JP2016031503A - Method for forming conductive pattern, conductive pattern substrate, and touch panel sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a conductive pattern by which occurrence of defective disconnection between a conductive pattern and a silver paste can be inhibited even under high temperature and high humidity conditions without depending on a composition of the silver paste.SOLUTION: The method for forming a conductive pattern includes: an exposure step of irradiating a photosensitive layer that includes a photosensitive resin layer disposed on a substrate and a conductive film containing conductive fiber disposed on a surface of the photosensitive resin layer opposite to the substrate, with active rays along a pattern in the absence of oxygen; a developing step of removing an unexposed part of the photosensitive layer by use of an alkali developer to form a conductive pattern; and a cleaning step of cleaning the conductive pattern formed in the developing step by use of an acid aqueous solution containing an organic acid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for forming a conductive pattern, a conductive pattern substrate, and a touch panel sensor, and in particular, a conductive pattern used as an electrode wiring of a device such as a flat panel display such as a liquid crystal display element, a touch panel (touch screen), a solar cell, or illumination. The present invention relates to a forming method, a conductive pattern substrate, and a touch panel sensor.

  Liquid crystal display elements and touch panels are widely used in large electronic devices such as personal computers and televisions, small electronic devices such as car navigation systems, mobile phones and electronic dictionaries, and display devices such as OA / FA devices.

  Various types of touch panels have already been put into practical use, but in recent years, the use of capacitive touch panels has been advanced. In a capacitive touch panel, when a fingertip (conductor) contacts the touch input surface, the fingertip and the conductive film are capacitively coupled to form a capacitor. For this reason, the capacitive touch panel detects the coordinates by capturing the change in charge at the contact position of the fingertip.

  In particular, the projected capacitive touch panel is capable of multipoint detection of fingertips, and thus has a good operability that allows complicated instructions to be given. Use as an input device on a display surface in a device having a small display device such as a music player is advancing.

  In general, in a projected capacitive touch panel, a plurality of X electrodes and a plurality of Y electrodes orthogonal to the X electrodes have a two-layer structure in order to express two-dimensional coordinates based on the X and Y axes. Forming.

  In such a touch panel, a liquid crystal display element, a solar cell, illumination, and the like, a transparent conductive film is used as part of the transparent wiring, the pixel electrode, or the terminal.

  Conventionally, ITO (Indium-Tin-Oxide), indium oxide, tin oxide, and the like have been used as materials for transparent conductive films because they exhibit high transmittance to visible light. As electrodes provided on a substrate for a liquid crystal display element or the like, a pattern obtained by patterning a transparent conductive film made of the above-mentioned material is mainly used.

  As a method for patterning a transparent conductive film, a method is generally used in which a transparent conductive film is formed on a substrate, a resist pattern is formed by photolithography, and a predetermined portion of the conductive film is removed by wet etching to form a conductive pattern. Is. In the case of an ITO film and an indium oxide film, a mixed liquid composed of two liquids of hydrochloric acid and ferric chloride is often used as an etching liquid.

  The ITO film and the tin oxide film are generally formed by a sputtering method. In this method, the properties of the transparent conductive film are likely to change depending on the difference in sputtering method, sputtering power, gas pressure, substrate temperature, type of atmospheric gas, and the like. Differences in the film quality of the transparent conductive film due to variations in sputtering conditions cause variations in the etching rate when the transparent conductive film is wet-etched, which tends to reduce the product yield due to patterning defects. In addition, since the conductive pattern forming method described above has undergone a sputtering process, a resist forming process, and an etching process, the process is long and a great burden is imposed on the cost.

  In recent years, attempts have been made to form a transparent conductive pattern using a material that replaces ITO, indium oxide, tin oxide, and the like in order to solve the above problems. For example, Patent Literature 1 below discloses a method for forming a conductive pattern using a photosensitive conductive film including a conductive film containing conductive fibers. If this technique is used, a conductive pattern can be easily formed directly on various substrates by a photolithography process.

International Patent Publication No. 2010/021224

  Incidentally, a wiring circuit for transmitting an electrical change generated in the transparent conductive film portion to the control IC is formed in the frame area of the touch panel. As such a wiring circuit, an extremely thin wiring circuit pattern is printed by screen printing using a vapor-deposited metal wiring circuit formed by using a vapor-deposited metal thin film and a thermosetting or evaporation drying type silver paste. However, a silver paste printed wiring circuit formed by heat treatment can be mentioned, but the latter silver paste printed wiring circuit is more widely used in terms of cost. That is, a projected capacitive touch panel generally has a structure in which a transparent conductive film and a control IC are physically and electrically connected by a silver paste printed wiring circuit. If the paste printed wiring is disconnected or short-circuited, or if a disconnection or short-circuit occurs in the connection portion between the silver paste and the transparent conductive film or the silver paste and the control IC, a problem that the touch panel does not operate normally occurs.

  As described above, by using the photosensitive conductive film disclosed in Patent Document 1, touch panel sensor electrodes (conductive patterns obtained by patterning a transparent conductive film) can be easily formed on various substrates by a photolithography process. can do. However, when the sensor electrode and the control IC are connected by the silver paste printed wiring, there is a problem that the resistance value between the conductive pattern and the silver paste increases under a high temperature and high humidity condition, and is easily disconnected. Since this increase in resistance value is influenced by the composition of the silver paste, it is possible to prevent the increase in resistance value by selecting an appropriate silver paste. However, the silver paste is also required to have printability for forming fine wiring, and there are few silver pastes that achieve both the printability and the suppression of the increase in resistance value.

  The present invention has been made in view of the above circumstances, and does not depend on the composition of the silver paste, and is capable of suppressing the occurrence of disconnection failure between the conductive pattern and the silver paste even under high temperature and high humidity conditions. It aims at providing the formation method of a pattern, the conductive pattern board | substrate obtained using this method, and a touchscreen sensor.

  In order to achieve the above object, the present invention provides a conductive film containing a photosensitive resin layer provided on a substrate and conductive fibers provided on a surface of the photosensitive resin layer opposite to the substrate. A conductive pattern is formed by removing an unexposed portion of the photosensitive layer using an alkaline developer, and an exposure step of irradiating the photosensitive layer containing actinic rays in a pattern in the absence of oxygen. There is provided a method for forming a conductive pattern, comprising: a developing step; and a cleaning step of cleaning the conductive pattern formed in the developing step using an acidic aqueous solution containing an organic acid. Note that “in the absence of oxygen” does not mean that oxygen is not present at all, and it is sufficient that the presence of oxygen is suppressed to such an extent that a conductive pattern can be formed. In the absence of oxygen, vacuum conditions may be used, and the photosensitive layer may be protected with a film.

  According to the method for forming a conductive pattern of the present invention, the composition of the silver paste is obtained by including a cleaning step of cleaning the conductive pattern formed through the exposure step and the development step using an acidic aqueous solution containing an organic acid. Without depending, it is possible to suppress the occurrence of disconnection failure between the conductive pattern and the silver paste even under high temperature and high humidity conditions. This is because the conductive pattern after development is washed with an acidic aqueous solution containing an organic acid, so that an unstable salt remaining in the conductive pattern (a salt of a metal ion such as Na existing in the developer and an acidic functional group). ) Can be effectively returned to the acidic functional group, and as a result, the occurrence of disconnection failure with the silver paste can be suppressed even under high temperature and high humidity conditions without depending on the composition of the silver paste. I guess there is. If the unstable salt remains, metal ions remain. Since the metal ion becomes an electron carrier and at the same time an electron receiver, if it remains in the conductive pattern, it promotes silver ionization and migration, and may eventually lead to disconnection. Therefore, the occurrence of disconnection failure can be suppressed by returning the unstable salt to the acidic functional group by the washing step and reducing the residual amount of metal ions. In addition, since the organic acid does not react with the conductive fiber, the use of the organic acid for washing can prevent the conductive fiber from being corroded by the acid.

  In the method for forming a conductive pattern of the present invention, a photosensitive conductive film having a support film, a conductive film provided on the support film, and a photosensitive resin layer provided on the conductive film is used for the photosensitive film. The photosensitive layer is preferably provided by laminating such that the photosensitive resin layer is in close contact with the substrate. In the case of this embodiment, the exposure step is performed “in the absence of oxygen” due to the presence of the support film.

  In this case, the photosensitive layer can be more easily formed on the substrate, and productivity can be improved. Moreover, the smoothness of the surface on the opposite side to the board | substrate of a photosensitive layer can be improved by transferring the electrically conductive film and photosensitive resin layer which were provided on the support film, and the smoothness of the conductive pattern formed is improved. Can be improved.

  In the method for forming a conductive pattern of the present invention, after the exposure step and before the development step, a part or all of the unexposed portion of the photosensitive layer in the exposure step is irradiated with actinic rays in the presence of oxygen. It is preferable to further include a second exposure step. Moreover, when forming the said photosensitive layer using the said photosensitive conductive film, the formation method of the conductive pattern of this invention is the presence of oxygen after peeling the said support film after the said exposure process and before the said image development process. Therefore, it is preferable to further include a second exposure step of irradiating a part or all of the unexposed portion in the exposure step of the photosensitive layer with actinic rays.

