JPH053690B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a substrate having a novel transparent conductive circuit, and its purpose is to manufacture a transparent substrate with excellent quality through a manufacturing process that is simpler than conventional etching methods, lift-off methods, etc. The present invention relates to an economically advantageous method of manufacturing a substrate having a conductive circuit. The present invention relates to materials for liquid crystal displays, electrochromic displays, electrophotographic recording media, electrophoretic recording media, transparent switches, connectors, flexible circuits, antistatic bodies, planar heating elements, solar cells, conductors, etc. The present invention can be applied to a method of manufacturing a substrate having a transparent conductive circuit, which is useful in various industrial fields of electrical and electronic industries. The following method is known as a method of manufacturing a substrate having a transparent conductive circuit. That is, metal thin films such as gold, silver, palladium, tin oxide,
After forming a thin film of metal oxide such as indium oxide, antimony oxide, or cadmium tin oxide on the entire surface of a glass substrate, plastic substrate, sheet substrate, or film substrate by vacuum evaporation, sputtering, or printing, the necessary A circuit masking layer is formed on the conductive circuit portion by a photoresist method or a screen printing method. Next, after removing unnecessary metal thin film pattern parts or metal oxide thin film pattern parts by wet or dry etching method, a transparent conductive circuit is formed by removing the masking layer. However, these methods had the following drawbacks. That is, when forming a masking layer with photoresist, coating of photosensitive resin,
Processes such as pattern baking, development, and photoresist removal are required, resulting in poor workability, and when forming a masking layer with resist ink using the screen printing method, production is slow due to the long drying time required. It had problems such as poor performance and the need for a variety of expensive materials, and was also subject to various limitations in terms of equipment and work. As an example of a method for solving this problem, a thickened etching solution described in JP-A-58-113376 is applied directly to the conductive thin film through a silk screen, and then washed with water, etc. A method of etching a desired pattern using a process has been proposed, but in a follow-up experiment conducted by the inventors
With this method, the etching effect after application of the etching solution cannot be sufficiently confirmed or guaranteed from the appearance, or the reliability regarding adjustment of the holding time after application and cleaning time until completion of etching is extremely low, and there is a possibility that the etching is not completed. If water washing is performed beforehand, there is a risk that unnecessary parts will be eroded, and it is difficult to ensure reproducibility in actual industrial production. It was recognized that there was a strong tendency to lower the quality of products, and that there were many difficult problems in the product inspection process and work management. On the other hand, in the case of the lift-off method, unnecessary pattern parts on the substrate are printed in advance using, for example, water-soluble ink, and then a thin metal film or a thin metal oxide film is formed on the entire surface of the substrate, and then washed with water. A method has been devised in which a desired transparent conductive circuit can be obtained by removing the water-soluble ink pattern using a method that eliminates the need for an etching process from an industrial perspective. This makes the work considerably easier, but although it is an excellent method for mass production, it tends to pose economical problems when producing a wide variety of products in small quantities. In view of the current situation, the inventors of the present invention have devoted many years of intensive research and consideration to solving the problems of the prior art, and as a result, they have succeeded in forming a desired transparent conductive circuit on a substrate. We have finally completed the present invention as a new and remarkable method. This method involves forming a desired pattern on a transparent conductive film using a color-changing ink containing an acidic compound containing an aliphatic carbonyl group and a color-changing compound, and then changing the color of the ink as the reaction progresses. It was discovered that by visually confirming the completion of etching and then removing the ink by washing etc., it was possible to form beautiful transparent conductive circuits with a precision not seen in conventional methods.Based on this knowledge, various types of We investigate the raw material-related conditions and work procedures, etc.
