JP5888255B2 - Electrode film, method for producing the same, and image display device - Google Patents

Description

  The present invention relates to an electrode film, and more particularly, to an electrode film having a conductive mesh in which an electrode has a low resistance and a conductive wire forming the electrode is thinned. Moreover, this invention relates to the manufacturing method of this electrode film, the touchscreen using this electrode film, the image display apparatus which has arrange | positioned this touchscreen, etc.

  In recent years, touch panels have become widespread as input devices for various electronic devices. Various types of touch panels such as a resistive film type and a capacitance type have been put into practical use.

A touch panel generally has a transparent conductive film made of an ITO (indium tin oxide) thin film formed on one surface of a transparent substrate made of a glass plate, a polyethylene terephthalate film, or the like as an electrode member for a touch panel. Is used (Patent Document 1).
However, the transparent conductive film made of an ITO thin film is expensive because a rare metal (rare earth element) called indium is used, and the resistance (surface resistivity) is high in order to increase the area of the touch panel. At some point, it is difficult to meet the demands for cost reduction and large screen.

Therefore, an electrode member for a touch panel in which a metal mesh composed of a fine metal wire pattern is formed on a transparent base material instead of the ITO thin film transparent conductive film has been proposed (Patent Document 2). According to the metal mesh, the cost and the resistance can be reduced as compared with the ITO thin film.
In addition, the metal mesh of this electrode for touch panels has recently been demanded to make the electrode finer in terms of visibility and high transmittance with the increase in image quality and the spread of portable small terminals called tablets. Has been.

  When this metal mesh electrode is used as an electrode for a touch panel, invisibility becomes a problem as compared with a transparent electrode made of an ITO thin film. Therefore, the metal mesh electrode needs to be thinned in order to improve the invisibility and to increase the transmittance. Moreover, since the metal layer which forms a mesh pattern exhibits a comparatively high reflectance, external light is reflected, a mesh pattern is visually recognized, and the image contrast of a touch panel apparatus will fall. Therefore, the blackening layer is disposed on the observer side of the metal layer. This blackening layer improves the invisibility of the mesh pattern, improves the image contrast, and improves the visibility of the image.

Such a touch panel electrode is formed by first laminating a metal thin film and a blackened layer on a transparent substrate, and then patterning the metal thin film and the blackened layer by etching using a photolithography technique. It is fabricated by forming an electrode.
There is also a method of patterning only a metal thin film and forming a blackened layer using a method such as electroless plating.

However, the blackening layer made of metal oxide, nitride, sulfide, etc., such as copper oxide, usually formed with a thickness of 0.5-1 μm, composed of alloy or metal oxide, nitride, sulfide is copper Compared to pure metal thin films, etc., the corrosion rate during etching is slow. For this reason, when thin wires are produced by patterning using photolithography technology, erosion due to etching is slow in the blackened layer portion, and when reaching the metal thin film portion, not only in the depth direction (thickness direction) but also in the lateral direction Erosion also proceeds in the (surface direction). Normally, there is no problem when a thick copper layer is provided. However, when a thin copper layer is provided, the cross-sectional shape of the thin conductor becomes an inversely tapered shape due to this side etching phenomenon. Due to the side etching, the variation in the mesh line width becomes large, and further, the sensor pattern line portion (wire flange portion) is disconnected.
Such a problem becomes more apparent when thinning a desired metal mesh electrode, particularly when a metal mesh having a line width of less than 10 μm is manufactured, because the possibility of disconnection increases as the wire becomes thinner.

JP 2008-310551 A JP 2011-134311 A

  The present invention has been made under such circumstances, and its object is to form a copper film and a blackened metal film formed on a transparent substrate by patterning them by etching using a photolithography technique. An electrode film comprising a fine metal mesh comprising a copper layer and a blackened metal layer, wherein the electrode has a reverse taper shape, the variation in mesh line width is small, and there is no fine wire metal mesh, And a manufacturing method thereof, a touch panel using the electrode film, an image display device in which the touch panel is arranged on a display surface, and the like.

  As a result of various studies, the inventor of the present invention, in the production of a fine metal mesh electrode composed of a copper layer and a blackened metal layer, has a blackened metal layer whose corrosion rate is slower than that of copper. It has been found that the object of the present invention can be achieved by setting the thickness of the metal halide layer in a specific thin numerical range.