  By performing the second exposure step, the exposed portion in the previous exposure step (hereinafter also referred to as “first exposure step”) is a cured resin layer having a conductive film, that is, a conductive pattern, and the second exposure step is performed. Of the exposed portion in the exposure step, the portion other than the exposed portion in the first exposure step can be a cured resin layer that does not have a conductive film. By providing the resin cured layer not having the conductive film together with the conductive pattern on the substrate, the step difference of the conductive pattern can be reduced as compared with the case where only the conductive pattern is provided on the substrate. The reason for this effect is that the second exposure step is performed in the presence of oxygen, thereby inhibiting the curing of the photosensitive layer on the side opposite to the substrate, thereby preventing the unexposed portion of the first exposure step. The present inventors speculate that the surface layer portion of the photosensitive layer is cured only to such an extent that the conductive film can be removed even if exposed in the second exposure step. In addition, the conductive pattern obtained through the second exposure step can be sufficiently secured to the substrate by the cured resin layer.

  In the method for forming a conductive pattern of the present invention, the photosensitive resin layer contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator. It preferably contains an oxime ester compound. Thereby, the transparency and resolution of the conductive pattern to be formed can be improved.

  In the method for forming a conductive pattern of the present invention, the conductive fiber is preferably a silver fiber. Thereby, the electroconductivity of the conductive pattern formed can be improved. In addition, the conductivity of the conductive pattern can be easily adjusted.

  In the method for forming a conductive pattern of the present invention, the acidic aqueous solution preferably has a pH of 0-6. In this case, the acidity and corrosivity are not too strong, and the unstable salt remaining in the conductive pattern can be effectively returned to the acidic functional group without causing corrosion of the conductive fibers.

  In the method for forming a conductive pattern of the present invention, the alkaline developer is preferably an alkaline aqueous solution. Since the alkaline aqueous solution is safe and stable and has good operability, the development process can be easily performed.

  In the method for forming a conductive pattern of the present invention, the alkaline developer may be an alkaline quasi-aqueous developer composed of an alkaline aqueous solution and one or more organic solvents. The alkaline quasi-aqueous developer is safe and stable, has good operability, and can promote development by the presence of an organic solvent, so that the development process can be performed more easily.

  In the method for forming a conductive pattern of the present invention, the photosensitive resin layer preferably contains a compound having at least one of a carboxyl group and a phenolic hydroxyl group. Thereby, the alkali developability of the photosensitive layer can be improved. In addition, the compound which has at least 1 sort (s) of the said carboxyl group and phenolic hydroxyl group can be used as (A) binder polymer.

  The present invention also provides a conductive pattern substrate comprising a substrate and a conductive pattern formed on the substrate by the conductive pattern forming method of the present invention.

  In the conductive pattern substrate of the present invention, since the conductive pattern is formed by the conductive pattern forming method of the present invention, the conductive pattern and the silver paste are not affected by the composition of the silver paste, even under high temperature and high humidity conditions. It is possible to suppress the occurrence of disconnection failure between the two.

  The present invention further provides a touch panel sensor comprising the conductive pattern substrate of the present invention.

  By providing the conductive pattern substrate of the present invention, the touch panel sensor of the present invention may cause a disconnection failure between the conductive pattern and the silver paste even under high temperature and high humidity conditions without depending on the composition of the silver paste. Can be suppressed.

  According to the present invention, without depending on the composition of the silver paste, a method for forming a conductive pattern that can suppress the occurrence of disconnection failure between the conductive pattern and the silver paste even under high temperature and high humidity conditions, and this method are used. A conductive pattern substrate and a touch panel sensor obtained in this way can be provided.

It is a schematic cross section showing one embodiment of a photosensitive conductive film. It is a partially cutaway perspective view showing one embodiment of a photosensitive conductive film. It is a schematic cross section for demonstrating one Embodiment of the formation method of the conductive pattern of this invention. It is a schematic cross section for demonstrating another embodiment of the formation method of the conductive pattern of this invention. It is a model top view which shows an example of an electrostatic capacitance type touch panel sensor. It is a schematic diagram for demonstrating an example of the manufacturing method of the touchscreen sensor shown by FIG. FIG. 6 is a partial cross-sectional view taken along line a-a ′ shown in FIG. 5. FIG. 6 is a partial cross-sectional view taken along line b-b ′ shown in FIG. 5.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.
In this specification, “(meth) acrylate” means “acrylate” or “methacrylate” corresponding thereto, and the same applies to “(meth) acryloyl” and “(meth) acrylic acid alkyl ester”.
“(Meth) acryl” means “acryl” or “methacryl”.
“A or B” only needs to include one of A and B, or may include both. Furthermore, the materials exemplified below may be used alone or in combination of two or more unless otherwise specified.

  The conductive pattern forming method according to the present embodiment includes a photosensitive resin layer provided on a substrate and a conductive film containing conductive fibers provided on the surface of the photosensitive resin layer opposite to the substrate. A conductive pattern is formed by removing an unexposed portion of the photosensitive layer using an alkaline developer, and an exposure step of irradiating the photosensitive layer containing actinic rays in a pattern in the absence of oxygen. A developing step, and a cleaning step of cleaning the conductive pattern formed in the developing step using an acidic aqueous solution containing an organic acid. Here, the photosensitive layer is, for example, a photosensitive conductive film having a support film, a conductive film provided on the support film, and a photosensitive resin layer provided on the conductive film. By laminating such that the layer is in close contact with the substrate, it can be provided on the substrate.

<Photosensitive conductive film>
FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of a photosensitive conductive film used in the present embodiment. A photosensitive conductive film 10 shown in FIG. 1 includes a support film 1 and a photosensitive layer 4 provided on the support film 1. The photosensitive layer 4 includes a conductive film 2 and a photosensitive film provided on the conductive film 2. And a functional resin layer 3.

  In the present specification, the boundary between the conductive film 2 and the photosensitive resin layer 3 is not necessarily clear. The conductive film 2 only needs to have conductivity in the surface direction of the photosensitive layer 4, and the conductive resin 2 may be mixed with the photosensitive resin layer 3. For example, the conductive film 2 may be impregnated with a composition constituting the photosensitive resin layer 3, or the composition constituting the photosensitive resin layer 3 may be present on the surface of the conductive film 2.

  Hereinafter, each of the support film 1, the conductive film 2, and the photosensitive resin layer 3 constituting the photosensitive conductive film 10 will be described in detail.

  Examples of the support film 1 include polymer films having heat resistance and solvent resistance such as polyethylene terephthalate film, polyethylene film, polypropylene film, and polycarbonate film. Among these, a polyethylene terephthalate film is preferable from the viewpoints of transparency and heat resistance. In addition, since these polymer films are removed from the photosensitive layer 4 in the step of peeling the support film 1, the polymer film has been subjected to a surface treatment that makes removal impossible, or cannot be removed. The material must not be.

  From the viewpoint of mechanical strength, the thickness of the support film 1 is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. By setting the thickness of the support film 1 to the above numerical value or more, for example, a step of applying a conductive dispersion to form the conductive film 2, a photosensitive resin composition for forming the photosensitive resin layer 3 is used. It is possible to prevent the support film 1 from being broken in the step of coating or the step of peeling the support film 1. Further, when the photosensitive resin layer 3 is irradiated with actinic rays through the support film 1, the thickness of the support film 1 is preferably 100 μm or less and 80 μm or less from the viewpoint of excellent resolution of the conductive pattern. More preferably, it is 60 μm or less.

  From the above viewpoint, the thickness of the support film 1 is preferably 5 to 100 μm, more preferably 10 to 80 μm, and still more preferably 15 to 60 μm.

  The haze value of the support film 1 is preferably 0.01 to 5.0%, more preferably 0.01 to 3.0%, from the viewpoint of improving sensitivity and resolution. More preferably, it is -2.0%, and it is especially preferable that it is 0.01-1.0%. The haze value can be measured according to JIS K 7105. For example, it can be measured with a commercially available turbidimeter such as NDH-1001DP (manufactured by Nippon Denshoku Industries Co., Ltd., product name). .

The conductive film 2 contains at least one kind of conductive fiber. Examples of the conductive fiber include metal fibers such as gold, silver, copper, and platinum, and carbon fibers such as carbon nanotubes.
From the viewpoint of conductivity, it is preferable to use gold fiber, silver fiber or copper fiber. Furthermore, it is more preferable to use silver fibers from the viewpoint of easily adjusting the conductivity of the conductive film 2 to be formed.

The metal fibers, a method of reducing the metal ions with a reducing agent such as NaBH _4, can be manufactured by the polyol method. The carbon nanotubes may be commercial products such as Hipym single-walled carbon nanotubes from Unidim.

