JP2014013819A - Conductive pattern formation substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive pattern formation substrate which has low contact resistance in a connection portion with a layer including a metal nanowire and has high flexibility for disposing an electrode and wiring.SOLUTION: The conductive pattern formation substrate includes: a base material 2; a nanowire layer 3 which is provided on an outer surface of the base material 2 and contains a metal nanowire 4; a relay conductive layer 8 which is provided on the nanowire layer 3 so as to contact with the metal nanowire 4; and a wiring layer 9 which is provided in contact with the relay conductive layer 8 and has smaller surface resistance than the relay conductive layer 8. The relay conductive layer 8 makes surface contact with an outer surface of the metal nanowire 4. The wiring layer 9 includes: multiple conductive fillers which at least partially contacts with the relay conductive layer 8; and a binder which supports the multiple conductive fillers in a state that the multiple conductive fillers are dispersed.

Description

  The present invention relates to a substrate on which a conductive pattern is formed.

  Conventionally, as an example of a conductive pattern formed on a substrate, a conductive pattern having a fibrous conductor such as a metal nanowire or a carbon nanotube is known. These conductive patterns are sometimes configured as light-transmitting conductive patterns, and are employed for transparent electrodes and the like disposed on a touch panel screen.

For example, Patent Document 1 discloses a touch panel in which electrodes and wiring patterns are formed by conductive metal fine wires (metal nanowires). In the touch panel described in Patent Document 1, an electrode is formed by immersing a thin film having metal nanowires dispersed in an ultraviolet curable resin in an etching solution to form a pattern.
Moreover, in patent document 1, the metal nanowire and copper foil are made into the conduction | electrical_connection state by laminating | stacking the layer which consists of copper foil on the layer which consists of ultraviolet curable resin in which metal nanowire was disperse | distributed.

JP 2011-146023 A

  In the technique disclosed in Patent Document 1, unnecessary copper foil is removed by etching from a laminate in which copper foil is laminated on a layer made of an ultraviolet curable resin in which metal nanowires are dispersed, and yet another etching method. By removing unnecessary metal nanowires. For this reason, it is substantially impossible to remove the metal nanowires arranged in the lower layer of the copper foil, and the degree of freedom for arranging electrodes and wirings is limited.

  The present invention has been made in view of the above-described circumstances, and the object thereof is low contact resistance at a connection portion with a layer containing metal nanowires, high connection stability between metal nanowires, and electrodes. Another object is to provide a conductive pattern forming substrate having a high degree of freedom for arranging wiring and wiring.

In order to solve the above problems, the present invention proposes the following means.
The conductive pattern forming substrate of the present invention is uniformly provided on the nanowire layer so as to be in contact with the base material, the nanowire layer provided on the outer surface of the base material and containing the metal nanowire, and the metal nanowire. A conductive layer having a conductive property and a wiring layer provided in contact with the relay conductive layer, wherein the wiring layer includes a plurality of conductive fillers at least partially in contact with the relay conductive layer; A binder that supports the plurality of conductive fillers in a state in which the plurality of conductive fillers are dispersed, and the metal nanowires that are in contact with the relay conductive layer are in contact with the plurality of conductive fillers that are in contact with the relay conductive layer. On the other hand, at least a part of the conductive pattern forming substrate is electrically connected through the relay conductive layer.

  Further, the wiring layer may have a sheet resistance smaller than that of the relay conductive layer.

The relay conductive layer may be a layer including a plurality of metal particles connected to each other.
The relay conductive layer may include a conductive metal oxide or a conductive polymer.

  The relay conductive layer is stacked on the nanowire layer, and the wiring layer is stacked on a surface of the outer surface of the relay conductive layer opposite to the surface where the relay conductive layer is in contact with the nanowire layer. May be.

The wiring layer may be in contact with the base material.
Further, at least a part of the wiring layer may be in contact with the nanowire layer.

