 are 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 a gas. The target material is preferably oxygen-free copper.

Next, the copper oxide layer 5 is arranged on the upper surface of the copper layer 4. For example, the 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 the same methods as those described above for forming the transparent conductive layer 3, and preferably the sputtering method. By this method, the copper oxide layer 5 having a uniform thickness can be formed on the upper surface of the copper layer 4 with good adhesion.

The conditions of the sputtering method for the copper oxide layer 5 are the same as the conditions 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. The target material is preferably copper oxide (CuO).

In this way, as shown in FIG. 1, the conductive film 1 including the transparent substrate 2, the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5 is obtained. This conductive film 1 is a transparent conductive film with a copper layer.

The above-mentioned manufacturing method can be carried out by a roll-to-roll method. Further, a part or the whole can be carried out in a batch system.

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

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

For example, the central portions (touch input areas) of the copper oxide layer 5 and the copper layer 4 in plan view are etched so that a desired pattern (leading wiring) is formed in the peripheral edge portion (area corresponding to the routing wiring) in plan view. To remove.

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

Then, a neutral etching solution is brought into contact with the copper oxide layer 5 exposed from the dry film resist 10. As a result, as shown in FIG. 2B, the copper oxide layer 5 and the copper layer 4 arranged therebelow are etched by the neutral etching solution. That is, the copper oxide layer 5 and the copper layer 4 are simultaneously etched. 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 is, 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-based aqueous solution is used.

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

As a result, as shown in FIG. 2C, the copper oxide layer 5 and the copper layer 4 are patterned. That is, the patterned copper oxide layer 5A and the 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 acidic etching liquid is brought into contact with the upper surface of the transparent conductive layer 3.

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) of the planar view. To do.

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

Then, an acidic etching solution is brought into contact with the transparent conductive layer 3 exposed from the dry film resist 10. As a result, as shown in FIG. 2E, the transparent conductive layer 3 is etched by the acidic etching solution.

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

Examples of the acidic etching solution 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 upper surface of the transparent conductive layer 3 by, for example, peeling.

As a result, the transparent conductive layer 3 is patterned to form the patterned transparent conductive layer 3A (a laminated body including 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, as one embodiment of the conductive film 1, the patterned conductive material including the transparent substrate 2, the patterned transparent conductive layer 3A, the patterned copper layer 4A, and the patterned copper oxide layer 5A in this order. 1A is obtained.

The total thickness of the conductive film 1 is, for example, 2 μm or more, preferably 20 μm or more, and 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 copper layer 4 therebelow) is, for example, 1.0 Ω/□ or less, preferably 0.5 Ω/□ or less. Further, for example, it is 0.001 Ω/□ or more.

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

Further, the conductive film 1 can be used, for example, as a substrate for reflecting near infrared rays, and can be particularly preferably 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 the image display device.

Further, the conductive film 1 is, for example, an electrophoretic system, a twist ball system, a thermal rewritable system, an optical writing liquid crystal system, a polymer dispersion type liquid crystal system, a guest/host liquid crystal system, a toner display system, a chromism system, an electric field. It can be suitably used for a flexible display element such as a deposition type.

According to this conductive film 1, since the copper oxide layer 5 is provided on the upper side of the copper layer 4, 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 the variation in surface resistance due to the change with time. Therefore, the stability of the surface resistance of the upper surface of the conductive film 1 (such as the leading wiring) is excellent.

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

Moreover, in the patterning method of the conductive film 1, since the copper oxide layer 5 and the copper layer 4 are patterned by bringing the conductive film 1 into contact with a neutral etching solution, the transparent conductive layer below the copper oxide layer 5 is patterned. The etching of 3 can be suppressed. Therefore, erosion of the metal layer 7 in the transparent conductive layer 3 and eventually 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. In addition, 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, visual recognition of the pattern can be suppressed.

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, and the reflectance in the near-infrared region is high, so that heat rays such as sunlight can be efficiently absorbed. Can be shut off. Therefore, it can be suitably applied to an image display device used in an environment where the panel temperature is likely 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 the indium tin composite oxide, the transparency is excellent, and the visual recognition of the pattern can be effectively performed. Can be suppressed.

