WO2019049617A1 - Conductive film, touch panel sensor and touch panel - Google Patents

Abstract

The present invention addresses the problem of providing a conductive film which comprises a metal thin wire that has a line width of 2.0 μm or less and exhibits excellent adhesion to a substrate for a long period of time. The present invention also addresses the problem of providing a touch panel sensor and a touch panel, each of which comprises this conductive film. A conductive film according to the present invention comprises a substrate and a conductive part that is arranged on at least one main surface of the substrate and is composed of a metal thin wire. The metal thin wire comprises a base layer and a conductive layer, which are sequentially arranged in this order from the substrate side, and a coating film that covers a lateral surface part of the base layer; and the metal thin wire has a line width of 2.0 μm or less. The base layer contains elemental nickel as a main component; the conductive layer contains copper as a main component; and the coating film has a thickness of less than 100 nm and contains a metal which is selected from among metals that are electrochemically more noble than nickel.

Description

Conductive film, touch panel sensor, and touch panel

The present invention relates to a conductive film, a touch panel sensor, and a touch panel.

DESCRIPTION OF RELATED ART The electroconductive film by which the electroconductive part which consists of a metal fine wire is arrange | positioned on a board | substrate is used for various uses. For example, in recent years, with the increase in the loading rate of touch panels on mobile phones, portable game devices, etc., the demand for conductive films for capacitive touch panel sensors capable of multipoint detection is rapidly expanding.

For example, when using a display with a touch panel, the user looks at the display from a distance of several tens of centimeters from the display. At this time, in order to prevent the thin metal wire from being visually recognized by the user, it is required to further narrow the line width of the thin metal wire.
In general, thin metal wires having a narrow line width have poor adhesion to the substrate. For this reason, in recent years, in order to improve this, there has been proposed a conductive film provided with a layer having a function of further improving the adhesion between the substrate and the fine metal wire.

As the conductive film as described above, for example, Patent Document 1 discloses a transparent conductive film provided with a transparent electrode layer having a fine metal wire pattern on at least one surface of a transparent film substrate, and the fine metal wire is A second metal layer in contact with the first metal layer and the first metal layer from the transparent film substrate side in this order, and a Ni base metal layer is mainly provided between the transparent film substrate and the first metal layer A transparent conductive film is described, wherein the base metal layer and the first metal layer are in contact with each other.

International Publication No. 2014/156489

The inventor examined the transparent conductive film described in Patent Document 1. When the line width of the metal fine wire is 2.0 μm or less, the metal fine wire becomes the base metal when exposed to the atmosphere for a long time It has been found that the problem of peeling from the substrate as a whole and the problem of peeling between the first metal layer and the base metal layer tend to occur.

Then, this invention makes it a subject to provide the conductive film containing a metal fine wire whose line | wire width is 2.0 micrometers or less and excellent in the adhesiveness to a board | substrate over a long period of time.
Another object of the present invention is to provide a touch panel sensor and a touch panel including the above-mentioned conductive film.

As a result of intensive studies to achieve the above problems, the present inventors have found that the above problems can be solved by the conductive film in which the side surface portion of the base layer mainly composed of nickel alone is covered with a predetermined film. The present invention has been completed.
That is, it discovered that the said objective could be achieved by the following structures.

[1] A conductive film comprising: a substrate; and a conductive portion composed of fine metal wires disposed on at least one of the main surfaces of the substrate,
The metal fine wire includes an underlayer and a conductive layer disposed in this order from the substrate side, and a film covering the side surface of the underlayer, and the line width is 2.0 μm or less.
The base layer contains nickel alone as a main component,
The conductive layer contains copper as a main component,
The conductive film, wherein the film contains a metal selected from metals which are electrochemically nobler than nickel, and whose thickness is less than 100 nm.
[2] The conductive film according to [1], wherein the film contains a metal selected from metals electrochemically nobler than silver.
[3] The conductive film according to [1] or [2], wherein the film contains palladium.
[4] The conductive film according to any one of [1] to [3], wherein the line width of the fine metal wire is 1.2 μm or less.
[5] The conductive film according to any one of [1] to [4], wherein the conductive layer contains copper in an amount of 90% by mass or more based on the total mass of the layer.
[6] A touch panel sensor comprising the conductive film according to any one of [1] to [5].
[7] A touch panel including the touch panel sensor according to [6].

According to the present invention, it is possible to provide a conductive film including a metal fine wire having a line width of 2.0 μm or less and excellent in adhesion to a substrate over a long period of time.
Further, according to the present invention, it is possible to provide a touch panel sensor and a touch panel including the above-mentioned conductive film.

It is a conceptual diagram showing the problem of a prior art. It is a top view of 1st Embodiment of the conductive film of this invention. FIG. 3 is a cross-sectional view taken along the line AA of the conductive film shown in FIG. 2A. It is a partially expanded view of the electroconductive part in FIG. 2A. It is a fragmentary sectional view of 1st Embodiment of the electroconductive film of this invention (it is sectional drawing in the BB cross section in FIG. 2C). It is a fragmentary sectional view of a 2nd embodiment of a conductive film of the present invention. It is a fragmentary sectional view of a substrate with a foundation film obtained by performing a foundation film formation process. It is a fragmentary sectional view of a substrate with a 2nd metal film obtained by implementing a 2nd metal film formation process. It is a fragmentary sectional view of a substrate with a resist film obtained by performing a resist film formation process. It is a fragmentary sectional view of a substrate with a first metal film obtained by performing a first metal film formation process. It is a fragmentary sectional view of the laminated body obtained by implementing a resist film removal process. It is a fragmentary sectional view of a layered product obtained by carrying out a foundation film and the 2nd metal film removal process. It is a fragmentary sectional view of the electroconductive film obtained by implementing a film formation process.

Hereinafter, the present invention will be described in detail.
The description of the configuration requirements described below may be made based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.
In the present specification, a numerical range represented using “to” means a range including numerical values described before and after “to” as the lower limit value and the upper limit value.
In addition, “active light” or “radiation” in the present specification means, for example, a bright line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet (EUV: extreme ultraviolet lithography) light, X-rays, and Means electron beam etc. In the present specification, light means actinic rays and radiation. Unless otherwise specified, the "exposure" in the present specification means not only exposure by far ultraviolet rays represented by a mercury lamp and an excimer laser, X-rays and EUV light but also particle beams such as electron beams and ion beams unless otherwise specified. Also includes drawing by.

