JPH0737447A - Paste for transparent conductive film pattern formation and transparent conductive film pattern formation - Google Patents

Abstract

PURPOSE:To provide a paste having high productivity since screen printing can be employed and make the spike of the pattern small. CONSTITUTION:A paste for transparent conductive film pattern formation is a paste prepared by mixing a mixture of mesophase carbon small spheres and inorganic powder with a binder and a solvent, and dispersing them in the binder and the solvent. A transparent conductive film pattern is formed using the paste. A fine and highly precise pattern is thus formed on a transparent conductive film. Shielding substances are easily washed out after the transparent conductive film formation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film pattern forming paste and a transparent conductive film pattern forming method using the paste.

[0002]

2. Description of the Related Art Conventionally, there are roughly two methods for forming a pattern on a transparent conductive film. That is, (A): a method of removing the transparent conductive film by reducing or plasma etching after covering the area other than the portion to be removed after forming the transparent conductive film, and (B): forming a pattern of a shield on the substrate. After that, a transparent conductive film is formed,
Then, the transparent conductive film on the shield and the shield are removed by physical or chemical means.
As an example of (A), JP-A-62-136579,
JP-A-62-290900, JP-A-62-206
No. 708 gazette is cited, but all of these manufacturing methods have drawbacks such as complicated steps and high equipment costs due to the use of acids and harmful substances. As an example of the (B) shielding material, Japanese Patent Publication No. 35-1380 proposes a material using a sulfate or a chloride, but it is difficult to obtain fine particles, so that a uniform shielding pattern can be obtained. It is difficult, and there is a drawback that only fine patterns with low dimensional accuracy can be obtained.

Further, Japanese Patent Publication No. 47-24446 proposes a mixture of a pigment and a low melting point glass powder, which is easily fused with a substrate when a transparent conductive film is formed. It is not suitable when a high temperature is required to form the film. JP-A-49-113573 discloses powders of magnesium oxide, aluminum oxide, etc.
Japanese Patent Publication No. 61-43806 proposes to use calcium carbonate alone or a mixture of calcium carbonate and graphite, but these oxides and carbides should be exposed to a strong oxidizing atmosphere at the transparent conductive film forming temperature. Reacts slightly with the glass substrate, and the surface of the glass substrate obtained by removing the shield after film formation is fogged and cannot be used for applications requiring a clean appearance. Since a so-called spike phenomenon in which the edge of the transparent conductive film is lifted easily occurs, it is not preferable when various films are formed on the transparent conductive film.

Further, Japanese Patent Laid-Open No. 2-75536 proposes a device using mesophase carbon microspheres. It is noted that when the paste using the mesophase carbon microspheres is used without being mixed with the inorganic substance, the generation of the spikes is smaller than that when using titanium oxide, aluminum oxide or the like. However, when exposed to a strong oxidizing atmosphere at the transparent conductive film formation temperature, carbon evaporates,
It was revealed that the surface of the glass substrate was slightly fogged. As described above, a satisfactory method for forming a fine transparent conductive film pattern has not been developed so far.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to overcome the above-mentioned drawbacks of the prior art.
It is an object of the present invention to provide a paste capable of forming a fine transparent conductive film pattern and a method of forming a transparent conductive film pattern using the paste.

[0006]

The present invention has been made to solve the above problems, and is characterized in that a mixture of mesophase carbon microspheres and inorganic powder is mixed and dispersed with a binder and a solvent. And a paste for forming a transparent conductive film pattern.

The raw material of the mesophase carbon microspheres used in the present invention is not particularly limited, but as the ash content,
The content is preferably 0.1% or less for the purpose of minimizing the reactivity with the substrate. Regarding the particle size distribution, for the purpose of easy paste formation and good pattern accuracy, the maximum particle size is 20 μm or less and the average particle size (Dse: integrated value indicating the relationship between the particle size and the integrated volume). It is preferable that the particle size distribution curve has a particle size corresponding to 50% of the loading volume) of 10 μm or less.

As the inorganic powder, titanium oxide,
Aluminum oxide, oxides such as zirconium oxide, or silicon nitride, which do not react with the glass substrate even when exposed to a strong oxidizing atmosphere at the transparent conductive film forming temperature, and which do not evaporate, are preferable. Alternatively, two or more kinds can be mixed and used. The average particle size of the inorganic powder is preferably 1 μm or more and 10 μm or less.