The present invention has finally been completed. That is, the present invention uses a color-changing ink containing an aliphatic carbonyl group-containing acidic compound having at least one group selected from a hydroxyl group, a carbonyl group, a nitro group, a cyano group, and a halogen atom, and a color-changing compound. A method for manufacturing a substrate having a transparent conductive circuit is disclosed, which is characterized in that a pattern is printed on a transparent conductive film on the surface of the substrate, and after visually confirming the discoloration of the ink, the pattern portion is washed and removed. The present invention will be explained in detail below. In the present invention, the aliphatic carbonyl group-containing acidic compound having at least one group selected from a hydroxyl group, a carbonyl group, a nitro group, a cyano group, and a halogen atom preferably satisfies the following conditions. In other words, those that quickly react with and etch the transparent conductive film, those that have good dispersion and solubility without forming gels or precipitates when mixed into the ink binder, those that can be quickly removed by washing, etc. is preferred. Now, the specific names of such compounds are as follows: (a) Examples of compounds with hydroxyl groups: lactic acid, glycolic acid, malic acid, citric acid,
Hydroxybutyric acid, tetrahydroxyadipic acid (b) Examples of carbonyl group-containing acrolein hydrate, adipic acid, acetylacetone, acetoacetic acid, itaconic acid, oxydipropionic acid, citric acid, glyoxal, glyoxylic acid, glycolic acid, ketomalonic acid ,
Succinic acid, diacetyl, oxalic acid, tartaric acid, pimelic acid, pyruvic acid, butanetetracarboxylic acid, fumaric acid, maleic acid, malonic acid, malic acid, levulinic acid (c) Examples of substances with nitro groups Nitroacetic acid, nitropropionic acid (d) Examples of substances containing a cyano group Cyanoacetic acid, cyanopropionic acid (e) Examples of substances containing a halogen atom Chloral, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, chlorofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, hexachloroacetone, penta Chloroacetone, hexafluoroacetone, pentafluoroacetone, perfluoro fatty acid, dibromoacetic acid, tribromoacetic acid Aliphatic monocarbons that do not contain polar groups such as hydroxyl group, carbonyl group, nitro group, cyano group, or halogen atom shown above As a result of many experiments, it was found that even when acids were applied to the method of the present invention, the expected excellent effects could not be expected. Of course, among the aliphatic monocarboxylic acids, formic acid and acetic acid have an etching effect, but they have the disadvantage of achieving a beautiful cleaning and removal effect only on the design area, and only the above-mentioned acidic compounds containing aliphatic carbonyl groups are superior. We got the results. The amount of the acidic compound mentioned above in the present invention is not particularly limited, but is generally 20 parts by weight per 100 parts by weight of the binder in the ink.
It is desirable that the content is between 50 parts by weight and 50 parts by weight. If the amount is less than 20 parts by weight, the etching speed may become slow, discoloration may occur, or the etching may become slow, resulting in operational inconveniences. Moreover, if the amount exceeds 50 parts by weight, side etching may occur during etching, the production and storage of the ink may become difficult, and printability may be impaired. Next, the color-changing compound referred to in the present invention will be explained. The color-changing compound mentioned here includes oxidation-reduction compounds.
A compound that changes color due to a change in pH or a compound that changes color due to the formation of a phosphor. It will be explained in more detail. Compounds that change color due to changes in pH are reagents that sense and detect changes in hydrogen ion concentration on the acidic side.Specific examples of such reagents include methyl violet, methanyl yellow, and metacresol purple. , p-xylenol blue, thymol blue, tropaeolin OO, benzopurpurin 4B, quinaldine red, methyl yellow, bromophenol blue, tetrabromophenol blue, methyl orange, bromochlorophenol blue, α-naphthyl red, alkali alizarin sulfonate, bromcresol green , methyl red, chlorphenol red, benzoyl auramine G, bromcresol purple, bromophenol red, bromthymol blue, etc. alone or as a mixture thereof. For example, Bromcresol Purple 0.05% + Bromthymol Blue 0.05% changes color from yellow to purple (acid to alkaline) at pH 6.7, and Bromcresol Green 0.075% + Methyl Orange 0.05% changes color from orange to green (at PH 4.3). acid to alkali). In addition to the above, compounds in which the change in pH is caused by redox refer to reagents that undergo an oxidation or reduction reaction with transition metal ions, which are components of the transparent conductive film, and change color. are hydroquinones, alkylhydroquinones, polyphenols, polyphenol carboxylic acids,
These include organic peroxides, soluble iron salts, soluble rare earth salts, etc. Compounds that change color due to phosphor production are:
The combination of the transparent conductive film component and the dye component causes a partial change in the structure of the dye component, causing a change in the visible or ultraviolet spectrum, or new fluorescence that is clearly visible to the naked eye. , or a compound that changes the fluorescent color tone, specifically fluorescein and its derivatives, flavone derivatives, and acridine derivatives. In addition to the color-changing compounds explained above, general-purpose binders, solvents, surfactants, antifoaming agents, etc. suitable for various printing methods are added to this color-changing ink and processed into ink. be done. To summarize the above, a color-changing ink is defined as an ink that includes a material that etches a transparent conductive film and a material whose color tone changes depending on the degree of oxidation or reduction of the ink system during etching. As the printing method, a screen printing method, a gravure printing method, a flexographic printing method, an offset printing method, a letterpress printing method, etc. are used. The substrate of the present invention can be either organic or inorganic. Various resin sheets or various resin films can be used as the organic substrate, but polyester film is particularly preferred for printing. As inorganic substrates, materials with good heat resistance such as glass, quartz glass, sapphire, spinel, rutile, zirconia, hafnia, garnet, barium titanate, strontium titanate, mica, asbestos, and various ceramics are used, but they are not economical. For this purpose, substrates such as glass, quartz glass, mica, etc. are advantageous. The transparent conductive film of the present invention has conductivity,
In addition, transparent materials are preferred, such as gold,
Metal thin films such as silver, platinum, palladium, rhodium, etc.