[Conductive film]
The feature of the conductive film of the present invention is that the side portion of the base layer containing a single nickel as a main component is covered with a predetermined film.

First, the problems of the prior art will be described in detail.
In Patent Document 1, as shown in FIG. 1, a metal thin wire 108 provided with a substrate 100, a base metal layer 102 disposed on the substrate 100, a first metal layer 104, and a second metal layer 106. And a transparent conductive film 110 is disclosed. The base metal layer 102 contains nickel as a main component.

As described above, in the transparent conductive film 110, when the line width L1 of the metal fine wire 108 is 2.0 μm or less, the metal fine wire 108 peels off from the substrate 100 together with the base metal layer 102 when exposed to the atmosphere for a long time. There is a problem of being easy and a problem of being easy to exfoliate between the first metal layer 104 and the base metal layer 102.
The inventor found that the above problem is that nickel, which is the main component of the base metal layer 102, is easily corroded in the presence of oxygen and water in the atmosphere, starting from the side surface portion 102a exposed to the atmosphere. I speculated that it was the cause.
For example, copper suitably used as a material of the first metal layer 104 and the second metal layer 106 forms a passivity (oxide film) on the surface when exposed to the atmosphere, and the corrosion to the inside is suppressed . On the other hand, since nickel does not form a passive state, the corrosion of the base metal layer 102 mainly composed of nickel proceeds to the inside of the base metal layer 102 depending on the time of exposure to the atmosphere. As a result, it is considered that the adhesion of the base metal layer 102 to the substrate 100 is lowered and the adhesion of the base metal layer 102 to the first metal layer 104 is lowered.
In particular, when the line width L1 of the metal thin wire 108 is an ultra thin wire having a width of 2.0 μm or less, the influence of corrosion starting from the side surface portion 102a of the base metal layer 102 becomes relatively large. Becomes more prominent.

Hereinafter, the present invention which solved the above-mentioned problem is explained, taking the specific embodiment as an example. As described above, the feature of the conductive film of the present invention is that the side portion of the base layer containing nickel alone as the main component is covered with a predetermined film.
First, in the first embodiment of the conductive film of the present invention, which will be described later, as shown in FIG. 3, the fine metal wires 12 disposed on the substrate 10 are the underlayer 14 disposed in this order from the substrate 10 side. And the conductive layer 16 and the film 18 covering the base layer 14 and the periphery of the conductive layer 16. Further, the line width L2 of the thin metal wire 12 is 2.0 μm or less.
In the metal thin wire 12, the underlayer 14 contains a single nickel as a main component, and the film 18 contains a metal selected from metals which are electrochemically nobler than nickel. Here, "electrochemically noble metal than nickel" intends metal whose ionization tendency is lower than that of nickel, for example, tin, lead, antimony, bismuth, copper, mercury, silver, palladium, iridium, Platinum and gold can be mentioned.
That is, the side layer portion 14a of the underlayer 14 is covered with a metal material which is less susceptible to corrosion than nickel in the presence of oxygen and water in the atmosphere, whereby the underlayer 14 is made in the presence of oxygen and water in the atmosphere. The corrosion that occurs is suppressed.
The inventor has also confirmed that in the metal thin wire 12, the thickness L3 of the film 18 needs to be less than 100 nm. When the thickness L3 of the film 18 is 100 nm or more, the contact surface of the underlayer 14 with the substrate 10 becomes relatively smaller, and the adhesion of the underlayer 14 to the substrate 10 is lowered. It has been confirmed that when the line width of the thin metal wire is relatively large (for example, about 3 to 10 μm), the decrease in adhesion depending on the thickness of the film is not observed.

Further, in the second embodiment of the conductive film of the present invention, which will be described later, as shown in FIG. 4, the fine metal wires 32 disposed on the substrate 10 are the underlayer 34 disposed in this order from the substrate 10 side. And the conductive layer 36, and the film 38 covering the side portion 34a of the base layer 34. Specifically, in the metal fine wire 32, the conductive layer 36 is disposed on the surface 34b formed of the base layer 34 and the film 38 covering the side surface portion 34a. The metal thin line 32 has a line width L4 of 2.0 μm or less.
In the metal thin wires 32, the base layer 34 contains a simple substance of nickel as a main component, and the film 38 contains a metal selected from metals which are electrochemically nobler than nickel.
That is, by covering the side surface portion 34a of the base layer 34 with a metal material that is less likely to be corroded than nickel, the base layer 34 is inhibited from being corroded in the presence of oxygen and water in the air.
Further, in the thin metal wire 32, the thickness L5 of the film 38 is less than 100 nm. When the thickness L5 of the film 38 is 100 nm or more, the contact surface of the underlayer 34 with the substrate 10 becomes relatively small, and the adhesion of the underlayer 34 to the substrate 10 is lowered. It has been confirmed that when the line width of the thin metal wire is relatively large (for example, about 3 to 10 μm), the decrease in adhesion depending on the thickness of the film is not observed.

<< First Embodiment >>
Hereinafter, a first embodiment of the conductive film of the present invention will be described. FIG. 2A is a top view of the first embodiment of the conductive film of the present invention, and FIG. 2B is a cross-sectional view of the conductive film shown in FIG. 2A, taken along the line AA. FIG. 2C is a partially enlarged view of the conductive portion in FIG. 2A.

The conductive film 20 of the present invention includes a substrate 10 and a conductive portion 13 disposed on at least one of the main surfaces of the substrate 10 as shown in FIGS. 2A and 2B.

[Substrate 10]
The type of the substrate 10 is not particularly limited as long as the substrate 10 has a main surface and supports the conductive portion 13. As the substrate 10, a flexible substrate (preferably an insulating substrate) is preferable, and a resin substrate is more preferable.

The substrate 10 preferably transmits 60% or more of visible light (wavelength 400 to 800 nm) light, more preferably transmits 80% or more, still more preferably 90% or more, and transmits 95% or more. Is particularly preferred.