That is, the present invention
(1) An electrode film provided with a transparent substrate and a conductor mesh provided on the transparent substrate, the conductor mesh being provided on the copper layer having a thickness of 0.1 to 5 μm An electrode film comprising a blackened metal layer having a thickness of 0.01 to 0.4 μm and a slower corrosion rate than copper;
(2) The cross-sectional shape in the thickness direction of the conductor mesh is
Width of the top (W ₂ )> Width of the buttock (W ₁ )
The electrode film according to (1), which has a reverse tapered shape,
(3) The variation in the line width of the line portion of the conductor mesh pattern is
Swing width from average line width (2ΔW) / average line width (W) ≦ 0.4
The electrode film according to (1) or (2),
(4) A copper film, a blackened metal film, and a resist film are sequentially provided on a transparent substrate, the resist film is patterned and developed by pattern exposure and development, and then the blackened metal is formed using the patterned resist pattern layer as a mask A method for producing the electrode film according to any one of (1) to (3), wherein the film and the copper film are etched to form a blackened metal layer and a copper layer, and then the resist pattern layer is removed;
(5) A touch panel including the electrode film according to any one of (1) to (3).
(6) An image display device in which the touch panel according to (5) is arranged on a display surface,
(7) An image display device in which the electrode film according to any one of (1) to (3) is attached to the front surface of the display as an electromagnetic shielding material,
(8) The transparent antenna which stuck the electrode film in any one of said (1)-(3) on the front surface,
Is to provide.

  According to the present invention, in an electrode film provided with a fine wire metal mesh in which a copper layer and a blackened metal layer are laminated, the electrode film is provided with a fine wire metal mesh having a small variation in mesh line width and no disconnection, and A touch panel using the electrode film, an image display device in which the touch panel is arranged on a display surface, and the like can be provided.

It is a schematic sectional drawing which shows the structure of the electrode film of this invention. It is a figure which shows the cross-sectional shape of the metal mesh electrode of this invention. It is a top view which shows the variation in the line | wire width of the line part of the pattern of the metal mesh electrode of this invention. It is a figure for demonstrating the manufacturing method of the electrode film of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are conceptual diagrams, and the scale relations, aspect ratios, and the like of components may be exaggerated as appropriate for convenience of explanation.
In the following, for a film or layer, a pattern formed in a specific shape such as a mesh is referred to as a “layer”, and a form formed over the entire surface before being patterned is referred to as a “film”. It is called.

[Electrode film]
FIG. 1 is a schematic cross-sectional view showing the configuration of the electrode film of the present invention.
The electrode film 100 includes a transparent substrate 10 and an electrode 20 which is a conductive mesh provided thereon includes a copper layer 21 and a blackened metal layer 22 whose corrosion rate is slower than that of copper.

The transparent substrate 10 is not particularly limited as long as it is a transparent substrate, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, acrylic resin such as polymethyl methacrylate, polyolefin resin such as polypropylene, triacetyl cellulose (cellulose triacetate). ), A resin sheet made of a cellulose resin, a polycarbonate resin, or the like, or a glass such as soda glass, potassium glass, or quartz glass, or a plate made of an inorganic material such as crystalline quartz or fluorite.
In the present invention, the term “film” is used in a broad sense including not only a narrowly defined film but also a so-called thick sheet or sheet.
The thickness of these transparent substrates is selected from a range of about 20 to 3000 μm according to the application, required performance, price, and the like.

The electrode 20 which is a conductor mesh is composed of a copper layer 21 which is a highly conductive metal layer and a blackened metal layer 22 for improving the invisibility of the mesh pattern provided thereon (observer side).
In order to achieve the effects of the present invention, the copper layer needs to have a thickness of 0.1 to 5 μm, more preferably 0.5 to 2.5 μm, and the blackened metal layer has a thickness of 0.01 to 0.00 mm. It needs to be 4 μm.
By making the copper layer thin, it becomes easy to make a thin line. Particularly, a thin line of a copper layer having a line width of 10 μm or less, particularly 7 μm or less can be processed with good shape reproducibility. By thinning in this way, an electrode film having a fine wire metal mesh with little variation in mesh line width and no disconnection can be obtained.