  The fiber diameter of the conductive fiber is preferably 1 nm to 50 nm, more preferably 2 nm to 20 nm, and still more preferably 3 nm to 10 nm. The fiber length of the conductive fiber is preferably 1 μm to 100 μm, more preferably 2 μm to 50 μm, and still more preferably 3 μm to 10 μm. The fiber diameter and fiber length can be measured with a scanning electron microscope.

  The conductive film 2 may contain an organic conductor together with the conductive fiber. The organic conductor can be used without particular limitation, but it is preferable to use a conductive polymer such as a thiophene derivative or an aniline derivative. Specifically, polyethylenedioxythiophene, polyhexylthiophene, polyaniline, or the like can be used as the conductive polymer.

  FIG. 2 is a partially cutaway perspective view showing an embodiment of the photosensitive conductive film 10. As shown in FIG. 2, the conductive film 2 preferably has a network structure in which conductive fibers are in contact with each other. The conductive film 2 having such a network structure may be formed on the surface of the photosensitive resin layer 3 on the support film 1 side, but on the surface of the photosensitive layer 4 exposed when the support film 1 is peeled off. As long as conductivity is obtained in the surface direction, the conductive film 2 may be formed so that a part of the photosensitive resin layer 3 enters the conductive film 2, and the conductive film is formed on the surface layer of the photosensitive resin layer 3 on the support film 1 side. 2 may be included.

  The conductive film 2 is, for example, one or more of the above-mentioned conductive fibers, one or more of the above-mentioned organic conductors, if necessary, water or an organic solvent, and, if necessary, a dispersion stabilizer such as a surfactant. A conductive dispersion liquid containing an agent can be formed by coating on the support film 1 and then drying.

  The surfactant used in the conductive dispersion is not particularly limited, but is pentaethylene glycol monododecyl ether, a fluorosurfactant (for example, Zonyl (registered trademark) of DuPont), n-dodecyl-β-D. -Maltoside etc. are mentioned.

  The conductive dispersion can be applied by a known method such as a roll coating method, a comma coating method, a gravure coating method, an air knife coating method, a die coating method, a bar coating method, or a spray coating method. The drying can be performed at 30 to 150 ° C. for about 1 to 30 minutes using a hot air convection dryer or the like. In the conductive film 2, the conductive fiber and the organic conductor may coexist with the surfactant and the dispersion stabilizer.

  The thickness of the conductive film 2 varies depending on the use of the conductive pattern and the required conductivity, but is preferably 1 μm or less, more preferably 1 nm to 0.5 μm, and more preferably 5 nm to 0.1 μm. Further preferred. When the thickness of the conductive film 2 is 1 μm or less, the light transmittance in the wavelength region of 400 to 700 nm is high, the pattern formation is excellent, and it is particularly suitable for the production of a transparent electrode. The thickness of the conductive film 2 can be measured with a scanning electron microscope.

  When the conductive film 2 includes an organic conductor in combination with conductive fibers, the conductive film 2 may be formed using a conductive dispersion prepared by mixing them, and the conductive material including each of them alone. The conductive film 2 may be formed using a dispersion. For example, after applying a conductive dispersion containing conductive fibers to the support film 1, a conductive dispersion containing an organic conductor can be applied and dried to form the conductive film 2.

  The photosensitive resin layer 3 can be formed from a photosensitive resin composition containing (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator. When the photosensitive resin layer 3 contains the above three components, the adhesion between the substrate and the conductive pattern and the patterning property can be improved.

  (A) As binder polymer, epoxy resin obtained by reaction of acrylic resin, styrene resin, epoxy resin, amide resin, amide epoxy resin, alkyd resin, phenol resin, ester resin, urethane resin, epoxy resin and (meth) acrylic acid Examples thereof include acid-modified epoxy acrylate resins obtained by reaction of acrylate resins and epoxy acrylate resins with acid anhydrides.

  Among the above, from the viewpoint of excellent alkali developability and film formability, it is preferable to use an acrylic resin, and the acrylic resin has a structural unit derived from (meth) acrylic acid and (meth) acrylic acid alkyl ester. More preferred. Here, the “acrylic resin” means a polymer mainly having a structural unit derived from a polymerizable monomer having a (meth) acryloyl group.

  As the acrylic resin, for example, an acrylic resin produced by radical polymerization of a polymerizable monomer having a (meth) acryloyl group can be used.

  (A) It is preferable that a binder polymer has at least 1 sort (s) among a carboxyl group and a phenolic hydroxyl group from a viewpoint of making alkali developability more favorable. Examples of the polymerizable monomer having a carboxyl group include (meth) acrylic acid described above. Examples of the polymerizable monomer having a phenolic hydroxyl group include 4-hydroxyphenyl (meth) acrylate.

  (A) The ratio of the carboxyl group of the binder polymer is preferably 10 to 50% by mass, and preferably 12 to 40% by mass as the ratio of the polymerizable monomer having a carboxyl group to the total polymerizable monomer to be used. % Is more preferable, 15 to 30% by mass is further preferable, and 15 to 25% by mass is particularly preferable. In terms of excellent alkali developability, the content is preferably 10% by mass or more, and in terms of excellent alkali resistance, it is preferably 50% by mass or less.

  (A) It is preferable that the acid value of a binder polymer is 50 mgKOH / g or more and 150 mgKOH / g or less from a viewpoint of improving the developability with respect to various well-known developing solutions in a image development process. In addition, an acid value can be measured with reference to the Example of this-application specification.

  (A) The weight average molecular weight of the binder polymer is preferably 5,000 to 300,000, more preferably 20,000 to 150,000, and more preferably 30,000 to 100,000 from the viewpoint of balancing the mechanical strength and alkali developability. Further preferred. In terms of excellent developer resistance, the weight average molecular weight is preferably 5000 or more. Further, from the viewpoint of development time, it is preferably 300000 or less. In addition, a weight average molecular weight can be measured with reference to the Example of this-application specification.

  Next, (B) the photopolymerizable compound will be described. This photopolymerizable compound preferably has an ethylenically unsaturated bond. As the photopolymerizable compound having an ethylenically unsaturated bond, a compound obtained by reacting an α, β-unsaturated carboxylic acid with a polyhydric alcohol, and an α, β-unsaturated carboxylic acid with a compound containing a glycidyl group. , Urethane monomers such as (meth) acrylate compounds having a urethane bond, γ-chloro-β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β′- Examples thereof include phthalic acid compounds such as (meth) acryloyloxyethyl-o-phthalate and β-hydroxypropyl-β ′-(meth) acryloyloxyethyl-o-phthalate, and (meth) acrylic acid alkyl esters.

  Among these, from the viewpoint of improving the reliability of the electronic component after forming the transparent electrode pattern, a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid is preferable. Among them, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane diethoxytri (meth) acrylate, trimethylolpropane triethoxytri ( (Meth) acrylate, trimethylolpropane tetraethoxytri (meth) acrylate, trimethylolpropane pentaethoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, or dipentaerythritol Ritolol hexa (meth) acrylate is preferred, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane diethoxytri (meth) acrylate, trimethylolpropane triethoxytri (meth) acrylate, trimethylolpropane Methylolpropane tetraethoxytri (meth) acrylate, trimethylolpropane pentaethoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol penta (meth) acrylate, or dipentaerythritol hex (Meth) acrylate is more preferable, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, or dipentaerythritol hexa (meth) Acrylate is more preferred.

  The content ratio of (B) the photopolymerizable compound is preferably 30 to 80 parts by mass, and 40 to 70 parts by mass with respect to 100 parts by mass of the total amount of (A) the binder polymer and (B) the photopolymerizable compound. It is more preferable that In terms of excellent photocurability and coating properties on the formed conductive film 2, it is preferably 30 parts by mass or more, and in terms of excellent storage stability when wound as a film, it is 80 parts by mass or less. Preferably there is.

  (C) As a photoinitiator, a conventionally well-known thing can be especially used without a restriction | limiting, if the photosensitive resin layer 3 can be hardened by irradiation of actinic light. Among these, an aromatic ketone compound, an oxime ester compound, or a phosphine oxide compound is preferable, and an oxime ester compound or a phosphine oxide compound is more preferable, from the viewpoint of excellent transparency and resolution of the formed conductive pattern, and an oxime ester compound. Is more preferable.

Among the aromatic ketone compounds, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 is preferable.
Among the phosphine oxide compounds, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (product name “LUCIRIN TPO” manufactured by BASF Corporation) is preferable.
Among the oxime ester compounds, 1- [4- (phenylthio) phenyl] -1,2-octanedione, 2- (O-benzoyloxime) (manufactured by BASF Corporation, product name “OXE-01”) is preferable. .

  The content ratio of (C) the photopolymerization initiator is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of (A) the binder polymer and (B) the photopolymerizable compound, and 1 to 8 parts. More preferably, it is 1 part by mass, and still more preferably 1-5 parts by mass. In terms of excellent photosensitivity, it is preferably 0.1 parts by mass or more, and in terms of excellent resolution, it is preferably 10 parts by mass or less.