  In the conductive pattern forming substrate of the present invention, the metal nanowire and the wiring layer are electrically connected via the relay conductive layer that is in surface contact with the outer surface of the metal nanowire, so that the connection portion with the layer containing the metal nanowire The contact resistance at is low.

It is a typical top view which shows the conductive pattern formation board | substrate of one Embodiment of this invention. It is sectional drawing in the AA of FIG. FIG. 3 is an enlarged view of FIG. 2. It is a flowchart which shows the manufacturing method of the conductive pattern formation board | substrate of the embodiment. It is a figure which shows the structure of the modification of the embodiment, and is sectional drawing in the position similar to the AA line of FIG. It is a figure which shows the other structure in the modification of the embodiment, and is sectional drawing in the position similar to the AA line of FIG. (A) And (b) is a figure which shows the structure of the other modification of the embodiment, and is sectional drawing in the position similar to the AA line of FIG.

A conductive pattern forming substrate 1 (hereinafter simply referred to as “substrate 1”) according to an embodiment of the present invention will be described.
First, the configuration of the substrate 1 will be described. FIG. 1 is a schematic plan view showing a conductive pattern forming substrate of this embodiment. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is an enlarged view of a portion indicated by a symbol X in FIG.
As shown in FIGS. 1 and 2, the substrate 1 has a laminated structure in which a base material 2, a nanowire layer 3, a relay conductive layer 8, and a wiring layer 9 are laminated in this order. In addition, a rectangular window portion 15 is provided in the central portion when viewed from the thickness direction of the substrate 1 and has light transmissivity and can transmit an image or the like in the thickness direction of the substrate 1. Yes. The outer region of the window portion 15 is a frame portion 16 that does not require light transmission.
In the present embodiment, the frame portion 16 is a portion that is covered by a housing of a device (touch panel, tablet, or the like) that is a target in which the substrate 1 is incorporated. In addition, the window portion 15 is a portion for the operator to perform touch input while viewing the video or the like in the device to which the substrate 1 is incorporated. For example, the window portion 15 is disposed so as to overlap a surface on which an image or the like is displayed in the liquid crystal display device.

  The base material 2 is formed of a plate material, a film, a sheet, or a film and has an insulating property. The base material 2 may have light transmittance. Moreover, the base material 2 may have flexibility. In this embodiment, a polyethylene terephthalate sheet is employed as the substrate 2. In addition, as a material of the base material 2, besides polyethylene terephthalate, polycarbonate, polyethylene naphthalate, acrylic resin, cycloolefin polymer, glass and the like can be employed.

  As shown in FIG. 3, the nanowire layer 3 is a layer that is provided on the outer surface of the substrate 2 and contains metal nanowires 4. Specifically, the nanowire layer 3 includes a conductive pattern 5 in which a plurality of metal nanowires 4 are arranged in a circuit pattern, and an insulating portion that is insulative by removing the metal nanowires 4. 7.

The conductive pattern 5 is composed of a plurality of metal nanowires 4. The metal nanowire 4 constituting the conductive pattern 5 is a fine metal wire having a length of about several tens of micrometers, for example. The material of the metal nanowire 4 is preferably a highly conductive metal material such as silver, gold, copper, or aluminum. In the conductive pattern 5, the plurality of metal nanowires 4 are substantially uniformly dispersed in the light transmissive resin 6. Most of the plurality of metal nanowires 4 are in contact with the adjacent metal nanowires 4 and are electrically connected to the adjacent metal nanowires 4. Thereby, the conductive pattern 5 functions as an electrode, wiring, or the like. Furthermore, the conductive pattern 5 has light transmittance due to a gap between the metal nanowires 4.
In this embodiment, the conductive pattern 5 is electrically connected to the one or more electrode portions 5a and the electrode portion 5a in the window portion 15 when the substrate 1 is viewed from the thickness direction, and from the window portion 15 to the frame portion 16. The lead wire 5b led out to the side is constituted.

  As shown in FIG. 1, the insulating portion 7 is provided around the conductive pattern 5 and insulates between the lines constituting the conductive pattern 5.