Examples of the material constituting the resin substrate include polyether sulfone resins, polyacrylic resins, polyurethane resins, polyester resins (polyethylene terephthalate, polyethylene naphthalate, etc.), polycarbonate resins, polysulfone resins, polyamide resins Examples thereof include resins, polyarylate resins, polyolefin resins, cellulose resins, polyvinyl chloride resins, and cycloolefin resins. Among them, cycloolefin resins are preferable in that they have more excellent optical properties.
The thickness of the substrate 10 is not particularly limited, but is preferably 0.01 to 0.5 mm, more preferably 0.03 to 0.2 mm, from the viewpoint of balance between handleability and thinning.
Also, the substrate 10 may have a multilayer structure, and may include, for example, a functional film as one of its layers. The substrate itself may be a functional film.

[Conductive part 13]
Although the form of the conductive film which has planar shape was shown in FIG. 2A and FIG. 2B, it is not restrict | limited as above as a conductive film. The conductive film may have a three-dimensional shape (three-dimensional shape). Examples of the three-dimensional shape include a three-dimensional shape including a curved surface, and more specifically, a hemispherical shape, a semicylindrical shape, a corrugated shape, a convex-concave shape, and a cylindrical shape.
Moreover, in FIG. 2A and 2B, although the electroconductive part 13 is arrange | positioned on one main surface of the board | substrate 10, it is not restrict | limited to this form. For example, the conductive portions 13 may be disposed on both main surfaces of the substrate 10.
Moreover, in FIG. 2A and FIG. 2B, although the conductive part 13 is arrange | positioned at six stripe form, it is not restrict | limited to this form, What kind of arrangement | positioning pattern may be sufficient.

FIG. 2C is a partially enlarged top view of the conductive portion 13. The conductive portion 13 is formed of a plurality of thin metal wires 12 and includes a mesh-like pattern including a plurality of openings T formed by the crossing thin metal wires 12.
The line width of the thin metal wire 12 is 2.0 μm or less, more preferably 1.5 μm or less, and still more preferably 1.2 μm or less.
The lower limit of the line width of the thin metal wire 12 is not particularly limited, but generally 0.2 μm or more is preferable.
For example, when the conductive film is applied to a touch panel sensor, if the line width of the metal thin wire 12 is 2.0 μm or less, it is more difficult for the user of the touch panel to visually recognize the metal thin wire.

The thickness of the thin metal wire 12 is not particularly limited, but generally 0.1 to 5.0 μm is preferable, and 0.2 to 2.0 μm is more preferable from the viewpoint of conductivity.
The length X of one side of the opening T is preferably 20 to 250 μm.

In FIG. 2C, the opening T has a substantially rhombus shape. However, it is also possible to use polygonal shapes (for example, triangles, quadrangles, hexagons, and random polygons). Further, the shape of one side may be a curved shape or an arc shape other than a linear shape. In the case of the arc shape, for example, the two opposing sides may have an outwardly convex arc shape, and the other two opposing sides may have an inward convex arc shape. Further, the shape of each side may be a wavy line shape in which an outward convex arc and an inward convex arc are continuous. Of course, the shape of each side may be a sine curve.
In addition, in FIG. 2C, although the electroconductive part 13 has a mesh-like pattern, it is not restrict | limited to this form.

<Metal fine wire 12>
FIG. 3 is a partial cross-sectional view of the conductive film 20 (corresponding to a cross-sectional view taken along a line BB in FIG. 2C).
As shown in FIG. 3, the metal thin wire 12 includes the base layer 14 and the conductive layer 16 disposed in this order from the substrate 10 side, and the film 18 covering the periphery of the base layer 14 and the conductive layer 16.
Further, as described above, the line width L2 of the thin metal wire 12 is 2.0 μm or less.

The line width of the thin metal wire 12 can be obtained by embedding the thin metal wire 12 together with the substrate 10 in a resin and cutting it with an ultramicrotome in the width direction (direction orthogonal to the extending direction of the thin metal wire 12). After depositing carbon on the cross section, a line width measured by observing with a scanning electron microscope (S-5500 manufactured by Hitachi High-Technologies Corporation) is intended. When the line width differs in the height direction, the largest measurement width is defined as the line width.

(Base layer 14)
The underlayer 14 contains a single nickel as a main component. In addition, the said main component intends the component with largest content (mass) among the components contained in the base layer 14. As shown in FIG. Although it does not restrict | limit especially as content of the nickel single-piece | unit in the foundation layer 14, Generally 60 mass% or more is preferable with respect to the foundation layer total mass, and 70 mass% or more is more preferable. The upper limit is not particularly limited, but is 100% by mass. The underlayer 14 has a conductive property and also has a function of improving the adhesion between the substrate 10 and the conductive layer 16.
It does not restrict | limit especially as a formation method of the base layer 14, A well-known formation method can be used. Among them, the sputtering method or the vapor deposition method is preferable in that a layer having a more dense structure can be easily formed.

The thickness of the underlayer 14 is not particularly limited, but is preferably 5 nm or more. When the thickness of the base layer 14 is in the above numerical range, the metal thin wire 12 is more excellent in adhesion to the substrate 10. The upper limit of the thickness of the underlayer 14 is not particularly limited, and is, for example, 50 nm or less.

(Conductive layer 16)
The conductive layer 16 contains copper as a main component. The conductive layer 16 functions as a conductive portion of the thin metal wire 12.
The conductive layer 16 contains copper or an alloy thereof, but the main component is copper, and it is preferable that the content of copper is 90% by mass or more with respect to the total mass of the conductive layer in that the conductivity is more excellent. . The main component is intended to mean the metal having the largest content (mass) of the metals contained in the conductive layer 16. Further, the upper limit of the content of copper in the conductive layer 16 is not particularly limited, and is, for example, 100% by mass with respect to the total mass of the conductive layer.

In general, the thickness of the conductive layer 16 is preferably 3.0 μm or less, more preferably 2.0 μm or less, and still more preferably 1.0 μm or less. The lower limit of the thickness of the conductive layer 16 is not particularly limited, but in general, 0.1 μm or more is preferable.