  If necessary, the photosensitive resin layer 3 may have an adhesion-imparting agent such as a silane coupling agent, a plasticizer such as p-toluenesulfonamide, a filler, an antifoaming agent, a flame retardant, a stabilizer, a leveling agent, Additives such as a peeling accelerator, an antioxidant, a fragrance, an imaging agent, and a thermal crosslinking agent can be contained. It is preferable that the addition amount of these additives is 0.01-20 mass parts, respectively with respect to 100 mass parts of total amounts of (A) binder polymer and (B) photopolymerizable compound.

  The photosensitive resin layer 3 is formed on the support film 1 on which the conductive film 2 is formed, as required, methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide, propylene glycol monomethyl. It can form by apply | coating and drying the solution of the photosensitive resin composition about 10-60 mass% of solid content melt | dissolved in solvents, such as ether, or these mixed solvents. However, in this case, the amount of the remaining organic solvent in the photosensitive resin layer 3 after drying is preferably 2% by mass or less in order to prevent the organic solvent from diffusing in the subsequent step.

  The photosensitive resin layer 3 can be applied by a known method such as a roll coating method, a comma coating method, a gravure coating method, an air knife coating method, a die coating method, a bar coating method, or a spray coating method. After coating, drying for removing the organic solvent and the like can be performed at 70 to 150 ° C. for about 5 to 30 minutes with a hot air convection dryer or the like.

  Although the thickness of the photosensitive resin layer 3 changes with uses, it is preferable that it is 1-50 micrometers in thickness after drying, it is more preferable that it is 1-30 micrometers, and it is still more preferable that it is 1-15 micrometers, A thickness of 10 μm is particularly preferable. When the thickness is 1 μm or more, layer formation by coating tends to be easy, and when the thickness is 50 μm or less, light transmittance is good, sufficient sensitivity can be obtained, and the photocurability of the photosensitive resin layer 3 tends to be improved. There is. The thickness of the photosensitive resin layer 3 can be measured with a scanning electron microscope.

  In the photosensitive conductive film 10, the photosensitive layer 4 (laminated body of the conductive film 2 and the photosensitive resin layer 3) has a minimum light transmittance in a wavelength region of 400 to 700 nm when the film thickness is 1 to 10 μm. It is preferably 80% or more, and more preferably 85% or more. When the photosensitive layer 4 satisfies such conditions, the visibility of the display panel is further improved.

  The photosensitive conductive film 10 may further have a protective film so as to be in contact with the surface of the photosensitive resin layer 3 opposite to the support film 1 side.

  As the protective film, for example, a polymer film having heat resistance and solvent resistance such as a polyethylene terephthalate film, a polypropylene film, and a polyethylene film can be used. Moreover, you may use the polymer film similar to the above-mentioned support film 1 as a protective film.

  The adhesive force between the protective film and the photosensitive resin layer 3 may be weaker than the adhesive force between the photosensitive layer 4 and the support film 1 in order to facilitate the peeling of the protective film from the photosensitive resin layer 3. preferable.

Moreover, it is preferable that the number of fish eyes with a diameter of 80 micrometers or more contained in a protective film is 5 pieces / m < ² > or less. "Fish eye" means that when a material is melted by heat, kneaded, extruded, biaxially stretched, casting method, etc., foreign materials, undissolved materials, oxidized degradation products, etc. It is taken in.

  The thickness of the protective film is preferably 1 to 100 μm, more preferably 5 to 50 μm, still more preferably 5 to 30 μm, and particularly preferably 15 to 30 μm. The thickness of the protective film is preferably 1 μm or more from the viewpoint of excellent mechanical strength, and preferably 100 μm or less from the viewpoint of being relatively inexpensive.

  The photosensitive conductive film 10 may further have layers such as an adhesive layer and a gas barrier layer on the support film 1.

  The photosensitive conductive film 10 can be stored, for example, in the form of a flat plate as it is or in the form of a roll wound around a cylindrical core. At this time, it is preferable that the support film 1 is wound up so as to be the outermost side. Moreover, when the photosensitive conductive film 10 does not have a protective film, this photosensitive conductive film 10 can be stored in a flat plate form as it is.

  The core is not particularly limited as long as it is conventionally used, and examples thereof include polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, ABS resin (acrylonitrile-butadiene-styrene copolymer). Moreover, it is preferable to install an end surface separator on the end surface of the photosensitive conductive film 10 wound up in a roll shape from the viewpoint of end surface protection, and in addition, it is preferable to install a moisture-proof end surface separator from the viewpoint of edge fusion resistance. . Moreover, when packaging the photosensitive conductive film 10, it is preferable to wrap it in a black sheet with low moisture permeability.

<Method for forming conductive pattern>
The conductive pattern forming method according to this embodiment includes a photosensitive resin layer 3 provided on a substrate, and a conductive film containing conductive fibers provided on the surface of the photosensitive resin layer 3 opposite to the substrate. 2 is exposed to an actinic ray in the form of a pattern in the absence of oxygen, and an unexposed portion of the photosensitive layer 4 is removed using an alkaline developer, thereby forming a conductive pattern. A developing step for forming, and a cleaning step for cleaning the conductive pattern formed in the developing step using an acidic aqueous solution containing an organic acid.

  A method for forming the photosensitive layer 4 is not particularly limited, and a method for forming the photosensitive layer 4 by providing the conductive layer 2 by coating on the photosensitive resin layer 3 provided on the substrate, and the photosensitive conductive layer described above. The method etc. which form the photosensitive layer 4 by laminating | stacking the film 10 so that the photosensitive resin layer 3 closely_contact | adheres to a board | substrate are mentioned. The photosensitive layer 4 is preferably formed using the photosensitive conductive film 10. Hereinafter, the formation method of the conductive pattern of this embodiment using the photosensitive conductive film 10 is demonstrated using drawing.

  FIG. 3 is a schematic cross-sectional view for explaining a preferred embodiment of a method for forming a conductive pattern according to this embodiment. As shown in FIG. 3, the conductive pattern forming method according to the present embodiment includes a photosensitive conductive film 10 having a support film 1, a conductive film 2, and a photosensitive resin layer 3, and a photosensitive resin layer 3 on a substrate 20. A laminating step (FIG. 3A) for laminating in close contact, an exposure step (FIG. 3B) for irradiating a predetermined portion of the photosensitive layer 4 having the supporting film 1 with an actinic ray L, and then a supporting film 1 is peeled, the photosensitive layer 4 after the exposure process is developed to form a conductive pattern (conductive film 2a), and then the conductive pattern (conductive film 2a) is washed with an acidic aqueous solution ((c in FIG. 3). )). The conductive pattern thus obtained has the thickness of the cured resin layer 3b (cured product of the photosensitive resin layer 3) in addition to the thickness of the conductive film 2a. These thicknesses become the step Hb. As the level difference Hb is smaller, the smoothness required for a display or the like is easily obtained. Moreover, when the level difference Hb is large, the conductive pattern is easily visually recognized.

  Examples of the substrate 20 include a glass substrate or a plastic substrate such as polycarbonate, polyethylene terephthalate, and cycloolefin polymer. The thickness of the substrate 20 can be appropriately selected according to the purpose of use. The substrate may be in the form of a film. The substrate 20 preferably has a minimum light transmittance of 80% or more in a wavelength region of 400 to 700 nm.

  The photosensitive layer 4 is preferably provided by laminating a separately prepared photosensitive conductive film 10 on the substrate 20. By this method, the photosensitive layer 4 can be easily formed on the substrate 20, and productivity can be improved.

The laminating step is performed, for example, by pressing the photosensitive conductive film 10 to the substrate 20 while heating the photosensitive conductive film 10 after removing the protective film, if any. In addition, it is preferable to perform this operation under reduced pressure from the viewpoint of adhesion and followability.
The lamination of the photosensitive conductive film 10 is preferably performed by heating the photosensitive resin layer 3 or the substrate 20 to 70 to 130 ° C., and the pressure bonding pressure is about 0.1 to 1.0 MPa (about 1 to 10 kgf / cm ² ). However, these conditions are not particularly limited. If the photosensitive resin layer 3 is heated to 70 to 130 ° C. as described above, it is not necessary to pre-heat the substrate 20 in advance, but the substrate 20 is pre-heated in order to further improve the stackability. You can also.

  Examples of the exposure method in the exposure step include a method (mask exposure method) of irradiating actinic rays in an image form through a negative or positive mask pattern called an artwork as shown in FIG. A known light source is used as the active light source. Specifically, a carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, or the like is used. Further, an Ar ion laser, a semiconductor laser, a photographic flood bulb, a solar lamp, or the like may be used. Alternatively, a method of irradiating actinic rays in an image shape by a direct drawing method using a laser exposure method or the like may be employed.