As shown in FIGS. 2 and 3, the relay conductive layer 8 is provided on the nanowire layer 3 so as to be in contact with the metal nanowire 4. In the present embodiment, the relay conductive layer 8 is sandwiched between the nanowire layer 3 and the wiring layer 9. In addition, the relay conductive layer 8 in the present embodiment is disposed in the region of the frame portion 16. The relay conductive layer 8 has uniform conductivity. The relay conductive layer 8 may be a layer including a plurality of metal particles connected to each other, or a layer including a metal oxide or a conductive polymer. Specifically, as the relay conductive layer 8, a metal foil, a metal deposition film, a sintered body of a metal paste, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium lead oxide (IZO), oxidation Zinc (ZnO) or the like can be employed. Further, as the relay conductive layer 8, a conductive polymer can be employed. As a conductive polymer that can be used as the relay conductive layer 8, for example, a polythiophene-based conductive polymer can be used.
In the present embodiment, unlike the window portion 15, the frame portion 16 is not required to transmit light. Therefore, the relay conductive layer 8 disposed in the region of the frame portion 16 may be light opaque.
A part of the conductor component contained in the relay conductive layer 8 is a metal nanowire in a number of points or lines so as to be substantially in surface contact with the surface of the metal nanowire 4 exposed on the outer surface of the nanowire layer 3. Contact the wire 4. Further, the conductor component contained in the relay conductive layer 8 exists uniformly in the relay conductive layer 8. In addition, although it is preferable that the relay conductive layer 8 does not contain an insulator substantially, it may contain a trace amount insulator.

  The wiring layer 9 is provided in contact with the relay conductive layer 8. For example, the wiring layer 9 can be a layer in which the conductive filler 10 is dispersed in the binder 11. The conductive filler 10 is a conductive powder that is at least partially in contact with the relay conductive layer 8. For example, the conductive filler 10 can be made of gold, silver, copper, platinum, nickel, tin, lead, or an alloy thereof. The binder 11 is a member that supports the conductive filler 10 in a state where the conductive filler 10 is dispersed. The binder 11 preferably has conductivity. In the present embodiment, an insulator can be used as the binder 11.

Next, the manufacturing method of the board | substrate 1 of this embodiment is demonstrated. FIG. 4 is a flowchart showing the method for manufacturing the conductive pattern forming substrate of this embodiment.
First, the nanowire layer 3 is formed on the outer surface of the substrate 2 (step S1 shown in FIG. 4).
In step S <b> 1, a light-transmitting resin fluid in which the metal nanowires 4 are dispersed is applied to the outer surface of the substrate 2, and the fluid is cured to obtain a light-transmitting resin 6. Examples of the light transmissive resin 6 in which the metal nanowires 4 are dispersed include a thermosetting resin, a solvent evaporation drying resin, a two-component curable resin, a visible light curable resin, an ultraviolet curable resin, and an electron beam curable resin. It can be appropriately selected from resins and the like.
Step S1 is complete | finished now and it progresses to step S2.

Step S <b> 2 is a step of forming the conductive pattern 5 and the insulating portion 7 on the nanowire layer 3.
In step S <b> 2, a laser beam is irradiated to a region to be the insulating portion 7 in the nanowire layer 3. Then, the metal nanowire 4 in the area irradiated with the laser light disappears. Thereby, the conductor is removed in the insulating portion 7. A region other than the insulating portion 7 in the nanowire layer 3 becomes the conductive pattern 5. The conductive pattern 5 may include a pattern serving as a shield for reducing the influence of noise such as electromagnetic waves, for example, in addition to the pattern for transmitting power and electric signals.
In step S2, the metal nanowires 4 in the insulating portion 7 may be removed by wet etching, for example, instead of so-called laser etching using laser light.
Step S2 is complete | finished now and it progresses to step S3.

