JPH0415748B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for patterning a conductive thin film.

[Prior art]

Conventional materials with conductive thin films formed on substrates include glass plates, films with metal thin films such as gold or aluminum, and metal oxide thin films such as tin oxide or indium oxide. ing. These materials have surface conductivity due to their composition. Furthermore, transparent materials such as metal thin films or metal oxide thin films deposited by vapor deposition are also included, and are known as Nesa glass and transparent conductive films.

Materials with such surface conductivity are used for applications that take advantage of their conductivity, such as flexible circuits, antistatic, electromagnetic shielding, touch panels, and sheet heating elements. In particular, materials with transparent conductivity are used in other applications. It is widely used in the field of electronics for applications requiring transparent conductivity, such as electrodes for liquid crystal displays, electrodes for electroluminescent materials, and electrodes for photoconductive photoreceptors.

For these applications, there are few cases in which materials with surface conductivity are used as is without any post-processing. Depending on the application, the conductive parts may be etched into the required pattern, or a conductive substrate may be tightly attached to the front surface of a CRT, for example. It is often used like this.

Conventionally, the method of etching a conductive thin film formed on a curved substrate is a photoresist method or screen printing method to obtain a desired pattern. A mask is formed by a method and then etched. After that, a method is used to curve the substrate. However, these methods have the following problems.

(1) When a substrate is curved, it is usually curved using a heat forming method. During this process, the patterned conductive thin film portion on the surface of the substrate may be damaged or disconnected due to heating or physical external force. In particular, conductive metal oxide thin films such as indium tin oxide have little elongation and cannot withstand deformation when curved, resulting in wire breakage.

(2) When an etching method such as a photoresist method or silk screen printing method is used, the process is long and complicated, and the etching cost is high.

In addition, after forming the film into a curved surface using the photoresist method or silk screen printing method,
There is also a method of etching, in which a thin film pattern is formed on a curved surface, but in this case, the heating of the substrate during the baking and drying process changes the curvature of the curved substrate, resulting in a thin film pattern with a constant curvature. is not formed.

[Objective of the Invention] [Structure of the Invention] The present inventors have improved the conventional method of etching a complicated conductive thin film such as the photoresist method or the screen printing method, and have developed a method that can be easily etched onto a curved substrate. As a result of intensive study on patterning methods that achieve cost reduction, we applied water-soluble ink or alkali-soluble ink to the parts of the flat substrate that do not require vapor deposition before forming the curved surface, and after forming the substrate into the curved surface, conductive material was applied. Deposit a thin film. After that, they discovered a method of forming a pattern by immersing it in water or alkaline liquid and rubbing it to peel off the ink, thereby completing the present invention.

In the present invention, compared to a patterning method using a normal etching method, it is considered that one step is simplified because the etching and peeling steps are performed simultaneously in this method. The present invention will be explained in detail below.

As the substrate used in the present invention, a plastic film or sheet is suitable because it can be heated and formed into a curved surface without damaging the resist layer.

Therefore, polyester resins such as polyethylene terephthalate, polycarbonate resins, polyimide resins, polyamide resins, polyether sulfon resins, etc., which are commonly used as substrates, may be used. Among these, biaxially stretched polyethylene terephthalate film is the most suitable film because it has excellent dimensional stability, transparency, and mechanical properties. Water-soluble ink or alkali-soluble ink is applied in advance to areas on these plastic films that do not require vapor deposition. Next, this film is heated and formed into a curved surface, and then a conductive thin film is formed. Thereafter, it is immersed in water or an alkaline aqueous solution to peel off the resist and the conductive surface on the resist. The conductive thin film of the present invention has a thickness of 5000 mm formed on a substrate.
A conductive layer with a thickness of Å or less is preferred. If the thickness is 5000 Å or more, the etching method of the present invention takes too much time. Materials for the conductive thin film include various metals such as aluminum, zinc, iron, nickel, tantalum, copper, gold, silver, and cobalt, metal oxides such as tin oxide, indium tin oxide, etc. Other conductive materials include copper iodide and titanium nitride.