Exposure at the exposure step may vary depending on the composition of the device and the photosensitive resin composition ^used, and is preferably from ^{5mJ / cm 2 ~1000mJ / cm 2} , 10mJ / cm 2 ~200mJ / cm 2 is more preferable. In terms of excellent photocurability, it is preferably 10 mJ / cm ² or more, and in terms of resolution, it is preferably 200 mJ / cm ² or less.

  The exposure step is preferably performed without peeling off the support film 1. By exposing the photosensitive layer 4 without peeling off the support film 1, the influence of oxygen is reduced and the film is easily cured. The exposure process can be performed in air, vacuum, or the like, and the exposure atmosphere is not particularly limited.

  Further, the conductive pattern forming method according to the present invention is a second exposure step of irradiating a part or all of an unexposed portion in the exposure step with actinic rays in the presence of oxygen after the exposure step and before the development step. It is preferable to provide.

  FIG. 4 is a schematic cross-sectional view for explaining another preferred embodiment of the method for forming a conductive pattern according to this embodiment. The conductive pattern forming method according to the present embodiment includes a laminating step ((a) in FIG. 4) for laminating the above-described photosensitive conductive film 10 so that the photosensitive resin layer 3 is in close contact with the substrate 20, and a support film. A first exposure step (FIG. 4B) for irradiating a predetermined portion of the photosensitive layer 4 having 1 with an actinic ray, and then the support film 1 is peeled off and then in the presence of oxygen in the first exposure step. A second exposure step (FIG. 4C) for irradiating a part or all of the exposed and unexposed portions with an actinic ray, and developing the photosensitive layer 4 after the exposure step to form a conductive pattern (conductive film 2a). After forming, the process ((d) of FIG. 4) of wash | cleaning a conductive pattern (conductive film 2a) using acidic aqueous solution is provided. The second exposure step may be performed in the presence of oxygen, and is preferably performed in air, for example. Further, the second exposure step may be performed under a condition where the oxygen concentration is increased.

  According to the method of FIG. 4, the surface portion of the photosensitive resin layer 3 exposed in the second exposure step that is not sufficiently cured is removed by development. Specifically, the surface portion of the photosensitive resin layer 3 that is not sufficiently cured by the wet phenomenon, that is, the surface layer including the conductive film 2 is removed. As a result, a cured resin layer that does not have the conductive film 2 is provided on the substrate 20 together with the conductive pattern, and the level difference Ha between the conductive pattern and the substrate 20 can be reduced as compared with the case where only the conductive pattern is provided on the substrate 20. Can be small.

  The step Ha formed by the method of FIG. 4 is preferably 1 μm or less. By setting the level difference Ha to the above range, the conductive pattern 2a is less visible and the entrainment of bubbles when bonded to a new photosensitive conductive film 10 is suppressed. 42 can be produced. From the same viewpoint, the level difference Ha is more preferably 0.7 μm or less, and further preferably 0.5 μm or less. The level difference Ha of the conductive pattern 2a can be adjusted by controlling the exposure amount in the second exposure step.

  The step Ha of the conductive pattern 2a can be measured with a scanning electron microscope. The entrainment of bubbles derived from the step Ha can be observed with an optical microscope.

  As an exposure method in the second exposure step, a mask exposure method and a method of irradiating the entire photosensitive resin layer 3 with actinic rays without using a mask can be selected as necessary. When the mask exposure method is performed, as shown in FIG. 4C, for example, the active light L can be irradiated in an image form through the mask pattern 5.

  In addition, when the mask exposure method is performed in the second exposure step, as shown in FIG. 4D, a conductive pattern substrate 42 in which the unexposed portions are removed by development is obtained.

  In the more preferable method for forming a conductive pattern according to the present embodiment, by performing exposure twice, the portion exposed in the previous exposure step is not exposed in the second exposure step. It can prevent that a boundary part arises between the exposed part and the part exposed by the 2nd exposure process, and can prevent that the level | step difference between a conductive pattern and the board | substrate 20 becomes large. In addition, when an exposure part is fully hardened | cured at the previous exposure process, the said part does not need to be exposed at a 2nd exposure process.

  The actinic ray light source in the second exposure step is the same as that mentioned in the first exposure step. The second exposure step is performed in the presence of oxygen, for example, preferably in the air. Further, the condition of increasing the oxygen concentration may be used. In the second exposure step, when the support film 1 is laminated on the photosensitive layer 4, the support film 1 is removed and the photosensitive layer 4 is exposed.

Exposure at the second exposure step may vary depending on the composition of the device and the photosensitive resin composition used ^is preferably from ^{5mJ / cm 2 ~1000mJ / cm 2} , 10mJ / cm 2 ~200mJ / cm 2 more ^preferably, it is more preferably ^{30mJ / cm 2 ~150mJ / cm 2} . In terms of excellent photocurability, it is preferably 10 mJ / cm ² or more, and in terms of work efficiency, it is preferably 200 mJ / cm ² or less.

  In the second exposure step, reactive species generated from the photopolymerization initiator on the exposed surface side of the photosensitive layer 4 (the conductive film 2 and the photosensitive resin layer 3) are deactivated by oxygen, so that the conductive film of the photosensitive resin layer 3 is obtained. A region with insufficient curing can be provided on the two sides. Since excessive exposure sufficiently cures the entire photosensitive resin composition, the exposure amount in the second exposure step is preferably within the above range.

  When performing a 2nd exposure process, the surface part which is not fully hardened | cured of the photosensitive resin layer 3 exposed at the 2nd exposure process is removed at a development process. Specifically, the surface portion of the photosensitive resin layer 3 that is not sufficiently cured, that is, the surface layer including the conductive film 2 is removed by wet development. Thereby, the conductive film 2 having a predetermined pattern remains on the cured resin layer in the areas exposed in the first and second exposure processes, and the conductive film 2 is not present in the portion removed in the development process. A cured resin layer is formed. Thus, as shown in FIG. 4D, the conductive pattern 2a formed on the cured resin layer 3a has a small step Ha, and a conductive pattern substrate 42 having a conductive pattern with a small step is obtained.

  The wet development is performed by a known method such as spraying, rocking immersion, brushing, or scraping, using a developer corresponding to a photosensitive resin such as an alkaline aqueous solution, an aqueous developer, or an organic solvent developer. .

As the developer, an alkaline aqueous solution is preferably used because it is safe and stable and has good operability. Examples of the base used in the alkaline aqueous solution include alkali hydroxides such as lithium, sodium or potassium hydroxide, alkali carbonates such as lithium, sodium, potassium or ammonium carbonate or bicarbonate, potassium phosphate, sodium phosphate And alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate.
Among these, sodium carbonate, potassium carbonate, sodium hydroxide, and sodium borate are preferably used. As alkaline aqueous solution used for development, 0.1-5 mass% sodium carbonate aqueous solution, 0.1-5 mass% potassium carbonate aqueous solution, 0.1-5 mass% sodium hydroxide aqueous solution, 0.1-5 mass% A sodium borate aqueous solution is preferably used.
The pH of the alkaline aqueous solution used for development is preferably in the range of 9 to 11, and the temperature is adjusted according to the developability of the photosensitive resin layer 3.
In the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for accelerating development, and the like may be mixed. In the present specification, an alkaline aqueous solution mixed with an organic solvent is referred to as an alkaline quasi-aqueous developer.

  As the developer, an aqueous developer composed of water or an alkaline aqueous solution and one or more organic solvents may be used. Here, as the base contained in the alkaline aqueous solution, in addition to the above-mentioned bases, borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3 -Propanediol, 1,3-diaminopropanol-2-morpholine and the like.

  Examples of the organic solvent include diacetone alcohol, acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether. Can be mentioned.

  The aqueous developer preferably has an organic solvent concentration of 2 to 90% by mass, and the temperature can be adjusted according to the developability. Furthermore, the pH of the aqueous developer is preferably as low as possible within a range where the resist can be sufficiently developed, preferably pH 8-12, more preferably pH 9-10. In addition, a small amount of a surfactant, an antifoaming agent, or the like can be added to the aqueous developer.

  Examples of the organic solvent developer include 1,1,1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. These organic solvents preferably add water in the range of 1 to 20% by mass in order to prevent ignition.

  Examples of the development method include a dip method, a battle method, a spray method, brushing, and slapping. Among these, it is preferable to use a high-pressure spray system from the viewpoint of resolution.

  The method for forming a conductive pattern according to the present embodiment includes a cleaning step of cleaning with an acidic aqueous solution containing an organic acid after forming the conductive pattern by a development step. By washing with an acidic aqueous solution containing an organic acid, the unstable salt remaining in the conductive pattern can be effectively returned to the acidic functional group, and as a result, the high temperature is obtained without depending on the composition of the silver paste. It is possible to form a conductive pattern that does not cause disconnection failure with the silver paste even under high humidity conditions.

  The cleaning method in the cleaning step is not particularly limited, and examples thereof include a dipping method, a battle method, a spray method, a spin method, brushing, and slapping. Moreover, you may use these methods together as needed.