The binder is not particularly limited, but cellulose derivatives such as ethyl cellulose and methyl cellulose,
Starch, resins and mixtures thereof are used. As the solvent, an appropriate one can be selected depending on the manufacturing process to be adopted, but in the case of forming a pattern by screen printing, it is of small toxicity, moderate viscosity, evaporation rate,
Benzyl alcohol, pine oil, glycol, ethyl acetyl glycolate, because of having a boiling point,
At least one selected from the group consisting of butyl lactate, benzyl acetate, trimethylpentadiol monoisobutyrate, and water is preferably used.

It is preferable to use a mixing ratio of the mesophase carbon globules and the inorganic powder of from 99: 1 to 25:75 (weight ratio) to clean the appearance of the glass substrate obtained after the film formation and removal of the shielding material. And it is desirable in terms of reducing spikes. The mixture of mesophase carbon microspheres and inorganic powder, the combination of the binder and the solvent can be selected in an appropriate ratio depending on the manufacturing process adopted, but ethyl cellulose as the binder and benzyl alcohol as the solvent are selected, and the pattern is screen-printed. When formed, 40% of the mesophase carbon globules in the paste
To 70% (wt%), and the ratio of ethyl cellulose to the solvent is 1:99 to 20:80 (wt ratio), it is preferable from the viewpoint of workability and printability.

As the transparent conductive film which can be patterned using the paste of the present invention, SnO ₂ , Fb or Sb-doped SnO ₂ , ZnO, Z doped with Al, F or the like is used.
Examples thereof include In ₂ O ₃ doped with nO and Sn, but are not limited thereto. Further, the substrate for forming a transparent conductive film patterned using the paste of the present invention is not particularly limited, and various glass plates, plastic plates and the like can be used, but the paste of the present invention is particularly preferably used for glass plates. it can.

[0012]

In the present invention, when the paste using the mixture of the mesophase carbon microspheres and the inorganic powder is used, the generation of the spikes is substantially eliminated, and the substrate surface obtained by removing the shield after forming the conductive film. The reason why it shows a beautiful appearance without clouding is that the shield formed by the mixture has low wettability with the substrate such as glass and the conductive film, and has poor reactivity, so that high-temperature treatment for forming the conductive film is performed. It is thought that this is also due to the stability in.
As for the shielding property of the mixture, the higher the content ratio of the inorganic powder is,
Further, the peelability from the glass substrate is more excellent as the carbon content ratio increases.

[0013]

【Example】

Example 1 3 parts by weight of ethyl cellulose and 52 parts by weight of benzyl alcohol were thoroughly mixed, and 30 parts by weight of mesophase carbon microspheres (average particle size (Dse) of 6 μm) and titanium oxide powder (average particle size of 1 μm) were added to this solution. Using a paste obtained by adding parts by weight and kneading well, on a glass substrate,
A pattern was formed by screen printing so that the thickness after drying was about 20 μm. This was dried at 200 ° C. for 10 minutes, and then SiH ₄ and O ₂ gas were sprayed at a temperature of 550 ° C. to form a SiO ₂ film (film thickness of about 0.05 μm), and subsequently, a gaseous state was obtained at a temperature of 560 ° C. SnCl ₄ and H ₂ O are sprayed to form a tin oxide film (film thickness of about 0.15 μm)
Was formed. The shielding material flowed down only by washing the substrate thus obtained with water, and the traces of the flow-out were colorless and transparent as before the film formation. The electric resistance measured on both sides of the pattern having a width of 1 mm was 2 MΩ or more, and the spike measured by a stylus type film thickness meter was about 0.1 μm.

Example 2 2 parts by weight of ethyl cellulose and 33 parts by weight of benzyl alcohol were mixed well, and 25 parts by weight of mesophase carbon microspheres (average particle size (Dse) of 6 μm) were added to this solution.
On a glass substrate, using a paste obtained by adding 40 parts by weight of titanium oxide powder (average particle size 1 μm) and thoroughly kneading,
A pattern was formed by screen printing so that the thickness after drying was about 25 μm. This was dried at 200 ° C. for 10 minutes and then sprayed with SiH ₄ and O ₂ gas at 550 ° C. to form a SiO ₂ film (film thickness of about 0.05 μm). Then, at 450 ° C., zinc acetate was mixed with isopropyl alcohol and water. The diluted solution is sprayed and the zinc oxide film (film thickness about 0.2
μm) was formed. When the substrate thus obtained was washed with water, the shield flowed off, and the traces of the flow-off were colorless and transparent as before the film formation. The electric resistance measured on both sides of the pattern having a width of 1 mm was 2 MΩ or more. Further, when measured with a stylus type film thickness meter, the spike was about 0.3 μm.

