JPH04142517A - Production of transparent electrode - Google Patents

Abstract

PURPOSE:To obtain transparent electrodes by bringing a substrate and the thin-film surface of a sheet formed with a transparent conductive thin film on a base into light contact with each other via an adhesive layer by photoirradiation and further subjecting the surface to the photoirradiation via a mask, then peeling the sheet to allow the thin films of prescribed patterns to remain on the substrate. CONSTITUTION:The way that the adhesive power of the adhesive layer used for tight contact of the substrate and the sheet is changed by the photoirradiation includes the way that the adhesive power is intensified by a photopolymn. or photocrosslinking reaction and the way that the adhesive power is weakened by a photodecomposition reaction according to the compsn. of the adhesive layer. The adhesive layers of both are separated by the photoirradiation to the part where the transparent conductive thin film has the strong adhesive power to the substrate and the part where the adhesive power of the transfer sheet to the base is strong. The thin film of the part where the adhesive power to the substrate is strong remains on the substrate and the thin film of the part where the adhesive power to the base is strong is peeled together with the transfer sheet at the time of peeling the transfer sheet, by which the transparent electrode patterns are formed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to liquid crystal display devices, solar cells, transparent tablets,
The present invention relates to a method for manufacturing transparent electrodes used in liquid crystal light control glasses, anti-fog glasses, etc.

<Conventional technology> Conventionally, methods for manufacturing transparent electrodes include spraying and coating methods that utilize hydrolysis of thin films such as tin oxide, and chemical vapor deposition (hereinafter referred to as "CVD method") that utilizes thermal decomposition reactions. ), or physical vapor deposition methods (hereinafter referred to as It was formed directly on the substrate on which the transparent electrode was to be formed by the rPVD method.

In addition, a common method for patterning transparent electrodes is to protect necessary portions using a photoresist and then perform etching treatment with an acid such as hydrochloric acid.

<Problems to be Solved by the Invention> Spraying methods and coating methods generally require high processing temperatures, with substrate temperatures often ranging from 400'C to 600C. For this reason, when a transparent electrode is provided on a glass substrate having a color filter using dyes and organic pigments as coloring materials, there is a drawback that the dyes and organic pigments discolor.

Many attempts have been made to use the CVD method using tin oxide, but it has had the disadvantage that only liquids and solids that are easily vaporized can be used as raw materials, which limits the range of raw materials that can be selected.

PVD methods include vacuum evaporation, ion blating, sputter evaporation, and molecular beam crystal growth, but since all of them are film-forming processes in a vacuum, they often require batch processing. This was one of the causes of longer production times.

In addition, since the film-forming process temperature is extremely high, the substrate temperature is 2.
The temperature often rises to 000C or higher, which has the disadvantage that it cannot be used for substrates with weak heat resistance.

In addition to the drawbacks mentioned above, conventional methods for manufacturing transparent electrodes have the drawback that patterning of transparent electrodes is difficult.
When patterning a transparent electrode on a substrate, after forming a transparent conductive thin film on the entire surface using each method, a pattern is formed using a photoresist, and this is used as an etching resist for etching with hydrochloric acid or the like. , steps such as forming a transparent electrode pattern were required.

<Means for solving the problem> When forming a transparent electrode having a predetermined pattern on a substrate, a transparent conductive 4-film sheet in which a transparent conductive thin film is formed on a substrate and a support on which the transparent electrode is formed is used. The surfaces are brought into close contact with each other through an adhesive layer whose adhesive strength changes when irradiated with light, and the adhesive layer is bonded to the adhesive layer in a predetermined pattern by irradiating light through a mask that transmits or blocks light in a predetermined pattern. A transparent electrode is formed by changing the adhesive force with the substrate and leaving a transparent conductive thin film in a predetermined pattern on the substrate when the sheet is peeled off. A transparent electrode is formed on a substrate by a transfer method using a sheet on which a transparent conductive film is formed (hereinafter referred to as a "transfer sheet"). This has two effects. One is that since the transfer sheet can be manufactured in a completely separate process from the process of forming transparent electrodes on the substrate, the time required for the process of forming transparent electrodes on the substrate is significantly shortened. Another is that in order to deposit a transparent conductive thin film on a material other than the intended substrate, transparent electrodes can be formed on substrates that cannot withstand the high temperatures and other conditions required when depositing a transparent conductive thin film. It is.