  Examples of organic acids include carboxylic acids such as formic acid, acetic acid, malonic acid, and succinic acid, hydroxy acids such as lactic acid, salicylic acid, malic acid, tartaric acid, and citric acid, methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid. Examples thereof include sulfonic acid. Since the organic acid does not react with the conductive fiber, the use of the organic acid can prevent the conductive fiber from being corroded by the acid. Furthermore, it is possible to prevent the conductive fibers from being corroded by returning the unstable salt in the conductive pattern to the acidic functional group and reducing the residual amount of metal ions. Among these organic acids, the salt in the conductive pattern can be effectively returned to the acidic functional group without reacting with the conductive fiber in the conductive film, that is, without corroding the conductive fiber. Carboxylic acids and hydroxy acids are preferred.

  In this embodiment, an inorganic acid is not preferable as the acid of the acidic aqueous solution. This is because the inorganic acid reacts with the conductive fiber and corrodes the conductive fiber. Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid and the like. The acidic aqueous solution may contain an inorganic acid in combination with an organic acid as long as the effect of the present invention is not impaired, but the content of the inorganic acid in the acidic aqueous solution is 0.01% by mass or less. It is more preferable that the inorganic acid is not included.

  The pH of the acidic aqueous solution is preferably 0 to 6, more preferably 1 to 5, and still more preferably 2 to 4. If the pH is 0 or more, the acidity and corrosivity are not too strong, and if the pH is 6 or less, the unstable salt remaining in the conductive pattern can be effectively returned to the acidic functional group. . The temperature of the acidic aqueous solution is adjusted according to the pH. From the viewpoint of handleability and safety, the temperature of the acidic aqueous solution is preferably 10 ° C to 40 ° C, and more preferably 20 ° C to 30 ° C. Further, a surface active agent, an antifoaming agent, an organic solvent or the like may be mixed in the acidic aqueous solution.

  After the cleaning step, the conductive pattern may be further cleaned using water or a cleaning liquid composed of separately prepared water and the organic solvent used in the developer as necessary. The concentration of the organic solvent is preferably 0 to 90% by mass, and the temperature can be adjusted in accordance with the detergency.

After the washing step, the conductive pattern may be further cured by heating at about 60 to 250 ° C. or exposure at about 0.2 to 10 J / cm ² as necessary.

  According to the conductive pattern forming method of the present embodiment described above, a transparent conductive pattern can be easily formed on a substrate without forming an etching resist like an inorganic film such as ITO.

<Conductive pattern substrate>
The conductive pattern substrate according to the present embodiment can be obtained by forming a conductive pattern on the substrate by the conductive pattern formation method described above. From the viewpoint that the conductive pattern substrate can be effectively used as a transparent electrode, the surface resistivity of the conductive film 2 or the conductive pattern is preferably 2000Ω / □ or less, more preferably 1000Ω / □ or less, and 500Ω / □. More preferably, it is more preferably 100Ω / □ or less. The surface resistivity can be adjusted by, for example, the concentration of the conductive fiber and the dispersion of the organic conductor or the coating amount.

  In the conductive pattern substrate according to this embodiment, the minimum light transmittance in the wavelength region of 400 to 700 nm is preferably 80% or more, and more preferably 85% or more. When the conductive pattern substrate satisfies such a condition, visibility on a display panel or the like can be further improved.

<Touch panel sensor>
Next, a touch panel sensor including the conductive pattern substrate according to the present embodiment will be described.

  FIG. 5 is a schematic top view illustrating an example of a capacitive touch panel sensor. The touch panel sensor shown in FIG. 5 has a touch screen 102 for detecting a touch position on one surface of a transparent substrate 101, and a transparent electrode 103 that detects a change in capacitance in this region and uses it as an X position coordinate; A transparent electrode 104 having Y position coordinates is provided. Each of the transparent electrodes 103 and 104 having the X and Y position coordinates includes a lead wire 105 for connecting to a driver element circuit for controlling an electric signal as a touch panel, and the lead wire 105 and the transparent electrodes 103 and 104. A connection electrode 106 for connecting the two is disposed. Furthermore, a connection terminal 107 connected to the driver element circuit is disposed at the end of the lead-out wiring 105 opposite to the connection electrode 106.

  FIG. 6 is a schematic view showing an example of a method for manufacturing the touch panel sensor shown in FIG. In this manufacturing method, the transparent electrodes 103 and 104 are formed by the conductive pattern forming method according to the present invention.

  First, as shown in FIG. 6A, a transparent electrode (X position coordinate) 103 is formed on a transparent substrate 101. Specifically, the photosensitive conductive film 10 is laminated so that the photosensitive resin layer 3 is in close contact with the transparent substrate 101. The transferred photosensitive layer 4 (conductive film 2 and photosensitive resin layer 3) is irradiated with actinic rays in a desired shape through a light-shielding mask (exposure process). Thereafter, the light shielding mask is removed, the support film 1 is further peeled off, and the photosensitive layer 4 is irradiated with actinic rays (second exposure step). Then, by developing, the conductive film 2 is removed together with the photosensitive resin layer 3 which is not sufficiently cured, and the conductive pattern 2a is formed. The conductive pattern 2a is washed with an acidic aqueous solution after the development process. The transparent electrode 103 for detecting the X position coordinate is formed by the conductive pattern 2a (FIG. 6B). FIG. 6B is a schematic cross-sectional view taken along the line II of FIG. By forming the transparent electrode 103 by the conductive pattern forming method according to the present invention, it is possible to suppress the occurrence of disconnection failure between the lead-out wiring 105 formed using the silver paste and the transparent electrode 103. . In the method for forming a conductive pattern according to the present invention, the transparent electrode 103 having a small step can be provided by forming the transparent electrode 103 through the second exposure step.

  Subsequently, a transparent electrode (Y position coordinate) 104 is formed as shown in FIG. A new photosensitive conductive film 10 is further laminated on the transparent substrate 101 including the transparent electrode 103 formed by the above-described process, and the transparent electrode 104 for detecting the Y position coordinate is formed by the same operation as described above (FIG. 6 (d)). FIG.6 (d) is a schematic cross section of the II-II cut surface of FIG.6 (c). By forming the transparent electrode 104 by the conductive pattern forming method according to the present invention, it is possible to suppress the occurrence of a disconnection failure between the lead-out wiring 105 formed using the silver paste and the transparent electrode 104. . Further, in the method for forming a conductive pattern according to the present invention, even if the transparent electrode 104 is formed on the transparent electrode 103 by forming the transparent electrode 104 through the second exposure step, the step and the bubble A highly smooth touch panel sensor in which the reduction in visibility due to engraving is sufficiently suppressed can be manufactured.

  Next, on the surface of the transparent substrate 101, a lead wire 105 for connecting to an external circuit and a connection electrode 106 for connecting the lead wire 105 and the transparent electrodes 103 and 104 are formed (not shown). In FIG. 6, the lead-out wiring 105 and the connection electrode 106 are shown to be formed after the formation of the transparent electrodes 103 and 104, but they may be formed at the same time as each transparent electrode is formed. The lead-out wiring 105 can be formed at the same time as the connection electrode 106 is formed by screen printing using a conductive paste material containing flaky silver, for example.

  7 and 8 are partial cross-sectional views along a-a 'and b-b' shown in FIG. 5, respectively. These indicate the intersections of the transparent electrodes at the XY position coordinates. As shown in FIGS. 7 and 8, in the method for forming a conductive pattern according to the present invention, a transparent electrode is formed through the second exposure step, thereby obtaining a touch panel sensor with small steps and high smoothness. be able to.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

<Preparation of conductive dispersion (silver fiber dispersion)>
[Preparation of silver fiber by polyol method]
In a 2000 ml three-necked flask, 500 ml of ethylene glycol was placed and heated to 160 ° C. with an oil bath while stirring with a magnetic stirrer under a nitrogen atmosphere. A separately prepared solution prepared by dissolving ₂ mg of PtCl ₂ in 50 ml of ethylene glycol was added dropwise thereto. After 4 to 5 minutes, a solution of 5 g of AgNO ₃ dissolved in 300 ml of ethylene glycol and a solution of 5 g of polyvinylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) having a weight average molecular weight of 40,000 in 150 ml of ethylene glycol were prepared. The solution was dropped from each dropping funnel over 1 minute, and then stirred at 160 ° C. for 60 minutes.

  The reaction solution was allowed to stand at 30 ° C. or less, diluted 10-fold with acetone, centrifuged at 2000 rpm for 20 minutes with a centrifuge, and the supernatant was decanted. Acetone was added to the precipitate and stirred, followed by centrifugation under the same conditions as described above, and acetone was decanted. Then, it centrifuged twice similarly using distilled water, and obtained the silver fiber. When the obtained silver fiber was observed with an optical microscope, the fiber diameter (diameter) was about 5 nm, and the fiber length was about 5 μm.

[Preparation of silver fiber dispersion]
The silver fiber obtained above was dispersed in pure water so that the concentration was 0.2% by mass and pentaethylene glycol monododecyl ether was 0.1% by mass to obtain a silver fiber dispersion.