Step S <b> 3 is a step of forming the relay conductive layer 8.
In step S3, a conductor to be the relay conductive layer 8 is formed on the nanowire layer 3 so as to have a desired pattern shape.
For example, when a metal vapor deposition film is formed as the relay conductive layer 8, the metal vapor deposition film pattern can be formed using a mask in which an opening having a desired pattern shape is formed.
For example, when a sintered body of a metal paste is formed as the relay conductive layer 8, a fluid-like metal paste is applied onto the nanowire layer 3 by, for example, screen printing, and then the applied metal paste is heated. Then, the metal particles in the metal paste are sintered.
For example, when forming a light-transmitting conductive film made of ITO, FTO, IZO, ZnO or the like or a light-transmitting conductive film made of a conductive polymer or the like as the relay conductive layer 8, the light-transmitting conductive film is made of nano material. A pattern is formed on the wire layer 3.
Step S3 is complete | finished now and it progresses to step S4.

Step S4 is a step of forming the wiring layer 9.
In step S <b> 4, the wiring layer 9 is formed so as to have a pattern shape overlapping the relay conductive layer 8. For example, the wiring layer 9 can be formed by screen printing using a screen plate in which openings having a desired wiring pattern having a region overlapping the relay conductive layer 8 are formed. Thereby, the wiring layer 9 is laminated on the surface opposite to the surface where the relay conductive layer 8 is in contact with the nanowire layer 3.
This ends step S4.

  Next, the operation of the substrate 1 will be described.

First, a conventional technique for connecting metal nanowires to other wirings on a substrate will be described.
Conventionally, metal nanowires are retained by being cured after the resin is dispersed and applied to a resin fluid. For this reason, it is difficult to strictly control the number of metal nanowires exposed from the outer surface of the resin and the exposure amount. As a result, there is a variation in the contact resistance between the metal nanowire and the other wiring, and a conduction failure may occur between the metal nanowire and the other wiring.
In the conventional technology, metal nanowires and metal nanowires and other wirings are mechanically contacted by point contact or line contact. For example, when a substrate is bent, metal nanowires are There are cases where it is easily disconnected from other wiring. When the contact opportunity between the metal nanowire and the other wiring is lost, the conductive state of the substrate, which was in a normal conductive state at the time of manufacture, may become defective with use.

On the other hand, in this embodiment, as shown in FIG. 3, the relay conductive layer 8 is provided between the nanowire layer 3 and the wiring layer 9. There are innumerable contacts between the relay conductive layer 8 and the metal nanowires 4 at the contact interface 8a, and there are innumerable contacts between the relay conductive layer 8 and the wiring layer 9 at the contact interface 8b. The metal nanowires 4 in contact with the relay conductive layer 8 are electrically connected to the plurality of conductive fillers 10 in contact with the relay conductive layer 8 via the relay conductive layer 8.
As described above, the relay conductive layer 8 is substantially in surface contact with the metal nanowire 4 exposed from the nanowire layer 3 and substantially in surface contact with the wiring layer 9. Thereby, the relay conductive layer 8 laminated on the nanowire layer 3 can provide a number of paths for relaying electric power and electrical signals between the nanowire layer 3 and the wiring layer 9.
Furthermore, since the relay conductive layer 8 and the metal nanowire 4 are in a substantially surface contact state, even if the metal nanowire 4 moves slightly when the substrate 1 is bent, the metal nanowire 4 and the relay conductive layer are relayed. Mechanical contact with layer 8 is maintained. Thereby, the metal nanowire 4 and the relay conductive layer 8 are unlikely to have poor conduction.

  In the present embodiment, the relay conductive layer 8 has a layered structure sandwiched between the nanowire layer 3 and the wiring layer 9. If the relay conductive layer 8 is made thin, the nanowire The electrical resistance between the layer 3 and the wiring layer 9 can be lowered.