Examples include metal oxide thin films such as tin oxide, indium oxide, antimony oxide, titanium oxide, zirconium oxide, indium oxide-tin oxide, and tin oxide-antimony oxide, but considering etching processability and economic efficiency, indium oxide , tin oxide-based ones seem to be the most preferred. The thickness of these transparent conductive films is 10 Å to 500 Å, and the resistance value is 1 Ω/□ to 10 ⁴ Ω/□ depending on the application of the electric circuit.
Preferably 10Ω/□ to 2000Ω/□. Further, cleaning methods include shower cleaning, bath cleaning, ultrasonic cleaning, microwave cleaning, and the like. At this time, care must be taken not only to completely remove ink residues that impede the transparency of the transparent conductive circuit, but also to avoid damaging the surface of the transparent conductive circuit. From this point of view, industrially, shower cleaning is the preferred method, but in this case, it is desirable that the water pressure is 1 kg/m ² or more, and if it is 1 kg/m ² or less, it is difficult to obtain accurate etched patterns. seems difficult. Also, before the subsequent drying step, it is advisable to wash and drain the material using a sponge roller or the like, and care should be taken to ensure that drying is carried out efficiently. The present inventors conducted numerous experiments regarding the method of the present invention described above and confirmed the superiority of the present invention.In order to further explain the technical contents of the present invention, the following representative examples are presented. This will be shown as an example. It goes without saying that the method of the invention should not be limited solely to the examples shown below, but that its embodiments can be implemented as appropriate. Example 1 A biaxially stretched polyethylene terephthalate film (thickness 0.1 mm, 550 nm, parallel light beam 87%) was
Indium/tin oxide having a composition of indium oxide: tin oxide = 90:10 was deposited by a sputtering method. Sputtering was performed at a vacuum level of 10 ^-3 torr with argon gas introduced, and the deposited film thickness was approximately 100 Å.
It was hot. Next, polyacrylamide resin 100
Add 30g of trichloroacetic acid, 75mg of bromcresol green and 50mg of methyl orange to
Dilute with a mixed solvent of equal parts ethanol and water to bring the total volume to approx.
The weight was 300g, and an ink suitable for silk screening was created. Using this ink, 30 fine lines with a line width of 0.5 mm and a line spacing of 0.5 mm, that is, a 1.0 mm pitch and a length of 100 mm, were printed on the thin film. After 1 minute, the color of the ink changed from orange to greenish. The film is then washed with water to completely remove the ink and then dried. The surface resistance between both ends of each thin wire was 2.1 kΩ, and the insulation between each thin wire was perfect. Examples 2 to 10 Commercially available polyimide film (thickness 25 μm)
Copper was deposited by vacuum evaporation. Adhesive film thickness is approx.
It was 3000Å. On the other hand, synthetic resin 10 shown in Attached Table 1
150 g of an aqueous color-changing ink containing 4 g of an aliphatic carbonyl group-containing acidic compound shown in the attached table and 100 mg of a coloring reagent was prepared. Using the ink, 150 designs with a line width of 1.27 mm and a line spacing of 1.27 mm, that is, a pitch of 2.54 mm and a length of 50 cm, were printed on the copper surface of the polyimide film by gravure printing. 5～20
After the ink had finished discoloring after a few minutes, the film was washed with water to completely remove the ink and then dried.The surface resistance was measured and the results shown in Attached Table 1 were obtained. Examples 11-12 and Comparative Examples 1-3 Metals shown in the attached table were deposited to a thickness of 500 Å on a biaxially stretched polyethylene terephthalate film (thickness 50 μm) by vacuum deposition. Next, 100g of high molecular weight polyethylene glycol,
Apply ink containing 40g of the acidic compound shown in Attached Table 2, 300g of water, and 50mg of the discoloration reagent shown in Attachment 2, leave it for 30 minutes, confirm that the discoloration is complete, wash it with water, completely remove the ink, and dry it. When the surface resistance was measured and the etching effect was tested, the results shown in Attached Table 2 were obtained.

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Claims (1)

[Scope of Claims] 1. Using a color-changing ink containing an acidic compound containing an aliphatic carbonyl group and a color-changing compound having at least one group selected from a hydroxyl group, a carbonyl group, a nitro group, a cyano group, and a halogen atom. A method for manufacturing a substrate having a transparent conductive circuit, which comprises printing a pattern on a transparent conductive film on the surface of the substrate, visually checking for discoloration of the ink, and then washing and removing the pattern. 2. Production of a substrate having a transparent conductive circuit according to claim 1, wherein the color-changing compound is a compound that changes color due to a change in pH including redox, or a compound that changes color due to phosphor formation. Law.