The conductive layer 16 may be a single layer or multiple layers.
When the conductive layer 16 is a single layer, it can be formed, for example, by sputtering or vapor deposition.
Still, when the conductive layer 16 is a multilayer, the conductive layer 16 is, for example, a seed layer formed by a sputtering method, a vapor deposition method, or an electroless plating method in that the conductivity of the metal fine wire 12 is more excellent; It is preferable to have the plating layer arrange | positioned by the plating method on the said seed layer.
In addition, an electroplating method and an electroless plating method are mentioned as a plating method, The electrolytic plating method is preferable from the point of productivity.

The thickness of the seed layer is not particularly limited, but in general, 300 nm or less is preferable. The lower limit of the thickness of the seed layer is not particularly limited, but generally 30 nm or more is preferable.
The thickness of the plating layer is not particularly limited, but generally 3.0 μm or less is preferable, 2.0 μm or less is more preferable, and 1.0 μm or less is still more preferable. The lower limit of the thickness of the plating layer is not particularly limited, but in general, 0.1 μm or more is preferable.

It does not restrict | limit especially as a metal contained in the said seed layer, A well-known metal can be used.
The seed layer may include, for example, metals such as copper, nickel, chromium, lead, gold, silver, tin, and zinc, and alloys of these metals.
The main component (so-called, main metal) contained in the seed layer is preferably a metal other than nickel, and examples thereof include copper, chromium, lead, gold, silver, tin and zinc. In addition, the said main component intends metal whose content (mass) is the largest among metals contained in the said seed layer.
Among them, the seed layer preferably contains copper or an alloy thereof, in that the seed layer is superior in affinity to the plating layer and / or in that the function as a seed layer is more excellent. The main component of the seed layer is preferably copper.

The content of the metal constituting the main component in the seed layer is not particularly limited, but generally, the content of the metal is preferably 80% by mass or more, and more preferably 85% by mass or more based on the total mass of the seed layer. .

As a metal contained in the said plating layer, copper or its alloy is preferable.
As a main component (so-called, main metal) contained in the said plating layer, copper is preferable. In addition, the said main component intends the metal with largest content (mass) among the metals contained in the said plating layer.

The content of copper constituting the main component in the plating layer is not particularly limited, but generally, the content of the metal is preferably 80% by mass or more, more preferably 90% by mass or more based on the total mass of the plating layer. Preferably, 100% by mass is more preferable.

(Coating 18)
The film 18 contains a metal selected from metals which are electrochemically nobler than nickel, and has a thickness L3 of less than 100 nm.
The metal selected from metals which are electrochemically more noble than nickel is intended to be a metal whose ionization tendency is lower than that of nickel, for example, tin, lead, antimony, bismuth, copper, mercury, silver, palladium, iridium, platinum , And gold.
The film 18 preferably contains a metal selected from metals which are electrochemically nobler than silver, in that the adhesion of the fine metal wire 12 to the substrate 10 is excellent over a long period of time, and the visibility is further improved by blackening. It is more preferable to contain palladium in that the effect is also obtained. Preferably, the film 18 contains a metal selected from metals which are more electrochemically noble than nickel. The main component is intended to be the component having the largest content (mass) among the components contained in the film 18.
The content of the metal selected from the metals which are electrochemically more noble than nickel in the film 18 is not particularly limited, but generally, the content of the metal is 80% by mass or more based on the total mass of the film 18 Is preferable, 90 mass% or more is more preferable, and 100 mass% is still more preferable.
In addition, when the film 18 contains silver as a metal selected from metals that are electrochemically nobler than nickel, migration may occur in the metal thin wire 12. Therefore, the film 18 preferably contains a metal other than silver.

The thickness L3 (see FIG. 3) of the film 18 is less than 100 nm. The metal selected from metals electrochemically nobler than nickel contained in the film 18 has poor adhesion to the substrate 10 as compared to nickel. When the thickness L3 of the film 18 is 100 nm or more, the contact surface of the underlayer 14 with the substrate 10 is relatively reduced, and the adhesion of the underlayer 14 to the substrate 10 is reduced.
70 nm or less is preferable and 50 nm or less is more preferable at the point which the adhesiveness of the base layer 14 with respect to the board | substrate 10 is more excellent especially in thickness L 3 of the film | membrane 18.
The lower limit of the thickness L3 of the film 18 is, for example, 10 nm or more. The thickness L3 of the film 18 is preferably 20 nm or more, in that the adhesion of the thin metal wire 12 to the substrate 10 is excellent over a long period of time.

Here, the thickness L3 of the film 18 is intended to be a thickness obtained by elemental mapping using an EDS (Energy dispersive X-ray spectrometry) detector. Specifically, the thickness L3 of the film 18 is measured by the following method.

First, C (carbon) vapor deposition and Pt coating are performed on the conductive portion of the conductive film to impart conductivity and protect the surface. Next, the metal thin wire is cut in the width direction (direction orthogonal to the extending direction of the metal thin wire) using a Helios 400 type FIB-SEM (FIB: Focused Ion Beam, SEM: Scanning Electron Microscope) composite machine manufactured by FEI.
Then, using the obtained section, EDS analysis is performed at an acceleration voltage of 200 kV with an EDS detector (HD2300 type FE-STEM manufactured by Hitachi High-Technologies Corporation). In the element mapping obtained by EDS analysis, the thickness of the distribution region of a metal atom selected from metals which are electrochemically more noble than nickel is measured for each of the films disposed at both ends of the section, The average value is taken as the thickness of the film.

The formation method of the film 18 is not particularly limited, and a known formation method can be used, and among them, the substitution blackening treatment method is preferable.
The substitutional blackening treatment is a reaction utilizing the difference in ionization tendency among metals. According to the substitutional blackening treatment method, it is possible to form a film of a metal which is more electrochemically noble than nickel (in other words, a metal having a smaller ionization tendency) than the nickel. In addition, the thickness of a film can be suitably adjusted with the processing time etc. of a substitution blackening treatment method.
As a result, the film 18 can be disposed on the side surface portion 14 a of the underlayer 14.