<(A) component: Preparation of binder polymer solution (A1)>
A flask equipped with a stirrer, a reflux condenser, an inert gas inlet and a thermometer was charged with the material (1) shown in Table 1, heated to 80 ° C. in a nitrogen gas atmosphere, and the reaction temperature was increased to 80 ° C. ± While keeping at 2 ° C., the material (2) shown in Table 1 was uniformly dropped over 4 hours. After dropping of the material (2), stirring was continued at 80 ° C. ± 2 ° C. for 6 hours to obtain a binder polymer solution (A1) (solid content: 50% by mass).

<Preparation of binder polymer solution (A2)>
A flask equipped with a stirrer, reflux condenser, inert gas inlet and thermometer was charged with the material (1) shown in Table 2, heated to 80 ° C. in a nitrogen gas atmosphere, and the reaction temperature was 80 ° C. ± While maintaining at 2 ° C., the material (2) shown in Table 2 was uniformly dropped over 4 hours. After dropwise addition of the material (2), stirring was continued at 80 ° C. ± 2 ° C. for 6 hours to obtain a binder polymer solution (A2) (solid content: 50% by mass).

<Preparation of binder polymer solution (A3)>
A flask equipped with a stirrer, reflux condenser, inert gas inlet and thermometer was charged with the material (1) shown in Table 3, heated to 80 ° C. in a nitrogen gas atmosphere, and the reaction temperature was increased to 80 ° C. ± While maintaining at 2 ° C., the material (2) shown in Table 3 was uniformly added dropwise over 4 hours. After dripping the material (2), stirring was continued at 80 ° C. ± 2 ° C. for 6 hours to obtain a binder polymer solution (A3) (solid content 50% by mass).

<Evaluation of binder polymer solution>
About the produced binder polymer solution (A1)-(A3), the weight average molecular weight and oxidation were measured with the following method. The results are shown in Table 4.

(1) Weight average molecular weight The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC), and was derived by conversion using a standard polystyrene calibration curve. The GPC conditions are shown below.
[GPC conditions]
Pump: Hitachi L-6000 type (manufactured by Hitachi, Ltd., product name)
Column: Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (above, manufactured by Hitachi Chemical Co., Ltd., product name)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (manufactured by Hitachi, Ltd., product name)

(2) Acid value The acid value was measured as follows. First, the binder polymer solution was heated at 130 ° C. for 1 hour to remove volatile components, thereby obtaining a solid polymer. Then, after precisely weighing 1 g of the solid polymer, the precisely weighed polymer was put into an Erlenmeyer flask, and 30 g of acetone was added and dissolved uniformly. Next, an appropriate amount of an indicator, phenolphthalein, was added to the solution, and titration was performed using a 0.1N aqueous KOH solution. And the acid value was computed by following Formula.
Acid value = 10 × Vf × 56.1 / (Wp × I / 100)
In the formula, Vf represents the titration amount (mL) of the KOH aqueous solution, Wp represents the mass (g) of the measured resin solution, and I represents the proportion (mass%) of the non-volatile content in the measured resin solution.

Example 1
<Preparation of photosensitive conductive film>
[Preparation of conductive film]
The silver fiber dispersion obtained above is uniformly applied at a coating amount of 25 g / m ² on a 50 μm-thick polyethylene terephthalate film (PET film, manufactured by Teijin Ltd., product name “G2-50”) as a support film. And dried for 3 minutes with a hot air convection dryer at 100 ° C. to form a conductive film. In addition, the film thickness after drying of the electrically conductive film was about 0.1 micrometer.

[Preparation of photosensitive resin composition solution]
The material shown in Table 5 was mix | blended in the quantity (mass part) shown in Table 5, and it mixed for 15 minutes using the stirrer, and prepared the photosensitive resin composition solution. In addition, the compounding quantity of (A) component in Table 5 is a mass part of solid content except a solvent.

The symbols in Table 5 have the following meanings.
[Component (B)]
PET-30: Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd.)
[Component (C)]
OXE-01: 1,2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (o-benzoyloxime)] (manufactured by BASF Corporation)
[Other ingredients]
SH-30: Octamethylcyclotetrasiloxane (manufactured by Toray Dow Corning Co., Ltd., silicone leveling agent)

[Preparation of photosensitive conductive film]
The said photosensitive resin composition solution was apply | coated uniformly on the said electrically conductive film formed on the said PET film, and it dried for 10 minutes with a 100 degreeC hot air convection dryer, and formed the photosensitive resin layer. Thereafter, the photosensitive resin layer was covered with a polyethylene protective film (manufactured by Tamapoly Co., Ltd., product name “NF-13”, thickness 28 μm) to obtain a photosensitive conductive film. The dried film thickness of the photosensitive layer (laminated body of conductive film and photosensitive resin layer) was 5 μm.

[Measurement of light transmittance]
Laminator (manufactured by Hitachi Chemical Co., Ltd., product name “HLM-”) is formed so that the photosensitive resin layer is in contact with the glass substrate on a glass substrate having a thickness of 1 mm while peeling off the protective film. 3000 type ”), a glass substrate having a roll temperature of 110 ° C., a substrate feed speed of 1 m / min, and a pressure (cylinder pressure) of 4 × 10 ⁵ Pa (thickness of 1 mm, length of 10 cm × width of 10 cm) was used. The substrate was laminated under the condition of a linear pressure of 9.8 × 10 ³ N / m), and a photosensitive conductive film including a support film (PET film) was laminated on a glass substrate.

Next, using a parallel light exposure machine (product name “EXM1201” manufactured by Oak Manufacturing Co., Ltd.) on the photosensitive conductive film on the substrate, an exposure amount of 5 × 10 ² J / m ² (wavelength from the support film side) After irradiating with ultraviolet rays at a measured value at 365 nm, the support film was removed. This obtained the sample for light transmittance measurement in which the photocured material (film thickness of 5.0 micrometers) of the photosensitive layer which consists of a photosensitive resin layer and a electrically conductive film was laminated | stacked on the glass substrate.

  Subsequently, the visible light transmittance of the obtained sample was measured in a measurement wavelength range of 400 to 700 nm using an ultraviolet-visible spectrophotometer (manufactured by Hitachi Instrument Service Co., Ltd., product name “U-3310”). . The transmittance of the obtained sample was 92% at a wavelength of 700 nm, 91% at a wavelength of 550 nm, and 87% at a wavelength of 400 nm, and it was confirmed that good transmittance was secured.

[Measurement of resistance value]
Using the sample for light transmittance measurement, the sheet resistance value of the photocured material of the photosensitive layer was measured with a non-contact resistance measuring device (product name “NC-10” manufactured by Napson Co., Ltd.). It was 20Ω / □. The resistance measurement probe was contacted from the conductive film side of the sample (opposite side of the glass substrate), and the resistance value was measured.

<Formation of conductive pattern>
The obtained photosensitive conductive film was exposed to a PET film substrate (product name “A4300” manufactured by Toyobo Co., Ltd., length 150 mm × width 150 mm, thickness 125 μm) on the PET film substrate while peeling off the protective film. Using a laminator (product name “HLM-3000 type” manufactured by Hitachi Chemical Co., Ltd.) so that the conductive resin layer is in contact, the roll temperature is 110 ° C., the substrate feed speed is 1 m / min, and the pressure (cylinder pressure) is 4 × 10. Lamination was performed under the condition of ⁵ Pa to prepare a substrate in which a photosensitive conductive film including a support film (PET film) was laminated on a PET film substrate.

After lamination, when the PET film substrate is cooled and the temperature of the substrate reaches room temperature (23 ° C. to 25 ° C.), the line width / space width is 1 mm / 1 mm and the length is 120 mm on the PET film surface as the support film. The artwork having the wiring pattern was brought into close contact. Then, using a parallel light exposure machine (product name “EXM1201” manufactured by Oak Manufacturing Co., Ltd.) on the photosensitive conductive film on the PET film substrate, the exposure amount is 5 × 10 ² J / m ² from the support film side. (Measured value at i-line) was irradiated with ultraviolet rays.

  After the exposure, the substrate was left at room temperature (23 ° C. to 25 ° C.) for 15 minutes, and then the support film was removed. By development, a conductive pattern having a line width / space width of about 1 mm / 1 mm and a length of 120 mm was formed on the PET film substrate.

  Next, the substrate on which the conductive pattern was formed was immersed in a 1% by weight malic acid aqueous solution (pH = 2) at 30 ° C. for 60 seconds to wash the conductive pattern with an acidic aqueous solution, and further washed with pure water. .

Subsequently, using an ultraviolet irradiation device (manufactured by Oak Manufacturing Co., Ltd.), ultraviolet rays were irradiated from the conductive pattern side with an exposure amount of 1 × 10 ⁴ J / m ² (measured value in i-line). Thereby, formation of the conductive pattern on the substrate was completed.