12. Modified Example In the embodiment described above, as shown in FIG. 1, the transparent substrate 2, the transparent conductive layer 3, the copper layer 4 and the copper oxide layer 5 are provided, but for example, between the transparent substrate 2 and the transparent conductive layer 3. 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-described 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 upper surface of the transparent base material 2. For example, although not shown, the lower surface of the transparent base material 2 is not shown. In addition, the transparent conductive layer 3, the copper layer 4, and the copper oxide layer 5 can be further provided in order.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the examples and comparative examples. Further, specific numerical values such as a mixing ratio (content ratio), physical property values, and parameters used in the following description are described in the above “Mode for carrying out the invention”, and a corresponding mixing ratio ( Substitute the upper limit value (value defined as "below" or "less than") or the lower limit value (value defined as "greater than or equal to" "exceeding") such as content ratio), physical property value, parameter etc. be able to.

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

Then, the PET film was introduced into a vacuum sputtering apparatus, and an indium tin oxide layer having a thickness of 40 nm, a silver layer having a thickness of 8 nm, and an indium tin oxide layer having a thickness of 36 nm were sequentially formed from the bottom by a sputtering method to obtain a transparent conductive film. Layers were formed.

A target made of a sintered body of 12 mass% tin oxide and 88 mass% of indium oxide was used for forming the indium tin oxide layer, and a target made of Ag alloy was used for forming the silver layer. Used respectively.

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

Specifically, the transparent conductive layer was sputtered using a Cu target made of oxygen-free copper in a vacuum atmosphere in which an argon gas was introduced and the pressure was 0.4 Pa.

Next, the PET film in which the copper layer and the transparent conductive layer were laminated was introduced into a vacuum sputtering device, 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 in which an argon gas was introduced and the pressure was 0.4 Pa.

This obtained the electroconductive film provided with a PET film, a transparent electroconductive layer, a copper layer, and a copper oxide layer.

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 the copper oxide layer was not formed.

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

(1) Thickness The thickness of the substrate was measured using a film thickness meter (Digital Dial Gauge DG-205 manufactured by Peacock). The thickness of the first inorganic oxide layer, the metal layer, the second inorganic oxide layer, and the copper layer was measured using a transmission electron microscope (“HF-2000” manufactured by Hitachi, Ltd.) to determine the side cross section of the conductive film. It was measured by observing. The thickness of the copper oxide layer was measured using a scanning X-ray fluorescence analyzer ("ZSX Primus II" manufactured by Rigaku Corporation).

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

At this time, when the variation (maximum value or minimum value) of the surface resistance is within 5% of the average value of the measured surface resistance, it is evaluated as 5, and when it is within 15%, it is evaluated as 4 and 30%. When it was within 50%, it was evaluated as 3, when it was within 50%, it was evaluated as 2, and when it exceeded 50%, it was evaluated as 1 (defective). The results are shown in Table 1.

(3) Patterning Characteristics with Neutral Etching Liquid A masking tape was attached so that stripes were formed at 10 mm intervals on the upper surface of each example and the conductive film of each example. MECBRIGHT SF-5404B", pH 7.0, amine compound-organic acid-copper compound-based 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) When it was formed in a stripe pattern, it was evaluated as ◯, and when it was not formed in a stripe pattern, it was evaluated as x. The results are shown in Table 1.

(4) Patterning characteristics with an acidic etching solution In the same procedure as in (3) above, etching was carried out using acidic etching (30 wt% HNO ₃ aqueous solution, pH 1.0 or less) instead of neutral etching. Then, 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 the conductive films, there were spots where silver element did not exist, and the silver layer was damaged. Moreover, when the surface resistance of the surface of the transparent conductive layer was measured using a four-terminal resistance measuring device, the value of the surface resistance increased by 15% or more in all the 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 disposed on one side in the thickness direction of the transparent substrate, the transparent conductive layer including a first inorganic oxide layer, a metal layer and a second inorganic oxide layer in order;
A copper layer arranged on one side in the thickness direction of the transparent conductive layer,
A conductive film, comprising a copper oxide layer arranged on one side in the thickness direction of the copper layer. The conductive film according to claim 1, wherein the copper oxide layer has a thickness of 13 nm or less. The conductive film according to claim 1 or 2, wherein the copper layer and the copper oxide layer are patterned. A step of preparing the conductive film according to claim 1 or 2,
And a step of patterning the copper oxide layer and the copper layer by bringing a neutral etching solution into contact with one surface in the thickness direction of the conductive film, the method for patterning a conductive film.

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