Such a thin copper layer and blackened metal layer are preferably formed by forming a copper film by vapor deposition of copper, and then a blackened metal layer having a slower corrosion rate than copper by sputtering, vapor deposition, plating, etc. Can be obtained by forming a blackened metal film 32 made of an oxide containing copper and then patterning by etching (corrosion) using a photolithography technique as will be described later.
In addition, as a material constituting the blackened metal film (also the blackened metal layer meshed with this), the copper-colored luster due to external light reflection on the surface of the copper film (or the copper layer meshed with this) is visually observed. It is only necessary to appropriately select a material that satisfies processing requirements and various required physical properties of the electrode film from among materials made of a metal that is sufficient to be not visually recognized.
Specifically, an oxide containing copper is typical, and CuO (also called copper oxide (II) or cupric oxide), CuO—Cr ₂ O ₃ , CuO—Fe ₃ O _{4. -Mn 2 O 3, CoO-Fe} 2 O 3 -Cr 2 O 3 and the like. In the material, various elements other than those described in the chemical formula may be appropriately contained as an allowable impurity or as an additive for adjusting blackness and required physical properties. Further, the blackened metal film may contain two or more of the materials.
Other examples include black iron oxide (Fe ₃ O ₄ ), titanium black known as titanium black, and a compound made of titanium oxide.
Note that any of the oxides containing copper listed above has a slower corrosion rate V ^Z (defined as a corrosion distance that proceeds in the thickness direction Z per unit time) than the copper. In particular, this tendency is remarkable when the CuO film is corroded with a ferric chloride aqueous solution.
As a result, in the etching process of the copper film and the blackened metal film, the following problem of amplification of the distribution ΔW of the line width W of the line portion occurs. That is, as shown in FIG. 4D, a copper film 31, a blackened metal film 32 having a slower corrosion rate than copper, and a resist pattern layer 33 are laminated in this order on the transparent substrate 10, and the resist pattern layer 33 is formed. When the electrode film 100 as shown in FIG. 4E is manufactured by corrosive removal of the copper film 31 and the blackened metal film 32 (the transparent base material 10 remains) by corroding the opening of Since the corrosion rate V _black ^{Z in} the thickness direction Z of the metallized metal film 32 is relatively slow, the thickness of the blackened metal film 32 exposed in the copper film opening, the amount of impurities and lattice defects in the blackened metal layer 32, black Due to the influence of factors affecting the progress of the corrosion, such as the concentration and flow rate of the corrosion solution directly above the metallized metal film 32, the time t from when the blackened metal film 32 is completely removed and the corrosion solution reaches the copper film 31 is reached. An in-plane distribution Δt (fast and slow) occurs.
On the other hand, the corrosion rate V _Cu ^Z in the thickness direction Z of the copper film 31 is relatively high,
V _Cu ^Z > V _black ^Z
Therefore, at the time t _{last when the} corrosion of the copper film 31 is completed at the portion where the corrosion solution has finally reached the copper film 31, the width direction X (see FIGS. 3 and 4) orthogonal to the thickness direction is present at the portion. The side etching distance ΔX to) is almost in progress (ΔX≈0).
Therefore, the line width W is kept relatively wide at the portion where the corrosion solution finally reaches the copper film (this portion corresponds to a portion where the width W of the line portion is relatively wide in FIG. 3).
On the other hand, in the portion where the corrosion solution _first reaches the copper film 31 at time t _first , the width direction corrosion solution proceeds in the width direction X at time t _last . When the corrosion rate in the width direction X of the copper film 31 is V _Cu ^X ,
V _Cu ^X ≒ V _Cu ^Z > V _black ^Z
Therefore, the time proportional to the time difference Δt = t _last −t _first between the time when the corrosion solution first reaches the copper film 31 and the time when the corrosion solution finally reaches the copper film 31.
ΔX = Δt × V _Cu ^X = (t _last −t _first ) × V _Cu ^X
Corrosion (width reduction) proceeds in the width direction only.
Therefore, the line width W is relatively narrow in the portion where the corrosion solution first reaches the copper film (this portion corresponds to the portion in which the width W of the line portion is relatively narrow in FIG. 3).
In this case, when the etching process is completed over the entire region, the maximum Δ
Since the side etching proceeds in the width direction X during t = t _last −t _first , although there is a distribution depending on the location of the line part, the shape of the cross section perpendicular to the extending direction of the line part is As shown in FIG. 2A, the width W ₂ of the top portion far from the transparent base material has a reverse taper shape in which the width W _{1 of the} collar portion close to the transparent base material is larger (W ₂ > W ₁ ). .
Note that, in the portion where the corrosion solution finally reached the copper film 31, side etching is almost not advanced at the end of the etching process, so that W ₂ ≈W ₁ and the side etching amount ΔX is
ΔX = ΔX _MIN ≒ 0
It becomes.
In the portion where the corrosion solution first reaches the copper film 31, the side etching amount ΔX is the maximum value.
ΔX = ΔX _MAX = Δt × V _Cu ^X = (t _last −t _first ) × V _Cu ^X
It becomes.
Therefore, the entire conductor mesh includes at least a part (usually most) of a line part having an inversely tapered shape, and the line width W of the line part has a distribution ΔW corresponding to the side etching amount ΔX.