<Silver paste connection reliability evaluation>
The silver paste connection reliability evaluation of the obtained conductive pattern was performed by the following method. Hereinafter, those in which disconnection failure is unlikely to occur between the conductive pattern and the silver paste under high-temperature and high-humidity conditions are referred to as “good silver paste connection reliability”, and those in which disconnection failure is likely to occur are referred to as “silver paste connection reliability”. I'll call it "bad." Also, a method for checking whether the silver paste connection reliability is good or bad will be referred to as a silver paste connection reliability test.

  On the obtained conductive pattern (line pattern having a line width of about 1 mm and a length of 120 mm), silver paste electrodes were formed at intervals of 100 mm. The silver paste electrode was applied so as to have a diameter of 2 mm and a thickness of 1 mm. As the silver paste, TB3351C (manufactured by Three Bond, product name), AF4500 (manufactured by Taiyo Ink Manufacturing Co., Ltd., product name), AF6100 (manufactured by Taiyo Ink Manufacturing Co., Ltd., product name), DW-117H-41 (Toyobo Co., Ltd., product name) and FA-301CA (Fujikura Kasei Co., Ltd., product name) were used. Any silver paste was coated on the conductive pattern, and then heat-treated at 120 ° C./30 minutes with a box-type dryer (manufactured by Enomoto Kasei Co., Ltd., product name “ETAC HISPECHG220”). As described above, a silver paste electrode was formed on the conductive pattern to obtain a silver paste connection reliability evaluation sample of the conductive pattern.

Using the obtained silver paste connection reliability evaluation sample, first, the resistance value between the silver paste electrodes formed at intervals of 100 mm was determined using a pocket tester (manufactured by Custom Co., Ltd., product name “CDM-03D”). Measured. The resistance value was 15 × 10 ³ Ω, and this resistance value was used as the initial value (R0) before the silver paste connection reliability test.

  Next, the silver paste connection reliability evaluation sample was put into a high-temperature and high-humidity layer at 60 ° C. and 90% RH for 100 hours, and then allowed to stand in the atmosphere at room temperature for 1 hour, and then the resistance between the silver paste electrodes was again measured. The value was measured. This resistance value was defined as the resistance value (R1) after the silver paste connection reliability test.

Based on the resistance values R0 and R1 before and after the reliability test, the silver paste connection reliability of the conductive pattern was evaluated in five stages A to D (A is the best). Here, the ratio of R0 to R1 (R1 / R0) was Rr. The results are shown in Table 6.
A: Rr ≦ 1.1
B: 1.1 <Rr ≦ 1.2
C: 1.2 <Rr ≦ 1.5
D: Rr> 1.5 and R1 ≦ 1 × 10 ⁶ Ω
E: Rr> 1.5 and R1> 1 × 10 ⁶ Ω

(Examples 2-9)
The photosensitive conductive composition was the same as in Example 1 except that the photosensitive resin composition solution shown in Table 6 was used, development was performed with an alkaline developer shown in Table 6, and washing was performed with an acidic aqueous solution shown in Table 6. A film and a conductive pattern were prepared. Moreover, about the obtained conductive pattern, the silver paste connection reliability test was implemented by the method similar to Example 1, and silver paste connection reliability was evaluated. The results are shown in Table 6. The development process was performed by spraying an alkaline developer at 30 ° C. for 30 seconds (the same conditions as in Example 1). Moreover, the conditions of the washing | cleaning process by acidic aqueous solution wash | cleaned by immersing a conductive pattern in 30 degreeC acidic aqueous solution for 60 second (same conditions as Example 1).

(Comparative Examples 1-4)
The photosensitive conductive composition was the same as in Example 1 except that the photosensitive resin composition solution shown in Table 7 was used, development with the alkaline developer shown in Table 7, and washing with an acidic aqueous solution were not performed. A film and a conductive pattern were prepared. Moreover, about the obtained conductive pattern, the silver paste connection reliability test was implemented by the method similar to Example 1, and silver paste connection reliability was evaluated. The results are shown in Table 7.

(Comparative Examples 5-7)
Except for using the photosensitive resin composition solution shown in Table 7, developing with an alkaline developer shown in Table 7, and washing with an acidic aqueous solution containing an inorganic acid instead of an organic acid as shown in Table 7. In the same manner as in Example 1, a photosensitive conductive film and a conductive pattern were produced. Moreover, about the obtained conductive pattern, the silver paste connection reliability test was implemented by the method similar to Example 1, and silver paste connection reliability was evaluated. The results are shown in Table 7.

The symbols in Tables 6 and 7 have the following meanings.
[Component (B)]
PET-30: Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd.)
DPHA: Dipentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd.)
[Component (C)]
OXE-01: 1,2-octanedione, 1- [4- (phenylthio) phenyl-, 2- (o-benzoyloxime)] (manufactured by BASF Corporation)
[Other ingredients]
SH-30: Octamethylcyclotetrasiloxane (manufactured by Toray Dow Corning Co., Ltd., silicone leveling agent)
[Alkali developer]
Na ₂ CO ₃ : Sodium carbonate TMAH: Tetramethylammonium hydroxide

  As shown in Table 6, in Examples 1 to 9 in which washing with an acidic aqueous solution containing an organic acid was performed after the development step, the silver paste connection reliability was good regardless of the type of silver paste. Met.

  On the other hand, as shown in Table 7, in Comparative Examples 1 to 4 where washing with an acidic aqueous solution was not performed after the development step, the silver paste connection reliability was inferior. Moreover, also in Comparative Examples 5-7 which performed washing | cleaning with the acidic aqueous solution containing an inorganic acid instead of an organic acid after the image development process, it was a result similarly inferior to silver paste connection reliability.

  According to the method for forming a conductive pattern of the present invention, a conductive pattern that can suppress the occurrence of disconnection failure between the conductive pattern and the silver paste even under high temperature and high humidity conditions without depending on the composition of the silver paste is provided. can do. Moreover, according to this invention, a conductive pattern board | substrate and a touch panel sensor provided with the conductive pattern formed by the said method can be provided.

DESCRIPTION OF SYMBOLS 1 ... Support film, 2 ... Conductive film, 2a ... Conductive pattern, 3 ... Photosensitive resin layer, 3a, 3b ... Resin hardened layer, 4 ... Photosensitive layer, 5 ... Mask pattern, 10 ... Photosensitive conductive film, 20 ... Substrate 40, 42 ... conductive pattern substrate, 101 ... transparent substrate, 102 ... touch screen, 103 ... transparent electrode (X position coordinate), 104 ... transparent electrode (Y position coordinate), 105 ... lead-out wiring, 106 ... connection electrode, 107 …Connecting terminal.

Claims (12)

A photosensitive layer comprising a photosensitive resin layer provided on a substrate and a conductive film containing conductive fibers provided on a surface of the photosensitive resin layer opposite to the substrate, in the absence of oxygen. , An exposure step of irradiating actinic rays in a pattern, and
A developing step of forming a conductive pattern by removing an unexposed portion of the photosensitive layer using an alkali developer;
A cleaning step of cleaning the conductive pattern formed in the development step using an acidic aqueous solution containing an organic acid;
A method for forming a conductive pattern.   A photosensitive conductive film having a support film, a conductive film provided on the support film, and a photosensitive resin layer provided on the conductive film, so that the photosensitive resin layer is in close contact with the substrate. The method for forming a conductive pattern according to claim 1, wherein the photosensitive layer is provided by laminating. After the exposure step and before the development step,
The method for forming a conductive pattern according to claim 1, further comprising a second exposure step of irradiating a part or all of an unexposed portion in the exposure step of the photosensitive layer with an actinic ray in the presence of oxygen. After the exposure step and before the development step,
3. The method according to claim 2, further comprising a second exposure step of irradiating a part or all of an unexposed portion in the exposure step of the photosensitive layer with an actinic ray in the presence of oxygen after peeling the support film. Method for forming a conductive pattern.   The photosensitive resin layer contains (A) a binder polymer, (B) a photopolymerizable compound, and (C) a photopolymerization initiator, and contains an oxime ester compound as the component (C). The method for forming a conductive pattern according to claim 4.   The method for forming a conductive pattern according to claim 1, wherein the conductive fiber is a silver fiber.   The method for forming a conductive pattern according to any one of claims 1 to 6, wherein the pH of the acidic aqueous solution is 0 to 6.   The method for forming a conductive pattern according to claim 1, wherein the alkaline developer is an alkaline aqueous solution.   The method for forming a conductive pattern according to claim 1, wherein the alkaline developer is an alkaline quasi-aqueous developer composed of an alkaline aqueous solution and one or more organic solvents.   The method for forming a conductive pattern according to claim 1, wherein the photosensitive resin layer includes a compound having at least one of a carboxyl group and a phenolic hydroxyl group.   A conductive pattern substrate comprising: a substrate; and a conductive pattern formed on the substrate by the method for forming a conductive pattern according to claim 1.   A touch panel sensor comprising the conductive pattern substrate according to claim 11.

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