As described above, the substrate 1 of the present embodiment has a configuration in which the substrate 1 is connected to the wiring layer 9 via the relay conductive layer 8 that conducts substantially in surface contact with the metal nanowire 4. So contact resistance is low.
Further, since the relay conductive layer 8 is formed after the conductive pattern 5 and the insulating portion 7 are formed on the nanowire layer 3, a pattern is formed so that the lower layer of the relay conductive layer 8 and the wiring layer 9 is the insulating portion 7. In other words, the degree of freedom in forming the conductive pattern 5 and the insulating portion 7 is high.

  In addition, since the wiring layer 9 is electrically connected to the metal nanowire 4 through the relay conductive layer 8, there is a compatibility problem that makes it difficult to directly contact the metal nanowire 4 and the wiring layer 9. By interposing the relay conductive layer 8 having the property of being in surface contact with the metal nanowire 4 and being in surface contact with the metal nanowire 4, the possibility that the compatibility problem can be solved increases.

(Modification 1)
Next, a modified example of the present invention will be described. In addition, in each modified example described below, the same reference numerals are given to the same components as those in the above-described embodiment, and duplicate descriptions are omitted.
FIG. 5 is a diagram showing the configuration of this modification, and is a cross-sectional view at the same position as the line AA in FIG. FIG. 6 is a diagram showing another configuration in the present modification, and is a cross-sectional view at the same position as the line AA in FIG.
As shown in FIG. 5, in this modification, a part of the relay conductive layer 8 is in contact with a surface of the wiring layer 9 that is different from the surface directed to the nanowire layer 3. The relay conductive layer 8 of this modification is formed after the wiring layer 9 is formed on the nanowire layer 3.
In the case of this modification, in the part where the wiring layer 9 and the nanowire layer 3 are in direct contact, the conductive state is the same as in the prior art. In addition to this, the relay conductive layer 8 of this modification is in surface contact with both the wiring layer 9 and provides an infinite number of paths between the metal nanowire 4 and the wiring layer 9 as in the above-described embodiment. can do.
In addition, it is good also as the relay conductive layer 8 which contact | connects the wiring layer 9 so that the perimeter of the wiring layer 9 may be covered combining the present invention and the above-mentioned embodiment (refer FIG. 6). In this case, the contact area between the wiring layer 9 and the relay conductive layer 8 is increased as compared with the above-described embodiment, and the conduction path between the metal nanowire 4 and the wiring layer 9 can be further increased. As a result, the metal nanowire 4 and the wiring layer 9 can be connected in a stable conductive state.

(Modification 2)
Next, another modification of the present invention will be described. FIG. 7A and FIG. 7B are diagrams showing the configuration of this modification, and are cross-sectional views at the same position as the AA line of FIG.
In this modification, the wiring layer 9 is provided in contact with the base material 2 as shown in FIG. The relay conductive layer 8 is laminated on the nanowire layer 3 and the wiring layer 9 so as to cover a part of the nanowire layer 3 and a part of the wiring layer 9.
Moreover, in this modification, as shown to Fig.7 (a), the nanowire layer 3 and the wiring layer 9 may be in contact, for example, as shown in FIG.7 (b), the nanowire layer 3 and the wiring layer 9 may be spaced apart. When the nanowire layer 3 and the wiring layer 9 are separated from each other, the relay conductive layer 8 enters the gap between the nanowire layer 3 and the wiring layer 9.
Even in the case of this modification, the relay conductive layer 8 is electrically connected to the outer surface of the metal nanowire 4 in a substantially surface contact state, and is electrically connected to the wiring layer 9 in a substantially surface contact state. Thereby, like the above-mentioned embodiment, the relay conductive layer 8 provides innumerable paths through which electric power and electric signals flow between the metal nanowire 4 and the wiring layer 9.

This modification also has the same effect as the above-described embodiment.
Furthermore, in this modification, the relay conductive layer is formed on a surface (hereinafter, referred to as “side surface of the nanowire layer 3”) that is directed in a direction intersecting with the surface in contact with the substrate 2 among the outer surfaces of the nanowire layer 3. For example, even if a gap is generated between the nanowire layer 3 and the wiring layer 9 due to an error during manufacturing, the nanowire layer 3 and the wiring layer 9 are electrically connected via the relay conductive layer 8. It becomes a state.
Further, in this modified example, the nanowire layer 3 may be formed on the outer surface of the substrate 2 after the wiring layer 9 is formed on the outer surface of the substrate 2, contrary to the above-described embodiment.