<< Second Embodiment >>
Below, 2nd Embodiment of the electroconductive film of this invention is described. In addition, 2nd Embodiment of the electroconductive film of this invention differs from 1st Embodiment of the electroconductive film of this invention only in the position where a film | membrane is arrange | positioned. Therefore, about 2nd Embodiment of the electroconductive film of this invention, only the structure of a metal fine wire is demonstrated and it abbreviate | omits about description other than that.
FIG. 4 shows a partial cross-sectional view of a second embodiment of the conductive film of the present invention. Note that FIG. 4 corresponds to a cross-sectional view taken along the line BB in FIG. 2C.

As shown in FIG. 4, the fine metal wires 32 in the conductive film 40 have a base layer 34 and a conductive layer 36 disposed in this order from the substrate 10 side, and a film 38 for covering the side surface portion 34 a of the base layer 34; including. Specifically, in the metal thin wire 32, the conductive layer 36 is disposed on the surface 34b formed of the base layer 34 and the film 38 covering the side surface portion 34a of the base layer 34. That is, in the metal thin wire 32, the film 38 is not disposed so as to cover the periphery of the underlayer 34 and the conductive layer 36, and the film 38 is disposed only on the side surface portion 34a of the underlayer 34. Further, in the metal thin wire 32, the line width L4 is 2.0 μm or less. Further, the thickness L5 of the film 38 is less than 100 nm. The measurement method of the line width L4 and the thickness L5 is measured by the same method as the line width L2 and the thickness L3, respectively.

[Method of producing conductive film]
The manufacturing method in particular of the electroconductive film mentioned above is not restrict | limited, A well-known method is employable.
Below, the manufacturing method of the conductive film 20 shown in FIG. 3 is mentioned as an example, and the manufacturing method of the conductive film of this invention is demonstrated.
The method of manufacturing the conductive film 20 includes the following steps in this order.
(1) A step of forming a base film on at least one of the main surfaces of a substrate (base film forming step)
(2) Step of forming a second metal film on the above-mentioned base film (second metal film forming step)
(3) A step of forming a resist film having an opening in a region where a metal fine wire is formed on the second metal film (resist film formation step)
(4) Step of forming a first metal film on the second metal film in the opening by plating (first metal film forming step)
(5) Step of removing resist film (resist film removing step)
(6) A step of removing a part of the second metal film and the base film by using the first metal film as a mask (a step of removing the second metal film and the base film)
(7) Process of forming a film by substitution blackening treatment (film forming process)
Hereinafter, the procedure of each of the above steps will be described in detail with reference to FIGS. 5A to 5G.

<< Base film formation process >>
The base film forming step is a step of forming a base film on at least one main surface of the substrate. Specifically, as shown in FIG. 5A, the base film 44 is formed on the substrate 10 by performing this process.
As described later, the base film 44 becomes the base layer 14 shown in FIG. 3 after predetermined processing.
The method for forming the underlayer 44 is not particularly limited, and any known method can be used. Among them, the sputtering method or the vapor deposition method is preferable in that a layer having a more dense structure can be easily formed.
The substrate 10 is as described above.
The base film 44 is a film to be the base layer 14 and is a film mainly composed of nickel. The definition of the main component is as described for the base layer 14.

<< Second metal film formation process >>
The second metal film forming step is a step of forming a second metal film on the base film.
Specifically, as shown in FIG. 5B, the second metal film 46a is formed on the base film 44 by performing this process.
As described later, the second metal film 46a functions as a seed layer in the plating method.
As the metal contained in the second metal film 46a, a conductive layer having a predetermined composition may be formed, and examples thereof include the metals contained in the above-described seed layer.

The method of forming the second metal film 46a is not particularly limited, and any known method may be used, among which sputtering, vapor deposition, or electroless plating is preferable in that it is easy to form a layer having a more dense structure. The method is preferred.

<< Resist film formation process >>
The resist film forming step is a step of forming a resist film having an opening in a region where a metal thin wire is to be formed. Specifically, as shown in FIG. 5C, by performing this process, a resist film 47 is formed on the second metal film 46a.

The resist film 47 has an opening 49 in the region where the metal thin wire is to be formed.
The region of the opening 49 in the resist film 47 can be appropriately adjusted in accordance with the region in which the thin metal wire is to be disposed. For example, in the case of forming metal thin wires arranged in a mesh, a resist film having openings in a mesh is formed. In addition, normally, the opening is formed in a thin wire shape in accordance with the thin metal wire.
The line width W of the opening is 2.0 μm or less. The line width W is preferably 1.5 μm or less, and more preferably 1.2 μm or less. By setting the line width W of the opening to 2.0 μm or less, thin metal wires having a line width can be obtained. In particular, when the line width W of the opening is 1.2 μm or less, the line width of the obtained metal thin line becomes narrower, and when the conductive film is applied to a touch panel sensor, for example, the metal thin line It is hard to see. The lower limit of the line width W of the opening is not particularly limited, but is often 0.2 μm or more.
In the present specification, the width of the opening means the size of the thin line portion in the direction orthogonal to the extending direction of the thin line portion of the opening. Through each process described later, fine metal wires having a line width corresponding to the line width of the opening are formed.

The method of forming the resist film 47 on the second metal film 46a is not particularly limited, and a known resist film forming method can be used. For example, there is a method including the following steps.
(A) A step of applying a composition for forming a resist film on the second metal film 46 a to form a composition layer for forming a resist film.
(B) exposing the resist film-forming composition through a photomask provided with a pattern-like opening;
(C) developing the resist film-forming composition after exposure to obtain a resist film.
In addition, between the said process (a) and (b), between (b) and (c), and / or after (c), the composition layer for resist film formation and / or a resist film are heated. The process may be further included.

Step (a)
It does not restrict | limit especially as a composition for resist film formation which can be used in the said process (a), A well-known composition for resist film formation can be used.
As a specific example of a composition for resist film formation, a positive or negative radiation sensitive composition is mentioned, for example.

It does not restrict | limit especially as a method to apply | coat the composition for resist film formation on the 2nd metal film 46a, A well-known application method can be used.
As a coating method of the composition for resist film formation, a spin coat method, a spray method, a roller coat method, an immersion method etc. are mentioned, for example.