That is, in a conventional color liquid crystal display device, a thin ITo film was formed by sputtering on a color filter formed by a dyeing method, and a pattern was formed by etching to form a transparent electrode. However, since the heat resistance of the color filter is weak, the film forming temperature of the IT○ thin film must be kept at a low temperature, and as a result, the conductivity of the ITOJ film is often inferior. According to the present invention, by transferring an IT○ thin film formed under sufficient temperature conditions to a heat-resistant support, a transparent film with excellent conductivity can be applied to a substrate on which a color filter with poor heat resistance is formed. Electrodes can be formed.

The support for the transfer sheet may be a film made of polyimide, polyether sulfone, polyester, polycarbonate, polyvinyl alcohol, nylon, silicone resin, fluororesin, etc., a metal film made of thin steel plate, aluminum, stainless steel, glassine paper, paraffin paper, etc. be.

Materials for the transparent conductive thin film include metal oxides such as indium oxide and tin oxide, metals such as gold, silver, copper, palladium, rhodium, and aluminum, polypyrrole, polyacetylene,
There are conductive organic materials such as polyaniline. Methods for manufacturing transparent conductive thin films include spray method, chemical vapor deposition method, vacuum evaporation method, ion blasting method, sputter deposition method, sol-gel method for metals and metal oxides, and vapor phase deposition method for conductive organic materials. Use legal. Further, in order to improve the transferability of the transparent conductive thin film, a release layer may be provided between the support and the transparent conductive thin film. Although the transfer sheet is produced in this manner, the materials and manufacturing method are not limited to those described above.

A method of irradiating light through a mask that transmits or blocks light in a predetermined pattern (hereinafter referred to as a "photomask") and a method of drawing a pattern by scanning a high-intensity minute beam of light are IC techniques. This technology is also used in the manufacture of LSIs and LSIs, and has excellent resolution and dimensional accuracy. Photomasks are made by etching patterns on photographic film, which is a transparent film with a silver salt photosensitive layer, photographic plates, etc., with a silver salt photosensitive layer on glass, exposed and developed, or glass with metal such as chromium vapor-deposited. There are some drawings etc.

Adhesives whose adhesive strength changes when exposed to light include photopolymerizable oligomers such as polyester, unsaturated polyester, polyether, polyurethane, epoxy, and polybutadiene, as well as butanediol, hexanediol,
At least one photopolymerizable monomer of polyacrylate or polymethacrylate of polyhydric alcohols such as trimethylolpropane and pentaerythritol, and benzophenone, benzyl, benzoin alkyl ether, p-tert-butyl-dichloroacetophenone, 2
, 2-dimethoxy-2-phenylacetophenone, a chlorinated acetophenone derivative, a combination of photosensitive substances such as dithiocarbamate, or a photosensitive substance such as a polymer such as polyvinyl chloride, polyvinyl acetate, polyethylene oxide, and an azide compound or diazo compound. There is a combination of

The substrate on which the patterned transparent electrode is to be formed is a known material such as glass, plastic, or a laminate of these materials, and the substrate may include those mentioned in the industrial application field, such as solar cells, An intermediate product having a function such as a color filter used in a liquid crystal display device may be formed.

Depending on the composition of the adhesive layer, the adhesive strength of the adhesive layer changes when exposed to light; in some cases, the adhesive strength increases due to photopolymerization or photocrosslinking reaction, and in other cases, the adhesive force weakens due to photodecomposition reaction. In both cases, the adhesive layer is separated into areas where the transparent conductive thin film has strong adhesion to the substrate and areas where the transfer sheet has strong adhesion to the support, and when the transfer sheet is peeled off, the adhesive layer with the substrate is The transparent conductive thin film in the strong parts remains on the substrate, and the transparent conductive thin film in the parts with strong adhesion to the support is peeled off together with the transfer sheet to form a transparent electrode pattern. In addition, the manner in which the adhesive strength of the adhesive layer changes due to light irradiation was disclosed in Japanese Patent Publication No. 37-189.
79, 38-9663, 39-8436, 43-
22901, 49-10689, 49-39200
and JP-A-48-94503, JP-A-50-46315,
52-9501, or the method described in the specifications of the Japanese Society of Photography, Vol. 41, No. 4, pp. 245 and 250.
You can also refer to the method described on the page.

<Example 1> (Manufacture of transfer sheet) Using a polyimide film as a support, a processed TO'4 film was deposited at 0.001 by sputtering. It was formed on the entire surface with a thickness of 3 μm. The sputtering temperature was 3°0°C. The formed IT○ thin film had a light transmittance of 90% and a surface electrical resistance value of 2Ω/hole.

