JPS6367289B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a conductive paste that can be coated on an insulating substrate such as glass or ceramic and fired at a low temperature of 450°C to 500°C to form a conductive layer with excellent adhesion to the substrate, especially for liquid crystal display devices. The present invention relates to a conductive paste suitable for use. After coating on an insulating substrate such as glass or ceramic,
Conventional conductive pastes for forming conductive layers by firing at low temperatures of 450°C to 500°C are made of metal powders such as silver, gold, platinum, palladium, nickel, copper, etc.
It was made by mixing and dispersing glass frit in an organic vehicle. However, the conventional conductor layer created by applying this type of paste into a predetermined shape onto an insulating substrate such as glass by screen printing etc. and baking it at approximately 500℃ has a low sheet resistance value and excellent conductivity. However, it had poor adhesion to the substrate and lacked reliability. Therefore, a liquid crystal display device manufactured using conventional conductive paste as a wiring material for connection with an external power source has poor reliability. Here, the liquid crystal display device will be briefly explained. FIG. 1 is a cross _- sectional side view of a liquid crystal _display device. It has a structure in which a liquid crystal material 3 is sealed with a glass frit 4 in a gap between insulating substrates 2 and 2a made of sheets of glass or the like. Reference numerals 5 and 5a are connection wiring portions between the transparent electrodes 1 and 1a and the external power source 6, respectively. If the adhesion of the connection wiring parts 5, 5a to the insulating substrates 2, 2a is not good, not only the conductivity of the connection wiring parts 5, 5a will be impaired, but also moisture will enter from the parts with poor adhesion and damage the liquid crystal material. 3 and significantly shorten the life of the display device. Further, the conventional conductive paste contains a glass frit, and when the glass frit is fired at 450°C to 500°C,
Transparent electrodes 1 and 1a made of metal oxide such as In ₂ O ₃
This has the disadvantage that the conductivity is likely to be destroyed due to the electroconductivity being eaten away, resulting in an extremely low manufacturing yield of liquid crystal display devices. The purpose of the present invention is to overcome the above-mentioned conventional drawbacks,
It is an object of the present invention to provide a highly reliable liquid crystal display device by providing a conductive layer having excellent conductivity and good adhesion to an insulating substrate such as glass. A feature of the present invention is that a metal powder such as silver or nickel, an organic indium compound, an organic tin compound, or a mixture thereof, and an organic vehicle are mixed and made into a paste. The conductive layer obtained by applying the paste of the present invention onto an insulating substrate such as glass and then firing at 450° C. to 500° C. had a small sheet resistance value and a high adhesive strength with the substrate. This is an organic indium compound,
Alternatively, it is considered that In ₂ O ₃ or SnO ₂ or a mixture thereof produced by firing the organic tin compound or a mixture thereof acts as an inorganic binder between the metal powder and the insulating substrate material such as glass, improving the adhesion. In preparing the conductive paste of the present invention, first, tetraacetylacetonate indium In
An organic indium compound such as (acac) ₃ , or an organic tin compound such as dimethyltin acetope (CH ₃ )Sn(acac) ₂ , or a mixture thereof is dissolved in an organic solvent, and then a viscous solution such as ethyl cellulose or nitrocellulose is dissolved. Add the agent and mix to form the vehicle. Metal powders such as silver, nickel, platinum, palladium, etc. are added to this and mixed and dispersed to create a conductive paste. As the organic solvent, high-boiling alcohols such as 2-ethylhexanol and benzyl alcohol, high-boiling ethers such as butyl cellosolve and butyl carbitol, and high-boiling esters such as benzyl acetate and dimethyl phthalate can be used. The paste of the present invention contains In ₂ O ₃ or SnO ₂ , which is a composition for transparent electrodes of liquid crystal display devices, and does not contain glass frit. When used as a wiring member, it has excellent adhesion to both the transparent electrode and the substrate, has good conductivity, and does not eat away at the transparent electrode, making it a highly reliable liquid crystal display device.

[Table] From Table 1, the sheet resistance of the resulting conductive layer is lower in the paste prepared using vehicle [B] containing an organic indium compound and an organic tin compound, and the amount of nickel powder added is lower. It can be seen that the sheet resistance value decreases as the number increases. Example 2 A conductive paste was prepared by adding 50 wt % of silver powder or nickel powder as a metal powder to a vehicle having the following composition containing an organic indium compound and an organic tin compound. 2-Ethylhexanol (90-X) 32/80wt% Benzyl alcohol (90-X) 48/80wt% In (acac) ₃ X87/100wt% (CH ₃ ) ₂ Sn (acac) ₂ X13/100wt% Ethyl cellulose N -200 10wt% Here, pastes were created by changing the addition amount (X) of In(acac) ₃ and (CH ₃ ) ₂ Sn(acac) ₂ to X=10, 20, and 30wt%. A conductive layer was formed in the same manner as in Example 1.
Furthermore, for comparison, firing was performed in air and in a nitrogen atmosphere. Table 2 shows the results of measuring the adhesion, ie, coating strength, and sheet resistance (Rs) of the conductive layer formed.

[Table] A pencil-type scratch tester was used to measure the film strength. In Table 2, △ indicates a load of 150g/
Items marked with ^〇 are items with cracks under a load of 400 g/cm ² , and marks with ◎ are items with no cracks under a load of 400 g/cm ² . As can be seen from Table 2, the adhesion to the substrate is better when fired in a nitrogen atmosphere, and when nickel powder is used as the metal powder, the greater the amount added, the better the adhesion is. Furthermore, when silver powder is used as the metal powder, the sheet resistance value (Rs) increases as the amount of organic indium compound and organic tin compound added increases;
On the contrary, it can be seen that it decreases when nickel powder is used.

[Brief explanation of drawings]

FIG. 1 is a sectional side view of a main part of a general liquid crystal display device. 1, 1a: transparent electrode, 2, 2a: insulating substrate,
3: Liquid crystal substance, 4: Glass frit, 5, 5a:
Connection wiring section, 6: External power supply.

Claims (1)

[Claims] 1. A solution obtained by mixing an organic indium compound, an organic tin compound, or a mixture thereof in an organic solvent and dissolving it, a metal powder such as silver or nickel, and a viscous agent. The resulting conductive paste. 2 A step of mixing and dissolving an organic indium compound, an organic tin compound, or a mixture thereof in an organic solvent, and then adding and mixing a viscosity agent to create a vehicle, and adding silver, nickel, etc. to the vehicle. A method for producing a conductive paste, comprising the step of mixing and dispersing metal powder. 3 A conductive paste obtained by mixing an organic indium compound, an organic tin compound, or a mixture thereof in an organic solvent and dissolving it, a metal powder such as silver or nickel, and a viscous agent. A liquid crystal display device characterized in that a connection wiring portion between a transparent electrode and an external power source is formed using the above-mentioned material.