After forming the composition layer for forming a resist film on the second metal film 46a, the composition layer for forming a resist film may be heated. By heating, the unnecessary solvent remaining in the composition layer for forming a resist film is removed, and the composition layer for forming a resist film can be made uniform in the plane.
Although it does not restrict | limit especially as a method to heat the composition layer for resist film formation, For example, the method to heat a board | substrate is mentioned.
The temperature of the heating is not particularly limited, but generally 40 to 160 ° C. is preferable.

The thickness of the composition layer for forming a resist film is not particularly limited, but in general, the thickness after drying is preferably 0.5 to 2.5 μm.

・ Step (b)
It does not restrict | limit especially as a method to expose the composition layer for resist film formation, A well-known exposure method can be used.
As a method of exposing the composition layer for forming a resist film, for example, a method of irradiating the composition layer for forming a resist film with an actinic ray or radiation through a photomask provided with a pattern-like opening can be mentioned. . The exposure dose is not particularly limited, but in general, irradiation at 1 to 100 mW / cm ² for 0.1 to 10 seconds is preferable.

For example, when the composition for forming a resist film is a positive type, the line width W of the pattern opening provided in the photomask used in the step (b) is generally preferably 2.0 μm or less, and 1.5 μm or less Is more preferable, and 1.2 μm or less is more preferable.

The composition layer for forming a resist film after exposure may be heated. The heating temperature is not particularly limited, but generally 40 to 160 ° C. is preferable.

・ Step (c)
It does not restrict | limit especially as a method to develop the composition layer for resist film formation after exposure, A well-known developing method can be used.
Examples of known development methods include methods using a developer containing an organic solvent or an alkali developer.
Examples of the development method include a dip method, a paddle method, a spray method, and a dynamic dispensing method.

In addition, the resist film after development may be washed using a rinse solution. The rinse solution is not particularly limited, and known rinse solutions can be used. Examples of the rinse solution include organic solvents and water.

<< First metal film formation process >>
The first metal forming step is a step of forming the first metal film on the second metal film by the plating method in the opening of the resist film. Specifically, as shown in FIG. 5D, by performing this process, the first metal film 46b is formed on the second metal film 46a so as to fill the opening 49 in FIG. 5C.

The first metal film 46 b is formed by plating.
A well-known plating method can be used as a plating method. Specifically, electrolytic plating and electroless plating may be mentioned, and electrolytic plating is preferred from the viewpoint of productivity.
As a metal contained in the first metal film 46b, a conductive layer having a predetermined composition may be formed, and examples thereof include the metals contained in the above-described plating layer.

<< Resist film removal process >>
The resist film removing step is a step of removing the resist film 47. Specifically, as shown in FIG. 5E, by carrying out the present step, a stack including the substrate 10 and the base film 44, the second metal film 46a, and the first metal film 46b on the substrate 10 is provided. Get the body.

The method for removing the resist film 47 is not particularly limited, and a known method for removing the resist film 47 using a resist film removing solution may be mentioned.
Examples of the resist film removing solution include organic solvents and alkaline solutions.
The method for contacting the resist film removing solution with the resist film is not particularly limited, and examples thereof include a dip method, a paddle method, a spray method, and a dynamic dispensing method.

<< Second metal film and underlayer removal process >>
The second metal film and the underlayer film removing step is a step of removing a part of the second metal film and the underlayer film using the first metal film as a mask. Specifically, as shown in FIG. 5F, by performing this process, the base film 44 and the second metal film 46a corresponding to the area where the first metal film 46b is not formed are removed.

There is no particular limitation on the method of removing a part of the base film 44 and the second metal film 46a, but a known etching solution can be used.
Examples of known etching solutions include ferric chloride solution, cupric chloride solution, alkaline ammonia solution, sulfuric acid-hydrogen peroxide mixed solution, and phosphoric acid-hydrogen peroxide mixed solution. Among these, an etching solution which does not easily dissolve the first metal film 46 b and easily dissolves the base film 44 and the second metal film 46 a may be selected appropriately. In addition, the etching solution may be changed for each layer of the base film 44 and the second metal film 46a to perform multi-step etching.

<< Coating formation process >>
The film forming step is a step of forming a film in a region including at least the side surface portion of the base film by substitution blackening treatment. Specifically, by carrying out this step, a region including at least the side surface portion of the base film 44 (in the method of manufacturing the conductive film 20, the base film 44, the second metal film 46a, and the first metal film 46b) Side surface portion is blackened, and as shown in FIG. 5G, on the substrate 10, the base layer 14, the conductive layer 16 including the second metal film 46a and the first metal film 46b, and the base layer A coating 18 covering the periphery of the conductive layer 14 and the conductive layer 16 is formed. The conductive layer 16 and the film 18 in FIG. 5G correspond to the conductive layer 16 and the film 18 in FIG. 3, respectively. That is, the thin metal wires 12 shown in FIG. 3 are obtained through the film forming step.

The substitutional blackening treatment is a reaction utilizing the difference in ionization tendency among metals. According to the substitution blackening treatment method, nickel on the side portion of the underlayer can be replaced with a metal that is more electrochemically noble than nickel (in other words, a metal having a smaller ionization tendency).
As a specific method of the substitutional blackening treatment method, the above-mentioned laminate obtained through the second metal film and the base film removing step is immersed in an aqueous solution containing metal ions having a smaller ionization tendency than nickel. As a result, in the side surface portion in the base film 44 (corresponding to the surface area of the base film 44 in contact with the above aqueous solution), the nickel constituting the layer is dissolved to form nickel ions to emit electrons. The electrons reduce a metal having a small ionization tendency contained in the aqueous solution, whereby a metal having a small ionization tendency is deposited on the side portion of the base film 44. As a result, as shown in FIG. 5G, the film 18 can be disposed on the side surface of the base layer 14.
When the thin film 12 covers the periphery of the conductive layer 16 as well as the side surface portion 14a of the base layer 14 as in the metal thin wire 12 shown in FIG. 3, the nickel contained in the base layer 14 is mainly contained in the first metal film 46b. The laminate obtained through the second metal film and the base film removing step in an aqueous solution containing a metal ion as a component and a metal ion whose ionization tendency is smaller than that of the metal as the main component of the second metal film 46a. do it. The metal as the main component of the first metal film 46 b and the metal as the main component of the second metal film 46 a are preferably both copper, and in this case, as the metal ion, it is preferable to use silver. Also, metal ions having a smaller ionization tendency are preferable, and palladium ions are more preferable.
The liquid temperature of the solution at the time of immersion is not particularly limited, but usually 10 to 90 ° C., preferably 20 to 60 ° C.
The pH of the solution at the time of immersion is not particularly limited, but it is preferably 0 to 13, and more preferably 0 to 8.
The immersion time is not particularly limited, but is usually 1 to 8 minutes.