(Manufacture of photomask) Line 1100 μm, line length 100 mm straight line 200 μm on Fuji Photo Film ■ Lith Film PF-175A
A pattern of 500 lines lined up at a pitch of 500 was exposed using a photoplotter, developed and fixed.

(Manufacture of adhesive) An adhesive was prepared by dissolving 2.5 g of polyvinyl chloride and 1 g of 2,6-di(4-azidobenzal)-4-methylcyclohexanone in 96.5 g of tetrahydrofuran.

(Manufacture of transparent electrode) An acrylic plate was used as a substrate. An adhesive was applied to the surface of the substrate to a thickness of 2 μm and brought into close contact with the ITO thin film surface of the transfer sheet. After the adhesive layer was solidified, a photomask was closely attached to the surface of the substrate opposite to the adhesive surface, and exposed for 20 seconds using a high-pressure mercury lamp. Next, after heat treatment was performed at 80° C. for 3 minutes, the transfer sheet was peeled off, and a transparent electrode having a pattern with good resolution and dimensional accuracy was formed.

<Example 2> (Production of adhesive) 20 g of high viscosity bisphenol type epoxy acrylate,
7 g of pentaerythritol triacrylate and 0.6 g of benzoin isobutyl ether were added to 72 g of dichloromethane.
It was prepared by dissolving 4g of the product.

(Manufacture of transfer sheet) A polyimide film was used as a support, and an IrO2 film with a thickness of 0.3 μm was formed on the entire surface by sputtering. The sputtering temperature was 300°C. The light transmittance of the formed IT○ thin film is 9o%, and the surface electrical resistance value is 2Ω.
/It was a mouth. Next, the previously prepared adhesive was applied to the entire surface of the IT◯ thin film and allowed to air dry. The thickness of the adhesive layer after drying was 1 μm.

(Production of photomask) Draw a straight line of 200 μm at 100 μm and a line length of 1100 rn on Fuji Photo Film ■'s Lith Film PF-175A.
A pattern of 500 lines lined up at a pitch of m was exposed using a photoplotter, developed, and fixed.

(Manufacture of transparent electrode) An acrylic plate was used as a substrate. The adhesive layer of the transfer sheet was brought into close contact with the substrate, and a pressure of 2 kg/Cm2 was applied for 1 minute at room temperature. Next, a photomask was closely attached to the surface of the substrate opposite to the adhesive surface, and exposure was performed for 20 seconds using a high-pressure mercury lamp. Next, when the transfer sheet was peeled off, a transparent electrode having a pattern with good resolution and dimensional accuracy was formed.

<Effects of the Invention> According to the present invention, thin films of metal oxides such as indium oxide and tin oxide, thin films of metals such as gold, silver, copper, palladium, rhodium, aluminum, etc., or polypyrrole, polyacetylene, polyaniline, etc. can be used as materials for transparent electrodes. Since it is possible to use a conductive organic thin film, an electrode with high conductivity can be manufactured. The resolution and dimensional accuracy of the transparent electrode pattern are also excellent because optical methods are used. In addition, the entire process of forming a transparent conductive thin film, applying etching resist, pattern exposure, development, etching, and removing resist in conventional manufacturing methods can be replaced with just a short time of light irradiation and peeling. It is possible to significantly shorten the process and time. Furthermore, because the processing temperature is low, transparent electrodes with excellent conductivity can be formed even on substrates with weak heat resistance, and since no etching treatment is involved, transparent electrodes can be formed even on substrates that are sensitive to acids and solvents. I can do it.

Patent applicant: Miura Printing Co., Ltd.

Claims (3)

[Claims] (1) When forming a transparent electrode having a predetermined pattern on a substrate, the transparent conductive thin film surface of the sheet on which the transparent conductive thin film is formed on the substrate and the support on which the transparent electrode is formed is irradiated with adhesive strength. adheres to each other through a changing adhesive layer,
By irradiating light through a mask that transmits or blocks light in a predetermined pattern, the adhesive force between the adhesive layer and the substrate is changed in accordance with the predetermined pattern, and when the sheet is peeled off, the adhesive force between the adhesive layer and the substrate is changed according to the predetermined pattern. A method for producing a transparent electrode, characterized by leaving a patterned transparent conductive thin film on the substrate. (2) At least one peeling layer is provided between the support described in claim 1 and the transparent conductive thin film to facilitate the transfer of the transparent conductive thin film to the substrate. Method for manufacturing transparent electrodes. (3) A method for producing a transparent electrode, characterized in that the method of irradiating light through a mask as set forth in claim 1 is replaced by a method of drawing a pattern by scanning a small beam of high intensity light.