As a method of forming a conductive thin film on a substrate,
Any of the vapor deposition method, chemical plating method, electroplating method, chemical etching method, and combination methods thereof are possible; Vapor deposition method is suitable. Vapor deposition methods include vacuum evaporation method and RF
There are also DC sputtering methods, reactive sputtering methods, and ion plating methods. A preferred vapor deposition method is appropriately selected from the viewpoints of the conductivity to be formed, the material of the thin film, the physical properties required of the conductive thin film, and the manufacturing cost.

The conductive thin film may also have an anchor coating layer or a top coating layer, if necessary.

Next, a water-soluble ink or alkali-soluble ink is selected that is applied several microns to several tens of microns, has good adhesion to the polyethylene terephthalate film, and does not crack or peel off even during the curve forming or drying process.

For example, cellulose-based polymers such as ethyl cellulose and synthetic polymers such as water-soluble nylon can be considered. A conductive thin film is formed on the substrate by printing several micrometers to several tens of micrometers of these resists using a brush writing method or a silk screen method.

After the conductive layer is deposited, in the case of water-soluble ink, the ink is rubbed off in water. In the case of an alkali-soluble ink, when the ink is immersed in an alkaline aqueous solution and peeled off by friction, the conductive thin film is peeled off together with the ink and a pattern is formed.

〔Effect of the invention〕

The pattern formed in this way is mainly used as a switching device such as a touch panel, in which two conductive layers, upper and lower, are arranged facing each other. These curved touch panels are manufactured to match the curvature of the CRT and are used as a pointing system for the screen displayed on the CRT as an input device with less misalignment. The present invention has made it possible to create a patterned touch panel with a curved surface.

The present invention will be explained in detail below with reference to Examples.

Example 1 Ethyl cellulose was dissolved in water at 25 wt% to have a viscosity of 500 to 3000 PS to produce an ink for silk screen. Then, using a silk screen plate, 5 to 10 μm of the above-mentioned ink was printed on a biaxially stretched polyester film (thickness: 175 μm) which had been washed with freon, in areas not required for vapor deposition. After printing, dry at 100℃ for 30 minutes, heat and vacuum form the film to a curvature of 600mmR.
It was molded into. After that, the thickness was reduced to 300 by RF sputtering (using Nichiden ANELVA SPF-210H type).
Indium/tin oxide of Å was deposited. Thereafter, the resist surface was immersed in water and lightly rubbed with a cloth to peel it off and form a pattern. The insulation resistance between the patterns was 100MΩ or more when 500V was applied.
This showed that the etching was completed.

Example 2 Commercially available alkali-soluble resist (product name:
NAZDAR product number 226 (manufactured by Yoshikawa Industries) was used as an ink for silk screen. Then, using a silk screen plate, apply the above ink to a commercially available polyester film (125μm) after Freon washing.
1 in Fig. 1 was printed on the thickness). 100℃ after printing,
After drying for 30 minutes, heat mold the film to a curvature of 850mm.
It was molded into R. Then indium tin oxide
RF sputtering (Nichiden Anelva SPF-210H
300Å thick indium
Tin/oxide was deposited. Thereafter, the resist surface was immersed in a 5% KOH solution and rubbed lightly with a cloth to peel it off to form a pattern. Insulation resistance between patterns is 50V
It was shown that etching was completed when the applied voltage was 100 MΩ or more.

Thereafter, conductive paint was printed on a curved surface on all four sides to form electrodes. As a result, we were able to fabricate a burnable curved film electrode suitable for use as a transparent touch input device.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a printed pattern of a resist. 1 is a resist coating section.

Claims (1)

[Claims] 1. A curved surface characterized by printing a water-soluble or alkali-soluble ink on areas that do not require vapor deposition on a flat substrate in advance, then converting it into a curved surface, depositing a conductive thin film on it, and then removing the water-soluble or alkali-soluble ink. Patterning method for vapor deposited films.