In addition, the specific method in particular of a substitution blackening treatment method is not restrict | limited, A well-known method and a process liquid can be used. For example, the composition for blackening treatment described in patent publication 586 2916 can be used.

The conductive film 20 can be formed through the above steps.
The conductive film 40 shown in FIG. 4 can also be manufactured by the same method.
When a coating is not formed around the conductive layer 36 as in the thin metal wire 32 shown in FIG. 4 and only the side surface portion 34 a of the base layer 34 is covered with the coating 38, the ionization tendency is lower in the coating forming step. A second metal film and an aqueous solution containing a metal ion smaller than nickel contained in 14 and larger than the metal main component of the first metal film 46 b and the metal main component of the second metal film 46 a What is necessary is just to immerse the said laminated body obtained through the formation film removal process. Preferably, the metal as the main component of the first metal film 46b and the metal as the main component of the second metal film 46a are both copper, and in this case, tin, as the metal ion, is used. Lead, antimony, bismuth and the like can be mentioned.

[Use]
The conductive film of the present invention can be used in various applications. For example, various electrode films, heat generating sheets, and printed wiring boards can be mentioned. Among them, the conductive film is preferably used for a touch panel sensor, and more preferably used for a capacitive touch panel sensor. In the touch panel including the conductive film as a touch panel sensor, it is difficult for a thin metal wire to be visible.
Examples of the configuration of the touch panel include the touch panel module described in paragraphs 0020 to 0027 of JP-A-2015-195004, and the above contents are incorporated in the present specification.

Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, proportions, treatment contents, treatment procedures and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as limited by the following examples.

Example 1
On a PET (polyethylene terephthalate) film, a Ni film having a thickness of 20 nm was formed as a base film using a sputtering apparatus. Next, using a sputtering apparatus, a Cu film (second metal film) having a thickness of 50 nm was formed as a seed film on the Ni film.
Next, on the second metal film, a positive resist (MCP R 124 MG manufactured by Rohm and Haas Electronic Materials Co., Ltd.) was applied by a spin coater so as to have a thickness of 1 μm, and dried at 90 ° C. for 10 minutes. After irradiating a light of 365 nm wavelength (exposure amount: 16 mw / cm ² ) for 2 seconds using a parallel exposure machine through a photomask, the resist film is developed by developing with a 0.10 M sodium hydroxide aqueous solution. Obtained (line width of the opening of the resist film: 1.5 μm ± 0.1 μm). Next, the entire surface of the resist was exposed (3 seconds at an exposure amount of 16 mW / cm ² ) for later peeling.
Next, electroplating is performed at a current density of 3 A / dm ² using a copper sulfate high-throw bath (including Top Lucina HT-A and Top Lucina HT-B as additives, each of which is manufactured by Okuno Pharmaceutical Industry Co., Ltd.) The Cu plating film (1st metal film) formed so that a part was filled was obtained. The resist was peeled off with a 0.15 M aqueous solution of sodium hydroxide, and then the second metal film in the opening was removed with a Cu etching solution (Cu etchant manufactured by Wako Pure Chemical Industries, Ltd.). The underlayer was etched with a Ni etching solution (NC-A and NC-B manufactured by Nippon Chemical Industrial Co., Ltd.).
Finally, a surface treatment is carried out with a Pd solution (example 1 of Patent No. 586 2916, prepared with reference to blackening solution No. 2) at room temperature for 3 minutes to form a film (Pd layer), whereby the conductivity is achieved. A film was obtained (line width of 1 μm ± 0.1 μm of fine metal wire). The thickness of the film (corresponding to L3 in FIG. 3) in this example was 40 nm.

That is, in the conductive film of Example 1 obtained by the above steps, the metal thin wires formed on the substrate are the base layer and the conductive layer disposed in this order from the substrate side, and the periphery of the base layer and the conductive layer. And a coating to be coated.
In addition, the conductive layer contains copper as a main component (the content of copper is specifically 90% by mass or more with respect to the entire conductive layer). The conductive layer is composed of the first metal film and the second metal film.
The underlayer is made of Ni alone.
Also, the film contains palladium.

(Line width of thin metal wire)
The line width of the thin metal wire in the produced conductive film was measured by the following method.
First, the above conductive film is embedded in a resin together with the substrate, cut with an ultramicrotome in the width direction (direction orthogonal to the extending direction of the metal fine wire), and carbon is deposited on the obtained cross section , And was observed using a scanning electron microscope (S-5500 manufactured by Hitachi High-Technologies Corporation). When the line width differs in the height direction, the largest measurement width is defined as the line width.

(Thickness of film)
The thickness of the film of the metal fine wire in the produced conductive film was measured by the following method.
First, C deposition and Pt coating were performed on the conductive part of the conductive film for conductivity imparting and surface protection. Subsequently, the metal thin wire was cut in the width direction (direction orthogonal to the extending direction of the metal thin wire) using a Helios 400 type FIB-SEM (FIB: Focused Ion Beam, SEM: Scanning Electron Microscope) composite machine manufactured by FEI.
Then, using the obtained section, EDS analysis was performed at an acceleration voltage of 200 kV with an EDS detector (HD2300 type FE-STEM manufactured by Hitachi High-Technologies Corporation). In element mapping obtained by EDS analysis, the thickness of the distribution region of Pd atoms was measured one by one for each of the films disposed at both ends of the section, and the average value was taken as the thickness of the film.

The obtained conductive film was exposed to 85 ° C. and 85% Rh conditions for 168 hours.
Next, the tape adhesion test shown below was implemented with respect to the conductive film after exposing to the conditions of 85 degreeC 85% Rh for 168 hours.
As a result, peeling of the thin metal wires arranged in a mesh was not seen.