(Modification 3)
Next, still another modification of the present invention will be described.
In this modification, a part of manufacturing process of the conductive pattern formation board in the above-mentioned embodiment differs.
That is, in the step S1, first, a dispersion containing the metal nanowires 4 and the water-soluble polymer is applied to the substrate 2 and dried. Thereby, the metal nanowire 4 is temporarily fixed to the base material 2 through the water-soluble polymer.
Subsequently, for the purpose of further firmly fixing the metal nanowires 4 to the base material 2, a fluid-like resin having optical transparency is applied so that a part of the metal nanowires 4 is embedded in the resin. The resin may be a resin that is cured by a predetermined curing process. For example, as the resin, a thermosetting type, a light (including visible light, ultraviolet light, and infrared light) curable type, an electron beam curable type, a solvent evaporation drying type, a two-component curable type, or other known resins are appropriately used. You may select and adopt.
When the fluid-like resin is cured, the metal nanowires 4 are fixed to the base material 2, and the metal nanowires 4 are protected so as not to fall off the base material 2.
In this modification, a part of the metal nanowire 4 is exposed from the cured resin, and a portion of the metal nanowire 4 exposed from the cured resin is in surface contact with the relay conductive layer 8, and the above-described embodiment. Has the same effect as.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, the relay conductive layer may be provided in part or all of the window portion in the conductive pattern formation substrate.
The relay conductive layer may be a composite material including one or more of metal particles, metal oxides, and conductive polymers.
In addition, the constituent elements shown in the above-described embodiment and each modification can be combined as appropriate.
In addition, the design change etc. with respect to the said specific structure are not limited to the said matter.

DESCRIPTION OF SYMBOLS 1 Conductive pattern formation board | substrate 2 Base material 3 Nanowire layer 4 Metal nanowire 5 Conductive pattern 6 Optically transparent resin 7 Insulation part 8 Relay conductive layer 8a Contact interface 8b Contact interface 9 Wiring layer 10 Conductive filler 11 Binder

Claims (7)

A substrate;
A nanowire layer containing metal nanowires provided on the outer surface of the substrate;
A relay conductive layer provided on the nanowire layer so as to be in contact with the metal nanowire and having uniform conductivity;
A wiring layer provided in contact with the relay conductive layer;
With
The wiring layer is
A plurality of conductive fillers at least partially in contact with the relay conductive layer;
A binder that supports the plurality of conductive fillers in a state where the plurality of conductive fillers are dispersed;
Have
The metal nanowire in contact with the relay conductive layer is at least partially electrically connected to the plurality of conductive fillers in contact with the relay conductive layer via the relay conductive layer. substrate. The conductive pattern forming substrate according to claim 1,
The conductive pattern forming substrate, wherein the wiring layer has a smaller surface resistance than the relay conductive layer. The conductive pattern forming substrate according to claim 1 or 2,
The conductive pattern forming substrate, wherein the relay conductive layer is a layer including a plurality of metal particles connected to each other. A conductive pattern forming substrate according to any one of claims 1 to 3,
The conductive pattern forming substrate, wherein the relay conductive layer includes a conductive metal oxide or a conductive polymer. A conductive pattern forming substrate according to any one of claims 1 to 4,
The relay conductive layer is laminated on the nanowire layer,
The conductive pattern forming substrate, wherein the wiring layer is laminated on a surface of the outer surface of the relay conductive layer opposite to a surface where the relay conductive layer is in contact with the nanowire layer. A conductive pattern forming substrate according to any one of claims 1 to 5,
The conductive pattern forming substrate, wherein the wiring layer is in contact with the base material. The conductive pattern forming substrate according to claim 6,
At least a part of the wiring layer is in contact with the nanowire layer.

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