  The electrode of the present invention is a mesh (mesh pattern or lattice pattern) pattern, the line width W of the line portion is a fine line of 2 to 7 μm, and the aperture ratio of the mesh pattern is about 95 to 99%.

FIG. 2 is a diagram showing a cross-sectional shape of the metal mesh electrode of the present invention.
The metal mesh electrode of the present invention has a forward tapered shape such that “the width of the top (W ₂ ) ≦ the width of the heel (W ₁ )” as shown in FIG. 2B and “the width of the top” as shown in FIG. Any of the inverse taper shapes in which (W ₂ )> trench width (W ₁ ) ”is possible.
However, in view of the invisible external light reflection on the side face of the mesh pattern line portion and the simplification of the manufacturing process, a more preferable form is the reverse tapered shape of FIG.
That is, in the case of the reverse taper shape, the side surface of the line portion where the copper layer 21 is exposed without being covered with the blackened metal layer 22 has a characteristic of reflecting external light originally, but as can be seen from FIG. Such a side surface is hidden behind the back surface of the wider blackened metal layer 22, so that the visibility of external light reflection is suppressed. Since the blackened metal layer 22 is formed on the observer side, the observer is used to observe the electrode film from the blackened metal layer 22 side.
In the reverse taper shape (W ₂ > W ₁ ), the top width (W ₂ ) has an average line width of ₂ to 7 μm, and the width of the collar (W ₁ ) is 1 μm from the width of the top (W ₂ ). It is narrow within a range of less than about. The height (H) of the electrode is 0.1 to 5 μm (from the thicknesses of the copper layer and the blackened metal layer).
As described above, such a reverse taper shape is obtained by reducing the thickness of the blackened metal layer to 0.01 to 0.4 μm. This is because the progress of side etching of the penetrated copper portion is suppressed.
In addition, the forward tapered shape is formed by removing the blackened metal film 32 at the opening of the resist pattern layer 33 in FIG. 4D with hydrochloric acid and then using the corrosive liquid such as ferric chloride aqueous solution to form the copper film 31. It can be easily obtained by etching.

FIG. 3 is a top view showing variations in the line width of the line portion of the mesh pattern.
The variation (3σ) in the line width of the line portion of the mesh pattern of the present invention is “the deflection width from the average line width (2ΔW) / the average line width (W) ≦ 0.4”, and the linearity is high. When the line width variation converged in the range of 2ΔW / W, it was confirmed that the disconnection in the thin line region (2 to 7 μm) was not visually recognized. Note that the line width (W) here is evaluated, measured, etc., for the width W _{2 of the} apex that is wider in the case of the inversely tapered shape of FIG. On the other hand, in the case of the forward tapered shape shown in FIG. 2B, evaluation, measurement, and the like are performed for the width W ₁ of the flange portion that is wider.
The distribution ΔW of the line width W of the line portion is larger than the width W ₂ of the top portion and the width W ₁ of the collar portion at 5 or more, preferably 10 to 100 locations of the line portion of the mesh pattern. It is defined as three times the standard deviation σ obtained by measurement (3σ: amplitude of distribution on one side of the average value).
When evaluating the wide and narrow fluctuation range of the line width W itself of the line portion, the fluctuation width (twice the amplitude) 2ΔW = 6σ corresponding to the difference between the maximum value and the minimum value of the width distribution of the line width W evaluate.

[Method for producing electrode film]
FIG. 4 illustrates a method for producing the electrode film of the present invention.

  First, as shown to Fig.4 (a), the transparent base material 10 is prepared.