(Tape adhesion test (adhesion evaluation to substrate))
The adhesion of the metal thin line to the substrate was evaluated by a tape adhesion test.
A cellophane tape film ("CT24" manufactured by Nichiban Co., Ltd.) is pressed against the main surface of the substrate provided with metal fine wires using a conductive film produced by the above method and then adhered with a finger pad, and then cellophane tape Peeled off. Thereafter, the peeled area (%) of the metal thin wire on the substrate (area of peeled metal thin wire / area of metal thin wire in test piece × 100) was visually confirmed.

Example 2
The procedure was carried out in the same manner as in Example 1 except that a COP (cycloolefin polymer) film was used as a substrate. That is, the second embodiment is different from the first embodiment only in the type of the substrate.
Moreover, the tape adhesion test was implemented with respect to the electroconductive film after 168 hours of exposure conditions of 85 degreeC 85% Rh similarly to Example 1. FIG.
As a result, peeling of the thin metal wires arranged in a mesh was not seen. The thickness of the film (corresponding to L3 in FIG. 3) in this example was 40 nm.

[Example 3]
Everything was carried out in the same manner as in Example 1 except that the surface treatment was carried out for 5 minutes. In other words, Example 3 is different from Example 1 only in the thickness of the film.
Moreover, the tape adhesion test was implemented with respect to the electroconductive film after 168 hours of exposure conditions of 85 degreeC 85% Rh similarly to Example 1. FIG.
As a result, peeling of the thin metal wires arranged in a mesh was not seen. The thickness of the film (corresponding to L3 in FIG. 3) in this example was 80 nm.

Example 4
The second metal film was performed in the same manner as in Example 1 except that a Cu—Zn alloy film (component ratio 85: 15 (mass ratio) of a sputtering target) was used instead of the Cu film. In other words, the fourth embodiment is different from the first embodiment only in the type of the second metal film.

In the conductive film of Example 4 obtained by the above steps, the conductive layer contains copper as a main component (the content of copper is specifically 90% by mass or more with respect to the entire conductive layer). is there). The conductive layer is composed of the first metal film and the second metal film.

Moreover, the tape adhesion test was implemented with respect to the electroconductive film after exposing to the conditions of 85 degreeC 85% Rh for 168 hours similarly to Example 1. FIG.
As a result, peeling of the thin metal wires arranged in a mesh was not seen. The thickness of the film (corresponding to L3 in FIG. 3) in this example was 40 nm.

[Example 5]
The procedure was carried out in the same manner as in Example 4 except that a COP film was used as a substrate. That is, the fifth embodiment is different from the fourth embodiment only in the type of the substrate.
Moreover, the tape adhesion test was implemented with respect to the electroconductive film after exposing to the conditions of 85 degreeC 85% Rh for 168 hours similarly to Example 1. FIG.
As a result, peeling of the thin metal wires arranged in a mesh was not seen. The thickness of the film (corresponding to L3 in FIG. 3) in this example was 40 nm.

Comparative Example 1
It carried out like Example 1 except not having implemented surface treatment by Pd solution.
That is, the conductive film of the comparative example 1 is a structure which does not have a film.
Moreover, the tape adhesion test was implemented with respect to the electroconductive film after exposing to the conditions of 85 degreeC 85% Rh for 168 hours similarly to Example 1. FIG.
As a result, 50% or more of the metal thin wires arranged in a mesh were peeled off.

Comparative Example 2
Everything was carried out in the same manner as in Example 1 except that the surface treatment was carried out for 10 minutes.
That is, the conductive film of Comparative Example 1 has the same configuration as the conductive film of Example 1 except that the thickness of the film is 100 nm.
Immediately after preparation, the above-mentioned tape adhesion test was conducted, and peeling was observed in an area range of 3% or less of the metal thin wires arranged in a mesh shape.
Moreover, when the tape adhesion test was implemented with respect to the electroconductive film after 168 hours of exposure to 85 degreeC 85% Rh conditions similarly to Example 1, it arrange | positioned in mesh shape similarly to immediately after preparation. Peeling was observed in the area range of 3% or less of the metal thin wire.
The thickness of the film (corresponding to L3 in FIG. 3) in this example was 100 nm.

From the above results, it was confirmed that the conductive film of the example had excellent adhesion to the substrate over a long period of time while the line width was 2.0 μm or less.

10, 100, substrate 102 base metal layer 104 first metal layer 106 second metal layer 110 transparent conductive film L1, L2, L4 line width of metal fine wire 102a side portion of base metal layer 102 12, 32, 108 metal fine wire 13 conductive Part 14, 34 Base layer 16, 36 Conductive layer 18, 38 Coating 20, 40 Conductive film 14a Side layer of base layer 14 34a Side layer of base layer 34b Surface L3 Thickness of coating 18 Thickness L of coating 38 T opening X length of one side of opening T 44 base film 46 a first metal film 46 b second metal film 47 resist film 49 opening W line width of opening

Claims (7)

1. A conductive film comprising: a substrate; and a conductive portion disposed on at least one of the main surfaces of the substrate, the conductive portion being composed of fine metal wires,
   The metal fine wire includes an underlayer and a conductive layer disposed in this order from the substrate side, and a film covering the side surface of the underlayer, and the line width is 2.0 μm or less.
   The underlayer contains a simple substance of nickel as a main component,
   The conductive layer contains copper as a main component,
   The conductive film, wherein the film contains a metal selected from metals which are electrochemically nobler than nickel, and has a thickness of less than 100 nm.
2. The conductive film according to claim 1, wherein the film contains a metal selected from metals that are electrochemically nobler than silver.
3. The conductive film according to claim 1, wherein the film contains palladium.
4. The conductive film according to any one of claims 1 to 3, wherein the line width of the fine metal wire is 1.2 μm or less.
5. The conductive film according to any one of claims 1 to 4, wherein the conductive layer contains 90% by mass or more of copper based on the total mass of the layer.
6. A touch panel sensor comprising the conductive film according to any one of claims 1 to 5.
7. A touch panel comprising the touch panel sensor according to claim 6.

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