Comparative Example 1 3 parts by weight of ethyl cellulose and 52 parts by weight of benzyl alcohol were thoroughly mixed, and 45 parts by weight of mesophase carbon microspheres (average particle size (Dse) of 6 μm) were added to this solution, followed by thorough kneading. Screen-printed with paste to a thickness of about 20μ after drying by screen printing.
The pattern was formed so as to be m. 200 this board
After drying at 10 ° C for 10 minutes, the same procedure as in Example 1 was performed at 550 ° C.
At that temperature, SiH ₄ and O ₂ gas are blown to form a SiO ₂ film, and then at a temperature of 560 ° C., gaseous SnCl ₂ is formed.
₄ and H ₂ O were sprayed to form a tin oxide film. The shield thus obtained on the substrate could be removed by washing with water, but SEM observation of the place where the shield was present revealed that it was cloudy. In addition, width 1m
It was observed that the electric resistance on both sides of the m pattern was 2 MΩ or more, and the spike height was about 0.4 μm.

Comparative Example 2 2 parts by weight of ethyl cellulose and 33 parts by weight of benzyl alcohol were thoroughly mixed, and 65 parts by weight of titanium oxide having an average particle size of 1 μm was added to this solution and kneaded well. By screen printing on a glass substrate,
A pattern was formed so that the thickness after drying was about 25 μm. After drying this substrate at 200 ° C. for 10 minutes, SiH ₄ and O ₂ were sprayed at a temperature of 550 ° C. in the same manner as in Example 2 to form a SiO ₂ film (film thickness 0.05 μm),
Subsequently, a solution of zinc acetate diluted with isopropyl alcohol and water was sprayed at 450 ° C. to form a zinc oxide film (film thickness of about 0.2 μm). When the substrate thus obtained was washed with water, the shield did not completely flow down and remained in places. The fallen trace was colorless and transparent as in the film formation. The electric resistance on both sides of the pattern having a width of 1 mm was 2 MΩ or more, and the spike was about 1.5 μm when measured with a stylus type film thickness meter.

The above examples and comparative examples are summarized in Table 1.

[0018]

[Table 1]

[0019]

According to the present invention, a lift-off paste for patterning a transparent conductive film uses a mixture of mesophase carbon globules which have no reactivity with a glass substrate and have a low oxidation consumption rate, and an inorganic powder. , A fine and highly precise pattern can be formed on a transparent conductive film, the conditions for forming a transparent conductive film that requires a high temperature for forming a film such as tin oxide and zinc oxide are not limited, and shielding after the transparent conductive film is formed It has excellent effects that it is easy to wash things off, it is excellent in productivity because it can be used for screen printing, and that spikes are small.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eizu Suzuki 1150, Hazawa-machi, Kanagawa-ku, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory (72) Inventor Kazen Tanabe 1150, Hazawa-machi, Kanagawa-ku, Yokohama Asahi Glass Co., Ltd. Central Research Center

Claims (6)

[Claims] 1. A paste for forming a transparent conductive film pattern, characterized in that a mixture of mesophase carbon microspheres and an inorganic powder is mixed and dispersed with a binder and a solvent. 2. The paste for forming a transparent conductive film pattern according to claim 1, wherein the inorganic powder is at least one selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, and silicon nitride. . 3. The transparent conductive film pattern forming paste according to claim 1, wherein the binder is at least one selected from the group consisting of cellulose derivatives, starch, and resins. 4. The solvent is at least one selected from the group consisting of benzyl alcohol, pine oil, glycol, ethyl acetyl glycolate, butyl lactate, benzyl acetate, trimethylpentadiol monoisobutyrate, and water. The paste for forming a transparent conductive film pattern according to any one of claims 1 to 3, which is characterized in that. 5. A transparent conductive film pattern forming paste prepared by mixing and dispersing a mixture of mesophase carbon microspheres and inorganic powder with a binder and a solvent is applied on a substrate in a desired pattern to form a masking layer. A method for forming a transparent conductive film pattern, which comprises forming a transparent conductive film covering the pattern and then removing the masking layer to form a transparent conductive film pattern. 6. The method for forming a transparent conductive film pattern forming paste according to claim 5, wherein the substrate is glass.