  Next, as shown in FIG. 4B, a copper film 31 that forms the copper layer 21 of the electrode 20 is formed on the transparent substrate 10. The copper film 31 is not formed from a copper foil laminated on a base material via an adhesive layer, but directly formed on the transparent base material 10 without an adhesive layer. That is, a copper film 31 having a desired thickness is formed on the transparent substrate 10 instead of laminating a copper foil having a specific thickness on the transparent substrate 10. As a method for forming the copper film 31, various methods such as sputtering, vapor deposition, electroplating, and electroless plating can be adopted. However, since the copper film 31 can be manufactured in a relatively short time and inexpensively, the vapor deposition is performed. preferable.

  Thereafter, as shown in FIG. 4C, a blackened metal film 32 that forms the blackened metal layer 22 of the electrode 20 is formed on the copper film 31. As a method for forming the blackened metal layer 22, it is preferable to employ sputtering or vapor deposition of copper oxide.

Next, the copper film 31 and the blackened metal film 32 on the transparent substrate 10 are patterned in a desired pattern by patterning using a photolithography technique.
Specifically, first, a resist film is provided on the blackened metal film 32, and the resist film is subjected to pattern exposure and development to be patterned into a mesh pattern or a lattice pattern (FIG. 4D). Next, the blackened metal film 32 and the copper film 31 are etched using the patterned resist pattern layer 33 as a mask. Etching is preferably performed at 35 to 45 ° C. using a 40 ° Baume ferric chloride aqueous solution as an etching solution.
Thereby, the blackened metal layer 22 is formed from the blackened metal film 32, and the copper layer 21 is formed from the copper film 31. Thus, the electrode 20 including the copper layer 21 and the blackened metal layer 22 is formed in a desired pattern on the transparent substrate 10 (FIG. 4E).

  Then, the electrode film 100 is obtained by removing the resist pattern layer 33 on the electrode 20.

[Application of electrode film]
(Touch panel)
The electrode film of the present invention can be preferably used as a touch panel sensor, and the touch panel including the touch panel sensor includes a portable small terminal, electronic paper, a computer display, a small game machine, a cash dispenser display surface, and a ticket. It can be preferably used as a touch panel mounted on a display surface of a vending machine or the like. Such a display device may be a liquid crystal display device (LCD), a plasma display device (PDP), an electroluminescence (EL) display device, a cathode ray tube (CRT) display device, an electrophoretic display device, or the like. Good.

(Other)
Moreover, since the electrode film of this invention is electroconductive and mesh invisible, it can be preferably used as an electromagnetic wave shielding material affixed on the display front surface of image display apparatuses, such as PDP.
Furthermore, the electrode film of the present invention can be preferably used as a transparent antenna element. Since the transparent antenna element has both functions of transparency and a transmission / reception function, it can be used for various transparent antennas.
The transparent antenna can be preferably used by being attached to a site where transparency is required. In particular, it can be attached to the front of the display of mobile communication devices such as mobile phones and used for receiving terrestrial and satellite broadcasts. It can be attached to the window glass of automobiles, buses, trucks, railway vehicles, new transportation systems, etc. Transparent antenna for building windows that can be used for receiving radio waves such as radio waves, television, radio, vehicle radio, etc., and installed on window glass in houses, various buildings, and partitions to receive terrestrial waves and satellite broadcasts Can be used as etc.

DESCRIPTION OF SYMBOLS 10 Transparent base material 20 Electrode 21 Copper layer 22 Blackening metal layer 31 Copper film 32 Blackening metal film 33 Resist pattern layer 100 Electrode film

Claims (3)

A 0.1 to 5 μm thick copper film, a 0.01 to 0.4 μm thick blackened metal film and a resist film are sequentially provided on a transparent substrate, and the resist film is subjected to pattern exposure and development. Then, using the patterned resist pattern layer as a mask, the black metal film and the copper film are etched to form a black metal layer and a copper layer, and then the resist pattern layer is removed . The line width of the line part is 2 to 7 μm, and the variation in the line width is
Swing width from average line width (2ΔW) / average line width (W) ≦ 0.4
The manufacturing method of the electrode film for touchscreens provided with the conductor mesh which is . The method of manufacturing the electrode film for touchscreens of Claim 1 etched using ferric chloride aqueous solution as etching liquid . The method of manufacturing the electrode film for touchscreens of Claim 2 etched at 35-45 degreeC using 40 degree Baume ferric chloride aqueous solution as etching liquid .

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